• 국토계획
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• 제53권6호
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• pp.101-116
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• 2018

Paying an attention to the issue of energy poverty of low-income households and ensuing regressivity of energy consumption, this study empirically analyzes the effects of both household and housing characteristics on heating energy consumption in an integrated way and identifies their causal structure based on the 2016 Korea Housing Survey data provided by the Korean government. Multiple regression analysis shows that household income and deteriorated level of housing, such as age and degree of cracks have positive effects and floor area of housing has a negative effect on the heating energy consumption per unit area of housing (HECPUH). Path analyses further reveal that the direct effect of household income on HECPUH is offset by the indirect effects that are mediated by deteriorated level and floor area of housing, making the total effect statistically insignificant. As a result, there is no significant difference in HECPUH across all income strata, implying that low-income (high-income) households pay more (less) heating costs relative to their income level, since they reside in the houses with relatively low (high) energy efficiency. To deal with this regressive causal structure of energy consumption, a policy option is recommended to improve energy efficiency of low-income housing through the government assistance in its maintenance and repair.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2819-2827
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• 2022

The disposal area of a deep geological repository (DGR) for the disposal of spent nuclear fuels (SNFs) is estimated considering the spacing between deposition holes and between disposal tunnels, as determined by a thermal analysis using the decay heat of a reference SNF. Given the relatively large amount of decay heat of the reference SNF, the disposal area of the DGR is found to be overestimated. Therefore, we develop a computer program using MATLAB, termed ACom (Assembly Combination), to combine SNFs when stored in canisters such that the decay heat per canister is evenly distributed. The stability of ACom was checked and the overall distribution of the decay heat per canister was analyzed. Finally, ACom was applied to disposal scenarios suggested in the conceptual design of a DGR for SNFs, and it was confirmed that the decay heat per canister could be evenly distributed and that the maximum decay heat of the canister could be much lower than that of a canister estimated using a reference SNF. ACom can be used to improve the disposal efficiency by reducing the disposal area of a DGR for SNFs by ensuringg a relatively even distribution of decay heat per canister.

• 문화기술의 융합
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• 제7권1호
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• pp.564-569
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• 2021

본 연구에서는 일반적인 구조의 LED와 경사진 구조의 LED에 대하여, 전극이 없을 때와 전극에서 20%의 흡수(80% 반사)가 발생할 때, 그리고 전극에서 60%의 흡수(40% 반사)가 발생할 때로 구분하여, 전극에서의 흡수와 활성 영역의 높이가 광추출 효율 및 평균 광자 진행 거리에 미치는 영향을 조사하고, 활성 영역의 적절한 높이를 제안하였다. 일반적인 LED에서 전극의 흡수가 증가할수록, 광추출 효율은 18%에서 15%, 13%로 낮아지고, 활성 영역의 높이가 두 전극 사이의 정 중앙에 위치할 때 가장 광 추출 효율이 높다. 경사진 구조의 LED에서는 전극의 흡수가 증가할수록, 광추출 효율은 38%에서 33%, 25%로 낮아지고, 활성 영역의 높이가 두 전극 사이의 정 중앙에 위치할 때 가장 광 추출 효율이 높다. 경사진 구조의 LED는 일반적인 LED 보다 광추출 효율을 두 배 이상 높일 수 있다. 이는 전반사에 의해 광자가 칩 내부에 갇히는 현상을 줄여주기 때문이다.

• 대한기계학회논문집
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• 제15권6호
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• pp.2171-2180
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• 1991

본 연구에서는 구심터어빈의 설계시 많이 사용되고 있는 NASA의 안내깃 및 회 전익 손실모델들을 이용하여 PR과 K를 실험에 의존하지 않고 구하는 방법을 제시하고 자 한다. 그리고 이 방법을 가변 안내깃이 존재하거나 없는 가상의 구심터빈에 대하 여 탈설계 성능해석을 하여, 본 방법이 기존에 알려진 실험 현상과 유사한 경향을 보 이는지를 알아보기로 한다. 또한 안내깃이 있는 경우에 대하여 기존의 알려진 탈설 계 성능 예측용 프로그램과의 비교를 통하여 본 연구의 해석방법을 간접적으로 검증하 기로 한다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.644-648
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• 2004

In the present study were examined numerically and experimentally the off-design performance characteristics on an axisymmetric plug nozzle with variable throat area. In this nozzle concept, its throat area can be changed by translating the plug into the axial direction. First, a mixed-expansion plug nozzle, in which two expansion parts are arranged both inside and outside, was designed by means of the method of characteristics. Second, the CFD analysis was verified by the cold-flow wind tunnel test. Third, its performance characteristics were evaluated over a wide range of pressure ratio from half to double throat area through the design point, using the CFD code verified by the wind tunnel tests. It was made clear from the study that not so critical thrust efficiency losses were found and the maximum thrust efficiency loss was at most approximately 5 % under off-design conditions without external flow. This result shows that a plug nozzle can give the altitude compensation even under off-design geometry operations. However, shock waves were observed in the inner expansion part under the doubled throat area operation and thus some thermal problems may be caused on the plug surface. Furthermore, collapse of cell structure on the plug surface was observed with external flow (around Mach number 2.0) as it became lower pressure ratio below the design point and the fact may result in big efficiency loss regardless of geometrical configuration.

• 한국수자원학회논문집
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• 제39권11호
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• pp.915-922
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• 2006

본 연구는 소방방재청에서 계획하고 있는 도시유역의 침수피해를 방지하기 위한 대책 수립의 일환으로 도시유역의 중상류부에 중소규모의 저류지를 설치하는 방안에 대한 유출저감 효과 분석에 관한 것이다. 이를 위해 시범유역을 선정하여 유출분석을 실시하였고 저류지의 위치와 규모에 따른 유출저감 정도 및 치수안전도 확보 효과를 분석하였다. 분석결과 유역의 유출량을 모두 하도에서 소통시키는 개념이 아닌 유역에서 홍수량의 일부를 저류하여 유량을 분담하는 유역분담 저류지를 설치함으로써 하도의 부담을 완화시킬 수 있음을 확인하였고 저류지의 입지 및 규모의 선정에 따라 그 효과에 큰 차이가 있음을 알 수 있었다. 따라서 중상류부에 저류지를 설치하는 경우 하류부 유출 저감에는 상당히 효과적인 것으로 나타나 유역의 치수안전도 확보에 효율적인 방안이 될것으로 기대된다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권2호
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• pp.203-211
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• 2012

This paper proposes a $16{\times}16$ and $32{\times}32$ inverse transform architecture for HEVC (High Efficiency Video Coding). HEVC large transform of $16{\times}16$ and $32{\times}32$ suffers from huge computational complexity. To resolve this problem, we proposed a new large inverse transform architecture based on hardware reuse. The processing element is optimized by exploiting fully recursive and regular butterfly structure. To achieve low area, the processing element is implemented by shifters and adders without multiplier. Implementation of the proposed 2-D inverse transform architecture in 0.18 ${\mu}m$ technology shows about 300 MHz frequency and 287 Kgates area, which can process 4K ($3840{\times}2160$)@ 30 fps image.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.243-244
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• 2009

The $TiO_2$ nanofiber doped $TiO_2$ electrode area applied to dye-sensitized solar cells(DSSCs). The mixtures of $TiO_2$ nanofiber to $TiO_2$ photoelectrode has larger surface area than $TiO_2$ photoelectrode. In this research added 2.5, 5 and 10wt% $TiO_2$ nanofibers and the optimum condition of 5 wt% $TiO_2$ nanofiber's high surface area contributing the improvement of short-circuit photocurrent. The open-circuit voltage was 0.7V and solar energy conversion efficiency was 5.4%.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.594-597
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• 2006

Image co-registration is the process of overlaying two images of the same scene. One of which is a reference image, while the other (sensed image) is geometrically transformed to the one. Numerous methods were developed for the automated image co-registration and it is known as a time-consuming and/or computation-intensive procedure. In order to improve efficiency and effectiveness of the co-registration of satellite imagery, this paper proposes a pre-qualified area matching, which is composed of feature extraction with Laplacian filter and area matching algorithm using correlation coefficient. Moreover, to improve the accuracy of co-registration, the outliers in the initial matching point should be removed. For this, two outlier detection techniques of studentized residual and modified RANSAC algorithm are used in this study. Three pairs of Landsat images were used for performance test, and the results were compared and evaluated in terms of robustness and efficiency.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.615-618
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• 2003

A prototype of 76 ha Shi-hwa constructed wetland was constructed for the first time in Korea to purify severely polluted stream water. Hydrology, vegetation(macrophyte) and water quality for Banwol and Donghwa wetland built in Shi-hwa tidal reclaimed area were monitored to evaluate the performance of the wetlands. The overall efficiency for the treatment of polluted stream water using the wetlands showed no significant improvement. The monthly average removal rates on SS, BOD, TN and TP for Banwol and Donghwa wetlands showed 66.5% and 62.8%, 14.8 and 34.3%, 33.9 and 47.1% and 20.8 and 51.6%, respectively. It is considered that three major factors, ie. wide fluctuations in inflow rate, short hydraulic retention time and small open area compared with vegetated area could have a great influence on low system efficiency.