• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.85-91
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• 2013

Recently, the weight of high-quality multimedia contents is explosively growing out of the network total traffic. This steep increase of media contents to require huge traffic does not contribute to the generation of revenue streams and it leads to the situation of dumb pipe to trouble network providers into the big burden of investment on the network expansion. Accordingly, the transfer to the smart network to enable the effective delivery of large-scale media is imminently challenging issue to the network providers to seek the profitable business. The smart network revolves around the technologies to enhance end-to-end quality and fair usage with network resources and to optimize the traffic for the contents delivery over the concept of Content-Centric Network. In this paper, we propose an architecture and fundamental functions suitable for the smart network and suggest improved test results through the construction of an experimental network.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.51-56
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• 2014

Thesedays, there are many smart device applications developed, especially on the using various sensors included in the smart device. Smart devices have several sensors which are camera, GPS, mike, and communication module for collecting ubiquitous environment, and many applications are developed by using such sensors. In this paper, we developed the multimedia stream architecture and examined the smart device applications based on open source with front and back-end server clouds for developing the conceptual architecture. Also, we examined the back-end distributed servers, realtime multimedia stream transferring, multi-media store, and media relay for other server and smart devices. We test the examined architecture on the real target environment to collect the SIP initial setup time, media stream delay, and end-to-end play time. The test results show that there have good network operation environment to provide realtime multimedia services, and we need to improve the end-to-end play time by minimizing the initial setup time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6C
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• pp.626-633
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• 2009

ISO/IEC/WD 24753 defines new modem specifications for a long-range RFID communications and application protocol for a sensor tag system. According to the standard, the frequency offset of the tag is 4%. In general wireless communications systems, it is known that a coherent receiver is superior to a non-coherent receiver. However, if the frequency offset is large, it is difficult to restore the original data accurately with a coherent receiver, and the performance of a coherent receiver is easily degraded. In this paper, a non-coherent receiver structure is adopted to solve the frequency offset problem of long-range RFID communications. We designed a frequency estimation block to find an optimal frequency from the received signal with 4% frequency offset and proposed a start frame delimiter (SFD) detection algorithm to determine the start position of the payload. The frequency estimation block finds the optimal frequency from the received signal using 9-correlators. And the SFD detection block searches the received signal to find the start position of the payload with dual correlator. We implemented a long-range RFID reader with the proposed methods and evaluated its performance in a wired/wireless test network. The implemented long-range RFID reader showed more superior performance than the commercial RFID reader in terms of recognition range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3610-3616
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• 2011

Electrical Railroads provide electric power, which can operate vehicles, via feeder wires. And the supplied current returns to the transformer substation through lines and ground net. The used load current depending on the operation of rail vehicles in the electric railway sections returns to the substation through a track which is a return circuit. The load current contains harmonics because of the power conversion equipment used in rolling stocks and such harmonic currents should not affect train control system. In this paper we present the test result in order to verify that the harmonics produced by the operation of rail vehicles in the newly built electric railway sections can affect interlocking systems. The test in question was performed in a linking section that trackside equipment under railway operating conditions and interlocking are linked in order to identify whether or not the interlocking fitted in a signal machine room can be affected by harmonics according to railway operation.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.135-141
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• 2013

Subway in Korea, most of a metropolitan public transport use only worth ten million people a day floating population of wireless communication can be considered HOT SOPT. These three operators' 2G/3G/4G / Wi-Fi / T-DMB frequency and the number of services to co-exist, and the subway train passengers and subway party for operation and management of the communication network is also the co-subway passenger safety and for this service for the effects of mutual interference of whether the verification was necessary. This research and testing different frequency / communication interference between services and testing to determine whether, through the subway authorities and mobile operators in each frequency-specific interaction check and there is no interference to the safety and quality of subway passengers communication services that can be verified as the data was found. The verification methods in the metro area, not just from one region to determine whether the interference with a common verification methods can be applied.

• Polymer(Korea)
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• v.24 no.2
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• pp.201-210
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• 2000

To determine the effect of chain length of linear amine curing agents on the thermal and mechanical properties, standard epoxy resin, diglycidyl ether of bisphenol A (DGEBA) was cured with diethylenetriamine (DETA), triethylenetetraamine (TETA) and tetraethylenepentaamine (TEPA) in a stoichiometrically equivalent ratio. From this work, the effect of linear amine curing agents on the thermal and mechanical properties was significantly influenced by chain length of curing agents. In contrast, the results showed that the DGEBA/DETA system had higher values than the DGEBA/TETA and DGEBA/TEPA system in the density, shrinkage (%), thermal expansion coefficient, tensile modulus, and flexural strength. Whereas the DGEBA/DETA cure system had lower values than the DGEBA/TETA and DGEBA/TEPA cure system in the maximum exothermic temperature, conversion (%), and T$_{g}$. These findings imply that the differences in the maximum conversion about the chain length of curing agents affect the thermal and mechanical properties.s.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.40-44
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• 2009

지하구는 도시의 신경망이라 할 수 있는 통신, 전력, 상수도, 난방, 쓰레기 처리시설 등 도시 운용/관리를 위한 주요시설물을 안전하게 수용하고, 유지 관리하기 위한 시설로 IT기술을 이용하여 수용된 시설을 효과적으로 유지/관리하고, 재난으로부터 안전하게 보호함과 동시에 최소의 비용과 에너지로 수용된 시설물을 유지관리하기 위한 연구가 많이 진행되고 있다. 따라서 본 논문에서는 지하구(공동구, 통신구, 전력구)의 운용 및 유지관리와 지하구에서 발생될 수 있는 각종 재난에 대응하기 위한 지하구 운용 및 유지관리에 대해 알아보고, 지하구 내부에 수용된 시설물을 효과적으로 유지관리하고 재난에 신속히 대응하기 위한 지하구 환경모니터링 시스템에 대해 기술 하고자 한다. 지하구 환경모니터링 시스템은 지하구 내부에는 전력, 상수도, 통신, 난방 등 다양한 시설물이 수용되어 있으며, 이러한 시설물의 부식, 고장 등으로부터 보호하기 위해 지하구내부의 환기시스템의 송풍기와 지하수와 기상재해로 인한 지하구 및 수용시설물의 침수를 막기 위한 양수펌프에 대해 실시간 상태모니터링 통해 송풍기 및 펌프의 고장여부를 판단하여 관리자에게 알림으로써 관리자가 신속하게 대응 할 수 있도록 하였다. 송풍기의 제어는 지하의 내부와 외부에 설치된 온/습도 센서를 통해 지하구 내부환경을 최적으로 유지할 수 있도록 함으로써 쾌적한 지하 내부환경 유지하고, 급/배기가 필요할 경우에만 송풍기를 가동함으로써 에너지를 절약 할 수 있으며, 화재, 침수 등에 대한 재난시 환풍기의 급/배기, 정지 등을 신속하게 제어할 수 있도록 하였다. 또한 지하구내부에서 발생된 재난을 유/무선을 이용하여 신속하게 지하구 주변의 장치(U-Pole 또는 통합컨트롤러)를 통해 경보를 전파함으로써 주변 시민들이 안전하게 대피할 수 있도록 하였다. 그리고 지하구 환경모니터링 시스템을 검증하기 위해 실제 지하구 및 실험실에 시스템 및 Test Board을 설치하여 운용시험을 실시 하였다.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.75-81
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• 2000

The anisotropy of soils has an important effect on stress-strain behavior. In this study, an attempt has been made to implement artificial neural network model for modeling the stress-strain relationship and predicting the undrained shear strength of normally consolidated clay with varying consolidation pressure ratios. The multi-layer neural network model, adopted in this study, utilizes the error back-propagation loaming algorithm. The artificial neural networks use the results of undrained triaxial test with various consolidation pressure ratios and different effective vertical consolidation pressure fur learning and testing data. After learning from a set of actual laboratory testing data, the neural network model predictions of the undrained shear strength of the normally consolidated clay are found to agree well with actual measurements. The predicted values by the artificial neural network model have a determination coefficient$(r^2)$ above 0.973 compared with the measured data. Therefore, this results show a positive potential for the applications of well-trained neural network model in predicting the undrained shear strength of cohesive soils.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.73-80
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• 2011

In this paper, we design and implementation of effective remote management system for VoIP(Voice over IP) terminal. Ordinary VoIP terminal is connected inside of NAT(Network Address Translation) assigned private IP address. NAT provides address mapping between outside public IP address and inside private IP address, for outside system telephone call is connected to inside VoIP terminal. In this paper, we also design and implementation of UDP hole punching function that the outside calls pass through the NAT, for outside management system call is connected to internal VoIP terminal, and gathered to management information of the VoIP terminal. Also, we evaluated and analysed of developed system in the test environment. As a result of test, It showed that it was well performed without any data error and data loss in the connectivity, and It showed that it was well gathered management information of the VoIP terminal.

• Korean Aquaculture
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• v.14 no.2
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• pp.52-65
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• 2002

비단가리비의 인공 종묘 생산을 목적으로 전라남도 신안군 대흑산도 주변에 서식하는 비단가리비를 대상으로 인공 종묘 생산을 위한 산란 유발, 수정란의 발생 과정, 유생 사육, 채묘 및 중간 육성 등 양식 생물학적 연구를 실시하였다. 어미의 각종 산란 유발 자극에 대한 반응은 Serotonin 주사, 온도 자극, 혼합 자극에서 반응율이 가장 높았으며, 자외선 조사 해수 자극은 수컷만 반응을 하였고 간출 자극은 반응이 없어 실효성이 없는 것으로 나타났다. 수정란의 크기는 $69.5{\mu}m$이었고, 수정 후 약 2시간에 2 세포기, 8시간 후에 8 세포기, 20시간 후에는 담륜자 유생으로 부화하였으며 40시간 후에는 D상 유생으로 되었다. 수온별 비단가리비 유생의 성장은 수온 $20^{\circ}C$에서 각장 $178.9{\mu}m$로 가장 좋았으며, 이 때의 생존율은 15.5%이었다. 그러나 수온 $15^{\circ}C$에서는 낮은 성장을 보여 각장 $135.9{\mu}m$로 성장하였으며, 생존율도 9.8%로 저조하였다. 수용 밀도별 사육 시험에서 $1m{\ell}$당 1개체와 5개체에서 성장 및 생존율이 양호하여 성장 및 생존율을 볼 때 적정 사육 밀도는 $1m{\ell}$당 5개체 이하로 나타났다. 먹이 생물 종류에 따른 유생의 성장을 알기 위하여 I, gal-baba, C, calcitrans, N, oculata를 단독 또는 혼합으로 공급하였을 때 실험 종료후 각장의 성장은 I, galbana+C. calcitrans+N. oculata구가 $194.2{\mu}$로 가장 좋았고 N. oculata구는 $162.2{\mu}m$로 가장 낮은 성장을 보였다. 생존율에서는 I. galbana+C. calcitransoculata구는 9.4%로 가장 낮은 생존율을 보였다. 채묘기별 유생의 부착률은 염화비닐판을 수평으로 놓은 것과 패각이 각각 3.43%와 3.17%로 가장 양호하였으나, 양파망과 염화비닐판을 수직으로 놓은 것은 각각 1.52%와 1.61%로 비교적 저조하였다. 수정 후 40일째부터 90일째까지 측정한 부착치패의 경과 일수에 따른 각장의 성장은 $SL=184.44e^{0.0335X}(r^2=0.9861)$의 회귀직선식으로서 나타났다. 중간육성 시험에서 수심별 성장을 분석한 결과, 비단가리비 치패는 저층보다 표층이 각장 5.92mm, 전중량 6.07g 정도 더 빨리 성장하였다.