• Proceedings of the Korea Contents Association Conference
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• 2010.05a
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• pp.644-646
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• 2010

최근 비점오염원 제어를 위해 오염총량제(Total Maximum Daily Loads, TMDL)가 도입되었으며, 이것은 도시유역에서의 대표적 비점오염원인 합류식 하수관거 월류수(Combined Sewer Overflows, CSOs)의 발생에 대한 분석이 선행되어야 한다. CSOs를 산정하기 위한 방법으로는 두 가지가 있다. 첫째, 확률강우량 분석에 의한 유출량 모의 방법으로, 이것은 표준강우사상에 의한 연간 CSOs 산정에 국한되는 한계를 가지고 있다. 둘째, 관측 강우 자료를 이용한 장기유출모의(LOS) 방법으로, 이 방법은 장기간의 강우 자료를 이용할 경우 최근의 강우 변화 양상을 반영하기 어려우며, 반면 단기간의 강우 자료를 이용할 경우 결과에 대한 신뢰도를 보장할 수 없다. 본 연구에서는 연간 CSOs 발생량 및 오염부하량을 산정하기 위하여 강우발생모형과 Long-term Outflow Simulation 모형을 이용하였다. 본 연구를 통한 CSOs의 산정은 앞서 언급된 기존 방법들의 문제점을 해결하고자 개발되었으며, 향후 도시화에 따른 유출 변화 및 유역 물순환 변화에 대한 연구에 활용될 수 있다.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.2
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• pp.195-204
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• 2014

The transition from fossil to renewable energy is inevitable due to fossil depletion. So, Renewable energy is very important for energy security and economic growth although it's R&D is long-term and high risky project. We propose new valuation method which combined system dynamics and compound real option method for long-term and high risk projects such as renewable energy. This method can show dynamic valuation results for the complex causal interaction and be easy for Monte-Carlo simulation to estimate volatility. And it can reflect the value of flexible decision for uncertainty. We applied the empirical analysis for Korea's photovoltaic industry by using this method. As results by empirical analysis, photovoltaic's R&D has high valuation using this method compared by traditional valuation methods such as DCF.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.527-530
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• 2017

LTE-R(Long Term Evolution-Railway) based on LTE technology is expected to use core communication technology for high speed railway as one of standards for railway communications. In this paper, transmission performance of video traffic as an application is analyzed on LTE-R networks. Performance is evaluated with compter simulation based NS(Network Simulator)-2, open video traffic is used, RTP(Real Time Protocol) is used for transmission protocol. Results and methods of this paper can be used for research and developmemt of LTE-R networks.

• The Journal of the Korea Contents Association
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• v.10 no.1
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• pp.372-380
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• 2010

In this study, we consider a mid-and-long term technological forecasting method based on simulation technique. We, first, gather information about a point of appearance time of new technologies which will be developed in the future and influence relationship among those technologies by Delphi survey. And then we propose a simulation-based heuristic approach searching for the key technology among new technologies which will be developed to attain a normative objective using the Delphi data. We also provide the range of occurrence time for individual technology and define key technologies in this study in contrast that a expert's estimate to occurrence time is only one point in traditional Delphi survey. The information for key technologies which are detected by this procedure gives priorities of R&D planning and aids the R&D planner or project manager in resource allocation.

• Proceedings of the SAREK Conference
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• 2006.11a
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• pp.25-25
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• 2006

• Journal of Korea Water Resources Association
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• v.53 no.5
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• pp.357-367
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• 2020

It is usually not easy to simulate the hydrologic cycle or water quality for ungaged watersheds, especially for long-term simulation. In this paper we evaluated the applicability of GSSHA, a process-based distributed hydrologic model, for the long-term discharge and water quality simulation for the ungaged Peace dam watershed. From the comparative analysis of the simulated discharge and water quality series with measured ones, we concluded that with its overall fair performance on simulating hydrograph patterns of the peak discharges and base flows for major storms the GSSHA model showed some possibility to be used as a watershed model even with its overestimation of peak discharges for small storms and different trends of simulated water quality from measured ones for some periods.

• Horticultural Science & Technology
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• v.30 no.4
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• pp.400-408
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• 2012

Effects of initial controlled atmosphere (CA) treatment on quality maintenance of 'Fuji' apples were assessed and compared with 1-methylcyclopropene (1-MCP) treatment and continuous CA storage. Apples were harvested twice at different maturity, treated with 1 ${\mu}L{\cdot}L^{-1}$ 1-MCP and then stored for 8 months at $0^{\circ}C$ under 3 conditions: air, CA for the first month followed by air (initial CA), and continuous CA (full CA). CA storage was performed with 1.5 kPa $O_2$ and < 1.0 kPa ($N_2$ balance). Following long-term storage, export simulation, refrigerated shipment and local distribution, were performed by holding apples at $0^{\circ}C$ for 2 weeks and on the shelf at $20^{\circ}C$ for 7 days. Both the application of 1-MCP and CA storage reduced ethylene production and respiration rates. Initial CA storage was also effective on reducing the metabolism although the effects were not as noticeable as full CA. Full CA storage with or without 1-MCP treatment maintained titratable acidity, flesh firmness, and sensory quality at the acceptable to excellent level even after the export simulation following 8-month storage regardless of harvest maturity. In contrast, effects of initial CA storage were limited to the maintenance of firmness and texture in early-harvested apples. Overall results indicated that harvest maturity is the critical factor for export fruit quality after long-term storage when separate treatment of initial CA storage or 1-MCP treatment is applied as a postharvest program.

• Magazine of the Korean Society of Agricultural Engineers
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• v.29 no.2
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• pp.53-63
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• 1987

Due to their wide range of application, deterministic comprehensive hydrologic models using digital computers have been developed in all countries of the world and researches are being undertaken for their appropriate applications. The aim of this study has been to demonstrate the practical implementation of a physically based distributed hydrologic model, the USDAHL-74 model and to investigate its ability to simulate the long term estimate of water balance quantities in a Korean mountainous watershed. Application of the model to Dochuk watershed indicates the following results. 1.Since the USDAHL-74 model includes all the major components of the hydrologic cycle in agricultural watersheds, thus is comprehnsive, the model seems to have a wide range of application from the fact that simulation results obtained are not only runoff volumes m various time units but their spatial variation as well as even soil moisture within the watershed. 2.An approximate calibration to determine the parameter values in the model using various data obtained from D0chuk shed shows that the simulation error of yearly runoff volume is only 0.6 % and a correlation coefficient between observed daily runoff volume and simulated one is 0.91 in all calibrated period.3.As a verification test of the model, runoff volumes are simulated using 1986 year data without changing the parameter values determined by 1985 year data. The tests show that the USDAHL-74 model is a flexible tool and that realistic production to simulate the long term estimate of runoff in Korean mountainous watershed could be obtained using only a short period of calibration.4. Despite of the encouraging results, there still remain minor problems concerning the practical application of the model to improve the result of simulations. Some of these are the small descrepancies between observed and simulated daily runoff volume appeared in the vicinity of peaks and the recession of1 the daily hydrographs and the model performance for the frozen ground and melting process in the model. 5. Alough the use of parameter with physical significance and the ability to improve calibrations on the basis of physical reasoning represents advantages in the simulation for ungaged watersheds, further researches are needed to use the USDAHL-74 mode to simulate runoff in ungaged watersheds.

• Journal of the Korea Society for Simulation
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• v.12 no.1
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• pp.35-48
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• 2003

This paper suggests the long-term strategy of the production distribution planning considering the capacity of factory production and the uncertain demand in a supply chain. This paper determines the near optimal capacity of factory production by using the advantages of mathematical and simulation models. Also, the relationship between the capacity from the suggested model and the strategy of production and distribution in a supply chain is studied. Arena is used for modeling and analysis.

• Korean Management Science Review
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• v.28 no.3
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• pp.1-13
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• 2011

Hub-and-spoke transportation network is a powerful and useful network structure that takes full advantage of economies of scale on routes between hubs. In recent studies, the network structure is extended to hybrid hub-andspoke that allows direct transportation between spokes. In this study, we considered more extended network structure which is called hybrid multiple hub-and-spoke that has multiple hubs and allows direct transportation between spokes. We developed a mathematical optimization model for automotive service parts transportation planning under hybrid multiple hub-and-spoke network structure. The model suggests a long-term transportation route planning and a short-term vehicle assignment planning. The model is verified by simulation and validated in real world application to Hyundai Mobis automotive service parts transportation planning. From the simulation result, the model reduced the transportation cost about 24.7%, the total distance about 6.8% and the CO2 emissions about 8.8%. In real world application for 6 months from July to December 2010, the model reduced the transportation cost about 9.1% by changing the long-term transportation route without daily vehicle assignment planning.