• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.1
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• pp.32-36
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• 2011

In this study, authors have proposed the autonomous state estimation which has been composed with IEC61850, GPS time synchronization and objective model design concept. The proposed method is able to supervise/correct measurement and communication error from SCADA. The major advantages of the proposed autonomous state estimation are that it is possible to evaluate integrity of data measured and transferred from SCADA, to reduce human intervention and to expense national-size applications such as EMS (Energy Management System), WAMS (Wide Area Monitoring System) or WAPS (Wide Area Protection System). This study addresses the issues related to the operation of the smart grid and proposes a new automated approach to achieve this goal. Through applying the proposed system to IEEE 14-bus test electric system, we prove the possibility of the proposed idea.

• Journal of Distribution Science
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• v.16 no.2
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• pp.19-24
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• 2018

Purpose - Drone delivery is expected to revolutionize the supply chain industry. This paper aims to introduce a collaborative parcel delivery problem by truck and drone (hereinafter called "TDRP") and propose a novel heuristic method to solve the problem. Research design, data, and methodology - To show the effectiveness of collaborative delivery by truck and drone, we generate a toy problem composed of 9 customers and the speed of drone is assumed to be two times faster than truck. We compared the delivery completion times by 'truck only' case and 'truck and drone' case by solving the optimization problem respectively. Results - We provide literature reviews for truck and drone routing problem for collaborative delivery and propose a novel and original heuristic method to solve the problem with numerical example. By numerical example, collaborative delivery is expected to reduce delivery completion time by 12~33% than 'truck only' case. Conclusions - In this paper, we introduce the TDRP in order for collaborative delivery to be effective and propose a novel and original heuristic method to solve the problem. The results of research will be help to develop effective heuristic solution and optimize the parcel delivery by using drone.

• Journal of the Korean Operations Research and Management Science Society
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• v.37 no.2
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• pp.1-16
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• 2012

NCW(Network Centric Warfare) offers BSEs(Battelspace-Entities) the capabilities of sharing information through C4ISRCommand, Control, Communications, Computers and Intelligence, Surveillance and Reconnaissance) network and it also improves their combat powers based on information superiority with awareness of common situation in battlefield and self-synchronization. Although the concept of NCW was developed at the end of 1990 and there have been various studies for NCW from the development of its concept, the effort for measuring the synergistic effect of NCW is insufficient at the present time. Therefore, in this paper we reviewed literatures concerning the effectiveness measurement of NCW. The category of our survey is network effect, metrics, simulation, battlefield information, social network analysis and mathematical model. The main purpose of this study is to suggest future researchers a research direction by analyzing the aspects and limitations of existing studies about the quantitative measurement of NCW.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.305-308
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• 2007

현재 네트워크상에 사용자를 인증하는 부분은 시스템 보안상으로 아주 중요한 역할을 하고 있다. 공개된 네트워크에서는 개인의 중요한 프라이버시 정보를 보호하기 위해 인증 절차를 거치게 된다. 이러한 인증 방법에는 간단한 Identity/Password 인증부터 복잡한 생채 공학 인증까지 다양한 기술들이 존재 한다. 최근 금융보안업계가 주축이 되어 일회용패스워드(OTP : One Time Password) 인증 시스템을 활용하기 위한 기술적 시도 및 개발이 활발히 이루어지고 있다. 일회용 패스워드는 사용자가 인증 받고자 할 때 새로운 패스워드를 생성하고 사용 후 버린다는 구조를 가지고 있다. 이는 매번 같은 패스워드를 사용했을 때 발생하는 보안 문제점을 해결할 수 있다. 그러나 OTP 인증 방법에도 여러 가지 공격 방법에 취약한 문제점들이 노출되어 있다. 본 논문은 기존의 인증 프로토콜 문제점을 개선하고 크기가 작은 스트림 알고리즘을 이용하여 스마트카드에서 사용 가능한 새로운 인증 프로토콜을 제안한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2096-2105
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• 1997

A parallel approach using a network of engineering workstations is presented for the efficient computation in the elastoplastic analysis of strip rolling process. The domain decomposition method coupled with the frontal solver for elimination of internal degrees of freedom in each subdomain is used. PVM is used for message passing and synchronization between processors. A 2-D plane strain problem and the strip rolling process are analyzed to demonstrate the performance of the algorithm and factors that have a great effect on efficiency are discussed. In spite of much communication time on the network the result illustrates the advantages of this parallel algorithm over its corresponding sequential algorithm.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.11-14
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• 2002

Incurable disease such as palsy and imbecility results from bolld pressure and bloodstream hitch. These diseases result in high blood pressure and brain bloodstream obstacle. So, we developed bloodstream improvement system that can improve bloodstream state using physical stimulation. It controls inflow and outflow of air to press and oppress human body sequentially. We can select stimulation region, pattern, pressure and time. Also, it can improve brain bloodstream state, because it can treat stress or headache putting pressure band on head. It can be used as breathing assistance system which has function for breath synchronization.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.643-645
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• 1999

통신망에서 시각/주파수 동기(synchronization)를 맞추기 위해서는 지상망을 이용하거나 위성을 이용하는 방법이 있다. 위성을 이용한 방법에서 지상의 송신국은 정밀시각정보, 위성위치데이타 및 오차보정데이타 등을 위성으로 송신한다. 이를 위해서 송신국의 위성데이터처리장치는 데이터 수집 및 가공, 베이스 밴드부로의 전송시 외부 기능블럭들과 신뢰성 있고 신속한 데이터처리를 수행하여야 한다. 본 논문에서는 한국통신의 무궁화위성을 이용한 시각/주파수 전송시스템 개발의 일환으로 송신국의 위성데이타처리장치에 대한 설계 및 구현 알고리즘을 제시하고자 한다.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.91-98
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• 2012

This paper implements 2X2 MIMO Long Term Evolution (LTE) base station using Software defined radio (SDR) technology. The implemented base station system processes baseband signals on a Graphics Processor Unit(GPU). GPU is a high-speed parallel processor which provides very important advantage of using a very powerful C-based programming environment that is Compute Unified Device Architecture (CUDA). The implemented software-based base station system processes baseband signals through GPU. It utilizes USRP2 as its RF transceiver. In order to guarantee a real-time processing of LTE baseband signals, we have adopted well-known signal processing algorithms such as frame synchronization algorithms, ML detection, etc. using GPU operating in parallel processing.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.3
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• pp.153-168
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• 1998

In this study we consider a CONWIP system in which the processing times at each station follow an exponential distribution and the demands for the finished Products arrive according to a compound Poisson process. The demands that are not satisfied instantaneously are assumed to be backordered. For this system we develop an approximation method to obtain the performance measures such as steady state probabilities of the number of parts at each station, the proportion of backordered demands, the average number of backordered demands and the mean waiting time of a backordered demand. For the analysis of the proposed CONWIP system, we model the CONWIP system as a closed queueing network with a synchronization station and analyze the closed queueing network using a product form approximation method. A matrix geometric method is used to solve the subnetwork in the application of the product-form approximation method. To test the accuracy of the approximation method, the results obtained from the approximation method were compared with those obtained by simulation. Comparisons with simulation have shown that the approximate method provides fairly good results.

• Journal of Sensor Science and Technology
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• v.9 no.6
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• pp.448-454
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• 2000

This paper describes the implementation of a multi-subject, multi-channel optical telemetry system for the short range measurement of electrocardiograms (EKGs) a system which receives command signals and transmits physiological signals to the external system using LED (Light Emitting Diode) and PD (Photodiode). This system decreases the dependency of power supply voltage to the CMOS IC chips and a new enforced synchronization technique using infrared bi-directional communication has also been proposed. The telemetry IC with the size of $5.1{\times}5.1mm^2$ has the following functions: receiving of command signal, initialization of internal state of all functional blocks, decoding of subject selection signal, time division multiplexing of 4-channel modulated physiological signals, transmission of modulated signals to external system, and auto power down control.