• 대한가정학회지
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• 제43권9호
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• pp.109-127
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• 2005

The present study examined the relationships among maternal attachment, self-concept, peer relationship, and school adjustment. The subjects were 293 Korean-Chinese elementary school students living in Yanji and Shenyang, China. The Inventory of Parent and Peer Attachment (Armsden & Greenberg, 1987), Social Competence Inventory(Doh & Falbo, 1999), and Self-Perception Profile for Adolesents(Harter, 1988) were used to measure the subjects' maternal attachment, and peer relationship, school adjustment, and self-concept, respectively. When structural equation modeling was applied, the results supported not only the model that maternal attachment and self-concept exert an influence on peer relationship, but also the model that they exert an influence on school adjustment. The results of this study suggest that the secure maternal attachment of Korean-Chinese works as an important mechanism that explains their peer relationship and adjustment at elementary school.

• 한국경영과학회지
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• 제17권2호
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• pp.91-106
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• 1992

It an inventory control system, the demand over time are often assumed to be independently identically distributed (i. i. d.). However, the demands may well be correlated over time in many situations. The estimation of reorder points is not simple for correlated demands with variable lead time. In this paper, a general class of autoregressive and moving average processes is considered for modeling the demands of an inventory item. The first four moments of the lead-time demand (L) are derived and used to approximate the distribution of L. The reorder points at given service level are then estimated by the three approximation methods : normal approximation, Charlier series and Pearson system. Numerical investigation shows that the Pearson system and the Charlier series performs extremely well for various situations whereas the normal approximation show consistent underestimation and sensitive to the distribution of lead time. The same conclusion can be reached when the parameters are estimated from the sample based on the simulation study.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.378-384
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• 2002

In this paper, we propose a mixed integer optimization approach for solving the inventory problem with variable lead time, reorder point, crashing cost and price -quantity discount. Chang and Chang[15] study a continuous review inventory model in which lead time is a decision variable under price-quantity discount. However, their study cannot find the optimal solution due to the flaws in the modeling and the solution procedure. We present a complete procedure to find the optimal solution for the model. In addition to the above contribution, we also apply the minimax distribution free approach to the model to devise a practical procedure which can be used without specific information on demand distribution.

• 아동학회지
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• 제27권3호
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• pp.67-79
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• 2006

The present study examined predictors of children's problem solving using structural equation modeling(SEM). Participants were 410 dyads of 2nd- and 6th-grade children and their mother or father. Children and their parents responded to questionnaires. Instruments were the PSI(Parent Behavior Inventory, 1998), CES-D(Center for Epidemiological Scale-Depression, for children's depression, 1977) Sherer's(1982) self-efficacy scale, and the Problem Solving Inventory(Heppner & Petersen, 1982). In both grades, warmth in parenting behavior affected children's self-efficacy, which in turn contributed to their problem solving. Rejection in parenting behavior had positive effects on problem solving through increasing self-efficacy in 2nd graders only. Results implied importance of self-efficacy and developmentally appropriate parenting to improve children's problem solving.

• 유통과학연구
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• 제14권4호
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• pp.21-31
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• 2016

Purpose - This study examines how consignment and Vendor-Managed Inventory perform as supply chain collaboration programs. By using three key collaborative features, this study defines the collaboration programs and develops theoretical models of different supply chain systems. Research design, data and methodology - This study conducts sophisticated analysis on the supply chain systems by applying simulation modeling based on time-phased operations. The simulation model represents a two-stage supply chain system where a supplier sells a single item to a buyer, and it incorporates various operations. Results - In general, the simulation outcomes support that more advanced collaboration programs outperform less advanced ones. The analysis on the simulation outcomes identifies the significant value of information sharing in both collaboration programs. The specific conditions where the particular collaboration system outperforms the others are recognized. Conclusions - The outcome of this study supports that the supply chain system can improve its performance by having more collaborative features. This study provides business practitioners with guidelines to identify the circumstances that the specific collaboration program can fully exploit its advantages.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2003년도 추계학술대회 및 정기총회
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• pp.193-200
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• 2003

급변하는 시장환경에서 고객수요가 불확실한 상황에서 고객서비스를 최우선으로 하는 기업에서는 전략적인 제휴를 통해 기업의 경쟁력을 확보하는 것이 최우선이라고 하겠다. 이러한 환경에서 대두된 경영혁신 기법들이 공급체인관리와 아웃소싱 개념이라고 할 수 있는데, 이에 본 연구에서는 제조기업의 입장에서 제품가격 경쟁력을 확보하기 위한 일환으로 재고량을 줄이고, 판매량을 늘리는 방안을 제고하고자 한다. 비용과 서비스 관점에서 볼 때 이들은 서로 상충관계에 있지만, 본 연구에서 제안하는 재고 공유 시스템을 통한 공동 재고정책은 기업의 입장에서 볼 때, 보다 적은 재고를 보유함으로써, 재고유지비용을 절감하고, 이는 최종 제품가격의 하락으로 이어져 가격효과를 통한 매출량의 증대시킬 수 있게 된다. 이를 검증하기 위해 본 연구에서는 시스템 다이나믹스 방법을 이용하고, 이를 통하여 본 연구에서 제시된 재고 공유 시스템구축의 타당성을 검증하고, 분석하였다

• 한국입자에어로졸학회지
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• 제5권3호
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• pp.139-148
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• 2009

2003년 12월 '수도권 대기환경 개선에 관한 특별법'이 국회를 통과하면서, 서울을 포함한 수도권 대기에서 미세먼지와 이산화질소 농도를 저감하는 것을 주요 목표로 하는 '수도권 대기환경관리 기본계 획'이 수립되었다. 휘발성유기화합물도 저감대상물질이며, 여러 오염배출원에서 저감하기 위한 계획이 수립되어 추진중이다. 효과적인 저감 대책을 수립, 시행하기 위해서는 정확한 추이와 현황, 그리고 주요 기여원을 알아야만 한다. 여기에서는 휘발성유기화합물의 서울에서의 대기 농도, 주요배출원에서의 배출 조성 측정 결과를 바탕으로 수용모델의 하나인 CMB를 활용한 결과와 배출량 자료를 비교하여 주요배출원을 파악하고 휘발성유기화합물 저감 대책을 수립할 경우 고려하여야 할 문제들을 검토하였다. 배출량 자료는 유기용제 사용이 가장 중요한 배출원이라고 산정하였으나, 이와는 다르게 CMB 모델 결과는 자동차 배출가스가 서울 대기의 휘발성유기화합물의 가장 중요한 배출원임을 보였다. CMB 모델에 사용된 대기 측정자료와 주요 배출원의 조성비, 모델 운용 과정을 검토한 결과 모델 결과는 신뢰도가 높은 것으로 판단하였다. 따라서 우리나라의 휘발성유기화합물 배출량 자료의 검증, 보완이 필요하다. 이와 함께 휘발성유기화합물 배출을 저감하는 목표(미세먼지 저감, 위해성 저감, 오존 저감 등)에 따라 구체적인 대상 성분과 대상 배출원을 정확하게 파악하여 정책을 집행하여야 함을 논의하였다.

• 품질경영학회지
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• 제50권1호
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• pp.153-167
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• 2022

Purpose: The purpose of this study is to guide the operation managers who plan daily production of large mass-processing facility that services multi-customers with multi-product, small-batch item characteristics by providing the practical best production quantity and the inventory allowed to build. Methods: Close observation of a subcontract paint-shop operator captured the daily decision process which was reflected in the subcontractor-unique mathematical model and the system dynamics simulation model. Multiple simulations were run to find the practical best production quantity and the maximum allowable stock level of inventory that did not undermine the profit from practical best daily production. Actual data and a few constant values were obtained from the firm under study. Results: While the inventory holding cost for the customer-owned material harms the total profit of the subcontractor, the running cost of the processing facility hinders production in small batches. This balances the maximum possible productions and results in practical best daily production which can be found through simulation runs with actual data. The maximum level of stocked inventory is deduced from the practical best daily production. Conclusion: To build a large volume that enables economy-of-scale production, operators should deal with multi-product small-batch items from multiple customers. When the planned schedule of the time and amount of material in-flow tend not to be reliable, operators can find it practical to execute level production across the planning horizon instead of adjusting to day-to-day in-flow fluctuations.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.715-731
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• 2021

Uncertainties are calculated for pressurized water reactor (PWR) spent nuclear fuel (SNF) characteristics. The deterministic code STREAM is currently being used as an SNF analysis tool to obtain isotopic inventory, radioactivity, decay heat, neutron and gamma source strengths. The SNF analysis capability of STREAM was recently validated. However, the uncertainty analysis is yet to be conducted. To estimate the uncertainty due to nuclear data, STREAM is used to perturb nuclear cross section (XS) and resonance integral (RI) libraries produced by NJOY99. The perturbation of XS and RI involves the stochastic sampling of ENDF/B-VII.1 covariance data. To estimate the uncertainty due to modeling parameters (fuel design and irradiation history), surrogate models are built based on polynomial chaos expansion (PCE) and variance-based sensitivity indices (i.e., Sobol' indices) are employed to perform global sensitivity analysis (GSA). The calculation results indicate that uncertainty of SNF due to modeling parameters are also very important and as a result can contribute significantly to the difference of uncertainties due to nuclear data and modeling parameters. In addition, the surrogate model offers a computationally efficient approach with significantly reduced computation time, to accurately evaluate uncertainties of SNF integral characteristics.

• Nuclear Engineering and Technology
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• 제46권3호
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• pp.353-362
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• 2014

The effects of nuclear data uncertainties are studied on a typical PWR fuel assembly model in the framework of the OECD Nuclear Energy Agency UAM (Uncertainty Analysis in Modeling) expert working group. The "Fast Total Monte Carlo" method is applied on a model for the Monte Carlo transport and burnup code SERPENT. Uncertainties on $k_{\infty}$, reaction rates, two-group cross sections, inventory and local pin power density during burnup are obtained, due to transport cross sections for the actinides and fission products, fission yields and thermal scattering data.