• Clinical and Experimental Pediatrics
• /
• v.45 no.9
• /
• pp.1114-1119
• /
• 2002

Purpose : The purposes of this study were to determine short- and long-term fractal correlation behavior of heart rates during daily activity in patients with neurocardiogenic syncope. Methods : Twenty five patients with histories of neurocardiogenic syncope episodes were included. Their analogue 24h ambulatory Holter electrocardiograms were analyzed. The tape was digitized and the digitized electrocardiograms were partioned into sections of one hour. Then their RR intervals were measured and 20,000 points of RRI were used. To quantify the fractal correlation behavior, we employed the detrended fluctuation analysis, and short-term($n{\leq}16$, ${\alpha}_1$) and long-term(n>16, ${\alpha}_2$) fractal scaling exponents were calculated. Results : When compared to control, 24-hour average values of ${\alpha}_1$ and all ${\alpha}_1$ values at quarters of each day were significantly higher in patients with syncope. On the contrary, their 24-hour average value of ${\alpha}_2$ and all ${\alpha}_2$ values at quarters of each day were lower in patients with syncope. However, statistical significances were found in 24-hour average value of ${\alpha}_2$ and in ${\alpha}_2$ value at MN-6AM. Conclusion : In the syncope patients with neurocardiogenic syncope, short-term fractal scaling exponents of RR interval was significantly high throughout the day. Therefore, their RR intervals were smoother in the short term scale and had a tendency to continue in the same direction of increase or decrease, which may contribute to persistent decrease in heart rate during a syncopal attack.

• Investigative Magnetic Resonance Imaging
• /
• v.18 no.3
• /
• pp.193-199
• /
• 2014

Purpose : To evaluate the relationship between superior labral dimension of the glenohumeral joint on direct MRA and presence of SLAP lesion. Materials and Methods: IRB approval was obtained and informed consent was waived for this retrospective study. Direct MRA studies of the shoulder in 296 patients (300 shoulders) with arthroscopic surgery were analyzed by two radiologists blinded to the arthroscopic results, which were used as gold standard. One of the radiologists reviewed the images twice (session 1 and 2) for the evaluation of intra-observer variability. Transverse and longitudinal dimensions of superior labrum on coronal T1-weighted images were measured as base and height of the inverted triangular-shaped superior labrum and compared between patients with SLAP lesions vs. non-SLAP patients. Presence of meniscoid labrum was noted. Statistical analysis was done using unpaired t-test. Results: Among 279 patients (283 shoulders), 122 patients (43.1%) had SLAP lesions. The mean base/height of superior labrum in SLAP and non-SLAP patients measured on T1-weighted MR image were 8.8 mm / 5.2 mm, 8.5 mm / 4.9 mm for reader 1; 8.2 mm / 4.9 mm, 8.1 mm / 4.5 mm for session 1 of reader 2; 8.0 mm / 4.8 mm, 7.6 mm / 4.3 mm for session 2 of reader 2. In SLAP group, the mean labral height was larger than non-SLAP group with statistically significant difference (p<0.05). Fifteen patients (5.3%) had meniscoid labrum according to operation records. Conclusion: In patients with SLAP lesion, the height of the superior glenoid labrum on oblique coronal image of MRA was slightly larger than non-SLAP patients. A larger height of superior glenoid labrum may be associated with SLAP lesions.

• Investigative Magnetic Resonance Imaging
• /
• v.17 no.3
• /
• pp.192-199
• /
• 2013

Purpose : To retrospectively evaluate the diagnostic performance of dynamic contrast-enhanced MR imaging (DCE-MRI) in detecting recurrent prostate cancer after HIFU of clinically localized cancer, as compared with T2-weighted imaging (T2WI). Materials and Methods: Twenty-six patients with increased prostate-specific antigen levels after HIFU were included in this study. All MR examinations were performed using T2WI and DCE-MRI, followed by transrectal ultrasound-guided biopsy. MRI and biopsy results were correlated in six prostate sectors. Residual or recurrent cancer after HIFU was defined as local tumor progression if biopsy results showed any cancer foci. Two independent readers interpreted the MR images. Results: Of 156 prostate sectors, 51 (33%) were positive for cancer in 17 patients. For detecting local tumor progression, the sensitivity of DCE-MRI and T2WI was 80% and 57% for reader 1 (P < 0.001) versus 84% and 61% for reader 2 (P < 0.001), respectively. The specificity and overall accuracy between DCE-MRI and T2WI showed no statistical difference in both readers (P > 0.05). Interobserver agreement of DCE-MRI and T2WI was moderate and fair, respectively. Conclusion: For detecting local tumor progression of prostate cancer after HIFU, DCE-MRI was more sensitive than T2WI, with less interobserver variability.

• Journal of Intelligence and Information Systems
• /
• v.19 no.3
• /
• pp.73-91
• /
• 2013

Advertising market has been facing new challenges due to dramatic change in advertising channels and the advent of innovative media such as mobile devices. Recent research related to mobile devices is mainly focused on the fact that mobile devices could identify users'physical location in real-time, and this sheds light on how location-based technology is utilized to achieve competitive advantage in advertising market. With the introduction of smartphone, the functionality of smartphone has become much more diverse and context awareness is one of the areas that require further study. This work analyses the influence of context awareness value resulted from the transformation of advertising channel in mobile communication market, and our research result reflects recent trend in advertising market environment which is not considered in previous studies. Many constructs has intensively been studied in the context of advertising channel in traditional marketing environment, and entertainment, irritation and information are considered to be the most widely accepted variables that has positive relationship with advertising value. Also, in smartphone advertisement, four main dimensions of context awareness value are recognized: identification, activity, timing and location. In this study, we assume that these four constructs has positive relationship with context awareness value. Finally, we propose that advertising value and context awareness value positively influence smartphone advertising attitude. Partial Least Squares (PLS) structural model is used in our theoretical research model to test proposed hypotheses. A well designed survey is conducted for college students in Korea, and reliability, convergent validity and discriminant validity of constructs and measurement indicators are carefully evaluated and the results show that reliability and validity are confirmed according to predefined statistical criteria. Goodness-of-fit of our research model is also supported. In summary, the results collectively suggest good measurement properties for the proposed research model. The research outcomes are as follows. First, information has positive impact on advertising value while entertainment and irritation have no significant impact. Information, entertainment and irritation together account for 38.8% of advertising value. Second, along with the change in advertising market due to the advent of smartphone, activity, timing and location have positive impact on context awareness value while identification has no significant impact. In addition, identification, activity, location and time together account for 46.3% of context awareness value. Third, advertising value and context awareness value both positively influence smartphone advertising attitude, and these two constructs explain 31.7% of the variability of smartphone advertising attitude. The theoretical implication of our research is as follows. First, the influence of entertainment and irritation is reduced which are known to be crucial factors according to previous studies related to advertising value, while the influence of information is increased. It indicates that smartphone users are not likely interested in entertaining effect of smartphone advertisement, and are insensitive to the inconvenience due to smartphone advertisement. Second, in today' ubiquitous computing environment, it is effective to provide differentiated advertising service by utilizing smartphone users'context awareness values such as identification, activity, timing and location in order to achieve competitive business advantage in advertising market. For practical implications, enterprises should provide valuable and useful information that might attract smartphone users by adopting differentiation strategy as smartphone users are sensitive to the information provided via smartphone. Also enterprises not only provide useful information but also recognize and utilize smarphone users' unique characteristics and behaviors by increasing context awareness values. In summary, our result implies that smartphone advertisement should be optimized by considering the needed information of smartphone users in order to maximize advertisement effect.

• Journal of the Korean earth science society
• /
• v.42 no.5
• /
• pp.524-535
• /
• 2021

Rapid climate change and oceanic warming have increased the variability of oceanic wave heights over the past several decades. In addition, the extreme wave heights, such as the upper 1% (or 5%) wave heights, have increased more than the heights of the normal waves. This is true for waves both in global oceans as well as in local seas. Satellite altimeters have consistently observed significant wave heights (SWHs) since 1991, and sufficient SWH data have been accumulated to investigate 100-year return period SWH values based on statistical approaches. Satellite altimeter data were used to estimate the extreme SWHs at the Ieodo Ocean Research Station (IORS) for the period from 2005 to 2016. Two representative extreme value analysis (EVA) methods, the Initial Distribution Method (IDM) and Peak over Threshold (PoT) analysis, were applied for SWH measurements from satellite altimeter data and compared with the in situ measurements observed at the IORS. The 100-year return period SWH values estimated by IDM and PoT analysis using IORS measurements were 8.17 and 14.11 m, respectively, and those using satellite altimeter data were 9.21 and 16.49 m, respectively. When compared with the maximum value, the IDM method tended to underestimate the extreme SWH. This result suggests that the extreme SWHs could be reasonably estimated by the PoT method better than by the IDM method. The superiority of the PoT method was supported by the results of the in situ measurements at the IORS, which is affected by typhoons with extreme SWH events. It was also confirmed that the stability of the extreme SWH estimated using the PoT method may decline with a decrease in the quantity of the altimeter data used. Furthermore, this study discusses potential limitations in estimating extreme SWHs using satellite altimeter data, and emphasizes the importance of SWH measurements from the IORS as reference data in the East China Sea to verify satellite altimeter data.

• Journal of Venture Innovation
• /
• v.5 no.3
• /
• pp.71-80
• /
• 2022

The real estate market is an important part of a country's economy and plays a major role in economic growth through the growth of many related industries. Changes in interest rates affect asset prices and have a significant impact on housing prices. This study analyzed housing prices by dividing them into nationwide, local, and Seoul housing prices in order to analyze whether the effect of changes in interest rates on housing prices shows regional differences. The analysis was conducted from the first quarter of 2011 to the fourth quarter of 2021, and was analyzed using the DOLS model. The main analysis results are as follows. First, interest rates were found to have a significant negative effect on national housing prices, and a drop in interest rates significantly increased national housing prices and an increase in interest rates significantly lowered national housing prices. The consumer price index and loan growth rate also had a positive effect on housing prices nationwide, but statistical significance was not high. Second, interest rates had a negative effect on local housing prices, unlike national housing prices, but were not statistically significant. On the other hand, it was found that the consumer price index and loan growth rate had a larger and significant positive effect on local housing prices compared to national housing prices. Finally, it was found that the interest rate had the only significant negative effect on housing prices in Seoul. And this effect was greater and more significant than the effect on national and local housing prices. In the end, it was found that the effect of interest rates on Korean housing prices differs locally. Interest rates have a significant negative effect on national housing prices, and local housing prices, but they are not statistically significant. In addition, the interest rate was found to have the largest and most significant negative effect on housing prices in Seoul. In addition, it was found that there was a difference in the effect of macroeconomic variables on housing prices. This means that there are differences between regions with different factors influencing local and Seoul housing prices, and this point should be considered when drafting and implementing real estate policies.

• Horticultural Science & Technology
• /
• v.34 no.2
• /
• pp.269-281
• /
• 2016

The statistical analyses of coefficient of variation, heritability, and genetic advance were carried out to identify differences in morphological characteristics, such as the stem and inflorescence length, of 10 major commercial cultivars of spray chrysanthemum (Chrysanthemum morifolium). For morphological characteristics, stem lengths ranged from 46.4 cm to 54.9 cm, the maximum diameter of stem was 5.6 to 8.5 mm, the hardness of the stem was 0.17 to $0.70kg{\cdot}m^{-2}$, the fresh weight of stem was 7.5 to 17.5 g, the dry weight of the stem was 1.6 to 3.3 g, the ratio of dry weight/fresh weight of stem was 15.9% to 23.1%. Also, the number of leaves on the stem was 8.4 to 12.2, the stem leaf area was 17.8 to $37.8m^2$, the fresh weight stem leaves was 5.3 to 18.6 g, the dry weight was 0.5 to 1.4 g and the ratio of dry weight /fresh weight of stem leaves was 7.6% to 11.5%. The inflorescence length ranged from 10.1 to 18.6 cm, the fresh weight of inflorescence was 7.3 to 26.7 g, the dry weight of inflorescence was 1.2 to 2.8 g, the ratio of dry weight /fresh weight of inflorescence was 10.4% to 17.1%. For flower, the diameter of the flower center was 8.2 to 13.3 mm, the petal width was 5.7 to 14.0 mm, the petal length was 12.9 to 33.1 mm, and the petal thickness was 157.8 to $354.4{\mu}m$. The mean values of each character in each cultivar were very different, and DMRT and LSD values based on morphological characteristics among 10 cultivars were highly significant. For variability and genetic parameters, the lowest CV (coefficient of variation), PCV (phenotypic coefficient of variation), and GCV (genotypic coefficient of variation) were 4.79% to 5.15% in stem length, and the highest variations were 62.97% to 65.21% in leaf area. ECV (error or environmental coefficient of variation) was the lowest for leaf area (1.71%) and it was the highest for leaf dry weight (19.30%). Heritability also significantly differed among the characteristics, ranging from 68.69% to 99.67%, the lowest value was shown in ratio of dry weight /fresh weight of stem and the highest value was for leaf area of stem. The value for genetic advance was the lowest in hardness of stem at 0.30 and the highest in leaf thickness at 156.65. The lowest genetic advance as percentage of mean of stem hardness was 9.17%, while the highest percentage of stem length was 134.27%. Thus the characters which had the highest values indicated above show the influence of additive gene action and may provide useful resources for selection programs for agronomic improvement.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.24 no.2
• /
• pp.267-281
• /
• 2019

Energetic mesoscale eddies in the East Sea (ES) associated with strong mesoscale variability impacting circulation and environments were statistically characterized by analyzing satellite altimeter data collected during 1993-2017 and in-situ data obtained from four cruises conducted between 2015 and 2017. A total of 1,008 mesoscale eddies were detected, tracked, and identified and then classified into 27 groups characterized by mean lifetime (L, day), amplitude (H, m), radius (R, km), intensity per unit area (EI, $cm^2/s^2/km^2$), ellipticity (e), eddy kinetic energy (EKE, TJ), available potential energy (APE, TJ), and direction of movement. The center, boundary, and amplitude of mesoscale eddies identified from satellite altimeter data were compared to those from the in-situ observational data for the four cases, yielding uncertainties in the center position of 2-10 km, boundary position of 10-20 km, and amplitude of 0.6-5.9 cm. The mean L, H, R, EI, e, EKE, and APE of the ES mesoscale eddies during the total period are $95{\pm}104$ days, $3.5{\pm}1.5cm$, $39{\pm}6km$, $0.023{\pm}0.017cm^2/s^2/km^2$, $0.72{\pm}0.07$, $23{\pm}21TJ$, and $588{\pm}250TJ$, respectively. The ES mesoscale eddies tend to move following the mean surface current rather than propagating westward. The southern groups (south of the subpolar front) have a longer L, larger H, R, and higher EKE, APE; and stronger EI than those of the northern groups and tend to move a longer distance following surface currents. There are exceptions to the average characteristics, such as the quasi-stationary groups (the Wonsan Warm, Wonsan Cold, Western Japan Basin Warm, and Northern Subpolar Frontal Cold Eddy groups) and short-lived groups with a relatively larger H, higher EKE, and APE and stronger EI (the Yamato Coastal Warm, Central Yamato Warm, and Eastern Japan Basin Coastal Warm eddy groups). Small eddies in the northern ES hardly resolved using the satellite altimetry data only, were not identified here and discussed with potential over-estimations of the mean L, H, R, EI, EKE, and APE. This study suggests that the ES mesoscale eddies 1) include newly identified groups such as the Hokkaido and the Yamato Rise Warm Eddies in addition to relatively well-known groups (e.g., the Ulleung Warm and the Dok Cold Eddies); 2) have a shorter L; smaller H, R, and lower EKE; and stronger EI and higher APE than those of the global ocean, and move following surface currents rather than propagating westward; and 3) show large spatial inhomogeneity among groups.