• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.12
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• pp.725-731
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• 2004

In this study, the three type hybrid interrupters according to the arrangement of the thermal expansion chamber and the puffer cylinder(they are called 'serial type', 'parallel/exchanged type', and 'parallel/separated type' respectively in this work) were designed and manufactured. This paper presents the tested results of the thermal recovery characteristics on the interrupters using a simplified synthetic test facility. The 'serial type' hybrid interrupter which is to obtain more easily the pressure rise for the thermal recovery compared with the others has the best capability in the thermal recovery characteristics. In order to investigate the stress on the operating mechanism, the distortion of the stroke wave in on-load test was examined to the stroke curve in no-load test. The biggest distortion was occurred in the 'parallel/exchanged type' hybrid interrupter. Finally, the small interruption capability on the three type interrupters was estimated by a theoretical form and the 'parallel/separated type' hybrid interrupter has the advantage of the others in the view of structure.

• Journal of the Korean Society of Child Welfare
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• no.56
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• pp.101-132
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• 2016

Fandom is a meaningful social phenomenon that represents a significant dimension of contemporary Korean youth culture. Previous research, however, has considered fandom as a deviant activity that is negative in nature, and there is scant research on the positive effects of fandom activity. This study examined the effects of off-line and on-line fandom activity participation on adolescents' academic time management capability. Data were collected from three waves (2010, 2012, and 2014) of the Korean Children and Youth Panel Survey (middle school cohort; N=2,206 at baseline). Results from the multi-level growth curve analysis were as follows. First, more than half of the adolescents reported participating in fandom activities, and the majority of them participated in both online and offline activities. Second, adolescents' academic time management capability improved over time. Third, both off-line and on-line fandom activity participation was positively associated with adolescents' academic time management capability at the baseline (first year of middle school). The size of this relationship, however, decreased over time (from middle school to high school). This study presented the importance of appropriate guidance by adults to develop and promote the positive aspects of fandom activity, and highlighted the need for further research that focuses on the positive aspects of fandom activities.

• Structural Engineering and Mechanics
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• v.11 no.6
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• pp.591-604
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• 2001

In this paper, a finite element with embedded displacement discontinuity which eliminates the need for remeshing of elements in the discrete crack approach is applied for the progressive fracture analysis of concrete structures. A finite element formulation is implemented with the extension of the principle of virtual work to a continuum which contains internal displacement discontinuity. By introducing a discontinuous displacement shape function into the finite element formulation, the displacement discontinuity is obtained within an element. By applying either a nonlinear or an idealized linear softening curve representing the fracture process zone (FPZ) of concrete as a constitutive equation to the displacement discontinuity, progressive fracture analysis of concrete structures is performed. In this analysis, localized progressive fracture simultaneous with crack closure in concrete structures under mixed mode loading is simulated by adopting the unloading path in the softening curve. Several examples demonstrate the capability of the analytical technique for the progressive fracture analysis of concrete structures.

• Journal of Korean Institute of Industrial Engineers
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• v.42 no.5
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• pp.337-351
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• 2016

As technologies' life-cycle shortens and their development directions are uncertain, firms' technology planning capability becomes increasingly important. Prior patent-based studies using technology growth curves identify developmental stages of technologies, thereby formulating technology development directions from an overall perspective. However, a technology generally consists of multiple sub-technologies and accordingly their development stages are likely various. In this regard, the prior studies failed to identify core sub-technologies and their specific development directions. Therefore, we suggest an approach consisting of 1) identifying core sub-technologies of a given technology using patent co-classifications and social network analysis, and 2) identifying each sub-technology's development stage and thereby determining its further development direction. We apply our approach to patents related to augmented reality to examine its applicability. It is expected that our approach will help identify evolving development stages for the core sub-technologies of a given technology, thereby effectively assisting technology experts in technology planning processes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.428-436
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• 1998

A TCS slip control system improves acceleration capability and steerability on slippery roads through engine torgue and/or brake torque control. This research mainly deals with the engine control algorithm via the adjustment of the engine throttle angle. The following new control strategy is proposed and investigated ; the TCS slip controller whose input is the difference between the desired driving wheel speed corresponding to the optimum slip ratio and the actual speed yields the target engine torque and then estimates the throttle angle based on the engine performance curve. Various simulation and hardware-in-the-loop simulation have been carried out. The results show the proposed strategy may compensate for the inherent nonlinearity between variation of the throttle angle and variation of the engine torque and produce better performance than the previous strategies without the engine map, especially in the high speed region.

• The Journal of Pediatrics of Korean Medicine
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• v.12 no.1
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• pp.145-162
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• 1998

The purpose of this study was to determine the effects of oriental medical care on growth deficiency children. These cases were collected to investigate the effects of oriental medical care on growth deficiency children. So the cases were divided into 5 groups. The growth velocity was compared to a normal growth curve, and the results are as follows: 1. Oriental medical care was efficient when the epiphysial plates were not closed. 2. In female middle school beyond 1st grade students and in male middle school 3rd grade students who had almost closed epiphysial plates, the oriental medical care was not efficient and did not promote growth velocity. endothelium were used for the experiment using organ bath. 3. In the cases where the parent were very short, the effects of the oriental medical care to promote growth velocity was not efficient. 4. when we treated children of normal height, their growth velocity was over the normal growth curve. 5. In preschool aged children, oriental medical care was very efficient to promote children's growth. 6. The principle oriental medical care was to make balanced their body and digestive organs by using herb medicines that have the capability to promote the growth of the bones, and build strong muscles.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.198-203
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• 2010

In this paper, study on the mode characteristics analysis of the SH-EMAT (shear horizontal, electromagnetic acoustic transducer) waves for evaluating the thickness reduction in plates such as corrosion and friction is presented. Noncontact methods for ultrasonic wave generation and detection have been a great concern and highly demanded due to their capability of wave generation and reception on surface of high temperature or on rough surface. Mode identification of the SH-EMAT wave is carried out in an aluminum plate with thinning defects using time frequency analysis method such as wavelet transform, compared with theoretically calculated group velocity dispersion curve. The changes of various wave features such as the amplitude and the time-of-flight have been observed and the correlations with the thickness reduction have been investigated. Firstly, experiments have been conducted to confirm that it is possible to selectively generate and receive specific desired SH modes. These modes have then been analyzed to select the parameters that are sensitive to the thickness change. The results show that the mode cutoff and the time-of-flight changes are feasible as key parameters to evaluate the thickness reduction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.34-40
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• 2019

We performed shape optimization of an anti-vibration rubber assembly which is used in the field option cabin of agricultural tractors to improve the vibration isolation capability. To characterize the hyper-elastic material property of rubber, we performed uniaxial and biaxial tension tests and used the data to calibrate the material model applied in the finite element analyses. We conducted a field test to characterize the input excitation from the tractor and the output response at the cabin frame. To account for the nonlinear behavior of rubber, we performed static analyses to derive the load-displacement curve of the anti-vibration rubber assembly. The stiffness of the rubber assembly could be calculated from this curve and was input to the harmonic analyses of the cabin. We compared the results with the test data for verification. We utilized Taguchi's parameter design method to determine the optimal shape of the anti-vibration rubber assembly and found two distinct shapes with reduced stiffness. Results show that the vibration at the cabin frame was reduced by approximately 35% or 47.6% compared with the initial design using the two optimized models.

• Structural Engineering and Mechanics
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• v.73 no.6
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• pp.613-620
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• 2020

The research study is focuses on a form of all-bolted joint with the external ring stiffening plate in the prefabricated steel structure. The components are bolted at site after being fabricated in the factory. Six specimens were tested under cyclic loading, and the effects of column axial compression ratio, concrete-filled column, beam flange sub plate, beam web angle cleats, and spliced column on the failure mode, hysteretic behavior and ductility of the joints were analyzed. The results shown that the proposed all-bolted joint with external ring stiffening plate performed high bearing capability, stable inflexibility degradation, high ductility and plump hysteretic curve. The primary failure modes were bucking at beam end, cracking at the variable section of the external ring stiffening plate, and finally welds fracturing between external ring stiffening plate and column wall. The bearing capability of the joints reduced with the axial compression ratio increased. The use of concrete-filled steel tube column can increase the bearing capability of joints. The existence of the beam flange sub plate, and beam web angle cleat improves the energy dissipation, ductility, bearing capacity and original rigidity of the joint, but also increase the stress concentration at the variable section of the external reinforcing ring plate. The proposed joints with spliced column also performed desirable integrity, large bearing capacity, initial stiffness and energy dissipation capacity for engineering application by reasonable design.

• Journal of Korea Water Resources Association
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• v.31 no.1
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• pp.95-103
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• 1998

Dam sediment can be predicted from the two methods: the one is a physical analysis based on the hydrjulic mechanism and the other is an empirical approach using observed data as a design factor. The former can be used to estimate short-term phenomena by mathematical methods. the latter can be used for deriving long-term design parameters such as dead storage calculation. Monthly reservoir operation is possible with the sluicing efficiency curve based on empirical data. The optimal sediment management can be carried out using the information variable which traces deposit sediments corresponding to the reservoir storage. The idea can provide an optimal operation strategy to save effective storage varying with time. This study presents a methodology for the long-term sediment prediction using sluicing efficiency curve. An application is conducted for estimating accumulated sedment deposit and water supply capability ofr the Fenhe dam in the Yellow rever of China.