• 한국수소및신에너지학회논문집
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• 제17권4호
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• pp.461-469
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• 2006

This paper deals with the national competitiveness of hydrogen energy. The effectiveness of investments for hydrogen energy R&D and constructions of hydrogen energy infrastructures can be evaluated by the national competitiveness of hydrogen energy, and it is evaluated by an AHP(analytic hierarchy process) method. The evaluation indices of the national competitiveness are selected as the technical level, the number of researchers, the investments for R&D, and the infrastructure of hydrogen energy. Similarly, the technical level is divided into the number of published papers, the number of foreign patents, and the number of published proceeding papers. The evaluation indices of the technical level and the number of researchers were investigated by database searches. It appears that South Korea locates the sixth position in the world. The results of our study suggest that South Korea is relatively competitive in the technical level and the number of researchers. However, our country needs the long-term and well-focused R&D, and the expansion of infrastructures to enhance the national competitiveness of hydrogen energy in the future.

• 에너지공학
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• 제24권1호
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• pp.24-31
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• 2015

바닥복사난방 공간에서 생활특성과 착의량에 따른 열쾌적 범위를 제시하고 각 조건별 에너지사용량 및 비용을 산출하여 비교하는 것을 목적으로 하였다. 좌식생활이 입식생활보다 낮은 온도에서 중립적 온도를 나타냈는데 바닥표면과 인체사이의 국부적인 열전달이 전신온열감에 영향을 주었기 때문으로 판단된다. 착의량이 높을수록 낮은 온도에서 중립점 온도를 나타냈는데 착의량을 증가시키면 인체에서 방출되는 열손실이 감소하여 낮은 실내온도에서 동일한 열쾌적을 느낄 수 있기 때문으로 판단된다. 좌식생활방식이 입식생활방식보다 평균 6.0%의 에너지 사용량이 절감되는 것으로 나타나 좌식생활이 경제적인 생활방식으로 분석되었다. 착의량 1.2 Clo 상태가 착의량 1.0 Clo 상태보다 평균 13.5%, 착의량 0.8 Clo상태보다 평균 18.0%의 에너지 사용량이 절감되는 것으로 나타나 동절기에 착의량을 증가시키는 생활습관의 변화만으로도 에너지 절감 효과가 큰 것으로 분석되었다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제2권5호
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• pp.199-202
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• 2013

무선 센서 네트워크에서 클러스터링 방식의 네트워크 수명은 클러스터 헤드 결정 방법에 의해서 영향을 받는다. 대표적인 클러스터링 방식인 LEACH(Low-Energy Adaptive Clustering Hierarchy)의 경우 주기적으로 클러스터 헤드를 선택함으로써 클러스터 재구축으로 인한 에너지 소모가 큰 단점이 있다. 한편 ACAWT(Adaptive Clustering Algorithm via Waiting Timer)는 클러스터 헤드의 잔여 에너지 수준이 하나의 특정 임계치에 도달하면 클러스터를 재구축하는 비주기적인 클러스터 재구축 방식을 사용한다. 본 논문에서는 클러스터를 주기적으로 재구축하지 않고 노드의 잔여 에너지 수준(level)을 여러 단계로 설정한 후 클러스터 헤드의 잔여 에너지 수준이 한 단계 낮아지면 클러스터를 재구축하는 방법을 제안한다. 또한 클러스터 헤드 선정 시 이웃 노드 수와 잔여 에너지 수준을 고려함으로써 클러스터 헤드의 분포를 균일하게 유지시켜 네트워크 수명을 연장시킨다. 본 제안 방식의 성능을 평가하기 위해서 Qualnet 기반의 시뮬레이션을 수행하였으며, ACAWT와 성능을 비교한 결과 제안 방식이 네트워크 수명 측면에서 우월함을 확인하였다.

• 에너지공학
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• 제24권2호
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• pp.22-33
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• 2015

본 논문은 한국 폐자원에너지기업을 대상으로 R&D 효율성을 평가하는 지표 중 하나로서 현재의 기술수준과 이에 영향을 미치는 요인에 대해 기술경제이론에 근거하여 분석하였다. 연구 방법으로는 한국 폐자원에너지기업을 대상으로 한 설문조사 데이터를 이용해 다항로지스틱회귀분석을 활용하였다. 분석의 결과, 국내 폐자원에너지기업의 기업규모, R&D투자 비중, R&D인력 비중은 기술수준에 긍정적인 영향을 미치지만, 국내시장 경쟁정도가 심할수록 기술수준에 부정적인 영향을 미치는 것으로 분석되었다. 반면, 규모의 경제는 기술수준에 유의미한 영향을 미치지 못하는 것으로 분석되었다. 이러한 분석결과에 따른 정책적 시사점은 시장경쟁 과열이 기업의 기술수준에 부정적인 영향을 미치지 않도록 이해관계자 간 상생할 수 있는 협력체계를 구축해야 하며, 또한 생산량 증대 및 생산비용 감소를 통해 기업이 규모의 경제효과를 거둘 수 있도록 하는 노력이 필요하다는 것이다.

• 국토계획
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• 제54권5호
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• pp.129-138
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• 2019

This study aims to empirically examine the relationship between building energy consumption and building and local factors in Seoul. Building energy issue is an important topic for low carbon and eco-friendly city development. Building physical, socio-economic and environmental factors effect to increasing or decreasing energy consumption. However, there are different characteristic in each area, and this kind of variable has a hierarchical structure. The multi-level model was used to consider the hierarchical structure of the variables. In this study, a multi-level model was applied to confirm the difference between areas. Spatial area is Seoul, Korea and the temporal scope is August, summer season. As the result, in Model 1 (Null Model), ICC is 0.817. This shows that the energy consumption differs by 8.174% due to factors at the Dong level. Model 2 (Random Intercept Model) suggests that building's physical factors and Average age, Household size and Land price in Dong level have significant effects on Building energy consumption. In Model 3 (Random Coefficient Model), random effect variables have intercepts and slopes to vary across groups. This study provides a perspective for policy makers that the building energy reduction policies to be applied for buildings should be differently applied on area. Furthermore, not only physical factors but also socio-economic and environmental factors are important when making energy reduction policy.

• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1234-1245
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• 2018

The risk of multi-unit nuclear power plants (NPPs) at a site has received considerable critical attention recently. However, current probabilistic safety assessment (PSA) procedures and computer code do not support multi-unit PSA because the traditional PSA structure is mostly used for the quantification of single-unit NPP risk. In this study, the main purpose is to develop a multi-unit Level 2 PSA method and apply it to full-power operating six-unit OPR1000. Multi-unit Level 2 PSA method consists of three steps: (1) development of single-unit Level 2 PSA; (2) extracting the mapping data from plant damage state to source term category; and (3) combining multi-unit Level 1 PSA results and mapping fractions. By applying developed multi-unit Level 2 PSA method into six-unit OPR1000, site containment failure probabilities in case of loss of ultimate heat sink, loss of off-site power, tsunami, and seismic event were quantified.

• 조명전기설비학회논문지
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• 제25권2호
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• pp.87-95
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• 2011

A Renewable Portfolio Standard(RPS) is a regulation that requires the increased generation of energy from renewable energy sources such as solar, wind, fuel cell, small hydro, biomass and geothermal. By environmental, technical and these regulatory reasons, the amount of renewable energy sources will be increased in a network. However, it is hard to assess risk of a transmission network with large scale renewable energy sources because the output characteristics of renewable energies are intermittent. This paper evaluates effects of a transmission system with supplemental large scale renewable energies into the existing system. To evaluate these effects, a methodology for risk level of components in a network is proposed considering steady state and contingency N-1 in this paper. We consider line current and bus voltage in each state of a network.

• 한국태양에너지학회 논문집
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• 제23권2호
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• pp.35-41
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• 2003

In order to investigate the offshore wind resources around Korean peninsula, the "QuikSCAT Level 3" data by ADEOS II satellite was analyzed from Jan 1 2000 to Jan 18 2003. The "SeaWinds" on the satellite is a specialize4 device for microwave scatterometery that measures near-surface wind speed and direction under all weather and cloud conditions. Wind speed are extrapolated from 10m to 60m with the exponent of 1/10 in the power law model. It has been found that the High wind energy potentials are prevailing in the South sea and Southeastern end of Korean peninsula.

• Current Research on Agriculture and Life Sciences
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• 제32권4호
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• pp.215-223
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• 2014

This study examines the contribution level of greenhouse gas(GHG) emission reduction and installation costs of renewable energy facilities. The GHG emission forecasts and industrial structures in the 16 regions of Korea are then analyzed to identify the proper supply of renewable energy sources for each region. The results show that water power is the most effective and efficient renewable energy source to reduce GHG emissions, followed by sunlight, wind power, geothermal heat, and solar heat, respectively. The 16 regions are then categorized into 4 groups based on their GHG emission forecast and industrial structure: high emission and manufacturing group, low emission and manufacturing group, low emission and service group, and high emission and service group. The proper supply of renewable energy sources for each group is then determined based on the contribution level and cost efficiency of GHG emission reduction.

• 한국식품영양학회지
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• 제11권6호
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• pp.647-686
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• 1998

The purpose of this study was to investigate selected nutrient intakes, dietary atherogenesity, energy balance and activity level of college students. One hundred and thirty onoe students (61 males and 70 females) made their three-day dietary records and one-day activity records along with one-day dietary records. BMI of the surveyed students was 22.33 for males and 20.28 for females. Average calorie intakes of male and female students was respectively 2166.20kcal and 1793.60kcal. Females had slightly higher fiber intakes than males in terms of fiber g/1000kcal. Carbohydrate, protein and fat ratios in energy composition of males and females were respectively 56.62 : 15.33 : 24.70 and 57.64 : 16.49 : 25.79. Average cholesterol intakes of male and female students were 295.66mg and 259mg respectively. The male showed higher saturated fat intake. and had higher atherogenic indices of diets such as cholesterol index(CI) and cholesterol-saturated fat index(CSI) than the female. Males spent an average of 1039.00 kcal/day compared to females of 687.93 kcal/day for all physical activities. Most students participated in light (100% of males and females) and moderate (33% of males and 3% of females) activities level. Few students spent time at severe and very severe activity level. Seventeen of the 131 students were in positive energy balance whereas 83% were in negative balance. Both genders with positive energy balance tended towards smaller weight and BMI, and larger food intakes than those with negative energy balance. Students with positive energy balance had higher saturated fat intakes and dietary atherogenic scores of CI and CSI than the counterparts with negative energy balance. Males with positive energy balance had decreased physical activity and daily energy expenditure whereas increased food and saturated fat intakes. Females with positive energy balance had singificantly increased food, saturated fat and sugar intakes.