• Proceedings of the KIPE Conference
• /
• 2006.06a
• /
• pp.191-193
• /
• 2006

The various wind turbines have been designed and developed for the century. The precision design of the blade and turbine system considering the wind circumstance is required for the high efficiency. In this paper, we investigated the output characteristics of the horizontal and vertical wind turbine related to the wind velocity. Furthermore we will intend to design the wind turbine blade adapted the urban wind circumstance.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.1185-1186
• /
• 2006

The wind turbines of various designs have been manufactured and operated for many years. The design considering the wind circumstance is required for the high efficient wind turbine, because the efficiency and characteristics of the wind turbines depends on the designs and structure of it's system. In this paper, a analysis on the output characteristic of the wind turbine according to wind velocity was performed. The results of the analysis data is desired to be used on the high efficient blade design.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.1
• /
• pp.21-26
• /
• 2015

This study represents the effective fire and smoke control in the case of fire in deep underground tunnels, even if the exhaust system can be calculated, the optimal smoke capacity can be determined by establishing technical standards for the transverse ventilation system focusing on the design as a basis for deriving the parameters for utilization. Numerical analyses were performed using the FDS program as a function of the unsteady flow in a deep underground tunnel fire. The analysis results were calculated within 250 m smoke using an inside wind velocity of 0m/s when the capacity of smoke was exhausted, $80m^3/s$, whereas in case of an internal wind velocity of 3m/s, the capacity of smoke exhaust was $197.1m^3/s$, showing an approximately 2.5 fold increase.

• Journal of Korean Society of Steel Construction
• /
• v.21 no.6
• /
• pp.553-561
• /
• 2009

Risk analysis of highway sign supporting structures and sound barriers was done. Stochastic wind load was modeled by using extreme value distribution from site measurement and the variability of structural parameters was considered. Limit state functions were defined to assess structural stability by wind and risk of highway facilities was analyzed by combining wind hazard. According to the numerical analysis results, sound barrier post shows significantly higher risk than highway sign supporting structures. This is caused by the fact that the design codes of the structures are different. To distribute wind induced risk in highway structures, unification and improvement of design codes are required based on risk assessment.

• Journal of the Korea Concrete Institute
• /
• v.17 no.4 s.88
• /
• pp.551-558
• /
• 2005

The setting and hardening of concrete is accompanied with nonlinear temperature distribution caused by development of hydration heat of cement. Especially at early ages, this nonlinear distribution has a large influence on the crack evolution. As a result, in order to predict the exact temperature history in concrete structures it is required to examine thermal properties of concrete. In this study, the convection heat transfer coefficient which presents thermal transfer between surface of concrete and air, was experimentally investigated with variables such as velocity of wind, curing condition and ambient temperature. At initial stage, the convection heat transfer coefficient is overestimated by the evaporation quantity. So it is essential to modify the thermal equilibrium considered with the boiling effect. From experimental results, the convection heat transfer coefficient was calculated using equations of thermal equilibrium. Finally, the prediction model for equivalent convection heat transfer coefficient including effects of velocity of wind, curing condition, ambient temperature and boiling effects was theoretically proposed. The convection heat transfer coefficient in the proposed model increases with velocity of wind, and its dependance on wind velocity is varied with curing condition. This tendency is due to a combined heat transfer system of conduction through form and convection to air. From comparison with experimental results, the convection heat transfer coefficient by this model was well agreed with those by experimental results.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.7
• /
• pp.922-930
• /
• 2020

Marine accidents involving fishing boats, caused by a loss of stability, have been increasing over the last decade. One of the main reasons for these accidents is a sudden wind attacks. In this regard, the wind loads acting on the ship hull need to be estimated accurately for safety assessments of the motion and maneuverability of the ship. Therefore, this study aims to develop a computational model for the inlet boundary condition and to numerically estimate the wind load acting on a fishing boat. In particular, wind loads acting on a fishing boat at the wind speed profile boundary condition were compared with the numerical results obtained under uniform wind speed. The wind loads were estimated at intervals of 15° over the range of 0° to 180°, and i.e., a total of 13 cases. Furthermore, a numerical mesh model was developed based on the results of the mesh dependency test. The numerical analysis was performed using the RANS-based commercial solver STAR-CCM+ (ver. 13.06) with the k-ω turbulent model in the steady state. The wind loads for surge, sway, and heave motions were reduced by 39.5 %, 41.6 %, and 46.1 % and roll, pitch, and yaw motions were 48.2 %, 50.6 %, and 36.5 %, respectively, as compared with the values under uniform wind speed. It was confirmed that the developed inlet boundary condition describing the wind speed gradient with respect to height features higher accuracy than the boundary condition of uniform wind speed. The insights obtained in this study can be useful for the development of a numerical computation method for ships.

• Fire Science and Engineering
• /
• v.22 no.3
• /
• pp.201-207
• /
• 2008

In this study, three Dimensional CFD simulations were carried out to investigate the effective smoke extraction system in bi-directional road tunnel fires using FLUENT. Characteristics of transverse system with big size extraction port or with uniform extraction port, semi-transverse system and longitudinal system for smoke extraction system were analyzed. Air velocity, port size, and operating method were used with variable. Distributions of smoke spread, CO was analyzed. As a result, the transverse ventilation system with big size port was found to be more effective than the uniform ports for bi-directional road tunnel.

• Journal of Bio-Environment Control
• /
• v.18 no.3
• /
• pp.215-224
• /
• 2009

A survey on the actual state of heating, cooling, ventilation, and air-flow and experimental measurement of temperature and humidity distribution in tomato greenhouse were performed to provide fundamental data required in the development of air-flow control technology. In single-span plastic houses, which account for most of 136 tomato greenhouses surveyed, roof windows, ventilation and air-flow fans were installed in a low rate, and installation specs of those facilities showed a very large deviation. There were no farms installed greenhouse cooling facilities. In the hot air heating system, which account for most of heating type, installation specs of hot air duct showed also a large deviation. The exhaust air temperature and wind speed in hot air duct also were measured to have a big difference depending on the distance from the heater. We are using the maximum difference as indicator to determine whether temperature distribution is uniform. However if the temperature slope is not identical in greenhouse, it can't represent the uniformity. We analyzed relation between the maximum difference and the uniformity of temperature and humidity distribution. The uniformity was calculated using the mean and standard deviation of data from 12 measuring points. They showed high correlation but were represented differently by linear in the daytime and quadratic in the nighttime. It could see that the uniformity of temperature and humidity distribution was much different according to greenhouse type and heating method. The installation guidelines for ventilation and air-flow fan, the spread of greenhouse cooling technology for year-round stable production, and improvement of air duct and heating system, etc. are needed.

• Korean Journal of Plant Resources
• /
• v.27 no.5
• /
• pp.546-555
• /
• 2014

The final aim of this study is to develop a biofiltration system integrated with plant vegetation for improving indoor air quality effectively depending on indoor space and characteristics. However, to approach this final goal, several requirements such as constant pressure drops (PDs) and soil moisture contents (SMCs), which influence the capacity design for a proper ventilation rate of biofiltration system, should be satisfied. Thus, this fundamental experiment was carried out to adjust a proper wind speed and to ensure a stabilization of initial SMCs within biofilter for uniform distribution of SMCs and PDs, and for normal plant growth, especially avoiding root stress by wind. Therefore, we designed horizontal biofliter models and manufactured them, and then calculated the ventilation rate, air residence time, and air-liquid ration based on the biofilter depending on three levels of wind speed (1, 2, and $3cm{\cdot}s^{-1}$). The relative humidity (RH) and PD of the humidified air coming out through the soil within the biofilter, and SMC of the soil and plant growth parameters of lettuce and duffy fern grown within biofilter were measured depending on the three levels of wind speed. As a result of wind speed test, $3{\cdot}sec^{-1}$ was suitable to keep up a proper RH, SMC, and plant growth. Thus, the next experiment was set up to be two levels of initial SMCs (low and high initial SMC, 18.5 and 28.7%) within each biofilter operated and a non-biofiltered control (initial SMC, 29.7%) on the same wind speed ($3cm{\cdot}sec^{-1}$), and measured on the RH and PD of the air coming out through the soil within the biofilter, and SMC of the soil and plant growth parameters of Humata tyermani grown within biofilter. This result was similar to the first results on RHs, SMCs, and PDs keeping up with constant levels, and three SMCs did not show any significant difference on plant growth parameters. However, two biofiltered SMCs enhanced dry weights of the plants slightly than non-biofiltered SMC. Thus, the stability of this biofiler system keeping up major physical factors (SMC and PD) deserved to be adopted for designing an advanced integrated biofilter model in the near future.

• Proceedings of the KAIS Fall Conference
• /
• 2010.11b
• /
• pp.944-946
• /
• 2010

열교환기는 공조 및 기타 산업현장에서 많은 수요가 창출되고 있는데 본 논문에서는 3차원 수치해석을 이용하여 수송기계의 오일쿨러나 연료쿨러에 쓰이는 전형적인 열교환기에 대한 방열 성능을 해석하였다. 열교환기의 핀 타입 중 wavy 및 louver에 대하여 열교환기 성능 실험 데이터를 이용하는 3차원 열교환기 모델을 완성하고 통과 풍량에 따른 열교환량을 예측하였다. 이는 열교환기를 통과하는 풍속이 균일하지 않을 때 열교환량을 예측할 수 있어 설계 정확성 향상에 기여할 수 있다.