• Ocean and Polar Research
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• 제32권4호
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• pp.449-462
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• 2010

Ongoing port baseline surveys are essential for developing ballast water management procedures in order to control unwanted or potentially risky species. Seasonal distributional patterns of marine dinoflagellate Noctiluca scintillans internationally recognized as harmful species and the related environmental factors were surveyed at Incheon, Gwangyang and Ulsan seaports in Korea from 2007 to 2009. The above three seaports were chosen because of their status as the busiest in Korea and characterized by their different bioregions. Average temperature ranged from $2.08^{\circ}C$ in winter to $26.39^{\circ}C$ in summer at Incheon, $7.22^{\circ}C$ in winter to $25.77^{\circ}C$ in summer at Gwangyang, and $11.59^{\circ}C$ in winter to $21.67^{\circ}C$ in summer at Ulsan during the study period. Average salinity varied from 26.88 in winter to 31.25 in summer at Incheon, 22.83 in winter to 33.41 in summer at Gwangyang, and 30.04 in winter to 33.90 in summer at Ulsan. Noctiluca scintillans appeared consistently at all ports during the study period, indicating its eurythermal and euryhaline nature. The highest abundances (21,813 to 41,753 $inds{\cdot}m^{-3}$) of N. scintillans were observed in May 2008 and 2009 at the outer stations of Incheon port. Abundances of between 10,000 and 30,000 $inds{\cdot}m^{-3}$ were only observed at the innermost station of Ulsan in May, while abundances of between 10,000 and 40,000 $inds{\cdot}m^{-3}$ were frequently observed throughout all stations at Gwangyang during the study period, coinciding with consistently high concentration of chlorophyll-a (hereafter chl-a) ($4.32-8.24\;{\mu}g\;l^{-1}$) compared to other ports. Spatio-temporal variation of chl-a concentration was not significantly correlated with abundances of N. scintillans (p>0.01). However, relatively high chl-a concentrations were consistently recorded along with high abundances of N. scintillans throughout all stations at Gwangyang compared to other ports. Abundances of N. scintillans observed at the three surveyed ports did not significantly (p>0.01) affect the concentration of dissolved oxygen in the surface mixed layer, indicating that the species abundances were not enough to cause reduction of dissolved oxygen during the study period. Presented results indicated that the Gwangyang seaport may provide the most suitable environment for a wide range of N. scintillans blooming compared to other ports.

• 방사성폐기물학회지
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• 제14권2호
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• pp.113-122
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• 2016

본 연구에서는 항 내부에서 부하되는 오염물질이 파랑 및 흐름 조건으로 인하여 항외로 유출되는 과정을 수리실험을 통해 알아보았다. 월성원자력발전소 항내에 오염물질이 부하 되었을 시, 실험인자를 변화시켜가며 추적자를 활용한 흐름거동 조사를 수행하였다. 각 실험의 결과는 지수 함수에 따른 항내 오염물이 감소하는 경향이 나타나며, 항외 유출에 걸리는 시간의 기울기는 각각 다른 결과를 보여주었다. 관측된 데이터로부터 회귀식을 도출한 결과, 흐름 관측의 경우 유입되는 모터의 회전 속도 30, 20, 10 rpm에서 좌측 항내의 오염물이 50% 유출률에 도달하는 시간은 각각 2.70, 10.40, 26.39 days를 보였다. 모터의 회전속도가 30 rpm인 실험에서 유출되는 감소 추세가 가장 뚜렷하게 나타났으며, 회전속도 10 rpm인 실험에서 기울기는 완만하였다. 파랑 관측의 우측 영역의 오염물이 50% 유출률에 도달하는 시간은 4.59 days로 나타났으며, 좌측영역의 경우 15.35 days의 결과를 보였다.

• 대한기계학회논문집B
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• 제30권2호
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• pp.177-185
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• 2006

This study aims deriving analysis the flow characteristic of kitchen hood system with using 3-D numerical analysis method and improving the system to expel pollutes more efficiently. To understand the flow characteristics of four models, this study only focuses on velocity field, temperature field, and concentration field varying with followings whether separation plate is set or not and the shapes of separation plates. The quantity of air, speed of exhaust fan and temperature and concentration of heating source are concerned as constant values. The three models having different shapes have one exhaust port and the model which has the vent at the closest position to where pollutes are generated is discovered to be the most efficient model. Compare to the initial model (having no separation plate), it was $1.4-1.9\%$ more efficient at temperature distribution and $9.4-11.9\%$ more at $CO_2$ concentration distribution.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1651-1656
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• 2003

The present study has been conducted to analytically investigate the thermal control performance of variable conductance heat pipe(YCHP) with axial grooves. The condenser port of the YCHP is occupied by a inert gas in which the concentration of gas is varied with the operation temperature and the heat transport capacity is thus varied with the operating temperature due to the variation of inert gas concentration. In this study, numerical evaluation for the thermal control of the YCHP with axial grooves is made from the 1st order diffusion model that considers the diffusive expansion of inert gas by concentration gradient. Ammonia is used as a working fluid and Nitrogen as a control gas in the Aluminum tube. As a result, the thermal performance of YCHP based on diffusion model has been compared with that of YCHP from flat front model. Additionally, it is found that the concentration of inert gas is distributed in the condenser region of YCHP with axial grooves.

• 한국자동차공학회논문집
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• 제2권3호
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• pp.113-122
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• 1994

This paper describes the effects of combustion parameters on the characteristics of combustion products in swirling flow furnace. The concentration of combustion products and temperature distribution of flow field in the furnace have been investigated by numerical method. The fuel was injected into the furnace and the swirling device was constructed with three kinds of vane swirler at inlet port of furnace. The results of this study showed that the effect of combustion parameters on the concentration characteristics of carbon monoxide and nitrogen monoxide of combustion products. It was found that the pollutant formation wad dependent on the equivalence ratio and swirl intensity level.

• 한국항해학회지
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• 제8권1호
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• pp.49-70
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• 1984

Spatial and temporal variations of hydrography and currents are investigated in the Southeastern Sea of Korea during October 1982. The distribution of the water mass of high salinity (>34.40${\textperthousand}$) and low dissolved oxygen concentration (<5.0ml/l) indicates that the Tsushima current flows northward as it passes the Western Channel of the Korea Strait. The cold water (<$6.0^{\circ}c$) with low salinity (<$34.20{\textperthousand}$) and high dissolved oxygen concentration (>6.0ml/l) reaches the bottom of the western channel of the Korea Strait after flowing southward leaning against the slope rather than following the deepest part of the Channel. Repeated sections in the Korea Strait show a remarkable change of hydrographic structure over a period of 4 days ; both warn and cold waters are intensified, particularly in the eastern part of the strait toward the Tsushima Island.

• 한국항해항만학회지
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• 제34권10호
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• pp.775-780
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• 2010

기계장치에 있어서 브레이크 시스템은 기계의 안전상 동작만큼이나 중요한 부분이다. 기계를 급히 정지시켜야하는 비상시에 기계가 멈추지 않으면 큰 사고로 발전할 수 있기 때문이다. 이것은 모든 기계장치에서 공통된 사항이며, 선박에서 또한 마찬가지이다. 선박에는 2종류의 계류장치가 존재한다. 그 중 하나는 항해하는 선박을 근해에 정박시키기 위해서는 해저에 닻을 내리는 윈드라스 윈치이며, 또 다른 하나는 배를 항구에 계류시키기 위한 무어링 윈치이다. 그 중 기존에 사용하는 무어링 윈치의 경우, 브레이크 밴드가 하나의 철판으로 만들어져 있으며, 브레이크 밴드와 라이닝을 연결하는 볼트의 파손이 발생하게 된다. 본 연구에서는 이 파손을 방지하기 위해 유한요소해석 프로그램을 사용하여 응력이 집중되는 부위를 선정하였고, 이 부위를 분리하여 응력 집중을 해소하였다, 또한 이 분리지점의 각도에 따른 해석을 수행하여 최적의 위치를 선정하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.463-467
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• 2004

Rosette-type diffusers with four-ports per riser are constructed in relatively shallow water in Korea. However, the trajectorial bending phenomena due to lower-pressure inside the surrounded buoyant jets on the riser was not considered in most models and was not observed without any experimental results. The buoyant jet behavior affected by the bending effect where there have been growing interests need to be verified experimentally and need to be preceded in the analysis of the characteristics of the buoyant jets oil a riser. The hydraulic model experiments have been carried out to investigate the characteristics of the behavior of horizontal buoyant jets discharged from a Rosette-type riser with four ports as well as single port over a certain range of the experimental conditions including initial momentum and initial buoyancy using LIF (Laser Induced Fluorescence) system to obtain concentration fields. The intensity of the fluorescent light in each pixel on the images obtained from LIF system with the tracer of Rhodamine H was converted to the local dye concentration with a set of calibration procedures to account for the non-uniform distribution of light intensity and the attenuation of light energy by water medium. The experimental results shows that the trajectories from Your ports tend to bend more and more to the inner side with the increase of the densimetric Froude number while the buoyant jet from a single port rises up without any bending phenomena. The previous models, VISJET and Seo et al. (2002), do not simulate the trajectories well except the region before the bending section. This study will focus on the analysis of the behavior of the buoyant jets for mainly a Rosette-type riser by conducting hydraulic model experiments using LIF system.

• 한국입자에어로졸학회지
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• 제12권1호
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• pp.1-9
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• 2016

In this work, we evaluated the characteristics of flow field and uniformity of the nose-only exposure chambers for the inhalation toxicity test. Computational fluid dynamics (CFD) modeling was carried out to demonstrate uniformity of the nose-only exposure chambers. Because it is very important in the inhalation toxicity experiments that test materials are distributed uniformly to each holder of the chamber. The test was done with these 3 types of chamber with different form to develop inhalation toxicity evaluation system, easy-to-operate system among exposure chamber used for evaluating inhalation toxicity of environmental chemical mixtures. Through CFD interpretation, nose-only exposure chamber was made with the selection of the optimal conditions. For its evaluation, one type of fragrance was selected and measured particle size distribution of each port. The gene becoming luminous to green fluorescence was combined with GPT-SPE, a type of tGFP vector, to be inhaled to the mouse. Based on this, luminous intensity was checked. As a result, total particle number concentration of each port had average value of $3.17{\times}10^6{\sharp}/cm^3$ and range of the highest and lowest concentration value was approximately ${\pm}4.8%$. Autopsy of lung tissues of mouse showed that it had clearly better delivery of gene compared to the control group.

• 한국항해항만학회지
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• 제33권3호
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• pp.235-240
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• 2009

해안철근콘크리트 구조물은 해수 또는 비래염분에 의하여 철근이 부식하게 되고 결과적으로 콘크리트에 균열로 발전하여 성능을 다하게 된다. 본 연구에서는 염해에 대한 해안 철근콘크리트 구조물의 내구성능 평가를 위하여 수치해석에 의한 결정론적 방법이 아니라 확률론에 입각한 성능평가를 위하여 확률론적 시뮬레이션 수법을 구축하였다. 시뮬레이션 수법으로는 몬테카를로법이 적용되었으며, 파괴확률에 대한 설계확률변수(표면염화물 농도, 초기 함유 염소이온농도, 철근의 피복두께, 염소이온 확산계수) 및 각각의 변동계수의 영향을 평가하였다. Fick의 확산방정식을 이용한 해석결과, 해안에서의 거리의 차 및 확산계수의 차에 의한 영향은 컸으며 상대적으로 변동계수의 영향은 그다지 높지 않다는 것을 알 수 있었다.