• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.234-241
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• 2002

In this study, a numerical method which assesses running stability of freight car loading 300m CWR and structural safety of conventional railway track when passing over curves and steel girder bridges is presented. Optimal speed of the freight car is suggest on the basis of numerical reviews for stability of derailment of the freight car and structural safety of track at weak points of the conventional line.

• 대한교통학회지
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• 제8권1호
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• pp.41-54
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• 1990

The rapid increase in the freight movement in Korea demands the improvement of the freight transportation system both in quantity and in quality. In recent studies integrated freight terminals have been suggested as the most relevant physical facility that solves this problem. This paper is aiming at the efficiency of the freight transportation system in Korea via integrated freight terminals. We develop a mixed integer programming model to determine simultaneously the most efficient freight flow patterns as well as the optimal locations and sizes of the integrated freight terminal facilities. The results of the model implication is also presented.

• 대한산업공학회지
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• 제24권1호
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• pp.157-165
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• 1998

This paper considers the single-product production and transportation problem with discrete time, dynamic demand and finite time horizon, an extension of classical dynamic lot-sizing model. In the model, multiple freight container types are allowed as the transportation mode and each order (product) placed in a period is shipped immediately by containers in the period. Moreover, each container has type-dependent carrying capacity restriction and at most one container type is allowed in each shipping period. The unit freight cost for each container type depends on the size of its carrying capacity. The total freight cost is proportional to the number of each container type employed. Such a freight cost is considered as another set-up cost. Also, it is assumed in the model that production and inventory cost functions are dynamically concave and backlogging is not allowed. The objective of this study is to determine the optimal production policy and the optimal transportation policy simultaneously that minimizes the total system cost (including production cost, inventory holding cost, and freight cost) to satisfy dynamic demands over a finite time horizon. In the analysis, the optimal solution properties are characterized, based on which a dynamic programming algorithm is derived. The solution algorithm is then illustrated with a numerical example.

• 산업공학
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• 제20권2호
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• pp.204-215
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• 2007

This paper addresses vehicle routing planning in freight container transportation systems where a number of loaded containers are to be delivered to their destination places. The system under consideration is static in that all transportation requirements are predetermined at the beginning of a planning horizon. A two-phased procedure is presented for freight container transportation. In the first phase, the optimal model is presented to determine optimal total time to perform given transportation requirements and the minimum of number of vehicles required. Based on the results from the optimal model, in the second phase, ASA(Accelerated Simulated Annealing) algorithm is presented to perform all transportation requirements with the least number of vehicles by improving initial vehicle routing planning constructed by greedy method. It is found that ASA algorithm has an excellent global searching ability through various experiments in comparison with existing methods.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.194-201
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• 2002

In this study is presented a numerical method which assesses running safety of the freight car loading with loom CWR and structural safety of conventional railway track and fastening when passing over sharp curves and steel girder bridges. Optimal speed of the freight car is suggested based on the numerical reviews of the safety against derailment of the freight car and structural safety of track and fastening at vulnerable points of the conventional line.

• 한국항해항만학회지
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• 제28권6호
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• pp.509-515
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• 2004

여객수와 화물량에 대한 예측은 터미널의 개발 및 계획, 선사의 적정선복량 화보를 위해 중요하다. 본 연구에서는 역전파 학습 알고리즘을 이용한 뉴럴네트웍을 이용하여 목포항 여객수와 화물량을 예측하였다. 그리고 이동평균법, 지수평활법, 뉴럴네트웍의 예측수행을 평균제곱오차, 절대평균오차로 비교하여 뉴럴네트웍의 예측수행능력이 우수함을 검정하였다. 또한 2005년 목포항 여객수와 화물량을 예측하여 여객선 선복량의 적정성을 분석하였다.

• International Journal of Advanced Culture Technology
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• 제9권3호
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• pp.271-276
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• 2021

In this paper we analyze the effect of the credit period on inventory policy under trade credit with ordering cost including a fixed cost and freight cost, where the freight cost has a quantity discount. For marketing purposes, some supplier offers credit period to his buyer to stimulate the demand for the product he produces. The delay in payments during the credit period has the effect of reducing the buyer's capital opportunity cost. It is also assumed that the buyer pays the freight cost for the order and hence, the ordering cost consists of a fixed ordering cost and a variable freight cost which depends on the order quantity. As a result, the possibilities of trade credit and discounts on freight costs are expected to play an important role in the buyer's inventory policy. Based on the economic order quantity inventory model, we analyze how the buyer can determine the optimal inventory policy and we examine the effect of the length of credit period on the buyer's inventory policy.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2000년도 추계학술대회 및 정기총회
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• pp.275-278
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• 2000

This paper focuses on a performance analysis model for optimizing the freight terminal design and layout using AutoMod simulator and numerical analysis. We developed a model to analyze the freiht terminal performance per unit time and the material handling cost based on both throughput and waiting due to conjestion. We developed computer program for this model and some sample results by both numerical method and AutoMod simulator are compared.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2002년도 춘계학술대회
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• pp.237-241
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• 2002

This paper deals with the problem of determining the buyer's economic lot sizing policy for exponentially deteriorating products under trade credit. It is also assumed that the ordering cost consists of a fixed set-up cost and a freight cost, where the freight cost has a quantity discount offered due to the economies of scale. We formulate the mathematical model and the solution algorithm is developed based on the properties of an optimal solution.

• Journal of Advanced Marine Engineering and Technology
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• 제24권4호
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• pp.502-508
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• 2000

The amount of container freight is continuously increasing recently, but freight congestion problem frequently occurs at ports due to low efficiency of container crane in transportation and cargo handling. In this paper, a method for designing a fuzzy controller of the container crane system is presented. In this scheme a mathematical model for the system is obtained in state space representation. The response of the proposed fuzzy controller is compared with that of the optimal controller at the same condition. Through the simulation results, the performance of the fuzzy controller was observed better than that of optimal controller in respect of reference change, disturbances and parameter change. The fuzzy controller was also more stable and robust than the optimal controller.