• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.483-486
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• 2001

Home Networking is the last connection point for global information and telecommunication infrastructure establishment. Information infrastructure has been constructed to matured extent so far, and then the enhancement of data transferring performance and high speed capacity in houses tame to the problem to solve as the last communicating area. In addition, to hold such communicating rapacity in houses, the customer premises technology is important as the framework. In this paper, introducing various home networking technologies, prospect of premise technology is reviewed.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.3
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• pp.104-112
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• 1997

Line heating process has been used in forming hull surfaces long before and it has depended on skillful workers. As the reduction of production cost is major concern of shipbuilding companies, line heating work must be improved for higher productivity. In this paper, as the first step to automatic hull forming, a method is proposed to predict deformations due to line heating. It includes a simplified thermal elasto-plastic analysis to increase computing efficiency and to do real time visualization of deformed shapes. For the prediction of deformation, a method to estimate heat flux of the torch is also introduced. Predicted deformations for line heated plates show good agreement with experimental results. The proposed method can be used in control and simulation of line heating process with ease.

• 정보화사회
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• s.184
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• pp.28-39
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• 2007

IT산업은 항상 끊임없는 '혁신'을 통해서만 성장의 자양분을 얻는다. 기술적 또는 개념적 진보가 없다면 IT산업은 당연히 산업으로서의 존재가치가 없다. 그렇다면 2007년, 한국의 IT시장을 주도할 '10대 핵심 IT기술'들은 어떤 것들일까. 국내 통신 및 네트워크, 솔루션 업계가 가장 관심 있게 지켜보는 IT기술등 중 10개를 선별했다. 10대 IT기술에 포함된 것들 중에는 개념적으로는 10년전부터 출현해 알려져 있지만, 그동안 단순히 개념에 머물렀을 뿐 아직 상용화가 안 된 것들도 일부 포함돼 있다. 참신성보다는 실질적인 의미와 중요성에 무게들 둔 때문이다. 2007년에 주목할 만한 10대 IT기술로는 먼저 'IP 멀티미디어 서브시스템(IMS)이 꼽힌다. 유무선을 비롯한 다양한 네트워크를 자연스럽게 연결해주고 여러 서비스들의 다양한 조합이 가능해 고객맞춤형서비스를 가능하게 하는 '멀티미디어 멀티캐스트 컨트롤(MMC)도 10대 IT기술에 포함됐다. 이와 함께 100Mbps 초고속 인터넷 서비스를 가능하게 하는 ETTH (Ethernet To The Home), 차세대 보안이슈인 네트워크접근제어(NAC), 금융회사나 이동통신회사의 상품개발을 신속하게 지원하는 '프로덕트 팩토리', 하드웨어시스템의 최적화를 보장한 가상화 및 ILM, 컴퓨팅산업을 한 단계 이상 진화시킬 쿼드코어 CPU, 소프트웨어 시장의 새로운 패러다임인 SOA(서비스지향아키텍처), 본격적인 시장 확산이 기대되는 전자태그(RFID), IT거버넌스의 열기로 급부상하고 있는 ITAM(IT자산관리) 등도 올해 주목할 10대 IT기술 반열에 올랐다.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.4
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• pp.881-886
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• 2018

Over the last several decades, the advances in computer engineering technology have led a new paradigm of data-intensive research in the field of scientific applications. A collaborative work environment for storing, sharing and analyzing data is required for researchers of geographical distance. The Korean government supports the Research & Education network(KREONET) and the Global Science experimental Data hub Center(GSDC) to strengthen the nation's competitiveness. The KREONET has upgraded its backbone to 100Gbps to accommodate demand to transfer data fast among the global major experimental sites. This paper introduces the test result between high performance nodes reserved for big data transfer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.4
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• pp.337-346
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• 2014

This study aimed to understand the mode characteristics of a droplet subject to periodic forced vibration and the detachment of a droplet placed on a plate surface. An surface was coated with Teflon to clearly observe the behavior of a droplet. The contact angle between the droplet and surface and the hysteresis were found to be approximately $115^{\circ}C$ and within $25^{\circ}C$, respectively. The coating process was performed in a clean room that had an environment with a low level of contaminants and impurities such as air dust, detergents, and particles. To predict the resonance frequency of a droplet, theoretical and experimental approaches were applied. Two high-speed cameras were configured to acquire side and top views and thus capture different characteristics of a droplet: the mode shape, the detachment, the separated secondary droplet, and the waggling motion. A comparison of the theoretical and experimental results shows no more than 18 discrepancies when predicting the resonance frequency. These differences seem to be caused by contact line friction, nonlinear wall adhesion, and the uncertainty of the experiment. For lower energy inputs, the contact line of the droplet was pinned and the oscillation pattern was axisymmetric. However, the contact line of the droplet was de-pinned as the oscillation became more vigorous with increased energy input. The size of each lobe at the resonance frequency is somewhat larger than that at the neighboring frequency. A droplet in mode 2, one of the primary mode frequencies, exhibits vertical periodic movement as well as detachment and secondary ejection from the main droplet.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.118-131
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• 1995

The shock fracture analysis for the structures of navy vessels subject to underwater explosions or of high speed vessels frequently subject to impact loads has been carried out in two steps such as the global or macro analysis and the fine or micro analysis. In the macro analysis, Doubly Asymptotic Approximation(DAA) has been applied. The three main failure modes of structure members subject to strong shock loading are late time fracture mode such as plastic large deformation mainly due to dynamic plastic buckling, and the early time fracture mode such as tensile tearing failure or transverse shear failure. In this paper, the tensile tearing failure mode is numerically analyzed for the micro analysis by calculating the dynamic stress intensity factor $K_I(t)$, which shows the relation between stress wave and crack propagation on the longitudinal stiffener of the model. Especially, in calculating this factor, the numerical caustic method developed from shadow optical method of caustic well known as experimental method is used. The fully submerged vessel is adopted for the macro analysis at first, of which the longitudinal stiffener, subject to early shock pressure time history calculated in macro analysis, is adopted for the micro analysis.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.79-90
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• 2007

Prototype of $800{\ell}$ vacuum web coater (Vic Mama) consisting of ion source with low energy less than 250 eV for high speed surface modification and 4 magnetron sputter cathodes was designed and constructed. Its performance was evaluated through fabricating the adhesiveless flexible copper clad laminate (FCCL). Pumping speed was monitored in both upper noncoating zone pumped down by 2 turbo pumps with 2000 l/sec pumping speed and lower surface modification and sputter zone vacuumed by turbo pumps with 450 1/sec and 1300 1/sec pumping speed respectively. Ion current density, plasma density, and uniformity of ion beam current were measured using Faraday cup and the distribution of magnetic field and erosion efficiency of sputter target were also investigated. With the irradiation of ion beams on polyimide (Kapton-E, $38{\mu}m$) at different fluences, the change of wetting angle of the deionized water to polyimide surface and those of surface chemical bonding were analyzed by wetting anglometer and x-ray photoelectron spectroscopy. After investigating the deposition rate of Ni-Cr tie layer and Cu layer was investigated with the variations of roll speed and input power to sputter cathode. FCCL fabricated by sputter and electrodeposition method and characterized in terms of the peel strength, thermal and chemical stability.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.2
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• pp.127-138
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• 1996

The strip method, unified theory and 3-D panel method are commonly used methods for the seakeeping analysis of high-speed vessels. The strip method which is basically 2-dimensional method is known to give incorrect hydrodynamic coefficients and motion responses for the cases of high speed and low frequency region. And the unified theory which uses two dimensional approach in inner domain and slender body theory in outer domain is very complicate in computational modelling. Though the 3-D panel method requires comparatively long computation time, it is believed that the method gives good results without any limitation in ship speed and range of frequency for computation. In the 3-D panel method the source singularity representing translating and pulsating Green function is used and Hoff's method is adopted for the numerical calculation of the Green function. The computation time can be reduced by using the symmetry relationship with respect to longitudinal axis. In this paper the strip method and the 3-D panel method are compared for the seakeeping analysis of a high-speed catamaran. The Compared items are the hydrodynamic coefficients, wave exciting forces, frequency response functions and short-term responses in irregular waves.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.340-341
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• 2013

양자점(Quantum dots; QDs)은 단전자 트랜지스터, 레이저, 발광다이오드, 적외선 검출기와 같은 고효율 광전소자 응용을 위해 활발한 연구가 진행되고 있다. II-VI 족 화합물 반도체는 III-V 족 화합물 반도체와 비교했을 때 더 큰 엑시톤 결합에너지(exciton binding energy)를 가지는 우수한 특성을 보이고 있으며 이러한 성질을 가지는 II-VI 족 화합물 반도체 중에서도 넓은 에너지 갭을 가지는 CdTe 양자점은 녹색 영역대의 광전자 소자로서 활용되고 있다. 기존의 CdTe/ZnTe 양자점을 성장하기 위해 ZnTe와 격자부정합이 적은 GaAs 기판을 이용한 연구가 주를 이룬 반면 Si기판을 이용한 연구는 미흡하다. 하지만 Si 기판은 GaAs 기판에 비해 값이 싸고, 여러 분야에 응용이 가능하며 대량생산이 가능하다는 이점을 가지고 있어 초고속, 초고효율 반도체 광전소자의 제작을 가능케 할 것으로 기대된다. 또한 양자점의 고효율 광전소자에 응용을 위해서는 Si 기판 위에 양자점의 크기를 효율적으로 조절하는 연구 뿐 아니라 양자점의 크기에 따른 운반자 동역학에 대한 연구도 중요하다. 본 연구에선 분자선 에피 성장법(Molecular Beam Epitaxy; MBE)과 원자층 교대 성장법(Atomic Layer Epitaxy; ALE)을 이용하여 Si 기판 위에 성장한 CdTe/ZnTe 양자점의 크기에 따른 광학적 특성을 연구하였다. 저온 광 루미네센스(PhotoLuminescence; PL) 측정 결과 양자점의 크기가 증가함에 따라 더 낮은 에너지영역으로 피크가 이동하는 것을 확인하였다. 그리고 온도 의존 광루미네센스 측정 결과 양자점의 크기가 증가함에 따라 열적 활성화 에너지가 증가하는 것을 관찰하였는데, 이는 양자점의 운반자 구속효과가 증가하였기 때문이다. 또한 시분해 광루미네센스 측정 결과 CdTe/ZnTe 양자점의 크기가 증가함에 따라 소멸 시간이 긴 값을 갖는 것을 관찰하였는데, 이는 양자점의 크기가 증가함에 따라 엑시톤 진동 세기가 감소하였기 때문이다. 이와 같은 결과 Si 기판 위에 성장한 CdTe/ZnTe 양자점의 크기에 따른 열적 활성화 에너지와 운반자 동역학에 대해 이해 할 수 있었다.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.586-588
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• 2007

The Moore's law states that the number of transistors on a chip doubles about every 18 months. And it was reported that the network speed has been doubled about every 9 months. This indicates that computing power and network is no longer the obstacles for the high performance applications requiring terabits networks. We believe that the application motivates the network and vice versa. This presentation will introduce the GLORIAD which is the first ring network connecting six countries around the world and provides scientists with advanced networking tools that improve a communications and data exchange. The GLORIAD trans-Pacific link started its service on August 1, 2005. Since then, there has been remarkable demonstrations were performed through major conferences like Supercomputing Conference. This paper will introduce the global collaborative works on demonstrations of VMT, high energy physics, SDSS and HD video transmission during SC'06 in Tampa, FL.