• Journal of Astronomy and Space Sciences
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• 제27권4호
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• pp.329-335
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• 2010

We investigate the sources of the variation of the high-latitude thermospheric neutral mass density depending on the interplanetary magnetic field (IMF) conditions. For this purpose, we have carried out the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEGCM) simulations for various IMF conditions under summer condition in the southern hemisphere. The NCAR-TIEGCM is combined with a new empirical model that provides a forcing to the thermosphere in high latitudes. The difference of the high-latitude thermospheric neutral mass density (subtraction of the values for zero IMF condition from the values for non-zero IMF conditions) shows a dependence on the IMF condition: For negative $B_y$ condition, there are significantly enhanced difference densities in the dusk sector and around midnight. Under the positive-$B_y$ condition, there is a decrease in the early morning hours including the dawn side poleward of $-70^{\circ}$. For negative $B_z$, the difference of the thermospheric densities shows a strong enhancement in the cusp region and around midnight, but decreases in the dawn sector. In the dusk sector, those values are relatively larger than those in the dawn sector. The density difference under positive-$B_z$ condition shows decreases generally. The density difference is more significant under negative-$B_z$ condition than under positive-$B_z$ condition. The dependence of the density difference on the IMF conditions in high latitudes, especially, in the dawn and dusk sectors can be explained by the effect of thermospheric winds that are associated with the ionospheric convection and vary following the direction of the IMF. In auroral and cusp regions, heating of thermosphere by ionospheric currents and/or auroral particle precipitation can be also the source of the dependence of the density difference on the IMF conditions.

• 한국산학기술학회논문지
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• 제14권12호
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• pp.6053-6059
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• 2013

히트 펌프는 지열이나 태양열 등의 신재생 에너지를 이용하거나 기타 폐열을 재활용하여 기존의 전기 히팅 난방 시스템들보다 에너지 소비율을 낮출 수 있다는 장점으로 인해 그린 에너지 시스템으로써 주목을 받아 왔다. 고효율 히트펌프 시스템 설계를 위한 연구는 오랫동안 지속되어 왔지만, 각각의 구성요소가 유기적이며, 변화에 유연한 해석모델은 존재하지 않는다. 따라서 본 연구에서는 공기 열 원식 히트 펌프를 AMESim Software를 이용해 구성하였다. 독자적으로 개발한 스크롤 압축기 해석 모델을 히트펌프 시스템에 조합함으로써 효율 향상 방안을 모색하였으며, 실험 데이터를 이용하여 개발한 해석모델을 검증하였다. 실험 데이터와 개발한 해석 모델을 이용하여 예측된 데이터를 비교한 결과 최대 오차가 10% 이내로 두 데이터가 잘 일치하였다. 본 연구에서 개발한 히트펌프 해석모델은 향후 시제품을 개발하고 효율 향상을 위한 연구 등에 유용하게 사용될 것으로 사료된다.

• 한국콘텐츠학회논문지
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• 제18권10호
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• pp.425-430
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• 2018

전기자동차 배터리 시스템은 낮은 온도에서 배터리 출력과 수명이 감소하는 문제가 발생한다. 상온 유지를 목적으로 Positive Temperature Coefficient(PTC) 히터가 사용되고 있다. 하지만 PTC 히터는 복잡한 절연구조로 인해 중량이 크다. 중량이 클수록 전기자동차의 연비가 감소한다. 반면에 인덕션 히터는 단순한 절연 구조로 중량 저감에 효과적이며 빠른 온도 상승 특성을 가지고 있다. 따라서 전기자동차용 히터는 인덕션 히터가 적합하다. 인덕션 히터는 LC공진 회로로 구성된다. 정전용량이 클수록 가격과 중량이 상승하기 때문에 인덕턴스를 높여 정전용량을 감소시켜야한다. 또한 인덕션 히터의 주 발열원은 철손이다. 따라서 전자기장 설계 관점에서 인덕턴스 및 철손의 최적화가 중요하다. 본 논문에서는 인덕션 히터 구조 변경에 따른 인덕턴스 및 철손을 다구찌 기법과 유한요소법(FEM) 시뮬레이션을 통해 분석하고 최적화 설계하였다.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2001년도 정기총회 특별강연 및 춘계학술연구발표회(2)
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• pp.85-91
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• 2001

This paper provides a case study of landfill gas (LFG) utilization fer direct use as process fuel, and for electrical power generation at restored landfills in the Hong Kong Special Administrative Region of China (HKSAR). The paper specifically covers the LFG utilization schemes, which are required under landfill restoration contracts at the Shuen Wan and Urban Landfills. These contracts provide for the restoration and aftercare of six landfills, and are administered by the Environmental Protection Department (EPD) of the Hong Kong Government. The LFG utilization scheme at the Shuen Wan Landfill incorporates the direct use of LFG by compressing and dehumidifying the LFG prior to conveyance through a 1.6-kilometer (1-mile) pipeline. The pipeline provides an alternate fuel source to naphtha during process heating for gas production at the Tai Po Gas Production Plant of the Hong Kong and China Gas Limited (HKCC). The LFG utilization scheme at the Jordan Valley Landfill (one of the Urban Landfills) beneficially uses the LFG as fuel for electrical power generation with reciprocating internal combustion engines. The LFG is compressed, cooled, and filtered prior to delivery to two engine/generator sets. This system provides power to operate the leachate pre-treatment plant, which processes leachate from all of the Urban Landfill sites. The case study will examine the technical and non-technical considerations, including harriers, for developing, designing and implementing the LFG utilization projects in Hong Kong. Specific regulatory considerations and external governmental agency approvals are discussed, including the requirement to register as a gas-producing utility. While the paper focuses on LFG utilization applications in Hong Kong, many of the considerations discussed are also applicable to development of LFG utilization in other regions of Asia.

• 한국태양에너지학회 논문집
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• 제30권4호
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• pp.55-62
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• 2010

The purpose of this study is to present various analysis result of energy consumption that is a statistical analysis of high school facilities in Korea for setting the goal of energy saving. This study enforced analysis after it provided used energy consumption for the year 2008 and general in formation from 2202 high school facilities in 16 cities in South Korea by the relevant agency. Consequently, it represents that the average energy consumption of electric power was 428.7MWh(65.7%), gas consumption for heating was 129.5MWh(19.8%), oil consumption was 84.6MWh(13.0%), district energy was 10.0MWh(1.5%) in nation after changing as unit 'kWh' only for comparison with every energy source. This result describes that consumption of electric power was large greatly and it reflects the expectation that it will climb the demand regarding this energy in the future. In additionally, it analyzed average energy consumption with $98.3kWh/m^2$ by the unit area of air-conditioning and the district which has large energy consumption was Gyeonggi-do with $115.9kWh/m^2$. Furthermore, it described the average energy consumption of $60.8kWh/m^2$ by the unit area of floor area and the average energy consumption of a student analyzed with 1157.0kWh.

• 한국지반공학회논문집
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• 제29권8호
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• pp.65-73
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• 2013

지중 열교환 시스템은 지속적인 에너지 효율의 개선으로 공간 냉난방을 위한 친환경적 에너지 기술로 주목받고 있다. 지중에 매설된 파이프는 내부 유체 순환을 통하여 인접한 지반과 열적 상호작용으로부터 직접적인 열에너지 교환을 수행한다. 하지만, 파이프의 수치모델링에서 열-수리가 연관된 난류해석과 파이프의 긴 세장비에 의한 메쉬사이즈의 부적합성은 열교환 시스템의 적절한 수치해석을 어렵게 하고 있다. 본 논문에서는 파이프 내부 유체흐름에 대한 에너지 보존의 법칙을 적용하여 지배방정식을 유도하였으며, Galerkin수식화와 시간적분을 통하여 열-수리 연동일차원 파이프 요소를 개발하였다. 그리고 제안된 파이프 요소를 기 개발된 다공질 재료를 위한 열-수리-역학(Thermo-Hydro-Mechanical) 해석을 위한 유한요소 프로그램과 결합하였다. 개발된 요소를 이용한 수치해석 결과는 열응답 시험(Thermal Response Test) 결과로부터 주위지반의 유효 열전도도를 평가하기 위하여 사용하는 선형 열원 모델이 인접 파이프간의 열적상호작용과 파이프의 단부효과에 의하여 지반의 열전도도를 과다 평가하는 것으로 보여주었다. 따라서 열응답 시험 해석 결과에 대한 역해석을 적용하여 최적의 수렴성을 보여주는 변환행렬을 제시하였다.

• 한국식품영양과학회지
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• 제21권3호
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• pp.263-269
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• 1992

무청즙액을 식물녹엽단백질의 생산과 효모의 균체생산을 위한 두가지 목적으로 이용하는 연구를 하였다. 무청즙액을 80-10$0^{\circ}C$로 가열하거나 pH를 조정하여 침전시켰을 때 침전물의 양은 모두 무청즙액 1리터당 10.0-16.5g(평균 13.5g)이었고 이 침전물의 조단백질 함량은 25-30%이었다. 단백질을 침전시켜 제거한 여액은 전당의 함량이 1.0%정도 되게 희석하여 효모 Candida utilis를 배양하였을 때 무청 여액원액 1리터당 최고 19.59의 효모균체를 생산할 수 있었다. 따라서 무청즙액 1리터로부터 생산할 수 있는 고단백질자원은 33g이었다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.474-477
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• 2002

Equipment to cauterize tumors by an electrically heated Kanthal wire is under development. The wire( alloy of iron, chromium and Aluminum) keeps sufficient strength up to 1400 degrees in Celsius. Although AC 50Hz current source is used in the prototype experiment, RF current will be used in future. The diameter of the Kanthal wire was 0.3 mm which was connected to Kanthal wire of 0.8 mm. The thicker wire was used as a leading wire. The possibility of application of the heating wire in combination with an ultrasound endoscope was determined, where ultrasound endoscope is to be used to monitor the location on the wire and an extent of a tumor in digestive organs. This procedure requires the wire to be applied inside ultrasound transmitting media. First, the wire was applied in the degassed water in which a chicken liver sample was submerged. The wire, however, burned out in water soon after it became red-hot at 12 A. The reason is that large current is required for the wire to become red-hot due to strong convection. Starch paste of 3 weight percent was employed instead of water. This made the wire red-hot approximately at 6 A, showing the increased viscosity of the starch decreased the convection and the wire was cover by the steam. The liver sample was cauterized successively, while the location of the wire and the liver was monitored by an ultrasound diagnosis equipment outside the plastic vessel of the starch paste.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.470-475
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• 2003

KIGAM (Korea Institute of Geoscience and Mineral Resources) launched a new project to develop the low-enthalpy geothermal water in the area showing high geothermal anomaly, north of Pohang city, for large-scale space heating from KORP (Korea Research Council of Public Science & Technology) funding. Surface geologic and geophysical surveys including Landsat TM image analysis, gravity, magnetic, Magnetotelluric (MT) and controlled-source audio-frequency MT (CSAMT) and self-potential (SP) methods have been conducted and the possible fracture zone was found that would serve as deeply connected geothermal water conduit. By the end of 2003, two test wells of 1 km depth will be drilled and various kinds of borehole survey along with additional MT measurements and sample analysis will follow and then the detailed subsurface condition is to be characterized. Next step would be drilling the production well of 2 km depth and all further steps remain to be determined depending upon the results of the test well studies.

• 한국초등과학교육학회지:초등과학교육
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• 제31권3호
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• pp.321-333
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• 2012

The purpose of this study was to examine elementary school students' characteristics and difficulties in drawing and interpreting a line graph, and to present educational implications. Twenty five students(4th grader: 6, 5th grader: 9, and 6th grader: 10) at an elementary school participated in this study. We used a student's task which was about graphing on a given data table and interpreting his/her graph. The data table was on heating 200mL and 500mL of water and measuring their temperature at regular time intervals. We collected multiple source of data, and data analyzed based on the sub-variables of TOGS. The some results of this study are as follows: First, five children (20.0%), especially two of 10 sixth graders (20.0%), could not construct a line graph about a given data table. Second, twenty students (80.0%) had the ability on 'Scaling axes' and on 'Assigning variables to the axes', however, only a student understood why the time is on the longitudinal axis and the temperature is on the vertical axis. Third, in the case of 'Plotting points', twelve children (48.0%) could drew two graphs on a coordinate. Fourth, in the case of 'Selecting the corresponding value for Y (or X)', twenty student had little difficulty. on 'Describing the relationship between variables', seventeen students (68.0%) understood the relationship between time and temperature of water, and the relationship between temperature and amount of water. Finally, eleven students (44%) had the ability on 'Interrelating and extrapolation graphs.' Educational implications are also presented in this paper.