• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.547-566
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• 2014

This study investigates the decisive factors affecting the survival or collapse of cable networks in the Korean paid broadcasting market from 1993 to 2010. The effects of performance variables discussed in previous studies were verified through survival analyses. According to the results, the most influential factors in the survival of cable networks were horizontal integration (MPP), channel genre, the scheduling of HDTV content, and the proportion of access program scheduling. These findings imply that the differentiation strategy of content suppliers is the most decisive factor among all business performance-related factors. Specifically, the content supply power and strategy of the program provider (PP) have the greatest influence on cable network viability. The present study is meaningful as the first attempt to establish the performance of PPs in Korean pay broadcasting markets through the viewpoint of organizational mortality. Accordingly, the present study can supplement the results of cross-sectional studies conducted with smaller samples.

• 공업화학
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• 제4권3호
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• pp.544-548
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• 1993

Poly(phenylene sulfide sulfone)[PPSS]를 시간과 온도를 변화시키면서 열처리를 하였을 때 이들의 유리전이 온도($T_g$)를 DSC로서 조사하였다. 그 결과 PPSS의 $T_g$는 열처리온도가 $230^{\circ}C$까지는 열처리 시간이 길어질수록 증가하다가 평형에 도달하였다. 열처리 온도가 $245^{\circ}C$ 이상에서는 열처리 시간이 길어질수록 $T_g$가 증가하다가 어느 정도 시간이 되면 감소한 뒤 다시 증가하는 것으로 나타났다. 이 현상을 경화가 진행됨에 따른 chain extension반응과 oxidative crosslinking 및 thermal crosslinking으로 설명하였다.

• Journal of Oral Medicine and Pain
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• 제23권1호
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• pp.1-9
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• 1998

The aim of the study was to evaluate the anesthetic Effecs of pulsed Nd:YAG laser irradiation to the oral mucosa and the teeth. Twenty subjects who didn't have a history of significant systemic or current oral disease were included in this study. All the subjects were divided randomly into the experimental group and the control group with 10 for each group. Pain thresholds were measured with Weighted Needle Pinprick Sensory Threshold Test for the mucosal surface of lower lip and with electric pulp test for the upper right central incisor respectively, before and immediately after pulsed Nd:YAG laser irradiation in the condition of 2 watt, 20pps for 2 minute at 10mm distance. The experiment was double-blinded clinical trial. The results were as follows : 1. The mean pain threshold of the mucosal surface of lower lip for Weighted Needle Pinprick Sensory Threshold Test was 2.94(1.00g for the contral group respectively, and there was no statistical difference between two groups. 2. The mean pain threshold of the mucosal surface of lower lip was significantly increased immediately after pulsed Nd:YAG laser irradiation. 3. The mean pain threshold of the upper right central incisor for eledtric pulp test was 34.50(4.97V in the experimental group and 34.00(13.08V in the control group respectively, and there was no statistical difference between two groups. 4. The mean pain threshold of the upper right central incisor was significantly increased immediately after pulsed Nd:YAG laser irradiation.

• 한국BIM학회 논문집
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• 제6권2호
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• pp.1-11
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• 2016

In South Korea, there have been attempts to enhance BIM work practices in various aspects. Public Procurement Service(PPS) has recently published 'basic guidelines to improve BIM work practices in construction and facility management'. It defines roles and responsibilities of project members in their application of BIM. It also developed a set of modelling standards and guidelines for effective model creation, management and communication among BIM users. Moreover, numerous construction companies have tried to cultivate BIM specialized manpower throughout entire construction phases. However, there are still challenges faced by firms during BIM adoption. Therefore, this study aims to provide practical counsel for construction companies to help them create optimized facilities and deliver high performance by analyzing BIM-based domestic construction projects in Korea from 2009 and 2015. The study will investigate types of client, project, BIM application range, and application technology.

• 대한통합의학회지
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• 제2권3호
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• pp.31-37
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• 2014

Purpose : Delayed onset muscle soreness(DOMS) is a common problem that can interfere with rehabilitation as well as activities of daily living. The purpose of this study was to compare the effect of both trascutaneous electrical nerve stimulation(TENS) Micro current(MC) and only normal Therapy on Delyed Onset Muscle Soreness(DOMS). Method : The Methods ten untrained and male volunteer subjects were randomly assigned to one of two treatment groups: 1) a group that received TENS (60Hz) MC($60{\mu}A$, 3pps) a control group that received no MC treatment. Subjects performed repeated eccentric exercise of the non-dominant forearm flexor muscle with submaximal intensity by the simply designed eccentric exercise devices. Treatments were applied after 24hours and 48hours. Subjects attended on two consecutive days for treatment and measurement of paining(visual analogue scale: VAS) and CK(Creatine kinase) on a daily basis. Measurements were taken after treatment. Results : 1) There were no significant differences between TENS and MENS by two-way repeated ANOVA. The Results that t-test for VAS revealed significant differences within TENS group. 3) The t-test for VAS, and Creatine Kinase of time revealed significant differences within MC group. Conclusion : These findings suggest that both TENS and MENS had effect on DOMS.

• Communications for Statistical Applications and Methods
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• 제15권6호
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• pp.883-897
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• 2008

2006년 통계청이 시행한 광업 제조업 통계조사 결과(2005년 실적치)를 모집단으로 사용하면 최근 동향을 반영한 표본설계가 가능하다. 본 논문은 기존의 12개 업종보다 세분화된 94개 세부업종에 분류에 따라 매월 부품 소재산업의 생산, 출하, 재고의 변동사항을 조사하여 부품 소재산업의 경기변동실태를 파악하고 부품 소재산업의 육성정책 및 기업경영의 기초자료를 제공할 수 있는 새로운 표본설계를 제안한다. 표본설계는 응용절사법과 주성분을 이용한 다변량 네이만 배정법을 이용하여 층별로 표본크기를 결정하여 배정하고 표본추출은 확률비례계통추출을 사용한다.

• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.311-320
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• 1996

If root and resection is done during surgical endodontic treatment, newly exposed dentinal tubules form pathways between the canal and the peripheral tissue. Nd : YAG laser was used to block this phenomenon, and its effect was studied with dye penetration and SEM techniques. 40 intact single rooted teeth were divided into 4 groups(10 each) : control group and test groups, in which retrograde cavity surface, cutting surface, retrograde cavity surface & cutting surface were treated with laser(1 watt 15pps) and finally retrograde filling with IRM was conducted. After that, they were stained with 2 % methylene blue, sectioned and evaluated by the maximum infiltration depth. And to observe surface change, they were prepared for SEM. The results were as follows ; 1. All experimental groups showed microleakage with variation in amount. 2. The 2nd group which treated both the retrograde cavity and cutting surface showed significantly less microleakage than the other groups(p<0.05). There was no significant difference between groups treated on one side only. 3. As a result of SEM observation of dentin surface, obstruction of dentinal tubules with marble shaped granules, which were different from normal dentin could be seen. Cracks could be seen also. 4. In summary of this experiment, it is thought that effort to obstruct the exposed dentinal tubules as well as retrograde cavity after root end resection is needed.

• Journal of Oral Medicine and Pain
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• 제21권1호
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• pp.183-196
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• 1996

The author examined the clinical and histological changes on the dorsal tongue mucosa of adult Sprague-Dawley rats after lasing by pulsed Nd:YAG laser. The dorsal tongue was lased for 3 seconds by 1.5, 2.0, 2.5, 3.0, 3.5, 4.0W and 10, 15, 20, 20pps. After tissue changes were observed clinically, the excised samples were observed histologically and the width of tissue destruction was analyzed quantitatively under the Confocal laser microscope respectively. The following results were obtained : 1. Whitening of peripheral tissue was observed more as increasing pulsed per second (Hz) below power 2.5W and observed at all parameters above power 3.0W. 2. Charring of mucosal surface was observed at all parameters but mild at parameters below power 2.0W. 3. The destruction of epithelium was observed at all parameters and tissue destruction was extended to lamina propria at higher pulses per second. 4. The width of tissue destruction was more widening as increasing energies per pulse (p<0.001) and the narrowest at 20Hz than 10Hz, 15Hz and 30Hz(p<0.05). As the above results, author suggests power below-3.5W and 20Hz as the lasing parameters for oral soft tissue therapy.

• 전기학회논문지
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• 제58권6호
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• pp.1100-1104
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• 2009

As national power consumption every year increases, the power plant which is in the process of planning tries to establish high-capacity generator. The power system tends to become a large size. With the progress of electronic components, the control systems of the generator have been digitalized and rapid-response control system is possible. However, the minute frequency vibration of grid occurred with the effect of rapid-response control system. To solve these problem, PPS(Power System Stability) has been introduced since 2004, and it has being installed and applied to the thermal and nuclear power plant which are high-capacity, over 800MVA. However the minute frequency vibration is gradually changed to the bigger frequency vibration by fast-action control system, and this regional frequency fluctuation might be diffused wide area. Therefore, it is applied to the hydro generator which is small with fast-action governor system, and it is necessary to control the minute frequency vibration to prevent to diffuse. In this paper, the effect will be proved by establishing PSS on the Hydro-Generator which has both digital excitation and governor system for the first time in Korea.

• 대한기계학회논문집A
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• 제21권11호
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• pp.1871-1884
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• 1997

This paper describes the design process of a 3-component load cell with a multiple parallel plate structure which may be used to measure transverse forces and twisting moment simultaneously. Also we have derived equations to predict the bending strains on the surface of the beams in the multiple parallel plate structure under transverse force or twisting moment. It reveals that the bending strains calculated from the derived equations are in good agreement with the results from finite element analysis and experiment. Also we have evaluated the rated output and interference error of each component, which can be efficiently used to design a 3-component load cell with a multiple parallel plate structure.