• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2006년도 학술대회 1부
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• pp.182-187
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• 2006

유비쿼터스 컴퓨팅이 차세대 IT 패러다임으로 자리매김하면서 유비쿼터스 서비스 개발이 경쟁적으로 이루어지고 있다. 그러나 이에 일반적으로 사용되는 시나리오 기반 개발 공정은 유비쿼터스 서비스 개발에 필요한 여러 요구사항들을 채워주기 힘들다. 따라서 본 논문에서는 유비쿼터스 서비스 개발을 위해 시나리오 기반 접근법을 바탕으로 시나리오를 계층적으로 분석하고 이로부터 기술적 요구 사항을 도출하는 방법론을 제시한다. 그리고 이 방법론을 유비쿼터스 패셔너블 컴퓨터(UFC) 프로젝트에 실제 적용하였다. 착용형 컴퓨터를 입은 사용자가 유비쿼터스 컴퓨팅 환경 하에서 받을 수 있는 다양한 서비스 프로토타입을 구현하였다. 그 결과 유비쿼터스 회의 시나리오 상에서 필요한 여러 서비스들을 효과적으로 개발할 수 있었다.

• 한국농공학회논문집
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• 제50권3호
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• pp.91-104
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• 2008

This study developed the WSM (weighted scenario method)-AHP method that can optimize the weighting value for multi-criteria to make GIS grid-based potential surface. The potential surface has been used to simulate urban expansion using distributed cellular automata model and to generate land-use planning as basic data. This study formulated the WSM-AHP method in mathematically and applied to test region, Suwon city, which located on south area from Seoul. WSM-AHP method generates potential map for each pair of weighting value for all criteria, which one criterion is weighted with high weighting value and the others use low weighting value, considering that the summation for all criteria weighting values should be "1". The potential change rate to the step of weighted scenario for weighting value of criteria is standardized like AHP intensity matrix in this study. From the standard potential change rate, WSM-AHP intensity matrix is completed, and then the optimal weighting value is calculated from the maximum eigenvector of the WSM-AHP matrix, according to the new WSM-AHP method developed in this study. The applied results of new method showed that the optimal weighting value from WSM-AHP is more resonable than the general AHP specialists' evaluation for weighting value. The another new finding of this study is to suggest the deterministic approach to optimize the weighting value for the distributed CA model, which is used to find new city area and to generate rational land-use planning.

• 한국농공학회논문집
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• 제53권6호
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• pp.31-41
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• 2011

This study was conducted to predict future land-cover changes under climate change scenarios and to cluster analysis of regional land-cover characteristics. To simulate the future land-cover according to climate change scenarios - A1B, A2, and B1 of the Special Report on Emissions Scenarios (SRES), Dyna-CLUE (Conversion of Land Use Change and its Effects) was applied for modeling of competition among land-use types in relation with socioeconomic and biophysical driving factors. Gyeonggi-do were selected as study areas. The simulation results from 2010 to 2040 suggested future land-cover changes under the scenario conditions. All scenarios resulted in a gradual decrease in paddy area, while upland area continuously increased. A1B scenario showed the highest increase in built-up area, but all scenarios showed only slight changes in forest area. As a result of cluster analysis with the land-cover component scores, 31 si/gun in Gyeonggi-do were classified into three clusters. This approach is expected to be useful for evaluating and simulating land-use changes in relation to development constraints and scenarios. The results could be used as fundamental basis for providing policy direction by considering regional land-cover characteristics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.4977-4996
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• 2016

The existence of excessively large and too filled network buffers, known as bufferbloat, has recently gained attention as a major performance problem for delay-sensitive applications. Researchers have made three types of suggestions to solve the bufferbloat problem. One is End to End (E2E) congestion control, second is deployment of Active Queue Management (AQM) techniques and third is the combination of above two. However, these solutions either seem impractical or could not obtain good bandwidth utilization. In this paper, we propose a Transmission Control Protocol（TCP）delayed window update mechanism which uses a congestion detection approach to predict the congestion level of networks. When detecting the network congestion is coming, a delayed window update control strategy is adopted to maintain good protocol performance. If the network is non-congested, the mechanism stops work and congestion window is updated based on the original protocol. The simulation experiments are conducted on both high bandwidth and long delay scenario and low bandwidth and short delay scenario. Experiment results show that TCP delayed window update mechanism can effectively improve the performance of the original protocol, decreasing packet losses and queuing delay while guaranteeing transmission efficiency of the whole network. In addition, it can perform good fairness and TCP friendliness.

• 시스템엔지니어링학술지
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• 제19권2호
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• pp.32-45
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• 2023

Implementing Severe Accident Management (SAM) strategies is crucial for enhancing a nuclear power plant's resilience and safety against severe accidents conditions represented in the analysis of Station Blackout (SBO) event. Among these critical approaches, the In-Vessel Retention (IVR) through External Reactor Vessel Cooling (IVR-ERVC) strategy plays a key role in preventing vessel failure. This work is designed to evaluate the efficacy of the IVR strategy for a high-power density reactor APR1400. The APR1400's plant is represented and simulated under steady-state and transient conditions for a station blackout (SBO) accident scenario using the computer code, ASYST. The APR1400's thermal-hydraulic response is analyzed to assess its performance as it progresses toward a severe accident scenario during an extended SBO. The effectiveness of emergency operating procedures (EOPs) and severe accident management guidelines (SAMGs) are systematically examined to assess their ability to mitigate the accident. A group of associated key phenomena selected based on Phenomenon Identification and Ranking Tables (PIRT) and uncertain parameters are identified accordingly and then propagated within DAKOTA Uncertainty Quantification (UQ) framework until a statistically representative sample is obtained and hence determine the uncertainty bands of key system parameters. The Systems Engineering methodology is applied to direct the progression of work, ensuring systematic and efficient execution.

• 한국인구학
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• 제31권1호
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• pp.27-54
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• 2008

본 논문은 최근 출산율 저하와 인구고령화로 인한 성장잠재력의 저하에 대한 우려가 높아지고 있는 상황에서 성장잠재력을 제고하는 정책의 성공 여부는 인적자본의 양적.질적 제고를 통한 생산성 향상에 달려 있음으로 파악하고, 인구구조의 변화, 노동시장 조건의 변화 및 노동생산성의 변화 등이 잠재성장률에 미치는 영향을 분석하는 것을 목적으로 하고 있다. 이를 위해 성장회계 접근방식을 이용하여 1인당 GDP 증가율을 인구구조의 변화에 따른 부양비의 변화와 노동투입 요소의 양적.질적 부분의 변화로 분해하였다. 우선, 노동투입의 양적인 변화는 고용률과 근로시간의 변화에 기초하여 시산하였으며, 노동투입의 질적인 변화는 인적자본에 대한 투자가 노동생산성에 미치는 영향을 감안하였다. 또한 출산율과 여성고용을 제고하는 정책효과를 분석하기 위해 출산율과 여성의 고용률을 주요 정책변수로 한 정책시뮬레이션을 하였다. 1인당 GDP 증가율의 베이스라인 전망결과는 2010년까지 연평균 4%대 중반의 성장률을 보이다가, 2020년대에는 3.94%, 2030년대에는 3.03%, 2040년대에는 2.41%로 서서히 감소할 것으로 나타났다. 또한 출산율 제고에 따른 성장률 효과는 2030년을 지나서 반영이 되며, 고출산율 시나리오 (2030년 이후 합계출산율이 1.57명으로 유지)의 경우 베이스라인보다 2030년대 이후 연평균 약 0.10%p 높은 1인당 GDP 성장률을 보일 것으로 전망되었다. 한편, 여성고용률이 제고되는 시나리오(2025년 이후 $25{\sim}54$세 여성의 고용률이 74.5%로 상승)의 경우 베이스라인보다 2050년까지 연평균 0.04%p 높은 1인당 GDP 성장률을 보일 것으로 전망되었다. 본 연구는 양적인 노동투입의 효과만으로는 성장잠재력에 미치는 영향이 그다지 크지 않으며, 궁극적으로 노동생산성의 향상과 같은 질적인 요소의 증대가 성장잠재력 확충에 중요한 대안이 됨을 알려 주고 있다.

• 한국농공학회논문집
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• 제55권2호
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• pp.9-20
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• 2013

Many studies have reported additional treatment is needed to use wastewater for agricultural purpose. Economic considerations should be taken into account to establish infrastructure for agricultural reuse because of a large amount of water use in irrigation and relatively low water quality requirement. The objective of this study was to conduct economic analysis of wastewater reclamation and reuse systems for agriculture. A system dynamics approach considering complexity and dynamics in the wastewater reuse systems was used for the economic analysis, which are related with social, environmental, and economic problems. Sensitivity and benefit cost analysis for wastewater reuse systems was conducted through the established economic assessment model. The result of sensitivity analysis showed that water resources development and installation cost were the most sensitive for total benefits and costs, respectively. The scenario-based test of the organized economic assessment model shows marginal cost ranges and enables decision-makers to decide reasonable cost for the wastewater reuse systems for agriculture.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.103-114
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• 2003

This paper aims to propose a method that helps maintenance engineers to evaluate the damage states of bridge structure systems by using a Fuzzy Fault Tree Analysis. It may be stated that Fuzzy Fault Tree Analysis may be very useful for the systematic and rational fuzzy reliability assessment for real bridge structure systems problems because the approach is able to effectively deal with all the related bridge structural element damages in terms of the linguistic variables that incorporate systematically experts experiences and subjective judgement. This paper considers these uncertainties by providing a fuzzy reliability-based framework and shows that the identification of the optimum maintenance scenario is a straightforward process. This is achieved by using a computer program for LIFETIME. This program can consider the effects of various types of actions on the fuzzy reliability index profile of a deteriorating structures. Only the effect of maintenance interventions is considered in this study. However. any environmental or mechanical action affecting the fuzzy reliability index profile can be considered in LIFETIME. Numerical examples of deteriorating bridges are presented to illustrate the capability of the proposed approach. Further development and implementation of this approach are recommended for future research.

• Journal of Platform Technology
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• 제9권1호
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• pp.3-14
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• 2021

Cognitive Radio network (CR) is a promising paradigm that helps the unlicensed user (Secondary User) to analyse the spectrum and coordinate the spectrum access to support the creation of common control channel (CCC). The cooperation of secondary users and broadcasting between them is done through transmitting messages in CCC. In case, if the control channels may get jammed and it may directly degrade the network's performance and under such scenario jammers will devastate the control channels. Hopping sequences may be one of the predominant approaches and it may be used to fight against this problem to confront jammer. The jamming attack can be alleviated using one of the game modelling approach and in this proposed scheme stochastic games has been analysed with more single users to provide the flexible control channels against intrusive attacks by mentioning the states of each player, strategies ,actions and players reward. The proposed work uses a modern player action and better strategic view on game theoretic modelling is stochastic game theory has been taken in to consideration and applied to prevent the jamming attack in CR network. The selection of decision is based on Q learning approach to mitigate the jamming nodes using the optimal MDP decision process

• 산경연구논집
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• 제11권3호
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• pp.39-50
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• 2020

Purpose: Agriculture, which is heavily influenced by climate conditions, is one of the industries most affected by climate change. In this respect, various studies on the impact of climate change on the agricultural market have been conducted. Since climate change is a long-term phenomenon for more than a decade, long-term projections of agricultural prices as well as climate variables are needed to properly analyze the impact of climate change on the agricultural market. However, these long-term price projections are often major constraints on studies of climate changes. The purpose of this study is to analyze the impacts of climate changes on the Korean onion market using ex-post analysis approach in order to avoid the difficulties of long-term price projections. Research design, data and methodology: This study develops an annual dynamic partial equilibrium model of Korean onion market. The behavioral equations of the model were estimated by OLS based on the annual data from 1988 to 2018. The modelling system is first simulated to have actual onion market conditions from 2014 to 2018 as a baseline and then compared it to the scenario assuming the climatic conditions under RCP8.5 over the same period. Scenario analyses were simulated by both comparative static and dynamic approach to evaluate the differences between the two approaches. Results: According to the empirical results, if the climate conditions under RCP8.5 were applied from 2014 to 2018, the yield of onion would increase by about 4%, and the price of onion would decrease from 3.7% to 17.4%. In addition, the average price fluctuation rate over the five years under RCP8.5 climate conditions is 56%, which is more volatile than 46% under actual climate conditions. Empirical results also show that the price decreases have been alleviated in dynamic model compared with comparative static model. Conclusions: Empirical results show that climate change is expected to increase onion yields and reduce onion prices. Therefore, the appropriate countermeasures against climate change in Korean onion market should be found in the stabilization of supply and demand for price stabilization rather than technical aspects such as the development of new varieties to increase productivity.