• The Journal of the Acoustical Society of Korea
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• v.10 no.1
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• pp.20-29
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• 1991

A fundamental assumption in conventional linear predictive coding (LPC) analysis procedure is that the input to an all-pole vocal tract filter is white process. In the case of periodic inputs, however, a pitch bias error is introduced into the conventional LP coefficient. Multi-pulse (MP) LP analysis can reduce this bias, provided that an estimate of the excitation is available. Since the prediction error of conventional LP analysis can be modeled as the sum of an MP excitation sequence and a random noise sequence, we can view extracting MP sequences from the prediction error as a classical detection and estimation problem. In this paper, we propose an algorithm in which the locations and amplitudes of the MP sequences are first obtained by applying a likelihood ratio test (LRT) to the prediction error, and LP coefficients free of pitch bias are then obtained from the MP sequences. To verify the performance enhancement, we iterate the above procedure with adaptive threshold at each step.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.237-244
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• 2015

Export-led policies, FTA signed and economics of scale through a variety of market-oriented policies, such as regulations to improve market grew constantly. Accordingly, the correct decision making accurately analyze the economics market for decision, a problem has been an important issue in predicting. For accurate analysis and decision-making of the most common indicators of the stock market by proposing a number of indicators of economic transformation techniques were applied to the convergence model combining estimation and forecasts problem confirmed its effectiveness. Experimental result, gave the model estimation method to apply a transform to show the valid combinations proposed model state estimation result was confirmed in a very similar exercise aspect of the physical problem and the KOSPI index prediction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.907-910
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• 2011

This paper proposes a character segmentation algorithm of steel plate images composed of adaptive binarization by the SCW (Sliding Concentric Windows) technique, the object labelling by CCA (Connected Component Analysis), and 2D projection method. The SCW technique carries out the grayscale-to-binary image conversion in consideration of local characteristics of images. The character decision algorithm followed by the labelling technique by CCA (Connected Component Analysis) determines the character area effectively reducing the noise effect. The 2D projection with horizontal and vertical directions produces a tight bounding box for a character based on the cross points. Experimental results indicate that the proposed algorithm segments the characters in steel plate images effectively. The proposed algorithm can be applied to the devices with limited resources due to its excellent performance and low complexity.

• Information Systems Review
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• v.26 no.2
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• pp.45-57
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• 2024

This study develops a deep learning-based methodology for predicting Crude Palm Oil (CPO) prices. Palm oil is an essential resource across various industries due to its yield and economic efficiency, leading to increased industrial interest in its price volatility. While numerous studies have been conducted on palm oil price prediction, most rely on time series forecasting, which has inherent accuracy limitations. To address the main limitation of traditional methods-the absence of stationarity-this research introduces a novel model that uses the ratio of future prices to current prices as the dependent variable. This approach, inspired by return modeling in stock price predictions, demonstrates superior performance over simple price prediction. Additionally, the methodology incorporates the consideration of lag values of independent variables, a critical factor in multivariate time series forecasting, to eliminate unnecessary noise and enhance the stability of the prediction model. This research not only significantly improves the accuracy of palm oil price prediction but also offers an applicable approach for other economic forecasting issues where time series data is crucial, providing substantial value to the industry.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.177-180
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• 2000

소나 시스템에서는 신호 대 잡음비의 향상, 표적의 방위탐지 및 위치 데이터 산출, 간섭신호 제거 등을 위하여 지향성 빔을 만들어 사용한다. 본 논문에서는 선형으로 배열된 센서에서 각 센서쌍들에 대한 상호상관 행렬을 이용한 SCCBF(Spatial Cross Correlation Beamformer) 알고리즘을 제안하였다 이상적인 조건하에서 제안된 SCCBF는 CBF(Conventional Beamformer)에 비해 3dB의 Array Gain을 갖는 것을 이론적으로 검증하고 표적의 탐지 방위정확도를 나타내는 빔폭(Beam Width)이 CBF 보다 0.5배정도가 됨을 검증하고 모의실험을 통하여 이를 입증하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.1025-1031
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• 2001

In this paper, we derive the outage probability of cellular mobile system with STTB(Space Time Transmitter Diversity) scheme where the received radio signals and interferers experience Rayleigh fading and AWGN. The new probability density function of L independent identically distributed interferers is derived using Laplace transforms. We express the probability of outage as a function of the average-signal to average-interference power ratio and the signal to noise ratio. In addition, the frequency reuse distance which is one of the key parameters in the design of cellular systems is analyzed.

• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.181-184
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• 2009

본 논문은 번호판 내 명암도 대비를 이용한 자동차 번호판 검출 기법을 제안한다. 평균값 필터와 라플라시안 필터를 사용하여 영상의 잡음을 제거하는 동시에 에지 성분을 향상시킨 후 조명 환경 변화에 강인한 번호판 내 명암도 대비 특징을 이용하여 문자 후보를 검출한다. 다음으로 검출된 문자 후보가 열을 이루는 텍스트 후보를 검출하고, 이 영역을 Otsu 이진화 기업을 사용하여 x축에 투영하였을 시 나타나는 패턴을 평가함으로써 최종적으로 자동차 번호판을 검출하게 된다. 제안하는 기법의 성능을 평가하기 위해 다수의 데이터를 사용하여 실험하였고, 이를 분석하여 제안하는 기법의 우수성을 검증하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.61-64
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• 2004

본 논문에서는 저전송율 음성부호화기인 2.4kbps MELP(Mixed Excitation Linear Prediction) 보코더를 TI(Texas Instruments) 사의 고정소수점 DSP인 TMS 320VC5510을 이용하여 실시간 구현한 결과를 제시한다. MELP 보코더는 전통적인 LPC 합성방식에 기반한 것으로, 2.4kbps LPC 보코더가 여기신호를 유성음 구간에 대해서는 펄스열로, 무성음 구간에 대해서는 백색잡음 신호로 단순화시켜 합성함으로써 음질이 저하되거나 buzz 현상이 나타나는 단점을 적절히 혼합된 형태의 여기신호를 사용함으로써 보완한 것이다. DDVPC(Defense Digital Voice Processing Consortium)에서 제공하는 ANSI C 소스 코드를 이용하여 TMS320VC5510 DSK에서 실시간 동작이 가능하도록 최적화 작업을 수행하였으며, 구현된 MELP 보코더는 프로그램 메모리 46.5 kbyte와 데이터 메모리 57.9 kbyte를 가지며, 22.5ms의 한 프레임을 처리하는데 1326531 클럭(6.6 ms)이 소요되었다.

• Journal for History of Mathematics
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• v.17 no.2
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• pp.85-96
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• 2004

The Resealed range statistical analysis and Hurst exponent which are standard methods to test the chaotic model are used to examine sinusoid pattern. We notice that the Hurst exponent can be used as a measure to examine the time series data that show semi-cyclic trend with noise.

• Journal of Intelligence and Information Systems
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• v.5 no.1
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• pp.1-12
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• 1999

강건설계(robust design)는 낮은 비용으로 잡음에 강건한 고품질의 제품이나 공정을 설계하는 체계적이고 효율적인 방법이다. 그러나 강건설계의 과정 중 비표준 직교배열의 사용과 교호인자을 포함한 실험계획은 다소 복잡하고, 전문지식이 필요한 부분으로 비전문가에는 난해한 작업이다. 이를 해결하기 위하여 본 연구에서는 표준직교배열의 변형과 선점도를 이용하여 교호인자를 직교배열의 열에 자동으로 할당하는 전문가시스템 prototype을 개발하였다. 사용자가 수준별 인자수와 교호작용의 유무를 입력하면, 시스템은 적절한 직교배열을 선정하여 필요에 따라 변형하며, 제어인자와 교호작용을 직교배열표에 자동으로 할당하여 출력한다. 개발된 시스템을 사용함으로써 초보자도 직교배열을 쉽게 변형할 수 있으며 다수의 교호인자를 포함한 실험계획을 빠르게 할 수 있다. 본 연구에서 이용된 지식은 문헌에서 추출하였으며, 추론 전략으로는 규칙기반추론(rule-based reasoning)을 이용하였다.