• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.493-498
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• 2008

Particles or deposit formed by corrosion of the pipe material bring about bad influences on the heating systems with inconvenience, energy loss and so on. In order to obtain the non-corrosive environments, the circulation hot water should properly be treated in several ways to satisfy one or more conditions of the followings: suitable pH-level, low hardness, low oxygen content, low conductivity, low level of chlorides and sulphur compounds and low level of solid particles. This experimental study was carried out to develope the new guidelines on the optimal water quality and directions for water quality management in heating systems. As results, it was recommended that the heating water be maintained pH-level not less than 8, hardness contents as $CaCO_3$ no more than 50 mg/L, turbidity no more than 10 NTU and T-Fe contents 1 mg/L below.

• 한국지리정보학회지
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• 제6권4호
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• pp.85-98
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• 2003

최근 물환경에 관련된 광범위한 문제들을 해결하기 위한 대안으로 유역관리의 관심이 증대되고있는 시점에서, 본 연구는 금호강 유역을 모니터링하기 위한 환경정보의 구축과 소유역 단위의 환경특성이 하천 수질에 미치는 영향을 분석하였다. 소유역 단위의 환경특성을 분석하기 위한 GIS 데이터베이스는 축척 1:25,000의 지형도, 정밀토양도, 토지이용도, 10m 해상도의 DEM, 도로망도, 수계망도, Landsat TM 영상에서 산출된 식생지수(NDVI), 강우량, 그리고 RUSLE 모형에 의한 토양유실량으로 구성되었다. 소유역 단위의 환경특성과 하천 수질간의 상호관련성을 분석한 결과에 따르면, 유역의 도시화 또는 산업화에 관련된 주거 상업지역, 공업지역, 도로지역에 관련된 변수들은 BOD, COD, SS, T-N, T-P의 수질자료와 음(-)의 상관성을 가지는 것으로 분석되었다. 이와는 달리, 자연환경상태와 관련된 산림피복과 식생상태 변수들은 수질자료와 양(+)의 상관성을 가지는 것으로 분석되었다. 그러나, 농업적 토지이용과 농약 및 비료사용량, 토양유실량은 수질자료와 유의한 상관성을 가지지 않는 것으로 나타났다.

• 한국농공학회논문집
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• 제58권6호
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• pp.1-8
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• 2016

Crop damages due to agricultural drought has been increased in recent years. In Korea, water resources are limited indicating that proper management plans against agricultural drought are required for better water-use efficiency in agriculture. In this study, irrigation intervals and amounts for various crops and soil physical properties (sandy and silt loams) were estimated using the IWMM model. Five different crops (soybean, radish, potato, barley and maize) at the Bangdong-ri site in Chuncheon were selected to test the IWMM model. IWMM assessed agricultural drought conditions using the soil moisture deficit index (SMDI), and irrigation intervals and amounts were determined based on the degree of agricultural drought (SMDI). Additionally, we tested the effects of surface irrigation and sprinkler irrigation methods and various irrigation intervals of 2, 3, 5 and 7 days. In our findings, the irrigation intervals of 5 and 7 days showed the minimum rrigation amounts than others. When we considered that the intervals of 3 or 5 days are usually preferred to fields, the interval of 5 days was determined in our study. The estimated irrigation amounts for different crops were shown as maize > radish > barley > soybean > potato, respectively. The irrigation amounts for maize and barley were highly affected by soil properties, but other crops have less differences. Also, small differences in irrigation amounts were shown between the surface and sprinkler irrigation methods. These might be due to the lack of consideration of water loss (e.g., evapotranspiration, infiltration, etc.) in IWMM indicating model structural uncertainties. Thus, possible water loss (e.g., evapotranspiration, infiltration) need to be considered in application to fields. Overall, IWMM performed well in determining the irrigation intervals and amounts based on the degree of agricultural drought conditions (SMDI). Thus, the IWMM model can be useful for efficient agricultural water resources management in regions at where available water resources are limited.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.215-219
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• 2005

A macro spreadsheet model, WEANES (Wet Pond Annual Efficiency Simulation Model), has been developed to predict the long-term or annual removal efficiencies of wet retention/detention basins. The model uses historical, site-specific, multi-year, rainfall data, usually available from a nearby National Oceanic and Atmospheric Administration (NOAA) climatological station to estimate basin efficiencies which are calculated based on annual mass loads. Other required input parameters are: 1) watershed parameters; drainage area, pervious curve number, directly connected impervious area, and ti me of concentration, 2) pond parameters; control and overflow elevations, pond side slopes, surface areas at control elevation and pond bottom; 3) outlet structure parameters; 4) pollutant event mean concentrations; and 5) pond loss rate which is defined as the net loss due to evaporation, infiltration and water reuse. The model offers default options for parameters such as pollutant event mean concentrations and pond loss rate. The model can serve as a design, planning, and permitting tool for consulting engineers, planners and government regulators.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.829-841
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• 2018

An experiment was conducted for the OECD/NEA ROSA-2 Project using the large-scale test facility (LSTF), which simulated a 17% hot leg intermediate-break loss-of-coolant accident in a pressurized water reactor (PWR). In the LSTF test, core uncovery started simultaneously with liquid level drop in crossover leg downflow-side before loop seal clearing, and water remaining occurred on the upper core plate in the upper plenum. Results of the uncertainty analysis with RELAP5/MOD3.3 code clarified the influences of the combination of multiple uncertain parameters on peak cladding temperature within the defined uncertain ranges. For studying the scaling problems to extrapolate thermal-hydraulic phenomena observed in scaled-down facilities, an experiment was performed for the OECD/NEA PKL-3 Project with the Primarkreislaufe Versuchsanlage (PKL), as a counterpart to a previous LSTF test. The LSTF test simulated a PWR 1% hot leg small-break loss-of-coolant accident with steam generator secondary-side depressurization as an accident management measure and nitrogen gas inflow. Some discrepancies appeared between the LSTF and PKL test results for the primary pressure, the core collapsed liquid level, and the cladding surface temperature probably due to effects of differences between the LSTF and the PKL in configuration, geometry, and volumetric size.

• Nuclear Engineering and Technology
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• 제48권5호
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• pp.1174-1183
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• 2016

Hydrogen release during severe accidents poses a serious threat to containment integrity. Mitigating procedures are necessary to prevent global or local explosions, especially in large steel shell containments. The management of hydrogen safety and prevention of over-pressurization could be implemented through a hydrogen reduction system and spray system. During the course of the hypothetical large break loss-of-coolant accident in a nuclear power plant, hydrogen is generated by a reaction between steam and the fuel-cladding inside the reactor pressure vessel and also core concrete interaction after ejection of melt into the cavity. The MELCOR 1.8.6 was used to assess core degradation and containment behavior during the large break loss-of-coolant accident without the actuation of the safety injection system except for accumulators in Beznau nuclear power plant. Also, hydrogen distribution in containment and performance of hydrogen reduction system were investigated.

• 디지털산업정보학회논문지
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• 제10권2호
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• pp.37-45
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• 2014

This paper is a study of the water sensor using a coaxial cavity resonator. This water sensor uses the resonant frequency variation of the coaxial cavity resonator when there is a water drop of the used coaxial cavity resonator. And we made resonant frequencies by controlling the input voltage of the oscillator which will be mainly resonated in the coaxial cavity resonator. First, we made the coaxial cavity resonator by simulating the resonator structure with the proposed size and we expect the resonant frequency from the simulation and then we decide the VCO from the result. Second, we made the water drop detecting sensor circuit and measured the water sensor. We decided the size of the resonator as inner conductor 5mm, outer conductor 14mm, the height of resonator 9.5mm, and the height of the glass 6mm from the simulated result. The simulated resonant frequencies are 3.09GHz and we made the VCO frequency ranges from 2.56GHz to 3.2GHz. The measured resonant frequency is 2.97GHz and the return loss is under -8. 4 dB at the center frequency. When the water is dropped on the glass of the resonator, the voltage has changed from 690mV to 145mV. It shows the proposed water sensor can detect the water by the resonant frequency variation of the resonator.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.299-299
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• 2017

Due to the climate changes in Korea, the numbers of both torrential rain events and drought periods have increased in frequency. Water management practice against water shortage and flooding is one of the key interesting for field crop cultivation, and groundwater often serves as an important and safe source of water to crops. Therefore, the objective of this study is to evaluate the effect of groundwater table levels on soil water content and soybean development under two different textured soils. The experiment was conducted using lysimeter located in Miryang, Korea. Two types of soils (sandy-loam and silty-loam) were used with three groundwater table levels (0.2, 0.4, 0.6m). Mean soil water content during the soybean growth period was significantly influenced by groundwater table levels. With the continuous groundwater level at 0.2m from the soil surface, soil water content was not statistically changed between vegetative and reproductive stage, but the 0.4 and 0.6m groundwater table level was significantly decreased. Lower chlorophyll content in soybean leaves was found in shallow water table treatment in earlier part of the growing season, but the chlorophyll contents were non-significant among water table treatments. Groundwater table level treatments were significantly influenced on plant available nitrogen content in surface soil. The highest N contents were observed in 0.6m groundwater table level. It is probably due to the nitrogen loss by denitrification as the result of high soil water content. The length and dry weight of primary root was influenced by groundwater level and thus the highest length and dry weight of root were observed in 0.6m water table level. This result showed that soybean root growth did not extend below the groundwater level and increased with the depth of groundwater table level. The results of this study show that the management of groundwater level can influence on soil characteristics, especially on soil water content, and it is an important practice of to reduce yield loss caused by the water stress during the crop growing season.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.85-85
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• 2020

South Korea experiences few large scale erosion and sedimentation problems, however, there are numerous local sedimentation problems. A reliable and consistent approach to modelling and management for sediment processes are desirable in the country. In this study, field measurements of sediment concentration from 34 alluvial river basins in South Korea were used with the Modified Einstein Procedure (MEP) to determine the total sediment load at the sampling locations. And then the Flow Duration-Sediment Rating Curve (FD-SRC) method was used to estimate the specific degradation for all gauging stations. The specific degradation of most rivers were found to be typically 50-300 tons/㎢·yr. A model tree data mining technique was applied to develop a model for the specific degradation based on various watershed characteristics of each watershed from GIS analysis. The meaningful parameters are: 1) elevation at the middle relative area of the hypsometric curve [m], 2) percentage of wetland and water [%], 3) percentage of urbanized area [%], and 4) Main stream length [km]. The Root Mean Square Error (RMSE) of existing models is in excess of 1,250 tons/㎢·yr and the RMSE of the proposed model with 6 additional validations decreased to 65 tons/㎢·yr. Erosion loss maps from the Revised Universal Soil Loss Equation (RUSLE), satellite images, and aerial photographs were used to delineate the geospatial features affecting erosion and sedimentation. The results of the geospatial analysis clearly shows that the high risk erosion area (hill slopes and construction sites at urbanized area) and sedimentation features (wetlands and agricultural reservoirs). The result of physiographical analysis also indicates that the watershed morphometric characteristic well explain the sediment transport. Sustainable management with the data mining methodologies and geospatial analysis could be helpful to solve various erosion and sedimentation problems under different conditions.

• 한국농공학회논문집
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• 제56권6호
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• pp.103-111
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• 2014

This study was to develop the flood analysis module (FAM) for implementation of a web-based real-time agricultural flood management system. The FAM was developed to apply for an individual watershed, including agricultural reservoir. This module calculates the flood inflow hydrograph to the reservoir using effective rainfall by NRCS-CN method and unit hydrograph calculated by Clark, SCS, and Nakayasu synthetic unit hydrograph methods, and then perform the reservoir routing by modified Puls method. It was programmed to consider the automatic reservoir operation method (AutoROM) based on flood control water level of reservoir. For a $15.7km^2$ Gyeryong watershed including $472{\times}10^4m^3$ agricultural reservoir, rainfall loss, rainfall excess, peak inflow, total inflow, maximum discharge, and maximum water level for each duration time were compared between the FAM and HEC-HMS (applied SCS and Clark unit hydrograph methods). The FAM results showed entirely consistent for all components with simulated results by HEC-HMS. It means that the applied methods to the FAM were implemented properly.