• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.6
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• pp.559-565
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• 2004

Two different methods were used for the scattering analysis of side-drilled holes(SDH). The scattering models include an explicit model based on the Kirchhoff approximation and the solution of the exact separation of variables. The far-field scattering amplitude was calculated and their time-domain results were compared for the case of shear vertical wave. The exact solution predicts the existence of the creeping wave. The Kirchhoff approximation agreed to the exact solution, except the case of the creeping wave. Two measurement models were introduced to predict the response from the SDHs for the case of immersion, pulse-echo testing. The received voltage was calculated for the case of the shear vertical waves with the incident angle of $45^{\circ}$ to the SDH with the diameter of 1mm, and compared with the experimental results.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.2
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• pp.187-193
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• 2015

In this study, regressive models were employed to predict the blood velocity by using independent variables which measured by 3 sensors, such as electrocardiogram (ECG), photo-plethysmogram (PPG), pulse diagnosis sensor, without ultrasound device at high cost. In experiment, the high predictable model was induced to estimate the blood velocity correctly by comparing correlation values and significance probabilities between independent variables and blood velocities. Results showed that the model induced by two or three independent variables had a higher predictability than those by a single independent variable.

• Journal of the Korean institute of surface engineering
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• v.53 no.4
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• pp.138-143
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• 2020

In this study, we produced a coil of micro-pattern that can be used for electromagnetic wave absorber, heating material, wireless charging, sensor, antenna, etc. by using electrochemical additive manufacturing method. Currently, it contains research contents for manufacturing a micro pattern coil having practicality through control of process control variables such as applied voltage, distance between electrode, and nozzle injection. Circulation of the electrolyte through the nozzle injection control can significantly contribute to improving the surface characteristics of the coil because of minimizing voltage fluctuations that may occur during the additive manufacturing process. In addition, by applying the pulse method in the application of voltage, the lamination characteristics of the plated body were improved, which showed that the formation of a fine line width plays an important role in the production of a micro pattern coil. By applying the pulse signal to the voltage application, the additive manufacturing characteristics of the produced product were improved, and it was shown that the formation of a fine line width plays an important role in the production of a micro pattern coil.

• Clinical and Experimental Pediatrics
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• v.57 no.5
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• pp.217-221
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• 2014

Purpose: The aim of this study was to determine whether school-aged children with Kawasaki disease (KD) have an increased risk for early atherosclerosis. Methods: The study included 98 children. The children were divided into the following groups: group A (n=19), KD with coronary arterial lesions that persisted or regressed; group B (n=49), KD without coronary arterial lesions; and group C (n=30), healthy children. Anthropometric variables and the levels of biochemical markers, including total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A, apolipoprotein B, homocysteine, highsensitivity C-reactive protein (hs-CRP), and brachial artery stiffness using pulse wave velocity were compared among the three groups. Results: There were no significant differences in blood pressure and body index among the three groups. Additionally, there was no sex-specific difference. Moreover, the levels of triglyceride, HDL-C, apolipoprotein A, and hs-CRP did not differ among the three groups. However, the levels of total cholesterol (P =0.018), LDL-C (P =0.0003), and apolipoprotein B (P =0.029) were significantly higher in group A than in group C. Further, the level of homocysteine and the aortic pulse wave velocity were significantly higher in groups A and B than in group C (P=0.0001). Conclusion: School-aged children after KD have high lipid profiles and arterial stiffness indicating an increased risk for early atherosclerosis.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.209-215
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• 2019

The most important personal health care in digital health care is a very important issue mainly for chronic diseases. Therefore, it is important to develop a simple wearable device for real-time health management. Existing blood pressure estimation wearable devices use PPG characteristics to analyze PTT and propose blood pressure estimation algorithms. However, the influencing factors of the algorithm such as the reproducibility of PPG, whether to apply various PTTs, and variables generated from the physical differences of the measurers are actually very complex. Therefore, in this study, the correlation between PTT, SBP, and DBP was analyzed, and it was designed to use PPG sensors for device miniaturization. The blood pressure estimation algorithm took into account differences in PPG, heart rate, and personal variables.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1862-1865
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• 2005

We have a plan to design a controller for electron beam manufacturing system. At first, we designed a controller for SEM. The controller consists of five parts (power source, beam controller, scanning controller, optic controller and main controller). Beam controller supplies pulse wave for generating high voltage and can monitor the status of high voltage instrument through emission current. Optic controller controls focus, spot size and image shift. Main controller transmits variables from operating program to each part and monitors the status of peripheral device.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.4
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• pp.378-387
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• 2016

This study sought to investigate interrelationships and differences of brachial-ankle pulse wave velocity (baPWV), body composition and cardiovascular variables between genders who have been exercised or not in elderly. One hundred fifty participants were classified four groups. Especially out of variables, in male elderly group who had participated in exercise program the PWV range were significantly correlated with muscle mass (r=0.357, p=0.026), SBP (r=0.468, p=0.003), right baPWV (r=0.406, p=0.010), and left baPWV (r=0.333, p=0.038). In male elderly group who had not participated in exercise program, the PWV range were significantly correlated with heart rate (r=0.395, p=0.014), right baPWV (r=0.598, p=0.000), and left baPWV (r=0.602, p=0.000). In female elderly group who had participated in exercise program, the PWV range were significantly correlated with name of diagnosis (r=0.321, p=0.044), SBP (r=0.399, p=0.011), DBP (r=0.545, p=0.000), right baPWV (r=0.648, p=0.000), and left baPWV (r=0.676, p=0.000). In female elderly group who had not participated in exercise program, the PWV range were significantly correlated with age (r=0.471, p=0.003), right baPWV (r=0.836, p=0.000), and left baPWV (r=0.801, p=0.000). The PWV among four groups were not significant different after experiment. However, there were significant differences in the waist/hip ratio (F=9.197, p=0.000), muscle mass (F=74.295, p=0.000), and %fat (F=35.045, p=0.000) from body composition. And there were significant differences in the SBP (F=3.525, p=0.017) after experiment. In conclusion, these data show that regular exercise is associated with arterial compliance (PWV range, right or left PWV) and differed from genders. In other words, this paper may support the concept that regular exercise program may exert a protective effect on arterial compliance, body composition and cardiovascular systems.

• Clinical and Experimental Pediatrics
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• v.50 no.6
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• pp.549-555
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• 2007

Purpose : Pulse wave velocity (PWV) and ankle brachial index (ABI) are simple, non-invasive methods to assess arterial stiffness. These parameters are also known to be closely related to cardiovascular risk factors and diseases. The purposes of this study were to measure blood pressure, PWV, ABI in healthy Korean adolescents, set up their normal values and assess their correlations. Methods : Three hundred ninety two healthy adolescents (213 boys and 179 girls) underwent measurement of brachial ankle pulse wave velocity (baPWV), ABI, body mass index(BMI) and blood pressure from four extremities. Linear regression analysis was performed to reveal the correlations between PWV, ABI and independent variables. Results : Blood pressure and PWV were significantly higher in all extremities in males compared to females. Blood pressure of both brachial and ankle showed positive correlation with body weight, height, and BMI, whereas ABI showed no correlation with any of these indices. Conclusion : Blood pressure increases as body weight, height and BMI increases. PWV shows positive correlation with blood pressure. It will be helpful to predict the risks of cardiovascular diseases in adolescents.

• The Korean Journal of Health Service Management
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• v.7 no.3
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• pp.71-82
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• 2013

Arterial stiffness(AS) is an important pathologic state of vascular injury. This study was carried out to elucidate the effect of physiological variables on brachial-ankle pulse wave velocity(BAPWV), index of AS. Four hundred adults(volunteers) participated in this study. Body indices, biochemical, cardiac and inflammatory markers, and right(Rt)- and left(Lt)-BAPWV were measured. Body mass index(BMI), Rt- and Lt-BAPWV, glucose, triglyceride, alkaline phosphatase(ALP), gamma-glutamyl transferase(GGT), creatinine, uric acid, troponin-I(TNI), NT-proBNP and high sensitivity C-reactive protein(hs-CRP) levels were higher than the reference value of each variable. Rt- and Lt-BAPWV were directly correlated with age, body weight, BMI, glucose, ketone, aspartate aminotransferase, alanine aminotransferase, ALP, GGT, total cholesterol, low density lipoprotein, lipoprotein(a), apolipoprotein-B, blood urea nitrogen, heart rate, TNI, creatine kinase, CK-MB, lactic dehydrogenase, myoglobin, hs-CRP, lipase, reumatoid factor, fibrinogen and D-dimer (P<0.05, P<0.01, P<0.001 or P<0.000, respectively), but inversely associated with total bilirubin, uric acid, apolipoprotein-A1 and GFR (P<0.05). These observations suggest that a variety of physiological variables may influence BAPWV, resulting in increased risk or prevention of cardiovascular and/or cerebrovascular attacks. Therefore, physiological variables affecting BAPWV should be regularly controlled.

• Journal of Korean Biological Nursing Science
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• v.21 no.3
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• pp.178-187
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• 2019

Purpose: The purpose of this study was to investigate how college students' perceived stress, cognitive stress, and somatization affect their heart rate variability (HRV). Methods: This study is a cross-sectional survey research on 191 university students, registered at the G University. The perceived stress scale (PSS) and cognitive stress response scale, were used to assess level of stress. The somatization symptom scale of the Symptom Check List 90 (SCL-90), was used to assess level of somatization caused by stress. To assess heart rate variability (HRV), we conducted a five-minute test using a pulse wave analyzer, to analyze short-term HRV. Results: The SCL-90 somatization score had relatively high positive correlation (p< .001) with cognitive stress, but low positive correlation (p< .001) with perceived stress. Cognitive stress response had low negative correlation (p< .001) with 1nSDNN and 1nRMSSD among HRV parameters. Perceived stress was not correlated with HRV. Multiple regression analysis showed that variables of perceived stress, cognitive stress, and somatization symptoms, could not explain HRV. By contrast, one of the HRV indicators, 1nSDNN, was affected by age, gender, and aggressive-hostile thought, the latter being a subscale of the cognitive stress response scale. Conclusion: This study suggests that stress evaluation for people in early adulthood will be more effective, if the evaluation examines cognitive stress and heart rate variability.