• Computers and Concrete
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• v.18 no.1
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• pp.139-154
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• 2016

Since the concrete strength around the reinforcement rebar affects the tension stiffening, the tension stiffening effect of ultra high performance concrete on the concrete members reinforced by steel rebar is examined by testing the specimens with circular cross section with the length 850 mm reinforced by a steel rebar at the center of a specimen's cross section in this research. Conducting a tensile test on the specimens, the cracking behavior is evaluated and a curve with an exponential descending branch is obtained to explain the post-cracking zone. In addition, this paper proposes an equation for this branch and parameters of equation is obtained based on the ratio of cover thickness to rebar diameter (c/d) and reinforcement percentage (${\rho}$).

• The Korean Journal of Physiology
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• v.9 no.1
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• pp.13-22
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• 1975

From the study of movements of $Ca^{++}$ in frog cardiac muscle, Niedergerke (1963) postulated that $Ca^{++}$ necessary for the cardiac contraction is stored in a specific pool. Langer et al (1967) and DeCaro (1967) also found a close relationship between the change of $Ca^{++}$ flux kinetics and the change of contractile force. According to the studies of several investigators, Ca II (Bailey and Dressel 1968) or phase I and II (Langer 1965, Langer et al 1967, 1971) in the $Ca^{++}$ washout curve was associated with cardiac contractility. This investigation was aimed to elucidate the anatomical region of the contractile active $Ca^{++}$ pool. At the same time, it was assumed in this study that $Ca^{++}$ in the sarcoplasmic reticulumn represents one of the major intracellular $Ca^{++}$ pool and cardiac contractility was also dependent on the intracellular $Ca^{++}$ concentration. Consequently, this experiment was performed at different temperatures to activate to activate inhibit the deactivating process of activated $Ca^{++}$ in the intracellular space to see if changes in the contractility decay curve existed at different temperatures. The isolated hearts of rabbits and turtles (Amyda maackii) were attached to the perfusion apparatus according to the method employed by Bailey and Dressel (1968). The isolated hearts were initally perfused with a full Ringer solution containing 2 mg/ml of inulin for 1 hr, and then $Ca^{++}$ and inulin-free Ringer solution was perfused while the isometric tension was recorded and a serial sample of perfusion fluid dripping from the cardiac apex was collected for 10 sec throughout experimental period. The above procedure was performed at $23^{\circ}C$, $30^{\circ}C$ and $38^{\circ}C$ on the rabbit heart and $10{\sim}13^{\circ}C$, $10^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$ and $35^{\circ}C$ on the turtle heart. After determination of $Ca^{++}$ and inulin concentration of the samples, the $Ca^{++}$, inulin washout curve and the contractile tensin decay curve were analysed according to the method of Riggs (1963). The results were summarized as follows; 1. In the rabbit heart, there are 2 inulin compartments, 3 $Ca^{++}$ compartments and sing1e exponential decay of contractile tension. In the turtle heart, there are $1{\sim}2$ inulin compartments, $1{\sim}2$ $Ca^{++}$ compartments and $1{\sim}2$ phases of contractile tension decay. The fact that the inulin space was divided into 3 compartments in the washout curve in these hearts indicates the presence of heterogeneity in cardiac perfusion, i.e., overfused and underperfused area. 2. Ca I a9d Ca II in these hearts were found to have $Ca^{++}$ in the ECF compartments because their half times in the washout curves were far smaller than those of the inulin washout curves in the rabbit heart and similar to those of the inulin washout curves in the turtle heart. Ca III in the rabbit heart may have originated from the intracellular $Ca^{++}$ store. But no Ca III in the turtle heart was found. This may be due to the fact that the iutracellular $Ca^{++}$ pool in the turtle heart was too small to detect using this experimental procedure since sarcoplasmic reticulumn in the turtle heart is poorly developed. 3. In the rabbit heart, there were no chages in the half time of Ca I, Ca II, inulin I and inulin II at different temperatures, but the half time of Ca III was significantly prolonged at lower temperatures, and the half time of the contractile tension decay tended to be prolonged at lower temperatures but this was not significant. In the turtle heart, there were no changes in the half time of Ca I, Ca II, inulin 1, inulin II and phase I of the contractile tension decay at different temperatures, but the half time of phase II of the contractile tension decay was significantly prolonged at lower temperatures. This finding indicates that intracellu!ar $Ca^{++}$ in these hearts was also responsible particulary for maintaining the cardiac contractility at the lower temperatures. 4. The half times of contractile tension decay were shorter than those of Ca II in the $Ca^{++}$ washout curves in both animal hearts. According to the above results it was shown that $Ca^{++}$ in ECF is primarily and $Ca^{++}$ in the intracellular space is partially associated with the cardic contractility.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.4
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• pp.275-280
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• 2009

Purpose：We have investigated to analysis biomechanics for pinch strength due to elbow flexion degree. Methods：Pinch strength was measured by Electro Dynamometer(G-100) using four elbow flexion degree ($0^{\circ}$, $45^{\circ}$, $90^{\circ}$, $135^{\circ}$). Results：In experimental results, we found that pinch strengths were 5.4kg($0^{\circ}$), 4.8kg($45^{\circ}$), 5.6kg($90^{\circ}$) and 5.2kg($135^{\circ}$), respectively. The Pinch strengths got maximum at $90^{\circ}$ degree, minimum at $45^{\circ}$ degree. We have calculated F1 values using $\sum$T=0. As a result F1 values were 540N($0^{\circ}$), 480N($45^{\circ}$), 560N($90^{\circ}$) and 520N($135^{\circ}$), respectively. F1 values got maximum at $90^{\circ}$ degree, minimum at $45^{\circ}$ degree. Data curve line of $F_1$ values was increased in 45~90 section and decreased in 0~45, 90~135 sections, respectively. Conclusion：$F_1$ (Flexor digitorum superficialis and profundus) values were 10 times bigger than pinch strengths. Data curve line of $F_1$ values was similar to active length-tension curve in 45~90, 90~135 sections.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.475-476
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• 2009

• Journal of Acupuncture Research
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• v.21 no.2
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• pp.183-203
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• 2004

Objective : Tension-type headache is the most common headache. The objective of this study is to find the clinical manifestation of tension-type headache and correlation with autonomic bioelectric response. Methods : This observation was carried out on 60 patients with tension-type headache. We used headache questionnaire and the Autonomic Bioelectric Response recoder(ABR-2000) for this study. Results : 1. Distribution of sex & age : male : female=5 : 7, 50s&60s group (28.3%) 2. Duration of onset : over 5years(50%), over one years(83.4%) 3. Causes of illness : stress(58.3%), severe fatigue(53.5%), tension(33.3%) 4. Time of attack : irregular(56.7%), day time(16.7%) 5. Pattern of pain: heavy(31 people), stiffness of occipital region (27 people) tightening around the head(25 people) 6. Curve : 40%, 56.7%, 35.0% SL(Slope low) at peak 1, 2, 3/ SH&SI not found 7. Regulation : 16.7% RR(Regulation reverse) at peak 1, 25% RH(Regulation high) at peak 2, 15% RR(Regulation reverse) at peak 3 8. Graph : Activity-60.0%, 70.0%, 63.3% lowered reaction(L, LR, L!) at peak 1, 2, 3 Reactivity-83.3%, 95.0%, 93.3% lowered reaction at peak 1, 2, 3 Conclusion : We find tension-type headache has remarkable relativeness with autonomic bioelectric response.

• Journal of the Korean Chemical Society
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• v.8 no.1
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• pp.1-4
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• 1964

Relative surface tensions of aqueous solutions of KCl, KI and NaI have been measured at 25$^{circ}C$(30$^{circ}C$ for KCl) over a concentration range of 0.0001 to 3M solution. It was observed that there was a minimum in the surface tension-concentration curve for the extremely dilute solutions. Appearance of the minimum has been reported for the other salt solutions so far reported. At moderate and high concentration, these three salts increase the surface tension of water almost linearly as concentration increased, and behaved as a typical "capillary inactive substance", whereas they acted as a capillary active substance in very dilute solutions. Since the Onsager-Samaras equation for the surface tension as a function did not agree with the experimental data, the following empirical equations for the whole concentration range used were obtained. ${\sigma}_r\;=\;1\;+\;0.00072{\sqrt{c}}\;-\;0.0011c\;+\;0.023c^2\; for\;KCl\;at\;30^{\circ}C$ ${\sigma}_r\;=\;1\;+\;0.0077{\sqrt{c}}\;-\;0.0015c\;+\;0.024c^2\;for\;KI\;at\;25^{\circ}C$ ${\sigma}_r\;=\;1\;+\;0.00011{\sqrt{c}}\;-\;0.0090c\;+\;0.077c^2\;for\;NaI\;at\;25^{\circ}C$

• International Journal of Ocean System Engineering
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• v.1 no.3
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• pp.171-179
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• 2011

This paper presents the concept design procedure of a floating-type combined renewable energy platform based on hydrodynamic analyses and is focused on the fatigue design of taut-type mooring lines of the platform. Two types of combined renewable energy platforms are considered: a combination of wind turbine, wave turbine and photovoltaic energy plant and a combination of wind turbine, current turbine and photovoltaic energy plant. The basic configurations are conceptually determined from the understanding of floating offshore plants, while the main dimensions have been determined based on a hydrostatic calculation. Fully coupled hydrodynamic analyses have been carried out to identify the motion characteristics of the floating body and the tension histories of the mooring lines. The tension history is used for the fatigue life prediction based on the rain-flow cycle counting method. For the fatigue life prediction, tension life curves from API and the Palmgren-Miner rule are employed.

• Computers and Concrete
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• v.4 no.5
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• pp.403-424
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• 2007

The investigation of corrosion effects on the tensile behavior of reinforced concrete (RC) members is very important in region prone to high corrosion conditions. In this article, an experimental study concerning corrosion effects on tensile behavior of RC members is presented. For this purpose, a comprehensive experimental program including 58 cylindrical reinforced concrete specimens under various levels of corrosion is conducted. Some of the specimens (44) are located in large tub containing water and salt (5% salt solution); an electrical supplier has been utilized for the accelerated corrosion program. Afterwards, the tensile behavior of the specimens was studied by means of the direct tension tests. For each specimen, the tension stiffening curve is plotted, and their behavior at various load levels is investigated. Average crack spacing, loss of cross-section area due to corrosion, the concrete contribution to the tensile response for different strain levels, and maximum bond stress developed at each corrosion level are studied, and their appropriate relationships are proposed. The main parameters considered in this investigation are: degree of corrosion ($C_w$), reinforcement diameter (d), reinforcement ratio (${\rho}$), clear concrete cover (c), ratio of clear concrete cover to rebar diameter (c/d), and ratio of rebar diameter to reinforcement percentage ($d/{\rho}$).

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.381-388
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• 1988

The heights of the towers of a ropeway are theoretically derived and the result is experimentally verified. The accuracy in the equation of deflection angle obtained by applying the characteristics of catenary curve was confirmed through experiment. By applying these equations the optimal values of the tower heights could be obtained because the deflection angles trade off each other. The deflection angle was measured by using the curve fitting technique.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.4
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• pp.441-450
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• 1983

A reasonable J-resistance curve determination procedure is suggested by correcting the amount of overestimation in J-value whose effect becomes significant when crack grows. Experiments using compact tension specimens of an alloy steel (SCM4, K.S. Designation) are performed. The value of J estimated according to this procedure is compared with that as obtained from the method by Merkle and Corten. The conditions for J controlled crack growth proposed by Hutchinson and Paris are examined for the material used here. It appears that J resistance curve, which is independent of crack ratio can be obtained for those specimens satisfying the conditions of J controlled crack growth.