• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.93-94
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• 2017

• 대한조선학회논문집
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• 제59권6호
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• pp.400-412
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• 2022

This paper provides the results of numerical and theoretical predictions of oil outflows from damaged single-hull and double-hull ships.Theoretical equations derived from the unsteady Bernoulli equation and a CFD method for multi-phase flow analysis were used to estimate the oil outflow rate from cargo tank. The predicted oil outflow rate from a single-hull cargo tank damaged due to grounding and collision accidents showed a good agreement with the available experimental results in both numerical and theoretical analyses. However, in the case of the double-hull conditions, the time variation of the amount of water and oil mixture inside the ballast tank predicted by the theoretical equation showed some different behavior from the numerical results. The reason was that the interaction of the oil flow with the water inflow in the ballast tank was not reflected in the theoretical equations. In the problems of the initial pressure condition in the cargo and ballast tanks, the oil outflow and water inflow were delayed at the pressure condition that the tanks were sealed. When the flow interaction between the oil and water in the ballast tank was less complicated, the theoretical and the numerical results showed a good agreement with each other.

• 해양환경안전학회지
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• 제28권4호
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• pp.620-631
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• 2022

본 논문은 CFD 해석법을 이용하여 사고 선박의 손상부 형상에 따른 기름 유출량 변화를 예측하고, 이론 추정식에서 이를 고려할 수 있는 방출계수 도출 결과를 소개한다. Froude수와 Reynolds수 상사를 만족하는 조건에서 다상유동 해석법을 사용하여 모형선 크기의 기름 유출 문제를 다루었다. 수치해석 결과는 알려진 실험 결과와 비교하여 검증하였다. 수학적 형상들로 정의한 손상부 형상의 변화와 함께 손상부 가로세로비와 기름탱크 두께의 변화가 기름 유출 유동에 미치는 영향을 조사하였다. 보다 현실적인 상황을 고려하기 위해 손상부의 찧어진 철판의 영향에 대한 해석도 포함하였다. 수치해석 결과를 통해 사고 선박의 손상부 형상에 따른 기름 유출량의 변화를 확인하였으며, 다양한 손상부 형상이 가지는 점성 영향을 방출계수로 정량화하여 추출하였다. 본 논문에서 제시하는 방출계수에 대한 검증을 위하여 알려진 기름 유출량 주정식에게 적용하였으며, CFD 해석과 좋은 일치를 얻었다.

• 해양환경안전학회지
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• 제3권2호
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• pp.63-67
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• 1997

In this study, some approximate theoretical solutions about oil spreading under the influence of gravitational and viscous forces have been derived from the viewpoint of energy conservation. The theoretical model which derived newly is in agreement with Toi's one derived from a different hypothesis, and shown to predict well the spreading distance of oil front at an initial step of outflow, but further study is necessary to evaluate the spreading distance after longer time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.451-454
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• 2003

The Oil Coolers is very important unit for the stable thermal performance in machine tools, semiconductor equipments and high precision measuring systems. To select a proper oil cooler for the temperature control of core unit in a machine, not only cooling ability but also static and dynamic sensitivity of temperature sensors are considered. In this paper, the relationship between cooling ability and inflow oil temperature is identified. The cooling ability is increased with the increase of inflow oil temperature. The oil temperature control errors of a cooler are influenced by mainly sensitivity of temperature sensors and heating velocity in a machine. The validity of error cause analysis for temperature control is proved by real cooling experiments with inflow and outflow temperature sensors.

• Asian-Australasian Journal of Animal Sciences
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• 제9권6호
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• pp.637-642
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• 1996

This experiment was conducted to determine RDP values of locally available feedstuffs that are commonly used in ruminant rations in Bangladesh. Four cattle were fistulated in the rumen for the in situ nylon bag studies. Seventeen different feedstuff sample (9 roughages and 8 concentrates) were evaluated in $4{\times}14cm$ nylon bags and incubated in the rumen for different periods of time (2, 6, 12, 24, 48 and 72 h). The variation in crude protein (CP) contents reflected on the average CP disappearance value throughout the rumen incubation. Soluble fraction (a), insoluble but degradable fraction (b) along with the rate of degradation also varied widely among the various feedstuffs. Under 2% of rumen outflow rate, the percentages of the calculated protein degradabilities of roughages were rice straw, 16.7; maize grass, 70.6; oat grass, 70.8; dhal grass, 71.1; sunhemp, 78.4; napier grass, 62.4; matikalai grass, 72.1; khesarikalai grass, 76.9 and daincha browse, 78.4, respectively. The results in the protein degradabilities (%) in 8% ruminal outflow rate of concentrates were wheat bran, 61.6; rice polish (red), 61.3; rice polish (auto), 30.9; mustard oil cake, 71.8; sesame oil cake, 74.2; coconut oil cake, 57.9; soybean meal, 49.2 and fish meal, 37.9, respectively.

• 한국축산식품학회지
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• 제43권6호
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• pp.1128-1149
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• 2023

In order to extend the shelf life of refrigerating raw lamb by inhibiting the growth of microorganisms, preventing the oxidation of fat and protein, and absorbing the juice outflow of lamb during storage, an active packaging system based on plastic/gelatin bilayer film with essential oil was developed in this study. Three kinds of petroleum-derived plastic films, oriented polypropylene (OPP), polyethylene terephthalate, and polyethylene, were coated with gelatin to make bilayer films for lamb preservation. The results showed significant improvement in the mechanical properties, oxygen, moisture, and light barriers of the bilayer films compared to the gelatin film. The OPP/gelatin bilayer film was selected for further experiments because of its highest acceptance by panelists. If the amount of juice outflow was less than 350% of the mass of the gelatin layer, it was difficult for the gelatin film to separate from lamb. With the increase in essential oil concentration, the water absorption capacity decreased. The OPP/gelatin bilayer films with 20% mustard or 10% oregano essential oils inhibited the growth of bacteria in lamb and displayed better mechanical properties. Essential oil decreased the brightness and light transmittance of the bilayer films and made the film yellow. In conclusion, our results suggested that the active packaging system based on OPP/gelatin bilayer film was more suitable for raw lamb preservation than single-layer gelatin film or petroleum-derived plastic film, but need further study, including minimizing the amount of essential oil, enhancing the mechanical strength of the gelatin film after water absorption.

• 한국수산과학회지
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• 제36권6호
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• pp.743-748
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• 2003

An oil boom was set up in order to contain diffused oil from spills and for the retrenchment of damage caused by oil Pollution. Therefore, the oil boom anchor needed proper holding power to endure high resistance from flowing streams and to secure the oil boom around the spill, and must dredge directly into the seabed when it is dropped and block oil outflow immediately. This study investigated the holding power of the danforth anchor and the coastal fishing vessel anchor used for oil booms in the KMPRC (Korea Marine Pollution Response Corporation). For each type, a 30 kg and 20 kg anchor were used. The holding power of the danforth anchors were measured by dropping both weights 10 times. However the coastal fishing vessel anchors were dropped only 5 times each, because no substantial differences were found between drops. In the results of the danforth anchors, an anchor awoke occurred in 2 drops of the 30 kg anchor and in 4 drops of the 20 kg anchor, wherein there was no holding power to be measured. With exception to the anchor awoke cases, the maximum holding power of the danforth 30 kg and 20 kg anchors was 250-520 kg and 123-233 kg, respectively. In the case of the coastal fishing vessel anchors of 30 kg and 20 kg, throughout the experiment, there was no occurrence of an anchor awoke. For the 30 kg and 20 kg anchors, the maximum holding power was measured to be 209-230 kg and 155-170 kg, respectively. Therefore, the holding power of the coastal fishing vessel anchor was shown to be much poorer than that of the danforth anchor. However, the holding power of the danforth anchor was very unstable. Due to the occurrences of anchor awoke, there was no holding power and the measurement value of maximum holding power showed too much variation among the drop tests. Also, after the maximum holding power was achieved, anchor awoke occurred easily. In the case of the coastal fishing vessel anchor was much more stabile, because there was no anchor awoke and no instance where holding power failed. Also the maximum holding power was reached quickly and almost no variation occurred among the drop tests.

• 해양환경안전학회지
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• 제28권2호
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• pp.394-405
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• 2022

본 논문은 CFD 해석법을 이용한 단일선체 및 이중선체 선박의 손상에 따른 기름 유출량 추정 결과를 소개한다. 수치해석 기법으로 다상유동 해석법을 사용하고 기름 유출 유동에 대한 다양한 수치해석적 조건의 변화에 대한 영향을 조사하였다. 좌초 또는 충돌에 의한 다양한 손상 조건에서의 기름 유출량의 변화를 해석하였으며 실험 결과를 통해 검증하였다. 본 논문의 수치해석 결과는 단일선체와 이중선체의 기하학적 특성을 따라 실험 결과와 잘 일치하였다. 특별히 물과 기름의 복잡한 상호작용이 나타나는 이중선체의 기름 유출 상황도 실험과 동일하게 타당하게 예측하였다. 본 연구를 통해 사고 선박의 기름 유출량 추정에 필요한 CFD기법을 정립할 수 있었다.

• 한국기계가공학회지
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• 제11권4호
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• pp.111-117
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• 2012

Dust collecting performance of axial-vane type cyclone for oil mist was analyzed in this study. For predicting cut diameter size of cyclone, the number and angle of vane ($tan{{\beta}_2}^{\prime}$) was simulated by CFD. As the result, $tan{{\beta}_2}^{\prime}$ was decreased as the number of vane was increased and the angle of inclination(${{\beta}_2}^{\prime}$) decreased, and it cause strong swirl flow. Therefore, it could be confirmed that as the number of vane was increased and the angle of inclination was decreased, cut diameter size was decreased. Also, by verifying the results of CFD through experiment, the cut diameter size could be $2{\mu}m$ at $4m^3/min$ of flow rate.