• 대한교통학회지
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• 제8권2호
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• pp.55-66
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• 1990

The research deals with the establishment of transportation areas in the metropolitan cities. The purpose is three-fold ; 1) to review the existing literature : 2) to analyze the commuting (work and school) pattern and interregional movement pattern of passengers and freights ; 3) to establish the metropolitan transportation area based on the above analyses. The transportation area is defined by the analysis of trip pattern to the center city of each metropolitan area. The detailed indices for establishment are selected by the rank-size and time-distance analyses. For the operational purpose, the study defines 3 different transportation areas as follows : the first transportation area means the directly effecting region of the center city ; the second means the region with many reverse trips and development potentials ; and the third means the indirectly effecting region. It can be concluded that the first transportation area includes 10 cities and 5 counties in Seoul metropol tan region, Yangdsan-Gun, Kimhae-Gun and Kimhae-Si in Busan, Dalsung-Gun, Chilgok-Gun and Kyungsan-Gun in Daegu, Hwasung-Gun and Raju-Gun in Kwangju, and Daeduk-Gun in Daejun. These results could be expected to have many implications for the establishment of area-wide public transportation network, the metropolitan transportation decision-making bodies and others.

• 한국해양공학회지
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• 제13권3B호
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• pp.116-126
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• 1999

The purpose of this study is to analyze the economic aspect of sea transportation system between Inchon and Youngjong island in which Inchon international airport is being constructed. Total demand of sea transportation arising from in the airport and Yongyu Muwi leisure complex was estimated. To select optimum transportation route, environmental conditions in and around Inchon harbour and Youngjong island including the change of water depth by tide current, fog, rain, wind adn typhoon, ets., were investigated. The preliminary consideration on ships (size, velocity, transport capacity, price), routes, operational modes, terminals and berthing facilities were carried out. The transportation cost per passenger by sea transportation system was estimated to compare with that of land transportation system. It was found that sea transportation system proposed is competitive to the transportation system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 추계학술대회 논문집
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• pp.17-18
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• 2012

Generally, speed control system is used to control the elevator door. The whole speed profile must be installed in the speed controller of the door control system. However, it is not easy to modify the speed profile when door opening size and time are changed. In this paper, the making speed profile is discussed by the door opening size and time. The position control algorithms of PMSM for elevator door system are compared with general speed control, position control method with speed controller, and position control with speed command feedforward compensation by simulation using MATLAB/SIMULINK.

• Journal of Forest and Environmental Science
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• 제32권2호
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• pp.173-181
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• 2016

This study designed a model of the efficient production schemes and raw materials transportation optimization of current South Korean's simple and monolithic distribution system of wood to build a SCM (supply chain management) as a basic level to establish a distribution of future by pellet production of raw materials costs and reduce transport costs, and specifically to forest of pallet to contribute to revitalizing the market. The result of each transportation costs after building the best transportation network from raw material supply area to demand area applying transport law was 964,600 thousands Won from 6 supply areas to 7 demand areas. And the result of each model's analysis to get the pellet's efficient production through production cost reduction showed that it reduced from 325,701 Won/t to 240,106 Won/t, results of existing efficient pellet for the production model 8,233 tons over 20,000 tons annual production capacity from the size of the expanded production capacity when the expansion. However, when the production size expanded to 50,000 Tons of the production, the effect was very small even though production cost decreased.

• 대한교통학회지
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• 제24권4호
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• pp.103-113
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• 2006

화물운송시장의 분할은 운송시장의 효율화를 기하고 운송인이 물동량을 유치하기 위한 전략을 알기 위해 사용된다 화주 개개인의 성향을 파악하기 어려우므로 화주를 동질성을 갖는 몇 개의 군집으로 묶어 집단의 성향을 파악한다. 우리나라의 경우 표준산업분류의 배열순서에 따라 시장분할을 하여 왔다. 본 연구는 제조업체를 대상으로 새로운 운송시장 분할 가능성을 평가하였다. 연구의 결과 시장분할을 위한 적정 기준은 연간 입 출하량으로 우수한 분할능력을 보였다 또한 표준산업분류표의 배열순서에 따른 시장분할과 다른 결과를 도출하였다 본 연구는 물동량 발생 주체인 제조업체의 규모와 출하특성을 나타내는 자료를 이용하여 운송시장을 분할한 시도로서 의의가 있다.

• 대한안전경영과학회지
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• 제19권3호
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• pp.123-128
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• 2017

Logistics companies distinguish between medium-sized business and small business according to the size of enterprises. Of course, conglomerates are called global corporations. In this study, mid-sized companies over a certain size or more and those below are classified and decide the priorities among important factors to secure competitiveness in logistics companies are determined through AHP technique. Mid-sized companies are companies that can provide more than two logistics services. For example, they provide warehousing and transportation services in the same time. small companies are companies that can mostly provide one functional service. Warehousing, transportation, manpower, and information are listed as factors in this study. As a result of the study, medium-sized companies emphasized on the importance of transportation. When it comes to small companies, warehousing was emphasized as an important factor. Due to the simultaneous and contemporary service of warehousing and transportation in small-sized company, the reliable image of the company will be underestimated in case of delays in transportation. Competitiveness will also be weakened. Global corporations or conglomerates will start to consider relocating warehousing areas to others except for the central storage hub. They won't plan to invest directly, either. Therefore, it will be possible to secure competitiveness by providing the function of warehousing and to signed easily partnership.

• 한국입자에어로졸학회지
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• 제17권3호
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• pp.43-54
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• 2021

Size distributions of atmospheric particulate matter (PM) and its water-soluble organic and inorganic components were measured between January and February 2021 at an urban site in Gwangju in order to identify the major factors that determine their size distributions. Their size distributions during the study period were mainly divided into two groups. In the first group, PM, NO₃^-, SO₄^2-, NH₄⁺ and water-soluble organic carbon (WSOC) exhibited bi-modal size distributions with a dominant condensation mode at a particle size of 0.32 ㎛. This group was dominated by local production of secondary water-soluble components under atmospheric stagnation and low relative humidity (RH) conditions, rather than long-range transportation of aerosol particles from China. On the other hand, in the second group, they showed tri-modal size distributions with a very pronounced droplet mode at a diameter of 1.0 ㎛. These size distributions were attributable to the local generation and accumulation of secondary aerosol particles under atmospheric conditions such as atmospheric stagnation and high RH, and an increase in the influx of atmospheric aerosol particles by long-distance transportation abroad. Contributions of droplet mode NO₃^-, SO₄^2-, NH₄⁺ and WSOC to fine particles in the second group were significantly higher than those in the first group period. However, their condensation mode contributions were about two-fold higher in the first group than in the second group. The significant difference in the size distribution of the accumulation mode of the WSOC and secondary ionic components between the two groups was due to the influx of aerosol particles with a long residence time by long-distance transport from China and local weather conditions (e.g., RH).

• 대한산업공학회지
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• 제28권3호
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• pp.256-263
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• 2002

This paper addresses a planning problem in a pickup-delivery transportation' system under dynamic vehicle dispatching. We present a procedure to determine a fleet size in which stochastic characteristics of vehicle travels are considered. Statistical approach and queueing theory are applied to estimate vehicle travel time and vehicle waiting time, based on which an appropriate fleet size is determined. Simulation experiments are performed to verify the proposed procedure.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.171-178
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• 2002

At the present time, container transportation plays a key role in the international logistics and the efforts to increase the productivity of container logistics become essential for Korean trucking companies to survive in the domestic as well as global competition. This study suggests an approach for determining fleet size for container road transportation with dynamic demand. Usually the vehicles operated by the transportation trucking companies in Korea can be classified into three types depending on the ways how their expenses occur; company-owned truck, mandated truck which is owned by outsider who entrust the company with its operation, and rented vehicle (outsourcing). Armually the trucking companies should decide how many company-owned and mandated trucks will be operated considering vehicle types and the transportation demands. With the forecasted monthly data for the volume of containers to be transported a year, a heuristic algorithm using tabu search is developed to determine the number of company-owned trucks, mandated trucks, and rented trucks in order to minimize the expected annual operating cost The idea of the algorithm is based on both the aggregate production planning (APP) and the pickup-and-delivery problem (PDP). Finally the algorithm is tested for the problem how the trucking company determines the fleet size for transporting containers.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
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• pp.63-67
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• 2001

Since the transportation cost takes about two thirds of the logistics cost of Korean firms, significant reduction of business logistics cost can hardly be achieved without effectively reducing the transportation cost. Although consolidated transportation has been regarded as the most promising strategy for reducing the transportation cost, it has not been successful in practice. In this paper we consider a consolidated transportation for the factories located in a limited area such as industrial complexes, where loads of various volume and weight are consolidated. We want to group the loads to assign to a truck of various size such that the total transportation cost is minimized, while the maximum volume constraint and weight constraint of each truck are satisfied. We suggest four heuristic algorithms to efficiently determine the groups of loads; and conduct a computer simulation to evaluate the performances of the algorithms.