• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.183-186
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• 2007

Realistic deformation of computer simulated anatomical structures is computationally intensive. As a result, simple methodologies not based in continuum mechanics have been employed for achieving real time deformation of virtual reality. Since the graphical interpolations and simple spring models commonly used in these simulations are not based on the biomechanical properties of tissue structures, these "quick and dirty"methods typically do not accurately represent the complex deformations and force-feedback interactions that can take place during surgery. Finite Element(FE) analysis is widely regarded as the most appropriate alternative to these methods. However, because of the highly computational nature of the FE method, its direct application to real time force feedback and visualization of tissue deformation has not been practical for most simulations. If the mathematics are optimized through pre-processing to yield only the information essential to the simulation task run-time computation requirements can be drastically reduced. To apply the FEM, We examined a various in verse matrix method and a deformed material model is produced and then the graphic deformation with this model is able to force. As our simulation program is reduced by the real-time calculation and simplification because the purpose of this system is to transact in the real time.

• Journal of the Korean Society of Industry Convergence
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• v.16 no.1
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• pp.21-26
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• 2013

Burned gas of methane-air mixtures with water vapor have been analysed to study the exhaust emission using gas-chromatography and computation. The computations were carried out for the gas analysis using premix code of Chemkin program to compare the experimental results. The quantity of water vapor contained were changed 5% and 10% of total mixtures, and equivalence ratio of mixtures between 0.6 and 1.2 were tested under the ambient temperature 323K and 373K. The results showed CO, $CO_2$ decreased and $H_2$ increased by increasing the water contents. The CO increased and $CO_2$ decreased by increasing the ambient temperature. The $CO_2$ shows the maximum product at equivalence ratio 1.0, in otherwise the $CH_4$ produced the minimum values in the same range. The results showed little difference between these two methods.

• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.88-93
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• 2011

Due to vulnerable authentication scheme of SIP, intruders can easily impersonate legitimate user. HTTP Digest authentication scheme or private key issued by trust third parties has been used to prevent impersonation attack. However, these methods have suffered security vulnerability or service delay due to computation overhead. In this paper, we propose new authentication method to generate automatically one-time password using the pre-shared password and time information of messages exchanged between SIP UA(User Agent) and SIP Registrar. This method protects against impersonation attack without significant modification of exiting SIP authentication procedure to build securer SIP environment.

• The Journal of the Acoustical Society of Korea
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• v.10 no.3
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• pp.31-36
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• 1991

We propose an efficient pre-classification algorithm extracting candidate words to reduce the recognition time in a large-vocabulary recognition system and also propose the use of spectral and temporal smoothing of the observation probability to improve its classification performance. The proposed algorithm computes the coarse likelihood score for each word in a lexicon using the observation probabilities of speech spectra and duration information of recognition units. With the proposed approach we could reduce the computational amount by 74% with slight degradation of recognition accuracy in 1160-word recognition system based on the phoneme-level HMM. Also, we observed that the proposed coarse likelihood score computation algorithm is a good estimator of the likelihood score computed by the Viterbi algorithm.

• The KIPS Transactions:PartD
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• v.12D no.3 s.99
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• pp.499-506
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• 2005

A hash chain is a structure organized by hash function with high speed in computation. Systems using the hash chain are using extensively in various cryptography applications such as one-time passwords, server-supported signatures and micropayments. However, the most hash chain based on the system using pre-paid method provides anonymity but has the problem to increase payment cost. In this paper, we propose a new hash chain based on the micropayment system to keep user anonymity safe through blind signature in the withdrawal process of the root value without disclosing privacy information, and to improve efficiency by using secret key instead of public key in the system without the role of certificate.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.550-556
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• 2016

Polar codes are one of the most favorable capacity-achieving codes due to their simple structure and low decoding complexity. However, because of the disappointing decoding performance realized using conventional successive cancellation (SC) decoders, polar codes cannot be used directly in practical applications. In contrast to conventional SC decoders, list SC (SCL) decoders with large list sizes (e.g. 32) achieve performances very close to those of maximum-likelihood (ML) decoders. In SCL decoders with large list sizes, however, hardware increase is a severe problem because an SCL decoder with list size L consists of L copies of an SC decoder. In this paper, we present a low-area SCL decoder architecture that applies the proposed merged processing element-sharing (MPES) algorithm. A merged processing element (MPE) is the basic processing unit in SC decoders, and the required number of MPEs is L(N-1) in conventional SCL decoders. Using the proposed algorithm reduces the number of MPEs by about 70% compared with conventional SCL decoders when the list size is larger than 32.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.3
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• pp.264-271
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• 2013

A method of multiple transport-aircraft mission modeling is proposed in order to improve the efficiency of evaluating and optimizing pre-mission plans. To deal with the challenge of multiple transport-aircraft missions, the object-oriented modeling method is utilized. The elements of the mission are decomposed into objects and businesses, And the major mission objects and their important properties are summarized. A complex mission can be broken down into basic business modules such as the ground section and flight section. The business models of loading and fueling services in the ground section are described. The business model of the flight section is composed of an air route and flight profile with the flight equation and the fuel consumption model. The logical relationship of objects and business modules is introduced. The architecture of the simulation system, which includes a database, computation module, graphical user interface (GUI) module, and a result analysis module, is established. A sample case that includes two different plans is provided to verify the model's ability to achieve multi-aircraft composite mission simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.5
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• pp.1817-1827
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• 2014

As a new type of wireless network, Ad hoc network does not depend on any pre-founded infrastructure, and it has no centralized control unit. The computation and transmission capability of each node are limited. In this paper, a self-updating one-time password mutual authentication protocol for Ad hoc network is proposed. The most significant feature is that a hash chain can update by itself smoothly and securely through capturing the secure bit of the tip. The updating process does not need any additional protocol or re-initialization process and can be continued indefinitely to give rise to an infinite length hash chain, that is, the times of authentication is unlimited without reconstructing a new hash chain. Besides, two random variable are added into the messages interacted during the mutual authentication, enabling the protocol to resist man-in-the-middle attack. Also, the user's identity information is introduced into the seed of hash chain, so the scheme achieves anonymity and traceability at the same time.

• ETRI Journal
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• v.38 no.6
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• pp.1074-1084
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• 2016

This paper presents a transmission method for improving human body communications in terms of spectral efficiency, and the performances of bit-error-rate (BER) and frame synchronization, with a highly simplified structure. Compared to the conventional frequency selective digital transmission supporting IEEE standard 802.15.6 for wireless body area networks, the proposed scheme improves the spectral efficiency from 0.25 bps/Hz to 1 bps/Hz based on the 3-dB bandwidth of the transmit spectral mask, and the signal-to-noise-ratio (SNR) by 0.51 dB at a BER of $10^{-6}$ with an 87.5% reduction in the detection complexity of the length of the Hamming distance computation. The proposed preamble structure using its customized detection algorithm achieves perfect frame synchronization at the SNR of a BER of $10^{-6}$ by applying the proposed pre-processing to compensate for the distortions on the preamble signals due to the band-limit effects by transmit and receive filters.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.165-170
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• 2004

공간 데이터 웨어하우스에서 구축기는 의사절정을 위한 기반 데이터의 구축을 담당한다. 일반적으로 공간 데이터 웨어하우스의 데이터 적재는 잦은 갱신으로 인한 서버의 부하를 줄이기 위하여 구축기에 적재할 데이터를 임시 저장하고 일정주기마다 적재하는 방법을 이용한다. 이때 구축기의 정보는 차원테이블에 대한 갱신정보와 사실 테이블의 일부 갱신정보만을 유지하므로 여러 차원 테이블로 구성된 사실 테이블의 갱신은 공간 데이터 웨어하우스 서버에서 수행해야 한다. 사실 테이블의 갱신연산은 연관된 차원 테이블들에 의해 처리되므로 높은 처리 비용이 필요하다. 따라서 사실테이블의 처리로 인해 적재시간이 증가하며, 이는 사용자의 의사결정 응답시간을 증가시킨다. 본 논문에서는 공간 데이터 웨어하우스의 구축기에서 사실테이블의 사전 계산 기법을 제안한다. 이 기법은 차원 테이블 및 사실 테이블에 대한 메타정보와 추가적으로 기록되어야할 데이터 정보를 구축기에 유지한다. 구축기는 이 정보를 이용하여 삽입 연산시 사실 테이블에 적재할 갱신 정보를 사전에 계산하고, 이를 적재주기에 함께 적재한다. 따라서 사실 테이블의 신을 데이터 적재 이전에 구축기에서 계산하므로 공간 데이터 웨어하우스 서버에서 발생하는 높은 처리 비용을 감소시킬 수 있다. 공간 데이터 웨어하우스 사용자의 의사결정 응답시간을 감소시킨다.