• Korean Journal of Agricultural Science
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• 제37권3호
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• pp.465-469
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• 2010

In order to develop effective recycling technologies of disused railway wood ties, wood properties and residual creosote oil of wood ties were investigated. Among the total 50 wood ties, 32 wood ties were identified as tropical hardwood tree, such as, Keruing (Dipterocarpus spp.), Kempas (Koompassia malaccensis), Kapur (Dryobalanops spp.) Naytoh (Palaquium rostratum), and so on. Disused wood ties showed mostly sound structure without degradation of cell walls by decay fungi. Disused wood ties showed high strengths of bending and compressive parallel to grain because degradation of wood properties was hardly occurred in use under exterior condition. Disused railway wood ties had relatively poor depth of penetration and residual of creosote oil because of refractory wood structures. These results suggest that disused railway wood ties may be useful as recycling wood wastes.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.501-506
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• 1999

The purpose of this study is to experimentally investigate the strength and ductility of reinforced high strength concrete columns under uniaxial load and several test variables. To do this, we have conducted tests on thirteen 20$\times$20$\times$60cm specimens with 8 and 12 longitudinal steel bars subjected to monotonic uniaxial compression. The main variables considered in this test are the configuration of ties, the space the ties, the diameter of ties and yield strength of ties. The results indicate that the strength and the ductility of reinforced high strength concrete columns have been influenced on these variables except yield strength of ties. Judging from test results, real stress of ties at peak concrete stress is suitable variable than yield strength of ties for estimation of the strength gain factor(Ks).

• Journal of the Korea Concrete Institute
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• 제12권1호
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• pp.53-60
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• 2000

The objective of this study is to investigate the flexural behavior of reinforced concrete columns confined by lateral ties. This test was carried on the twelve reinforced concrete columns subjected to lateral and constant axial loads. The main experimental variables are concrete strength, the configuration of lateral ties, and the amount of lateral ties. Test results indicated that the steel configuration in column sections plays an important role in column behavior, and a proper configuration of lateral ties can obtain more ductile by the reduction of the space of lateral ties. Also, this experiment show that the utlization of high-strength concrete in columns properly designed on ACI Code takes less ductile. Therefore, we can conclude that the design of high-strength concrete columns under high axial loads requires more lateral ties than ACI Code.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.601-604
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• 1999

The objective of this study is to investigate the flexural behavior of reinforced concrete columns confined by lateral ties. This test was carried on the twelve reinforced concrete columns, 200$\times$200$\times$800mm size. objected to flexure and constant axial loads. The main variables are concrete strength, the configuration of lateral ties and the amount of lateral ties. Test results indicated that steel configuration plays an important role in column behavior, and a proper configuration of lateral ties can be more ductile than the reduce of the space of lateral ties. By this experiment, the ductility of high-strength concrete columns designed on A.C.I Code is not adequate, and are concluded that the design of high-strength concrete column is executed by more lateral ties under high axial loads.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.157-158
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• 2017

This tests examined bond stress-slip relationship of V-ties embedded into concrete as a supplementary lateral reinforcement proposed for ductility of concrete flexural members. The different leg shapes of V-ties were prepared as a test parameter. The V-tie with pressed end-legs exhibited 28% higher bond strength than the conventional V-ties, whereas bond stress-slip curves were insignificantly affected by the embedment length of V-ties.

• Journal of Families and Better Life
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• 제26권6호
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• pp.1-20
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• 2008

This study investigates the influences of factors such as type and degree of family leisure among parents with five day work weeks on adolescents' perceived family strengths. Its findings are based on questionnaires collected from 525 male and female parents of middle school students. Factor analysis and MANOVA were employed for data analysis and $Scheff{\acute{e}}$ tests for post-hoc analysis. The main findings were as follows. First, adolescents whose parents work five days a week were at a higher level than other adolescents in terms of finances, family ties, communication, and social ties. Second, there were no significant differences concerning adolescents' family strength by type of family leisure. Third, adolescents with more family leisure activities scored higher than others in the areas of manageable strengths, financial levels, family ties, communication, and family social ties. Fourth, among families following the five day working system, adolescents who had more family leisure activities scored higher than the others in regards to manageable strengths, financial levels, family ties, communication, and family social ties. Additionally, where adolescents thought they had fewer family leisure activities, family-oriented adolescents tended to be engaged in higher physical-activity-oriented and hobby-oriented activities in relation to manageable strengths, financial level, family ties, and communication and hobby-oriented adolescents engaged in higher than average amounts of physical-activity, strengthening family social ties in the process. Fifth, concerning families not adhering to the five day working system, adolescents who had more family leisure activities scored higher than others in terms of manageable strengths, financial levels, family ties, communication, and family social ties. As the above results indicate, family leisure activities appear to be a key factor influencing family strength. Therefore, further support should be extended toward developing new forms of family leisure and additional studies should be devoted to the subject.

• Journal of Korea Trade
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• 제26권4호
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• pp.39-62
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• 2022

Purpose - Along with the growing awareness of environmental sustainability, international green entrepreneurship is expected to realize international sustainable development (ISD) by introducing ecological innovation results, using fewer resources consumption, and reducing negative environmental impacts. Building upon contingency theory and social network theory, this paper attempts to explore the role of home country-based networks (technology ties and business ties) as contingent factors that might impact the effectiveness of entrepreneurial orientation (EO) in promoting ISD among green ventures. Design/methodology - Original data were collected from 127 green ventures in China based on the random sampling technique. These green ventures mainly focus on the lower use of energy or materials, lower CO2 emissions, and higher ecological benefits located in the Fujian province, which highlights green economic growth and economic cooperation with international markets. Moderated hierarchical linear regression analysis was conducted to test our hypotheses concerning the main relationship between EO (innovativeness, proactiveness, and risk-taking) and ISD as well as the moderating effects of home country-based networks (technology ties and business ties) on the main relationship. Findings - Empirical results indicate that: first, both innovativeness and proactiveness positively affect ISD; second, both technology ties and business ties at home might significantly strengthen the positive relationship between innovativeness (or proactiveness) and ISD. However, this study did not find significant moderating effects of technology ties or business ties at home on the relationship between risk-taking and ISD. Originality/value - Since previous literature often gives more focus on the host country context of social networks, this study shifts to a home country-based network context. Therefore, our research might enrich the international green entrepreneurship literature by empirically investigating the contingent value of home country-based networks in the relationship between EO and ISD in the context of an emerging economy such as China.

• Journal of the Korea institute for structural maintenance and inspection
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• 제6권2호
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• pp.245-253
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• 2002

This study was focused on the effect of concrete strength and lateral ties of concrete columns using high-strength concrete. Thirty-six concrete columns with 20cm square cross-section were tested. Experimental parameters included the concrete strength, the distribution of longitudinal bars and the volumetric ratio, yield strength, spacing of lateral ties. From the experiments, we found that: 1) the increasing rate of the strength and ductility of concrete columns caused by confinement of lateral ties was decreasing, as the concrete strength increased. 2) The high volumetric ratio and the reduction of tie spacing had a tendency to enhance the strength and improve the ductility. 3) The high-strength concrete columns required high volumetric ratio of lateral ties to maintain the proper strength and ductility. It was observed that the current AIK design code to specify the maximum tie spacing of high-strength concrete columns led to the poor strength and ductility for seismic design.

• Structural Engineering and Mechanics
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• 제18권2호
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• pp.151-166
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• 2004

The interaction between concrete core expansion and deformation of perimeter ties has been known to have a significant effect on the effective confinement of rectangular reinforced concrete (RC) tied columns. This interaction produces passive confining pressure to the concrete core. Most existing models for determining the response of RC tied columns do not directly account for the influence of flexural stiffness of the ties and the variation of confining stress along the column height. This study presents a procedure for determining the confined compressive strength of RC square columns confined by rectilinear ties with various tie configurations considering directly the influence of flexural flexibility of the ties and the variation of confining stress along the vertical direction. The concept of area compatibility is employed to ensure compatibility of the concrete core and steel hoop in a global sense. The proposed procedure yields satisfactory predictions of confined strengths compared with experimental results, and the influence of tie flexibility, tie configuration and degree of confinement can be well captured.

• Journal of the Korea Institute of Building Construction
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• 제18권2호
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• pp.99-107
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• 2018

The objective of the present study is to propose a reliable shape of supplementary V-ties in the section jacketing approach for seismic strengthening of reinforced concrete columns. A total of 24 pull-out specimens were prepared. The test parameters selected with regard to bond strength of V-ties were the shape of V-ties, embedment length of V-tie legs, and compressive strength of concrete. The measured bond strength of V-ties with different shapes were compared with that of the conventional V-ties and predictions using CEB-FIP equation. Ultimately, V-ties with pressed end-details at their legs could be recommended for the supplementary lateral reinforcement of strengthening columns with jacketing thickness less than the embedment length [= max (75mm, $6d_b$)] of conventional V-ties, where $d_b$ is the diameter of the reinforcing bar used for V-ties.