• 한국태양에너지학회 논문집
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• 제28권4호
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• pp.68-75
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• 2008

The purpose of this research is revise the value yield to compensate of measure the difference between computer simulation and the measurement value on the two methods which can calculates thermal performance. The way is need to understand about thermal performance, air tightness, simulations and comparisons of analysis to influence the value of each identified. The opening type of the windows and doors to be used at the analysis are T/T, L/S and SL Different condition of the windows and doors excluded except the opening type. Each of the four samples was selected by the way of opening. Result of the analysis of the difference between measurement and simulation are that T/T approach 5.3%, L/S approach 15.7%, SL approach 21% and the more air-tightness guarantees less difference of the numerical value. Each compensation value calculates by the correlation regression analysis and the air-tightness data. After the compensation of the resulting difference in T/T, L/S, SL indicate 5.4%, 2.5%, 1.0% respectively.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.102-107
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• 1996

The blowdown transient pipe flows resulting from the actuation of the safety/relief valve (SRV) under valve opening conditions have been analyzed. The analytical model has been developed for a uniform pipe with friction through which the flow is discharged into a suppression pool in case of a sudden opening of the SRV The piping flow characteristics and dynamic loads are calculated. Effects of system pressure, pipe length and submergence depth are included.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.191-198
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• 1997

The subject of this thesis is the vibration response of framed structure for buildings of "damed beam" type. In steel rigid frame with damped beams, web plate in mid span of beams is perforated to form a rectangular opening, only upper and lower flanges being remained. When the frame is subjected to horizontal seismic forces, dominant shearing deformation takes place in the opening part of the beams. Energy absorber in stalled in the opening is driven by relative displacement caused by the shearing deformation and provide the frame with damping force. First, static deformation of portal frames having a beam with the web opening is discussed and formulas of elastic deformation is derived.s derived.

• 설비공학논문집
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• 제22권7호
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• pp.460-467
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• 2010

In housing units constructed recently in Korea, the length of ondol coil is different in each room, so the flow rate of hot water is adjusted by setting valve opening. If the flow rate is not appropriate for heating load, the room temperature seriously deviates from the set temperature range for comfort. In particular, too small valve opening can induce a noise by cavitation. In order to adjust the valve opening, two methods by zone area and a new method by return temperature rise were modelled and simulated using TRNSYS and EES. As a result, heating energy consumption during one week was the same on three methods, but the room temperature of the new method minimally deviated from the range of set temperature with a low possibility of noise.

• 한국안전학회지
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• 제30권6호
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• pp.18-25
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• 2015

Computational study of a gravity current prior to the backdraft was conducted using fire dynamic simulator (FDS). Various initial conditions of mixture compositions and compartment temperature as well as four opening geometries (Horizontal, Door, Vertical, and Full opening) were considered to figure out their effects on the gravity current. The density difference ratio (${\beta}$) between inside and outside of compartment, the gravity current time ($t_{grav}$) and velocity ($v_{grav}$), and non-dimensional velocity ($v^*$) were introduced to quantify the flow characteristics of the gravity current. Overall fluid structure of the gravity current at the fixed opening geometry showed similar development process for different ${\beta}$ conditions. However, $t_{grav}$ for entering air to reach the opposed wall to the opening geometry increased with ${\beta}$. Door, Vertical, and Horizontal openings where openings are attached on the ground showed similar development process of the gravity current except for Horizontal opening, which located on the middle of the opening wall. The magnitude of $v_{grav}$ at fixed ${\beta}$ was, from largest to smallest, Full > Vertical > Door > Horizontal, but it depended on both the size and location of the opening. On the other hand, $v^*$ was found to be independent to ${\beta}$, and only depended on the geometry of the opening.

• 한국구조물진단유지관리공학회 논문집
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• 제25권5호
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• pp.76-85
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• 2021

이 연구에서는 유공보강근의 형상에 따른 RC 유공보의 구조성능을 평가하기 위하여 전단실험을 수행하였다. 실험체는 총 4체이며, 주요변수는 유공의 유무, 유공 보강 유무, 유공 보강근의 형상이다. 이 연구에서는 사각형과 팔각형이 혼합된 나선형의 유공보강근을 개발하였으며, 이를 기존 Band형과 비교하였다. 실험결과, 제안 유공 보강근으로 유공을 보강한 실험체는 타 실험체에 비하여 최대 전단력과 최대 전단력 이후 에너지소산면적이 증가하는 것으로 나타났다. 따라서 제안 유공 보강근은 유공 주위의 균열제어와 함께 전단성능의 향상에 효과적임을 확인하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제12권4호
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• pp.36-40
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• 2010

In this paper, a noble method for rapid cooldown of pulse tube refrigerator (PTR) was proposed and experimentally investigated. An orifice pulse tube refrigerator generates refrigeration effect by expansion PV work at the cold-end, and its amount is affected by the orifice valve opening. There exists the optimum valve opening for maximum cooling capacity and it varies as cold-end temperature. It is verified from simulation results using isothermal model that the optimum valve opening increases as the cold-end temperature increases. In the experiments, a single stage orifice pulse tube refrigerator is fabricated and tested. The fabricated PTR shows 97.5 K of no-load temperature and 10 W at 110 K of cooling capacity with the fixed orifice valve opening. From experiments, the initial cooldown curve with four cases of valve opening control scenario are obtained. And it is experimentally verified that the initial cooldown time can be reduced through the control of orifice valve opening.

• International Journal of Concrete Structures and Materials
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• 제18권3E호
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• pp.191-198
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• 2006

The objective of this study is to examine fracture characteristics of concrete at early ages, i.g. critical stress intensity factor, critical crack-tip opening displacement, fracture energy, and bilinear softening curve based on the concepts of effective-elastic crack model and cohesive crack model. A wedge splitting test for Mode I was performed on cubic wedge specimens with a notch at the edge. By experimenting with various strengths and ages, load-crack mouth opening curves were obtained, and the results were analyzed by linear elastic fracture mechanics and FEM(finite element method). The results from the test and analysis showed that critical stress intensity factor and facture energy increased while critical crack-tip opening displacement decreased with concrete aging from 1 day to 28 days. Four parameters of bilinear softening curve from 1 day to 28 days were obtained from a numerical analysis. The obtained fracture parameters and bilinear softening curves at early ages from this study are to be used as a fracture criterion and an input data for the finite element analysis of concrete at early ages.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.177-185
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• 2022

Hydrogen risk in the containment filtered venting system (CFVS) vessel was analyzed, considering operation pressure and modes with the effect of PAR and accident scenarios. The CFVS is to depressurize the containment by venting the containment atmosphere through the filtering system. The CFVS could be subject to hydrogen risk due to the change of atmospheric conditions while the containment atmosphere passes through the CFVS. It was found that hydrogen risk increased as the CFVS opening pressure was set higher because more combustible gases generated by Molten Core Concrete Interaction flowed into the CFVS. Hydrogen risk was independent of operation modes and found only at the early phase of venting both for continuous and cyclic operation modes. With PAR, hydrogen risk appeared only at the 0.9 MPa opening pressure for Station Black-Out accidents. Without PAR, however, hydrogen risk appeared even with the CFVS opening set-point of 0.5 MPa. In a slow accident like SBO, hydrogen risk was more threatening than a fast accident like Large Break Loss-of-Coolant Accident. Through this study, it is recommended to set the CFVS opening pressure lower than 0.9 MPa and to operate it in the cyclic mode to keep the CFVS available as long as possible.

• 한국수소및신에너지학회논문집
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• 제29권4호
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• pp.370-377
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• 2018

Ball valve has been widely used in the field of high-pressure gas pipeline as an important component because of its low flow resistance and good leakage performance. The present paper focuses on the flow nature at the downstream of the ball valve used for gas pipelines according to valve opening rates. Steady 3-D RANS equations, SC/Tetra, have been introduced to analyze the flow characteristics inside the ball valve. Numerical boundary conditions at the inlet and outlet of the valve system are imposed by mass flow-rate and pressure, respectively. Velocity distributions obtained by numerical simulation are compared with respect to the valve opening rates of 30, 50, and 70%. Cavity distributions, asymmetry flow velocity and the flow stabilization point at each opening rate are also compared. When the valve opening rates are 30 and 50%, the flow stabilization requires the sufficient length of 10D or more due to the influence of the recirculation flow at the downstream of the valve.