• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.4
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• pp.88-94
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• 2004

High manganese steel was maintained stability of Non-Magnetics performance. Fatigue tests were carried out under constant stress amplitude, using a non-magnetic high manganese steel. The fatigue crack growth mechanism of the high manganese steel was clarified from results such as observation of crack growth path and fracture surface. The result of getting this study was shown as following: 1) Remarkably ${\Delta}Kth$ of the high manganese steel is big with about 3 times of the general steel product. 2) In the low ${\Delta}K$ value region, da/dN is dependent on Kmax, and in the high ${\Delta}K$ value region, it is dependent on ${\Delta}Keff$. The reason of this behavior is crack closure due to fracture surface roughness and fretting oxide. 3) It seems to ease the stress concentration of crack tip crack growth behavior in the ${\Delta}Kth$ vicinity by the generation of the secondary crack.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.714-719
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• 2011

The surface roughness depending on the machining method is very important because is produce a finished product through riveting, sealing, bonding, and special paint in order to curb the turbulence and air resistance which occur between the sheets. Aluminum alloy 2024 which is widely used for interior and exterior material of aircraft are tested. Jin-young JW-60C wire cutting machine was used in this experiment. In this paper, the experimental investigation has been performed to find out the influence of the surface roughness and surface shape characteristics on the wire-cut EDM of discharge energy in aluminium alloy 2024. The selected experimental parameters are peak current, no-load voltage, off time and feed rate. The experimental results give the guideline for selecting reasonable machining parameters. The high discharge energy on the idle time, almost no change in surface roughness can be seen.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.1
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• pp.37-42
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• 2005

The localization of manufacturing technique development is actualizing for low cost with supplies of display devices. We need more high cutting technique because consumers want flat glasses of various sizes. Recently, most general two methods are normal wheel cutting and laser cutting, but both of them have some faults. First, the wheel cutting has cracks and sharp edges of sections. Second, it is easy for laser cutting to cut curved lines. however, it has thermal damage and low traverse speed. I suggest a new cutting method by high-wave frequency vibration wheel cutting(HFVC), which is good for quality improvement. Vertical cracks and crack depth is observed, after HFVC. When the average of the crack depth is $30{\mu}m$ and the average of the wallner liner depth is $200{\mu}m$, it has the most high quality of the sections in this experiment. As a result, when we consider between the normal wheel cutting method and the HFVC method, the latter has low cracks and good quality.

• Mycobiology
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• v.37 no.1
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• pp.62-66
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• 2009

The internal stipe necrosis of cultivated mushrooms (Agaricus bisporus) is caused by the bacterium Ewingella americana, a species of the Enterobacteriaceae. Recently, Ewingella americana was isolated from cultivated white button mushrooms in Korea evidencing symptoms of internal stipe browning. Its symptoms are visible only at harvest, and appear as a variable browning reaction in the center of the stipes. From these lesions, we isolated one bacterial strain (designated CH4). Inoculation of the bacterial isolate into mushroom sporocarps yielded the characteristic browning symptoms that were distinguishable from those of the bacterial soft rot that is well known to mushroom growers. The results of Gram stain, flagellal staining, and biochemical tests identified these isolates as E. americana. This was verified by pathogenicity, physiological and biochemical characteristics, and the results of an analysis of the 16S rRNA gene sequences and the fatty acids profile. This is the first report of the isolation of E. americana from cultivated white button mushrooms in Korea.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.47-50
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• 2008

This study analyzed the effect of increasing the number of times using aluminum form to the surface quality of concrete through small sized test, and the result was summarized as following. At the early stage, there was no remarkable change between aluminum and coated plywood form, and the surface quality of concrete both forms slightly declined corresponding with increasing the number of times using.As void on the surface corresponding to the number of times, the voids ranged 0.1~1mm were increased corresponding to increasing the number of times using forms, and the other range voids were also increased according to increasing the number of times using forms. It was confirmed that the surface of concrete was damaged gradually. For comparison with aluminum and coated plywood form though this experimental results, there might be no difference, if release agent was used properly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.627-632
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• 2011

The internal broadband noise of a centrifugal fan in a household refrigerator is predicted by using hybrid CAA technique based on stochastic turbulent synthetic model. First, the unsteady flow field around the centrifugal fan is predicted using Computational Fluid Dynamics (CFD) method. Then, the turbulent flow field is synthesized by applying the stochastic turbulent synthetic technique to the predicted flow field. The aerodynamic noise sources of the centrifugal fan are modeled on a basis of the synthesized turbulent field. Finally, the broadband noise of the centrifugal fan is predicted using Boundary Element Method (BEM) and the modeled sources. The predicted result is compared with the experimental data. It is found that the predicted result closely follows the experimental data. The proposed method can be used as an effective tool for designing low-noise fans without expensive computational cost required generally for the LES and DNS simulations to resolve the turbulence flow field responsible for the broadband noise.

• Journal of Plant Biotechnology
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• v.43 no.3
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• pp.281-292
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• 2016

Plants can recognize and respond in various ways to diverse environmental stresses, including pathogenic microorganisms, salt, drought, and low temperature. Salicylic acid (SA) is one phytohormone that plays important roles in the regulation of plant growth and development. Nonexpressor of pathogenesis-related genes 1 (NPR1) was originally identified as a core protein that could function as a transcriptional co-regulator and SA receptor during systemic acquired resistance (SAR), a plant immune response that could activate PR genes after pre-exposure of a pathogen. Although the function of NPR1 in plant defense response and the role of SA hormone in the regulation of plant physiological processes have been well characterized, the biological role of NPR1 in plant abiotic stress responses is largely unknown. In this review, we will summarize and discuss the current understanding of NPR1 function in response to plant environmental stresses.

• Journal of the Korean Society of Industry Convergence
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• v.12 no.2
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• pp.85-90
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• 2009

The Toyota production system (TPS) developed by Toyota corporation is a management principle and production model to improve values added through elimination of waste. Since the oil shock in 1970s, the TPS has drawn the worldwide attentions as a main factor of competitiveness of Japanese manufacturing system and has been studied and implemented in many countries regardless of size and types of industry. For the correspondence to various customer's requirement, it is required to establish on time delivery procedure and to shorten lead time. Therefore it intended to establish TPS which is adopted to 7 losses reduction and JIT(Just in Time). In this paper, the automatic production line for color TV manufacturing by TPS was developed and proved to push up two times of productivity, to reduce the 25 workers at a time, and to widen the flexibility of manufacturing from 14" to 25" TV.

• Journal of Korean Physical Therapy Science
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• v.9 no.1
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• pp.37-43
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• 2002

The purpose of this study was to investigate the effects of aqua-exercise program on fitness and blood factors in the elderly women. Subjects were fifteen members living in Daejon(15 females), between 65 and 77 years of age. The subjects was put in the aqua-exercise program for 8 weeks, between July and september, 2001. The results of this study were as follows : 1. After the exercise program, there are significant differences of Fat Mass(p<0.05), Fat Distribution(p<0.01), Obesity(p<0.01), Soft Lean Mass(p<0.05). 2. After the exercise program, subjects showed Meaningful increase of SGOT(p<0.01), SGPT(p<0.001).

• Journal of the Korean Society of Earth Science Education
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• v.2 no.1
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• pp.23-32
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• 2009

e-PBL based on constructivism adopted PBL(Problem Based Learning) and WBI(Web Based Learning), and it becomes the advanced model of instruction to be achieved PBL on-line. In this thesis, I applied e-PBL to 'the changing weather' part in the high school earth science I, compared to the lecture centered instruction, and analyzed how it affected on. On the basis of these, this study predicts the applicability on the cooperative learning and self-directed learning in the high school and suggests the improving of the teaching-learning with the results. The following shows the conclusion with as the central result of research. Firstly, the instruction applied e-PBL proved more effective academic achievement than the lecture centered instruction. Secondly, the instruction applied e-PBL proved more effective on the improving self-directed learning ability. Thirdly, the instruction applied e-PBL proved more effective self-efficacy than the lecture centered instruction.