• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.157-163
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• 2003

IEEE 802.11a Distributed Coordination Function(DCF) Protocol을 사용하여 Real-Time MultiMedia Data의 전송을 수행할 경우, DCF Protocol의 적합하지 못한 Mechanism에 의하여, Data 전송의 극대화를 이루지 못한다. Retransmission이 반복되는 경우, Binary Slotted Exponential Backoff Mechanism은 거대한 Packet Delay와 Jitter의 원인이 되며 Automatic Repeat Request(ARQ) 방식의 Ack Mechanism은 MultiMedia Data를 전송하기에 적합하지 못하다. 본 논문은 위와 같은 문제점을 해결하기 위하여 Real-Time MultiMedia Data을 주로 전송하는 STA에 따른 Real-Time/Non-Real-Time(RT/NRT) Station(STA)의 구분과 보내고자 하는 Real-Time MultiMedia Data의 Network Traffic Load(The Required Bandwidth)를 고려하여, Modified DCF(mDCF) Protocol의 Modified Backoff(mBackOff), Modified BlockAck(mBlockAck) Mechanism을 제시함으로서, Data 전송의 극대화를 제공하며, 또한 IEEE 802.11a와의 호환성을 제공한다.

• The Research Journal of the Costume Culture
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• v.17 no.4
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• pp.723-732
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• 2009

The quick response(QR) system is very popular in Korean apparel companies. However, the usage of QR system was not known well. The purpose of this study is to identify the usage of the quick response decision support system(QR DSS) and postponement manufacturing in the Korean apparel company. The researched company was the only one which used the QR DSS. The researchers carried out the depth interview with the QR decision makers of the company. This company had 14 brands, and had used the QR DSS since January, 2008. The results are as follows: The QR DSS was supportive computer software program, and it helped the staffs to make agile decision about QR repeat production of clothing. The QR DSS automatically calculated the related data, and suggested the expected sales volume and the proper supply amounts of the styles. There were four functions in QR DSS : 'QR Alert', 'Proper Supply Amount Simulation', 'Sensible QR', and 'Supply/Sales Simulation by Item'. The men's clothing brands effectively used 'Supply/Sales Simulation by Item' function. And the women's clothing brands effectively used 'QR Alert' function. This company also used the postponement production system for QR repeat production. The postponement production was conducted with four methods : the yarn stocking, the grey fabric stocking, the dyed fabric stocking, and the fabric sourcing. The men's clothing brands usually used of the yarn stocking methods and the dyed fabric stocking methods. The women's clothing brands usually used the grey fabric stocking methods. By using QR DSS and postponement production system the company was able to shorten the lead time for QR decision making.

• Molecules and Cells
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• v.26 no.1
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• pp.53-60
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• 2008

We characterized the human endogenous retrovirus (HERV-W) family in humans and primates. In silico expression data indicated that 22 complete HERV-W families from human chromosomes 1-3, 5-8, 10-12, 15, 19, and X are randomly expressed in various tissues. Quantitative real-time RT-PCR analysis of the HERV-W env gene derived from human chromosome 7q21.2 indicated predominant expression in the human placenta. Several copies of repeat sequences (SINE, LINE, LTR, simple repeat) were detected within the complete or processed pseudo HERV-W of the human, chimpanzee, and rhesus monkey. Compared to other regions (5'LTR, Gag, Gag-Pol, Env, 3'LTR), the repeat family has been mainly integrated into the region spanning the 5'LTRs of Gag (1398 bp) and Pol (3242 bp). FISH detected the HERV-W probe (fosWE1) derived from a gorilla fosmid library in the metaphase chromosomes of all primates (five hominoids, three Old World monkeys, two New World monkeys, and one prosimian), but not in Tupaia. This finding was supported by molecular clock and phylogeny data using the divergence values of the complete HERV-W LTR elements. The data suggested that the HERV-W family was integrated into the primate genome approximately 63 million years (Myr) ago, and evolved independently during the course of primate radiation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.752-759
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• 2012

This paper presents a mission orbit design method for spacecraft which use the sun-synchronous and ground repeat orbits. In this work, we have proposed a new design procedure, "Nonlinear simulation-based numerical optimization technique" using the commercial S/W's such as STK (Satellite Tool kit) and Matlab, which are widely adopted S/W's in the area of orbital mechanics and engineering analysis. Inclusion of all the perturbation effects on the spacecraft not only can more precisely satisfy the mission requirements for sun-synchronicity and repeated ground track, and also operational requirements such as minimum change in the S/C local time, maximization of the contact time with a specified ground station, etc. can be appropriately considered. Design examples for LEO sun-synchronous mission are presented to demonstrate the usefulness of the proposed method in this paper.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10A
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• pp.1532-1538
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• 1999

In general, because error rate of wireless link is higher than that of wired link, DLC layer protocol for wired network with low error rate is not proper for wireless environments. In addition, the conventional DLC layer protocol for wireless network is optimized for the low-speed data service, so it is difficult to use conventional DLC protocol in the current mobile communication environments handing high-speed and multimedia services. Therefore, a DLC layer protocol that is suitable to current wireless communication environments is required. In this paper, we propose a novel error control scheme that supports a variety of traffic attribute and is applicable to high-speed and multimedia data service in WATM. The proposed scheme provides enhanced throughput performance for real-time traffic by using modified ASR ARQ without ACK and reduces loss rate by using FEC in the case of high error condition. Also, for non real-time traffic, the use of ASR ARQ without ACK enhances throughput performance and delay time is decreased by using FEC in the case of high error rate channel. As a result of simulation, the proposed scheme has better performance than conventional ASR ARQ protocol in view of delay and throughput.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.6
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• pp.401-412
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• 2022

In this study, we investigated the design methods of satellite constellations to conduct near-real-time surveillance reconnaissance of the Korean Peninsula. Also, we designed satellite constellations utilizing the Walker-Delta method and repeat-ground-track method, and taking into account the target area and the feasible number of satellites. The constrains of the Electro-Optical and Synthetic Aperture Radar equipment were also considered in performance analysis. As a result, the designed constellation has mean revisit time of less than 30 min which enables near-real-time surveillance reconnaissance of the Korean Peninsula. This research provides the strategy to design the satellite constellation for reconnaissance. Furthermore, it contributes to suggesting an operating strategy for micro-satellites constellation and guidelines for establishing space force.

• International Area Studies Review
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• v.22 no.4
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• pp.189-208
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• 2018

This study validates if this relationship results in differences of significance levels between first time and repeat visitors and analyzes if there exist any differences in the spatial characteristics of tourist attractions using Social Network Analysis(SNA) for the spacial attributes of movement network Focusing on Hwaseong city, South Korea. It is important for balanced development between tour sites in Hwaseong by enhancing the value of tourism resources and applying the concept of hub-and-spoke tourism development. Based on the analyzing the centrality of tourist movement networks, degree centrality, closeness centrality, and betweenness centrality all did not show much variation for 20 tourist attractions versus the top five. That is, the attractions that both first time and repeat visitors visit are concentrated in well-known, famous places. The authors hope that this study, which defines practical interactions among attractions based movement, will be used as practical data for developing tourist retention marketing strategies.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2005.10a
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• pp.143-146
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• 2005

Human activity pattern has been changed as the contemporary urban society changes. Diverse activities repeat regular patterns as time passes. Diagram is a simple drawing which aims to organize and unify various information. The elements of the social behaviour could be spatialized by means of diagram applications. By using diagrams, architects understand contemporary urban society and form new space conditions. Time-based activity patterns consists of activity pattern in a restricted space and in urban structure for space use. Activity patterns for different time zones are explained by two types of diagrams, space occupation and flexibility of space, By the characteristic of space system structred by these diagrams, activities and programs are rearranged and variety of space is allowed through flexibility. Also, programs are mixed to apply to simultaneous occurrence of ever-changing human activities.

• Journal of the Korean Geosynthetics Society
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• v.11 no.3
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• pp.1-9
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• 2012

If the railways consisting of soil subgrade is applied to repetitive loading, elastic deformation and plastic deformation will occur at the same time. So the repeat traffic loading condition should be considered to predict the long-term deformation on railway roadbed. In this study, laboratory data from the repeated load triaxial tests and cylinder model test were used to predict accumulated settlement on railway foundation and results were analyed based on the nonliear models and stress state considered. It has proposed predict model using power function model on plastic settlement of roadbed materials.

• Journal of Embryo Transfer
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• v.7 no.2
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• pp.89-96
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• 1992

This research was conducted to investigate the interrelationship among methods of injection of PMSG-hCG to the number of ovulated eggs, percentage of matured oocytes and in vitro fertilization using out-bred ICR mice. The results obtained are as follows, 1) The optimurn dose was 5 IU for both PMSG and hCG, while the number of ovulated eggs was 42$\pm$8, percentage of M II was 73% and in vitro fertilization rate was 81 %. 2) The optimum injection interval of PMSG-hCG was 48 hours, while the number of ovulated eggs was 48 $\pm$ 8, percentage of M II was 80% and in vitro fertilization rate was 81%. 3) The optimum time for collecting eggs was between 16 and 18 hours after hCG injection, while the numbers of ovulated eggs were 44$\pm$8, 42$\pm$7 and 43$\pm$7 in 14,16 and 18 hours after hCG injection respectively, and percentages of M II were 79 and 81 %, and in vitro fertilization rates were 81 and 80% in 16 and 18 hours after hCG injection, respectively. 4) The repeat of superovulation decreased with the number of ovulated eggs, percentage of M II and in vitro fertilization rate, than in control. But it was recovered by increasing the repeat interval.