• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2089-2098
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• 2015

With the continuous development in insulation of electrical equipment design, the reliability of the system has been enhanced. However, in the manufacturing process and during operation under continues stresses introduce local defects, such as voids between interfaces that can responsible to occurrence of partial discharge (PD), electric field distortion and accumulation of charges. These defects may lead to localize corrosion and material degradation of insulation system, and a serious threat to the equipment. A model of three layers of PI film with air gap is presented to understand the influence of interface and voids on exploitation conditions such as strong electrical field, PD activity and charge movement. The analytical analysis, and experimental results are good agreement and show that the lose contact between interfaces accumulate more residual charges and in consequences increase the electric field intensity and accelerates internal discharges. These residual charges are trapped charges, injected by the electrodes has often same polarity, so the electric field in cavities increases significantly and thus partial discharge inception voltage (PDIV) decreases. Contrary, number of PD discharge quantity increases due to interface. Interfacial polarization effect has opposite impact on electric field and PDIV as compare to void.

• Journal of Welding and Joining
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• v.32 no.3
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• pp.11-18
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• 2014

TSV(through silicon via) filling technology is making a hole in Si wafer and electrically connecting technique between front and back of Si die by filling with conductive metal. This technology allows that a three-dimensionally connected Si die can make without a large number of wire-bonding. These TSV technologies require various engineering skills such as forming a via hole, forming a functional thin film, filling a conductive metal, polishing a wafer, chip stacking and TSV reliability analysis. This paper addresses the TSV filling using Cu electrodeposition. The impact of plating conditions with additives and current density on electrodeposition will be considered. There are additives such as accelerator, inhibitor, leveler, etc. suitably controlling the amount of the additive is important. Also, in order to fill conductive material in whole TSV hole, current wave forms such as PR(pulse reverse), PPR(periodic pulse reverse) are used. This study about semiconductor packaging will be able to contribute to the commercialization of 3D TSV technology.

• Journal of Ocean Engineering and Technology
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• v.2 no.1
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• pp.135-149
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• 1988

Friction welding has been shown to have significant economic and technical advantages. However, one of the major concerns in using friction welding is the reliability of the weld quality. No reliable nondestructive test method is available at present for detecting weld quality, particularly in a production environment. Friction welds are formed by the mechanisms of diffusion as well as mechanical interlocking. The severe plastic flow at the interface by forge action of the process brings the subsurfaces so close together that detection of any unbonded area becomes very difficult. This paper presents an attempt to determine the friction weld strength quantitatively using the ultrasonic pulse-echo method. Instead of detecting flaws or cracks at the interface, the new approach calculates the coefficient of reflection based on measured amplitudes of the echoes. It has been finally confirmed that this coefficient could provide the quantitative relationship to the weld quality such as tensile strength, torsional strength, impact value, hardness, etc. So a new nondestructive analysis system of friction weld strength of dissimilar metals using an ultrasonic technique could be well developed.

• Journal of Magnetics
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• v.17 no.3
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• pp.225-228
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• 2012

Muscle contusion usually results from a direct blunt impact and is frequently associated with contact sports. Muscle contusion results from microscopic muscle fiber and capillary disruption causing a microhemorrhage dissecting torn fibers and remaining viable muscle fibers. Recent studies concluded that some physical methods, including pulsed ultrasound (PU) and pulsed electromagnetic field (PEMF) treatment, accelerate and facilitate wound healing, improve scar quality and have beneficial effects on muscle and tendon healing. However, there are few studies on the effects of the early use of physical methods, such as PU and PEMF, on the expression of neurotrophic factors. The objective of this study was to investigate the effects of the early application of PU and PEMF, measured through the expression of BDNF in the muscles (gastrocnemius) and spinal cords of rats after skeletal muscle contusion. In the spinal cords and muscles, there was a significant increase of BDNF expression in the PEMF and PU groups, a greater increase was found in the PEMF group than in the PU group. In conclusion, PEMF is a useful therapeutic method that improves muscle healing after muscle contusion.

• Korean Journal of Applied Biomechanics
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• v.25 no.4
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• pp.453-463
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• 2015

Objective : The purpose of this study was to investigate the effects of the Probody Massage Program on the physical characteristics, gross motor function and ROM (Range Of Motion) of children with cerebral palsy. Method : The subjects of this study were two children who have been diagnosed with first grade cerebral palsy that utilized T development support center located in B Metropolitan city for 8 weeks, twice a week, to carry out the Probody Massage Program for 30 minutes. Physiological reactions (height, weight, BMI, blood pressure (an index of inflammation), pulse rate) and large operating functions (sitting, crawling and the joints' range of motion as an angle of the shoulders' upper limb articulation) were measured pretest, after 4 weeks, and after 8 weeks. Results : The Probody Massage Program showed positive changes in physical characteristics (blood pressure, sitting, and crawling), gross motor function (upper limb shoulder movement), joint range of motion, height, body weight, metabolic activation and blood circulation of children with cerebral palsy. Conclusion : We believe making a practical impact on the growth and development, functional recovery of daily life, and improvement of quality of life of children with cerebral palsy by utilizing Probody Massage Program improves blood pressure (an index of inflammation), pulse, sitting, crawling, and the joints' range of motion as an angle of the shoulder joints' upper limb movement of children with cerebral palsy.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2018-2030
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• 2015

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal reference-random carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).

• Anxiety and mood
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• v.9 no.2
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• pp.121-127
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• 2013

Objective : Several studies have reported the association between posttraumatic stress disorder (PTSD) and hypertension (HTN). The aim of this study was to evaluate the impact of PTSD symptoms on blood pressure. Methods : Korean veterans of the Vietnam War with (n=62) or without PTSD (n=87) participated in this study. The clinician administered PTSD scale (CAPS) and alcohol use disorder identification test (AUDIT) were applied. Blood pressure, pulse rate, risk factors of HTN and demographic data of the subjects were collected. Effects of potential explanatory variables on HTN were analyzed with logistic regression. Results : Diastolic blood pressure was significantly higher in PTSD group (p=0.015). However, PTSD subjects showed significantly lower pulse rate than non-PTSD subjects (p=0.004). Logistic regression analysis showed that avoidance symptom might be a predictor for hypertension (OR=1.065, p=0.030). Conclusion : These results suggest that PTSD, especially avoidance symptom, might be a risk factor on HTN in the elderly with PTSD. Further studies are needed to evaluate the change of blood pressure according to the clinical improvement of PTSD.

• Biomedical Science Letters
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• v.15 no.1
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• pp.9-15
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• 2009

Early age at menarche, which is indicator of early biological maturity, has been shown to be associated with increased adult body mass index. Early menarche has also been associated with many cardiovascular disease risk factors and metabolic syndrome. To evaluate the impact of menarche to cardiovascular risk factor, we assessed by age at menarche, brachial-ankle pulse wave velocity (baPWV), which represents arterial stiffness, in women with or without metabolic syndrome. The subjects recruited for this study were three hundred one women. Relatively early menarche and relatively late menarche were classified according to less than $50^{th}$ percentile for relatively early menarche, and great than the $50^{th}$ percentile for relatively late menarche. Subject were divided four group, 1) women who had not adulthood metabolic syndrome and relatively early menarche, 2) women who had not adulthood metabolic syndrome and relatively late menarche, 3) women who had adulthood metabolic syndrome and relatively early menarche, 4) women who had adulthood metabolic syndrome and relatively late menarche. Women who had a relatively early menarche with adulthood metabolic syndrome had significantly high levels of blood pressure, triglyceride, fasting insulin and homeostatic model assessment of insulin resistance (HOMA-IR) levels than women with late menarche with adulthood metabolic syndrome, and had significantly lower HDL-cholesterol levels. And also, women who underwent a relatively early menarche with metabolic syndrome had highest level of baPWV in adult. In this study we found effect of age at menarche on adulthood metabolic risk factors for cardiovascular disease (e.g., baPWV, insulin resistance, hyperlipidemia) in Korean women.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.338-342
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• 2018

In order to solve the floor impact sound problem in the upper and lower floors, the Ministry of Land, Transport and Maritime Affairs also notifies the physical properties of the resilient material affecting the floor impact sound level. The dynamic modulus of elasticity and the loss factor before and after heating are most related to the floor impact noise, especially for the cushioning material. Therefore, in this study, the rate of change with respect to the dynamic modulus and loss factor with temperature change was examined by increasing $10^{\circ}C$ by $10^{\circ}C$ from the temperature condition of $70^{\circ}C$ specified in the standard. The dynamic modulus of elasticity and the loss modulus were measured by using the pulse excitation method for eight kinds of samples. The calculation method was calculated by the time series analysis method using the damped vibration waveform.

• Journal of Korean Society of Disaster and Security
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• v.8 no.1
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• pp.21-27
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• 2015

Recent researches show that climate change has impact on the rainfall process at different temporal and spatial scales. The present paper is focused on climate change impact on sub-daily rainfall quantile of Han River basin in South Korea. Climate change simulation outputs from ECHO-G GCM under the A2 scenario were used to estimate daily extreme rainfall. Sub-daily extreme rainfall was estimated using the scale invariance concept. In order to assess sub-daily extreme rainfall from climate change simulation outputs, precipitation time series were generated based on NSRPM (Neyman-Scott Rectangular Pulse Model) and modified using the ratio of rainfall over projection periods to historical one. Sub-daily extreme rainfall was then estimated from those series. It was found that sub-daily extreme rainfall in the future displayed increasing or decreasing trends for estimation methods and different periods.