• Journal of the Korean Institute of Navigation
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• v.24 no.5
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• pp.343-360
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• 2000

The information technology(IT) development of telecommunication, along with the informationalization over the world, enables the firms to process their inner and outer operations through Electronic Data Interchange (EDI) system. And the concept of logistics has become more important to the enterprises in strategic sense because it had aggrandized itself to more comprehensive and integrative concept. Also the world shipping market is more competitive than any other market. In these environment, to maintain competitve power, shipping firms process operations by Logistics Information system(LIS), And then, reduce the working processes, working time and its costs. So the LIS has become more important in developing our national logistics system and industry. Therefore, this study purposes on empirically analyzing the activation factors of shipping LIS and the relationship these factors with logistic performances in the shipping industry. Considering environments of Shipping logistics information system, this study sets up the research model and hypothesis to examine the activation factors of shipping LIS and the relationship these factors with logistic performances. We used the field data on the 163 numbers of firms(29 overseas shipping companies and 133 forwarding Agency) to get the empirical evidence. According to the study results, The shipping LIS activation factors which the sample firms recognized as important: were top manager's support, well structured communication channel, strategic plan's connection and inner informationalization level. And IS organization ＆ human resources, IS discipline ＆ training, software development, IS organizational alignment, database management system, information standardization, competitive advantage, financial support and government support represent partially significant. Also, the current shipping LIS's main problems are expensive system cost, standardization of working process's, institution's imperfection and system's interaction defect. So these problems must be improved to activate shipping LIS.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.373-373
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• 2009

Relative humidity, membrane conductivity and water activity are critical parameters of polymer electrolyte membrane fuel cells (PEMFC) for high performance and reliability. These parameters are closely related with temperature. Moreover, the ideal values of these parameters are not always identical along the channels. Therefore, the cooling channel design and its operating condition should be well optimized along the all location of the channels. In the present study, we have performed a numerical investigation on the effects of cooling channels on performance of a PEMFC. Three-dimensional Navier-Stokes equations are solved with the energy equation including heat generated by the electrochemical reactions in the fuel cell. The present numerical model includes the gas diffusion layers (GDL) and serpentine channels for both anode and cathode gas flows, as well as cooling channels. To accurately predict the water transport across the membrane, the distribution of water content in the membrane is calculated by solving a nonlinear differential equation with a nonlinear coefficient, i.e., the water diffusivity which is a function of water content as well as temperature. Main emphasis is placed on the heat transfer between the solid bipolar plate and coolant flow. The present results show that local current density is affected by cooling channels due to the change of the oxygen concentration and the membrane conductivity as well as the water content. It is also found that the relative humidity is influenced by the generated water and the gas temperature and thus it affects the distribution of fuel concentration and the conductivity of the membrane, ultimately fuel cell performance. Unit-cell experiments are also carried out to validate the numerical models. The performance curves between the models and experiments show reasonable results.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.3
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• pp.165-176
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• 2009

The process of berthing/deberthing operations for entering/leaving vessels in Busan northern harbor was analyzed and evaluated by using an integrated VTS(vessel traffic service) system installed in the ship training center of Pukyong National University, Busan, Korea. The integrated VTS system used in this study was consisted of ARPA radar, ECDIS(electronic chart display and information system), backup(recording) system, CCTV(closed-circuit television) camera system, gyro-compass, differential GPS receiver, anemometer, AIS(automatic identification system), VHF(very high frequency) communication system, etc. The network of these systems was designed to communicate with each other automatically and to exchange the critical information about the course, speed, position and intended routes of other traffic vessels in the navigational channel and Busan northern harbor. To evaluate quantitatively the overall dynamic situation such as maneuvering motions for target vessel and its tugboats while in transit to and from the berth structure inside a harbor, all traffic information in Busan northern harbor was automatically acquired, displayed, evaluated and recorded. The results obtained in this study suggest that the real-time tracking information of traffic vessels acquired by using an integrated VTS system can be used as a useful reference data in evaluating and analyzing exactly the dynamic situation such as the collision between ship and berth structure, in the process of berthing/deberthing operations for entering/leaving vessels in the confined waters and harbor.

• The Journal of Korean Oriental Chronic Disease
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• v.10 no.1
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• pp.21-31
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• 2005

We have analyzed 247 patients who were admitted to the 3rd ICU for intensive care between January 2003 and December 2003 to investigate characteristics of ICU patients and obtain better guidance and management in the ICU. The results are as follows: 1) The total number of patients was 247. The proportion of males was 59.1 %, of females was 40.9%, and the ratio of male to female was about 1.45:1. 2) The most prevalent age group is those in their seventies, the proportion is 33.6%. 3) The total admission days was 3,438days, and mean patient stay being 13.9days. 4) The total number of expired patients was 26, the mortality rate was 10.5%. The mortality in distribution by disease was higest in Cerebral infarction, rate was 53.8%. the proportion of raised intracranial pressure was 42.3%, of hemorrhagic transformation was 11.5%. 5) In distribution by admission channel, Oriental hospital E.R. was 60.7%, Oriental hospital ward was 38.5%, and etc. was 0.8%. 6) The number of patients of Cerebral infarction was 146(59.1%), being the highest in distribution by chief disease and the proportion of MCA territory infarction is highest in the Cerebral infarction(61.6%). 7) In distribution by Oriental Medicine therapy, the proportion of Acupuncture treatment was 15.8%, of Acupuncture treatment combination Herb medication was 78.5%, and of Acupuncture, Herb medication plus subcutaneous Acupuncture treatment was 5.7%.

• The Journal of the Korea Contents Association
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• v.3 no.3
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• pp.40-46
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• 2003

In the paper, designed digital contents security module to check unlawfulness reproduction and distribution of digital contents. This paper applied Diffie-Hellman algorithm that use discrete logarithm and random number as primary for public key application to create encryption key that agree each other through communication channel between DCPS and HOST, and applied Triple DES repeat DES 3 times through 2 different encryption key that is selecting ANSI X9.17 that is key management standard, ISO 8732 and PEM(Privacy-Enhanced Mail) etc. by secondary protection for safe transmission of digital contents in transmission line. Designed security module consist of key exchange module, key derivation module and copy protection processing module. Digital contents security module that design in this thesis checks reproduction and distribution of digital contents by unauthenticated user through user certification function and digital contents encryption function, and protect digital contents transmission line.

• Journal of the Korean Society of Safety
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• v.31 no.2
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• pp.70-75
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• 2016

Recently, coastal erosion has been widely in progress and the erosion level becomes also serious in the world wide, espeically in East Sea in Korea. Since it would threaten the life, economics and security risk, it is necessary to much comprehend the reason why coastal erosion has occurred according to the geographical characteristics. Meanwhile, analysis about hydrodynamics of the solitary wave such as tunami in swash zone is needed for the best management practice of coastal erosion. Solitary wave is nonlinear wave and can be reproduced in the laboratoy scale by openning suddenly a sluice gate with water head difference, of which methodology was found in the literature, since it could be simply determined by a significant wave height. Thus, in this sutdy the generation of solitary wave was experimentalized using the sluice gate. Experimental conditions were classified by angles of a beach slope, a water level in a beach slope and a difference of water level between in a headtank and a channel bed. Two kinds of dimensionless analyses based from experimental results in this study were presented; the first analysis indicates nondimensionalization between the wave height and the water level in a beach slope in order to investigate characteristics of solitary wave approaching the beach. The second shows the other nondimensionalization between dynamic pressure and static pressure on a beach slope to investigate the relationship between wave breaking and wave pressure. Under the same conditions as laboratory experiments, the numerical results computed with a SWAN model embedded in FLOW 3D were compared in terms of wave height, and pressure on the beach slope, which shows good agreement with each other. Overall results from this study could provide fundamental hydraulic data for the reliabile verification of numerical simulation results about coastal erosion in swash zone caused by solitary waves.

• Journal of the Korean Institute of Navigation
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• v.25 no.2
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• pp.159-172
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• 2001

The information technology(IT) development of telecommunication, along with the information analyzation over the world, enables the firms to process their inner and outer operations through Electronic Data Interchange (EDI) system. And the concept of logistics has become more important to the enterprises in strategic sense because it had aggrandized itself to more comprehensive and integrative concept. Also the world shipping market is more competitive than any other market. In these environment, to maintain competitive power, shipping firms process operations by Logistics Information system(LIS), And then, reduce the working processes, working time and its costs. So the LIS has become more important in developing our national logistics system and industry. Therefore, this study purposes on empirically analyzing the activation factors of shipping LIS and the relationship these, factors with logistic performances in the shipping industry. Considering environments of Shipping logistics information system, this study sets up the research model and hypothesis to examine the activation factors of shipping LIS and the relationship these factors with logistic performances. We used the field data on the 163 numbers of firms(29 overseas shipping companies and 133 forwarding Agency) to get the empirical evidence. According to the study results, The shipping LIS activation factors which the sample firms recognized as important: were top managers support, well structured communication channel, strategic plans connection and inner information analyzation level. And IS organization & human resources, IS discipline & training, software development, IS organizational alignment, database management system, information standardization, competitive advantage, financial support and government support represent partially significant. Also, the current shipping LISs main problems are expensive system cost, standardization of working processs, institutions imperfection and systems interaction defect. So these problems must be improved to activate shipping LIS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2A
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• pp.144-153
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• 2006

In this paper, we propose an efficient video data transmission protocol using the cross-layer approach in ad hoc networks. Due to node movement, the MANET is frequently changing path and each path has different transmission rate so that it has low performance when transmitters select a constant transmission late at the encoding time. Because MANET is running limited energy, efficient energy management is important because it increases network life time and network throughput. Therefore we need an effective video transmission method that considers physical layer channelstatistics, node's energy status, and network topology changes at the same time unlike the OSI recommendation protocol in that each layer isindependent and hard to transmit adaptively video data according to the network conditions. Therefore, in this paper we propose a cross-layer effective video transmission protocol and mechanism that can select an optimal path using multilayer information such as node's residual energy, channel condition and hop counts and can determine the adequate coding rate adaptively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9B
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• pp.745-750
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• 2008

In a cognitive radio based system, quality of service (QoS) for the secondary user must be maintained as much as possible even while that of the primary user is protected all he time. In particular, switching wireless links for the secondary user during the transmission of multimedia data causes delay and information loss, and QoS degradations occur inevitably. The efficient resource management scheme is necessary to support the seamless multimedia service to the secondary user. This paper proposes a novel frequency selection method based on Multi-Criteria Decision Making (MCDM), in which uncertain parameters such as received signal strength, cell load, data rate, and available bandwidth are considered during the decision process for the frequency selection with the fuzzy set theory. Through simulation, we show that our proposed frequency selection method provides a better performance than the conventional methods which consider the received signal strength only.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.17-24
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• 2018

The HEC-HMS model was applied to identify the rainfall-runoff processes for the Anseongchun basin, where the lower part of the stream has been damaged severely by tropical storms in the past. Modeling processes include incorporating with the SCS-CN model for loss, Clark's UH model for transformation, exponential recession model for baseflow, and Muskingum model for channel routing. The parameters were calibrated through an optimization technique using a trial and error method. Sensitivity analysis after calibration was performed to understand the effects of parameters, such as the time of concentration, storage coefficient, and base flow related constants. Two storm water events were simulated by the model and compared with the corresponding observations. Good accuracy in predicting the runoff volume, peak flow, and the time to peak flow was achieved using the selected methods. The results of this study can be used as a useful tool for decision makers to determine a master plan for regional flood control management.