• 수산해양기술연구
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• 제22권2호
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• pp.7-15
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• 1986

In order to investigate the performance for the mackerel purse seine of one boat purse seiner using in the sea area of Cheju Island, a model net is made of the scale of 1/400 of its full scale, and model test on the shape of net and the tension of purse line is carried out in the stagnant water channel of the circulating water tank. Designing and testing for the model net are based on the Tauti's law. The obtained results are as follows; 1. The sinking rate of net is maximized the value of 6.40 m/min from 5 to 10 minutes after shooting net, and the mean value is 6.13 m/min. 2. The enclosed area formed with the float line after pursing operation is 76-84% of the area which is formed immediately after the shooting operation. At that time, purse seine is pulled inward the circle of surrounding net about 26.5% of the diameter. 3. In operating, when longitudinal section area of the central part of the net is maximized, the split area of both the wing-ends is 31-32% of the former. 4. When the time for the completing of pursing is 20 minutes, the maximum tension of the purse line is about 10.2 tons.

• 한국농공학회지
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• 제16권3호
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• pp.3477-3491
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• 1974

Following are the results of the study on the property of falling permeation of stratified soil in the close state under existence of stagnant water on a soil layer. 1. When on the stratified soil a least permeating layer was put on the soil layer the load Pressure was present owing to appearance of saturation close state driving decrease of the pressure in the lower layer, on the other hand when the least permeating layer was placed under the layer the lower least permeating layer pressure was decreased. 2. In the case of least permeating layer the variation of current gradient according to the respective level after treating the layer was enormous and due to usal storage phenomena for the Kl layer which was coarse that was trifle. 3. The permeability of the respective layer of stratified soil in the close state died not always coincide with that of single layer. 4. Generally Zunker's equation of average permeability was valid but actually calculated permeating velocity after treating the layer of stratified soil was seriously differ from the measured value owing to the variation of current gradient, especially when the pressure head at the layer boundany was discontinuous the validity of the equation of average permeability was seemed to be doubtful. 5. The permeating velocity of stratified soil was regulated by the least permeating layer, i.e. it is thought to be rational to estimate the value by calculating the current gradient with its proper permeability, pressure headon the layer and its thickness.

• 한국농공학회지
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• 제21권3호
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• pp.121-126
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• 1979

The objective of this study was to grasp the condition of the distribution of water temperature in the warm water pool, and these observations were performed in Wudu warm water pool located at Wodu-Dong in Chuncheon. The results summarized in this study are as follows; 1. The horizontal distribution charts of water temperature at each depth of points were shown as Fig. 3, Fig. 4, and Fig. 5, respectively. In consequence of the observation, the condition of warm water was stagnant in the coner of warm water pool. As the result, it was found out that stagnant condition was the heaviest at water surface (depth; 0.05m), more heavier at middle depth (depth; 0.55m) and some heavy at bottom of the pool (depth; 1.10m). 2. The vertical water temperature change was shown as Fig. 6, and the mean water temperature of water surface (depth;0.05m) was higher about $2.2{\sim}3.3^{\circ}C$ than bottom water temperature. 3. Therefore, it was required to device such structures as form of broad cannels or overflow diversion weirs to mingle with top and bottom water.

• 한국농공학회지
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• 제32권E호
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• pp.80-87
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• 1990

Energy balance equations Were developed to describe the heat transfer mechanisms in a double layer plastic greenhouse with a water curtain system. Heat transfer variables were determined by using various temperature data measured in a conventional prototype semicircular cross-section greenhouse over a range of water temperatures and water flow rates. The heat transfer coefficient between flowing water and greenhouse air was independent of water flow rates. But the heat transfer coefficient between water surface and the stagnant air space within the double plastic layer was dependent on water flow rates. Substituting the heat transfer coefficients, determined from the energy balance equations in the heat transfer equations, demonstrated various relationships among ambient air temperature, greenhouse air temperature, water temperature, and water flow rates. The heating benefits were linearly related to not only the inside and outside air temperatures but also to the water temperature. The energy conservation effects of the water curtain system were found even initial water temperatures were considerably lower than the greenhouse setting temperatures. Sensitivity analysis for heat transfer coefficients demonstrated that the heat transfer coefficient between greenhouse air and the stagnant air within the plastic layers was the most significant coefficient in the estimation of heating effects.

• 대한토목학회논문집
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• 제5권1호
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• pp.75-81
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• 1985

정지상태의 수역에서 연직상향으로 방류(放流)되는 평면부력(平面浮力)?의 발달과정(發達過程)흐름영역(領域)의 거동이 질량(質量), 운동량(運動量) 및 추적물보존(追跡物保存)의 적분방정식(積分方程式)에 의하여 해석된다. 이 해석은 밀도(密度)후르드수(數)와 핵(核)에 대한 퍼짐비 및 발달과정(發達過程)흐름영역(領域)의 길이를 포함한다. 발달과정(發達過程)흐름영역(領域)의 끝에서 중심선속도(中心線速度)는 특히 낮은 밀도(密度)후르드수(數)에서 부력(浮力)의 영향을 크게 받는다. 이 결과는 발달(發達)된 흐름영역(領域)의 해석(解析)에 필요한 초기조건(初期條件)을 제공한다.

• 한국의류학회지
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• 제32권11호
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• pp.1680-1691
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• 2008

This study examines how the development and value of dresses shown in MBC historical dramas have changed with the overall change of the dramas. As for the research method, the second data analysis was done with literature study which was supplemented with interviews with the wardrobe team of MBC production design center. Historical dramas produced by MBC have gone through the developmental period, legitimate historical drama-oriented period, stagnant period, and historical dramas-modernized period. The value of costume in each period is as follows: Costume in the developmental period is considered only as part of drama setting. During legitimate historical drama-oriented period, it carries value as educational data and historical replica produced by historical research. Production design including costume obtains its own value in the stagnant period although the production of historical dramas decreases dramatically. And lastly, in the historical dramas-modernized period, costume starts to have commercial value as cultural contents. Historical drama costume may contain important value in terms of education and history, even though there has been controversy on TV historical dramas' role: they should focus on reproducing historical facts or they should support writers' creativity.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.705-706
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• 2008

When heat generated inside a large factory building is not discharged due to a stagnant flow, the working environment of workers becomes worse and the cooling of high-temperature products such as hot-rolling coils is delayed. To investigate the natural ventilation inside a large factory building, experimental studies were carried out using wind-tunnel tests. The scale-down factory building models were placed in an atmospheric boundary layer (ABL) and the mean and fluctuating velocity fields were measured using a particle image velocimetry (PIV) technique. For the prototype factory model, the outdoor air is only entrained into the factory building through the one-third open windward wall, and stagnant flow is formed in the rear part of the target area. In order to improve the indoor ventilation environment of the factory building, three different louver-type ventilators were attached at the upper one-third open windward wall of the factory model. Among the three louver ventilators tested in this study, the ventilator model #3 with the outer louver (${\theta}_o$ = 90$^{\circ}$) and the inner louver (${\theta}_i$ = -70$^{\circ}$) was found to improve the natural ventilation inside the factory building model effectively. The flow rate of the entrained air was increased with aligning the outer louver blades with the oncoming wind and guiding the entrained air down to the ground surface with elongated inner louver blades.

• 대한토목학회논문집
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• 제6권2호
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• pp.93-101
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• 1986

정지수역(靜止水域)에서 연직상향(鉛直上向)으로 방류(放流)되는 평면부력(平面浮力)?의 거동을 연속방정식(連續方程式), 운동량수송식(運動量輸送式) 및 추적물(追跡物) 수송식(輸送式)에 의하여 수치적(數値的)으로 해석한다. 이 해석은 유함수(流凾數)와 과수송식(過輸送式)을 도입하고 Prandtl 난류모형(亂流模型)을 이용하였다. 방류밀도(放流密度) Froude 수(數)가 4~32인인 부력(浮力)?의 발달된 흐름영역(領域)에서 구한 ?중심선의 속도(速度)와 온도변화(溫度變化), ?주변수역(周邊水域)의 온도분포(溫度分布)와 흐름양상은 기존자료와 잘 맞음을 확인할 수 있다. 적분형해석(積分型解析)에 필요한 퍼짐율과 확산비(擴散比)가 방류밀도(放流密度) Froude 수(數)와 방류구(放流口)로부터의 거리의 함수로 유도된다.

• 대한기계학회논문집
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• 제19권7호
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• pp.1731-1740
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• 1995

Experimental investigations have been made to study the double-diffusive nature of convection of an initially stratified salt-water solution due to heating from below in a rotating cylindrical cavity. The objective is to examine the flow phenomena and the heat transfer characteristics according to the changes in temperature gradient, concentration gradient and rotating velocity of cavity. Thermal and solutal boundary conditions at side wall are adiabatic and impermeable, respectively. The top and bottom plate are maintained each at constant temperature and concentration. The cavity is put into a state of solid body rotation. Like the stationary case, the types of initially-formed flow pattern are classified into three regimes depending on the effective Rayleigh number and Taylor number; stagnant flow regime, single mixed-layer flow regime and successively formed multi-mixed layer flow regime. At the same effective Rayleigh number, the number of initially-formed mixed layer and its growth rate decrease as the effect of rotation increases. The temperature and concentration profiles are both uniform in each layer due to convective mixing in the layered-flow regime, but look both liner in stagnant flow regime and single mixed-layer flow regime. At the interface between adjacent layers, the temperature changes smoothly but the concentration changes rapidly.

• Journal of Advanced Marine Engineering and Technology
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• 제27권3호
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• pp.447-452
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• 2003

Crevice corrosion is localized form of corrosion usually associated with a stagnant solution on the micro-environmental level. Such stagnant micro environments tend to occur in crevices (shielded areas) such as those formed under gaskets washers insulation material. fastener heads. surface deposits. disbonded coatings. threads. lap joints and clamps. Crevice corrosion is initiated by changes in located electrochemical reaction within the crevice such as a) depletion of inhibitor in the crevice b) depletion of oxygen in the crevice c) a shift to acid conditions in the crevice and d) build-up of aggressive ion species (e.g chloride) in the crevice. In this study. the mechanism of crevice corrosion for Type 430 stainless steel is investigated undercondition that the size of specimen is $15{\times}20\{times}3mm$, in 1N $H_2SO_4$ + 0.05N NaCl solution. and the artificial crevice gap size of 3 x 0.2 x 15 mm. Crevice corrosion is measured under applied potential -300mV(SCE) to the external surface. The obtained result of this study showed that 1) the induced time for initiation of crevice is 750 seconds. 2) potential of the crevice was about from -320mV to -399mV. which is lower than that of external surface potential of -300mV It is considered that potential drop in the crevice is one of mechanisms for the crevice corrosion