• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.11a
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• pp.227-233
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• 1998

본 논문에서는 다양한 이동환경에 따른 기지국에서의 전력제어에 의한 위치검출 및 등록, 관리기능, 핸드오프 등과 같은 여러가지 기능들 중 사용자 단말에 대한 이동성을 보장하여 사용자가 자신의 기지국을 벗어난 경우에도 중단 없는 서비스 제공이 가능하도록 해주는 핸드오프 절차와 기법에 대해 고찰한다. 또한 BSA(Basic Service Area)에 독립적으로 분산되어 있는 이동단말들을 대상으로 기존의 방식에서의 자원할당방식을 고찰한다. 본 논문에서는 외국에서의 연구사례를 고찰하여 상대적인 비교를 토대로 사용자 단말에 이동성을 보장하며, 또한 이용률을 극대화시키기 위한 동적자원 할당이 가능한 VCT, NCNR 방식을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3154-3164
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• 1996

A major concern in a cellular mobile communication system is how to efficiently utilize the limited amount of frequencies. Various channel assignment methods and traffic sharing schemes have been proposed to improve system performance. However, these approaches suffer from complicated software and hardware requirements due to increased amount of traffic control In this paper, we propose a new method for improving system performance by controlling the powers of the set-up and voice channels of each cell site. We first show that the average number of blocked calls in a system is minimized when the traffic reates are made identical for all cell sites in a system. This result, together with the relationship between the channel powers and the service area, is used to determine the appropriate channel powers of each cell site. We also determine the upper limit on the channel power of each cell site considering co-channel interference and numerically show that the proposed method is effective in reducing the number of blocked calls without an excessive increase in the amount of system control.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.729-733
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• 1988

In this paper, a new procedure for selecting weighting matrices in linear discrete time quadratic optimal control problems (LQ-problem) is proposed. In LQ problems, the quadratic weighting matrices are usually decided on trial and error in order to get a good response. But using the proposed method, the quadratic weights are decided in such a way that all poles of the closed loop system are located in a desired area for good responses as well as for stability and values of the quadratic cost functional are kept less then a specified value. The closed loop systems constructed by this method have merits of LQ problems as well as those of pole assignment problems. Taking into consideration that little is known about the relationship among the quadratic weights, the poles and the values of cost functional, this procedure is also interesting from the theoretical point of view.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.21
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• pp.29-41
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• 1990

An assessment of risk in industrial and urban environments is essential in the prevention of accident and in the analysis of situations which are hazardous to public health and safety. The risk imposed by a particular hazard increases with the likelihood of occurence of the event, the exposure and the possible consequence of that event. In a traditional approach, the calculation of a quantitative value of risk is usually based on an assignment of numerical values of each of the risk factors. Then the product of the values of likelihood, exposure and consequences called risk score is derived. However vagueness and imprecision in mathematical quantification of risk are equated with fuzziness rather than randomness. In this paper, a fuzzy set theoretic approach to risk analysis is proposed as an alternative to the techniques currently used in the area of systems safety. Then the concept of risk evaluation using linguistic representation of the likelihood, exposure and consequences is introduced. A risk assessment model using approximate reasoning technique based on fuzzy logic is presented to drive fuzzy values of risk and numerical example for risk analysis is also presented to illustrate the results.

• Journal of the Korea Society of Computer and Information
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• v.20 no.9
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• pp.105-111
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• 2015

This paper suggests O(n) linear-time algorithm for car sequencing problem (CSP) that has been classified as NP-complete because of the polynomial-time algorithm to solve the solution has been unknown yet. This algorithm applies maximum options-equiped car type first production rule to decide the car sequencing of n meet the r:s constraint. This paper verifies thirteen experimental data with the six data are infeasible. For thirteen experimental data, the proposed algorithm can be get the solution for in all cases. And to conclude, This algorithm shows that the CSP is not NP-complete but the P-problem. Also, this algorithm proposes the solving method to the known infeasible cases. Therefore, the proposed algorithm will stand car industrial area in good stead when it comes to finding a car sequencing plan.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.8
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• pp.733-739
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• 2005

Device Description that is described as C-based DDL(Device Description Language) should be provided for the control system to use the progressive function of field device in the distributed control system. DD expresses field device function itself and parameter. DD is used to set a necessary function far a control strategy in the central control system. DD technology which was adopted as international standard IEC 61804-Part 2 is being used in PROFIBUS, Foundation Fieldbus and HART. However, the DD is dependent to the fieldbus and it doesn't have a suitable form in the industrial Ethernet. This paper presents the possibility of a change from EDD(Electronic Device Description) and GSD(General Slave Data) used for integrating field devices to XDD(XML for Device Description) and verifies it's effectiveness. Also, this paper presents research assignment on the XML application in the distributional system from now on by examining the possibility of Ethernet`s development in the industrial area.

• ETRI Journal
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• v.43 no.2
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• pp.173-183
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• 2021

As low-power wide-area network (LPWAN) end devices (EDs) are deployed in massive scale, their economic and environmental costs of operation are becoming too significant to ignore and too difficult to estimate. While LPWAN architectures and protocols are designed to primarily save energy, this study shows that energy saving does not necessarily lead to lower cost or environmental footprint of the network. Accordingly, a theoretical framework is proposed to estimate the operational expenditure (OpEx) and environmental footprint of LPWAN EDs. An extended constrained optimization model is provided for the ED link assignment to gateways (GWs) based on heterogeneous ED configurations and hardware specifications. Based on the models, a simulation framework is developed which demonstrates that OpEx, energy consumption, and environmental footprint can be in conflict with each other as constrained optimization objectives. We demonstrate different ways to achieve compromises in each dimension for overall improved network performance.

• Korean Institute of Interior Design Journal
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• v.22 no.3
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• pp.154-163
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• 2013

Current principles of designating a smoking area within a non-smoking area rely on mere compartmentalization. This causes non-smokers aversion against smokers and smokers complaints about anti-smoking policies, which means both of them are not satisfied with the current scheme. In addition, such a system, far from the original intent of the law, does not provide appropriate respect for people's rights. The biggest problem of the current scheme is that smoking areas are not separated from non-smoking areas. Japan has continued installing independent smoking areas since 2002 and witnessed a decrease in the smoking rate. The country's success is attributable to: the state's active intervention in connection with enterprises; continuous environmental improvements and creation of goods; 'smoking etiquette' campaigns; and the sociality and group consciousness of Japanese people. It is recognized that the synergy of the designation of independent smoking areas and such multi-faceted efforts has led to the nation's accomplishment. Hence, it is required to install independent smoking areas in non-smoking areas in Seoul in order to respect the rights of smokers and non-smokers and resolve conflicts between them. It is not suitable to merely model after Japan's case, however, studies and guidelines that are tailored to Korea's own environment and social atmosphere are required. To ensure that the people recognize the necessity for smoking areas, a social consensus is formed and proper smoking areas are established in a systemic manner, a system for that purpose should connote a symbol of the social consensus and consequent guidelines should take physical elements, human activities and semantic assignment into consideration. This study aims to present basic guidelines to install separated smoking areas, which will keep distance between smokers and non-smokers, form a social consensus and establish a sound smoking culture. These would ensure that the rights of both smokers and non-smokers are fully respected and that government policies are trusted by the people.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.145-154
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• 2009

The main goal of this paper is to develop a methodology for increasing the reliability of truck OD matrices in Seoul Metropolitan Area. We propose a Hybrid Method made up of five processes by using Non-Traffic Assignment and Gradient Method. A Hybrid Method and Gradient Method have applied for comparison and estimation in Seoul Metropolitan Area. Mean Error and Root Mean Square Error of a Hybrid Method present lower than Gradient Method. The findings of this paper show that the new truck OD matrices created by a Hybrid Method are more reliable than the existing truck OD matrices in the Seoul Metropolitan Area.

• Journal of Internet Computing and Services
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• v.15 no.5
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• pp.33-41
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• 2014

The purpose of this study is to provide statistical analysis based suggestions on effective methods to take advantage of social network service (SNS) for educational purposes based on investigations of undergraduate students with high utilization of SNS. To achieve this, we conducted an open questionnaire survey and qualitatively analyzed the data using NVivo 10 program. Additionally, to visualize the analysis by education subject of the SNS educational methods, we have divided the data into 3 categories of teacher, student and common area. As a result, our analysis showed that the exchange opinions and discussions, information sharing and learning of contents of questions and answers, surveys, intimacy formation, counseling etc. were of the common area. Furthermore, teacher area included the notice announcement, teaching materials sharing, real-time assessment (quiz), attendance check, assignment grading and feedback, etc. Finally the student area was of project activities (group/individual), prepare and review the shared data, video self learning, peer review and feedback of projects, lecture evaluation, etc.