VOD 서비스를 위한 VBR MPEG 비디오 스트림의 대역폭 평활화

양정민(Jung-Min Yang),이재홍(Jae-Hong Lee),전병호(Byeong-Ho Jeon),김태균(Tae-Kyun Kim) 한국정보과학회 1997 한국정보과학회 학술발표논문집 Vol.24 No.2Ⅲ

본 연구에서는 주문형 비디오 서비스를 대상으로 대용량 저장 장치에 저장된 가변 비트율(VBR) 부호화 MPEG 비디오 데이터를 ATM망으로 전송하기 위한 대역폭 평활화 방안을 제안한다. 대역폭 평활화 알고리즘의 성능 평가를 위한 평가 인자들을 제시하고, 제안된 평활화 방안과 기존 방안을 비교 분석하였다. 성능 평가 인자별 비교 분석에 의해 제안된 방안이 간단한 알고리즘을 사용하고도 적절한 대역폭 변화 변위를 보여 주었으며, 특히 대역폭 변경 횟수를 대폭 줄일 수 있었다.

병렬 결합된 비동기 순차 머신을 위한 교정 제어

양정민(Jung-Min Yang) 대한전자공학회 2014 전자공학회논문지 Vol.51 No.8

이번 연구에서는 병렬 결합된 두 개의 비동기 순차 머신에 대한 교정 제어 문제를 다룬다. 각 비동기 머신은 동일한 외부입력을 받아 서로 독립적인 상태 천이 특성을 보인다. 본 논문에서는 한 개의 교정 제어기만을 이용하여 두 개의 비동기 머신의 폐루프 시스템 동작을 각각의 기준 모델의 동작과 일치시키도록 하는 제어 방법을 제안한다. 본 방법은 교정 제어기 두 개를 사용해야 하는 기존 방법에 비해 제어기 크기 및 계산량을 줄일 수 있다. 본 논문에서는 대상 비동기 머신이 입력/상태 유형이라고 설정하고 상태 피드백 교정 제어기가 존재할 조건과 설계 과정을 제시한다. 또 예제 시스템을 통하여 제안된 기법의 적용 과정을 기술한다. We address the problem of corrective control for two asynchronous sequential machines in parallel connection. Each asynchronous machine receives the same external input and shows independent state transition characteristics. We propose a novel control scheme in which only one corrective controller is employed so as to make the closed-loop system of each machine match the behavior of the corresponding reference model. Compared with the former method utilizing two corrective controllers, our scheme can reduce the controller size and computational load in controller design. We present the existence condition and design procedure for a state-feedback corrective controller under the assumption that the controlled machines are of input/state type. The design procedure for the proposed controller is described in an illustrative example.

입력 외란이 존재하는 비동기 순차 머신의 교정 제어 Ⅱ : 제어기 설계

楊正敏(Jung-Min Yang) 대한전기학회 2007 전기학회논문지 Vol.56 No.9

This paper presents the problem of controlling asynchronous sequential machines in the presence of input disturbances, which may be also regarded as an adversary in a game theoretic setting. The main objective is to provide necessary and sufficient condition for the existence of a corrective controller that solves model matching problem of an asynchronous machine suffering from input disturbance. The existence condition can be stated in terms of a simple comparison of two skeleton matrices. The proposed controller eliminates the adversarial effect of input disturbance and makes the controlled machine mimic the behavior of a model in stable-state way. Whenever controller exists, algorithms for their design are outlined and demonstrated in a case study.

입력 외란이 존재하는 비동기 순차 머신의 교정 제어 Ⅰ : 모델링

楊正敏(Jung-Min Yang) 대한전기학회 2007 전기학회논문지 Vol.56 No.9

This paper presents the problem of controlling asynchronous sequential machines in the presence of input disturbances, which may be also regarded as an adversary in a game theoretic setting. The main objective is to develope a new methodology for including unpredictable behavior of input disturbance into models of asynchronous machines. The input disturbance, representing uncontrollable noise input, is embedded into a new model of asynchronous machines in form of input/state finite state machines. It is shown that the proposed modeling preserves the fundamental model and well-pose of asynchronous machines. The reachability matrix, an important performance index of asynchronous machines, is also adapted according to input disturbance and will be used for constructing corrective controllers in the companion paper.

직렬 결합된 복합 비동기 순차 머신을 위한 모델 정합

양정민(Jung-Min Yang) 대한전자공학회 2013 전자공학회논문지 Vol.50 No.5

본 논문에서는 복합 비동기 순차 머신을 제어하는 방법을 다룬다. 논문에서 고려하는 비동기 머신은 입력/상태 머신 두 개가 직렬 결합된 것으로서 선행 머신의 출력 값이 후행 머신의 입력으로 전달된다. 제어 목적은 폐루프 시스템의 입력과 출력의 정상 상태 특성을 원하는 모델의 동작과 일치시키는 모델 정합 문제를 구현하는 교정 제어기를 꾸미는 일이다. 교정 제어기는 후행 머신의 상태 피드백 정보만 전달 받기 때문에 선행 머신의 상태를 정확하게 알 수 없는 불확실성이 존재한다. 본 논문에서는 그러한 불확실성 하에서 모델 정합 교정 제어기가 존재할 조건을 구하고 설계 알고리듬을 제안한다. 또한 사례 연구를 통해서 제안된 제어기의 설계 과정을 예시한다. In this paper, we study the problem of controlling composite asynchronous sequential machines. The considered asynchronous machine consists of two input/state machines in cascade connection, where the output of the front machine is delivered to the input channel of the rear machine. The objective is to design a corrective controller realizing model matching such that the stable state behavior of the closed-loop system matches that of a reference model. Since the controller receives the state feedback of the rear machine only, there exists uncertainty about the present state of the front machine. We specify the existence condition for a corrective controller given the uncertainty. The design procedure for the proposed controller is described in a case study.

산약(山藥)의 항산화 작용에 대한 단백질체 분석 연구

양정민 ( Jeong Min Yang ),이지형 ( Ji Hyung Lee ),성정석 ( Jung Suk Sung ),김동일 ( Dong Il Kim ) 대한한방부인과학회 2008 大韓韓方婦人科學會誌 Vol.21 No.2

에너지 안정여유도를 이용한 사족 보행 로봇의 내고장성 걸음새

楊正敏(Jung-Min Yang) 대한전기학회 2006 전기학회논문지 D Vol.55 No.7

This paper proposes a novel fault-tolerant gait for quadruped robots using energy stability margins. The previously developed fault-tolerant gaits for quadruped robots have a drawback of having marginal stability margin, which may lead to tumbling. In the process of tumbling, the potential energy of the center of gravity goes through a maximum. The larger the difference between the potential energy of the center of gravity of the initial position and that of this maximum, the less the robot tumbles. Hence this difference of potential energy, dubbed as Energy Stability Margin (ESM), can be regarded as the stability margin. In this paper, a novel fault-tolerant gait is presented which gives positive ESM to a quadruped robot suffering from a locked joint failure. Positive ESM is obtained by adjusting foot positions between leg swing sequences. The advantage of the proposed fault-tolerant gait is demonstrated in a case study where a quadruped robot with a failed leg walks on a even slope.

제어 불능 입력이 존재하는 비동기 순차 머신의 상태 피드백 제어 및 오류 카운터로의 응용

양정민(Jung-Min Yang),곽성우(Seong Woo Kwak) 제어로봇시스템학회 2009 제어·로봇·시스템학회 논문지 Vol.15 No.10

The model matching problem of asynchronous sequential machines is to design a corrective controller such that the stable-state behavior of the closed-loop system matches that of a prescribed model. In this paper, we address model matching when the external input set consists of controllable inputs and uncontrollable ones. Like in the frame of supervisory control of Discrete-Event Systems (DES), uncontrollable inputs cannot be disabled and must be transmitted to the plant without any change. We postulate necessary and sufficient conditions for the existence of a corrective controller that solves model matching despite the influence of uncontrollable events: Whenever a controller exists, the algorithm for its design is outlined. To illustrate the physical meaning of the proposed problem, the closed-loop system of an asynchronous machine with the proposed control scheme is implemented in VHDL code.

비동기 순차 머신의 강인한 상태 피드백 제어 및 VHDL 구현

양정민(Jung-Min Yang),곽성우(Seong Woo Kwak) 대한전기학회 2009 전기학회논문지 Vol.58 No.12

This paper proposes robust state feedback control of asynchronous sequential machines with model uncertainty. The considered asynchronous machine is deterministic, but its state transition function is partially known before executing a control process. The main objective is to derive the existence condition for a corrective controller for which the behavior of the closed-loop system can match a prescribed model in spite of uncertain transitions. The proposed control scheme also has learning ability. The controller perceives true state transitions as it undergoes corrective actions and reflects the learned knowledge in the next step. An adaptation is made such that the controller can have the minimum number of state transitions to realize a model matching procedure. To demonstrate control construction and execution, a VHDL and FPGA implementation of the proposed control scheme is presented.

고장 난 다리가 있는 사족 보행 로봇을 위한 최적 힘 배분

양정민(Jung-Min Yang) 대한전기학회 2009 전기학회논문지 Vol.58 No.3

The force distribution in multi-legged robots is a constrained, optimization problem. The solution to the problem is the set points of the leg contact forces for a particular system task. In this paper, an efficient and general formulation of the force distribution problem is developed using linear programming. The considered walking robot is a quadruped robot with a locked-joint failure, i.e., a joint of the failed leg is locked at a known place. For overcoming the drawback of marginal stability in fault-tolerant gaits, we define safety margin on friction constraints as the objective function to be maximized. Dynamic features of locked-joint failure are represented by equality and inequality constraints of linear programming. Unlike the former study, our result can be applied to various forms of walking such as crab and turning gaits. Simulation results show the validity of the proposed scheme.