• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.1
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• pp.8-15
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• 1995

The reliable measurement of metal in biological media in human body is one of critical indicators for the proper evaluation of its toxic effect on human health. Recently in Korea the necessity of quality assurance of measurement in occupational health and occupational hygiene fields brought out regulatory quality control program. Lead is often used as a standard metal for the program in both fields of occupational health and hygiene. During last 20 years lead poisoning was prevalent in Korea and still is one of main heavy metal poisoning and the capability of the measurement of blood lead is one of prerequisites for institute of specialized occupational health in Korea. Furthermore blood lead is most important indicator to evaluate lead burden of human exposure to lead and the reliable and accurate analysis is most needed whenever possible. To evaluate the extent of the interlaboratory differences of blood lead measurement in several well-known institute specialized in occupational health in Korea, authors prepared 68 blood samples from two storage battery industries and all samples were divided into samples with 2 ml. One set of 68 samples were analyzed by authors's laboratory(Soonchunhyang University Institute of Industrial Medicine: SIIM) and 40 samples of other set were analyzed by C University Institute of Industrial Medicine(CIIM) and the rest 28 samples of other set were analyzed by Japanese institute(K Occupational Health Center:KOHC). Authors also prepared test bovine samples which were obtained from Japanese Federation of Occupational Health Organization (JFOHO) for quality control. Authors selected 2 other well-known occupational health laboratories and one laboratory specialized for instrumental analysis. A total of 6 laboratories joined the interlaboratory comparison of blood lead measurement and the results obtained were as follows: 1. There was no significant difference in average blood lead between SIIM and CIIM in different group of blood lead concentration, and the relative standard deviation of two laboratories was less than 3.0%. On the other hand, there was also no significant difference of average blood lead between SIIM and KOHC with relative standard deviation of 6.84% as maximum. 2. Taking less than 15% difference of mean or less than 6 ug/dl difference in below 40 ug/dl in whole blood as a criteria of agreement of measurement between two laboratories, agreement rates were 87.5%(35/40) and 78.6%(22/28) between SIIM and CIIM, SIIM and KOHC respectively. 3. The correlation of blood lead between SIIM and CIIM was 0.975 (p=0.0001) and the regression equation was SIIM = 2.19 + 0.9243 ClIM, whereas the correlation between SUM and KOHC was O.965(p=0.0001) with the equation of SIIM = 1.91 + 0.9794 KOHC. 4. Taking the reference value as a dependent variable and each of 6 laboratories's measurement value as a independent variable, the determination coefficient($R^2$) of simple regression equations of blood lead measurement for bovine test samples were very high($R^2>0.99$), and the regression coefficient(${\beta}$) was between 0.972 and 1.15 which indicated fairly good agreement of measurement results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.10
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• pp.896-908
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• 2014

The electrical medical device market have been expanded since the public interest in healthy living that has deepened together with the global health trend of the aging population. The external hand-held ultrasonic probe is a frequently approved medical device and it is commonly used in the clinical field. However, there is no obvious standard or a guideline in Korea on regarding evaluation of performance of such external hand-held ultrasonic probe for approval and quality management. In this study, local and foreign reference standards were reviewed to propose performance test standards and methods after conducting characteristic of probe, market, and permission status. In addition, such proposed test items were validated to develop a draft guideline that is internationally harmonized for performance evaluation. This study is expected not only improve the quality and performance of the external hand-held ultrasonic probe but also contribute to securing consistency of permission and evaluation works for approval.

• Journal of Digital Convergence
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• v.12 no.4
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• pp.293-303
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• 2014

The mobile game market is fast growing after the Kakao game launched. Especially, the market is placed at the second highest by occupying 33.1% of the market. However, the rate of the total sales amount is only 6%, showing quite an imbalance between the market occupancy and the sales amount. This means that the profit-making models are not stabilized yet in the mobile game market. The absence of profit-making models can be ascertained by the relationship of DAU and sales ranking. There are several games which are ranked at DAU Top10 among Google free games, but not ranked at top 10 among sales amounts. On the other hand, there are several games which are low in DAU ranking but high in sales amount ranking. This result shows that there is no direct interrelation between the product attractiveness which users feel and the profit-making models in the market. This study compared the Google play free games which are ranked at top 10 in terms of DAU ranking and sales amount ranking to find out the factor which causes the imbalance between the DAU ranking and sales amount ranking. Based on this outcome, this study presents the reference point for the design of profit-making models on behalf of the manufacturers who wish to launch into the mobile game market in the future.

• Tuberculosis and Respiratory Diseases
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• v.71 no.6
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• pp.431-437
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• 2011

Background: We tried to examine the small airway diseases which can be found early, in workers exposed to inorganic dusts. This is measured in normal breath by using the impulse oscillometry (IOS). Methods: The Pulmonary function test (forced vital capacit [FVC], forced expiratory volume in one second [$FEV_1$], forced expiratory flow between 25% and 75% of vital capacity [$FEF_{25-75}$]), IOS resistance (Rrs at 5, 10, 15, 20, 25, 35 Hz) and reactance (Xrs at 5, 10, 15, 20, 25, 35 Hz) were measured for 454 workers. The subjects were classified into 173 workers of normal (38.1%) and 281 patients with pneumoconiosis (61.9%). Results: There were significant differences between normal and patients with FVC ($3.82{\pm}0.61$ vs. $3.53{\pm}0.56L$), $FEV_1$ ($2.67{\pm}0.63$ vs. $2.35{\pm}0.48L$), and $FEF_{25-75}$ ($1.88{\pm}0.95$ vs. $1.47{\pm}0.80L/sec$) between groups (p<0.05). And as for IOS, there was no significant difference in resistance (Rrs) (p>0.05), and there were significant differences between normal and patients with reactance (Xrs) 15 Hz ($0.003{\pm}0.05$ vs. $-0.006{\pm}0.04kPa/L/s$), 20 Hz ($0.043{\pm}0.05$ vs. $0.031{\pm}0.04kPa/L/s$), and 35 Hz ($0.141{\pm}0.05$ vs. $0.131{\pm}0.05kPa/L/s$) between groups (p<0.05). Conclusion: We could find out that 15 Hz, 20 Hz, and 35 Hz values of reactance were significantly influenced by pneumoconiosis. When usefulness and reproducibility to carry out the IOS are considered, it is thought that in future work will be required to draw the reference values for normal Korean persons.

• Journal of the Korean Geographical Society
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• v.47 no.3
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• pp.359-374
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• 2012

This paper intends to examine spatial patterns and regional variations of aging population in Korea based on census data for 163 areas during 1980~2010. It briefly investigates general characteristics of aging population in Korea from previous studies and clarifies spatial patterns of aging process at regional level with reference of population growth rate at different time periods. Cities in Korea are classified into several stages including aging society, aged society and super-aged society according to the percentages of aging population out of total population every five years. At the regional scale, the stage of aging society was revealed from 1980, while the stage of aged society was shown from 1995 and super-aged society was entered from 2000 in Korea. Eighty cities in the analysis were shown at the stage of super-aged society in 2010. The portions of aging population are highly related to city size and population growth rate. For instance, the cities both in small size and with low population growth rate are revealing high percentage of aging population. As of 2010, most rural areas are staged into super-aged society, while most cities within Seoul metropolitan area and mid-sized cities are kept in the stage of aging society. At regional scale, there are no significant statistical correlations between total fertility rate and aging population.

• Journal of the Korean Society of School Health
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• v.5 no.1
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• pp.101-110
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• 1992

We investigated each 50 students in the primary school its 1st year student(boys & girls) on the conditions of oral hygiene between urban and rural children centering around the dental caries. The purpose of this study is to promote national oral health and to offer the basic data on the oral health level of community. We got conclusion as follows : 1. Sex : The prevalence rate of dental caries between the rural and urban children showed high to the urban children. 2. Education Level of Parents : When the educational background of father is high, the prevalence rate of dental caries showed high(P<0.01). The educational background of mother has not influenced on the prevalence rate. 3. Economic Level of Home : When the economic level of home is high, the prevalence rate of dental caries is high(P<0.01). 4. Intake Frequency of Eating Between Meals : The average intake frequency of eating between meals a day of urban children was $2.3{\pm}0.76times$, the average intake frequency of eating between males a day of urban children was $2.79{\pm}0.82times$(P<0.01). 5. Brushing Frequency : The average brushing a day of rural children was $2.48{\pm}0.82times$, urban children was $2.34{\pm}0.71times$, and when the brushing frequency is high, the prevalence rate of dental caries showed low(P<0.01). 6. Brushing Time : The rural children and urban children had no difference, but brushing time had influenced on the prevalence rate(P<0.01). 7. Kinds of Drinking Water: The kinds of drinking water had not influenced on the prevalence rate of dental caries. 8. Amount of Pocket Money : The urban children is the more amount of pocket money than the rural, when the amount of pocket money is lots, the prevalence rate of dental caries showed high(P<0.01). 9. Average Intake Frequency a day for the caries food of eating between meals of rural children was 2.91 times and urban children was 3.47 times. The average intake frequency a day for the caries food of eating between meals had influenced on the prevalence rate dental caries. In the point of view for the oral health, the urban children is bad than the rural children in the actual conditions of intake. The education of oral health for parents has demanded, the necessity of oral control for the children of the improvement effectively as the methods to maintain the oral health level.

• Journal of Korean Orthopaedic Sports Medicine
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• v.11 no.2
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• pp.75-81
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• 2012

Purpose: To evaluate the ultrasonographic (US) findings in both shoulders of asymptomatic high school baseball players and compare with healthy control. Materials and Methods: 42 individuals (age: $7.6{\pm}1.2$ years) participated in this study. We recruited two groups of high school male baseball players, 14 pitchers and 18 fielders without shoulder pain for recent 6 months as well as one control group of 10 untrained healthy high school students who were age-matched. Ultrasound measurements of thickness of the biceps and supraspinatus tendon and acromio-humral distance (AHD) at $0^{\circ}$ abduction were taken in dominant and nondominant shoulders. Results: On US examination, subacromial bursa effusion was observed in 7 of the dominant shoulders and in 2 of the nondominant shoulder of 32 baseball players and in none of the asymptomatic controls. The thickness of the biceps and supraspinatus tendons and AHD in both shoulders were significantly greater in the baseball players than in the controls (p<0.05). We also found that the biceps and supraspinatus tendon thickness and AHD of the dominant shoulder were significantly greater than the non-dominant shoulder in baseball players (p<0.05), but there were no differences between pitchers and fielders and between healthy controls. Conclusion: Subacromial effusion could be found even in the asymptomatic stage and the thickness of the biceps and supraspinatus tendons and AHD were significantly greater in the baseball players than in the healthy controls. Our data is useful reference guide for the ultrasonographic diagnosis of shoulder pathologies occurring in high school baseball players.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.149-154
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• 2002

This study is examined the difference between binocular spherical diopter and astigmatism diopter, spherical diopter, astigmatism diopter, and axis of astigmatism by sex and age with reference to the prescription of refraction for a total of 257 persons, 134 persons (male:78, female: 56)of teen-age and 123 persons of twenty-age who visit optical shop. Spherical correction diopter is mainly distributed to 280 eyes between -0.25D and -4.00D. And in astigmatism correction, for right astigmatism, 48 eyes(49.48%) are prescribed astigmatism diopter for a range of C-0.25~C-0.50D, 29 eyes(29.89%) has C-0.75~C-1.00D, 65 eyes(67.01%) has with the rule astigmatism. For left astigmatism, 43 eyes(42.57%) are prescribed astigmatism diopter of C-0.25~C-0.50D and 37 eyes(36.63%) has C-0.75C~1.00D, 73 eyes(72.27%) are shown with the rule astigmatism. And also each 108 persons(47.16%) and 28 persons(25.00%) are shown no difference between binocular spherical correction diopter and binocular astigmatism correction diopter, 94 eyes(39.49%) of teen-age and 104 eyes(42.27%) of twenty-age, male 119 eyes(41.90%) and female 79 eyes(34.34%) need correcting astigmatism. In pupillary distance, 165 persons mostly have 59~64mm.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.399-409
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• 2010

Steel structures are threatened to reduce load-carrying capacity as the cross section is decreased by corrosion. However, there has been no method in definitely evaluating residual load-carrying capacity and the effect of corrosion to the load-carrying capacity of steel. This study evaluated tensile residual load-carrying capacity of corroded steel plates by using tensile tests of specimens, which were selected from the web of temporary structure's main beam. After the surface shapes were measured and tensile tests were examined, the rust of 21 corroded specimens was, first of all, removed using a chemical method. From the tensile test result, which of reference specimens that was picked off at the flange of the same main 13-mm-thick beam and corroded specimens were based, surface geometry and correlation with the reduction of corroded thickness and strain, yield strength or tensile strength was established as constant numbers. Effective thickness of corroded steel with irregular cross sections could be calculated using average residual thickness and standard deviation. The irregular cross sections could be the evaluated tensile strength that is equalized to non-corroded uniform steel's regardless of corrosion. Also, reasonable measuring intervals of residual thickness could be proposed by using this result to apply for executive work.

• The korean journal of orthodontics
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• v.27 no.5 s.64
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• pp.669-682
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• 1997

[$Bj\ddot{o}rk$] and Skieller concluded after following facial growth patterns using implants in upper and lower jaw bones that stable structures, which are not influenced by the growth do exist and so these must be the reference landmarks in the process of superimposition. In spite of such facts, for the last 40 years since the discovery of stable structures, most orthodontists have preferred best fit superimposition method to structural method. Cases such as Angle's Class II division 2 malocclusion that show characteristic forward and upward growth or one under long period of post-treatment observation demonstrate that distinct differences exist between the two methods of superimposition. Today, ethical concerns prohibit further growth studies that use implants, md so there is no choice but to use stable structural superimposition method based on $Bj\ddot{o}rk's$ data. Thus, to encourage clinical use of stable structural superimposition method, logic for the use of stable structural superimposition method will be demonstrated, and its technical methods of application will be introduced step by step.