• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.257-258
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• 2019

이 연구는 기 개발한 간이 선박조종 시뮬레이터의 조종성능 개선에 관한 것이다. 선박조종 시뮬레이터에서 모델선박의 조종성 지수는 임의로 정하는 것이 아니라 가능한 모델대상선박의 실제 움직임과 동등하거나 유사하게 설정되어야 한다. 선행연구에서는 이미 발표된 대학교 실습선(한바다호)의 선박조종 실선데이터를 기반으로 모델선박의 조종성 지수를 도출하였으나, 타각이 10°를 초과할 경우 네 종류의 실선시험 결과와 평균 17.9%의 상대오차가 발생하였다. 이에, 타각 10°, 20° 및 35°에서의 한바다호 조종성 지수에 대해 에르미트 보간을 이용하여 3차 다항식을 산출하고, 이를 모델선박에 적용하였다. 그 결과 타각 35° 이내의 전 구간에서 조종성능의 상대오차가 평균 13.7%에서 11.6%로 약 2.1% 개선됨을 확인하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4D
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• pp.613-622
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• 2011

The aim of this study is to provide fundamental references for the establishment of environmental policies by using and evaluating EPI (Environmental Performance Index). Data of EPI for this study come from the 2010 World Economic Forum. By using these variables, we have comparison analysis of EPI of 163 countries. Next, the object of similarity analysis using MDS is the OECD countries and shown on PREMAP, drawing the position of each nation in environmental category and environmental policy index. The result of this study shows that there are differences in environmental policy index according to each nation's income and furthermore, similarity analysis makes it possible to locate environmental policy index of each nation in an awareness, which would help to set directions of policies concerning environment through the comparison with other advanced countries. But it could be more worth investigating time-series analysis for the change of environment-related variables because EPI has been just four times published since its first announcement in 2002. Despite, such limits would be overcome through continuous data collected over time.

• Journal of the Korean Geographical Society
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• v.41 no.1 s.112
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• pp.94-105
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• 2006

This paper aims to analyze changes of unusual temperature events on summer and winter and their controlling factors. There has been obviously an increased frequencies of summer unusual high temperature occurrence and decreased frequencies of winter unusual low temperature at most of stations. WMI, winter SHI and AOI might be essential for prediction of unusual temperature during winter and summer OHI and spring NPI for summer unusual low temperature. These factors are crucial because they reflect the recent global warming trend as well as have apparent associations with unusual temperature occurrence frequency in Korea.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1570-1574
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• 2009

2008년 여름 우리나라는 예년과 달리 홍수기에 북상하는 태풍이나 8월말에서 9월초까지 발생하던 장마전선의 영향을 받지 못했을 뿐만 아니라 홍수기 이후에도 중국에서 다가오는 동서고압대의 지속적인 영향으로 9월 중순 최고기온을 경신하면서, 강수가 없는 건조한 날씨가 계속되었다. 남부지방을 중심으로 8월말 이후 심화된 가뭄은 9월 중순에는 전국적으로 확산되었으며 도서지역의 부분적인 제한급수가 실시되거나 밭 작물 재배에 피해를 초래하기도 하였다. 본 연구에서는 위성영상 기반의 식생지수를 이용하여 2008년 가을가뭄의 시공간적 변화와 행정구역별, 권역별 가뭄 우심지역을 판별하였다. 또한, 가뭄정보를 제공하는 가뭄모니터링 시스템의 가뭄지수와 가뭄의 변화와 심도 등을 비교하였다. 위성영상자료는 MODIS NDVI를 이용하여 제작한 VCI와 SVI를 이용하였으며, 수자원공사의 '가뭄정보시스템'에서 제공하는 주 단위의 가뭄지수와 한국건설기술연구원 '통합수자원평가계획 시스템개발'에서 제공하는 월 단위의 가뭄지수를 활용하였다. 연구결과 행정구역상으로는 전라남 북도와 경상남도 지역이, 권역별로는 섬진 영산강 권역에서 극심한 가뭄이 발생한 것으로 판명되었으며 식생지수 기반의 가뭄발생지역 판별 결과와 기상학적 가뭄지수인 SPI와 PDSI의 가뭄분포가 유사하게 나타났다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.248-248
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• 2017

최근 가뭄 모니터링을 위해 과거에 비하여 고해상도의, 물리적으로 기반을 두는 정보가 요구되고 있다. 기존에 주로 활용하고 있는 통계적 방법론 기반의 가뭄지수들은 지니고 있는 한계에 대해 여러 개선과정을 거치고 있으나, 기상변수로부터 지표상의 식생 관련 변수로의 전파 과정에 대한 개별 통계적 가뭄지수 간의 관계 설명이 매우 어렵다. 이와 같은 관계로, 국내 유역에서의 물리적 기반을 둔 고해상도 가뭄 판단방법에 대한 시도가 필요한 시점이다. Brown et al. (2008)은 위성기반 식생정보, 기상학적 가뭄지수, 지형학적 조건을 고려한 식생가뭄반응지수(Vegetation Drought Response Index; 이하 VegDRI)를 개발하였다. 학습자료에 대해 CART 기반의 경험적 모델을 구축하여, 격자마다 근-실시간 자료를 적용한 VegDRI를 산출하여 고해상도의 지도를 산출하는 방식을 제시하였다. VegDRI는 NCDC의 U.S. Drought Monitoring에 활용되고 있으며, NOAA의 Drought Task Force Assessment Protocol에서는 가뭄 모니터링의 기준으로 설정되어 있다. 본 연구에서는 국내에 VegDRI를 적용하고자 필요한 자료수집 및 전처리 과정을 거쳐 결과를 도출하였다. 기상청 ASOS 기상관측소에서 얻은 기상변수, MODIS 위성으로부터 추출된 정규식생지수(Normalized Difference Vegetation Index; NDVI), 지형학적 정보와 기상학적 가뭄지수(SPI, PDSI)를 기계학습으로 모델링하여 VegDRI를 산출하였다. 산출된 VegDRI 공간분포도에 대하여 기존에 활용되던 유관기관의 가뭄 판단방법과의 유사성과 차이점을 비교 검토하여 적용성을 평가하였다.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.59-67
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• 2002

As a parameter for hydrodynamic modeling to define the range of seawater intrusion, dispersivities are frequently determined from pre-experiments or theoretical studies because field experiments need a lot of time and expenses. If the dispersivities are inadequate for an aquifer, the numerical results may have some errors. We examined the validity of longitudinal dispersivities by comparing the ranges of seawater intrusion with numerical modeling, field data and apparent resistivity sections. In the numerical modeling the TDS distributions simulated by the Xu's longitudinal dispersivity are more similar to the values of TDS measured at monitoring wet]s and boreholes than those by the Neuman's longitudinal dispersivity. The ranges of seawater intrusion by numerical simulations using Xu's longitudinal dispersivity show that the contour line of 1000 ㎎/L. as TDS is located at 480 m from the coast in May, while at 390 m in July. The difference is originated from the shift of the interface between seawater and fresh water. It moved toward the coast in July because of the seasonal increase of hydraulic gradient according to rainfall. A contour line of 15 ohm-m was used to define the range of seawater intrusion in apparent resistivity sections. From this criterion on the interface between seawater and fresh water, the range of seawater intrusion is located at 450 m from the coast. This result is similar to the range of seawater intrusion simulated by the numerical modeling using Xu's dispersivity. Therefore the range of seawater intrusion shows the difference due to the dispersivities used for the hydrodynamic modeling and the dispersivity generated by the Xu's equation is considered more effective to decide the range of seawater intrusion in this study area.

• Journal of Aquaculture
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• v.17 no.3
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• pp.197-208
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• 2004

Five commercially valuable Korean Veneroid, Protothaca jedoensis, Ruditapes philippinarum, Saxidomus purpuratus, Cyclina sinensis and Meretrix lusoria were recognized by comparing internal and external morphological characters. As length of the primary tooth was directly grown proportional to shell size but all other characters were not measured according to size of shell. Hence, the morphological characters of these Veneroids may be estimated from the size of the unique primary tooth and it might be enough to be a good criterion for identification of species among Veneriods. Numerical index of hinge plate length of these species was assessed systematically, irrespective of measuring the length, height and width of the shell. The highest internal and external morphological similarity was observed between P. jedoensis and R. philippinarum and the lowest similarity was observed between P. jedoensis and M. lusoria. These similarities may be affected by multiple environmental factors as well as genetic characters. For artificial seed production of P. jedoensis, R. philppinarum, a closest relative among the five species, must be focussed.

• Horticultural Science & Technology
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• v.19 no.2
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• pp.159-162
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• 2001

The genetic relationships of Korean native Orostachys species collected from various regions were analysed using random amplified polymorphic DNA (RAPD) method. Eighteen Orostachys species analysed with UPGMA were clustered into three groups A, B, and C. However, four species were not clustered into any group. O. iwarenge species in group A (No. 18-No. 22) showed low similarity with 66.3-73.9% according to the cluster analysis. O. malacophyllus species in group B (No. 12-No. 17) showed low similarity with 66.7-83.7% according to the cluster analysis. The similarity coefficient value of O. japonicus (No. 3-No. 8) except Anmyeondo collected variety (No. 9) showed higher level with 84.2-92.3% than O. iwarenge or O. malacophyllus. Therefore, O. japonicus is thought to be genetically stable, and have less regional variation.

• Korean Journal of Environment and Ecology
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• v.27 no.3
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• pp.327-343
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• 2013

The aim of this study is to perform community analysis and biological assessment of water quality using benthic macroinvertebrate from Wangpi-cheon watershed which is defined as conservation areas of ecosystem and landscape by ministry of environment in Korea. Field survey of the study area was carried out 2 times from June to September in 2012. As a result of the field survey, total 155 species of benthic macroinvertebrates in 74 families, 15 orders, 7 classes and 5 phyla were collected. The findings of community analysis using the classified species and individuals showed relatively low DI(Dominant Index) value of 0.22 and very high value of average H'(Diversity index) as 4.24. And the analyzed results of SI(Similarity Index) according to habitat types using functional feeding groups showed higher values of 94.51% and 93.19% respectively to tributary and main stream after the designation of conservation areas of ecosystem and landscape. These results infer that various species and lots of individual are widely distributed at Wangpi-cheon watershed and stream ecosystem of the study area is healthy and well maintained after the designation of conservation areas. And also, the calculated EPT value was 62.9% as high enough to explain the cleanness of Wangpi-cheon watershed. We evaluated environmental condition and biological water quality by using ESB(Ecological Score of Benthic macroinvertebrate community) and KSI(Korean Saprobic Index). The average evaluated ESB shows very high value of 208.2, therefore Wangpi-cheon watershed is designated as 'First priority protection waters' area and the value of KSI is 0.32 which meets the saprobic water quality standard as 'First class'.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.130-131
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• 2010

본 논문에서는 기존 링크 기반 유사도 계산 방안에 사용되는 두 가지 정규화 방안들을 설명하고, 두 정규화 방안 중에서 논문 데이터베이스에 적합한 정규화 방안을 선정한다. 또한, 실제 논문 데이터베이스에 두 가지 정규화 방안을 적용한 기존 링크 기반 유사도 계산 방안의 정확도를 측정함으로써 선정된 정규화 방안이 다른 정규화 방안보다 우수하다는 것을 규명한다.