• 한국항해항만학회지
• /
• 제27권2호
• /
• pp.239-246
• /
• 2003

해양에 기름이 유출되면 방제작업의 초기단계에서 기름의 이동 및 확산을 차단하기 위하여 오일 붐을 사용하는 것이 일반적이다. 그러나 오일 붐은 유속, 기름의 밀도와 점성, 수심, 기름의 양, 그리고 붐 흘수의 길이 등과 같은 여러 인자들에 의해 그 포획능력이 영향을 받는다. 본 연구에서는 이들 누유인자가 오일 붐의 포획과정에 어떠한 영향을 미치는지를 체계적으로 파악하기 위하여 컴퓨터 모델링을 수행하였다. 모델링을 위하여 CFD(computational fluid dynamics) 프로그램 중에서 가장 널리 알려진 Fluent를 이용하였으며 기존의 실험자료와 비교함으로써 모델링 결과를 검증하였다. 본 연구의 결과는 방제작업 책임자와 오일 붐 설계자에게 유용한 참고자료가 될 것으로 기대된다.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2003년도 춘계공동학술대회논문집
• /
• pp.171-178
• /
• 2003

해양에 기름이 유출되면 방제작업의 초기단계에서 기름의 이동 및 확산을 차단하기 위하여 오일 붐을 사용하는 것이 일반적이다. 그러나 오일 붐은 유속, 기름의 밀도와 점성, 수심, 기름의 양, 그리고 붐 홀수의 길이 등과 같은 여러 인자들에 의해 그 포획능력이 영향을 받는다. 본 연구에서는 이들 누유인자가 오일 붐의 포획과정에서 어떠한 영향을 미치는지를 체계적으로 파악하기 위하여 컴퓨터 모델링을 수행하였다. 모델링을 위하여 CFD(computational fluid dynamics) 프로그램 중에서 가장 널리 알려진 Fluent를 이용하였으며 기존의 실험자료와 비교함으로써 모델링 결과를 검증하였다. 본 연구의 결과는 방제작업 책임자와 오일 붐 설계자에게 유용한 참고자료가 될 것으로 기대된다.

• 한국해양공학회지
• /
• 제11권4호
• /
• pp.189-196
• /
• 1997

An oil tracking system that monitors the spilt oil trajectory by using GPS was developed. The system consists of a tracking buoy deployed on the oil spilt area and an onshore(or onboard) monitoring station. The tracking buoy is equipped with GPS, signal converter, handy radio and battery while the monitoring station includes a station radio, signal converter, antennas and PC. The hull shape of buoy is designed to effectively simulate the spilt oil movement at sea surface. Radio sets for HAM are used as a data transmitter and a data receiving station, and signal converter is also for amateur use. A field experiment was conducted and it was shown that the integrated system is relable and robust. The developed oil tracking system reveals reatively good performance at reasonable cost. In favorable environment the system may communicate in the distance more than 50km.

• 대한치과교정학회지
• /
• 제20권1호
• /
• pp.61-86
• /
• 1990

To study the effect of prostglandin $E_2$ and evening primrose oil on orthodontic tooth movement in rats, one hundred and sixty rats were divided into four groups of 40 rats each. One group, injected with saline on the palate subperiosteally, served as a control group. A second and third group were injected subperiosteally on the palate with $PGE_2$ $10{\mu}g$ and evening primrose oil 10mg respectively. The fourth group was given indomethacin $20{\mu}g/m{\ell}$ orally by water bottle. The maxillary first molar was moved mesially from the incisors using a 50gm force rubber band. In each group at the 1, 2, 3, 5, and 7th day, 4 rats were examined by light microscope, and 4 by electron microscope. The obtained results were as follows: 1. Osteoclastic activity was maximum at the 3rd day in the $PGE_2$ group on the interradicular alveolar bone of the first molar, followed by the evening primrose oil group, control group, and indomethacin group. 2. Root resorption and vacuolar changes were maximum in the $PGE_2$ group. 3. At the 3rd day of the $PGE_2$ group, the osteoclasts showed well developed ruffled borders and clear zones. At the same day, the evening primrose oil group also showed well developed ruffled borders and clear zones, but less than the $PGE_2$ group. 4. At the 3rd and 5th day of the $PGE_2$ group, fibroblasts showed phagocytized fragmented collagen fibers in the cytoplasm. At the 7th day of the $PGE_2$ group, fibroblasts showed collagen fibers forming at the cell membrane surface.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제8권3호
• /
• pp.1-7
• /
• 2003

지하 유류저장탱크에서 유류가 지속적으로 누출되는 경우에는 지하수 이동에 비해서 LNAPL의 이동을 무시할 수 없다. 본 연구에서는 지하수면 위에서 LNAPL의 이동을 고려한 수정된 용질이동 모델을 개발하였다 LNAPL 이동을 고려하지 않는 기존 모델과 비교한 결과 수두 구배, 누출되는 기름의 양, 분산지수에 따라 두 모델은 차이점을 보였다. 수두 구배가 낮을수록, 누출되는 유류의 양이 증가할수록 수정된 모델과 기존 모델 사이의 평균편차가 증가하였다. 분산지수가 변화함에 따라서 평균편차는 변하지 않았지만, 분산지수가 증가할수록 두 모델 사이의 편차는 공간적으로 보다 넓게 나타났다. 수직방향으로의 분산이 크게 나타날 경우에는 LNAPL의 이동을 고려한 모델과 이동을 고려하지 않은 모델과의 차이가 지하수 유동 방향뿐만 아니라 수직방향으로도 크게 나타났다. 결국 LNAPL의 이동을 무시할 수 없는 지하환경에서는 기존의 모델을 가지고 용질이동을 모사할 경우 실제보다 농도가 낮게 추정될 가능성이 높다. 이 연구의 결과로 LNAPL이 지하수면 위에서 얼마나 빨리 이동하는지 아는 것이 올바른 오염물의 농도 예측에 중요하다는 것을 파악하였다.

• The Journal of Asian Finance, Economics and Business
• /
• 제7권10호
• /
• pp.63-71
• /
• 2020

In this paper, we propose the new time-varying coefficient GARCH-in-Mean model. The benefit of our model is to allow the risk-return parameter in the mean equation to vary over time. At the end of 2019 to the beginning of 2020, the world witnessed two shocking events: COVID-19 pandemic and 2020 oil price war. So, we decide to use the daily data from December 2, 2019 to May 29, 2020, which cover these two major events. The purpose of this study is to find the dynamic movement between risk and return in four major oil markets: Brent, West Texas Intermediate, Dubai, and Singapore Exchange, during COVID-19 pandemic and 2020 oil price war. For the European oil market, our model found a significant and positive risk-return relationship in Brent during March 26-April 21, 2020. For the North America oil market, our model found a significant positive risk return relationship in West Texas Intermediate (WTI) during March 12-May 8, 2020. For the Middle East oil market, we found a significant and positive risk-return relationship in Dubai during March 12-April 14, 2020. Lastly, for the South East Asia oil market, we found a significant positive risk return relationship in Singapore Exchange (SGX) from March 9-May 29, 2020.

• 한국해양공학회지
• /
• 제32권6호
• /
• pp.474-484
• /
• 2018

In this study, a new numerical modeling system was proposed to predict oil spills, which increasingly occur at sea as a result of abnormal weather conditions such as global warming. The hydrodynamic conditions such as the flow velocity needed to calculate oil dispersion were estimated using a three dimensional hydrodynamic model based on the Navier-Stokes equation, which considered all of the physical variations in the vertical direction. This improved the accuracy compared to those estimated by the conventional shallow water equation. The advection-diffusion model for the spilled oil was combined with the hydrodynamic model to predict the movement and fate of the oil. The effects of absorption, weathering, and wind were also considered in the calculation process. The combined model developed in this study was then applied to various test cases to identify the characteristics of oil dispersion over time. It is expected that the developed model will help to establish initial response and disaster prevention plans in the event of a nearshore oil spill.

• 한국자동차공학회논문집
• /
• 제16권2호
• /
• pp.1-7
• /
• 2008

In order to enhance the performance of an automotive engine, many researchers have been carried out. An oil jet cooling a piston is one of important parts for engine performance. Therefore, the efficient cooling system of an oil jet is needed. In this paper, unsteady flow analysis of the oil jet which consists of a check valve and a nozzle has been accomplished. And the reaction between mass flow rate and ball movement was also investigated.

• 해양환경안전학회지
• /
• 제2권1호
• /
• pp.57-65
• /
• 1996

The latest date, No. 1 YouII was grounded and sunk into the sea at MAMHYUNGJEDO ( South brother Island) in Sep. 21. 1995, and M.V. Sea Prince of V.L.C.C also made a big oil poullution accident owing to Typhoon "Paei" at front sea of Yeu Choun on Jul. 25. 1995. The large or small scall scale of oil poullution accident frequently was occurred about 300-350 cases per ine(1) year. The countries advanced in marine relations like as, nited Kingdom and Japan, have perfect system The country of expert education, training and oil recovery equipments in oil poullution accidents. The large quantity oil skimming ship's basic condition need general skimming ship which was high speed and large quantity skimming ability , and hve to store the recovered oil into tanks This oil skimming shop are composit the skimmer whuch move up and down according to the wace movements, storage tank which storage the recovered oil in after side, transfer pump which transformed from flooding tank to separating tank and separating tank which separated the oil mixtures, Also there are cylindrical floated which keep the auto positing, gate which keep the auto positing, gate which protect and guide the recovering oil from sea and balance weight for skimmer balance. Also there are cylindrical floated which keep the auto positing, gate which protect and guide the recovering oil from sea and balance weight for skimmer balance. The important arrangement is twin arm which moved by two hinge and move te skimming unit by wave movement. In gate of inside, made long wear in the gate bellow position, there are also connected the flexible hose for oil mixtures drop. The separating tank composited with multi-divided bulkhead for ffective oil and sea water separating by settling and flotation principle. As use the above natural princile and equipment, we can remove the large quantity oil by developed oil skimming ship.ming ship.

• Korean Chemical Engineering Research
• /
• 제48권4호
• /
• pp.462-469
• /
• 2010

기체와 액체가 만나는 2상 공정들은 화학공학, 생명화학공학, 환경공학, 식품공학 등에 두루 존재한다. 위와 같은 공정의 최적화를 위해서는 거품의 움직임과 형태에 대한 정확한 파악이 필요하다. 액체 내부에서 거품의 움직임은 액체의 밀도, 점도, 표면장력과 거품의 크기와 속도에 영향을 받는다. 본 논문에서는 고점도 실리콘 오일 내부에서의 거품의 움직임과 형태를 관찰하였다. 또한 국외 논문 및 저서에서 정립된 거품의 에너지 수지 식, 항력계수와 변형계수를 이용하여 거품의 종말속도, 항력계수, 변형계수, 형태를 예측해 보고 이를 실험결과와 비교해 보았다. 실험 결과 거품의 속도는 점도가 낮을 경우가 더 빨랐고, 거품의 항력계수는 점도가 클 때 더 컸다. 거품의 형태는 점도가 클 때 덜찌그러진(구형에 가까운) 형태였다. 실험결과와 국외 논문 및 저서에서 정립된 항력계수와 변형계수를 이용한 예측결과를 비교해 본 결과 Batchelor가 제시한 이론이 가장 정확한 예측을 하는 것으로 나타났다. Batchelor가 제시한 거품의 에너지 수지식, 항력계수와 변형계수를 사용하여 예측한 거품의 2차원 측면 형태는 실험에서 관찰된 거품의 2차원 측면 형태와 유사하였다.