• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1955-1959
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• 2005

This paper presents a systematic analysis and a simple design of a robust adaptive control law for a class of non linear systems with modeling errors and a time-delay input. The theory for designing a robust adaptive control law based on input- output feedback linearization of non linear systems with uncertainties and a time-delay in the manipulated input by the approach of parameterized state feedback control is presented. The main advantage of this method is that the parameterized state feedback control law can effectively suppress the effect of the most parts of nonlinearities, including system uncertainties and time-delay input in the pp-coupling perturbation form and the relative order of non linear systems is not limited.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.185-187
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• 1995

A boost converter proposed in this paper operates with high power factor due to input current of sinusoidal waveform. If there were no input LPF, the current is got to be discontinuos form in proportion to AC input voltage magnitude under the constant duty factor switching. Thereupon, the harmonics of input current waveform is reduced and the LPF is made with few elaboration and the control circuit is simple. The switching devices in proposed circuit are operated with soft switching by the partial resonant method. The patial resonant circuit makes use of a reactor using step-up and a capacitor of loss-less snubber. The result is that switching loss is very low and efficiency of system is high.

• 대한전자공학회논문지SP
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• 제41권5호
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• pp.283-290
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• 2004

이 논문에서는 MPEG audio 알고리즘의 필터뱅크를 덧셈을 사용하여 저전력으로 구현할 수 있는 구조를 제안하였다. 제안된 구조는 CSD(Canonic Signed Digit) 형의 계수를 사용하며, 입력신호 샘플을 최대로 공유함으로서 사용되는 덧셈기의 수를 최소화하였다. 제안된 구조는 알고리즘에서 사용된 공통입력 공유, 선형위상 대칭 필터계수를 이용한 공유, 공통입력을 이용한 블록 공유, CSD 형의 계수와 공통패턴 공유를 통하여 사용되는 덧셈의 수를 최소화할 수 있음을 보였다. Verilog-HDL 코딩을 통하여 시뮬레이션을 수행한 결과, 제안된 구조는 기존의 곱셈기 구조의 구현면적과 비교하여 60.3%를 감소시킬 수 있음을 보였다. 또한 제안된 구조의 전력소모는 곱셈기 구조와 비교하여 93.9%를 감소시킬 수 있음을 보였다. 따라서 고속의 곱셈기가 내장된 DSP 프로세서를 사용하지 않고도, Arithmetic Unit나 마이크로 프로세서를 사용하여 효과적으로 MPEG audio 필터뱅크를 구현할 수 있음을 보였다.

• Computers and Concrete
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• 제30권3호
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• pp.225-236
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• 2022

In this article, Multi-Gene Genetic Programming (MGGP) is proposed for the estimation of the compressive strength of concrete. MGGP is known to be a powerful algorithm able to find a relationship between certain input space features and a desired output vector. With respect to most conventional machine learning algorithms, which are often used as "black boxes" that do not provide a mathematical formulation of the output-input relationship, MGGP is able to identify a closed-form formula for the input-output relationship. In the study presented in this article, MGPP was used to predict the compressive strength of plain concrete, concrete with fly ash, and concrete with furnace slag. A formula was extracted for each mixture and the performance and the accuracy of the predictions were compared to the results of Artificial Neural Network (ANN) and Extreme Learning Machine (ELM) algorithms, which are conventional and well-established machine learning techniques. The results of the study showed that MGGP can achieve a desirable performance, as the coefficients of determination for plain concrete, concrete with ash, and concrete with slag from the testing phase were equal to 0.928, 0.906, 0.890, respectively. In addition, it was found that MGGP outperforms ELM in all cases and its' accuracy is slightly less than ANN's accuracy. However, MGGP models are practical and easy-to-use since they extract closed-form formulas that may be implemented and used for the prediction of compressive strength.

• 산업융합연구
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• 제22권2호
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• pp.63-71
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• 2024

기존 스마트폰에서 사용된 PIN과 같은 인증기법은 디스플레이 구조의 변형 또는 화면 크기의 가변성에 대한 고려가 이루어지지 않아 최근의 가변 디스플레이 기반 스마트폰에 적용될 경우 비밀정보 입력부의 축소나 확대로 발생 가능한 취약점과 같은 디스플레이 면적의 변형에 따른 사회공학 공격에 대한 취약점이 있다. 본 연구는 롤러블 및 벤더블 스마트폰과 같이 디스플레이 크기 변화에 대응하는 보안 키패드를 제안한다. 이를 위해 우선 각 기존 인증기법에서 새로운 폼팩터에 적용될 경우 발생할 수 있는 보안 문제를 분석하였으며 이에 대응하는 보안 요구사항을 도출하였다. 제안하는 보안 키패드는 롤러블 및 벤더블 스마트폰의 디스플레이 크기에 따라 입력에 적합한 간격과 크기로 키의 배열 및 배치가 변형 가능하므로 화면 크기가 작을 때 발생할 수 있는 키 입력 오류 문제를 고려하였다. 또한, 키 입력 좌표를 불규칙적으로 분산하여 사회공학 공격에 대한 입력 정보 유출 문제도 고려하였다. 제안 기법은 다양한 크기와 형태의 스마트폰에서 사용할 수 있어 기존 기법보다 더 나은 사용자 경험과 보안성을 제공한다.

• 농촌계획
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• 제8권3호
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• pp.33-40
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• 2002

The PTDRT model as prediction techniques for desalinization in reclaimed tidelands was developed and verified whether it is applicable to reclaimed tidelands at the beginning stage. The changes of salt concentration during desalinization, the water requirements and period required for desalinization, were simulated according to soil properties and desalinization methods by repression analyses. The program was also designed to systematize input data and analysis data associated with desalinization, and to confirm the results by a graphic form. All input data and the results can be printed after the form of a typical report.

• International Journal of Precision Engineering and Manufacturing
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• 제3권4호
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• pp.15-23
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• 2002

With the development of a laser scanner of high precision and increased speed, reverse engineering becomes a key approach to reduce the time for the development of new products. But the modeling process is not so automated enough until now. Modeling in real workshops is usually performed by the experienced operators and it requires a skillful technique to get the resultant surface of high quality and precision. In this paper, a systematic solution is proposed to automate the free-form surface generation from the measured point data. Compatibility is imposed to the measured point data during input curve generation. And the compatibility of cross-sectional curve is also considered for the loft surface generation. The data in each step is produced in IGES file format to make an easy interface to other CAD/CAM software without any further data manipulation.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.51-58
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• 2001

The PTDRT model as prediction techniques of desalinization in reclaimed tidelands was developed and verified in order to be applicable to reclaimed tidelands at the beginning stage. In this model, the changes of salt concentration during desalinization, the water requirements and period required for desalinization, were simulated according to soil properties and desalinization methods by regression analyses. This program was also designed to systematize input data and analysis data associated with desalinization, and to confirm the results by a graphic form. All input data and the results are able to be printed after the form of a typical report.

• Journal of information and communication convergence engineering
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• 제12권2호
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• pp.67-74
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• 2014

In multi-hop communication systems, two-way relaying is one of the solutions to mitigate the spectral efficiency loss caused by a half-duplex transmission. In this paper, a simple two-way relaying scheme is proposed for two-hop two-user multiple input multiple output (MIMO) systems. In the proposed system, a base station and a relay station (RS), both equipped with two antennas, form a point-to-point MIMO channel, while the RS and two single-antenna mobile users form a point-to-multipoint multiuser (MU)-MIMO channel. Numerical examples show that the proposed system achieves a significant sum rate gain as compared to a one-way relaying system as the distance between a relay and the two users decreases. We also show that although we can expand the proposed scheme to more than two users, its performance gain as compared to that of one-way relaying decreases with an increase in the number of users.

• 한국통신학회논문지
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• 제18권3호
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• pp.355-359
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• 1993

본 논문에서는 echo canceller에서 LMS 알고리즘을 이용할 때 원하는 MSE하에서 가장 빠른 수렴 속도를 가져오는 최적 수렴상수에 대한 공식을 유도하였다. White 입력 데이터에 대해서 최저 수렴상수는 필터의 탭수, 입력신호 분산, 초기 MSE, 원하는 MSE의 간단한 폐쇄 형태(closed-form)의 함수가 되고 이런 특성으로 인해 실제 적용에서 쉽게 디자인될 수 있다. 또한 컴퓨터 시뮬레이션을 통해서 유도된 결과의 정확성과 유효성을 검증하였다.