• Journal of KIISE
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• v.43 no.8
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• pp.835-840
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• 2016

Monte Carlo ray tracing has been widely used for simulating a diverse set of photo-realistic effects. However, this technique typically produces noise when insufficient numbers of samples are used. As the number of samples allocated per pixel is increased, the rendered images converge. However, this approach of generating sufficient numbers of samples, requires prohibitive rendering time. To solve this problem, image filtering can be applied to rendered images, by filtering the noisy image rendered using low sample counts and acquiring smoothed images, instead of naively generating additional rays. In this paper, we proposed a Stein's Unbiased Risk Estimator (SURE) based $\grave{A}$-Trous wavelet to filter the noise in rendered images in a near-interactive rate. Based on SURE, we can estimate filtering errors associated with $\grave{A}$-Trous wavelet, and identify wavelet coefficients reducing filtering errors. Our approach showed improvement, up to 6:1, over the original $\grave{A}$-Trous filter on various regions in the image, while maintaining a minor computational overhead. We have integrated our propsed filtering method with the recent interactive ray tracing system, Embree, and demonstrated its benefits.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.2
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• pp.111-118
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• 2004

Techniques based on thresholding of wavelet coefficients are gaining popularity for denoising data because of the reasonable performance at the low complexity. The VisuShrink which removes the noise with the universal threshold is one of the techniques. The universal threshold is proportional to the noise deviation and the number of data samples. In general, because the noise deviation is not known, one needs to estimate the deviation for determining the value of the universal threshold. But, only for the finest scale wavelet coefficients, it has been known the way of estimating the noise deviation, so the noise in coarse scales cannot be removed with the VisuShrink. We propose here a new denoising method which removes the noise in each scale except the coarsest scale by Visushrink method. The noise deviation at each band is estimated by the monotonic transform and weighted deviation, the product of estimated noise deviation by the weight, is applied to the universal threshold. By making use of the universal threshold and the Soft-Threshold technique, the noise in each band is removed. The denoising characteristics of the proposed method is compared with that of the traditional VisuShrink and SureShrink method. The result showed that the proposed method is effective in denoising on Gaussian noise and quantization noise.

• Journal of Korean Society of Forest Science
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• v.90 no.1
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• pp.1-9
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• 2001

The objectives of this study were to explain market structures of logs imported to Korea from U.S.A., New Zealand. Chile. The demand for imported logs is modeled as a function of output of wood manufacturing in Korea and log prices of competing suppliers. It is hypothesized that the quantity of log impaled in a period is determined by its own and competing prices and the output of wood corresponding manufacturing sector in the current period. Import demand functions of logs imported to Korea from U.S.A., New Zealand and Chile were estimated by SURE(Seemingly Unrelated Regression Equations). Elasticities of amounts of logs imported to Korea from U.S.A., New Zealand and Chile with respect to price of imported log from U.S.A. were -2.88, 1.36 and 3.17, respectively. Elasticities of amounts of logs imported to Korea from U.S.A., New Zealand and Chile with respect to price of imported log from New Zealand were 0.71, -1.65 and 1.44, respectively, Elasticities of amounts of logs imported to Korea from U.S.A., New Zealand and Chile with respect to price of imported log from Chile was -2.88. 1.36 and 3.17.

• 한국경영정보학회:학술대회논문집
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• 2007.06a
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• pp.333-338
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• 2007

소프트웨어 개발 프로젝트의 15%는 시작하기도 전에 종결되며, 66%의 프로젝트는 실패로 간주되고 있다. 또한 평균적으로, 완료된 프로젝트의 43%가 비용을 초과하는 것으로 나타났다. 실제로 2002년도 미국에서 소프트웨어 프로젝트의 투자 실패로 인한 손실은 비용의 초과로 생긴 170억 달러를 포함해 총 손실 금액이 380억 달러인 것으로 추정하고 있다. 이러한 문제점을 해결하고자 하는 여러 시도 중에 하나가 ISBSG(International Software Benchmarking Standard Group, 2004)으로, 소프트웨어 프로젝트 관련 데이터를 국제적으로 수집하여 위와 같은 문제의 원인을 밝히고자 노력하고 있다. 본 연구는 ISBSG에서 수집한 데이터를 이용해 소프트웨어 시스템과 관련된 요인 중에서 기능성 품질, 문서화품질, 훈련정도, 소프트웨어크기, 전체결함수, 사업요구사항충족, 사용편리성, 목표달성이라는 6개 변수 간의 연관성을 분석하였다. 분석대상 프로젝트는 49개이고, 분석 방법으로는 SURE(Seemingly Unrelated REgression)를 사용하였다. 분석 결과 소프트웨어 기능성품질은 사업요구사항충족, 사용편리성과 정의 관계를 가지며, 사용편리성은 사업요구사항충족과 정의 관계를 가지는 것으로 밝혀졌다. 또한 사업요구사항충족은 목표달성과 정의 관계를 가지고 있다.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.393-396
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• 2003

고압축 영상신호에서 발생된 양자화잡음 제거 효과를 비교하였다. 잡음제거는 Soft-Threshold 기법을 이용하여 각 대역에서 양자화 잡음을 제거하였다. Soft-Threshold 기법에 적용하기 위해 각 대역별 잡음분산을 Monotonic 변환 및 SURE, Visu 방법으로 추정하여 양자화 잡음제거 효과를 PSNR로 비교하였다. 양자화 잡음 제거 결과 영상에 따라 달라지지만 유니폼 양자화 영상에서 약 5～6dB 정도의 영상품질 개선 효과가 있었다.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.329-339
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• 2011

This study aims at investigating how English proficiency affects economic development of a country by analyzing the relationships among English proficiency, economic activities (amount of trade, R&D investment, etc), and the rate of economic growth, focusing on twenty-one non-English-speaking OECD countries. Ordinary Least Square (OLS) and Seemingly Unrelated Regression Estimation (SURE) were used for the data analysis in the study. The findings reveals that there existed little statistical significance to support the fact that English proficiency was directly related to the economic development in a positive way in many countries except Mexico, the Czech Republic, Finland, and Poland. However, English proficiency indirectly influenced the economic development in the way of increasing the amount of trade. These results can lead to the conclusion that English proficiency is not a sufficient element but a necessary one. Furthermore, it is expected that English proficiency can positively affect the economic development when it plays a part as sufficient complementary goods which make up for physical capital, technology accumulation, political stability, and worthy government.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.4
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• pp.255-265
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• 2007

In case of wavelet coefficients have correlation, in image signal denoising using wavelet shrinkage denoising method, the denoising effect for the image signal is reduced when the wavelet shrinkage denoising method is used. The coefficients of multiwavelet transform have correlation by pre-filters. To solve the degradation problem in multiwavelet transform, V Sterela suggested a new pre-filter for the Universal threshold or weighting factors to the threshold. In this paper, to improve the denoising effect in the multiwavelet transform, the coefficient normalizing method that the coefficient are divided by estimated noise deviation is adopted to the transformed multiwavelet coefficients in the course of wavelet shrinkage technique. And the thresholds of universal, SURE and GCV are estimated using normalized coefficients and tried to denoise by the wavelet shrinkage technique. We compared PSNRs of denoised images for each thresholds and confirmed the efficiency of the proposed method.

• The Journal of the Korea Contents Association
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• v.10 no.3
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• pp.315-325
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• 2010

The issues on education as a human capital formation in recent years have been focused for all of the countries with emerging of the knowledge-based economy. The present study compared and analyzed the relationships between the educational investment and national economic growth of ten non-English-speaking OECD countries during 1970-2008, using Ordinary Least Square (OLS) and Seemingly Unrelated Regression Estimation (SURE) as the main analytical methods. Findings indicate that educational investment, R&D investment, and fertility rate were statistically significant in the estimation of the variables related to the human capital formation, and these elements had also positive influence on the national economic growth. The most salient factor was the fertility rate, and the R&D investment and educational investment appeared as the next factors in the national economic growth. In particular, the dimensions in the coefficient of the fertility rate showed 1.8 times of the R&D and 3.5 times of the educational investment, respectively. These results imply that educational investment, R&D investment, and the policies which promote fertility rate should be taken into account for the continuous economic growth of each country.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.300-308
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• 2010

This study empirically investigates the export structure change of OECD countries in the field of information technology from 1995 to 2005. We used Between and Within Entropy index to estimate the difference of export structure change rather than RCA index(simple export structure change). In addition, we also estimate the relationship between R&D activities and export difference. First, empirical findings showed that IT export market concentration is decreasing gradually, and changing to more competitive market structure. Second, compared to other OECD countries, Korean exports weight of information and communication industry can be seen higher than that of bio-industry. Third, Entropy index was increased from 1995 and then gradually decreased as the starting point of 2000. Finally, the relationship between R & D activities in the telecommunications industry and impact of the export structure changes was a positive.

• Journal of Korean Society of Transportation
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• v.23 no.3 s.81
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• pp.61-71
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• 2005

We evaluated the availability of Origin-Destination Matrix from traffic counts Using conjugate gradient method to large scale networks by applying it to the networks in 246 zones. As a result of the analysis of the consistency of the model on Nationwide Networks, the upper and lower levels in model had the systematic relationship internally. From the analysis of the estimable power or the model according to the number of traffic counting links, the error in traffic volume had the estimable power in the range of permissible error. In addition, the estimable power of estimation of an Origin-Destination Matrix was more satisfactory than that of existing methods. We conclude that conjugate gradient method cab be applied to nationwide networks if we can make sure that the algorithm of the developed model is reliable by doing various kinds of experiment.