• Title/Summary/Keyword: Model following control

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The Effects of 8-week Ketone Body Supplementation on Endurance Exercise Performance and Autophagy in the Skeletal Muscle of Mice (8주 케톤체 투여가 마우스 지구성 운동수행능력과 골격근의 자가포식에 미치는 영향)

  • Jeong-sun Ju;Min-joo Park;Dal-woo Lee;Dong-won Lee
    • Journal of Life Science
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    • v.33 no.3
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    • pp.242-251
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    • 2023
  • The purpose of this study was to investigate the effects of 8-week β-hydroxybutyrate (β-HB) administration with and without endurance exercise training on endurance exercise performance and skeletal muscle protein synthesis and degradation using a mouse model. Forty-eight male wild-type ICR mice (8 weeks old) were randomly divided into four groups: sedentary control (Sed+Con), (Sed+Con), sedentary β-HB (Sed+β-HB), exercise control (Exe+Con), and exercise β-HB (Exe+β-HB). β-HB was dissolved in PBS (150 mg/ml) and injected subcutaneously daily (250 mg/kg) for 8 weeks. Mice performed 5 days/week of a 20 min treadmill running exercise for 8 weeks. The running exercise was carried out at a speed of 10 m/min at a 10° incline for 5 min, and then the speed was increased by 1 m/min for every 1 min of the remaining 15 min. Following 8 weeks of treatments, visceral fat mass and skeletal muscle mass, blood parameters, and the markers for autophagy and protein synthesis were analyzed. The data were analyzed with one-way ANOVA (p<0.05) using the SPSS 21 program. Eight weeks of Exe+β-HB treatment significantly lowered blood lactate levels compared with the other three groups (Sed+Con, Sed+β-HB, and Exe+β-HB) Exe+β-HB) (p<0.05). Eight weeks of Exe+β-HB significantly increased maximal running time (time to exhaustion) compared with the Sed+Con and Exe+Con groups (p<0.05). Eight weeks of β-HB administration significantly decreased autophagy flux and autophagy-related proteins in the skeletal muscle of mice (p<0.05). Conversely, the combined treatment of β-HB and endurance exercise training increased protein synthesis (mTOR signaling and translation) (p<0.05). The 8-week β-HB treatment and endurance exercise training had synergistic effects on the increase in endurance performance, increase in protein synthesis, and decrease in protein degradation in the skeletal muscle of mice.

Neuroprotection of Recombinant Human Erythropoietin Via Modulation of N-methyl-D-aspartate Receptors in Neonatal Rats with Hypoxic-ischemic Brain Injury (신생 백서의 저산소성 허혈성 뇌손상에서 NMDA receptor 조절을 통한 유전자 재조합 인 에리스로포이에틴의 신경보호)

  • Jang, Yoon-Jung;Seo, Eok-Su;Kim, Woo-Taek
    • Neonatal Medicine
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    • v.16 no.2
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    • pp.221-233
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    • 2009
  • Purpose: Erythropoietin (EPO) has neuroprotective effects in many animal models of brain injury, including hypoxic-ischemic (HI) encephalopathy, trauma, and excitotoxicity. Current studies have demonstrated the neuroprotective effects of EPO, but limited data are available for the neonatal periods. Here in we investigated whether recombinant human EPO (rHuEPO) can protect the developing rat brain from HI injury via modulation of NMDA receptors. Methods: In an in vitro model, embryonic cortical neuronal cell cultures from Sprague-Dawley (SD) rats at 19-days gestation were established. The cultured cells were divided into five groups: normoxia (N), hypoxia (H), and 1, 10, and 100 IU/mL rHuEPO-treated (H+E1, H+ E10, and H+E100) groups. To estimate cell viability and growth, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was done. In an in vivo model, left carotid artery ligation was performed on 7-day-old SD rat pups. The animals were divided into six groups; normoxia control (NC), normoxia Sham-operated (NS), hypoxia-ischemia only (H), hypoxia-ischemia+vehicle (HV), hypoxia-ischemia+rHuEPO before a HI injury (HE-B), and hypoxia-ischemia+rHuEPO after a HI injury (HE-A). The morphologic changes following brain injuries were noted using hematoxylin and eosin (H/E) staining. Real-time PCR using primers of subunits of NMDA receptors (NR1, NR2A, NR2B, NR2C and NR2D) mRNA were performed. Results: Cell viability in the H group was decreased to less than 60% of that in the N group. In the H+E1 and H+E10 groups, cell viability was increased to >80% of the N group, but cell viability in the H+E100 group did not recover. The percentage of the left hemisphere area compared the to the right hemisphere area were 98.9% in the NC group, 99.1% in the NS group, 57.1% in the H group, 57.0% in the HV group, 87.6% in the HE-B group, and 91.6% in the HE-A group. Real-time PCR analysis of the expressions of subunits of NMDA receptors mRNAs in the in vitro and in vivo neonatal HI brain injuries generally revealed that the expression in the H group was decreased compared to the N group and the expressions in the rHuEPO-treated groups was increased compared to the H group. Conclusion: rHuEPO has neuroprotective property in perinatal HI brain injury via modulation of N-methyl-D-aspartate receptors.

A Study on the Cultivation Processes and Settlement Developments on the Mangyoung River Valley (만경강유역의 개간과정과 취락형성발달에 관한 연구)

  • NamGoong, Bong
    • Journal of the Korean association of regional geographers
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    • v.3 no.2
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    • pp.37-87
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    • 1997
  • As a results of researches on the cultivation processes and settlement developments on the Mangyoung river valley as a whole could be have four 'Space-Time Continuity' through a [Origin-Destination] theory model. On a initial phases of cultivation, the cultivation process has been begun at mountain slopes and tributory plains in upper part of river-basin from Koryo Dynasty to early Chosun Dynasty. At first, indigenous peasants burned forests on the mountain slopes for making 'dryfield' for a cereal crops. Following population increase more stable food supply is necessary facets of life inducing a change production method into a 'wetfield' in tributory plains matching the population increase. First sedentary agriculture maybe initiated at this mountain slopes and tributory plains on upper part of river basin through a burning cultivation methods. Mountain slopes and tributory plains are become a Origin area in cultivation processes. It expanded from up to down through the valleys with 'a bits of land' fashion in a steady pace like a terraced fields expanded with bit by bit of land to downward. They expanded their land to the middle part of river basin in mid period of Chosun Dynasty with dike construction techniques on the river bank. Lower part of river cultivated with embankment building techniques in 1920s and then naturally expanded to the tidal marshes on the estuaries and river inlets of coastal areas. 'Pioneer fringes' are consolidated at there in modern times. Changes in landscapes are appeared it's own characters with each periods of time. Followings are results of study through the Mangyoung river valley as a whole. (1) Mountain slopes and tributory plains on the upper part of river are cultivated 'dryfields' by indigenous peasants with Burning cultivation methods at first and developed sedentary settlements at the edges of mountain slopes and on the river terrace near the fields. They formed a kind of 'periphery-located cluster type' of settlement. This type of settlement are become a prominant type in upper part of river basin. 'Dryfields' has been changed into a 'wetfields' at the narrow tributory plains by increasing population pressure in later time. These wetfields are supplied water by Weir and Ponds Irrigation System(제언수리방법). Streams on the tributory plains has been attracted wetfields besides of it and formed a [water+land] complex on it. 'Wetfields' are expanded from up to downward with a terraced land pattern(adder like pattern, 붕전) according to the gradient of valley. These periphery located settlements are formed a intimate ecological linkage with several sets of surroundings. Inner villages are expanded to Outer villages according to the expansion of arable lands into downward. (2) Mountain slopes and tributory plains expanded its territory to the alluvial deposited plains on the middle part of river valley with a urgent need of new land by population increase. This part of alluvial plains are cultivated mainly in mid period of Chosun Dynasty. Irrigation methods are changed into a Dike Construction Irrigation method(천방수리방법) for the control of floods. It has a trend to change the subjectives of cultivation from community-oriented one who constructed Bochang along tributories making rice paddies to local government authorities who could be gather large sums of capitals, techniques and labours for the big dike construction affairs. Settlements are advanced in the midst of plains avoiding friction of distances and formed a 'Centrallocated cluster type' of settlements. There occured a hierarchical structures of settlements in ranks and sizes according merits of water supply and transportation convenience at the broad plains. Big towns are developed at there. It strengthened a more prominant [water+land] complex along the canals. Ecological linkages between settlements and surroundings are shaded out into a tiny one in this area. (3) It is very necessary to get a modern technology of flood control at the rivers that have a large volume of water and broad width. The alluvial plains are remained in a wilderness phase until a technical level reached a large artificial levee construction ability that could protect the arable land from flood. Until that time on most of alluvial land at the lower part of river are remained a wilderness of overgrown with reeds in lacks of techniques to build a large-scale artificial levee along the riverbank. Cultivation processes are progressed in a large scale one by Japanese agricultural companies with [River Rennovation Project] of central government in 1920s. Large scale artificial levees are constructed along the riverbank. Subjectives of cultivation are changed from Korean peasants to Japanese agricultural companies and Korean peasants fell down as a tenant in a colonial situation of that time in Korea. They could not have any voices in planning of spatial structure and decreased their role in planning. Newly cultivated lands are reflected company's intensions, objectives and perspectives for achieving their goals for the sake of colonial power. Newly cultivated lands are planned into a regular Rectangular Block settings of rice paddies and implanted a large scale Bureaucratic-oriented Irrigation System on the cultivated plains. Every settlements are located in the midst of rice paddies with a Central located Cluster type of settlements. [water+land] complex along the canal system are more strengthened. Cultivated space has a characters of [I-IT] landscapes. (4) Artificial levees are connected into a coastal emnankment for a reclamation of broad tidal marshes on the estuaries and inlets of rivers in the colonial times. Subjectives of reclamation are enlarged into a big agricultural companies that could be acted a role as a big cultivator. After that time on most of reclamation project of tidal marshes are controlled by these agricultural companies formed by mostly Japanese capitalists. Reclaimed lands on the estuaries and river inlets are under hands of agricultural companies and all the spatial structures are formed by their intensions, objectives and perspectives. They constructed a Unit Farming Area for the sake of companies. Spatial structures are planned in a regular one with broad arable land for the rice production of rectangular blocks, regular canal systems and tank reservoir for the irrigation water supply into reclaimed lands. There developed a 'Central-located linear type' of settlements in midst of reclaimed land. These settlements are settled in a detail program upon this newly reclaimed land at once with a master plan and they have planned patterns in their distribution, building materials, location, and form. Ecological linkage between Newly settled settlemrnts and its surroundings are lost its colours and became a more artificial one by human-centred environment. [I-IT] landscapes are become more prominant. This region is a destination area of [Origin-Destination] theory model and formed a 'Pioneer Fringe'. It is a kind of pioneer front that could advance or retreat discontinously by physical conditions and socio-cultural conditions of that region.

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A Study on the Resilience Process of Persons with Disabilities (중도장애인의 레질리언스(Resilience) 과정에 관한 연구)

  • Kim, Mi-Ok
    • Korean Journal of Social Welfare
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    • v.60 no.2
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    • pp.99-129
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    • 2008
  • This study analyzed the resilience process of persons with disabilities using the grounded theory approach. To conduct this study, the researcher conducted in-depth interviews with 8 persons with disabilities. In data analysis, this study identified 393 concepts on the resilience process of persons with disabilities and the concepts were categorized into 45 sub-categories and 18 primary categories. In the paradigm model on the resilience process of persons with disabilities, it was identified that casual conditions included 'unawareness of disability before being disability', 'extreme pain', 'repressing psychological pain', and the contingent conditions were 'dis-empowerment by staying in home', 'isolation by himself with difficulty in accepting the disability', 'experience of frustration from social barriers with prejudice against persons with disabilities'. Also, it was identified that the resilience process could be dependent on the type and the degree of the disability, the gender, and the length of time being disability. In spite of the casual and contingent conditions, the central way in which persons with disabilities could acquire resilience was identified as 'enhancement of the power of positive thinking'. The control conditions which accelerate or retard central phenomenon were 'the awareness of not being alone through family, friends, neighborhood and the social system' externally and 'finding purpose in life through religion and help from other persons with disabilities', internally. The action/interactional sequences enhanced the efforts, self searching and active acting, and as a result, persons with disabilities could find comfort in life, participate in society and change the perspective of disability in society. The core categories of resilience process in persons with disabilities were a belief in affirmation and choice of life by initiative. In the process analysis, stages developed in the following: 'pain', 'strangeness', 'reflection', 'daily life'. This stage was more continuous and causal than discrete and complete. In this process, the types of resilience of persons with disabilities are divided into 'existence reflection', 'course development', 'implicit endeavor', and 'active execution'. This study showed the details of the paradigm models, the process and types with an in-depth understanding of the resilience process of persons with disabilities using grounded theory as well as theory construction and policy and clinical involvement on the study of persons with disabilities.

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The Application of Customer Relationship Management for the Effective Prenatal Care (효과적인 산전관리를 위한 고객관계관리(CRM)의 도입)

  • Shin, Sook;Paik, Soo-Kyung;Kang, Sung-Hong;Kim, Yu-Mi
    • Korea Journal of Hospital Management
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    • v.10 no.1
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    • pp.93-114
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    • 2005
  • The prenatal care is the preventive medical service to help the pregnant mother deliver the healthy baby. It's regular examines give some chances to check-up the healthy conditions. This thesis concentrates on the CRM system to support an effective prenatal care system and prove the effectiveness of it. As CRM is the adapted management related to the customer's own information, it is important to develop the CRM model classified by the patients characteristics. A general hospital in Busan operated the CRM system to carry out the effective prenatal care and there is an analysis to ensure the effectiveness of CRM system for the pregnant women in our maternity ward. The results can be summarized as follows: 1) According to the comparisons with the CRM system, we can conclude the system is desirable. (1) Maternal Age : In the age distribution, the prenatal visit frequency, triple marker freqency, oral GTT and targeted ultrasonography in the experimental group in 30 to 34 years old is higher on the whole. For over 35 years old group, the higher frequency comes out in the oral GTT and targeted ultrasonography and for 25 to 29 years old group the different figure shows just in the targeted ultrasonography. (2) Area of residence: There is a clear difference in all the items in Busan and near area but no sign of difference in prenatal visits and oral GTT in other residencial area. Especially in the targeted ultrasonography the higher figure shows in the experimental group located in the both areas. The targeted ultrasonography is known as the specific examination which should be examined by the specialists, on the contrary the other examinations can be operated in the small clinic. So the public information and seminars related with ultrasonography increases the check-up frequency. The clinic requests some ultrasonographical examinations to the specialists in general hospital. (3) Parity: The clear difference shows that the CRM system causes the prenatal visit frequency to become higher in experimental group. The figure is 9.7 times and 8.6 times each. This is opposite that the past study said multiparity reduced the average prenatal visits. But the result of CRM is considered as the method to help the multiparity understand the importance of the prenatal care. (4) Obstetrical history: In the experimental group of the spontaneous delivery group, the figure is higher in the prenatal visit frequency, triple marker, oral GTT and targeted ultrasonography but the Caesarean section delivery group has higher figure in targeted ultrasonography. (5) In the first check-up, the rate of targeted ultrasonography in under 16 week pregnancy, in the 16 week pregnancy to 32 week pregnancy and the over 32 week pregnancy in the experimental group is upper than the compared one. For the oral GTT, there is a difference in under 16 week pregnancy but no difference in prenatal visits and triple marker. 2) The analysis of characteristics of prenatal care through the decision tree resulted in the fact that the most important variable is the residential area. After the delivery frequency is following, the obstetrical history and maternal age are in order. It is the same result in the triple marker and oral GTT. Consequently it is the same order of important variables in CRM system. The effectiveness of CRM system is proved in this study. The CRM system is a marketing method to control and lead the customers through the segmentation of customer data. It increases the new customer aquisition, maintenance of loyal customers, augmentation of customers value, activation of potential customers and creation of life time customers. So eventually it can enlarge the customers value. The medical institution should make efforts to establish the data base enforced by the customer's information on the underlying ordinary data system to carry out the CRM system effectively. In addition, it should develop the a variety of marketing strategy in order to set up one to one marketing satisfying the needs of individual patients.

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Awareness and Need as Factors in an Incremental Oral Health Care Program for Korean Adults (일부 성인의 계속구강관리프로그램 인식과 요구도)

  • Jang, Ho-Yeol;Lee, Su-Ryeon;Lee, Yun-Ji;Lee, Soo-Bin;Lee, Ha-Neul;Lee, Hye-Bin;Hwang, Soo-Jeong
    • Journal of dental hygiene science
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    • v.16 no.6
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    • pp.442-448
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    • 2016
  • Dental caries and periodontal disease are considered to be chronic, but can be prevented through an incremental oral health program covering all ages. The National Oral Health Program for adults provides oral health exam and scaling, and is covered by national health insurance for those over 20 years of age in Korea. The aim of this study was to collect basic data for developing an oral health program for adults by identifying factors related to awareness and need. The data were obtained by convenience sampling of 303 subjects. The use of dental plaque disclosing agents affected tooth brushing frequency, toothbrushing time and use of oral auxiliary devices. Education on toothbrushing methods affected toothbrushing time and use of oral auxiliary devices. Of those surveyed, 93.1% replied that an incremental oral health program for adults was needed, and 68.0% intended to participate. In a regression model, the factors that had an effect on the perceived need for an oral health program were education level, use of oral hygiene auxiliary devices, and toothbrushing time, and the factors affecting intent to participate were education for prevention of periodontal disease and the use of oral hygiene auxiliary devices. The subjects stated that the following oral health programs were needed: an oral bacteria exam (74.3%), toothbrushing education (71.6%), a bad breath exam (69.3%), education on use of oral hygiene auxiliary devices (46.9%), a dental plaque exam (42.9%) and a saliva exam (37.6%). Oral health education appears to be an important factor for participation in an incremental oral health program.

The Antioxidative Activity of Glutathione-Enriched Extract from Saccharomyces cerevisiae FF-8 in In Vitro Model System (In Vitro 과산화지질에 미치는 glutathione 고함유 효모 Saccharomyces cerevisiae FF-8의 항산화효과)

  • Lee Chi-Hyeoung;Cha Jae-Young;Jun Bang-Sil;Lee Ho-Jun;Lee Young-Chun;Cho Yong-Lark;Cho Young-Su
    • Journal of Life Science
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    • v.15 no.5 s.72
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    • pp.819-825
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    • 2005
  • The Antioxidative accvities of the cell free extracts containing high glutathione by Saccharomyces cerevisiae FF-8 were tested in vitro experimental models : DPPH method for radical scavenging activity, ferric TBA method and ferric thiocyanate method using linoleic acid and tissue microsome for lipid peroxidation inhibitions. The concentration of intercellular glutathione by cultivating S. cerevisiae FF-8 in the YM optimal medium obtained $204\mug/ml$, which was increased by 2.76-fold from $74\mug/ml$ in the YM basal medium. A comparition between the YM basal medium and the YM optimal medium on antioxidative substance produced by S. cerevisiae FF-8 was investigated. In DPPH ($\alpha, \alpha-diphenyl-\beta-picrylhydrazyl$) method, the electron donating activity of the glutathione produced by S. cerevisiae FF-8 cultured in the YM optimal medium was as high as that of BHT ($ 0.05\%w/v $). The antioxidative a.tivity was measured by inhibition against lipid peroxidation of rat tissues' microsomes. The results of anti-oxidant activity of the cell free extracts by S. rerevisiae FF-8 cultured in the YM optimal medium was shown in the following order . $ liver 60.98\% > kidney 56.43\% > heart 52.91\% > brain 52.13\% > testis 45.57\% > spleen 42.95\% $. In antioxidative activities determined by ferric thiocyanate method and TBA methods against lipid peroxidation, the lipid peroxidation in the control mixture increased more rapidly than the typical peroxidation curve of linoleic acid from one day. The antioxidative activity of the cell free extracts by cultivating S. cerevisine FF-8 in the YM optimal medium were higher than that of the YM basal medium. These data indicate that the cell free extracts containing a high intercellular glutathione of S. cerevisiae FF-8 cultured in YM optimal medium showed strong antioxidative capacities by DPPH radical scavenging activity and ferric thiocyanate and TBARS measurements.

The Relationship between Entrepreneurial Education and Entrepreneurial Intentions : Focusing on Moderating Effects of Entrepreneurial Orientation and Environmental Factors (창업교육과 창업의지의 관계: 기업가 지향성과 환경적 요인의 조절효과)

  • Lee, Jae-Seok;Lee, Sang-Myung
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.10 no.3
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    • pp.61-74
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    • 2015
  • This study attempts to empirically examine the influence of entrepreneurial education in university on entrepreneurial intentions of undergraduate and graduate students as potential entrepreneur and new moderating factors on the relationship between entrepreneurial education and entrepreneurial intentions. We suggested EO(innovativeness, risk-taking propensity, proactiveness and locus of control) and environmental factors(entrepreneurial family background and resource accessibility) as new moderating factors in the relationship. For this study, the following research questions are raised : First, is there a significant difference in entrepreneurial intentions of enrolled and unenrolled students in entrepreneurial education? Second, does entrepreneurial education affect entrepreneurial intentions positively? Finally, do EO and environmental factors have moderating effects in the relationship between entrepreneurial education and entrepreneurial intentions? In order to test our research model, the current study collected data from 265 undergraduate and graduate students who are majoring in natural sciences or engineering in Seoul National Univ., Hanyang Univ., and KAIST. To investigate our research questions and hypotheses, independent-sample T-test and hierarchical regression analysis were employed. The results of empirical analysis revealed that entrepreneurial education positively related to entrepreneurial intentions and that the relationship between entrepreneurial education and entrepreneurial intentions moderated by EO and environmental factors. First, the result showed the significant difference in entrepreneurial intentions between enrolled and unenrolled students in entrepreneurial education. Entrepreneurial intentions of students who enrolled entrepreneurial education was higher than others. Second, entrepreneurial education affected the entrepreneurial intentions positively. Finally, the moderating effects of innovativeness, risk-taking propensity, proactiveness and entrepreneurial family background among investigated six moderators were significant. entrepreneurial education-entrepreneurial intentions relationship was even stronger under high innovativeness and high proactiveness. But risk-taking propensity and entrepreneurial family background decreased the effect of entrepreneurial education on entrepreneurial intentions.

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Finding Influential Users in the SNS Using Interaction Concept : Focusing on the Blogosphere with Continuous Referencing Relationships (상호작용성에 의한 SNS 영향유저 선정에 관한 연구 : 연속적인 참조관계가 있는 블로고스피어를 중심으로)

  • Park, Hyunjung;Rho, Sangkyu
    • The Journal of Society for e-Business Studies
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    • v.17 no.4
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    • pp.69-93
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    • 2012
  • Various influence-related relationships in Social Network Services (SNS) among users, posts, and user-and-post, can be expressed using links. The current research evaluates the influence of specific users or posts by analyzing the link structure of relevant social network graphs to identify influential users. We applied the concept of mutual interactions proposed for ranking semantic web resources, rather than the voting notion of Page Rank or HITS, to blogosphere, one of the early SNS. Through many experiments with network models, where the performance and validity of each alternative approach can be analyzed, we showed the applicability and strengths of our approach. The weight tuning processes for the links of these network models enabled us to control the experiment errors form the link weight differences and compare the implementation easiness of alternatives. An additional example of how to enter the content scores of commercial or spam posts into the graph-based method is suggested on a small network model as well. This research, as a starting point of the study on identifying influential users in SNS, is distinctive from the previous researches in the following points. First, various influence-related properties that are deemed important but are disregarded, such as scraping, commenting, subscribing to RSS feeds, and trusting friends, can be considered simultaneously. Second, the framework reflects the general phenomenon where objects interacting with more influential objects increase their influence. Third, regarding the extent to which a bloggers causes other bloggers to act after him or her as the most important factor of influence, we treated sequential referencing relationships with a viewpoint from that of PageRank or HITS (Hypertext Induced Topic Selection).

STRAIN AND TEMPERATURE CHANGES DURING THE POLYMERIZATION OF AUTOPOLYMERIZING ACRYLIC RESINS

  • Ahn Hyung-Jun;Kim Chang-Whe;Kim Yung-Soo
    • The Journal of Korean Academy of Prosthodontics
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    • v.39 no.6
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    • pp.709-734
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    • 2001
  • The aims of this experiment were to investigate the strain and temperature changes simultaneously within autopolymerzing acrylic resin specimens. A computerized data acquisition system with an electrical resistance strain gauge and a thermocouple was used over time periods up to 180 minutes. The overall strain kinetics, the effects of stress relaxation and additional heat supply during the polymerization were evaluated. Stone mold replicas with an inner butt-joint rectangular cavity ($40.0{\times}25.0mm$, 5.0mm in depth) were duplicated from a brass master mold. A strain gauge (AE-11-S50N-120-EC, CAS Inc., Korea) and a thermocouple were installed within the cavity, which had been connected to a personal computer and a precision signal conditioning amplifier (DA1600 Dynamic Strain Amplifier, CAS Inc., Korea) so that real-time recordings of both polymerization-induced strain and temperature changes were performed. After each of fresh resin mixture was poured into the mold replica, data recording was done up to 180 minutes with three-second interval. Each of two poly(methyl methacrylate) products (Duralay, Vertex) and a vinyl ethyl methacrylate product (Snap) was examined repeatedly ten times. Additionally, removal procedures were done after 15, 30 and 60 minutes from the start of mixing to evaluate the effect of stress relaxation after deflasking. Six specimens for each of nine conditions were examined. After removal from the mold, the specimen continued bench-curing up to 180 minutes. Using a waterbath (Hanau Junior Curing Unit, Model No.76-0, Teledyne Hanau, New York, U.S.A.) with its temperature control maintained at $50^{\circ}C$, heat-soaking procedures with two different durations (15 and 45 minutes) were done to evaluate the effect of additional heat supply on the strain and temperature changes within the specimen during the polymerization. Five specimens for each of six conditions were examined. Within the parameters of this study the following results were drawn: 1. The mean shrinkage strains reached $-3095{\mu}{\epsilon},\;-1796{\mu}{\epsilon}$ and $-2959{\mu}{\epsilon}$ for Duralay, Snap and Vertex, respectively. The mean maximum temperature rise reached $56.7^{\circ}C,\;41.3^{\circ}C$ and $56.1^{\circ}C$ for Duralay, Snap, and Vertex, respectively. A vinyl ethyl methacrylate product (Snap) showed significantly less polymerization shrinkage strain (p<0.01) and significantly lower maximum temperature rise (p<0.01) than the other two poly(methyl methacrylate) products (Duralay, Vertex). 2. Mean maximum shrinkage rate for each resin was calculated to $-31.8{\mu}{\epsilon}/sec,\;-15.9{\mu}{\epsilon}/sec$ and $-31.8{\mu}{\epsilon}/sec$ for Duralay, Snap and Vertex, respectively. Snap showed significantly lower maximum shrinkage rate than Duralay and Vertex (p<0.01). 3. From the second experiment, some expansion was observed immediately after removal of specimen from the mold, and the amount of expansion increased as the removal time was delayed. For each removal time, Snap showed significantly less strain changes than the other two poly(methyl methacrylate) products (p<0.05). 4. During the external heat supply for the resins, higher maximum temperature rises were found. Meanwhile, the maximum shrinkage rates were not different from those of room temperature polymerizations. 5. From the third experiment, the external heat supply for the resins during polymerization could temporarily decrease or even reverse shrinkage strains of each material. But, shrinkage re-occurred in the linear nature after completion of heat supply. 6. Linear thermal expansion coefficients obtained from the end of heat supply continuing for an additional 5 minutes, showed that Snap exhibited significantly lower values than the other two poly(methyl methacrylate) products (p<0.01). Moreover, little difference was found between the mean linear thermal expansion coefficients obtained from two different heating durations (p>0.05).

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