• 한국컴퓨터산업학회논문지
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• 제2권4호
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• pp.435-442
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• 2001

최근에 인터넷상에서 정보이용이 급증함에 따라 멀티미디어 정보를 효율적으로 관리하고 검색하기 위한 여러 가지 방법들이 제안되고 있다. 따라서 본 논문에서는 SRR(Semantic Reference Relation)과 DRR(Direct Reference Relation)을 이용한 새로운 그룹화 방법을 제안한다. 제안된 방법은 MDI(Multimedia Document Informations)를 멀티미디어 객체 클러스터로 간주하여 그룹화 한다. 제안된 방법의 성능을 알아보기 위하여 1000개의 멀티미디어 문서데이터를 테스트하며, 그 결과 제안된 방법의 성능이 보다 효율적임을 보인다.

• Journal of Biosystems Engineering
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• 제21권3호
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• pp.306-314
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• 1996

A seeder monitoring system was developed to solve the problems of mis-sowing and tube clogging in direct seeding machines, which have been one of the factors that reduce the performance of sowing operations. The system consisted of photo sensors, air nozzles, an air compressor, and a one-chip micro-computer based controller. The system was also equipped with the devices that perform the functions of self-checking and intermittent air injection for cleaning seed tubes. The performance of the system was tested in the laboratory and field. Using the well-cleaned rice seed, the average time for checking the mis-sowing was 1.37 seconds in the field and 1.2 seconds in the laboratory without any malfunction. Overall evaluation of the system indicated that the system can be utilized for seeding machines not only for paddies but beans and corns.

• International Journal of Safety
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• 제1권1호
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• pp.1-6
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• 2002

It is important to control the high accurate position and force to prevent unexpected accidents by a robot manipulator. Direct-drive robots are suitable to the position and force control with high accuracy, but it is difficult to design a controller because of the system's nonlinearity and link-interactions. This paper is concerned with the study of the stabilization force control of direct-drive robots. The proposed algorithm is consists of the feedback controllers and the neural networks. After the completion of learning, the outputs of feedback controllers are nearly equal to zero, and the neural networks play an important role in the control system. Therefore, the optimum adjustment of control parameters is unnecessary. In other words, the proposed algorithm does not need any knowledge of the controlled system in advance. The effectiveness of the proposed algorithm is demonstrated by the experiment on the force control of a parallelogram link-type robot.

• 한국전산유체공학회지
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• 제7권2호
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• pp.17-24
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• 2002

The transient flow fields in a direct injection engine was analyzed by using the STAR-CD CFD code doting the intake/compression processes. The analyses were focused on the computation grid generation by using the IC3M code which is a pre-developed and especially well adapted for the analyses of internal combustion engine. The results showed that the used grid generation technique was well suited for the flow analyses on any internal combustion engine.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2001년도 추계 학술대회논문집
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• pp.63-69
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• 2001

The transient flow fields in direct injection engines were analyzed by using the STAR-CD CFD code during the intake/compression processes. The analyses were focused on the computation grid generation by using the IC3M code which is a pre-developed and especially well adapted for the analyses of internal combustion engines. The results showed that the used grid generation technique was well suited for the flow analyses on any internal combustion engines.

• Journal of Electrical Engineering and Technology
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• 제2권4호
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• pp.505-512
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• 2007

The object of this paper is to study a new control structure for sensorless induction machines dedicated to electrical drives using a three-level voltage source inverter VSI-NPC. The amplitude and the rotating speed of the flux vector can be controlled freely. The scheme investigated is an Enhanced direct torque control "EDTC" for electric vehicle propulsion. The considered application imposes some constraints which are achieved in EDTC control (fast torque response, optimal switching logic, torque control at zero speed, and large speed control. The results obtained for an induction motor indicate superior performance over the FOC type without need for any mechanical sensor.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.898-902
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• 1995

STEP is a neutral model for exchanging CAD modelbetween different CAD systms. The paper presents a laser path contour generation for rapid prototyping originated form STEP format files without using any tools nor libraries for STEP data manipulation. Polygons are generated from every point on the layer of given thickness, which are the intersections of layer plane and edges stored in entity tables. Curves are approximated with polygons whitin segment tolerance limit in order to cover sculptured surfaces. With the advantage of less data loss in direct slicing over STL formats, the system developed in this work shows a good potential to provide data share with various CAD systems including RP data preparation.

• 대한수학회보
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• 제48권5호
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• pp.1033-1039
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• 2011

Let R be a ring with identity 1, I(R) be the set of all idempotents in R and G be the group of all units of R. In this paper, we show that for any semiperfect ring R in which 2 = 1+1 is a unit, I(R) is closed under multiplication if and only if R is a direct sum of local rings if and only if the set of all minimal idempotents in R is closed under multiplication and eGe is contained in the group of units of eRe. In particular, for a left Artinian ring in which 2 is a unit, R is a direct sum of local rings if and only if the set of all minimal idempotents in R is closed under multiplication.

• Structural Engineering and Mechanics
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• 제6권5호
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• pp.473-484
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• 1998

The first and second moments of response variables for SDOF systems with hysteretic nonlinearity are obtained by a direct linearization procedure. This adaptation in the implementation of well-known statistical linearization methods, provides concise, model-independent linearization coefficients that are well-suited for numerical solution. The method may be applied to systems which incorporate any hysteresis model governed by a differential constitutive equation, and may be used for zero or non-zero mean random vibration. The implementation eliminates the effort of analytically deriving specific linearization coefficients for new hysteresis models. In doing so, the procedure of stochastic analysis is made independent from the task of physical modeling of hysteretic systems. In this study, systems with three different hysteresis models are analyzed under various zero and non-zero mean Gaussian White noise inputs. Results are shown to be in agreement with previous linearization studies and Monte Carlo Simulation.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.218-223
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• 2007

This paper presents a simple, robust excitation control system for synchronous generator using direct instantaneous voltage control(DIVC) method. The proposed DIVC excitation system can operate as high dynamics of power conversion system without any control gains such as Pill controller. And the transient overshoot of generator voltage can be suppressed with a simple time constant. For the continuous control of excitation system, the fast IGBT inverter system is used in this paper for exciter's field control. The proposed control scheme is verified by the computer simulations and experimental results in the prototype generation system.