• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.789-794
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• 2001

In this study, a program for the off-design performance prediction of multi-stage axial-compressors is developed based on stage-stacking method. To account for the increased losses at off-design conditions, generalized performance curve is applied. The purpose of this study is to investigate the influence of the choice of generalized performance curve and stator exit angle. For this purpose, we tested various generalized performance curves and stator exit angles. In conclusion, Muir's pressure coefficient curve gives a good prediction results regardless of the efficiency curve for a low-stage compressors. On the other hand, for high-stage compressors, The combination of Muir's pressure coefficient curve and Stone's efficiency curve gives a optimistic results. Stator exit angle has a small effect on overall performance curve.

• 한국정보처리학회논문지
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• 제6권6호
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• pp.1458-1467
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• 1999

신장해슁이나 B+-트리와 같은 기존의 색인구조들은 문자열의 부분검색을 지원하지 못하거나 부분검색에 제약점을 가지고 있다. 최근 웹 환경에서 동작하는 정보검색 엔진들이 사용하는 역파일의 빠른 검색성능을 가지면서 문자열 부분검색을 효율적으로 지원하는 색인기법을 제안한다. 제안된 색인기법은 기본적으로 역파일 구조이며, 2음절 단위의 패턴으로 색인을 구성함으로써 문자열 부분검색을 지원한다. 제안된 색인기법의 특성을 분석하기 위해 제안된 방법의 성능을 다양한 환경에서 실험을 통하여 비교하고 분석한다. 또한 성능평가를 위해 기존의 역파일 기법, 요약 파일 기법들과 제안하는 색인기법의 분석적 모델을 검색시간과 저장공간 측면에서 세시하고, 그 모델을 기반으로 그들의 성능을 비교한다. 분석적 비교모델을 통한 성능비교 결과, 제안된 부분검색을 위한 색인기법은 저장공간의 오버헤드는 크지만 기존 요약 파일 기법에 비해 검색성능을 상당히 향상시킨다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제3권2호
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• pp.138-145
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• 2003

Performance assessment was introduced to improvement of self-directed learning and method of assessment for differenced learning as the seventh educational curriculum is enforced. Performance assessment is overcoming limitation about problem solving ability and higher thinking abilities assessment that is problem of a written examination and get into the spotlight by way for quality of class and school normalization. But, performance assessment has problems about possibilities of assessment fault by appraisal, fairness, reliability, and validity of grading, ambiguity of grading standard, difficulty about objectivity security etc. This study proposes fuzzy performance assessment system to solve problem of the conventional performance assessment. This paper presented an objective and reliable performance assessment method through fuzzy reasoning, design fuzzy membership function and define fuzzy rule analyzing factor that influence in each sacred ground of performance assessment to account principle subject. Also, performance assessment item divides by formation estimation and subject estimation and designed membership function in proposed performance assessment method. Performance assessment result that is worked through fuzzy performance assessment system can pare down burden about appraisal's fault and provide fair and reliable assessment result through grading that have correct standard and consistency to students.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.62.1-62
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• 2001

This paper suggests an inverse optimal PID control design method for the trajectory tracking case of mechanical systems. Also, simple coarse/fine performance tuning laws are suggested based on the analysis for performance limitation of inverse optimal PID controller. Experimental results for a robot manipulator show the validity of our analysis for the performance tuning methods.

• 디지털산업정보학회논문지
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• 제10권4호
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• pp.63-70
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• 2014

Method a target estimation in spatial are mobile wireless communication using network cell and GPS. It have much error that mobile wireless communication depend on cell size. GPS method can't find a target in shadow and inner area. In this paper, we estimate a target as direction of arrival method using adaptive array antenna system. Adaptive array antenna system can obtain desired signal to remove other signal This paper studied digital beamforming method in order to estimation a target. Proposed method is modified optimum weight and antenna error correction to estimation an optimal receive signal. Digital beamforming method decided a signal phase and amplitude from received signal on array antenna element. But if it is not to do error correction of received signal, system performance have decreased. Firstly, we proposed modified optimum weight in order to finding desired target. Secondly, we are error correction of antenna incident signals by optimal weight before digital beamforming method. Thirdly, throughly simulation, we showed that system performance of proposed method compare proposal method with general method. It have improved resolution of estimation target to good performance more proposed method than general method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1860-1863
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• 1997

Transfer alignement is the process of initializing attitude of slave INS using the data of master INS. This paper presents the performance analysis of transfer alignment at sea using convariance analysis method. Velocity & angle matching and angular rate & acceleration matching are used for analysis, and the performance of two matching methods are compared. We propose a new method for angular rate & acceleration matching. Under the assumption of accurate modeling of ship flexure, the performance of transfer alignment time and accuray is improved very much for the new method.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.373-376
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• 2006

There are representative two performance evaluation methods for performance-based design(PBD) of reinforced concrete structures by the nonlinear static analysis, one method includes the capacity spectrum method(CSM) suggested in ATC-40(996) and the other is the displacement coefficient method(DCM) in FEMA-273(1997). The objective of this paper is to compare and verify two methods and suggest the displacement-based design for new performance evaluation of reinforced concrete structures.

• 대한기계학회논문집A
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• 제26권12호
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• pp.2483-2491
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• 2002

This study presents an efficient method for robust optimal design. In order to avoid the excessive evaluations of the exact performance functions, two-point diagonal quadratic approximation method is employed for approximating them during optimization process. This approximation method is one of the two point approximation methods. Therefore, the second order sensitivity information of the approximated performance functions are calculated by an analytical method. As a result, this enables one to avoid the expensive evaluations of the exact $2^{nd}$ derivatives of the performance functions unlike the conventional robust optimal design methods based on the gradient information. Finally, in order to show the numerical performance of the proposed method, one mathematical problem and two mechanical design problems are solved and their results are compared with those of the conventional methods.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.718-723
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• 2009

The purpose of this study is to present an in-site evaluation method for building insulation performance using Infra-red camera. The research contents of this study are to evaluate validity and suitability of building insulation defect survey using Infra-red camera for apartment housing with temperature & heat flow pattern analyze method. By establishing the in-site evaluation method building insulation performance using infra-red camera, it is expected that 1) building envelope repair market will be activated by using developed method in ESCO and remodeling companies, 2) the method developed in this research will contribute to reduce national energy consumption by promoting old building insulation remodeling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 심포지엄 논문집 정보 및 제어부문
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• pp.19-21
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• 2004

This paper considers pulse width modulation (PWM) methods which are used in 3-phase brushless DC motor controller. Due to many disadvantages of bipolar PWM method, unipolar PWM method is mostly used in industrial field. In constant speed control application, the unipolar PWM method shows a good performance of speed control. But in the wide range of speed control application, it shows a poor performance especially when deceleration is needed. So we propose hybrid PWM method that utilizes two PWM methods according to the sign of speed controller output. The simulation and experimental result shows that the proposed method improves a speed control performance of the brushless DC motor which is applied to industrial sewing machines.