• Transactions on Control, Automation and Systems Engineering
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• 제4권4호
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• pp.330-340
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• 2002

In this Paper. a non-linear approach to a design of model reference adaptive control is presented. The approach is demonstrated by a case study of a simple single-pole and no zero, linear, discrete-time plant. The essence of the idea is to generate a full non-linear model of the plant dynamics and the parameter adaptation dynamics as a gradient descent algorithm with respect to a Riemannian metric. It is shown how a Riemannian metric can be chosen so that the modelled plant dynamics do in fact match the true plant dynamics. The performance of the proposed scheme is compared to a traditional model reference adaptive control scheme using the classical sensitivity derivatives (Euclidean gradients) for the descent algorithm.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권3호
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• pp.292-299
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• 2004

For Web System composed of a variety of hardware, software and network system, there is a wide difference in price, function and capacity. In addition, it is important to select the most suitable system when web system is constructed as the claim of high-quality web service from user has increased. Data of bench-marking is usually employed when the system is selected. Evaluation with the result of bench-marking, however, is not easy at web situation composed of a variety of systems. In this paper, first integrated bench-marking of hardware, software and network system metric were determined, and the plan to effectively compare and evaluate the result of bench-marking by using fuzzy set were offered.

• 디지털융복합연구
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• 제1권1호
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• pp.45-67
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• 2003

Developing user success metric will make it possible to evaluate the effectiveness of different electronic government systems and will help produce empirical data relating user success to task performance in electronic government environments. The purpose of this study is that combining output-oriented and interaction-oriented variables together into a single model might explain more of the variance in the dependent variable user success in a electronic government than either type of variable could have explained alone. The hypothesized reason is that user success is the result of the reciprocal effects of the properties of the information system and several facets of psychological functioning. Thus, the complex interplay between the system and the user in certain situational contorts may produce different degrees of user success with electronic governments.

• Journal of Communications and Networks
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• 제6권2호
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• pp.123-132
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• 2004

The various challenges to realize a fixed wireless ATM network are discussed and some solutions for these challenges are presented. In this paper, the capacity allocation in wireless ATM, the wireless link impact on ATM traffic, and the optimum utilization of the wireless network resonrces for a line of sight (LOS) winless ATM link are studied. An adaptive MQAM modulator is introduced to provide a suitable solution to these issues. The modulator level is adjusted using a unique QoS metric in a wireless network. The metric, termed modified effective bandwidth, takes into account the bandwidth demand, QoS requirements, and outage conditions of the wireless ATM link. A performance study using VBR MPEG-l video traffic in a fixed wireless channel (Ricean channel) demonstrates the advantages of the proposed system.

• Journal of Multimedia Information System
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• 제5권2호
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• pp.67-78
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• 2018

This article proposes the modified KNN (K Nearest Neighbor) algorithm which considers the feature similarity and is applied to the word categorization. The texts which are given as features for encoding words into numerical vectors are semantic related entities, rather than independent ones, and the synergy effect between the word categorization and the text categorization is expected by combining both of them with each other. In this research, we define the similarity metric between two vectors, including the feature similarity, modify the KNN algorithm by replacing the exiting similarity metric by the proposed one, and apply it to the word categorization. The proposed KNN is empirically validated as the better approach in categorizing words in news articles and opinions. The significance of this research is to improve the classification performance by utilizing the feature similarities.

• 시스템엔지니어링학술지
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• 제17권2호
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• pp.69-81
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• 2021

The human performance issues and increased automation issues in advanced Small Modular Reactors (SMRs) are critical to numerous stakeholders in the nuclear industry, due to the undesirable implications targeting the Man Machine Interface Systems (MMIS) complexity of (Generation IV) SMRs. It is imperative that the design of future SMRs must address these problems. Nowadays, Multi Agent Systems (MAS) are used in the industrial sector to solve multiple complex problems; therefore incorporating this technology in the proposed innovative SMR (I-SMR) design will contribute greatly in the decision making process during plant operations, also reduce the number MCR operating crew and human errors. However, it is speculated that an increased level of complexity will be introduced. Prior to achieving the objectives of this research, the tools used to analyze the system for complexity reduction, are the McCabe's Cyclomatic complexity metric and the Henry-Kafura Information Flow metric. In this research, the systems engineering approach is used to guide the engineering process of complexity reduction concept of the system in its entirety.

• Journal of Internet Technology
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• 제20권1호
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• pp.293-300
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• 2019

The Internet of Things (IoT) enables embedded devices to connect to the internet either through IP or the web in a physical environment. The increase in performance of wireless access services, adaptive load balancing, and interference routing metric becomes the key challenges in Wireless Mesh Networks (WMN). However, in the case of IoT over WMN, a large number of users generate abundant net flows, which can result in network traffic jam. Therefore, in this paper, we propose a Load Balancing and Interference Delay Aware routing metric algorithm to efficiently address the issues present in the current work. The proposed scheme efficiently utilizes the available mesh station queue information and the number of mesh stations suffering from channel interference in the available path. The simulations results show that the proposed scheme performed superior to the existing routing metrics present in the current literature for similar purposes.

• 한국정보과학회논문지:시스템및이론
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• 제30권9호
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• pp.445-453
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• 2003

일정 수준의 시스템 성능을 제공하기 위해 다수의 서버를 클러스터로 연결하여 동시에 가동할 경우, 서버의 가동 대수가 증가함으로 인해 발생하는 가용도 저하 문제를 해결해야 하며, 이를 위해서는 시스템의 성능 변화를 반영할 수 있는 가용 성능에 대한 명확한 정의가 요구된다. 기존의 가용도에 관한 연구들은 시스템의 성능(대기시간, 응답시간 등)을 고려하지 않는 가용도 계산 모델이 주를 이루고 있으며, 또한 클러스터 시스템을 구성하는 주 서버의 결함 발생을 허용하기 위한 방안에 대한 연구가 부족하였다. 본 논문에서는 위와 같은 문제점들에 대한 해결 방안의 일환으로, 비용 효율적인 결함허용을 위해 n 대의 주 서버와 k 대의 여분서버로 구성된 클러스터 시스템에서 대기시간을 일정 수준이하로 만족시키는지에 근거한 새로운 가용도 척도를 제시하였으며, 다양한 시스템 운영 상태에 대한 실험을 통하여, 시스템의 대기 시간 데드라인 성능이 포함된 보다 현실적인 가용도 및 downtime을 계산하였다.

• 한국통신학회논문지
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• 제28권10C호
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• pp.942-948
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• 2003

채널 상태 정보 (Channel State Information, CSI)를 사용하지 않는 비동기식 복조기를 위한 다중 격자 부호화 연속 위상 주파수 변조 방식 (Multiple Trellis Coded Modulation applied to Continuous Phase Frequency Shift Keying, MTCM/CPFSK)의 성능을 비상관적인 라이시안 페이딩 채널상에서 분석하였다. 복조기에서 신호 판별에 적합한 척도(metric)로 수신 신호와 후보 신호 사이의 제곱 교차 상관값 (squared cross-correlation)을 사용하였으며, 이 때 신호쌍 오류(Pairwise Error Probability, PEP)를 구하였다. 또한, PEP를 이용하여 신호 사이의 등가 정규화 기하 제곱 거리 (Equivalent Normalized Squared Distance, ENSD)를 구하고, 완벽한 CSI를 사용하는 비동기식 MTCM/CPFSK의 ENSD와 비교하였다. 마지막으로, PEP를 변환 함수 상한법(Transfer Function Bounding, TFB)에 대입하여 각각의 방법에 의해 구해진 이론적인 비트 오류 성능(Bit Error Rate, BER)을 비교하고, 모의실험 결과를 통하여 검증하였다.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제21권5호
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• pp.379-386
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• 2015

본 논문에서는 스마트폰 사용자 중심의 반응 완료 시간에 대한 동적 분석을 활용하여 사용자가 실제 인지하는 성능 중심의 새로운 최적화 프레임워크를 제안한다. 이를 위하여 먼저 스마트폰 응용프로그램에서 사용자가 실제 인지하는 성능에 대한 평가 지표로써 사용자 중심 반응 시간을 정의한다. 또한, 이러한 사용자 중심 반응 시간의 동적 탐색에 기반하여 사용자가 인지할 수 있는 성능 병목 지점을 최적화의 힌트로써 개발자에게 제공하는 사용자 중심 반응 시간 분석 도구의 설계와 개발에 대하여 소개한다. 제안한 사용자 중심 반응 시간 분석 도구를 갤럭시 넥서스 스마트폰에 구현하여 그 정확도와 계산부하를 평가한 결과, 전체 반응 시간의 1% 미만의 계산 부하로 카메라를 이용하여 측정한 결과 대비 92%의 정확도를 보였다. 제안한 도구의 효율성 평가를 위하여 소스 코드가 공개되어 있는 안드로이드 응용프로그램의 성능 개선에 제안한 도구를 활용하여 최대 16.4%의 성능 향상을 달성하였다.