• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.129-129
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• 2011

냉음극 변압기 전원 소스를 이용하여 저진공에서 플라즈마를 발생시키는 시스템을 개발하였다. 또한 이 장치를 이용하여 도핑된 산화막 증착 기술을 연구하였다. 이 때 도핑 전구체는 액체 소스였으며 이를 기화시켜 사용하였다. 특히 p 타입이 도핑된 이산화규소 박막 증착을 상온에서 실시하였다. 공정 압력은 400~1,000 mT였으며, 전압은 약 1,100~2,100 V 범위에서 조절하였다. 증착된 박막은 박막 두께와 홀 측정을 실시하였다. 홀 측정을 위한 인듐 금속 접합을 400 C에서 실시하였다. 결과를 요약하면, 플라즈마 공정 압력이 400에서 1,000 mTorr로 증가함에 따라 박막 증착 속도는 약 240~440 ${\AA}$/min이었다. 또한 증착된 p-SiO2의 벌크 농도는 같은 압력 증가에 따라 약 $1.2{\times}10^{19}$에서 $6.5{\times}10^{18}/cm^3$으로 절반 정도 감소하였다. 그에 따라 도핑된 산화막의 비저항은 $~1.4{\times}10^{-3}$에서 $2.5{\times}10^{-3}{\Omega}{\cdot}cm$로 증가하였다. 홀 이동도는 약 380~400 $cm^2/V{\cdot}s$를 유지하였다. 또한 전압이 1,100 에서 2,100 V로 증가함에 따라 산화막의 증착 속도는 약 330에서 410 ${\AA}$/min으로 증가하였다. 그러나 전압이 증가해도 벌크 농도는 약 8,9~$6.6{\times}10^{18}/cm^3$의 범위였다. 보다 자세한 결과는 발표를 통해 설명할 것이다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.172-174
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• 2011

표면경도와 내마모특성을 가진 질화처리는 다양한 철강재료에 적용되고 있다. 플라즈마를 이용한 질화법은 다른 질화처리법에 비해 처리시간이 짧고 폐수 및 배기가스와 같은 오염물질의 발생이 거의 없어 친환경적이며 낮은 온도에서 처리가 가능하기 때문에 변형 및 금속학적 물성의 변화가 없는 것이 특징이다. 한편 DLC 처리법은 물리화학적 특성이 다이아몬드와 유사하면서도 저온 합성이 가능하고, 표면이 평활하다는 합성기술상의 장점을 가지고 있기 때문에 많은 분야에서의 응용이 연구되고 있는 재료이다. 특히 고경도, 고윤활성 등의 물리적, 화학적, 광학적 특성과 화학적 안정성과 신체적합성 등의 특성으로 인해 기계부품, 공구, 광학기기, 전자부품, 자동차부품과 의료용 기기분야 등에 적용하고 있다. 본 연구에서는 질화처리 및 DLC 처리를 한 챔버내에서 동시처리하여 그 특성을 평가하였다. 이와같이 얻어진 처리물을 Field Emission Scanning Electron Microscope를 이용하여 단면분석을 하였고, 시편의 경도는 나노인덴터로 측정하였다. ball-on-disk 방식의 마모시험기를 이용하여 내마모특성을 관찰하였으며, 접합력을 측정하기 위해 스크래치 테스트를 실시하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.373-373
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• 2012

염료 감응형 태양전지는 기존 Si 기반 PN접합 무기 태양전지에 비해서 경제적이다. 하지만 그 에너지 변환 효율은 아직까지 세계 최고 수준이 10%밖에 도달하지 못하였다. 그래서 다양한 방식의 효율개선 연구가 활발히 진행되고 있는 실정이다. 본 연구에서는 진공원자층증착(ALD)를 이용하여 Core-shell 구조의 $TiO_2$층 위에 아주 얇고 균일한 $Al_2O_3$ (알루미나) 산화막을 입혔다. 이를 통해서 염료감응형 태양전지의 에너지 변환 효율을 향상시켰다. 본 연구에서는 진공원자층증착(ALD)기술을 이용한 $Al_2O_3$ (알루미나) 산화막의 증착조건에 따른 염료감응태양전지의 효율 개선 매커니즘에 대해서 고찰하였다.

• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.76-82
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• 2000

PTC thermistors with multilayer structure were fabricated by internal electrode bonding technique in order to realize low resistance. MLPTC (Multilayer Positive Temperature Coefficient) possess various features, such as small size, low resistivity and large current. We describe the effect of additives on the PTC characteristics, voltage - current characteristics, temperature dependence of resistance and complex impedance spectra as a function of frequency range 100 Hz to 13MHz to determine grain boundary resistance. It was found that MLPTC thermistor has both highly nonlinear effects of temperature dependent resistance and voltage dependent current behaviors, which act as passive element with self-repair mechanisms. Decrease of room temperature resistance with increasing the number of layers was demonstrated to be a grain boundary effect. Switching characteristics of current were caused by heat capacity of PTC thermistor with multilayer structure. Switching times are lengthened by increasing the number of layers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1592-1596
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• 2010

According to the increase of the channel length with fixed width/length, characteristic curves of drain current as a function of gate bias voltage of indium gallium zinc oxide (IGZO) thin-film transistors moved to a positive direction of gate voltage, and field-effect mobility decreased. In case of fixed length and width of channel, field-effect mobility was lower and subthreshold slope was larger when drain bias voltage was higher. Due to large work function of IGZO, band bending at the junction region between IGZO channel and source/drain electrodes was expected to be in opposite direction to that between silicon and metal electrodes; this could explain the above results.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.212-215
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• 2010

Spin polarized tunneling studies were carried out with Al-Ga bilayer as a spin detector, by Meservey-Tedrow technique. The superconductor (SC)/Insulator (I)/Ferromagnet (FM) tunnel junctions were provided by ultra high vacuum molecular beam epitaxy (UHV-MBE) technique. The analysis of interfacial properties in the Al-Ga bilayer was also carried out by Auger electron spectroscopy. It was observed that the superconducting transition temperature and energy gap were raised in comparison with that of bulk Ga and pure ultrathin Al films. Current studies clearly show how one can modify the material properties at the interface just with a few monolayers.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.321-326
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• 2007

The joined-wing is a new concept of the airplane wing. The fore-wing and the aft-wing arc joined together in the joined-wing. The range and loiter are longer than those of a conventional wing. The joined-wing can lead to increased aerodynamic performances and reduction of the structural weight. The structural behavior of the joined-wing has a high geometric nonlinearity according to the external loads. The gust loads are the most critical loading conditions in the structural design of the joined-wing. The nonlinear behavior should be considered in the optimization of the joined-wing. It is well known that conventional nonlinear response optimization is extremely expensive: therefore, the conventional method is almost impossible to use in large scale structures such as the joined-wing. In this research, geometric nonlinear response structural optimization is carried out using equivalent loads. Equivalent loads are the load sets which generate the same response field in linear analysis as that from nonlinear analysis. In the equivalent loads method, the external loads are transformed to the equivalent loads (EL) for linear static analysis, and linear response optimization is carried out based on the EL.

• Journal of the Korean Institute of Gas
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• v.8 no.3 s.24
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• pp.31-36
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• 2004

Electrofusion(EF) joints have been widely used as they are easy to fuse and suitable for high-quality joints for polyethylene(PE) pipes. This paper studies the cause of defects and classifies 5 types of defects. The defect detection technique for electrofusion joints of polyethylene piping is utilized by the ultrasonic phased array technique to obtain ultrasonic images of electrofusion joints. Test sample joints have been designed and fabricated using artificial defects which were made using paper. Finally, we studied the condition of electrofusion in the field and analyzed the main causes of defects. And we classified the defect types as local lack of fusion, sand inclusion, voids or air inclusion, short stab, excess penetration or excess bead.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.1
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• pp.49-52
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• 2002

This study demonstrated the feasibility of tape casting method to fabricate soda borosilicate glass-coated stainless steel electrostatic chucks(ESC) for low temperature semiconductor processes. Glass coating on the stainless steel substrate was 125 $\mu\textrm{m}$ thick. The adhesion of glass coating was found to be excellent such that it was able to withstand temperature cycling to over $300^{\circ}C$ without cracking and delamination. The electrostatic clamping pressure generally followed the theoretical voltage-squared curve except at elevated temperatures and high applied voltages. The deviations at elevated temperatures and high applied voltages are due to increased leakage current as the electrical resistivity of glass coating drops.

• Food Science and Preservation
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• v.10 no.2
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• pp.230-235
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• 2003

Mayonnaise has probability of fatness and adult disease because main components of it contain high calorie. We prepared dietary mayonnaise used for corn starch paste. And also, dietary mayonnaise with hot taste was manufactured by using both O.R.capsicum and O.R.paprika. It was observed that the calorie of general mayonnaise was 748 Kcal and the calorie of dietary mayonnaise used for starch was 237∼240 Kcal. The dietary effect was certified by animal experiment.