• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.127-134
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• 2005

This paper introduces a newly developed high speed material testing apparatus for tensile tests at the strain rate up to 500/sec. The tensile properties of sheet metals are indispensable for the accurate crashworthiness analysis of auto-bodies since the local strain rate reaches to 500/sec in the car crash. An appropriate experimental method has to be developed to acquire the tensile properties at the intermediate strain rate ranged from 0.003/sec to 200/sec. Tensile tests of various different steel sheets for an auto-body were perform ed to obtain the dynamic properties with respect to the strain rate. The dimensions of specimens that can provide the reasonable results were determined by the finite element analysis. A special jig fixture of a load cell is designed to reduce the load ringing phenomenon induced by unstable stress propagation at the high strain rate. Stress-strain curves were acquired for each steel sheet from the dynamic tensile test and utilized to obtain the relationship of the stress to the strain rate.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.2
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• pp.63-67
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• 2008

Purpose: To study the route of information on eye-health and the practical rate for college students. Methods: 292 college students' data were examined by SAS of questionnaire. Results: College students mainly gained the information on eye-health from the optician's shop (45.21%), mass communication (27.74%), and ophthalmic clinic (14.38%). The rate of satisfaction of informations from those routes was high. Especially, the satisfaction of the information from the optician's shop was very high (85.60%). Visual acuity corrected students mainly gained the information from the optician's shop (55.50%), and non-corrected students gained mainly from mass communication (43.56%). The practical rate of the information was high (70.21%). The practical rate of the information gained from the optician's shop was very high (76.52%). Conclusions: Many College students gained the information on eye-health from the optician's shop. The rate of satisfaction and the practical rate in optician's shop was higher than the other routes.

• Journal of radiological science and technology
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• v.19 no.1
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• pp.55-74
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• 1996

This study was carried out to improve service efficiency and to cope with a emergency situation in emergency radiography, through analysis of the radiographic distribution and literature cited about emergency care. Data collection of radiographic distribution was surveyed for 761 emergency outpatients who visit during JAN, 1994 at ER of the general hospital in Pusan city. The results is as follows: Emergency radiography rate of simple radiography was 61.1 %, special radiography 2.5 %, CT 12.6 %, and ultrasonography 6.7 %. In simple radiography rate, a high rate was distributed on male(63.6 %), thoracicsurgery part(90.0%), admission patient(74.9 %), and long stayed patient at ER. In special raiography rate, a high rate was observed in urologic part(28.6%), and in CT rate, observed neurosurgery part(49.2 %) and neurologic part(36.7%). Ultrasonography rate was high for female(8.8 %) and internal medicine part(15.9 %). There are distributed regional radiography rate in radiographic type that chest(55.3 %) is high in the simple radiography, urinary system(1.2%) in the special study, and brain(40.0 %) in the CT. Regional radiography rate according to diagnostic department also was showed highly for head(64.6%) in neurosurgery, chest(90.0%) in thoracic-surgery, abdomen(58.0%) in general-surgery, spine (40.0% ) in neuro-surgery, and pelvis(15.9%), upper extrimity(20.5%), and lower extrimity(31.8%) in orthopedic-surgery each. Mean radiographic case number per patient of simple radiography was sinificant on sex, age, transfer relation in both total and radiographic patients(p<0.05). Mean radiographic case number was highly distributed on male(2.2 case number) in sex, on thirties(2.7) in age, transfered patient(2.7) in patient type, and on neurosurgery(3.4) in diagnostic charged part. Total radiographic case number in regional part was highly distributed on chest(499 case number). Considering the above results, emergency radiographer should take care of the elder patient in emergency radiography and get hold of injury mechanism to decrease possible secondary injury during radiography. Because of high radiography rate of urinary system in special study, radiographer should know well about dealing with contrastmedia administration and related instrument. All radiographer who take charge emergency patient should cope with a emergency situation during radiography, Because head trauma patients is very important in patient care, especilly in CT at night, charged doctor should be always silted with CT room and monitoring-patient. Radiography was reqested by many diagnostic department in ER. Considering that rate of simple radiography is high, special room for emergency radiography should be established in ER area, and the radiographer of this room should be stationed radiologic technician who is career and can implement emergency patient care.

• Journal of the Korean institute of surface engineering
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• v.19 no.3
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• pp.109-120
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• 1986

The electroless nickel plating on high alumina ceramics was performed in the bath containing nickel chloride, sodium hypophosphite and mono- or bi-carboxylic acid as a complexing agent in order to examine the empirical rate law as well as the effects of the complexing agent, plating temperature and pH on the rate of deposition. Adding the carboxylic acid to the plating bath, the rate of deposition was increased considerably, and each of the complexing agents showed a maximum deposition rate plateau around a particular concentration of the complexing agent. The rate of deposition was increased with increasing either temperature or pH, but microstructure of the surface became more rough. Furthermore, empirical rate law of the elecltroless nickel deposition on high alumina ceramics was discussed with the activation energy and other rate parameters calculated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.421-424
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• 2006

High nitrogen steels (HNS) exhibit both high strength and ductility during tensile deformation. In the present study the Fe-18Cr-14Mn-4Ni-0.9N high nitrogen steel was heat treated at $1000^{\circ}C$ and $1100^{\circ}C$ to produce $Cr_2N$ precipitates in austenite matrix and full austenite microstructures, respectively. Tensile tests of the heat treated specimens were performed at two different strain rates of 0.05/sec and 0.00005/sec. Each tensile curve of the specimens could be well characterized by the the modified Ludwik equation. Plastic deformation of the steel was adequately represented by the four parameters of the modified Ludwik equation. At 0.05/s strain rate, the specimen with the $Cr_2N$ precipitate exhibited higher strength than the full austenite specimen, while the full austenite specimen showed better mechanical properties at 0.00005/s strain rate. It was found that the $Cr_2N$ precipitates influences deformation behavior of the high nitrogen steel significantly.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.344-354
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• 2014

Transmission control protocol friendly rate control (TFRC) is designed to mainly provide optimal service for unicast applications, such as multimedia streaming in the best-effort Internet environment. However, high bandwidth networks with large delays present an environment where TFRC may have a problem in utilizing the full bandwidth. TFRC inherits the slow-start mechanism of TCP Reno, but this is a time-consuming process that may require many round-trip-times (RTTs), until an appropriate sending rate is reached. Another disadvantage inherited from TCP Reno is the RTT-unfairness problem, which severely affects the performance of long-RTT flows. In this paper, we suggest enhanced TFRC for high quality video streaming over high bandwidth delay product networks. First, we propose a fast startup scheme that increases the data rate more aggressively than the slow-start, while mitigating the overshooting problem. Second, we propose a bandwidth estimation method to achieve more equitable bandwidth allocations among streaming flows that compete for the same narrow link with different RTTs. Finally, we improve the responsiveness of TFRC in the presence of severe congestion. Simulation results have shown that our proposal can achieve a fast startup and provide fairness with competing flows compared to the original TFRC.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1073-1081
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• 2001

Many researches have published numerous papers about the high-strain-rate obtained from Split Hopkinson Pressure Bar(SHPB) tests. And 6.5wt%Si steel is widely known as an excellent magnetic material because its magnetostriction is nearly zero. Single crystals are prepared by the Floating Zone(FZ) method, which melts the alloy by the use of a high temperature electron beam in a pure argon gas condition. In this paper, the fracture behavior of the poly crystals and single crystals (DO$_3$phase) of Fe-6.5wt%Si alloy by SHPB test is observed. The comparison of high-strain-rate results with static results was done. Obtained main results are as follows: (1) Fe-6.5wt%Si alloy has higher strength at high-strain-rate tensile. SHPB results of polycrystal are twice as high as static results. (2) From the fractography, the cleavage steps are remarkably reduced in the SHPB test compared with the static test.

• CELLMED
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• v.5 no.1
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• pp.4.1-4.4
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• 2015

Yoga is an ancient Indian system of life, encompassing various practices including practices for self-discipline and also for regulating the health states of the individual, being practiced for thousands of years. The present study aims at understanding the effect of two high frequency breathing practices over autonomic nervous system. Forty healthy male volunteers of age $21{\pm}2$ years with $9{\pm}3$ months of Yoga practice experience were recruited. The two high frequency Yoga breathing practices, kapalabhati (KB) and bhastrika (BH) were given as interventions randomly on either of the two days to minimise laboratory bias. They were assessed before and immediately after the interventions for heart rate, respiratory rate, heart rate variability (HRV), blood pressure and peripheral oxygen saturation. There was a significant increase in heart rate (p<0.01; p<0.001), systolic blood pressure (p<0.01; p<0.001), NN50 (p<0.01; p<0.001) component of HRV for both KB and BH groups respectively. There was a significant reduction in respiratory rate in both the groups (p<0.001, and p<0.05, BH and KB respectively) immediately following intervention. A significant increase in LF component of HRV and reduction in Diastolic blood pressure and high frequency (HF)component following KB was also observed (p<0.05, for all comparisons). The Mean peripheral oxygen saturation remained unaltered in both the groups (p>0.05).The results suggest that high frequency yoga breathing practices induce physiological arousal immediately as evidenced by increased blood pressure and heart rate. The sympathetic arousal was more following KB session as evidenced by an increased diastolic blood pressure, LF power and a decrease in HF power of HRV as compared to the BH session.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.656-663
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• 2005

This paper presents a multi-channel enhancement scheme for the MAC protocol of IEEE 802.15.3 High-rate WPAN (Wireless Personal Area Network). The current MAC protocol of the IEEE 802.15.3 High-rate WPAN is designed for sharing a single channel among DEVs of a piconet; that is, within a single piconet, PNC prevents interference through MAC layer assignment of time slots to other DEVs using time-division multiple access. When the number of DEVs that communicate with each other frequently, is increased in a single WPAN, the size of the superframe becomes inevitably large, and this may result in a significant throughput drop or a failure to provide QoS guarantee. A multi-channel enhancement scheme for the MAC protocol of IEEE 802.15.3 High-rate WPAN is proposed to significantly increase the aguegate throughput and more reliably provide the QoS guarantees in a piconet

• The Journal of the Korea Contents Association
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• v.13 no.6
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• pp.236-245
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• 2013

This study analyzed the relationship between elderly suicide rates and socio-economic factors from the macroscopic perspectives. As certain theoretical background of elderly suicide, sociological and economic perspectives are applied. The economic factors of elderly suicide rates consisted of economic growth and unemployment rate, economic activity rate of the aged, and relative poverty rate (income inequality rate). The sociological factors included social welfare spending, divorce rate, growth rate of population aging, and elderly dependency ratio. According to research findings, first, the more economic activity of the aged is low, the more elderly suicide rate is high. Second, the more social welfare spending rate goes flat, the more elderly suicide rate is growing. Third, the more relative poverty rate (income inequality), increasing population aging rate, and elderly dependency ratio are high, elderly suicide rate goes high at the same time. Finally, this study proposed several socio-economic policy alternatives for preventing continuous growth of Korean elderly suicide rate.