• Nuclear Engineering and Technology
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• 제51권1호
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• pp.284-292
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• 2019

For the continuous operation of a nuclear reactor, burnt fuel needs to be replaced with fresh fuel, where appropriate (ex-vessel) fuel handling is required. Particularly for the Sodium-cooled Fast Reactor (SFR) refueling, its process has unique challenges due to liquid sodium coolant. The ex-vessel spent fuel transportation should concern several design features such as the radiation shielding, decay-heat removal, and inert space separated from air. This paper proposes a new design optimization methodology of cask shielding to transport the spent fuel assembly in a prototype SFR for the first time. The Particle Swarm Optimization (PSO) algorithm had been applied to design trade-offs between shielding and cask weight. The cask is designed as a double-cylinder structure to block an inert sodium region from the air-cooling space. The PSO process yielded the optimum shielding thickness of 26 cm, considering the weight as well. To confirm the shielding performance, the radiation dose of spent fuel removed at its peak burnup and after 1-year cooling was calculated. Two different fuel positions located during transportation were also investigated to consider a functional disorder in a cask drive system. This study concludes the current cask design in normal operations is satisfactory in accordance with regulatory rules.

• 설비공학논문집
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• 제7권3호
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• pp.538-545
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• 1995

The heat transfer model of ondol heating system is derived in the linear form. The step responses of On-Off controller, PID controller and Position type fuzzy controllers are compared in the sense of several aspects : variation of temperature feedback variable, variation of supplied heat quantity by the boiler, variation of flow rate, variation of thickness of the base, variation of the outdoor temperature.

• 대한기계학회논문집
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• 제18권9호
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• pp.2431-2442
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• 1994

In this paper the efficient space marching Viscous Shock Layer and Parabolized Navier-Stokes method have been applied to study the complex 3-D hypersonic equilibrium chemically reacting flowfilelds over sphere-cone($10^{\circ}$) vehicle at low angles of attack($0^{\circ}~5^{\circ}), Mach 20, and an altitude of 35km. The current bluntbody/afterbody space marching numerical method predicts the complex flowfields accurately and efficiently even on a small computer. The shock thickness from equilibrium air model is thinner than that from the perfect gas model. The windside wall heat-transfer rate, pressure and skin friction force were increased significantly when compared with those of leeside. The CA, CN, CM were increased almost linearly with the angle of attack in this region. The wall pressure, heat transfer, skin friction and axial force coeffient from equilibrium model were much higher than those from perfect gas model. The center of pressure moved forward with the increase of angle of attack.

• KIEAE Journal
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• 제8권5호
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• pp.3-10
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• 2008

The Korean traditional architecture has developed by adapting to the natural environment, and has successfully created a comfortable indoor settings by using the surrounding natural resources. This is reflected in the building layout, space design and even materials. Our traditional wooden windows adjusting ambient temperature and humidity have both the functions of window and door, although they are clearly divided in the West. The opening and closing method of our traditional windows is similar and their dimensions are shown not to be standardized but diverse in terms of the characteristic of wooden furniture and that of components placed between columns. Thus this study aims to research the sound insulation and absorption performance of traditional windows to be varied with thickness, finishing method of window paper and thickness of air layer. Despite increase of the thickness of window paper, sound absorption was reduced, and the same result was shown when both sides of the structure were finished with thick window paper. The sound insulation performance of the windows could be evaluated to be inappropriate with $R_w$ 0 ~ $R_w$ 14.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.807-812
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• 2008

The various attempts is made to solve the energy and environment problems. In addition, people interested in their life quality want the more eco-friendly living space. So we suggested that the earth-sheltered house could be one of the eco-friendly and low energy consuming houses to meet the social interest. And we also made data for design of the earth-sheltered house to be applicable to climate of Korea. In this study, a simulation was performed to estimate a boundary temperature according to earth sheltering thickness at the earth-sheltered part(exterior wall) in the case of earth sheltering on the plane ground not using a sloped site. And we analyzed the reduction of a thermal load by using this boundary temperature. We also compared a case of earth sheltering at the vertical wall with a case of earth sheltering at the roof to know the thermal reduction effect of a case of earth sheltering at the vertical wall.

• 생물환경조절학회지
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• 제22권4호
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• pp.316-321
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• 2013

본 연구는 온실의 관류전열량을 분석하고 예측하는데 필요한 기초자료 제공을 위하여, 공기막 이중 PO필름의 열저항식을 모델링하였고, 전도, 복사, 대류에 의한 열저항 특성을 규명하였다. 또한 열저항식의 타당성 검증을 위해 열저항식에 의한 관류전열량의 계산값과 실험값을 비교 분석하였다. 공기막 이중 PO필름의 열저항식은 PO필름, 공기막, PO필름의 직렬 열저항식으로 구성되며, 공기막은 복사와 대류에 의한 병렬 열저항식으로 구성된다. 고온부 $T_1$의 평균온도는 276.1K, 저온부 $T_2$의 평균온도는 266.8K로 나타났으며, 다른 조건들이 동일할 경우 챔버 내부온도가 높을수록 $T_1$과 $T_2$의 평균온도와 온도차가 증가하는 것을 확인할 수 있었다. 전도열저항은 $0.00091K{\cdot}W^{-1}$로 전체 열저항의 1% 미만으로 매우 미미한 수준이고, 공기막의 열저항이 $0.18K{\cdot}W^{-1}$로 전체 열저항의 99% 이상을 차지하는 것으로 나타났다. 공기막의 경우 대류열 저항이 복사열저항에 비해 1.33~2.08배 정도 크게 나타났으며, 복사열저항은 평균온도의 3제곱에 반비례하고 대류열저항은 온도차가 4.7, 5.3, 5.5, 5.7, 12.3, 13.2, 13.3, 13.5, 13.8 및 14.0K로 증가할 때 각각 0.78, 0.75, 0.74, 0.73, 0.57, 0.56, 0.56, 0.56, 0.55 및 $0.55K{\cdot}W^{-1}$로 감소하였다. 관류전열량의 계산값과 실험값의 차이는 실험조건별로 0.6~17.2W의 범위로 평균 6.9W였으며, 실험값은 계산값의 79.8~97.7% 범위로 평균 87.3% 수준으로 나타났다. 전체적인 계산값과 실험값의 관류전열량 경향성은 잘 일치하고 있으며, 공기막 이중필름의 열저항은 공기막 두께 및 주입공기의 종류와는 직접적인 상관관계를 보이지 않았다.

• 대한원격탐사학회지
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• 제26권6호
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• pp.617-627
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• 2010

Although many researches for heat island study have been developed, there is little attempt to link the findings to actual and hypothetical scenarios of urban developments which would help to mitigate the Urban Heat Island (UHI) in cities. The aim of this paper is to analyze the UHI at urban area with different geometries, land use, and environmental factors, and emphasis on the influence of different geometric and environmental parameters on ambient air temperature. In order to evaluate these effects, the parameters of (i) Air pollution (i.e. Aerosol Optical Thickness (AOT)), (ii) Green space Normalized Difference Vegetation Index (NDVI), (iii) Anthropogenic heat (AH) (iv) Building density (BD), (v) Building height (BH), and (vi) Air temperature (Ta) were mapped. The optimum operational scales between Heat Island Intensity (HII) and above parameters were evaluated by testing the strength of the correlations for every resolution. The best compromised scale for all parameters is 275m resolution. Thus, the measurements of these parameters contributing to heat island formation over the study areas of Hong Kong were established from mathematical relationships between them and in combination at 275m resolution. The mathematical models were then tabulated to show the impact of different percentages of parameters on HII. These tables are useful to predict the probable climatic implications of future planning decisions.

• KIEAE Journal
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• 제15권1호
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• pp.77-82
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• 2015

The purpose of this study is to compare the thermal insulation performance of windows according to the formation of air layer and to evaluate its energy efficiency on a selected standard house. A thermal insulation test, KS F 2278 was used to measure U-values (Heat transmission coefficients) for the following three cases: the first case (Case 1) is a Low-E pair glass (Argon injected), the second case (Case 2) is a Low-E pair glass with the air cap attached on the glass surface, and the third case (Case 3) is a Low-E pair glass, on the frame of which the air cap is attached. The evaluation of the energy efficiency was conducted according to a building energy calculation method from ISO 13790, calculation of energy use for space heating and cooling, using the U-values obtained from the thermal insulation tests. As results of the tests, the U-values of Case 1, Case 2, and Case 3 were $1.668W/m^2{\cdot}K$, $1.568W/m^2{\cdot}K$, and $1.319W/m^2{\cdot}K$ respectively. The Case 2 had about 5.9% lower value than the Case 1, and the Case 3 had about 20.9% lower value than the Case 1. It seems that the thermal performance of the windows is attributed to an increase of the heat resistance and the thickness of air layer. An evaluation of the energy efficiency of the three cases on the selected standard house showed that the amount of heating energy demand per unit area was $7.776kWh/m^2{\cdot}yr$ for the Case $1,6.856kWh/m^2{\cdot}yr$ for the Case 2, and $4.856kWh/m^2{\cdot}yr$ for the Case 3. This study suggests that the formation of air layer (by using air cap) and its thickness should reduce the heat energy demand and thus improve the energy saving efficiency

• 한국항공우주학회지
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• 제46권3호
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• pp.257-268
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• 2018

본 논문은 한국형 전투기 개발 시 적의 위협에 대한 취약성 분석을 위해 요구되는 고속 관통자가 표적을 관통하는 기구에 대해 수치 해석적으로 연구한 결과이다. 표적은 1 mm~6.3 mm 두께를 갖는 준 무한평면의 알루미늄(Aluminum) 2024 재질을 고려하였다. 관통자는 반구형 노즈 형상을 갖는 강(steel) 재질로, 입사속도는 350~3353 m/s까지, 질량은 0.32~16 g까지 갖는 것으로 고려하였다. 수치해석을 위해 사용된 실 사격 데이터는 THOR 방정식으로부터 추정하여 유추하였다. 수치해석 결과 표적을 관통하는 과정에서 관통자의 탄도한계속도는 관통자의 질량에 대한 지수 함수적으로 감소하는 수식으로 형식화(closed form of formalization) 하였다. 관통 후 잔류속도 및 잔류질량은 표적의 두께와 관통자의 질량 및 입사속도에 의존된 지수 함수적으로 감소하는 수식으로 각각 형식화하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.17-20
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• 2006

Korean traditional houses have been developed in sympathy with natural environment and formed comfortable indoor condition by properly using surrounding natural resources including building layout, space construction and material our traditional wooden windows adjusting ambient temperature and humidity have both the functions of window and door, although they are clearly divided in the West. While window paper is attached from the outside in China and Japan, it is attached from the inside in Korea. The opening and closing mode of windows is similar and their dimensions are shown not to he standardized but diverse in terms of the characteristic of wooden furniture and that of components placed between columns. Thus this study is to look into the performance of band-lattice door of a typical traditional one by observing changes in sound absorption characteristics according to difference in thickness and finishing method of window paper and those in sound absorption characteristics with the changed thickness of air layer in traditional windows and doors.