• Journal of Korean Society for Geospatial Information Science
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• v.16 no.1
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• pp.23-32
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• 2008

According to recent frequent local flash flood due to climate change, the very short-term rainfall forecast using remotely sensed rainfall like radar is necessary to establish. This research is to evaluate the feasibility of GIS-based distributed model coupled with radar rainfall, which can express temporal and spatial distribution, for multipurpose dam operation during flood season. $Vflo^{TM}$ model was used as physically based distributed hydrologic model. The study area was Yongdam dam basin ($930\;km^2$) and the 3 storm events of local convective rainfall in August 2005, and the typhoon.Ewiniar.and.Bilis.collected from Jindo radar was adopted for runoff simulation. Distributed rainfall consistent with hydrologic model grid resolution was generated by using K-RainVieux, pre-processor program for radar rainfall. The local bias correction for original radar rainfall shows reasonable results of which the percent error from the gauge observation is less than 2% and the bias value is $0.886{\sim}0.908$. The parameters for the $Vflo^{TM}$ were estimated from basic GIS data such as DEM, land cover and soil map. As a result of the 3 events of multiple peak hydrographs, the bias of total accumulated runoff and peak flow is less than 20%, which can provide a reasonable base for building operational real-time short-term rainfall-runoff forecast system.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.575-580
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• 2020

In this study, we simulated an amine regeneration process with heat-stable salts removal unit. We derived the optimal operating conditions considering the flow rate of waste, the removal rate of heat-stable salts, and the loss rate of MDEA (methyl diethanolamine). In the amine regeneration process that absorbs and removes acid gas, heat-stable salt impairs the absorption efficiency of process equipment and amine solution. An ion exchange resin method is to remove heat-stable salts through neutralization by using a strong base solution such as NaOH. The acid gas removal process was established using the Radfrac model, and the equilibrium constant of the reaction was calculated using Gibbs free energy. The removed amine solution is separated and flows to the heat-stable salts remover which is modeled by using the Rstoic model with neutralization reaction. Actual operation data and simulation results were compared and verified, and also a case study was conducted by adjusting the inflow mass of removal unit followed by suggesting optimal conditions.

• Journal of Korean Society for Geospatial Information Science
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• v.3 no.2 s.6
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• pp.101-113
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• 1995

In pipeline planning, the systematic and reasonal management of topographical and spatial data are needed in order to omprove the availibilities for data analysis and the effective combinations of spatial informations. According to that fact, DBMS (Database Management System) and DSS(Decision making Support System) have to be developed for the planning of water supply system Also, the economic selection for harmonious delivery of water to target area, since the alternatives of pre-designed pipeline are influenced by hydraulic stability and geographic characteristics. In this study, GIS technique for water supply planning and management which stores graphic features and attributes as digital data sets is considered and engineering application programs are integrated for effective planning of water supply system. Decision making support system based on analyzing technical, Social and economical aspects is developed for the extension of water supply facilities and pipeline configurations. Especially, Hydraulic, land-use and economic influences are considered as important factors for the purpose of developing the system. Hydraulic analysis program(SAPID) for pipeline flow which is already developed in Water Resources Research Institute and economic analysis program(ECOVEL) are integrated with GIS for resonable decision making. Every possible aspects in pipeline planning for water supply is reviewed and the applicabilities of developed system into the field are evaluated.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.10b
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• pp.15-15
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• 1994

M MA ODS 합금의 보다 폭넓용 실용확훌 위해 크게 요구되고 있는 적정 접합기술 개발의 한 방안￡로, 마찰압접(Friction Welding) 방법의 가능성옳 조사하기 위하여 마찰압력과 시간, 마 찰 후 접촉압력(Upset Pressure) 풍을 다양하게 변화시켜 접합체톨 제조한 후, 접합체 강도에 대한 인장시험과 접합계연의 결합 및 미세구조에 대한 현미경 관찰, EDS에 의한 원소분석, 접 합이옴부의 경도분포와 파단면 분석 풍율 행하였다. 실험에 사용된 모재는 기계적 합금법으로 제조된 Inca사의 Ni기 MA 754 합금이었으며, 직경 l 10 mm, 길이 50 mm로 가공한 후, 아세통￡로 초음파 세척하여 접합에 사용하였다. 접합온 브 레이크식 마찰압접기틀 사용하여 행하였으며, 회전시험편의 회전수는 2400 rpm이었A며, 다른 한쪽의 고정시험편과의 마찰압력 및 마찰시간온 각각 50 - 500 MPa과 1-5초로, 또한 업셋압 력도 50 - 600 MPa로 변화시켰다. 이때 업셋압력은 모든 시편에 대해 일정하게 6초동안 가하 였다. 얻어진 접합체는 각 압접조건 당 2개 이상의 접합시험편에 대해 상온 인장강도톨 측정하 였으며, 파단이 일어난 위치를 확인한 후 파면에 대한 분석율 주사전자현미경(SEM)과 에너지 분산형 분광분석기mDS)릎 사용하여 행하였다. 컵합이옴부의 첩합성올 확인하기 위하여, 접합 체를 접합변에 수직으로 절단, 연마한 후 광학현미경과 SEM, EDS 퉁으로 관찰, 분석하여 접 합부의 형상과 결합형성 여부, 접합계면의 미세조직 퉁옳 조사하였다. 또한 마찰압접에 따론 모재와 접합계연부의 경도분포훌 접합이옴부로부터 모재쪽으로 일정 간격율 두어 마이크로 비 커스 경도기로 측정, 조사하였다. 이상의 설험 결과, 다옴과 같온 결론옳 얻었다. ( (1) 접합체 강도가 모채 강도의 95% 이상이 되는 양호한 렵합체흩 얻기 위한 마찰압력 조건 온, 2400 rpm의 회전속도와 6초의 업셋압력 유지시간에서 마찰압력과 업셋압력, 그리고 마찰시 간이 각각 400 MPa 이상과 500 MPa 이상,2초입율 확인하였다. ( (2) 컵합이옴부의 관찰 결과, 모든 마찰압접 조건에서 컵합이옴부는, 기폰 모재의 texture 조직 을 유지하고 있는 모재부 영역(영역 ill)과 첩합계면부에 인접하여 업셋압력이 주어질 때 단조 효과에 의해 계연 외부로 metal flow가 일어나면서 형성된 영역 II, 매우 미세한 결정립으로 구성된 중앙부의 영역 1 로 이투어져 있옴융 확인하였다. ( (3) 최적접합조건이 충족되지 않온 경우, 접합부의 영역 I 에서 관찰된 void와 균열, 불균일한 접합계면 통의 접합결함에 Al과 Y. Ti 퉁￡로 구성된 산화물률이 용집되어 있옴을 확인하였 다-( (4) 접합체의 파단 양상온 크게 접합부 파단과 모재부 파단, 이률의 혼합형 파단i로 나눌수 있었다. 모재부 파단의 경우, 파단면이 매끄럽고 파변상의 결정립도 매우 미세하였으며, 산확물 의 용집도 찾아보기 어려웠 나, 접합부 파단의 경우에는 파변의 굴곡이 비교척 심하고 연성 입계파괴의 형태를 보였￡며, 결정립도 모채부 파단의 경우에 비해 조대하였다. 조대하였다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.1
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• pp.7-17
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• 2014

Molten salt electrorefining process achieves uranium deposits at cathode using an electrochemical processing of spent nuclear fuel. In order to recover pure uranium from cathode deposit containing about 30wt% salt, the adhered salt should be removed by cathode process (CP). The CP has been regarded as one of the bottle-neck of the pyroprocess as the large amount of uranium is treated in this step and the operation parameters are crucial to determine the final purity of the product. Currently, related research activities are mainly based on experiments consequently it is hard to observe processing variables such as temperature, pressure and salt gas behavior during the operation of the cathode process. Hence, in this study operation procedure of cathode process is numerically described by using appropriate mathematical model. The key parameters of this research are the amount of evaporation at the distillation part, diffusion coefficient of gas phase salt in cathode processor and phase change rate at condensation part. Each of these conditions were composed by Hertz-Langmuir equation, Chapman-Enskog theory, and interphase mass flow application in ANSYS-CFX. And physical properties of salt were taken from the data base in HSC Chemistry. In this study, calculation results on the salt gas behavior and optimal operating condition are discussed. The numerical analysis results could be used to closely understand the physical phenomenon during CP and for further scale up to commercial level.

• Magazine of the Korean Society of Agricultural Engineers
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• v.29 no.4
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• pp.59-72
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• 1987

Although long-term runoff analysis is important as much as flood analysis in the design of water works, the technological level of the former is relatively lower than that of the latter. In this respect, the precise estimation model for the volume of successive runoff should he developed as soon as possible. Up to now, in Korea, Gajiyama's formula has been widely used in long-term runoff analysis, which has many problems in applying in real situation. On the other hand, in flood analysis, unit hydrograph method has been exclusively used. Therefore, this study aims at trying to apply unit hydrograph method in long-term runoff analysis for the betterment of its estimation. Four test catchment areas were selected ; Maesan area in Namlum river as a representative area of Han river system, Cheongju area in Musim river as one of Geum river system, Hwasun area in Hwasun river as one of Yongsan river system, and Supyung area in Geum river as one of Nakdong river system. In the analysis of unit hydrograph, seperation of effective rainfall was carried out firstly. Considering that effective rainfall and moisture condition of catchrnent area are inside and outside of a phenomenon respectively and the latter is not considered in the analysis, Initial base flow(qb)was selected as an index of moisture condition. At the same time, basic equation(Eq.7) was established, in which qb can take a role as a parameter in relating between cumulative rainfall(P) and cumulative loss of rainfall(Ld). Based on the above equation, computer program for estimation model of qbwas seperately developed according to the range of qb, Developed model was applied to measured hydrographs and hyetographs for total 10 years in 4 test areas and effective rainfall was estimated. Estimation precision of model was checked as shown in Tab- 6 and Fig.8. In the next stage, based on the estimated effective rainfall(R) and runoff(Qd), a runoff distribution ratio was calculated for each teat area using by computerised least square method and used in making unit hydrographs in each test area. Significance of induced hydrographs was tested by checking the relative errors between estimated and measured runoff volume(Tab-9, 10). According to the results, runoff estimation error by unit hydrograph itself was merely 2 or 3 %, but other 2 or 3 % of error proved to be transferred error in the seperation of effective rainfall. In this study, special attentioning point is that, in spite of different river systems and forest conditions of test areas, standardized unit hydrographs for them have very similar curve shape, which can be explained by having similar catchinent characteristics such as stream length, catchinent area, slope, and vegetation intensity. That fact should be treated as important factor ingeneralization of unit hydrograph method.

• Journal of the Korean Geophysical Society
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• v.3 no.2
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• pp.113-126
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• 2000

We have conducted multiple geophysical surveys to investigate the geoenvironmental change of the Nanjido Landfill due to the stabilization process. Geophyscial surveys are comprized of gravity, magnetic, dipole-dipole electrical and SP methods. Due to the field conditions, surveys were conducted on the top surface of the landfill no.2 and southern border areas in front of landfills. The gravity anomalies obtained on the top surface of the landfill no.2 in 1999 show that the gradient of the anomaly on the central area is decreasing in comparison with that observed four years ago. The complexity of magnetic anomaly pattern it also decreasing. These facts suggest that the stabilization work of the Nanjido landfill makes some progress by compaction process due to repetitive subsidence and refilling. The dipole-dipole electrical resistivity and SP data obtained on the outside of the waterproof wall at the landfill no.1 were severely affected by unsatisfactory surface conditions. On the other hand, the dipole-dipole electrical resistivity profiles obtained on the inside and outside parts of the waterproof wall at the landfill no.2 show the blocking effect of leachate flow by the waterproof wall. Few SP anomalies are observed on the top and side surfaces of the landfill no.2, but SP anomalies obtained on the base area inside the waterproof wall strongly reflect the effect of leachate collecting wells.

• Journal of the Korean Geotechnical Society
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• v.30 no.3
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• pp.59-72
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• 2014

For circular rigid footings with a rough base on sand, combined vertical - moment loading capacity was studied by three-dimensional numerical modelling. Mohr-Coulomb plasticity model with the associated flow-rule was used for the soil. After comparing the results of the swipe loading method, which can construct the interaction diagram with smaller number of analyses, and those of the probe loading method, which can simulate the load-paths in the conventional load tests, it was found that both loading methods give similar results. Conventional methods based on the effective width or area concept and the results by eccentricity factor ($e_{\gamma}$) were reviewed. The results by numerical modelling of this study were compared with those of previous studies. The combined loading capacity for vertical (V) - moment (M) loading was barely affected by the internal friction angle. It was found that the effective width concept expressed in the form of eccentricity factor can be applied to circular footings. The numerical results of this study were smaller than the previous experimental results and the differences between them increased with the eccentricity and moment load. Discussions are made on the reason of the disparities between the numerical and experimental results, and the areas for further researches are mentioned.

• Korean Journal of Construction Engineering and Management
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• v.7 no.5
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• pp.128-137
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• 2006

This paper is to develop curtain wall process life-cycle system in high-rise buildings in order to establish effective cooperation communication channels among the diverse constituents. This paper is to provide a base toward a curtain wall life-cycle management system to support decision making and the effective flow in light of information and materials. The four objectives of the research are 1) the analysis of the current curtain wall life-cycle process, 2) the analysis and development of the curtain wall design process As-Is model, and 3) the Muda analysis of the design process As-Is model and the suggestion of the improvements, 4) the development of curtain wall design To-Be model and comparative analysis of the improvement in terms of value streams. This research indicates the wastes decrease (or the values increase) from 6.7% up to 100% in different decision criteria through the improvement by the comparative analysis between the As-ls and To-Be curtain wall design process. This research suggests the potential improvement by VSM and a curtain wall life-cycle management system in curtain wall construction for diverse constituents be significant.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.5
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• pp.453-460
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• 2013

The surface roughness and heat transfer enhancement devices are known to increase the performance of a flat plate soar collector. This study includes the experiments on the effect of the several heat transfer enhancement devices inserted in duct to simulate the flat-plate solar collector. Experiment was basically at a constant heat flux on the upper duct wall. Inserted heat transfer enhancement devices are Chamfered rib $10^{\circ}$, Chamfered rib $20^{\circ}$, Rib & Groove and Rib & Dimple. Reynolds number is in the range of 2,300 to 22,000 which corresponds to turbulent regime. With the heat transfer enhancement devices, heat transfer would increase by the secondary flow and the increase of the heat transfer area. Pressure drop also increases with the insertion of the enhancement devices. Rib & Dimple model is the best in heat transfer enhancement, however, Chamfered rib $10^{\circ}$ model is the lowest in the pressure drop. Considering the heat transfer enhancement simultaneously with low pressure drop increase, performance factor was the best for the Chamfered rib $10^{\circ}$.