• 산업공학
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• 제12권4호
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• pp.586-594
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• 1999

This paper introduces a production scheduling system for the block assembly shop in a shipbuilding company. We are to make a schedule for the assembly shop and related subassembly production shop. The objectives of the scheduling system are balancing of the workload of the subassembly shops as well as the assembly shop. There are a number of technological and resource constraints including assembly space restriction which is most important and critical resource in the shop. It is very hard and time consuming to consider the two problems, the workload balancing and the spatial allocation problem, simultaneously, and hence, we analyze the two problems independently. The first problem has already been introduced(고시근, 1996), and the overall appearance of the system and the spatial allocation algorithm are presented in this paper.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2005년도 공동추계학술대회
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• pp.442-450
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• 2005

One of the important tactical problems for the efficient operation of container terminals is to determine the usage of storage space There are two different strategies for stacking containers; mixing strategy. in which outbound containers and inbound containers are mixed in the same block. and segregating strategy, in which outbound containers and inbound containers are stacked in blocks different from each other. The performance of space allocation strategies also depends on the types of handling equipment in the yard and the number of handling equipment allocated to each block. A simulation model is developed considering various handling characteristics of yard cranes. Performances of various space and equipment allocation strategies are evaluated by using the simulation model.

• 한국컴퓨터정보학회논문지
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• 제21권2호
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• pp.1-7
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• 2016

In this paper, we propose in this paper present a novel locality data allocation policy as COLD(Correlated Locality Data) allocation policy. COLD is defined as a set of data that will be updated together later. By distributing a COLD into a NAND block separately, it can preserve th locality. In addition, by handling multiple COLD simultaneously, it can obtain the parallelism among NAND chips. We perform two experiment to demonstrate the effectiveness of the COLD data allocation policy. First, we implement COLD detector, and then, analyze a well-known workload. And we confirm the amount of COLD found depending on the size of data constituting the COLD. Secondly, we compared the traditional page-level mapping policy and COLD for garbage collection overhead in actual development board Cosmos OpenSSD. Experimental results have shown that COLD data allocation policy is significantly reduces the garbage collection overhead. Also, we confirmed that garbage collection overhead vary depending on the COLD size.

• Journal of Communications and Networks
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• 제18권3호
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• pp.420-428
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• 2016

In this paper, we investigate the scheduling and power allocation for coordinated multi-point transmission in downlink long term evolution advanced (LTE-A) systems, where orthogonal frequency division multiple-access is used. The proposed scheme jointly optimizes user selection, power allocation, and modulation and coding scheme (MCS) selection to maximize the weighted sum throughput with fairness consideration. Considering practical constraints in LTE-A systems, the MCSs for the resource blocks assigned to the same user need to be the same. Since the optimization problem is a combinatorial and non-convex one with high complexity, a low-complexity algorithm is proposed by separating the user selection and power allocation into two subproblems. To further simplify the optimization problem for power allocation, the instantaneous signal-to-interference-plus-noise ratio (SINR) and the average SINR are adopted to allocate power in a single cell and multiple coordinated cells, respectively. Simulation results show that the proposed scheme can improve the average system throughput and the cell-edge user throughput significantly compared with the existing schemes with limited feedback.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.258-262
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• 2009

In this paper, we propose an effective memory reduction algorithm to reduce the amount of reference frame buffer and memory bandwidth in video encoder and decoder. In general video codecs, decoded previous frames should be stored and referred to reduce temporal redundancy. Recently, reference frames are recompressed for memory efficiency and bandwidth reduction between a main processor and external memory. However, these algorithms could hurt coding efficiency. Several algorithms have been proposed to reduce the amount of reference memory with minimum quality degradation. They still suffer from quality degradation with fixed-bit allocation. In this paper, we propose an adaptive block-based min-max quantization that considers local characteristics of image. In the proposed algorithm, basic process unit is $8{\times}8$ for memory alignment and apply an adaptive quantization to each $4{\times}4$ block for minimizing quality degradation. We found that the proposed algorithm could improve approximately 37.5% in coding efficiency, compared with an existing memory reduction algorithm, at the same memory reduction rate.

• 대한전자공학회논문지
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• 제22권6호
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• pp.41-45
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• 1985

영상 변환부호화에 있어 블록양자화방식은 전체시스템의성능을 결정한다. 본 노문에서는 변환계수들의 분산치를 아는 경우와 거의 같은 성능을 갖는 양자화방법이 연구되었다. 연구된 방법은 비트배정(bit allocation) 및 분산치 추정을 양자화기에서의 분산치부정합 영향이 되도록 작아지게한 것이다. 그 성능은 변환계수의 확률밀도를 몇가지로 가정하여 컴푸터 시뮬레이션을 통해 확인되었다. 그 결과 대칭형 최적 비균등양자화기 및 최적 균등양자화ㅏ기 및 최적 균등양자화기의 경우 종래의 방법에 비해 NMSE면에서 야25%의 개선을 얻을 수 있었고 이 때의 부호화율은 약 1bit/pel 이었으며 사용된 변화능 DCT(diserete cosine transform)이었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권1호
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• pp.162-174
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• 2014

Most shipbuilding scheduling research so far has focused on the load level on the dock plan. This is because the dock is the least extendable resource in shipyards, and its overloading is difficult to resolve. However, once dock scheduling is completed, making a plan that makes the best use of the rest of the resources in the shipyard to minimize any additional cost is also important. Block assignment planning is one of the midterm planning tasks; it assigns a block to the facility (factory/shop or surface plate) that will actually manufacture the block according to the block characteristics and current situation of the facility. It is one of the most heavily loaded midterm planning tasks and is carried out manually by experienced workers. In this study, a method of representing the block assignment rules using a diagram was suggested through analysis of the existing manual process. A block allocation program was developed which automated the block assignment process according to the rules represented by the diagram. The planning scenario was validated through a case study that compared the manual assignment and two automated block assignment results.

• 디지털콘텐츠학회 논문지
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• 제18권1호
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• pp.63-70
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• 2017

최근 소셜 리딩과 같이 사용자 피드백이 활발해지면서 사용자 피드백 기반 전자책 콘텐츠를 제작에 대한 요구가 증가하였다. 그러나 사용자 피드백을 전자책에 반영하기 위해서는 직접코딩을 해야 하므로 코딩을 못하는 저자에게는 어려움이 있었다. 본 연구는 이러한 문제점을 해결하기 위한 블록 조립식 피드백 에디터 시스템을 개발하였다. 에디터는 입력 처리 출력모듈을 직접코딩으로 구현하였던 사용자 피드백을 영역지정, 컴포넌트 배치, 블록 편집 및 코드 생성 삽입 기능으로 반영할 수 있다. 본 시스템은 HTML, 자바스크립트, PHP, Codeigniter를 이용하여 구현하였다. 블록 편집 기능은 오픈 소스인 Blockly를 이용하여 블록을 제공, 조립할 수 있도록 하였다. 코드 생성 및 삽입 기능은 라이브러리 함수 코드를 삽입한다. 본 시스템을 통해 코딩을 못하는 일반 저자도 코딩 없이 쉽게 사용자 피드백 반영이 가능하도록 한다.

• 한국통신학회논문지
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• 제34권12A호
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• pp.1006-1013
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• 2009

본 논문에서는 블록 대각화 기법을 사용하는 다중 사용자 MIMO (Multiple-Input Multiple-Output) 하향링크 채널 환경에서 모든 사용자의 성능을 동일하게 보장하기 위하여 데이터 스트림의 수를 할당하는 기법을 제안한다. 기존의 연구들은 전체 채널 용량의 최대화에 중점을 두고 있고, 각 사용자의 채널 환경에 따라서 채널 용량이 불균등하게 분배되어 사용자 간의 차이가 크다. 뿐만 아니라, water-filling 기법을 사용하여 전력을 제어함으로써, 채널 이득이 작은 사용자는 매우 작은 채널 용량만을 가질 수 있었다. 또한, 대부분의 연구에서는 모든 사용자에 대해 동일한 수의 데이터 스트림을 사용함으로써, 스스로 데이터 스트림의 분배에 의한 추가적인 이득을 제한했다. 본 논문에서는 사용자 채널의 크기에 따라 데이터 스트림을 분배하여 모든 사용자에게 균등한 채널 용량을 보장하는 조건에서 이를 최대화하는 기법을 제안하고 모의실험을 통하여 제안된 기법이 기존의 기법에 비해 송신전력과 채널 용량의 이득이 더 큰 것을 확인한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권1호
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• pp.20-39
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• 2020

This paper considers a downlink multi-carrier cooperative non-orthogonal multiple access (NOMA) transmission, where no direct link exists between the far user and the base station (BS), and the communication between them only relies on the assist of the near user. Firstly, the BS sends a superimposed signal of the far and the near user to the near user, and then the near user adopts simultaneous wireless information and power transfer (SWIPT) to split the received superimposed signal into two portions for energy harvesting and information decoding respectively. Afterwards, the near user forwards the signal of the far user by utilizing the harvested energy. A minimum data is required to ensure the quality of service (QoS) of the far user. We jointly optimize power allocation, subcarrier allocation, time allocation, the power allocation (PA) coefficient and the power splitting (PS) ratio to maximize the number of data bits received at the near user under the energy causality constraint, the minimum data constraint and the transmission power constraint. The block-coordinate descent method and the Lagrange duality method are used to obtain a suboptimal solution of this optimization problem. In the final simulation results, the superiority of the proposed NOMA scheme is confirmed compared with the benchmark NOMA schemes and the orthogonal multiple access (OMA) scheme.