• International Journal of Railway
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• v.3 no.2
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• pp.60-67
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• 2010

This paper deals with an experimental study on the wheel flange climbing of railway vehicles, which is a major factor leading to derailment. An experiment is carried out on a 1/5-scale model wheelset of a truck used on a standard-gauge track, which is placed on a roller rig. The lateral external force acting on the wheelset is ramped up until derailment occurs under the condition of a fixed attack angle and wheel-load unbalance ratio. Three parameters, the height of wheel lift, the lateral force, and the wheel load acting on the outer rail, are measured until derailment occurs. From these measurements, it is possible to observe the behavior of the wheelset and to elucidate how the attack angle, the wheel-load unbalance ratio and the lateral external force affect flange-climb derailment. Then, a numerical simulation is carried out using an analytical model based on a single wheelset. As a result, the flange-climb behavior observed in the experiment can be explained theoretically on the bases of the analytical results, although further improvement of the model is desired.

• Journal of Korean Public Health Nursing
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• v.24 no.2
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• pp.173-181
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• 2010

Purpose: The aim of this study was to gauge the social willingness to pay for cognitive enhancement program for elders. Methods: The subjects of this study were 77 subjects >65-years-of-age. The data were collected by direct interviews. The measures of willingness to pay were open-ended question and referendum format. The data were analyzed using descriptive statistics, t-test, $x^2$-test, and multiple regression. Results: Respondents were willing to pay 18,573 won for one use of a cognitive enhancement program for elders. The Monthly income was the only factor that statistically significantly affected willingness to pay. Conclusion: The findings will contribute to policy formulation regarding community based nursing program for elders.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.4
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• pp.45-53
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• 2013

Efficient water operation and management of an irrigation system plays an important element in the sustainability of irrigated agriculture. An agricultural water is delivered in many open canals of irrigation delivery system by reservoirs. The poor water distribution and management in an irrigation system is a major factor leading to low water efficiency. It is necessary to compare the estimated irrigation demands with the actual water supplies for decision making to maintain the water supply according to demand strategy. Smarter water management, new technologies and improvement of water management system, is essential to solve the problem of water efficiency and availability. In this paper, the irrigation efficiencies according to water delivery performance indicator were measured with automatic water gauge at irrigation canals, and calculated from spatial and temporal distribution of water supply for the lack of planning in water delivery. The analysis of results are obtain an insight into possible improvement methods to develop canal water management policies that enable irrigation planners to optimally manage scarce available water resources.

• Transactions of Materials Processing
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• v.12 no.5
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• pp.498-503
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• 2003

The die for cold forging gets a very high axial load and radial pressure during processing and hence deforms considerably in the radial direction. This radial deformation of die becomes a important factor influencing the dimensional accuracy of a product. In order to obtain the product with highly accurate dimension, therefore, it is essential to acquire some information on elastic deformation of the die and the product. The study has been performed for the relation of the deformation between the die and the product in backward extrusion. The strain of the die has been given by the simple experiment using the strain gauges attached to the outer surface of the die. Also the history of the deformation of the die and the product has been given by the experiment and Lames' formula. The results has been compared with the previous another method. The study has given useful results for the deformation history of the die and the product through the experiment and Lame's formula in backward extrusion, which can be applied in the die design for the product with accurate dimension.

• Korean Journal of Human Ecology
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• v.9 no.4
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• pp.55-66
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• 2006

The purpose of this study was to identify the effect on the evaluation or a female teachers' role-performance based on appearance according to backgrounds of students and their parents. For this study, data was collected between October 19 and 29, 2005 by means of a questionnaire designed to gauge a subject's evaluation of a teacher's abilities in learning guidance, living guidance, and human relations. The researchers selected two middle schools and four high schools in the city of Gwang-ju. The 398 surveys completed were analyzed using factor analysis, one-way ANOVA, Duncan's multiple range test, t-test and descriptive statistics. According to the study, the evaluation of a female teacher's abilities varies with the backgrounds of both students and their parents. Among the students tested perceptions were affected by gender, grade level and type of school attended. For mothers there were differences based on age, occupation and family income.

• Journal of Fashion Business
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• v.25 no.5
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• pp.99-113
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• 2021

This study aimed to produce sensors for measuring thigh motor skills. A textile stretch sensor was manufactured using a CNT(Carbon Nano Tube) 0.1 wt% water SWCNT(Single-Walled Carbon Nano Tube) solution, and different designs were applied to increase the sensitivity of the sensor, and different GF(Gauge Factor) values were compared using UTM devices. The same design was applied to fabrics and weaves to observe changes in performance according to fibrous tissue, and the suitability of sensors was determined based on tensile strength, elongation, and the elongation recovery rate. Sensitivity was found to vary depending upon the design. Thus the manufactured sensor was attached to a pair of fitness pants as a prototype, divided into lunge position and squat position testing, and the stretch sensor was used to measure thigh movements. It was shown that stretch sensors used to measure thigh motor skills should have light and flexible features and that elongation recovery rates and tensile strength should be considered together. The manufactured stretch sensor may be applicable to various sports fields that use lower limb muscles, wearable healthcare products, and medical products for measuring athletic ability.

• Geomechanics and Engineering
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• v.35 no.1
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• pp.1-11
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• 2023

A growing trend of utilizing helical piles for soft soil strata to support infrastructure projects is currently observed in Saemangeum, South Korea. Recognized mainly due to its ease of installation and reusability proves to be far more superior compared to other foundation types in terms of sustainability. This study applies modified p-y springs to characterize the behavior of a laterally loaded helical pile with a shaft diameter of 89.1 mm affixed with 3 helices evenly spaced along its embedded length of 2.5 m. Geotechnical soil properties are correlated from CPT data near the test bed vicinity and strain gauges mounted on the shaft surface. A modification factor is applied on the p-y springs to adjust the simulated data and match it to the bending moment, soil resistance and deflection values from the strain gauge measurements. The predicted lateral behavior of the helical pile through the numerical analysis method shows fairly good agreement to the recorded field test results.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2173-2178
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• 2008

Railroad is the major factor of vibration source in railway vehicles, and it must carefully maintained the original condition to secure the safety and good ride comfort of passenger. Measuring the condition of rail irregularities such as surface, alignment, gauge, twist and cant etc is required to maintain the good performance of railroad. Currently, the various rail irregularity measurement systems(EM120, ROGER1000K and the Total Rail Irregularity Measurement system of Korea High Speed Train) are operated in Korea to estimate the rail irregularity. It is hard to verify the correlation of one rail irregularity data of a measurement system with the other, because they have been adopted different rail irregularity estimation methods. The best method securing the reliability of the irregularity data is the direct confirmation on the ground where the measurement system had detected as a fault section, but it is impossible to apply all sections simultaneously due to limitation of time, labor, cost and equipments. There is a method to secure the reliability of the data by using acceleration values. Rail irregularities, the major factor of vibration in railway vehicle, are transmitted to the vehicle acceleration through masses, springs, dampers and joints as the system dynamic formation. In this study, Transition Function has been adopted by using the rail irregularity and the acceleration value regarding as input & output parameters respectively. It has been verified by comparing the analyzed results with real measured irregularity data from the Total Rail Irregularity Measurement system of Korea High Speed Train. Also various methods has been accomplished to verify the correlation between rail irregularities and acceleration values.

• Journal of Periodontal and Implant Science
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• v.32 no.4
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• pp.865-873
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• 2002

The primary cause of tooth loss after 30 years of age is periodontal disease. Destruction of alveolar bone by periodontal disease is done by bone resorbing activity of osteoclasts. Understanding differentiation and activation mechanism of osteoclasts is essential for controling periodontal disease. The purpose of this study is to identify the possible effects of Vitamin D and cytokines affecting osteoclasts and its precursor cells. Four to six week-old mice were killed and humerus, radius, tibia and femur were removed aseptically and washed two times with Hank's solution containing penicillin-streptomycin and then soft tissue were removed. Bone marrow cells were collected by 22 gauge needle. Cells were cultured in Hank's solution containing 1 mg/ml type II collagenase, 0.05% trypsin, 41mM EDTA. Supernatant solution was removed 5 times after 15 minutes of digestion with above mentioned enzyme solution, and remained bone particles were maintained in alpha-MEM for 15 minutes and $4^{\circ}C$ temperature. Bone particles were agitated for 1 minute and supernatant solution containing osteoclast precursor cells were filtrated with cell stainer. These separated osteoclast precursor cells were dispensed with 100-mm culture dish by $1{\times}10^7$ cells unit and cultured in ${\alpha}$- MEM containing 20 ng/ml recombinant human M-CSF, 30 ng/ml recombinant human soluble osteoclast differentiation factor and 10% fetal calf serum for 2 and 7 days. Total RNA of osteoclast precursor cells were extracted using RNeasy kit. One ${\mu}g$ of total RNA was reverse transcribed in $42^{\circ}C$ for 30 minutes using SuperScriptII reverse transcriptase. Expression of transcribed receptors of each hormone and cytokine were traced with 1 ${\mu}l$ of cDNA solution by PCR amplification. Vitamin D receptor WAS found in cells cultured for 7 days. TNF-${\alpha}$ receptor was found in cells cultured for 2 days and amount of receptors were increased by 7 days. IL-1 type I receptor was not found in cells cultured 2 and 7 days. But, IL-1 receptor type II was found in cells cultured for 2 days. TGF-${\alpha},{\beta}$type I receptor was found in cells cultured 2 and 7 days, and amount of receptors were increased by 7 days of culture. These results implies Vitamin D and cytokines can affect osteoclasts directly, and affecting period in differentiation cycle of osteoclasts is different by Vitamin D and cytokines.

• Journal of Periodontal and Implant Science
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• v.29 no.1
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• pp.233-249
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• 1999

Primary fixation is one of the most important factor in establishing adequate osseointegration between implant and bone. To evaluate the initial healing response of bone around implants without primary bone contact, this study was designed to create considerable space between implant and bone in 5 mongrel dogs, about 1-year old. After 3 holes of 6.0mm in diameter were prepared at the femur neck of the dogs, commercially pure titanium thread type implants(STERI-$OSS^{(R)}$), 8mm in length and 3.8mm, 5.0mm and 6.0mm in diameter, were inserted. Implants were supported by only nonresorbable membrane($Teflon^{(R)}$), and the penetration of upper soft tissue into the gap was inhibited by it. The each implant was positioned in the center of the drilled hole. 9 implants with different diameters were inserted in 3 dogs for histologic observation, and 12 were inserted in 2 dogs for mobility test and removal torque test.Fluorescent dyes were injected in order of Doxycycline, Alizarin Red S, and Calcein at intervals of 2 weeks. At 4-, 8-, and 12-week after placement, 3 dogs were sacrificed for histologic observation, and at 8- and 12-week after placement, 2 dogs were sacrificed for mobility test using $Periotest^{(R)}$ (Simens AG, Bensheim, Germany) and torque test using Autograph AGS-1000D $series^{(R)}$(Japan). The result were as follows: 1. The wider the gap between bone and implant was, the less bone maturity was, and the later osseointegration was occurred. Trabecular direction of new bone around implant was changed from parallel to perpendicular to the implant, and the gap was filled with new bone, over time. 2. There was a decreasing tendency over time in the mobility of all implants, but the wider gap between bone and implant was, the smaller decrease of the mobility was. 3. There was a increasing tendency over time in the removal torque gauge of all implants, and the wider gap was, the smaller increase of the removal torque gauge was. The results suggest that osseointegration in case of implant without primary bone contact may be obtained by guided bone regeneration technique with prolonged healing period, but the time of second surgery should be considered carefully.