• 한국수자원학회논문집
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• 제42권8호
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• pp.591-605
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• 2009

본 연구에서는 하천제방의 침식, 침투영향을 고려한 위험도 및 통합위험도를 산정하였다. 이를 위해 추계학적 강우변동 생성기법을 이용하여 생성된 태풍기와 장마기별 유량 및 수위수문곡선을 활용하여 하천제방에 대한 침식, 침투 그리고 통합 위험도를 산정하였다. 침식에 대한 하천제방의 위험도는 허용 소류력을 이용하여 평가하였고 침투류 해석은 각 제방별로 대표 제방단면을 선정 후 SEEP/W 모형을 통해 해석을 실시하였으며 한계동수경사법을 이용한 MFOSM 분석을 통해 제방의 침투붕괴 위험도를 산정하였다. 본 연구에서는 확정론적 분석방법과 달리 정량적인 위험도를 산정할 수 있었고 실제 강우 변동의 특성 및 다양한 제방파괴 요인을 반영하였으며, 이를 하나의 위험도로 통합하여 제시하고 있으므로 본 연구모형의 결과는 그 적용성에 있어 매우 유용할 것으로 판단된다. 본 연구모형은 향후 홍수에 대한 제방파괴 위험지점 파악 및 제내지 홍수위험도와 연계한 홍수보험, 주민대피지도 구축 등에 활용 될 수 있어 유역의 홍수통합관리시 효율적이고 체계적인 대책수립에 크게 기여할 것으로 판단된다.

• 대한토목학회논문집
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• 제34권4호
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• pp.1171-1180
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• 2014

유역의 유효우량을 산정할 경우 NRCS-CN 방법을 이용하는 것이 보통이다. NRCN-CN 방법에서 유역의 유출특성을 나타내는 중요한 인자인 유출곡선지수(CN)은 미국 유역을 대상으로 개발되어졌기 때문에, 미국 이외의 국가에서 적용될 경우 지역의 강우-유출 특성을 반영하지 못하는 한계점을 가지고 있다. 이에 많은 연구에서 유역의 CN값을 보정하는 방법을 제시하고 있다. 본 연구에서는 우리나라에 적절한 유효우량 산정방법을 제시하기 위하여 유역의 CN값을 가중평균하는 방법과 유역의 경사도를 고려하여 CN값을 보정하는 방법을 적용하여 유효우량을 산정하고 이를 관측 유효우량과 비교 분석을 수행하였다. 본 연구 결과, 경사도를 고려하여 CN값을 보정할 경우 유효우량이 전반적으로 크게 산정되었으며, 유효우량의 지속시간 또한 길어지는 것으로 나타났다. 유효우량의 산정방법에 따른 통계학적 오차 분석을 수행한 결과, 경사도로 보정한 CN값을 적용한 가중평균 유효우량 산정방법이 관측 직접유출량과 높은 정확성을 가지는 것으로 나타났다. 또한, 관측 자료를 이용하여 추정한 초기손실량과 GIS 자료를 이용하여 추정한 최대잠재보유수량과의 관계를 분석한 결과, NRCS-CN 방법에서 적용되고 있는 선형가정은 실제 강우-유출 관계와 큰 차이를 가지고 있는 것으로 나타났다.

• 상하수도학회지
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• 제34권3호
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• pp.211-220
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• 2020

When domestic sewage and rainwater runoff are discharged into a single sewer pipe, it is called a "combined sewer system." The sewage design standards in Korea specify the flow velocity based only on the volume of rainfall; therefore, sedimentation occurs on non-rainy days owing to the reduced flow rate and velocity. This sedimentation reduces the discharge capacity, causes unpleasant odors, and exacerbates the problem of combined sewer overflow concentration. To address this problem, the amount of sewage on non-rainy days, not just the volume of rainfall, should also be considered. There are various theories on sedimentation in sewer movement. This study introduces a self-cleansing velocity based on tractive force theory. By applying a self-cleansing velocity equivalent to the critical shear stress of a sand particle, sedimentation can be reduced on non-rainy days. The amount of sewage changes according to the water use pattern of citizens. The design hourly maximum wastewater flow was considered as a representative value, and the velocity of this flow should be more than the self-cleansing velocity. This design method requires a steeper gradient than existing design criteria. Therefore, the existing sewer pipelines need to be improved and repaired accordingly. In this study, five types of improvement and repair methods that can maximize the use of existing pipelines and minimize the depth of excavation are proposed. The key technologies utilized are trenchless sewer rehabilitation and complex cross-section pipes. Trenchless sewer rehabilitation is a popular sewage repair method. However, it is complex because the cross-section pipes do not have a universal design and require continuous research and development. In an old metropolis with a combined sewer system, it is difficult to carry out excavation work; hence, the methods presented in this study may be useful in the future.

• 한국환경복원기술학회지
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• 제18권6호
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• pp.73-83
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• 2015

The objective of this study is to establish implications for forest restoration planning in North Korea by analyzing spatio-temporal forest changes and detecting bio-physical factors driving forest degraded. We measured the relationship and spatial distribution between shifting cultivation and sparse forest. We also analyzed between degraded forest land and ecological variables by binary logistic regression to find biophysical drivers of forest degradation and deforestation in North Korea. Between the sparse forest and the shifting cultivation, a positive relationship is found (r=0.91) and scattered discontinuously throughout the country (Moran's I = -1, Z score = -13.46 (p=0.000)). The sparse forest showed a negative relationship with the warmest month(bio 9), the coldest month(bio10), and the minimum of soil water contents (swc_min), while the shifting cultivation had a negative relationship with the warmest month(bio 9) and the minimum of soil water contents(swc_min). However, the most critical drivers convert forests into sloping farmland were the three months rainfall in summer(bio8) and the yearly mean of soil water contents. Such results reflect the growth period of crops which overlaps with the rainy season in North Korea and the recent land reclamation of uplands where the soil water contents are maintained with a dense forest. When South Korea aids forest restoration projects in North Korea, in consideration of food shortage due to North Korea's cropland deficiency, terrace farmlands where soil water contents can be maintained should be excluded from the priority restoration area. In addition, an evaluation method for selecting a potential restoration area must be modified and applied based on multiple criteria including altitude and socio-economic factors in the respective regions.

• 대한토목학회논문집
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• 제34권1호
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• pp.145-153
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• 2014

현재 국내외적으로 다양한 가뭄지수들이 개발과 더불어 가뭄평가를 위한 다양한 기준이 개발되고 있다. 가뭄지수를 이용하여 가뭄의 시작, 강도 및 종료 시점을 정의할 경우, 일반적으로 특정 기준값(threshold)에 근거한 해석이 이루어지고 있으나, 이는 실제 가뭄을 평가하는데 불확실성을 가중시키는 원인으로 작용하고 있다. 따라서 본 연구에서는 기존의 가뭄지수 기반의 가뭄판단 시 적용되어져 왔던 특정한 기준값에 근거한 해석이 아닌, 기상학적 가뭄발생의 주된 원인 중 하나인 월강수량 자료에 내재되어 있는 특징을 최대한 활용하고자 은닉 마코프 모형(Hidden Markov Model, HMM) 기반의 확률론적 가뭄해석기법을 제안하였다. 그 결과, 본 연구에서 제시한 HMM 기반의 확률론적 가뭄해석기법은 기존의 다양한 가뭄지수를 적용한 가뭄해석과 비교하여 기상학적 측면에서의 가뭄판단의 명확한 기준 제시 및 가뭄발생의 원인을 규명하는 데 있어 체계적으로 불확실성을 감안한 해석이 가능하였다.

• 한국환경과학회지
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• 제19권8호
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• pp.971-981
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• 2010

The objectives of this study were to measure ambient total gaseous mercury (TGM) concentrations in Seoul, to analyze the characteristics of TGM concentration, and to identify of possible source areas for TGM using back-trajectory based hybrid receptor models like PSCF (Potential Source Contribution Function) and RTWC (Residence Time Weighted Concentration). Ambient TGM concentrations were measured at the roof of Graduate School of Public Health building in Seoul for a period of January to October 2004. Average TGM concentration was $3.43{\pm}1.17\;ng/m^3$. TGM had no notable pattern according to season and meteorological phenomena such as rainfall, Asian dust, relative humidity and so on. Hybrid receptor models incorporating backward trajectories including potential source contribution function (PSCF) and residence time weighted concentration (RTWC) were performed to identify source areas of TGM. Before hybrid receptor models were applied for TGM, we analysed sensitivities of starting height for HYSPLIT model and critical value for PSCF. According to result of sensitivity analysis, trajectories were calculated an arrival height of 1000 m was used at the receptor location and PSCF was applied using average concentration as criterion value for TGM. Using PSCF and RTWC, central and eastern Chinese industrial areas and the west coast of Korea were determined as important source areas. Statistical analysis between TGM and GEIA grided emission bolsters the evidence that these models could be effective tools to identify possible source area and source contribution.

• 대한공간정보학회지
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• 제20권2호
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• pp.109-117
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• 2012

최근 복합적 대형 재난이 빈번히 발생하면서 전지구적인 재해 재난 모니터링을 위해 인공위성 센서, 항공/지상 LiDAR 등 다양한 관측센서들이 활용되고 있다. 특히, 전지구를 주기적 반복적으로 관측하며 cm급 고해상도 공간 영상정보를 제공하는 상업 위성은 국가적 재해 재난 발생에 대한 전조 모니터링에서부터 신속한 복구 등 재해 재난업무에 그 활용범위가 확대되고 있다. 그러나, 기존의 독자적 위성운용 시스템만으로는 광역적이고 준실시간적 대응을 요하는 재해 재난 상황 대응에는 한계가 있으므로, 다중 센서가 탑재된 탑재체 운용, 여러 대의 탑재체를 연동하여 적시에 위성영상을 확보하기 위한 긴밀한 국제적 협력체계가 필요하다. 본 논문에서는 지난 2011년 발생했던 국내 폭설 및 집중호우 재난 대응을 위해 국립방재연구원과 국제재난기구인 International Charter와의 협업을 통하여 신속한 위성영상 수급과 자료처리, GIS 분석, 지도화(mapping)함으로써 적시적으로 의사결정지원이 가능한 재난관리 체계를 제시하였다.

• 한국도로학회논문집
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• 제19권5호
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• pp.21-31
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• 2017

PURPOSES : One of the main components of road projects funded by the Economic Development Cooperation Fund (EDCF) is the improvement or rehabilitation of existing pavements. The result is that pavement structures are critical to the success of a project. There is, however, no design standard available at present that reflects a region's specific features including climate conditions and quality of pavement materials. For this reason, a comparative study of the major EDCF borrowers' flexible pavement design standards was conducted. This study led to the proposal of a new method for applying flexible pavement designs which can be used for EDCF-funded projects in Asia. METHODS : The method has been produced by adjusting some input data of the "AASHTO Interim Guide for Design of Pavement Structures" in accordance with certain Asian countries' geometrical features, tropical and subtropical weather, and strength of pavement materials. The Philippine regional factors, having five different grades, have been selected after taking into consideration the amount of rainfall, strength of pavement materials, and characteristics of the Asia and Pacific regions. Structural layer coefficients have been prepared for two different regions according to the geometric difference between Southeast and Southwest Asia. The Philippine and Sri Lankan coefficients have been used for Southeast Asia and Southwest Asia, respectively. CONCLUSIONS : Owing to applying this new method, it was verified that the thickness of the pavement was underestimated by between 11 cm and 16 cm compared with the originally designed thickness. Having discovered that the use of the Korean and American-oriented factors and coefficients is not appropriate for other Asian countries, the new method is expected to enhance the quality of pavement in future projects.

• Asian-Australasian Journal of Animal Sciences
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• 제9권2호
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• pp.203-210
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• 1996

A 13-month study was conducted to determine the monthly variation of crude protein(CP), cell contents(CC), fiber fractions and mineral concentrations of paragrass [Brachiaria mutica (Forsk.) Stapf.] and stargrass (Cynodon plectostachyum Pilger) and to estimate the correlations among the nutrient fractions and climatic factors. The forage samples collected by hand plucking were found to contain CP and mineral concentrations. i.e. calcium(Ca), magnesium(Mg), potassium(K) and zinc(Zn) above the critical levels based on ruminant veeds. Monthly differences(p<0.05) were observed in all CP, CC, neutral detergent fiber(NDF), acid detergent fiber(ADF), hemicellulose(HE), cellulose(CE) and acid detergent lignin(ADL) between the two grass species. Monthly differences(p<0.05) were also observed in all concentrations of forage Ca, K, phosphorus(P), copper(Cu) and Zn except in Mg of both grasses and K of stargrass. Species differences(p<0.05) were observed in all nutrient fractions except Mg and K concentrations. Rainfall had positive correlations to CP, P(p<0.01) and CC(p<0.05); it had negative correlations to NDF(p<0.05). ADF, CE, Ca, Cu and Zn(p<0.01). Temperature, humidity and daylength had also some correlations to various nutrient fractions.

• 대기
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• 제18권4호
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• pp.299-316
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• 2008

The intensive upper-air observation network was organized over southwestern region of the Korean Peninsula during the Korea Enhanced Observing Program in 2005 (KEOP-2005). In order to examine the effect of additional upper-air observation on the numerical weather forecasting, three Observing System Experiments (OSEs) using Korea Local Analysis and Prediction System (KLAPS) and Weather Research and Forecasting (WRF) model with KEOP-2005 data are conducted. Cold start case with KEOP-2005 data presents a remarkable predictability difference with only conventional observation data in the downstream and along the Changma front area. The sensitivity of the predictability tends to decrease under the stable atmosphere. Our results indicates that the effect of intensive observation plays a role in the forecasting of the sensitive area in the numerical model, especially under the unstable atmospheric conditions. When the intensive upper-air observation data (KEOP-2005 data) are included in the OSEs, the predictability of precipitation is partially improved. Especially, when KEOP-2005 data are assimilated at 6-hour interval, the predictability on the heavy rainfall showing higher Critical Success Index (CSI) is highly improved. Therefore it is found that KEOP-2005 data play an important role in improving the position and intensity of the simulated precipitation system.