• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.154-157
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• 2004

With the need of high-speed and mass data transmission, optical communication system requires the growth of optical components. Waveguide photodiodes(WGPDs) are introduced and circuit models of WGPD and submodule are required for the optical receiver application. In this paper, the circuit models of WGPD and submodule are investigated and modeling results are derived by PEEC methodology. The s-parameters are measured for the test structures of WGPD and submodule and the equivalent circuit models are examined. The modeling results agreed well with the measured data and can present a reasonable physical representation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.282-287
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• 1996

The non-linear torsional vibrations of the propulsion shafting system with viscous damper are considered. The motion is modeled by non-linear differential equations of second order. the equivalent system is modeled by two mass softening system with Duffing's oscillator. The steady state response of a equivalent system is analyzed for primary resonance only. Harmonic balance method as a non-linear vibration analysis technique is used. Jump phenomena are explained. The primary unstable region obtained by the Mathieu equation is investigated. Both theoretical and measured results of the propulsion shafting system are compared with and evaluated. As a result of comparisons with both data, it was confirmed that Duffing's oscillator can be used as a analysis method in the modeling of the propulsion shafting system attached viscous damper with non-linear stiffness.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.8-8
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• 1992

The study of magnetic properties of ferro and ferri-magnetic materials has shown that, due to their different time constants, magnetisation mechanisms (domain wall displacement, spin rotation and wall bulging) can be separated by using the complex permeability formalisms, they exhibit characteristic features in $\mu$′ versus $\mu$" plots. In many cases. the elements (inductances, resistances and capacitances) of the equivalent circuit representing the friquency behaviour, can also be associated with physical parameters of the sample [1-3]. In a different approach, domain wall dynamics can be represented by a motion equation with mass, damping and restoring force terms [4]. In this paper, we show that these two approaches are consistent and how they are related.

• Steel and Composite Structures
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• v.44 no.5
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• pp.685-690
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• 2022

In this paper, the equivalent material properties of cellular metamaterials with different types of perforations have been presented using finite element (FE) simulation of tensile test in Abaqus commercial software. To this end, a Representative Volume Element (RVE) has been considered for each type of cellular metamaterial with regular array of circular, square, oval and rectangular perforations. Furthermore, both straight and perpendicular patterns of oval and rectangular perforations have been studied. By applying Periodic Boundary conditions (PBC) on the RVE, the actual behavior of cellular material under uniaxial tension has been simulated. Finally, the effective Young's modulus, Poisson's ratio and mass density of various metamaterials have been presented as functions of relative density of the RVE

• Korean Journal of Adult Nursing
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• v.25 no.5
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• pp.539-548
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• 2013

Purpose: The purpose of this study was to investigate the effect of supplemental vitamin D on the physiological indices, muscle mass, and physical functions of aged women. Methods: A non-equivalent pretest-posttest design was used. The participants were 65 elderly women with low serum vitamin D levels. This study was conducted for 12 weeks. The experimental group (n=34) received vitamin D and regular exercise whereas the control group (n=31) received only regular exercise. The data were analyzed by the IBM PASW Statistics (SPSS) 19.0 program. Results: Serum vitamin D (U=0.00, p<.001), parathyroid hormone (U=99.50, p<.001) and calcium (U=250.50, p<.001) levels were significantly increased in the experimental group after the intervention. The experimental group showed significantly increased scores of muscle mass, strength, physical balance, and gait compared to those of the control group. Conclusion: Vitamin D supplementation improved physiological indices, muscle mass, and physical functions. In addition, this program may help to prevent disorders of the musculoskeletal system in aged women.

• Journal of Korean Biological Nursing Science
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• v.12 no.1
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• pp.1-7
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• 2010

Purpose: This research is to promote an walking exercise program for the subjects to continue exercise by mitigating stresses with increase in increase their physiological index. Methods: The research design was a non-equivalent control group, quasiexperimental study. The research has been executed from August 1st to September 30th 2008 by operating walking exercise program to 50 subjects. Only 24 patients who continued this program to the last were could be investigated. Results: Among the subjects who participated in the program had shown significant differences in weight and BMI. Despite of an insignificant change in skeletal muscle mass, fat mass, body fat ratio and WHR, average value for skeletal muscle mass showed an increasing tendency, while the average values for fat mass, body fat ratio and WHR showed a decreasing tendency. Conclusion: In conclusion, walking exercise program was design for the subjects to be able to exercise without an extra cost for a special tool to exercise with an positive effect on increasing health problem.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.8 s.197
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• pp.81-88
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• 2007

This paper presents the development of a new inchworm actuation system using the shearing deformation of the piezoelectric actuators. In this new actuation system, piezoelectric shearing/expanding actuators, an inertial mass and an advanced preload system are configured innovatively to generate the motion of an inertial mass. There are two modes in the new actuation system: (1) stick mode, and (2) clamp mode. In stick mode, the deformation of the piezoelectric shearing actuators drives an inertial mass by means of the friction force at their contact interface. On the other hand, in clamp mode, the piezoelectric expanding actuators provide the gripping force to an inertial mass and, as a result, eliminate its backward motion following the rapid backward deformation of the piezoelectric shearing actuators. To investigate the feasibility of the proposed new actuation system, the experimental system is built up, and the static performance evaluation and dynamic analysis are conducted. The open-loop performance of the linear motion of the proposed new actuation system is evaluated. In dynamic analysis, the mathematical model for the contact interface is established based on the LuGre friction model and the equivalent parameters are identified.

• Journal of Korean Academy of Nursing
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• v.46 no.2
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• pp.249-259
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• 2016

Purpose: The purpose of this study was to examine the effects of auricular acupressure on reducing obesity in adult women with abdominal obesity. Methods: The study design was a non-equivalent control group pretest-posttest design. Participants were 58 women, aged 20 years or older, assigned to the experimental group (n=30) or control group (n=28). Auricular acupressure using vaccaria seeds was administered to the experimental group. The sessions continued for 8 weeks. Outcome measures included body weight, abdominal circumference, and body mass index, body fat mass, body fat percentage, triglyceride, total cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol, and serum glucose. Results: Women in the experimental group showed significant decreases in body weight (t=6.19, p<.001), abdominal circumference (t=4.01, p<.001), and body mass index (t=2.58, p=.006) after 8 weeks compared with those in the control group. Conclusion: Results show that auricular acupressure using vaccaria seeds was effective in decreasing body weight, abdominal circumference, body mass index, and triglyceride levels in adult women with abdominal obesity.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.60-65
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• 2016

Dynamic performance of transmission has a substantial effect on dynamic performance and fuel efficiency of a vehicles. Dynamic performance of transmission and mass moments of inertia of transmission gears are related directly each other. Then a smaller amount of kinetic energy from vehicles that repeat acceleration and deceleration requires lighter rotating part in transmission. It is going to increases fuel efficiency as a result. In this study, equivalent inertia moments of inertia at different speeds were calculated by simplifying the transmission system. To find out lightening effect at low speed level gear on fuel efficiency, the powerflow of transmission was analyzed. And the lightning effect of the rotating parts in transmission is compared with the mass reduction of sprung parts in vehicle.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.545-552
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• 2006

Small-scale models have been frequently used for seismic performance tests because of limited testing facilities and economic reasons. However, there are not also enough studies on similitude law for analogizing prototype structures accurately with small-scale models, although conventional similitude law based on geometry similitude is not well consistent in their inelastic seismic behaviors. When fabricating prototype and small-scale model of reinforced concrete structures by using the same material, added mass is demanded from a volumetric change and scale factor could be limited due to aggregate size. Therefore, it is desirable to use different materials for small-scale model. In our recent study, a modified similitude law was derived depending on geometric scale factor, equivalent modulus ratio and ultimate strain ratio. And quasi-static and pseudo-dynamic tests on the specimens are carried out using constant and variable modulus ratios, and correlation between prototype and small-scale model is investigated based on their test results. In this study, tests on scaled model of different concrete compressive strength aye carried out. In shaking table tests, added mass can not be varied. Thus, constant added mass on expected maximum displacement was applied and the validity was verified in shaking table tests. And shaking table tests on non-artificial mass model is carried out to settle a limitation of acceleration and the validity was verified in shanking table tests.