• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.3
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• pp.324-340
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• 2010

Video streaming service over wireless networks is a challenging task because of the changes in the wireless channel conditions that can occur due to interference, fading, and station mobility. To provide an efficient wireless video streaming service, the rate adaptation scheme should improve wireless node performance and channel utilization. Moreover, the quality adaptation scheme should be considered at the streaming application. To meet these requirements, we propose a new cross-layer design for video streaming over wireless networks. This design includes the rate and quality adaptation schemes. The rate adaptation scheme selects the optimal transmission mode and resolves the performance anomaly problem. Based on performance improvement by the proposed rate adaptation scheme, our quality adaptation scheme improves the quality of video streaming. Through performance evaluations, we prove that our cross-layer design improves the wireless channel utilization and the quality of video streaming.

• Journal of Korean Clinical Nursing Research
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• v.19 no.3
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• pp.309-320
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• 2013

Purpose: This study was conducted to identify relationships among circadian types, sleep quality, and adaptation to night shifts among nurses working on two or three day night duties. Methods: The participants were 199 ward nurses from two university hospitals in Gyeongnam province. Each nurse worked on two or three day night duties. Data were collected between September 24 and October 14, 2012 and analyzed using t-test, ANOVA, $Scheff{\grave{e}}$ test, Pearson correlation, and multiple regression with SPSS/WIN 14.0 program. Results: Mean scores for sleep quality and adaptation to night shifts was $4.92{\pm}1.46$ on a 10-point scale and $2.66{\pm}0.47$ on a 5-point scale respectively. There were no significant differences in sleep quality and adaptation to night shifts according to circadian types of nurses. There were significant correlation between sleep quality and adaptation to night shifts (r=.25, p<.001). Factors affecting adaptation to night shifts were preference for night shifts, and subjective health status, which together explained about 35% of the total variance. Conclusions: Nurses working on two or three day night duties had low level of sleep quality and adaptation to night shifts. It is necessary to improve preference for night shifts and subjective health status for improving adaptation to night shifts of nurse.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.37-40
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• 2002

최근 음성 인식 시스템의 성능 향상을 위해 화자 적응(speaker adaptation)에 대한 연구가 활발히 진행되고 있다. HMM 기반 인식 시스템의 모델 파라미터를 수정하는 화자 적응의 경우, MAP 방법과 MLLR 방법에 대한 연구가 주류를 이루고 있다. 두 방법은 adaptation data의 양에 따라서 서로 다른 성능을 보인다. 본 논문에서는 adaptation data의 quality를 정의하고, 이를 기존 두 방법의 가중치로 이용하여 화자 적응을 수행하는 방법을 제안한다. 제안한 방법을 KAIST 통신연구실에서 구축한 한국어 도시이름 500단어 인식 시스템에 적용하여 성능을 개선하였다.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.10
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• pp.975-979
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• 2010

Existing quality adaptation schemes are useful for improving network stability in a congested network, but these schemes do not guarantee the quality of experience on video streaming due to the frequent variations in playback quality for a streaming service. In this paper, we propose a network-adaptive quality adaptation scheme to guarantee the quality of experience on SVC(Scalable Video Coding) video streaming. The proposed scheme estimates the available bandwidth by bandwidth measurement scheme using media characteristic, and then smoothly adjusts the quality level of SVC video stream according to the estimated bandwidth. Through the simulation, we prove that our scheme guarantees the quality of experience for video streaming by minimizing quality variation.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.397-399
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• 2001

프록시 서버는 점차 다양해지고 있는 클라이언트의 이질성(heteroginiety)과 이에 따른 서버와 네트워크의 과부하를 해결하기 위한 방법으로 제시되고 있다. 본 연구에서는 분산된 프록시 서버 환경에서 주어진 프록시들의 부하 균형을 위하여 각 비디오 객체의 계층(layer) 들을 서로 다른 프록시에 분리하여 저장하였다가 필요시 전송함으로서 네트워크 환경에서 특정 프록시 서버로의 집중과 혼잡성을 줄이도록 한다. 이로서 적응적인 화질(Quality Adaptation)을 보장하기 위한 계층적 코딩(layered coding) 스트리밍 서비스를 보다 효율적으로 제공할 수 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.413-417
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• 2009

The use of scalable video coding scheme has been regarded as a promising solution for guaranteeing the quality of service of the video streaming over the Internet because it is a capable coding scheme to perform quality adaptation depending on network conditions. In this paper, we use a streaming model that transmits base layer using TCP and enhancement layers using DCCP, which try to provide transmission reliability of the BL and TCP friendliness. Unlike pervious works, the proposed algorithm performs rate adaptation based on playout buffer status. The PoB status of the client is sent back periodically to the server and serves as a network congestion indicator. Experimental results show that our scheme improves streaming quality comparing with pervious scheme in the case of not only constant/dynamic background flows but also VBR-encoded video sequence.

• Women's Health Nursing
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• v.28 no.3
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• pp.210-221
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• 2022

Purpose: The purpose of this study was to construct a hypothetical model based on Meleis and colleagues' Transition Theory and a literature review to explain women's menopausal transition, constructing a modified model considering previous studies and model fit and testing the effects between variables. Methods: With a correlational survey design, middle-aged Korean women aged 40 to 64 years who had experienced menopausal symptoms were recruited and filled out a self-administered study questionnaire. Measures included menopausal symptoms, resilience, social support, menopause management, menopause adaptation, and quality of life. The data were analyzed using SPSS 24.0 and AMOS 24.0. Results: The model fit indices were considered acceptable: 𝛘²/degree of freedom=2.93, standardized root mean residual=.07, comparative fit index=.90, and parsimonious normed fit index=.73. All eight direct-effect paths-from menopausal symptoms to support and adaptation, from support to adaptation and resilience, from resilience to adaptation and management, from management to quality of life, and from adaptation to quality of life-were significant. The explanatory power of the menopause transition model was 63.6%. Conclusion: Women who experience menopausal symptoms may be able to maintain and improve their quality of life if menopause management and menopause adaptation are successful through resilience and social support. Future research is needed to confirm whether strengthening facilitation as a nursing intervention strategy may promote healthy response patterns.

• The Korean Journal of Rehabilitation Nursing
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• v.2 no.1
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• pp.61-71
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• 1999

This quasi-experimental study was intended to test the effect of self-help group program, which is one of the way to enhance adaptation and quality of life to mastectomy patients. Data was collected from July 14, 1998 to Oct. 31, 1998 at two Medical Center in Seoul. The subjects for this study were the patients who had undergone mastectomy and were follow-up ; 14 in experimental group and 14 in control group matched with age and treatment. The instruments for this study were adaptation in Lee(1994)'s physical symptom questionnaire, Zung's Self-rating Depression Scale(SDS, 1965), and Self-rating Anxiety Scale(SAS, 1970), quality of life in Spranger(1996)'s and No(1988)'s Quality of Life Questionnaire. The self-help group program for mastectomy patients was developed based on literature review and pilot study by the investigator. The subjects of experimental group were participated in 6 weeks self-help group program and were received arm and shoulder exercise, informational support, and interpersonal support by group members. The control group were received no intervention, Both group answered questionnaires prior to intervention and 6 weeks later. The data analyzed by frequency, $X^2$-test, Mann-Whitney U test. Wilcoxon Signed Rank test, Pearson's Correlation Coefficient and Stepwise Multiple Regression using SPSS WIN. The results are as follows ; Hypothesis 1. "The experimental group with the self-help group program will have a higher score on adaptation state than control group." was not supported. But the post test score of anxiety and depression in experimental group were declined and the depression score was reduced relatively. Hypothesis 2. "The experimental group with the self-help group program will have a higher score on quality of life than control group." was not supported. But the posttest score of quality of life in experimental group was reduced relatively. Hypothesis 3. "The higher adaptation state of mastectomy patients, the higher quality, of life." was supported(r=,80, p<.001). Additionally, the lower physical symptom, depression and anxiety, the higher quality of life And depression, which was the main predictor of quality of life, accounted for 59.5%, depression and anxiety accounted for 65.5% of the variance in quality of life. In conclusion, when the self-help group program was intervened to mastectomy patients, it was tended to increase quality of life and to reduce depression and anxiety. So self-help group program can be considered useful nursing inter vention effect on adaptation and quality of life of mastectomy patients. With discussion, I suggest repeated further re search on self-help group with appropriate sample size and longitudinal study. Also during adjuvant therapy, it is needed to develop convenient method to be supported from peer group and family, such as computer mediated support group.

• Journal of KIISE
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• v.44 no.1
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• pp.95-106
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• 2017

HTTP adaptive streaming has recently emerged to handle the rapidly growing traffic and to provide high quality multimedia contents. To improve the QoE (Quality of Experience) for HTTP adaptive streaming service, the average video bitrate should be maximized, and the video switching frequency (difference of bitrate between adjacent segments) and video stalling events need to be minimized. The recently proposed quality adaptation algorithms for HTTP adaptive streaming do not provide high QoE, since detailed QoE factors such as video switching frequency and bitrate difference of adjacent segments, are not considered. In this paper, we propose a SQA (Smooth Quality Adaptation) algorithm to improve the user QoE. The proposed algorithm provides the smoothed QoE, such that it minimizes the unnecessary video switching events by maintaining the quality in a certain period, thus minimizing the bitrate difference of adjacent segments. Through simulation, we confirm that the proposed algorithm reduces the unnecessary switching events, and prevents the sudden decrease in video quality.

• Journal of Broadcast Engineering
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• v.14 no.1
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• pp.44-58
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• 2009

To provide efficient video streaming service over a wireless networks, the rate adaptation scheme should be applied at the low layer and the quality adaptation scheme should be considered at the high layer. In this paper, we propose a new cross-layer design which includes rate adaptation scheme at the MAC/PHY layers and quality control at the application layer. Proposed rate adaptation scheme improves the wireless channel utilization by transmitting the consecutive frames and selects optimal transmission mode by calculating the goodputs for each transmission mode. Based on selected transmission mode, the rate adaptation scheme calculates the rate limits and informs that to the application layer. Then the video streaming application utilizes this rate limits to adjust the quality of the video stream. Through performance evaluations, we prove that our cross-layer design improves the quality of the wireless video streaming service by means of the proposed rate adaptation scheme.