• Journal of the Korean Wood Science and Technology
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• 제46권5호
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• pp.437-448
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• 2018

Physical characteristics of Korean red pine (Pinus densiflora) were investigated with different cultivation locations in Taebaek Mountains as Goseong-gun, Hongcheon-gun and Bonghwa-gun as experimental sites. Moisture content based on air-dried or green (artificial) wood was no significant differences with different cultivation places. Specific gravities of both sapwood and heartwood of red pine from Bonghwa-gun were higher than those from other two sites (Hongcheon-gun or Goseong-gun). Specific gravity of heartwood of red pine from Goseong-gun was higher than it from Hongcheon-gun, but this trend was opposite in case of sapwood. Higher specific gravity of red pine heartwood from Goseong-gun maybe resulted in higher strength than those of other sites. In shrinkage ratio, there was no significant difference among different cultivation places in radial directions, but red pine from Bonghwa-gun was higher than those of other sites in tangential directions. Hygroscopicity was no significant differences with different cultivation places. These results will be helpful information for efficient use of pinewood and good quality of pinewood production for genetical breeding improved.

• Journal of Technology Innovation
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• 제20권3호
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• pp.153-180
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• 2012

The objective of this study is to identify the characteristics of high performer among R&D professionals and to examine the effects of LMX(Leader-Member Exchange) and TFL(Transformational Leadership) on job satisfaction or organizational commitment. The empirical result shows that; 1) when compared with the low performers of R&D professionals, the high performers have more proactive personality such as risk-taking propensity, self-efficacy, need for achievement, 2) the high performers have more innovative problem-solving style, 3) the impact of LMX and TFL on job satisfaction or organizational commitment is significant and positive, 4) the augmentative effect of TFL over LMX on job satisfaction or organizational commitment exists for low performer but does not exist for high performer. Based on the result, the theoretical and practical implications are discussed.

• Journal of the Korea institute for structural maintenance and inspection
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• 제9권1호
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• pp.181-188
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• 2005

Generally, high performance concrete has characteristics such as low water-cementitous material ratio, lots of unit binder powder, thus the drying shrinkage and autogenous shrinkage are tend to be increased. The purpose of this study is to investigate the effect of the glyclos based shrinkage reducing agent on the drying shrinkage and autogenous shrinkage of high performance concrete with 30% of water-cemetitious material ratio as a study to develop the technology to reduce the concrete shrinkage. Test results show that the drying and autogenous shrinkage of high performance concrete are reduced by about 20~35% at the mixing ratio of shrinkage reducing agent of 0.5%, and 1.0%, compared with plain concrete. Therefore, it analyze that the using of shrinkage reducing agent is effective to reduce the drying shrinkage and autogenous shrinkage of high performance concrete.

• Korean Journal of Construction Engineering and Management
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• 제15권4호
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• pp.49-57
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• 2014

Since the structure systems of construction projects have been forced to be large, high-rised, and complex, many researchers have been put their efforts to develop high strength concrete incorporating diverse advanced materials. In order to improve the performance of the concrete, the fibers leading high ductility to concrete have been used, consequently concrete columns adopting High-Performance Fiber Cement(HPFC) have been developed. This paper analyzed not only the construction work process of HPFC column installed to the real construction project, but also construction productivity of the columns by using discrete event simulation technique. As a result, several considerations on installing such a column have identified, compared with the works for typical concrete columns. In particular, there was specific characteristic to install the columns in terms of labor resource productivity, which is not shown with the work for the typical concrete columns.

• Journal of Korean Society of societal Security
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• 제4권1호
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• pp.29-37
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• 2011

Recently, Inhabitants nearby the high embankment road have requested a civil complaint on the environmental deteriorations and economic harms. This study was carried out numerical simulation using the 3-D microclimate model 'Envi-met' in order to investigate the variations of a flow field and a temperature field at the road sections with a high embankment and a bridge. About the simulation of flow field, the wind field has changed due to the disturbance of airflow by a high embankment road considerably. And the wind velocity decreased in the whole of simulation space widely. But, the wind velocity and wind direction sited loose to the section of a bridge, relatively. In the results of a temperature field, the slight variations of temperature field were discovered by the disturb of the mixing flow from a high embankment road. These results indicate that the numerical simulation can provide useful information to minimize the disasters, such as traffic accidents and various microclimatic environments in the transportation projects.

• Journal of the Korean Recycled Construction Resources Institute
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• 제9권2호
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• pp.200-207
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• 2021

The purpose of this study is to investigate experimentally the effects of type of superplasticizer on tensile behavior and cracking pattern of alkali-activated slag-based cementless composite. Three mixtures were prepared according to type of superplasticizer, and the compressive strength and tension tests were performed. Test results showed that differences of tensile strength, tensile strain capacity, and toughness of composites were up to 28.1%, 39.1%, and 66.2%, respectively, according to type of superplasticizer, although fiber balling or poor dispersion of fibers in fresh composites was not observed. It was also observed that the type of superplasticizer influenced number of cracks and maximum fiber bridging stress.

• The Journal of the Korea Contents Association
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• 제19권2호
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• pp.22-35
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• 2019

Utilizing fit theory in strategic human resource management, this study examines the impact of two HR practices on newcomer turnover rates. While there is a growing body of research identifying the linkage between high-performance work systems(HPWS) and improved organizational performance through higer employee commitment, little research addresses how specific mechanisms among the systems deliver different performances to organizations. Using management by objective(MBO) and job rotation in HPWS, we found a strong main effect of each practice-it decreases newcomer turnover rates. This main effect becomes stronger when one practice combined with another, showing synergy exists. Linking HPWS research to turnover, this study provides insightful evidence of interactions between MBO and job rotation for organizational performance.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제26권4A호
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• pp.787-794
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• 2006

Generally, high performance concrete has characteristics such as low water-cementitious material ratio, lots of unit binder powder, thus the heat of hydration, autogenous shrinkage are tend to be increased. This study is to investigated the effect of the expansive additive and shrinkage reducing agent on the shrinkage properties of high performance concrete as a study to develop the reduction technology of the concrete shrinkage. Test results showed that the expansive additive and shrinkage reducing agent were effective the reduction of shrinkage of high performance concrete. Especially, the using method in combination with expansive additive and shrinkage reducing agent was more effective than the separately using method of that. Also, it analyzed that the combination of expansive additive of 5% and shrinkage reducing agent of 1% was the most suitable mixture, considering to the fluidity, strength and shrinkage properties.

• Journal of the Korea institute for structural maintenance and inspection
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• 제10권2호
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• pp.143-152
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• 2006

High performance concrete(HPC) has been widely used in high-rise building. The HPC has several benefits including high strength, high fluidity and high durability. However, spalling is susceptible to occur in HPC and HPC also tends to be deteriorated in the side of fire resistance performance at fire. This paper investigated the spalling prevention of high performance RC column. Control concrete showed severe failure and a case of concrete with fire enduring spraying material exhibited more severe spalling failure than even control concrete. In addition, concrete with fire enduring paint reported the most favorable spalling resistance effect for preventing spall, compared with other concrete covered with finishing materials, such as fire enduring spraying material, gypsum board, marble board and fire enduring PC board. Meanwhile, concrete adding 0.1% of PP fiber demonstrated spalling resistance performance after 3hours load bearing test.

• Journal of the Korea institute for structural maintenance and inspection
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• 제10권3호
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• pp.97-105
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• 2006

The autogenous shrinkage of high-performance concrete is important in that it can lead the early cracks in concrete structures. The purpose of the present study is to explore the autogenous shrinkage of high-performance concrete with admixture and to derive a realistic equation to estimate the autogenous shrinkage model of that. For this purpose, comprehensive experimental program has been set up to observe the autogenous shrinkage for various test series. Major test variables were the type and contents of admixture and water-cement ratio is fixed with 30%. The autogenous shrinkage of HPC with fly ash slightly decreased than that of OPC concrete, but the use of blast furnace slag increased the autogenous shrinkage. Also, the autogenous shrinkage of HPC is found to decrease with increasing shrinkage reduction agent and expansive additive. A prediction equation to estimate the autogenous shrinkage of HPC with admixture was derived and proposed in this study. The proposed equation show reasonably good correlation with test data on autogenous shrinkage of HPC with mineral and chemical admixture.