• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.113-116
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• 2007

본 논문은 인간의 보행에 대한 에너지 분석을 통해 biped robot의 설계 단계에서 최적의 보행제어인자를 추출하기 위한 연구이다. 에너지 효율이 높은 보행인자 값을 얻기 위해 인간의 보행영상을 획득하고, 획득된 영상을 5-link biped robot model로 근사화하여 dynamics와 energy를 분석한다. 또한 link의 길이 비율과 link의 무게, link의 관성의 변화를 통해 5-link로 근사화된 인간의 보행 효율과 기구적 요소 사이의 민감도를 판단할 수 있다. 인간과 자유도가 다른 biped robot이 인간과 같은 보행을 위하여 설계단계에서 고려되어야할 중요한 기구적 요소가 이러한 민감도를 통해 구해진다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.11a
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• pp.73-77
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• 1993

박막모델을 사용하여 연료전지 성능에 영향을 주는 여러 인자들에 대해 전압과 전류의 관계를 모사 하여 비교하였다. 또한 단위전지에 대해 제어루프를 구성함으로서 전극성능 모델식을 이용한 연료전지의 제어 가능성을 확인하였다. 확산계수가 증가할수록 그리고 전극두께가 얇고 전극의 세공반경이 클수록 전극성능은 증가하였다. 단위전지의 제어를 위해서 양극과 음극의 반응기체 유속을 조절할 수 있는 압력에 대해 설정치 변화와 외란의 변화에 대한 제어모사를 행한 결과 각 전극의 압력이 설정점에 빠르게 수령하여 연료전지의 효과적인 제어가 가능함을 검증하였다.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.213-216
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• 2000

퍼지제어기를 실제 플랜트에 적용할 경우, 모델링 오차와 플랜트에 대한 관련지식의 부족으로 만족할 만한 제어 결과를 기대하지 못한다. 이러한 경우 제어기 성능을 향상시키기 위해 제어인자를 다시 조정해야 하고, 이 조정과정은 시행착오방법으로 수행되기 때문에 많은 시간과 비용을 필요로 한다. 본 논문에서는 퍼지 논리를 사용하여 스케일링 계수를 자동조정하는 퍼지 레귤레이터를 제안하였다. 스케일 계수의 출력 범위와 오차, 오차 변화량 따라 퍼지 레귤레이터는 적절한 스케일링 계수값을 결정함으로써 퍼지제어기의 성능을 향상시키게 된다. 제안한 방법의 타당성을 확인하기 위해 2차 플랜트에 적용하여 모의실험을 수행하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2A
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• pp.121-127
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• 2010

In this paper, we propose a computationally efficient scheduling algorithm that can arbitrarily control the throughput-fairness tradeoff in a multiuser wireless communication environment. As a new scheduling criterion, we combine linearly two well-known scheduling criteria such as one of achieving the maximum sum throughput and the other of achieving the maximum fairness, so as to control the relative proportion of the throughput and the fairness according to a control factor. For linear combining two different criteria, their optimization directivenesses and the units should be unified first. To meet these requirements, we choose an instantaneous channel capacity as a scheduling criterion for maximizing the sum throughput and the average serving throughput for maximizing the fairness. Through a unified linear combining of two optimization objectives with the control factor, it can provide various throughput-fairness tradeoffs according to the control factors. For further simplification, we exploit a high signal-to-noise ratio (SNR) approximation of the instantaneous channel capacity. Through computer simulations, we evaluate the throughput and fairness performances of the proposed algorithm according to the control factors, assuming an independent Rayleigh fading multiuser channel. We also evaluate the proposed algorithm employing the high SNR approximation. From simulation results, we could see that the proposed algorithm can control arbitrarily the throughput-fairness performance between the performance of the scheduler aiming to the maximum sum throughput and that of the scheduler aiming to the maximum fairness, finally, we see that the high SNR approximation can give a satisfactory performance in this situation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.18-28
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• 1998

A laboratory experiment was made of a control of temperature oscillation in Czochralski convection. Numerical computation was also made to delineate the control of temperature oscillation. The suppression of temperature oscillation was achieved by varying the rotation rate of crystal rod ($\Omega=\Omega_0(1+A sin 2{\pi}ft/t_p)$), where A denotes the amplitude of rotation rate and f the frequency factor. Based on the inherent dimesionless time period of temperature oscillation ($t_p$), the suppression rate of temperature oscillation was characterized by the mixed convection parameter ($0.217{\leq}Ra/PrRe^2{\leq}1.658$). The optimal values of A and f were also scrutinized. To understand the suppression mechanism of temperature oscillation, the controls of isotherm($\theta$) and equi-vorticity($\omega$) were investigated.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.2
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• pp.28-37
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• 1999

Differentially Responsible Adaptive Critic Learning technique is proposed for learning the control technique with multiple control inputs as in robot system using reinforcement learning. The reinforcement learning is a self-learning technique which learns the control skill based on the critic information Learning is a after a long series of control actions. The Adaptive Critic Learning (ACL) is the representative reinforcement learning structure. The ACL maximizes the learning performance using the two learning modules called the action and the critic modules which exploit the external critic value obtained seldomly. Drawback of the ACL is the fact that application of the ACL is limited to the single input system. In the proposed Differentially Responsible Action Dependant Adaptive Critic learning structure, the critic function is constructed as a function of control input elements. The responsibility of the individual control action element is computed based on the partial derivative of the critic function in terms of each control action element. The proposed learning structure has been constructed with the CMAC neural networks and some simulations have been done upon the two dimensional Cart-Role system and robot squatting problem. The simulation results are included.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.5
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• pp.463-468
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• 2009

Torsional oscillations of the drivetrain in electric vehicles are generated under rapid driving conditions. These lead to an uncomfortable jerking of the vehicle and an increased stress of the mechanical components. To suppress torsional oscillations, the low pass and notch filters between the torque command from the acceleration pedal and electric motor input torque are suggested. The filter parameters are optimized based on Taguchi method with $L_{18}(3^5)$ orthogonal array. The signal to noise (S/N) ratio mainly depends on slew rate of motor input torque, damping ratio and natural frequency of notch filter. With the proposed suppression control scheme, the S/N ratio is shown to be increased by 4.7dB and the torque overshoot of the drive shaft is reduced to 30%.

• Progress in Medical Physics
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• v.2 no.1
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• pp.17-28
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• 1991

Generally, it is an accurate radiation measurement technique for processors fo thermoluminescent dosimenters(TLDs) to characterize each element they use by producing element correction factors(FCFs). TLDs are classified into three groups such as reference. control, and field TLDs. Reference TLDs are used only for the production of ECFs for the control and field TLDs. They are kept locked in a safe place except when it is necessary to use a subset of them to produce ECFs for the control and field TLDs. The ECF of a given element is a measure of the response of the element relative to the mean response of an arbitrarily selected group of reference elements. As TLDs are used in the field, their relative responses to radiation might be decreased due to muliple readings and physical abuse. Therefore, the producditon of ECFs are performed initially and periodically during the field use. This element correction method provides an excellent tool to examine new TLDs and to monitor the reliability of old TLDs. This paper discuss the 10 step procedures developed to produce and examine ECFs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1456-1463
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• 1999

This paper describes the measurement system of antenna factor using standard antenna method in OATS(Open Area Test Site) of KRISS(Korea Research Institute of Standards and Science) and methods for reducing an environmental noise affecting antenna factor. The range of measurement frequency is 30 - 1000 MHz, all control and data acquisition were done by computer automatically. Measurement results of antenna factors are presented, total uncertainty of antenna factor is $\pm$1 dB.

• Journal of Digital Convergence
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• v.10 no.2
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• pp.225-229
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• 2012

A reformer for a small fuel cell system is an apparatus which converts hydrocarbon fuel into hydrogen-rich gas. Among many indices of a reformer, the most crucial index of a reformer is CO concentration in the off-gas out of reformer which must be controled under 5ppm for the efficiency and performance of a system. This paper suggests the criteria of a reformer operation for the stability of a reformer in a fuel cell system by deducing crucial indices and improving processes. The six-sigma technique was applied to verify the optimum control and operation of a reformer of a fuel cell combined heat and power system. The result of temperature control of each parts of a reformer system is the concentration of CO which is the most important factor for the operation of a fuel cell system. The temperature of the parts of a reformer, MTS, LTS and Prox, were controled so that the concentration of CO.