• Korean Journal of Remote Sensing
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• v.36 no.5_4
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• pp.1255-1266
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• 2020

In this study, a complex simulation prototype was developed for rapid and accurate prediction of chemical dispersion range in order to reduce human casualties caused by chemical accidents. Complex simulation considered the leakage momentum during the near-field dispersion to take into account the leakage characteristics of the chemical. In the far-distance dispersion process, the wind distribution of the existing model, which was presented uniformly, was improved using weather and topographical information around the accident site, to realize a wind field similar to the actual one. Finally, the damage range was more precise than the existing model in line with the improved near- and far-distance dispersion process. Based on the results of damage range prediction of the complex simulation, it is expected that it will be highly utilized as a system to support policy decision-making such as evacuation and return of residents after a chemical accident.

• Journal of Soil and Groundwater Environment
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• v.11 no.4
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• pp.25-32
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• 2006

In this study, a novel bioreactor system using a diffuser type hollow fiber membranes (hollow fiber membrane diffuser, HFMD) was applied to investigate the feasibility and biodegradation capacity for the treatment of a gaseous mixture consisting of benzene, toluene and p-xylene(BTX). First, A mixed culture pre-acclimated to toluene effectively biodegraded the BTX mixture at an overall removal efficiency of approximately 70% for a 20-day operational period. It was found that the biodegradation of toluene was slightly inhibited because of the presence of benzene and p-xylene. Second, the elimination capacity (EC) of total BTX increased up to 360 $g/m^3/hr$, which was substantially higher than maximum ECs for BTEX reported in the biofiltration literature. Consequently, the hollow fiber membrane diffuser was considered as an alternative method over other conventional VOC-treating technologies such as biofilters.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.288-288
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• 2019

지구온난화로 인해 해수면이 지속적으로 상승하고 있으며, 이에 따라 연안인근 지역은 복합원인에 의한 홍수피해가 빈번히 발생하고 있다. 우리나라는 반도 지형으로 해수면 상승에 따라 침수피해 발생 시 피해규모가 클 것으로 예상되어 이에 적극적으로 대처할 필요가 있다. 복합원인에 의한 침수예상도는 해수위를 고려한 내외수 침수피해 발생 시 침수의 범위 및 양상을 예측한다. 먼저 침수발생 시 피해규모가 클 것으로 예상되는 연안인근의 도심지역을 위주로 대상지역을 선정하였으며, 침수발생 원인별 침수예상도를 작성하였다. 작성된 침수예상도를 바탕으로 상세 홍수취약성을 평가하였으며, 이를 바탕으로 주요 시설물의 위치 선정, 관거 개량의 우선순위 선정 등에 활용할 수 있다. 먼저 도상조사를 통해 침수발생 후보지역을 선정하고, 현장답사를 통해 현장 변경사항, 재해원인 및 재해발생가능성을 검토하여 대상지역으로 여수시 연등천 인근을 선정하였다. 모의 방법으로는 HEC-HMS 및 XP-SWMM 등 강우-유출 모형에 의해 침수해석을 실시하고, 하류단 경계조건의 변화에 따른 기점수위를 산정하여 해수위를 고려하였다. 하류단 경계조건으로는 대상지역의 폭풍해일에 의한 해수위 상승고를 적용하였다. 배수토구가 하천으로 연결된 경우에는 해당 하천의 홍수위 산정이 필요하며 홍수위 산정에는 HEC-RAS 모형을 사용하였다. 작성된 침수예상도를 통해 상세 홍수취약성 분석을 실시하였으며, 상세 홍수취약성 지수는 "기후변화 적응을 위한 연안도시지역별 복합원인의 홍수 취약성 평가기술 개발 및 대응방안 연구"에서 개발된 지표를 기반으로 산정하였다. 본 연구에서는 강우-유출 모형의 하류단 경계조건 변화를 통해 해수위 상승을 고려하여 연안도시 지역의 침수예상도를 작성하였으며, 침수발생 예상도를 통해 상세 홍수취약성을 분석하였다. 이는 침수발생에 따른 대피지도 개발, 주요 시설물의 계획, 침수피해 예방을 위한 구조적 대책 수립을 위한 기초자료로 활용될 수 있다.

• Journal of Institute of Convergence Technology
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• v.5 no.2
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• pp.27-32
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• 2015

Air intakes are an essential component of aircraft engines. They are mainly used to offer uniform airflows to engine faces. Fighter aircraft have to mask the engine face inside the fuselage in order to reduce the Radar Cross Section(RCS). Therefore, offset intakes like a S-Duct are one of promising components for this purpose. During a fight, it is unavoidable that the flow will enter the intakes at some face angles other than zero. In this case, the performance of the aircraft engine will be influenced to the angle of incidence. In this study, the CFD analysis of the semi-circular S-Duct with AR(0.5,0) is performed to investigate the influence of the angle of incidence on the performance of the S-Duct using a distortion coefficient. To consider the adverse pressure gradient, a $k-{\omega}$ SST turbulence model is employed. The secondary flow and flow separation are observed for all computational cases. It is found that the positive incidence angle produces the best performances.

• 한국지형공간정보학회:학술대회논문집
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• 1993.10a
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• pp.141-145
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• 1993

A new digital change detection algorithm, Euclidean Distance Analysis, was developed in an attempt to utilize the multi-band information in a selected band-comination, as an alternative to the conventional single-band analysis methods. To evaluate the relative performance of this new method, image differencing was applied. The better performance in change detection between the two algorithms investigated was provided by the Euclidean distance analysis. The new technique of Euclidean distance analysis holds promise for change detection, since it summarizes the multiple-band information on the cover-type changes and reduces the data dimensionality. It is suggested to further evaluate this new method, quantitatively, in the different environments. The use of different accuracy indices was also examined in the determining the optimal threshold level for each change image. As the standard measure for classification accuracy, the Kappa coefficient of agreement was used for evaluation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.371-376
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• 2007

Pan and rayon materials, two types of carbon fabric/phenolics composites, are using as thermal protectors for SRM's nozzle. After burning tests, It was required to analyze the performance of nozzles by ablated shape because ablative patterns were different from each other. For studying of performance on supersonic nozzles that have ablated shape, 1-dimensional analysis and numerical analysis were performed and results were presented in this paper. As the results of this study, in case of the thrust loss, rayon was predicted about 0.53% higher than pan and in case of total impulse loss, rayon was predicted about 0.4% higher than pan.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.376-380
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• 2012

자연재해위험지구란 자연재해로부터 안전하지 못하여 국민의 생명과 재산에 피해를 줄 수 있는 지역과 자연재해의 피해를 저감할 수 있는 시설을 포함한 주변지역으로서 자연재해대책법 제12조의 규정에 의하여 지정된 지구를 말한다. 자연재해대책법에 따라 시장 군수 구청장은 상습침수지역 산사태위험지역 등 지형적인 여건 등으로 인하여 재해가 발생할 우려가 있는 지역에 대하여는 자연재해위험지구로 지정 고시한다. 2010년에 특별 재고시 되어진 재해위험지구 지정현황을 비롯하여 최근 지정해제 등 변경사항을 고려하여 총 683개(2011년 현재)의 지구를 대상으로 조사한 결과, 침수위험지구는 401개(전체의 59%), 붕괴위험지구는 128개(전체의 19%), 유실위험지구는 98개(전체의 14%), 취약방재위험지구는 28개(전체의 4%), 고립위험지구는 18개(전체의 3%), 해일위험지구는 10개(전체의 1%)로 분석되었다. 본 연구에서는 2010년 특별 재고시된 자연재해위험지구(침수위험지구)의 2011년도 현황을 바탕으로 기 지정된 재해위험지구에 대한 대규모 하천정비 및 기후변화에 따른 침수위험의 변화영향을 검토하였다. 이는 대규모 하천정비 및 기후변화에 따른 기존의 침수영향변화를 복합적으로 검토하여 한강, 낙동강, 금강, 영산강 수계 자연재해위험지구(침수위험지구)의 복합 영향의 범위를 분석하였다.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.355-368
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• 2021

This study aims to identify appropriate tree species and crops for agroforestry target sites in North Korea based on ecological geography and site properties. To this end, an ecological geographic map (13 regions and 4 zones) of North Korea was made using satellite images and North Korean academic journal articles. The target agroforestry sites were selected and mapped according to 18 site conditions depending on 3 site characteristics, and the sites were divided into short-term and long-term target sites depending on the agroforestry management period. Finally, optimal combinations of 30 tree species and 19 crops were selected by overlapping the ecological geographic map and agroforestry target site map. For regions within the same zone, tree species and crops were almost similar; however, compared to regions in other zones, they differed. This is likely because the geographical climatic characteristics reflected in the ecological geographic map vary greatly from zone to zone. These results will be used to propose a combination of suitable tree species and crops that takes into account both management purposes and management types for inter-Korean forest cooperation in the agroforestry sector.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.4
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• pp.307-316
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• 2010

Complex terrain refers to irregular surface properties of the earth that influence gradients in climate, lateral transfer of materials, landscape distribution in soils properties, habitat selection of organisms, and via human preferences, the patterning in development of land use. Complex terrain of mountainous areas represents ca. 20% of the Earth's terrestrial surface; and such regions provide fresh water to at least half of humankind. Most major river systems originate in such terrain, and their resources are often associated with socio-economic competition and political disputes. The goals of the TERRECO-IRTG focus on building a bridge between ecosystem understanding in complex terrain and spatial assessments of ecosystem performance with respect to derived ecosystem services. More specifically, a coordinated assessment framework will be developed from landscape to regional scale applications to quantify trade-offs and will be applied to determine how shifts in climate and land use in complex terrain influence naturally derived ecosystem services. Within the scope of TERRECO, the abiotic and biotic studies of water yield and quality, production and biodiversity, soil processing of materials and trace gas emissions in complex terrain are merged. There is a need to quantitatively understand 1) the ecosystem services derived in regions of complex terrain, 2) the process regulation occurred to maintain those services, and 3) the sensitivities defining thresholds critical in stability of these systems. The TERRECO-IRTG is dedicated to joint study of ecosystems in complex terrain from landscape to regional scales. Our objectives are to reveal the spatial patterns in driving variables of essential ecosystem processes involved in ecosystem services of complex terrain region and hence, to evaluate the resulting ecosystem services, and further to provide new tools for understanding and managing such areas.

• Korean Journal of Remote Sensing
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• v.37 no.5_2
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• pp.1329-1340
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• 2021

The intertidal zone, which is a transitional zone between the ocean and the land, requires continuous monitoring as various changes occur rapidly due to artificial activity and natural disturbance. Monitoring of coastal topography changes using remote sensing method is evaluated to be effective in overcoming the limitations of intertidal zone accessibility and observing long-term topographic changes in intertidal zone. Most of the existing coastal topographic monitoring studies using remote sensing were conducted through high spatial resolution images such as Landsat and Sentinel. This study extracted the waterline using the NDWI from the GOCI-II (Geostationary Ocean Color Satellite-II) data, identified the changes in the intertidal area in Gyeonggi Bay according to various tidal heights, and examined the utility of DEM generation and topography altitude change observation over a short period of time. GOCI-II (249 scenes), Sentinel-2A/B (39 scenes), Landsat 8 OLI (7 scenes) images were obtained around Gyeonggi Bay from October 8, 2020 to August 16, 2021. If generating intertidal area DEM, Sentinel and Landsat images required at least 3 months to 1 year of data collection, but the GOCI-II satellite was able to generate intertidal area DEM in Gyeonggi Bay using only one day of data according to tidal heights, and the topography altitude was also observed through exposure frequency. When observing coastal topography changes using the GOCI-II satellite, it would be a good idea to detect topography changes early through a short cycle and to accurately interpolate and utilize insufficient spatial resolutions using multi-remote sensing data of high resolution. Based on the above results, it is expected that it will be possible to quickly provide information necessary for the latest topographic map and coastal management of the Korean Peninsula by expanding the research area and developing technologies that can be automatically analyzed and detected.