• The korean journal of orthodontics
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• v.20 no.1
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• pp.123-133
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• 1990

The work was undertaken to evaluate the calcification of the second and the third molars in skeletal Class II and III malocclusions. The differences in the calcification stages between skeletal Class II and III malocclusion were evaluated and statistically analysed from panoramic radiographs of 202 males and females ranging in age from 11 to 15 years old. The results were as follows, 1. The calcification stages of the second and the third molars were not different between the skeletal Class II and III malocclusions in each age groups of both sexes. 2. The calcification stages of lower second and third molars of the skeletal Class III malocclusion are more advanced than those of the skeletal Class II malocclusion in male. 3. The clacification stages of upper second and third molars are more advanced than those of lower second and third molars in skeletal Class II malocclusion. 4. The calcification stages of lower second and third molars are more advanced than those of upper second and third molars in skeletal Class III malocclusion.

• Korean Journal of Cleft Lip And Palate
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• v.6 no.2
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• pp.59-67
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• 2003

A cephalometric study was performed to reveal differences between skeletal Class III malocclusion patients and cleft lip and palate patients, The material for this study consisted of 16 males (mean age 19.8, range 17-29) and 9 females(mean age 19.4, range 16-27) with cleft lip and palate, and 222 Skeletal Class III malocclusion patients(males 106, females 116), Cephalometric tracing and measurements were done by one investigator. Results were followed: 1. Cleft lip and palate group had more retrusive maxilla than the skeletal Class III malocclusion group. 2, Cleft lip and palate group had smaller effective maxillary and mandibular length than skeletal Class III malocclusion group, and the difference was more prominent in the mandible than in the maxilla. 3. Dental compensation was not observed in the upper incisors of cleft lip and palate group and in the lower incisors it was smaller than skeletal Class III group. 4, In the Gonial angle and lower anterior facial height values, there was no significant difference between cleft lip and palate and skeletal Class III malocclusion group. These results can be used in orthodontic treatment planning and orthognathic surgery for the cleft lip and palate patients.

• Journal of Yeungnam Medical Science
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• v.11 no.2
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• pp.323-331
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• 1994

1,050 patients who visited orthodontic dental department from 1983 to 1994, were surveyed on the yearly tendency of orthodontic patient distribution and state by means of Angle's classification. The results were as follows: 1. There was increased visiting rate of patient per year and higher visiting rate in female than in male. 2. 8-15 age group was 61.4% in total visiting patients and over 20 age group was 18.5%, under 7 age group was 8.1% 3. Class I malocclusion was 42.2%, class II div 1 was 22.5%, class II-2 was 3.9%, class III was 29.1% and cleft lip & palate was 2.0% in total visiting patient. 4. As showed the living distribution, Namgu and Susunggu's patients were 43.7% of the total patients. 5. There was increased tendency for the number of the patient to be recieved orthognathic surgery.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.285-294
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• 2021

This study analyzes the factors that determine the attitude toward the electronic wristband(smartband) to check the position of self-quarantine subjects due to COVID-19. Furthermore, I analyze the interaction of class and age among the factors that determine attitudes toward the electronic wristband. In this study, the attitude toward self-quarantine electronic wristband is analyzed as a binary logit model, focusing on class and age. As a result of the analysis, the middle class significantly agreed with the self-quarantine electronic wristband compared to the lower class, and the older the person, the more in favor. On the other hand, the interaction between the class and the age shows that the age weakens the positive effect on the attitude of the self-quarantine electronic wristband in the middle and upper middle classes. The implication of this study is that it is necessary to push for mandatory electronic wristband in areas with high proportion of high-aged people with positive attitude toward self-quarantine electronic wristband and in the same age group, the approval rate is low, so it is necessary to promote mandatory electronic wristband in areas where the vulnerable class is dense.

• Journal of Korea Foresty Energy
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• v.25 no.1
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• pp.1-8
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• 2006

This study was conducted to develope allometric equations and to estimate biomass, stem density, and biomass expansion factor for the three stand age classes (I-II, III-IV, and V-VI) of Japanese larch (Larix leptolepis) in Gapyeong area. Total dry weight (kg/tree) and aboveground biomass (ton/ha) were 57.8 and 71.1 for I-II class, 185.4 and 195.6 for III-IV class, and 1047.9 and 180.6 for V-VI class, respectively. Total above and belowground biomass (ton/ha) was 96.3 for I-II class, 265.7 for III-IV class, and 244.5 for V-VI class. The proportion (%) of stem to total biomass increased with stand age class and was 53.9 for I-II class, 55.7 for III-IV class, and 57.7 for V-VI class, respectively, while that of foliage decreased and was 7.1 for I-II class, 4.5 for III-IV class, 2.3 for V-VI class. Ratios of root to aboveground biomass were 0.35 for all age classes. Stem density ($g/cm^3$) differed between I-II class and III-VI class. Aboveground and total biomass expansion factors were 1.31-1.44 and 1.26-1.94. Our results showed that differences in stand density with stand age classes might influence allometric equation, stem density and ratios of aboveground biomass to stem biomass and total biomass to stem biomass (biomass expansion factors).

• Journal of Community Nutrition
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• v.6 no.2
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• pp.67-77
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• 2004

In order to investigate the differences of nutrient intakes by the economic status and different age groups and to identify the nutritional risk group and its specific nutrition problem, 2001 Korean National Health and Nutrition Survey were analyzed. The subject's numbers of 9,391 were classified into four classes such as low (14.2%), medium (37.2%), high (26.0%), and high above (22.6%) on the basis of the family monthly income and the 2001 Korean minimum cost of living according to the family size. Mean intakes of energy and all nutrients assessed by the RDAs, lipid-energy %, and MAR were increased as the economic status were going up. Na intake expressed per 1,000kcal was in reverse. Nearly a half(45.5%) of the low-income people seemed to take nutritionally inadequate diet in consideration with MAR values. Deficiencies of iron and even energy in the toddlers (1 to 2 years) of low-income class were of great concern. Adolescent age group has been observed that their calcium and iron intakes, and possibly energy, were appeared to be the most deficient among all the age groups regardless of the economic status. For the elderly in all the economic status except high-above class, calcium, vitamin A, and riboflavin were commonly deficient nutrients. Calcium deficiency was appeared throughout nearly all the ages except toddlers and all the economic classes. Even in the high-above class 57.3% took insufficient amount of calcium.

• Journal of Forest and Environmental Science
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• v.27 no.2
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• pp.113-118
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• 2011

This study was carried out to analyze annual diameter growth characteristics for major 11 tree species using the data for Gangwon province of the National Forest Resources Inventory in 2007. The annual diameter growth of coniferous species was 5.02 mm, 4.70 mm, and 3.90 mm in Korean white pine, Japanese larch, and Korean red pine, respectively. In growths of the deciduous trees, dogwood, basswood, and cork oak had 3.55 mm, 3.48 mm and 3.01 mm, respectively. Average of the annual diameter growths for all species was 3.38 mm. The relationship between diameter growth and age class showed that the growth rate decreased for all species as age increased. The age class II had the highest annual diameter rate. In relation of the stand density(trees per hectare) and diameter growth, the diameter growth tended to decrease as the stand density increased for most species, especially Korean white pine, cork oak, and basswood. Finally age had the highest value in the correlation coefficients between measurement factor and growth rate regardless of species.

• 한국노년학
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• v.29 no.2
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• pp.593-610
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• 2009

The Purpose of this study are to examine the middle-age and old worker's employment rates by age and gender at economic depression and recovery periods after the economic crisis, to identify the main 3causes of the change of the middle-age and old worker's employment rates between two periods, and to analyze whether the determinants affecting the middle-age and old worker's employment may be different by age and gender. For this study, The Annual Korean Labor Panel data(from 1st to 7th) are used. The results show that the employment rates are increased in the economic recovery period, and the difference between male and female employment rates decrease as ages go up. As we predicted, the determinants affecting the middle-age and old worker's employment are different by age and gender. For example, the existence of partner has positive effect on the male employment, but negative effect on female employment. The increases of the middle and old age worker's employment rates in the recovery period are mainly caused by the extension of the individualism(that is, the increases of the middle and upper class workers' employment), rather than the increases of the poor workers' employment rates due to the poverty(that is, the increases of the lower and poor class workers' employment). In the recovery period, comparing to the economic depression periods, the middle-age and old workers in the high class were likely to remain his(her) a good job while those in lower class are more difficult to get a job. This results show that the polarization of middle-age and old worker's employment has been appeared in the recovery periods(after 2001).

• International Journal of Reliability and Applications
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• v.7 no.1
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• pp.13-25
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• 2006

A new class of life distributions is studied. This class is defined based on comparing the residual life time to the whole life in the moment generating function order giving 'the new better than used in the moment generating function order ageing class $(NBU_{mgf})$'. Fundamental properties of this class are given including some closure properties and characterizations. Finally, we consider new results about comparisons of age and block replacement policies when the underlying distribution belongs to $NBU_{mgf}$ aging classes.

• Korean Journal of Child Studies
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• v.23 no.3
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• pp.149-169
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• 2002

The focus of this research was to understand the socio-demographic characteristics, pregnancy conditions, social support, and future plan of teenage unwed mothers in Korea. Among the unwed mother, the teenage group was a higher percentage (53.7%) than the over-twenties group (46.3%). In the distribution of teenage unwed mothers, the major part, 94.6%, was in the 16- to 17- year-old age range, and 5.4% were under 15 years of age. This indicates that the age of unwed mothers is getting lower. Most teenage unwed mothers were from intact(72.3%) and/or low-class(62.3%) families. A significant percentage (37.7%)was from middle- and upper-middle class families, signifying that teenage pregnancy is not a problem only of disadvantaged and lower class families. The education of one-third of the teenage unwed mothers in this study was only up to first year of middle school(7th grade), indicating that pregnancy may be a reason they dropped out of school.