• The Journal of Asian Finance, Economics and Business
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• 제7권9호
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• pp.659-672
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• 2020

The outbreak of a recent strain of Coronavirus, known as 'COVID-19', has spread sharply from China across the globe, resulting in a dramatic recession in the global economy. This uncertainty has therefore negatively influenced the business perspective and the various formulated strategies that may not considered such [extreme] circumstances. Using baseline analysis and archival data, this paper reports some of the major implications of COVID-19 on global business and strategy and puts forward suggested research agenda as potential future directions for organizations. In order to survive and remain sustainable, this paper argues that businesses need to revisit their strategies during current COVID-19 crises from three perspectives, including supporting human resources financial commitment, forming cross-functional teams and connecting with their supply chains, as well as investing in corporate social responsibility and doubling down efforts with regard to partnerships. The study also represents a preliminary analysis to the implications of COVID-19 on the business and strategies across the globe and is considered the first such in the field of business, as to date all research papers on COVID-19 have been published in medical-related journals. Directions for future research are also proposed at the end of this study.

• 대한산업공학회지
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• 제31권2호
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• pp.106-119
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• 2005

Uncertainties inherent in customer demand patterns make it difficult for supply chains to achieve just-in-time inventory replenishment, resulting in loosing sales opportunity or keeping excessive chain wide inventories. In this paper, we propose two intelligent adaptive inventory control models for a supply chain consisting of one supplier and multiple retailers, with the assumption of information sharing. The inventory control parameters of the supplier and retailers are order placement time to an outside source and reorder points in terms of inventory position, respectively. Unlike most extant inventory control approaches, modeling the uncertainty of customer demand as a stationary statistical distribution is not necessary in these models. Instead, using a reinforcement learning technique, the control parameters are designed to adaptively change as customer demand patterns change. A simulation based experiment was performed to compare the performance of the inventory control models.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.540-544
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• 2009

Hydrologic pattern under climate change has been paid attention to as one of the most important issues in hydrologic science group. Rainfall and runoff is a key element in the Earth's hydrological cycle, and associated with many different aspects such as water supply, flood prevention and river restoration. In this regard, a main objective of this study is to evaluate design flood using simulation techniques which can consider a full spectrum of uncertainty. Here we utilize a weather state based stochastic multivariate model as conditional probability model for simulating the rainfall field. A major premise of this study is that large scale climatic patterns are a major driver of such persistent year to year changes in rainfall probabilities. Uncertainty analysis in estimating design flood is inevitably needed to examine reliability for the estimated results. With regard to this point, this study applies a Bayesian Markov Chain Monte Carlo scheme to the NWS-PC rainfall-runoff model that has been widely used, and a case study is performed in Soyang Dam watershed in Korea. A comprehensive discussion on design flood under climate change is provided.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1264-1267
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• 2005

Fuzzy logic control has been widely applied for handling the system which has uncertainty or high robust system. Since the dynamic behaviors of the systems contain complexity and uncertainty in its parameters, several fuzzy logic controllers have been implemented to control room temperature in the field of air conditioning system. In this paper, the fuzzy logic control has been developed to control both in door temperature and humidity in the air conditioning systems. The manipulating variables are speed of compressor, heater and supply air flow rate. The microcomputer was used to interface with in system. The experimental results show the superior of multivaiable fuzzy logic control to keep room temperature and humidity in air conditioning system for the best comfortable.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.73-79
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• 2003

The steam turbine efficiency is an important factor in power plant. Accurate evaluation of steam turbine performance is essential. However, it is not easy to evaluate the steam turbine performance due to its high temperature and high pressure circumstance. Therefore most steam turbine performance tests were conducted by air similarity test. This paper described a test program for air similarity test of steam turbine at Korea Aerospace Research Institute. A test facility has been designed and built to evaluate aerodynamic performance of turbines. The test facility consists of air supply system, single stage test section, power absorption system, instrumentation and auxiliary system. For evaluation of steam turbine performance, the test of single stage axial turbine air similarity performance was conducted and uncertainty analysis was performed.

• 한국군사과학기술학회지
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• 제13권5호
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• pp.748-758
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• 2010

Navy surface vessels require pier services such as emergency repair, oil supply, arm loading/unloading, craning, standby readiness, normal repair, gun arrangement, ammunition loading, and food loading during the period in port. The purpose of this study is to establish efficient berth allocation plan for navy surface vessels in home port under the limited resources of piers and equipments. This study suggests Mixed Integer Programming model for berth allocation problem, considering precedence relationships among services and the uncertainty of the arrival and departure for each vessel. For an effective analysis, the model is implemented by ILOG OPL(Optimization Programming Language) Studio 6.0 and ILOG CPLEX 11.1., which shows a reasonable result.

• 한국수자원학회논문집
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• 제50권7호
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• pp.475-488
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• 2017

정확히 가뭄을 모의하기 위해서는 수문기상학적 현상을 반영할 수 있는 가뭄지수가 필요하며, 국내에서 수문학적 가뭄을 모의하기 위해 MSWSI (Modified Surface Water Supply Index)를 활용한 여러 연구가 진행되었다. 본 연구에서는 MSWSI의 한계점을 분석하고 MSWSI의 불확실성을 정량화하였다. 우선 MSWSI 인자로서 활용가능한 수문기상인자의 선정에 따른 영향을 분석하였다. 기존 MSWSI에 적용한 하천유량, 지하수위, 강수, 댐유입량의 4개 입력인자별로 하나의 관측소자료만을 이용하였으나 본 연구에서는 중권역별 특성에 맞도록 댐저수위와 댐방류량도 포함하였으며, 여러 관측소의 자료를 취득하여 면적평균자료를 사용하였다. 2001년과 2006년 가뭄사례에 대해 MSWSI 모의검증 결과, 본 연구의 MSWSI가 실측수문기상자료의 경향을 더 잘 반영하여 가뭄을 모의하였으며, MSWSI 인자의 선정이 가뭄모의 정확성에 영향을 주는 것으로 나타났다. 다음으로 MSWSI 인자에 적용하는 확률분포의 선정에 따른 영향을 분석하였다. 강수자료는 Gumbel와 GEV 분포, 하천자료는 정규분포와 Gumbel 분포, 댐자료는 2-매개변수 대수정규분포와 Gumbel, 지하수는 3-매개변수 대수정규분포를 따르는 것으로 나타났다. 이에 따라 중권역별로 최대 36개의 MSWSI를 산정하였으며, 확률분포의 선정에 따라 MSWSI 범위가 매우 다르게 나타나 어떠한 확률분포을 적용하느냐에 따라 MSWSI 결과는 매우 달라질 수 있음을 확인하였다. 마지막으로 maximum entropy를 이용하여 MSWSI 입력인자의 선정과 입력인자별 확률분포 선정의 영향에 따른 불확실성을 정량화하였다. 분석결과, 입력인자의 수가 많이 적용될수록 불확실성은 증가하는 것으로 나타났으며, 홍수기에 MSWSI 입력인자별 확률분포 적용에 따라 MSWSI의 불확실성이 증가하는 것으로 나타났다.

• 품질경영학회지
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• 제36권4호
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• pp.93-101
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• 2008

The rare metals, used for semiconductors, PDP-LCS and other specialized metal areas necessarily, has been playing a key role for the Korean economic development. Rare metals are influenced by exogenous variables, such as production quantity, price and supplied areas. Nowadays the supply base of rare metals is threatened by the sudden increase in price. For the stable supply of rare metals, a rational demand outlook is needed. In this study, focusing on the domestic demand for chromium, the uncertainty and probability materializing from demand and price is analyzed, further, a demand forecast model, which takes into account various exogenous variables, is suggested, differing from the previously static model. Also, through the OOS(out-of-sampling) method, comparing to the preexistence ARIMA model, ARMAX model, multiple regression analysis model and ECM(Error Correction Mode) model, we will verify the superiority of suggested model in this study.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.575-584
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• 2016

Considering the randomness and uncertainty of wind power, a reliability model of WTGs is established based on the combination of the Weibull distribution and the Markov chain. To analyze the failure mode quickly, we use the switch-section partitioning method. After defining the first-level load zone node, we can obtain the supply power sets of the first-level load zone nodes with each WTG. Based on the supply sets, we propose the dynamic division strategy of island operation. By adopting the fault analysis method with the attributes defined in the switch-section, we evaluate the reliability of the distribution network with WTGs using a sequential Monte Carlo simulation method. Finally, using the IEEE RBTS Bus6 test system, we demonstrate the efficacy of the proposed model and method by comparing different schemes to access the WTGs.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.396-396
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• 2000

Multiperiod optimization is the key step to tackle the supply chain optimization problems. Taking supply and demand uncertainty or prediction into consideration during the process synthesis phase leads to the maximization of the profit for the long range time horizon. In this study, new algorithm based on the Genetic Algorithms is proposed for multiperiod optimization formulated in MINLP, GDP and hybrid MINLP/GDP. In this study, the focus is given especially on the design of the Genetic Algorithm suitable to handle disjunctive programming with the same level of MINLP handling capability. Hybridization with the Simulated Annealing is tried. and many heuristics are adopted for this purpose.