• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1155-1159
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• 1999

Thin film solar cells on a glass/$SnO_2$ substrate with p-SiC/i-Si/n-Si heterojunction structures were fabricated using a plasma-enhanced chemical-vapor deposition system. The photovoltaic properties of the solar cells were examined with varying the gas phase composition, x=$CH_4/\;(SiH_4+CH_4)$, during the deposition of the p-SiC layer. In the range of x=0~0.4, the efficiency of solar cell increased because of the increased band gap of the p-SiC window layer. Further increase in the gas phase composition, however, led to a decrease in the cell efficiency probably due to in the increased composition mismatch at the p-SiC/i-Si layers. As a result, the efficiency of a glass/$SnO_2$/p-SiC/i-SiC/i-Si/n-Si/Ag thin film solar cell with $1cm^2$ area was 8.6% ($V_{oc}$=0.85V, $J_{sc}$=16.42mA/$cm^2$, FF=0.615) under 100mW/$cm^2$ light intensity.

• Polymer(Korea)
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• v.29 no.6
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• pp.588-592
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• 2005

For the purpose of obtaining polycarbonate film which blocks ultra-violet ion beam was irradiated onto the surface of PC film. This method has gotten several advantages compared with the techniques, such as the protection of changes in film thickness and UV blocking material deposited onto a base film. In order to investigate UV blocking PC film, the optical and chemical characteristics, surface morphology and lightfastness were confirmed by UV/Vis, FTIR(ATR) spectroscopy, AFM, and Q-UV fasoess analyses. As a result, it was shown that the modified PC film was able to block almost all of UV region and easily control the degree of UV block. The optical changes in the film were attributed to chemical changes in PC surface by ion beam irradiation. Moreover, we expect that the modified PC film can durably block UV due to no changes in colour and UV transmittance after UV fastness test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1421-1426
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• 2012

Cornering maneuvers with reduced body roll and without comfort loss are important requirements for car manufacturers. An electric active roll control(ARC) system controls the body roll angle by using motor-driven actuators installed at the centers of the front and rear stabilizer bars. Co-simulation using the Matlab/Simulink controller model and the CarSim vehicle model was proposed to evaluate the performance of the ARC control algorithm. To validate the performance of the ARC actuator and system, bench tests and vehicle tests were proposed.

• Journal of Korea Multimedia Society
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• v.13 no.8
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• pp.1142-1153
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• 2010

Conjunctival injection is the initial symptom of various eye diseases such as conjunctivitis, keratitis, or uveitis. The quantification of conjunctival injection may help the diagnosis and follow-up evaluation of various eye diseases. The size of the sclera is an important factor for the quantification of conjunctival injection. However, previous manual segmentation is time-consuming.Automatic segmentation is needed to extract the objective region of interest. This paper proposed a method based on the level set algorithm to segment the sclera from an anterior eye image. The initial model of the level set algorithm is calculated using the Lab color space, k-means algorithm and the geometric information. The level set algorithm was applied to the images in which the valley between the eyeball and skin was enhanced using the hessian analysis. This algorithm was tested with 52 images of the anterior eye segment. Results showed that the proposed method performs better than those with the level set algorithm using an arbitrary circle, or the region growing algorithm with color information. The proposed method for the segmentation of sclera may become an important component for the objective measurement of the conjunctival injection.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.10
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• pp.47-55
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• 1999

In this paper, a new function hazard elimination algorithm is proposed for asynchronous circuit synthesis. In previous approach, function hazard is eliminated by using state graph which is obtained from the state assignment on STG(signal transition graph) representing transition relationship among signals. These algorithms can use conventional hazard removal and synthesis method applied in synchronous system, but it has much computational complexity and takes much time to handle the state graph. Although some hazard elimination algorithm from STG were proposed, it could not reduce the area overhead due to the addition of new signals. The proposed algorithm eliminate function hazard directly on STG and also control the number of minterms and product-term of added signal in order to minimize the area overhead. Experimental results on benchmark data shows that overall circuit area after hazard elimination is decreased about 15% on the average than that of previous method.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.769-772
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• 2008

Pores can become factors of reducing the capacity of concrete by being path of degradation factors and moisture can fill up pores inside of concrete, so evaluating the effect of unidirectional permeability due to moisture on pore structure of concrete structure is very important. Therefore, the change of pore structure in cases of 0%, 40%, 60%, 80% and 90% humidity being maintained on test specimens and in case of Lithium Silicate, which is chemical compound, being coated were evaluated. As a result, the condensation due to moisture could be confirmed since unidirectional permeability was decreased and the density of Pore Structure was improved as the percentage of water content was being increased. And, solution-type Lithium Silicate fills up pores of sizes around 1$\mu$m in the condition of carrying water and improves the density but the range of capacity improvement due to osmosis will be limited according to functional conditions.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.223-224
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• 2007

광기록의 역사는 1980년대초 Sony와 Philips가 공동 개발한 CD (compact disc: 640MB)의 출현으로부터 시작하여 1996년의 DVD (digital versatile disc: 4.7GB)를 거쳐 최근의 BD (Blu-ray disc: >20GB)에까지 이르고 있다. Read-only memory, recordable, rewritable 등 다양한 저장 및 재생방식이 존재하는데, 이는 레이저 조사에 의한 기록매체의 특성변화의 가역성 (reversibility)에 의존하므로 저장 및 재생방식에 따라 저장매체 또한 다르게 된다. 기록용량의 증가는 레이저의 파장이 짧아지고 동시에 사용된 렌즈의 개구수 (NA: Numerical aperture)가 증가함에 따른 빔 spot size의 감소에 기인한다. 회절한계를 극복하여 빔의 spot size를 줄이고자 하는 연구는 현재도 전세계적으로 활발히 이루어지고 있고 이러한 노력의 일환으로 어느 정도의 추가적인 저장용량 증가는 가능할 수 있으나, 2차원 방식으로는 대용량 광정보기록 (수백 GB ${\sim}$ TB급)의 실현은 불가능하다는 것이 일반적인 예상이다. 한편 장기적으로 기존의 2차원 정보기록방식을 대체하고 저장용량을 획기적으로 증가시킬 수 있는 bit-type 3차원 광정보기록의 개념이 1990년을 전.후로 처음으로 제시되었다. 이는 2차원 bit 정보가 수십 내지 수백 개의 다층 (multi-layer) 형태로 기록되는 방식인데, 그동안 산업체의 관심이 상대적으로 높지 않았던 이유는 영화, 음악 등 엔터테인먼트 시장성 확대를 위해 Blu-ray disc나 HD-DVD에 대한 연구개발에 치중해왔기 때문이다. 하지만 최근 급변하는 정보시스템 서비스 환경 속에서 정보유통량이 기하급수적으로 증가하고 있고 개인이 취급하는 정보량도 2010년경에는 수백 GB 단위가 될 것으로 예상되고 있으며 디지털 방송, 네트워크를 기반으로 한 서비스 수요 뿐 만 아니라 전자도서관이나 VOD (Video on Demand) 서비스 사업에 필수적인 수 TB급의 대용량 저장장치에 대한 수요 또한 크게 증가할 것으로 전망된다. 이에 따라 점차 그 물리적 한계에 다다르고 있는 기존의2차원 정보저장방식을 대체하고 저장용량을 획기적으로 증가시킬 수 있는3차원 정보기록(> $10^{13}$ $bits/cm^3$)에 대한 필요성이 대두된다.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.420-428
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• 2018

In this paper, represented uninterruptible power supply (UPS) equipment maintaining constant output voltage, the proposes a photovoltaic system constructed with a step up boosting chopper and single phase pulse width modulation (PWM) voltage source inverter. as power source disconnection, voltage variation and output current variation with load variation. This system is driven by being synchronized voltage fed inverter and AC source, and in the steady state of power source charge battery connected to DC side with solar cell using a Photovoltaic that it was so called constant voltage charge. It can be results of saving electric power, and through a normal operation of energy storage system (ESS), the system operated the LED a calling on signal changes at the airport in an efficient manner. In addition, better output waveform was generated because of PWM method, and it was proved to test by experiment maintained constant output voltage regardless of AC source disconnection, load variation, and voltage variation of AC power source.

• Journal of Preventive Medicine and Public Health
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• v.38 no.1
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• pp.9-15
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• 2005

Objectives : To analyze medical expenses by cancer site and survival time among cancer patients in their last year of life. Method : The study subjects were 45,394 people that had died of cancers in 2002, were registered by the Korea Central Cancer Registry and received National Health Insurance benefit in the last year (360 days) of life. Personal identification data, general characteristics, dates of death and cancer incidence, and site of cancer were collected from the National Statistical Office and the Korea Central Cancer Registry, and merged with the data of the individual medical expenses of the Health Insurance Review Agency. Results : Average monthly cost curves were U-shaped with high costs near the time of diagnosis and death, and lower costs in between. Medical expenses in the last year of life were around 30.3, 16.7, 13.0, and 12.1 million won among leukemia, lymphoma, ovarian cancer, and breast cancer patients, respectively. Digestive organ cancers including stomach, esophagus, liver, pancreas, and colorectal cancers had relatively low medical expenses. Medical expenses in the last year of life were inverse U-shaped with high expenses near one year of survival. Average monthly cost in the 12 months before death among the patients who had survived $10{\sim}15$ years were more than two-fold greater than the cost before diagnosis among those who had survived for less than one year. Conclusions : Leukemia was the most expensive cancer. It is possible that once diagnosed as cancer, medical expenses do not return to the level before diagnosis. Further research will be needed to understand the magnitude and change of the medical expenses among cancer patients with long term follow up data.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.109-109
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• 2016

철을 보호하는 코팅막에 있어서 현재는 우수한 희생방식성을 가지는 아연(Zn)이 많은 분야에서 활용되고 있지만 성능 향상을 위해서는 코팅막의 두께 증가가 필연적이다. 동일한 두께 혹은 그 이하에서 더 나은 내식성을 가지는 코팅막을 개발하는 목적으로 알루미늄(Al)과 마그네슘(Mg)을 이용한 코팅막의 개발을 진행하고 있으며 이 발표에서는 Al과 Mg의 코팅막을 다층으로 제작하여 이전 실험의 Al-Mg 코팅 강판과 비교 하였을 때 어떠한 특성이 나타나는지를 확인하였다. Al-Mg 코팅층은 99.999%의 Al, 99.99%의 Mg target을 사용하여 스퍼터링을 이용하여 냉연강판 위에 코팅하였다. 증발물질과 기판과의 거리는 7cm 이며, 기판은 세척을 실시한 후 클리닝 챔버에 장착하고 ${\sim}10^{-5}Torr$ 까지 진공배기를 실시하였다. 클리닝 챔버가 기본 압력까지 배기되면 아르곤 가스를 주입하고 기판홀더에 -800 V의 직류 전압을 인가하여 약 30분간 글로우 방전 청정을 실시하였다. 기판의 청정이 끝나면 아르곤 가스를 차단하고 코팅 챔버로 시편을 이송 후 코팅층 성분의 구성형태에 따라 Al과 Mg을 코팅하였다. Al-Mg 코팅층은 $5{\mu}m$의 두께를 기준으로 계면의 코팅층이 각각 Al과 Mg이며 다층으로 구성된 코팅층을 제작하였다. 그리고 후속 공정으로 질소 분위기 $400^{\circ}C$에서 10분간 열처리를 하였다. Al-Mg 코팅층을 주사전자현미경(SEM)으로 관찰한 결과, 표면에서는 Al 또는 Mg의 결정성 구조를 보였으며 단면에서는 다층의 경계를 조금이지만 확인할 수 있었으며 글로우방전분광기(GDLS)를 통해 열처리 후에는 층의 구분이 모호해 지는 것을 확인 할 수 있었다. 그리고 XRD를 통하여 열처리 후 Al-Mg 합금상의 생성도 확인하였다. 또한 Al-Mg가 다층으로 코팅된 강판을 염수분무시험을 통해서 내부식 특성을 확인하였다. Al-Mg 코팅 강판의 염수분무시험 결과, 모든 제작된 코팅층에서 열처리 전 보다 열처리 후 3배 이상의 내식성의 향상효과를 확인할 수 있었다. 이러한 결과로부터 열처리에 의한 합금상 생성 그리고 Al-Mg 박막의 미세구조 변화가 강판의 내식성에 영향을 미치고 있다는 것을 확인할 수 있었지만 다층 제작이 미치는 영향에 대해서는 좀 더 연구가 필요한 것으로 판단된다.