• ETRI Journal
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• 제43권3호
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• pp.447-458
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• 2021

The quality of experience (QoE) of video streaming is degraded by playback interruptions, which can be mitigated by the playout buffers of end users. To analyze the impact of playout buffer dynamics on the QoE of wireless adaptive hypertext transfer protocol (HTTP) progressive video, we model the playout buffer as a G/D/1 queue with an arbitrary packet arrival rate and deterministic service time. Because all video packets within a block must be available in the playout buffer before that block is decoded, playback interruption can occur even when the playout buffer is non-empty. We analyze the queue length evolution of the playout buffer using diffusion approximation. Closed-form expressions for user-perceived video quality are derived in terms of the buffering delay, playback duration, and interruption probability for an infinite buffer size, the packet loss probability and re-buffering probability for a finite buffer size. Simulation results verify our theoretical analysis and reveal that the impact of playout buffer dynamics on QoE is content dependent, which can contribute to the design of QoE-driven wireless adaptive HTTP progressive video management.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1769-1778
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• 2009

산업의 발달 및 도시화의 증가로 인해 위험물질을 포함한 물류 수송량은 날로 증가하는 추세이고 위험물질 수송차량들의 사고발생 위험도 따라서 증대되고 있다. 본 연구에서는 위험물 운송이 점차 증가하고 있는 철도수송에 있어 기존 선행 연구의 피해규모 분석모형을 적용하고, 위험물 물류 표준화 연구에서 정의된 물질별 사고노출량을 기준으로 하여 위험물 물질별 인구 및 환경 노출규모를 GIS(Geographic Information System)의 버퍼링 분석 기 법을 통하여 일반적으로 분석이 어려운 피해규모산정을 자동으로 도출하는 방안을 제시하였다. 각 링크별 인구 및 노출규모 산출 모형을 적용하기 위해서는 Network(철도망), Zone(행정구역), 철도사고 Data, 철도화물 통행량, 하천 및 강 등을 GIS Database로 구축하였고, 최종적으로 Buffering 분석과 함께, 중첩분석의 Clip 기법과 Special Join 기법을 함께 사용하여 본연구의 제시한 위험물 물질별 피해규모 자동 추출 방안을 제시해 보았다.

• Journal of Dental Anesthesia and Pain Medicine
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• 제20권5호
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• pp.271-279
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• 2020

Background: The present study aimed to evaluate and compare the efficacy of buffered and unbuffered local anesthesia solutions during inferior alveolar nerve block (IANB) administration in children. Methods: PubMed, Ovid SP, and Cochrane databases were searched separately by two independent reviewers for potential papers published between 1980 and April 2020 using relevant MeSH terms and pre-specified inclusion and exclusion criteria. T Studies of IANB administration in children comparing buffered and unbuffered local anesthesia solutions were evaluated. The primary outcome evaluated was pain (perception and reaction), while the secondary outcome was the onset of anesthesia. Results: A total of five articles were included in a qualitative analysis; among them, four qualified for quantitative analysis of the primary outcome and three for quantitative analysis of the secondary outcome. A fixed-effects model was used to perform the meta-analysis. Pain perception (child-reported pain): Significantly lower pain scores were reported with buffered local anesthesia solution than with unbuffered solution (P = 0.006, MD: -0.32, 95% CI: -0.55 to -0.09). Pain reaction (observer-reported pain reaction in child): No significant difference was found between buffered and unbuffered solution in terms of observer-reported pain behavior in the child (P = 0.09, MD: -0.21, 95% CI: -0.46 to 0.04). Onset of anesthesia: A significantly lower duration of anesthesia onset was reported with buffered local anesthesia solution than with unbuffered solution (P = 0.00001, MD: -12.38, 95% CI: -17.64 to -7.13]. Conclusion: Buffering local anesthesia solution may reduce discomfort due to IANB injection administration and lower the initial onset time of anesthesia. More randomized control trials with adequate sample sizes should be carried out to validate the accuracy of these results.

• 치위생과학회지
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• 제10권6호
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• pp.465-472
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• 2010

본 연구에서는 20대 여대생에게 개인에 따라 치아우식증 발생에 작용하는 서로 다른 요인을 찾아내기 위해 치아우식병 발생요인 중 타액요인을 집중적으로 분석하고자 타액분비율, 타액점조도, 타액완충능을 조사하였으며, 치면세균막내 산체류도 치아우식증에 큰 영향을 주기에 치면세균막 수소이온농도를 함께 조사 하여 비교 분석한 결과는 다음과 같다. 다음과 같은 분석결과는 20대 여대생의 치아우식활성검사 결과판독의 기초자료를 제공하고, 치아우식증 발생요인을 규명하는데 기초자료를 제공하고자 실시되었다. 1. 조사 대상자의 평균 우식치아는 1.67개 이었으며, 치아우식으로 인한 발거치아는 0.47개 충전치아는 6.31개로 나타났다. 따라서 평균 영구치우식경험치아는 8.44개로 조사되었다. 2. 치아우식활성검사 방법에 따른 성적으로는 평균 자극성타액분비량은 $12.56{\pm}4.15ml$, 비자극성타액분비량은 $3.89{\pm}1.83ml$, 타액점조도는 $1.49{\pm}0.69$, 타액완충능은 $8.51{\pm}2.44$, 치면세균막 수소이온농도검사는 양치전 $5.62{\pm}0.50$, 양치후 5분 $5.23{\pm}0.58$, 양치후 10분 $5.25{\pm}0.56$, 양치후 15분 $5.29{\pm}0.62$, 양치후 20분 $5.34{\pm}0.58$, 양치후 25분 $5.40{\pm}0.53$, 양치후 30분 $5.61{\pm}0.59$로 나타났다. 3. 자극성타액 및 비자극성타액 분비량, 타액점조도, 타액완충능은 비우식집단이 우식집단 보다 높게 나타났으나, 통계적으로는 유의하지 않았다. 치면세균막 수소이온 농도는 진행 중인 치아우식증이 있는 자와의 관계에서도 전체적으로 통계적인 유의성을 나타내지 않았으나, 비우식집단이 우식집단보다 높게 나타났다. 4. 우식활성검사방법간의 상관관계는 자극성타액분비량은 비자극성 타액분비량과는 유의한 양의 상관이 있었으며(p<0.001), 비자극성타액분비량은 타액완충능과 음의 상관을 나타냈다(p<0.01). 치면세균막 수소이온농도 검사는 양치후 시간이 경과함에 따라 양의 상관을 보였으나, 타액점조도 및 타액완충능과는 유의한 상관이 없었다(p>0.05).

• 대한지리학회지
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• 제36권3호
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• pp.329-341
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• 2001

본 연구는 도시내, 특히 도심에서 범죄 분포가 갖는 의미를 지리학적으로 밝히려고 하였다. 청주시 도심지 역의 범죄 발생의 특징은 폭력 범죄와 절도 범죄가 많고 상대적으로 강력 범죄의 발생률은 낮다. 도심지역 내의 범죄 발생 장소는 연령별. 범죄 유형별로 분리되어 나타난다. 연령별로는 중앙시장과 풍물시장 주변이 30대 이상. 성안 길 주변이 10, 20 대의 피의자가 많다. 범죄 유형별로는 풍물시장과 중앙공원 주변에서 폭력 범죄가 많이 나타나고. 중앙시장과 성안길 입구는 폭력과 절도 범죄가 혼합되어 나타난다. 도심지역의 폭력 범죄는 유흥업소 주변에서 음주 후 발생하는 경우가 많고, 절도 범죄는 도심지역의 많은 유동인구라 물품 판매를 하는 기능테라 관련이 높다. 도심지역의 도로 버퍼링 분서 결과, 2차선 이상의 도로 영향권에서 발생한 범죄는 40%가 설명이 된다. 나머지 60%는 골목길과 소로길에서 발생하였다.

• ETRI Journal
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• 제33권1호
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• pp.136-139
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• 2011

A modular upgrade design for packet transport switch nodes is presented where packet loss is dramatically reduced by intra-module and inter-module buffer sharing. This modular design offers significant cost and power reduction in a high-data-rate system where buffers are highly costly and power-greedy.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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• pp.91-94
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• 2000

This paper introduces the design of low-power, fast-locking delay locked-loop using complementary pass transistor logic(CPL). Low-power design has become one of the most important in the modem VLSI application. CPL has the advantage of fast speed, high density, and low power with signal buffering between stages. Based on this analysis, we concluded that the I/O performance can be beyond 500㎒, 2-poly, 2-metal 0.65$\mu\textrm{m}$, 3.3V supply.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.297-300
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• 2001

This paper proposes a sound multicast packet-switching method which can less affect QoS degradation. The method includes a switch fabric with extra switching paths dedicated for multicast packets. Presented also are both a buffering structure and a scheduling algorithm for the proposed method. Simulation analysis for the method shows that the switching delay of unicast packets is decreased even though arrival rate of multicast packets is increased.

• 한국GIS학회:학술대회논문집
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• 한국GIS학회 2002년도 춘계학술대회논문집
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• pp.153-159
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• 2002

This study mainly concentrates on the development of a land information management system to manage the land related information in an effective way for the water-pollutant buffering zone, which was established to sustain better quality of the drinking water over the upper part of the Han river. For developing such system, a procedure was implemented covering user requirement analysis, system design, spatial DB design, and coding. DB linkage with affiliated institutes and cadastral DB updating were proposed as the part of the efforts to enhance the applicability of the system. In addition to that, modularization was adopted for more efficient and cost-effective system development.

• Journal of Preventive Medicine and Public Health
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• 제29권2호
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• pp.295-309
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• 1996

The purpose of this study is to investigate the effect of job stress and social support on the organizational effectiveness of hospital employees and to examine the role of social support in the experience of job stress among the employees. Previous studies have yielded mixed results regarding the role of social support. Some studies provide supporting evidence for the buffering effect of social support, while others do not. Still others report findings about reverse buffering effects. These inconsistent findings are, in part, accounted for by methodological problems such as poor measurement, small sample size, and the existence of high multicollinearity. To examine more rigorously the role of social support in relation to the negative effects of job stress, this study was carefully designed to overcome methodolgical shortcomings found in the past research. In addition, unlike the previous studies, which were concerned mostly with health-related variables as consequences of job stress, in this study, three work-related variables (job satisfaction, organizational commitment, and intent to stay) which had close relationships with organizational effectiveness were examined as output variables. The sample used in this study consisted of 353 employees from a university hospital in the surburbs of Seoul. Data were collected with self-administered questionnaires and analyzed using canonical analysis and hierarchical regression analysis. The results of this study indicate that; (1) job stress has negative main effects on job satisfaction, organizational commitment, and intent to stay; (2) social support has positive main effects on the same three output variables, (3) social support does not moderate the harmful effects of job stress on the three outcome variables, and (4) the three-way interaction effects of (social support * job stress * gender) and of (social support * job stress * education) are not supported. The implications of these findings for the management of human resources are discussed.