• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.73-79
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• 2011

Purpose: The aim of this study was to evaluate the effect of repeated firings on the color of zirconia restoration with different shading method. Materials and methods: Three different types of zirconia frameworks (adding metallic pigments to the initial zirconia powder before sintering (Group NM), dipping the milled frameworks in dissolved coloring agents (Group KI), or application of liner material to the sintered white frameworks (Group KW) were used to support A3 shade dentin porcelain. Repeated firings (3, 5, or 7) were performed, color differences among ceramic specimens were measured using a colorimeter. Repeated measurements analysis of variance (ANOVA) was used to analyze the data for significant difference. The Tukey Honestly Significant Different (HSD) test was used to perform multiple comparisons (${\alpha}$ = .05). Results: 1. $L^*a^*b^*$ values of the ceramic systems were affected by the number of firings (1, 3, 5 or 7 firings) (P < .001) and shading methods (P < .001). 2. As the number of firings increased, the $L^*$ (for all groups) and $a^*$ value (for KW and NM groups) decreased and the $b^*$ value(for all groups) increased. 3. The mean color differences caused by repeated firings were perceptible (${\Delta}E$ > 1) for group KW and KI fired after 3 times, except for group NM fired after 7 times. 4. In order of decreasing ${\Delta}E$ value fired after 7 times, the values were group KI(${\Delta}E$ = 2.26) > group KW (${\Delta}E$ = 1.47) > group NM (${\Delta}E$ = 1.08) (P < .001). Conclusion: Repeated firings influenced the color of the zirconium-oxide all-ceramic specimens with different shading methods.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.16-24
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• 2001

The purpose of this study was to evaluate the specificity, sensitivity, and diagnostic power of caries activity test using laser fluorescence. The subjects of this study were 50 children of $7\sim9$ years old. Fluorescence from initial carious lesion of teeth illuminated by an argon laser(480nm) was observed and photographed with barrier filter. Visual examination for the dDfFtT rate and Streptococcus mutans colony counting was done to evaluate correlation with caries activity test using laser fluorescence. Data analysis was accomplished by Axelsson's method. The results from the present study can be summarized as follows: 1. There was positive correlation $(\gamma=0.48)$ between laser fluorescence test and Streptococcus mutans count. And also positive correlation $(\gamma=0.39)$ exists between laser fluorescence test and dDfFtT rate (P<0.01). 2. Positive correlation $(\gamma=0.27)$ between Streptococcus mutans colony count and dDfFtT rate was found(P<0.05). 3. When dDfFtT rate was defined to standard testing method, the specificity, senstivity, and diagnostic power of laser fluorescence test were 44.4%, 85.7%, and 87.8%. 4. When dDfFtT rate was defined to standard testing method, the specificity, senstivity, and diagnostic power of S. mutans colony counting were 77.8%, 92.9%, 84.8%. 5. When S. mutans colony counting was defined to standard testing method, sensitivity, specificity and diagnostic power of laser fluorescence test were 40.0%, 84.8%, 95.1%. In regard to above results, laser fluorescence test considered to be accurate and reliable method for determining caries activity because of it's close relationship with caries susceptibility test and caries experience measurements. And it was also considered to be practical because it would be simple, inexpensive, and time saving method.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.102-109
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• 2003

The purpose of this study was to evaluate the linear polymerization shrinkage(%) and microhardness of composite resin(Z-100, 3M, USA) according to 2-step light curing method. Conventional light curing unit(Curing Light 2500, 3M USA) and 2-step light curing unit(Elipar Highlight, ESPE, Germany) were used as light source. The strain gauge method was used for determination of polymerization shrinkage(%). Samples were divided by 3 groups according to light curing methods (Group I : $450mW/cm^2$, 40sec, Group II : $650mW/cm^2$, 40sec, Group III : $150mW/cm^2$, 10sec & $650mW/cm^2$, 30sec). Preparations of acrylic molds were followed by filling and curing. Strain gauges attached to each sample were connected to a strainmeter. Measurements were recorded at each second for the total of 10 minutes including the periods of light application. And microhardness of each group after 24hours from light irradiation were measured. Obtained data were analyzed statistically using Ore-way ANOVA and/or Scheffe test. The results of the present study can be summarized as follows: 1. Composite resin in acrylic molds showed the initial expansion at the early phase of polymerization. This was followed by the contraction with the rapid increase in volume during the first 60 seconds and gradually diminished as curing process continued. 2. The lowest linear polymerization shrinkage(%) was found in group III followed by group I, II during the measuring periods. 3. Group III using 2-step curing method showed statistically significant reduction of linear polymerization shrinkage(%) compared with group I, II at 1 minute and 10 minutes from light irradiation(p<0.05). 4. The microhardness values of each group not revealed significant difference.

• Tuberculosis and Respiratory Diseases
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• v.48 no.5
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• pp.748-756
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• 2000

Background : Bronchogenic carcinoma is generally considered as a disease that predominantly affects middleaged and elderly men. A small percentage of patients with lung cancer are diagnosed in the third or fourth decade of life or earlier. The current study was performed to review the clinical characteristics of bronchogenic carcinoma in patients younger than 40 years of age at Chungnam National University Hospital. Method : To determine the clinicopathologic characteristics including survival rates of lung cancer patients younger than 40 years of age and to compare them with those of patients 이der than 40 years of age at diagnosis, data of 905 patients diagnosed as lung cancer from January. 1990 to Marm 1997 were analyzed. Result : Twenty-three of 905 patients(2.5%) belonged to the young age group (less than 40 years). Male to female ratios of young age group and control group were 2.8 : 1 and 5.3 : 1, respectively. The mean duration of symptoms from onset to the definite diagnosis was 3.2 months in the young age group. The most common initial symptoms in the young age group were cough(52.2%) and dyspnea(43.5%). Adenocarcinoma (43.5%) was more frequent in the young age group than in the control group(20.1%). Stage III and IV(70%) tumors were more frequent in the young age group than in the control group(52.3%). Distant metastasis rate of the young age group(56.5%) was higher than that of the control group(22.3%). Conclusion : The predominance of adenocarcinoma, the lower male-female ratio, and the high incidence of advanced stage tumor at diagnosis are the characteristics of lung cancer in patients younger than 40 years of age.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.1
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• pp.59-70
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• 2020

This study was proceeded to empirically identify the start-up support policy as an element that affects the performance of the early start-ups and measure the effectiveness of the current start-up support policy, in order to suggest the direction future policies according to the study. To accomplish this the influence of the start-up support policy on the early start-ups was analyzed, and the differences according to the industry and growth stage of the start-ups, as the characteristics of the start-ups, were identified. The research subjects collected real data of 297 start-ups of the past three years that were selected for the Initial Start-Up Package project, and performed multiple regression analysis on the influence between variables, and hierarchical regression analysis on moderating effects. The summary of the study is as follows. First, as a result of identifying the influential relationship between the start-up support policy and the performance of the start-up, sales had made a significant impact on the start-up fund, start-up mentoring, and start-up infrastructure(space), while start-up education failed to show a significant effect on the increase in sales. In terms of employment, start-up mentoring was the only field that showed a significant influential relationship. Second, as a result of identifying the moderating effect of the start-up's industry and growth stage, the industry did not have a statistically significant influence, but the interactive effect was seen in start-up education. To be more specific in terms of the sales relationship of each industry, knowledge services turned out to be helpful in improving sales, while manufacturing turned out to be effective in improving sales regardless of being supported with start-up mentoring and start-up infrastructure (space). The sales relationship regarding the start-up growth stage was identified to be statistically significant. The preliminary stage was not statistically significant, while providing start-up mentoring and start-up funding were effective for start-up stage and growing stage, respectively. On the other hand, employment did not perform a significant influence on the start-up growth stage. This study analyzes the effectiveness the start-up support policy for early start-ups, identifies the need in differentiated support policies according to the characteristics of the start-ups, and suggests implications for the direction in which future policies should be made towards.

• Progress in Medical Physics
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• v.26 no.4
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• pp.201-207
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• 2015

The new function of 3DVH software for dose calculation inside the patient undergoing TomoTherapy treatment by applying the measured data obtained by ArcCHECK was recently released. In this study, the dosimetric accuracy of 3DVH for the TomoTherapy DQA process was evaluated by the comparison of measured dose distribution with the dose calculated using 3DVH. The 2D diode detector array MapCHECK phantom was used for the TomoTherapy planning of virtual patient and for the measurement of the compared dose. The average pass rate of gamma evaluation between the measured dose in the MapCHECK phantom and the recalculated dose in 3DVH was $92.6{\pm}3.5%$, and the error was greater than the average pass rate, $99.0{\pm}1.2%$, in the gamma evaluation results with the dose calculated in TomoTherapy planning system. The error was also greater than that in the gamma evaluation results in the RapidArc analysis, which showed the average pass rate of $99.3{\pm}0.9%$. The evaluated accuracy of 3DVH software for TomoTherapy DQA process in this study seemed to have some uncertainty for the clinical use. It is recommended to perform a proper analysis before using the 3DVH software for dose recalculation of the patient in the TomoTherapy DQA process considering the initial application stage in clinical use.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.12
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• pp.1681-1690
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• 2000

A study on energy and protein utilization, and milk production of Bali cows on grass-legume diets was carried out using 12 first lactation cows (initial BW $263.79{\pm}21.66kg$) during a period of 16 weeks starting immediately post calving. The animals were randomly allotted into 4 dietary treatment groups R1, R2, R3 and R4, receiving from the last 2 months of pregnancy onwards, graded improved rations based on a mixture of locally available grass and legume feed ad libitum. R1 contained on a DM basis 70% elephant grass (PP, Penisetum purpureum) plus 30% Gliricidia sepia leaves (GS), R2 was 30% PP plus 55% GS supplemented with 15% Hibiscus tilliactus leaves (HT, defaunating effect), R3 and R4 were 22.5% PP+41.25% GS+11.25% HT+25% concentrate, where R3 was not and R4 supplemented with zinc di-acetate. TDN, CP and zinc contents of the diets were 58.2%, 12.05% and 18.3 mg/kg respectively for R1, 65.05%, 16.9% and 25.6 mg/kg respectively for R2, 66.03%, 16.71% and 29.02 mg/kg respectively for R3 and 66.03%, 16.71% and 60.47 mg/kg respectively for R4. Milk production and body weight were monitored throughout the experimental period. In vivo body composition by the urea space technique validated by the body density method and supported by carcass data was estimated at the start and termination of the experiment. Nutrient balance and rumen performance characteristics were measured during a balance trial of 7 days during the 3rd and 4th week of the lactation period. Results indicated that quality of ration caused improvement of ruminal total VFA concentration, increments being 52 to 65% for R2, R3 and R4 above R1, with increments of acetate being less (31 to 48%) and propionate being proportionally more in comparison to total VFA increments. Similarly, ammonia concentrations increased to 5.24 to 7.07 mM, equivalent to 7.34 to 9.90 mg $NH_3-N/100ml$ rumen fluid. Results also indicated that feed quality did not affect DE and ME intakes, and heat production (HP), but increased GE, UE, energy in milk and total retained energy (RE total) in body tissues and milk. Intake-, digestible- and catabolized-protein, and retained-protein in body tissues and milk (Rprot) were all elevated increasing the quality of ration. Similar results were obtained for milk yield and components with mean values reaching 2.085 kg/d (R4) versus 0.92 kg/d (R1) for milk yield, and 170.22 g/d (R4) vs 71.69 g/d (R1), 105.74 g/d (R4) vs 45.35 g/d (R1), 101.34 g/d (R4) vs 46.36 g/d (R1) for milk-fat, -protein, and -lactose, respectively. Relatively high yields of milk production was maintained longer for R4 as compared to the other treatment groups. There were no significant effects on body mass and components due to lactation. From the relationship $RE_{total}$ (MJ/d)=12.79-0.373 ME (MJ/d); (r=0.73), it was found that $ME_{m}=0.53MJ/kgW^{0.75}.d$. Requirement of energy to support the production of milk, ranging from 0.5 to 3.0 kg/d, follows the equation: Milk Prod. ($Q_{mp}$, kg/d)=[-2.48+4.31 ME($MJ/kg^{0.75}.d$)]; (r=0.6) or $Q_{mp}$=-3.4+[0.08($ME-RE_{body\;tissue}$)]MJ/d]; (r=0.94). The requirement for protein intake for maintenance ($IP_m$) equals $6.19 g/kg^{0.75}.d$ derived from the relationship RP=-47.4+0.12 IP; (r=0.74, n=9). Equation for protein requirement for lactation is $Q_{nl}$=[($Q_{mp}$)(% protein in milk)($I_{mp}$)]/100, where $Q_{nl}$ is g protein required for lactation, $Q_{mp}$ is daily milk yield, Bali cow's milk-protein content av. 5.04%, and $I_{mp}$ is metabolic increment for milk production ($ME_{lakt}/ME_{m}=1.46$).

• The Journal of Society for e-Business Studies
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• v.25 no.1
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• pp.135-176
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• 2020

This study is to investigate the factors affecting the usage intentions of 5G service between 5G service subscribers and non-subscribers based on the Integratively Extended Technology Acceptance Model in the initial B2C 5G service market. We designed the integratively extended technology acceptance model to find the more specific factors to affect the usage intentions by integrating the exogenous factors including the technical factors, the social factors, and the personal factors with the ETAM(Extended Technology Acceptance Model). Referring to the previous studies, we constructed the hypotheses of structural influence relationship from the exogenous factors to the dependent usage intentions factors through the mediating belief factors. We designed the 5G service usage intentions model based on these hypotheses and operational definitions of the factors. Using the analysis of SEM(Structural Equation Model), the proposed model and the hypotheses were empirically tested by the data collected from 245 subscribed respondents and 245 non-subscribed respondents. As a result, the perceived ease of use has an effect on the perceived usefulness and enjoyment, and the perceived usefulness/enjoyment and the personal innovativeness have positive effects on the usage intentions of both groups.

• Journal of agricultural medicine and community health
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• v.4 no.1
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• pp.41-61
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• 1979

Two interview surveys (1976 for 800 patients, 1978 for 200 patients) and an inventory survey through medical records(1978) for epileptic patients who have registered with the Korean Epilepsy Association (Rose Club) since 1971 were carried out by trained health workers in advance of survey. The data obtained from the analysis showed as follows: 1) 35.2% of patients were born in Seoul and 70. 6% of patients born elsewhere have lived in Seoul. 2) 50-60% of patients were 15-30 years cid. 3) 33.4%, 24,6 and 24.6 of all pupils and students went to elementary, junior and senior high schools respectively. 4) 21.2% of all pupils and students had dropped out of school and 51.4% of them were away from school because of epilepsy. 5) 3.1% of all patients had no job at all and students comprised 20.9% of patients followed by clerical work, commercial business and farming with about 6% in each group.6) Reasons given for unemployment such as dismissal (4.3%), quit (27.7%), hesitation to employ (42.5%)and discontinuance of job (25.5%) were basically due to epilepsy. 7) About half(46.2%) of all patients have become Christian since the Rose Club was a voluntary agency which has been sponsored by Christians. 8) 82. 6% of patients were diagnosed as having grand mal as the most. 9) 29.4% of patients explained aura with psychomotor disturbances and 13.8% with sensory disorders. 10) 46.3% of patients were attacked with seizures when they were tired and others(11.6% and 4.9%) after excessive eating and hunger. 11) Patients suffered more seizures in spring and summer rather than in autumn and winter and most patients had attacks 1-5 times a month. 12) For etiologic reasons of epilepsy, 35.5% of patients considered it was caused by psychological stress and 11.5% by trauma. Only 1.1% of patients considered it as having hereditary components. 13) 51% of patients were slow in caring for their own illnesses. They started to reat epilepsy after spending 5 years of time from the initial seizure. Only 5.4% of patients had received the modern anti-epileptic therapy right after the nitial seizure. 14) 62.1% of patients had no therapy or irregular or incomplete treatment before registration at the Rose Club Clinic. 15) Before registration at the Rose Club, 42.4% of patients received medical care. On the other hand, 25.6% went to herb doctors and 12.5% used to go to the drugstore in order to get anti-epileptic drugs. 16) 41. 6% of patients who took anti-epileptic drugs had more or less side-effects. Indigestion was the most common. 17) For continuation of treatment, 30.3% have received treatment for more than 5 years and the evident showed that epilepsy took a longer time to be cured. 18) Regarding the medical care received 44.2% of patients were very satisfied with effective care and 26.5% felt as good. 19) For attitudes toward epilepsy. 27.0% of patients and 68.2% of patients family were pessimistic. 20) 65.9% of patients had optimistic attitudes toward effectiveness of medical care of epilepsy. 21) 64.8% of wives and husbands had better understanding and cooperative for their spouses who had epilepsy. 22) 33.3% of patients were under-treated at the place of work. 23) 70.2% of patients wished to marry when they reach childbearing age and 63% wished to have children. Through the above results it is recommended for nation-wide epilepsy control that the sound and correct health education not only from health aspect but also from welfare aspect should be planned and implemented as soon as possible.

• Management & Information Systems Review
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• v.23
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• pp.41-74
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• 2007

In Korea, corporate merger activities were activated since 1980, and nowadays(particuarly since 1986) the changes in domestic and international economic circumstances have made corporate managers have strong interests in merger. Korea and America have different business environments and it is easily conceivable that there exists many differences in motives, methods, and effects of mergers between the two countries. According to recent studies on takeover bids in America, takeover bids have information effects, tax implications, and co-insurance effects, and the form of payment(cash versus securities), the relative size of target and bidder, the leverage effect, Tobin's q, number of bidders(single versus multiple bidder), the time period (before 1968, 1968-1980, 1981 and later), and the target firm reaction (hostile versus friendly) are important determinants of the magnitude of takeover gains and their distribution between targets and bidders at the announcement of takeover bids. This study examines the theory of takeover bids, the status quo and problems of merger in Korea, and then investigates how the announcement of merger are reflected in common stock returns of bidding firms, finally explores empirically the factors influencing abnormal returns of bidding firms' stock price. The hypotheses of this study are as follows ; Shareholders of bidding firms benefit from mergers. And common stock returns of bidding firms at the announcement of takeover bids, shows significant differences according to the condition of the ratio of target size relative to bidding firm, whether the target being a member of the conglomerate to which bidding firm belongs, whether the target being a listed company, the time period(before 1986, 1986, and later), the number of bidding firm's stock in exchange for a stock of the target, whether the merger being a horizontal and vertical merger or a conglomerate merger, and the ratios of debt to equity capital of target and bidding firm. The data analyzed in this study were drawn from public announcements of proposals to acquire a target firm by means of merger. The sample contains all bidding firms which were listed in the stock market and also engaged in successful mergers in the period 1980 through 1992 for which there are daily stock returns. A merger bid was considered successful if it resulted in a completed merger and the target firm disappeared as a separate entity. The final sample contains 113 acquiring firms. The research hypotheses examined in this study are tested by applying an event-type methodology similar to that described in Dodd and Warner. The ordinary-least-squares coefficients of the market-model regression were estimated over the period t=-135 to t=-16 relative to the date of the proposal's initial announcement, t=0. Daily abnormal common stock returns were calculated for each firm i over the interval t=-15 to t=+15. A daily average abnormal return(AR) for each day t was computed. Average cumulative abnormal returns($CART_{T_1,T_2}$) were also derived by summing the $AR_t's$ over various intervals. The expected values of $AR_t$ and $CART_{T_1,T_2}$ are zero in the absence of abnormal performance. The test statistics of $AR_t$ and $CAR_{T_1,T_2}$ are based on the average standardized abnormal return($ASAR_t$) and the average standardized cumulative abnormal return ($ASCAR_{T_1,T_2}$), respectively. Assuming that the individual abnormal returns are normal and independent across t and across securities, the statistics $Z_t$ and $Z_{T_1,T_2}$ which follow a unit-normal distribution(Dodd and Warner), are used to test the hypotheses that the average standardized abnormal returns and the average cumulative standardized abnormal returns equal zero.