• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.85-88
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• 2004

In this study, a simple moment-resisting precast concrete beam-column connection is proposed for highly seismic zone using dywidag ductile rod [DDC]. DDC is superior system for ductility, energy dissipation capacity, connection strength, and drift capacity. A study was carried out to investigate the connection behavior subjected to cyclic inelastic loading. Four Precast beam-column interior connections and one monolithic connection will be tested. The variables will be examined were the strength relationship between joint's ductile rod and beam reinforcement for gain energy dissipation capacity. The specimens will be tested only reverse cyclic loading in accordance with a prescribed displacement history. Connection performance is evaluated on the basis of ductility, energy dissipation capacity, connection strength, and drift capacity. the precast connection using DDC is capable of matching of exceeding the performance of the monolithic connection and thereby provides moment-resisting behavior.

• Earthquakes and Structures
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• v.12 no.2
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• pp.201-211
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• 2017

This paper experimentally investigates the effect of yield strength of reinforcing bars and stirrups on the seismic performance of reinforced concrete (RC) circular piers. Reversed cyclic loading tests of nine-large scale specimens with longitudinal and transverse reinforcement of different yield strengths (varying between HRB335, HRB500E and HRB600 rebars) were conducted. The test parameters include the yield strength and amount of longitudinal and transverse reinforcement. The results indicate that the adoption of high-strength steel (HSS) reinforcement HRB500E and HRB600 (to replace HRB335) as longitudinal bars without reducing the steel area (i.e., equal volume replacement) is found to increase the moment resistance (as expected) and the total deformation capacity while reducing the residual displacement, ductility and energy dissipation capacity to some extent. Higher strength stirrups enhance the ductility and energy dissipation capacity of RC bridge piers. While the product of steel yield strength and reinforcement ratio ($f_y{\rho}_s$) is kept constant (i.e., equal strength replacement), the piers with higher yield strength longitudinal bars are found to achieve as good seismic performance as when lower strength bars are used. When higher yield strength transverse reinforcement is to be used to maintain equal strength, reducing bar diameter is found to be a better approach than increasing the tie spacing.

• PNF and Movement
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• v.16 no.2
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• pp.187-194
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• 2018

Purpose: This study aimed to assess the effect of rowing ergometer training on the aerobic capacity and strength of male high school students over a 12-week period. Methods: Fourteen high school students volunteered to participate in the study. The subjects were divided into two groups: seven subjects in the experimental group and seven in the control group. The subjects in the experimental group performed rowing ergometer training for 75 min per session at three days a week for 12 weeks. The exercise intensity set the maximum heart rate (HRmax) from 40% to 80%. Aerobic capacity was measured by ventilation, cardiac output, and oxygen intake per body weight. Strength was measured by grip strength and back strength before and after training. Results: A significantly increased ventilation (p=0.01), cardiac output (p=0.01), and oxygen intake per body weight (p=0.00) were found in the experimental group. A significantly increased grip strength in the right and left hands (p=0.00, 0.00) and back strength (p=0.04) were observed in the experimental group. Conclusion: Rowing ergometer training can be an effective combined exercise for aerobic capacity and strength of high school students.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.13-21
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• 2019

Purpose : The purpose of this study was to investigate the effect of abdominal muscle strengthening exercise on abdominal muscle strength and respiratory function in stroke patients. Methods : The subjects were 14 stroke patients (10 males, 4 females) hospitalized at W rehabilitation hospital in Busan City and randomly assigned to 7 exercise groups and 7 control groups. Exercise was performed in combination with an upper and lower extremity pattern of proprioceptive neuromuscular facilitation. Measurements of abdominal muscle strength and respiratory function were made before intervention and 4 weeks after intervention. Abdominal muscle strength was assessed using a digital manual dynamometer, and respiratory function was assessed by spirometry. The collected data were analyzed with a paired t-test and independent t-test and the significance level was set as α =.05. Results : The results showed that applying abdominal muscle strengthening exercise to stroke patients showed a significant increase in abdominal muscle strength and a significant difference between groups (p<.05). Maximal-effort expiratory spirogram (MES) readings were significantly increased in forced vital capacity (FVC), and forced expiratory volume in one second (FEV₁), in the exercise group, and there were a significant differences between the groups in terms of FEV1 (p<.05). Slow vital capacity (SVC) was significantly increased in vital capacity (VC), tidal volume (TV), inspiratory reserve volume (IRV), and expiratory capacity (EC), and there were significant differences between the groups in VC, TV, expiratory reserve volume (ERV), EC, and inspiratory capacity (IC) (p<.05). Conclusion : Abdominal muscle strengthening exercise was effective in the abdominal muscle strength of stroke patients, and it was confirmed to have a positive effect on the enhancement of respiratory function. Therefore, it seems that exercise programs for stroke patients with respiratory weakness should include abdominal muscle strengthening exercises.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1001-1010
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• 2009

The study that unconfined compression strength of intact rock which is the most important factor to determine the bearing capacity effects discontinuities in rock mass has been carried out actively so far. However, the study which is related to lithological characters such as vesicle which is one of the primary characteristics of Basalt has barely been conducted. On this study, We have analyzed the correlation-ship between vesicle and unconfined compression strength and the effect on the bearing capacity, based on the reviewing on the changes of unconfined compression strength as the amount of vesicle of Basalt. It is impossible to analyze the amount of vesicle of Basalt as measuring unit. So it was analyzed by the ratio of the core sample's surface area and another area that vesicle takes up. Also, unconfined compression strength was calculated by point load test and unconfined compression strength test. The analysis shows that vesicle area ratio and unconfined compression strength have the exponential relationship and vesicle area ration is the factor to determine the bearing capacity of Basalt. It is considered that the reliability of calculating of the bearing capacity of Basalt will be improved as we study the correlation-ship between the vesicle area ratio and rock mass grade hereafter.

• Computers and Concrete
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• v.2 no.1
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• pp.79-96
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• 2005

The use of high-strength concrete (HSC) has significantly increased over the last decade, especially in offshore structures, long-span bridges, and tall buildings. The behavior of such concrete is noticeably different from that of normal-strength concrete (NSC) due to its different microstructure and mode of failure. In particular, the shear capacity of structural members made of HSC is a concern and must be carefully evaluated. The shear fracture surface in HSC members is usually trans-granular (propagates across coarse aggregates) and is therefore smoother than that in NSC members, which reduces the effect of shear transfer mechanisms through aggregate interlock across cracks, thus reducing the ultimate shear strength. Current code provisions for shear design are mainly based on experimental results obtained on NSC members having compressive strength of up to 50MPa. The validity of such methods to calculate the shear strength of HSC members is still questionable. In this study, a new approach based on artificial neural networks (ANNs) was used to predict the shear capacity of NSC and HSC beams without shear reinforcement. Shear capacities predicted by the ANN model were compared to those of five other methods commonly used in shear investigations: the ACI method, the CSA simplified method, Response 2000, Eurocode-2, and Zsutty's method. A sensitivity analysis was conducted to evaluate the ability of ANNs to capture the effect of main shear design parameters (concrete compressive strength, amount of longitudinal reinforcement, beam size, and shear span to depth ratio) on the shear capacity of reinforced NSC and HSC beams. It was found that the ANN model outperformed all other considered methods, providing more accurate results of shear capacity, and better capturing the effect of basic shear design parameters. Therefore, it offers an efficient alternative to evaluate the shear capacity of NSC and HSC members without stirrups.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.38-45
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• 2005

This research was investigated on the increase in strength capacity among different five wood-to-wood connections. Group using small diameter bolts with equal area loss has the highest increase in strength capacity, secondly the group inserted plywood, thirdly the group used glued bolt, and lastly the group inserted rubber plate. These groups showed at least 10% increase in strength capacity more than existing connection groups. Therefore, these results can be applied to develop the new highly efficient connection. To select suitable connection configuration and materials, however, economical advantage and increase in strength capacity and the difficulty should be considered by the additional works.

• Journal of Convergence for Information Technology
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• v.11 no.8
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• pp.73-83
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• 2021

Due to the rapid development of technology compared to the past, it is becoming difficult for companies to survive in a fiercely competitive environment if they do not innovate. In order for a company to carry out innovative activities, it is very important to find new knowledge, digest it, and secure its own technological capabilities. In this study, the causal relationship between exploration and exploitation activities, technology innovation capacity, innovation performance(technical performance, product performance), absorptive capacity, and innovation performance was identified. As a result of the analysis, exploration and exploitation activities were found to affect technology innovation capacity, and technology innovation capacity, absorptive capacity, and innovation strength were found to affect innovation performance. In addition, it was found that absorptive capacity and innovation strength play a mediating role between technology innovation capacity and innovation performance. The results of this study are expected to be useful as guidelines when planning or carrying out innovation activities in companies.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.59-62
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• 2003

Kinds, shapes and fraction ratios of fibers have influence on properties of HPFRCC(High-Performance Fiver Reinforced Cementitious Concrete ) like bending strength, strain capacity and fracture toughness. For example, hydrophilic fibers have different chemical bond strength from hydrophobic fibers, fiber shapes influence on fiber pull-out and rupture, and fiber volume fraction influence on bending strength. In this study, to estimate influences of kinds, shapes and fraction ratios of fibers, we make HFRCC with 3 kind of fiber in various volume fraction of fiber and compare cracking, bending strength and fracture toughness. As the results, bending strength of HPFRCC was increased as fiber volume fraction was Increase and fiber tensile strength was increase, and strain capacity and fracture toughness of HFRCC was higher in fiber pull-out fracture than in fiber rupture fracture. And HFRCC showing pseudo strain hardening has higher fiber reinforce efficiency than others.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.460-467
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• 1997

Compared to normal-strength concrete, high-strength concrete has the lower lateral expansion capacity caused by the higher elastic modulus and the lower internal crack characteristic. Therefore, the effect of the lateral confining action of hoops appears slowly and also in inefficient Nevertheless. it has been reported that the strength and deformation capacity of high-strength concrete is improved by well-distributed hoops. Due to that argument, this investigation has been compared and analyzed by the experimental works on the deformation capacity and the confinement mechanism of high-strength concrete shear wall of the high-rise building reinforced by rectangular steel tubes and rectangular hoops at both edges of the shear wall.