• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.25-33
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• 2021

Purpose : The purpose of this study is to evaluate the accuracy and usefulness of the Trigger mode for the Respiratory Gated Radiation Therapy (RGRT) Materials and methods : A QUASAR respiratory phantom that inserted a 3 mm fiducial marker (a gold marker) was used to estimate the accuracy of the Trigger mode. And the 20 bpm was used as reference respiration rate in this study. The marker that placed at the center of the phantom was contoured, and the lower threshold of a gating window was fixed at 2.0 mm using an OBI with Truebeam STx^TM. The upper threshold was measured every 0.5 mm from 1.0 mm to 3.0 mm. The respiration rates were changed every 10 bpm from 10 bpm to 60 bpm. We repeatedly measured five times to check the error rate of the trigger mode in the same condition. Result : The differences of a distance from a peak phase to upper threshold, 1.0 to 3.0 mm at a 20 bpm as a reference for 3 days in a row were 0.68±0.05 mm, 0.91±0.03 mm, 1.23±0.03 mm, 1.42±0.04 mm, and 1.66±0.06 mm, respectively. Measurement result of changes in respiratory rate compared to baseline respiratory rate in maximum absolute difference. The coefficient of determination (R2) to estimate the correlation between the respiration velocity and variation of absolute difference was on average 0.838, 0.887, 0.770, 0.850, and 0.906. The p-values of all the variables were below 0.05. Conclusion : Using Trigger mode during respiratory gated radiation therapy (RGRT), accuracy and usefulness of trigger mode at reference breathing rate were confirmed. However, inaccuracies depending on the rate of breathing it could be uncertain in case of respiration rate is faster than 20 bpm as a standard respiration rate compared to slower than 20 bpm. Consequently, when conducting a RGRT using the trigger mode, real time monitoring is required with well educated respiration.

• Journal of Intelligence and Information Systems
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• v.23 no.2
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• pp.107-122
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• 2017

Volatility in the stock market returns is a measure of investment risk. It plays a central role in portfolio optimization, asset pricing and risk management as well as most theoretical financial models. Engle(1982) presented a pioneering paper on the stock market volatility that explains the time-variant characteristics embedded in the stock market return volatility. His model, Autoregressive Conditional Heteroscedasticity (ARCH), was generalized by Bollerslev(1986) as GARCH models. Empirical studies have shown that GARCH models describes well the fat-tailed return distributions and volatility clustering phenomenon appearing in stock prices. The parameters of the GARCH models are generally estimated by the maximum likelihood estimation (MLE) based on the standard normal density. But, since 1987 Black Monday, the stock market prices have become very complex and shown a lot of noisy terms. Recent studies start to apply artificial intelligent approach in estimating the GARCH parameters as a substitute for the MLE. The paper presents SVR-based GARCH process and compares with MLE-based GARCH process to estimate the parameters of GARCH models which are known to well forecast stock market volatility. Kernel functions used in SVR estimation process are linear, polynomial and radial. We analyzed the suggested models with KOSPI 200 Index. This index is constituted by 200 blue chip stocks listed in the Korea Exchange. We sampled KOSPI 200 daily closing values from 2010 to 2015. Sample observations are 1487 days. We used 1187 days to train the suggested GARCH models and the remaining 300 days were used as testing data. First, symmetric and asymmetric GARCH models are estimated by MLE. We forecasted KOSPI 200 Index return volatility and the statistical metric MSE shows better results for the asymmetric GARCH models such as E-GARCH or GJR-GARCH. This is consistent with the documented non-normal return distribution characteristics with fat-tail and leptokurtosis. Compared with MLE estimation process, SVR-based GARCH models outperform the MLE methodology in KOSPI 200 Index return volatility forecasting. Polynomial kernel function shows exceptionally lower forecasting accuracy. We suggested Intelligent Volatility Trading System (IVTS) that utilizes the forecasted volatility results. IVTS entry rules are as follows. If forecasted tomorrow volatility will increase then buy volatility today. If forecasted tomorrow volatility will decrease then sell volatility today. If forecasted volatility direction does not change we hold the existing buy or sell positions. IVTS is assumed to buy and sell historical volatility values. This is somewhat unreal because we cannot trade historical volatility values themselves. But our simulation results are meaningful since the Korea Exchange introduced volatility futures contract that traders can trade since November 2014. The trading systems with SVR-based GARCH models show higher returns than MLE-based GARCH in the testing period. And trading profitable percentages of MLE-based GARCH IVTS models range from 47.5% to 50.0%, trading profitable percentages of SVR-based GARCH IVTS models range from 51.8% to 59.7%. MLE-based symmetric S-GARCH shows +150.2% return and SVR-based symmetric S-GARCH shows +526.4% return. MLE-based asymmetric E-GARCH shows -72% return and SVR-based asymmetric E-GARCH shows +245.6% return. MLE-based asymmetric GJR-GARCH shows -98.7% return and SVR-based asymmetric GJR-GARCH shows +126.3% return. Linear kernel function shows higher trading returns than radial kernel function. Best performance of SVR-based IVTS is +526.4% and that of MLE-based IVTS is +150.2%. SVR-based GARCH IVTS shows higher trading frequency. This study has some limitations. Our models are solely based on SVR. Other artificial intelligence models are needed to search for better performance. We do not consider costs incurred in the trading process including brokerage commissions and slippage costs. IVTS trading performance is unreal since we use historical volatility values as trading objects. The exact forecasting of stock market volatility is essential in the real trading as well as asset pricing models. Further studies on other machine learning-based GARCH models can give better information for the stock market investors.

• Korean Journal of Hospice Care
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• v.8 no.1
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• pp.1-12
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• 2008

Perpose: The purpose of this study was to investigate the perception of death between Korean and Chinese nursing students. And it will help develop curriculum for preparing death, the quality of hospice care, as well as nursing education and practice. Methods: Data was collected from 492 nursing students participated(248 Korean and 244 Chinese) by questionnaire designed for examining Death Orientation (Thorson & Powell, 1988). They were analyzed using Cronbach's Alpha coefficients, factor analysis, t-test, ANOVA and regression analysis (SPSS; win 12.0 version) Results: More than half of the Korean nursing students followed a religion (58.5%) while the majority of Chinese nursing students did not follow a religion (93.9%). In the view of the afterlife, nursing students in China had two views. 'I really don't know what happens after a person dies (30.3%)' and ‘There is no afterlife and death is the end (29.5%)’. On the other hand the Korean nursing students’ answer were, 'After dying, a person goes to heaven or hell (27.3%)' and 'I really don't know what happens after a person dies. (22.9%)' The study also found that the average of 25 items in Death Orientation is 2.36points of nursing students in Korea and 2.50points of nursing students in China. This means that the concern, anxiety and fear were of the middle level for the Chinese Students and were higher than Korean students (t=3.51, p=.000). In the low factor of death orientation, those in Korea had higher 'anxiety of burden to family' than those in China (t=-3.50, p=.001). The nursing students in China had higher 'anxiety of the unknown (t=4.96, p=.000)', 'fear of suffering (t=6.88, p=.000), 'fear of extinction body and life (t=5.20, p=.000), 'fear of lost self-control(t=2.12, p=.034)', and 'anxiety of future existence and nonexistence (t=2.33, p=.020)' than those in Korea. There was no statistically significant difference for the 'concern of body and fear of identity lost' category. The death orientation of Korean nursing students had statistically significant differences according to age (t=3.20, p=.002), religion (t=2.56, p=.011), and afterlife (F=4.64, p=.000). The contribution of Death Orientation had a statistically significant difference, the afterlife variable (0.735, p=0.001). The death orientation of Chinese nursing students did not have any statistically significant differences. Conclusion: In conclusion, there were differences in death orientation between Korean and Chinese nursing students. In particular, those who believed in afterlife showed acceptance of death. The results of this study suggest that nursing curricula should include education program on death and spiritual nursing. Additional studies are needed to establish death education in China with careful considerations on Chinese policies, cultures and social systems.

• Explosives and Blasting
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• v.9 no.1
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• pp.3-13
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• 1991

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill ${\phi}70mm$ on the calcalious sand stone (soft -modelate -semi hard Rock). The total numbers of test blast were 88. Scale distance were induced 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ were V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W : Maximum charge per delay-period of eight milliseconds or more (kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents where the quantity $\frac{D}{W^b}$ is known as the scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagorized in three groups. Cubic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge Per delay Plots of peak particle velocity versus distoance were made on log-log coordinates. The data are grouped by test and P.P.V. The linear grouping of the data permits their representation by an equation of the form ; $V=K(\frac{D}{W^{\frac{1}{3}})^{-n}$ The value of K(41 or 124) and n(1.41 or 1.66) were determined for each set of data by the method of least squores. Statistical tests showed that a common slope, n, could be used for all data of a given components. Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m ------- under l00m ${\cdots\cdots\cdots}{\;}41(D/sqrt[2]{W})^{-1.41}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}A$ Over 100m ${\cdots\cdots\cdots\cdots\cdots}{\;}121(D/sqrt[3]{W})^{-1.66}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}B$ where ; V is peak particle velocity In cm / sec D is distance in m and W, maximLlm charge weight per day in kg K value on the above equation has to be more specified for further understaring about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5254-5260
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• 2012

The purpose of this study is to find the relationship between lumber Herniated Nuclesus Pulposus of specific part and fat infiltration in paraspinal muscle. Also we intended to find the relationship between Body Mass Index(BMI) and fat infiltration ratio in the lumber paraspinal muscle based on the sexes of patients. We conducted this study of patients who visited our hospital from May, 2010 to May, 2012. The subjects are composed of 40 patients(20 females and 20 males), who are 30 to 50 years old suffering from severe lumber herniated nuclesus pulposus, who had or were going to have operation treatment. BMI is measured through anthropometry of each patient and fat infiltration inside the muscle is estimated by measuring the cross section area of lumbar paraspinal muscle from mid-cross section of disc(L2-S1) and fat infiltration ratio. The data of this study are analyzed by independent t-test to figure out the difference of fat infiltration between male and female, and by paired sample T-test after getting mean and standard deviation to find the changes of fat infiltration of lumbar on each level. Also correlation analysis is done by setting age as a control variable to find the correlation between BMI and fat infiltration of the whole lumbar. As a result, we could get only the meaningful difference between the sexes on upper lumber part(L2-L3) while we couldn't find any significant difference in the rest of lumbar(L3-S1). Besides, the changes of fat infiltration ratio on each lumbar level increased rapidly from lumbar 3,4 to lumbar 4,5. We also found that there is no correlation between fat infiltration ratio of lumbar paraspinal muscle(L2-S1) and BMI.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.67-71
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• 2013

Purpose: The Change of CT exposure condition have a effect on image quality and patient exposure dose. In this study, we evaluated effect CT image quality and SUV when CT parameters (Pitch, Rotation time) were changed. Materials and Methods: Discovery Ste (GE, USA) was used as a PET/CT scanner. Using GE QA Phantom and AAPM CT Performance Phantom for evaluate Noise of CT image. Images are acquired by using 24 combinations that four stages pitch (0.562, 0.938, 1.375, 1.75:1) and six stages X-ray tube rotation time (0.5s-1.0s). PET images are acquired using 1994 NEMA PET Phantom ($^{18}F-FDG$ 5.3 kBq/mL, 2.5 min/frame). For noise test, noise are evaluated by standard deviation of each image's CT numbers. And then we used expectation noise according to change of DLP (Dose Length Product) to experimental noise ratio for index of effectiveness. For spatial resolution test, we confirmed that it is possible to identify to 1.0 mm size of the holes at the AAPM CT Performance Phantom. Finally we evaluated each 24 image's SUV. Results: Noise efficiency were 1.00, 1.03, 1.01, 0.96 and 1.00, 1.04, 1.02, 0.97 when pitch changes at the QA Phantom and AAPM Phantom. In case of X-ray tube rotation time changes, 0.99, 1.02, 1.00, 1.00, 0.99, 0.99 and 1.01, 1.01, 0.99, 1.01, 1.01, 1.01 at the QA Phantom and AAPM Phantom. We could identify 1.0 mm size of the holes all 24 images. Also, there were no significant change of SUV and all image's average SUV were 1.1. Conclusion: 1.75:1 pitch is the most effective value at the CT image evaluation according to pitch change and It doesn't affect to the spatial resolution and SUV. However, the change of rotation time doesn't affect anything. So, we recommend to use the effective pitch like 1.75:1 and adequate X-ray tube rotation time according to patient size.

• Korea journal of population studies
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• v.31 no.2
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• pp.21-44
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• 2008

The main purpose of this study is to examine the effect of the family instability on the elderly suicide and to examine the change over time. An analytical model of causal structure was set up with residence, family instability and socioeconomic level as explanation variables for this study. The cause of death statistics and micro-data from the vital statistics for 1995, 2000 and 2005 were used. Family instability was measured through divorce, and the rate of elderly(male and female) suicide as well as the suicide rate of the elderly and those in their 20-50's was used for this analysis to examine the effect of divorce. This study hypothesized about family instability and elderly suicide through a literature review. This paper presents maps of the suicide rate by using GIS, and then ANOVA and regression analysis are carried out to verify a difference in the elderly suicide rate affected by residence and divorce. Divorce rate appears in most areas with a high level centering around metropolises except the central inland area. The rate of elderly suicide which stayed in only specific regions with a high level has increased as time went by, and the graph leveled high in most regions except the southwestern coast. In addition, the elderly suicide rate was increased rapidly in rural areas for the most recent 10 years. This shows the seriousness of problems of the aged in rural areas. Through the periods of economic crisis, a sudden increase in divorce causes family instability, which increase the suicide rate increasing. Divorce affects the elderly suicide rate and the 20-50s' suicide rate in the same way, and the stronger effect goes to the elderly rather than those in their 20-50s'. Regarding elderly suicide, the divorce has a different effect by gender, affecting males more than females. With these facts, we can draw the conclusion that family instability has the most significant effect on elderly males' suicide.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.1
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• pp.19-25
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• 2009

Purpose: The aims of this study were to analyze correlation between the maximum standardized uptake value (SUVmax) of 2-[F-18]-fluoro-2-deoxy-d-glucose (FDG) on positron emission computed tomography (PET-CT) scan and the degree of contrast enhancement on computed tomography (CT) scan in lung cancers, and to recognize the difference in SUVmax and CT enhancement between groups of different histopathologic subtypes. Materials and Methods: Our study included 53 patients of pathologically confirmed primary lung cancer, who were performed PET-CT and post-contrast chest CT. We calculated initial and delayed SUVmax (SUV1, SUV2), difference between SUV1 and SUV2 (SUVd), retention index (RI), and the degrees of CT contrast enhancement of lung cancers. We analyzed these variables for subtypes of lung cancers. Results: The values (mean$\pm$ standard deviation) were $8.3{\pm}4.4$ for SUV1, $10.7{\pm}5.7$ for SUV2, $2.4{\pm}1.6$ for SUVd, $30{\pm}14$ for RI and $47.1{\pm}14.8$ HU (Hounsfield Unit) for degree of CT contrast enhancement. The difference of SUV1 and degree of CT enhancement between subtypes was not meaningful. SUV1 showed positive correlations with SUVd (r=0.74, p<0,01) and tumor size (r=0.58, p<0.01), but no significant correlation with degree of CT enhancement (r=0.06, p=0.69). In 10 cases, there was discrepancy in the same mass between the area of highest FDG-uptake and the area of highest contrast enhancement. Conclusion: We suggest that FDG uptake in lung cancer does not have a positive linear correlation with degree of CT enhancement. And there is no significant difference in FDG uptake and degree of CT enhancement between different subtypes of lung cancers.

• Journal of dental hygiene science
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• v.10 no.3
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• pp.147-153
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• 2010

The purpose of this study was to investigate the correlation between food intake pattern body component bone mineral density(BMD) and dental caries experience of college women and we wanted to determine the correlation of these factors with dental caries experience. Research was conducted to offer basic data to develope a nutritional program for the future prevention from oral disease. The subjects in this study were 132 college women who participated in the food intake survey and who's body component and BMD was measured. The statistical analysis was done by using the SPSS 15.0 program. The results of this study were as follows; 1. The food intake pattern was not directly correlated with DMFT index. 2. The body component was not directly correlated with DMFT index. 3. The SOS, BQI was directly correlated with DMFT index(p<0.05). 4. T-score of BMD had the greatest influence on DMFT index(p<0.05). Above results indicated that bone mineral density are related with the incidence of dental caries experience and further research is necessary to develop a nutritional and health promotional program in order to prevent oral illness.

• Journal of Hospice and Palliative Care
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• v.13 no.2
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• pp.98-108
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• 2010

Purpose: The purpose of this study was to identify the relationship between fatigue and quality of life (QOL) of Korean cancer inpatients. Methods: The data were collected from May to August 2007. Study subjects were recruited at D, Y and A university hospitals in Daegu and Kyungpook, Korea. The research instruments utilized in this study were fatigue (FACT-F) and quality of life (FACT-G) in Korean version 4. Data were analyzed with descriptive statistics, t-test, ANOVA, and Pearson correlation using SPSS Win 12.0 program. Results: Fatigue of subjects showed a significant difference according to the type of treatment, change in weight, performance status, exercise, and sleep. The QOL of subjects showed a significant difference according to the purpose of treatment, change in weight, performance status, exercise, and sleep. The mean score of fatigue was 22.48 and the mean score of QOL was 55.52. The fatigue was negatively related to QOL, physical well-being, emotional well-being, and functional well-being. Conclusion: The results suggest the needs for intervention in order to reduce fatigue and to improve QOL of cancer inpatients.