• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.685-687
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• 2003

최근 국내우주개발 중장기계획에 따라 지구관측위성, 통신위성, 기상위성 등 다양한 위성개발이 추진되고 있으나, 선진국들이 첨단 위성의 기술이전을 기피함에 따라 국내주도의 독자적인 차세대위성의 개발 필요성이 대두되고 있다. 그러나 새로운 위성의 설계, 제작, 조립 및 시험, 검증에는 많은 시설 및 장비가 필요하며 오랜 기간과 많은 예산이 소요된다. 이를 해결하기 위해 새로운 위성의 개발 시 선진국에서는 범용위성 개발 테스트베드(Flight System Testbed)를 제작하여 사전에 위성시스템을 모델링 및 검증함으로서 개발기간의 최적화, 개발예산의 최소화, 신기술의 적용 등에 활용하고 있는 추세이다. 국내의 경우, 위성의 지상관제와 운용요원의 교육을 위해 위성시뮬레이터를 제작하여 확용하는 단계이나, 새로운 위성 개발을 위한 위성전자전산시스템 개발검증장비 및 활용기술은 전무한 상태이다. 향후 다양한 위성임무에 대응한 위성의 개발기간 단축 및 비용절감과 첨단 위성전자시스템 및 부품기술의 사전 검증을 위해 위성 전자전산시스템 개발검증장비에 대한 연구가 필수적이다. 본 논문에서는 해외 위성선진국에서의 위성전자전산시스템에 대한 기술에 대해 살펴보고 현재까지 진행된 차세대 위성개발을 위한 위성시스템 개발검증 장비의 설계에 대해 알아보고자 한다.

• Journal of the Korea Society of Computer and Information
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• v.18 no.6
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• pp.1-8
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• 2013

In this paper, we design and implement a firmware for low-cost small PCR devices. To minimize machine code size, the proposed firmware controls real-time tasks simultaneously only with support of the hardware interrupt, but without support of the operating system program. The proposed firmware has the host-local structure in which the firmware receives operation commands from PC and sends operation results to PC through usb communication. We implement a low-cost small PCR device with the proposed firmware loaded on microchip PIC18F4550 chip, and verify that the implemented PCR device significantly reduces cost and volume size of existing commercial PCR devices with a similar performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12B
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• pp.1060-1065
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• 2003

As the Internet continues to grow, network games are widely spreaded. For most network games, many users' meet on a server causes a heavy load to the sewer, which in turn brings inconvenience to the user. Moreover, it demands increased expense to the service provider for deploying additional servers. In this paper, we propose a hybrid distributed system for network games. In our proposed system, a client is independents of the server and exchanges information directly with other clients. The client depends on servers only for the update information. The proposed methodology classifies messages according to the characteristics of information that the message handles and applies either client-to-server and pear-to-pear communication for processing messages which increases the efficiency of systems.

• Journal of Digital Contents Society
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• v.3 no.2
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• pp.221-233
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• 2002

In this paper, we present integer programming models and algorithms for the Capacitated Facility Location-Allocation Problem (CFLP). The models and algorithms can be used for the design of logistics networks and for the location of telecommunication facilities. We are given a set of candidate facility installation sites, one type of facility for each candidate site with its capacity and installation cost, a set of customers with their demand requirement, and flow cost for one unit of demand flow from each customer to each candidate site. (CFLP) is to determine the number of facilities for each candidate site and the set of customers which are connected to each site with minimum cost, while satisfying the demand requirement of each customer and constraints imposed on the allocation of customers to facilities. We present two integer programming models for (CFLP), and devise a branch-and-cut algorithm and a branch-and-price algorithm for the problem.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.3
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• pp.1-10
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• 2008

The seismic performance of a structure designed without consideration of seismic loading can be effectively enhanced through seismic rehabilitation. The appropriate level of rehabilitation should be determined based on the decision criteria that minimize the anticipated earthquake-related losses. To estimate the anticipated losses, seismic risk analysis should be performed considering the probabilistic characteristics of the hazard and the structural damage. This study presents the decision procedure in which the probabilistic seismic demand model is utilized for the effective estimation and minimization of the total seismic losses through seismic rehabilitation. The probability density function and the cumulative distribution function of the structural damage for a specified time period are established in a closed form, and are combined with the loss functions to derive the expected seismic loss. The procedure presented in this study could be effectively used for making decisions on the seismic rehabilitation of structural systems.

• Journal of Korea Port Economic Association
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• v.32 no.1
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• pp.123-133
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• 2016

LNG(Liquefied Natural Gas) bunkering has become an important issue with the enforcement of environment regulations in shipping industry required by the International Maritime Organization (IMO). With increased attention on LNG bunkering, many studies that focus on safety, regulation, demand forecasting, and the feasibility of LNG fueled ships have been carried out. However, most of the existing research has not included considerations of the price of LNG bunkering and its competitiveness. This paper, therefore, suggests ways to increase price competitiveness in the LNG bunkering market in the Busan Port. This paper analyzes the LNG bunkering supply mechanism by investigating various LNG bunkering terminal business in the LNG supply market. Factors that determine LNG bunkering price and its elasticity are also identified. Market players who want to operate LNG bunkering terminals in the Busan Port should introduce a merchandising trade method that is able to exclude the "Korea premium" in order to increase price competitiveness. This paper also suggests adoptable strategies such as the use of TPS (Terminal to Ship via Pipeline) type of bunkering service and the importance of location for minimizing initial investment cost.

• Korean Journal of Construction Engineering and Management
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• v.25 no.4
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• pp.34-44
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• 2024

In defense and military facility projects, adjustments to contract amounts due to design changes directly or indirectly affect factors such as increased construction costs and extended construction periods. Moreover, they can lead to differences of opinion and conflicts between the military and contracting parties. This case study analyzed the integrated management of defense and military facility projects by the Gyeonggi Southern Facilities Division, which oversees projects in Seoul and the southern Gyeonggi Province region for the Army, Navy, Marine Corps, and Air Force. Out of 388 completed projects, 103 cases with design changes were selected for analysis, aiming to ensure the reliability of data regarding the proportion of design changes in project completion. The study classified samples by the causes of design changes specified in the Ministry of Planning and Finance's contract regulations, assigning rankings based on the occurrence rates of each cause. Furthermore, it analyzed detailed factors for each cause of design change and derived implications to propose improvement measures. Considering the limited access to military primary data, this case study is expected to contribute to minimizing design changes in defense and military facility projects. Additionally, it is anticipated to be practically useful for subsequent research on contract amount adjustments resulting from design changes.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.443-448
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• 2003

A study on optimum design of the lightweight mirror of a satellite camera is presented. An optical surface deformation of the lightweight mirror, which is a principal component of the camera system, is an important factor affecting the optical performance of the whole camera system. In this study, optimum design of the lightweight mirror is presented. Total weight of the mirror to reduce the optical surface deformation and the launching cost is used as an objective function. Peak-to-valley value and natural frequency of the mirror are given as constraints to the optimization problem. The sensitivities of the objective function and constraint are calculated by a finite difference method. The optimization procedure is carried out by the commercial optimizer, DOT. As a verification of the optimum design of the mirror, two design examples are treated. In the real application example, the lightweight mirror with 600mm effective diameter is treated. The optimized results with various design variables, which are obtained by considering thickness limitations, are analyzed.

• The KIPS Transactions:PartA
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• v.13A no.1 s.98
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• pp.27-34
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• 2006

Designers should know CAD tool/license information such as available number of licenses or tools, types, and configuration methods to use CAD tools properly in their group. Usually, this information is provided by managers who administrate CAD tool and license servers in the specific design group. In the previous CAD tool/licenses sharing methods, designers have to get CAD tool/license information manually and setup the environments with their own hands. n a new designer comes into the design working group, the designer wastes unnecessary design time, because of these processes. As a result, designer's poductivity and utilization of CAD tools will decrease Besides, managers also waste their time and effort, since they should provide CAD tool/license information manually to each designer. In this paper, we present an automated scheme to share CAD tool/license information based on directory service. The proposed methods automate the communication processes between managers and designers that minimze unnecessary time to share CAD information. In addition, as this system maintains the consistency of CAD information automatically that remove the repeated work of managers and designers, it improves the enciency of sharing. Besides, it automates the license configuration steps using prof(y Last, we offer Executable Proxy which is proper for thin CAD application. We believe this scheme will reduce designers and managers' time and effort as well as maximize the utilization of CAD tools.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1053-1063
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• 2014

This study presents a sustainable design method that optimizes the embodied energy of concrete beam based on the concept of sustainable development that effectively utilizes natural resource and energy within the range that our succeeding generation can afford to utilize. In order to get the flexural strength carrying the ultimate load, concrete beam sections are designed by optimization that consists of the embodied energy as a objective function and the requirements of design code as constrained conditions. The sustainable design can be used to minimize the embodied energy consumed in material production, construction, operation, demolition of the infrastructure. As a result of comparison of the cost and the embodied energy optimizations based on practical beam sections, it is shown that 20% embodied energy saving and 35% $CO_2$ emission saving are achieved by sacrificing 10% cost increase. The sustainable design method provides a new effective methodology that manages the strength design concept based on cost minimization together with economic feasibility and sustainability. In addition, the method is expected to be applied to more various structural design practices.