• 대한물리치료과학회지
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• 제17권3_4호
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• pp.29-39
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• 2010

Purpose: The purpose of this study was to examine the effect of foot position and lifting an object on muscle activity and foot pressure during sit to stand(STS) in hemiparetic patients. Methods: Fourteen patients participated in this study. Surface electromyography was used to collect muscle activity and foot pressure measurement system was used to analyze foot pressure in hemiparetic side. Three different foot position was assumed(anterior, neutral, posterior) in hemiparetic side. The repeated two-way analysis of variance and multiple comparisons were conducted to determine statistical significance with a significance level of 0.05. Results: The results were as follows. 1) Lower extremity muscle activity was significantly higher(p<0.05) in biceps femoris and tibialis anterior muscle during STS without holding an object. With changing positions of the affected foot, muscle activity was significantly increased (p<0.05) in vastus medialis and lateral gastrocnemius when the foot was positioned in posterior. 2) There was no significant difference(p>0.05) in foot pressure during STS with object holding and foot positioning. Conclusion: Muscle activity showed a significant increase when the foot was positioned in posterior in comparison to the muscle activity when the foot was in neutral or anterior position.

• 구강회복응용과학지
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• 제17권2호
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• pp.113-123
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• 2001

The success of complete denture prosthesis is to satisfy three basic requirements for the edentulous patient : maximum comfort, efficiency, and esthetic appearance. This can be achieved only if the dentures are both stable and retentive. When the residual alveolar ridge has resorbed significantly, stability and retention are more dependent on the correct position of the teeth and external surfaces of the denture. The stability and retention of the denture can be improved by locating the denture in the neutral zone and reproducing exact mandibular border movement for balanced occlusion. The neutral zone philosophy is based upon the concept that there exists a specific area where the musculature function will not unseat the denture in the mouth. In here, forces generated by the tongue are neutralized by the forces generated by the lips and cheeks. One of the simplest methods for recording border movements in three dimensions is to make stereographic record of condylar movement. Stereographs are made in the mouth during mandibular movement with intraoral clutches and central bearing point, and used in dictating the condylar movement on the articulator later by generating the condylar paths in doughy acrylic resin. Its procedure is simpler and more convenient than that of Pantograph. In this clinical report, we introduce the concept of neutral zone and stereograph in complete denture fabrication.

• 천문학회지
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• 제53권6호
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• pp.169-179
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• 2020

Emission features formed through Raman scattering with atomic hydrogen provide unique and crucial information to probe the distribution and kinematics of a thick neutral region illuminated by a strong far-ultraviolet radiation source. We introduce a new 3-dimensional Monte-Carlo code in order to describe the radiative transfer of line photons that are subject to Raman and Rayleigh scattering with atomic hydrogen. In our Sejong Radiative Transfer through Raman and Rayleigh Scattering (STaRS) code, the position, direction, wavelength, and polarization of each photon is traced until escape. The thick neutral scattering region is divided into multiple cells with each cell being characterized by its velocity and density, which ensures flexibility of the code in analyzing Raman-scattered features formed in a neutral region with complicated kinematics and density distribution. To test the code, we revisit the formation of Balmer wings through Raman scattering of the far-UV continuum near Lyβ and Lyγ in a static neutral region. An additional check is made to investigate Raman scattering of O vi in an expanding neutral medium. We find a good agreement of our results with previous works, demonstrating the capability of dealing with radiative transfer modeling that can be applied to spectropolarimetric imaging observations of various objects including symbiotic stars, young planetary nebulae, and active galactic nuclei.

• Wind and Structures
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• 제22권4호
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• pp.429-454
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• 2016

In this paper, a shear deformation plate theory based on neutral surface position is developed for free vibration analysis of functionally graded material (FGM) plates. The material properties of the FGM plates are assumed to vary through the thickness of the plate by a simple power-law distribution in terms of the volume fractions of the constituents. During manufacture, defects such as porosities can appear. It is therefore necessary to consider the vibration behavior of FG plates having porosities in this investigation. The proposed theory is based on assumption that the in-plane and transverse displacements consist of bending and shear components, in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments. The neutral surface position for a functionally graded plate which its material properties vary in the thickness direction is determined. The equation of motion for FG rectangular plates is obtained through Hamilton's principle. The closed form solutions are obtained by using Navier technique, and then fundamental frequencies are found by solving the results of eigenvalue problems. Numerical results are presented and the influences of the volume fraction index and porosity volume fraction on frequencies of FGM plates are clearly discussed.

• 대한치과교정학회지
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• 제45권4호
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• pp.198-208
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• 2015

Objective: To quantify, for each activation, the effect of preactivations of differing distribution and intensity on the neutral position of T-loops (7-mm height), specifically the horizontal force, moment to force (M/F) ratio, and load to deflection ratio. Methods: A total 100 loops measuring $0.017{\times}0.025$ inches in cross-section were divided into two groups (n = 50 each) according to composition, either stainless steel or beta-titanium. The two groups were further divided into five subgroups, 10 loops each, corresponding to the five preactivations tested: preactivations with occlusal distribution ($0^{\circ}$, $20^{\circ}$, and $40^{\circ}$), gingival distribution ($20^{\circ}$), and occlusal-gingival distribution ($40^{\circ}$). The loops were subjected to a total activation of 6-mm with 0.5-mm iterations. Statistical analysis was performed using comprised ANOVA and Bonferoni multiple comparison tests, with a significance level of 5%. Results: The location and intensity of preactivation influenced the force intensity. For the M/F ratio, the highest value achieved without preactivation was lower than the height of the loop. Without preactivation, the M/F ratio increased with activation, while the opposite effect was observed with preactivation. The increase in the M/F ratio was greater when the preactivation distribution was partially or fully gingival. Conclusions: Depending on the preactivation distribution, displacement of uprights is higher or lower than the activation, which is a factor to consider in clinical practice.

• Geomechanics and Engineering
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• 제10권3호
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• pp.357-386
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• 2016

In this research work, an exact analytical solution for thermal stability of solar functionally graded rectangular plates subjected to uniform, linear and non-linear temperature rises across the thickness direction is developed. It is assumed that the plate rests on two-parameter elastic foundation and its material properties vary through the thickness of the plate as a power function. The neutral surface position for such plate is determined, and the efficient hyperbolic plate theory based on exact neutral surface position is employed to derive the governing stability equations. The displacement field is chosen based on assumptions that the in-plane and transverse displacements consist of bending and shear components, and the shear components of in-plane displacements give rise to the quadratic distribution of transverse shear stress through the thickness in such a way that shear stresses vanish on the plate surfaces. Therefore, there is no need to use shear correction factor. Just four unknown displacement functions are used in the present theory against five unknown displacement functions used in the corresponding ones. The non-linear strain-displacement relations are also taken into consideration. The influences of many plate parameters on buckling temperature difference will be investigated. Numerical results are presented for the present theory, demonstrating its importance and accuracy in comparison to other theories.

• Safety and Health at Work
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• 제11권4호
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• pp.458-465
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• 2020

Background: The aim of this study was to analyze the interaction between neck and/or wrist pain and hand grip strength (HGS) and to investigate factors (age, sex, neck disorders, and carpal tunnel syndrome) influencing the HGS of industrial quality proofing workers (N = 145). Methods: Standardized questionnaires [Neck Disability Index (NDI), Boston Carpal Tunnel Questionnaire] were used to evaluate existing neck and/or wrist pain. HGS measurements were performed in different wrist positions. Results: Significant differences between participants with and without neck pain were found in different wrist positions, in neutral wrist position right [without neck pain (n = 48) 46.34 (43.39 - 49.30); with neck pain (n = 97) 38.46 (36.20 - 40.72), F_(1,144) = 16.82, p < 0.001, ŋ_p² = 0.11] and left [without neck pain 44.06 (41.19 - 46.94); with neck pain 37.36 (35.13 - 39.58), F_(1,144) = 12.70, p < 0.001, ŋ_p² = 0.08]. A significant difference between participants with and without wrist pain was found for neutral wrist position right [without wrist pain (n = 105) 42.53 (40.37 - 44.70); with wrist pain (n = 40) 37.24 (33.56 - 40.91), F_(1,144) = 6.41, p = 0.01, ŋ_p² = 0.04]. Regression analysis showed significant results especially for steps two (age and weight, NDI) and three (age and weight, NDI, Boston Carpal Tunnel Questionnaire) for neutral position right (R² = 0.355, R² = 0.357, respectively). Conclusion: Neck pain has an impact on HGS but should be evaluated in consideration of age and sex.

• 대한치과보철학회지
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• 제28권1호
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• pp.123-135
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• 1990

It would be of importance to determine the neutral Tone by a resultant axis of relation on relation to the mandible in understanding the biomechanics of the mandibular movement. In this study, the neutral zone at the habitual opening and closing mandibular movements is the shape of the paths described by a minimum moving point occured as an average center of the determined instantaneous centers of rotation. Twenty, aged $23{\sim}25$, male dental students without Temporomandibular disorders and with normal occlusion clinically were selected for the study. The habitual opening and closing mandibular movements were recorded by the Gnathorecouder and analyzed by the computer program of a planer rigid body model and the determined method of a minimum moving point. The results obtained from this study were as follows. 1. The minimum moving points were placed in the body of the mandible except two subjects. 2. The mean of maximum displacements of a minimum moving point was $0.62{\pm}0.08cm$ on X-axis and $0.73{\pm}0.16cm$ on y-axis. 3. The mean of maximum displacements of a minimum moving point was $3.39{\pm}0.62cm$ 4. The position and shape of the neutral zone were determined by the position, displacements, and moving distances of a minimum moving point.

• 마이크로전자및패키징학회지
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• 제23권2호
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• pp.79-84
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• 2016

유연전자소자가 외부힘에 의해 변형될 경우 반도체 다이가 기계적 응력 때문에 변형되거나 파괴되고 이러한 변형이나 파괴는 channel의 전자이동도를 변화시키거나 배선의 저항을 증가시켜 집적회로의 동작 오류를 발생시킨다. 따라서 반도체 집적회로는 굽힘 변형이 발생해도 기계적 응력이 발생하지 않는 중립축에 위치하는 것이 바람직하다. 본 연구에서는 굽힘변형을 하는 flip-chip 접합공정이 적용된 face-down flexible packaging system에서 중립축의 위치와 파괴 모드를 조사하였고 반도체 집적회로와 집중응력이 발생한 곳의 응력을 감소시킬 수 있는 방법을 제시하였다. 이를 위해, 설계인자로 유연기판의 두께 및 소재, 반도체 다이의 두께를 고려하였고 설계인자가 중립축의 위치에 미치는 영향을 조사한 결과 유연기판의 두께가 중립축의 위치를 조절하는데 유용한 설계인자임을 알 수 있었다. 3차원 모델을 이용한 유한요소해석 결과 반도체 다이와 유연기판 사이의 Cu bump 접합부에서 항복응력보다 높은 응력이 인가될 수 있음을 확인하였다. 마지막으로 flexible face-down packaging system에서 반도체 다이와 Cu bump 의 응력을 감소시킬 수 있는 설계 방법을 제안하였다.

• 한국산학기술학회논문지
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• 제13권3호
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• pp.1229-1237
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• 2012

본 연구는 파악력의 강도가 두 가지 팔 자세에서 어깨근육 근활성도에 어떠한 영향을 미치는지 알아보기 위하여 실시되었다. 건강한 성인 22명(남 11명, 여 11명)을 대상으로 실시하였고, 4가지 파악력(최대 파악력의 0%, 30%, 50%, 70%)을 팔의 중립 자세와 팔 $90^{\circ}$ 거상 자세에서 적용 했을 때 상승모근, 하승모근, 극하근, 전삼각근, 후삼각근의 근활성도를 표면 근전도를 이용하여 측정하였다. 팔 중립 자세에서는 파악력의 강도에 따라 극하근, 전삼각근, 후삼각근이 유의한 차이를 보였고(p<0.05), 팔 $90^{\circ}$ 거상 자세에서는 전삼각근, 후삼각근이 유의한 차이를 보였다(p<0.05). 본 연구의 결과, 2가지 팔의 자세에서 각각 파악력의 강도에 따라 어깨근육 근활성도가 변화됨을 확인하였다. 손 쥐기 과제를 중립자세에서 실시할 경우 어깨관절 안정근인 극하근이 활성화되고, 팔 $90^{\circ}$ 거상 자세에서는 삼각근을 억제된다는 점을 고려하여, 손을 사용하는 작업 시 인간공학적 접근으로 어깨 손상의 예방과 손상 후 재활 훈련 시 효율적인 전략으로 사용할 수 있을 것으로 여겨진다.