• Journal of Power Electronics
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• 제1권2호
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• pp.117-126
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• 2001

A synchronous motor(SM) with q-axis special field winding of which the q-axis field-current compensates and cancels armature reaction can be driven at unity power factor under the conditions of transient state as well as steady state. The motor operates in high efficiency in all conditions. However, in order to obtain maximum performance of the motor, it is required that the time constant of armature circuit corresponds to that of q-axis field circuit. Inverse LQ(ILQ) design method on a basis of the pole assignment is suitable for this problem:(1) The time constants of the output responses can be designed for desired specifications, (2) Relations between feedback gains and response of closed loop system are very clear and (3) Optimal solutions can be given by simple procedure of ILQ method without solving the Ricaati's equation, compared to the usual LQ design method. Accordingly, the ILQ method can make the responses of armature current and q-axis field-current correspond. In this paper, it is proved by numerical simulations and experiments that the ILQ method is very effective for optimal regulator design of this plant and realizes a high-performance motor with unity power factor and high efficiency.

• Journal of the Korean Statistical Society
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• 제16권2호
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• pp.71-79
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• 1987

The linear and quadratic log contrast model with mixtures on the strictly positive simplex, $$ x_{q-1} = {(x_1, \cdots, x_q):\sum x_, = 1 and \delta \leq \frac{x_i}{x_j} \leq \frac{1}{\delta} for all i,j},$$ are considered. Using the invariance arguments, symmetric D-optimal designs are investigated. The class of symmetric D-optimal designs for the linear log contrasts model is given. Any D-optimal design for the quadratic log contrast model is shown to metric D-optimal designs for q=3 and 4 cases are given.

• 한국자기학회지
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• 제27권2호
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• pp.54-62
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• 2017

본 논문은 압축기 구동용 180 W급 매입형 영구자석 동기 전동기의 설계에 관하여 기술하였다. 먼저 전동기의 초기설계는 d-q 등가회로 모델을 이용한 해석기법을 이용하여 전동기 파라메타범위를 선정하고 이를 만족하는 초기형상을 도출하였다. 그리고, 전동기의 토크 리플을 저감하기 위해서 최적설계를 수행하였다. 최적설계는 실험계획법과 반응표면법을 이용하였으며, 끝으로 설계결과에 대한 타당성은 실험을 통해서 검증하였다.

• 전자공학회논문지CI
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• 제42권1호
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• pp.27-34
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• 2005

본 논문에서는 그래프 임베딩 문제와 관련된 이항트리에서의 Q-에지 번호매김 방법을 제안한다. 이러한 연구결과는 신뢰성이 높은 통신망을 설계하는 최적화 문제인 "n 개의 노드와 e 개의 에지를 가지면서 연결도가 최대인 그래프를 구성하라."를 해결한 Harary 그래프의 일반화인 원형군 그래프(circulant graph)의 점프열로 Q-에지번호들을 이용하면 연결도가 최대인 신뢰성이 높은 새로운 상호연결망(interconnection networks)의 위상을 설계할 수 있다. 그리고 이러한 위상은 이항트리를 스패닝 트리로 가지므로 최적방송이 가능하다.

• 한국공간구조학회논문집
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• 제23권2호
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• pp.29-36
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• 2023

Reinforcement learning (RL) is widely applied to various engineering fields. Especially, RL has shown successful performance for control problems, such as vehicles, robotics, and active structural control system. However, little research on application of RL to optimal structural design has conducted to date. In this study, the possibility of application of RL to structural design of reinforced concrete (RC) beam was investigated. The example of RC beam structural design problem introduced in previous study was used for comparative study. Deep q-network (DQN) is a famous RL algorithm presenting good performance in the discrete action space and thus it was used in this study. The action of DQN agent is required to represent design variables of RC beam. However, the number of design variables of RC beam is too many to represent by the action of conventional DQN. To solve this problem, multi-agent DQN was used in this study. For more effective reinforcement learning process, DDQN (Double Q-Learning) that is an advanced version of a conventional DQN was employed. The multi-agent of DDQN was trained for optimal structural design of RC beam to satisfy American Concrete Institute (318) without any hand-labeled dataset. Five agents of DDQN provides actions for beam with, beam depth, main rebar size, number of main rebar, and shear stirrup size, respectively. Five agents of DDQN were trained for 10,000 episodes and the performance of the multi-agent of DDQN was evaluated with 100 test design cases. This study shows that the multi-agent DDQN algorithm can provide successfully structural design results of RC beam.

• 대한기계학회논문집B
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• 제23권11호
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• pp.1390-1398
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• 1999

A numerical analysis for ROT sparger of PWR(Pressurized Water Reactor) is carried out. Computation is performed to investigate the flow characteristics as the change of design factor. As the result of this study, RDT sparger's flow resistance coefficient is K=3.53 at the present design condition if engineering mar&in is considered with 20%, and flow ratio into branch pipe is $Q_s/Q_i=0.41$. Velocity distribution at exit is not uniform because of separation in branch pipe. In the change of inlet flow rate and section area ratio of branch pipe for main pipe, flow resistance coefficient is increased as $Q_s/Q_i$ decreasing, but in the change of branch angle and outlet nozzle diameter of main pipe, flow resistance coefficient is decreased as $Q_s/Q_i$ decreasing. As the change rate of $Q_s/Q_i$ is the larger, the change rate of flow resistance coefficient is the larger. The change rate of pressure loss is the largest change as section area ratio changing. The optimal design condition of sparger is estimated as the outlet nozzle diameter ratio of main pipe is $D_s/D_i=0.333$, the section area ratio is $A_s/A_i=0.2$ and the branch angle is ${\alpha}=55^{\circ}$.

• 한국통신학회논문지
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• 제28권11C호
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• pp.1062-1069
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• 2003

본 논문에서는 요구된 성능을 만족시키는 강인한 최적 PID 제어기 설계를 위한 새로운 루프 형성 기법을 제안 하고자 한다. 설계하고자 하는 PID 제어기의 영점들을 플랜트의 최대 극점에 근접하도록 가중치 요소 Q와 R을 선택하면 루프 형상이 고주파수 영역의 센서잡음 장벽으로부터 최대한 멀어지게 된다. 2차 시스템에 대하여 강인한 최적 PTD 제어기 설계가 가능한 새로운 루프 형성 기법은 LQR 방법에서 발전되었다.

• 대한임베디드공학회논문지
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• 제11권3호
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• pp.153-162
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• 2016

This paper proposes an optimal dynamic resource allocation method in IoT (Internet of Things) parking guidance system using Q-learning resource allocation model. In the proposed method, a resource allocation using a forecasting model based on Q-learning is employed for optimal utilization of parking guidance system. To demonstrate efficiency and availability of the proposed method, it is verified by computer simulation and practical testbed. Through simulation results, this paper proves that the proposed method can enhance total throughput, decrease penalty fee issued by SLA (Service Level Agreement) and reduce response time with the dynamic number of users.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.67-70
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• 2002

This paper presents an optimal robust LQ-PID controller design method for a second order system with time-delay to meet design specifications. By LQR formulation of the second order system with time-delay, tuning parameters of PID controller are related by the weighting factors Q and R of cost function. The selection of the weighting factors Q and R are chosen to satisfy such the design specifications as overshoot and settling time.

• 대한전자공학회논문지
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• 제11권4호
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• pp.23-28
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• 1974

이심코일을 포함한 회로를 정밀하게 설계하는데 있어서 늘 골치거리가 되는 것은 실제의 코일의 Q가 주파수에 따라 변하는 사실을 어떻게 처리할 것인가 하는 것이다. 자심손실 자체가 주파수에 따라 복잡하게 변하기 때문에 일정한 직렬저항, 병렬커패시턴스를 부가한 종래의 등가회로는 이 경우 거의 유용성을 상실한다. 본논문에서는 우선 주어진 자심의 Q를 인덕턴스와 주파수의 함수로 표시하는 수학적 표시식을 가정하고 그것이 자심제조업자가 제공하는 또는 실험적으로 얻어지는 data에 가장 잘 들어맞도록 표시식의 퍼래미터들을 결정한다. 다음에 회로설계는 최적화방법을 쓰되 그 각 반복단계에서 요구되는 회로의 주파수응답의 정밀한 계산을 위에서 얻은 Q의 표시식을 이용하여 수행한다. 환언하면 본 논문에서 제시된 방법은 코일의 Q의 근사적 표시식과 최적화방법을 효과적으로 함께 사용한 것이며 이것으로서 상술한 실제적 코일에 부수된 난문제는 많이 해결되었다고 본다. 최적화방법으로서는 Fletcher-Powell 방법을 이용했으며 한가지 예제를 들어 본 논문에서 제시한 방법을 설명하였다.