• 한국지구과학회지
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• 제27권3호
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• pp.302-312
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• 2006

이 연구에서는 1979년부터 2004년까지 25년 동안에 극 진동의 강도가 한반도 겨울 한파에 미치는 영향을 대기순환과 열원을 분석하여 조사하였다. 북극 진동이 강할 때 한파의 발생 횟수는 약할 때 보다 약 14.3% 더 발생하는 것으로 나타났다. 월 발생 횟수에서도 양의 AO에서 1.05회/월, 음의 AO에서 1.33회/월로 나타나서 북극 진동이 강할 때가 약할 때 보다 약 26.6% 더 많았다. 이것은 북극 진동이 강한 특정 달에 한파가 자주 발생한다는 것을 의미한다. 또한 북극 진동이 강할 때가 약할 때보다 $0.6^{\circ}C$ 더 낮은 기온을 보였다. 북극 진동의 강약에 따른 열원의 차이를 고찰한 결과, 북극 진동이 강해졌을 때 한반도 주변의 기온은 이류항에 의한 냉각이 강화되어 더 낮아지지만, 열원항에 의한 상쇄 효과에 의해 기온 하강을 억제하는 것으로 나타났다. 그 결과 대기 순환의 유의한 차이에도 불구하고 음의 AO와양의 AO 사이에 기온 차이는 평균적으로 $0.6^{\circ}C$로 작게 나타난다.

• 한국환경과학회지
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• 제12권7호
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• pp.809-816
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• 2003

The short-term version of Industrial Source Complex Model(ISCST3) was evaluated for estimating short-term concentrations using criteria pollutant(SO$_2$, NO$_2$, CO, PM10) data from emission inventory of Young Tong area in Suwon for the year 2002. The contribution of pollutant concentration from point, line, area sources was found 21.8, 76.5 and 1.6%. Statistical parameters, such as correlation coefficient, index of agreement(IA), normalized mean square error(NMSE) and fractional bias(FB) were calculated for each pollutants. The model performance were found good for PM10(82%) and NO$_2$(69%), but poor for SO$_2$(34%) and CO(13%).

• KIEAE Journal
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• 제17권4호
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• pp.33-39
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• 2017

Purpose: The use of renewable energy system is essential for building energy independence and saving energy consumption in the building sector. Among renewable energy technologies, ground source heat pump(GSHP) system is more energy-efficient and environmental-friendly than other heat source systems due to utilize stable ground heat source. However, the GSHP system requires a high initial installation cost and installation space in limited urban area, so it is difficult to have superiority in the market of heat source system. Therefore, it is necessary to develop the installation method of low-cost and improve system performance. This paper aims to evaluate the performance of double u-tube ground heat exchanger(GHX) and verify system feasibility through real-scale experiment. Method: In this study, the real-scale experiment of vertical closed-type GSHP system was conducted using double u-tube GHX and high-efficiency grout. Through the verification experiment, heat source temperature, heat exchange rate(HER) and seasonal performance factor(SPF) were measured according to the long-term operation. In addition, the feasibility analysis was conducted comparing to the single u-tube system. Result: In the results of experiment, average HER was 136.27 W/m and average SPF was 5.41. Furthermore, compared to the single u-tube, the installation cost of the developed system could be reduced about 70% in the same heating load condition.

• 보건행정학회지
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• 제32권2호
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• pp.173-179
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• 2022

Background: This study aimed to identify patterns of elderly patients who transferred from long-term care hospitals to emergency rooms and provide the evidence of emergency medical systems to prepare for a super-aged society. Methods: The data source was the National Emergency Department Information System database from January 2014 to December 2019 in Korea. We performed a cross-sectional study among elderly patients (≥65 years) who transferred from a long-term care hospital to an emergency room. Trend analysis was conducted by year. Results: We identified 225,765 elderly patients who were transferred from long-term care hospitals to emergency rooms between January 1, 2014 and December 31, 2019. The proportion of the study population and their mean age were recently increased (p<0.001, respectively). The proportion of elderly patients being re-transferred (p=0.049) and the patients re-transferred to long-term care hospitals is significantly increased (p=0.005). Conclusion: The establishment of efficient emergency medical services for an aging society is important. It is necessary to develop a healthcare network with the government, long-term care hospitals, and medical institutions in the community suitable for preventing disease deterioration.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.386-392
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• 2021

MACCS (MELCOR Accident Consequence Code System), WinMACCS, and MelMACCS now facilitate a multi-unit consequence analysis. MACCS evaluates the consequences of an atmospheric release of radioactive gases and aerosols into the atmosphere and is most commonly used to perform probabilistic safety assessments (PSAs) and related consequence analyses for nuclear power plants (NPPs). WinMACCS is a user-friendly preprocessor for MACCS. MelMACCS extracts source-term information from a MELCOR plot file. The current development can combine an arbitrary number of source terms, representing simultaneous releases from a multi-unit facility, into a single consequence analysis. The development supports different release signatures, fission product inventories, and accident initiation times for each unit. The treatment is completely general except that the model is currently limited to collocated units. A major practical consideration for performing a multi-unit PSA is that a comprehensive treatment for more than two units may involve an intractable number of combinations of source terms. This paper proposes and evaluates an approach for reducing the number of calculations to be tractable, even for sites with eight or ten units. The approximation error introduced by the approach is acceptable and is considerably less than other errors and uncertainties inherent in a Level 3 PSA.

• Environmental Engineering Research
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• 제17권1호
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• pp.47-56
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• 2012

A long-term nationwide nonpoint-source pollution monitoring program was initiated by the Ministry of Environment Republic of Korea (ME) in 2007. Monitoring devices including rain gauges, flow meters, and automatic samplers were installed in monitoring sites to collect dynamic runoff data in 2008-2009. More than 10 rainfall events with three or more antecedent dry days were monitored per year. More than 10 samples were collected and analyzed per event. So far, five land use types (single family, apartments, education facilities, power plants, and other public facilities) have been monitored 23 to 24 times each. Characterization of the runoff from different land use types will aid unit load estimation in Korea and hopefully in other countries with similar land use. The monitoring results will be reported regularly at national and international levels.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.53-57
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• 2002

The solar energy is purity and infinity. Solar power converter were used to convert the electrical energy from the solar arrays to a stable and reliable power source. So many countries research this solar energy system The photovoltaic system is construct many solar cell array. In this paper, new implementation solar system was showed buck converter that V-I curve produced. This system can be used to study the short-term and long-term performances of solar cell and efficiency. This system is a far more cost effective and reliable replacement for field and outdoor flight testing. Study of buck converter, analysis and control series or parallels connection characteristics of solar cell way.

• 환경영향평가
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• 제21권4호
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• pp.573-579
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• 2012

Many countries have recently been expanding efforts for low-carbon global economy to solve the problem of global warming. Development and research for various types of new reusable energy is on the rise throughout the world. The most promising source of energy is the solar photovoltaic energy and the government take an initiative to establish both short-term and long-term policies to develop the solar energy potential resource map. The solar energy and industrialize area researched by GIS methods for optimum site for solar power transfer system. This study attempts to address the hot issue of the development and suitability of the solar photovoltaic energy site using GIS spatial analysis. We need to analyze and describe the solar technology, green energy policies and the energy market trend of the field.

• Journal of Electrical Engineering and Technology
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• 제5권2호
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• pp.264-269
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• 2010

This paper presents the analysis of the dielectric characteristics of a hot $SF_6$ gas in a gas circuit breaker. Hot gas flow is analyzed using the FVFLIC method considering the moving boundary, material properties of real $SF_6$ gas, and arc plasma. In the arc model, the re-absorption of the emitted radiation is approximated with the boundary source layer where the re-absorbed radiation energy is input as an energy source term in the energy conservation equation. The breakdown criterion of a hot gas is predicted using the critical electric field as a function of temperature and pressure. To validate the simulation method, breakdown voltage for a 145kV 40kA circuit breaker was measured for various conditions. Consistent results between the simulation and experiment were confirmed.

• 한국발생생물학회지:발생과생식
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• 제14권3호
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• pp.155-162
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• 2010

The trophectoderm is one of the earliest cell types to differentiate in the forming placenta. It is an important for the initial implantation and placentation during pregnancy. Trophoblast stem cells (TBSCs) develop from the blastocyst and are maintained by signals emanating from the inner cell mass. However, several limitations including rarity and difficulty in isolation of trophoblast stem cells derived from blastocyst still exist. To establish a model for trophoblast differentiation, we isolated TBSCs from human term placenta ($\geq$38 weeks) and characterized. Cell cycle was analyzed by measuring DNA content by FACS analysis and phenotype of TBSCs was characterized by RT-PCR and FACS analysis. TBSCs have expressed various markers such as self-renewal markers (Nanog, Sox2), three germ layer markers (hNF68, alpha-cardiac actin, hAFP), trophoblast specific markers (CDX-2, CK7, HLA-G), and TERT gene. In FACS analysis, TBSCs isolated from term placenta showed that the majority of cells expressed CD13, CD44, CD90, CD95, CD105, HLA-ABC, cytokeratin 7, and HLA-G. Testing for CD31, CD34, CD45, CD71, vimentin and HLA-DR were negative. TBSCs were shown to decrease the growth rate when cultured in conditioned medium without FGF4/heparin as well as the morphology was changed to a characteristic giant cell with a large cytoplasm and nucleus. In invasion assay, TBSCs isolated from term placenta showed invasion activities in in vivo using nude mice and in vitro Matrigel system. Taken together, these results support that an isolation potential of TBSCs from term placenta as well as a good source for understanding of the infertility mechanism.