• 한국해양공학회지
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• 제26권1호
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• pp.54-59
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• 2012

This study presents investigation on ullage effect in sloshing experiment. The experiment was done with two dimensional tank. Sloshing experiments were carried out in the tank with 6 different ullage pressures. The tested filling ratio was 30% of the tank height. The flow field was recorded with high speed camera. The sloshing impact pressure were measured at 18 locations. It was shown that the variation of ullage pressures influences the magnitude of pressure and flow field. This study demonstrated the importance of ullage pressure in sloshing test.

• 한국농공학회지
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• 제11권3호
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• pp.1707-1718
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• 1969

The purpose of this experiment is to determine the relations between numbers, arrangements and pumping rates of wells. In this experiment, well pipes were vertically set up in an artificial water-bearing sand layer of homogeneous quality. Wells were arranged in different ways and their number was varied in order to observe the variation of pumping rates. Sands were filled in a square tank, $183cm{\times}91.5cm{\times}91.5cm$ so as to secure a water-bearing layer. Water was constantly supplied from a supply tank located at an end of the tank. The number of well pipes was varied from one to four. Well pipes were connected by a horizontal header pipes were connected by a horizontal header pipe located above them and one pump was used. Pumping rates were measured, when they were arranged in longitudinal and lateral directions, They were also arranged in a square and triangle. The main results thus obtained are presented as follows: (1) When well pipes are laid out in a longitudinal line, i. e., in a flow direction, the ratios of pumping rates of one-pipe well and wells 2-, 3- and 4- pipe t, are 1.903, 2.506 and 2.66, respectively. (2) When well pipes are laid out in a lateral line, i.e., in a perpendicular direction to flow, the same ratios as (1) are 1.912, 2.527 and 2.88. (3) When four pipes are laid out in a square and three pipes are laid out in a triangle, pumping rates are deereased, Comparing with the cases when pipes are laid out in a straight line.

• 한국해양공학회지
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• 제32권3호
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• pp.202-207
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• 2018

This paper presents the efficiency of a floating vertical axis wind turbine with variable-pitch. A model was designed to use the lift force and drag force for blades with various pitch angles. The blade's pitch angle is controlled by the stopper. To validate the efficiency of the wind turbine discussed in this paper, a model test was carried out through a single model efficiency experiment and wave tank experiment. The parameters of the single model efficiency experiment were the wind speed, electronic load, and pitch angle. The wave tank experiment was performed using the most efficient pitch angle from the results of the single model efficiency experiment. According to the results of the wave tank experiment, the surge and pitch motion of a structure slightly affect the efficiency of a wind turbine, but the heave motion has a large effect because the heights of the wind turbine and wind generator are almost the same.

• Fisheries and Aquatic Sciences
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• 제26권8호
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• pp.461-469
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• 2023

The objective of this study was to evaluate how the tank colours may change the effects of extreme temperature on the survival, growth, and quality of juvenile golden trevally (Gnathanodon speciosus). The experiment was set up with fifteen treatments of five tank colours (blue, red, yellow, grey, and white) and three temperatures (30℃, 32℃, 34℃) with three replications. Fish performance was assessed for four weeks. The results showed that tank colours and elevated temperatures affected the quality of golden trevally juveniles. The survival and growth rate of fish tend to decrease gradually, but the deformation rate of fish tended to increase in the order of tank colours: red, yellow > grey, blue, and white. The growth and survival rate of fish gradually decreased when the rearing temperature increased from 30℃ to 34℃ and this effect was independent of tank colors. Importantly, the deformation rate increased under elevated temperature, particularly in blue and white tanks with potential long-term effects. It is, therefore, not recommended to use blue and white tanks for rearing the golden trevally juveniles, particularly during extremely high temperatures from heatwave events.

• 대한조선학회논문집
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• 제51권5호
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• pp.396-408
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• 2014

In this study, uncertainty analysis based on ITTC(International Towing Tank Conference) Recommended Procedures is carried out in the towing-tank experiment for motion responses and added resistance. The experiment was conducted for KVLCC2 model in head sea condition. The heave, pitch and added resistance were measured in different wave conditions, and the measurement was repeated up to maximum 15 times in each wave condition in order to observe the uncertainty of measured data. The uncertainty analysis was carried out by adopting the ISO-GUM(International Organization for Standardization, Guide to the Expression of Uncertainty in Measurements) method recommended by ITTC. This paper describes the details about the analysis method, uncertainty and the measured uncertainty for each source. The uncertainty analysis results are summarized as a tabular form. To validate the accuracy of the present measurement, the experimental results are compared with the results of numerical computation and other experiment. From the present uncertainty analysis, the main sources of uncertainty are identified, which can be very useful to improve the accuracy for added resistance experiment.

• 한국산학기술학회논문지
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• 제7권3호
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• pp.440-447
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• 2006

본 연구의 목적은 미나리와 끈상 미생물접촉재를 이용하여 생활하수의 하수처리장 방류수의 수질 개선을 위함이다. 최종 방류수의 수질을 개선하기 위한 침전조 모형 플랜트를 2개 제작하여 실험하였는데, 하나(Tank 1)는 기존 하수처리장 침전조와 같게 제작 하였으며, 다른 하나의 침전조(Tank 2)는 침전조의 수초섬 상부에는 미나리를 식재하고 하부에는 끈상 미생물 접촉재를 배치하였다. 유기 오염물질인 BOD, 부유고형물질인 SS, 질소 그리고 인에 대한 고도처리 효율을 검증하였다. 실험 결과 Tank 2에서 유출되는 배출수가 Tank 1에서 배출되는 유출수보다 처리 효율이 향상되었다. 처리 효율을 살펴보면, Tank 1보다 Tank 2 유출수의 BOD는 $7.9%{\sim}38.8%$가 향상되었으며, 부유고형 물질인 SS는 $14.3%{\sim}60.0%$ 향상되었다. 부영양화 물질인 T-N은 $9.6%{\sim}31.5%$ 향상되었으며, T-P는 $33.0%{\sim}80.0%$까지 향상되었다. 처리 효율로 판단하면 T-P와 SS 제거효율이 BOD와 T-N보다 높았다.

• 한국태양에너지학회 논문집
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• 제27권3호
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• pp.45-54
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• 2007

For a conventional natural-circulation type solar water heater, the pressure head is limited by the height between the storage tank and hot water tap. Therefore, it is difficult to provide sufficient hot water flow rate for general usage. This study deals with a design modification of the storage tank to utilize the tap-water pressure to increase hot-water supply Based on fluid dynamic and heat transfer theories, a series of modeling and simulation is conducted to achieve practical design requirements. An experimental setup is built and tested and the results are compared with theoretical simulation model. The storage tank capacity is 240 l and the outer diameter of piping was 15 mm. Number of tube turns tested are 5, 10, and 15. Starting with initial storage tank temperature of $80^{\circ}C$, the temperature variation of the supply hot water is investigated against time, while maintaining minimum flow rate of 10 1/min. Typical results show that the hot water supply of minimum $30^{\circ}C$ can be maintained for 34 min with tap-water supply pressure of 2.5 atm, The relative errors between modeling and experiments coincide well within 10% in most cases.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2009년도 춘계학술발표회
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• pp.85-86
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• 2009

슬로싱 현상은 탱크안의 자유표면을 갖는 유체의 비선형거동으로 탱크안의 구조물에 동적 하중을 발생시키므로 일반적으로 해양 구조물의 설계에 중요한 문제이다. 이 연구에서는 피칭운동을 하는 사각탱크 내에서 자유표면을 갖는 유체의 슬로싱에 대해 실험적으로 연구하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.151-157
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• 2005

In the chemical, mineral and electronics industries, mechanically stirred tanks are widely used for complex liquid and particle mixing processes. In order to understand the complex phenomena that occur in such tanks, it is necessary to investigate flow field in the vessel. Most difficulty on the numerical analysis of stirred tank flow field focused particularly on free surface analysis. In order to decrease the dead zone and improve the flow efficiency of a system with free surface, this paper presents a new method that overcomes free surface effects by properly combining the benefits of using experiment and 3-D CFD. This method is applied to study the mixing flow in an agitated tank. From the results of experimental studies using the PIV (particle image velocimetry) system, the distribution of mixing flow including free surface are obtained. And these values that are expressed as a velocity vector field have been patched for simulating the free surface. The results of velocity distribution obtained by 3-D CFD are compared with those of experimental results. The experimental data and the simulation results are in good agreement.

• 한국유체기계학회 논문집
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• 제7권6호
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• pp.55-61
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• 2004

A numerical procedure for optimizing the shape of three-dimensional sedimentation tank is presented to maximize its sedimentation efficiency. The response surface based optimization is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis for multi-phase flow. Standard $k-{\epsilon}$ model is used as a turbulence closure. Three design variables such as, tank height to center feed wall diameter ratio, blockage ratio of center feed wall and angle of distributor are chosen as design variables. Sedimentation efficiency is defined as an objective function. Full-factorial method is used to determine the training points as a means of design of experiment. Sensitivity of each design variable on the objective function has been evaluated. And, optimal values of the design variables have been obtained.