• Structural Engineering and Mechanics
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• 제42권1호
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• pp.1-12
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• 2012

In this study, Pasternak foundation model, which is a two parameter foundation model, is used to analyze the behavior of laterally loaded beams embedded in semi-infinite media. Total potential energy variation of the system is written to formulate the problem that yielded the required field equations and the boundary conditions. Shear force discontinuities are exposed within the boundary conditions by variational method and are validated by photo elastic experiments. Exact solution of the deflection of the beam is obtained. Both foundation parameters are obtained by self calibration for this particular problem and loading type in this study. It is shown that, like the first parameter k, the second foundation parameter G also depends not only on the material type but also on the geometry and the loading type of the system. On the other hand, surface deflection of the semi infinite media under singular loading is obtained and another method is proposed to determine the foundation parameters using the solution of this problem.

• 한국전문물리치료학회지
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• 제23권3호
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• pp.29-39
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• 2016

Background: In the treatment of temporomandibular joint (TMJ) disorder, the goals of traditional physical therapy are not only to reduce the inflammatory process leading to pain, but also to decrease joint overload and muscle hyperactivity. To achieve those goals, physical therapists generally use a photo-therapy, joint mobilization, and massage. Objects: To examine the impact of an unloading technique using non-elastic taping on the pain, opening mouth, functional level, and quality of life in patients with TMJ disorder. Method: Twenty patients with TMJ disorder were included in this study and randomly divided into the experimental ($n_1$=10), and control ($n_2$=10) groups. Traditional physical therapy including massage and stretching for 30 min was performed in both groups. Non-elastic taping was performed in the experimental group after traditional physical therapy, and they were recommended to keep the tape attached for 12 hours. Outcomes for pain, functional level, and quality of life were measured using a survey. The opening mouth was measured using a general ruler. Result: Significant differences were observed in the pain level, opening mouth, functional level, and quality of life after the intervention and on follow-up in both groups. However, we found that while the levels of all parameters were maintained throughout the follow-up period in the experimental group, the functional status level was not maintained throughout the follow-up period in the control group. Conclusion: Our unloading technique using non-elastic tape results comparable to those achieved by traditional physical therapy in the treatment of TMJ. However, the unloading taping method using non-elastic tape is more effective than traditional physical therapy in maintaining the impact of intervention.

• Structural Engineering and Mechanics
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• 제82권4호
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• pp.469-476
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• 2022

A mathematical model of Lord-Shulman photo-thermal theorem induced by pulse heat flux is presented to study the propagations waves for plasma, thermal and elastic in two-dimensional semiconductor materials. The medium is assumed initially quiescent. By using Laplace-Fourier transforms with the eigenvalue method, the variables are obtained analytically. A semiconductor medium such as silicon is investigated. The displacements, stresses, the carrier density and temperature distributions are calculated numerically and clarified graphically. The outcomes show that thermal relaxation time has varying degrees of effects on the studying fields.

• 오토저널
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• 제3권2호
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• pp.27-33
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• 1981

In the paper, it was attempted to verify how the strength around fillet area of shifted gear would be affected by variables such as number of teeth, shifted value, and diametral pitch. Thereafter, the Lewis' tooth factor of the shifted gear was computed in terms of previously mentioned variables in order to observe the characteristics of stress change related from tooth factor and tooth number with the parameter of shifted values and diametral pitches. From the results of quasi-theoretical values by Finite Element Method(F.E.M.)and experimental values through the photo-elastic tests, the followings were identified. The more the number of gear teeth increased, the more the profile of the tooth became close to that of rack, and accordingly the stresses in the fillet area decreased significantly in certain range. Furthermore, as the shifted value and pressure angle increase the stresses tend decrease. Moreover, the stresses analyzed by F.E.M. in the filled area became around 1.22 times larger than the stresses computed by Lewis' form factor, and this is supposed as on influence of the stress concentration in fillet area.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.48-53
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• 2004

This paper suggested the method determing the stress intensity factor (SIF) for functionally gradient materials (FGMs) by photo elastic experimental method. The SIF for the center crack in a finite rectangulat plate with a linear variation of shear modulus with constant density and Poisson's ratio along the direction of the crack under mode I static loading is obtained. The exponential and linear variation of stress fields are used for obtaining the SIF. The greater crack length, the increaser the difference of the SIF between right and left side crack tip.

• Journal of Biosystems Engineering
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• 제15권3호
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• pp.177-185
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• 1990

The break of rotary blade is occured from a stress concentration of the inside of blade by the outside impulsive load. In order to examine its inside stress and stress concentration of rotary blade, a epoxy plate which is suitable to applicate by photoelastic system is used to experiment. These results are summarized as follow. 1. Refer to the existence of bolt hole and a size of its of rotary blade, a stress concentration which cause the break of rotary blade is not exposed. 2. It is expected to be break to section of hold of rotary blade and the break of this is due to that there are concentrated by shearing force, bending moment and bending stress. 3. When the crack which caused from processing are set up to any location, the stress concentration taken to the creak point. 4. Without regard to the location of the reaction points of rotary blade, the bending stress which is greated than the bending moment is occured within about 6 em toward the center line of bolt hole and it was possible to break that section.

• 한국결정학회지
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• 제5권2호
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• pp.51-66
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• 1994

융액인상법으로 Y3Al5O12 및 Nd: Y3Al5O12단결정을 육성하였다. 인상속도, 회전속도 및 Nd3+이온의 주입농도가 결정의 품질에 미치는 영향을 분석하였다. 광탄성효과및 화학부식 법을 이용하여 여러가지 종류의 결함을 검출하 고, 육성된 결정의 분광학적 성질과 레이저 기능성을 조사하였다. 양질의 단결정을 육성하기 위한 인상속도는 Nd3+이온의 주입농도에 따라 달라진다. Y3Al5O12단결정은 2∼4mm/hr, Nd3+이온 주입농도가 3.0∼3.5a/o 일때 0.6∼0.5mm/hr,4.Oa/o 이상일 때 04mm/hr 이하가 적당하였다. 회전속도가 27∼60rpm 일때 볼록하고, 80∼100rpm 일 때 오목한 고액계면을 형성하였다. 육성된 결정은 <111> 방위로 성장되었으며 격자상수는 12.Ol7A로 측정되었다. 결함으로서 core, (211)facet 줄무의, 금속입자 함유물, 전위 및 광학적 불균질상이 검출되었다. Y3AlO12단결정에 대한 Nd3+이온의 4준위 레이저 천이과정을 확인하고, 육성된 결정으로부터 직경 4.0mm 길이 63mm크기의 레이저 발진봉을 제조한 후 레이저 공진한 결과 lasing threshould 1.8lJ, slope efficiency 0.49%로 측정되었다.