The flow acting on a confined jet flow can be represented as a conventional turbulence flow with its complex phase and characteristics. This is still effectively applied in a variety of industries, for example in ejectors. In this study coaxial confined model made of transparent acrylic pipe and driving water nozzle in order to figure out of recirculation flow near the wall of pipe and prove how flow in the pipe can be developed. It was revealed that length of the recirculation flow adjacent to wall of pipe was characterized to be larger when Reynolds Number is getting bigger.

In this study, the heat flow characteristics of natural convection was theoretically analyzed with time by changing various locations of heat trace with tube surface about enclosed circular tube by applying nominal tube diameter 90 mm of KS D 3507. Before carrying out CFD (Computational Fluid Dynamics) analysis, it is presumed that the boundary condition is the tube’s inside and outside fluid temperature of 273 °K, the tube surface heat flux according to the heat trace location of 16 W/m. The result confirmed that water of inside tube is occurred natural convection caused by density difference depending on temperature profile. Additionally, in case of heat trace location, the heat transfer and flow characteristics showed clearly that two-heat trace location =135° and 180° was more favorable distribution than one-heat trace appropriate location =135°.

This study involved the shape of water jet nozzle to promote blasting ability and an increase of projection distance when cleaning VLBC cargo hold. Simulation of water jet projection process inside VLBC cargo hold was done in both 2D and 3D environment. The result are promising since both case show the capability of water contacting the desired target.

Flow visualization of Butterfly valve is tested five cases(15°, 30°, 45°, 60° and 90°) of vlave opening angle. Measurement by the PIV(Particle Image Velocimetry) was conducted to investigate the flow characteristics of butterfly valve about discharge of dam.. Flow behaviors such as instantaneous and time-mean velocity vectors are investigated each cases. The results from flow visualization using PIV through the video which do not contain a cavitation phenomenon was confirmed in accordance with the valve opening. Performs valve opening and the flow properties of the Karman vortex generated by the frequency analysis is 90° was calculated the frequency of the butterfly valve applied to the actual dam. Butterfly valve for the emergency discharge valve is susceptible to cavitation caused by the valve opening 90° and repeat the cycle in the valve side of the vortex emission system is a high possibility of damage due to fatigue.

The study on ice thermal storage system is to improve total system performance in actual air-conditioning facilities. This paper deals with experimental research to observe the characteristics of heat flow and the effect of ice thermal storage in case of three sizes of ice ball, which are included identification of ice thermal extraction. Diameters of three ice ball was 103mm, 96mm, and 76mm is equivalent to 0.45, 0.50 and 0.55 in porosity respectively. Also inlet geometric parameters are the perforator and distributor. Flow rate of brine were 2LPM, 4LPM and 6LPM and the temperature difference in dynamic parameter are 8℃, 10℃ and 12℃. Flow rate of brine used the liter per minute(LPM) for liquid measurement applications. The effect of brine flow rate on efficiency increased as the temperature difference and porosity increased. An adaption of a long-term storage in case of smaller porosity(ɛ=0.45) was available through experiments of outlet temperature responses.

To perform long-term sewer monitoring, It is important to understand the nature of the wastewater flow that occurs at the point on early stage of the monitor and to prevent in advance a problem which may caused. We can infer the flow properties and external factors by analyzing the scatter graph obtained from the measured data flow rate monitoring data since an field external factor affecting the sewage flow is reflected in the flow rate monitoring data. In this study, Selecting the three points having various external factors, and we Inferred the sewer flow characteristics from depth-velocity scatter graph and determined the analysis equation for the dry-weather flow rate data. At the‘point 1’expected non-pressure flow, we were able to see the drawdown effect caused by the free fall in the manhole section. At the‘point 2’, existed weir and sediments, there was backwater effect caused by them, and each of size calculated from the scatter graph analysis were 400 mm and 130 mm. At the‘Point 3’, there is specific flow pattern that is coming from flood wave propagation generated by the pump station at upstream. In common, adequate equations to explain the dry weather flow data are flume equation and modified manning equation(SS method), and the equations had compatibility for explaining the data because all of R2 values are over 0.95.

We have performed CFD simulation and analyzed flow and concentration fields for the basic data of the ventilation system for removing pollutants which were produced in a lecture room. The flow patterns indicated differently according to the arrangement of openings and the concentration distribution of pollutants were showed higher and lower because of the effect of that flow patterns. In the case of arranging the openings to the upper and lower side, the stagnation appearance of flow formed in the interested space. In the case of arranging the openings to the right and left side, the stagnation of high concentration pollutants appeared in the middle area of the interested space. On the increasing exhaust velocity, the distribution of pollutants appeared similar to the normal case, but the concentration of pollutants were lower.

본 연구는 기존의 게임에 대한 전반적인 부정적 인식에서 벗어나 긍정적인 측면에서 스마트폰 게임을 살펴볼 필요성이 있다고 판단하여 심리적인 측면에서 스마트폰 게임 이용동기와 게임특성이 게임몰입에 미치는 영향을 살펴보았다. 주요 결과를 제시하면, 스마트폰 게임 이용동기는 현실도피, 기분전환, 즐거움, 몰입, 성취 등으로 나타났고, 이 중 현실도피를 제외한 기분전환, 즐거움, 몰입, 성취가 스마트폰 게임몰입에 유의미한 정적 영향을 주는 것으로 나타났다. 따라서 스마트폰 게임 이용자들이 기분전환, 즐거움, 몰입, 성취동기를 추구할수록 게임몰입도 높아지는 것으로 평가할 수 있다. 둘째, 스마트폰 게임특성 중 게임구성, 조작용이성을 제외하고 게임의 생동감은 게임몰입에 유의미한 정적 영향을 미치는 것으로 나타났다. 그러므로 스마트폰 이용자들이 게임을 통해 생동감을 높게 지각할수록 게임몰입이 높아지는 것으로 평가된다. 이상과 같은 결과를 통해 몰입 자체가 건전한 심리작용이고, 스트레스를 해소하거나 여가시간을 즐겁게 보내는데 일정 부분 기여함을 전제로 한다면, 스마트폰 게임 이용이 스트레스를 해소하고 여가시간을 보다 즐겁고 재미있게 보내는데 있어 긍정적으로 작용할 수 있을 것이다. 나아가 일정부분 여가문화 차원으로 활용할 수 있음을 시사한다.

본 연구에서는 수중 삼각형상구조물의 경사도와 레이놀즈 수 변화에 따른 구조물 주위의 유동특성을 분석하였다. 모델링한 삼각형상구조물 주위의 유동장은 회류수조에서 가시화실험과 입자영상유속계(PIV)를 이용하여 계측하였다. 실험결과 경사각이 45°인 삼각형상구조물이 레이놀즈 수 Re=2.9×10³에서 구조물 높이의 2.7배까지 상승하는 속도성분이 나타났다. 레이놀즈 수가 일정할 때 경사각이 클수록 구조물 후방에 하강하는 속도성분이 크게 나타났고, y/hs=1.75이상의 영역에서는 경사각과 레이놀즈 수가 구조물 후방의 유동형태에 변화를 주지 않았다.

In this paper, we analyzed the characteristics of the mass flow rate and velocity of the refrigerant in response to a change in the number of holes and the diameter size(Type-1～4) of the valve guide refrigerant to flow from Pc to Ps when the pressure is constant. Type-1 is 40% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-2 is 64% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-3 is 50% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-4 is 47% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate.

A 2D axisymmetric numerical analysis was performed to study the characteristics of charge process inside solar thermal storage tank. The porosity and heat transfer coefficient of filler material as well as inlet velocity of heat transfer fluid are selected as simulation parameters. The porosity is varied as 0.2, 0.5, and 0.8 to account for the effect of filler granule geometry. Two levels of the heat transfer coefficient is adopted to assess the heat transfer between heat transfer fluid and filler material. The inlet velocity is varied as 0.00278, 0.0278, and 0.278m/s. As both of the porosity and the heat transfer coefficient increase, the discrepancy of the temperature distributions between the filler and heat transfer fluid decreases. As the inlet velocity increases, the penetration depth of the heat transfer fluid increases proportionally.

The water distribution system should be invariably operated on continuous pattern for 24 hours a day. Occasionally, it is not practically possible to operate for 24 hours due to water shortage or financial constraints. Therefore an intermittent water supply is unavoidable in water shortage area and developing countries.But the intermittent water supply can introduce large pressure forces and rapid fluid accelerations into a water supply network. These disturbances may result in new pipe failure, leakage and secondary contamination.This paper proposed an improvement methodology to prevent the disturbances by intermittent water supply. For the study, the hydraulic variation of intermittent flow in water distribution system was measured and analyzed in the field by comparing with simulation of hydraulic model. Installations of control valves such as, pressure reducing and sustaining and air valves were employed for pressure and flow control. The effectiveness of the methods are presented by comparing hydraulic conditions before and after introducing the proposed solutions.

극저온 액체 상태의 LNG는 주거용과 산업용으로 공급되기 전에 가스 상태로 변환된다. 이러한 재가스화 과정 중에 LNG는 83.7×104 kJ/kg 정도의 많은 냉열에너지를 제공한다. 이 냉열에너지를 일부 선진국들에서는 질소, 수소, 헬륨과 같은 극저온 유체들의 액화, 제빙 및 냉방시스템에 이용하고 있다. 따라서 우리나라에서도 인천, 평택 및 통영 LNG 인수기지 주변에 LNG의 냉열에너지를 이용한 냉열에너지 회수시스템을 설립할 필요가 있다. 여기서는 저열유속상태에서 상변화를 동반하는 LNG의 유동거동 특성을 파악하기 위해 LNG의 85 %를 차지하는 메탄을 작동유체로 사용하였다. 또한 본 논문은 극저온 열교환기 내부를 흐르는 메탄과 질소, 프로판, R11 및 R134a의 유동경계에 영향을 주는 관 직경, 관의 경사각도 및 포화압력의 효과를 보여준다. 또한 여기서 얻어진 이론적 연구결과와 기존의 실험 데이터와도 비교 되었다. 그리고 메탄의 유동경계에 주는 파이프의 경사각도의 영향은 매우 큼을 알 수 있었다.

In this study, numerical simulation has been conducted to investigate flow characteristics in air supply room for container vessels by a 3-dimension numerical simulation. A commercial CFD program, FLUENT, is used on the analysis. It is shown that the air supply efficiency in this room can be improved by changing position of axial fan, even though other conditions still remain unchanged.

A 2D axisymmetric numerical analysis was performed to study the characteristics of charge process inside solar thermal storage tank. The interfacial area density and inertial resistance of filler material are selected as simulation parameters. The interfacial area density is varied as 800, 2000, and 4000 1/m. The inertial resistance is varied as 1, 3, and 5 1/m. When the interfacial area density increases from 800 to 4000 1/m, the discrepancy of the temperature distributions between the filler and heat transfer fluid decreases. As inertial resistance increases from 1 to 5, both of the temperature and fluid flow pattern changes considerably.

수치모델을 이용하여 한국 동해 용승역의 유동특성에 대해 연구하였다. 용승을 일으키는 주요 인자인 바람, 해류 등을 파악하여 동해 연안역의 시·공간적인 분포와 용승유량을 정량적으로 산정한다. 연구해역인 동해에서 대·소기의 조류는 흐름의 크기가 차이가 났으나 창조류 시 남향하고 낙조류 시 북향하는 흐름을 보였다. 취송류는 연안을 따라 북향하는 흐름을 보이며 표층에서는 외해로 발산하고 저층에서는 연안으로 보상하는 흐름을 나타낸다. 취송류에 의한 용승발생분포는 평균 0.1cm/s정도의 상승류가 동해 전 연안에 걸쳐 넓게 분포하며 표층에서 강하고 저층으로 갈수록 좁게 분포하는 경향을 보였다. 상승류의 최대 유속은 약 1.4cm/s 정도로 영덕, 후포, 구룡포 그리고 기장의 연안에서 나타났다. 또한 본 연구에서는 용승해역에서 용승유량을 정량적으로 산정하여 밝혀낸다.

In this study, we modeled a actual shape of a plate heat exchanger into triangular grooved channel and tried to examine flow characteristics experimentally by particle image velocimetry. Five Reynolds numbers were selected with the height of grooved channel and sectional mean velocity of inlet flow. As a result, the triangular grooved channel had a compound flow consisting of the flow in lower channel and the groove flow receiving shear stress by the channel flow. The sheared mixing layer, in the boundary between the triangular groove and the channel, affected main flow to raise turbulent in the channel.