• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2006.11a
• /
• pp.255-260
• /
• 2006

천수만의 수리 역학 및 수질 모델을 위하여 3차원 수리역학 모델(EFDC)과 21개 수질 변수에 대한 수질 모델이 접합된 3차원 수리역학-부영양화 모델(HEM-3D)을 이용하였다. 관측 자료에 대한 모델 검증 결과, 조위는 관측치에 비해 5% 정도, 유속은 10% 정도 작은 값을 보였으며, 지각은 모델 결과치가 고정항에서 늦고 간월도에서 빠르게 나타났다. 수질 항목, 특히 용존산소의 관측치에 나타난 전반적인 분포 양상을 잘 재현하고 있었으며, 항목별 기여도 분석에서는 수질 모델이 퇴적물에 의한 산소 소비에 민감하게 반응하고 있으며, 용존산소 변화에 있어서 퇴적물에 의한 영향이 중요한 역할을 하고 있음을 보여주었다. 본 모델 결과는 기존의 모델들과 비교하여 천수만 해역의 해수 유동 특성을 잘 재현하고 있으며, 본 모델과 연계된 수질 모델의 오염물 확산과 수질 항목들의 거동을 이해할 수 있는 정보를 제공하였다. 그럼에도 불구하고 본 연구를 통하여 나타난 문제점은, 수질 예측 모델에 필요한 수질 변수들의 관측 자료와 양식장에 의한 오염 부하량 자료가 충분하지 못하며, 퇴적물에 의한 수질 변화를 정량화할 수 있는 모델의 개발이 시급하다는 것이다. 특히 퇴적물에 의한 산소 요구량은 유기퇴적물이 미생물 등에 의해 분해되는 과정에서 요구되는 산소량으로서, 해수 유동 조건의 변화와 오염부하에 의한 유기퇴적물의 집적이 주된 요인이다. 방조제 건설 이후 해수유동 조건의 변화와 더불어 지속적으로 오염물이 유입되고, 담수 및 천수만의 수질이 점점 악화되고 있다. 따라서 이러한 오염부하와 퇴적물에 대한 관리대책이 시급한 것으로 판단되며, 향후 정확한 수질 예측을 위해서는 본 연구에서 나타난 문제점들에 대한 재고가 필요할 것으로 사료된다.

• Proceedings of KOSOMES biannual meeting
• /
• 2006.11a
• /
• pp.155-158
• /
• 2006

한국 남해안 거제도 앞바다에 투하된 인공용승구조물에 대한 유통 변화를 파악하기 위해 ADCP(Acoustic Doppler Current Profiler)를 선박에 장착하여 정선관측을 실시하였다. 관측결과 구조물 투하전과 후의 유통비교를 보면 구조물 주변역에서 표층에서부터 수심 $30\sim40m$까지의 충과 그 이심까지의 흐름이 다르게 나타났다. 또한 구조물 주변역에서 연직유동성분의 흐름이 구조물 투하 전에는 하강류의 분포가 많이 나타났으나 구조물 투하 후에는 상승류의 성분이 많이 나타남을 알 수 있었다.

• Nuclear Engineering and Technology
• /
• v.2 no.1
• /
• pp.19-25
• /
• 1970

A study was conducted on the coolant mixing between water flowing in two adjacent subchannels. Measurements were made of the quantity of mass transferred between a larger rectangular channel and a smaller triangular channel in a 19-rod fuel bundle under the conditions of single phase flow and air-water two-phase flow. The results of the experiments showed that the low mixing rate appears in single phase flow, and high mixing rate was measured in air-water two-phase flow Mixing rate decreases with the increasing of air void fraction during the air-water flow. It seems that the high mixing rate in the air-water flow was caused due to adequate agitation of the chaotic air void.

• Journal of the Korean Chemical Society
• /
• v.40 no.6
• /
• pp.436-444
• /
• 1996

The characteristics of water have been studied for 1 year by means of relationships between tritium and total dissolved solid(TDS), tritium and conductivity, tritium and chloride, and tritium and total hardness for 15 springs in the vicinity of Jeonju city of Korea. From the results of the study, the springs were divided into four characteristic groups, but the characteristics of most springwaters studied were similar to those of rainfall. Fifteen springwaters were evaluated to see if those are tasty and healthy using the Hashimoto's Mineral Balance Index. As a result, only one spring (J-4) was found as tasty and healthy.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.14 no.1
• /
• pp.21-27
• /
• 2008

Triangular structure is used as basic shape of artificial structures for generating the upwelling current in order to make rich fishing ground at sea. Artificial upwelling current could bring the deep sea water containing a lot of nutrients from the bottom up to the surface. The purpose of this study is to examine the flow characteristics around underwater triangular structure with various stratification parameter. An experimental study was carried out for the triangular structure model in the circulating water channel to investigate flow characteristics by flow visualization method. A velocity fields around the underwater structure were measured by particle image velocimetry(PIV). The experimental results showed that the upwelling effect at the back and upper region of the structure could be best when the water depth was 2 times of the structure height and the stratification parameter was approximately 3.0. These quantitative data will be useful to determine the functional efficiency cf artificial upwelling structures.

• Journal of Energy Engineering
• /
• v.25 no.1
• /
• pp.69-75
• /
• 2016

Bubble size is a key parameter for an accurate prediction of bubble behaviours in the multi-dimensional two-phase flow. In the current STAR CCM+ CFD code, a mechanistic bubble size model $S{\gamma}$ is available for the prediction of bubble size in the flow channel. As another model, Yun model is developed based on DEBORA that is subcooled boiling data in high pressure. In this study, numerical simulation for the gas-liquid two-phase flow was conducted to validate and confirm the performance of $S{\gamma}$ model and Yun model, using the commercial CFD code STAR CCM+ ver. 10.02. For this, local bubble models was evaluated against the air-water data from DEDALE experiments (1995) and Hibiki et al. (2001) in the vertical pipe. All numerical results of $S{\gamma}$ model predicted reasonably the two-phase flow parameters and Yun model is needed to be improved for the prediction of air-water flow under low pressure condition.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.2
• /
• pp.224-231
• /
• 2011

Heating and/or cooling of the channel with pin-fin structure is a promising choice for the efficient heat transfer. Complex pin-fin structure shows highly irregular behavior like porous media. This study shows the numerical analysis on the characteristic of heat transfer and pressure drop of a channel with pin-fin structure. It predicts the experimental data quite well at the high porosity region with large diameter. Low porosity activates the rigorous flow disturbance and, consequently, the enhanced heat transfer. However, the concept of optimum design should be carefully reviewed because the pressure drop is also increased with decreasing porosity at low porosity region.

• The Korean Journal of Rheology
• /
• v.6 no.1
• /
• pp.20-29
• /
• 1994

본 논문에서는 실리콘 오일을 용매로 사용하여 조성된 전기유동유체의 전기장 부하 변화에 따른 역학적 특성을 고찰하였으며 그응용성에 대하여 연구하였다. 유체에 가해지는 전기장은 0~0.25kV/mm까지 변화시켰고 외부에서 가해지는 회전력은 0∼500rpm까지의 범위로 설정하였으며 용매의 점성계수 및 각각의 용매에 대한 입자 중량비를 달리하여 자체 조성한 4종류의 전기유동유체에 대하여 특성을 고찰하였고, 전기유동유체의 항복응력도 부 하되는 전기장의 함수로 증가함을 알수 있었다. 또한 부하되는 전기장의 크기 뿐만이 아니 라 입자의 중량비 용매의 점성계수도 전기유동유체의 거동에 많은 영향을 미침을 알수 있었 다. 또한, 전기유동유체를 이용한 응용예로서 지능구조물을 제작하여 전기장에 따른 진동특 성변화를 고찰하였다. 실험결과 부하되는 전기장의 강도가 증가함에 따라 구조물의 고유진 동수가 점차적으로 증가하였으며 입자의 중량비가 증가할수록 증가폭이 커 넓은 범위의 제 어영역을 가짐을 알수 있었다. 전기유동유체의 진동제어 이용가능성을 입증하기 위하여 시 간영역에서 구조물의 전기장에 대한 과도 진동제어 응답과 강제진동제어 응답을 실험하였다.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.8 no.2
• /
• pp.166-174
• /
• 2005

Plan of Logistics facility and Management of Freight trucks need for Efficient Improvement of Urban Goods Movement. For this, it need to clear flow pattern of Freight volumes and Freight trucks on urban space. Therefor, The purpose of this study is to clear space flow pattern of Freight volumes and Freight trucks as base data for Plan of Urban Goods Movement on Incheon city. Incheon city is selected because it is at sea & air ports and carries out various Activity of Urban Goods Movement. As the result of this study, it understands and analyzes Characteristic on flow pattern of Freight volumes and Freight trucks. Through this study, we'll expect that this results could be contributed in the understand of actual conditions of Freight volume and freight trucks and the basic data for Improvement of urban goods movement and the management policy of freight trucks in urban goods movement.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.20 no.2
• /
• pp.241-246
• /
• 2014

The purpose of this study is to investigate the flow characteristics around underwater triangular structure with various inclination and Reynolds number. A flow fields around the triangular structure model were measured by visualization method and PIV in the circulating water channel. The result of the experiment is where the triangular structure that has a inclination of $45^{\circ}$ and the reynolds number at $Re=2.9{\times}10^3$ showed rising velocity component to 2.7 times of the structure height. When the reynolds number is steady and when the inclination is greater the descending velocity component of the structure's rears current form is greatly shown and for the areas where it's more than y/hs=1.75 has a change in the angle of inclination but it doesn't give a great effect to it.