• 한국항만경제학회지
• /
• 제20권1호
• /
• pp.21-42
• /
• 2004

This paper addresses the operation, problems, and development policy of Gwangyang Port, Korea. This paper aims to analyze the operation condition and problems of Gwangyang Port and suggest long-term policies for developing Gwangyang Port as a logistic hub in northeast period. It is made up of three main sections: the operation, problems, and forecast of freight volumes; analysis of operational results of Gwangyang Port; development strategies of Gwangyang Port as a Logistics Hub. This paper was mainly based on a review of current papers/reports, an analysis of secondary data, and questionnaire survey. The major development strategies identified consisted of expansion regular service sea-route, formation of inter-modal transportation system, strengthening of port sales for Gwangyang port's recognition, securing operation-profits by fixed cargo volume, and promotion of free tread zone.

• 한국세라믹학회지
• /
• 제29권11호
• /
• pp.855-862
• /
• 1992

Thermoelectric power, electrical conductivity and Hall effect were measured, as functions of temperature in the range of 100 to 600 K, on polycrystalline Bi4/3Sb2/3Te3 which had been prepared via uniaxial hot-pressing at different temperatures in the range of 373 K to 773 K, aiming at searching a profitable processing route to a polycrystalline thermoelectric material, a promising, viable alternative to a single crystalline one. It was found that, with increasing temperature of pressing under a fixed pressure, the material, normally a p-type prior to being hot-pressed, underwent a transition to n-type. This transition was confirmed to be due to plastic deformation during hot-pressing and interpreted as being attributed to the change of the major ionic defect BiTe' into TeBi˙at temperature high enough for structure elements mobility. Thermoelectric figure-of-merit of the hot-pressed material was discussed in connection with the p-n transition in addition to microstructure.

• 디자인학연구
• /
• 제6권1호
• /
• pp.1-10
• /
• 1993

This paper described design as a purposeful human activity for solving its problems. This means, problem solving is finding a way to get from some initial situation to a desired goal.In order to do this, like a voyage, there should be a compass, and a route map to guide the designer through the design process. Evaluation gives information about the way a design is proceeding and suggests the direction in which change should be made in order that the complex of design concepts should be fulfilled in a satisfactory manner.I think Pugh's total design model discussing in this paper takes a layered approach through a series of sequential actions, part of which is to find the product status. Each layer has the $$\mu$ti-dimensional elements, Product Design Specification (PDS) around the design core. I made a comparative study of several evaluation tools wi th Pugh's model and examined the criteria for evaluation and the rating / weighing methods.It needs, however, more study in order that PDSs may have its values and be fixed from the dynamic design concepts.

• 한국컴퓨터정보학회논문지
• /
• 제21권3호
• /
• pp.25-32
• /
• 2016

Mobile Ad Hoc Networks(MANETs) consists of mobile nodes which communicate with each other without any centralized infrastructure. Message broadcasting by flooding for route discovery in MANET can result in high redundant retransmission, contention and collision of broadcasting packet, known as the broadcast storm problem collectively. The cross-layer design is adopted in this paper, which lets routing layer share the received signal strength information at MAC layer. Also this paper proposes a new probabilistic approach that dynamically adjusts the rebroadcasting probability of a node for routing request packets (RREQs) according to the received signal strength. The simulation results show that the proposed approach demonstrates better performance than blind flooding, fixed probabilistic broadcasting approaches.

• 한국경영과학회:학술대회논문집
• /
• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
• /
• pp.1740-1745
• /
• 2006

This paper is concerned with a novel heuristic algorithm for the multi-trip vehicle routing problem with time windows. The objective function is the minimization of total vehicle operating time, fixed cost of vehicle and the minimization of total lateness of customer. A mixed integer programming formulation and a heuristic algorithm for a practical use are suggested. A heuristic algorithm is constructed two phases such as clustering and routing. Clustering is progressed in order to assign appropriate vehicle to customer, and then vehicle trip and route are decided considering traveling distance and time window. It is shown that the suggested heuristic algorithm gives good solutions within a short computation time by experimental result.

• 조명전기설비학회논문지
• /
• 제21권4호
• /
• pp.104-114
• /
• 2007

In this paper, an Ad-hoc Routing Protocol that works in wireless Ad-hoc communication networks with multiple radios and multiple channels and that controls call admission based on bandwidth measurement is proposed. Unlike the conventional Ad-hoc node with a single radio using a single channel, an Ad-hoc node of the protocol proposed, the MCQosR(Multiple Channel Quality of Service Routing), has multiple radios and uses multiple channels, which allows full duplex transmission between wireless Ad-hoc nodes, and reduces intra interference on the route. Also, a fixed channel only for reception at each node enables the estimation of the available bandwidth, which is used to control the call admission for QoS provision. The performance of the MCQosR was verified by simulation.

• 한국생산제조학회지
• /
• 제19권6호
• /
• pp.859-866
• /
• 2010

Generally, a fixed type guide-bush system is installed during machining miniature work-pieces with high precision in the multi-task CNC lathe. But a conventional guide-bush system does not provide a constant clamping force under the condition of varying work-piece diameters. It is important to maintain a constant clamping force for guaranteeing machining precision. This paper proposes a new guide-bush system with a pneumatic clamping device for the CNC Swiss-turn lathe to keep constant clamping force with changes in work-piece diameters. Through performance tests, new clamping system developed in the study showed better machining precision at the cost of a small increase in the temperature of the system than conventional systems due to an increase in the frictional heat and a change in the heat transfer route.

• Journal of Communications and Networks
• /
• 제9권4호
• /
• pp.408-418
• /
• 2007

In this paper, we address the question of dynamic network provisioning for time-varying traffic rates, with the objective of maximizing the system throughput. We assume that the network is capable of providing bandwidth guaranteed traffic tunnels for an ingress-egress pair and present an approach that (1) updates the tunnel routes and (2) adjusts the tunnel bandwidths, in an incremental, adaptive manner, based on the variations in the incoming traffic. First, we consider a simpler scenario where tunnel routes are fixed, and present an approach for adjusting the tunnel bandwidths dynamically. We show, through simulations, that our dynamic bandwidth assignment algorithm significantly outperforms the optimal static bandwidth provisioning policy, and yields a performance close to that of the optimal dynamic bandwidth provisioning policy. We also propose an adaptive route update algorithm, which can be used in conjunction with our dynamic bandwidth assignment policy, and leads to further improvement in the overall system performance.

• 제어로봇시스템학회논문지
• /
• 제17권4호
• /
• pp.375-381
• /
• 2011

This paper deals with the improvement of visual path following through velocity variation according to the coordinate of feature points. Visual path follow first teaches driving path by selecting milestone images then follows the route by comparing the milestone image and current image. We follow the visual path following algorithm of Chen and Birchfield [8]. In [8], they use fixed translational and rotational velocity. We propose an algorithm that uses different translational velocity according to the driving condition. Translational velocity is adjusted according to the variation of the coordinate of feature points on image. Experimental results including diverse indoor cases show the feasibility of the proposed algorithm.

• 조명전기설비학회논문지
• /
• 제24권7호
• /
• pp.26-40
• /
• 2010

We propose a new routing protocol, MCQosR, that is based on bandwidth estimation, admission control, and a routing metric, MCCR - suitable for wireless ad-hoc networks with multiple radios and channels. To use the full capacity of a wireless link, we assume a node with multiple radios for full duplex operation, and a radio using multiple channels to exclude route-intra interference. This makes it possible to use the capacity of a wireless link. Then, to provide bandwidth and delay guarantee, we have a radio with a fixed channel for layer-3 data reception at each node, used to estimate the available bandwidth and expected delay of a wireless link. Based on the estimate of available bandwidth and delay, we apply the call admission control to a new call requiring bandwidth and delay guarantee. New calls with traffic that will overflow link or network capacity are rejected so the accepted calls can use the required bandwidth and delay. Finally, we propose a routing metric, MCCR, which considers the channel contentions and collisions of a wireless link operating in CSMA/CA. MCCR is useful for finding a route with less traffic and distributing traffic over the network to prevent network congestion as much as possible. The simulation of the MCQosR protocol and the MCCR metric shows traffic is distributed and guaranteed service is provided for accepted calls.