• Journal of Information Technology Applications and Management
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• 제26권6호
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• pp.103-117
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• 2019

Demand for high power motors is rapidly increasing as the 4th industry and convergence technology has recently emerged. In order to produce high-strength permanent magnets, the magnets used for magnetization have been increased from DC 300V in the 1970s to DC 2.5kV in the 2010s, Up to DC 10kV in the 2030s, It is expected that higher voltage will be used to magnetize. However, in the case of a magnetizer using an existing electric signal control device, it is necessary to use a control device with a high-voltage insulation function in case a high voltage used for magnetization is leaked to the control device. If a short circuit accident occurs, the controller must be shut down and serious problems such as excessive repair costs arise. In this study, a control system adopting optical communication method instead of electric signal control method is proposed to prevent leakage currents in high-voltage magnetizer. We design a transmitter(Tx) and a receiver(Rx) device for the optical communication control device and implemented a prototype connecting the optical cable. In order to demonstrate the utility of high-voltage magnetizer using the optical communication control device, we analyzed the initial cost and the yearly cost for the years to analyze the net present value. As a result, In the case of the low-voltage magnetizer, the electric signal control method cost less, As the operating voltage of the magnetizer becomes higher. It is confirmed that it takes less cost when the optical communication control device is used.

• 융합보안논문지
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• 제15권4호
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• pp.3-9
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• 2015

웹 서비스를 가능하게 하는 웹 어플리케이션은 내부 개발자가 보안 의식을 갖고 만든다면 일정 수준 이상의 안전성을 보여준다. 하지만 외주 개발의 경우, 품질의 우수성보다는 요구 사항을 충족하고 요청 받은 기능을 실행시키는데 주안점이 있기 때문에 안전성이 우선되지 못한다. 따라서, 본 논문에서는 소프트웨어에 대한 객관적이고도 독립적인 시각으로의 평가를 가능하게 해주는 소프트웨어 테스트 절차를 보안 중심으로 개선하였다. 제안된 모델은 웹 어플리케이션의 외주 개발 시에도 초기부터 보안을 고려할 수 있게 해주며, 특히 보안 인식이 부족한 상황에서 작성된 프로그램의 수정 소요 발생으로 인한 개발 일정 지연 사태를 미연에 방지할 수 있는 효과가 있음을 확인하였다. 이러한 결과는 자원관리체계를 중심으로 웹 어플리케이션에 대한 소요가 증가하고 있는 국방 분야에서도 엄격한 테스트를 토대로 보안 취약점을 지닌 채 서비스되는 것을 방지할 수 있기에 활용이 가능할 것으로 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1297-1300
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• 2008

A conventional linear accelerator system requires a flat-topped pulse with less than ${\pm}$ 0.5% ripple to meet the beam energy spread requirements and to improve pulse efficiency of RF systems. A pulse transformer is one of main determinants on the output pulse voltage shape. The pulse transformer was investigated and analyzed with the pulse response characteristics using a simplified equivalent circuit model. The damping factor ${\sigma}$ must be >0.86 to limit the overshoot to less than 0.5% during the flat-top phase. The low leakage inductance and distributed capacitance are often limiting factors to obtain a fast rise time. These parameters are largely controlled by the physical geometry and winding configuration of the transformer. A rise time can be improved by reducing the number of turns, but it produces larger pulse droop and requires a larger core size. By tradeoffs among these parameters, the high-voltage pulse transformer with a pulse width of 10 ${\mu}s$, a rise time of 0.84 ${\mu}s$, and a pulse droop of 2.9% has been designed and fabricated to drive a klystron which has an output voltage of 284 kV, 30-MW peak and 60-kW average RF output power. This paper describes design optimization of a high-voltage pulse transformer for high-power pulsed applications. The experimental results were analyzed and compared with the design. The design and optimal tuning parameter of the system was identified using the model simulation.

• BMB Reports
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• 제44권5호
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• pp.298-305
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• 2011

Most intracellular reactive oxygen species (ROS), especially superoxide anion ($O_2^{{\bullet}_-}$) that is converted from oxygen, are overproduced by excessive electron leakage from the mitochondrial respiratory chain. Intracellular oxidative stress that damages cellular components can contribute to lifestyle-related diseases such as diabetes and arteriosclerosis, and age-related diseases such as cancer and neuronal degenerative diseases. We have previously demonstrated that the excessive mitochondrial $O_2^{{\bullet}_-}$ production caused by SDHC mutations (G71E in C. elegans, I71E in Drosophila and V69E in mouse) results in premature death in C. elegans and Drosophila, cancer in mouse embryonic fibroblast cells and infertility in transgenic mice. SDHC is a subunit of mitochondrial complex II. In humans, it has been reported that mutations in SDHB, SDHC or SDHD often result in inherited head and neck paragangliomas (PGLs). Recently, we established Tet-mev-1 conditional transgenic mice using our uniquely developed Tet-On/Off system, which equilibrates transgene expression to endogenous levels. These mice experienced mitochondrial respiratory chain dysfunction that resulted in $O_2^{{\bullet}_-}$ overproduction. The mitochondrial oxidative stress caused excessive apoptosis leading to low birth weight and growth retardation in the neonatal developmental phase in Tet-mev-1 mice. Here, we briefly describe the relationships between mitochondrial $O_2^{{\bullet}_-}$ and aging phenomena in mev-1 animal models

• Applied Science and Convergence Technology
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• 제23권6호
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• pp.309-316
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• 2014

A large particle accelerator requires an ultrahigh vacuum (UHV) system of average pressure under $1{\times}10^{-7}$ Pa for mitigating the impact of beam scattering from the residual gas molecules. The surface inside the beam ducts should be controlled with an extremely low thermal outgassing rate under $1{\times}10^{-9}Pa{\cdot}m^3/(s{\cdot}m^2)$ for the sake of the insufficient pumping speed. To fulfil the requirements, the aluminum alloys were adopted as the materials of the beam ducts for large accelerator that thanks to the good features of higher thermal conductivity, non-radioactivity, non-magnetism, precise machining capability, et al. To put the aluminum into the large accelerator vacuum systems, several key technologies have been developed will be introduced. The concepts contain the precise computer numerical control (CNC) machining process for the large aluminum ducts and parts in pure alcohol and in an oil-free environment, surface cleaning with ozonized water, stringent welding process control manually or automatically to form a large sector of aluminum ducts, ex-situ baking process to reach UHV and sealed for transportation and installation, UHV pumping with the sputtering ion pumps and the non-evaporable getters (NEG), et al. The developed UHV technologies have been applied to the 3 GeV Taiwan Photon Source (TPS) and revealed good results as the expectation. The problems of leakage encountered during the assembling were most associated with the vacuum baking which result in the consequent trouble shootings and more times of baking. Then the installation of the well-sealed UHV systems is recommended.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.462-462
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• 2014

The effect of rear passivation for passivated emitter and rear cell (PERC) using ozone and H2O oxidant of atomic layer deposited (ALD) Al2O3 was studied by post-annealing in N2 and forming gas ambients. Rear surface of PERC solar cell was passivated by Al2O3 grown by ALD with ozone and H2O oxidant. Al2O3 grown by ALD with ozone oxidant has been known to have many advantages, such as lower interface defects, low leakage current density. Its passivation quality is better than Al2O3 with H2O. Al2O3 layer with 10 nm and 20 nm thickness was grown at $150^{\circ}C$ with ozone oxidant and at $250^{\circ}C$ with H2O oxidant. And then each samples were post-annealled at $450^{\circ}C$ in N2 ambients and at $850^{\circ}C$ in forming gas ambients. The passivation quality was investigated by measuring the minority carrier lifetime respectively. We examined atomic layer deposited Al2O3 such as growth rate, film density, thickness, negative fixed charge density at AlOx/Si interface, and reflectance. The influences of process temperature and heat treatment were investigated using Sinton (WCT-120) by Quasi-Steady State Photoconductance (QSSPC) mode. Ozone-based ALD Al2O3 film shows the best carrier lifetime at lower deposition temperature than H2O-based ALD.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.278.1-278.1
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• 2014

Organic materials have been explored as the gate dielectric layers in thin film transistors (TFTs) of backplane devices for flexible display because of their inherent mechanical flexibility. However, those materials possess some disadvantages like low dielectric constant and thermal resistance, which might lead to high power consumption and instability. On the other hand, inorganic gate dielectrics show high dielectric constant despite their brittle property. In order to maintain advantages of both materials, it is essential to develop the alternative materials. In this work, we manufactured nanocomposite gate dielectrics composed of organic material and inorganic nanoparticle and integrated them into organic TFTs. For synthesis of nanocomposite gate dielectrics, polyimide (PI) was explored as the organic materials due to its superior thermal stability. Candidate nanoprticles (NPs) of halfnium oxide, titanium oxide and aluminium oxide were considered. In order to realize NP concentration dependent electrical characteristics, furthermore, we have synthesized the different types of nanocomposite gate dielectrics with varying ratio of each inorganic NPs. To analyze gate dielectric properties like the capacitance, metal-Insulator-metal (MIM) structures were prepared together with organic TFTs. The output and transfer characteristics of organic TFTs were monitored by using the semiconductor parameter analyzer (HP4145B), and capacitance and leakage current of MIM structures were measured by the LCR meter (B1500, Agilent). Effects of mechanical cyclic bending of 200,000 times and thermally heating at $400^{\circ}C$ for 1 hour were investigated to analyze mechanical and thermal stability of nanocomposite gate dielectrics. The results will be discussed in detail.

• 한국재료학회지
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• 제8권11호
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• pp.1067-1073
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• 1998

CO와 $H_2$의 탄소원을 사용한 마이크로파 플라즈마 화학기상증착 방법으로 SOD 구조에 적용될 양질의 다이아몬드 박막을 형성하였고, SOD 구조를 형성하기 위해 diamond/Si(100) 구조 위에 poly-Si 박막을 저압화학기상 증착법으로 제작하였다. CO/$H_2$탄소원의 유량비 증가에 따라 다이아몬드의 결정은 octahedron 구조에서 cubo-octahedron 구조로 바뀌었으며, 결정면은 {111}과 {100}으로 혼합되어 형성되었다. 비정질 carbon과 non-diamond성분이 없는 양질의 다이아몬드 박막은 CO/$H_2$의 유량비가 0.18일 때 형성되었으며, 주 결정상은 (111) 면이었다. diamond/Si(100) 계면은 void가 없는 평활한 계면을 이루었으며, 다이아몬드 박막의 유전상수, 누설전류와 비저항은 각각 $5.31\times10^{-9}A/cm^2$ 그리고 $9\times{10^7}{\Omega}cm$이었다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 춘계학술대회
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• pp.789-790
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• 2013

기존 MOS (Metal-Oxide-Semiconductor) 소자의 게이트 산화막으로 사용된 $Er_2O_3/SiO_2$ 더블레이어 층은 낮은 누설전류와 높은 캐패시턴스를 갖는 장점을 가지고 있다. 본 논문에서는 이 더블레이어 층을 비휘발성 메모리 소자의 전하포획층으로 처음 적용하여 우수한 성능의 메모리 특성을 얻을 수 있었다. 소자를 제작하기 전에 EDISON Nanophysics 시뮬레이션을 통해 낮은 누설 전류값과 높은 캐패시턴스 값을 기준으로 하여 산화막 두께를 최적화하였다. 이 후, 최적화된 조건으로 금속실리사이드 소스/드레인, 10 um/ 10um의 채널 넓이/길이를 갖는 비휘발성 메모리 소자를 제작하였다. 그 결과, 11 V, 50 ms의 프로그램 특성, -11 V, 500 ms의 소거 특성 및 10년의 기억유지 특성, $10^4$의 내구성 특성을 얻을 수 있었다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.366-373
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• 2005

This paper presents two new circuit topologies of the dc busline side active resonant snubber assisted voltage source high frequency link soft switching PWM full-bridge dc-dc power converters acceptable for either utility ac 200V-rms or ac 400V-rms input grid. These high frequency switching dc-dc converters proposed in this paper are composed of a typical voltage source-fed full-bridge PWM inverter, high frequency transformer with center tap, high frequency diode rectifier with inductor input filter and dc busline side series switches with the aid of a dc busline parallel capacitive lossless snubber. All the active switches in the full-bridge arms as well as dc busline snubber can achieve ZCS turn-on and ZVS turn-off transition commutation with the aid of a transformer leakage inductive component and consequently the total switching power losses can be effectively reduced. So that, a high switching frequency operation of IGBTs in the voltage source full bridge inverter can be actually designed more than about 20 kHz. It is confirmed that the more the switching frequency of full-bridge soft switching inverter increases, the more soft switching PWM dc-dc converter with a high frequency transformer link has remarkable advantages for its power conversion efficiency and power density implementations as compared with the conventional hard switching PWM inverter type dc-dc power converter. The effectiveness of these new dc-dc power converter topologies can be proved to be more suitable for low voltage and large current dc-dc power supply as arc welding equipment from a practical point of view.