• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.205-211
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• 1998

The MTF(modulation transfer function) measuring system with a linear CCD(charge coupled-device) was constructed to cvaluate a color CRT(catode ray tube). The measured MTF values were corrected by considering the spectral response and the pixel sizes of CCD. The effects of a spot size, video bandwidth, pitch of shadow mask holes, display luminance, and ambient illumination on image quality were studied. The uniformity of resolution and the contrast Ioss by ambient light of the color CRT monitor were measured, and the results were analyzed by MTFA(modulation threshold area).

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.27-30
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• 2006

본 논문은 디지털 모바일 비디오에 대한 객관적 화질 평가 방법을 제안한다. 본 논문에서 제시하는 화질 평가 방법은 경계 영역을 구한 뒤, 그 주변 영역에서의 에러 값에 근거한 경계영역 특징과 영상 압축 코덱에 의하여 발생하는 블로킹 효과를 측정함으로써 주관적 화질을 객관화 하였다. 제안한 알고리듬의 성능 평가를 위하여 Mean Opinion Score (MOS)값과 기존의 방법/제안한 방법의 결과를 비교하였다. 본 논문에서는, 인간 시각에 의한 MOS값과의 상관도가 제안한 방법이 기존의 방법에 비하여 비교적 큼을 보였다.

• Journal of KIEE
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• v.10 no.1
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• pp.1-6
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• 2000

This paper represents the design of 3D endoscopic video system in order to improve visualization and enhance the ability of the surgeon to perform delicate endoscopic surgery. In comparison of the polarized and electric shutter-type stereo imaging system, The former is superior in terms of accuracy and performance speed for knot-tying and loop pass test. The result of experiments show that the proposed 3D endoscopy system has a wide viewing angle and zone which is necessary for multi-view and it has better image quality and stability of the optical performances than the electric shutter-type does.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8B
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• pp.1150-1158
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• 2010

At present multimedia service composed of voice, data, and video service is prevalent in the Internet. As such, wide-scale penetration of Internet service imposes tremendous pressure to the network infrastructure such as the media servers and links as well as the nodes. In addition, users from a large-scale population require broad bandwidth and high level of QoS. This requires a network with reliable and scalable services to customers, which also necessitates a realistic method for the design of the a media server. In this work, we explore the influence of user's behavior about delay on the performance of media server that takes into account the system and user attributes in a realistic manner. By incorporating user's behavior about the delay-sensitivity, we present an analytic framework for the evaluation of the performance of the media server, via which we illustrate a meaningful intuition in the provision of Internet multimedia service.

• Journal of Communications and Networks
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• v.12 no.6
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• pp.558-567
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• 2010

In this paper, we analyze the capability of satellite broadcasting systems to offer different levels of quality of service (QoS). We focus on the European telecommunications standards institute satellite digital radio and digital video broadcasting satellite handheld (DVB-SH) standards, which have recently been proposed for satellite broadcasting communications. We propose a strategy to provide different levels of QoS for the DVB-SH standard on the basis of an extension of the interleaving scheme, referred to as molded interleaver, which supports low latency service requirements for interactive services. An extensive analysis based on laboratory measurements shows the benefits of this solution. We also present a multilevel coding (MLC) scheme with multistage decoding designed for broadcasting communications as an alternative to the existing standards, where services with different levels of QoS are provided. We present a graphical method based on mutual information for the design and evaluation of MLC systems used for broadcasting communications. Extensive simulations for a typical satellite channel show the viability of the proposed MLC scheme. Finally, we introduce multidimensional constellations in the proposed MLC scheme in order to increase the number of different protection levels.

• Journal of the Korean Society of Radiology
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• v.8 no.1
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• pp.43-49
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• 2014

PACS is needed medical imaging with large-capacity storage device. Slower transmission degrades the performance of the PACS. Thus, the image read by the reading of the long-term stored image without compromising the quality of the video, which does not affect future readings in the range will be compressed and stored. Compression and video storage, and video transport Noise generated during storage and transmission of medical images and the resulting loss of information that occurs when the monitor output from many problems. The study estimates server display monitor and client display monitor of philips DSA system, and suggests that the evaluation and improvement about PSNR, process from server display signal obtaining to client display monitor. P company DSA is used in the test. Two monitors that are $1280{\times}1024$ pixel monitor of P company and 1536x2048 pixel monitor of Wide are used displaying angiography picture. MARO-view is taken in PACS program, and Visual $C^{++}$ is taken as accomplishing PSNR measurement program. As a result of experiment, no change in No 1, 3 of PSNR appear that there is no error in telephotograph and display. In terms of compressibility, low compressibility has small change of definition, and there was not remarkable drawback of compressibility which has little change in definition.

• Journal of The Korean Association For Science Education
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• v.31 no.1
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• pp.1-13
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• 2011

The purpose of this research is to investigate ways to introduce mentoring system to support beginning and experienced teachers for their professional development. As an alternative to existing teacher training programs, we planned and implemented a mentoring system to examine its effects in developing professionalism among teachers-in-need, and those who have not met the teacher's evaluation standards. Mentoring is defined as being concerned with promoting the 'development of an individual to his/her full potential,' both professionally and personally. It is linked with professional and career development, and is somewhat characterized by an 'expert-novice' relationship. The mentoring system in science features group mentoring, where 3 prot$\'{e}$g$\'{e}$-mentor teams gathered together for instructional consulting using their videotaped classroom teaching. Through video-based discussions, teachers could share reflective experiences through collaborative investigations based on evidences revealed in classroom teaching videos. Using open-ended interviews with the teachers and video-based discussions, we extracted needs and goals of mentoring, the need of mentoring system to support beginning teachers, and the requirement of mentor quality in light of mentor's expected roles. Conclusions and recommendations related to teachers' mentoring and for the government's development of mentoring system are discussed.

• Journal of Korean Dental Science
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• v.13 no.2
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• pp.43-51
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• 2020

Purpose: The practical examination portion of the National Dental Licensing Examination (NDLE) is slated to be administered in the latter half of 2021 in the form of a clinical performance examination that comprehensively evaluates the patient-dentist interaction using standardized patients (SPs). The SPs should be equipped with the basic qualities and capacity as evaluators for a fair and reliable administration of the test. Materials and Methods: In this study, we analyzed the existing training materials for SPs who participated in domestic and overseas practical tests for the development of training materials for SPs through seminars and surveys of 11 dentistry schools and colleges. Result: First, SPs should be selected according to the basic quality criteria and capacity, which they must possess, and the preliminary basic training about the details which they must have knowledge of and be provided through videorecorded cases before the implementation of the preliminary field training. Second, the roles of SPs and the calibration process of the evaluation result forms are needed when conducting the preliminary field training for SPs. After watching video-recorded scenario cases, the SPs participate in discussions about the watched videos before proceeding to calibration practices of evaluation result forms. Third, because the Type A questionnaire of the practical examination of the NDLE is dependent on the SPs' capacity and training, the fairness of the practical test is largely dependent on the SPs. Therefore, practicing the roles as evaluators and evaluation training should be provided using practical test items that can improve the reliability of the test and show a high level of reproducibility about the same case. Conclusion: The findings of this study will be utilized for the development of training materials for SPs, so they can participate in the administration of a fair and reliable practical examination of the NDLE.

• Atmosphere
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• v.25 no.1
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• pp.19-30
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• 2015

The Ka-band cloud radar (KCR) has been operated by the National Institute of Meteorological Research (NIMR) of Korea Meteorological Administration (KMA) at Boseong National Center for Intensive Observation of severe weather since 2013. Evaluation of data quality is an essential process to further analyze cloud information. In this study, we estimate the measurement error and the sampling uncertainty to evaluate data quality. By using vertically pointing data, the statistical uncertainty is obtained by calculating the standard deviation of each radar parameter. The statistical uncertainties decrease as functions of sampling number. The statistical uncertainties of horizontal and vertical reflectivities are identical (0.28 dB). On the other hand, the statistical uncertainties of Doppler velocity (spectrum width) are 2.2 times (1.6 times) larger at the vertical channel. The reflectivity calibration of KCR is also performed using X-band vertically pointing radar (VertiX) and 2-dimensional video disdrometer (2DVD). Since the monitoring of calibration values is useful to evaluate radar condition, the variation of calibration is monitored for five rain events. The average of calibration bias is 10.77 dBZ and standard deviation is 3.69 dB. Finally, the statistical characteristics of cloud properties have been investigated during two months in autumn using calibrated reflectivity. The percentage of clouds is about 26% and 16% on September to October. However, further analyses are required to derive general characteristics of autumn cloud in Korea.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.4
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• pp.855-860
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• 2014

Currently, aircraft and automobile simulator for training provides a variety of training by making hypothetical situation on a simulator installed on the ground currently. And the instructor maximizes the effectiveness of the training by monitoring training and instructing the required training. When trainees are boarding the aircraft or automobile. The Instructor in the ground is not able to monitoring aircraft, automobile. The assessment of the training is not easy after the end of the training. Therefore, it is difficult to provide high quality of education to the students. In this paper, simulation system is to develop the following. Collecting GPS and real-time information for aircraft, automobile $\grave{a}$implementing 3D simulation. Implementing current image of the aircraft or automobile in the screen by 3D real-time monitoring of training situation at the control center utilizing for training saving 3D video files analysis, evaluation on training after the end of the training.