• 대한전자공학회논문지TC
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• 제49권5호
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• pp.7-14
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• 2012

양자화된 빔포밍 시스템은 정확한 채널 상태 정보를 특정 벡터로 구성된 유한 집합, 즉 코드북으로 양자화하여 원하는 벡터에 대응되는 인덱스만을 송신단으로 피드백함으로써 피드백 오버헤드 및 지연 등에 의해 발생되는 영향을 최소화한다. 이와 관련하여 전역 (exhaustive) 및 그룹화 (group-based)를 이용한 탐색 기반의 인덱스 재배치 기법을 통해 추가적인 비트의 요구없이 피드백 에러에 의한 성능저하의 최소화 기법에 대한 연구가 수행되었다. 본 논문에서는 기존에 연구되었던 인덱스 재배치 기법에 코드북 내 벡터간의 chordal 거리에 따른 최적 코드북 설계기법 통해 적응적 특성을 갖는 개선된 그룹화 기반의 코드북 인덱스 배치 기법을 제안한다. Monte-Carlo 기반의 모의실험에 의해 제안하는 기법은 송신 안테나 수가 4이고 LTE 코드북을 이용할 경우 인덱스 재배치 기법을 사용하지 않을 때보다 동일한 비트 에러율을 얻기 위해 0.5~1dB 성능이 향상되며, 기존 그룹화 기반의 인덱스 배치 기법보다는 동일 환경에서 0.1~0.2dB 성능이 향상된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권8호
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• pp.2626-2646
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• 2014

This study presents a power and Physical Resource Blocks (PRBs) joint allocation algorithm to coordinate uplink (UL) interference in the device-to-device (D2D) underlaying Long Term Evolution-Advanced (LTE-A) networks. The objective is to find a mechanism to mitigate the UL interference between the two subsystems and maximize the weighted sum throughput as well. This optimization problem is formulated as a mixed integer nonlinear programming (MINLP) which is further decomposed into PRBs assignment and transmission power allocation. Specifically, the scenario of applying imperfect channel state information (CSI) is also taken into account in our study. Analysis reveals that the proposed PRBs allocation strategy is energy efficient and it suppresses the interference not only suffered by the LTE-A system but also to the D2D users. In another side, a low-complexity technique is proposed to obtain the optimal power allocation which resides in one of at most three feasible power vectors. Simulations show that the optimal power allocation combined with the proposed PRBs assignment achieves a higher weighted sum throughput as compared to traditional algorithms even when imperfect CSI is utilized.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1338-1341
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• 2004

In this paper, we have proposed a new approach of routing and wavelength assignment algorithms, called Possible Available Wavelength (PAW) algorithm. The weight of a link is used as the main factor for routing decision in PAW algorithm. The weight of a link is defined as a function of hop count and available wavelengths. This function includes a determination factor of the number of wavelengths that are being used currently and are supposed to be available after a certain time. The session requests from users will be routed on the links that has the greatest number of link weight by using Dijkstra's shortest path algorithm. This means that the selected lightpath will has the least hop count and the greatest number of possible available wavelengths. The impact of proposed link weight computing function on the blocking probability and link utilization is investigated by means of computer simulation and comparing with the traditional mechanism. The results show that the proposed PAW algorithm can achieve the better performance in terms of the blocking probability and link utilization.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2207-2213
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• 2010

본 논문에서는 FSM(finite-state machine)을 이용하여 차수 계산(degree computation)을 하지 않고 수정된 유클리드 알고리즘(modified Euclidean algorithm)을 구현할 수 있는 구조를 제안한다. 제안된 구조는 차수계산이 필요없기 때문에 RS(Reed-Solomon) 복호기의 하드웨어 복잡도를 줄일 수 있고, 고속의 복호기 설계가 가능하게 된다. 제안된 구조를 이용하는 RS(255,239) 복호기를 Verilog HDL로 구현하였고, 기존의 복호기에 비해 게이트 수를 약 13%정도 줄일 수 있다.

• Journal of Mechanical Science and Technology
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• 제20권7호
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• pp.981-992
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• 2006

In this paper, a lateral vehicle control using the concept of control configured vehicle (CCV) is presented. The control objectives for the lateral dynamics of a vehicle include the ability to follow a chosen variable without significant motion change in other specified variables. The analysis techniques for decoupling of the aircraft motions are utilized to develop vehicle lateral control with advanced mode. Vehicle lateral dynamic is determined to have the steering input and control torque input. The additional vehicle modes are also defined to using CCV concept. We use right eigenstructure assignment techniques and command generator tracker to design a control law for an lateral vehicle dynamics. The desired eigenvectors are chosen to achieve the desired decoupling (i.e., lateral direction speed and yaw rate). The command generator tracker is used to ensure steady-state tracking of the driver's command. Finally, the developed design is utilized by using the lateral vehicle dynamic with four wheel.

• 제어로봇시스템학회논문지
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• 제12권10호
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• pp.1002-1011
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• 2006

In this paper, a lateral vehicle control using the concept of control configured vehicle(CCV) is presented. The control objectives for the lateral dynamics of a vehicle include the ability to commend a chosen variable without significant motion change in other specified variables. The analysis techniques fur decoupling of the aircraft motions are utilized to develop vehicle lateral control with advanced mode. Vehicle lateral dynamic is determined to have the steering input and control torque input. The additional vehicle modes are also defined to using CCV concept. We use right eigenstructure assignment techniques and command generator tracker to design a control law for an lateral vehicle dynamics. The desired eigenvectors are chosen to achieve the desired decoupling(i.e., lateral direction speed and yaw rate). The command generator tracker is used to ensure steady-state tracking of the driver's command. Finally, the developed design is utilized by using the lateral vehicle dynamic with four wheel.

• 대한교통학회:학술대회논문집
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• 대한교통학회 2003년도 제43회 학술발표회논문집
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• pp.127-150
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• 2003

This research presents a novel application of static traffic assignment methods, but with a variable time value, for estimating the market share of a high-speed rail (HSR) in the NW-SE corridor of Korea which is currently served by the airline (AR), conventional rail (CR), and highway (HWY) modes. The proposed model employs the time-space network structure to capture the interrelations among all competing transportation modes, and to reflect their supply- and demand-sides constraints as well as interactions through properly formulated link-node structures. The embedded cost function for each network link offers the flexibility for incorporating all associated factors, such as travel time and fare, in the model computation, and enables the use of a distribution rather than a constant to represent the time-value variation among all transportation mode users. To realistically capture the tripmakers' value-of-time (VOT) along the target area, a novel method for VOT calibration has been developed with aggregate demand information and key system performance data from the target area. Under the assumption that intercity tripmakers often have nearly "perfect" travel information, one can solve the market share of each mode after operations of HSR for each O-D pair under the time-dependent demand with state-of-the-art traffic assignment. Aside from estimating new market share, this paper also investigated the impacts of HSR on other existing transportation modes.

• 한국정보처리학회논문지
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• 제1권1호
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• pp.38-49
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• 1994

기존 포트란 프로그램을 벡터 처리 가능한 코드인 벡트란으로 변환시키는데 있어 서 가장 문제가 되는 것은 루프내에서 제어의 분기가 발생하는 경우 조건적 전달이 일어난다는 것이다. 조건적 전단이란 어떤 문장의 실행이 다른 문장내의 변수 값에 의 해 이루어지는 제어 의존성으로, 본 논문은 루프내부의 조건적 제어를 제거하기 위한 알고리즘과 조건적 할당문을 이용하였을 때 그 내부의 복잡한 조건에 대한 단순화 알 고리즘을 제시한다. 이 때 조건적 할당문의 조건은 부울 변수(2-상태)뿐 아니라 3가지 이상의 상태를 나타내는 n-상태변수를 통하여 나타낸다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.3831-3851
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• 2015

This paper is concerned with the problem of joint resource allocation and user-pairing in virtual MIMO SC-FDMA systems to improve service quality of experience (QoE). No-reference logarithmic model is introduced to quantify service experience for each user and the objective is to maximize sum of all user's mean of score (MOS). We firstly formulate the optimal problem into an S-dimensional (S-D) assignment problem. Then, to solve this problem, the modified Lagrangian relaxation algorithm is deduced to obtain the suboptimal result of joint user-paring and subchannel allocation. The merits of this solution are as follows. First, the gap between its results and the global optimal one can be quantified and controlled by balancing the complexity and accuracy, which merit the other suboptimal algorithms do not have. Secondly, it has the polynomial computational complexity and the worst case complexity is O(3LN³), where L is the maximum iteration time and N is the number of subchannels. Simulations also prove that our proposed algorithm can effectively improve quality of experience and the gap between our proposed and the optimal algorithms can be controlled below 8%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권12호
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• pp.5800-5818
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• 2018

Interference may occur when several co-located wireless body area networks (WBANs) share the same channel simultaneously, which is compressed by resource scheduling generally. In this paper, a QoS-aware Adaptive Coloring (QAC) scheduling algorithm is proposed, which contains two components: interference sets determination and time slots assignment. The highlight of QAC is to determine the interference graph based on the relay scheme and adapted to the network QoS by multi-coloring approach. However, the frequent resource assignment brings in extra energy consumption and packet loss. Thus we come up with a launch condition for the QAC scheduling algorithm, that is if the interference duration is longer than a threshold predetermined, time slots rescheduling is activated. Furthermore, based on the relative distance and moving speed between WBANs, a prediction model for interference duration is proposed. The simulation results show that compared with the state-of-the-art approaches, the QAC scheduling algorithm has better performance in terms of network capacity, average delay and resource utility.