• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1173_1174
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• 2009

Recently, the influence of electromagnetic environment for low frequency range on human body has been being argued. Light Rail Transit (LRT) System is an urban transit system which has approximately an intermediate transportation capacity between conventional subway and bus. The LRT systems have been applied and being operated in about a hundred lines around the world and many projects that apply the LRT systems in Korea are being proceeded and scheduled. LRT system is operated under the electrical circumstance of high voltage and large current and passengers are exposed in those electrical circumstance. In this paper, EMI/EMC for low frequency range of K-AGT system is measured and analyzed comparing with the international standard.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.481-487
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• 2010

The equivalent circuits intended to analyze the characteristics of IPT systems can be shown in structures similar to those of existing transformers. IPT systems are composed of combinations of the primary and secondary coils based on magnetic coupling, and the performances are determined by the lengths or the degrees of magnetic coupling of current collecting conductors(secondary) and feeding rails (primary) and system performances become the maximum when they are coupled under the optimum condition. To maximize the output currents of the secondary side, the shapes of iron cores and the structures of coils etc should be considered. To this end, three types of IPT system simulation models were selected and they were analyzed using an electromagnetic field analyzing program. To compare the types with each other, the sizes of the IPT systems and the primary side voltages etc were made to be the same. The electromagnetic fields were analyzed while changing the thicknesses of the cores and the lengths of the air gap etc and the results were analyzed in order to derive the optimum specifications.

• Journal of the Korean earth science society
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• v.24 no.3
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• pp.160-171
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• 2003

This study was designed to analyze the types of concepts about earth science related to seasonal changes, so as to develop a generative learning model focused on dissolving cognitive conflicts between the aforementioned concepts through debates and using said debates to find out how effectively the model works. There are 100 types of earth science concepts concering seasonal changes, 66 of which are unscientific in nature, including misconceptions. Through a second field trial and a research and development (R&D) process, a test on these concepts was developed, consisting of 14 items. For the experimental group, a four-phase generative learning strategy that reflects the types of earth science concepts and cognitive conflicts between such concepts was developed through pre-analysis and discussion, respectively. On the other hand, a traditional teaching and teaming strategy was used for the control group. A meaningful statistic gap found between the two groups through a covariance analysis, the significance level of which was 0.05. This result may be interpreted to mean that the generative teaming strategy is a possible alternative for correcting misconceptions about scientific concepts of seasonal changes.

• Journal of the Korean Operations Research and Management Science Society
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• v.3 no.1
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• pp.49-54
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• 1978

과거 우리나라 경제의 지속적인 고도성장을 주도해온 공업부문은 중화학공업부문의 확대로 오는 80년대에도 공업부문의 성장은 계속될 것으로 본다. 이에따라 공업용지와 용수의 급격한 증가가 예상되는 반면에 국사의 유한성 특히 경제용지 공업용지 조성가능지역의 제한성으로 공업용지와 공업용수의 공급면에서 많은 문제점이 나타날 것으로 본다. 그러므로 앞으로의 과제는 인구분산, 균형적인 지역개발등 지역개발을 중심으로한 경제개발계획수립이 요청되는 바 본 논문은 특히 공업용지와 공업용수의 종합적 이용을 기하기 위하여 한정된 자원의 합리적 배분을 지역공간적인 차원에서 다루어 보았다. 따라서 본 논문에서도 L.P기법의 수학적이고 이론적인 해석은 생략하고 다만 L.P기법에 의한 지역계획수립에 적용한 실험을 토대로 하여 이 기법의 적용방법에 한하였으며, 앞으로 지역통계 자료의 보완과 더불어 좀더 수증적인 분석이 될 수 있겠끔 발전 보완시키고자 한다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.273-274
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• 2008

Recently, the most wide-area blackout in North America, Canada and Europe had shown us indirectly the importance of Wide-Area Power System Protection and had influence on the direction of domestic electric power industry. After reorganization of the electric power industry in 2001, market incentives controls the power generation, transmission and distribution rather than stability of power grid, and moreover it produce bad results like inefficient facility management and too much competition. In addition, we can easily predict the massive loss of social and economic when the wide-area outage occurs by north direction load flow which is a pending problems of domestic power system and in a changed industry likes hi-tech manufacture and information technology industries. This paper introduces the development of infra systems for prevent wide-area blackout in situations of the power system operations.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.38-38
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• 2008

질화갈륨계 발광다이오드는 차세대 반도체 조명용 및 기타 광전소자 등에의 응용 가능성 때문에 주목을 받고 있다. 본 발표에서는 발광다이오드용 In/ITO 전극이 p-형 질화갈륨과 열처리 후 오믹접촉을 이루는 메커니즘을 설명한다.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.5
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• pp.724-729
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• 2008

Umbilical cord blood has been recently considered an attractive potential alternative as a source of stem cell transplantation to curing diseases such as leukemia, cancers, immune disorders. Normally the stored system of the umbilical cord blood specimen is equipped with a computer-controlled robotic arm that enables the samples to locate the identification places in liquid nitrogen tank at regulated temperature as about $-196^{\circ}C$. As the half of robotic arm is in the air and the rest part is submerged in liquid nitrogen, the temperature of robotic arm varies from ambient to liquid nitrogen temperature. In this study the temperature variation of upper part of arm above tank lid was thermally analysed by using the commercial code of Ansys. The result of analysis was that the upper part of robotic arm was seriously frozen due to heat transfer from liquid nitrogen as low as -$120^{\circ}C$. In order to solve the frost problem of robotic arm, small PTFE tube block as resistance material was introduced into the lower part of tank lid instead of the whole stainless steel(SUS) robotic arm. The results showed that the temperature of robotic arm above the lid was higher enough, and this method would be one of the very effective measure to solve the problem.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.3
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• pp.384-388
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• 2000

본 연구는 cocoa mass를 마이크로파 roasting하여 그 향기성분의 변화를 pyrazine류를 중심으로 살펴보는 한편 상법으로 roasting한 경우와 비교하고자 하였다. 마이크로파 roasting은 110,120,130,140,15$0^{\circ}C$의 온도에서 20분 및 30분 동안 행하였고 상법의 경우는 14$0^{\circ}C$에서 30분간 roasting하였다. Roasting한 시료를 연속수증기증류추출법으로 추출하고 농축한 후 GC와 GC/MS로 향기 성분을 분석하였다. 마이크로파 roasting의 경우 5분만에 14$0^{\circ}C$에 도달한 후 그 온도를 잘 유지하였으나, 상법의 경우 25분이 경과되어서야 14$0^{\circ}C$에 도달되었다. Roasting 한 시료의 향기성분으로 2,6-dimethyl pyrazine, 2,3,5-trimethyl pyrazine, 2,3,5,6-teramethyl pyrazine, 5-methyl fufural, 2-methyl-6-propyl pyrazine 등이 확인되었다. Roasting 온도가 증가함에 따라 dimethyl-, trimethyl-, tetramethyl pyrazine류가 증가하였고, tetramethyl pyrazine은 15$0^{\circ}C$ 20분 roasting의 경우 현저하게 증가하였으나, 30분 동안 roasting한 경우 14$0^{\circ}C$에서 증가하였다가 15$0^{\circ}C$일 때는 감소하였다. 그러나 적정 roasting 지표인 di/tri, di/tetra pyrazine의 비율은 1 이하를 보임으로써 마이크로파 roasting이 cocoa mass의 향기 발현에는 부족한 것으로 나타났다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.12
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• pp.639-644
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• 2015

This study reviews the discharge coefficient for thermal buoyancy natural ventilation through experimentation. We measure the air velocity at the outlet, which is needed to derive the discharge coefficient and to compare with the theoretical value. When a temperature difference exists between the inside and outside of the building, the measured discharge coefficient differs from the theoretical value with a maximum difference of 12%. The size and position of the openings have little effect on the discharge coefficient. For practical application, the theoretical discharge coefficient can be used with little modification.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.353-353
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• 2008

트랜지스터 속도는 현저하게 향상되어지는 반면에 RFICs(RF integrated circuits)는 대용량화, 고속화, 고집적화, 소형화, 고 효율화 온칩(on-chip) 수동소자의 부재에 의해 발전을 이루지 못하였다. 즉, 최근 전자기기의 집적화, 초소형화 됨에 따라 실장 밀도를 높이기 위해 부품의 소형화가 강하게 요구되는 동시에 Radio Frequency(RF)에서 이용가능한 수동소자인 capacitor를 개발하고자 본 논문에서는 손가락 모양(interdigital configuration)을 갖는 RF capacitor를 Ansoft사의 HFSS를 이용하여 이상적인 S-parameter, 정전용랑(capacitance), 손실계수(loss tangent)를 도출하고자 한다. 680um의 $Al_2O_3$ 기판에 BST doped MgO을 30um, Chromium과 gold를 각각 5um로 증착시켰다. 핑거 개수 (n, number), 핑거 길이(1, length), 핑거 간격(g, gap), 핑거 너비(w, width)를 변화 시켜가면서 이상적인 결과 값에 가까운 모양 (interdigital configuration)을 얻을 수 있었다. 핑거 수 3 개 일 때 입력 값에 대하여 손실 없는 출력 값(투과값)을 갖는 $S_{21}$이 1.5GHz에서 6dB이하로 떨어졌으며 핑거 간격이 줄고 핑거 너비가 커지고 핑거길이가 커질수록 높은 캐패시턴스 값을 갖는 것을 확인 할 수 있었다.