• Annual Conference of KIPS
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• 2005.11a
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• pp.1495-1498
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• 2005

오늘날의 MMORPG 환경에서 수만${\sim}$수십만 명의 유저들이 동시 접속하여 게임을 즐기고 있다. 수많은 인원이 같은 맵 상에서 활동하기 때문에 최근의 게임 서버들은 맵의 영역에 따라 유저를 분할하여 처리하고 있다. 이를 위한 방안으로 Seamless 게임 서버 방식이 이슈가 되고 있으며 이 방식에서는 PC의 서버간 이동시 필연적으로 지연이 발생하게 된다. 본 논문에서는 이를 최소화하기 위해 MigAgent 를 이용하여 Field Server간 통신 및 PC와 Field Server간 통신을 효율적으로 관리하기 위한 방법을 제안한다.

• Annual Conference of KIPS
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• 2005.11a
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• pp.917-920
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• 2005

전자문서보관소와 같이 대규모의 전자문서가 저장되는 시스템은 어떤 특정한 방법을 기준으로 해당 데이터를 저장한다. 이는 데이터의 저장, 검색, 송수신, 보안 요소 등 여러 가지 요구사항에서 기인하며, 이를 근거로 설계 되어야 한다. 본고에서는 현재 이슈가 되고 있는 전자문서보관소의 적합한 데이터 저장 방법에 대하여 알아보고 이를 안전하게 관리하기 위한 방법을 접근제어 측면에서 생각하여 보기로 한다.

• Annual Conference of KIPS
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• 2005.11a
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• pp.897-900
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• 2005

본 논문에서는 식별 정보 기반의 비밀 분산 방식을 제안한다. 본 방식에서는 비밀 정보를 분할한 부분 정보에 딜러와 참가자의 식별정보가 포함된다. 각 식별정보는 비밀 분할 및 복원 과정에서 딜러와 참가자, 참가자와 참가자 간 상대방을 인증하는데 사용된다. 또한 참가자 간에는 상호 부분 정보의 송 수신 외에 딜러와의 통신 등 별도의 통신 과정 없이 부분 정보의 검증이 이루어진다.

• Annual Conference of KIPS
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• 2005.11a
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• pp.933-936
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• 2005

인터넷의 발달은 우리 생활에 많은 변화를 가져왔다. 이제는 단순한 통신뿐만 아니라 금융, 경제 분야에 이르기까지 다양한 범위의 활동들이 네트워크에서 이루어지고 있으며 그에 따라 정보보호의 중요성도 증가했다. 네트워크 상에서의 정보보를 위해 현재 대표적으로 VPN 시장에서는 IPSec 기반의 VPN과 SSL 기반의 VPN이 경쟁을 하고 있다. 이에 본 논문에서는 IPSec과 SSL 프로토콜의 성능을 비교하고 다양한 관점에서 성능을 평가한 사례들을 분석한다. 그리고 이를 통해 IPSec과 SSL 프로토콜의 대한 성능평가 도구의 연구 필요성을 제시한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1401-1412
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• 1992

On band limited channel like satellite communication and voice communication. TCM(Trellis Coded Modulation) is a communication method that has coding gain which combines modulation with channel coding without bandwidth expansion. In this paper, we apply PAM, PSK, QAM to TCM, and propose the extended path back method decoding algorithm which improved drawback of viterbi decoding algorithm and apply to TCM this decoding algorithm. Using Monte Carlo simulation, we analyze performance of each modulation technique and efficiency of decoding algorithm.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.7
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• pp.323-331
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• 2000

Recently Advanced Static Var Compensators(ASVC) or STATic Synchronous COMpesator(STATCOM) has been considered as a next generation reactive power controller. The STATCOM is a voltage source inverter(VSI) based on the static VAr compensator with only small capacitors on the dc side. The main function of the STATCOM is to keep the bus voltage magnitude at the desired value. This paper compared the PAM STATCOM with the PWM STATCOM. The characteristics and the control method of each model is analyzed. And the simulation of STATCOMs based on the above two methods is presented.

• The Journal of Korea Robotics Society
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• v.11 no.3
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• pp.140-145
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• 2016

In this paper, we fabricate arrayed-type flexible capacitive touch sensor using liquid metal (LM) droplets (4 mm spatial resolution). Poly-4-vinylphenol (PVP) layer is used as a dielectric layer on the electrode patterned Polyethylene naphthalate (PEN) film. Bonding tests between hydroxyl group (-OH) on the PVP film and polydimethylsiloxane (PDMS) are conducted in a various $O_2$ plasma treatment conditions. Through the tests, we can confirm that non-$O_2$ plasma treated PVP layer and $O_2$ plasma treated PDMS can make a chemical bond. To measure dynamic range of the device, one-cell experiments are conducted and we confirmed that the fabricated device has a large dynamic range (~60 pF).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.975-979
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• 1994

The experimental and finite element studies of a coaxial cylindrical shell filled with liquid in the annular gap were performed to understand its vibration characteristics. Finite element analysis was achieved by using ANSYS code. Form the investigation of the changing trend of natural frequencies for the change of annular gap we know that the natural frequency of the coaxial cylindrical shell varies according to the mode shape. that is, in case of in-phase mode the natural frequency decrease as annular gap increase, but in case of out-of-phase mode the natural frequency increase. Finite element analysis results show the excellent agreement with the experimental results both in air and in water case, so that analysis on other cases with be possible without experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.404-406
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• 2014

The NDIF method is developed for eigenvalue analysis of arbitrarily shaped two-dimensional acoustic cavity with a mixed boundary, which consists of rigid-wall and open boundaries. The NDIF method, which was developed by the author in 2000, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods (FEM and BEM). The validity of the proposed method is shown in a case study, which indicate that eigenvalues obtained by the proposed method are more accurate compared to the exact method or FEM(ANSYS).

• Journal of the Mineralogical Society of Korea
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• v.1 no.1
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• pp.63-69
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• 1988

Chondrodite form the Wondong mine, Korea, which is the first occurrence from the southern Korea, has been studied for its mineralogical characterization. It occurs in close association with penninite, phlogopite, diopside and garnet within the magnetite ore bodies, which are debeloped along the contact of the Hwajeol Formation and rhyolite. Two kinds of chondrodites are recognized by their different optical properties; the high birefringent untwinned one and the low birefringent twinned one. The former has slightly higher Mn content than the latter. Twinning in chondrodite has been formed in close relation to substitution Mg (Fe, Mn) in the humite solid solution, as evidenced by the chemical variation across the twin lamallae.