• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6B
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• pp.728-737
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• 2011

For the real time monitoring and tracking of shipping container which is one of the core objects for global logistics, Wireless Ad-Hoc Network technology might be needed in stacking environments such as ports, yards and ships. In this paper, we propose a container network routing protocol suitable for port or yard stacking environments which include some constraints such as shadow area problem from metal material, frequent movement of container, etc. With this protocol in which a mesh network algorithm is applied, every container data packet can be delivered to the sink node reliably even with frequent join/leave of container nodes. As soon as a node on path gets malfunction, alternative backup path is supported with notice to neighbor node, which makes constant total optimal path. We also verified that the performance of proposed protocol is better than AODV, one of previous major MANet(Mobile Ad-Hoc Network) protocol with a function for alternative path, which says the proposed protocol is better for frequent join/leave and variable link quality.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3A
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• pp.258-264
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• 2009

In this paper, we propose an efficient cooperative diversity scheme for mobile satellite multimedia broadcasting services. The proposed scheme is a transmit diversity technique to adapt time varying channel conditions, and we do not need any channel quality information from the return link. In the proposed scheme, we utilize space-time block coding (STBC) and rate compatible turbo codes in order to realize the transmit diversity for the mobile satellite system with several repeaters. The satellite and several repeaters operate in unison to send the encoded signals, so that the receiver may realize diversity gain. The simulation results demonstrate that the proposed scheme can provide highly improved performance.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.3
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• pp.213-218
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• 2020

In this study, we propose a control algorithm to reduce the unbalanced characteristics of a three-phase system power caused by the unbalanced load of the AC electric railway. Then, we verify its performance through the design of a power compensator and experiments applying it. Like electric railway systems, a Scott transformer is applied, and the load and single-phase back-to-back converters are connected to the M-phase and T-phase outputs. The back-to-back converter monitors the difference in active power between the unbalanced loads in real-time and compensates for the power by using bidirectional characteristics. The active power is performed through PI control in the synchronous coordinate system, and DC link overall voltage and voltage balancing control are controlled jointly by M-phase and T-phase converters to improve the responsiveness of the system. To verify the performance of the proposed power compensation device, an experiment was performed under the condition that M-phase 5 kW and T-phase 1 kW unbalanced load. As a result of the experiment, the unbalance rate of the three-phase current after the operation of the power compensator decreases by 58.66% from 65.04% to 6.38%, and the excellent performance of the power compensator proposed in this study is verified.

• Korean Journal of Community Nutrition
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• v.24 no.5
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• pp.422-432
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• 2019

Objectives: The purposes of the study were to assess wastes generated in school foodservice and to identify factors influencing the generation of plate waste. Methods: A survey was administered from November 18-30 in 2015 to dietitians and nutrition teachers that were employed in schools located in Gyeonggi province. A questionnaire file and on-line survey site link were sent to the dietitians and nutrition teachers by e-mail. A total of 622 dietitians and nutrition teachers responded and 594 responses were used for data analysis after excluding 28 responses with significant missing data. Results: Plate waste was the major part of food waste generated in school foodservice. Vegetable menus and soup/stews were discarded the most as plate waste. The dietitians and nutrition teachers perceived students' unbalanced diet and lack of appreciation of food as causes of the plate waste. Regarding waste management, they were concerned about environmental contamination by food waste and felt uncomfortable about discarding food. No plate waste day was the most frequently used plate waste reduction activity, followed by newsletters on plate waste reduction. Difficulty in getting teachers' support for dietary education during meal time was rated the greatest barrier to implementing the activities. To reduce plate waste, they perceived that students should understand the importance of environment conservation, teachers should supervise students' eating during meal time, students should be educated about proper portion, and foodservice staff should improve food quality. Conclusions: To improve students' intake and reduce plate waste in school foodservice, foodservice staff need to involve students in school foodservice and improve the palatability of meals, especially vegetable dishes. School nutrition teachers and dietitians should educate students about healthy eating and environment conservation and the school community needs to understand and support plate waste reduction and healthy eating in schools.

• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.372-382
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• 2005

DS/CDM-QPSK (ITU-R Recommendation BO.1130-4 Annex 6, 'Digital System E'), which has been adoptedas a standard of Korean Satellite DMB (Digital Multimedia Broadcasting) system, is a satellite-based multimedia broadcasting service which transmits the multi-channel and high quality contents to the terrestrial users through a satellite or gap-fillers. The broadcast from a satellite is directly received in the plain terrain which are within line-of-sight, but in cities where the broadcast cannot be received directly due to the shadow of buildings, an attempt is being made to install 'Gap-Fillers' to improve the reception in those areas. The gap-fillers, however, may induce interference to service of adjacent band, when their output power is substantially higher compared to the received signal power of signal from a satellite of the adjacent service. In this paper, a link budget analysis is performed, and the optimal EIRP of a gap-filler to maximize the gap-filler coverage, while preventing adjacent band interference is derived.

• Korean Institute of Interior Design Journal
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• no.37
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• pp.129-135
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• 2003

Currently, obtaining information about the interior design studies through the internet web sites is one of the outstanding mediums. Those are of the housings, architecture, interior design, furniture products, hotels and its journals, etc., and out of all those informations are the highly expected value of use. This study focuses on web-site uses in the interior designs' business. To process the study, a two-step research was executed; The step 1 was to find out the current status of web-sites by asking the each panelist to submit the monitored results after having searched and tested for more than two sites that was executed during the October, 2001. The analysis was made with the 47 sample sites selected from the monitored sites. And the step 2 was to find out the contents and evaluation factors of web-sites related the interior design. The results of the study are summarized as follows: First, the monitored Intoner design related 25 web-sites were classified into 3 groups. One group of 13 sites is identified as a remodeling/construction works, and one another with 7 sites is as shopping site, and the other with 5 sites is as a professional portal site. Second, the evaluation has been implemented which has shown 5 variables on the information searches are $\circled1$ the diversities of contents, $\circled2$ the accuracy/reliability of techniques, $\circled3$ the design of a picture and communication, $\circled4$ the convenience of link, and $\circled5$ the originality of web-site This study will provide the users with a fundamental material in evaluating the quality of interior design information on the internet web sites.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.8
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• pp.18-22
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• 2015

Digitalization of the substation in Korea has been in progress so far with focusing on Station Bus. However, its application to Process Bus has been delayed due to some technical issues. IEDs based on Process Bus use the data values of SV and GOOSE. As the size of communication data on Process Bus is comparatively bigger than that of Station Bus, it is very important for the evaluating the performance of Process Bus to analyze the transferring speed and quality of data from the first equipment, which is located on process level, to station level. According to the results of related studies, it is said that the most important factor for the design and operation of Process Bus network is the communication delay with consideration of the volume of packets. In the paper, the results of performance test for the network with and without application of VLAN on Process Bus system that uses integrated IEDs are presented. Additionally, the paper proposes the optimal method to analyze the communication delays of network systems through evaluating the maximum delay time, link process ratio and the amount of lost packets by using a simulation tool.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.522-525
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• 2006

Recently, mobile devices support multi-functions such as 3D game, wireless internet, moving pictures, DMB, GPS, and PMP. Bigger size of display device is indispensable to support these functions and higher speed of the interface is needed. However, conventional parallel interfaces between processor and display nodule are not competent enough for that high speed transfers. High-speed serial interface is beginning to appear as an alternative for parallel interface. The advantages of the serial interface are high bandwidth, small number of interconnections, low-power consumption, and good quality of electro-magnetic interference. In this paper, we implement serial interface and use it for a display module. LVDS is used for PHY layer and a defined packet is used for link layer. The feature of the implemented serial interface is the reduced number of interconnections with enough bandwidth.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.459-465
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• 2014

Recently, multimedia data transmission becomes important issues in the wireless sensor network. For the multimedia data transmission in wireless sensor network, QoS (Quality of service) is an important factor to determine the system performance. AODV algorithm is one of the widely used algorithm for wireless ad-hoc environment. In AODV, the destination node selects the route with the smallest hop count. Since AODV only considers the hop count, the selected route could have low channel condition, and degrade QoS. In this paper, we propose a modified AODV algorithm that considers the successful transmission rate of each link. The proposed algorithm regards the number of retransmission which can be obtained from the successful transmission rate as the hop count, and applies the modified hop count to AODV. The advantage of the proposed algorithm is that the modified AODV can support QoS without significant change of the conventional algorithm.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.1
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• pp.68-81
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• 2000

CORBA Trader Service is to locate appropriate objects that provide the desired functionality at runtime. To provide this service, the Trader Service federates a local trader and remote traders by considering the Traders or Link policies, and it returns the service offers that are requested by the importer. This traditional way of trading reveals a performance problem due to the low response time. The response time largely depends on the amounts of service offers of the Importer's request and the frequency of federations with the other trader. The performance is a key factor for evaluating the Trader Service performance.In order to overcome the low response time and to provide the high-quality services, we propose new policies of Import and Trader, and present a PUTS(Push Trader Service) model which implements this new advanced trader service. We present the design and implementation of the PUTS's major modules, also make a comparison between PUTS system and traditional trader system in terms of performance and functionality through case studies.