• Korean Business Review
• /
• v.21 no.2
• /
• pp.1-16
• /
• 2008

This paper investigate the volume-volatility and volume-return relationship in the Korean Treasury Bond futures market using daily price and volume data categorized by three trader type i.e. individual investor, institutional investor and foreign investor over the period of October 1999 through December 2005. Major results are summarized as follows: (i) The effect of volume on return was not different across the trader type. (ii) The effect of volume on volatility was not unidirectional across the type of investor. While unexpected sell of individual investor has positive effects on volatility, negative effects in the case of institutional investor. (iii) We cannot find the evidence of asymmetric response of volatility to shock in trading volume or net position. This result differs from that of Korean Stock Price Index 200 futures market which showed strong positive asymmetry. Finally, some limitations of this paper and direction for further research were suggested.

• Journal of Acupuncture Research
• /
• v.27 no.6
• /
• pp.43-57
• /
• 2010

Objectives : To investigate the effects of electroacupuncture on parameters related to obesity in adults with abdominal obesity. Methods : A three arm randomized single blind pilot study was conducted from Jan 4 to March 25, 2010 in Kyung Hee Oriental Medical Hospital. The subjects were 39 adults with abdominal obesity and were randomly divided by computer generated random table into 3 groups; EA(electroacupuncture), sham EA(sham electroacupuncture) and waitlist groups. Acupuncture points located at abdomen($CV_{12}$, $CV_6$, $ST_{25}$, $SP_{15}$, $SP_{14}$) and extremities($LI_4$, $LI_{11}$, $ST_{36}$, $ST_{44}$) were inserted by disposable stainless steel needles and were stimulated 30 minutes with 24Hz, 0.27~1.3mA(tolerable strength), asymmetric biphasic continuous pulse wave form by STN-111 Stratek device in EA group. Two treatment sessions per week for 5 weeks(10 sessions in total) were done in EA and sham EA groups. The primary outcome measurement was WC(waist circumference), and the secondary outcome measurements included WHR(waist hip ratio), ASF(thickness of abdominal subcutaneous fat), and inbody measurements of BW(body weight), BMI(body mass index), BFR(body fat ratio) and VFA(visceral fat area), and also scores of BULIT-R(bulimia test revised), KoQoL(Korean obesity of QoL) and BSQ(body shape questionnaire). Results : All of 39 subjects were included in ITT(intention-to-treat) analysis. There were significant reductions in WC, WHR and ASF after 5-week electroacupuncture treatments and the percentage reductions were significantly greater than sham EA or waitlist group. There were no significant differences between groups in percentage reductions of other parameters(BW, BMI, BFR, VFA, BULIT-R, KoQoL and BSQ). But, there were continuous reductions in BW, BMI, BFR and VFA at 3 weeks after the end of treatment and there was significant reduction in BW compared with the baseline value in EA group. No seriously adverse effects were reported during the period. Conclusions : Electroacupuncture was more effective than sham electroacupuncture or no intervention on the reduction of WC, WHR and ASF in adults with abdominal obesity.

• Journal of Oral Medicine and Pain
• /
• v.15 no.1
• /
• pp.27-35
• /
• 1991

In order to evaluate muscular activity patterns of masticatory muscles and asymmetry patterns of muscular activity according to the levels of occlusal force, twenty-one individuals of age ranged from 23 to 27 years were examined. They were selected according to the following criteria : 1) no symptoms of temporomandibular disorder, 2) complete dentition except third molars, 3) normal or Angle's class I molar relationship and 4) no experience of dental treatment. The electromyographic amplitudes was measured for evaluation of muscular activity and asymmetric patterns of masseter and anterior temporal muscle during unilateral clenching at the levels of 10%, 20%, 40% and 50% of the maximum occlusal force by use of electromyogram and bite force meter. The obtained results were as follows : 1. The muscle activity indices of masticatory muscles of clenching side at the clenching levels of 10%, 20% and 30% of the maximum occlusal force were -19.12, -9.87, -0.49%, so that activity of anterior temporal muscle was dominant than that of masseter muscle. At the levels of 40%, 50% of the maximum occlusal force, muscle activity indices were 4.68%, 6.70%, so that activity of masseter was dominant at all level and as the levels of occlusal force was increased, muscular activity index was tend to decrease. 2. In masseter, asymmetry indices of muscular activity at the levels of 10%, 20% of maximum occlusal force were -10.34 and -1.24%, so that muscular activity of non-clenching side were dominant and at the levels of 30%, 40% and 50% each of maximum occlusal force, muscular activity was dominant on clenching side as 4.68, 7.18 and 10.9%. In anterior temporal muscle, asymmetry indices were 33.38%, 25.46, 2095, 10.23 and 15.45% at the levels of 10%, 20%, 30%, 40% and 50% each of maximum occlusal force, so that activity of clenching 15.45% at the levels of 10%, 20%, 30%, 40% and 50% each of maximum occlusal force, so that activity of clenching side was dominant than that of non-clenching side at all levels, but as the levels of occlusal force was increased, asymmetry indices of muscular activity was tend to decrease. 3. Between both sides, average electromyographic amplitudes of masseter and anterior temporal muscle were correlated, so that as the levels of occlusal force was increased, average electromyographic amplitudes of both side in same muscle were increased proportionally. But asymmetry indices between muscular activities of masseter and anterior temporal muscle were not correlated.

• The Korean Journal of Financial Management
• /
• v.26 no.4
• /
• pp.191-234
• /
• 2009

This study examined on the volatility feedback hypothesis through the use of threshold GARCH-in-Mean (GJR-GARCH-M) model developed by Glosten, Jaganathan, and Runkle (1993) in the stock markets of 14 emerging countries during the period of January, 1996 to May, 2009. On this study, I found successful evidences which can support the volatility feedback hypothesis through the following three estimation procedures. First, I found relatively strong positive relationship between the expected market risk premiums and their conditional standard deviations from the GARCH-M model in the basis of daily return on each representative stock market index, which is appropriate to investors' risk-averse preferences. Second, I can also identify the significant asymmetric time-varying volatility originated from the investors' differentiated reactions toward the unexpected market shocks by applying the GJR-GARCH-M model and further find the lasting positive risk aversion coefficient estimators. Third, I derived the negative signs of the regression coefficient of unpredicted volatility on the stock market return by re-applying the GJR-GARCH-M model after I controlled the positive effect of predicted volatility through including the conditional standard deviations from the previous GARCH-M model estimation as an independent explanatory variable in the re-applied new GJR-GARCH-M model. With these consecutive results, the volatility feedback effect was successfully tested to be effective also in the various emerging stock markets, although the leverage hypothesis turned out to be insufficient to be applied to another source of explaining the negative relationship between the unexpected volatility and the ex-post stock market return in the emerging countries in general.

• The KIPS Transactions:PartD
• /
• v.15D no.6
• /
• pp.755-766
• /
• 2008

Recently, NAND flash memory is becoming into the spotlight as a next-generation storage device because of its small size, fast speed, low power consumption, and etc. compared to the hard disk. However, due to the distinct characteristics such as erase-before-write architecture, asymmetric operation speed and unit, disk-based systems and applications may result in severe performance degradation when directly implementing them on NAND flash memory. Especially when a B-tree is implemented on NAND flash memory, intensive overwrite operations may be caused by record inserting, deleting, and reorganizing. These may result in severe performance degradation. Although ${\mu}$-tree has been proposed in order to overcome this problem, it suffers from frequent node split and rapid increment of its height. In this paper, we propose Log-Structured B-Tree(LSB-Tree) where the corresponding log node to a leaf node is allocated for update operation and then the modified data in the log node is stored at only one write operation. LSB-tree reduces additional write operations by deferring the change of parent nodes. Also, it reduces the write operation by switching a log node to a new leaf node when inserting the data sequentially by the key order. Finally, we show that LSB-tree yields a better performance on NAND flash memory by comparing it to ${\mu}$-tree through various experiments.

• International Area Studies Review
• /
• v.14 no.1
• /
• pp.55-76
• /
• 2010

This paper analyses interaction between yen/dollar exchange rates and NIKKEI index using bivariate GJR-GARCH(1,1) model. The data employed for the study is daily data series for the period of Jan. 4, 1995 through Aug. 30, 2009. One of main findings is that market inefficiency appears in the periods of financial crisis. Second, the volatility of exchange rates and stock returns has more increased in the wake of the volatility shock of the previous period during financial crisis than during non-financial crisis. Third, interestingly, the asymmetric volatility shock by bad news in those markets is bigger in financial crisis period than in non financial crisis. Fourth, in the period of current global financial crisis triggered by subprime mortgage crisis in U.S, volatility shock at the previous period is bigger than that of Asian financial crisis that happened in 1997. Lastly, the correlation between both returns of exchange rates and stock prices turns up positive according to the empirical estimation. This result may come from the fact that Japanese stock market does not have much attraction for international financial investment compared to stock markets of neighbouring countries like China, Korea and so on, while real sector's contribution to the economy is considered more importantly.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.29 no.4
• /
• pp.173-178
• /
• 2019

In this study, we demonstrated a characterization of ${\alpha}-Ga_2O_3$ grown on a cone-shape patterned sapphire substrate by using the halide vapor phase epitaxy. An ${\alpha}-Ga_2O_3$ was grown on different size of PSS and c-plane sapphire substrate for comparison to confirm the effect of PSS. In addition, growth time of ${\alpha}-Ga_2O_3$ was gradually increased to confirm growth mechanism of ${\alpha}-Ga_2O_3$ grown on the PSS. A growth temperature was changed to $470-550^{\circ}C$. It can be analyzed growth conditions and mechanisms on the cone-shape PSS, resulting in a significant decrease in the FWHM value of an asymmetric plane (10-14) of ${\alpha}-Ga_2O_3$, due to lateral growth that occurs during the growth process.

• Yonsei Medical Journal
• /
• v.59 no.9
• /
• pp.1138-1142
• /
• 2018

This study aimed to analyze the impact of sleep deprivation (SD) on cardiac, hemodynamic, and endothelial parameters and to determine whether these are sustained with increased periods of SD. The study included 60 healthy men (mean: age $31.2{\pm}6.3years$; body mass index $24.6{\pm}2.6kg/m^2$). Hemodynamic parameters, parameters of myocardial contractility, spectral analysis of heart rate (HR) and blood pressure (BP) variability, and the sensitivity of arterial baroreflex function were evaluated. Biochemical tests were performed to assess L-arginine (L-Arg) and asymmetric dimethylarginine (ADMA) levels in reflection of endothelial nitric oxide synthase ability. Measurements of cardiovascular system parameters were obtained at 9 a.m. (baseline) on the first day of the study and 9 a.m. (24-h SD), 1 p.m. (28-h SD), and 5 p.m. (32-h SD) on the second day. Blood samples for evaluating biochemical parameters were obtained at baseline and after 24-h SD. ANOVA Friedman's test revealed a significant effect for time in relation to HR (${\chi}^2=26.04$, df=5, p=0.000), systolic BP (${\chi}^2=35.98$, df=5, p=0.000), diastolic BP (${\chi}^2=18.01$, df=5, p=0.003), and mean BP (${\chi}^2=28.32$, df=5, p=0.000). L-Arg and ADMA levels changed from $78.2{\pm}12.9$ and $0.3{\pm}0.1$ at baseline to $68.8{\pm}10.2$ and $0.4{\pm}0.1$ after 24-hr SD, respectively (p=0.001, p=0.004). SD in healthy men is associated with increases in BP, which appear to occur after 24 hours of SD and are maintained over increasing periods of SD. The observed hemodynamic changes may have resulted due to disordered vascular endothelial function, as reflected in alterations in L-Arg and ADMA levels.

• Journal of Korea Port Economic Association
• /
• v.39 no.1
• /
• pp.115-129
• /
• 2023

This study analyzed the risk spillover of BDI on shipping company stock prices through the Copula-CoVaR method based on daily data from January 4, 2010, to October 31, 2022. The main empirical analysis results and policy implications are as follows. First, copula results showed that there was a weak dependence between BDI and shipping company stock prices, and PAN, KOR, and YEN were selected as the most fitting model for dynamic Student-t copula, HMM was selected as the rotated Gumbel copula, and KSS was selected as the best model. Second, in the results of CoVaR, it was confirmed that the upside (downside) CoVaR was significantly different from the upside (downside) VaR in all shipping companies. This means that BDI has a significant risk spillover on shipping companies. In addition, as for the risk spillover, the downside risk is generally lower than the upside risk, so the downside and upside risk spillover were found to be asymmetrical. Therefore, policymakers should strengthen external risk supervision and establish differentiated policies suitable for domestic conditions to prevent systematic risks from BDI shocks. And investors should reflect external risks from BDI fluctuations in their investment decisions and construct optimal investment portfolios to avoid risks. On the other hand, investors propose that the investment portfolio should be adjusted in consideration of the asymmetric characteristics of up and down risks when making investment decisions.

• Science of Emotion and Sensibility
• /
• v.8 no.1
• /
• pp.47-54
• /
• 2005

This study is aimed to inspect how the different sensitivities in Behavioral activation system(BAS) and behavioral inhibition system(BIS) modulate on the properties of physiological responses stimulated by positive or negative affective sound. We measured the electroencephalogram(EEG) and electrocardiogram (ECG) of 32 students, consisted of four groups depending on the BAS and BIS sensitivities, during listening to meditation music or noise. The EEG was recorded at Fpl and Fp2 sites and Power spectral density(PSD) of HRV was derived from the ECG, and the power of HRV was calculated for 3 major frequency ranges(low frequency[LF], medium frequency and high frequency[HF]). After listening to music or noise, subjects reported the affect induced by the sound. For EEG, the power in the alpha band at Fp2, especially in the alpha-2 band(9.0-11.0 Hz) increased during the subjects listening to music, while the power at Fpl increased during noise. During listening to meditation music, there is a tendency that the left-sided activation in prefrontal cortex(PFC) is positively correlated with the difference of BAS(Z)-BIS(Z). During listening to noise, there is a tendency that the right-sided activation in PFC is dominant in case any of the sensitivity of BAS or BIS is high. For HRV, we found that the index of MF/(LF+HF), during listening to music, was higher significantly in the individuals with a low BIS but high BAS than in the individuals with a low sensitivity both BIS and BAS individuals. With high BIS, regardless of the BAS sensitivity, the difference of this index values was not significant. From these results we suggest that the physiological responses of different individuals in BAS and BIS react differently under the same emotionally provocative challenge.