• Management Science and Financial Engineering
• /
• v.8 no.2
• /
• pp.33-45
• /
• 2002

This study suggests an approach for determining fleet size for LTL (less -than-truckload) transportation with dynamic demand for on-time supply of the parts between the assembly line in an automobile company and its part suppliers in Korea. The vehicles operated by the transportation trucking companies in Korea in general 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 entrusts the company with its operation, and rented truck (outsourcing) . With the forecasted monthly production data a year, a heuristic algorithm is developed to determine the number of company-owned trucks, mandated trucks, and rented trucks in order to minimize the expected annual operating cost, which is based on the solution technologies used in the aggregate production planning and vehicle routing problem. Finally the algorithm is tested for the problem how the trucking company transports parts for the automobile company.

• Korean Management Science Review
• /
• v.19 no.2
• /
• pp.75-89
• /
• 2002

According to the fast-paced environment of information technology and improving customer services, the design activities of logistics systems improve customer centric services and delivery performance implementing e-logistics system. The fundamental design issues that arise in the delivery system planning are optimizing the system with minimum cost and maximum throughput and service level. This study is concerned with the integrated model development of delivery system with customer responsive service level for DCM, Demand Chain Management. We used a two-step approach for this study. First, we formulated the supply. center facility planning using stochastic set-covering problem and assigned the customers to the supply center using clustering algorithm. Second, we developed vehicle delivery planning for a supply center based on GIS, GIS-VRP. Also we developed a GUI-type computer program for proposed method for supply center problem using GIS and Geo-DataBase of Busan area. The computational results showed that the proposed method was very effective on a set of test problems.

• Korean Management Science Review
• /
• v.14 no.2
• /
• pp.47-61
• /
• 1997

This paper considers the parallel machines scheduling problem characterized as a multi-objective combinatorial problem. As this problem belongs to the NP-complete problem, genetic algorithms are applied instead of the traditional analytical approach. The purpose of this study is to show how the problem can be effectively solved by using genetic algorithms with a permutation approach. First, a permutation representation which can effectively represent the chromosome is introduced for this problem . Next, a schedule builder which employs the combination of scheduling theories and a simple heuristic approach is suggested. Finally, through the computer experiments of genetic algorithm to test problems, we show that the niche formation method does not contribute to getting better solutions and that the PMX crossover operator is the best among the selected four recombination operators at least for our problem in terms of both the performance of the solution and the operational convenience.

• Management Science and Financial Engineering
• /
• v.2 no.1
• /
• pp.123-145
• /
• 1996

We consider a priority-based multiclass queue with probabilistic feed-back. There are J service stations. Each customer belongs to one of the several priority classes, and the customers of each class arrive at each station in a Poisson process. A single server serves queued customers on a priority basis with a nonpreemptive scheduling discipline. The customers who complete their services feed back to the system instantaneously and join one of the queues of the stations or depart from the system according to a given probability. In this paper, we propose a new method to simplify the analysis of these queueing systems. By the analysis of busy periods and regenerative processes, we clarify the underlying system structure, and systematically obtain the mean for the sojourn time, i.e., the time from the arrival to the departure from the system, of a customer at every station. The mean for the number of customers queued in each station at an arbitrary time is also obtained simultaneously.

• Management Science and Financial Engineering
• /
• v.10 no.2
• /
• pp.73-87
• /
• 2004

Automotive and aircraft assembly process rely on fixtures to support and coordinate parts and subassemblies. Fixture layout in multi-station panel assemblies has a direct dimensional effect on final products and thus presents a quality problem. This paper describes a methodology for fixture layout design in multi -station assembly processes. An optimal fixture layout improves the robustness of a fixture system against environmental noises, reduces product variability, and eventually leads to manufacturing cost reduction. One of the difficulties raised by multi-station fixture layout design is the overwhelmingly large number of design alternatives. This makes it difficult to find a global optimality and, if an inefficient algorithm is used, may require prohibitive computing time. In this paper, simulated annealing is adopted and appropriate parameters are selected to find good fixture layouts. A four-station assembly process for a sport utility vehicle (SUV) side frame is used throughout the paper to illustrate the efficiency and effectiveness of this methodology.

• Architectural research
• /
• v.7 no.1
• /
• pp.1-9
• /
• 2005

The needs of collaboration among design participants spread in different locations is emphasized in the early design stage in order to not only save time and provide places to meet and talk, but also to save cost for those events as well: This is being realized by the Internet, which helps support a networked, integrated real-time multi-user environment. As the base for collaboration activities moves from physical places to cyberspace, the methods of connecting every participant by means of a computer technology have been desired and considered. This study aims at investigating today's collaboration technology in the architectural design process, especially focused on the early stages, in terms of temporal dimensions. In addition, major concepts for and previous efforts and tools of collaborative design have been examined, and a specific recommendation has been proposed for future development of collaborative architectural design systems: That is distributed collaboration, which is accessible and comprehensible to all the professionals in the building design team, which not only allows the sharing of information but also the sharing of understanding, and which facilitates the development of design tools for different aspects of the envisioned collaborative design environment.

• Bulletin of the Korean Space Science Society
• /
• 1992.10a
• /
• pp.12-12
• /
• 1992

Results from the Earth Radiation Budget Experiment (ERBE) will help interpret the data from the operational satellite system. However, a major problem exists because a follow-on experiment to ERBE is not planned until the late 1990`s. Meanwhile, it will be necessary to provide OLR estimates from the operational satellite system. Since 1973the outgoing long wave radiation(OLR) data have been obtained by the 10#m window radiance(AVHRR) estimation technique from he observation NOAA operational satellites. However, those data have not been universall if accepted because they are estimated from the radiance in but one narrow spectral regiou. However , this type of technique has not been exploited for use with data from the ]fIRS multispectral radiometer. Since the radiance data measured by HIRS contains more: information on atmospheric variables than the AVHRR, it is a potentially better instrument for operational estimates of the OLR In this study, results from model are better flux estimates than the AVHRR, The technique is then tested by comparing simultalleous AVHRR and HIRS OLR estimations with a radiation model flux calculation froml homogeneous atmospheric scenes at the regions of desert and subtropic ocean.

• Journal of Multimedia Information System
• /
• v.3 no.3
• /
• pp.69-76
• /
• 2016

Currently, research on more convenient and safer cars for drivers and passengers, the intelligent cars, are being actively conducted. The researches involve designing systems that intelligently minimize physical damages caused by car accidents, not just pursuing passive safety measures like airbags or safety belts. However, there are many cases around the world where airbags cannot be activated in times of accidents and it is difficult for consumers to check if their airbags will be activated, especially for the old-style cars. Thus, in this paper, a base technology for an application that can determine whether the airbags will actually be actuated at a critical moment based on the mechanical calculations is being introduced.

• The Journal of Korea Robotics Society
• /
• v.2 no.1
• /
• pp.21-28
• /
• 2007

The Intelligent Space(ISpace) provides challenging research fields for surveillance, human-computer interfacing, networked camera conferencing, industrial monitoring or service and training applications. ISpace is the space where many intelligent devices, such as computers and sensors, are distributed. According to the cooperation of many intelligent devices, the environment, it is very important that the system knows the location information to offer the useful services. In order to achieve these goals, we present a method for representing, tracking and human following by fusing distributed multiple vision systems in ISpace, with application to pedestrian tracking in a crowd. And the article presents the integration of color distributions into particle filtering. Particle filters provide a robust tracking framework under ambiguity conditions. We propose to track the moving objects by generating hypotheses not in the image plan but on the top-view reconstruction of the scene. Comparative results on real video sequences show the advantage of our method for multi-object tracking. Also, the method is applied to the intelligent environment and its performance is verified by the experiments.

• Journal of Astronomy and Space Sciences
• /
• v.26 no.4
• /
• pp.651-658
• /
• 2009

Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.