• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.15-21
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• 2010

The transported probability density function(PDF) model has been applied to simulate the turbulent nonpremixed piloted jet flame. To realistically account for the mixture fraction PDF informations on the turbulent non-premixed jet flame, the present Lagrangian PDF transport approach is based on the joint velocity-composition-turbulence frequency PDF formulation. The fluctuating velocity of stochastic fields is modeled by simplified Langevin model(SLM), turbulence frequency of stochastic fields is modeled by Jayesh-Pope model and effects of molecular diffusion are represented by the interaction by exchange with the mean (IEM) mixing model. To validate the present approach, the numerical results obtained by the joint velocity-composition-turbulence frequency PDF model are compared with experimental data in terms of the unconditional and conditional means of mixture fraction, temperature and species and PDFs.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.55-60
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• 2002

$100 A/mm^2$ class Bi-2223 tapes have recently become commercially available. Some important characteristics of the tapes, e .g. critical current, ac loss, characteristics at joint, fault current characteristics, are required for an application such as a power cable or a power transformer. In this paper they have been investigated experimentally. The results indicate that the self-field loss of the high current density tapes is not negligible, compared to resistive loss in a copper wire for the same currents. In a cable, the self-field loss for relatively large currents is much larger than the magnetization loss due to an external field. But in a transformer, the magnetization loss is dominant, compared to the self-field loss. Finally the fault current characteristics show that the high current density tapes are never safe from burn-out even for fault currents with a few cycles.

• Journal of Mechanical Science and Technology
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• v.15 no.1
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• pp.44-51
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• 2001

One of the recent issues in design of the spot-welded structure such as the automobile body is to develop an economical prediction method of the fatigue design criterion without additional fatigue test. In this paper, as one of basic investigation for developing such methods, fracture mechanical approach was investigated. First, the Model I, Mode II and Mode III, stress intensity factors were analyzed. Second, strain energy density factor (S) synthetically including them was calculated. And finally, in order to decide the systematic fatigue design criterion by using this strain energy density factor, fatigue data of the ΔP-N(sub)f obtained on the various in-plane bending type spot-welded lap joints were systematically re-arranged in the ΔS-N(sub)f relation. And its utility and reliability were verified by the theory of Weibull probability distribution function. The reliability of the proposed fatigue life prediction value at 10(sup)7 cycles by the strain energy density factor was estimated by 85%. Therefore, it is possible to decide the fatigue design criterion of spot-welded lap joint instead of the ΔP-N(sub)f relation.

• Journal of muscle and joint health
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• v.12 no.1
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• pp.48-56
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• 2005

Purpose: This study was measured to the bone mineral density(BMD) and biochemical bone markers in young women in order to identify the relationship between bone mineral density and biochemical bone markers. Methods: Forty two healthy young women were enrolled. BMD were checked Dual Energy X-ray Absorptiometry and biochemical bone markers were checked ELSA-OSTEO(CIS bio international, France)analyzed kit, Pyrilinks-D(Metra Biosystems Inc., U.S.A)analyzed kit. Data were analyzed with frequencies, percentages, means, and Pearson correlation coefficients. Results: 1) Young women forearm(radius & ulnar) BMD was $0.55g/cm^2$, lumbar($1{\sim}4$) BMD was $0.92g/cm^2$, neck of femur BMD was $0.75g/cm^2$, trochanter of femur BMD was $0.61g/cm^2$, ward's triangle of femur BMD was $0.68g/cm^2$. In biochemical bone marker, Osteocalcin was 21.94ng/ml, Deoxypyridinoline was 11.94nmol/nmolCr. 2) There was no significant correlation between BMD and biochemical bone markers. Conclusion: Results not indicated association between bone mineral density and biochemical markers. As seen in the small sample, future research on BMD and biochemical markers need to studies to the large sample.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.2
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• pp.289-300
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• 2010

Purpose : This study was to explore the effects of knee joint taping exercise on muscle strength, bone mineral density, pain and IGF-1 in blood of elderly women with knee Osteoarthritis. Methods : Thirty elderly women with knee osteoarthritis were divided into three groups: the taping with exercise group (n=10), the regular exercise group (n=10) and control group (n=10). Participants' muscle strength, bone mineral density, pain and IGF-1 in blood were measured three times : before exercise, after 6 weeks, and after 12 weeks. Results : Participants in both exercise (taping & non-taping) groups showed improvement in muscle strength, bone mineral density, pain and IGF-1 in blood after 6 and 12 weeks compared to before exercise. In particular, the taping exercise group had a greater effect on muscle strength than the regular exercise group. Conclusion : Both exercise programs considerably improved muscle strength, bone mineral density, reduced pain and IGF-1 in blood in elderly women with knee Osteoarthritis. The knee joint taping exercise is perhaps a better exercise to improve muscle strength than the regular exercise in treating elderly women with knee Osteoarthritis

• Journal of muscle and joint health
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• v.19 no.3
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• pp.350-361
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• 2012

Purpose: The purpose of this study is to explore the level of bone mineral densities of the femur neck and to identify factors affecting bone mineral density of the femur in Parkinson's disease (PD) patients. Methods: Participants were 121 PD patients visiting the outpatient clinic of D University Hospital in B City. Bone mineral density was measured at the femur neck by using a dual-energy x-ray absorptiometry. The serum vitamin D level, the amounts of milk intake, caffeine intake, cigaret smoking, and alcohol consumption, and the number of steps taken daily were measured. Past and present disease history, the medication history, and duration of the disease were also collected. The level of disability was obtained by neurologists using the Hoehn and Yahr stage and the Unified Parkinson's Disease Rating Scale. Results: Among PD patients, 57% had osteopenia and 15.7% had osteoporosis. The bone mineral density of the femur was associated with weight, serum vitamin D level, age, and working status. Conclusion: The identification of weight and serum vitamin D level as important predictive factors emphasizes the importance of balanced nutrition for PD patients.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.320-320
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• 2016

Nanocrystalline Carbon thin films have numerous applications in different areas such as mechanical, biotechnology and optoelectronic devices due to attractive properties like high excellent hardness, low friction coefficient, good chemical inertness, low surface roughness, non-toxic and biocompatibility. In this work, we studied the comparison of pure DC power and pulsed DC power in plasma sputtering process of carbon thin films synthesis. Using a close field unbalanced magnetron sputtering system, films were deposited on glass and Si wafer substrates by varying the power density and pulsed DC frequency variations. The plasma characteristics has been studied using the I-V discharge characteristics and optical emission spectroscopy. The films properties were studied using Raman spectroscopy, Hall effect measurement, contact angle measurement. Through the Raman results, ID/IG ratio was found to be increased by increasing either of DC power density and pulsed DC frequency. Film deposition rate, measured by Alpha step measurement, increased with increasing DC power density and decreased with pulsed DC frequency. The electrical resistivity results show that the resistivity increased with increasing DC power density and pulsed DC frequency. The film surface energy was estimated using the calculated values of contact angle of DI water and di-iodo-methane. Our results exhibit a tailoring of surface energies from 52.69 to $55.42mJ/m^2$ by controlling the plasma parameters.

• Journal of the Optical Society of Korea
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• v.14 no.3
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• pp.228-234
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• 2010

This paper presents the joint characteristic function of the first- and second-order polarization-modedispersion (PMD) vectors in installed optical fibers that are almost linearly birefringent. The joint characteristic function is a Fourier transform of the joint probability density function of these PMD vectors. We regard the random fiber birefringence components as white Gaussian processes and use a Fokker-Planck method. In the limit of a large transmission distance, our joint characteristic function agrees with the previous joint characteristic function obtained for highly birefringent fibers. However, their differences can be noticeable for practical transmission distances.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.10 no.1
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• pp.30-36
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• 2003

Purpose: The strength of hand grip, low back muscles and knee joint muscles were measured and then compared to the bone mineral density (BMD) of each forearm bones (including ulna and radius), lumbar spine, and femur in young women in order to identify the relationship between muscle strength and bone mineral density. Method: The BMD was measured with a Dual Energy X-ray Absorptiometry and muscle strength was measured with a handgrip dynamometer and a Cybex Norm. Data were analyzed with frequencies, percentages, means, and Pearson correlation coefficients. Result: 1) Higher grip strength correlated positively with higher BMD in the forearm (r=.246, p=.007), higher low back extensor strength with higher BMD in the femur (neck, trochanter and Ward's triangle)($r=.323{\sim}.226$, $p=.003{\sim}.043$) and higher strength in the knee joint extensor with higher BMD in the lumbar spine (r=.227, p=.041), femur neck, and femur trochanter significantly ($r=.295{\sim}.226$, $p=.007{\sim}.043$). There was no significant correlation between the strength of low back extensors and BMD in the lumbar spine, now with strength of knee joint flexor and the BMD in the femur. 2) The muscle strength of each part of the body had significant positive correlations to each other part ($r=.255{\sim}.728$ $p=.021{\sim}.000$) Conclusion: The results of this study showed that with the development of a muscle there was an increased BMD of the corresponding part, and the BMD of each part was influenced by adjacent muscles. To promote the health of bones, it is important to strengthen the muscles of related bones, based on balanced development of all muscles.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.1
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• pp.55-63
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• 2019

In engineering problems, many random variables have correlation, and the correlation of input random variables has a great influence on reliability analysis results of the mechanical systems. However, correlated variables are often treated as independent variables or modeled by specific parametric joint distributions due to difficulty in modeling joint distributions. Especially, when there are insufficient correlated data, it becomes more difficult to correctly model the joint distribution. In this study, multivariate kernel density estimation with bounded data is proposed to estimate various types of joint distributions with highly nonlinearity. Since it combines given data with bounded data, which are generated from confidence intervals of uniform distribution parameters for given data, it is less sensitive to data quality and number of data. Thus, it yields conservative statistical modeling and reliability analysis results, and its performance is verified through statistical simulation and engineering examples.