• The Korean Journal of Applied Statistics
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• v.21 no.1
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• pp.177-182
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• 2008

There are times when we need more sample to achieve a more accurate estimator. Since these two sets of sample have the information about the same population, it is necessary to treat both as a single combined data. In this paper we present the unpooled sample variance for the combined data when we just know a sample mean and variance for the each data set without the raw data. It is shown that the pooled variance $s^2_p$ is always greater than the exact variance $s^2_t$ when ${\bar{x}}_n\;=\;{\bar{y}}_m$. And the difference of means for two data, ${\bar{x}}_n-{\bar{y}}_m}$, is larger, the difference of $s^2_p$ and $s^2_t$ is larger.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.05a
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• pp.6-8
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• 2021

최근 COVID-19의 백신이 개발되어 접종을 시작했다. 정부는 집단면역 생성을 위해 접종 목표치를 설정하고, 민관합동신속대응팀을 설립하는 등의 조치를 취하고 있다. 하지만 COVID-19의 백신이 다른 백신에 비해 개발 기간이 훨씬 짧을뿐더러, 효과가 입증되지 않아 신뢰를 얻지 못하고 있다. 블록체인은 거래 당사자 간의 거래정보를 네트워크에 참여하는 모든 구성원들이 공동으로 기록, 검증, 저장하는 분산장부 기술로 공인된 제3자 없이도 무결성 및 신뢰성을 확보할 수 있다. 이에 본 논문에서는 COVID-19 백신의 신뢰도를 제고하기 위해 블록체인을 기반으로 한 백신 접종 이력 관리 시스템을 설계하고, 향후 QR코드 등의 방식과 연동하여 백신 여권 등으로의 확장 가능성을 제시한다.

• Journal of Broadcast Engineering
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• v.16 no.2
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• pp.216-225
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• 2011

Following the proliferation of three-dimensional video contents and displays, many terrestrial broadcasting companies have been preparing for stereoscopic 3DTV service. In terrestrial stereoscopic broadcast, it is a difficult task to code and transmit two video sequences while sustaining as high quality as 2DTV broadcast due to the limited bandwidth defined by the existing digital TV standards such as ATSC. Thus, a terrestrial 3DTV broadcasting with a heterogeneous video codec system, where the left image and right images are based on MPEG-2 and H.264/AVC, respectively, is considered in order to achieve both high quality broadcasting service and compatibility for the existing 2DTV viewers. Without significant change in the current terrestrial broadcasting systems, we propose a joint rate control scheme for stereoscopic 3DTV service based on the heterogeneous dual codec systems. The proposed joint rate control scheme applies to the MPEG-2 encoder a quadratic rate-quantization model which is adopted in the H.264/AVC. Then the controller is designed for the sum of the left and right bitstreams to meet the bandwidth requirement of broadcasting standards while the sum of image distortions is minimized by adjusting quantization parameter obtained from the proposed optimization scheme. Besides, we consider a condition on maintaining quality difference between the left and right images around a desired level in the optimization in order to mitigate negative effects on human visual system. Experimental results demonstrate that the proposed bit rate control scheme outperforms the rate control method where each video coding standard uses its own bit rate control algorithm independently in terms of the increase in PSNR by 2.02%, the decrease in the average absolute quality difference by 77.6% and the reduction in the variance of the quality difference by 74.38%.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.4
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• pp.100-110
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• 2008

The purposes of the study were to analyze the effects of determinants and persuasive messages on the willingness-to-pay cultural & heritage assets' admission fees. Recently visitors have responded to a nationwide boycott of the fees within national parks due to feelings of disapproval and resentment. Data were collected through onsite surveys of 302 visitors in the Mt. Gyeryong National Park. Regression analysis and two-way ANOVA were employed to obtain the results. The results indicate that credit card payment was the most prominent predictor of willingness-to-pay at the .05 level. The second highest coefficient was obtained in the condition levying of admission fees and parking fees at the same time, providing temple interpretive services, followed by free days for everyone on special days each month. In addition, the most persuasive message was the descriptive content, which stated that fees were profoundly committed to the protection of the cultural heritage for future generations. As a result, it is effective to continually persuade visitors to use posters or reminders that stress the preservation of cultural assets at the entrance gate.