각형 출입구를 갖는 방호터널의 방폭밸브에 미치는 폭압 평가

방승기,신진원 한국 지열 · 수열에너지학회 2021 한국지열에너지학회논문집 Vol.17 No.4

This paper presents a study to reduce the effect of blast pressure on the blast valves installed in protection tunnels, where the shape of the tunnel entrance and the blast pocket is optimized based on the predetermined basic shape of the protective tunnels. The reliability of the numerical tunnel models was examined by performing analyses of mesh convergence and overpressure stability and with comparison to the data in blast-load design charts in UFC 3- 340-02 (DoD, 2008). An optimal mesh size and a stabilized distance of overpressure were proposed, and the numerical results were validated based on the UFC data. A parametric study to reduce the blast overpressures in tunnel was conducted using the validated numerical model. Analysis was performed applying 1) the entrance slope of 90, 75, 60, and 45 degrees, 2) two blast pockets with the depth 0.5, 1.0, and 1.5 times the tunnel width, 3) the three types of curved back walls of the blast pockets, and 4) two types of the upper and lower surfaces of the blast pockets to the reference tunnel model. An optimal solution by combining the analysis results of the tunnel entrance shape, the depth of the blast pockets, and the upper and lower parts of the blast pockets was provided in comparison to the reference tunnel model. The blast overpressures using the proposed tunnel shape have been reduced effectively.

CFD를 이용한 연도 shaft의 열전달 해석 및 온도저감 방안

방승기 청운대학교 건설환경연구소 2012 청운대학교 건설환경연구소 논문집 Vol.7 No.2

This research investigated how the heat from chimneys of the central shafts in buildings had affected neighboring households. In examining the issue, we used data from thirty-five storied apartments with three storied basements. The basements accommodated a multiplex theater, a great shopping mall, seven absorption chillers, and six hot-water boilers. To reduce emission air temperatures from the chimneys, we installed heat recovery system. Then, using the interpretation results of computer fluid dynamics, we estimated temperature distributions by measuring emission air temperatures and the heights of apartments. According to the experiments, the relationship between air temperature and height could be estimated as 0.26×height+32.67 for the dataset with the emission gas temperature 220℃ and the gas speed 1.5m/s. In comparison, the relationship was again estimated as 0.84×height+17.57 for the experiment with the emission gas temperature of 120℃ and the gas speed of 1.5m/s. We obtained very high coefficients of determination in both cases. 본 연구에서는 고층아파트 건물 중앙부분의 shaft에 설치된 굴뚝에서 발생되는 열이 인접세대에 미치는 영향을 파악하였다. 연구 대상건물은 서울에 위치한 지하 3층, 지상 35층의 공동주택으로 기계실은 지하 3층에 위치하고 있다. 기계실에는 공동주택과 같은 단지 내에 있는 영화관(멀티플렉스), 대형 할인매장 및 임대매장의 냉난방을 위한 흡수식 냉온수기 7대, 급탕보일러 6대가 있다. 굴뚝으로 배기되는 배기가스의 온도를 낮추기 위해서 각 장비에 폐열회수장치를 설치하고 배기가스의 온도에 따라 공동주택에서 높이에 따른 온도분포를 예측하는 식을 CFD 해석결과를 이용하여 작성하였다. 예측결과 배기가스의 온도가 220℃고 배기속도가 1.5m/s인 경우 연도 샤프트의 높이에 따른 온도는 0.26×height+32.67로 표현할 수 있으며, 이때 결정계수는 0.986으로 매우 높게 나타났다. 또한 배기가스의 온도와 배기속도가 120℃, 1.5m/s인 경우는 샤프트 내부의 온도는 0.84×height+17.57로 높이에 따른 연도 shaft의 온도를 표현할 수 있으며, 이때 결정계수는 0.987로 나타났다.

환기회수 및 부하율 변화에 따른 휘발성유기화합물 농도 감쇠 예측에 관한 연구

방승기,손장열,안병욱 대한설비공학회 2005 설비공학 논문집 Vol.17 No.6

We measured the time-dependent concentration of VOCs emitted from Ondol floor, furniture, and the wall made of various building materials. After obtaining results from the previous measurement, we developed the estimation equations of the concentration decay, and obtained the estimated graphs for the concentration decay under different air change rates and loading factor conditions by using the estimated equations. We conducted our tests by applying our measurements to real residences for 110 days in the case of furniture and for 40 days in the case of the floor. We also conducted experiments in the cases of various wall materials for 7 days which totaled 10 times. We used the GC/FID for experiments for real residences according to the specified procedures of the NIOSH 1501, and carried out experiments for wall materials according to the specified procedures of the ASTM 5116-97. When conducting experiments for wall materials, we set the temperature and relative humidity at 23℃ and 50%, respectively. We also set the air change rate and loading factor at 0.7/h and 1.617 m2/m3, respectively.Our results showed that it is possible to predict proplrly the time-dependent concentration decay of VOCs by using logarithmic functions in both cases of experiments for real residences and for wall materials. Furthermore, we found that the concentration decay rate of VOCs increased rapidly as the air exchange rate increased while the concentration decay rate decreased as the loading factor increased.

설계단계에서 건축물의 종합성능 평가 사례 연구 -청소년 수련관의 LCC, 음향성능, 피난성능 평가를 중심으로-

방승기,이철구,백용규,조현 한국생활환경학회 2005 한국생활환경학회지 Vol.12 No.4

We carried out this research in order to examine life-time cost of the building after its completion, its acoustical performance, and the time required for evacuation in the event of a fire. Our research was based on the data obtained from buildings for teenagers. We obtained the following results. First, the analysis of the total cost estimates showed that the most economical case was the case when we used a hot and chilly water generator. Second, the simulation results from an auditorium experiment indicated that the reverberation time at 500 Hz was 1.34 seconds when all seats were not occupied whereas it reached 1.1 seconds when all seats were occupied. The differences between the calculated RTs and target RTs were respectively 0.04 and 0.02 seconds. Third, we found that the sound pressure level was relatively uniform because it was located within 4 dB. Fourth, simulation results showed that the ZONE 3 turned out to be most effective because its occupants were able to go through each emergency exit within regulated time.

Characteristics of Volatile Organic Compounds Emitted in Building Materials and Their Predictions of Time-dependent Variation

방승기,이광호,손장열 대한건축학회 2005 Architectural research Vol.7 No.1

Unlike other countries, Korea uses various kinds of wall-paper as finishing material. Conventional wall-paper consists of paper and vinyl, and petrochemical ink is used for the decoration of the surface. Adhesive is used to paste the wall with the wall-paper, which emit substantial amounts of VOCs and formaldehyde. In this study, VOCs characteristics emitted from specimens made of concrete, mortar, gypsum board and wall-paper were investigated using small chamber method. Moreover, concentration and emission factor of BTEX(Benzene, Toluene, Ethylbenzene, m,p,o-Xylene) and TVOC were investigated, and concentration and emission factor decay were estimated. As a result of the prediction, both time-dependent concentration decay and cumulative concentration can be converted into the logarithmic scale. Furthermore, prediction equations were developed from the experimental results under accurately controlled experimental conditions. Therefore, there may be difference if the estimated equations are directly applied to real buildings. Further research should be done on the generalization of the developed prediction equations.

온돌용 마루와 가구에서 발생하는 휘발성유기화합물(VOCs) 농도 감소 예측에 관한 연구

방승기,손장열,박병윤 대한건축학회 2005 대한건축학회논문집 Vol.21 No.6

In this study, Ondol floor and furniture were installed in a real residence in order to measure the indoor VOCs concentration. The study was conducted in order to develop the concentration decay prediction equation of indoor BTEX (Benzene, Toluene, Ethylbenzene, Xylene) using the measured results. In addition, the graph of concentration decay of each pollutant with the variation of indoor air exchange rate was drawn up using the prediction equation. As a result, the conclusions were obtained as follows. (1) When the time-dependent concentration decay of BTEX(Benzene, Toluene, Ethylbenzene, Xylene) after the installation of floor in a real residence was estimated, the prediction equation can be expressed as logarithmic function. (2) In case of the floor, it is found that using the cumulative values of concentration measured by hours is more accurate than using the non-cumulative values, and the time-dependent indoor concentration of benzene can be estimated as 408.52(1-e-0.0031*time) with the R2 of 0.94 which is significantly high value. (3) In case of the floor, the indoor concentration of each pollutant is found to decrease rapidly as the air exchange rate rises, and it can be estimated as linear function.

신축 아파트의 실내 마감재 변경 및 시공단계별 휘발성유기화합물 발생 특성

방승기,조우진,손장열 대한설비공학회 2006 설비공학 논문집 Vol.18 No.6

In this research, IAQ is measured to evaluate the emission performance of VOCs in three new apartment houses finished by totally EFMs(Environmental Friendly Material), partially installed EFMs and general materials. Among various VOCs, Target pollutants for the IAQ measurement are benzene, ethylbenzene, toluene, xylene, 1,4-Dichlorobenzene and formaldehyde. The measurement is conducted one day after each interior finishing material is worked over by construction schedule. The result of this research concluded that (1) Except toluene, the concentration levels of each pollutant did not exceed the national IAQ standards in all test residences, (2) As the interior finishing work schedule, A toluene level peaked when the furniture installing was ended. (3) The toluene concentration level of the house installed general interior materials as the non-EFMs furniture was one and half higher than other houses. Consequently, installing the furniture made by EFMs is one of effective methods to improve the IAQ for new apartment houses.

Bake-Out에 의한 신축 아파트의실내 오염물질농도 저감효과 평가

방승기,박병윤 대한설비공학회 2006 설비공학 논문집 Vol.18 No.4

Indoor air pollution has been significantly aggravated due to hazardous pollutants emitted from petrochemical finishing materials in new apartments. Pollutants emitted into indoor environment have significant effects on the health of occupants, causing undesirable symptoms related to sick building syndrome such as headache, dizziness, difficulty in concentration, etc. Therefore, this paper attempted to investigate the reduction effect of bake out on VOCs emission in new apartments. Experiments were carried out in three households, one of which was naturally ventilated. The naturally ventilated showed the lowest indoor pollutant concentration and also showed the highest reduction rate by the use of bake out. The most desirable result was observed when the household was naturally ventilated after bake out. More detailed experiments are expected to be carried out afterwards on the prediction of reduction rate of each pollutant.

대판신건물 설비의 현대화 진행과정 -기획계획 컨셉/설계검증사례-

방승기 대한설비공학회 2000 설비저널 Vol.29 No.5

설계단계에서의 화재 및 피난성능 평가

방승기,조현 한국방재학회 2009 한국방재학회지 Vol.9 No.3