• Journal of Welding and Joining
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• v.29 no.1
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• pp.90-98
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• 2011

Al-Si coated Boron steel and Zn coated DP steel were welded using DISK laser and the microstructure and hardness of the weld were investigated. Full penetration was obtained, when the welding speed was lower than 4m/min. In the specimen welded with laser power of 3 kW and welding speed of 2 m/min, the hardness was the highest in the heat affect zone in the boron steel (HAZ-B) and that of the heat affect zone in the DP steel (HAZ-D) was lower than HAZ-B. The hardness of fusion zone was in between those of HAZ-B and HAZ-D. The decreased hardness from each HAZ to base metal(BM) could be explained that ferrite contents increases when access to the BM. The variation of hardness in the welds could be explained by the difference of microstructure, that is, full martensite in HAZ-B, mixture of martensite and bainite in the fusion zone, and the mixture of martensite, ferrite and bainite in HAZ-D.

• Journal of Technology Innovation
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• v.8 no.2
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• pp.97-117
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• 2000

TOEM strategy is widely used in Japan and Korea because of the diverse advantages such as cost sharing, technology transfer, equipment lease and base technology acquisition between parent company and OEM supplier. There are, however, some disadvantages that (1)OEM suppliers are likely to be reactive to environmental changes and (2) may have difficulty in building competitive position and long-term growth. When the parent company relocates its plant to foreign countries to achieve lower labor cost or to enhance value added this change will affect directly the OEM supplier's outcome. The parent company's divestiture from existing businesses will also affect the OEM supplier. For the OEM supplier to survive in face of these strategic changes it must enter the new countries with the parent company. Alternatively, the OEM supplier must actively diversify its technologies based on its core capabilities of existing product and process technologies and seek new business arenas. The strategy of aligning its businesses with the parent company's new business strategy allows the OEM supplier to share the new market while it requires the OEM supplier to develop core capabilities. In Korea many small and medium sized OEM suppliers are dependent on a few large companies. For the industry structure in Korea where industry concentration is extremely high OEM suppliers should move away from the past strategy, where they are dependent on the parent company's low profitability businesses. They should actively enter new businesses for which parent companies enter to achieve long-term growth.

• Journal of Korean Society of Rural Planning
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• v.5 no.2 s.10
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• pp.14-23
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• 1999

This studys concerns with a critical issues of urban and rural integration for rurban development. Todays, many of urban-rural integrated cities are confronted with the negative effects of administrative boundary integration. The first problem is induced from the developmental gaps and different residential demands between the core-city and peripheral-county. The second problem is social-economic and administrative unification costs neglected. The third problem is the environmental pollutions and degradations in peripheral-county by rapid urbanization. The forth problem is the inequality of the public services and regional investments in the urban-rural Integrated cities. The fifth problem is the administrative relation and financial distribution between core-city and residual province when the urban-rural integrated core-city becomes large urban city. The results of the questionnaire analysis as follows. The first point, the preference of administrative boundary integration is different in intra-areas of urban-rural integrated county by it's location. The second point, the diversity of preference of residents depends on theirs job, age, resdential period, education and income level. So, administrative boundary integration must consider the many important factors which affect the socio-economic situations between the core-city and peripheral-county. In conclusion, residents' preference for the admistrative boundary integration depends on their situation without rational approach for macro regional development. In this contexts, comprehensive approach for the urban-rural administrative boundary integration is needed in consistent with rapid change of local government's functions.

• The Journal of Information Systems
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• v.15 no.4
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• pp.1-22
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• 2006

Nowadays, IS projects are getting more complicated and large-scaled. Therefore, many researchers and practitioners have been interested in the IS development methodologies, automated tools, techniques, and TQM to improve IS performance. Latest Standish Group's research reported that after the PMO introduction, project scale became bulkier than 1 or 2 year ago, and that IS development project success probability was increased sharply by 62 percents from 37. The previous researches listed just various PMO functions. This research is to seize the core functions and management level of the PMO affecting on the IS project performance with banks which are the leading industry to accept the PMO in Korea. The activities in the categories of implementation management technology support management infrastructure management are the core functions of the PMO to affect the IS performance including schedule management quality management user and stakeholders' satisfaction. Also, the PMO management level is important for IS project success. Among the 5 levels PMI suggested, PMO can implement the project effectively at least at the third level. Korean companies which are about to introduce the PMO have to consider the PMO core functions and management level to increase the IS maturity.

• Nuclear Engineering and Technology
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• v.41 no.9
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• pp.1171-1180
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• 2009

The internal core baffle structure of a French Pressurized Water Reactor (PWR) consists of a collection of baffles and formers that are attached to the barrel. The connections are done thanks to a large number of bolts (about 1500). After inspection, some of the bolts have been found cracked. This has been attributed to the Irradiation Assisted Stress Corrosion Cracking (IASCC). The $Electricit\acute{e}$ De France (EDF) has set up a research program to gain better knowledge of the temperature distribution, which may affect the bolts and the whole structure. The temperature distribution in the structure was calculated thanks to the thermal code SYRTHES that used a finite element approach. The heat transfer between the by-pass flow inside the cavities of the core baffle and the structure was accounted for thanks to a strong thermal coupling between the thermal code SYRTHES and the CFD code named Code_Saturne. The results for the CP0 plant design show that both the high temperature and strong temperature gradients could potentially induce mechanical stresses. The CPY design, where each bolt is individually cooled, had led to a reduction of temperatures inside the structures. A new parallel version of SYRTHES, for calculations on very large meshes and based on MPI, has been developed. A demonstration test on the complete structure that has led to about 1.1 billion linear tetraedra has been calculated on 2048 processors of the EDF Blue Gene computer.

• Journal of Korean Physical Therapy Science
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• v.25 no.3
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• pp.25-31
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• 2018

Background: The purpose of this study was to find out how changes in knee angles in stable and unstable support surfaces affect the muscle thickness of core muscles. Methods: The subjects of this study were 25 male adult. Each knee angle of 120, 90 and 60 degrees, they were performed bridge exercise on the stabilized surface and on the unstable support surface using TOGU, and measured the muscle thickness of the external and internal oblique muscle and the abdominal muscles through ultrasound images. Results: There was no significant difference between the thickness of the rectus abdominis and the internal oblique muscle depending on the support surface and the knee joint bending angles. However, there was a significant difference between the external oblique muscle and the transverse abdominis muscle by knee joint flexion angle. Conclusion: While the muscle thickness of the core muscle was not significantly affected by each support surface during the bridge exercise, there were significant changes in the core muscle as a result of changes in knee angle.

• The Journal of Advanced Prosthodontics
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• v.5 no.3
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• pp.319-325
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• 2013

PURPOSE. The objective of this study was to determine the effect of the color of a background substructure on the overall color of a zirconia-based all-ceramic crown. MATERIALS AND METHODS. Twenty one posterior zirconia crowns were made for twenty subjects. Seven premolar crowns and six molar crowns were cemented onto abutments with metal post and core in the first and second group. In the third group, eight molar crowns were cemented onto abutments with a prefabricated post and composite core build-up. The color measurements of all-ceramic crowns were made before try-in, before and after cementation. A repeated measure ANOVA was used for a statistical analysis of a color change of all-ceramic crowns at ${\alpha}$=.05. Twenty four zirconia specimens, with different core thicknesses (0.4-1 mm) were also prepared to obtain the contrast ratio of zirconia materials after veneering. RESULTS. $L^*$, $a^*$, and $b^*$ values of all-ceramic crowns cemented either on a metal cast post and core or on a prefabricated post did not show significant changes (P>.05). However, the slight color changes of zirconia crowns were detected and represented by ${\Delta}E{^*}_{ab}$ values, ranging from 1.2 to 3.1. The contrast ratios of zirconia specimens were 0.92-0.95 after veneering. CONCLUSION. No significant differences were observed between the $L^*$, $a^*$, and $b^*$ values of zirconia crowns cemented either on a metal cast post and core or a prefabricated post and composite core. However, the color of a background substructure could affect the overall color of posterior zirconia restorations with clinically recommended core thickness according to ${\Delta}E{^*}_{ab}$ values.

• PNF and Movement
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• v.15 no.2
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• pp.167-176
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• 2017

Purpose: This study investigated the effect of core and abdominal muscle-strengthening exercises on muscle activity in the lower extremity on unexpected perturbation. Methods: Twenty subjects were randomly divided into the core exercise group (n=10) or the abdominal muscles strengthening group (n=10). The two groups performed their exercises during three sessions a week for a total of four weeks. The muscle activity in the lower muscles (rectus femoris, biceps femoris, tibialis anterior, gastrocnemius) was assessed using surface electromyography (EMG) and normalized maximal voluntary isometric contraction (MVIC) before and after the exercises. Results: An increase in the tibialis anterior activity after the core and abdominal muscles strengthening exercises was found after four weeks. A significant difference in the pre- and post-exercise was found. The gastrocnemius muscle activity increased in the core exercise group more than the abdominal muscles strengthening group. However, the difference was not significant. Conclusion: The results of this study suggest that the core and abdominal muscles strengthening exercises increased the tibialis anterior muscle activity. It is expected to help make more balance ability that affect who has abdominal muscles weakness.

• Korean Journal of Applied Biomechanics
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• v.28 no.4
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• pp.213-218
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• 2018

Objective: The purpose of this study was to examine the effect of the core muscle strength enhancement of the elderly on 8 weeks training using the core exercise equipment for the elderly on the ability to control the whole-body center of mass in posture stabilization. Method: 16 females (10 exercise group, 6 control group) participated in this study. Exercise group took part in the core strength training program for 8 weeks with total of 16 repetitions (2 repetitions per week) using a training device. External perturbation during standing as pulling force applied at the pelvic level in the anterior direction was provided to the subject. In a UCM model, the controller selects within the space of elemental variables a subspace (a manifold, UCM) corresponding to a value of a performance variable that needs to be stabilized. In the present study, we were interested in how movements of the individual segment center of mass (elemental variables) affect the whole-body center of mass (the performance variable) during balance control. Results: At the variance of task-irrelevant space, there was significant $test^*$ group interactions ($F_{1,16}=7.482$, p<.05). However, there were no significant main effect of the test ($F_{1,16}=.899$, p>.05) and group ($F_{1,16}=1.039$, p>.05). At the variance of task-relevant space, there was significant $test^*$ group interactions ($F_{1,16}=7.382$, p<.05). However, there were no significant main effect of the test ($F_{1,16}=.754$, p>.05) and group ($F_{1,16}=1.106$, p>.05). Conclusion: The results of this study showed that the 8 weeks training through the core training equipment for the elderly showed a significant decrease in the $Vcm_{TIR}$ and $Vcm_{TR}$. This result indicates that the core strength training affects the trunk stiffness control strategy to maintain balance in the standing position by minimizing total variability of individual segment CMs.

• Physical Therapy Korea
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• v.29 no.1
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• pp.64-69
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• 2022

Background: Gluteus medius muscle is important for the stability of hip joint. The sufficient core stability can be contributed to the performance of gluteus medius muscle in standing position. In addition, the external support may affect core stability in standing position. Objects: The purpose of this study was to investigated the effectiveness of the external support on the strength and muscle activity of hip abductor muscle during hip abduction in standing position in subjects without core stability. Methods: Fifteen subjects participated in this study. The subjects were evaluated by using the double-leg lowering with bent knees to measure the core stability. The strength and muscle activity of hip abductors was measured in standing position with the condition with and without external support using the tensiometer sensor and the surface electromyography. The paired t-test was used to investigate the difference between hip abductor strength and activity according to external support. The level of statistical significance was set at α = 0.05. Results: The hip abductor strength and muscle activity of gluteus medius muscle with external support were significantly greater than those without external support during hip abduction in standing position (p < 0.05). Conclusion: During hip abduction in standing position, the external support may be contributed to the improvement of the hip abductor strength and muscle activity of gluteus medius especially in the subjects without core stability.