• ETRI Journal
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• 제44권6호
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• pp.925-935
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• 2022

In this study, we propose a limited feedback-based frequency divided group beamforming with sparse space-frequency transmit diversity coded orthogonal frequency division multiplexing (OFDM) system for ultrareliable low latency communication (URLLC) scenario. The proposed scheme has several advantages over the traditional hybrid beamforming approach, including not requiring downlink channel state information for baseband precoding, supporting distributed multipoint transmission structures for diversity, and reducing beam sweeping latency with little uplink overhead. These are all positive aspects of physical layer characteristics intended for URLLC. It is suggested in the system to manage the multipoint transmission structure realized by distributed panels using a power allocation method based on cooperative game theory. Link-level simulations demonstrate that the proposed scheme offers reliability by achieving both higher diversity order and array gain in a nonline-of-sight channel of selectivity and limited spatial scattering.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1994년도 춘계공동학술대회논문집; 창원대학교; 08월 09일 Apr. 1994
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• pp.144-144
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• 1994

• 한국통신학회논문지
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• 제32권3A호
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• pp.297-309
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• 2007

우리는 이동 애드 혹 네트워크에서 인터넷 프로토콜을 위한 세 가지의 주소 자동 설정 기법을 소개한다. RADA (Random ADdress Allocation)는 무작위로 IP 주소를 선택하는 방법이고, LiA (Linear Address Allocation)는 최대 IP 주소를 사용하여 순서대로 새로운 주소를 할당하는 방법이다. LiACR (Linear Address Allocation with Collision Resolution)이라고 칭하는 LiA의 확장된 방법은 제어 메시지의 오버헤드를 줄이는 방법을 사용하였다. 짧은 시간동안 다수의 노드들이 네트워크에 들어오게 되면 RADA는 LiA나 LiACR 보다 훨씬 빠르게 주소를 할당할 수 있다. 하지만 RADA는 주소 공간을 비효율적으로 사용하게 된다. 즉, RADA 는 특히 전장이나 위급 상황에서 긴급한 주소 설정이 필요할 경우 유용하다. 반면에 LiA나 LiACR은 네트워크 크기가 크고, 닫힌 형태이며, 관리 제어의 형태로 종속되는 이를테면, 무선 서비스 제공자에 의해 조정되는 애드 혹 네트워크에 더 적합하다.

• 한국인터넷방송통신학회논문지
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• 제18권4호
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• pp.183-189
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• 2018

최근 차량 무선통신 기술이 발달됨에 따라 차량과 클라우드 기술을 접목한 차량 클라우드(Vehicular Cloud)의 관심이 높아지고 있다. 기존 기법들은 이동성이 있는 V2V(Vehicle-to-Vehicle)와 V2I(Vehicle-to-infrastructure)의 차량 네트워크를 기반으로 데이터 수집을 하거나 중앙 서버와의 실시간 통신을 통한 클라우드 서비스에 집중하고 있다. 본 논문에서는 주차된 차량을 클라우드 형태로 그룹화 하여 데이터센터로 활용하기 위한 연구에 초점을 맞춘다. 먼저 주차 공간의 차량을 데이터센터의 자원으로 활용하는 차량 데이터센터 모델을 제시한다. 또한 차량 데이터센터 모델에서 각 차량의 이탈율을 고려한 예상 실행시간을 계산하고 이를 활용하는 자원 선택 기법을 제안한다. 시뮬레이션을 통해 예상 실행시간 관점에서 제안된 자원 선택 기법이 기존 기법에 비해 더 향상됨을 보인다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2300-2305
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• 2011

A Train control system is intended to assure train operation safety and to improve train operation efficiency. To perform these missions, the Train Control System consists of train safety space control part, train route control part and train operation management part. Train control technology changed from track circuit based to wireless based. And Wireless based train control technologies were developed by some railway signaling companies in Korea. To commercialize these control technologies, the development project is carried now. This project did analyze system requirements, and made the system development specification. Now this project finished system functions allocation, which will be performed by some subsystem. This paper describes roles of each function and the allocation of these functions to each subsystem.

• Industrial Engineering and Management Systems
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• 제13권4호
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• pp.408-413
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• 2014

The QWERTY type keyboard is a classical device that has been used for computers for a long time. The keyboard design of mobile devices like smartphones is an important issue to consider because of the limited space on the touch screen. This paper presents a design for symbol allocation on the QWERTY type soft keyboard. A 27-cell model, including the full stop (.), is proposed in this paper. A QWERTY type keyboard for smartphones is mainly known for its spatial compatibility, whereas the characters of the ANSI keyboard are allocated to the shoulder positions for functional auxiliary input methods such as the long pressing method.

• 한국경영과학회지
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• 제34권4호
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• pp.43-56
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• 2009

In korean peninsular, aircraft defense with SAM (Surface-to-Air Missile) is very important because of short range of combat space in depth. Effective and successful defense operation largely depends on two factors, SAM's location and the number of SAM for each target based on missile's availability in each SAM's location. However, most previous papers have handled only the former. In this paper, we developed Set covering model which can handle both factors simultaneously and Multi-heuristic algorithm for solving allocation problem of the batteries and missile assignment problem in each battery. Genetic algorithm is used to decide optimal location of the batteries. To determine the number of SAM, a heuristic algorithm is applied for solving missile assignment problem. If the proposed model is applied to allocation of SAM, it will improve the effectiveness of air defense operations.

• 동아시아식생활학회지
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• 제18권3호
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• pp.405-414
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• 2008

The purpose of this study was to understand the relationship between a chef's physical pain complaints and occupational circumstances. Cause-and-effect analysis of employees whose work was related to cooking was analyzed in relation to, - factor of cooking circumstances (kitchen condition, cooking operation, cooking allocation and distance of movement, cooking facilities) in order to ascertain possible links to physical pain. Cooking operations appeared to causes pain, especially in neck, shoulders, and legs. Cooking allocation and distance of movement, affected backache, eye-tiredness, and change of body-weight. Cooking space and facilities was related to, pain in waist, neck, shoulders, legs, arms, wrists, and back. Because cooking operations require extended concentrations and intensive effort, inappropriate occupational circumstances can lead to employees who usually suffer from accumulated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.4835-4855
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• 2015

TV white space (TVWS) is showing promise to become the first widespread practical application of cognitive technology. In fact, regulators worldwide are beginning to allow access to the TV band for secondary users, on the provision that they access the geolocation database. Device-to-device (D2D) can improve the spectrum efficiency, but large-scale D2D communications that underlie TVWS may generate undesirable interference to TV receivers and cause severe mutual interference. In this paper, we use an established geolocation database to investigate the power allocation problem, in order to maximize the total sum throughput of D2D links in TVWS while guaranteeing the quality-of-service (QoS) requirement for both D2D links and TV receivers. Firstly, we formulate an optimization problem based on the system model, which is nonconvex and intractable. Secondly, we use an effective approach to convert the original problem into a series of convex problems and we solve these problems using interior point methods that have polynomial computational complexity. Additionally, we propose an iterative algorithm based on the barrier method to locate the optimal solution. Simulation results show that the proposed algorithm has strong performance with high approximation accuracy for both small and large dimensional problems, and it is superior to both the active set algorithm and genetic algorithm.

• 대한산업공학회지
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• 제40권5호
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• pp.481-491
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• 2014

In this paper, we discussed a problem for improving the throughput of a crankshaft manufacturing line in an automotive factory in which the budget for purchasing new machines and installing additional buffers is limited. We also considered the constraint of available space for both of machine and buffer. Although this problem seems like a kind of buffer allocation problem, it is different from buffer allocation problem because additional machines are also considered. Thus, it is not easy to calculate the throughput by mathematical model, and therefore simulation model was developed using $ARENA^{(R)}$ for estimating throughput. To determine the investment plan, a modified Arrow Assignment Rule under some constraints was suggested and it was applied to the real case.