• 한국항해항만학회지
• /
• 제29권1호
• /
• pp.9-15
• /
• 2005

항만의 계획 및 개발단계에서 중요한 요소 중 하나는 항로의 설계이다. 대부분의 경우 수심이 확보되어 있는 수역이라면 항로의 설계의 핵심은 항로의 배치와 항로폭의 결정이 될 것이다. 본 연구에서는 가변범퍼영역모델을 이용하여 항로를 설계하고 평가한다 이 모델은 선박의 주요명세, 선박점용이론, 선박의 속력, 선박지휘자의 조선기술과 경험을 항로설계에 반영할 수 있으며, 특히 선박의 운동 및 조종특성에 영향을 주는 외력을 정확하게 반영할 수 있다. 이를 위해 선박조종자의 선박제어와 외력 등에 의해 생성되는 선박의 동적데이터를 분석하기 위해 전기능선박조종시뮬레이터를 이용하였으며, 항로의 적정성과 안전성을 평가하기 위해 점용도와 점용지수를 정의한다. 개발된 항로설계기법을 울산신항개발계획에 적용하였다. 이 계획에서 항로의 폭은 전장의 1.5배 중심교각 57도인 만곡부의 곡률반경은 전장의 5.0배로 설계하였으며, 항로부근에는 SBM이 위치하고 있다. 모델의 적용결과 항로의 폭과 곡률반경은 적절하지만, 대각도 변침과 항로부근에 위치한 SBM에 의해 선박조선상의 어려움이 야기되는 것으로 분석되었다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2008년도 하계종합학술대회
• /
• pp.245-246
• /
• 2008

A cell planning and resource allocation scheme called the proposed is presented for improving channel capacity and for maintaining a proper QoS (Quality of Service) over the downlink OFDMA (Orthogonal Frequency Division Multiple Access) system. Through an optimal combination of sectorization and frequency overlay, the proposed scheme accomplishes an improvement in both channel capacity and outage probability. In the simulation, the proposed scheme outperforms 3-sectorization in terms of throughput and outage probability.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2003년도 추계종합학술대회
• /
• pp.737-740
• /
• 2003

대부분의 디지털 방송 시스템에서는 한정된 지상파 주파수 자원 때문에 최소한의 주파수 자원을 사용하는 SFN 또는 OCR등의 기법을 제공하고 있다. 본 논문에서는 미국 ATSC방식의 OCR과 유럽의 DVB-T방식의 SFN에 대한 특성을 연구 분석하고 중계기 및 송신기의 위치에 따른 수신영역을 시뮬레이션 하기 위한 방안을 제시한다.

• Journal of Information Processing Systems
• /
• 제13권6호
• /
• pp.1602-1612
• /
• 2017

Since rapidly disseminating of Internet of Things (IoT) as the new communication paradigm, a number of studies for various applications is being carried out. Especially, interest in the smart medical system is rising. In the smart medical system, a number of medical devices are distributed in popular area such as station and medical center, and this high density of medical device distribution can cause serious performance degradation of communication, referred to as the coexistence problem. When coexistence problem occurs in smart medical system, reliable transmitting of patient's biological information may not be guaranteed and patient's life can be jeopardized. Therefore, coexistence problem in smart medical system should be resolved. In this paper, we propose a distributed coexistence mitigation scheme for IoT-based smart medical system which can dynamically avoid interference in coexistence situation and can guarantee reliable communication. To evaluate the performance of the proposed scheme, we perform extensive simulations by comparing with IEEE 802.15.4 MAC protocol which is a traditional low-power communication technology.

• 한국정밀공학회지
• /
• 제12권2호
• /
• pp.135-144
• /
• 1995

조립작업에 있어서의 경로계획(path planning)에 대하여 지금까지 많은 연구가 진행되어 왔으며, 그것의 주종을 이루는 것들은 cell decomposition 방식과 potential field 방식이다. 이러한 방식들은 free space를 세분하거나 potential field를 계산하는데 많은 시간을 필요로 하며, 조립부품 이동영역이 configuration space로 먼저 치환이 되어야 하는 문제점들이 발생하게 된다. 그러므로, 만약에 조립부품에 대한 이동환경이 복잡하지 않고 알려져 있으면 위의 방식들은 비용적인 면에서 많은 낭비를 가져온다. 본 논문에서는 간단하면서도 알려진 작업환경에서 효과적인 조립부품의 경로계획 알고리즘을 개발하였다. 먼저, channel, junction 및 간격 유지계수(clearance gap)의 개념을 도입하고, 이 개념들을 이용하여 룰 방식의 알고리즘을 개발하였다. 그리고, 이 알고리즘을 이동용 로봇의 경로계획에도 적용될 수 있음을 보였다.

• 농촌계획
• /
• 제6권2호
• /
• pp.12-19
• /
• 2000

Irrigation pipeline networks consist mainly of buried pipes and are therefore relatively free from topographic constraints. Installation of irrigation pipeline systems is increasing since the systems have several advantages compared to open channel systems. To achieve economic design of pipeline networks, the layout should meet several conditions such as shortest path, maximum flow, and least cost. Graph theory is mathematical tool which enable to find out optimum layout for complicated network systems. In this study, applicability of graph theory to figure out optimum layout of irrigation pipeline networks was evaluated.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권5호
• /
• pp.2453-2467
• /
• 2017

Wireless communication is a telecommunication technology, which enables wireless transmission between the portable devices to provide wireless access in all types of environments. In this research, the measurements and various empirical models are analysed and compared in order to find out a suitable propagation model to provide guidelines for cell planning of wireless communication systems. The measured data was taken in urban region with low vegetation and some trees at 900 MHz frequency band. Path loss models are useful planning tools, which permit the designers of cellular communication to obtain optimal levels for the base station deployment and meeting the expected service level requirements. Outcomes show that these empirical models tend to overestimate the propagation loss. As one of the key outputs, it was observed that the calculations of Weissberger model fit with the measured data in urban environment.

• 해양환경안전학회지
• /
• 제1권1호
• /
• pp.9-25
• /
• 1995

Although the studies carried out in recent years have provied much new information about channel widths and alignment, they are not consistent in their results. In addition, as a result of variations in local condition and type of traffic accommodated, the dimensions of the channel widths vary over a wide range. Therefore, the recommendation made by the maritime engineering organizations over the world, do not offer detailed and decisive optimal design criteria and are all different. It, therefore, was attempted in this paper to draw a decisive guideline on the optimal widths and alignment of the navigational channels, which can be utilized by the port designers at the stage of the planning. The guideline was drawn through the comparison and analysis of the existing guidelines of the U.S.A, Japan and PIANC and simulation experiment. The simulation experiment was carried out using the "Off Line Port and Waterway Design Simulator" to find the optimal dimensions of the widths of the navigational channels. 90 different simulation runs were conducted at the 3 different secenario channels. New guidelines, the result of the study, is expected to be used usefully by the Korean port designers when designing the rapodly developing ports in Korea. in Korea.

• 한국해양공학회지
• /
• 제22권4호
• /
• pp.84-89
• /
• 2008

It is hard to find experimental data for a model test of small high-speed planning boats. It is difficult to verify the performance seen in a model test for a high-speed boat because the ship-model scale-ratio is very small and the flow velocity of the circulating water channel and the X-carriage speed of the towing tank are restricted. Therefore most hull-form designs for high-speed small boats depend on the sea-trial test result for similar boats or evaluation through numerical calculations. This study investigated the anti-rolling effect of the stern sub-body in a 50-knot doss planning boat. To carry out this work, new model test procedures were set up in the actual sea. Using this method, the anti-rolling effect of the stern sub-body was investigated. A stern sub-body attached to a planning boat was proved to be effective in reducing the roll and pitch angle.

• 무역상무연구
• /
• 제36권
• /
• pp.143-170
• /
• 2007

In order to analyze the distribution channel of marine products in Korea, this study shows SCM approach to redesign of the marine distribution channel with case study related to previous literatures. In view of the supply chain and the future impact of RFID on the marine SCM on the recognition of the importance of the seafood traceability system, this study also provides the possibility to accomplish effective SCM for integration of production, storage, transportation, delivery, and sale when RFID is used in the seafood distribution channel based on the expansion of awareness on the marine product traceability. The traceability system for seafood is considered as the distribution infrastructure established in RFID deployment. By introducing Lotte mart case, this case study also discusses the marine distribution structure in view of the supply chain, to present an effective foundation for supplying seafood throughout production, distribution, and consumption. This is achieved by introducing RFID in an ubiquitous environment, and suggesting far more efficient control planning throughout the seafood distribution channel in view of the expected effects resulting from the introduction. In addition, as the alternative of solving this situation, this study propose the supply chain in seafoods by comprehensive management in whole distribution channels. In the SCM in seafood perspectives, HACCP can take into account the whole seafood chain from the point of supply to the point of consumption when assessing hazards. As the contributions of this study, this study emphasizes the seafood industry first should require the establishment of the relevant infrastructure, for which the efforts of the government and demonstrative project participants are essential.