• The Transactions of the Korea Information Processing Society
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• v.5 no.6
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• pp.1639-1651
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• 1998

In this paper, we present analytical and simulation models for evaluating the operation of a uniprocessor computer which utilizes a time redundant approach (such as recomputation by shilted operands) for lault-tolerant computing. In the proposed approach, all incoming jobs to the uniprocessor are duplicated, thus two versions 01 each job must be processed. Three methods for appropriately scheduling the primary and sL'Condary versions of the jobs are proposed and analyzed. The proposed scheduling methods take into account the load and the fault rate of the uniprocessor to evaluate two figures of merit for cost and profit with respect to a delay in response time due to faults and fault tolerance. Our model utilizes a fault-tolerant schedule according to which it is possible to find an optimal delay (given by $\kappa$) based on empiric parameters such as cost, the load and the fault rate of the uniprocessor.

• Annual Conference on Human and Language Technology
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• 2019.10a
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• pp.12-17
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• 2019

FAQ(Frequently Asked Questions) 질의 응답 시스템은 자주 묻는 질문과 답변을 정의하고, 사용자 질의에 대해 정의된 답변 중 가장 알맞는 답변을 추론하여 제공하는 시스템이다. 정의된 대표 질문 및 대응하는 답변을 클래스(Class)라고 했을 때, FAQ 질의 응답 시스템은 분류(Classification) 문제라고 할 수 있다. 종래의 FAQ 분류는 동일 클래스 내 동의 문장(Paraphrase)에서 나타나는 공통적인 특징을 통해 분류 문제를 학습하였으나, 이는 비슷한 단어 구성을 가지면서 한 두 개의 단어에 의해 의미가 다른 문장의 차이를 구분하지 못하며, 특히 서로 다른 클래스에 속한 학습 데이터 간에 비슷한 의미를 가지는 문장이 존재할 때 클래스 분류에 오류가 발생하기 쉬운 문제점을 가지고 있다. 본 논문에서는 이 문제점을 해결하고자 서로 다른 클래스 내의 학습 데이터 문장들이 상이한 클래스임을 구분할 수 있도록 클래스 일치 여부(Class coincidence classification) 문제를 결합 학습(Jointly learning)하는 기법을 제안한다. 동일 클래스 내 학습 문장의 무작위 쌍(Pair)을 생성 및 학습하여 해당 쌍이 같은 클래스에 속한다는 것을 학습하게 하면서, 동시에 서로 다른 클래스 간 학습 문장의 무작위 쌍을 생성 및 학습하여 해당 쌍은 상이한 클래스임을 구분해 내는 능력을 함께 학습하도록 유도하였다. 실험을 위해서는 최근 발표되어 자연어 처리 분야에서 가장 좋은 성능을 보이고 있는 BERT 의 텍스트 분류 모델을 이용했으며, 제안한 기법을 적용한 모델과의 성능 비교를 위해 한국어 FAQ 데이터를 기반으로 실험을 진행했다. 실험 결과, 분류 문제만 단독으로 학습한 BERT 기본 모델보다 본 연구에서 제안한 클래스 일치 여부 결합 학습 모델이 유사한 문장들 간의 차이를 구분하며 유의미한 성능 향상을 보인다는 것을 확인할 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.5
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• pp.1-10
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• 2007

In this paper, we proposed development of improved model reduction and design of common controller using reduction model. The Algorithm of improved model reduction considered the transient response and the steady-state response in response curve. The generalized controller is designed not only to ensure specified phase margin and iso-damping property also optimized smith-predictor controller about real model using reduction model. Simulation examples are given to show the better performance of the proposed method than convention methods.

• Journal of Broadcast Engineering
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• v.12 no.1 s.34
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• pp.28-40
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• 2007

In this paper, we proposes an idea for improved sound characteristic which decreasing a problem in previous reverberation algorism structure. To later reflection sound, proposed new reverberation structure, using a lopped and nested all-pass delay line, and it is designed to improve an natural concert hall sound. In addition, In order to have best imaginary sound effect, we extracted the factors by controlling each delay line's delay time, and we realized a proposed new algorithm by using general-purpose DSP. Through several experimental cases, we observed better effect on improvement of linear flatten and reverberation density and decreasing about colorlessness and non-linear sound at previous proposed model about impulse input.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.66-78
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• 2002

In this paper, we propose a new symbol offset estimation technique for an orthogonal frequency-division multiplexing (OFDM)-based wireless LAN. When both inter-symbol interference (ISI) and inter-channel interference (ICI) do not exist in an OFDM symbol, symbol offsets cause circular shifts in the estimated channel impulse response (CIR) by the amount of symbol offset. Also, the power delay profile of a typical multipath wireless channel can be modeled by exponentially decaying function, and most energy of multipath channel is concentrated at the beginning part of the CIR. Based on these properties, the proposed symbol offset estimation technique estimates the CIR, which is circularly shifted by the amount of symbol offset, and then calculates the partial mean power from the estimated impulse response by using a moving window with a finite length. And, symbol offset can be estimated from the index of a moving window having the maximal partial mean power. The proposed technique can reduce noise effect in the process of the CIR estimation, and remove ISI and ICI using repetitive training symbol structure in time-domain for minimum training overhead. The performances of the proposed symbol offset estimation technique in typical indoor channels are demonstrated by computer simulation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.4 s.310
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• pp.35-44
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• 2006

The network induced transmission delay deteriorates the performance and stability of the real-time distributed control system on LonWorks over IP (LonWorks/IP) virtual device network (VDN). LonWorks/IP virtual device network is an integrated form of LonWorks device network and IP data network. The time delay in servo control on the LonWorks/IP-based VDN has highly stochastic nature. In the real-time distributed servo applications for predictive maintenance on the factory floor, timely response is essential.

• Journal of KIISE:Information Networking
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• v.27 no.2
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• pp.237-246
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• 2000

A broadband access network in B-ISDN subscriber network, plays a role of concentration or multiplexing of various subscribers into a service node. For call and connection control functions, DSS2 and B-ISUP signalling protocols are standardized for each of a subscriber side and a network node. B-BCC and B-ANCC protocol were proposed for VB5.2 interface. This interface allows dynamic control of ATM connections at the broadband access network. To establish an end-to-end ATM connection, interworking functions between VB5.2 interface's connection control protocol and the signalling protocol, are performed at the service node. A sequential interworking model and a parallel interworking model were proposed for these interworking functions. The sequential interworking model recommended by ITU-T causes an overall connection setup delay by introducing the access network, because this model proceeds the signalling protocol of network node after the response of VB5.2 interface protocol. On the other hand, the parallel interworking model proceeds the signalling protocol and the VB5.2 interface protocol simultaneously. The simultaneity of the parallel interworking model minimizes the overall connection setup delay. In this paper, we analyze and simulate above two interworking models with B-BCC or B-ANCC protocol in terms of a connection setup delay and completion ratio.

• 대한공업교육학회지
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• v.31 no.2
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• pp.364-380
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• 2006

This paper presents a procedure for designing command to maneuver flexible structure with very little residual vibration, even in the presence of modeling errors. For the open loop maneuver, the various shaped profiles using multiple step inputs delayed in time are considered for robustness and compared with the responses of rigid body and flexible body in virtue of simulations and experiments. Input shaping generates vibration-reducing shaped commands through convolution of an impulse sequence with the desired command. A flexible model with a cylindrical hub and four symmetric appendages is considered to examine the responses to real plant, and to illustrate the effectiveness of the proposed shapers. The appendages are long and flexible, leading to low frequency vibration under any control action. It is shown by a series of simulation that a properly designed feedback controller with input shaper performs well, as compared with open loop controller with input shaper. The control objective is to achieve a fast settling time of residual vibration to flexible structure and robustness (insensitivity)to plant uncertainty, to eliminate residual vibration.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.26-35
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• 2004

As part of thrust control technology research on turbopump-fed type liquid-propellant rocket engine system, the low frequency dynamic characteristics of turbopump was investigated. It can be described that a turbopump system has a 1st-order lag element. When the value, which was resulted by subtraction of the variation of turbine moment with respect to the variation of revolution number from the variation of pump moment with respect to the variation of revolution number, was positive, the time constant of the 1st-order lag element was positive which stood for a stable system. Increasing the above-mentioned valve within positive range leaded to the increase of response and to the decrease of controllability.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.5-7
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• 2012

This study presents relations between the time lag and interaction index of the impinging-jet injectors using time lag model in a model chamber. To analyze the response of the flame, 5% amplitude of oxidizer velocity is artificially perturbed at a resonance frequency. At the mixing point of fuel and oxidizer, which determines the characteristic length, the relationship between velocity perturbation and heat release rate is quantified by combustion parameters of interaction index and time lag. As the improved method to apply the time-lag, the method using the average velocity obtained from numerical results is suggested.