• Management & Information Systems Review
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• v.30 no.4
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• pp.147-173
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• 2011

It is generally accepted that there are momentum effects in the short term and reversal effects in the long term, which makes abnormal excess returns in the major stock markets in the world. In Korea stock market, however, the previous studies demonstrate that contrarian strategies based on reversal effects are more effective than momentum strategies following momentum effects in the short term as well as in the long term. This paper examines wether contrarian strategies are still effective In Korea stock market from 1980 to 2009, and the short term reversals may be changed after the foreign exchange crisis in 1997-1998. Moreover, this paper investigates how contrarian profits are shown considering the state of market. In my research, unlike previous studies, I find that both of contrarian strategies using price change and price level cannot gain excess risk adjusted returns in Korea stock market from 1980 to 2009, but this result is due to the fact that reversal effects existed before the foreign exchange crisis but momentum effects does after the foreign exchange crisis in 1997-1998. Specially, after the foreign exchange crisis, it is confirmed momentum strategies using 52 week high price, that is, price level are more effective than momentum strategies using price change. And following the strategies using 52 week high price after the foreign exchange crisis, the momentum is not only observed in the up market but also in the down market, which is different with the results of the studies regarding to American market, where the momentum is just found in the up market.

• The Korean Journal of Air & Space Law and Policy
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• v.29 no.1
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• pp.3-32
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• 2014

Safety Management System is the aviation industry policy for while operating the aircraft, to ensure the safety crew, aircraft and passengers. For operating a safe aircraft, in order to establish the international technical standards, the International Civil Aviation Organization has established the Annex 19 of the Convention on International Civil Aviation. As a result, member country was supposed to be in accordance with the policy of the International Civil Aviation Organization, to accept the international standard of domestic air law. The South Korean government announced that it would promote active safety management strategy in primary aviation policy master plan of 2012. And, by integrating and state safety programmes(ssp) and safety management system(sms) for the safe management of Annex 19 is to enforce the policy on aviation safety standards. State safety programmes(ssp) is a system of activities for the aim of strengthening the safety and integrated management of the activities of government. State safety programmes(ssp) is important on the basis of the data of the risk information. Collecting aviation hazard information is necessary for efficient operation of the state safety programmes(ssp) Korean government must implement the strategy required to comply with aviation methods and standards of the International Civil Aviation Organization. Airlines, must strive to safety features for safety culture construction and improvement of safety management is realized. It is necessary to make regulations on the basis of the aviation practice, for aviation safety regulatory requirements, aviation safety should reflect the opinion of the aviation industry.

• Sleep Medicine and Psychophysiology
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• v.5 no.1
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• pp.88-102
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• 1998

Objectives : We attempted to study obstructive sleep apnea symptoms prevalence and sleep apnea-associated factors in Korean rural adult population. Methods : In 1,441 adult subjects of three rural communities selected by cluster sampling, we administered an epidemiologic survey using questionnaire methods from July 14, 1996 to July 28, 1996. Results : 1) In 14.1% of the subjects, snoring was reported to occur almost daily and 2.9% of the subjects reported sleep apnea symptoms occurring almost daily. 2) Snoring and sleep apnea symptoms were found more frequently in males or in mid-aged group(45 - 64 years old) than in females or in younger- and older-aged groups, respectively. Compared with the subjects who have no snoring, the subjects who have snoring or sleep apnea symptoms had greater body mass index(BMI), waist-hip ratio, hemoglobin level, RBC count, and higher diastolic blood pressure. 3) Cigarette smoking and alcohol drinking more than once a week were significantly associated with suffering from sleep apnea symptoms. 4) In multiple logistic regression analysis, being male, mid-aged, and greater BMI were independently associated with the presence of snoring and sleep apnea symptoms. Conclusion : We conclude that, in the Korean rural adult population, males or mid-aged group suffers more from snoring and sleep apnea symptoms than females or younger- and older-aged groups. In addition, being male, mid-aged, and greater BMI were significantly associated independently with the presence of snoring and sleep apnea symptoms.

• Tuberculosis and Respiratory Diseases
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• v.42 no.6
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• pp.888-899
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• 1995

Background: Topical inhaled steroids, budesonide(Bu) and beclomethasone dipropionate (BOP), are now established as effective drugs in the management of chronic asthma. These drugs have high topical anti-inflammatory effect with low systemic activity. This study was performed to determine the effects of two inhaled corticosteroids, Bu and BOP, on the adrenocortical supression in 44 patients with bronchial asthma or chronic obstructive pulmonary disease. Methods: The adrenocortical function was assessed by measurement of serum cortisol concentration at 8 o'clock in morning and free cortisol in 24-hour urine collection at interval in 44 patients. No steroid was administered during the pretreatment period of 10 days and the final 6 days of the study. Each subject inhaled BOP or Bu, in daily doses of 800 or 1,600 micrograms for 12 days. The dose was delivered by metered dose inhaler (MDI) or diskhaler or large spacing device attached to MDI. Results: The levels of serum cortisol and 24-hour urinary free cortisol were decreased during the treatment period in patients inhaled Bu delivered by MDI in daily doses of 800 and 1,600 micrograms. In contrast, serum cortisol level was decreased on 6 and 12th day of treatment period in patients with BDP diskhaler in daily doses of 800 micrograms. In daily doses of 1,600 micrograms, the serum cortisol and 24hour urine free cortisol levels were decreased on 6, 9 and 12th day of treatment period in patients with BDP disk haler. The serum cortisol and 24-hour urinary free cortisol levels were not significantly decreased during the treatment period in patients inhaled Bu delivered by large spacing device attached to a MDI. Conclusion: These results showed that 1) the endogenous cortisol secretion was suppressed after inhalation of BDP and Bu in daily doses of 800 and 1,600micrograms, 2) Bu with MDI suppressed the adrenocortical function more than BDP with diskhaler, in daily doses of 1600 micrograms. and 3)large spacing device attached to a MDI might decrease the risk of suppression in the hypothalamic -pituitary- adrenal axis.

• Tuberculosis and Respiratory Diseases
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• v.39 no.6
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• pp.511-516
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• 1992

Background: It is well known that cigarette smoking is the risk factor of lung cancer, chronic obstructive pulmonary disease and ischemic heart disease. But there are few reports about the immediate effect of cigarette smoking on the cardiopulmonary functions. The serum level of carbon monoxide increases during cigarette smoking. It is known that carbon monoxide increases respration rate, heart rate and cardiac output, with decrease in maximal oxygen consumption. So we have studied to determine the immediate effects of cigarette smoking on the cardiopulmonary function during exercise. Method: Thirteen healthy smoking male subjects were included in this study. Each subject was undertaken pulmonary function test and incremental exercise test on two separate days, one without smoking (control) and the other after smoking three cigarettes per hour for five hours. The order of the two tests was randomized. Results: 1) The mean age of the subjects was $25{\pm}4.9$ year-old and the mean smoking history was $6{\pm}5$ pack years. 2) The mean blood level of carbon monoxide on the smoking day was higher than that on the nonsmoking day ($5.97{\pm}1.34%$ vs. $1.45{\pm}0.83%$; p<0.01). 3) The mean maximal oxygen consumption on the smoking day was lower than that on the nonsmoking day ($2.09{\pm}0.32$ L/min vs. $2.39{\pm}0.32$ L/min; p<0.05). 4) The mean anaerobic threshold on the smoking day was lower than that on the nonsmoking day ($1.33{\pm}0.24$ L/min vs. $1.53{\pm}0.20$ L/min; p<0.05). 5) The mean heart rate at rest on the smoking day was higher than that on nonsmoking day ($84.38{\pm}11.06$ beats/min vs. $75.46{\pm}5.83$ beats/min; p<0.05). But the means of maximal heart rate on both days were not different. 6) The pulmonary function tests were similar on both days. Conclusion: There was no change in pulmonary function test, but the maximal oxygen consumption and anaerobic threshold were decreased on the smoking day. So it was concluded that cigarette smoking impaired the cardiovascular functions immediately during exercise.

• Tuberculosis and Respiratory Diseases
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• v.43 no.2
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• pp.138-146
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• 1996

Background : Known as a kind of complication or a specific form of pulmonary tuberculosis, endobronchial tuberculosis caused several kinds of problems in diagnosis and managements. But the frequency of this disease are is widely variable, generally reported from as low as 10 - 20 % to as high as 40 - 50 %. We prospectively performed bronchoscopy in patients diagnosed as pulmonary tuberculosis to evaluate the frequency of endobronchial tuberculosis and its related findings. Method : From March, 1995 to February, 1996, we prospectively performed bronchoscopy in patients newly diagnosed as pulmonary tuberculosis and evaluated the frequency of endobronchial tuberculosis, its clinical features and laboratory findings including raiologic, microbiologic and physiologic aspects. Results : Number of patients diagnosed as pulmonary tuberculosis was 103 and 55 patients(53.4%) were found to have endobronchial tuberculosis. But the frequency were 43.8% in male and 76.7% in female, respectively. Frequently noted symptoms were nonspecific including cough, sputum, fever, weight loss in the order of frequency but cough was more frequent than in pulmonary tuberculosis. Physical examination showed rale, decreased breathing sound and wheezing and wheezing was more frequent than in pulmonary tuberculosis. All 7 subtypes were noted bronchoscopically and edema-hyperemia (stenotic without fibrosis) type was most frequently(32.7%) noted, and followed by chronic nonspecific bronchitis type, stenotic with fibrosis type and actively caseating type in the order of frequency. The relationship between subtypes of endobronchial tuberculosis and radiologic findings was insignificant. Right lung was involved more frequently than left lung and left upper lobe was most commonly involved site, and followed by right upper lobe and trachea. Acid-fast bacilli(AFB) positivity in sputum and / or bronchial washing fluid was 73% and suggested high risk of infectivity. Conclusion : The frequency of endobronchial tuberculosis in patients with pulmonary tuberculosis was higher than known and also suggested bronchoscopic examination to detect endobronchial involvement should be recommanded and careful management is also needed to prevent complications.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.629-638
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• 1997

Background : Surgical intervention is known as the principle management for hemoptysis of significant amount. But surgical procedure is applicable to only small number of patients because of increased mortality in emergency surgery and various functional and structural problems after lung resection. Bronchial artery embolization(BAE) has been used as an alternative interventional technique for immediate control of patients with increased risk for surgery due to recurrent or massive hemoptysis. BAE also has limitations such as recurrent bleeding after procedure and its role for the application to small amount of hemoptysis is still not established. Method : To evaluate immediate and long term effectiveness of BAE, we analysed 65 patients with hemoptysis according to therapeutic modalities they received ; BAE versus conservative management. Results : The success rate for immediate control of hemoptysis was significantly higher in BAE group with 43 cases(100%) among 43 cases compared with 17 cases(77%) among 22 cases in conservative group (p < 0.001). The disease control duration was $19.5{\pm}8.06$ months in BAE group and $18.8{\pm}6.06$ months in conservative group(p > 0.05). The therapeutic response in BAE group was 82%(36/43 cases) and 95%(21/22 cases) in conservative group (p > 0.05). According to the amount of hemoptysis, the therapeutic response were seen in 91%(29/32 cases) in less than 100ml and 85%(28/33 cases) in 100~400ml (p > 0.05). According to the manifestation of hemoptysis, the therapeutic response in groups of recurrent and nonrecurent were 87%(20/23 cases) and 88%(37/42 cases)(p > 0.05). Conclusion : The difference of therapeutic response between BAE and conservative group in patients with small amounts of hemoptysis was not found except for immediate control of hemoptysis.

• The Journal of Society for e-Business Studies
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• v.20 no.3
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• pp.59-77
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• 2015

Social networking sites (SNS), such as Facebook, provide abundant social comparison opportunities. Given the widespread use of SNSs, the purpose of the present study was to examine the impact of exposure to social media-based social comparison on user's negative emotions and discontinuous use intention on SNS. We present evidence that under the use of SNS, social comparison activities diverge into three patterns, with explicit self-evaluation desire made against similar target (lateral comparison), self-defense desire made against less fortunate target (downward comparison), and self-enhancement desire made with more fortunate target (upward comparison). Such social comparison processes frequently arise, as people are increasingly using on SNSs, the downward contacts ameliorating self-esteem with positive emotions, but the upward contacts and standard contacts with lateral status enabling a person to compare his or her situation with others and simultaneously increase negative emotions due to its differences with others. In other words, as people increasingly relying on SNSs for a variety of everyday tasks, they risk overexposure to upward or standard social comparison information that may have a cumulative detrimental impact on future intention on SNS use. This study with survey with 209 SNS users found that these negative emotions lead to negative fatigue (attitude) and then discontinuous use intention (behavior) on SNS. Our findings are among the first to explicitly examine discontinuous use intention on SNS using social comparison theory and our results are consistent with those of past research showing that upward social comparisons can be detrimental.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.3
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• pp.183-190
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• 2004

Objectives: Methylenetetrahydrofolate reductase (MTHFR) mutation are commonly associated with hyperhomocysteinemia, and through their defects in homocysteine metabolism, they have been implicated as a risk factor for recurrent spontaneous abortion. Recent report describe that 28-bp tandem repeat polymorphism in thymidylate synthase enhancer region (TSER) that influence enzyme activity would affect plasma homocysteine level. We have investigated the relationship between TSER genotype and plasma homocysteine level in 54 patients with recurrent spontaneous abortion. Methods: Plasma homocysteine level was measured by fluorescent polarizing immunoassay. MTHFR mutation (C677T and A1298C) was identified by PCR-restriction fragment length polymorphism assay and TSER mutation was analyzed by PCR method. The data were analyzed using the program SAS 8.2 for Windows. Results: Total homocysteine level was significantly higher in MTHFR 677TT genotype ($9.80{\pm}3.87{\mu}mol/L$) than MTHFR 677CC genotype ($8.14{\pm}1.74{\mu}mol/L$) in Korean patients with unexplained recurrent spontaneous abortion (p=0.0143). However, the plasma homocysteine level was not significantly different in the MTHFR 1298AA ($8.42{\pm}2.65{\mu}mol/L$) and 1298CC ($6.09{\pm}0.32{\mu}mol/L$; p=0.2058) and, TSER 2R2R ($8.61{\pm}1.68{\mu}mol/L$) and 3R3R ($8.05{\pm}2.81{\mu}mol/L$; p=0.9319) mutant genotypes, respectively. In this study, we found the combination effects of TSER and MTHFR C677T genotypes. Plasma homocysteine levels were the highest ($11.47{\pm}4.66{\mu}mol/L$) in individuals with TSER 3R3R ($8.05{\pm}2.81{\mu}mol/L$) and MTHFR 677TT ($9.80{\pm}3.87{\mu}mol/L$) genotypes. Individuals with a combination of both TSER 2R2R/2R3R and MTHFR 677CC/CT genotypes ($7.69{\pm}1.77{\mu}mol/L$) had lower plasma homocysteine levels than TSER 2R2R ($8.61{\pm}1.68{\mu}mol/L$) and MTHR 677CC ($8.14{\pm}1.74{\mu}mol/L$) genotypes, respectively. The effect of MTHFR polymorphism in the homocysteine metabolism appears to be stronger than that of TSER polymorphism. Conclusion: Although statistically not significant, we found the elevated level of plasma homocysteine in combined genotypes with TSER and MTHFR (C677T and A1298C) in Korean patients with unexplained habitual abortion. In this study, we reported the possibility that TSER polymorphism is a genetic determinant of plasma homocysteine levels in the Korean patients as well as MTHFR C677T polymorphism. A large prospective study is needed to verify our findings.

• Korean Journal of Food Science and Technology
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• v.37 no.4
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• pp.660-670
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• 2005

Standard procedure for development of food list was established based on food intake data of 2001 National Health and Nutrition Survey and 2002 Seasonal Nutrition Survey for Total Diet Study. Foods were sorted in descending order of mean intake, and 54 items within cumulative percentage of 80 were selected, followed by selection of 16 additional items with consumption frequency of 10% or higher. Based on higher consumption in certain seasons, regions, sexes, and age classes, 14 additional items were added. Additional 17 items with probable high contents of heavy metals or 23 items with probable high pesticide residues were added. Altogether, 101 and 107 individual food items were included for heavy metal and pesticide residue lists, accounting for 84.9 and 83.3% mean energy intakes of Korean population, respectively.