• Korean Journal of Crystallography
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• 제14권1호
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• pp.7-12
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• 2003

The compound SrA1₂(BO₃)₂O is a good host lattice for negative thermal expansion. We have measured thermal expansion over the limited temperature range by X-ray diffraction and ceramic dilatometry. In the aluminum borate compound, a thermal contraction is observed with a coefficient -1.64×10/sup -4/ Å/℃ on the c axis in the temperature range 23∼215℃ and with a maximum change -1.75㎛ in length of a ceramic bar of 20㎜ in the temperature range 110∼170℃, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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• pp.73-76
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• 2009

Autogenous shrinkage of high-strength mass concrete is affected high temperature history. So to evaluate autogenous shrinkage of high-strength mass concrete accurately, thermal expansion in it should be removed. In this study, compensated autogenous shrinkage was calculated after gathering thermal expansion coefficient at early age experimentally. As a result of the study. Autogenous shrinkage of mass specimen (300 ${\times}$ 300 ${\times}$ 300mm) was remarkably higher than it of standard specimen (100 ${\times}$ 100 ${\times}$ 400mm). So it was found that compensation on thermal expansion should in evaluating autogenous shrinkage of high-strength mass concrete. And this study shows results on opc and similar own contraction, if used retarder.

• International Journal of Concrete Structures and Materials
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• 제18권3E호
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• pp.145-150
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• 2006

An experiment with the objective of providing guidelines for joint depth determination and timing of contraction joint sawcutting to avert uncontrolled cement concrete pavement cracking has been conducted. Theoretical analysis and laboratory tests were performed to help in understanding and analyzing the field observation. Using two-dimensional elastic fracture mechanics, the influence of several parameters on crack propagation was delineated by a parametric study, involving initial notch ratio, joint spacing, Young's modulus and thermal expansion coefficient of concrete, temperature gradient, and modulus of subgrade reaction. Bimaterials made of rock plus cement mortar and rock plus polymer mortar were applied to the concrete in a field test section, and they were subjected to fracture tests. These tests have shown that fracture mechanics is a powerful tool not only in judging the quality of the jointed cement concrete pavement but also in providing a criterion for crack propagation and delamination. Based on fracture mechanics, a method is proposed to determine the joint depth, sawcut timing, and spacing of the jointed cement concrete pavement. This method has successfully been applied to a test section in Seohaean expressway. This study also summarizes the research results obtained from a field test for jointed plain concrete pavement, which was also carried out on the Seohaean expressway.

• Journal of Korean Physical Therapy Science
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• 제9권1호
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• pp.167-175
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• 2002

Functional Electrical Stimulation is the clinical application of a small electric current to the intact nerves of the body, in order to trigger a muscle contraction. This contraction is then incorporated into a functional activity, for example walling. A clear distinction needs to be made between therapeutic stimulation and functional stimulation. The former being of an exercise orientation, where one would relax while the stimulation works on its own. Functional electrical stimulation on the other hand, incorporates this elicited muscle movement into an everyday activity, like standing, walking, reaching out etc. But recently, New method used to FES which updated electrode insult in muscle and small nerve branch. A lot of new research build up many countries such as England, USA, Japan, Spain, Canada. So I had been write this paper for introduce new FES method, and I hope to more enhanced motivation of therapist for the functional electric stimulation.

• Journal of the Korean Society for Precision Engineering
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• 제26권5호
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• pp.135-141
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• 2009

The bearing clearance is influenced by shrink fit and thermal expansion during operation. The designer must take into account the reduction of clearance after installation to the interference fits, and thermal expansion must be considered. The purpose of this study is to grasp the internal clearance variation and behavior of a bearing which is a deep connected with fatigue life of bearing and performance of spindle through FEM(Finite Element Method). Finite element analysis is performed by using commercial code ANSYS according to variation of thermal condition and rotational speeds. This paper presents correct negative internal clearance according to temperature during operation. Furthermore, interrelation between thermal expansion and contraction are presented to maintain adequate contact force for three type of spindle system (HSK-A60, HSK-40E, HSK-32E). The influence of the centrifugal force and Internal clearance variation of bearing is studied to operating rotational speed.

• Korean Journal of Human Ecology
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• 제7권3호
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• pp.15-33
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• 2004

A precise understanding of the human form in static pose serves as the basis of designing clothing. When the human body is in motion, however, even an article of clothing designed to fit the human form in static pose can pull and change, thus restricting the body. In order to increase the fit of the clothing, which may be termed the second skin, its form and measurements therefore must be determined in correlation not only with the formal characteristics of the human body, in static pose but also with its functional characteristics in motion, as caused by the movements of the human body. In this study, the motion factor was selected as the primary basis for designing slacks with good fit in both static and moving states. By indentifying the areas in which lower limb movement cause significant changes in body surface lines, we suggest several application methods for designing slacks. Using unmarried female university students aged 18 - 24 as subjects, a total of 32 body surface categories (15 body surface lines and 17 body surface segment lines) were measured in one static and 9 movement poses. In particular, expansion and contraction levels and rates were measured and used in the analysis. The analysis first involved the calculation of the average measurement per body part in body surface line in static pose as well as of the average expansion and contraction levels and rates in 9 lower limb movements. Two-way MANOVA and multiple comparison analysis (Tukey) were conducted on movements and individual somatotypes regarding measurement per body part and expansion and contraction rates. Body parts whose measurements of body surface lines differed significantly in body surface line in static pose versus in movement were then identified. The results of this study are as follows. First, changes in body surface lines caused by lower limb movements were significant in all body surface lines of the lower trunk, both horizontal and vertical, with the exception of abdomen girth, midway thigh girth, ankle girth, hip length, and posterior knee girth. Second, significantly expanded 10 body surface lines in moving pose were detected and illustrated in table 4. These body parts should be studied in designing or pattern designing, especially for close-fitting pants, in using stretch fabric, and in sensory evaluation of good fit during movement.

• Economic and Environmental Geology
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• 제42권5호
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• pp.509-512
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• 2009

Powder diffraction patterns of the zeolite mesolite ($Na_{5.33}Ca_{5.33}Al_{16}Si_{24}O_{80}{\cdot}21.33H_2O$), with a natrolite framework topology were measured as a function of pressure up to 5.0 GPa using a diamond-anvil cell and a $200{\mu}m$-focused monochromatic synchrotron X-ray. Under the hydrostatic conditions mediated by pore-penetrating alcohol and water mixture, the elastic behavior of mesolite is characterized by continuous volume expansion between ca. 0.5 and 1.5 GPa, which results from expansion in the ab-plane and contraction along the c-axis. Subsequent to this anomalous behavior, changes in the powder diffraction patterns suggest possible reentrant order-disorder transition. The ordered layers of sodium- and calcium-containing channels in a 1:2 ratio along the b-axis attribute to the $3b_{natrolite}$ cell below 1.5 GPa. When the volume expansion is completed above 1.5 GPa, such characteristic ordering reflections disappear and the $b_{natrolite}$ cell persists with marginal volume contraction up to ca. 2.5 GPa. Further increase in pressure leads to progressive volume contraction and appears to generate another set of superlattice reflections in the $3c_{natrolite}$ cell. This suggests that mesolite in the pressure-induced hydration state experiences order-disorder-order transition involving the motions of sodium and calcium cations either through cross-channel diffusion or within the respective channels.

• The Korean journal of sports medicine
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• 제36권4호
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• pp.197-206
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• 2018

Purpose: This study analyzed the muscle activity changes induced by motions of reaching forward and chest expansion that were examined from the bilateral muscles with rectus abdominis, external oblique, multifidus, and longissimus thoracic using Pilates cadillac instrument. Methods: Nine young adult women, who have no musculoskeletal disorder and any of chronic diseases, were participated. Surface electromyography system was used for recording of all signals produced by muscles, and then normalized as percentage of maximum voluntary isometric contraction (%MVIC). The paired t-test and repeated measures of analysis of variance was performed. Results: Reaching-forward motion showed a higher muscle activity from non-dominant external oblique muscle than that of the chest-expansion motion. During both reaching-forward motion and chest-expansion motion, MVIC values collected from dominant side of external oblique muscle were shown a significantly lower than the values obtained from non-dominant side (p<0.05). Conversely, %MVIC values in external oblique muscle collected from dominant side showed a significantly higher than the values obtained from non-dominant side of the same oblique muscle (p<0.05). Reaching-forward motion was caused a higher %MVIC on non-dominant external oblique muscle than that of the chest-expansion motion (p<0.05). Regardless of dominant or non-dominant sides, external oblique muscle was shown the highest activation rate of all the other muscles during reaching forward action, and longissimus thoracic muscle was shown the highest activation rate of all the other muscles during chest expansion action. Conclusion: Reaching-forward motion is suitable for activating an external oblique muscle, and chest-expansion motion is an effective enough in activating of longissimus thoracic muscle.

• Journal of the Korean Ceramic Society
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• 제40권2호
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• pp.109-112
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• 2003

The grain-boundary microcracking materials in the system $Al_2$TiO$_{5}$ -ZrTiO$_4$(ZAT) is influenced by the thermal expansion anisotropy. The range of ZAT compositions investigated had showed very low thermal expansions of 0.3~1.3$\times$10$^{-6}$ K loin compared to 8.29$\times$10$^{6}$ K of pure ZrTiO$_4$and 0.68$\times$10$^{6}$ K of polycrystalline $Al_2$TiO$_{5}$ , respectively, compared with the theoretical thermal expansion coefficient for a single crystal of $Al_2$TiO$_{5}$ , 9.70$\times$10$^{6}$ K. The low thermal expansion and microcraking temperature are apparently due to a combination of thermal contraction and expansion caused by the large thermal expansion anisotropy of the crystal a ies of the $Al_2$TiO$_{5}$ phase.

• Journal of the Korean Ceramic Society
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• 제40권3호
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• pp.317-321
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• 2003

The grain-boundary microcracking materials in the system A1$_2$Ti $O_{5}$ -ZrTi $O_4$(ZAT) is influenced by the thermal expansion anisotropy. The range of ZAT compositions investigated had showed very low thermal expansions of 0.3~1.3$\times$10$^{-6}$K compared to 8.29$\times$10$^{-6}$K of pure ZrTi $O_4$and 0.68$\times$10$^{-6}$K of polycrystalline A1$_2$Ti $O_{5}$ , respectively, compared with the theoretical thermal expansion coefficient for a single crystal of A1$_2$Ti $O_{5}$ , 9.70$\times$10$^{-6}$K. The low thermal expansion and microcraking temperature are apparently due to a combination of thermal contraction and expansion caused by the large thermal expansion anisotropy of the crystal axes of the A1$_2$Ti $O_{5}$ phase.