• 제어로봇시스템학회논문지
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• 제4권4호
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• pp.487-493
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• 1998

Camera calibration is the process of determining the coordinate relationship between a camera image and its real world space. Accurate calibration of a camera is necessary for the applications that involve quantitative measurement of camera images. However, if the camera plane is parallel or near parallel to the calibration board on which 2 dimensional objects are defined(this is called "ill-conditioned"), existing solution procedures are not well applied. In this paper, we propose a neural network-based approach to camera calibration for 2D images formed by a mono-camera or a pair of cameras. Multi-layer perceptrons are developed to transform the coordinates of each image point to the world coordinates. The validity of the approach is tested with data points which cover the whole 2D space concerned. Experimental results for both mono-camera and stereo-camera cases indicate that the proposed approach is comparable to Tsai's method［8］. Especially for the stereo camera case, the approach works better than the Tsai's method as the angle between the camera optical axis and the Z-axis increases. Therefore, we believe the approach could be an alternative solution procedure for the ill -conditioned camera calibration.libration.

• Structural Engineering and Mechanics
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• 제38권4호
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• pp.405-416
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• 2011

An efficient two-level domain decomposition parallel algorithm is suggested to solve large-DOF structural problems with nonlinear material models generating unsymmetric tangent matrices, such as a group of plastic-damage material models. The parallel version of the stabilized bi-conjugate gradient method is developed to solve unsymmetric coarse problems iteratively. In the present approach the coarse DOF system is solved parallelly on each processor rather than the whole system equation to minimize the data communication between processors, which is appropriate to maintain the computing performance on a non-supercomputer level cluster system. The performance test results show that the suggested algorithm provides scalability on computing performance and an efficient approach to solve large-DOF nonlinear structural problems on a cluster system.

• Structural Engineering and Mechanics
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• 제23권4호
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• pp.325-337
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• 2006

A hybrid structural design and optimization methodology that combines the strengths of genetic algorithms, local search techniques, and parallel computing is developed to evolve optimal truss systems in this research effort. The primary objective that is met in evolving near-optimal or optimal structural systems using this approach is the capability of satisfying user-defined design criteria while minimizing the computational time required. The application of genetic algorithms to the design and optimization of truss systems supports conceptual design by facilitating the exploration of new design alternatives. In addition, final shape optimization of the evolved designs is supported through the refinement of member sizes using local search techniques for further improvement. The use of the hybrid approach, therefore, enhances the overall process of structural design. Parallel computing is implemented to reduce the total computation time required to obtain near-optimal designs. The support of human-computer interaction during layout optimization and local optimization is also discussed since it assists in evolving optimal truss systems that better satisfy a user's design requirements and design preferences.

• 한국소음진동공학회논문집
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• 제15권9호
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• pp.1003-1008
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• 2005

The acoustic absorption of a multiple layer perforated plate system is very good near the resonance frequency region, while it has been regarded as a demerit that its frequency bandwidth is considerably narrow. In order to overcome such a demerit, the parallel perforated plates with different porosities are proposed. The sound absorption of such system composed of a parallel perforated plate is calculated by an equivalent electroatoustic circuit approach and validated by comparing the calculated absorption coefficients with those measured by the two-microphone impedance tube method. The sound absorptive characteristics and performance of parallel perforated plate systems are discussed from a standpoint of frequency bandwidth related with sound absorption.

• Journal of Korean Neurosurgical Society
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• 제58권3호
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• pp.236-241
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• 2015

Objective : We report on the technical feasibility and limitations of the transmanubrial approach for cervicothoracic junction (CTJ) lesions and emphasize the advantage of bisecting the upper part of the manubrium in an inverted Y-shape. Methods : Thirteen patients who underwent the fourteen transmanubrial approach for various CTJ lesions were enrolled during 2005-2014. For the evaluation of the accessibility for the CTJ lesion, we analyzed the two parallel line defined as a straight line parallel to the inferior and superior plateau of the upper and lower healthy vertebrae, the angle of the two parallel lines and the distance from the sternal notch to lines at the sternum on preoperative magnetic resonance images. Surgical limitations and perspectives, as well as postoperative clinical outcomes were evaluated retrospectively. Results : The CTJ lesions were six metastases, three primary bone tumors, two herniated discs, and one each of a traumatic dislocation with syrinx formation and tuberculous spondylitis and ossification of the posterior longitudinal ligament. If two parallel lines pass below the sternal notch, the manubriotomy should be inevitably performed. The mean preoperative Visual analogue scale score was 8 (range, 5-10), which improved to 4 (range, 0-6) postoperatively. Seven cases showed an increase in Frankel score postoperatively. Conclusion : The spatial relationship between the sternal notch and the two parallel lines to the lesion was rational to determine the feasibility of manubriotomy. The transmanubrial approach for CTJ lesions can achieve favorable clinical outcomes by providing direct decompression of lesion and effective reconstruction.

• Journal of Power Electronics
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• 제16권4호
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• pp.1245-1255
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• 2016

The single resonant inverter is widely employed in typical inductive power transfer (IPT) systems to generate a high-frequency current in the primary side. However, the power capacity of a single resonant inverter is limited by the constraints of power electronic devices and the relevant cost. Consequently, IPT systems fail to meet high-power application requirements, such as those in rail applications. Total harmonic distortion (THD) may also violate the standard electromagnetic interference requirements with phase shift control under light load conditions. A power regulation approach with selective harmonic elimination is proposed on the basis of a parallel multi-inverter to upgrade the power levels of IPT systems and suppress THD under light load conditions by changing the output voltage pulse width and phase shift angle among parallel multi-inverters. The validity of the proposed control approach is verified by using a 1,412.3 W prototype system, which achieves a maximum transfer efficiency of 90.602%. Output power levels can be dramatically improved with the same semiconductor capacity, and distortion can be effectively suppressed under various load conditions.

• 한국컴퓨터정보학회논문지
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• 제18권7호
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• pp.1-10
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• 2013

본 논문에서는 Thumb-2 명령어 집합 구조의 성능을 개선하기 위하여 분기 명령어와 사용 빈도가 높은 명령어를 동시에 실행하는 병렬 분기 명령어 집합을 제시한다. 제시된 기법에서는 16비트 분기 명령어와 사용 빈도가 높은 16비트 LOAD, ADD, MOV, STORE, SUB 명령어를 각각 결합하는 새로운 32비트 명령어를 도입한다. 새로운 명령어의 인코딩 공간을 제공하기 위해 사용 빈도가 낮은 기존 명령어의 레지스터 필드에 사용되는 비트 수를 줄이고 이를 통해 절약된 비트들을 이용하여 병렬 분기 명령어를 인코딩한다. 실험 결과, 제시된 방법은 코드 크기를 증가시키지 않고 전통적인 방식과 비교하여 평균 8.0%의 성능을 향상시킨다.

• 한국정보처리학회논문지
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• 제3권7호
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• pp.1680-1686
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• 1996

연역 데이타베이스가 병렬 컴퓨터 구조에 분할 적재될 때, 내포 술어에 대한 갱신이 결정적일 필요가 있으며, 이 결과를 이용한 내포 술어의 병렬 평가 알고리즘이 요구된 다. 본 논문에서는 병렬 연역 데이타베이스의 내포 술어에 대한 삽입과 삭제가 결정적 인 방법을 제안하고 병렬 영역 데이타베이스를 휘한 병렬 컴퓨터 구도에서 갱신 방 법이 고려된 확장된 병렬 평가 알고리즘을 제안한다. 연역 데이타베이스는 외연적 데이타베이스 즉 사실들의 집합과, 내포적 데이타베이스 즉 규칙들의 집합으로 구성된다. 이 집합들을 여러개의 처리기에 분산 적재 하였을 때, 각각의 처리기에서 갱신 방법과 그 결과를 이용한 병렬 평가방법을 연구한다. 각각의 처리기는 자신의 지역 기억장치를 가지며 연결망을 통하여 서로 메세지를 교환함으로써 통신한다.

• 예술인문사회 융합 멀티미디어 논문지
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• 제4권2호
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• pp.369-378
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• 2014

The Reed-Muller code is one of the efficient algorithms for multiple bit error correction, however, its high-computation requirement inherent in the decoding process prohibits its use in practical applications. To solve this problem, this paper proposes a graphics processing unit (GPU)-based parallel error control approach using Reed-Muller R(r, m) coding for real-time wireless communication systems. GPU offers a high-throughput parallel computing platform that can achieve the desired high-performance decoding by exploiting massive parallelism inherent in the algorithm. In addition, we compare the performance of the GPU-based approach with the equivalent sequential approach that runs on the traditional CPU. The experimental results indicate that the proposed GPU-based approach exceedingly outperforms the sequential approach in terms of execution time, yielding over 70× speedup.

• 한국전산응용수학회:학술대회논문집
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• 한국전산응용수학회 2003년도 KSCAM 학술발표회 프로그램 및 초록집
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• pp.15-15
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• 2003

We provide some recent results of approximation algorithms for solving Markov Games and discuss their applications to problems that arise in Computer Science. We consider a receding horizon approach as an approximate solution to two-person zero-sum Markov games with an infinite horizon discounted cost criterion. We present error bounds from the optimal equilibrium value of the game when both players take “correlated” receding horizon policies that are based on exact or approximate solutions of receding finite horizon subgames. Motivated by the worst-case optimal control of queueing systems by Altman, we then analyze error bounds when the minimizer plays the (approximate) receding horizon control and the maximizer plays the worst case policy. We give two heuristic examples of the approximate receding horizon control. We extend “parallel rollout” and “hindsight optimization” into the Markov game setting within the framework of the approximate receding horizon approach and analyze their performances. From the parallel rollout approach, the minimizing player seeks to combine dynamically multiple heuristic policies in a set to improve the performances of all of the heuristic policies simultaneously under the guess that the maximizing player has chosen a fixed worst-case policy. Given $\varepsilon$>0, we give the value of the receding horizon which guarantees that the parallel rollout policy with the horizon played by the minimizer “dominates” any heuristic policy in the set by $\varepsilon$, From the hindsight optimization approach, the minimizing player makes a decision based on his expected optimal hindsight performance over a finite horizon. We finally discuss practical implementations of the receding horizon approaches via simulation and applications.