• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1541-1545
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• 2009

홍수 기간 중 부유잡목에 의한 수위상승 원인은 크게 상류부에서 이송되어진 유송잡물에 의한 교량 등의 수공구조물에 집적으로 인한 통수능 부족에 의하여 발생되는 수위상승과 하천내 수공 구조물의 부적절한 설계 및 시공으로 인한 수위상승으로 구분되어 진다. 현재 교량의 여유고 산정에 사용되는 홍수위는 통수능을 고려하지 않은, 하천정비계획에 사용되는 홍수위를 적용하고 있으며, 다만 통수능의 확보를 위하여 경간장에 대한 제한을 두고 있을 뿐이다. 중소하천에 위치하는 교량의 경우, 여유고 확보에 대한 기준을 적용함에 있어서 교량이 위치한 하천 단면에서의 통수능의 영향이 고려되어야 유수의 월류에 대한 위험성을 줄일 수 있다. 더욱이 하천설계기준(2005)에서는 고정 홍수량에 의한 여유고 산정치를 제안하고 있을 뿐이기 때문에, 하천설계기준에서 교량과 관련된 여유고도 하상변동과 만곡부에 의한 수위 상승, 유송잡물에 의한 통수능 영향, 계산오차 등을 고려하여 충분한 여유고를 확보하도록 보완할 필요가 있다. 본 연구에서는 부유잡목에 의한 수위상승 원인을 분석을 하고, 이에 따른 수리모형실험을 통하여 부유잡목의 높이/폭(H/B)변화에 의한 수위상승, 부유잡목의 형태별 수위상승, 교각사이 개도비에 따른 수위 상승량을 산정하여 기존의 여유고에 대한 추가적인 여유고를 확보하여 홍수시 통수능을 확보하고자 하였다. 부유잡목의 형태에 따른 수위상승량을 산정하기 위하여 개도비를 70%로 고정한 후, Fr수를 변화시켜 부유잡목의 높이/폭(H/B) 형태에 따라 산정한 결과, 부유잡목이 존재하지 않는 상태에 비하여 부유잡목에 의한 영향으로 인한 수위증가율이 Fr값이 클수록 더욱 크게 나타났으며, 부유잡목이 동일면적인 경우 폭(B)에 비하여 높이(H)가 커질수록 수위 상승이 크게 나타났다. 또한, Fr수 변화에 따른 최고수위 상승율을 구하였을 때, 상류조건에서 Fr < 0.5 인 경우는 기존 여유고에 대하여 최대 10%의 여유고를 추가 확보하며, 0.5 < Fr < 1 인 경우는 기존 여유고에 대하여 최대 20%의 여유고를 추가 확보하도록 설계하는 것이 바람직하다.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.5
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• pp.857-864
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• 2020

The multi-functional VoIP phone supports the Ethernet protocol in the TIPS(: Tactical IP Switch), which is one of the sub-systems of the tactical information and communication system (TICN). It provides secured voice / video calls in conjunction with VoIP exchanges and supports differential services such as multi-party calls and command functions. In this paper, improving methods have been proposed to reduce power supply defects in the field of multi-functional VoIP phones. The power supply part was improved by applying TVS of the output voltage inlet of the dedicated adapter of the multi-functional VoIP phone, TVS of the PoE module input, adding blocking diodes, and adding DC / DC converters behind the poly-switch. Also, functional and environmental tests were performed to verify the validity of the proposed methods.

• Journal of Korea Multimedia Society
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• v.15 no.5
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• pp.639-650
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• 2012

In 2009, Tsai et al. proposed reversible image hiding scheme using linear prediction coding and histogram shifting. Tsai et al.'s scheme improved the hiding capacity of Ni et al.'s scheme by using the prediction coding and two histograms. However, Tsai et al.'s scheme has problems. In the prediction coding, the basic pixel is not used from embedding procedure. Many additional communication data are generated because two peak and zero point pairs are generated by each block. To solve the problems, this paper proposes a novel reversible data hiding scheme based on modulo operation and histogram shifting. In experimental results, the hiding capacity was increased by 28% than Tsai et al.'s scheme. However, the additional communication data was decreased by 71%.

• 한국해양학회지
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• v.23 no.1
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• pp.1-12
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• 1988

To clarify the community structure of phytoplankton in the Kyeonggi Bay, the community analysis were performed to investigate the relationship between the environmental factors and the phytoplankton communities. Low diversity with occurrence of few dominant species throughout the year, except summer, implies that ecological environment of this study area is very unstable due to incessant physical perturbation and large fluctuation of other environmental factors. According to the results of the cluster analysis this study area could be divided into river discharge, polluted and unpolluted area. Principal component analysis of overall phytoplankton community in this area clearly showed four seasonal succession patterns grouped into the spring type, the summer type, the late summer type, the late autumn-winter type. Summer communities composed of common phytoplankton are highly correlated with temperature and transparency. Winter communities composed of most tychopelagic plankton are positively correlated with suspended substances and nutrient, while negatively correlated with transparency.

• Journal of Food Hygiene and Safety
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• v.14 no.4
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• pp.422-427
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• 1999

Antimicrobial activity of Korean leek was effective on Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, E. coli O157:H7, Pseudomonas fluorescens, Pichia membranaefaciens. Extract from raw Korean leek and that from frozen one showed antimicrobial activity; in contrast, extract stored frozen condition or extract from blanched one lost antimicrobial activity. Filtration, centrifugation, and vacuum concentration did not affect antimicrobial activity of the leek, nor did the changes in storage pHs. Addition of ground leek to soy milk, soy curd, and broth for cold noodle resulted in the prolonged shelf life by significantly reducing the number of viable cells.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1310-1318
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• 2012

This study presents a new system that can make up for the decrease in identification rate due to the environmental or physical factors of a fingerprint identification system, which is most actively used among existing biometric systems. Considered most usable in life among many types of biometrics due to the convenience of use, smaller initial investment, and the smaller size, fingerprint identification is widely used in diverse applications. However, a fingerprint identification system has several defects, including environmental factors, physical skin damage, and variable sensor contact, lowering the identification rate in comparison to other biometric systems. On the basis of the existing fingerprint system, this study presents a more efficient system that can improve the identification rate by getting additional biometric information and three-dimensional finger type information through the use of simple and inexpensive additional equipment, which can be used in diverse areas.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.807-811
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• 2007

In this paper, we introduce an application virtualization method that could be supported without changing and modifying any resources and execution environment on host system, using non-installable portable software format that could be executed by one-click on any host without installing process. For the purpose of designing and implementing an application virtualization method, we construct virtual supporting system that includes virtual file system and virtual registry hive on kernel level of Windows operating system. Also, when users execute portable software on any hosts to provide consistency on using portable software, we describe method of processing information of appending and modifying files and registry datum on virtual file system and virtual registry hive through Copy-on-Write scheme.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.127-130
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• 2015

ITU-R has conducted a studies for the frequency allocation to the maritime mobile satellite service (MMSS) in the 7375 - 7750 / 8025 - 8400 MHz under WRC-15 agenda item 1.9.2. In order to allocate a certain frequency bands to the new service, compatibility between new service and the existing services is ensured taking into account protecting the existing services form interference of new service. In this paper, we present current studies results of the frequency sharing studies between new allocation to MMSS and the existing services in the ITU-R. In addition, some proposals for allocating the 7/8 GHz frequency bands to MMSS are also considered for efficient spectral utilization with respect to preparing WRC-15.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.31-41
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• 2016

A computer program that simulates electric utility steam condensers was developed, and used to investigate the effects of enhanced tubes in steam condensers. The replacement of smooth tubes with enhanced tubes reduces the steam condensing temperature, and increases the efficiency of the electric utility. Therefore, a significant amount of power may be reserved without any modification of the utility. Three enhanced tubes, corrugated, low fin with internal ribs, and low fin with internal 3-D roughness, were considered. The results showed that there is an optimal internal roughness height. Low fin tubes with a 3-D roughness were superior to the other enhanced geometries. This was attributed to longitudinal vortices generated between the circumferential dimples. An additional 0.5 MW~1.3 MW was possible when smooth tubes were replaced with enhanced tubes in the 600 MW electric utility condenser. The additional power increased with increasing coolant temperature. More investigations on fouling, corrosion, and mechanical properties will be necessary for actual applications of enhanced tubes in electric utility condensers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2252-2258
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• 2016

CCMP(centralized conferencing manipulation protocol) enables adding and removing conference participants, changing their roles, adding and removing media streams in conference system. In this paper, by using extended CCMP, a new distributed conference system architecture which can be used to multiple servers distributed conference system in SIP(session initiation protocol) environment has been presented. In this study, according to increasing number of participants, a new extended CCMP architecture which can distribute conference system loads to multiple servers dynamically to decrease loads of servers has been designed. This extended CCMP architecture also can add dynamically new servers from the prepared servers pool. Furthermore, new conference information data format which can represent extended CCMP has been designed, and exchange procedures of extended CCMP control messages which can distribute loads between servers have also been presented. The performance of the proposed system has been analysed by simulation.