• 한국자동차공학회논문집
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• 제10권3호
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• pp.151-158
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• 2002

Automotive engineers involved in a new car project use various CAD systems that are chosen based on work requirements. For example, engineers in Hyundai Motors are using Pro/Designer and Alias fur the style design, but they use CATIA to design parts and assemblies, ANSYS for FEM analysis, and Pro/Engineer to design engines. Because they use different CAD systems, they have difficulties in collaborative design. Data, which contains errors, is transferred between CAD systems. It is difficult to find out such errors in a large CAD model. An evaluation method for CAD models has been developed in this study. This diagnosis tool analyses a STEP or an IGES file generated from a CAD system, and produces a quantitative error report. The tool has been tested with actual data sets. This paper proposes an algorithm that produces mathematical error values of entities of IGES models that have geometrical data, and entities of STEP models that have topological data, and inspects every part off model. To develop this system, we have used the OpenCASCADE kernel, which is an open source kernel developed by Matra Datavision of France.

• 한국멀티미디어학회논문지
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• 제7권11호
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• pp.1571-1579
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• 2004

비디오를 다양한 단말과 이종의 망에 효과적으로 제공하기 위한 방법 중에, FD(Frame Dropping)-CD(Coefficient Dropping) 트랜스코딩 기법은 계산량을 줄이고, 손쉽게 구현할 수 있다는 측면에서 주목을 받고 있다. 그러나, FD-CD트랜스코딩 기법은 CD에 의한 왜곡이 GOP내의 부호화 의존성을 갖는 프레임의 복호화 영상 품질에 많은 영향을 미친다. 본 논문에서는, CD로 인하여 각 프레임별로 전파되는 왜곡의 크기를 적응적으로 예측하는 모델링 기법을 제안한다. 제안된 기법은 각 프레임별로 부호화된 매크로블록의 부호화 모드 비율에 대해 적응적으로 구해진다. 모의실험을 통하여, 제안된 모델은 CD로 인해 초래되는 전체 왜곡크기를 잘 예측할 수 있음을 보이고, 또한, 부호화된 비트스트림에서 CD에 의해 초래되는 프레임 단위로 일정한 전체 왜곡을 삽입하는데 효과적임을 보인다.

• ETRI Journal
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• 제29권5호
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• pp.559-568
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• 2007

This paper presents a new distortion control scheme with a simple estimation model for the propagation errors incurred by dropping some parts of the bitstream in a frame dropping-coefficient dropping (FD-CD) transcoder. The primary goal of this paper is to facilitate bit-rate conversions and rate-distortion controls in the compressed domain without introducing a full decoding and reencoding system in the pixel domain. First, the error propagation behavior over several frame sequences due to coefficient dropping is investigated on the basis of statistical and empirical properties. Then, such properties are used to develop a simple estimation model for the CD distortion accounting for the characteristics of the underlying coded-frame. Finally, the proposed estimation model allows us to determine the amount of coefficient dropping and to effectively allocate rate-distortions into coded-frames. Experimental results show that the proposed estimation model accurately describes the characteristics of propagation errors adaptively in the compressed domain and can be easily applied to distortion control over different kinds of video sequences.

• 한국측량학회지
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• 제17권3호
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• pp.213-223
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• 1999

부가가치가 큰 대규모 공공자료인 국가기본도 수치지도 자료기반의 고품질을 확보하고, 수치지도제작에서 발생할 수 있는 각종 오류들을 효율적으로 탐색할 수 있는 개선된 수치지도제작 모형을 구현하였다. 이를 위해 기존에 제작된 수치지도를 분석하고 수치지도 상에 포함될 수 있는 각종 오류를 대분류 자료층으로 구분하여 유형화하고, 유형화된 오류들을 탐색하기 위해 자동오류탐색 프로그램과 전산부호검사 프로그램을 개발하였으며, 순수육안탐색방법을 체계화하여 오류탐색방법에 따라 탐색 가능한 오류들을 범주화하였다. 수치지도제작 개선모형을 구현하기 위해 연구한 결과, 수치지도 제작과정에서 발생할 수 있는 각종 오류들이 체계적으로 탐색됨으로써, 수치지도 제작 공정별로 오류가 감소된 수치지도 자료기반의 구축이 가능하게 되었으며, 수치지도 자료기반의 오류가 최소화되어 품질이 향상됨을 확인할 수 있었다.

• 한국과학교육학회지
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• 제27권9호
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• pp.778-786
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• 2007

이 연구에서는 비유를 사용한 화학 개념 학습에서 대응 오류 분석 활동의 효과를 개념 이해도,대응 관계 이해도,수업에 대한 인식 측면에서 조사하였다. 2개 중학교의 1학년 121명을 비교 집단과 처치 집단으로 배치한 후,'물질의 상태와 분자 배열'에 대하여 수업을 실시하였다. 비교 집단에서는 TWA 모형에 기초한 비유 수업을 하였고,처치 집단에서는 TWA 모형의 '유사성 대응' 및 '차이점 지적'을 '대응 오류 분석 활동'으로 대체한 수업을 하였다. 연구 결과,학생들의 장의존성 장독립성에 관계없이 개념 이해도 검사와 대응 관계 이해도 검사에서 처치 집단의 점수가 비교 집단보다 높았으며,그 차이가 통계적으로 유의미하였다. 수업에 대한 인식 검사 결과에서는 대부분의 학생들이 비유를 사용하는 수업에 대해 긍정적으로 인식하였으나,처치 집단의 학생들은 대응 오류 분석 활동을 어려워하는 것으로 나타났다. 이에 대한 교육적 함의를 논의하였다.

• 한국정밀공학회지
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• 제18권6호
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• pp.87-92
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• 2001

An error analysis is very important for a precision machine to estimate its performances. This study proposes a new parallel device, cubic parallel manipulator. Errors of the proposed cubic parallel manipulator include upper and down universal joint errors, due to the directional changes in the forces in the links, and actuation errors. An error analysis is presented based on an error model formed through the relation between the universal joint errors of the cubic parallel manipulator and the end effector accuracy. The analysis shows that the method can be used in predicting the accuracy of other cubic parallel devices.

• 한국정밀공학회지
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• 제19권5호
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• pp.64-71
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• 2002

A new model utilizing a transfer function was proposed in the previous paper fur analizing motion errors of hydrostatic tables. Validity of the proposed method was theoretically verified as the calculated motion errors were compared with the results by conventional multi pad method. In this paper, relationship between form error of rail and motion errors of hydrostatic table is analized theoretically in order to comprehand so-called ‘averaging effect of oil film’. Experiments on the motion errors of hydrostatic table is conducted with 3 different rails, and the results are compared with the results calculated by Transfer Function Method. The results show good agreement. From the results, it is verified that TFM is very effective to analize the motion errors of hydrostatic table.

• 소음진동
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• 제6권5호
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• pp.595-605
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• 1996

If the control force designed on the basis of the mathematical model with parameter errors is applied to control the actual system, the closed-loop performance of the actual system will be degraded depending on the degree of the errors, In this study, the effect of parameter errors on the robustness of several natural controls has been analyzed and compared. Every asymptoic stability condition for the natural controls has been derived using Lyapunov approach, and the characteristics of the stability conditions has also been compared. The extent of deviation of the closed-loop performance from the designed one for the natural controls is derived using operator techniques, and evaluated by numerical method. It has been found that the optimal control, acceleration feedback control, and acceleration-position feedback control among the considered natural controls would be robust one with respect to the parameter errors.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.34-39
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• 1993

Presented in this paper is a complete error covariance analysis for strapdown inertial navigation system(SDINS). We have found that in SDINS the cross-coupling terms in gyrocompass alignment errors can significantly influence the SDINS error propagation. Initial heading error has a close correlation with the east component of gyro bias erro, while initial level tilt errors are closely related to accelerometer bias errors. In addition, pseudo-state variables are introduced in covariance analysis for SDINS utilizing the characteristics of gyrocompass alignment errors. This approach simplifies the covariance analysis because it makes the initial error covariance matrix to a diagonal form. Thus a real implementation becomes easier. The approach is conformed by comparing the results for a simplified case with the covariance analysis obtained from the conventional SDINS error model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.454-458
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• 2001

A new model utilizing a transfer function was proposed in the previous paper for analizing motion errors of hydrostatic tables. Validity of the proposed method was theoretically verified as the calculated motion errors were compared with the results by conventional multi pad method. In this paper, relationship between form error of rail and motion errors of hydrostatic table is analized theoretically in order to comprehand so-called 'averaging effect of oil film'. Experiments on the motion errors of hydrostatic table is conducted with 3 different rails, and the results are compared with the results calculated by Transfer Function Method. The results show good agreement. From the results, it is verified that TFM is very effective to analize the motion errors of hydrostatic table.