• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.483-489
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• 2018

Driving behaviors are reported to be vulnerable to safe driving in unexpected situations or driving in the city due to deterioration of physical and cognitive functions in elderly drivers. The purpose of this study was to investigate the difference in driving behaviors according to age of self-drivers and to identify changes in physical function related to driving caused by normal aging. The subjects of the study included 75 healthy adults (21 persons aged 20-39 years, 40 persons 40-64 years, 14 persons 65 years old) who were self-driving and possessed a driver's license. Data included sex, dominant hand, medication, exercise, age, and driving time obtained by a self-reported questionnaire. In addition, this study measured steering, acceleration and braking using a Driver Test Station. Results of the study showed there was no significant difference in power test according to age group, but the total time of the timer test and the emergency brake test significantly differed according to age. The timer test and emergency brake test were completed fastest in young adults between 20 and 39 years old and completed slowest in elderly people 65 years old or over. Based on our study results, it is suggested that normal aging affects the perceptual-cognitive processes associated with driving behaviors.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1330-1338
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• 2011

Social activities of the elderly have been increasing as our society progresses toward an aging society. As their activities increase, so does the occurrence of falls that could lead to fractures. Falls are serious health hazards to the elderly. Therefore, development of a device that can detect fall accidents and prevent fracture is essential. In this study, we developed a portable fall detection system for the fracture prevention system of the elderly. The device is intended to detect a fall and activate a second device such as an air bag deployment system that can prevent fracture. The fall detection device contains a 3-axis acceleration sensor and two 2-axis tilt sensors. We measured acceleration and tilt angle of body during fall and activities of daily(ADL) living using the fall detection device that is attached on the subjects'. Moving mattress which is actuated by a pneumatic system was used in fall experiments and it could provide forced falls. Sensor data during fall and ADL were sent to computer and filtered with low-pass filter. The developed fall detection device was successful in detecting a fall about 0.1 second before a severe impact to occur and detecting the direction of the fall to provide enough time and information for the fracture preventive device to be activated. The fall detection device was also able to differentiate fall from ADL such as walking, sitting down, standing up, lying down, and running.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.3
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• pp.13-20
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• 1991

The present work was aimed to examine the variation of precipitations and mechanical properties by thermomechanical treatments (TMT) in Al-2.19 wt%Li and Al-2.0 wt%Li-0.11 wt%Zr alloys. This study was performed by TEM, SEM observation, DSC, electrical resistance measurement, hardness and tensile strength measurement. First peak of resistivity aged at $90^{\circ}C$ was caused by precipitation of ${\delta}^{\prime}$-precursor phase, and second peak was caused by precipitation of ${\delta}^{\prime}$ phase. According to this result, the precipitation process of Al-2.19 wt%Li alloy was as follow : $SSSS{\rightarrow}{\delta}^{\prime}$-precursor phase ${\rightarrow}{\delta}^{\prime}$ (Coherent ${\rightarrow}$ Semi-coherent) ${\rightarrow}{\delta}$. In a Al-2.0 wt%Li-0.11 wt%Zr ternary alloy, the first peak of resistivity was appeared at initial aging heat-treatment. It is result from exsistant of ${\delta}^{\prime}$-precursor phase. The effect acceleration in a binary alloy was not appeared and the over-aging ternary alloy was accelerated with increase of the reduction rate. It is caused by combination effect of ${\delta}^{\prime}$ and composite phase.

• Environmental and Resource Economics Review
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• v.27 no.3
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• pp.545-567
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• 2018

This study applied and compared Poisson model, negative binomial model, zero inflated Poisson model, and zero inflated negative binomial model to estimate determinants of employed labour quantity. To estimate each of models, this study used fisheries census data which were obtained at microdata integrated service running by Statistics Korea. The study selected zero inflated negative binomial model according to the Vuong test and Likelihood-ratio test. In addition, the study estimated fishing village's practical changes on employed labour quantity as analyzing changes from 2010 to 2015. The results showed that the household with fishing vessels and high selling price had a significant effect on decrease of the labour quantities. Meanwhile, the longer work experience of the household, the more significant the increase in the labour quantities. In conclusion, this study presented that capitalized fishing household and the acceleration of aging had a significant impact on the change in the labour quantities.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.477-481
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• 2008

The secondary hardening and fracture behavior in P/M high speed steels bearing V content of 9 to 10 wt% have been investigated in terms of austenitizing temperature and precipitation behavior. Austenitizing was conducted at 1,100 and $1,175^{\circ}C$ of relatively low and high temperatures. Coarse primary carbides retained after austenitization were mainly V-rich MC type. They give a significant influence on hardeness and toughness, as well as wear resistance. Tempering was performed in the range of $500{\sim}600^{\circ}C$. The peak hardness resulting from the precipitation of the fine MC secondary carbides was observed near 520, irrespective of austenitizing temperature. Aging acceleration(or deceleration) did not occur with increasing austenitizing temperature because it mainly influences contents of V and C of matrix through the dissloution of coarse primary MC containing lots of V and C. The precipitation of secondary MC carbides, which also contain V and C, did not change the aging kinetics itself. In the 10V alloy containing much higher C content, the impact toughness was lower than 9V alloy, because of the larger amount of primary carbide and high hardness.

• Journal of the Institute of Convergence Signal Processing
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• v.23 no.2
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• pp.76-83
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• 2022

With the recent development of IT technology, research and interest in various biosignal measuring devices is increasing. As an aging society is in full swing, research on the elderly population using IT-related technologies is continuously developing. This study is about the development of life pattern detection and fall detection algorithm, which is one of the medical service areas for the elderly, who are rapidly developing as they enter a super-aged society. This study consisted of a system using a 3-axis accelerometer and an electrocardiogram sensor, collected data, and then analyzed the data. It was confirmed that behavioral patterns could be classified from the actual research results. In order to evaluate the usefulness of the human activity monitoring system implemented in this study, experiments were performed under various conditions, such as changes in posture and walking speed, and signal magnitude range and signal vector magnitude parameters reflecting the acceleration of gravity of the human body and the degree of human activity. was extracted. And the possibility of discrimination according to the condition of the subject was examined by these parameter values.

• Transactions of the Society of Information Storage Systems
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• v.8 no.2
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• pp.50-55
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• 2012

Optical disks are widely used in libraries and archives as digital data media due to their long-term storage stability. Though archive-grade optical disks are already available on the market, there is a relative less focusing on the reliable recording conditions. Commercial BD-R media were recorded at various recording speeds with the maximum speed of 6X, and tested at the acceleration aging conditions. Through the evaluation of long-term storage features by the data stability test, lower recording speed of 2x resulted in better long-term storage stability. In addition, degradation aspects of unstable long-term storage feature at outer region of disk were discussed.

• Journal of Korean Academy of Nursing
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• v.37 no.6
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• pp.914-923
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• 2007

Purpose: This qualitative study aimed to identify the common, lived experiences of grandmothers who cared for their grandchildren as the primary caregivers. Methods: This study was based on the phenomenological method described by Colaizzi (1978). Results: Seven theme clusters emerged from the data as follows: "grandmother caregivers accept the parenting role of the incessant responsibilities and the distrust of non-kin caregivers.", "grandmother caregivers have a double maternal roles; an instrument-oriented maternal role to their own child and relationship-oriented maternal role to their grandchild.", "grandmother caregivers are partially authorized to make decisions in the matters of their grandchild.", "grandmother caregivers suffer a deterioration in their health by an acceleration of the aging process.", "caregiving causes grandmother caregivers to feel a sense of social isolation, and persue various coping strategies to control this feeling.", "grandmother caregivers have a greater feeling of self-esteem, but they often conflict with their adult children if they don't feel appreciated by them.", "grandmother caregivers have limited social support and their health issues are often overlooked in the family context.' Conclusion: The results of this study can guide nurses and health care workers to understand the experiences of grandmother caregivers and to implement individualized nursing interventions suited for them.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.7
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• pp.892-897
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• 2018

Due to population aging, an increase in the number of patients with chronic illnesses, and an increase in the number of single-person households, monitoring of health status in everyday life without the need for a hospital has become very important. For this reason, researches on various health care devices have been attempted, among which wearable devices are attracting much attention. In this paper, we propose a new ring-type wearable device for next generation healthcare. On the inner side of the ring, a metal electrodes for GSR measurement and an optical sensor for measurement of pulse wave signals of two wavelengths of red and near-infrared light were mounted. In addition, it was equipped with an acceleration sensor, and information about the degree of motion could be obtained. In this paper, it is shown that a health monitoring device can be implemented in the form of a ring, and the measured signals can be used to calculate heart rate, oxygen saturation, sleep time and sleep efficiency. Through the advanced algorithm, it is expected that we can extract various health information, especially sleep related health information by using the ring device, and it is also expected that it can contribute to the implementation of wearable healthcare effectively.

• Journal of the Korean Society for Railway
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• v.9 no.4 s.35
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• pp.357-361
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• 2006

This paper dealt with the performance evaluation and the diagnostic techniques of lightning arresters for DC electric traction vehicle. Field Measurements on the protective operation of lightning arresters against surge currents were carried out on running vehicles to acquire the data necessary for the diagnosis. The frequency and the magnitude of surge events were analyzed. Surge currents of $1\sim3$ times were recorded in one running service route and their magnitudes were ranges of $150A\sim2kA$. Also, an acceleration experiment on a lightning arrester by the standard lightning impulse current of 8/20 us and 5 kA was performed to know the aging characteristics. After the surge current application of 3,000 times, the reference voltage decreased by 4.5 %, and the leakage current was below 10 uA at the continuous operating voltage and about 50 uA at the rated voltage. From the experimental results, we propose a decision level of leakage current for the arrester used in this paper and designed an arrester tester which analyzes arrester condition by the magnitude of leakage current.