• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.5
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• pp.359-365
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• 2022

Air-to-ground missile(AGM), which can be operated by being mounted on the outside of the aircraft, is capable of precision strikes, ensuring high survivability. Helicopter, which is one of the AGM operating platforms, is reported to experience a lightning strike once between 1000 and 20000 flight hours in average. When the lightning strikes the helicopter fuselage, lightning transient signal can be induced to internal and external electronic equipment cables through the skin of the helicopter. If the transient signal exceeding the criteria to electrically initiated device(EID) related to the explosive in the AGM can affect the safety of the helicopter by a warhead explosion, etc. In this paper, we suggest an indirect lightning test method to prove the safety of AGM on helicopter, and present the indirect lightning test results.

• Journal of Korea Multimedia Society
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• v.24 no.12
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• pp.1589-1597
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• 2021

Due to the low output rate and time delay of vehicle's navigation results, the electro-optical tracking system(EOTS) cannot estimate accurate target positions. If an inertial measurement unit(IMU) is additionally mounted into the EOTS and inertial navigation system(INS) is constructed, the high navigation output rate can be obtained. And the time-delay can be compensated by using the augmented Kalman filter. An accurate initial attitude is required in order to have accurate navigation outputs. In this paper, an attitude determination algorithm is proposed using the augmented Kalman filter in order to compensate measurement delay of the EOTS and have accurate initial attitude. The proposed initial attitude determination algorithm consists of an augmented Kalman filter, an INS, and an integrated Kalman filter. The augmented Kalman filter compensates the time-delay of the vehicle's navigation results and the integrated Kalman filter estimates the navigation error of the INS. In order to evaluate performance of the proposed algorithm, vehicle's navigation outputs and IMU measurements were generated using sensors' model-based measurement generator and initial attitude estimation errors of the proposed algorithm and the conventional algorithm without the augmented Kalman filter were compared for the generated measurements. The evaluation results show that the proposed algorithm has better accuracy.

• Journal of the Korea Society for Simulation
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• v.19 no.3
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• pp.45-54
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• 2010

The inherent complexity of semiconductor fabrication processes makes it hard to solve well-known job scheduling problems in analytical ways, which leads us to rely practically on discrete event modeling simulations to learn the effects of changing the system's parameters. Meanwhile, unpredictable disturbances such as machine failures and maintenance diminish the productivity of semiconductor manufacturing processes with fixed scheduling policies; thus, it is necessary to adapt job scheduling policy in a timely manner in reaction to critical environmental changes (disturbances) in order for the fabrication process to perform optimally. This paper proposes an adaptive job control framework for a wafer fabrication process in a control system theoretical approach and implements it based on a DEVS modeling simulation environment. The proposed framework has the advantages in view of the whole systems understanding and flexibility of applying new rules compared to most ad-hoc software approaches in this field. Furthermore, it is flexible enough to incorporate new job scheduling rules into the existing rule set. Experimental results show that this control framework with adaptive rescheduling outperforms fixed job scheduling algorithms.

• Journal of Advanced Navigation Technology
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• v.27 no.2
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• pp.214-220
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• 2023

Because there exist a region in the rotational speed and torque map that the a particular combination of a motor and an ESC (Electronic Speed Control) can maintain its peak efficiency, identifying this region is important for designing an efficient system. Firstly the accuracy of the measurement device is verified using the published propeller measurement data. And then, the combined motor-ESC efficiencies of an individual propeller are measured at a wide range of rotational speeds. With measurements obtained from a large number of different propellers, efficiency contours are obtained. It is shown that there exist a significant difference between the measured combined efficiency and the motor efficiency computed using a simple model. In addition, with the same motor, the combined efficiency can have a meaningful variation depending on the model of the ESC. The efficiency contours derived from this study will be useful for the design and optimization of electric propulsion systems of an aircraft where propulsion efficiency is critical.

• Journal of Practical Engineering Education
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• v.15 no.3
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• pp.549-555
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• 2023

The representative technology of the WWAN wireless communication network used in the Internet of Things is LoRa communication technology, and LoRa communication uses the ISM band. The 920 MHz (920.9 MHz~923.3 MHz) band frequency, which is used as a domestic LoRa frequency, had a problem in performing LoRa network practice in the curriculum using a commercially available LoRa modules that have been used in Europe and the United States because of different frequency band, but a RYLR896 LoRa module was developed that allowed RF frequency to be programmed. With this module, this paper confirmed that the frequency can be set at a specified frequency in Korea using AT commands. In addition, using these RYLR896 LoRa modules, a LoRa network consisting of end nodes and gateways was constructed and practiced to confirm that development equipment capable of practicing the RYLR896 LoRa module and IoT was operating normally.

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.493-500
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• 2023

In this study, we developed an impedance sensor capable of controlling electrode polarization by coating iridium oxide (IrO_x) on the surface of the screen-printed carbon electrode. IrO_x was deposited on the surface of carbon electrodes according to the number of cycles (0~50 cycles) by cyclic voltammetry. Observation of scanning electron microscope images revealed that the size and number of IrO_x particles increased as the number of cycles increased. The changes in impedance responses as a function of the NaCl concentration of the as-obtained sensors were investigated using electrochemical impedance spectroscopy. The sensors manufactured in 50 cycles exhibited the best coefficient of determination and reproducibility, attributed to the well-controlled electrode polarization. We further demonstrated the usefulness of the IrO_x-based sensor as a diagnosis sensor for dry eye syndrome by comparing the results of the commercially available osmometer and our sensor using actual solution samples.

• Annual Conference of KIPS
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• 2007.11a
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• pp.991-994
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• 2007

최근 컴퓨터 기술의 발전과 네트워크의 개방화 그리고 무선 모바일 통신 기술의 비약적인 보급으로 인하여 컴퓨팅 환경을 이루고 있는 각종 장치(PC, 모바일 단말, 저장장치, 네트워크 기기 등)가 다양한 형태의 보안 위협에 노출되어 데이터의 유실, 조작, 유출되어 금전적인 피해를 입거나 프라이버시 침해를 받고 있다. 이러한 문제를 근본적으로 해소하기 위하여 설립된 TCG(Trusted Computing Group)는 세계적인 IT 핵심기업들을 중심으로 구성된 비영리 단체로서 PC 혹은 모바일 기기 등의 단말과 서버 장비 그리고 저장 장치 및 네트워크로 구성된 컴퓨팅 환경에서 보안성 향상 및 데이터의 신뢰성을 제고하기 위하여 TPM(Trusted Platform Module)이라는 반도체 칩을 신뢰의 기반(root of trust)으로 한 신뢰 플랫폼을 제안하고 있다. 한편 SaaS(Software as a Service)는 패키지 형태의 소프트웨어를 네트워크 서비스 형태로 바꾸어 사용량에 비례한 요금제로 과금하는 방식을 채택하고 사용자가 온디맨드로 요청한 서비스를 적시에 제공하는 기술로 최근 전세계적으로 각광을 받고 있다. 이때 다양한 컴퓨팅 환경 안의 사용자에게 높은 신뢰성과 보안성 그리고 연속성을 갖는 SaaS 서비스를 제공하고 데이터의 무결성 및 비밀유지와 정확한 서비스 사용시간을 기록하고 업로드하는 기능들을 제공하는 SaaS 플랫폼은 TPM기반의 신뢰컴퓨팅 기술을 통하여 쉽게 구현될 수 있다. 본 논문에서는 일시적으로 네트워크와 차단된 상태의 PC 혹은 모바일 단말에서도 위의 조건들을 만족하는 SaaS 서비스를 지원하는 신뢰 플랫폼이 가져야 할 기능들에 대하여 분석-도출한 후 그러한 기능들을 제공하는 컴포넌트로 구성된 신뢰형 SaaS 사용자 플랫폼을 설계하였다.

• Journal of IKEEE
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• v.23 no.4
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• pp.1461-1464
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• 2019

In this paper, we propose the development of embedded board for integrated radiation exposure protection fireman's life-saving alarm capable of location tracking and radiation measurement. The proposed techniques consist of signal processing unit, communication unit, power unit, main control unit. Signal processing units apply shielding design, noise reduction technology and electromagnetic wave subtraction technology. The communication unit is designed to communicate using the wifi method. In the main control unit, power consumption is reduced to a minimum, and a high performance system is formed through small, high density and low heat generation. The proposed techniques are equipment operated by exposure to poor conditions, such as disaster and fire sites, so they are designed and manufactured for external appearance considering waterproof and thermal endurance. The proposed techniques were tested by an authorized testing agency to determine the effectiveness of embedded board. The waterproof grade has achieved the IP67 rating, which can maintain stable performance even when flooded with water at the disaster site due to the nature of the fireman's equipment. The operating temperature was measured in the range of -10℃ to 50℃ to cope with a wide range of environmental changes at the disaster site. The battery life was measured to be available 144 hours after a single charge to cope with emergency disasters such as a collapse accident. The maximum communication distance, including the PCB, was measured to operate at 54.2 meters, a range wider than the existing 50 meters, at a straight line with the command-and-control vehicle in the event of a disaster. Therefore, the effectiveness of embedded board for embedded board for integrated radiation exposure protection fireman's life-saving alarm has been demonstrated.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.1
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• pp.16-22
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• 2024

Along with the high interest in electric vehicles and new renewable energy, there is a growing demand to apply lithium-ion batteries in the construction equipment industry. The capacity of heavy construction equipment that performs various tasks at construction sites is rapidly decreasing. Therefore, it is essential to accurately predict the state of batteries such as SOC (State of Charge) and SOH (State of Health). In this paper, the errors between actual electrochemical measurement data and estimated data were compared using the Dual Extended Kalman Filter (DEKF) algorithm that can estimate SOC and SOH at the same time. The prediction of battery charge state was analyzed by measuring OCV at SOC 5% intervals under 0.2C-rate conditions after the battery cell was fully charged, and the degradation state of the battery was predicted after 50 cycles of aging tests under various C-rate (0.2, 0.3, 0.5, 1.0, 1.5C rate) conditions. It was confirmed that the SOC and SOH estimation errors using DEKF tended to increase as the C-rate increased. It was confirmed that the SOC estimation using DEKF showed less than 6% at 0.2, 0.5, and 1C-rate. In addition, it was confirmed that the SOH estimation results showed good performance within the maximum error of 1.0% and 1.3% at 0.2 and 0.3C-rate, respectively. Also, it was confirmed that the estimation error also increased from 1.5% to 2% as the C-rate increased from 0.5 to 1.5C-rate. However, this result shows that all SOH estimation results using DEKF were excellent within about 2%.

• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.143-155
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• 2011

Lately electronic tagging policy for the sexual offenders was introduced in order to reduce and prevent sexual offences. However, most sexual offences against children happening these days are committed by the tagged offenders whose identities have been released. So, for the crime prevention, we need measures with which we could minimize the suffers more promptly and actively. This paper suggests a new system to relieve the sexual abuse related anxiety of the children and solve the problems that electronic bracelet has. Existing bracelets are only worn by serious criminals, and it's only for risk management and positioning, there is no way to protect the children who are the potential victims of sexual abuse and there actually happened some cases. So we suggest also letting the students(children) wear the LBS(Location Based Service) and USN(Ubiquitous Sensor Network) technology based electronic bracelets to monitor and figure out dangerous situations intelligently, so that we could prevent sexual offences against children beforehand, and while a crime is happening, we could judge the situation of the crime intelligently and take swift action to minimize the suffer. And by checking students' attendance and position, guardians could know where their children are in real time and could protect the children from not only sexual offences but also violent crimes against children like kidnapping. The overall system is like follows : RFID Tag for children monitors the approach of offenders. While an offender's RFID tag is approaching, it will transmit the situation and position as the first warning message to the control center and the guardians. When the offender is going far away, it turns to monitoring mode, and if the tag of the child or the offender is taken off or the child and offender stay at one position for 3~5 minutes or longer, then it will consider this as a dangerous situation, then transmit the emergency situations and position as the second warning message to the control center and the guardians, and ask for the dispatch of police to prevent the crime at the initial stage. The RFID module of criminals' electronic bracelets is RFID TAG, and the RFID module for the children is RFID receiver(reader), so wherever the offenders are, if an offender is at a place within 20m from a child, RFID module for children will transmit the situation every certain periods to the control center by the automatic response of the receiver. As for the positioning module, outdoors GPS or mobile communications module(CELL module)is used and UWB, WI-FI based module is used indoors. The sensor is set under the purpose of making it possible to measure the position coordinates even indoors, so that one could send his real time situation and position to the server of central control center. By using the RFID electronic roll book system of educational institutions and safety system installed at home, children's position and situation can be checked. When the child leaves for school, attendance can be checked through the electronic roll book, and when school is over the information is sent to the guardians. And using RFID access control turnstiles installed at the apartment or entrance of the house, the arrival of the children could be checked and the information is transmitted to the guardians. If the student is absent or didn't arrive at home, the information of the child is sent to the central control center from the electronic roll book or access control turnstiles, and look for the position of the child's electronic bracelet using GPS or mobile communications module, then send the information to the guardians and teacher so that they could report to the police immediately if necessary. Central management and control system is built under the purpose of monitoring dangerous situations and guardians' checking. It saves the warning and pattern data to figure out the areas with dangerous situation, and could help introduce crime prevention systems like CCTV with the highest priority. And by DB establishment personal data could be saved, the frequency of first and second warnings made, the terminal ID of the specific child and offender, warning made position, situation (like approaching, taken off of the electronic bracelet, same position for a certain time) and so on could be recorded, and the data is going to be used for preventing crimes. Even though we've already introduced electronic tagging to prevent recurrence of child sexual offences, but the crimes continuously occur. So I suggest this system to prevent crimes beforehand concerning the children's safety. If we make electronic bracelets easy to use and carry, and set the price reasonably so that many children can use, then lots of criminals could be prevented and we can protect the children easily. By preventing criminals before happening, it is going to be a helpful system for our safe life.