• ETRI Journal
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• v.27 no.4
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• pp.341-354
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• 2005

The adaptation of video according to the heterogeneous and dynamic resource constraints on networks and devices, as well as on user preferences, is a promising approach for universal access and consumption of video content. For optimal adaptation that satisfies the constraints while maximizing the utility that results from the adapted video, it is necessary to devise a systematic way of selecting an appropriate adaptation operation among multiple feasible choices. This paper presents a general conceptual framework that allows the formulation of various adaptations as constrained optimization problems by modeling the relations among feasible adaptation operations, constraints, and utilities. In particular, we present the feasibility of the framework by applying it to a use case of rate adaptation of MPEG-4 video with an explicit modeling of adaptation employing a combination of frame dropping and discrete cosine transform coefficient dropping, constraint, utility, and their mapping relations. Furthermore, we provide a description tool that describes the adaptation-constraint-utility relations as a functional form referred to as a utility function, which has been accepted as a part of the terminal and network quality of service tool in MPEG-21 Digital Item Adaptation (DIA).

• International Journal of Control, Automation, and Systems
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• v.6 no.6
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• pp.845-858
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• 2008

In this paper, we consider a terminal, linear control system with delay, subject to unknown but bounded disturbances. For this system, we consider the problem of constructing a worst-case optimal feedback control policy, which can be corrected at fixed, intermediate time instants. The policy should guarantee that for all admissible uncertainties the system states are in prescribed neighborhoods of predefined system states, at all fixed, intermediate time instants, and in the neighborhood of a given state at a terminal time instant, and the value of the cost function is the best guaranteed value. Simple explicit rules(which can be easily implemented on-line) for constructing the optimal control policy in the original control problem are derived.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.3
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• pp.327-364
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• 2015

In this paper, a generalized guidance law with an arbitrary pair of guidance coefficients for impact angle control is proposed. Under the assumptions of a stationary target and a lag-free missile with constant speed, necessary conditions for the guidance coefficients to satisfy the required terminal constraints are obtained by deriving an explicit closed-form solution. Moreover, optimality of the generalized impact-angle control guidance law is discussed. By solving an inverse optimal control problem for the guidance law, it is found that the generalized guidance law can minimize a certain quadratic performance index. Finally, analytic solutions of the generalized guidance law for a first-order lag system are investigated. By solving a third-order linear time-varying ordinary differential equation, the blowing-up phenomenon of the guidance loop as the missile approaches the target is mathematically proved. Moreover, it is found that terminal misses due to the system lag are expressed in terms of the guidance coefficients, homing geometry, and the ratio of time-to-go to system time constant.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.1-7
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• 2023

TCP is considered a major candidate transport protocol even for constrained IoT networks due to its ability to integrate into the existing network infrastructures. Since TCP implementations such as uIP TCP often allow only a single TCP segment per connection to be unacknowledged at any given time due to resource constraints, the congestion control relies only on RTO management. In our previous work, to address the problem that uIP TCP performs poorly particularly when a radio duty cycling mechanism is enabled and the hidden terminal problem is severe, we proposed a RTO scheme for uIP TCP and validated the performance through Cooja simulation. In this study, we investigate the effect of other factors that were not considered in our previous work. More specifically, the effect of traffic intensity, the degree of the hidden terminal problem, and RDC is investigated by varying the offered load and the transmission range, and the RDC channel check rate. Simulation results imply that we need to further investigate how to improve TCP performance when the radio duty cycling mechanism is used.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.321-329
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• 2009

Due to the massive increase of data that should be managed, the problems in data quality management have been issued. In addition the lack of integrated management of the data causes duplication of data, low qualify services, and, missing data. To overcome these problems, this study attempts to examine the way of the data qualify management. To do this, metadata was defined, and its current management status in various view points was analyzed, and finally the metadata management was applied to the container terminal. for the "A" container terminal, we performed data standardization, and reflected major constraints and developed the pilot metadata repository. The contributions of this study are in improvement of the data qualify in the container terminal, and its practical application with metadata management method. Limitations of this study is its partial implementation of the metadata management to the company and interoperability of the metadata management for business to business data integration for the future research.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.83.4-83
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• 2002

$\bullet$ We present a state-feedback RHC for discrete-time TS fuzzy systems with input constriants. $\bullet$ The controller employ the current and one-step past information on the fuzzy weighting functions. $\bullet$ It is obtained from the finite horizon optimization problem with the invariant ellipsoid constraint $\bullet$ Under parameterized LMI conditions on the terminal weighting matrix $\bullet$ The closed-loop system stability is guaranteed. $\bullet$ The parameterized linear matrix inequalities are relaxed to a finite number of solvable LMIs.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.5
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• pp.567-573
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• 1998

본 논문에서는 입력과 상태변수에 hard constraint가 있는 이산시간 시스템에 대한 새로운 이동구간 제어기를 제안한다. 제안된 이동구간제어기가 terminal ellipsoid constraint를 이용하여 지수 안정성(exponential stability)을 보장함을 보인다. Feasibility를 증가시키기 위하여 시스템을 안정 모드와 불안정 모드로 바꾸는 방법, constraint를 완화하는 방법을 제안한다. Constraint를 완화할 때 constraint를 만족시키지 못하는 부분의 성능을 개선시키는 방법을 제안하고 예제를 통해서 몇 가지 제안한 방법들을 비교한다.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.5
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• pp.600-607
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• 1998

일반적인 비선형 동역학 최적화문제를 비선형 프로그래밍 문제로 변환하는데 제어변수들을 방사성 기본 함수로 근사화하는 방법이 사용되었다. 방사성 기본 함수의 계수들을 연속적으로 보정하기 위하여 최소수정기법에 기초를 둔 비선형 프로그래밍 알고리즘이 연구되었다. 이러한 알고리즘을 실제적인 다변수 제어 시스템에 적용하여 성능을 검증하였다.

• ETRI Journal
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• v.6 no.4
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• pp.31-36
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• 1984

This paper presents an efficient method for real power loss minimization and for improvements in voltage profiles. This method is accomplished by optimal control of reactive power in the system. The problem is formulated as an optimization problem, suitable for solution by linear programming technique. After establishing the objective function for minimizing the system losses with the help of linearised sensitivity relationships of control variables, i. e., the transformer tap position, generator terminal voltages and switchable reactive power sources. The linear programming technique is used to determine the optimal adjustments to the above variables, simultaneously satisfying the constraints. The proposed algorithm has been tested on a sample system and the result is presented and discussed.

• Annual Conference of KIPS
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• 2012.11a
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• pp.1344-1347
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• 2012

Mobile Cloud Computing services anywhere, anytime access to the Internet via a mobile terminal means to provide services, speakers are called Mobiloud. Computing processing power limitations of mobile devices, storage, due to space constraints, the tasks handled by mobile devices and data processing services to move to cloud environments. In recent years, smartphone, tablet PC and mobile device companies and individuals to spread and spread, and the content of the accelerating cloud painters, mobile cloud that can communicate with each other requires a standard service.