• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.237-237
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• 2018

자연재해로 인한 국민의 인적 물적 피해는 해마다 증가되고 있으며, 자연재해 피해 중 대다수가 홍수에 의한 피해를 보이고 있다. 홍수 피해를 줄이기 위한 재해저감 활동 중 비구조적 대책의 하나인 홍수예 경보시스템은 수리학적 모형을 활용하여 하천의 홍수위를 예측하고 범람 위험성과 제방 붕괴 가능성을 사전에 경보하는 시스템으로서 하천변 주민 대피와 홍수피해 대응 활동에 매우 중요한 역할을 담당하고 있다. 홍수예 경보시스템이 본연의 역할을 제대로 수행하기 위해서는 수리학적 모형이 지형적 특성을 잘 반영하고 있어야 하며, 높은 정확도로 홍수위를 예측하여야 한다. 이에 본 연구에서는 4대강 중 홍수위험도가 높고 최근 하상단면 측량으로 인하여 수리학적 모형의 개선이 필요한 영산강 수계에 대하여 주요 지류인 황룡강과 지석천의 하도자료를 고려한 수리학적 모형을 구축하였다. 2013년 7월과 2014년 7월 2개의 홍수사상을 이용하여 시행착오법을 통한 조도계수를 보정하였으며, 2012년 8월과 9월 홍수사상을 통하여 검증하였다. 향후 본 연구를 통하여 개선되어진 영산강 수계 수리학적 모형을 활용하여 정확하고 신속한 홍수 예 경보가 이루어지길 기대한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.60-60
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• 2020

기후변화 및 지구온난화로 인한 자연재해 규모가 점차 대형화, 다양화되고 있어 이로 인한 피해도 증대되고 있다. 특히, 다양한 시설과 인구밀도가 높은 도심 지역은 집중호우, 태풍, 홍수 등 자연재해에 취약하여 인적·물적 피해 위험성이 매우 높다. 방재 시설확보 및 개선을 통한 더 높은 안정성 및 기상예보를 통한 대응, 대책을 통한 피해 저감이 이루어지고 있다. 그러나 일반적으로 제공되는 단일 수치모형 기반의 결정론적 기상예측정보는 기상 상태, 선행시간, 모형 매개변수 등으로 인한 불확실성이 매우 크며 이에 대한 정보가 제공되지 않다. 이러한 문제점을 보완하기 위해 앙상블 수치모델 정보와 기상레이더 자료 기반의 단기 예측정보가 활용이 가능하다. 그러나, 앙상블 수치모델의 불확실성, 기상레이더 기반 예측정보의 짧은 예측 선행시간으로 인해 수문학적 모형에 입력자료로 활용은 어려운 실점이다. 본 연구에서는 지점 관측자료의 시간적 연속성, 기상레이더 자료의 공간적 연속성, 앙상블 예측정보의 선행시간 정보를 융합하여 기상예측정보에 대한 불확실성 개선 및 선행시간에 따른 정확도를 높일 방법을 제안하였다. 기상청에서 제공하는 앙상블 예측자료인 LENS 자료, 레이더 강수량, ASOS 관측자료 기반으로 분석이 수행되었으며 분석결과는 예측강수량을 활용하는 분야에 긍정적 영향을 미칠 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.192-192
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• 2021

산지 사면에서 발생한 토석류는 지형변화에 큰 영향을 미치는 대표적인 자연재해이다. 특히, 집중호우로 인해 발생하는 산사태의 경우 단시간에 많은 토사가 붕괴되며, 이는 매우 빠른 속도로 유동하는 토석류로 발전할 수 있다. 이러한 토석류가 도심지역에서 발생할 경우 많은 인명 및 재산피해를 야기하며, 이와 같은 피해를 저감하기 위해선 토석류의 유동과 피해규모를 예측할 수 있는 수치모형을 통한 연구가 필수적으로 이루어져야한다. 유동 및 퇴적지역의 피해규모를 크게 증가시킬 수 있는 침식-연행작용에 대한 연구는 최근에 활발히 이루어지고 있다. 수치모형으로 분석된 피해범위와 규모를 정밀하게 산정하기 위해선 침적과정에 대한 구현·해석이 필요하나 국내·외적으로 토석류 침적에 대한 연구는 미비한인 실정이다. 이에 본 연구는 침적을 고려하는 침식-연행작용 모형을 개발하여 토석류의 유동 및 퇴적과정을 자연현상에 가깝게 묘사하고자 하였다. 해당 모형은 2011년 우면산 일대에서 발생한 일련의 토석류를 대상으로 검증하고자하며, 연구지역의 지형 및 붕괴지점 자료는 토석류 발생 전·후 DEMs(Digital Elevation Models)을 이용하여 구축하였다. 현장에서 관측된 피해 범위, 총퇴적량, 특정 지점에서의 최대 피해 높이와 첨두속도 등은 실측자료로 활용하여 모형의 결과와 비교·분석하였으며 이를 통해 모형의 성능을 검증하고자 하였다.

• Journal of the Korean GEO-environmental Society
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• v.17 no.11
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• pp.35-43
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• 2016

In this study, by using a Effective Microorganisms Brewing Cycle, it confirmed the purification effect of pollutants that are adsorbed on the basins stench removal and retarding soil. On the basis of on-site application test, a soil decontamination system will be suggested. Using a Effective Microorganisms Brewing Cycle, the odor concentration is reduced 2.5 times than that of natural purification treatment method. It was measured and found that the quality of the pore water discharged from the soil is improved. In addition, it was found that a composite of copper and lead with the fermentation microorganisms adsorbed on soil particles from the surface of the stirred experiments lagoon mixed soil is reduced to 65% and 66%, respectively, The TPH organic component was confirmed that the reduction effect of 85%. Restoration of reservoir contaminated soils using the effective microorganism brewing cycle needs to be more developed and implemented as a long-term purification system. This study may be a good reference of developing more complete microorganism brewing system which will efficiently reduce the odor and soil contamination based on optimal stirring and mixing ratio of the compound solutions and contaminated soils in reservoir.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.957-964
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• 2010

The deactivated catalyzed diesel particulate filter-trap (DPF) was remanufactured by ultrasonic wave treatment with various prepared solutions, followed by active component re-impregnation, and the emission control performance and surface properties of remanufactured DPF were studied at various remanufacturing conditions. The proper ultrasonic wave cleaning time at various prepared solutions and optimal re-impregnation amounts of active component for the best emission control performance of DPF were investigated and its performance tests were also carried out with various temperatures for the conversions of CO, THC (total hydrocarbon) and PM (particulate matter) by catalytic reaction test unit using bypass gas from the diesel engine dynamo system. It was found that the emission control performance of DPF remanufactured with the high-temperature air washing, ultrasonic wave cleaning at acid/base solutions and active component re-impregnation method was recovered to 95% level of its activity compared to that of the fresh DPF, which was caused by removing the deactivating materials from the surface of the DPF, through the analyses of performance test and their surface characterization by Optical microscope, EDX, ICP, TGA, and porosimeter.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.582-594
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• 2018

In this study, the vertical and horizontal flow wetlands were combined in series to create conditions for flow in the exhalation and anaerobic state with the aim of monitoring the variability and reduction of dissolved organic matterin the bio-reactive artificial wetlands, and the performance assessment was conducted as acrylic reaction groups by designing artificial wetlands that filled the functionalresiduals. In case of artificial wetlands in vertical and horizontal planes, the concentration of dissolved oxygen (DO) in the reaction tank was measured as 2.7 mg/L in the vertical flow wetlands under exhalation, and N.D. in the horizontal flow artificial wetlands under anaerobic conditions. The test was carried out by changing the operation time to 140 min, 80 min, and 60 min. The test was conducted with the same natural operation time of 20 min depending on the operation time. All hours of operation were shown to be due to microbial activity. In 3D-EEM, it was found that the longer the driving time was taken, the more reduction the organic compounds in the areas of insoluble human resources, III and V. Further research on the mechanism analysis of future reduction effects is expected to be carried out, but the findings are expected to contribute to the development of technologies for reducing obfuscated substances using artificial wetlands in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.434-442
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• 2019

Low Impact Development(LID) techniques has been attracting attention as a countermeasure to solve frequent flood damage in urban areas. LID is a techniques for returning to the natural hydrological cycle system by infiltrating the runoff from the impervious surface into the soil. The Bio-retention, one of the LID element technology has outflow reduction effect by reserving and infiltrating storm water runoff from watersheds. Recently, a number of studies have been carried out as interest in the reduction of storm water runoff and non-point pollutants in Bio-retention has increased. However, quantitative analysis on the outflow reduction of Bio-retention applied to small watershed is insufficient. In this study, Bio-retention model was constructed in a small watershed using K-LIDM which is capable of hydrologic analysis. When the storage capacity was increased or dividing the Bio-retention and watershed, the outflow reduction effect was 20% according to the storage capacity increase and 5~15% in the distributed Bio-retention system. The results of this analysis will be used as the basic data of future Bio-retention research related to watershed characteristics, vegetation type and soil condition.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.4
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• pp.249-256
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• 2009

The amount of nutrients from the effluents of rice culture - free-range ducks (RCFD) paddy fields and the effects of natural wetlands located at downstream of RCFD on water quality and aquatic plants was evaluated. This was carried out in a 61.9 ha paddy fields in Ulsan, Gyeongnam, where downstream is a 5.9 ha natural wetland, 61% of which was covered with well-developed aquatic plants. The amounts of T-N and T-P in the effluent from paddy field with RCFD were 13.7 and $2.5kg\;ha^{-1}$, respectively, which is 1.2~2.5 times higher than those observed in conventional rice culture practice. The amount of runoff from the RCFD area, calculated using the revised TANK model, was $543mm\;ha^{-1}$ with 808 kg of T-N and 130 kg of T-P during rice cultivation period. The dominant aquatic plants in the wetland includes Phragmites communis, Zizania latifolia, Persicaria thunbergii. etc. The nutrient contents of the aquatic plants which amounted to 761 kg of T-N and 103 kg of T-P were almost equivalent to 94% and 79% of the T-N and T-P in RCFD and CRC effluent. Therefore, the use and maintenance of wetlands in RCFDs area could be a good solution to management the non-point pollution from duck feces in RCFD paddy fields.

• Membrane Journal
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• v.22 no.5
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• pp.332-341
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• 2012

We studied the effects of induction of natural convection instability flow (NCIF) according to the gravitational orientation (inclined angle) of the membrane cell on the reduction of membrane fouling in the constant-flow ultrafiltration (UF) of colloidal silica solutions. Five colloidal silica solutions with different silica size (average size = 7, 12, 22, 50 nm and 78 nm) were used as UF test solutions. The silica particles in colloidal solutions form cakes on the membrane surface thereby causing severe membrane fouling. The constant-flow UF performance according to the gravitational orientation of the membrane cell (from $0^{\circ}$ to $180^{\circ}$ inclined angle), was examined in an unstirred dead-end cell. We evaluate the effects of NCIF on the suppression of fouling formation by measuring the variation of transmembrane pressure (TMP) and the increase of critical flux by using the flux-stepping method. In the constant-flow dead-end UF for the smaller size (7, 12 nm and 22 nm) silica colloidal solutions, changing the gravitational orientation (inclined angle) of the membrane cell above the $30^{\circ}$ angle induces NCIF in the membrane module. This induced NCIF enhances back transport of the deposited silica solutes away from the membrane surface, therefore gives for the reduction of TMP. But in the constant-flow UF for the more larger size (50 nm and 78 nm) silica colloidal solutions, NCIF effects are not appearing. The critical flux is increased as increasing the module angle and decreasing the silica size. Those results show that the intesity of NCIF occurrence in membrane module is more higher as increasing the module angle and decreasing the silica size.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.1
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• pp.23-30
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• 2014

To improve efficiency of diesel engine which requests high output recently and is used all kinds of industrial areas, this thesis experimented dynamic characteristics and exhaust gas characteristics of diesel engine installed by supercharger of correspondent output 200HP and natural inhalation diesel engine through the dynamometer and exhaust gas analyzer in same condition. As the result of experiment with natural inhalation diesel engine and diesel engine installed by supercharger, there were a few differences of output, but dynamic characteristics at high speed showed increased output and efficiency of the engine installed by supercharger. On the contrary, in exhaust gas characteristics, the model installed by supercharger showed increased exhaust gas such as $NO_X$, $O_2$, etc, but added value of exhaust gas is low if considering $CO_2$ reduction and efficiency of dynamic characteristic's increase. Based on the results, diesel engine installed by supercharger is expected to show higher economic feasibility than natural inhalation diesel than natural inhalation engine from an angle of efficiency. Keywords: 200hp class Turbocharger, Exhaust Gas, Engine Performance, Marine Diesel Engine.