• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1795-1799
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• 2013

The corrosion property of aluminum by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt is investigated in liquid and gel electrolytes consisting of ethylene carbonate/propylene carbonate/ethylmethyl carbonate/diethyl carbonate (20:5:55:20, vol %) with vinylene carbonate (2 wt %) and fluoroethylene carbonate (5 wt %) using conductivity measurement, cyclic voltammetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. All corrosion behaviors are attenuated remarkably by using three gel electrolytes containing 3 wt % of hydrophilic and hydrophobic fumed silica. The addition of silica particles contributes to the increase in the ionic conductivity of the electrolyte, indicating temporarily formed physical crosslinking among the silica particles to produce a gel state. Cyclic voltammetry also gives lower anodic current responses at higher potentials for repeating cycles, confirming further corrosion attenuation or electrochemical stability. In addition, the degree of corrosion attenuation can be affected mainly by the electrolytic constituents, not by the hydrophilicity or hydrophobicity of silica particles.

• 대한방사선기술학회지:방사선기술과학
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• 제41권2호
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• pp.135-140
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• 2018

In this study, the dose of antimony shielding sheet was measured and the shielding rates according to the distance between the radioisotopes and the detector was analyzed according to the type of $^{99m}Tc$, $^{18}F$, $^{201}Tl$, $^{131}I$, $^{123}I$ using the antimony shielding sheet. The detector was used with an inspector. Six sheets of 0.25 mmPb were prepared with 20 cm width and length. Measurement results using $^{99m}Tc$, $^{201}Tl$, and $^{123}I$ showed that as the thickness of the sheet became thicker, the farther the distance from the source to the sheet was, the smaller the transmitted dose amount was measured. It was analyzed that a thickness of 1.50 mm or more was required to obtain a shielding rates of 90% or more. In the experiments of $^{18}F$ and $^{131}I$, the dose value was highest when 0.25 mm sheet was used, and the shielding rates was negative, unlike the results of other radioisotopes. Since $^{201}Tl$ are used when using antimony sheet and $^{18}F$ and $^{131}I$ have no shielding effect, it is thought that it is effective to reduce dose by repeating training and simulation training so that work can be done in a short time.

• 한국멀티미디어학회논문지
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• 제15권11호
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• pp.1377-1383
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• 2012

본 연구는 마우스의 입력을 사람의 손동작으로 대체하는 휴먼마우스 시스템에 관한 것이다. 모니터의 해상도가 커지면서 웹카메라와 모니터간의 해상도 차이로 인하여 단순히 웹카메라에서 손의 위치를 인식하여 포인터를 이동시키는 방법으로는 모니터의 모든 범위에 커서를 위치시킬 수가 없다. 따라서, 되돌아오는 동작을 반복하지 않고 마우스의 위치를 모니터의 가장자리까지 원하는 곳으로 편리하게 위치시키는 효과적인 방법을 제안한다. 또한, 다양한 마우스이벤트를 처리하기 위하여 엄지와 검지를 이용한 손가락 동작 인식을 제안하고 인식률을 측정한 결과, 97% 이상으로 그 유효성을 확인하였다.

• 한국항공우주학회지
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• 제45권9호
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• pp.724-733
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• 2017

비정상 비행(Upset) 상황으로 인한 항공기 사고는 유인항공기와 무인항공기 모두에 치명적인 피해를 발생시킨다. 본 논문은 항공기의 비정상 비행상황에 대한 실시간 대처와 추가적인 위험상황을 방지하기 위한 기법을 연구한다. 먼저 확장칼만필터(Extended Kalman Filter) 방법을 이용해 얻게 되는 예측값과 센서를 통해 실제로 얻게 되는 측정값 사이의 차이를 모니터링하여 현재 항공기의 비정상 비행 진입 여부를 판단한다. 또한, 확장칼만필터의 시간 업데이트를 반복 연산하여 얻은 수 초 후의 예측값을 통해 항공기의 상태가 비정상 비행상황으로 진입할 것인지를 예측하여 사전에 판단할 수 있게 된다. 본 연구결과는 차세대 유무인 항공기의 비정상 비행 상태 진입 방지 시스템 구축을 위한 가교 역할을 할 것으로 사료된다.

• 대한방사선기술학회지:방사선기술과학
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• 제42권1호
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• pp.61-66
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• 2019

The purpose of this study was to improve the unstable treatment posture by placing the Carbon fabric blanket on the couch which was used for the patient fixation for the unstable posture from the severe pain caused by the neuromuscular pressure of the spinal metastatic cancer patient and to analyze the dose difference caused by the energy loss of high energy radiation. Using a linear accelerator, a FC-65G was installed at a depth of 5 cm at a solid phantom at 6 MV and 10 MV energies. The SAD was 100 cm, Gantry angle was $0^{\circ}$, a Cotton and Carbon blanket with a thickness of 1 cm on the couch, The blankets were placed on the couch and the dose was measured according to field size. For the dose measurement, and the dose was measured at 100 MU each time, and the mean value was calculated by repeating the measurement three times in order to reduce the error. The results showed that the difference rate in dose between Carbon blanket and Cotton blanket was respectively -0.54% and -0.75% based on the absence of the blanket(Non). Therefore, it is considered that the use of Carbon fabric blanket, which reduces the patient's pain and does not affect the depth dose, may be useful during radiation therapy of the spine metastasis cancer.

• 한국방사선학회논문지
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• 제15권2호
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• pp.125-130
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• 2021

AAPM CT 성능 팬텀에서 CT수 교정 삽입부의 각 핀과 물에 대응하는 유효원자번호 및 물리적 밀도에 대한 CT수에 관한 자료가 거의 없다. 따라서 자료화의 필요성이 제기되었다. 이 연구의 목적은 AAPM CT 성능 팬텀에서 CT수 교정 삽입부의 각 핀 및 물에 대하여 유효원자번호를 산출하고, 산출된 유효원자번호 및 물리적 밀도에 대한 CT수를 측정하여 비교분석하는데 있다. AAPM CT 성능 팬텀의 CT수 교정 삽입부에서 각 핀과 물의 유효원자번호 및 물리적 밀도에 관한 CT수의 자료를 획득하기 위하여, 먼저 각 핀과 물에 대한 유효원자번호를 산출하였다. 그리고 CT스캐너로 CT수 교정 삽입부를 스캔하여 CT슬라이스들을 획득하였다. 중심 CT슬라이스에서 각 핀과 물에 대하여 CT수들을 측정하였다. 결과로서, 유효원자번호에 대한 CT수들은 유효원자번호가 증가할수록 비선형적으로 증가와 감소를 반복하는 양상을 나타내었다. 그리고 물리적 밀도에 대한 CT수들도 물리적 밀도가 증가할수록 비선형적으로 증가와 감소를 반복하는 양상을 나타내었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.100.1-100.1
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• 2011

Electrochemical impedance spectroscopy(EIS) are using widely as a useful technique mainly in the field of electrochemical for the analysis of electrode reactions or characteristics of the composites. The response analysis of the systems technique provides comprehensive informations about the characteristic and structure of complex and internal reaction. The EIS is the method to measure impedance of the measurement target classified by the frequency, it select the equivalent impedance model to give same response from the result and it calculate the parameter. Therefore, the chemical reaction inside the fuel cell is to modeling to electrical impedance. And as repeating the same experiment in each of the operating point, we can get each different parameter. As a result, we can establish the equivalent impedance model in each operating point. Therefore, if we use these models, we can evaluate the fuel cell without the internal design parameter of the fuel cell as required in existing modeling. The EIS is used typically technique for distinguish status of fuel cell called SOH(State Of Health). When the fuel cell is degradation, Efficiency and health of the fuel cell is reduced because internal impedance is increase. As usage of these principles, we can evaluate state of fuel cell through the impedance analysis of fuel cells. In this study, we are presents EIS distinction system and algorithm for residential fuel cell systems. At the time of the fuel cell installation in the fields, the EIS system and proposed algorithm will be able to apply as technique for efficiency and performance evaluation about fuel cell system.

• Journal of Advanced Marine Engineering and Technology
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• 제31권6호
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• pp.744-752
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• 2007

Recently a fuel oil of the diesel engine in the ship is being changed with low quality as the oil price is higher more and more. Therefore the wear and corrosion in all parts of the engine like cylinder liner ring groove of piston crown, spindle and seat ring of exhaust valve are increased with using of heavy oil of low quality In particular the degree of wear and corrosion in between valve spindle and seat ring are more serious compared to the other parts of the engine due to operating in severe environment such as the high temperature of exhaust gas and repeating impact. Thus the repair weld to the valve spindle and seat ring is a unique method to prolong the life of the exhaust valve in an economical point of view In this study. corrosion property of both weld metal zone and base metal was investigated with some electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram and polarization resistance etc. in 5% $H_2SO_4$ solution. in the case of being welded with some welding methods and welding materials to the exhaust valve specimen as the base metal. In all cases. the values of hardness of the weld metal zone were more high than that of the base metal. And their corrosion resistance were also superior to the base metal. The weld metal of A2F(AC SMAW: 2 pass welding with foreign electrode) showed a relatively good results to the corrosion resistance as well as the hardness compared to the ether welding methods and welding materials. Moreover it indicated that hardness of the weld metal by the domestic electrode was considerably high compared to that of the foreign electrode.

• 한국지능시스템학회논문지
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• 제20권2호
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• pp.304-310
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• 2010

현대를 살아가는 현대인들이 경험하는 만성통증 및 디스크는 성인의 80% 이상이 경험하는 흔한 질병이다. 이러한 질환들 중 교통사고, 추락 등 물리적인 충격에 의한 발생율은 10%정도이며 대부분이 습관적으로 부적합한 자세를 취하게 되어 특정 부위에 지속적인 스트레스가 쌓여 발생하게 된다. 이처럼 부적합한 자세가 오랫동안 이어져 질환의 원인이 되는 것을 알면서도 고쳐지지 않는 이유는 지속적인 반복을 통한 습관화로 인하여 부적합한 자세를 바로 인지하지 못함으로써 바르게 교정하지 못하고 지속되어지기 때문이다. 따라서 본 시스템은 자세를 측정할 수 있는 센서들을 사용자에게 부착 후 사용자의 자세에 따른 데이터를 수집하여 정확한 자세를 측정하고 자세추정알고리즘을 이용하여 해당 자세의 적합여부를 추정한다. 사용자가 부적합한 자세를 지속적으로 취할 경우 이를 인지할 수 있도록 한다. 그리고 적합한 자세로 변경하도록 유도하여 부적합한 자세의 습관화를 방지하는데 목적을 두고 있다. 또한 부적합한 자세의 원인을 분석 후 제거하여 적합한 자세를 취하는데 보조자의 기능을 수행 한다. 정확한 측정을 통한 반복적인 인지 학습을 통해 올바른 자세를 습관화 한다면 성장기 어린이와 만성 질환자에게 많은 도움을 줄 것으로 생각 된다.

• Corrosion Science and Technology
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• 제9권6호
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• pp.310-316
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• 2010

Recently a fuel oil of the diesel engine of the marine ship is being changed with heavy oil of low quality as the oil price is higher more and more. Therefore the wear and corrosion in all parts of the engine such as cylinder liner, piston crown, spindle and seat ring of exhaust valves are predominantly increased. In particular the degree of wear and corrosion of piston crown is more seriously compared to the other parts of the engine due to operating in severe environment such as the high temperature of exhaust gas and repeating impact. Thus the repair weldment of the piston crown is a unique method to prolong the its life in a economical point of view. In this case, filler metals having a high corrosion and wear resistance such as stellite 6, Inconel 625 and Inconel 718 are mainly being used for repair welding. However it has been often happened that piston crown on the ship,s job site is being actually inevitably welded with mild filler metals. Therefore in this study, filler metals such as E4301, E4313 and E4316 were welded at SS401 steel as the base metal, and corrosion property of their weld metals in the case of post weld heat treatment or not was investigated with some electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram and polarization resistance etc. in 0.1% $H_2SO_4$ solution. Corrosion resistance of the weld metal of E4301 was better than the other weld metals in the case of no heat treatment, however, its resistance was considerably decreased with post weld heat treatment(annealing:$625^{\circ}C$, 2 hr) compared to other weld metals. The weld metals of E4313 and E4316 showed a relatively good corrosion resistance by post weld heat treatment.