• Tuberculosis and Respiratory Diseases
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• v.50 no.3
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• pp.320-333
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• 2001

Background : Peak expiratory flow (PEF) provides a simple, quantitative, and reproducible measure of the existence and severity of airflow obstructions. Peak flow meters are designed to monitor the condition asthma patients. There are many reports showing the normal predicted value of PEF in other countries. Studies on healthy Korean adults have been performed in a relatively small sample number and a lower limit for the normal value was not reported. Therefore, an attempt to provide normal predictive PEF value with a lower limit was made. Method : The PEF(Mini-Wright Peak Flow Meter) measurements and spirometry were done in 233 men and 631 women without history of respiratory disease. All subjects were non-smokers with no respiratory symptoms. The normal predictive value and its lower limit were developed by multiple regression analysis. The result was compared with regression equations in other reports. Results : The regression equation for the normal PEF predictive value(L/min) is $25.117+4.587{\times}$Age(year)-$0.064{\times}Age^2+2.931{\times}$Height(cm) in men($R^2=025$), and 146.942-$0.011{\times}Age^2+1.795{\times}$Height(cm)+$0.836{\times}$Weight(kg) in women($R^2=0.21$). The regression equation for the lower limit of this value (L/min) is $25.117+4.587{\times}$Age(year)-$0.064{\times}Age^2+1.936{\times}$Height(cm) in men, and $146.942-0.011{\times}Age^2+1.232{\times}$Height(cm)+$0.481{\times}$Weight(kg) in women. The residuals were normally distributed. The PEF in Korean males was sililar to those reported in British and Japanese subjects. The PEF in Korean females was similar to that in British subjects, but higher than the PEF in Japanese subjects. The lower limit of normal value was 71% of normal predictive PEF value in men and 76% in women. Conclusion : The normal predictive PEF value and its lower limit was measured from 233 male and 631 female asymptomatic, lifelong non-smoking participants. The normal predictive value was different from those of other studies on Korean subjects. Therefore, further studies are required.

• Journal of Global Scholars of Marketing Science
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• v.18 no.2
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• pp.223-252
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• 2008

In this study, we attempt to propose a choice-based diffusion model with switching cost, which can be used to forecast the dynamic substitution and competition among previous and new products at both individual-level and aggregate level, especially when market data for new products is insufficient. Additionally, we apply the proposed model to the empirical case of substitution and competition among Analog Cable TV that represents previous fixed charged broadcasting service and Digital Cable TV and Internet Protocol TV (IPTV) that are new ones, verify the validities of our proposed model, and finally derive related empirical implications. For empirical application, we obtained data from survey conducted as follows. Survey was administered by Dongseo Research to 1,000 adults aging from 20 to 60 living in Seoul, Korea, in May of 2007, under the title of 'Demand analysis of next generation fixed interactive broadcasting services'. Conjoint survey modified as follows, was used. First, as the traditional approach in conjoint analysis, we extracted 16 hypothetical alternative cards from the orthogonal design using important attributes and levels of next generation interactive broadcasting services which were determined by previous literature review and experts' comments. Again, we divided 16 conjoint cards into 4 groups, and thus composed 4 choice sets with 4 alternatives each. Therefore, each respondent faces 4 different hypothetical choice situations. In addition to this, we added two ways of modification. First, we asked the respondents to include the status-quo broadcasting services they subscribe to, as another alternative in each choice set. As a result, respondents choose the most preferred alternative among 5 alternatives consisting of 1 alternative with current subscription and 4 hypothetical alternatives in 4 choice sets. Modification of traditional conjoint survey in this way enabled us to estimate the factors related to switching cost or switching threshold in addition to the effects of attributes. Also, by using both revealed preference data(1 alternative with current subscription) and stated preference data (4 hypothetical alternatives), additional advantages in terms of the estimation properties and more conservative and realistic forecast, can be achieved. Second, we asked the respondents to choose the most preferred alternative while considering their expected adoption timing or switching timing. Respondents are asked to report their expected adoption or switching timing among 14 half-year points after the introduction of next generation broadcasting services. As a result, for each respondent, 14 observations with 5 alternatives for each period, are obtained, which results in panel-type data. Finally, this panel-type data consisting of $4{\ast}14{\ast}1000=56000$observations is used for estimation of the individual-level consumer adoption model. From the results obtained by empirical application, in case of forecasting the demand of new products without considering existence of previous product(s) and(or) switching cost factors, it is found that overestimated speed of diffusion at introductory stage or distorted predictions can be obtained, and as such, validities of our proposed model in which both existence of previous products and switching cost factors are properly considered, are verified. Also, it is found that proposed model can produce flexible patterns of market evolution depending on the degree of the effects of consumer preferences for the attributes of the alternatives on individual-level state transition, rather than following S-shaped curve assumed a priori. Empirically, it is found that in various scenarios with diverse combinations of prices, IPTV is more likely to take advantageous positions over Digital Cable TV in obtaining subscribers. Meanwhile, despite inferiorities in many technological attributes, Analog Cable TV, which is regarded as previous product in our analysis, is likely to be substituted by new services gradually rather than abruptly thanks to the advantage in low service charge and existence of high switching cost in fixed charged broadcasting service market.

• Tuberculosis and Respiratory Diseases
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• v.46 no.3
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• pp.372-385
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• 1999

Background: The purpose of this study was to examine the causes and pathologic process of chronic non-productive cough as an isolated symptom with a normal spirometry and chest radiograph by investigating clinicopathologic findings. Method: We studied 25 adults with chronic non-productive cough over a 3-week period with a normal chest radiograph and pulmonary function tests without any other symptoms. Clinical assessment, cough score, chest and sinus radiograph, pulmonary function tests, methacholine challenge, allergic skin prick test, and bronchoscopy for bronchial biopsies were performed. Subjects were then treated with prednesolone 20 to 30 mg/day for 1 to 2 weeks. Results: The experimental group was divided into two subgroups-those infiltrated with eosinophils, and those infiltrated with lymphocytes depending on eosinophil and lymphocyte counts, both of which were respectively higher than those of the control group. Eosinophils infiltrated group had mean numbers of eosinophil of 89.8 $cells/mm^3$ while control group's mean was 0.4 $cells/mm^2$(p=0.005). Lymphocyte infiltrated group was 4 patients whose mean was 84.3 $cells/mm^2$ with 28.4 $cells/mm^2$ of control group(P=0.026). In addition, the mean thickness of the basement membrane of experimental group was $14.20{\pm}5.20{\mu}m$ in contrast of control group whose mean was $3.50{\pm}1.37{\mu}m$(P=0.001). With the methacholine challenge test, 7 of the 21 eosinophil infiltrated subjects were diagnosed with cough variant asthma ; the other 14 with eosinophilic bronchitis. Three subjects with eosinophilic bronchitis were atopic positive (21.4%) with the skin prick test In the lymphocyte dominant group, all four subjects were diagnosed with lymphocytic bronchitis. Cough score was improved after steroid treatment in 22 of 25 subjects in the experimental group (88.0%). Conclusion: These results suggest chronic non-productive cough as an isolated symptom with a normal spirometry and chest radiograph was associated with airway inflammation by eosinophil and lymphocyte infiltration. The causes for chronic non-productive cough were eosinophilic bronchitis, cough variant asthma, and lymphocytic bronchitis(written in frequency). They further suggest that therapeutic treatment with steroids can provide effective symptomatic relief.

• Tuberculosis and Respiratory Diseases
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• v.42 no.4
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• pp.481-491
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• 1995

Background: Recently there has been a trend of an increasing incidence of mediastinal tuberculous lymphadenitis(MTL) in adults. MTL often cause bronchial stenosis or esophago-mediastinal fistula. In spite of effective treatment, it is difficult to cure. Moreover, relapse frequently occurs. Authors analyzed chest CT findings and clinical features of 29 cases with MTL Methods: 29 cases with MTL were retrospectively studied with the clinical and radiologic features from April 1990 to March 1995 Results: 1) A total of 29 cases were studied. 12 cases were male and 17 cases were female. The male to female ratio was 1:1.4 Mean age was 29 years old. The 3rd decade(45%) was the most prevalent age group 2) The most common presenting symptoms and signs were palpable neck masses(62%) followed by cough(59%) and sputum(38%) 3) Except in one case of MTL, all patients had coexisting pulmonary tuberculosis, cervical tuberculous lymphadenitis, endobronchial tuberculosis and tuberculous pleurisy. Among the coexisting tuberculous diseases, Pulmonary tuberculosis was the most common(76%) 4) On simple chest X-ray, mediastinal enlargement was noted in 21 cases(72%), but it was not noted in 8 cases(28%). The most frequently involving site was the paratracheal node in 16 cases(72%). Rt side predominence(73%) was noted 5) Patterns of node appearance on a postcontrast CT scan were classified into 3 types. There were 19 cases(30%) of the Homogenous type, 30 cases(47%) of the Central low density type and 15 cases(23%) of the Peripheral fat obliteration type. The most common type was the central low density type. The most common lymph node size was 1~2 cm(88%) 6) The most frequently involved site was the paratracheal node in 26 cases(89%) by chest CT. Rt side(63%) was predominant 7) 9 cases(43%) had complete therapy and most common treatment duration was 13 - 18 months. 12 cases(57%) had incomplete continuing antituberculous medication and half of the cases had been treated above 19 months. Conclusion: Chest CT findings of MTL showed central low density area and peripheral rim enhancement, so this characteristic findings could differentiate it from other mediastinal diseases and help a diagnosis of tuberculosis. In spite of effective antituberculous medication, it is difficult to cure. Moreover, relapse frequently occurs. Further studies will be needed of the clinical features and the treatment of MTL.

• Journal of Preventive Medicine and Public Health
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• v.30 no.2 s.57
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• pp.308-326
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• 1997

Many studies have led to the notion that essential hypertension in adults is the result of a process that starts early in life: investigation of blood pressure(BP) in children and adolescents can therefore contribute to knowledge of the etiology of the condition. A unique longitudinal study on BP in Korea, known as Kangwha Children's Blood Pressure(KCBP) Study was initiated in 1986 to investigate changes in BP in children. This study is a part of the KCBP study. The purposes of this study are to show changes in BP and to determine factors affecting to BP level and change in Korean adolescents during age period 12 to 16 years. A total of 710 students(335 males, 375 females) who were in the first grade at junior high school(12 years old) in 1992 in Kangwha County, Korea have been followed to measure BP and related factors(anthropometric, serologic and dietary factors) annually up to 1996. A total of 562 students(242 males, 320 females) completed all five annual examinations. The main results are as follows: 1. For males, mean systolic and diastolic BP at age 12 and 16 years old were 108.7 mmHg and 118.1 mmHg(systolic), and 69.5 mmHg and 73.4 mmHg(diastolic), respectively. BP level was the highest when students were at 15 years old. For females, mean systolic and diastolic BP at age 12 and 16 years were 114.4 mmHg and 113.5 mmHg(systolic) and 75.2 mmHg and 72.1 mmHg(diastolic), respectively. BP level reached the highest point when they were 13-14 years old. 2. Anthropometric variables(height, weight and body mass index, etc) increased constantly during the study period for males. However, the rate of increase was decreased for females after age 15 years. Serum total cholesterol decreased and triglyceride increased according to age for males, but they did not show any significant trend fer females. Total fat intake increased at age 16 years compared with that at age 14 years. Compositions of carbohydrate, protein and fat among total energy intake were 66.2:12.0:19.4, 64.1:12.1:21.8 at age 14 and 16 years, respectively. 3. Most of anthropometric measures, especially, height, body mass index(BMI) and triceps skinfold thickness showed a significant correlation with BP level in both sexes. When BMI was adjusted, serum total cholesterol showed a significant negative correlation with systolic BP at age 12 years in males, but at age 14 years the direction of correlation changed to positive. In females serum total cholesterol was negatively correlated with diastolic BP at age 15 and 16 years. Triglyceride and creatinine showed positive correlation with systolic and diastolic BP in males, but they did not show any correlation in females. There was no consistent findings between nutrient intake and BP level. However, protein intake correlated positively with diastolic BP level in males. 4. Blood pressure change was positively associated with changes in BMI and serum total cholesterol in both sexes. Change in creatinine was associated with BP change positively in males and negatively in females. Students whose sodium intake was high showed higher systolic and diastolic BP in males, and students whose total fat intake was high maintained lower level of BP in females. The major determinants on BP change was BMI in both sexes.

• The Korean Journal of Nuclear Medicine
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• v.34 no.5
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• pp.418-425
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• 2000

Purpose: There is no established formula for estimating renal depths in Korean. As a result, we undertook this study to develop a new formula, and to apply this formula in the calculation of glomerular filtration rate (GFR). Materials and Methods: We measured the renal depth (RD) on the abdominal CT obtained in 300 adults (M:F: 167:133, mean age 50.9 years) without known renal diseases. The RDs measured by CT were compared with the estimated RDs based on the Tonnesen and Taylor equations. New formulas were derived from the measured RDs in 200 out of 300 patients based on several variables such as sex, age, weight, and height by multiple regression analysis. The RDs estimated from the new formulas were compared with the measured RDs in the remaining 100 patients as a control. In 48 patients who underwent Tc-99m DTPA renal scintigraphy, GFR was measured with three equations (new formula, Tonnesen and Taylor equations), respectively, and compared with each other. Results: The mean values of the RDs measured from CT were 6.9 cm for right kidney of the men (MRK), 6.7 cm for left kidney of the men (MLK), 6.7 cm for right kidney of the women (WRK), and 6.6 cm for left kidney of the women (WLK). The RDs estimated from Tonnesen equation were shorter than the ones measured from CT significantly. The newly derived formulas were 12.813 (weight/height)+0.002 (age)+ 2.264 for MRK, 15.344 (weight/height)+0.011 (age)+0.557 for MLK, 12.936 (weight/height)+ 0.014 (age)+1.462 for WRK and 13.488 (weight/height)+0.019 (age)+0.762 for WLK. The correlation coefficients of the RD measured from CT and estimated from the new formula were 0.529 in MRK, 0.729 in MLK, 0.601 in WRK, and 0.724 in WLK, respectively. The GFRs from the new formula were significantly higher than those from the Tonnesen equation significantly, which was the most similar to normal GFR values. Conclusion: We generated new formulas for estimating RD in Korean from the data by CT. By adopting these formulas, we expect that GFR can be measured by the Gates method accurately in Korean.

• Korea journal of population studies
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• v.11 no.2
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• pp.54-66
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• 1988

I. Introduction Since the 1970's drug abuse among young people has increasingly become a social problem in Korea. In the 1980's, drug abuse, especially glue sniffing, has become the cause of many unfortunated incidents resulting in harm to others as well as the abusers themselves. Taking into consideration of the seriousness of this problem, the Republic of Korea National Red Cross initiated a nation-wide research programme, to understand the present situation and to raise the level of public awareness. The goal of this research was to begin a nation - wide campaign against drug abuse. The research team was composed of the Advisary Committee members and the staff of the Youth Department of the Republic of Korea National Red Cross. The data were collected in February 1988 with the collaboration of the staff and volunteers in the local Chapters. The respondents were allocated nation-wide by the quota sampling method. The questionnaires were distributed to the respondents in three groups :2, 700 to junior and senior high school students, 605 to working youths, and 916 to delinquent youths. A total of 4, 221 questionnaires were collected. II. Characteristics of the Respondents The respondents in each group were selected evenly from rural and urban areas. The general characteristics of the respondents can be described as follow: in case of students, the proportions between male and female respondents, and between senior high school and junior high school students were almost evenly distributed. In case of working youths, the proportion of females (80.5%) was higher than those of the students and the delinquents groups. Delinquent youths were defined as those currently being under custody of the centers for juvenile delinquents. Of this number, 38.8% and 68.2% were junior and senior high school drop-outs respectively. The majority of them (92.6%) were male. As for the family background of the respondents, the proportion of those residing in poverty - stricken areas, and the proportion of those from broken families were higher in case of working youths and delinquent youths than those in case of students. III. Present Patterns of Drug Abuse The following summarizes the presents of drug abuse, as tabulated from the results of the survey. 1. Smoking The percentage of youths who smoke was 36% in the student group, 32% m the working youths group, and 94.4% in the delinquent youths group. 2. Alcohol 50.3% of students, 71.6% of working youths, and 93.3% of delinquent youths has experienced drinking alcohol beverages. 3. Tonic: non - alcoholic, caffeinated beverages popular in Korea and Japan The percentage of those who have used tonic at least once was over 90% in all of the three groups. 4. Sedative About 70% of each group has used sedative with the proportion of working youths use higher than those in other groups. 5. Stimulants Those who have used stimulants comprised around 15% in each group. 6. Tranquilizers Somewhat less than 5% of students and working youths, and 28% of delinquent youths, have used tranquilizers. 7. Hypnotics The users of hypnotics amounted to 0.4% of students, 2.6% of working youths and 7.1% of delinquent youths. 8. Marihuana Those who have used marihuana indicated 0.7% of students, 0.8% of working youths, and 13% of delinquent youths. 9. Glue-sniffing The percentage of glue-sniffing was 3.7%, 5% in the students group and in the youths group respectively, but the proportion was unusually high, at 40.7% in the delinquent youths group. From the results of the survey the present situation of drug abuse in Korea can be summarized as follows: 1. A high percentage of Korean youths have experienced smoking cigarettes and drinking alcoholic beverages. 2. Tonics (non - alcoholic, caffeinated beverages), antipyretic analgesics and stimulants quite regularly used. 3. Tranquilizers, hypnotics, marihuana and glue-sniffing are more widely used among delinquent youths than the other youths. From this fact, there exists a correlation between drug abuse and juvenile delinquency. IV. Time-series Analysis of the First Experience of Drug Abuse and Deviant Behaviour The respoundents were asked when they were first exposed to drugs and when they committed deviant acts. By calculating the average age of each experience, the following pattern was found (See Figure 1). Youths are first exposed to drugs by abuse of tonic(non - alcoholic, caffeinated beverages). At the age of 13, they amoke cigarettes, the use of antipyretic analgesics begins at 14 year old, while at the age of 15, they use tranquilizers, and at 16 hynotics. The period of drug abuse which starts from drinking caffeinated beverages and smoking cigarettes and ends in the use of hypnotics takes about three years. During this period, other delinquent behaviours begin to surface, that is, at the age of 13 when smoking cigarettes begins, the delinquent behaviour pattern starts with truancy. Next, they start taking money from others by using physical force. Prior to the age of 15, they are suspended from school, become hostile to adults, begin running away from home, and start using stimulants and alcohol. Soon they become involved even in glue-sniffing and in the use of marihuana. At the age of 15, they begin to see adult videos and carry weapons. Sexual promiscuity and usage of tranquilizers follows the viewing of adult videos. Consequently, by the time they reach the age of 16, they visit drinking establishments, and are picked up by police for committing delinquent acts. And finally, they come to use hypnotic - type drugs. From the above descriptions, drug abuse can be assumed to have a close correlation with delinquent behaviour. V. Social Factors Related to Drug Abuse As for the Korean youths, glue-sniffing is found to he related to aggressive delinquency, in such cases as run - aways, being picked up by the police, and taking money by force. Smoking cigarettes and drinking alcohol is found to be related to seeing adult videos and visiting drinking establishments. Hypnotics and marihuana were found to be representive of drugs which are related to degenerational delinquency, irrespective of social delinquency. The social factors connected with these drug abuse are as follows: 1. Individual factors Male students were more heavily involved in the usage of drug than females. Youths who do not attend church were more likely to be involved in drugs than those who attend. 2. Family factors The youths who were displeased with their mothers smoking and those who thought their parents did not love each other, or those whose parents had used drugs without prescription, were more likely to he drug users. 3. School factors Those youths who found school life boring, were unsuccessful in their studies, spend most of their time with friends, feel their teachers smoke too much, those who had a positive perception of their teachers smoking were likely to he drug users. To sum up, drug abusers depend on the influence of their parents, teachers and peers. IV. Reasons for Drug Abuse Korean students have mainly used drugs to release stress (42.8%), to stay awake (19.7%), and because of the easy accessibility of drugs( 16.6%). Other reasons are due to their ignorance of the side effects of the drugs (3.6%), natural curiosity (4.2%), and to increase strength(3.O%). From the above facts, the major reasons for drug abuse among Korean youths are to release stress and to stay awake in order to prepare exams. Furthermore, since drugs are readily available, we can conclude that drug abuse is caused by the school system(such as entrance exams) in Korea. VII. Conclusion Drug usage among Korean youths are relatively less common than those of western youths. In some cases, such as, glue-sniffing and use of stimulants, the pattern of drug abuse is found. Moreover, early drug abuse is evident, and it has a close connection with deviant behaviour, resulting in juvenile delinquency. Drug abuse cannot be attributed to any one social factor. Specifically, drug abuse depends on parents, peers, teachers and other members of the community, and also is influenced by social institutions such as the entrance exam system. Every person and organization concerned with youth must participate collectively in restraining drug abuse. Finally, it is suggested that social agencial working for youth welfare should make every effort to tackle this serious problem confronted by the Korean youths today.