• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.365-373
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• 2016

Composites are the most useful restorative material. However, composites have some disadvantages such as polymerization shrinkage, long working time, and susceptibility to water and contamination, which are stood out more especially when treating children. To solve these problems, bulk-fill composites have been developed. The aim of this study is to compare mechanical properties of bulk-fill and conventional composites. Bulk-fill composites (SureFil SDR flow (SDR), Tetric N-Ceram bulk fill (TBF)) and conventional composites (Filtek Z-350 (Z-350), Unifil Flow (UF), Unifil Loflo Plus (UL)) were used. The Vickers hardness tester was used to measure the microhardness of materials, and Fourier transform infrared spectroscopy was used to measure the degree of conversion. Polymerization shrinkage was measured by using a linometer. Flexural and compressive properties were measured by using the universal testing machine. Data were statistically analyzed by ANOVA and Scheffe's post hoc test. The level of significance was set to p < 0.05. Most conventional composites showed higher microhardness than bulk-fill composites. However, bulk-fill composites showed a higher top/bottom microhardness ratio than conventional composites. Bulk-fill composites showed a higher top/bottom degree of conversion ratio than conventional composites. The polymerization shrinkage was highest in UL and lowest in Z-350. The polymerization shrinkage of flowable composites was higher than that of non flowable composites. The compressive properties were highest in Z-350 and lowest in SDR and UL. In terms of flexural properties, Z-350 was the highest. However, none of the bulk-fill composites exhibited mechanical properties as good as those of conventional composites. Nonetheless, the ratio of microhardness and degree of conversion, which are important properties of bulk filling, were higher in bulk-fill composites. Therefore, the bulk-fill composites might be considered suitable restorative materials in pediatric dentistry.

• Journal of Global Scholars of Marketing Science
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• v.19 no.1
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• pp.9-21
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• 2009

Recently, the researches to explain Switching Behavior through Theory of Planned Behavior have been discovered. Many researches say that System factors of mobile telecommunication service(MTS) is positively associated with Switching Intention. But There is no difference of system factors between mobile telecommunication services because of IT technique Development. Thus, this study investigated whether switching cost and alternative's attractiveness influence switching intention concerning mobile telecommunication service by adopting Theory of Planned Behavior (TPB) as an underlying theoretical premise. The study also attempted to determine the moderating effects of personal innovativeness on switching intention. For these purposes the author has developed several hypotheses as follows: H-1. The switching cost of different MTS is associated with the attitude of MTS which is using. H-2. The switching cost of different MTS is associated with the subjective norm of MTS which is using. H-3. The switching cost of different MTS is associated with the perceived behavior control of MTS which is using. H-4. The alternative's attractiveness of different MTS is associated with the attitude of MTS which is using. H-5. The alternative's attractiveness of different MTS is associated with the subjective norm of MTS which is using. H-6. The alternative's attractiveness of different MTS is associated with the perceived behavior control of MTS which is using. H-7. The switching cost of different MTS is associated with the switching intention. H-8. The alternative's attractiveness of different MTS is associated with the switching intention. H-9. The attitude of MTS is associated with the switching intention. H-10. The subjective norm of MTS is associated with the switching intention. H-11. The perceived behavior control of MTS is associated with the switching intention. H-12. The personal innovativeness has been a moderating effects to switching intention. Data has been collected from 403 respondents for this study using a questionnaire method. The survey for the actual analysis of the research was done and analyzed with the customers who have an experience of using Mobile telecommunication service and the samples were selected among the middle and high school students who live in Seoul area, the university students who live in Seoul, Gyeonggi and Chungcheng Provinces, and the ordinary workers who are working in Seoul and Gyeonggi Province. The survey was done for 23 days from March 28, 2008 through April 12, 2008. The positive analysis was done with SPSS 12.0K statistics package and visual PLS program using the analysis techniques of frequency analysis, reliability analysis, correlation analysis and factor analysis. In addition, structural equation modeling was conducted using AMOS 5.0. The data was analyzed by frequency analysis using SPSS 12.0 and structural equation modeling using AMOS 5.0. The result of the overall model analysis is as follows: Chi-Square=378.306, d.f.=107, p-value=0.0, GFI=.904, AGFI= 0.863, IFI= 0.939, NFI= 0.917, RMSEA= 0.079, TLI= 0.922. The results of the overall model analysis were coherent. The following study results were revealed: First, switching cost was related positively to attitude, subjective norm and perceived behavior control, three components of TPB. Second, alternative's attractiveness was related negatively to subjective norm but positively to perceived behavior control. Third, switching cost and attitude was related negatively to switching intention, while perceived behavior control was related positively to switching intention. Finally, the study found the moderating effects of personal innovativeness on switching intention. Based on the results, the study offers marketing strategic implications for mobile telecommunication service industry.

• The Korean Journal of Nuclear Medicine
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• v.34 no.1
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• pp.30-38
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• 2000

Purpose: We investigated the role of myocardial perfusion SPECT in prediction of ventricular dilatation and the role of revascularization including thrombolytic therapy and PTCA in prevention of ventricular dilatation after an acute myocardial infarction (AMI). Materials and Methods: We performed dipyridamole stress, 4 hour redistribution, and 24 hour reinjection Tl-201 SPECT in 16 patients with AMI two to nine days after attack. Perfusion and wall motion abnormalities were quantified by perfusion index (PI) and wall motion index (WMI). Left ventricular ejection fraction (LVEF), WMI and ventricular volume were measured within 1 week of AMI and after average of 6 months. According to serial changes of left ventricular end-diastolic volume (LVEDV), patients were divided into two groups. We compared WMI, PI and LVEF between the two groups. Relationships among degree of volume, stress-rest PI, WMI, CKMB, Q wave, LVEF and revascularization were analysed using multivariate analysis. Results: Only initial rest perfusion index was significantly different between the two groups (p<0.05). While initial LVEF, stress PI, CKMB, trial of revascularization procedure, presence of Q wave and WMI were not significantly different between the two groups. Eight of 16 patients (50%) showed LV dilatation on follow-up echocardiography. Three of 3 patients (100%) who did not undergo revascualrization procedure documented LV dilatation. And only 5 (38%) of the remaining 13 patients who underwent revascularization revealed LV dilatation. There was no difference in infarct location between the two groups. By multivariate linear regression analysis in patients only undergoing revascularization, rest perfusion index was the only significant factor. Conclusion: Myocardial perfusion SPECT performed prior to revascularization was useful in prediction of LV dilatation after an AMI. Rest perfusion index on myocardial perfusion plays as a significant predictor of left ventricular dilatation after AMI. And revascularization appears to be a valuable procedure in alleviating LV dilatation after AMI with or without viable myocardium in a limited number of patients studied retrospectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.477-482
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• 2006

Viral diseases, especially Barley yellow mosaic virus (BaYMV) and Barley mud mosaic virus (BaMMV), have been most serious in barley fields. In this study, we investigated the effect of different level of resistance to viral diseases on the plant growth and yield in barley. Various viral disease symptoms on leaves of overwintered plants were similar between medial-resistant and susceptible varieties of Saessalbori and Baegdong. In diagnosis of virus infection, BaYMV and BaMMV were detected in Saessalbori and Baegdong, but not in the resistant variety, Naehanssalbori. Plant height was restrained about $11{\sim}12cm$ prior to heading in Saessalbori and Baegdong comparing to Naehanssalbori. Even if both varieties were medial resistant to virus diseases, Saessalbori was different from Baegdong in heading date and culm length due to its recovery from viral damages prior to heading. Both medial-resistant and susceptible varieties were quite different from the resistant variety in yield components such as heading date, number of spikes and culm length when evaluated in the virus-infected or non-infected field. Baegdong delayed 7 days in heading date and reduced by more than 50% in culm length and spike numbers as compared to Naehanssalbori. On the other hand, Saessalbori showed similar heading date, but was shorter by 20% in culm length than Naehanssalbori. Three varieties tested in the non-infected field over two years were not significantly different for yield potential with ranges of $340{\sim}405kg/10a$. However, significant yield reduction (P<0.01) was observed in Saessalbori and Baegdong with ranges of $108{\sim}288kg/10a$ as compared to Naehanssalbori (391 kg/10a) when tested in the virus-infected field. Yield potentials of Saessalbori and Baegdong reduced by 35 and 63%, respectively in the virus-infected field as compared to those in the non-infected field. Our results showed that damages from virus diseases were significant on the early plant growth to yield and its components in barley.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.3
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• pp.121-133
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• 1975

Soils of the agricultural land derived mostly from volcanic ash in Jeju island may be characterized by relatively high PH, high contents of organic matter and exchangeable bases, and significantly low content of available phosphorus. The PH, organic matter, and available phosphorus of the soils in northern Jeju are 6.1, 12.6%, and 23 ppm, while those of the soils in the southern Jeju are 6.4, 3.7 %, and 76 ppm respectively. Upland soils in Jeju may be classified into 4 groups on the basis of soil fertility: black soil, very dark brown soil, dark brown, and red yellow soil. The organic matter content of black soil, very dark soil and dark brown soil is 15%, 7%, and 3% respectively. The soils of high organic matter content show the high phosphorus absorption coefficient, low content of available phosphorus, and low degree of the base saturation. The soil productivity for barley in the northern Jeju is higher than that in the southern Jeju and the productivity in the western Jeju is higher than that in the eastern part. The productivity for barley is in decreasing order of dark brown soil, very dark brown soil and black soil. Yields of potato and sweet potato in Jeju are higher than in the mainland. Those crops are considered to be tolerant to aluminumtoxicity. The response of sweet potato to nitrogen, phosphorus, and potassium in Jeju soils is lower than that in the mainland, while the response of barley and rape to nitrogen and phosphorus is higher than that in the mainland. The response to fertilizer applied is greater in the northern Jeju than in the southern Jeju. Lime requirement for the Jeju soils calculated on the basis of laboratory tests is so tremendous that single application of lime required might induce adverse effect. Most of the phosphorus applied to the Jeju soils is readily fixed as unavailable form and application of phosphorus in the level of 30 to 40 kg/10a is thought to give little effect.

• Journal of Preventive Medicine and Public Health
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• v.36 no.3
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• pp.255-262
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• 2003

Objectives : We carried out tests for neurobehavior by using WHO-NCTB (neurobehavioral core test battery) and Perdue pegboard score test to identify differences between lacunar infarction cases and controls. Methods : Among the subjects who underwent MRI between February 2001 and March 2002 in a university hospital located in Seoul and who were diagnosed only as lacunar infarction without any intracranial disease, 46 patients were selected as cases (male: 21, female: 25). Controls were selected who had no cerebrovascular disease on MRI by matching age (5 years), gender, and education (2 years) in a ratio of 1:1 , Among WHO-NCTB, the following 5 tests and Perdue pegboard score test were used to categorize the study subjects: digit and symbol matching, simple reaction time, Benton visual retention, digit span, and Pursuit aiming test, Results : Among the above 6 tests of neurobehavior, lacunar infarction cases showed lower score than controls except for the simple reaction time test. As the controlling variables of multivariate analysis in the stepwise regression analysis, the followings were selected due to their significant association: age, education, BMI, gender, drinking, exercise, add systolic blood pressure. From multivariate regression analysis, there was significant difference (p<0.05) between lacunar infarction cases and controls in digit and symbol matching, Benton visual retention, digit span, pursuit aiming, and Perdue pegboard score test, but not in the score of simple reaction time test. Conclusions : We suggest that the above 5 tests for neurobehavior, with the exception of the simple reaction time test, might be used as the basis for recommendation of further treatment and other neurological tests by the earlier defection for neurological abnormality in lacunar infarction.

• Clinical and Experimental Pediatrics
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• v.49 no.5
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• pp.558-564
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• 2006

Purpose : Transcranial electromagnetic stimulation(TMS) is a noninvasive method which stimulates the central nervous system through pulsed magnetic fields without direct effect on the neurons. Although the neurobiologic mechanisms of magnetic stimulation are unknown, the effects on the brain are variable according to the diverse stimulation protocols. This study aims to observe the effect of the magnetic stimulation with two different stimulation methods on the cultured hippocampal slices. Methods : We obtained brains from 8-days-old Spague-Dawley rats and dissected the hippocampal tissue under the microscope. Then we chopped the tissue into 450 µm thickness slices and cultured the hippocampal tissue by Stoppini's method. We divided the inserts, which contained five healthy cultured hippocampal slices respectively, into magnetic stimulation groups and a control group. To compare the different effects according to the frequency of magnetic stimulation, stimulation was done every three days from five days in vitro at 0.67 Hz in the low stimulation group and at 50 Hz in the high stimulation group. After N-methyl-D-aspartate exposure to the hippocampal slices at 14 days in vitro, magnetic stimulation was done every three days in one and was not done in another group. To evaluate the neuronal activity after magnetic stimulation, the $NeuN/{\beta}$-actin ratio was calculated after western blotting in each group. Results : The expression of NeuN in the magnetic stimulation group was stronger than that of the control group, especially in the high frequency stimulation group. After N-methyl-D-aspartate exposure to hippocampal slices, the expression of NeuN in the magnetic stimulation group was similar to that of the control group, whereas the expression in the magnetic non-stimulation group was lower than that of the control group. Conclusion : We suggest that magnetic stimulation increases the neuronal activity in cultured hippocamal slices, in proportion to the stimulating frequency, and has a neuroprotective effect on neuronal damage.

• Clinical and Experimental Pediatrics
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• v.56 no.10
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• pp.439-445
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• 2013

Purpose: Previous studies suggest that the concentration of 25-hydroxyvitamin D [25(OH)D] in cord blood may show an inverse association with respiratory tract infections (RTI) during childhood. The aim of the present study was to examine the influence of 25(OH)D concentrations in cord blood on infant RTI in a Korean birth cohort. Methods: The levels of 25(OH)D in cord blood obtained from 525 Korean newborns in the prospective COhort for Childhood Origin of Asthma and allergic diseases were examined. The primary outcome variable of interest was the prevalence of RTI at 6-month follow-up, as diagnosed by pediatricians and pediatric allergy and pulmonology specialists. RTI included acute nasopharyngitis, rhinosinusitis, otitis media, croup, tracheobronchitis, bronchiolitis, and pneumonia. Results: The median concentration of 25(OH)D in cord blood was 32.0 nmol/L (interquartile range, 21.4 to 53.2). One hundred and eighty neonates (34.3%) showed 25(OH)D concentrations less than 25.0 nmol/L, 292 (55.6%) showed 25(OH)D concentrations of 25.0-74.9 nmol/L, and 53 (10.1%) showed concentrations of ${\geq}75.0$ nmol/L. Adjusting for the season of birth, multivitamin intake during pregnancy, and exposure to passive smoking during pregnancy, 25(OH)D concentrations showed an inverse association with the risk of acquiring acute nasopharyngitis by 6 months of age (P for trend=0.0004). Conclusion: The results show that 89.9% of healthy newborns in Korea are born with vitamin D insufficiency or deficiency (55.6% and 34.3%, respectively). Cord blood vitamin D insufficiency or deficiency in healthy neonates is associated with an increased risk of acute nasopharyngitis by 6 months of age. More time spent outdoors and more intensified vitamin D supplementation for pregnant women may be needed to prevent the onset of acute nasopharyngitis in infants.

• Korean Journal of Poultry Science
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• v.36 no.3
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• pp.231-238
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• 2009

The present study was conducted to investigate the antimicrobial activities of extracts from approximately 40 different traditional Korean medicinal herbs against S. gallinarum and S. epidermidis. The extracts from Schizandra chinensis Baill., Melia azedarach Linn$\acute{e}$, Caesalpinia sappan Linn$\acute{e}$. and Rhus javanica Linn$\acute{e}$. exhibited high antimicrobial activities against S. gallinarum, whereas the extracts from Melia azedarach Linn$\acute{e}$ and Rhus javanica Linn$\acute{e}$. exhibited high antimicrobial growth for S. epidermidis. Minimum inhibitory concentrations (MIC) of Melia azedarach Linn$\acute{e}$, Caesalpinia sappan Linn$\acute{e}$. and Rhus javanica Linn$\acute{e}$. for S. gallinarum were 1.2 mg/mL, whereas MIC of exracts from Rhus javanica Linn$\acute{e}$. extract for S. epidermidis were 0.6 mg/mL. Heat treatment of the extracts from Schizandra chinensis Baill. and Rhus javanica Linn$\acute{e}$. caused a significant reduction in antimicrobial activities against S. gallinarum. but didn't affect antimicrobial activities against S. edidermidis. Alkaline treatment of the extracts from Schizandra chinensis Baill. caused a significant reduction in antimicrobial activities against S. gallinarum, while similar treatment of the extracts from Rhus javanica Linn$\acute{e}$. caused a significant increase in antimicrobial activities against S. edidermidis. Since extracts from Rhus javanica Linn$\acute{e}$. and Caesalpinia sappan Linn$\acute{e}$. exhibited the highest antimicrobial activities, these extracts at the concentrations of 100, 300 or 500 ppm were added and then bacterial growth-inhibiting activities for S. gallinarum and S. epidermidis by these two extracts were further examined. Optical density at 620 nm ($OD_{620}$) after 24 hours incubation in the absence of Rhus javanica Linn$\acute{e}$. extract ranged from 0.30 to 0.45 compared with $OD_{620}$ value ranging from 0.06 to 0.18 in the presence of 100, 300 or 500 ppm of the extract, indicating that growth of all bacteria was significantly inhibited within 24 hours by the addition of at least 100 ppm of Rhus javanica Linn$\acute{e}$ extract. Value of $OD_{620}$ after 24 hours incubation in the absence of Caesalpinia sappan Linn$\acute{e}$. extract ranged from 0.30 to 0.55 compared with $OD_{620}$ value ranging from 0.05 to 0.15 in the presence of 300 or 500 ppm of the extract, indicating that growth of all bacteria was also significantly inhibited within 24 hours by the addition of at least 300 ppm of Caesalpinia sappan Linn$\acute{e}$. extract. In conclusion, these findings suggest that extracts from Rhus javanica Linn$\acute{e}$. and Caesalpinia sappan Linn$\acute{e}$. may play important roles in antimicrobial activities against S. gallinarum and S. epidermidis.

• Research in Plant Disease
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• v.20 no.4
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• pp.235-244
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• 2014

Clubroot and Fusarium wilt of cole crops (Brassica oleracea L.) are destructive diseases which for many years has brought a decline in quality and large losses in yields all over the world. The breeding of resistant cultivars is an effective approach to reduce the use of chemical fungicides and minimize crop losses. This study was conducted to evaluate the resistance of 60 cabbage (B. oleracea var. capitata) and 6 broccoli (B. oleracea var. italica) lines provided by The RDA-Genebank Information Center to clubroot and Fusarium wilt. To investigate resistance to clubroot, seedlings of the genetic resources were inoculated with Plasmodiophora brassicae by drenching the roots with a mixed spore suspension (1 : 1) of two isolates. Of the tested genetic resources, four cabbage lines were moderately resistant and 'K166220' represented the highest resistance to P. brassicae. The others were susceptible to clubroot. On the other hand, to select resistant plants to Fusarium wilt, the genetic resources were inoculated with Fusarium oxysporum f. sp. conglutinans by dipping the roots in spore suspension of the fungus. Among them, 17 cabbage and 5 broccoli lines were resistant, 16 cabbage lines were moderately resistant, and the others were susceptible to Fusarium wilt. Especially, three cabbage ('IT227115', 'K161791', 'K173350') and two broccoli ('IT227100', 'IT227099') lines were highly resistant to the fungus. We suggest that the resistant genetic resources can be used as a basic material for resistant B. oleracea breeding system against clubroot and Fusarium wilt.