• Journal of the Korean GEO-environmental Society
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• v.18 no.5
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• pp.27-33
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• 2017

In this research, laboratory tests were carried out to investigate the engineering properties of Light-Weight Air Foamed Soil (LWAS) based on silty clays with the animal foaming agent and cement. LWAS has been used as an embankment material over soft ground for road and side extension of the existing road. In field, unit weight and flow value is measured right after producing in mixing plant in order to control the quality of LWAS, and laboratory tests are carried out to confirm the quality through compressive strength of LWAS as well. In this research, direct estimation of the specification requirement of strength using flow values in field is the main purpose of the study together with other characteristics. From the test results, it can be seen that flow values increase with the initial water content and unit weight increases with the depth due to material segregation. Compared to the upper specimen, lower end of 60 cm specimen shows about 2 times higher compressive strength. Relationship between flow values and normalized factor presented by Yoon & Kim (2004) was presented. With that relationship, compressive strength can be predicted from flow values in field. From the relationship, the normalized factor was calculated. Thereafter calculated compressive strengths according to the flow values were compared to measured strengths in the laboratory. The higher the initial water content of the dredged soil has, the better relationship between predicted and measured shows. Therefore it is necessary to predict the compressive strength in advance through the relationship between the flow value and the normalized factor to reflect it in the design stage.

• Journal of Distribution Science
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• v.14 no.5
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• pp.39-50
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• 2016

Purpose - The purpose of this study was to substantiate the relationship between on-the-job training (OJT) characteristic factors and OJT outcomes and the moderating effect of the tie strength between a trainer and a trainee on the relationship. OJT characteristic factors were composed of a unit of work to be learned, trainee's motivation, trainer's ability, OJT design, and OJT support. OJT outcomes included job satisfaction and organizational commitment in the research. The tie strength means a sense of intimacy with a trainer. All of the OJT characteristic factors, OJT outcomes, and the tie strength were defined operationally as the perceived ones by a trainee. Research design, data, and methodology - This study analyzed the data of 302 employees in a domestic travel agency as early career for seven years or less. The main methods for the analysis were multiple linear regression analysis and moderating effect analysis. The whole process of the data analysis was conducted using the SPSS 21.0 for windows. Results - The results of the study are as follows: First, every five element of OJT, including unit of work to be learned, trainee's motivation, trainer's ability, OJT design, and OJT support, showed positive influence on OJT outcomes - job satisfaction and organizational commitment. Second, the tie strength between a trainer and a trainee was positively related with OJT outcomes. Finally, the strength of ties between the trainer and the trainee was found positively to moderate the relationship of a unit of work to be learned, OJT design, or OJT support, with OJT outcomes. However, the moderating effect of the tie strength was not significant statistically between the trainee's motivation or the trainer's ability, and OJT outcomes. Conclusion - In the study, it was demonstrated that every OJT characteristic factors have a positive contribution to job satisfaction and organizational commitment for early career employees. In addition, the study showed the need to pay attention to improve the quality of relationships between trainers and trainees, in order to increase the impact of a unit of work to be learned, OJT design, and OJT support. These findings suggest the implications in the three factors as external factors that constitute OJT. The three factors are made by HRD practitioners who are involved in design and operation of the program as well as their interventions to improve the quality of the relationship between trainers and trainees. On the other hand, it was demonstrated in the research that trainee's motivation and trainer's ability, regardless of their tie strength, have a direct impact on OJT outcomes by itself. Moreover, the trainee's motivation and trainer's ability are intrinsic characteristics, rather than external factors that constitute OJT. Therefore, they are unlikely to be changed by HRD practitioners' interventions. In conclusion, it was argued in the research that the trainee's motivation and trainer's ability should be a consideration in selecting and matching partners in OJT participants before starting OJT.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1117-1123
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• 2016

Roller-Compacted Concrete Pavement (RCCP) is a type of pavement that shares conventional concrete pavement material characteristics and asphalt pavement construction characteristics. Even though RCCP is compacted in the same way and have similar aggregate gradation to asphalt pavements, its materials and structural performance properties are similar to those of conventional concrete pavement. With cement hydration and aggregate interlock, Roller-Compacted Concrete or RCC can provide strength properties equal to those of conventional concrete with low cement content. Therefore, compaction ratio of RCC can highly influence on its strength. In general, 95% of compaction ratio is required for proper strength development. RCC strength can be highly influenced by compaction energy which depends on compaction equipment and compaction method. Therefore, it is necessary to analyze the relationship between compressive strength and compaction ratio of RCC. RCCP specimens were produced at different compaction ratio by using different compaction methods and energies. The compaction ratio was defined by the ratio of the specimen's dry density and its maximum dry density. The maximum dry density was obtained from Modified Proctor test. 28 days compressive strength corresponding to each compaction ratio case was tested. Finally, the relationship between compressive strength and compaction ratio can be analyzed. For application of roller-compacted concrete in domestic construction site, the relationship is important for field compaction management.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.397-400
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• 2002

The mechanical properties of concrete such as modulus of elasticity, bond strength and shear strength are proportional to square root of compressive strength. And compressive strength of concrete is developed rapidly at early ages. Thus the relationship between compressive strength and its mechanical properties should be verified because the mechanical properties of early age concrete and hardened concrete are different. In this study, to predict the concrete slab deflection at early ages, modulus of elasticity and effective moment of inertia(Ie) are observed and compared with experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.232-236
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• 1993

The Tunnel Form(T/F) system instead of traditional euro form has been tried to reduce construction duration and to improve concrete quality in reinforced concrete wall type apartment construction. To find the relationship for concrete compressive strength between cylinder mold and slab, the different curing locations of concrete cylinder mold in the room have been investigated. The test results showed that the compressive strength of the cylinder concrete with middle-upper location in the room was most near concrete compression strength with respect to slab concrete strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.675-678
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• 2004

The importance of predicting concrete compressive strength of in concrete structures is gradually increasing in construction industry. The estimation of concrete compressive strength of is a critical factor of the construction schedule and quality control. This study was performed to examine the relationship between concrete compressive strength and stress wave velocity which was determined by the impact echo method and SASW method.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.53-58
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• 2003

Many researchers have rigorously studied the nonlinear behavior of stress-strain relationship of concrete using mathematical curves. Most of model equations for stress-strain relationship, however, have been focused on old age concrete, and were not able to adequately represent the behavior of concrete at an early age. A wide understanding on the behavior of concrete from early age to old age is very important in evaluating the durability and service life of concrete structures. In previous study by authors of this paper, a stress-strain model equation for low- and medium-strength concretes was suggested. In this paper, to extend the application region of compressive stress-strain curve to high-strength concrete, an analytical research was performed. An analytical expression of stress-strain curve with strength and age was developed using regression analyses on the experimental results. For the verification of the proposed model equation, it was compared to the experimental data. The result showed that the proposed model equation was not only compatible with the experimental data quite satisfactorily but also describing well the effect of strength and age on stress-strain curve.

• Journal of the Korean Geotechnical Society
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• v.20 no.4
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• pp.5-13
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• 2004

Strength and compressibility characteristics of Light-Weighted Foam Soil (LWFS) are experimentally investigated in the paper. LWFS is composed of the dredged soils, cement and air foam to reduce unit-weight and to increase compressive strength. For these purposes, both unconfined compression tests and triaxial compression tests are carried out fer artficially prepared specimens of LWFS with various initial water contents, cement contents, mixing ratio of silty dredged soils and different confining stresses. The experimental results of LWFS indicate that the stress-strain relationship and the compressive strength are strongly influenced by cement contents rather than intial water contents of the edged soils. In this paper, the normalizing scheme considering the ratio of initial water contents, cement contents, and air foam contents has been proposed to evaluate the relationship between compressive strength of LWFS and a normalized factor.

• Journal of the Korean Wood Science and Technology
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• v.26 no.1
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• pp.63-69
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• 1998

This study was carried out to get some basic information on mechanical properties of Korea Lepidobalanus for rational utilization of wood. Five species of Quercus variabilis, Q. aliena, Q. serrata, Q. mongolica, Q. acutissima belong to Lepidobalanus were investigated in this research. Relationship of anatomical characteristics to compression strength parallel to grain was analyzed using stepwise regression technique. All possible combination of 21 independent variables were regressed on compression strength parallel to grain. The summarized results in this study were as follows: I. In the proportion of wood structural elements, the factors that had the greatest influence on compression strength parallel to grain appeared to be proportion of ray in earlywood in Q. variabilis and Q. acutissima, proportion of wood fiber in latewood in Q. aliena and Q. serrata and proportion of vessel in earlywood in Q. mongolica respectively. 2. In the size of wood element and its structure, the factors that had the greatest influence on compression strength parallel to grain were microfibril angle in Q. variabilis, Q. serrata and Q. mongolica and length of wood fiber in Q. aliena and Q. acutissima.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.985-990
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• 2001

Chloride permeability of high strength concrete(HSC) was investigated using saltwater pending test and rapid chloride permeability test by electrical potential(ASTM C 1202). The lower water-cement ratio concrete showed the lower diffusion coefficient of chloride. The relationship between the diffusion coefficient of chloride and charge passed by the rapid chloride permeability test could be obtained. This relationship appears to be an effective method for evaluating chloride permeability of low water-cement HSC.