• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.10a
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• pp.323-328
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• 2003

전력산업의 초기부터 전기설비의 주변에서 사람의 안전은 중요한 관심사가 되어왔다. 전격사고의 대부분은 충전설비의 고장으로 누전이 되어 대지전위의 상승 또는 충전부와 접촉함으로써 허용치를 초과하는 인체전류의 크기와 통전시간에 의해 사람의 안전에 부정적인 영향을 끼친다. 세계 각 국에서는 전격모델과 관련된 안전기준을 마련하여 전격 위험성 분석 및 평가를 시행하고 있다. 그럼에도 불구하고 국내에서는 전격사고로 인한 사망, 부상 등의 인명피해와 그 재산피해가 증가하고 있다.(중략)

• Electric Engineers Magazine
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• v.254 no.10
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• pp.34-40
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• 2003

the# star city 신축공사는 철골(판매시설), 철근콘크리트(주거시설)가 병행, 시공되고 대지와의 접촉면이 큰 고층 건축물로 각종의 다양한 전기, 전자, 통신설비 기기가 도입되고 있어 문제가 되는 것이 접지의 시공법이다. 건축물에 있어서 뇌보호란 크게 외부 뇌보호와 내부 뇌보호로 나눌 수 있으며 외부 뇌보호는 직격뢰로 부터 건물등을 보호하는 것이고 내부 뇌보호는 낙뢰시 전위상승으로 인한 영향 및 뇌전류의 전자효과를 저감하는 것으로 특히 과전압 내성이 작은 전자기기 등을 대상으로 하는 보호이다.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.187-189
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• 2002

일반적으로 상용주파수에서의 대지는 입력전류의 크기에 따라 일정한 저항체로 다루어 질 수 있으며, 접지도체 임피던스도 무시할 수 있고 접지도체 전체가 등전위로 볼 수 있다. 그러나 써어지 전류 유입시에는 주파수가 수백 MHz 이므로 접지도체 임피던스에 의한 전압강하가 크게 될 뿐 아니라 써어지 전류 유입점의 도체전위가 매우 많이 상승하게 된다. 따라서, 본 논문에서는 운전중인 변전소 안전측면에서 접지임피던스와 보폭 및 접촉전압 등의 위험전압측정을 통한 안전성을 검토하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.6
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• pp.67-76
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• 2005

This paper proposes a compact-sized surface myoelectric sensor for the myoelectric hand prosthesis. To fit the surface myoelectric sensor in the socket for the myoelectric hand prosthesis, the sensor should be a compact size. The surface myoelectric sensor is. composed of a skin interface and a single processing circuit that are mounted on a single package. The skin interface has one reference and two input electrodes, and the reference electrode is located in the center of two input electrodes. In this paper we propose two types of sensors with the circle- and bar-shaped reference electrode, but all input electrodes are the bar-shaped. The metal material of the electrodes is the stainless steel (SUS440) that endures sweat and wet conditions. Considering the conduction velocity and the median frequency of the myoelectric signal, we select the inter-electrode distance (IED) between two input electrodes as 18mm, 20mm, and 22 mm. The signal processing circuit consists of a differential amplifier with a band pass filter, a band rejection filter for rejecting 60Hz power-line noise, amplifiers, and a mean absolute value circuit. We evaluate the proposed sensor from the output characteristics according to the IED and the shape of the reference electrode. From the experimental results we show the surface myoelectric sensor with the 18mm IED and the bar-shaped reference electrode is suitable for the myoelectric hand prosthesis.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.566-566
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• 2013

종래의 흑연 위주 연료전지 분리판에서 최근 고분자 전해질 막 연료전지가 높은 전력, 낮은 작동 온도로 자동차 산업에서 상당한 주목을 받고 있다. 분리판의 기술적 요구사항은 높은 전기 전도도, 높은 내식성, 가스 밀봉성, 경량성, 가공성, 저비용 등이다. 후보 물질로는 전기 전도성을 갖는 질화물계가 고려되고 있다. 기판으로는 스테인레스강이 가장 유력하며 Fe에 첨가된 Ni, Cr이 존재하므로 Cr 또는 CrN를 박막의 형태로 전자빔 증발법, 마그네트론 스퍼터링법으로 고속 증착하려는 시도가 있었다. 본 연구에서는, 스테인리스 강박(0.1 mm 이하)에 보호막으로 CrN을 선택하고 고속, 고품질증착을 위해서 새로운 방법인 스퍼터 승화법을 개발하였다. 박막의 품질을 개선할 수 있는 고밀도 유도 결합 플라즈마 영역 내에 Cr 소스를 직류 바이어스 함으로써 가열 및 스퍼터링이 일어나도록 하였다. 5 mTorr의 Ar 유도 결합 플라즈마를 2.4 MHz, 500 W로 유지하면서 직류 바이어스 전력을 30 W (900 V, 0.02 A) 인가하고, $N_2$의 유량을 0.5, 1.0, 1.5 SCCM로 변화를 주어 반응성 증착 공정의 결과로 얻어지는 CrN 박막의 특성을 분석하였다. N2의 유량이 증가할수록 $Cr_2N$이 감소하고, CrN이 증가하는 것을 확인하였다. 또한 부식성과 접촉저항을 측정하였다. 부식 전위는 N20 SCCM 보다 모두 상승하는 것을 확인하였고, $N_21$ SCCM에서 부식 전류 밀도가 2.097E-6 (at 0.6V) $A/cm^2$로 나타났다. 접촉저항 에서는 시료 당 3군데(top, center, bottom)를 측정하였다. 전기전도도 측면에서 가장 좋은 결과는 $N_21$ SCCM 일 때 $28.8m{\Omega}{\cdot}cm^2$의 접촉저항을 갖는 경우였다. 미국 에너지성의 기준은 부식 전류밀도 1.E-6 $A/cm^2$이하, 접촉 저항 $0.02{\Omega}m^2$이므로 매우 근접한 결과를 보이고 있다.

• Journal of Korea Multimedia Society
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• v.17 no.2
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• pp.124-131
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• 2014

In this paper, we propose the non-contact gesture recognition algorithm using 4- channel electrometer sensor array. ELF(Extremely Low Frequency) EMI and PLN are minimized because ambient electromagnetic noise around sensors has a significant impact on entire data in indoor environments. In this study, we transform AC-type data into DC-type data by applying a 10Hz LPF as well as a maximum buffer value extracting algorithm considering H/W sampling rate. In addition, we minimize the noise with the Kalman filter and extract 2-dimensional movement information by taking difference value between two cross-diagonal deployed sensors. We implemented the DTW gesture recognition algorithm using extracted data and the time delayed information of peak values. Our experiment results show that average correct classification rate is over 95% on five-gesture scenario.

• Tribology and Lubricants
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• v.38 no.3
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• pp.73-83
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• 2022

This paper is concerned with an analysis of a surface edge crack emanated from a sharp contact edge. For a geometrical model, a square wedge is in contact with a half plane whose materials are identical, and a surface perpendicular crack initiated from the contact edge exists in the half plane. To analyze this crack problem, it is necessary to evaluate the stress field on the crack line which are induced by the contact tractions and pseudo-dislocations that simulate the crack, using the Bueckner principle. In this Part I, the stress filed in the half plane due to the contact is re-summarized using an asymptotic analysis method, which has been published before by the author. Further focus is given to the stress field in the half plane due to a pseudo-edge dislocation, which will provide a stress solution due to a crack (i.e. a continuous distribution of edge dislocations) later, using the Burgers vector. Essential result of the present work is the corrective functions which modify the stress field of an infinite domain to apply for the present one which has free surfaces, and thus the infiniteness is no longer preserved. Numerical methods and coordinate normalization are used, which was developed for an edge crack problem, using the Gauss-Jacobi integration formula. The convergence of the corrective functions are investigated here. Features of the corrective functions and their application to a crack problem will be given in Part II.

• Journal of the Korean Electrochemical Society
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• v.3 no.1
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• pp.39-43
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• 2000

The light emitting diode (LED) was fabricated from n-type porous silicon. We investigated both the current-voltage characteristics of the LED with various electrode materials and changes of electroluminescence with applied current density. Also we probed changes in electroluminescence as a function of operation time at a given current. In order to Improve the contact area between the electrode material and porous silicon layer, we deposited indium on porous silicon layer by electroplating and investigated the electric characteristics of the LED and changes of electroluminescence.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.6
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• pp.325-331
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• 2022

Hydrogen embrittlement in metals has been a serious issue with regard to structural safety. In this study, molecular dynamics simulations revealed that the aggregation of hydrogen atoms at the crack tips suppresses the dislocation emission and thus results in cleavage fracture. A series of molecular dynamics simulations were performed considering factors such as the concentration of hydrogen atoms, loading rate, and diffusion coefficient. We investigated the conditions that minimize hydrogen embrittlement. The simulation results were consistent with the experimental results and used to quantify hydrogen embrittlement.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.4
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• pp.347-353
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• 2002

A structure of a glass electrode-type pH sensor for measuring any concentration of $H^+$ in an aqueous solution was embodied with bulk micromachining technology. Two open well structures were formed, and a reference electrode was secured by the Ag/AgCl thin film in the sloped side of the etched structure. A sensitive membrane of an indicator electrode for generating a potential by an exchange reaction to $H^+$ was made with a glass containing Na 20% or more finely so that its thickness might be $100{\mu}m$ or so, and then it was bonded to one pyramidal structure. A liquid junction for a current path was formed by filling an agar in the anisotropically etched part of the Si wafer, which had a size of $50{\mu}m{\times}50{\mu}m$, and then bonded it to the other. After complete fabrication of each part, it was filled with a 2M KCl reference solution and encapsulated the sensor structure with a cold expoxy. The potential value of fabricated pH sensor was about 90mV/pH in the standard pH solutions.