• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.959-968
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• 2017

Electrical safety monitoring System (ESMS) is a critical component in modern power systems, which is characterized by large-scale access points, massive users and versatile requirements. For convenience of the information integration and analysis, the software development, maintenance, and application in the system, the cloud platform based ESMS is established and assessed in this paper. Firstly the framework of the system is proposed, and then the assessment scheme with a set of evaluation indices are presented, by which the appropriate cloud product can be chosen to meet the requirements of a specific application. Moreover, to calculate the weights of the evaluation indices under uncertainty, an improved interval AHP method is adopted to take into consideration of the fuzziness of expert scoring, the qualitative consistency test, and the two normalizations in the process of eigenvectors. Case studies have been made to verify the feasibility of the assessment approach for ESMS.

• 한국안전학회지
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• 제12권3호
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• pp.67-75
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• 1997

This paper presents a study on the application of Asynchronous Team(A-Team) theory for QVC(Reactive power control) and security assessment in a power system. Reactive power control problem is the one of optimally establishing voltage level given reactive power sources, which is very important problem to supply the demand without interruption and needs methods to alleviate a bus voltage limit violation more quickly. It can be formulated as a mixed-integer linear programming(MILP) problem without deteriorating of solution accuracy to a certain extent. The security assessment is to estimate the relative robustness of the system and deterministic approach based on AC load flow calculations is adopted to assess it, especially voltage security. A distance measure, as a measurement for voltage security, is introduced. In order to analyze the above two problem, reactive power control and static security assessment, In an integrated fashion, a new organizational structure, called an A-team, is adopted. An A-team is well-suited to the development of computer-based, multi-agent systems for operation of large-scaled power systems. In order to verify the usefulness of the suggested scheme herein, modified IEEE 30 bus system is employed as a sample system. The results of a case study are also presented.

• 인터넷정보학회논문지
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• 제19권5호
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• pp.107-113
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• 2018

Object-oriented databases (OODBs) canbe used for many non-traditional database application areas such as computer-aided design, etc. Usually those application areas require advanced modeling power for expressing complicated relationships among data sets. OODBs have more distinguished features than the traditional relational database systems. One of the distinguished characteristics of OODBs is class hierarchy (also called inheritance hierarchy). A class hierarchy in an OODB means that a class can hand down the definitions of the class to the subclass of the class. In other words, a class is allowed to inherit the definitions of the class from the superclass. In this paper, we present performance evaluation metrics for class hierarchy in OODBs from a concurrency control perspective. The proposed performance metrics are developed to determine which concurrency control scheme in OODBs can be used for a given class hierarchy. In this study, in order to develop performance metrics, we use class hierarchy structure (both of single inheritance and multiple inheritance), and data access frequency for each class. The proposed performance metrics will be also used to compare performance evaluation for various concurrency control techniques.

• 대한전자공학회논문지SP
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• 제37권6호
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• pp.76-82
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• 2000

선박의 수중방사소음을 최소화하기 위해서는 주요 소음원인 탑재장비, 추진계통 및 구조물의 전달과정 등에 의해 발생되는 각각의 소음특성 규명이 이루어져야 한다. 그러나 선박의 운항시 계측된 신호는 다중의 소음원과 많은 전달경로에 의해 신호가 중첩되어 발생되고, 소음원과 전달함수를 계측할 수 없는 경우가 많다. 이 논문에서는 캡스트럼 신호처리를 이용한 계측된 응답신호로부터 각각의 소음원과 전달함수 특성을 분리 추출할 수 있는 시험분석기법을 제시하고, 제시된 기법을 수치계산 및 가진실험에 적용하여 검증하고 실제 선박에 적용하여 유용함을 보인다.

• 벤처창업연구
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• 제1권1호
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• pp.91-104
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• 2006

미래산업으로 각광 받으며 빠른 성장을 보일 것으로 예상되었던 텔레메틱스는 기술적, 경제적인 원인으로 인하여 기대되는 발전을 보여주지 못하고 있어 2020년을 목표로 하고 있는 국가교통시스템의 고도화인 u-Transportation 수립에도 차질을 빚을 수 있다. 이에 본 논문은 기술적, 경제적 단점을 해소하고 텔레메틱스 기반의 ITS 활성화를 도모할 수 있는 기술진보 현황을 제시하고 유비쿼터스 건설부분의 블루오션(Blue Ocean)이 될 수 있는 RFID(Radio Frequency IDentification)의 활용 현황을 살펴보고 사업화 방안에 대해 고찰하였다.

• 한국광학회지
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• 제35권5호
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• pp.218-227
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• 2024

펨토초 레이저 펄스를 이용한 테이블 탑(table-top) 규모의 THz파 광원은 주로 전자가 가진 전하량의 시공간적인 변화를 기반으로 한다. 본 해설논문에서는 전자가 가진 스핀 각운동량이 THz파 발생에 기여하는 새로운 방식에 대해 소개한다. 우선 강자성체(ferromagnet)에서의 레이저 유도 스핀 전류 발생에 초점을 맞추어 나노미터 두께의 강자성체/비자성체 복합 박막에서의 고출력, 광대역, 편광 자유도 등 우수한 특성을 설명한다. 또한 나노미터 두께의 박막을 기반으로 반도체 결합 소자 개발, 대면적 광 소자 개발, 플렉시블 광 소자 개발 등의 다양한 응용 기술 연구를 소개한다. 이를 통해 스핀트로닉 THz파 발생 원리를 이해하고, 차세대 THz 광 소자로서 주목받고 있는 전자의 스핀을 활용한 다양한 응용 연구를 수행하는 데 도움을 주고자 한다.

• 대한원격탐사학회지
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• 제38권5_2호
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• pp.781-791
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• 2022

산불로 인한 피해를 최소화하기 위해서 산불위험 예보 정보를 제공하는 것은 필수적이다. 따라서 본 연구에서는 우리나라를 대상으로 기계학습 기반의 산불위험 중기예보(1일 후부터 7일 후까지) 모델을 개발하였다. Global Data Assimilation and Prediction System (GDAPS)의 기상예보 자료와 기 개발된 산불위험지수(Fire Risk Index, FRI)의 과거 및 현재 정보, 그리고 기타 환경요소(i.e., 고도, 산불다발지수, 가뭄지수)의 현재 정보를 반영하여 모델을 개발하였다. 본 연구에서는 실시간 학습을 통해 모델을 개발하였으며, 효율적인 모델 개발을 목적으로 과거 산불위험지수와 가뭄지수의 유무를 고려하여 세가지 경우(Scheme 1: 과거 산불위험지수 및 가뭄지수, Scheme 2: 과거 산불위험지수, Scheme 3: 과거 산불위험지수 변화 추세 및 가뭄지수)로 연구를 수행하였다. 본 연구에서 개발된 산불위험예보모델은 예보기간에 상관없이 높은 정확도(피어슨 상관계수(Pearson correlation) >0.8, relative root mean square error <10%)를 나타냈으며, 실제 산불 발생 건에 대해서도 유의미한 결과를 보였다. 과거 산불위험지수의 추세보다는 산불위험지수 값 자체를 입력변수로 사용하는 것이 높은 정확도를 보였으며, 가뭄지수 사용과 관계없이 좋은 결과를 나타냈다.

• 한국물환경학회지
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• 제26권2호
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• pp.208-214
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• 2010

This study aimed at the introduction of desktop method for assessment of environmental flows developed by International Water Management Institute (IWMI) recently and its application to Geum river basin. This scheme simulated the influence on aquatic ecosystem caused by watershed development and in turn the decrease of water quantity keeping the river's own flow regime. It was found to be as very effective method although it had simple structure. Flow duration curves for different environmental classes at Sutong and Gongjoo sites were estimated according to the natural conditional scenario of Geum river basin and the results were relatively compared well with the previous studies. The behaviors of monthly average runoff time series of both sites showed the level of A class. The results of this study would provide the fundamental data to establish the future plans of monitoring or management for aquatic ecosystem of Geum river basin.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.202-205
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• 1990

In this paper the development of new technique based on the travelling-wave information contained in the post fault voltage and current signals has been presented. To develop fault location methods which can cope with close-up fault and zero-inception angle problems, magnitude of the backward wave has been used. The technique developed can be incorporated in a generalized algorithm for application as a high speed distance scheme. In this way some of the problems and limitations associated with travelling wave schemes are avoided. Verification of the relay operating principles is presented through digital computer numerical simulation using an electromagnetic transient program(EMTP) in conjunction with simulation of the proposed algorithms.

• Journal of applied mathematics & informatics
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• 제27권1_2호
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• pp.301-313
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• 2009

This paper presents a Finite Element Method (FEM) application to thermal study of natural three layers of human dermal parts of varying properties. This paper carries out investigation of temperature distributions in these layers namely epidermis, dermis and under lying tissue layer. It is assumed that the outer skin is exposed to atmosphere and the loss of heat due to convection, radiation and evaporation of water have also been taken into account. The computations are carried out for one dimensional unsteady state case and the shape functions in dermal parts have been considered to be quadratic. A Finite Element scheme that uses the Crank-Nicolson method is used to solve the problem and the results computed have been exhibited graphically.