• Progress in Superconductivity
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• v.13 no.1
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• pp.52-57
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• 2011

A superconductor flywheel energy storage system (SFES) is an electro-mechanical battery which transforms electrical energy into mechanical energy for storage, and vice versa. The 35 kWh class SFES is composed of a main frame, superconductor bearings, electro-magnetic dampers, a motor/generator, and a composite flywheel. The energy storing capacity of the SFES can be limited by the operational speed range of the system. The operational speed range is limited by many factors, especially the resonant frequency of the main frame and flywheel. In this study, a steel frame has been designed and constructed for a 35 kWh class SFES. All the main parts, their housings, and the flywheel are aligned and assembled on to the main frame. While in operation, the flywheel excites the main frame, as well as all the parts assembled to it, causing the system to vibrate at the rotating speed. If the main frame is excited at its resonant frequency, the system will resonate, which may lead to unstable levitation at the superconductor bearings and electro-magnetic dampers. The main frame for the 35 kWh class SFES has been designed and constructed to improve stiffness for the stable operation of the system within the operational speed range.

• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.306-314
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• 2015

This paper examines the difference in the value of the nuclear fuel cycle cost calculated by the deterministic and probabilistic methods on the basis of an equilibrium model. Calculating using the deterministic method, the direct disposal cost and Pyro-SFR (sodium-cooled fast reactor) nuclear fuel cycle cost, including the reactor cost, were found to be 66.41 mills/kWh and 77.82 mills/kWh, respectively (1 mill = one thousand of a dollar, i.e., $10^{-3}$ $). This is because the cost of SFR is considerably expensive. Calculating again using the probabilistic method, however, the direct disposal cost and Pyro-SFR nuclear fuel cycle cost, excluding the reactor cost, were found be 7.47 mills/kWh and 6.40 mills/kWh, respectively, on the basis of the most likely value. This is because the nuclear fuel cycle cost is significantly affected by the standard deviation and the mean of the unit cost that includes uncertainty. Thus, it is judged that not only the deterministic method, but also the probabilistic method, would also be necessary to evaluate the nuclear fuel cycle cost. By analyzing the sensitivity of the unit cost in each phase of the nuclear fuel cycle, it was found that the uranium unit price is the most influential factor in determining nuclear fuel cycle costs.

• Journal of the Korean Solar Energy Society
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• v.28 no.1
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• pp.51-56
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• 2008

Since the direct normal insolation is a main factor for designing any solar thermal power system, it is necessary to evaluate its characteristics all over the country. We have begun collecting direct normal insolation data since December 1992 at 16 different locations and considerable effort has been made for constructing a standard value from measured data at each station. KIER(Korea Institute of Energy Research)'s new data will be extensively used by solar thermal concentrating system users or designers as well as by research institutes. From the results, we can conclude that 1) Yearly mean $2.67\;kWh/m^2/day$ of the direct normal insolation was evaluated for all days all over the 16 areas in Korea. 2) All day's direct normal insolation of spring and summer were $2.91\;kWh/m^2/day$ and $2.23\;kWHm^2/day$, and for fall and winter their values were $2.78\;kWh/m^2/day$ and $2.77\;kWh/m^2/day$ respectively. So, spring, fall and winter were higher, and summer was lower than the yearly mean value.

• Environmental Engineering Research
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• v.17 no.2
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• pp.89-94
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• 2012

Pyrolysis/gasification technology utilizes an energy conversion technique from various waste resources, such as biomass, solid waste, sewage sludge, and etc. to generating a syngas (synthesis gas). However, one of the major problems for the pyrolysis gasification is the presence of tar in the product gas. The tar produced might cause damages and operating problems on the facility. In this study, a gliding arc plasma reformer was developed to solve the previously acknowledged issues. An experiment was conducted using surrogate benzene and naphthalene, which are generated during the pyrolysis and/or gasification, as the representative tar substance. To identify the characteristics of the influential parameters of tar decomposition, tests were performed on the steam feed amount (steam/carbon ratio), input discharge power (specific energy input, SEI), total feed gas amount and the input tar concentration. In benzene, the optimal operating conditions of the gliding arc plasma 2 in steam to carbon (S/C) ratio, 0.98 $kWh/m^3$ in SEI, 14 L/min in total gas feed rate and 3.6% in benzene concentration. In naphthalene, 2.5 in S/C ratio, 1 $kWh/m^3$ in SEI, 18.4 L/min in total gas feed rate and 1% in naphthalene concentration. The benzene decomposition efficiency was 95%, and the energy efficiency was 120 g/kWh. The naphthalene decomposition efficiency was 79%, and the energy yield was 68 g/kWh.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.289-292
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• 2002

국어에서 wh-단어가 포함된 의문사 의문문과 부정사 의문문은 통사적으로 같은 구조를 가지지만 의미적으로는 중의 관계에 있다. 그러나 두 의문문은 문장으로 발화될 때 음성적으로 서로 다른 여러 가지 운율 특징의 차이를 보여줌으로써, 발화 차원에서는 더 이상 중의 관계를 유지하지 않는다. 본고에서는 이러한 중의성의 해소는 두 의문문의 초점이 달리 실현되기 때문이라고 본다. 기존의 연구에서는 두 가지 의문문의 억양 연구를 초점의 작용 범위와 문말 억양의 차이, 강세구 형성의 유형을 중심으로 고찰하였다 .그리고 의문사와 부정사의 의미는, 이에 후행하는 서술어와 형성하는 강세구 유형에서 우선적으로 그 의미가 구분될 수 있다고 보았다. 그러나, 본고에서는 국어의 wh-단어가 초점으로서 작용하는 운율적 돋들림을 좀더 다양한 환경에서 실험하였다. 그리고 의문사${\cdot}$부정사와 후행하는 언어단위의 강세구 형성(accentual phrasing) 유형, 의문사${\cdot}$부정사 의문문 전체 문장 억양의 실현 양상, wh-단어 자체의 음의 높낮이(pitch contour) 실현 유형, 문말 억양(boundary tone)에서 음의 높낮이를 대상으로 분석하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.129-129
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• 2015

2011년 후쿠시마 원자력발전소 사고 이후, 발전원의 위험사고비용 및 환경피해비용에 대한 관심이 대두되고 있다. 전력은 생산과정 뿐만 아니라 발전소 건설, 발전소 운영, 송 배전을 통한 전력 공급, 폐기물처리 등의 각 과정에서 다양한 환경비용을 야기하고 있다. 따라서 발전원의 환경영향을 수용자적 입장에서의 평가할 필요가 있다. 본 연구에서는 컨조인트 분석법의 일종인 선택실험법을 적용하여 발전에 따른 환경영향 속성들에 대해 평가한 후, 발전원별로 상이한 속성 값에 속 성별 추정치를 반영하여 발전원별 환경비용을 수용자적 입장에서 추정하였다. 발전원부문이 환경에 미치는 영향에 대한 속성을 온실가스 배출, 건강피해, 지역피해, 온배수 배출로 선정하였고, 제시금액은 비교 대상 발전원들의 전력거래 단가 및 가구당 지출하는 월평균 전기요금수준을 기준으로하여 35,000원에서 75,000원까지의 총 다섯 가지 속성수준으로 구분하였다. 다항로짓모형을 적용하여 발전원별 각 환경영향에 대한 속성별 한계지불의사액 추정하고, 발전원간의 환경비용을 산정하였다. kWh 당 수력발전(0원/kWh) 대비 타 발전원의 추가 환경비용은 26원/kWh­832원/Wh로 환경적 영향 측면에서 국민수용성이 가장 높게 나타났다.

• Journal of the Korean Solar Energy Society
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• v.33 no.3
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• pp.67-74
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• 2013

These days, although thermal energy is decreasing, electric energy is increasing in building. Also, it is very important to research and distribute BIPV(Building Integrated photovoltaic) because our society consider electricity more significant than other energy in building. Therefore, in this paper, our research team analyzed difference between BIPV yield and building energy consumption through experimental research. As a result, yearly building energy consumption was 104,602.4kWh and BIPV yield was 105,267kWh. And then, totally counterbalanced time took up 26%, reduced electric load time took up 16%. In other words, peak load could be reduced up to 42% by BIPV. As a result, yearly building energy consumption was 104,602.4kWh and BIPV yield was 105,267kWh. And then, totally counterbalanced time took up 26%, reduced electric load time took up 16%. In other words, peak load could be reduced up to 42% by BIPV.

• Journal of the Korean Solar Energy Society
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• v.30 no.4
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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.

• Journal of IKEEE
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• v.23 no.2
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• pp.687-694
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• 2019

Residential electricity consumer can rent a photovoltaic power generator, whose profit can be exist if the decreased electric fee is larger than the rent fee. But the exact function of the profit have not expressed until now, which is shown in this paper. Two assumptions are supposed. The first assumption is that the generated electric power by the renting photovoltaic generator is 300kWh per month. The second assumption is that the rent fee 362300 won is paid once when the photovoltaic generator is installed. The earings rate, the payback time and the sensitivity of a low-voltage residential electricity consumer's profit consuming 401~1000kWh per month at a detached house for the initial 7 years is calculated by the induced exact function.

• New & Renewable Energy
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• v.1 no.1 s.1
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• pp.79-86
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• 2005

This study conducted an analysis of economic feasibility with unit generating costs calculated based on scenarios of capacity factors, discount rates, government supporting rates, installation costs. However, It Is clear that few new and renewable energies can meet the tariffs [government purchasing prices] set by the government in light of the current market reality. Without the government support, solar PV is not economically feasible at the tariff of \716.40/kWh. in the case of wind Power, the current tariff of \107.66/kWh is not enough to make it competitive except for a mid- and large-scale wind farm The analysis showed that even small hydro is not economically acceptable at the current tariff of \73.69/kWh.