• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제5권3호
• /
• pp.523-541
• /
• 2011

In current IEEE 802.11 wireless LAN, every unicast transmission requires an ACK from the receiver for reliability, though it consumes energy and bandwidth. There have been studies to remove or reduce ACK overhead, especially for energy efficiency. However none of them are practically used now. This paper introduces a noble method of selective unacknowledged transmission, where skipping an ACK is dynamically decided frame by frame. Utilizing the fact that a multicast frame is transmitted without accompanying an ACK in 802.11, the basic unacknowledged transmission is achieved simply by transforming the destination address of a frame to a multicast address. Since removing ACK is inherently more efficient but less strict, its practical profit is dependent on traffic characteristics of a frame as well as network error conditions. To figure out the selective conditions, energy and performance implications of unacknowledged transmission have been explored. Extensive experiments show that energy consumption is almost always reduced, but performance may be dropped especially when TCP exchanges long data with a long distance node through a poor wireless link. An experiment with a well-known traffic model shows that selective unacknowledged transmission gives energy saving with comparable performance.

• 대한산업공학회지
• /
• 제25권4호
• /
• pp.500-509
• /
• 1999

In this paper, we consider an optimal routing problem when point-to-point and point-to-multipoint connection traffics are offered in an ATM network. We propose a mathematical model for cost-minimizing configuration of a logical network for a given ATM-based BISDN. Our model is essentially identical to the previous one proposed by Kim(Kim, 1996) which finds a virtual-path configuration where the relevant gains obtainable from the ATM technology such as the statistical multiplexing gain and the switching/control cost-saving gain are optimally traded-off. Unlike the Kim's model, however, ours explicitly considers the VP's QoS(Quality of Service) for more efficient utilization of bandwidth. The problem is a large-scale, nonlinear, and mixed-integer problem. The proposed algorithm is based on the local linearization of equivalent-capacity functions and the relaxation of link capacity constraints. As a result, the problem can be decomposed into moderate-sized shortest path problems, Steiner arborescence problems, and LPs. This fact renders our algorithm a lot faster than the previous nonlinear programming algorithm while the solution quality is maintained, hence application to large-scale network problems.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2011년도 춘계학술발표대회
• /
• pp.158-159
• /
• 2011

Energy efficiency in wireless sensor networks (WSNs) is one significant factor that needs to be considered when making any designs or doing any enhancements on the communication protocol stack. In WSNs using traditional geographic routing, when a sensor node receives a data packet that needs to be transmitted to the sink, it will forward the packet to the neighbor node which is closest to the sink. The traditional geographic routing assumes that the link quality is always 100%. This may cause a bad result as per which we waste too many energy for retransmissions between the two nodes. Thus, the problem here is how to select such node as forwarder at most efficiently in the aspect of both energy consumption and the distance toward the destination. The better node we choose, the more energy we can conserve for the whole network. In this paper, we propose a next-hop forwarding selection metric, called Energy Consumption for Transmission (ECT), which can resolve the above problem in the best way.

• Journal of Power Electronics
• /
• 제4권3호
• /
• pp.138-151
• /
• 2004

In this paper, a constant frequency phase shifting PWM-controlled voltage source full bridge-type series load resonant high-frequency inverter using the $4^{th}$ generation IGBT power modules is presented for innovative consumer electromagnetic induction heating applications, such as a hot water producer, steamer and super heated steamer. The bridge arm side link passive capacitive snubbers in parallel with each power semiconductor device and AC load side linked active edge inductive snubber-assisted series load resonant tank soft switching inverter with a constant frequency phase shifted PWM control scheme is evaluated and discussed on the basis of the simulation and experimental results. It is proved from a practical point of view that the series load resonant and edge resonant hybrid high-frequency inverter topology, what is called, DE class type, including the variable-power variable-frequency regulation function can expand zero voltage soft switching commutation area even under low output power setting ranges, which is more suitable and acceptable for newly developed induction heated dual pack fluid heaters. Furthermore, even the lower output power regulation mode of this high-frequency load resonant tank inverter circuit is verified so that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.

• 한국건축시공학회지
• /
• 제13권6호
• /
• pp.619-626
• /
• 2013

건설현장에서는 많은 사진이 촬영되나, 촬영된 사진들에 대한 6하원칙 정보가 효율적으로 관리되지 못하고 있다. 이로 인하여, 건설경험과 지식이 없는 경우에는 의사소통이 용이하지 않고, 이해관계자간의 협의, 분쟁, 시설물 유지관리, 다른 시설물 건설 등에 촬영된 사진정보가 활용되는데 한계가 있었다. 본 연구에서는 촬영된 사진과 6하원칙 정보가 결합된 벡터사진의 필요성을 제기하고, 벡터사진 생성 및 서버저장 모듈의 프로토타입을 개발하였다. 촬영된 벡터사진은 실시간으로 서버에 저장되고, 6하원칙정보에 의해 DB 시스템에서 효율적으로 관리될 수 있다. 향후 벡터사진과 BIM모델을 연계하는 시스템을 개발하면, 사진 속의 벡터정보를 BIM모델의 객체 속성정보와 연결시킬 수 있게 되어, 벡터사진은 더욱 다양한 용도로 활용될 수 있을 것으로 기대된다.

• 한국인터넷방송통신학회논문지
• /
• 제13권6호
• /
• pp.101-108
• /
• 2013

본 논문에서는, NACK 메시지가 스펙트럼 공유와 협력을 위한 명령으로 사용되어지는 방법을 제안하였다. 1차 사용자의 직접 연결이 중단될 때, 협력과 공유의 자동 반복을 허가하고, 패러다임 기반의 협력 스펙트럼 공유의 조정 메시지의 수를 절약하기 위해 허가한다. 공유 시, ${\alpha}$의 남은 전력 부분이 1차 재전송 신호인 동안, 2차 전송된 신호를 위한 $1-{\alpha}$ 전력 부분은 중계기 공유로 선택된다. 중계기를 사용하지 않는 경우, 1차 송신단은 전체 전력($1-{\alpha}$)를 사용하여 신호를 재전송 하기 위해 NACK를 사용한다. 두 시스템은 BPSK 신호를 적용한 것으로 가정한다. 이 기법에서, 2차 사용자는 공동 최적화 복호를 하는 것으로 제안한다. 프레임 오류율(FER) 성능은 양 시스템에서 분석된다. 이론과 시뮬레이션 결과는 본 프로토콜의 유효성을 분석하고 효율적임을 확인하였다.

• 한국항만경제학회지
• /
• 제23권3호
• /
• pp.103-126
• /
• 2007

우리나라와 일본정부는 해운정책의 일환으로써 계획조선정책을 실시하였다. 한국의 경우, 선복의 확보, 자국화자국선의 실시, 국내조선산업과 해운을 연계하여 육성하기 위하여 계획조선제도의 도입을 실시하였다. 일본도 마찬가지로 제2차세계대전중에 파괴된 상선대의 회복 및 자국조선산업의 활성화를 위하여 계획조선제도를 실시하였다. 우리나라의 계획조선정책은 선박자본측면에서 해운회사의 부담을 경감시킴으로써 우리나라 해운회사들이 저렴한 선원비와 화물유보정책 등의 지원하에서 급속한 성장을 이룩하는데 일조를 담당하였음은 인정되나 문제점도 발견된다. 첫째, 조달재원의 금리적인 측면에서 선진 해운국의 조달금리와 비교하여 볼 때 열위에 있었다는 점이다. 둘째, 계획조선을 위한 조달재원이 부족하여 수요를 충족시키지 못한 점이다. 셋째, 한국정부는 시장환경변화에 따른 신속한 정책의 반영이 결여되어 있었다. 오늘날 세계해운시장이 개방화, 국제화되고 있는 시점에서 경쟁력 있는 선박의 확보는 해운기업의 중요한 경영요소의 하나이며 우리나라도 이를 지원할 수 있는 방향으로 해운정책이 수립되어야 한다.

• 통상정보연구
• /
• 제9권2호
• /
• pp.257-283
• /
• 2007

As Global industrial structure is diversified, multinational corporations accomplished fast internationalization to introduction of new management policy by development of an IT technology. Enterprise' business environment is changing transcending border. To overcome raging waves of change accident and to be secured enterprise's future, the logistics is recognized the third profit source joining in curtailment of sale enlargement, production cost. To seek cost saving or reform in logistics class that is last area of pursuit of profits within ancient city life in the fast lane from these viewpoint, importance of study that integrates and manages international logistics bases supply neck walk is emphasized. Specially, to meet on in terms of competitive power security regarding curtailment of logistics cost is available through link between logistics bases, various consumer's request, merchandise and service logistics management that supply fixed quantity as is reliable in right place at good season was embossed by point game plan of business management, and SCM efficiency anger of mortification international logistics activity importance of study that see at that dominate competitive advantage point bring. This study analyzes interrelation and presents model for integration of international logistics bases supply network with supply network habit at factor and supply chain, and supply network activity in integration of supply chain process and production. Also, it establishes following method of study to achieve study purpose for actual proof analysis for integration sequence of international logistics bases supply network. Specially, immersion of network and supply network, very high interrelation appeared by thing which is with international logistics base supply network integration. The integration of international logistics base supply network means that the enterprises which give trust and sincerity deal with market environment change positively and can decide proceeding of various cooperative work. Also, it means the possibility by necessity of cooperative relation and interdependence to continuous immersion and normative immersion, for the maintain of long business relations.

• 한국콘텐츠학회논문지
• /
• 제18권6호
• /
• pp.102-112
• /
• 2018

본 연구는 우리나라 에너지 절감 기술 개발이 절실히 요구되어지고 있으며 에너지 효율성 개선을 통해 환경부하를 최소화하여 경제적 원/부자재 절감으로 이어질 수 있도록 지역 중소기업의 핵심 신기술을 배경으로 외관디자인개발을 진행하고 기술에 대하여 특허 범위를 확대 강화하고 디자인권리를 확보함으로써 경쟁사의 침해를 피해 강소기업 설장의 발판이 되는 개발연구이다. 유형의 제품과 무형의 기술을 통합한 기술-디자인융합을 통해 기업에 대한 진단 분석을 진행하고 핵심기술에 대한 분석 평가를 진행하여 권리범위를 진단하고 디자인개발을 통해 신기술에 대한 권리범위와 디자인권리를 확대 및 권리침해를 예방하고 디자인 개발 이후 기업의 기술성장에 대한 분석에 그 목적이 있다. 기술-디자인융합을 통해 핵심기술에 대한 권리범위를 넓히고 기업의 제품을 디자인 개발하여 기업의 가치를 높이고 기업 핵심기술과 디자인에 대한 개발로 권리를 강화하고 역량기업으로 성장할 수 있도록 진행하고자 한다.

• 수산해양교육연구
• /
• 제17권2호
• /
• pp.193-208
• /
• 2005

The object of this study is to provide a framework of increasing the effectiveness of the R&D planning of experts in fisheries and the education of students with the theoretical background and analytical skills through the adoption of technology roadmapping process in the marine production industry. The study was conducted by fact-finding surveys and the response content for surveys obtained from each expert advisor in the field of fisheries and maritime affairs such as fishery industries, some government organizations and research institutes including the Ministry of Maritime Affairs and Fisheries (MOMAF), National Fisheries Research and Development Institute (NFRDI) and fisheries-related universities was analyzed. The major implementation tasks to effectively achieve the basic goals of technology roadmap for short and middle-term research and development in the fisheries production field are as follows: 1. Research in order to achieve the realization of community-based resource management fisheries or fishermen-oriented co-management fisheries with paradigm shift in fisheries management. 2. Research in order to derive the construction of cost reducing and manpower saving systems in fishery-related science, technology and engineering. 3. Research in order to create the high value-added fisheries products with a focus on the upgrading of processing, freezing and refrigerating facilities, the reduction of logistics costs and the minimization of distribution steps. 4. Research in order to achieve the realization and development of environmental-friendly fisheries and internationally competitive fisheries through restructuring the entire fishing industries, in particular, small-scale fisheries. 5. Research in order to achieve the effective utilization of fisheries resources with a new creation of clean and living marine environment by fisherman under the balanced management and protection of marine living resources and fishing grounds.