• 한국멀티미디어학회논문지
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• 제7권3호
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• pp.327-339
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• 2004

본 논문에서는 반복적인 에러 최소화 기법을 이용한 하프톤 영상의 워터마킹 알고리즘을 제안하였다. 워터마크는 하프톤 영상의 랜덤한 위치의 픽셀값으로 저장된다. 삽입된 워터마크로 인한 하프톤 영상의 왜곡을 최소화하고 비가시성을 증대하기 위하여 반복적인 에러 최소화 기법이 사용된다. 원영상과 HVS(Human Visual System) 필터 처리된 하프톤 영상과의 차이를 하프토닝 에러로 정의하고 반복적으로 각각의 픽셀 위치에서 이 하프토닝 에러를 최소화할 수 있는 픽셀 패턴을 찾아서 이것으로 원래의 픽셀패턴을 대치한다. 절단이나 회전과 같은 기하학적인 변형에 견고하게 하기 위하여 동일한 워터마크를 반복하여 하프톤 영상안에 삽입하였다. 실제 인쇄 및 스캐닝 실험을 통하여 제안된 알고리즘이 기하학적 변형에 견고함을 보였고 또한 기존과 방법과 비교하여 제안된 방법이 많은 양의 워터마크 정보에도 불구하고 우수한 품질의 하프톤 영상을 생성함을 보였다.

• 응용통계연구
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• 제21권1호
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• pp.109-123
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• 2008

많은 소지역 추정량이 제안되었으며, 국내외에서 소지역 추정에 관한 많은 연구가 진행되고 있다. 또한 소지역 추정량의 특성과 우수성을 비교하기위한 비교통계량도 연구되고 있다. 기존의 소지역 추정량은 MSE(Mean square error)를 최소화하여 얻어지며, 이에 따라 추정량의 우수성도 MSE를 기준으로 판단하고 있다. 본 논문에서는 최근 새롭게 재조명 되고 있는 MSPE(Mean square percentage error)를 최소화하는 추정량을 제안하였다. 신기일 등 (2007)에서 사용된 비교통계량과 MSE 그리고 MSPB를 이용하여 제안된 추정량과 기존의 소지역 추정량을 비교하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.82-82
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• 2000

The way which estimates a position from Navigation is Dead-reckoning Navigation and Radio Navigation. Generally dead-reckoning navigation uses Gyro and odometer as sensor, but these have problems which are an integrating noise and a noise-sensitivity. Gps which is used by radio-navigation has a Troposthetic error and MultiPath ewer and so on. For minimizing a Troposthetic error and a Multipath error, this paper suggests to an algorithm which use vanishing point on CCD camera.

• 대한인간공학회지
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• 제26권4호
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• pp.121-125
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• 2007

The objective of this study is to develop short-term prevention measures for minimizing possible human error in nuclear power facilities. To accomplish this objective, a group of subject matter experts (SMEs) were formed, which is consisting of those from regulatory bodies, academia, industries and research institutes. Prevention measures were established for urgent execution in nuclear power facilities on a short-term basis. This study suggests short-term measures for reducing human error on three different areas; (1) strengthening worker management, (2) enhancing workplace environments and working methods, and (3) improving the technologies regulating human factors. Under the leadership of the Ministry of Science and Technology, these short-term measures will be pursued and implemented systematically by utility and regulatory agencies. The details of prevention measures are presented and discussed.

• 전기학회논문지
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• 제65권12호
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• pp.2189-2196
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• 2016

This paper proposes a new finite control set-model predictive control (FCS-MPC) method for induction motors. In the method, the reference state that satisfies the given torque and rotor flux requirements is derived. Cost indices for the FCS-MPC are defined using the state tracking error, and a linear matrix inequality is formulated to obtain a proper weighting matrix for the state tracking error. The on-line procedure of the proposed FCS-MPC comprises of two steps: select the output voltage vector of the two level inverter minimizing the cost index and compute the optimal modulation factor of the minimizing output voltage vector in order to reduce the state tracking error and torque ripple. The steady state tracking error is removed by using an integrator to adjust the reference state. The simulation and experimental results demonstrated that the proposed FCS-MPC shows good torque, rotor flux control performances at different rotating speeds.

• Journal of electromagnetic engineering and science
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• 제4권3호
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• pp.102-106
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• 2004

A novel Genetic Algorithm(GA)-based method is suggested to transform a coupling matrix to another, without the procedure of Matrix Rotation. This can remove tedious work like pivoting and deciding rotation angles needed for each of the iterations. The error function for the GA is simply formed and used as part of error minimization for obtaining the solution. An 8th order dual-mode elliptic integral function response filter is taken as an example to validate the present method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.382-386
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• 2002

The tapping is machining process that makes a female screw on the parts to be assembly together. It is used for the high-speed tapping machine with synchronizing function for the high productivity. This paper describes the development of the ultra high-speed tapping machine with 10,000rpm. The key factors in the tapping speed are the acceleration/deceleration velocity and the synchronizing errors between the spindle motor and feeding motor. To minimizing acceleration/deceleration time, the low inertia spindle with synchronous built-in servo motor is developed. To minimizing synchronizing errors, the tapping cycle algorithm under open architecture CNC environment is optimized. The developed tapping machine has 0.13sec/10,000rpm in acceleration/deceleration time and the synchronizing error below 4.0%. It has 0.55sec for cycle time of one female screw, M3 tap, 2 times depth of tap diameter.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.153-156
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• 1999

The technique is reported of identifying parameters in off-line process. The technique demands that closed-loop system consists of a reference and two-degree-of-freedom controllers (TDFC) in real process. A model process is the same as the real process except their parameters. Deviations are differences between the reference and the output of the plant or the model. The technique is based on minimizing identification error between the two deviations. The parameter differences between the plant and the model are characterized of mean value and of variance which are derived from the identification error. Consequently, the algorithm which identifies the unknown plant parameters is shown by minimizing the mean value and the variance, respectively, within double convergence loops. The technique is applied to course change of a ship. The plant deviation at the first trial is shown to occur in replacing the nominal parameters by the default parameters. The plant deviation at the second trial is shown to not occur in replacing the nominal parameters by the identified parameters. Hence, the identification technique is confirmed to be feasible in the real field.

• Structural Engineering and Mechanics
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• 제34권1호
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• pp.109-133
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• 2010

This paper addresses the modified Dynamic Relaxation algorithm, called mdDR by minimizing displacement error between two successive iterations. In the mdDR method, new relationships for fictitious mass and damping are presented. The results obtained from linear and nonlinear structural analysis, either by finite element or finite difference techniques; demonstrate the potential ability of the proposed scheme compared to the conventional DR algorithm. It is shown that the mdDR improves the convergence rate of Dynamic Relaxation method without any additional calculations, so that, the cost and computational time are decreased. Simplicity, high efficiency and automatic operations are the main merits of the proposed technique.

• 한국기계가공학회지
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• 제6권4호
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• pp.71-75
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• 2007

Geometrical error of ultra-precision machining due to spherical tool alignment error is analyzed. Deviation of spherical edge, ranged several ten micrometers, generates vertical and horizontal error of tool path and affects profile accuracy of machined surface. Simulation of machined error shows effect of tool alignment error and enables to estimate alignment error. This work provides technical insights into the minimizing of geometrical error of ultra-precision machining.