• 한국수산과학회지
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• 제52권1호
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• pp.92-96
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• 2019

The influence of water temperature (WT) on air temperature (AT) in the eastern and western coastal regions of the Korean peninsula in the winter was investigated using historical data from the Korean Meteorological Agency (KMA) and the National Institute of Fisheries Science (NIFS), focusing on the relationship between AT and WT. The data analysis shows that, during winter, the AT is generally higher by +1.9 to $+2.7^{\circ}C$ at Kangreung ($37.2^{\circ}N$) in the eastern region than at Inchon ($37.4^{\circ}N$) in the western region, i.e., the AT in the eastern region of the Korean Peninsula tends to be higher overall than that in the western region when similar latitudes are compared. On the other hand, in the winters of 1977-2006, the WT at Sokcho was higher by $+0.8^{\circ}C$ (January) to $+2.3^{\circ}C$ (March) than that at Sochungdo, directly resulting in increased AT ($+1.22^{\circ}C$) at Sokcho. This study suggests that higher AT in the eastern region during winter is caused by the influence of water flow, such as the East Korean Warm Current in the East/Japan Sea.

• 대한기계학회논문집B
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• 제20권4호
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• pp.1395-1405
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• 1996

The purpose of this experimental research is to investigate the local heat transfer characteristics in the upward free water jet impinged on a downward flat plate of uniform heat flux. The inner shape of rectangular nozzle used was sine curve type and its contraction ratio of inlet to outlet area was five. Experimental parameters considered were Reynolds number, nozzle exit-flat plate distance, and level of supplementary water. Local Nusselt number was influenced by Reynolds number, Prandtl number, supplementary water level, and distance between the nozzle exit and flat plate. Within the impingement region, the Nusselt number has a maximum value on the nozzle center axis and decreases monotonically outward from center. Outside of the impingement region, on the other hand, the Nusselt number has a secondary peak near the position where the distance from nozzle center reaches four times the nozzle width. However if nozzle exit velocity exceeds 6.2 m/s, the secondary peak appears also in the impingement region. The empirical equation for the stagnation heat transfer is a function of Prandtl, Reynolds, and axial distance from the nozzle exit. The optimum level of supplementary water to augment the heat transfer rate at stagnation point was found to be twice the nozzle width.

• 한국수산과학회지
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• 제41권2호
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• pp.134-139
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• 2008

To improve the oxygen-deficient water mass (ODW), the spatial and temporal variation in the water quality and characteristic of ODW occurrence were analyzed using yearly water quality data from 1989 to 2006 in Jinhae Bay, Korea. In addition, we estimated $ODW_{area},\;ODW_{vol.}$ and $ODW_R$ for Jinhae Bay. The overall water quality improved during the 2000s, based the annual variation in dissolved oxygen, chemical oxygen demand, etc. A cluster analysis classified Jinhae Bay into the southwestern, central, northern, and eastern regions. ODW occurred throughout the southwestern region in 1993 and 2002-2004, and the estimated $ODW_{vol.}$ was about $1.92km^3$. ODW did not occur in the eastern region because circulating seawater was exchanged in that part of Jinhae Bay. As ODW was generated every year in the southwestern region, this is the most polluted area in Jinhae Bay. The ODWR decreased in the northern region, showing that the water quality there has improved since a wastewater treatment plant began operating in 1994.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.27-36
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• 2020

Natural convection and thermal stratification phenomena are found in large water pools that are being used as heat sinks for decay heat removal from the reactor core using passive heat removal systems. In this study, the two-phase (water and air) natural convection and thermal stratification phenomena with conjugate heat transfer in the rectangular enclosure were investigated numerically using ANSYS Fluent 17.2 code. The transient numerical simulations of these phenomena in the full-scale computational domain of the experimental facility were performed. Generation of water vapour bubbles around the heater rod and evaporation phenomena were included in this numerical investigation. The results of numerical simulations are in good agreement with experimental measurements. This shows that the natural convection is formed in region above the heater rod and the water is thermally stratified in the region below the heater rod. The heat from higher region and from the heater rod is transferred to the lower region via conduction. The thermal stratification disappears and the water becomes well mixed, only after the water temperature reaches the saturation temperature and boiling starts. The developed modelling approach and obtained results provide guidelines for numerical investigations of thermal-hydraulic processes in the water pools for passive residual heat removal systems or spent nuclear fuel pools considering the concreate walls of the pool and main room above the pool.

• 한국물환경학회지
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• 제27권4호
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• pp.438-444
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• 2011

Magnesium is one of the abundant natural resources in the earth crust and seawater, which is directly related to various organisms activities interconnecting with water-rock system. In aqueous system, magnesium is known to predominantly exist in the form of $Mg^{2+}$ ion which is verified in its $E_h-pH$ diagram. When it is at equilibrium in aqueous system, temperature takes an essential role to complete equilibrium states. This study represents the change of the stable region of magnesium ion according to temperature, and how the consequences would affect aquatic organisms. It was revealed that there is a noticeable tendency shrinking the stable region of magnesium ion in a diagram as temperature increases, and as a result, aquatic bio-species presumably have difficulties to absorb the nutrient. Also, it was considered that the water system would be acidified by decreasing alkalinity.

• 지역연구
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• 제37권1호
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• pp.45-61
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• 2021

본 연구의 목적은 한강수계 물이용부담금을 둘러싼 이해당사자들의 갈등해결을 위한 최적방안을 제시하는 방법론적 틀을 설계하고, 분석결과를 통해 한강수계 물이용부담금 갈등해결을 위한 정책 방향을 제시하는 것에 목적을 두고 있다. 이를 위해 한강수계 물이용부담금을 두고 서로 다른 입장을 취하고 있는 의사결정자들 간의 다면적인 갈등의 메커니즘을 이해하는 과정이 선행되었으며 갈등해결을 위한 그래프모형을 적용하여 한강수계 물 이용부담금 갈등 해결을 위한 최적방안을 도출하였다. 분석결과에 따르면 한강수계 물이용부담금 갈등의 해결점을 찾을 수 있는 최적의 상태는 서울·인천 지역이 지속적으로 물이용부담금 인하를 요구하는 것과 동시에, 서울·인천·경기 지역이 기존 부과요율에 따른 부과금을 납부하는 것이다. 그리고 한강수계관리위원회는 갈등 해결을 위해 물이용부담금 부과요율 결정에 대한 의사결정구조 합리화, 서울·인천 지역에 대한 한강수계관리기금 지원근거 마련, 수혜 지역 및 주민의 특성을 고려한 한강수계관리기금의 투명한 운용 등을 포함하는 서울·인천 및 경기지역이 원하는 정책을 수립할 때 갈등의 해결점을 찾아갈 수 있었다. 본 연구는 한강수계 물이용부담금 갈등해결 관련 환경정책 방향을 수립하는데 객관적인 의사결정 정보 제공을 할 수 있고, 환경의 공동 사용에 따른 갈등과 관련된 유사한 후속연구에 방법론적인 기반을 제공할 것으로 기대된다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.116-116
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• 2020

Gilgit-Baltistan (GB) is a highly mountainous and remote region covering 45% of Upper Indus Basin (UIB) with around 1.8 million population is vulnerable to climate change and socio-economic growth makes water resources management and planning more complex. To understand the water scarcity in the region this study is carried out to project water supply and demand for agricultural and domestic sector under various climate-socio-economic scenarios in five sub catchments of GB i.e., Astore, Gilgit, Hunza, Shigar and Shyok for a period of 2015 to 2050 using Water Evaluation and Planning (WEAP) model. For climate change scenario ensembled mean of three global climate models (GCMs) was used under three different Representative Concentration Pathway (RCP) scenarios (RCP2.6, RCP6.0 and RCP8.5). The Shared Socioeconomic Pathways (SSPs) and agricultural Land Development (LD) scenarios were combined with climate scenarios to develop climate-socio-economic scenario. Our results indicate that the climate change and socio-economic growth would create a gap between supply and demand of water in the region, with socio-economic growth (e.g. agricultural and population) as dominant external factor that would reduce food production and increase poverty level in the region. Among five catchments only Astore and Gilgit will face shortfall of water while Shyoke would face shortfall of water only under agricultural growth scenarios. We also observed that the shortfall of water in response to climate-socio-economic scenarios is totally different over two water deficient catchments due to its demography and geography. Finally, to help policy makers in developing regional water resources and management policies we classified five sub catchments of UIB according to its water deficiency level.

• 대한원격탐사학회지
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• 제36권5_4호
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• pp.1245-1254
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• 2020

본 연구에서는 CCTV 영상을 이용한 기존 수위감지 알고리즘의 한계점을 보완하기 위하여 Region growing 기법을 적용하였다. 먼저 세 가지 기법(수평 투영 프로파일, Texture 분석, Optical flow)을 적용해 물 영역을 추정하고, 기법별 결과를 종합 분석하여 최초 수위를 설정하였다. 이후 최초 수위를 기준으로 Region growing을 통해 수위 변화를 지속적으로 감지하도록 하였다. 그 결과, 주변 환경요인에 영향 없이 수위를 올바르게 감지하였으며, 영상분석 결과에 대한 전반적인 오차 평균은 5% 미만인 것을 확인할 수 있었다. 또한, 본 알고리즘이 하천이 아닌 도심지 내 침수 도로 영상에서도 물 영역이 감지되는 것을 확인할 수 있었다. 이러한 결과는 전국에 설치된 수많은 CCTV 영상을 통해 자동적으로 수위를 감지함으로써 제한된 인력으로 상시 모니터링이 어려웠던 점을 보완할 수 있으며, 집중호우, 태풍 등으로 인해 발생되는 사고발생 위험성을 사전에 인지하여 예방할 수 있는 기반을 마련하는데 기여할 수 있을 것으로 생각된다.

• 한국농공학회논문집
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• 제51권1호
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• pp.27-32
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• 2009

The objective of this study is to assess the feasibility of wastewater reuse for the vegetable farming. The study region, about 250 ha in size, is located on the west coast of Jejudo, Korea. Major agricultural products of the study area are the cabbage, broccoli, garlic and onion. To confirm the feasibility of wastewater reuse, the drought duration and the water requirement analysis were conducted respectively. The average annual precipitation of the study region (1,121 mm) was smaller than that of Jeju island (1,975 mm). The drought duration for a ten-year return period in October through November was more than 20 days. The water requirement for irrigation was calculated by the FAQ Penman-Monteith method which took into account the cultivated crops, planting system, and meteorological conditions of the study region. The water requirement for a ten-year return period was estimated 4.7 mm/day and the water demand for irrigation was $4,584\;m^3/day$. As a result, the irrigation water for the crops was insufficient during their breeding season, especially in October through November. Thus, the result indicated that the study region required the alternative water supply such as wastewater reuse during the non-rainy season. As drought continues to place considerable stress on the availability of fresh water supplies in the study region, irrigation with reclaimed wastewater will play an important role in helping to meet future water demands.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.450-450
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• 2022

The study aims to develop scenarios for efficient groundwater use using existing wells in order to prepare for an eventual drought. In the recent decades, droughts are not only intensifying, but they are also spreading into territories where droughts used to be less intense and relatively infrequent. With the increasing disaster, efficient groundwater use is urgently needed not only to prevent the problem of groundwater depletion but also drought risk reduction. Thus, the research addressed the problem of efficient aquifer use as source of water during drought and emergencies. The research focused on well network system applied to Yanggok-ri in Korea using simulation models in visual MODFLOW. The approach consists to variate groundwater pumping rate in the most important wells used for irrigation across the study area and evaluate the pumping effect on water level fluctuation. From the evaluation, the pumping period, appropriate pumping rate of each well and the most vulnerable wells are determined for a better groundwater management. The project results divide the study area into two different regions (A and B), where the wells in the region A (western part of the region) show a crucial drop in water level from May to early July and in august as consequence of water pumping. While wells in region B are also showing a drawdown in groundwater level but relatively less compare to region A. The project suggests a scenarios of wells which should operate considering water demand, groundwater level depletion and daily pumping rate. Well Network System in relevant project, by pumping in another well where water is more abundant and keep the fixed storage in region A, is a measure to improve preparedness to reduce eventual disaster. The improving preparedness measure from the project, indicates its implication to better groundwater management.