月: 2023年2月

What Is a Linux Server?

A Linux server is a server that uses the Linux operating system.

The Linux OS was originally developed in 1991 by a Finnish university student, Linus Torvalds, in a project. Since it was an open-source concept, it has the advantage of a low investment compared to using a Windows OS, which requires a fee, and since there is little virus software that targets the Linux OS, it has a comparative advantage in terms of security.
The OS itself is lighter than Windows, so it can run comfortably even on a slow CPU, but because it is open source, the speed of evolution is rapid. However, CUI (Character-based User Interface) is required for operation, which is a factor that raises the operational hurdle for user adaptation.

Uses of LINUX Servers

LINUX servers are used in a wide range of fields, including the following:

1. Web servers
2. File servers
3. Mail servers
4. Printer servers
5. Proxy servers
6. DNS servers

Principles of Linux Servers

Linux servers can be used as servers to provide a variety of services.
A server is a computer that provides various services to client computers over a network. It responds to client requests provided over the network. A dedicated PC may be assigned to the server, but it is also possible to have both client and server software co-located on a single PC. In this case, it can function as a server or act as a client, depending on the situation. Multiple types of services can be provided on a single server.

Types of Linux Servers

Unlike the Windows OS, the Linux OS is open source, which is a major feature of the Linux OS, and it continues to evolve in a completely different way from Windows. Since the programs are open to the public, anyone can view and improve them and customize them for their own systems. Developers around the world continue to improve Linux, and there are a wide variety of Linux operating systems in existence today. The best known are CentOS, Ubuntu, and Red Hat Linux, but there are also Fedora Core, Vine Linux, and other Linux operating systems.

Other Information About Linux Servers

1. Types of Servers

Not only Linux OSs but also servers offer a wide variety of services. Typical examples include the following:

Web servers: This is a service that holds web pages internally and sends out predetermined pages and data to the client when requested by the client. The client-side exchanges data with the server via a web browser.
FTP Server: A service that uploads and downloads data in response to client requests over a network.
Database: A management service that accesses and stores data held internally in response to requests from other server applications.
Mail Server: Receives e-mails sent from PCs, tablets, smartphones, etc., and delivers them to a designated mail server. On the other hand, the mail server receiving this mail retrieves the delivered mail from the mailbox in which it is stored and receives it. Other servers include file servers, printer servers, DNS servers, SSH servers, and proxy servers.

2. Backup of LINUX Servers

LINUX servers, especially those that are used for commercial purposes and have a high risk of data loss, must be backed up regularly. There are two types of backup methods as follows:

System backup: System backup means backing up everything on the system, including the OS. In the event of hardware failure, the backup image can be easily restored by installing it on new hardware. This can shorten the mean time to restore (MTTR) in the event of a failure.
Data Backup: Data backup is a method of backing up only data. To restore the data in the event of a failure, the OS and software must be installed individually to restore the data, but the time required to retrieve the backup is short. Generally, the method is to acquire system backups at regular intervals, such as one month, and data backups daily. This reduces the cost of the backup itself while shortening the MTTR in the event of a failure.

3. Price of LINUX Servers

Linux OS is provided in the form of open source and is free of charge, but if you need support for commercial use, you need to choose a commercial Linux OS that comes with a fee. The most famous is Red Hat Enterprise Linux OS (RHEL), which requires a fee for use but provides security measures and support. Other well-known commercial Linux OSs include Oracle Enterprise Linux and SUSE Linux Enterprise Server.

What Is a LAN Module?

A LAN module is a critical component enabling devices to connect to a local area network (LAN), either through wired or wireless connections. These modules, which can be integrated into devices or connected via interfaces like USB or PCI, facilitate data exchange and communication over networks, supporting standards such as TCP/IP and encryption protocols for secure wireless communications.

Uses of LAN Modules

LAN modules are integral to a wide array of devices, extending beyond PCs and smartphones to:

• Sensors: Facilitating the transmission of data from various sensors to servers for remote monitoring.
• Home Appliances: Enabling smart home devices to connect to the internet for remote control and access to online services.
• Industrial Equipment: Equipping machinery with the capability to send operational data for analysis, maintenance, and monitoring.

Their versatility makes them foundational to the connectivity of IoT devices devices, empowering almost any networked device.

Principles of LAN Modules

LAN modules operate based on several core principles:

1. Data Transmission: Breaking down data into frames for sending, with conversion into appropriate signals.
2. Data Reception: Converting received signals back into digital data and reconstructing frames.
3. Error Checking: Ensuring data integrity through error detection methods and requesting retransmission if necessary.
4. Flow Control: Managing the data transfer rate to prevent loss and ensure synchronization.

Other Information on LAN Modules

1. Category of LAN Cables

For wired LAN modules, the category of LAN cables used affects transmission speed, with categories ranging from CAT5e to CAT8, supporting speeds up to 40 Gbps. Selection of the appropriate cable category is crucial for maximizing network performance.

2. LAN Modules for the IoT

Modern LAN modules cater to the IoT’s demands with compact sizes and low power consumption, ensuring they fit into various devices and maintain efficiency, especially in battery-powered scenarios.

What Is an IP Radio?

An IP Radio is a press-to-talk (PTT)-based mobile communications service that transmits voice and data in VoIP format over cellular or Wi-Fi radio networks. It is also called an IP transceiver, PoC transceiver, or LTE transceiver.

In addition to IP radios provided by carriers themselves, there are also many companies that lease cell phone lines from carriers and operate IP radio services as MVNOs.

Since no license is required and costs are low, even small companies and individuals can use IP radios. They are used in business fields such as construction sites, warehouses, and the logistics industry.

Recently, IP radios have also been equipped with smartphone integration functions and are used in a wide variety of applications.

Uses of IP Radios

Since IP radios can communicate over a wider area than conventional radios and do not require base station facilities or licenses, they are used as a means of communication for business purposes at event sites, airports, subways, etc. over a large area.

IP radios are also used at fire departments and fire brigades, and at city halls as a means of communication in times of disaster, because they can share information with a large number of people and are easy to connect even in situations where telephone lines are congested.

Principle of IP Radio

IP radio uses VoIP (Voice over IP) to convert voice data into digital signals and transmit them as packet data. The communication network of the cell phone company is used as the transmission channel for the packet data.

Since data is encrypted between the IP radio and the cellular phone base station, secure communication is possible.

Types of IP Radios

There are several types of IP radios, depending on the shape and other factors.

1. Portable Type

Portable radios are compact in size and can be carried in a person’s hand and used while moving around. They are battery-operated and can operate for approximately 12 to 17 hours. They are suitable for use by event staff, traffic guides, security personnel, etc.

2. In-Vehicle Type

In-vehicle types are terminals that are installed in automobiles. Since they uses the car’s power supply, there is no need to worry about recharging the battery. They can be used for long hours and are suitable for use in trucks, cabs, etc.

3. Application Type

By installing an application on a smartphone, the device can be used as an IP radio. Functions such as recording, text-to-speech, and voice reading are provided as functions unique to the application.

Features of IP Radio

IP radios have the following features:

1. Many Available Locations

As long as cell phone signals are within range, radio signals can be received in places that are difficult to reach with ordinary radios, such as in mountain forests, between buildings, and underground. 

2. Group and Individual Communications Are Possible

IP radios have many calling modes and can make individual calls as well as group calls. In group calls, it is possible to talk simultaneously with mobile stations subscribed to a single contract, or to talk with other command stations at the same time. In case of important or emergency calls, calls can be interrupted. 

3. Stable Calls

Since IP radios use the cellular phone system, there is virtually no interference or interruption of calls while moving, which is experienced with other radios. Therefore, stable calls can be made. 

4. Built-in GPS Function

The GPS built into IP radios can be used to determine the location of trucks and cabs. However, some models may not be equipped with this function.

5. Fixed Communication Fee

The communication fee for IP radio is fixed monthly, so there is no increase in the fee no matter how much you use it.

6. Easy to Connect During Disasters

Even in a situation of congestion due to a large number of calls during a disaster, it is relatively easy to connect because of packet communications.

What Is an IoT Gateway?

An IoT (Internet of Things) gateway acts as a critical bridge between IoT devices and the broader network or cloud, facilitating the transfer and translation of data from various sensors into actionable insights. It also serves to enforce security measures and data protocols, ensuring efficient and safe operations within IoT ecosystems.

Uses of IoT Gateways

IoT gateways find applications across multiple sectors, enhancing operational efficiency, safety, and data management:

• Agriculture: Facilitates remote monitoring and management of farm conditions through data collected from soil sensors and machinery.
• Transportation: Enables intelligent transportation systems to process data from road sensors for real-time traffic management.
• Energy Infrastructure: Helps monitor and control power distribution through sensor data analysis in power plants and substations.
• Factories: Supports automation and quality control in manufacturing through the collection and analysis of production line data.

Principle of IoT Gateways

IoT gateways operate on a four-step process to ensure data integrity and seamless communication:

1. Data Reception: Collects data from connected devices via both wireless (e.g., Bluetooth, Wi-Fi) and wired (e.g., RS-232) technologies.
2. Conversion: Translates and possibly filters or aggregates the data into suitable formats and protocols for further processing.
3. Protection: Implements security measures like encryption to safeguard data integrity and privacy.
4. Data Transmission: Forwards the processed data to cloud servers or on-premise data centers for analysis and storage.

Other Information on IoT Gateways

1. IoT Area Network

IoT area networks connect nearby IoT devices, typically within 100 meters, using power-efficient communication standards like Zigbee and Bluetooth. IoT gateways link these local networks to the broader Internet, optimizing infrastructure costs and power consumption.

2. Edge Computing

Edge computing distributes data processing closer to IoT devices, minimizing server-centric system load and optimizing network resources. Modern IoT systems leverage advanced hardware in gateways for pre-processing tasks, reducing reliance on central servers and enhancing system efficiency.

What Is HPLC?

HPLC (High-Performance Liquid Chromatography) is a method for separating and detecting individual compounds in a sample through the interaction between a column and the sample. It is highly effective for measuring and detecting trace components and is widely used in industries such as pharmaceuticals, biochemistry, food, and environmental studies.

Since the peak area of HPLC is proportional to the sample concentration, it is possible to quantify the concentration of components in the sample. The separation behavior of samples in HPLC varies depending on the column and mobile phase, requiring the design of appropriate analysis conditions.

How to Use HPLCs and Their Applications

High Performance Liquid Chromatography (HPLCs) are analytical method that utilize the interaction between a column and a sample to separate each component within a sample. The method is straightforward: analysis can be performed by directly injecting the sample solution or by placing the sample solution in the autosampler for batch processing.

HPLCs are utilized in various industries. In the pharmaceutical field, they are used to analyze trace impurities and active ingredients. In the food, beverage, and environmental sectors, they analyze nutritional ingredients, functional components, additives, and pesticide residues. In biochemistry, HPLCs are employed for analyzing proteins and nucleic acid-related substances.

Principles of HPLCs and Columns Used

HPLCs and gas chromatography (GC) are types of chromatography. This method separates compounds contained in an analyte by passing them through a column, allowing adsorption to the column or other media. The medium through which the sample components flow, such as a solvent in HPLCs or gas in GC, is called the “mobile phase,” while the medium to which the sample adsorbs, like a column, is the “stationary phase.”

The type and strength of interaction between the sample components and the column vary depending on the column type. For example, in an ODS column, an alkyl chain (octadecyl group) is bonded to the column, enabling the sample’s adsorption through hydrophobic interaction. Silica gel columns have silanol groups on the surface that adsorb polar compounds. Other column types include those modified with phenyl groups, cyano groups, and amino groups.

Concentration Calculation Using HPLC Peak Area

The peak area of HPLCs is proportional to the concentration of a sample. However, when using a UV detector, the peak area varies with the absorbance coefficient (ease of light absorption), even if the sample concentration is the same. Therefore, when analyzing concentrations using HPLCs, it is necessary to prepare standard samples for area comparison.

One concentration analysis method is the “external standard method”. This involves preparing multiple standard samples with known concentrations for HPLC analysis and determining the peak areas. Since the concentration of each sample is known, an equation for determining concentration from the area value can be obtained by plotting the area value against the concentration.

The second method is the “internal standard method”. Here, another compound, chemically and physically stable, is added as an internal standard to a standard sample with a known concentration. After addition, HPLC analysis is performed to determine the ratio of the standard sample’s peak area to that of the internal standard. A calibration curve can be obtained using the ratio of the added internal standard amount as the abscissa and the peak area ratio as the ordinate.

HPLC Detectors and Limits of Detection

A variety of instruments serve as HPLC detectors, including ultraviolet-visible (UV-Vis) detectors, fluorescence detectors, and differential refractive index detectors (RID). The detection limits of these detectors vary widely depending on the sample. For instance, the UV-Vis detector has a detection limit of approximately 10 picograms (pg), and the fluorescence detector is 0.1 pg.

The most sensitive is the mass spectrometer (MS), estimated to have a detection sensitivity of 0.01 pg. However, the detection limit depends on the type and concentration of compounds in the sample, the degree of separation, and sometimes derivatization. Optimization of HPLC analysis, including sample pretreatment, is necessary for high-sensitivity detection.

What Is a GPS Sensor?

A GPS sensor is a device used in the Global Positioning System (GPS), a worldwide satellite-based positioning system. GPS operates continuously, providing high-accuracy location measurements for various applications such as car navigation, time synchronization, and geophysical observations.

Uses of GPS Sensors

Initially used in aircraft, ships, and surveying, GPS sensors have found widespread use in today’s information technology era. They are actively incorporated into smartphones, laptops, car navigation systems, digital cameras, smartwatches, and drones. GPS sensors also play a crucial role in precision surveying and measuring crustal deformation to mm or cm levels. Additionally, GPS satellites help synchronize time data measured by international atomic clocks for determining international standard time.

Principles of GPS Sensors

GPS sensors determine their position on Earth by measuring the distance to multiple satellites. The L1 and L2 signals emitted from these satellites are detected by GPS receivers, which calculate the time difference between signal transmission from the satellite and reception on Earth. Since these radio waves travel at the speed of light, the time of travel multiplied by the speed of light gives the distance between the satellite and the GPS sensor on the ground.

Other Information on GPS Sensors

1. Operation of GPS Satellites

GPS satellites transmit L1 and L2 signals at specific times. The ground control monitors the satellites’ time and orbit, managing signal transmission and reception. Most ground control stations are unmanned, except for the main station.

2. Number of GPS Satellites

For accurate positioning, information from at least four GPS satellites is typically used to compensate for the less accurate clocks in GPS receivers compared to the atomic clocks in the satellites.

3. Accuracy of GPS

GPS sensors in smartphones and car navigation systems generally offer an accuracy of several meters. Efforts to enhance accuracy include combining GPS data with WIFI base station distances, electronic compasses, and other technologies. The broader term for satellite-based positioning systems like GPS is GNSS (Global Navigation Satellite System), which includes systems like QZSS (Quasi-Zenith Satellite System).

4. RTK Technology

RTK (Real Time Kinematic) is a method that enhances GPS accuracy by using two receivers—a reference base station and a mobile station—to compensate for positional deviations. This can improve accuracy to a few centimeters, making it promising for use in smartphones and drones. When combined with ICT (information and communication technology), RTK opens up possibilities for new services like smart agriculture, construction, and drone delivery.

5. GPS Transmitters

GPS transmitters calculate location from GPS signals and transmit this information to specific destinations. They can be used for real-time tracking or manual searching, with applications ranging from monitoring the elderly and children to theft prevention for vehicles and personal items and ensuring safety in outdoor activities.

What Is a GNSS Receiver?

A GNSS receiver is a device that receives signals from global navigation satellite systems to determine geographic positions, converting these signals into precise latitude and longitude coordinates. GNSS encompasses various satellite systems including the United States’ GPS, Europe’s Galileo, Russia’s GLONASS, China’s BeiDou, and Japan’s QZSS (Quasi-Zenith Satellite System or MICHIBIKI).

Uses of GNSS Receivers

GNSS receivers are integral to location-based services, offering applications in-car navigation systems, smartphones, drones, public transportation monitoring, safety tracking for vulnerable populations, and construction site management. They also play a crucial role in disaster preparedness by monitoring potential landslide zones.

Principle of GNSS Receivers

GNSS receivers operate based on two main principles: single (independent) positioning and relative positioning, involving calculations from signals of four or more satellites to determine precise locations. While single positioning calculates distance based on signal travel time, relative positioning enhances accuracy through techniques like Differential GPS (DGPS) and interferometry, utilizing multiple receivers to correct common errors.

Other Information on GNSS Receivers

1. Domestically Produced Positioning Satellite MICHIBIKI

Japan’s MICHIBIKI system complements GPS by providing additional coverage and improved accuracy, especially in Asia and Oceania. With its unique orbit designed to maximize visibility over Japan, MICHIBIKI aims to support more stable positioning services.

2. Examples of MICHIBIKI Applications

MICHIBIKI’s enhanced positioning capabilities are being leveraged in various sectors, including automated agricultural machinery, traffic safety, and autonomous driving, road law enforcement, snow removal, and aiding the visually impaired with independent navigation.

What Is an FRP Sheet?

FRP (fiber-reinforced plastics) sheets are composite materials made from a UV-curable resin matrix reinforced with glass fibers. Known for their ease of use, including the ability to be cut, drilled, and painted, these sheets are utilized extensively for structural repairs and enhancements, as well as for waterproofing and protection against environmental elements.

Uses of FRP Sheets

From reinforcing building structures and extending the lifespan of bridges and storage tanks to repairing automobile bumpers and enhancing corrosion resistance in marine environments, FRP sheets offer a versatile solution. Their waterproof, insulating, and corrosion-resistant properties make them ideal for a wide range of applications, including control panels, roofing, sluice gates, and swimming pools.

Principle of FRP Sheets

The core material of FRP sheets is epoxy acrylate or vinyl ester resin, which hardens under UV light. The incorporation of glass fibers enhances their mechanical strength, allowing these sheets to conform to the shapes of the surfaces to which they are applied once cured.

Characteristics of FRP Sheets

FRP sheets are celebrated for their straightforward installation, robustness once cured, and resistance to water, chemicals, and heat. They can be cured with UV light, including sunlight, making them adaptable to various environments. Some products are specifically designed to be environmentally friendly, avoiding VOCs and complying with food safety regulations.

Other Information on FRP Sheets

How to Install FRP Sheets

Installation requires careful preparation of the substrate to ensure cleanliness and the absence of air pockets. Exposure to UV light or sunlight activates the curing process, with typical curing times ranging from 20 minutes under artificial UV to over 35 minutes in sunlight. Conditions such as weather can affect curing, making preliminary tests advisable. Post-installation, it’s important to manage exposure to prevent premature curing and address any potential odor issues from styrene in the resin.

What Is FPGA Development?

FPGA Development is the custom design of an FPGA to develop an IC with the desired functionality.

FPGA stands for “Field Programmable Gate Array” and is an integrated circuit whose functions can be programmed on site. FPGA Development consists of a large array of circuits such as arithmetic units, memory, registers, and simple logic circuits.

Without any modification, it is nothing more than an array of circuits with no functionality, but by combining the circuits inside and designing the logic circuits, the developer can freely provide the functionality he or she desires.

Similar to FPGAs, there are ASICs (Application Specific Integrated Circuits) that can be customized to the user’s wishes. However, these ICs are manufactured after custom functions are designed. In addition to the time-consuming design and development process, the functions cannot be freely changed in the field once the product has been manufactured.

Uses of FPGA Development

FPGA Development is essential for the development of electronic devices and boards, including ICs. FPGA Development is used in the development of electronic devices for telecommunications, automotive, medical devices, consumer electronics, and all other fields.

FPGA Development benefits from the ability to program the necessary functions into FPGAs, actually place them in electronic devices for verification on actual devices, and provide feedback on the results.

Another disadvantage is the higher production cost compared to ASICs. There has been a tendency to use FPGAs during the FPGA Development stage and put ASICs on the final product after the design is finalized. Recently, however, improvements in semiconductor manufacturing technology have led to higher integration and lower cost of FPGAs, and more and more FPGAs are being used in final products.

Principles of FPGA Development

The flow of FPGA Development is basically the same as that of other IC development such as ASICs, except that in ASIC development, the manufacturing department is responsible for the prototyping process, whereas in FPGA Development, the FPGA developer is also responsible for the process of implementing the program on the actual chip, which is equivalent to the ASIC prototype.

The FPGA Development flow includes the following processes:

1. Specification Determination

The “specifications” such as functions to be implemented in the FPGA, interfaces with other components in the system in which the FPGA will be embedded, timing constraints, etc. are compiled, and the FPGA that meets the specifications is pruned.

2. Logic Circuit Design

Logic operations are described using hardware description languages such as VHDL and Verilog-HDL.

3. Functional Verification

Functional simulation is performed to verify that the logic circuit behavior is correct.

4. Compilation

From the HDL description, logic expressions consisting of gates on the FPGA are generated, and the logic expressions are further optimized to generate a netlist. Then, each circuit is placed on the actual FPGA and the wiring between circuits is determined. This series of processes is called compilation.

5. Timing Verification

Based on the placement and routing information, the physical delay time is simulated to confirm that the timing constraints are satisfied.

6. Downloading

The generated circuit data is downloaded to the FPGA. Through this process, the FPGA, which was just an array of gates, is transformed into the circuit desired by the FPGA Development.

7. FPGA Operation Verification

FPGAs are operated to verify that there are no functional defects or performance deficiencies. There are two types of operation verification: one is to set the FPGA on an evaluation board and run an evaluation simulation, and the other is to actually mount the FPGA on a system and operate it. The actual device verification is suitable for FPGAs with large gate sizes because of the short verification time required.

Other Information on FPGA Development

1. Programming Language For FPGA Development

HDL, which is used to write FPGA code, is a low-level language, so it used to be difficult to write code for FPGAs unless you are a hardware engineer who can design circuits. Now, with the use of integrated software platforms, FPGA Development can be done in another programming language without knowledge of HDL.

The platform translates high-level languages into low-level languages to enable FPGA functionality; it is also possible to accelerate FPGAs using pre-trained deep learning models created with the Tensorflow and Pytorch frameworks.

2. Hardware Efficiency

In devices such as ASICs, jumping between programs and memory is a method that uses power for storing and retrieving data and reduces real-time performance; in FPGAs, there is no need to jump between programs and memory, and efficient data storage and retrieval is possible. FPGAs can also offload power-hungry tasks.