• Korean Journal of Cleft Lip And Palate
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• v.4 no.2
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• pp.19-27
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• 2001

This study was performed to determine the prevalence of hypodontia and hyperdontia of permanent teeth among Korean schoolchildren, and to compare differences in the prevalence between Korea, other country, and other ethnic groups. The sample consisted of 346 girls aged 6.9～0.3 yr and 375 boys aged 6.8～0.4 yr on whom a panoramic radiograph was taken at Yeonchun-Gun community in Korea. The prevalence of congenitally missing teeth (third molars excluded) was 6.7% in boys and somewhat higher, 9.5% in girls, and 8.0% for both sexes combined. On the average, number of missing teeth per affected child was 1.9 teeth. The most commonly congenitally missing teeth were the mandibular second premolar (32.7%), followed by the mandibular incisor (28.7%), the maxillary second premolar (16.7%), and the maxillary lateral incisors (10.2%). The prevalence of supernumerary teeth was 2.1 % in boys, 1.4% in girls, and 1.8% for both sexes combined. The most common supernumerary teeth were the mesiodens (76.9%), followed by the supernumerary premolar (23.1 %). The affected male-female ratio was 1.6: 1.0. The prevalence of congenital missing teeth in this study was similar to in studies of Japanese, Danish, American and German. The frequency of hyperdontia was lower in this study than in studies of Chinese children, Japanese and American.

• The korean journal of orthodontics
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• v.30 no.1 s.78
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• pp.43-52
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• 2000

Hemifacial microsomia ( HFM ) is the second most common craniofacial abnormalies. HFM represnted a spectrum of clinical findings such as hypoplasia of the mandibular ramus and condyle, confinement of maxilla growth, external and/or middle ear defects, involvement of some cranial suture, buccal soft tissue, facial nerve, and muscles in the affected side. HFM often showed progressive facial asymmetry and occlusal plane slanting to the affected side with growth. There were several reports about asymmetry of tooth maturation, hypodontia, delayed eruption, enamel hypoplasia in HFM. Since teeth develope in close association with size and morphology of the maxillary and the mandible, it is highly likely that dental changes will be present in HFM. So the Purpose of this study was to investigate the differences of the primary and the permanent teeth dimensions in the maxillary and the mandibular dentition between the affected and the non-affected side of HFM.. The sample of this study consisted of 34 unilateral HFM Patients (18 males and 16 females, average age : 5 year 11 months old). The authors examined the mesiodistal and the faciolingual dimensions of the primary and the permanent teeth and performed statistical study by using paired t-test. The results were as follows 1. The mesiodistal dimensions of the mandibular second primary molar and the mandibular first permanent molar in the affected side of HFM were significantly smaller than those of non-affected side. But there were no significant differences in the anterior teeth and the mandibular first primary molar. It means that a gradient of severity from anterior teeth to posterior teeth was found in the mandibular dentition. 2. Although there were no significant differences in the faciolingual dimensions of the primary and the permanent teeth in the maxillary and the mandibular dentition between the affected and non-affected side of HFM, there were general trend of compensatory increase in faciolingual dimension of the mandibular primary and the permanent teeth in the affected side Therefore these results showed that HFM might affect on the abnormality of tooth dimension, especially the most posterior teeth, in the affected side of the mandible.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.2
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• pp.253-261
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• 2006

Estimating the size of unerupted teeth is an essential aspect of orthodontic diagnosis and treatment planning in the mixed dentition. Several methods were introduced and used for the prediction. The most common methods among these would be Moyers probability chart and Tanaka and Johnston equations. These are currently used widely, but they were developed for Caucasians. Because there are clear racial differences in teeth size, the objectives of this study were to produce correlation coefficients between the combined mesiodistal widths of the permanent mandibular incisors and those of the canines and premolars for each quadrant, and prediction tables with regression equations, specifically for Korean. 178 young adults (70 women, 108 men, mean age 21.63 years) were selected from the College of Dentistry, Yonsei University, Seoul, Korea. The mesiodistal crown diameters of the permanent teeth were measured with calipers. Significant sexual dimorphism was found in tooth sizes. The correlation coefficients between the total mesiodistal width of the mandibular permanent incisors and those of the maxillary and mandibular canines and premolars were found to be between 0.52 and 0.64. The standard error of the estimatation was better (0.60) for women and the ${\gamma}^2$ values ranged from 0.27 to 0.41 for both sexes Prediction tables were prepared for Korean. This study showed larger canine and premolar diameters than Tanaka and Johnston's and Moyers' studies which might be due to the racial differences. Further investigations with a larger sample size will be needed for more representative data on the Korean population.

• Steel and Composite Structures
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• v.4 no.5
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• pp.385-402
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• 2004

Nearly 400 composite railway bridge decks of a new kind belonging to the trough type with U-shaped cross section have been constructed in Belgium over the last fifteen years. The construction of these bridge decks is rather complex with the preflexion of precambered steel girders, the prestressing of a concrete slab and the addition of a 2nd phase concrete. Until now, they have been designed with a classical computation method using a pseudo-elastic analysis with modular ratios. Globally, they perform according to the expectations but variability has been observed between the measured and the computed camber of these bridge decks just after the transfer of prestressing and also at long-term. A statistical analysis of the variability of the relative difference between the measured camber and the computed camber is made for a sample of 36 bridge decks using no less than 10 variables. The most significant variables to explain this variability at prestressing are the ratio between the maximum tensile stress reached in the steel girders during the preflexion and the yield strength and the type of steel girder. For the same sample, the long-term camber under permanent loading is computed by two methods and compared with measurements taken one or two years after the construction. The camber computed by the step-by-step method shows a better agreement with the measured camber than the camber computed by the classical method. The purpose of the paper is to report on the statistical analysis which was used to determine the most significant parameters to consider in the modeling in order to improve the prediction of the behaviour of these composite railway bridge decks.

• Progress in Superconductivity and Cryogenics
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• v.19 no.1
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• pp.30-35
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• 2017

The effects of the crystallographic orientation and sample thickness on the magnetic levitation forces (F) and trapped magnetic field (B) of single grain YBCO bulk superconductors were examined. Single grain YBCO samples with a (001), (110) or (100) surface were used as the test samples. The samples used for the force-distance (F-d) measurement were cooled at 77 K without a magnetic field (zero field cooling, ZFC), whereas the samples used for the B measurement were cooled under the external magnetic field of a Nd-B-Fe permanent magnet (field cooling, FC). It was found that F and B of the (001) surface were higher than those of the (110) or (100) surface, which is attributed to the higher critical current density ($J_c$) of the (001) surface. For the (001) samples with t=5-18 mm, the maximum magnetic levitation forces ($F_{max}s$) of the ZFC samples were larger than 40 N. About 80% of the applied magnetic field was trapped in the FC samples. However, the F and B decreased rapidly as t decreased below 5 mm. There exists a critical sample thickness (t=5 mm for the experimental condition of this study) for maintaining the large levitation/trapping properties, which is dependent on the material properties and magnitude of the external magnetic fields.

• Journal of Ecology and Environment
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• v.30 no.4
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• pp.325-330
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• 2007

Recognizing the ecological importance of forest gap formation for forest community structure, we examined the differences in species diversity between forest gaps and closed canopy areas for trees and shrubs in three developmental stages (seedling, sapling I, and sapling II) in a typical mixed broadleaved-Korean pine forest. We randomly placed 100 sample plots ($2{\times}2m$ for seedling and sapling I, and $5{\times}5m$ for sapling II) in forest gap and closed canopy areas of a 9 ha permanent sample plot for vegetation surveys of plants of each developmental stage in each habitat type. Even though the formation of forest gaps encouraged the occurrence of gap-dependent species and increased overall species diversity, there were no significant differences in species richness among the three developmental stages for both tree and shrub species (p>0.05). Comparing the two types of sites, statistical tests revealed no difference in species richness for trees, but highly significant differences (p<0.01) between forest types for shrubs for seedlings and sapling I, but not sapling II. Analysis of variance test indicated that there were no significant differences in species diversity among the three developmental stages of tree species (p>0.05) for both Simpson and Shannon indices. The variance for shrub seedlings was significantly different between forest gaps and closed canopy areas, but not for sapling I and sapling II. The analysis showed that the species diversity in forest gaps was significantly different from that of closed canopy areas for seedling and sapling I (p<0.01), but not for sapling II (p>0.05).

• The korean journal of orthodontics
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• v.21 no.1 s.33
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• pp.131-170
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• 1991

This study was designed to analyze morphological characteristics of Korean young adults, norms and standard deviation of variables, sexual differences, correlationship between each area of face and correlationship between hard tissue and soft tissue. The primary sample consisted of 45 males and 57 females who were early and middle twenties and had acceptable profile, no history of previous orthodontic treatment, absence of remarkably large overjet and overbite, full complement of permanent teeth, Class I skeletal and dental relationships and good vertical facial proportions. Their cephalograms were analyzed morphologically with a computer morphometrics. Then the final sample - 25 males and 38 females - were selected within 1 S.D. of E-line, ANB, P/A facial height ratio, Interincisal angle, L1 to A-Pog, ODI and APDI. The results of the study were as follows: 1 In the form and proportion of facial skeleton there were no significant differences between males and females, but in the size males were larger than females. 2. The dental protrusion patterns had no significant sexual difference and no significant correlationship between protrusion of upper lip and inclination of upper incisor. But mentolabial angle had positively correlated with interincisal angle and negatively with inclination of upper and lower incisor. 3. In the relationship between nose and soft-tissue profile, males were larger than females in nasal length, height and angular measurements. 4. In analysis of soft-tissue profile, males were larger than females in the length and thickness. In the angular measurements and proportion of soft-tissue profile, there were no significant differences between males and females.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.17 no.2
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• pp.1-11
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• 2004

Objective: Chronic otitis media is an inflammation and infection of the middle ear which is persistent. Chronic otitis media occurs when the eustachian tube becomes blocked repeatedly, multiple infections, ear trauma, or swelling of the adenoids. A chronic ear may be the result of an acute ear infection that does not clear completely, or the result of recurrent ear infections. A chronic ear infection may be more destructive than an acute ear infection because its effects are prolonged, and it may cause permanent damage to the ear. Methods : Experimental animals made use of 4-5 weeks age(weight 20-25g) ICR(male)mouse. In the breeding farm, the lighting time was controlled from 7:00 am until 7:00 pm, the temperature was controlled within $22{\pm}0.5{\circ}$ and water and food were not limited. The extracts which were extracted from Hwangginaetak-san devided low dose group( 1.0g/kg-HN) and high dose group(3.0g/kg-HN), they were intragastrically administered to the mouse of sample A and sample B prior to LPS I.P injection. Compared with inflammation induced group which were induced by LPS, we measured the WBC count, IL-6 level in plasma and TNF-${\alpha}$ level in plasma. Results: 1. Hwangginaetak-san decreased WBC count in inflammatory reaction induced by LPS 2. Hwangginaetak-san decreased IL-6 level in inflammatory reaction induced by LPS. 3. Hwangginaetak-san didn't decreased TNF-${\alpha}$ level in inflammatory reaction induced by LPS Conclusion: According to above results, Hwangginaetak-san was improved its suppression effect to the inflammatory reaction through WBC count and IL-6 level. So Hwangginaetak-san is considered to be used for treatment of chronic otitis media by controlling the WBC count and IL-6 level in plasma.

• Korean Journal of Materials Research
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• v.22 no.11
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• pp.569-574
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• 2012

Large single grain $Gd_{1.5}Ba_2Cu_3O_{7-y}$ (Gd1.5) bulk superconductors were fabricated by a top-seeded melt growth (TSMG) process using an $NdBa_2Cu_3O_{7-y}$ seed. The seeded Gd1.5 powder compacts with a diameter of 50 mm were subjected to the heating cycles of a TSMG process. After the TSMG process, the diameter of the single grain Gd1.5 compact was reduced to 43 mm owing to the volume contraction during the heat treatment. The superconducting transition temperature ($T_c$) of the top surface of the single grain Gd1.5 sample was as high as 93.5 K. The critical current densities ($J_cs$) at 77 K and 1T and 1.5 T were in ranges of 25,200-43,900 $A/cm^2$ and 10,000-23,000 $A/cm^2$, respectively. The maximum attractive force at 77 K of the sample field-cooled using an Nd-B-Fe permanent magnet (surface magnetic field of 0. 527 T) was 108.3 N; the maximum repulsive force of the zero field-cooled sample was 262 N. The magnetic flux density of the sample field-cooled at 77 K was 0.311T, which is approximately 85% of the applied magnetic field of 0.375 T. Microstructure investigation showed that many $Gd_2BaCuO_5$ (Gd211) particles of a few ${\mu}m$ in size, which are flux pinning sites of Gd123, were trapped within the $GdBa_2Cu_3O_{7-y}$ (Gd123) grain; unreacted $Ba_3Cu_5O_8$ liquid and Gd211 particles were present near the edge regions of the single grain Gd1.5 bulk compact.

• Journal of Preventive Medicine and Public Health
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• v.38 no.3
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• pp.337-344
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• 2005

Objectives : Job insecurity, such as non-standard work, is reported to have an adverse impact on health, regardless of health behaviors. The aim of this study was to examine the relationship between non-standard employment and health in Korea. Methods : We analyzed a representative weighted sample, which consisted of 2,112 men and 1,237 women, aged 15-64, from the 1998 Korea National Health and Nutrition Examination Survey. Non-standard employment included part-time permanent, short time temporary and daily workers. Self-reported health was used as a health indicator. Results : This study indicated that women were more likely to report poorer health than men with standard jobs. Of all employees, 20.3% were female manual workers. After adjusting for potential confounders, such as age, education, equivalent income, marital, social and self-reported economic status and health behavior factors, nonstandard employment was found to be significantly associated with poor health among female manual workers (OR, 1.86; 95% CI, 1.24 to 2.79). No significant association was found in other working groups Conclusions : Among female manual workers, nonstandard employees reported significantly poorer health compared with standard workers. This result raises concern as there are increasing numbers of non-standard workers, particularly females.