• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.748-754
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• 2010

The contents of soil organic matter (SOM) and $Al_o+1/2Fe_o$ in soils are important criteria for the classification of new Andisols in Soil Taxonomy system. There are many soil types in Jeju Island with various soil forming environments. This paper was conducted to estimate the contents of soil organic matter and the content of ammonium oxalate extracted Al and Fe ($Al_o+1/2Fe_o$) using various environmental variables and to make soil property maps using a statistical analyses. The soil samples were collected from 321 locations and analyzed to measure the contents of SOM and $Al_o+1/2Fe_o$. It was analyzed the relationships among them and various environmental variables such as temperature, precipitation, net primary product, radiation, evapotranspiration, altitude, soil forming energy, topographic wetness index, elevation, difference surrounded area, and distances from the shore and the peak. We can exclude multi-collinearity among environmental variables with principal component analysis and reduce all the variables to 3 principal components. The contents of SOM and $Al_o+1/2Fe_o$ were estimated by multiple regression models and maps of them were made using the models.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1307-1311
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• 2007

유역의 자연 유출량이 줄어드는 갈수기 동안 낙동강 본류의 수질은 상류지역의 댐 방류량에 큰 영향을 받는다. 따라서 수질이 취약한 중 하류부지역의 수량과 수질을 종합적으로 고려한 낙동강 수계의 물 관리를 위해서는 댐 방류량과 하류 수질의 정량적인 관계에 근거한 다목적댐군의 연계운영이 필요하다. 본 연구의 목적은 정상상태 하천수질모델을 이용하여 낙동강수계 다목적댐군의 방류량과 하류 하천의 수질 관계를 정량적으로 분석하고, 갈수기 동안 낙동강 수질개선을 위해 필요한 적정 댐 용수공급 시나리오를 제시하는데 있다. 낙동강수계 댐 군의 하류 하천 수질을 고려한 저수지운영 계획 수립을 지원하기 위하여 1차원 정상상태 수질예측모델인 QUAL2E를 구축하고 실측 유량과 수질자료를 이용하여 모델을 보정하고 검증하였다. 검증된 모델은 낙동강수계 상류에 위치한 안동댐, 임하댐, 그리고 중 하류 지류에 위치한 합천댐과 남강댐의 용수공급 시나리오별 하천 수질개선 효과를 분석하는데 적용하였다. 연구결과 낙동강 수질이 악화되는 갈수기 동안 중 하류부에 위치한 상수원의 수질을 개선하기 위해서는 합천댐과 남강댐에서보다는 상류에 위치한 안동댐과 임하댐에서 용수를 추가 공급하는 것이 더욱 효과적인 것으로 평가되었다. 댐 방류량 증감에 따라 수질영향을 가장 크게 받는 하천구간은 수질오염도가 가장 크게 나타나는 금호강합류점${\sim}$고령교구간인 것으로 분석되었다. 본 연구결과는 낙동강과 같이 수량이 부족한 하천은 오염부하량 삭감 대책과 함께 갈수기 유량조절이 매우 중요한 요소임을 보여주며, 주기적인 수질악화를 겪는 낙동강 중 하류 지역의 수질개선을 위한 상류 다목적댐군의 연계운영 계획 수립에 활용될 수 있을 것으로 사료된다.치모의 결과와 현장에서 관측한 유속장을 비교함으로써 본 연구에서 제시한 실제 탁수배제능력을 검증하였다.를 구축하였다는데 의의가 있다.로와 접하는 건물의 경우 모서리부 광고 효과가 지배적이며 대부분 곡선돌출형이 사용되고 있었다. 그러므로 모서리 저층부를 필로티로 계획하여 보행흐름을 원활하게 하고 대신 입면을 투명하게 하여 간접광고(내부전시) 효과를 유도하는 것이 좋다. 특히 원형모서리는 건물 특화 성격이 강하므로 불가피할 경우 소형 액센트 광고 위치를 미리 벽면으로 할애하는 것이 경관 및 입면계획에 유리한 것으로 분석되었다. 불확실도 해석모형 등의 새로운 기능을 추가하여 제시하였다. 모든 입출력자료는 프로젝트 단위별로 운영되어 data의 관리가 손쉽도록 하였으며 결과를 DB에 저장하여 다른 모형에서도 적용할 수 있도록 하였다. 그리고 HyGIS-HMS 및 HyGIS-RAS 모형에서 강우-유출-하도 수리해석-범람해석 등이 일괄되게 하나의 시스템 내에서 구현될 수 있도록 하였다. 따라서 HyGIS와 통합된 수리, 수문모형은 국내 하천 및 유역에 적합한 시스템으로서 향후 HydroInformatics 구현을 염두에 둔 특화된 국내 수자원 분야 소프트웨어의 개발에 기본 토대를 제공할 것으로 판단된다.았다. 또한 저자들의 임상병리학적 연구결과가 다른 문헌에서 보고된 소아 신증후군의 연구결과와 큰 차이를 보이지 않음을 알 수 있었다. 자극에 차이가 있지 않나 추측되며 이에 관한 추후 연구가 요망된다. 총대장통과시간의 단축은 결장 분절 모두에서 줄어들어 나타났으나 좌측결장 통과시간의 감소 및 이로 인한 이 부위의 통과시간 비율의 저하가 가장 주요하였다. 이러한 결과는 차가운 생수 섭취가 주로 결장 근위부를 자극하는 효과를 발휘하는 것이

• The Journal of Engineering Geology
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• v.17 no.3
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• pp.393-404
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• 2007

The purpose of this study is to capture the essentials in survey and evaluation scheme which are able to assess the hazard of a rock slope systematically. Statistical analysis are performed on slope instability parameters related to failure of the rock slope. As the slope instability parameters, twelve survey items are considered such as tension crack, surface deformation, deformation of retaining structures, volume of existing failures, angles between strike of discontinuity and strike of cut slope face, angles between dip of discontinuity and dip of cut slope face, discontinuity condition, cut slope angle, rainfall or ground water level, excavation condition, drainage condition, reinforcement. A total of 233 road cut slopes located in Gyeongnam were considered. The stability of the road cut slopes were evaluated by estimating the slope instability index(SII) and corresponding stability rank. 126 rock slopes were selected to analyze statistical relation between SII and slope instability parameters. The multiple regression analysis was applied to derive statistical models which are able to predict the SII and corresponding slope stability rank. Also, its applicability was explored to predict the slope failures using the variables of slope instability parameters. The results obtained in this study clearly show that the methodology given in this paper have strong capabilities to evaluate the failures of the road cut slope effectively.

• Journal of Korea Water Resources Association
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• v.30 no.4
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• pp.317-326
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• 1997

The Palmer Drought Severity Index has been ectensively used to quantitatively evaluate the drought severity at a location for both agricultural and water resources management purposes. In the present study the Palmer-type formula for drought index is drived for the whole country by analyzing the monthly rainfall and meteorological data at nine stations with a long period of records. The formula is then used to compute the monthly drought severity index at sixty-eight rainfall stations located throughout the country. For the past five significant drought periods the spatial variation of each drought is shown as a nationwide drought index map of a specified duration from which the relative severity of drought throughout the country is identifiable for a specific drought period. A comparative study is made to evaluate the relative severity of the significant droughts occurred in Korea since 1960's. It turned out that '94-'95 drought was one of the worst both in the areal extent and drought severity. It is found that the Palmer-type formula is a very useful tool in quantitatively evaluating the severity of drought over an area as well as at a point. When rainfall and meteorological forecast become feasible on a long-term basis the method could also be utilized as a tool for drought forecasting.

• Korean Journal of Ecology and Environment
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• v.52 no.1
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• pp.50-64
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• 2019

Recently, quantitative analyses of food web structure based on carbon and nitrogen stable isotopes are widely applied to environmental assessments as well as ecological researches of various ecosystems, particularly rivers and streams. In the present study, we analyzed carbon and nitrogen stable isotope ratios of POM (both planktonic and attached forms), zooplankton, benthic macroinvertebrates and fish collected from 6 sites located at Nakdong River. Samples were collected from upstream areas of 5 weirs (Sangju, Gangjeong-Goryeong, Dalseong, Hapcheon-Changnyeong, and Changnyeong-Haman Weirs) and one downstream area of Hapcheon-Changnyeong Weir in dry season (June) and after rainy season (September). We suggested ranges of their carbon and nitrogen stable isotope ratios and calculated their trophic levels in the food web to compare their temporal and spatial variations. Trophic levels of organisms were relatively higher in Sangju Weir located at upper part of Nakdong River, and decreased thereafter. However, the trophic levels were recovered at the Changnyeong-Haman Weir, the lowest weir in the river. The trophic level calculated by nitrogen stable isotope ratios showed more reliable ranges when they were calculated based on zooplankton than POM used as baseline. The suggested quantitative ecological information of the majority of biological communities in Nakdong River would be helpful to understand the response of river food web to environmental disturbances and can be applied to various further researches regarding the quantitative approaches for the understanding food web structure and function of river ecosystems as well as restoration.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.952-957
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• 2005

A sensitivity analysis study was performed to examine the effects of cell size on a distributed non-point source pollution model. The model, AnnAGNPS, whiff is a modified version of USDA's AGNPS, was applied to Eung stream watershed, a tributary of Cheongmi stream located in the South Branch of Han River System. The model components and results, such as channel length, slope, land use, and delivery ratio, were analyzed according to the various cell sizes from 10 to 200 ha. As cell sire increases, channel length decreases due to short-circuiting of meandering creek. The decreased channel length has more significant effects on the model results than any other geomorphological change. When the effects of land use and soil distribution are excluded, sediment delivery loads increase due to shorter time to reach the outlet of the watershed in larger tell size. When those effects are included, however, sediment delivery loads decrease in larger fell size because the variety of land use types can not be inputted. The predominant land use in the applied watershed is forest with very low soil erosion such that the predicted sediment delivery might be much lower than real system. The cell size of 30 ha was determined to produce the most appropriate resolution. Surface runoff and non-point source loads of TN, TP and BOD were predicted and the results agree well with the field measurements. From this study, it was shown that the model results would be very dependent on variations of topography, land use, and soil distribution, as a function of cell size, and the optimum cell size is very important for successful application of distributed non-point source pollution model.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.3
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• pp.48-62
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• 2018

In this study, landslide of debris flow occurred at 51 sites around Daeryounsan located in between Chuncheon-si and Hongcheon-gun during July in 2013 were investigated in field and behavior characteristics of debris flow were analyzed on the basis of records of rainfall and site investigation. According to debris flow types of channelized and hill slope, location and slope angle of initiation and deposit zone, and width and depth of erosion were investigated along entire runout of debris flow. DEM(Digital Elevation Model) of Daeryounsan was constructed with digital map of 1:5,000 scale. Land slide hazard was estimated using SINMAP(Stability INdex MAPping) and the predicted results were compared with field sites where debris flow occurred. As analyzed results, for hill slope type of debris flow, predicted sites were quite comparable to actual sites. On the other hand, for channelized type of debris flow, debris flow occurrence sites were predicted by using stability index associated with topographic wetness index. As analyzed results of 4 different conditions with the parameter T/R, Hydraulic transmissivity/Effective recharge rate, proposed by NRCS (Natual Resources Conservation Service), predicted results showed more or less different actual sites and the degree of hazard tended to increase with decrease of T/R value.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.547-553
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• 2016

Black carbon (BC) contained in particulate matter (PM) originating from the exhaust gases of ships' diesel engines has been receiving great attention as a cause of glacial melting and warming in the polar regions. In this study, we took samples from various locations of PM emitted from the training ship (T/S) HANBADA's main engine, in cooperation with the Korea Maritime and Ocean University. We analyzed the structure and characteristics of these samples using high-resolution transmission electron microscopy (HR-TEM) and applied our findings as fundamental research for developing PM reduction technology. We also employed our results to determine appropriate preemptive action to meet upcoming PM/BC regulations. In addition, we confirmed the emission trend of pollutants from exhaust gases under various engine operating conditions using an exhaust gas analyzer. Results obtained from the analysis of HR-TEM images showed that the structure of the PM is chain-like wispy agglomerates consisting of a number of individual spherical particles. As the sampling location was moved away from the turbo charger (T/C) towards the funnel, more condensates were observed at a low temperature and the molecular structure of the PM lost its characteristic BC structure as an amorphous structure gradually appeared. Furthermore, through the analysis of exhaust gases, we predicted a decrease in PM concentration in the exhaust stream as engine rpm increase.

• Journal of Korea Water Resources Association
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• v.51 no.6
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• pp.481-490
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• 2018

Recently, the spatiotemporal patterns of flood disasters have become more complex and unpredictable due to climate change. Flood hazard map including information on flood risk level has been widely used as an unstructured measure against flooding damages. In order to product a high-precision flood hazard map by combination of hydrologic and hydraulic modeling, huge digital information such as topography, geology, climate, landuse and various database related to social economic are required. However, in some areas, especially in developing countries, flood hazard mapping is difficult or impossible and its accuracy is insufficient because such data is lacking or inaccessible. Therefore, this study suggests a method to delineate large scale flood-prone area based on topographic factors produced by linear binary classifier and ROC (Receiver Operation Characteristics) using globally-available geographic data such as ASTER or SRTM. We applied the proposed methodology to five different countries: North Korea Bangladesh, Indonesia, Thailand and Myanmar. The results show that model performances on flood area detection ranges from 38% (Bangladesh) to 78% (Thailand). The flood-prone area detection based on the topographical factors has a great advantage in order to easily distinguish the large-scale inundation-potent area using only digital elevation model (DEM) for ungauged watersheds.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1817-1821
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• 2010

본 연구에서의 지리정보시스템(GIS)을 이용한 사방댐 입지선정모델 개발은 산사태 발생 예측을 위한 사면안정성 평가 기준을 개발하여 사방댐 지점을 선정하기 위하여 체계적으로 표준화된 시스템을 구축하는 것이 목표이며, 2002년 태풍 '루사'와 2003년 태풍 '매미'에 의하여 토석류와 산사태가 발생한 서부경남 지역의 38개 지점에 대하여 항공사진 수집 및 현장조사를 수행하고, 산사태 발생에 관계되는 강우, 지형, 지질 및 토양, 임상 등을 인자로서 규정하였다. 연구결과 서부경남지역에서 발생한 산사태는 지리산, 가야산, 좌굴산 등 EL. 500m 이상의 비교적 고도가 높은 산악지역에서 지형성 집중호우에 의하여 발생하는 것으로 분석되었으며, 강우량과 산사태의 상관분석결과 시강우량 70mm 이상 및 누가강우량 230mm 이상에서 산사태의 발생빈도가 높은 것으로 나타났다. 또한 산사태 발생지점에서의 고도(평균해수면 기준)와 능선의 고도와의 비를 백분율로 계산하여 빈도를 살펴보면 산사태 발생지점이 능선의 90% 이상의 고도에서 산사태의 발생빈도가 53%로 가장 높고, 80-90%는 21%, 70-80% 16%의 순으로 산사태 발생빈도가 감소하고 있으며, 고도가 더욱 낮아져 산사태 발생지점이 60% 이하로 내려가면 산사태 발생빈도는 급격히 감소한다. 예를 들어 능선의 고도가 1000m일 경우 900m 이상의 고도(90% 이상)에서 산사태 발생빈도가 가장 높고 600m 이하의 고도(70% 이하)에서는 발생빈도가 급격히 저하하는 것으로 나타났다. 산사태 발생지점의 표면 굴곡도에 따른 산사태의 발생빈도는 대부분의 평행사면에서 74%, 약간 오목사면에서 26%가 발생하는 것으로 나타났다. 각 지구의 지질 및 토양별 산사태 발생빈도는 화성암계열의 지질 및 자갈/암괴 섞인 토사의 토양에서 발생하는 것으로 분석되었고, $34-40^{\circ}$ 사면경사에서 40%, $26-34^{\circ}$ 사면경사에서 26%, $26^{\circ}$ 이하의 사면경사에서 22%가 주로 발생하였으며, $40^{\circ}$ 이상의 높은 사면경사에서는 극히 미미하였다. 또한 임상 기준으로는 침엽수림에서 주로 발생하는 것으로 나타났다. 본 연구에서는 이상의 결과를 기초로 매우 안정, 안정, 부분적 안정, 불안정, 매우 불안정, 위험 지역으로 구분하고, 평가한 결과는 불안정 33개소, 매우 불안정 5개소 등 38개소 지점 모두에 사방댐 설치가 필요한 것으로 분석되었다.