• 대한교통학회지
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• 제28권6호
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• pp.159-166
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• 2010

통행분포(trip distribution)에서는 첫 단계인 통행발생(trip generation)에서 구해진 통행 유출량(trip production)과 통행 유입량(trip attraction)을 연결시키는 작업이 행해진다. 즉 하나의 존에서 유출되는 통행량을 다른 존에 분포시키는 과정이라 할 수 있다. 그런데, 통행분포모형에 사용되는 통행시간이나 비용 등의 통행저항들이 통행수요가 변함에 따라 함께 변함에도 불구하고 현재 사용하고 있는 중력모형에서는 이를 고려하지 못하는 한계를 갖고 있다. 즉, 목적지까지의 통행비용이 커지면 통행수요는 줄어들며, 반대로 통행비용이 적으면 통행수요가 커지는 것과 같은 관계가 존재하게 된다. 이런 측면에서 본 연구는 통행분포시 목적지간에 균형(equilibrium condition of trip distribution)이 존재함을 증명한다. 이를 위하여 대표적인 통행분포모형인 중력모형을 이용하여 통행분포시 균형조건을 유도하며, 이런 균형조건을 만족시키는 통행분포를 구하는 방법론을 제시한다. 또한, 본 연구에서 제시된 모형은 간단한 예제를 통하여 평가하며, 통행분포시 균형상태의 해가 도출됨을 확인한다.

• 대한산업공학회지
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• 제39권5호
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• pp.422-428
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• 2013

In many cases, an $\bar{X}$ control chart which is based on the performance variable is used in industrial fields. However, if the performance variable is too costly or impossible to measure and a less expensive surrogate variable is available, the process may be more efficiently controlled using surrogate variables. In this paper, we propose a model for the economic design of a VSI (Variable Sampling Interval) $\bar{X}$ control chart using a surrogate variable that is linearly correlated with the performance variable. The total average profit model is constructed, which involves the profit per cycle time, the cost of sampling and testing, the cost of detecting and eliminating an assignable cause, and the cost associated with production during out-of-control state. The VSI $\bar{X}$ control charts using surrogate variables are expected to be superior to the Shewhart FSI (Fixed Sampling Interval) $\bar{X}$ control charts using surrogate variables with respect to the expected profit per unit cycle time from economic viewpoint.

• 현장농수산연구지
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• 제25권4호
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• pp.67-77
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• 2024

This study analyzed the profitability and diagnosed business performance of fruit and vegetable (cherry tomatoes, tomatoes, strawberries, cucumbers) businesses targeting young farmers participating in the youth business incubation center of A Smart Farm Innovation Valley. The purpose of this is to provide basic data for decision-making by prospective young entrepreneurs. As a result of the analysis, Smart Farm Innovation Valley had the advantage of having a fixed rental fee. As a result, it was analyzed that various costs such as depreciation of large farm equipment, depreciation of farming facilities, repair and maintenance costs, land rent, floating capital service cost, fixed capital service cost, and land capital service cost are being reduced. However, excessive input of labor, water, electricity, other materials, and fertilizer costs was being made. Guidance to reduce these costs is expected to make a significant contribution to expanding the influx of young farmers.

• 동력기계공학회지
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• 제9권2호
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• pp.106-111
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• 2005

After many casualties of conventional bulk carriers in recent years, a double hull bulk carrier was proposed to enhance the structural safety of a side shell and a transverse bulkhead. In this paper, two alternative structural designs of a double hull bulk carrier were carried out based on the Lloyd's rule. One has the double sided hull with longitudinal stiffeners and the other has that with a girder. The final structural design was examined in comparison with an existing single hull bulk carrier from the viewpoints of cargo hold capacity and the increases of weight and construction cost. Generally, the construction cost of a ship consists of the costs of material, labor and overhead cost. But, in this study, the relative construction cost concept was introduced to compare the economical validity more precisely. In this concept, fixed overhead cost is excluded in the assessment of construction cost, and only the variable overhead cost is added up to labor cost. As the result of this study, a double hull bulk carrier can be constructed within 1% increase of weight and construction cost.

• Journal of the Korean Statistical Society
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• 제25권1호
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• pp.95-110
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• 1996

We consider the question of efficiency of the Bayes sequential procedure with respect to the optimal fixed sample size Bayes procedure in a simple vs. simple testing problem for data coming from a general nonregular density b(.theta.)h(x)l(x < .theta.). Efficiency is defined in two different ways in these caiculations. Also, the minimax sequential risk (and minimax sequential stratage) is studied as a function of the cost of sampling.

• 산업공학
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• 제13권3호
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• pp.455-461
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• 2000

Logistics systems can be evaluated by how productively distribution center operates, how promptly transportation vehicle dispatches, how efficiently facility layout is, and so on. In this paper, a practical vehicle routing scheme with fixed delivery time and fixed vehicle routes is introduced. The method helps the distribution center reduce logistics cost with respect to dispatching vehicles, and satisfy the customer with pre-determined delivery time window constraints. A case study has shown that the proposed scheme not only generates a feasible schedule with time windows, but also balances material flow in warehouse.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.270-273
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• 2000

A new phase shift PWM parallel-input/series-output modularized dual converter is proposed in this paper. This converter is operated with a fixed duty ratio and its output voltage is regulated by phase shift between each module. Since the operating duty ratio of each module is fixed it is sufficient to implement a simple open loop drive circuitry for each module and the cost of total system can be much reduced. The operation of the converter is analyzed in this paper and verified by computer simulation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.491-494
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• 2005

The present report addresses the durability related design issues for the structural reinforced concrete of the Busan-Geoje Fixed Link - Bridges and Immersed Tunnel. The overall aim of the durability related issues is to establish the requirements to the design and the construction that will secure the stated and achieve that objective with cost effective construction. To prove that the stated design life of 100 years is valid, a performance and reliability based verification, according on the DuraCrete approach have been performed.

• 한국경영과학회지
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• 제3권1호
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• pp.31-46
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• 1978

Consider a time interval during which the demand for trips is fixed (e.g. the rush hour period). The traveller has a choice between various public modes, whose travel times and fares are fixed, and the automobile mode, for which travel time and cost depend on the volume of traffic flow on those roads, which are subject to congestion. We consider the equilibrium in terms of a representative travellerm, who choses for any trip the mode and route with the least combined money and time cost. When several (parallel) model or routes are chosen, then the combined cost of money and time must be equal among these. Our problem is first, to find the optimal flows of cars and of public mode carriers on the various links of their networks and second the optimal fares for trips by the variousmodes. The object is to minimize the total operating costs of the carriers and car plus the total time costs to travellers. The optimal fares are related to, but not identical with the dual variables of the underlying Nonlinear Program. They are equal to these dual variables only in the case, when congestion tolls on trips or on the use of specific roads are collected from automobile users. When such tolls are not collected, they must be passed on as subsidies to travellers using competing modes. The optimal fares of public modes are then reduced by the amounts of these subsidies. Note that subsidies are not a flat payment to public carriers, but are calculated on the basis of tickets sold. Fares and subsidies depend in general on tile period considered. They will be higher during periods of higher demand. When the assumption of fixed trip demand is relaxed, this tare system is no longer best, but only second best since too much traffic will, in general, be generated. The Free Rider Theorem states the following : Suppose road tolls can be charged, so that a best pricing system for public modes is posssible. Then there may exist free rides on some routes and modes, but never on a complete round trip.

• 경영과학
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• 제13권2호
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• pp.25-48
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• 1996

Mixed Model Assembly Lines (MMALs) are increasingly used to produce differentiated products on a single assembly line without work-in-process storage, Usually, a typical MMAL consists of a number of (1) stations doing exactly the same operation on every job, (2) stations involving operations with different choices, and (3) stations offering operations that are not performed on every job, or that are performed on every job but with many options. For stations of the first type there is no sequencing problem at all. However, for the second type a set-up cost is incurred each time the operation switches from one choice to another. At the third type of stations, different models, requring different amounts and choices of assembly work, creates an uneven flow of work along the line and variations in the work load at these stations. When a subsequence of jobs requires more work load than the station can handle, it is necessary to help the operations at the station or to complete the work elsewhere. Therefore, a schedule which minimize the sum of set-up cost and utility work cost is desired. So this study has developed Fixed Random Ordering Rule (FROR), Fixed Ascending Ordering Rule (FAOR), Fixed Descending Ordering Rule, and Extended NHR (ENHR). ENHR is to choose optimal color ordering of each batch with NHR, and to decide job sequence of the batch with it, too. As the result of experiments, ENHR was the best heuristic algorithm. NHR is a new heuristic rule in which only the minimum addition of violations from both partial sequence and unassigned sequence at every branch could be considered. And this is a heuristic sequencing rule for the third type of stations at MMAL. This study developed one more heuristic algorithm to test the performance of NHR, which is named as Practical Heuristic Rule (PHR).