• Structural Engineering and Mechanics
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• 제71권1호
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• pp.37-43
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• 2019

This paper studies application of modified couple stress theory and first order shear deformation theory to magneto-electro-mechanical vibration analysis of three-layered size-dependent curved beam. The curved beam is resting on Pasternak's foundation and is subjected to mechanical, magnetic and electrical loads. Size dependency is accounted by employing a small scale parameter based on modified couple stress theory. The magneto-electro-mechanical preloads are accounted in governing equations to obtain natural frequencies in terms of initial magneto-electro-mechanical loads. The analytical approach is applied to investigate the effect of some important parameters such as opening angle, initial electric and magnetic potentials, small scale parameter, and some geometric dimensionless parameters and direct and shear parameters of elastic foundation on the magneto-electro-elastic vibration responses.

• International Journal of Advanced Culture Technology
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• 제11권3호
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• pp.247-252
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• 2023

The purpose of the study was to examine the mediating effect of kindergarten teachers' psychological burnout in the relationship between grit and teacher-child interactions. We conducted a cross-sectional study with 191 kindergarten teachers in South Korean. To measure the major variables, Grit scale [1], teacher-child interaction scale [2], and psychological burnout scale [3] were used. Hayes' PROCESS macro was used to test mediation effects of psychological burnout in the relationship between grit and teacher-child interactions. Indirect effects were tested using bootstrapped confidence intervals. As the results, kindergarten teachers' teacher-child interactions were found to have a significantly positive correlation with their grit but a significantly negative correlation with their psychological burnout. In addition, the relationship between grit and teacher-child interactions was mediated by psychological burnout.

• 자원ㆍ환경경제연구
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• 제15권2호
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• pp.177-200
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• 2006

최근 수확불변 하에서의 오염처리비용회피활동(pollution haven activities)에 대한 연구는 많이 진행되어 왔으나 수확체증 하에서의 연구는 미미한 실정이다. 1990년대 이후 수확체증 하에서의 교역이론이 산업 재배치에 대한 문제를 다루면서 수확체증과 오염처리비용회피활동 간의 관계를 살피는 것은 의미 있는 일이다. Davis (1998)가 발표한 수확체증 하에서의 자국시장효과(home market effect)에 대한 모형을 응용하여 환경정책이 산업 재배치에 주는 효과를 분석한 결과 시장규모가 적은 지역에서 오염물처리에 대한 책임을 생산자가 담당하는 지역과 시장규모가 크면서 오염물로 인한 비효용을 거주자가 감내하는 지역과의 교역상황에서 교역장벽이 높을 때 일부 공해산업에 대해 오염처리비용회피효과가 존재하나 교역장벽이 낮아지면서 공해산업뿐만 아니라 저공해산업에서도 산업의 지역이탈이 관찰되어 오염처리비용회피활동에 대한 식별이 힘들어지며 오염처리비용회피효과(pollution haven effect)뿐만 아니라 오염처리비용회피가설(pollution haven hypothesis)이 동시에 성립됨을 보일 수 있었다. 따라서 시장규모가 작으나 환경보전가치가 높아 환경규제가 강한 지역에서 환경보전과 지역경제발전을 동시에 도모하기 위해서는 오염처리기술의 생산성을 높이기 위한 활동이 필수적이다.

• Korean Journal of Acupuncture
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• 제28권1호
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• pp.171-177
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• 2011

Objectives : This study is designed to evaluate the effect of Hyun-Ga therapy for the scoliosis patient with Lumbago. Methods : After treatment with Hyun-Ga therapy compared with Cobb's angle and Visual Analog Scale (VAS). Results : After six treatments with Hyun-Ga therapy in one case, significant decrease in Cobb's angle and Visual Analog Scale (VAS) was observed. Conclusions : Hyun-Ga therapy might be effective for the scoliosis patient with Lumbago. It will be attempted to more patients in the future.

• Journal of Acupuncture Research
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• 제31권4호
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• pp.163-171
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• 2014

Objectives : The aim of this study was to observe the effect of needle-embedding combined with oriental medical treatment therapy on hemifacial spasm. Methods : 2 patients were treated with needle-embedding therapy with oriental medical treatment. After treatment, we evaluated the effect by Scott's scale. And we checked the satisfaction degree and side effect. Results : After treatment, the grade of spasm classified by Scott's scale was decreased and hemifacial spasm was visibly improved. Conclusions : This study showed that needle-embedding therapy with oriental medical treatment was effective to improve hemifacial spasm.

• Smart Structures and Systems
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• 제17권6호
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• pp.881-901
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• 2016

In this study, a method to compensate the effect of temperature variation on impedance responses which are used for prestress-loss monitoring in prestressed concrete (PSC) girders is presented. Firstly, an impedance-based technique using a mountable lead-zirconate-titanate (PZT) interface is presented for prestress-loss monitoring in the local tendon-anchorage member. Secondly, a cross-correlation-based algorithm to compensate the effect of temperature variation in the impedance signatures is outlined. Thirdly, lab-scale experiments are performed on a PSC girder instrumented with a mountable PZT interface at the tendon-anchorage. A series of temperature variation and prestress-loss events are simulated for the lab-scale PSC girder. Finally, the feasibility of the proposed method is experimentally verified for prestress-loss monitoring in the PSC girder under temperature-varying conditions and prestress-loss events.

• Advances in aircraft and spacecraft science
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• 제6권1호
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• pp.1-18
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• 2019

This present article represents the study of the forced vibration of nanobeam of a single-walled carbon nanotube (SWCNTs) surrounded by a polymer matrix. The modeling was done according to the Euler-Bernoulli beam model and with the application of the non-local continuum or elasticity theory. Particulars cases of the local elasticity theory have also been studied for comparison. This model takes into account the different effects of the interaction of the Winkler's type elastic medium with the nanobeam of carbon nanotubes. Then, a study of the influence of the amplitude distribution and the frequency was made by variation of some parameters such as (scale effect ($e_0{^a}$), the dimensional ratio or aspect ratio (L/d), also, bound to the mode number (N) and the effect of the stiffness of elastic medium ($K_w$). The results obtained indicate the dependence of the variation of the amplitude and the frequency with the different parameters of the model, besides they prove the local effect of the stresses.

• 천문학회보
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• 제39권2호
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• pp.74.2-74.2
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• 2014

Magnetohydrodynamics(MHD) dynamo depends on many factors such as viscosity ${\gamma}$, magnetic diffusivity ${\eta}$, magnetic Reynolds number $Re_M$, external driving source, or magnetic Prandtl number $Pr_M$. $Pr_M$, the ratio of ${\gamma}$ to ${\eta}$ (for example, galaxy ${\sim}10^{14}$), plays an important role in small scale dynamo. With the high PrM, conductivity effect becomes very important in small scale regime between the viscous scale ($k_{\gamma}{\sim}Re^{3/4}k_fk_f$:forcing scale) and resistivity scale ($k_{\eta}{\sim}PrM^{1/2}k_{\gamma}$). Since ${\eta}$ is very small, the balance of local energy transport due to the advection term and nonlocal energy transfer decides the magnetic energy spectra. Beyond the viscous scale, the stretched magnetic field (magnetic tension in Lorentz force) transfers the magnetic energy, which is originally from the kinetic energy, back to the kinetic eddies leading to the extension of the viscous scale. This repeated process eventually decides the energy spectrum of the coupled momentum and magnetic induction equation. However, the evolving profile does not follow Kolmogorov's -3/5 law. The spectra of EV (${\sim}k^{-4}$) and EM (${\sim}k^0$ or $k^{-1}$) in high $Pr_M$ have been reported, but our recent simulation results show a little different scaling law ($E_V{\sim}k^{-3}-k^{-4}$, $EM{\sim}k^{-1/2}-k^{-1}$). We show the results and explain the reason.

• Membrane and Water Treatment
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• 제3권4호
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• pp.253-266
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• 2012

In this work, the effect of hybrid salts precipitation-nanofiltration (SP-NF) process on the scale deposits in thermal and membrane desalination processes has been studied. The analysis was carried out to study the scale formation from the Arabian Gulf seawater in MSF and RO reference processes by changing the percentage of pretreatment from 0 to 100%. Four different SP-NF configurations were suggested. A targeted Top Brine Temperature (TBT) of $130^{\circ}C$ may be achieved if 30% portion is pretreated by SP and/or NF processes. As a rule of thumb, each 1% pretreatment portion increases the reference TBT of $115^{\circ}C$ by $0.6^{\circ}C$. For both MSF and RO, parallel pretreatment of certain percentage of the feed by SP and the rest by NF, showed the lowest scale values. The case showed the best values for sulfate scale prevention and the highest values of increasing the monovalent ions relative to the divalent scale forming ions. Sulfate scale is significant in MSF process while carbonate scale is significant in RO. Salt precipitation was suggested because it is less costly than nanofiltration, but nanofiltration was used here because it is efficient in sulfate ions removal.

• 한국정밀공학회지
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• 제24권3호
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• pp.108-116
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• 2007

To overcome many defects such as the high product cost, large energy consumption, and big space capacity in conventional mechanical machining, the miniaturization of machine tool and micro factory systems has been envisioned recently. The object of this paper is to research the effect of dynamic characteristic parameters in bolted-joint beams, which is widely applied to the joining of mechanical structures in order to identify structural system characteristics and to predict dynamic behavior according to scale-down from macro to micro system as the development of micro/meso-scale machine tool and micro factories. Modal parameters such as the natural frequency, damping ratio, and mode shape from modal testing and dynamic characteristics from finite element analysis are extracted with all 12 test beam models by materials, by size, and by joining condition, and then the results obtained by both methods are compared.