• 대기
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• 제30권4호
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• pp.377-390
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• 2020

Not only emissions, but also atmospheric circulation is a key factor that affects local particulate matters (PM) concentrations in Korea through ventilation effects and transboundary transports. As part of the atmospheric circulation, air stagnation especially adversely affects local air quality due to weak ventilation. This study investigates the large-scale circulation related to air stagnation over Korea during winter and projects the climate change impacts on atmospheric patterns, using observed PM data, reanalysis and regional climate projections from HadGEM3-RA with Modified Korea Particulate matter Index. Results show that the stagnation affects the PM concentration, accompanied by pressure ridge at upper troposphere and weaken zonal pressure gradient at lower troposphere. Downscaling using HadGEM3-RA is found to yield Added-Value in the simulated low tropospheric winds. For projection of future stagnation, SSP5-8.5 and SSP1-2.6 (high and low emission) scenarios are used here. It has been found that the stagnation condition occurs more frequently by 11% under SSP5-8.5 and by 5% under SSP1-2.6 than in present-day climate and is most affected by changes in surface wind speed. The increase in the stagnation conditions is related to anticyclonic circulation anomaly at upper troposphere and weaken meridional pressure gradient at lower troposphere. Considering that the present East Asian winter monsoon is mainly affected by change in zonal pressure gradient, it is worth paying attention to this change in the meridional gradient. Our results suggest that future warming condition increase the frequency of air stagnation over Korea during winter with response of atmospheric circulation and its nonlinearity.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.131-137
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• 2004

This paper is intended as an investigation of the deposition characteristics and mass transport flux estimation in the Nakdong estuary. In order to understand the effects of the tidal current circulation which influenced to an estuary terrain change, the seawater circulation calculation by the use of 2D numerical model for the three cases of without riverflow, mean and flood riverflow quantity condition practiced and each sectional net-flux of water quantity between sandbars(so called, dung) estimated. It may be that an estuary terrain change due to the large scale construction and reclamation at the Nakdong estuary influence to the long-time deposition characteristics. by the revim for the old research, we know that the development of the local sandbars has been moved toward the east-side from the west-side estuary area after the construction of the Nakdong river dike, at present the strong-acted location is the Bakhap-dung of the front sea of Tadea. The seawater circulation pattern at this large scale area of tidal flat bring on a change due to the water quantity outflowing from the Nakdong river. Base on the calculated results for the section net-flux of water quantity, we see that the accumulating action very strong at the local sea around Jangjado, Bakhapdung and Tadae for the case of flood riverflow quantity condition, but at the local sea around Jinudo for the another cases. Consequently, it is emphasized that in the Nakdong estuary the main sensitive regions which influenced from the discharge of riverflow were the local sea around Jangjado, Bakhapdung, Tadae and Jinudo.

• 한국유기농업학회지
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• 제21권3호
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• pp.335-350
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• 2013

With the efforts to development of renewable energy technologies, and increasing awareness to environmental issues, the usage of wood pallets has been increasing every year since the introduction of wood pallet technology to the domestic market. until 2009, majority usage of pellet boiler was in the residential houses. In an effort to increase the distribution of wood pellet boiler to cultivation facilities with high usage of fuels, The Ministry of Agriculture and Forestry has launched a distribution project of wood pellet boiler for fuel usage as a part of the agricultural and fishery energy efficiency projects. Although only small number of farms with a heat-culturing facility have replaced from conventional boiler to pellet boiler. Although part of reason for low usage of pallet boiler is lack of understanding and information of it, the main reasons are high initial cost and uncertainty of its cost efficiency. Also, most people from agricultural industry don't realize it's significance in terms of environmental benefit due to lack of understanding in 'resource circulation' and 'adopting to climate change'. In this study, first, we did a cost-efficiency analysis of the farm which uses a diesel boiler to grow cucumber, tomato, paprika. Then we replaced the diesel boiler to a pallet boiler and measured its cost-efficiency again. By comparing the cost-efficiency of the diesel boiler with the pellet boiler, we analyzed the economic viability of pellet boiler. Then we analyzed viability of pallet boiler usage in terms of 'resource circulation' and 'adopting to climate change'. As a result of our analysis, we have found out that under the current system of government support, the energy usage varies depends of the types crops grown and the higher the energy use, the more cost efficient it is to use the pallet boiler. Also, it is economically viable to use the pallet boiler in terms of 'resource circulation' and 'adopting to climate change'.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.1963-1973
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• 2020

Liquid metal-cooled reactors use various passive safety systems driven by natural circulation. Investigating these safety systems experimentally is more advantageous by using a simulant. Although numerous experimental approaches have been applied to natural circulation-driven passive safety systems using simulants, there has been no clear validation of the similarity law. To validate the similarity law experimentally, SINCRO-V experiment was conducted using Wood's metal and water for simulant of the Wood's metal. A pair of SINCRO-V facilities with length-scale ratio of 14.1:1 for identical Bo' was investigated, which was the main similarity parameter in temperature field simulation. In the experimental range of 0.2-1.0% of decay heat, the temperature distribution characteristics of the small water facility were very similar to that of the large Wood's metal facility. The temperature of the Wood's metal predicted by the water experiment showed good agreement with the actual Wood's metal temperature. Despite some error factors like discordance of Gr' and property change along the temperature, the water experiment predicted the Wood's metal temperature with an error of 27%. The validity of the similarity law was confirmed by the SINCRO-V experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기설비전문위원
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• pp.24-26
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• 2006

In these days, Korea Railway apply simple catenary system to general lines and high speed lines of Korea Electric Railway. Circulation Current in catenary system frequently bring undesirable consequences. Namely, the Connector wire has many problems according to a flow of excessive circulation (or traction current) and a sudden rise of temperature on catenary when electric car or locomotive is running in high speed. The occurrence of events by the load increasement do considerable damages to peoples, organizations and systems. In this paper, we proposed the improved changes on the catenary system of a improvement and change of a messenger wire protector, improvement of connector wire,s institution angle and of a replacement the connector wire with a dropper. A case of Circulation Current continually has broken out in Yongdungpo Electric Office's own bailiwick. By or through the medium of these obstacles, we have further use of many studies and considering countermeasures. Therefore, we have to deal with the question in design and execution of catenary system for High Speed Railway because we will spend a lot of time and more money for maintenance than for construction of that.

• International Journal of Vascular Biomedical Engineering
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• 제4권1호
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• pp.9-16
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• 2006

In this article we introduce computer models that have been developed in the past to determine the concentration of metabolic gases, the oxygen and carbon dioxide, along the pulmonary circulation. The terminal concentration of these gases in the arterial blood is related with the total change of the partial pressure of the same gases in the alveoli for the time beginning with inspiration and ending with expiration. It is affected not only by the ventilation-perfusion ratio and the gas diffusion capacity of the lung membrane but also by the pulmonary defect such as shunt, dead space, diffusion impairment and ventilation-perfusion mismatch. Some pathological pulmonary symptoms such as ARDS and CDPD can be understood through the mathematical models of these pulmonary dysfunctions. Quantitative study on the blood oxygenation process using various computer models is therefore of foremost importance in order to monitor not only the pulmonary health but also the cardiac output and cell metabolism. Reviewed in this paper include the basic and advanced methods that enable numerical study on the gas exchange and on the arterial oxygenation process, which might depend on the various heart and lung physiological conditions listed above.

• Ocean and Polar Research
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• 제38권4호
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• pp.271-286
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• 2016

We evaluate the temperature and salinity fields in the East Sea reproduced by the global ocean reanalysis data using HYbrid Coordinate Ocean Model (HYCOM for short). Temporal correlation of Sea Surface Temperature (SST) change between HYCOM and the Group for High Resolution Sea Surface Temperature (GHRSST) are higher in summer than winter. Though distributions of temperature and salinity in the HYCOM are similar to those from historical data (World Ocean Atlas 2013 V2), salinity in the HYCOM is lower (highter) in the region where the salinity is high (low). Temperature fields in the Ulleung basin of HYCOM are quite similar to those derived from Pressure-recording Inverted Echo Sounder (PIES), such as the correlation coefficient is higher than 0.7. This indicates that the HYCOM represents well the circulation and meso-scale phenomena in the Ulleung basin.

• Journal of the korean society of oceanography
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• 제35권4호
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• pp.161-169
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• 2000

A seasonal circulation in the East China Sea and the Yellow Sea and its possible cause have been studied with CSK data during 1965-1989. Water mass distributions are clear in winter, but not in summer because the upper layer waters are quite influenced by atmosphere. To solve the problem, a water mass analysis by mixing ratio is used for the lower layer waters. The results show that the distribution of Tsushima Warm Current Water expands to the Yellow Sea in winter and retreats to the East China Sea in summer. It means that there is a very slow seasonal circulation between the East China Sea and the Yellow Sea: Tsushima Warm Current Water flows into the Yellow Sea in winter and coastal water flows out of the Yellow Sea in summer. By the circulation, the front between Tsushima Warm Current Water and coastal water moves toward the shelf break in summer so that the flow is faster in the deeper region. The process eventually makes the transport in the Korea Strait increase. The Kuroshio does not seem to influence the process. A possible mechanism of the process is the seasonal change of sea surface slope due to different local effects of surface heating and diluting between the East China Sea and the Yellow Sea.

• 수산경영론집
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• 제33권2호
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• pp.153-168
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• 2002

Korea's marine products trade is taking for phase that income exceeds export after 2000. According to external environment change of Korea and Japan fishery agreement and an import liberalization of marine products, import of live fish and fresh fish is increasing rapidly. This study investigates import view of Japan live fish and fresh fish. Live fish which is imported from Japan has red seabream and seabass, but it is in declining tendency because of the increase in import of cheaper croaker from the China. If see importer's trend, entry to import business of fresh fish is eased a little. If a circulation trend is seen, However, it is thought that a future import trend is influenced by economic trends of Japan and the grade of place-of-production development of a domestic trader. Circulation market outside is common and the district wholesale store has played the important role. The import view of Japanese live fish and a fresh fish will increase against the background of maintenance of domestic circulation organization, and upgrading of marine product consumption However, it is thought that a future import trend is influenced by economic trends of Japan and the grade of place-of-production development of a domestic trader.

• 한국문헌정보학회지
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• 제50권3호
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• pp.429-453
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• 2016

이 연구는 대학도서관의 단행본 대출패턴을 대출건수 및 Bonn 이용계수 측면에서 주제별, 신분별, 계열별로 분석하였다. 이 연구에서는 대출건수의 과반 이상을 차지하는 도서를 '집중장서'라 정의하였으며, 전체 대출건수의 50%를 대출도서의 20%인 집중장서가 차지한다는 '대출도서 20/50 법칙'을 제안하였다. 각 주제별 대출건수 중 집중장서가 차지하는 비중을 이용계수를 이용하여 분석하였고, 월별 대출패턴과 대출기간도 분석하였다. 또한 대출횟수와 대출기간을 함께 고려한 '장서활용량'을 정의하고, 집중장서의 대출패턴을 대출횟수와 장서활용량 측면에서 비교분석하였다. 집중장서의 경우 총 대출건수와 총 장서활용량의 약 50%를 차지함을 알 수 있었고 모두 멱함수 분포도를 나타냄을 확인하였다.