• Clinical and Experimental Reproductive Medicine
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• v.32 no.3
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• pp.243-251
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• 2005

Objective: Low-dose aspirin have been proposed to improving endometrial receptivity and pregnancy rate in COH-IVF by increasing endometrial perfusion. However, the effect of low-dose aspirin in COH-IVF could be negligible because there have been large quantity of other important factors responsible for changing endometrial perfusion accompanied by COH procedure. In contrast, in frozen-thawed embryo transfer cycles which were not accompanied by COH procedure, the effects of low-dose aspirin in endometrial blood flow seems to be more certain than in COH-IVF cycles. In this study, we analyzed the effect of low-dose aspirin treatment on implantation and pregnancy rates in patients undergoing frozen-thawed embryo transfer Methods: From January 2003 to December 2003, total 264 cycles from 264 patients who attended infertility clinic at Samsung Cheil Hospital were enrolled in this study. All cases included in this study, embryos were frozen and thawed at the pronuclear stage and three days after incubation, at least 2 or more good quality embryos were transferred into uterus. In study group, low dose aspirin (100 mg/day) was administrated from the first or second date of menstrual day to 9 days after embryo transfer. On the other hand, control group did not take any medicine except estradiol valerate for endometrial priming. Several variables including implantation and pregnancy rates were compared in both groups. After then, each groups were stratified by endometrial thickness checked at embryo transfer (ET) day such as (28 mm versus <8 mm) and same variables above described were compared between study and control groups. Results: The mean age, infertility duration, endometrial thickness at embryo transfer day and mean number of transferred embryo were not significantly different in both groups. Also, implantation rates (study group: 15.8%, control group: 20.5%) and pregnancy rate (study group: 45.1%, control group: 43.5%) were not significantly different between two groups. (p>0.05) After we analyzed same variables stratified by endometrial thickness checked at embryo transfer day, we could not found any significant difference between study and control groups. Conclusions: Low-dose aspirin treatment seems to have no advantage of improving implantation and pregnancy rates in patients undergoing frozen-thawed embryo transfer.

• Tuberculosis and Respiratory Diseases
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• v.44 no.5
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• pp.1094-1104
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• 1997

Background : Spontaneous pneumothoraces(SP) are divided into primary spontaneous pneumothoraces (PSP) which develop in healthy individuals without underlying pulmonary disorders and secondary spontaneous pneumothoraces(SSP) which occur in those who have underlying disorders such as tuberculosis or chronic obstructive lung diseases. Yet there is no established standard therapeutic approach to this disorder, i.e., from the spectrum of noninvasive treatment such as clinical observation with or without oxygen therapy, to aggressively invasive thoracoscopic bullectomy or open thoracotomy. Although chest tube thoracostomy has been most widely used, the patients should overcome pain in the initiation of tube insertion or during indwelling it potential infection and subcutaneous emphysema. Thus smaller-caliber tube has been challenged for the treatment of pneumothorax. Previously, we studied the therapeutic efficacy of 8 French catheter for spontaneous pneumothorax. But there has been few data for effectiveness of small-caliber catheterization in comparison with that of chest tube. In this study, we intended to observe the long-term effectiveness of 8 French catheter for the treatment of spontaneous pneumothoraces in comparison with that of chest tube thoracostomy. Method : From January, 1990 to January, 1996, sixty two patients with spontaneous pneumothoraces treated at Chung-Ang University Hospital were reviewed retrospectively. The patients were sub-divided into a group treated with 8 French catheter(n=23) and the other one with chest tube insertion(n=39). The clinical data were reviewed(age, sex, underlying pulmonary disorders, past history of pneumothorax, size of pneumothorax, follow-up period). And therapeutic effect of two groups was compared by treatment duration(duration of indwelling catheter or tube), treatment-associated complications and recurrence rate. Results : The follow-up period(median) of 8 French catheter group and chest tube group was 28 and 22 months, which had no statistical significance. Ther was no statistically significant difference of clinical characteristics between two groups with SP, PSP, SSP. The indwelling time of 8 French catheter group was $6.2{\pm}3.8$ days, which was significantly shorter than that of chest tube group in SP, $9.1{\pm}7.5$ days(p=0.047). In comparison of treatment-related complication in PSP, 8 French catheter group as 6.25% of complication showed lower tendency than the other group as 23.8% (p=0.041 ; one-tailed, p=0.053; two-tailed). The recurrence rate in each group of SP was 17.4%, 10.3%, which did not show any statistically significant difference. Conclusion : Treatment with 8 French catheter resulted in shorter indwelling time in sponteous pneumothorax, and lower incidence of treatment-related complication in primary spontaneous pneumothorax. And the recurrence rate in each of treatment group showed no statistically significant difference. So, we can recommend the 8 French small-caliber catheter for the initial therapy for spontaneous pneumothorax for the replacement of conventional chest tube thoracostomy. But further prospective study with more subjects of spontaneous pneumothorax will be needed for the evaluation of effectiveness of 8 French cateter.

• Journal of Intelligence and Information Systems
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• v.16 no.2
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• pp.19-32
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• 2010

Volatility plays a central role in both academic and practical applications, especially in pricing financial derivative products and trading volatility strategies. This study presents a novel mechanism based on generalized autoregressive conditional heteroskedasticity (GARCH) models that is able to enhance the performance of intelligent volatility trading systems by predicting Korean stock market volatility more accurately. In particular, we embedded the concept of the volatility asymmetry documented widely in the literature into our model. The newly developed Korean stock market volatility index of KOSPI 200, VKOSPI, is used as a volatility proxy. It is the price of a linear portfolio of the KOSPI 200 index options and measures the effect of the expectations of dealers and option traders on stock market volatility for 30 calendar days. The KOSPI 200 index options market started in 1997 and has become the most actively traded market in the world. Its trading volume is more than 10 million contracts a day and records the highest of all the stock index option markets. Therefore, analyzing the VKOSPI has great importance in understanding volatility inherent in option prices and can afford some trading ideas for futures and option dealers. Use of the VKOSPI as volatility proxy avoids statistical estimation problems associated with other measures of volatility since the VKOSPI is model-free expected volatility of market participants calculated directly from the transacted option prices. This study estimates the symmetric and asymmetric GARCH models for the KOSPI 200 index from January 2003 to December 2006 by the maximum likelihood procedure. Asymmetric GARCH models include GJR-GARCH model of Glosten, Jagannathan and Runke, exponential GARCH model of Nelson and power autoregressive conditional heteroskedasticity (ARCH) of Ding, Granger and Engle. Symmetric GARCH model indicates basic GARCH (1, 1). Tomorrow's forecasted value and change direction of stock market volatility are obtained by recursive GARCH specifications from January 2007 to December 2009 and are compared with the VKOSPI. Empirical results indicate that negative unanticipated returns increase volatility more than positive return shocks of equal magnitude decrease volatility, indicating the existence of volatility asymmetry in the Korean stock market. The point value and change direction of tomorrow VKOSPI are estimated and forecasted by GARCH models. Volatility trading system is developed using the forecasted change direction of the VKOSPI, that is, if tomorrow VKOSPI is expected to rise, a long straddle or strangle position is established. A short straddle or strangle position is taken if VKOSPI is expected to fall tomorrow. Total profit is calculated as the cumulative sum of the VKOSPI percentage change. If forecasted direction is correct, the absolute value of the VKOSPI percentage changes is added to trading profit. It is subtracted from the trading profit if forecasted direction is not correct. For the in-sample period, the power ARCH model best fits in a statistical metric, Mean Squared Prediction Error (MSPE), and the exponential GARCH model shows the highest Mean Correct Prediction (MCP). The power ARCH model best fits also for the out-of-sample period and provides the highest probability for the VKOSPI change direction tomorrow. Generally, the power ARCH model shows the best fit for the VKOSPI. All the GARCH models provide trading profits for volatility trading system and the exponential GARCH model shows the best performance, annual profit of 197.56%, during the in-sample period. The GARCH models present trading profits during the out-of-sample period except for the exponential GARCH model. During the out-of-sample period, the power ARCH model shows the largest annual trading profit of 38%. The volatility clustering and asymmetry found in this research are the reflection of volatility non-linearity. This further suggests that combining the asymmetric GARCH models and artificial neural networks can significantly enhance the performance of the suggested volatility trading system, since artificial neural networks have been shown to effectively model nonlinear relationships.

• Journal of Intelligence and Information Systems
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• v.26 no.3
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• pp.171-191
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• 2020

This study focused on digital music, which is the most valuable cultural asset in the modern society and occupies a particularly important position in the flow of the Korean Wave. Digital music was collected based on the "Gaon Chart," a well-established music chart in Korea. Through this, the changes in the ranking of the music that entered the chart for 73 weeks were collected. Afterwards, patterns with similar characteristics were derived through time series cluster analysis. Then, a descriptive analysis was performed on the notable features of each pattern. The research process suggested by this study is as follows. First, in the data collection process, time series data was collected to check the ranking change of digital music. Subsequently, in the data processing stage, the collected data was matched with the rankings over time, and the music title and artist name were processed. Each analysis is then sequentially performed in two stages consisting of exploratory analysis and explanatory analysis. First, the data collection period was limited to the period before 'the music bulk buying phenomenon', a reliability issue related to music ranking in Korea. Specifically, it is 73 weeks starting from December 31, 2017 to January 06, 2018 as the first week, and from May 19, 2019 to May 25, 2019. And the analysis targets were limited to digital music released in Korea. In particular, digital music was collected based on the "Gaon Chart", a well-known music chart in Korea. Unlike private music charts that are being serviced in Korea, Gaon Charts are charts approved by government agencies and have basic reliability. Therefore, it can be considered that it has more public confidence than the ranking information provided by other services. The contents of the collected data are as follows. Data on the period and ranking, the name of the music, the name of the artist, the name of the album, the Gaon index, the production company, and the distribution company were collected for the music that entered the top 100 on the music chart within the collection period. Through data collection, 7,300 music, which were included in the top 100 on the music chart, were identified for a total of 73 weeks. On the other hand, in the case of digital music, since the cases included in the music chart for more than two weeks are frequent, the duplication of music is removed through the pre-processing process. For duplicate music, the number and location of the duplicated music were checked through the duplicate check function, and then deleted to form data for analysis. Through this, a list of 742 unique music for analysis among the 7,300-music data in advance was secured. A total of 742 songs were secured through previous data collection and pre-processing. In addition, a total of 16 patterns were derived through time series cluster analysis on the ranking change. Based on the patterns derived after that, two representative patterns were identified: 'Steady Seller' and 'One-Hit Wonder'. Furthermore, the two patterns were subdivided into five patterns in consideration of the survival period of the music and the music ranking. The important characteristics of each pattern are as follows. First, the artist's superstar effect and bandwagon effect were strong in the one-hit wonder-type pattern. Therefore, when consumers choose a digital music, they are strongly influenced by the superstar effect and the bandwagon effect. Second, through the Steady Seller pattern, we confirmed the music that have been chosen by consumers for a very long time. In addition, we checked the patterns of the most selected music through consumer needs. Contrary to popular belief, the steady seller: mid-term pattern, not the one-hit wonder pattern, received the most choices from consumers. Particularly noteworthy is that the 'Climbing the Chart' phenomenon, which is contrary to the existing pattern, was confirmed through the steady-seller pattern. This study focuses on the change in the ranking of music over time, a field that has been relatively alienated centering on digital music. In addition, a new approach to music research was attempted by subdividing the pattern of ranking change rather than predicting the success and ranking of music.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2199-2206
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• 2014

This research, used an contrast agent, which weighs about 1mmol/mL, of twice as much amount of gadolinum, per unit, for the test of magnetic-resonance shoulder arthrography. the reasearch which was carried out from January, of the year 2012 to August of the year 2013. consisted, of target of 41, patients including 20 ones, of whom an original, contrast agent of amount of 0.5mmol/mL, 21, ones of whom, a new, of amount of 1mmol/mL was used on, were the test target, in order to figure out the differences, according to the amount of gadolinum, according to the test results, the SNR of the contrast agent, of amount of 1mmol/mL, which is of high amount of gadolinum, was noticeably higher than the one of amount of 0.5mmol/mL(the percentage of joint space 38.01%, the supraspinous muscle 8.40%, head of humerus 12.78%). and CNR of the contrast agent, of amount of 1mmol/mL, which is of high amount of gadolinum, was higher than the one of amount of 0.5mmol/mL(the percentage of joint space and supraspinous muscle 48.96%, the one of joint space and head of humerus 42.00%). In conclusion, one of the methods of increasing the reducing effect of T1, is to use contrast agent of amount of 1mmol/mL, in order to increase the reducing effect of T1, acquire the visual of high testing quality.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.6 no.1
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• pp.32-38
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• 2003

Purpose: Hepatic allografts from donors with hepatitis B core antibody have been demonstrated to transmit hepatitis B virus (HBV) infection to recipients after liver transplantation (LT). The efficacy of hepatitis B immune globulin (HBIg) to prevent de novo hepatitis B was investigated by comparing active immunization in the early phase to HBIg monotherapy in the late phase of pediatric liver transplants at Samsung Medical Center. Methods: Among pediatric liver transplants, from May, 1996 to June, 2002, 15 recipients who were hepatitis B surface antigen (HBsAg) (-) received an allograft from a donor with hepatitis B core antibody (HBcAb) (+). Except two who died from unrelated causes, eleven of 13 recipients were HBsAb (+), and 2 were naive (HBsAb(-), HBcAb(-)). All patients were vaccinated for HBV before LT. In the early phase (January, 1997~November, 1997, 3 patients), HBsAb (+) recipients received booster vaccination after LT. In the late phase (December, 1997~, 10 patients), all recipients were given booster vaccination and received HBIg therapy in order to maintain HBsAb titer greater than 200 IU/L. Lamivudine was given in one case because of severe side effect of HBIg. We retrospectively analyzed the effect of the preventive therapy for de novo hepatitis B through medical records. Results: De novo hepatitis B developed in three of 13 recipients (23.1%). All of 3 patients who received active immunization in the early phase became HBsAg (+) at 7~19 months after transplantation. One of them was naive before LT and the other two were HBsAb (+). All of 10 recipients who were given HBIg in the late phase remained HBsAg (-) at 7~55 months' follow-up. Conclusion: Passive immunization with HBIg was effective for prevention of de novo hepatitis B in HBsAg (-) recipients of hepatic allografts from HBcAb (+) donors.

• Korean journal of communication and information
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• v.17
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• pp.112-144
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• 2001

This study attempts to analyze how and why Chosun Ilbo and Hankyoreh Shinmun produce particular social discourses about the media reform in different ways. In doing so, this paper attempts to disclose the ideological nature of media reform discourses in social contexts. For the purpose, a content analysis method was applied to the analysis of straight news, while an interpretive discourse analysis was appled to analyze both editorials and columns in newspapers. As a theoretical framework, an articulation theory was applied to explain the relationships among social forces, ideological elements, discourse practices and subjects to produce the media reform discourses. In doing so, I attempted to understand the overall conjuncture of the media reform aspects in social contexts. The period for the analysis was limited from January 10th to August 10th this year. Newspaper articles related to the media reform were obtained from the database of newspaper articles, "KINDS," produced by Korean Press Foundation, in searching the key word, "media reform". Total articles to be analyzed were 765, 429 from Hankyoreh Sinmun and 236 from Chosun Ilbo. The research results, first of all, empirically show that both Chosun Ilbo and Hankure Synmun used straight news for their firms' interests and value judgement, in selecting and excluding events related to media reform or in exaggerating and reducing the meanings of the events, although there are differences in a greater or less degree between two newspaper companies. Accordingly, this paper argues that the monopoly of newspaper subscriber by three major newspapers in Korean society could result in the forming of one-sided social consensus about various social issues through the distorting and unequal reporting by them. Second, this paper's discourse analysis related to the media reform indicates that the discourse of ideology confrontation between the right and the left produced by Chosen Ilbo functioned as a mechanism to realize law enforcement of the right in articulating the request of media reform and the anti-communist ideology. It resulted in the discursive effect of suppressing the request of media reform by civic groups and scholars and made many people to consider the media reform as a ideological matter in Korean society.

• Neonatal Medicine
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• v.18 no.2
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• pp.320-327
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• 2011

Purpose: To determine the effect of changing practice guidelines designed to avoid hyperoxia or hypoxia in very low birth weight or very preterm infants. Methods: We analyzed a database of <1,500 g birth weight or <32 weeks of gestation infants who were born and admitted to the neonatal intensive care unit of Chungnam National University Hospital from January 2007 to July 2010. First, we defined the relationship between arterial partial pressure of oxygen ($PaO_2$) and pulse oxygen saturation ($SpO_2$). When we evaluated 96 pairs of $PaO_2$ and $SpO_2$ measurements, oxygen saturation was 90-94% at a $PaO_2$ of 43-79 mmHg on the oxyhemoglobin dissociation curve, according to pulse oximetry. Based on this observation, a change in practice was instituted in August 2008 with the objective of avoiding hypoxia and hyperoxia in preterm infants with targeting a $SpO_2$ 90-94% (period II). Before the change in practice, high alarms for $SpO_2$ were set at 100% and low alarms at 95% (period I). Results: Sixty-eight infants the met enrollment criteria and 38 (56%) were born during period II, after the change in $SpO_2$ targets. Demographic characteristics, except gender, were similar between the infants born in both periods. After correcting for the effect of confounding factors, the rates for mortality, severe retinopathy of prematurity, and IVH attended to be lower than those for infants in period II. No difference in the rate of patent ductus arteriosus needed to treat was observed. Conclusion: A change in the practice guidelines aimed at avoiding low oxygen saturation and hyperoxia did not increase neonatal complication rates and showed promising results, suggesting decreased mortality and improvements in short term morbidity. It is still unclear what range of oxygen saturation is appropriate for very preterm infants but the more careful saturation targeting guideline should be considered to prevent hypoxemic events and hyperoxia.

• Korean Journal of Animal Reproduction
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• v.22 no.4
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• pp.367-373
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• 1998

A survey was carried out to investigate the effect of the herd size on the reproductive traits of Hanwoo(Korean native cows). Data on the reproductive traits of 670 Korean native cows were collected from January, 1996 to December, 1997 and analyzed by the herd size. The results obtained were summarized as follows: 1. The average ages at first breeding were 437.9, 425.5 and 452.9 days in herd size 1 (less than 20 heads), 2 (21∼50 heads) and 3 (more than 51 heads), respectively (the over all average was 443.0 days). However, there was no significant difference between herd sizes (p＞0.05). 2. The average ages at first conception were 452.8, 438.4 and 467.1 days in herd size 1, 2 and 3, respectively (the over all average was 460.0 days). However, there was no significant difference between herd sizes (p＞0.05). 3. The average ages at first calving were 741.2, 730.2 and 755.9 days in herd size 1, 2 and 3, respectively (the over all average was 746.6 days). However, there was no significant difference between herd sizes (p＞0.05). 4. The average days to first estrus after calving was 70.1 days and it was shortest in herd size 3 (64.8 days) and longest in herd size 1(82.1 days). 5. The average numbers of services per conception were 1.54, 1.61 and 1.48 in herd size 1, 2, and 3, respectively (the over all average was 1.53). However, there was no significant difference between herd sizes (p＞0.05). 6. The average days to first conception after calving were 115.6, 99.1 and 80.6 days in herd size 1, 2 and 3, respectively (the over all average was 91.2 days). There was a trend that it was shorter as the herd size increased(p＜0.05). 7. The average length of calving interval was 375.3 days and it was shortest in herd size 3 (367. 4 days) and longest in herd size 1 (389.5 days).

• Clinical and Experimental Pediatrics
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• v.50 no.12
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• pp.1225-1230
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• 2007

Purpose : Multiple transfusions in patients with chronic anemia can result in excessive iron deposition in tissues and organs. Effective iron chelation therapy in chronically transfused patients can only be achieved when iron chelators remove sufficient amounts of iron equivalent to those accumulated in the body from transfusions, thus leading to maintain body iron load at a non-toxic level. This study was retrospectively carried out to investigate the effect of intravenous iron chelation therapy with deferoxamine in patients who have received multiple transfusions. Methods : From March 2005 to January 2007, 15 patients who have received multiple transfusions were included in this study. Transfusion dependent patients were defined as those receiving >1 packed red blood cell (RBC) units/month for at least 6 months. They received intravenous deferoxamine for 7 days (10-30 mg/kg/day, 24 hour continuous infusions). Before and after deferoxamine infusions and 3 months later, we compared serum iron, TIBC, and ferritin in transfusion dependent patients and transfusion independent patients. Results : There were 6 males and 9 females and their age range was 5.6-21.3 (median 8.3) years. Transfusion dependent patients were 7 and 8 were transfusion independent states after stem cell transplantation or chemotherapy. There was no significant change in ferritin level after deferoxamine treatment for the transfusion dependent patients but significant falling of ferritin level was observed for the transfusion independent patients 3 months later compared with baseline ferritin level (P=0.046). Some adverse events were observed but symptoms were mild and tolerable. Conclusion : Seven days of intravenous deferoxamine was safe and effective in transfusion independent patients. In transfusion dependent patients, chelation therapy should be maintained, in order to minimize or prevent iron accumulation and storage in the tissues.