• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.385-388
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• 2013

In this paper, we show the weakness of the image matching method by using MPEG-7 EHD(Edge Histogram Descriptor) and suggest how to improve this weakness by using image normalization. EHD algorithm is an image matching technique that collects edge's slope of distribution and same distribution. However, the EHD error rate is high because EHD is sensitive for changes of object distortion and rotation that will be matched. We improve matching performance by accurately extract edge information in image by using normalization. We compare and analyze the normalized EHD algorithm by using distortion and rotation and it shows robustness for changes of the size and rotation.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.7
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• pp.271-276
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• 2014

Short message service(SMS) in a mobile communication environment is a very convenient method. However, it caused a serious side effect of generating spam messages for advertisement. Those who send spam messages distort or deform SMS sentences to avoid the messages being filtered by automatic filtering system. In order to increase the performance of spam filtering system, we need to recover the distorted sentences into normal sentences. This paper proposes a method of normalizing the various types of distorted sentence and extracting keywords through automatic word spacing and compound noun decomposition.

• Journal of KIISE:Software and Applications
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• v.34 no.6
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• pp.503-518
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• 2007

Normalization transforms one parent genotype to be consistent with the other before crossover. In this paper, we explain how normalization alleviates the difficulties caused by non-synonymously redundant encodings in genetic algorithms. We define the encodings with maximally non-synonymous property and prove that the encodings induce uncorrelated search spaces. Extensive experiments for a number of problems show that normalization transforms the uncorrelated search spaces to correlated ones and leads to significant improvement in performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11C
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• pp.1052-1061
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• 2003

This paper proposes a novel normalization scheme in the state metric calculation unit for the Block-wise MAP Turbo decoder. The proposed scheme subtracts one of four metrics from the state metrics in a trellis stage and shifts, if necessary, those metrics for normalization. The proposed architecture can reduce power consumption and memory requirement by reducing the number of the state metrics by one in a trellis stage in the Block-wise MAP decoder which requires an intensive state metric calculations. Simulation results show that dynamic power has been reduced by 17.9% and area has been reduced by 6.6% in the Turbo decoder employing the proposed normalization scheme, when compared to the conventional Block-wise MAP Turbo decoders.

• The Journal of the Acoustical Society of Korea
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• v.24 no.4
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• pp.224-229
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• 2005

In this paper, we Propose a novel cepstrum normalization method which normalizes the probability density function (pdf) of cepstrum for robust speech recognition in additive noise environments. While the conventional methods normalize the first- and/or second-order statistics such as the mean and/or variance of the cepstrum. the proposed method fully normalizes the statistics of cepstrum by making the pdfs of clean and noisy cepstrum identical to each other For the target Pdf, the generalized Gaussian distribution is selected to consider various densities. In recognition phase, we devise a table lookup method to save computational costs. From the speaker-independent isolated-word recognition experiments, we show that the Proposed method gives improved Performance compared with that of the conventional methods, especially in heavy noise environments.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.48-55
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• 1999

In this paper, the ill-posed inverse problem of surface waves caused by a two-dimensional pulsating pressure distribution on the free surface is studied using the regularization method. In order to exemplify the method, a cosine pressure distribution on a limited range of the undisturbed free surface is considered. By taking the resulting horizontal velocity as input data, the corresponding pressure is determined numerically by three different regularization schemes. It is found that the iterated Tikhonov method provides with the most accurate result, while solutions obtained from the Landweber-Friedman regularization are most stable.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5A
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• pp.298-304
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• 2012

In this paper, we propose robust estimators for the frequency offset of orthogonal frequency division multiplexing in non-Gaussian noise environments. We first propose a maximum-likelihood (ML) estimator in non-Gaussian noise modeled as a complex isotropic Cauchy process, and then, we present a simpler suboptimal estimator based on the ML estimator. From numerical results, it is demonstrated that the proposed estimators not only outperform the conventional estimators, but also have a robustness in non-Gaussian noise environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1278-1290
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• 2008

This paper proposes a preprocessing method and a neural network based character recognizer to enhance the overall performance of the license plate recognition system. First, plate outlines are extracted by virtual line matching, and then the 4 vertexes are obtained by calculating intersecting points of extracted lines. By these vertexes, plate image is reconstructed as rectangle-shaped image by bilinear transform. Finally, the license plate is recognized by the neural network based classifier which had been trained using delta-bar-delta algorithm. Various license plate images were used in the experiments, and the proposed plate normalization enhanced the recognition performance up to 16 percent.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.221-221
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• 2016

최근 레이더를 이용한 정량적 강수추정과 관련된 연구가 활발히 수행되고 있으며, 우량계와 레이더 자료의 합성과 관련된 연구가 수행되고 있다. 이는 정도 높은 우량계 자료의 장점과 강우의 공간분포를 파악할 수 있는 레이더 자료의 장점을 결합하여 고품질의 자료를 생산할 수 있기 때문이다. 자료합성과 관련된 다양한 기법이 도입되었고, 크리깅의 한 종류인 코크리깅이 널리 사용되고 있다. 크리깅은 값을 알고 있는 지점의 자료를 가중선형 조합하여 미지점의 값을 예측하는 경험적 방법으로 연속적이며 정규분포를 따르는 자료에 대해 유효하다. 그러나 강우자료는 강한 양의 왜곡도를 나타나고 간헐성도 강하게 나타나 크리깅의 이러한 조건을 만족시키지 못한다. 이로 인해 강우 자료에 크리깅을 수행할 경우 예측 값이 왜곡되거나 편향될 가능성이 크다. 이에 본 연구에서는 강우의 간헐성과 정규분포를 따르지 않는 특성을 고려하여 단순크리깅의 적용방법을 개선하였다. 단순크리깅은 가장 간단한 크리깅 기법으로 설명이 쉽고 적용사례를 비교하기 유리하여 이를 개선하면 다른 복잡한 크리깅 기법에도 쉽게 적용이 가능한 이점이 있다. 본 연구에서는 모의 자료와 레이더 강우 자료를 이용하여 단순크리깅을 수행하였고, 그 결과를 비교하여 자료의 간헐성과 비정규적 특성이 예측 값에 미치는 영향을 분석하였다.

• Journal of Labour Economics
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• v.41 no.4
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• pp.31-62
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• 2018

Using matching and difference-in-differences estimation method, this study estimates causal effects of health shocks on employment and income of full-time workers aged 40-55. Acute hospital admissions lower significantly the employment probability and earnings. The changes in employment and earnings persist up to three years after the health shock. The economic impacts of health shocks vary by socioeconomic status and job characteristics among individuals. Irregular workers are more likely to leave their jobs after health shocks than regular workers. Among irregular workers, the probability of leaving labor market after health shock decreases with the size of the firm.