• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.324-330
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• 2016

A magnetic contactor is a switching device widely used for electric circuits. For the operation of magnetic contactors, magnetic coils are essential; these coils create and interrupt the electric circuit. In this paper, the finite element analysis model was developed to reflect the experimental data, and was verified through alteration of the applied voltages and the numbers of turns. Effects of electromagnetic force on the geometrical variations of the facing poles for fixed and moving cores of two magnet coils were investigated. In addition, effects of slope and air gap size between two facing poles on the electromagnetic force were explored through the distribution of the magnetic flux density in the magnetic coils of a push-type solenoid. Through this analysis, the characteristics of the electromagnetic force against the facing poles were explored.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.223-227
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• 2014

This paper presents an improvement method for human body sensing module and management system, specifically focused on the human body detection module with ultrasonic sensors to detect the usage of toilets and the management system to control the state of the toilets of the entire building. The proposed human body sensing module consists of the detection sensor to detect the movement of human body and the contact sensor to detect the position in a certain distance. The management system is configured of the control unit to process the signal transmitted from sensors, opening and closing valves according to the sensing signal, and the short range wireless communication unit to save the operational status data as well as transmit the data at regular intervals.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.67-77
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• 2016

In this paper, we propose an algorithm for open/closed eye detection based on modified Hausdorff distance. The proposed algorithm consists of two parts, face detection and open/closed eye detection parts. To detect faces in an image, MCT (Modified Census Transform) is employed based on characteristics of the local structure which uses relative pixel values in the area with fixed size. Then, the coordinates of eyes are found and open/closed eyes are detected using MHD (Modified Hausdorff Distance) in the detected face region. Firstly, face detection process creates an MCT image in terms of various face images and extract criteria features by PCA(Principle Component Analysis) on offline. After extraction of criteria features, it detects a face region via the process which compares features newly extracted from the input face image and criteria features by using Euclidean distance. Afterward, the process finds out the coordinates of eyes and detects open/closed eye using template matching based on MHD in each eye region. In performance evaluation, the proposed algorithm achieved 94.04% accuracy in average for open/closed eye detection in terms of test video sequences of gray scale with 30FPS/$320{\times}180$ resolution.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.788-792
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• 2007

국내외의 자동차 메이커는 고효율, 저공해 자동차 개발에 집중하고 있으며, 그 방법으로 하이브리드 자동차가 최우선시 되고 있다. 하이브리드 자동차의 밧데리 팩을 구성하는 핵심 부품 중 하나인 고전압 직류 릴레이는 주행 중 엔진 구동력을 보조하는 구동모터에 전기 에너지를 공급하는 밧데리의 출력을 개폐하는 기기이다. 고전압 직류 릴레이의 개폐 동작시 발생하는 소음은 자동차 운전 중 실내로 유입되어 운전자의 승차감을 떨어뜨리는 요인이 되므로 릴레이의 개폐 동작시 발생하는 소음 저감을 위한 연구가 필요하다. 본 연구에서는 폐로(ON) 동작시 발생하는 소음 저감을 위해 소음원인 충격력을 감소시키기 위한 이중 접압스프링 구조를 제안하였으며, 소음 저감 성능평가를 수행하였다. 먼저 정확한 충격해석을 위해 고전압 직류 릴레이의 최소 동작 전압인 5.9V부터 상시 인가 전압인 12V까지 총 6개의 전압레벨에서 릴레이의 전자력을 측정하였으며, 기존 접압스프링 구조와 이중 접압스프링 구조에 관하여 외연적 탄소성 유한요소 프로그램인 LS-DYNA를 사용하여 충격해석을 수행하였다. 고전압 직류 릴레이의 소음원인 가동전극과 고정전극에서 발생하는 일차 충격력과 가동철심과 고정철심에서 발생하는 이차 충격력을 비교, 평가하였다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.05a
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• pp.245-250
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• 1998

각종 전기ㆍ전자기기에서 발생하는 불요 전자파는 노이즈(Noise) 또는 고조파로 불려지고 있는데 이러한 전자파 규제 항목은 크게 두가지(EMI/EMS)로 대분 된다. EMI(Electro magnetic Interference)는 전자파 장해로서 기기 자체에서 발생하는 전자파의 양을 제한하는 것이고 EMS(Electromagnetic Susceptibility)의 경우는 전자파 내성으로서 각종 외부에서 기기 내부로 침입하는 전자기적 에너지에 의하여 기기가 오작동하지 않는 능력을 평가하는 것을 말하며 이 것들을 총칭하여 전자파 적합성(EMC, Electromagnetic Compatibility)라고 정의한다. (중략)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.89-98
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• 2002

Optical current sensor and optical voltage sensor modules were designed and fabricated to improve measurement error and insulation in automatic power distributor By using Faraday effect, optical current sensor with an $\alpha$-iron core was designed and fabricated to minimize current induction of the other phase and was optimized to maintain linearity. Optical voltage sensor was fabricated owing to the pockets effect and adopted spatial electric field type because of small room in an automatic power distributor. To connect a distributor with an external terminal for signal processing, optical multi connector was designed, fabricated and tested for coupling loss and gas leakage. The linearity of optical current sensor for applied current maintains variation of smaller than 2.5% for applied current range from 20A to 700A. The linearity of optical voltage sensor was smaller than 1% for appling voltage from 6.6kV to 19.8kV. Since the measured characteristics are good, these devices can be considered as being applicable in practice.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.393-397
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• 2020

Shunt reactor, a facility for reactive power compensation, is switched several times a day depending on the load pattern. When the circuitbreaker opens the shunt reactor over-voltage is generated by several factors which degrade the insulating performance of internal parts of the circuit-breaker and cause severe voltage stress on the equipment in the power system. Transient phenomenon occurring during the switching of shunt reactor are available in laboratories that verify the performance of the circuit-breaker by simulating the power system. However, it is difficult to measure the transient phenomenon that occurs during actual operation in actual power system due to many limitations. Therefore, this paper deals with the modeling using EMTP to analyze the reignition and current chopping which causes more severe transient recovery voltage in the small inductive current breaking in actual power systems. In addition, this paper analyzes the main phenomenon that cause circuit-breaker failure in opening shunt reactor using EMTP model.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.855-856
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• 2008

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.153-154
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• 2008

변전기기의 주요 절연매질인 절연유 및 $SF_6$ 가스에서 절연불량으로 부분방전이 발생할때 방사되는 전자기파 특성을 측정, 분석 하였다. 부분방전 발생기구로 부유전극을 제작하여 실험하였으며 부분 방전에 의한 전자기파 신호의 특성을 분석한 결과 변압기 주 절연물인 절연유에서 발생하는 부분방전신호가 크고 높은 주파수의 신호가 발생하였고, 가스절연개폐장치 주 절연물인 $SF_6$ 가스에서 발생하는 부분방전신호도 비교적 높은 주파수 신호가 발생하였다. 본 분석결과는 변전소 주요 설비인 변압기 및 가스절연개폐장치에서 발생가능한 절연이상을 진단하기 위한 전자기파를 이용한 부분방전 분석기술 개발에 응용할 예정이다.

• Transactions of The Korea Fluid Power Systems Society
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• v.6 no.4
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• pp.24-32
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• 2009

For a design of on/off solenoid actuator for valve actuating, designer must have the experimental knowledge as well as general electromagnetic formulas to design object. It is possible for theoretical knowledge to do the out-line design, but it is impossible to optimal design without experimental knowledge which only can be achieved through many repeated experiments. In addition, in present on/off type solenoid actuator field, the smaller, lightening, lower consumption power, high response time are effected as the most important design factor. So, experimental knowledge is more needed for optimal design of solenoid actuator. In this study, we derived the governing equations for optimal design of on/off solenoid actuator for valve actuating and developed a design program composed electromagnetic theories and experimental parameter values for inexperienced designers. And we proved the propriety of this program by experiments.