• 제목/요약/키워드: dynamic safety stocks

검색결과 9건 처리시간 0.026초

동적 안전재고를 고려한 롯트량 결정 기법에 관한 연구 (A Study on the Lot-Sizing Rules with the Dynamic Safety Stocks)

  • 손권익;최승국
    • 산업기술연구
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    • 제20권A호
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    • pp.219-228
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    • 2000
  • The determination of lot sizes in prevailing inventory problems has been made with constant safety stock over the planning horizon. But, it is more profitable to accommodate the safety stock to dynamically fluctuating demands. The objective of this paper is to study the method to determine the dynamic safety stock and lot sizing rules depending on the actual customer demands. The last period or highly fluctuating period during the consumption of a lot is the most critical one to stock-out. It means that such periods must be given more attentions. Some dynamic methods to control safety stock are proposed with viewpoints of the time, quantity, and time-quantity. Simulation results show that lot sizing methods with dynamic safety stock reduce about 10% of average total cost compared to those with constant safety stock.

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DP법을 이용한 (1,m)형 재고시스템의 보충 의사결정에 관하여 (A Study on the Decision Determination of Replenishment using Dynamic Approach in (1,m)Type Inventory System)

  • 이재원;이철영;조덕필
    • 한국항만학회지
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    • 제14권1호
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    • pp.37-45
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    • 2000
  • Centralized safety stock in a periodic replenishment system which consists of one central warehouse and m regional warehouse can reduce backorders allocating the centralized safety stocks to regional warehouse in a certain instant of each replenishment cycle. If the central warehouse can not monitoring inventories in the regional warehouse, then we have to predetermine the instant of allocation according to demand distribution and this instant must be same for all different replenishment cycle. However, transition of inventory level in each cycle need not to be same, and therefore different instant of the allocation may results reduced shortage compare to the predetermined instant of allocation. In this research, we construct a dynamic model based on the assumption of monitoring inventories in the regional warehouse everyday, and develop an algorithm minimize shortage in each replenishment cycle using dynamic programming approach.

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(1, m)형 재고시스템에 의한 안전재고의 집중과 최적분배계획에 관한 연구 (Minimize Shortages in Two-Phase Periodic Replensihment System Using Dynamic Approach)

  • 이재원;이철영;조덕필
    • 한국항해항만학회:학술대회논문집
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    • 한국항해항만학회 1999년도 추계학술대회논문집
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    • pp.83-90
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    • 1999
  • Centralized safety stock in a periodic replenishment system which consists of one central warehouse and m regional warehouse can reduce backorders allocation the centralized safety stocks to regional warehouse in a certain instant of each replenishment cycle. If the central warehouse can not monitoring inventories in the regional warehouse, then we have to predetermine the instant of allocation according to demand distribution and this instant must be same for all different replenishment cycle. However, transition of inventory level in each cycle need not to be same, and therefore different instant of the allocation may results reduced shortage compare to the predetermined instant of allocation. In this research, we construct a dynamic model based on the assumption of monitoring inventories inventories in the regional warehouse everyday, and develop an algorithm minimize shortage in each replenishment cycle using dynamic programming approach.

영업차량에서의 궤도비틀림 검측 방안 연구 (Track Irregularity Inspection Method for Commercial Vehicle)

  • 이찬우;최은영
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2003년도 춘계학술대회 논문집
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    • pp.768-773
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    • 2003
  • The inspection of track irregularity, which is the most important index for the evaluation of the dynamic safety of the rolling stock, is performed by setting up the testing train set. The self-diagnosis for the various rolling stocks and railways can be obtained if it is possible to take the simultaneous inspection of track irregularity for the commercial vehicle while it is running and to build up a dynamic safety evaluation system. It is expected to have some good effects, such as preventing accident with the low dynamic safety, cutting cost for the testing train set and evaluating the exact influence on the rolling stock and railway. In this study, innertial measuring method, which allows us to directly measure the track irregularity from the commercial vehicle, will be considered and some overseas cases will be explored as well.

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알루미늄 차체 하중 시험 방법에 관한 비교 평가 (Comparison and Evaluation of Load Test Methods for Aluminum Car Body)

  • 서승일;박춘수;신병천
    • 한국철도학회논문집
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    • 제7권1호
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    • pp.32-36
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    • 2004
  • Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Static load test has been performed up to date to assess structural safety of the carbody. However, static load test is not sufficient to evaluate fatigue strength of the carbody, because fatigue failure is caused by dynamic load. In this study, the established load test methods for carbody are described and the characteristics of the methods are discussed. Also, a testing method to simulate dynamic loading condition is proposed for evaluation of fatigue strength of the carbody. The results by the proposed testing method are compared with the results by the static load test and new findings are discussed.

알루미늄 차체 하중 시험 방법에 관한 비교 평가 (Comparison and Evaluation of Load test Methods for Aluminum Car Body)

  • 서승일;박춘수;신병천
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2003년도 추계학술대회 논문집(I)
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    • pp.187-191
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    • 2003
  • Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Static load test has been performed up to date to assess structural safety of the carbody. However, static load test is not sufficient to evaluate fatigue strength of the carbody, because fatigue failure is caused by dynamic load. In this study, the established load test methods for carbody are described and the characteristics of the methods are discussed. Also, a testing method to simulate dynamic loading condition is proposed for evaluation of fatigue strength of the carbody The results by the proposed testing method are compared with the results by the static load test and new findings are discussed.

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철도차량의 충돌 시뮬레이션을 위한 유압 완충기의 특성 맵 (Characteristic Map of Hydraulic Buffer for Collision Simulation of Rolling Stock)

  • 김진성;최정흠;박영일
    • 한국안전학회지
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    • 제31권1호
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    • pp.41-47
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    • 2016
  • The rolling stock is composed of several cars. In order to operate in combination, it is necessary to connect the device, called coupler, between the rolling stocks. When the collision occurs between cars, couplers should be able to absorb the shock. Urban railway has used only rubber absorbers. But recently, the hydraulic buffer has been considered in general railway. In order to know the performance of the buffer it should be conducted to experiments. But whenever this combination change, we should experiments to know a lot of the dynamic behavior of each coupler. These experiments are generally replaced by the simulation, since a lot of time and cost consuming. The quasi-static map of hydraulic buffer obtained by the experiments is required for the simulation. However, the experiments for obtaining such a quasi-static map is costly and time consuming. In this paper, it proposes a method for deriving the quasi-static map of hydraulic buffer from the theoretical model.

국내 지진재해도를 고려한 저층 필로티 건물의 붕괴 확률 (Collapse Probability of a Low-rise Piloti-type Building Considering Domestic Seismic Hazard)

  • 김대환;김태완;추유림
    • 한국지진공학회논문집
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    • 제20권7_spc호
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    • pp.485-494
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    • 2016
  • The risk-based assessment, also called time-based assessment of structure is usually performed to provide seismic risk evaluation of a target structure for its entire life-cycle, e.g. 50 years. The prediction of collapse probability is the estimator in the risk-based assessment. While the risk-based assessment is the key in the performance-based earthquake engineering, its application is very limited because this evaluation method is very expensive in terms of simulation and computational efforts. So the evaluation database for many archetype structures usually serve as representative of the specific system. However, there is no such an assessment performed for building stocks in Korea. Consequently, the performance objective of current building code, KBC is not clear at least in a quantitative way. This shortcoming gives an unresolved issue to insurance industry, socio-economic impact, seismic safety policy in national and local governments. In this study, we evaluate the comprehensive seismic performance of an low-rise residential buildings with discontinuous structural walls, so called piloti-type structure which is commonly found in low-rise domestic building stocks. The collapse probability is obtained using the risk integral of a conditioned collapse capacity function and regression of current hazard curve. Based on this approach it is expected to provide a robust tool to seismic safety policy as well as seismic risk analysis such as Probable Maximum Loss (PML) commonly used in the insurance industry.

산업의 주식시장 선행성에 관한 실증분석 - 자산간 수익률 예측 가능성 - (A Study on Industries's Leading at the Stock Market in Korea - Gradual Diffusion of Information and Cross-Asset Return Predictability-)

  • 김종권
    • 대한안전경영과학회:학술대회논문집
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    • 대한안전경영과학회 2004년도 추계학술대회
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    • pp.355-380
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    • 2004
  • 이 논문은 과거의 산업 포트폴리오 수익률이 어떻게 확률추세(stochastic trend)로부터 전체 주식시장과 두 가지 거시경제 변수(경기동행지수와 산업생산)들을 예측할 수 있는 지를 알아보는 데에 초점을 두고 있다. 먼저, 산업들의 포트폴리오 수익률과 전체 주식시장 수익률이 VAR모형을 토대로 볼 경우 Granger 인과관계를 갖고 있는지를 살펴보았다. 이 분석의 결과에서 건설, 금속, 무역, 반도체, 보험, 비금속광물, 서비스, 섬유, 식료, 운수/창고, 유통, 의류, 자동차부풀, 전기전자, 정유, 조선, 종이/목재, 증권, 컴퓨터, 통신, 화학 등 21개 업종은 각 산업별 포트폴리오 수익률이 전체 주식시장 수익률을 $5\%$ 수준에서 통계적으로 유의한 영향을 주고 있음을 알 수 있었다. 이들 21개의 산업별 포트폴리오 수익률은 경제적으로도 중요한 의미를 지니고 있다. 즉, 당월(t)의 비금속광물과 정유, 금속 포트폴리오 수익률 등은 다음 월(t+1)의 전체 주식시장 수익률과 음(-)의 상관관계를 갖고 있는 것을 알 수 있었다. 이는 역사적인 데이터를 살펴볼 때, 이들 산업 제품의 가격의 상승은 향후 경제에 악영향을 주기 때문인 것이다. 반면에, 의류 및 무역 등의 경우에는 반대로 이들 산업들의 포트폴리오 수익률이 전체 주식시장 수익률과 양의 상관관계를 나타내 이들 산업들에 있어서 높은 수익률은 향후 경제가 상승국면이 예상됨을 나타내어 주고 있다. 이와 같은 산업별 포트폴리오 수익률과 거시경제변수 간의 높은 상관관계를 토대로 하여 전체 주식시장 수익률 예측을 가능하게 하는 업종 정보(sector information)의 점진적 확산(slow diffusion) 현상이 발생하게 되는 것이다.수 있었다.의 20세 이하 골절 및 탈구가$30.3\%까지 감소하게되어 년도가 증가함에 따라 청장년 층에 비하여 소아골절 및 탈구가 전체적으로 감소하는 경향을 보였다. 스키골절의 부위별 발생빈도는 1990년 이전까지 하지골절 및 탈구가 많았으나 이후 점차 상지의 골절 탈구가 증가하였다 하지에서 가장 많은 골절은 경골 골절이었으며, 경골골절은 회전력에 의한 나선형골절이 $76.5\%로 가장 많았고 년도에 따른 변화는 보이지 않았다. 스키손상의 발생빈도는 초기에 비하여 점차 감소하는 경향을 보였으며, 손상의 특성도 부위별, 연령별로 다양한 변화를 나타내었다.해가능성을 가진 균이 상당수 검출되므로 원료의 수송, 김치의 제조 및 유통과정에서 병원균에 대한 오염방지에 유의하여야 할 것이다. 확인할 수 있었다. 이상의 결과에 의하면 고농도의 유기물이 함유된 음식물쓰레기는 Hybrid Anaerobic Reactor (HAR)를 이용하여 HRT 30일 정도에서 충분히 직접 혐기성처리가 가능하며, 이때 발생된 $CH_{4}$를 회수하여 이용하면 대체에너지원으로 활용 가치가 높은 것으로 판단된다./207), $99.2\%$(238/240), $98.5\%$(133/135) 및 $100\%$ (313)였다. 각각 두 개의 요골동맥과 우내흉동맥에서 부분협착이나 경쟁혈류가 관찰되었다. 결론: 동맥 도관만을 이용한 Off pump CABG를 시행하여 감염의 위험성을 증가시키지 않으면서 영구적인 신경학적 합병증을 일으키지 않았고 좋은 혈관 개존율을 보여주었다. 따라서 동맥 도관을 이용한 Off pump CABG는 관상동맥의 협착의 정도에

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