• Journal of Korea Water Resources Association
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• v.37 no.8
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• pp.631-641
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• 2004

The objective of this study is to test the applicability of SLURP (Semi-distributed Land Use-based Runoff Process) on Soyanggang-dam watershed. SLURP model is a conceptual semi-distributed form model that can be used to examine irrigation plan and the effects of proposed changes in water management within a basin or to see what effects external factors such as climate change or changing land cover might have on various water users. Topographical parameters were derived from DEM using TOPAZ and SLURPAZ. Monthly NDVIs were calculated from multi-temporal NOAA/AVHRR images during four years (1998 ∼ 2001). Weather elements (dew-point temperature, solar radiation, maximum/minimum temperature and relative humidify) were obtained from five meteorological stations within and near the study area. To simulate daily hydrograph during 1998 ∼ 2001, the model parameters of each land cover class were optimized by sensitivity analysis and SCE-UA method. Test result of SLURP was summarized by various statistics method (WMO volume error, Nash-Sutcliffe efficiency, mean error and coefficient of variation).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6B
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• pp.373-378
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• 2012

In this study, a new empirical equation for the transverse dispersion coefficient has been developed based on the theoretical background in river bends. The nonlinear least-square method was applied to determine regression coefficients of the equation. The estimated dispersion coefficients derived by the new equation were compared with observed transverse dispersion coefficients acquired from natural rivers and coefficients calculated by the other existing empirical equations. From a comparison of the existing transverse dispersion equations and the new proposed equation, it appears that the behavior of the existing formula in a relative sense is very much dependent on the friction factor and the river geometry. However, the new proposed equation does not vary widely according to variation of friction factor. Also, it was revealed that the equation proposed in this study becomes an asymptotic curve as the curvature effect increases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.17-24
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• 2018

The HEC-HMS model was applied to identify the rainfall-runoff processes for the Anseongchun basin, where the lower part of the stream has been damaged severely by tropical storms in the past. Modeling processes include incorporating with the SCS-CN model for loss, Clark's UH model for transformation, exponential recession model for baseflow, and Muskingum model for channel routing. The parameters were calibrated through an optimization technique using a trial and error method. Sensitivity analysis after calibration was performed to understand the effects of parameters, such as the time of concentration, storage coefficient, and base flow related constants. Two storm water events were simulated by the model and compared with the corresponding observations. Good accuracy in predicting the runoff volume, peak flow, and the time to peak flow was achieved using the selected methods. The results of this study can be used as a useful tool for decision makers to determine a master plan for regional flood control management.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.135-135
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• 2018

한강의 잠수교는 평상시에는 사람과 차의 통행이 가능하나 예측수위가 5.5m일 경우, 보행자통제, 6.2m일 경우, 차량통제를 실시한다. 잠수교는 국토교통부의 홍수예보 지점은 아니지만 그 특수성으로 인해 정확한 홍수위 예측을 통해 선행시간을 확보할 필요가 있다. 일반적으로 하천 홍수위 예측을 위해서는 강우-유출 모형과 하도추적을 위한 수리모형을 결합한 모델링이 요구되나 잠수교는 하류부 조위로 인한 배수 및 상류부 팔당댐 방류량의 영향을 받아 물리적 수리 수문모형의 구축이 상당히 제약적이다. 이에 본 연구에서는 딥러닝 오픈 라이브러리인 Tensorflow 기반의 LSTM 심층신경망(Deep Neural Network) 모형을 구축하여 잠수교의 수위예측을 수행한다. LSTM 모형의 학습과 검증을 위해 2011년부터 2017년까지의 10분단위의 잠수교 수위자료, 팔당댐의 방류량과 월곶관측소의 조위자료를 수집한 후, 2011년부터 2016년까지의 자료는 신경망 학습, 2017년 자료를 이용하여 학습된 모형을 검증하였다. 민감도 분석을 통해 LSTM 모형의 최적 매개변수를 추정하고, 이를 기반으로 선행시간(lead time) 1시간, 3시간, 6시간, 9시간, 12시간, 24시간에 대한 잠수교 수위를 예측하였다. LSTM을 이용한 1~6시간 선행시간에 대한 수위예측의 경우, 모형평가 지수 NSE(Nash-Sutcliffe Efficiency)가 1시간(0.99), 3시간(0.97), 6시간(0.93)과 같이 정확도가 매우 우수한 것으로 분석되었으며, 9시간, 12시간, 24시간의 경우, 각각 0.85, 0.82, 0.74로 선행시간이 길어질수록 심층신경망의 예측능력이 저하되는 것으로 나타났다. 하천수위 또는 유량과 같은 수문시계열 분석이 목적일 경우, 종속변수에 영향을 미칠 수 있는 가용한 모든 독립변수를 데이터화하여 선행 정보를 장기적으로 기억하고, 이를 예측에 반영하는 LSTM 심층신경망 모형은 수리 수문모형 구축이 제약적인 경우, 홍수예보를 위한 활용이 가능할 것으로 판단된다.

• Journal of Korea Water Resources Association
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• v.39 no.2 s.163
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• pp.151-160
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• 2006

In this study, threshold runoff which is a hydrologic component of flash flood guidance(FFG) is estimated by using Manning's bankfull flow and Geomorphoclimatic Instantaneous Unit Hydrograph(GcIUH) methods on Han River watershed. Geographic Information System(GIS) and 3' Digital Elevation Model database have been used to prepare the basin parameters of a very fine drainage area($1.02\~56.41km^2$), stream length and stream slope for threshold runoff computation. Also, cross-sectional data of basin and stream channel are collected for a statistical analysis of regional regression relationships and then those are used to estimate the stream parameters. The estimated threshold runoff values are ranged from 2 mm/h to 14 mm/6hr on Han River headwater basin with the 1-hour duration values are$97\%$ up to 8mm and the 6-hour values are $98\%$ up to 14mm. The sensitivity analysis shows that threshold runoff is more variative to the stream channel cross-sectional factors such as a stream slope, top width and friction slope than the drainage area. In comparisons between the computed threshold runoffs on this study area and the three other regions in the United States, the computed results on Han River watershed are reasonable.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.4
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• pp.297-307
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• 2017

Skin properties are influenced by a variety of internal or external factors. This study was conducted to investigate and compare the skin characteristics in Asian women. We evaluated values of skin physical parameters, and then assessed the correlations among the parameters, and regional differences in 1,500 Asian subjects in seven countries (Malaysia, Indonesia, Vietnam, Thailand, India, China, and South Korea). The values of transepidermal water loss (TEWL), pH, skin hydration, sebum content, skin sensitivity, elasticity, crow's feet wrinkles, and skin brightness were measured. New Delhi's women were observed to have a lower level of hydration in stratum corneum, sebum content, stinging scores, and darker skin color than others. Furthermore, their skin surface pH on all sites is the highest among seven countries. Vietnamese had the lowest pH values in skin surface. Korean and Chinese had generally higher elasticity and fewer wrinkles. Both the skin hydration and TEWL had positive correlations with the stinging test, and there was a negative correlation between wrinkles and stinging test. These results represent that there was no clear trend related to the area or region. Skin physical parameters should be studied along with understanding of regional differences and various factors (skin care habits, lifestyle and personal sensitivity).

• Journal of Technology Innovation
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• v.25 no.4
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• pp.107-143
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• 2017

This study aims to understand the impact of internal and external environments and innovation efforts on a company's performance. First, the relationships and patterns between variables were determined through an exploratory factor analysis. Afterwards, a cluster analysis was conducted, in which the influential factors summarized in the factor analysis were classified. Finally, structural equation modeling was used to carry out an empirical analysis of the structural relationship between innovation efforts and the company's performance in the classified clusters. 7 factors were derived from the exploratory factor analysis of 40 input variables from external and internal environments. 4 clusters (n=1,022) were formed based on the 7 factors. Empirical analysis of the 4 clusters using structural equation modelling showed the following: Only independent technology development had a positive impact on the company's performance for Cluster 1, which is characterized by sensitivity to a technological/competitive environment and innovativeness. Only independent technology development and joint research had positive impacts on the company's performance for Cluster 2, which is characterized by sensitivity to a market environment and internal orientation. Joint research and the mediating variable of government support program utilization had positive impacts, while the introduction of technology had a negative impact on the company's performance for Cluster 3, which is characterized by sensitivity to a competitive environment, innovativeness, and willingness to cooperate with the government and related institutions. Independent technology development as well as the mediating variables of network utilization and government support program utilization had positive impacts on the company's performance for Cluster 4, which is characterized by openness and external cooperation.

• Asia Marketing Journal
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• v.11 no.3
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• pp.31-56
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• 2009

As the competition intensifies and the market matures, marketers are more and more concerned with the relationship marketing. Many of the previous researches have pointed out that not all of the consumers are relationship-oriented. But none of the previous research has systematically investigated this issue. This research investigated the relationship among the three concepts: consumers' intrinsic characteristics, perceived importance of relational benefits, and relationship building intention with the salesperson. In this research the perceived importance of relational benefits is treated as mediating variable in the relationship between consumers' intrinsic characteristics and relationship building intention with the salesperson. The conceptual model in this study can be depicted as follows. From the consumers' perspective relational benefits can be defined as "the additional benefits consumers can receive in addition to core services through the long-term relationship with the service provider." And in this study two kinds of relational benefits are adopted by reviewing the previous research: confidence benefits and social benefits. Relational benefit received from the salesperson is very important to predict consumers' relationship building intention with the salesperson. The more relational benefits consumer wants from the salesperson, the more relationship building intention he/she has. From this point two hypotheses are derived as follows. Hypothesis 1: As the perceived importance of confidence benefit from the salesperson increases, the relationship building intention with the salesperson increases. Hypothesis 2: As the perceived importance of social benefit from the salesperson increases, the relationship building intention with the salesperson increases. In this study four individual characteristics(risk taking tendency, variety-seeking tendency, product knowledge, trust orientation) are hypothesized to influence the perceived importance of confidence benefits from the salesperson. And three individual characteristics(interpersonal orientation, price consciousness, trust orientation) are hypothesized to influence the perceived importance of social benefits from the salesperson. These 7 hypotheses are as follows. Hypothesis 3: As the risk taking tendency increases, the perceived importance of confidence benefits from the salesperson decreases. Hypothesis 4: As the variety-seeking tendency increases, the perceived importance of confidence benefits from the salesperson decreases. Hypothesis 5: As the product knowledge increases, the perceived importance of confidence benefits from the salesperson decreases. Hypothesis 6: As the trust orientation increases, the perceived importance of confidence benefits from the salesperson increases. Hypothesis 7: As the interpersonal orientation increases, the perceived importance of social benefits from the salesperson increases. Hypothesis 8: As the price consciousness increases, the perceived importance of social benefits from the salesperson decreases. Hypothesis 9: As the trust orientation increases, the perceived importance of social benefits from the salesperson increases. The whole model in this study can be depicted as follows: Data were collected from the 396 consumers who actually trade stocks through the salesperson and were analyzed using structural equation model. The analysis results show that consumers' perceived importance of relational benefits(confidence benefit and social benefit) play the roles of mediating variables in the causal relationship between consumers' inherent characteristics and their relationship building intention with the salesperson. As for the individual characteristics, the influences of variety-seeking tendency, trust orientation, and price consciousness are statistically significant. It was found that variety-seeking tendency has a significant negative effect on the perceived importance of confidence benefit, and that trust orientation has a significant positive effect on the perceived importance of both of confidence and social benefit. Finally it was also found that, on the contrary to the influence direction suggested in the hypothesis, price consciousness has a significant positive effect on the perceived importance of social benefit.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.57-61
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• 2009

본 연구에서는 SWAT(Soil and Water Assessment Tool) 모형을 이용하여 미래 기후변화가 댐 유역의 하천수질에 미치는 영향을 분석하였다. 충주댐 상류유역($6,585.1km^2$)에 대해 민감도 분석을 통해 최적의 유출및 유사관련 매개변수를 선정하였으며, 충주호 유입하천 상류 2개 지점/영월1, 영월2)과 유역 출구점을 대상으로 일별 유출량 및 월별 수질자료를 바탕으로 모형의 보정(1998-2000)및 검증(2001-2003)을 실시하였다. 미래 기후자료는 IPCC(Intergovernmental Panel on Climate Change)에서 제공하는 SRES/Special Report on Emission Scenarios) A2, A1B, B1 기후변화시나리오의 MIROC3.2 hires와 ECHAM5-OM 모델의 결과 값을 이용하였다. 먼저 과거 30년 기후자료(1977-2006, baseline)를 바탕으로 각 모델별 20C3M(20th Century Climate Coupled Model)의 모의 결과 값을 이용하여 강수와 온도를 보정한 뒤 Change Factor(CF) Method로 Downscaling 하였으며, 미래 기후변화 시나리오는 2020s, 2050s, 2080s의 세 기간으로 나누어 각각 분석 하였다. 기후변화 시나리오 적용에 따른 SWAT 모의결과로부터 기후변화가 수문학적 거동 및 하천수질에 미치는 영향을 평가하였다.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.11
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• pp.1174-1179
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• 2008

Many modeling and calibration methods have been developed to analyze and design the biological wastewater treatment process. For the systematic use of activated sludge model (ASM) in a real treatment process, a most important step in this usage is a calibration which can find a key parameter set of ASM, which depends on the microorganism communities and the process conditions of the plants. In this paper, a standardized calibration protocol of the ASM model is developed. First, a weighted effluent quality index(WEQI) is suggested far a calibration protocol. Second, the most sensitive parameter set is determined by a sensitive analysis based on WEQI and then a parameter optimization method are used for a systematic calibration of key parameters. The proposed method is applied to a calibration problems of the single carbon removal process. The results of the sensitivity analysis and parameter estimation based on a WEQI shows a quite reasonable parameter set and precisely estimated parameters, which can improve the quality and the efficiency of the modeling and the prediction of ASM model. Moreover, it can be used for a calibration scheme of other biological processes, such as sequence batch reactor, anaerobic digestion process with a dedicated methodology.