• 대한전자공학회논문지TC
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• 제42권9호
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• pp.57-64
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• 2005

블루투스는 마스터와 슬레이브 간에 피코넷을 구성하며, 피코넷 네부에서는 시분할 방법으로 통신을 하며 이러한 피코넷이 모여 스캐터넷을 구성한다. 블루투스의 통신은 주파수 홉핑을 사용하기 때문에 여러개의 피코넷이 존재하거나 많은 수의 장치가 연결될 경우에는 스캐터넷이 필요하다. 블루투스 기술규격에는 스캐터넷의 형성 방법에 대하여 구체적으로 정의하지 않고있다. 기존에 제안되고 있는 스캐터넷 형성알고리즘은 스캐터넷의 토폴로지가 트리형태가 되도록 구성한다. 그렇지만 기존의 방법은 트리를 구성함에 있어서 스캐터넷 통신의 기본단위가 피코넷이라는 블루투스 통신의 특성을 간과하고 있다. 본 논문에서는 스캐터넷을 이루고 있는 피코넷에서 효율적인 전송률을 보장할 수 있는 형태로 트리를 구성함으로써, 스캐터넷 전체의 평균 전송효율을 높이는 방법을 제안한다.

• Journal of Computational Design and Engineering
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• 제2권2호
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• pp.105-112
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• 2015

Product Lifecycle Management (PLM) ranges from design concepts of products to disposal. In this paper, we focus on the production planning phase in PLM, which is related to process planning and production scheduling and so on. In this study, key decisions for the creation of production plans are defined as production-planning attributes. Production-planning attributes correlate complexly in production-planning problems. Traditionally, the production-planning problem splits sub-problems based on experiences, because of the complexity. In addition, the orders in which to solve each sub-problem are determined by priorities between sub-problems. However, such approaches make solution space over-restricted and make it difficult to find a better solution. We have proposed a representation of combinations of alternatives in production-planning attributes by using Zero-Suppressed Binary Decision Diagrams. The ZDD represents only feasible combinations of alternatives that satisfy constraints in the production planning. Moreover, we have developed a solution search method that solves production-planning problems with ZDDs. In this paper, we propose an approach for managing solution candidates by ZDDs' network for addressing larger production-planning problems. The network can be created by linkages of ZDDs that express constraints in individual sub-problems and between sub-problems. The benefit of this approach is that it represents solution space, satisfying whole constraints in the production planning. This case study shows that the validity of the proposed approach.

• 가정과삶의질연구
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• 제21권2호
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• pp.117-130
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• 2003

This study was conducted to examine elderly users' satisfaction with welfare services and the environments of the senior citizen centers in mid-sized and small cities in Korea. Three hundred and two elderly users were surveyed for this study. Age and gender differences in the level of satisfaction were found. The male elderly users and older users were more satisfied with the education programs than the female and younger users. The elderly people who reside in single-family residences were more satisfied with the educational programs and part-time job opportunities offered at the center than the elderly users who were living in apartment buildings. This could be explained by the fact that dwellers of single housing had more freedom and more room for self-regulation in scheduling their program participation, whereas the apartment building residents had rarely experienced social exchanges with their neighbors. There were significant differences in satisfaction with the environments of the centers by gender, marital status, age, level of education, religion, and housing type. The group differences were explained by the abundance of community activities that are centered around younger and female participants. Based on these findings, it is suggested that more specialized educational and social programs should be developed for the younger users in their early 60s, that co-ed religious activities and hobby programs should be expanded, and that the home-visiting welfare staff should regularly provide the elderly users the information on programs and activities.

• 한국항공운항학회지
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• 제23권3호
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• pp.28-34
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• 2015

An analysis method of trajectory prediction has been suggested and the developed trajectory prediction module, which is an important functional component of the Arrival Manager (AMAN) of Jeju airport, has been tested by applying the suggested method. The objective of this method is to improve prediction performance of the trajectory prediction module. The trajectory prediction module predicts the trajectories based on the real-time track data and flight plans. Therefore, the suggested analysis method includes the simulation framework which is based on real-time playback, recording, and graphic display systems for testing. Besides, the definition of time error, which is a important index for the time based scheduling system, such as AMAN, is included in the suggested analysis method. An example of arrival time prediction accuracy improvement through the suggested analysis method has also been presented.

• 한국통신학회논문지
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• 제27권7C호
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• pp.685-695
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• 2002

본 논문에서는 실제 자원의 개발 전에도 망 관리 시스템의 개발 및 운용 테스트를 수행하도록 지원하는 실제자원 시뮬레이터(RRS: Real Resource Simulator)를 소개한다. RRS는 객체의 상태를 유지하는 MOT(Managed Object Table)와 사용자가 정의한 동작 특성을 유지하는 SDT(Simulation Data Table), 랜덤(Random) 값과 랜덤주기(interval) 값을 발생할 지원 함수들, 순차적인 사건 발생 또는 값의 수정을 지원하는 스케줄링 테이블 그리고 이들을 전체적으로 관장하는 메인 커널로 이루어져 있다. 또한 사용자는 확장된 GDMO 문법을 이용하여 RRS의 동작 특성을 지정할 수 있는데, 본 논문에서는 이를 처리할 확장된 GDMO 컴파일러를 설명하고, 사용자와 RRS간의 동작, RRS와 에이전트간 동작, RRS, 에이전트, 망관리 시스템으로 이루어진 환경에서의 동작 확인 결과를 보인다.

• Journal of Communications and Networks
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• 제18권2호
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• pp.150-161
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• 2016

Coordinated multi-point transmission (CoMP) techniques are being touted as enabling technologies for interference mitigation in next generation heterogeneous wireless networks (HetNets). In this paper, we present a comparative performance study of uplink (UL) CoMP algorithms for the 3GPP LTE HetNets. Focusing on a distributed and functionally-split architecture, we consider six distinct UL-CoMP algorithms: 1. Joint reception in the frequency-domain (JRFD) 2. Two-stage equalization (TSEQ) 3. Log-likelihood ratio exchange (LLR-E) 4. Symmetric TSEQ (S-TSEQ) 5. Transport block selection diversity (TBSD) 6. Coordinated scheduling with adaptive interference mitigation (CS-AIM) where JRFD, TSEQ, S-TSEQ, TBSD and CS-AIM are our main contributions in this paper, and quantify their relative performances via the post-processing signal-to-interference-plus-noise ratio distributions.We also compare the CoMP-specific front-haul rate requirements for all the schemes considered in this paper. Our results indicate that, with a linear minimum mean-square error receiver, the JRFD and TSEQ have identical performances, whereas S-TSEQ relaxes the front-haul latency requirements while approaching the performance of TSEQ. Furthermore, in a HetNet environment, we find that CS-AIM provides an attractive alternative to TBSD and LLR-E with a significantly reduced CoMP-specific front-haul rate requirement.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1874-1885
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• 2018

The customer side operation is getting more complex in a smart grid environment because of the adoption of renewable resources. In performing energy management planning or scheduling, it is essential to forecast non-controllable resources accurately and robustly. The PV system is one of the common renewable energy resources in customer side. Its output depends on weather and physical characteristics of the PV system. Thus, weather information is essential to predict the amount of PV system output. However, weather forecast usually does not include enough solar irradiation information. In this study, a PV system power output prediction model (PPM) under limited weather information is proposed. In the proposed model, meteorological radiation model (MRM) is used to improve cloud cover radiation model (CRM) to consider the seasonal effect of the target region. The results of the proposed model are compared to the result of the conventional CRM prediction method on the PV generation obtained from a field test site. With the PPM, root mean square error (RMSE), and mean absolute error (MAE) are improved by 23.43% and 33.76%, respectively, compared to CRM for all days; while in clear days, they are improved by 53.36% and 62.90%, respectively.

• Journal of Information Processing Systems
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• 제6권4호
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• pp.553-562
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• 2010

The core services in cloud computing environment are SaaS (Software as a Service), Paas (Platform as a Service) and IaaS (Infrastructure as a Service). Among these three core services server virtualization belongs to IaaS and is a service technology to reduce the server maintenance expenses. Normally, the primary purpose of sever virtualization is building and maintaining a new well functioning server rather than using several existing servers, and in improving the various system performances. Often times this presents an issue in that there might be a need to increase expenses in order to build a new server. This study intends to use grid service architecture for a form of server virtualization which utilizes the existing servers rather than introducing a new server. More specifically, the proposed system is to enhance system performance and to reduce the corresponding expenses, by adopting a scheduling algorithm among the distributed servers and the constituents for grid computing thereby supporting the server virtualization service. Furthermore, the proposed server virtualization system will minimize power management by adopting the sleep severs, the subsidized servers and the grid infrastructure. The power maintenance expenses for the sleep servers will be lowered by utilizing the ACPI (Advanced Configuration & Power Interface) standards with the purpose of overcoming the limits of server performance.

• 한국정보처리학회논문지
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• 제4권7호
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• pp.1781-1787
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• 1997

최근에 네트워크의 사용량이 증가하고, 다양한 대역폭을 요구하는 응용이 증가함에 따라 이를 지원하기 위하여 유연성이 뛰어난 통신 프로토콜로서 ATM을 사용하게 되었다. ATM은 다양한 대역폭을 요구하는 응용 서비스를 제공하나, 셀의 손실과 지연이라는 문제점을 가지고 있다. 본 논문에서는 ATM망에서의 셀 손실과 셀 지연의 문제점을 해결하기 위해 기존의 트래픽 제어기법을 분석하고, 클래스별로 버퍼의 크기를 할당하는 통합 버퍼 관리기법과 트래픽 특성에 따른 다중 임계를 이용한 ATM 스위치 모델과 트래픽 제어기법을 제시한다. 또한, 시뮬레이션을 통하여 기존의 연구와 본 논문에서 제안된 기법을 비교하여 성능향상을 분석하고 검증한다. 분석 결과, 제안된 기법은 평균 셀 손실율의 측면에서 버퍼 크기에 비례하여 성능이 향상됨을 알 수 있다.

• 한국정보처리학회논문지
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• 제6권9호
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• pp.2320-2331
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• 1999

본 연구에서는 한정된 자원만을 사용하는 기존의 워크스테이션 클러스터링 환경의 제한성을 극복하기 위하여 인터넷에 연결된 혼합 이기종 컴퓨터들을 병렬 컴퓨팅 플랫폼으로 활용하고자 하는 인터넷 컴퓨팅 환경의 구축 기법을 제안한다. 제안하는 글로벌 인터넷 컴퓨팅 환경(Global Internet Computing Environment)은 프로그램의 용이성, 이기종 지원의 효율성, 시스템의 확장성, 그리고 시스템 성능에 초점을 두고 자바를 프로그래밍 및 수행 환경으로 채택하여 인터넷 컴퓨팅 구축에 있어 필수적인 동적 자원 중계 및 관리, 효율적인 병렬 테스크 수행 기법을 제시한다. 본 논문에서는 제안하는 글로벌 인터넷 컴퓨팅 환경의 구성모델 및 동작모델 그리고 시험시스템 구축 내용 및 벤치마킹을 통한 성능 평가 결과를 제시하며 이를 바탕으로 인터넷 컴퓨팅 환경의 구축 개념, 복잡성, 성능의 문제에 대한 분석결과를 기술한다.