• 한국정밀공학회지
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• 제12권12호
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• pp.165-172
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• 1995

Many algorithms to enhance a speed performance of a robot have been studied, but it's rare to consider disign aspect of a robot arm for time optimal problem. In this paper, section demensions of a robot arm and a velocity profile of an end-effector were optimally designed to minimize the cycle time. Capacity of actuators, deflections of end-effector, and a fundamental natural frequency of the robot arm were constrained in optimal design. For a given path with a trapezoidal velocity profile, torques of each joint were calculated using the inverse kinematics and dynamics. For the SCARA type robot which is mainly used for assembly tasks, the time optimal design of each robot arm id presented with the above constraints.

• 대한조선학회논문집
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• 제41권3호
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• pp.28-34
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• 2004

This paper presents the results of the structural analysis and optimal design of the ROV to be operated at 6000m depth in the ocean. This will be the first domestic deep-sea ROV operating with an AUV and a launcher equipped with robot arms and the current weight is about 3 ton. initial optimal dimension of the frame is determined based on the stress analysis using FEA code ANSYS and design sensitivity and optimization results. The current design is the initial design and there is a possibility to change the design according to the modification of material, equipments and array of structure.

• 한국기계가공학회지
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• 제16권6호
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• pp.109-116
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• 2017

In this study, the optimization of the overall dimensions of an automobile bumper was investigated through CAE and experiment using the Six Sigma method and design of experiment (DOE) method, respectively. Injection pressure, injection speed, injection time, cooling time, holding time, injection temperature, and holding pressure were selected as the vital parameters affecting the overall width of product through analysis of trivial many using CAE. The optimal values were determined using the DOE method, and we analyzed the improvement by applying the optimal conditions to the production process. As a result, the mean value of the overall width was close to the target value, with a deviation of 0.05mm, and the processability and I-MR control were remarkably improved. Finally, the dimension pass rate of the product improved by 20%.

• 한국산업융합학회 논문집
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• 제25권3호
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• pp.357-363
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• 2022

In this study, in order to develop an non-slip metal grating, the stability of the grating according to the span of the grating and the gap and height of the bearing bar was evaluated. The optimal shape design of the grating was performed using the results of determining the stability of the grating. The purpose of this study is to determine the stability according to the spacing and height of the bearing bar by applying the design pressure at the design stage to develop the anti-skid grating, and to design the optimal shape for cost reduction. In the optimal design, the target variable was set as the mass, and the optimal design of the grating was performed based on about 20%. Regardless of the height of the bearing bar of the grating, the stress and deformation of the span and the grating showed a proportional tendency to each other, and it was found that the stress decreased as the height of the bearing bar increased. Based on the structural analysis results, an optimal design was performed using mass as the objective variable, and the existing 2mm thickness was changed to 1.6mm, reducing the mass by about 19%. The stress increased by about 4.4% compared to the maximum stress of the existing grating, but the minimum safety factor was 3.1, indicating that the optimally designed grating was stable.

• 대한공간정보학회지
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• 제18권1호
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• pp.41-46
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• 2010

최신 다차원 공간정보기술은 대학 내의 수많은 시설들에 대한 효율적 시설물관리 지원업무, 사업비 예산편성 및 관리 등의 예산편성 의사결정지원업무, 그리고 입시홍보 등을 수행하는 자료로 그 중요성이 부각되고 있다. 따라서 본 연구에서는 대학의 시설물관리를 위한 다차원 공간정보를 구축하여 신규 건축예정인 건물에 대해 공간 활용을 극대화할 수 있는 최적의 입지를 선정하였으며, 대학 상징물 이전에 따른 적지분석, 외부 환경변화에 따른 경관분석 등을 수행하였다. 그 결과 시설물 계획.관리의 합리화로 인한 대학의 쾌적한 공간조성 및 체계적 종합발전과 예산편성 또는 집행 시의 의사결정지원 등으로 중복투자방지와 예산절감 등의 효과를 극대화할 수 있는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제15권6호
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• pp.669-683
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• 2003

The stochastic optimal nonlinear control of coupled adjacent building structures is studied based on the stochastic dynamical programming principle and the stochastic averaging method. The coupled structures with control devices under random seismic excitation are first condensed to form a reduced-order structural model for the control analysis. The stochastic averaging method is applied to the reduced model to yield stochastic differential equations for structural modal energies as controlled diffusion processes. Then a dynamical programming equation for the energy processes is established based on the stochastic dynamical programming principle, and solved to determine the optimal nonlinear control law. The seismic response mitigation of the coupled structures is achieved through the structural energy control and the dimension of the optimal control problem is reduced. The seismic excitation spectrum is taken into account according to the stochastic dynamical programming principle. Finally, the nonlinear controlled structural response is predicted by using the stochastic averaging method and compared with the uncontrolled structural response to evaluate the control efficacy. Numerical results are given to demonstrate the response mitigation capabilities of the proposed stochastic optimal control method for coupled adjacent building structures.

• 한국정보통신학회논문지
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• 제15권2호
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• pp.279-285
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• 2011

차세대 무선통신에서는 현재 서비스 되고 있는 성능보다 높은 BER(Bit Error Rate)의 성능을 요구한다. 기존의 DVB-RCS(Digital Video Broadcasting - Return Channel via Satellite)에서 사용중인 이진 터보 코드(Double binary Turbo code)는 높은 SNR(에서 오류마루 현상이 발생하여 차세대 무선통신에서 사용하기가 어려움이 있다. 따라서 본 논문에서는 DVB-RCS NG에 적합한 부호화 방식으로 3D-터보 코드(Tthird-dimension Turbo code)의 부복호화기의 구조를 분석하고 성능분석 하였다. 3D-터보 코드는 기존의 DVB-RCS 방식에 rate-1인 post-encoder를 첨가시켜 오류마루 현상을 보완한 부호화기이다. 3D-터보 코드는 post-encoder의 형태, 인터리빙 기법, ${\lambda}$값의 변화에 따라 성능이 달라지므로 본 논문에서는 각 파라메타에 대한 최적의 값을 제시하였다. 전체적으로 3D-터보 코드가 기존의 DVB-RCS 터보 코드에 비해 성능이 우수하고 기존의 문제점인 오류마루 현상을 해결할 수 있음을 알 수 있다.

• International Journal of Computer Science & Network Security
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• 제22권11호
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• pp.331-337
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• 2022

Smart learning is augmented with digital, context-aware, and adaptable technologies to encourage students to learn better and faster. To ensure that digital learning is successful and that implementation is efficient, it is critical that the dimensions of digital learning are arranged correctly and that interactions between the various elements are merged in an efficient and optimal manner. This paper builds and discusses a basic framework for smart learning in the digital age, aimed to improve students' abilities and performance in learning. The proposed framework consists of five dimensions: Teacher, Technology, Learner, Digital content, and Evaluation. The Teacher and Learner dimensions operate on two levels: (a) an abstract level to fit in knowledge and skills or interpersonal characteristics and (b) a concrete level in the form of digital devices used by teachers and learners. Moreover, this paper proposes asynchronous online course delivery model. An Arabic smart learning platform has been developed, based on these smart learning core dimensions and the asynchronous online course delivery model, because despite the official status of this language in many countries, there is a lack of Arabic platforms to teach Arabic. Moreover, many non-native Arabic speakers around the world have expressed an interest in learning it. The Arabic digital platform consists of over 70 lessons classified into three competence levels: beginner, intermediate, and advanced, delivered by Arabic experts and Arabic linguists from various Arab countries. The five dimensions are described for the Arabic platform in this paper. Learner dimension is the Arabic and non-Arabic speakers, Teacher dimension is Arabic experts and Arabic linguistics, Technology dimension consists of technology for Arabic platform that includes web design, cloud computing, big data, etc. The digital contents dimension consists of web-based video, records, etc. The evaluation dimension consists of Teachers rating, comments, and surveys.

• 대한기계학회논문집A
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• 제30권11호
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• pp.1479-1485
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• 2006

To minimize the leakage of microwave which can occur when one pulls the door of a microwave oven during its operation, shape optimization of the door frame is presented. A numerical optimization is implemented to minimize the dynamic twisting deformation of the door frame. Shape design variables are defined, which represent the dimension of the bead in the flange. Two optimal design problems are established to minimize the maximum twisting deformation from harmonic response analysis. The problems are solved, their results being compared and evaluated.

• 대한기계학회논문집
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• 제12권2호
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• pp.381-388
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• 1988

본 연구에서는 설계조건에 만족하는 정확한 지주높이를 얻기 위하여 엄밀해를 가진 현수곡선이론을 바탕으로 하여 설계변수들과의 관계를 유도 및 수식화 하였다. 이를 최적설계문제로 정의하여 필요한 제한조건을 만족시키는 범위 내에서 지주의 굴적각들을 최소로 줄이는 최적화지법을 도입하여 체계적인 설계방법을 제시 하였다. 해석에 관한 설계예의 모델을 선정하여 굴절각들을 비교.검토하고 실험을 통하여 확인하였다.