• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2B
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• pp.193-205
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• 2009

Typhoons occurred in the tropical Pacific region, these might be affected the Korea moving toward north. The strong winds and the heavy rains by the typhoons caused a natural disaster in Korea. In the research, the heavy rainfall events based on typhoons were evaluated quantitative through various statistical techniques. First, probability precipitation and typhoon probability precipitation were compared using frequency analysis. Second, EST probability precipitation was calculated by Empirical Simulation Techniques (EST). Third, NL probability precipitation was estimated by coupled Nonparametric monte carlo simulation and Locally weighted polynomial regression. At the analysis results, the typhoons can be effected Gangneung and Mokpo stations more than other stations. Conversely, the typhoons can be effected Seoul and Inchen stations less than other stations. Also, EST and NL probability precipitation were estimated by the long-term simulation using observed data. Consequently, major hydrologic structures and regions where received the big typhoons impact should be review necessary. Also, EST and NL techniques can be used for climate change by the global warming. Because, these techniques used the relationship between the heavy rainfall events and the typhoons characteristics.

• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.175-182
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• 2000

Spatial interpolation of daily temperature forecasts and observations issued by public weather services is frequently required to make them applicable to agricultural activities and modeling tasks. In contrast to the long term averages like monthly normals, terrain effects are not considered in most spatial interpolations for short term temperatures. This may cause erroneous results in mountainous regions where the observation network hardly covers full features of the complicated terrain. We developed a spatial interpolation model for daily minimum temperature which combines inverse distance squared weighting and elevation difference correction. This model uses a time dependent function for 'mountain slope lapse rate', which can be derived from regression analyses of the station observations with respect to the geographical and topographical features of the surroundings including the station elevation. We applied this model to interpolation of daily minimum temperature over the mountainous Korean Peninsula using 63 standard weather station data. For the first step, a primitive temperature surface was interpolated by inverse distance squared weighting of the 63 point data. Next, a virtual elevation surface was reconstructed by spatially interpolating the 63 station elevation data and subtracted from the elevation surface of a digital elevation model with 1 km grid spacing to obtain the elevation difference at each grid cell. Final estimates of daily minimum temperature at all the grid cells were obtained by applying the calculated daily lapse rate to the elevation difference and adjusting the inverse distance weighted estimates. Independent, measured data sets from 267 automated weather station locations were used to calculate the estimation errors on 12 dates, randomly selected one for each month in 1999. Analysis of 3 terms of estimation errors (mean error, mean absolute error, and root mean squared error) indicates a substantial improvement over the inverse distance squared weighting.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.565-574
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• 2008

Fire-enhanced soil hydrophobicity often increases runoff and erosion in the mountain hillslope following severe wildfires. Estimation techniques for WEPP's parameters were studied in burnt mountain slopes. In burnt mountain slopes, the model over-predicted runoff in the small runoff and under-predicted runoff in the great runoff, and in the lower sediment runoff it had a tendency to over-predict soil loss. The effective hydraulic conductivity was most sensitive in the WEPP's runoff and its sediment runoff was mainly effected by the effective hydraulic conductivity, initial saturation, rill erodibility, and interrill erodibility. To improve the applicability of the WEPP, the adjustment coefficient of effective hydraulic conductivity was defined for runoff and the adjustment coefficient of rill erodibility and interrill erodibility was presented for sediment runoff. The adjustment coefficient of effective hydraulic conductivity in wildfire mountain slopes increased with maximum rainfall intensity of single storm and the vegetation height index. The adjustment coefficients of rill erodibility depended on soil components of size distribution curve and total rainfall depths in single storm. The adjustment coefficients of interrill erodibility decreased with increases of maximum rainfall intensity and vegetation height index. These results may be used in the application of WEPP model for wildfire mountain slopes.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.605-605
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• 2015

최근 지구온난화로 인해 전 세계적으로 기상이변이 발생하여 강우량과 집중호우 발생빈도가 증가하는 추세이다. 특히 동북아시아 지역은 인구밀도가 높아 강우량 및 집중호우 발생빈도 증가에 따른 도시홍수 발생확률이 높으며 홍수피해가 가중될 수 있다. 또한 도심지에 위치한 하천의 외수위 상승 및 배수시설 설계빈도 이상의 강우의 발생빈도가 증가하여, 기존 홍수방어대책으로는 제어하기 어려운 실정이다. "수자원장기종합계획(2011~2020), 2011, 국토해양부"에 따르면 기상청의 한반도 장기 미래 전망을 21세기말(2071년~2100년)에 대해 한국 평년 기온은 $4^{\circ}C$정도 상승하고, 강우량도 증가할 것으로 전망하고 있다. 따라서 도심지에 위치한 하천의 외수위 상승 및 배수실 설계빈도 이상의 강우가 빈번히 발생하여 기존 홍수방어대책으로는 제어하기 어려운 실정이다. 본 연구에서는 연구 대상지역인 서울, 북경, 도쿄 지역의 과거 도시홍수 사례의 비교분석을 통하여 집중호우 빈발, 기존 방재시설물의 기후변화 대응능력 부족, 저지대지역 지형적 영향, 무분별한 도시개발로 인한 도시지역 불투수면적의 증가, 고령화와 재해취약계층 등 여러 가지 도시홍수 재해 영향인자들을 제시하였다. 앞으로 도시홍수 발생의 근본 원인 파악 및 홍수관리 효과를 최대화 시킬 수 있는 대책 설립에 대한 연구가 필수적이다. 본 연구에서는 동북아시아 지역 도시홍수로 인한 인명 재산 피해를 최소화하기 위해 기존 한국, 중국, 일본 삼국의 주요 도시별 홍수에 대한 구조적 비구조적 방어대책을 종합하고 비교분석을 실시하였다. 향후, 국내외 도시홍수 저감대책 수립을 위한 참고자료로 활용될 수 있을 것으로 기대된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1171-1180
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• 2014

The NRCS-CN method is generally used to estimate effective rainfalls in a basin. However, since the curve number which plays a critical role in the NRCS-CN method was originally developed for US watersheds, it is limited to be directly applied to other basins outside the United States. Therefore various modifications have been suggested to revise the NRCS-CN for specific watershed condition. This study introduced the weighted average method and the slope-based CN to estimate effective rainfalls available for Korean watersheds and compared with the observed direct runoff. The overall results achieved from this study indicated that the adjusted slope-based CN considerably increases effective rainfalls in general and makes the duration of effective storm longer. Based on the statistical error analysis performed for various modifications of NRCS-CN, the weighted average method with the adjusted slope-based CN has highest precision with the observed direct runoff. In addition, after analyzing the relation between the initial loss estimated from rainfall-runoff observations and the potential maximum retention from GIS-based data, it turns out that the assumption of linear relationship between the initial loss and the potential maximum retention is not available for Korean watersheds.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.162-167
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• 2007

수질오염총량관리제에서 단위유역 할당부하량은 지자체의 개발용량과 밀접한 관계를 가지고 있기 때문에 상 하류 지역간의 첨예한 관심거리가 되고 있다. 총량관리제는 기준유량과 목표수질에 대한 기준배출부하량의 달성을 목적으로 하고 있기 때문에 합리적이고 과학적인 기준유량 및 목표수질의 설정이 무엇보다 중요하다. 또한 합리적인 수질모델링을 필요로 하는데, 유량배분은 모델링 과정에서 중요한 영향을 미치며, 지역의 기준배출부하량을 결정하는 결정적인 요소 중의 하나이다. 기존의 유량배분은 대부분 관측지점을 기준으로 한 단순한 면적비 유량배분기법(SAWA; simple area-based water-balance analysis)에 의존해왔다. 그러나 SAWA는 특정유역의 토지피복, 토양, 지형경사 및 강우분포 등의 수문학적 특성을 고려하지 못하는 한계점을 가지고 있다. 즉, 동일한 면적의 유역이라도 이러한 수문 특성인자에 따라 유출되는 유량이 달라지는 현상을 고려하지 못하고 있다. 이는 곧 지역의 기준배출부하량의 신뢰성에 영향을 미치기 때문에 지역간 분쟁의 소지가 될 수 있다. 본 연구는 기존의 유량배분 방법인 SAWA가 가지는 한계점을 극복하고자 강우분포 및 토지피복의 수문학적 특성을 이용한 유량배분기법(HIWA; hydro-infomatical water-balance analysis)의 개발을 목적으로 수행되었다. 강우분포와 토지피복이 하천유량에 미치는 영향을 분석하고 공간정보화 한 후 지형정보체계(GIS)의 수문분석 기법을 이용하여 유량을 배분하였다 ARC/INFO의 KRIGING 보간법을 이용하여 구축한 등강우분포도와 토지피복에 따른 유출특성을 분석하여 강우유출 해석을 위한 가중지형정보를 생성하였다. 연구는 2003년 10월-2004년 3월의 미호천수계 및 수질오염총량관리단위유역 말단지점의 실측자료를 이용하였으며, 연구결과 기존의 SAWA보다 본 연구에서 제안한 HIWA가 유량배분의 정확도를 높일 수 있음이 입증되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.59-59
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• 2020

온실가스 증가로 전구평균기온은 지속적으로 상승하고 있으며, 이러한 지구시스템 변화는 수자원의 시·공간적인 변동을 증대시킬 것으로 전망된다. 보다 적극적인 기후변화 대응을 위해 2015년 파리협정이 채택됨에 따라 전 세계에서는 온실가스 감축을 실천하고 있으며, 선진국에서는 산업화 이전 대비 1.5℃ 및 2.0℃ 전구기온상승에 따른 분야별 영향평가 및 적응방안을 마련하고 있다. 그러나 국내의 경우 아직까지 전구기온 상승에 따른 수자원 영향평가가 미흡한 실정이다. 본 연구에서는 AR5 기후변화 시나리오를 기반으로 1.5℃ 및 2.0℃ 전구기온 상승으로 인한 국내 수자원 변화 특성을 분석하였다. 이를 위해 몬순특성을 고려하여 적정 5 GCMs을 선정하였으며, 시간샘플링 기법을 활용하여 1.5℃ 및 2.0℃ 전구기온 상승시기를 추정하였다. 통계적상세화 기법을 적용하여 상세 기후변화 시나리오를 생산하고, 수문모형(VIC)에 적용하여 미래 수문변화를 전망하였다. 과거 대비 1.5℃, 2.0℃ 전구기온 상승에 따른 수문기상인자의 변화를 분석한 결과 연평균 강수량 및 유출량은 전구기온상승에 따라 증가하며, 계절별 변동성은 심화될 것으로 전망되었다. 유출량의 변화는 강수량 변화경향과 대체로 일치하였으나, 강수량 대비 전망결과의 불확실성이 크게 나타났다. 한편, 수문순환은 전 지역에서 가속화되는 것으로 확인되었으며, 모든 GCM의 전망결과에서 동일한 경향을 보였다. 수문기상인자(강수량, 증발산량, 유출량)의 강도별 발생빈도 및 총량은 저강도 구간에서 감소, 고강도 구간에서 증가하는 것으로 분석되었다. 이러한 특성은 강수량 및 유출량의 극대값 증가에 기여하여 수자원 관리의 어려움을 가중시킬 것으로 예상된다.

• Analytical Science and Technology
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• v.29 no.1
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• pp.19-28
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• 2016

The objective of this study was to determine the acidification of precipitation in the Jeju area. Precipitation samples were collected from the Jeju area from 2009-2014, and the major ionic species were analyzed. In the regression analysis, through a comparison of ion balance, electric conductivity, and acid fraction, the correlation coefficients showed a good linear relationship within the range of 0.927~0.983. The volume-weighted means of the pH and electric conductivity were 4.9 and 22.7 µS/cm, respectively. The ionic strength of precipitation was 0.27±0.38 mM, indicating about 35.9 % of total precipitation within the pure precipitation criteria. The volume-weighted mean concentrations (ìeq/L) of the ionic species in the precipitation were in the order of Na⁺ > Cl⁻ > nss-SO₄²⁻ > NO₃⁻ > NH₄⁺ > Mg²⁺ > H⁺ > nss-Ca²⁺ > PO₄³⁻ > K⁺ > HCOO⁻ > CH₃COO⁻ > NO₂⁻ > F⁻ > HCO₃⁻ > CH₃SO₃⁻ . The acidification contributions by sulfuric and nitric acids were 54.5 % and 36.5 %, respectively. Meanwhile the acidification contributions by formic and acetic acids were 4.8 % and 4.2 %, respectively. Thus, it was found that the acidification of the precipitation in the Jeju area was mainly due to the inorganic acids. The neutralization factors by NH₃ and CaCO₃ were also 33 % and 20 %, respectively.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.73-81
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• 2013

Ordinary least squares (OLS) regression is the primary statistical method in previous studies for vegetation distribution patterns in relation to landform. However, this global regression lacks the ability to uncover some local-specific relationships and spatial autocorrelation in model residuals. This study employed geographically weighted regression (GWR) to examine the spatially varying relationships between NDVI (Normalized Difference Vegetation Index) patterns and changing trends of landform (elevation, slope) and solar intensity (insolation and duration of sunshine) in Mt Geum-gang of North-Korea. Results denoted that GWR was more powerful than OLS in interpreting relationships between NDVI patterns and landform/solar intensity, since GWR was characterized by higher adjusted R2, and reduced spatial autocorrelations in model residuals. Unlike OLS regression, GWR allowed the coefficients of explanatory variables to differ by locality by giving relatively more weight to NDVI patterns which are affected by local landform and solar factors. The strength of the regression relationships in the GWR increased significantly, by showing regression coefficient of higher than 70% (0.744) in the southern ridge of the experimental area. It is anticipated that this research output will serve to increase the scientific and objective vegetation monitoring in relation to landform and solar intensity by overcoming serious constraints suffered from the past non-GWR-based approach.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.2
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• pp.136-142
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• 2020

The antimicrobial resistance rate in bacteria has increased over the last several decades. The transfer of antimicrobial resistant determinants on mobile genetic elements could cause the accelerated emergence and spread of multidrug resistant bacteria. This study investigated the aminoglycoside resistance determinants transferred by mobile genetic elements in a total of 33 aminoglycoside non-susceptible E. coli isolated from clinical specimens in Chungcheong province. 16S ribosomal RNA methyl-transferases (RMTases) and aminoglycoside-modifying enzyme (AME) genes were detected via PCR and DNA sequencing. The most common AME genes were aac(3')-II gene (54.5%), followed by aph(3')-Ia (18.2%) and aac(6')-Ib (15.2%). None of the evaluated RMTase genes were detected in the 33 isolates. Seventeen of the 18 isolates harboring aac(3')-II gene were resistant to gentamicin, and 16 of them were resistant to tobramycin. The 5 isolates harboring aac(6')-Ib gene were all resistant to tobramycin. In this study, we confirmed that one of the important mechanisms of aminoglycoside resistance in E. coli isolated from human is the acquisition of AME genes. Continuing investigations of antimicrobial resistant determinants in bacteria isolated from human may be required to prevent dissemination of antimicrobial resistant bacteria.