• Korean Journal of Remote Sensing
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• v.36 no.2_1
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• pp.139-153
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• 2020

Using a computationalfluid dynamics(CFD) model, thisstudy evaluated the representativeness of an air quality monitoring system (AQMS) in an urban area and presented a methodology to determine the suitable AQMS locations for specific purposes. For this, we selected a 1.6 km × 1.6 km area around the Eunpyeong-gu AQMS (AQMS 111181) as a target area. We conducted simulationsfor two emission scenarios (scenario one: air pollutants transported from inflow boundaries, scenario two: air pollutants emitted from roads). Urban airflows were markedly influenced by mountainous terrain located in the northeast and southeast of the target area, and complicated airflow patterns occurred around the buildings. The distributions of air pollutants were dependent on the terrain (mountain) in scenario one, but the road location and building height in scenario 2. We evaluated whether the AQMS could represent the air quality in the target area based on the simulations for two scenarios. The concentrations simulated at the AQMS were similar in magnitude to the layer mean concentrations, which indicated good representativeness for the air quality in the target area. We also suggested which locations were suitable for different measurement purposes (hot spots, clean zones, average zones, shelter zones, equi-background zones).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.2
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• pp.115-132
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• 1992

This study was conducted to clarify the distribution pattern of macrobenthic soft-bottom dwelling animals near the shellfish farming ground in Chinhae Bay, Korea Sampling was seasonally performed with van Veen grab$(0.1m^2)$ from October 1990 to July 1991. Benthic animals collected during the study comprised 107 species which amounted to 6,978 individuals: 52 species from polychaetes$(48.6\%)$, 34 species from crustaceans$(31.8\%),$ 14 species from molluscs$(13.1\%)$ and 7 species from other faunal groups$(6.5\%)$. The dominant species were four polychaetes and one amphipod: Lumbrineis longifolia, Capitella capitate, Mediomastus sp., Sigambra tentaculata and Erictonius pugnax. The study area could be divided into 3 regions based on the faunal similarity which was closely related to the content of organic matter in the surface sediment. The benthic community located near the shellfish farming ground showed large spatial and seasonal variations in species diversity and evenness in contrast to the stable values off the farming area. The oxygen deficient water mass below 2 ml/l In thi bottom layer during the summer stressed and depauperated the benthic community in the autumn of 1990. However, the benthic community did recover during the winter. It is postulated that the cyclic phenomenon of summer mortality followed by winter recovery may be a common characteristic in benthic communities subjected to a high level of organic pollution.

• Journal of Korea Multimedia Society
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• v.9 no.11
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• pp.1421-1434
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• 2006

Spatial data warehouses provide analytical information for decision supports using SOLAP (Spatial On-Line Analytical Processing) operations. Many researches have been studied to reduce analysis cost of SOLAP operations using pre-aggregation methods. These methods use the index composed of fixed size nodes for supporting the concept hierarchy. Therefore, these methods have many unused entries in sparse data area. Also, it is impossible to support the concept hierarchy in dense data area. In this paper, we propose a dynamic pre-aggregation index method based on the spatial hierarchy. The proposed method uses the level of the index for supporting the concept hierarchy. In sparse data area, if sibling nodes have a few used entries, those entries are integrated in a node and the parent entries share the node. In dense data area, if a node has many objects, the node is connected with linked list of several nodes and data is stored in linked nodes. Therefore, the proposed method saves the space of unused entries by integrating nodes. Moreover it can support the concept hierarchy because a node is not divided by linked nodes. Experimental result shows that the proposed method saves both space and aggregation search cost with the similar building cost of other methods.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.2
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• pp.100-116
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• 2019

Urban green spaces, as a means to mitigate social problems and environmental risks, are getting more attention in evaluating urban environment. The inequity of green space distribution is becoming a major issue in urban planning and management. This study investigated the characteristics of green space in 3 districts (Jung-gu, Dongdaemun-gu, Seongdong-gu), that are composed of 46 administrative divisions in central Seoul, to analyze the environmental equity of urban green spaces. The correlations between the amount of green space, including the coverage of street trees, and the socioeconomic status of each administrative division were analyzed. To deduce the effects of plant coverage on the urban temperature regime, the relationship between the normalized difference of vegetation index (NDVI) and land surface temperature (LST) was analyzed. The research revealed that the mean NDVI of an administrative division was negatively correlated with the percentage of basic living recipients and disabled people. The LST of a division with low NDVI was higher due to the lack of green coverage. Such environmental inequities were closely related to residential building type, which was strongly affected by the economic status of residents. The LST of an apartment area was $2.0^{\circ}C$ lower than that of single-family houses and multi-housing areas. This is expected as the average NDVI of the apartment area was more than twice as high as the other environments considered in this study. The inequity can be exacerbated without urban planning which is deliberately designed to reduce it.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.3
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• pp.220-225
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• 2013

Accidents between ships occur frequently at the traffic congestion area. Once a maritime accidents occur, it is likely to end up with critical damaged accidents. This paper develop a simulator for assessing quantitative risk based on statical maritime traffic data and realtime traffic distribution. Ship's passage risk assessment simulator consist of import of division of passage data, traffic distribution analysis and passage risk assessment analysis. Maritime traffic data of WANDO waterway apply to simulator for calculation of quantitative risk rate of waterway.

• The Journal of the Korea Contents Association
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• v.5 no.6
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• pp.129-137
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• 2005

A performance analysis of LEO Satellite Communication Service is being made in a variety of ways. In this paper we examined the variation of interference caused by the distribution of terminals within a cell and the maximum number of users according to the average distance between terminals, which had not been considered in former researches. Also we examined the interference made by sopt beam isolation value of some antennas(tapered-apertured antenna, gaussian antenna) which are used on LEO Satellite Communication Service Assigning this interference to the bandwidth of channels in LEO Satellite Communication Service, and with principal parameters(bandwidth, number of carrier) we made a performance analysis. And comparing tapered-apertured antenna with gaussian antenna we will find out which one is more effective and more suitable for interference.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.154-158
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• 2006

유역종합치수계획 수립시 유역내 해당 지점에서의 하도와 유역에 대한 홍수량 배분은 원활한 목표연도 홍수량 처리, 치수안전도 증대, 치수경제성 등을 고려하여 하도 및 유역에서 실현 가능한 모든 홍수방어대안 등을 검토하여 적절한 홍수량이 분담되도록 결정되어야 한다. 그러나 기존 문헌 및 연구에서 제시하고 있는 홍수량 배분에 대한 규정은 구체적이지 못하고 추상적이며 계획수립시 하도 홍수소통능력에 대한 객관적인 기준과 고려없이 하도분담량을 설정하고 있다. 이에 본 연구에서는 하도 홍수소통능력 평가에 대한 합리적인 기준설정이 필요하다고 판단되어 기존의 문헌 및 사례 등을 종합 분석하여 하도의 홍수소통능력 평가기법을 개발하였다. 하도 홍수소통능력의 판단기준은 하천내 유수의 소통능력은 물론, 하도내 수위가 높음으로 인해 내수배제가 원활히 이루어지지 못해 발생하는 홍수피해를 최소화할 수 있도록 5단계로 구분하였다. 그리고 제내지의 토지이용현황, 자산분포와 인구밀집도 등을 고려한 평가기준이 될 수 있도록 하였다. 내수에 대한 하도 홍수소통능력 검토시 도시하천의 경우에는 홍수피해 위험이 높고 자산이 많이 분포되어 있는 하천구간은 소파기준에 해당하는 침수심 0.5m 기준을 적용하였다. 그리고, 농경지하천의 경우는 농경지 침수시간에 따른 작물 피해액 기준을 도시하천의 개념과 유사하게 적용하여 홍수피해잠재능이 높은 지역에 위치한 하천의 경우는 침수지속시간이 24시간 이내가 되도록 적용하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.299-306
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• 1989

The combined convective heat transfer from vertical parallel plates with constant temperature has been studied by numerical method. The governing equations for the system are solved by the finite difference method and successive over relaxation scheme for Re$_{L}$ = 50 - 500, Gr = 10$^{4}$, Pr = 0.7. Results for various plate spacings and plate lengths are as follows ; For various plate spacings, the mean Nusselt number increases and then decreases as the dimensionless plate spacing increases. The optimum plate spacing for maximum mean Nusselt number decreases with increasing Reynolds number and can be expressed as a function of Reynolds number. For various plate lengths, the mean plate Nudest number increases as the dimensionless plate length decreases and Reynolds number increases.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2002.11a
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• pp.61-71
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• 2002

광양만내 해양바이러스양은 2.0$\times$$10^{8}$ particles/ml로 매우 풍부했다. 각 계절별 바이러스의 밀도는 여름에 최대 9.0$\times$$10^{8}$ particles/ml에서 겨울에는 최소값인 0.7$\times$$10^{8}$ particles/ml을 기록했다. 광양만 내의 바이러스, 박테리아, 식물플랑크톤 생물량의 공간적 분포는 open ocean system에 해당하는 정점 28, 38, 42, 46, 51에서 보다 closed estuarine system에 해당하는 정점 2, 5, 10 ,12, 16, 20에서 많은 것으로 나타났다. 그리고, 다른 closed estuarine system에 해당하는 정점 22, 26, 32, 34는 높은 바이러스 밀도를 보였지만 상대적으로 open ocean system에 비해서 낮은 박테리아와 식물플랑크톤의 생물량을 나타냈다. 몇몇 정점의 수심 깊이에서는 박테리아의 밀도가 바이러스의 밀도를 100배정도 초과했다. 해양 바이러스와 그들의 host system의 계절별 밀도는 역동적으로 번화했으며, 그들의 계절별 변화는 밀집한 상호연관성을 가졌다. 여름에 바이러스와 박레리아의 밀도는 증가된 반면 식물플랑크톤의 엽록소-a 농도는 평균값을 유지하였다. 겨울에는 바이러스와 박테리아의 밀도가 급속하게 줄어들었고, 마찬가지로 엽록소-a 농도 역시 감소하다가, 곧 다시 증가했다. 바이러스의 밀도는 2001년 8월에 최고점에 도달했으며, 박테리아의 밀도는 2001년 8월과 2002년 6월에 최고값을 가졌다. 반면에 엽록소-a의 농도는 2002년 4월에 최대치에 도달했다. 전체 host와 바이러스 밀도로 볼 때, 그들의 pool은 바이러스에 의한 mortality에 의해서 steady-state 상태로 유지되고, 바이러스의 밀도 또한 steady-state를 유지하는 것으로 보였다. 이러한 시도는 우리 나라 광양만 내에 존재하는 해양 바이러스의 생태적 분포 연구를 다루는 첫 번째 실험으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.981-981
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• 2012

최근 지구환경 변화에 따른 기후변화의 영향으로 자연재해의 형태는 점차 대형화, 다양화되고 있으며 극치사상의 발생 빈도가 계속해서 증가하고 있는 추세이다. 특히 도시하천의 경우 인구와 재산이 밀집해 있어 기후변화에 따른 홍수위험 및 취약성이 클 것으로 사료된다. 본 연구에서는 기후 변화에 따른 홍수위험 및 취약성 분석을 위하여 위험도 기반 불확실성을 다루는 수단으로 UQR-MCS (Upper Quartile Range-Monte Carlo Simulation)을 적용하였으며, 다양한 형태의 확률 분포로부터 특정변량(variable)의 확률분포 Quartile을 모의하였다. 또한 기후변화에 따른 도시하천의 홍수위험 및 취약성 평가를 위하여 도시하천에 적합한 홍수위험 및 취약성평가 지수(FVI: flood vulnerability index)를 산정하였으며, 홍수취약성지수는 기후변화(Climate change)와 도시화(Urbanization), 제방월류위험(Overtopping risk) 및 홍수범람 면적(Flood area) 등의 지표를 사용하였다. 각각의 지표는 엔트로피(Entropy) 기법을 적용하여 가중치를 부여하였으며, 표준화과정을 통한 일반화된 지표 값을 산정하였다. 우이천 유역의 기후변화에 따른 홍수위험 및 취약성 지표값은 KMA RCM A1B 시나리오자료를 바탕으로 추정한 미래 확률강수량과 각 인자별 재현기간에 따른 수문변량의 변화를 통하여 산정하였다. 본 연구의 결과는 향후 도시하천의 기후변화에 따른 홍수위험도분석 및 취약성 평가, 극치 수문사상에 대한 신뢰성 있는 분석과 더불어 예상치 못할 이상홍수에 대비한 하천방재 연구에 도움이 되리라 사료된다.