• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.1013-1016
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• 1999

Simple Genetic Algorithm(SGA) proposed by J. H. Holland is a population-based optimization method based on the principle of the Darwinian natural selection. The theoretical foundations of GA are the Schema Theorem and the Building Block Hypothesis. Although GA does well in many applications as an optimization method, still it does not guarantee the convergence to a global optimum in GA-hard problems and deceptive problems. Therefore as an alternative scheme, there is a growing interest in a co-evolutionary system, where two populations constantly interact and co-evolve. In this paper we propose an extended schema theorem associated with a schema co-evolutionary algorithm(SCEA), which explains why the co-evolutionary algorithm works better than SGA. The experimental results show that the SCEA works well in optimization problems including deceptive functions.

• 한국통신학회논문지
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• 제7권3호
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• pp.130-134
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• 1982

컴퓨터 통신 네트워크에서 端末裝置로부터 入力되는 메시지에 대하여 버퍼에 남아 있을 메시지 블록數에 관한 確率分布函數를 考察ㅎ여 平均블록數에서 最小 버퍼 사이즈를 요하는 블록長을 구하고 이 블록과 연결정보長과의 관계를 규명하여 이 分布에 대한 타당성을 모색하였다 또한 이 分布에 대한 亂數發生器를 설계하여 테스트한 결과 亂數데이터源으로 사용할 수 있음을 보였다.

• 융합신호처리학회논문지
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• 제14권1호
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• pp.13-20
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• 2013

A combined DWT and DCT based watermarking technique of low frequency watermarking with weighted correction is proposed. The DWT has excellent spatial localization, frequency spread and multi-resolution characteristics, which are similar to the theoretical models of the human visual system (HVS). The DCT based watermarking techniques offer compression while DWT based watermarking techniques offer scalability. These desirable properties are used in this combined watermarking technique. In the proposed method watermark bits are embedded in the low frequency band of each DCT block of selected DWT sub-band. The weighted correction is also used to improve the imperceptibility. The extracting procedure reverses the embedding operations without the reference of the original image. Compared with the similar approach by DCT based approach and DWT based approach, the experimental results show that the proposed algorithm apparently preserves superiori mage quality and robustness under various attacks such as JPEG compression, cropping, sharping, contrast adjustments and so on.

• 음성과학
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• 제13권2호
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• pp.19-33
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• 2006

The purpose of this paper was to examine acoustical characteristics of phonatory offset-onset mechanism in the connected speech of female adults with stuttering and normal nonfluency. The phonatory offset-onset mechanism refers to the laryngeal articulatory gestures. Those gestures are required to mark word boundaries in phonetic contexts of the connected speech. This mechanism included 7 patterns based on the speech spectrogram. This study showed the acoustic features in the connected speech in the production of female adults with stuttering (n=1) and normal nonfluency (n=3). Speech tokens in V_V, V_H, and V_S contexts were selected for the analysis. Speech samples were recorded by Sound Forge, and the spectrographic analysis was conducted using Praat. Results revealed a stuttering (with a type of block) female exhibited more laryngealization gestures in the V_V context. Laryngealization gesture was more characterized by a complete glottal stop or glottal fry both in V_H and in V_S contexts. The results were discussed from theoretical and clinical perspectives.

• 지질공학
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• 제4권2호
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• pp.127-138
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• 1994

균일 암반내 지하수 유동은 프락탈 성질의 균열 분포에 영향을 받으므로 정상류 이중 공극 모델로는 균열 암반 대수층의 수리지질학 성질을 설명하기가 어렵다. 본 연구에서는 새로운 정상류 이중공극 프락탈 모델이 제안되었다. 본 모델은 블록으로부터 균열로의 정상류를 포함하는 프락탈 대수층을 모식화한 것이다. 아울러 본 모델은 양수정의 우물저장효과와 우물손실효과를 고려하는 것이다. 여러가지 흐름의 차원과 여러가지 값이 배출계수에 대한 표준곡선들이 만들어졌다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 춘계학술대회 논문집
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• pp.63-70
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• 1994

An upper bound elemental technique(UBET) is applied to predict forging load and die-cavity filling for non-axisymmetric ring forging. The finial product is divided into three different deformation regions. That is axisymmetric part in corner, lateral plane-strain part and shear deformation on boundaries between them. The plane-strain and axisymmetric part are combinded by building block method. Also the total energy is computered through combination of three deformation part. Experiments have been carried out with pure plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agreement with the experimental results.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 춘계학술대회 학술발표 논문집
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• pp.77-80
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• 1998

The theoretical foundations of simple genetic algorithm(SGA) are the Schema Theorem and the Building Block Hypothesis. Although SGA does well in many applications as an optimization method, still it does not guarantee the convergence of a global optimum in GA-hard problems and deceptive problems. Therefore as an alternative scheme, there is a growing interest in a co-evolutionary system, where two populations constantly interact and cooperate each other. In this paper we show why the co-evolutionary algorithm works better than SGA in terms of an extended schema theorem. Also the experimental results show a co-evolutionary algorithm works well in optimization problems.

• ETRI Journal
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• 제28권3호
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• pp.401-404
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• 2006

A new log-domain first-order multifunction filter is proposed in this letter. The proposed filter is systematically derived using the state-space synthesis procedure from a corresponding block diagram. It provides low-pass (LP), high-pass (HP), and all-pass (AP) responses simultaneously for a single input signal. The filter circuit has a very simple structure since it uses only bipolar junction transistors (BJTs) and a grounded capacitor. It can be electronically tuned by changing an external current. The filter has a greater bandwidth due to its inherent current-mode and log-domain operations. PSPICE simulations are given to confirm the theoretical analysis.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2018년도 제57차 동계학술대회논문집 26권1호
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• pp.99-100
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• 2018

컴퓨팅 사고력이 강조됨에 따라 우리 나라를 비롯한 세계 여러 나라에서는 프로그래밍 교육 등 컴퓨팅 관련 교육을 실시하고 있다. 일반적으로 프로그래밍 교육에서 초보 학습자에게는 블록 기반 프로그래밍 언어를 학습한 후 텍스트 기반 프로그래밍 언어를 학습하게 된다. 블록 기반 언어와 텍스트 기반 언어는 동일한 프로그래밍 논리를 함양하게 되지만, 다른 모든 언어들과 마찬가지로 언어 특성, 사용법, 형태 등 다소 차이가 있다. 따라서 본 논문에서는 블록 기반 프로그래밍 언어에서 텍스트 기반 프로그래밍 언어의 학습 전이의 효과에 대해 이론적 고찰을 실시하였으며, 그 결과 대부분의 연구에서 긍정적 전이 효과를 입증하였음을 확인하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.170-175
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• 2005

In this study, experimental and theoretical methods were applied to understand brake squeal noise VVVF rolling stock on tracks. Trailer cars needed to payed a particular attention, because they were the major source of brake noise. VVVF rolling stocks for lines no 1 of the subway system in Seoul were used for experimental analyses. In order to study brake squeal noise, a dynamometer test at the S&T Brake, Co., which was a manufacturer of brake pads had performed. For measuring vibration and noise, vibration tests of brake parts (brake lining, brake lining head, back plates, etc.) at the SNUT were executed. Also, vibration tests of disc assembly and lining block at the heavy maintenance shop of the Gunja depot were performed. The modal analyses by using an ANSYS which was one of the CAE commercial program were simulated to know the relationship to the mechanism of brake noise. On the based of the tests and the simulations it was found that specific frequencies of the brake parts affected squeal noise, and improvements for reducing squeal noise were proposed.