• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.13-16
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• 2005

It would be desirable to have methods for specific problems, which have low communication costs compared to the computation costs, and in specific applications, algorithms need to be developed and mapped onto parallel computer architectures. Main memory access for shared memory system or global communication in message passing system deteriorate the computation speed. In this paper, it is found that the m-step generalization of the block Lanczos method enhances parallel properties by forming m simultaneous search direction vector blocks. QR factorization, which lowers the speed on parallel computers, is not necessary in the m-step block Lanczos method. The m-step method has the minimized synchronization points, which resulted in the minimized global communications compared to the standard methods.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1144-1149
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• 2008

Converting technology has developed to print information for the decades. Recently, this technology (like gravure, gravure-offset) is rising as an alternative way for mass production of printed electronics such as RFID, solar cell. For the width of printing line is under 10 microns, registration error should be minimized less than several microns. Tension disturbance is main cause of registration error and this should be minimized before the substrate is transported into printing zone. With PI controller, it is possible to suppress the disturbance within 2% of operating tension. But register error appears more than 10 micron using PIcontroller considering noise. So LQG controller is needed as an alternative control method. In this paper, the comparision of PI and LQG controller in the converting machine including measured noise and tension disturbance is presented. It is shown that the LQG controller is more suitable for precision tension control in printed electronics.

• 한국산업정보학회논문지
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• 제11권5호
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• pp.163-169
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• 2006

In order to use parallel computers in specific applications, algorithms need to be developed and mapped onto parallel computer architectures. Main memory access for shared memory system or global communication in message passing system deteriorate the computation speed. In this paper, it is found that the m-step generalization of the block Lanczos method enhances parallel properties by forming in simultaneous search direction vector blocks. QR factorization, which lowers the speed on parallel computers, is not necessary in the m-step block Lanczos method. The m-step method has the minimized synchronization points, which resulted in the minimized global communications and main memory access compared to the standard methods.

• 한국산업융합학회 논문집
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• 제22권1호
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• pp.29-37
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• 2019

A new permanent magnet biased hybrid maglev actuator is developed. Compared to the classical hybrid maglev actuators, the new maglev has unique flux paths such that bias fluxes are separated with control flux paths. The control flux paths have minimum reluctances only developed by air gaps, so the currents to produce control fluxes can be minimized. The consumed power to operate this maglev system can also be minimized. The gravity load can be compensated with the static magnetic forces developed by the permanent magnet bias fluxes while external disturbances are controlled with the bidirectional AC magnetic forces developed by control fluxes by currents. 1-D circuit model is developed for this model such that the flux densities and magnetic forces are extensively analyzed. 3-D finite element model is also developed to analyze the performances of the maglev actuator.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2360-2366
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• 2011

무인차량의 주행은 각종 센서를 이용한 차량제어시스템, 항법시스템, 장애물시스템, 통합시스템의 4가지 서브 시스템으로 구성 되어있다. 본 연구는 비접촉 거리측정 장치인 레이저스캐너를 이용하여 무인차량의 평행주차 및 직각주차 알고리즘 개발을 목적으로 하였다. 이 알고리즘을 검증하기 위하여 GPS와 차량에 6대의 레이저스캐너를 장착하여 이용하였고, 레이저스캐너를 이용한 위치 계산의 오차를 줄이기 위해 타이어 미끄러짐을 최소로 할 수 있도록 5km/h로 차량의 이동 속도를 제한하였다.

• 한국통신학회논문지
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• 제32권10C호
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• pp.1042-1050
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• 2007

본 논문은 머신 기술 언어를 이용하여 전력 소모가 최소화된 임베디드 코어 자동 생성 시스템의 설계에 대해 기술한다. 머신 기술 언어를 사용하여 어플리케이션에 적합한 임베디드 코어를 빠른 시간에 설계하기 위해 어플리케이션 실행시 동적 전력 소모가 최소화된 코어를 생성하는 시스템을 구축하였다. 제안된 시스템은 각 인스트럭션의 파이프라인 스테이지의 행위 정보로부터 파이프라인 해저드를 찾아내며 처리하는 능력을 가진 임베디드 코어를 생성한다. 생성된 코어는 파워 소모가 최소화되게 만들어져 있다. 자동 생성 시스템의 검증을 위해 ARM9, MIPS R3000에 대해 SMDL로 기술하고 전력 최적화 과정을 거쳐 HDL 코드를 자동 생성하였으며, 어플리케이션에 대해 시뮬레이션을 수행하여 소모되는 전력을 측정하였다. 실험 결과로 생성된 프로세서는 정확한 동작을 수행하였고, 어플리케이션과 생성된 코어에 따라 동적 전력 소모가 $20%{\sim}40%$ 줄어드는 것을 확인하였다.

• 설비공학논문집
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• 제12권4호
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• pp.354-362
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• 2000

Optimal supervisory control strategy for the set points of controlled variables in the central cooling system has been studied by computer simulation. A quadratic linear regression equation for predicting the total cooling system power in terms of the controlled and uncontrolled variables was developed using simulated data collected under different values of controlled and uncontrolled variables. The optimal set temperatures such as supply air temperature, chilled water temperature, and condenser water temperature, are determined such that energy consumption is minimized as uncontrolled variables, load, ambient wet bulb temperature, and sensible heat ratio, are changed. The chilled water loop pump and cooling tower fan speeds are controlled by the PID controller such that the supply air and condenser water set temperatures reach the set points designated by the optimal supervisory controller. The influences of the controlled variables on the total system and component power consumption was determined. It is possible to minimize total energy consumption by selecting the optimal set temperatures through the trade-off among the component powers. The total system power is minimized at lower supply, higher chilled water, and lower condenser water set temperature conditions.

• 한국멀티미디어학회논문지
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• 제8권12호
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• pp.1589-1596
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• 2005

The imprecise real-time system provides flexibility in scheduling time-critical tasks. Most scheduling problems of satisfying both 0/1 constraint and timing constraints, while the total error is minimized, are NP complete when the optional tasks have arbitrary processing times. Liu suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on uniprocessors for minimizing the total error. Song et al suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on multiprocessors for minimizing the total error. But, these algorithms are all off-line algorithms. On the other hand, in the case of on line scheduling, Shih and Liu proposed the NORA algorithm which can find a schedule with the minimum total error for a task system consisting solely of on-line tasks that are ready upon arrival. But, for the task system with 0/1 constraint, it has not been known whether the NORA algorithm can be optimal or not in the sense that it guarantees all mandatory tasks are completed by their deadlines and the total error is minimized. So, this paper suggests an optimal algorithm to search minimum total error for the imprecise on-line real-time task system with 0/1 constraint. Furthermore, the proposed algorithm has the same complexity, O(N log N), as the NORA algorithm, where N is the number of tasks.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2001년도 종합학술발표회 논문집 Vol.11 No.1
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• pp.34-38
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• 2001

This paper proposes a CP-OFDM(Orthogonal Frequency Division Multiplexing using Circular Polarization) system for improving the system performance. The circular polarization has a characteristic that it cannot receive the reflected waves which are reflected by odd times. By reducing the influences of the reflected waves, the circular polarization can reduce the time delay spread and the inter-channel interference. The guard interval needed for the OFDM frame can be minimized and the orthogonality between subchannels can be improved by using circular polarization. Therefore the proposed CP-OFDM system can improve the system performance as well as the spectrum efficiency. Both theoretical analysis and system simulation results are described.

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2006년도 추계 학술대회
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• pp.309-314
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• 2006

The linear Consecutive-k-out-of-n:F system consists of n component ordered linearly and fail if and only if at least k consecutive components fail. We assume that the components are independent and identical exponentially distributed. This paper develops a model to calculate the expected cost per unit time of a linear consecutive-k-out-of-n:F system. The optimization problem we consider regards the choice of the system structure parameter k to minimized the expected cost per unit time.