• Asian-Australasian Journal of Animal Sciences
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• v.16 no.5
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• pp.677-684
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• 2003

Twenty eight multiparous lactating cows were utilized in an experiment to evaluate the response to an exogenous fibrolytic enzyme on their lactational performance during early lactation period (in terms of milk production, milk composition, feed intake, milking efficiency, body weight change) and the exact time of this response. Cows were randomized into two groups (14 each) with similar parities and were fed a concentrate ration of barley, ground corn, soybean meal, and wheat bran and roughage ration of alfalfa hay. One of the two groups was supplemented with the fibrolytic enzyme immediately after parturition up to 100 post partum. The experiment was of two phases with 50 days each. The enzyme, which has a cellulase/hemicellulase activity (derived from Trichoderma group), was added to the concentrate part of the ration in a dry powder form. Milk production, 3.5% fat corrected milk, energy corrected milk were higher (p<0.05) for cows fed treated diet. At the same time, No differences were observed in percentages of milk components, feed intake, body weight, body weight change, or rectal temperature for the whole experimental period or during any of the two phases. Efficiency of milk production was higher (p<0.05) for treatment group cows than for that of the control ones. However, efficiency was better during the second phase than during the first phase. Feeding enzyme treated diets to dairy cows improved lactational performance during early 100 day of the lactation period. However, the first 50 days of lactation looked to be the critical.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.6
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• pp.38-45
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• 2010

Welding structures are designed to endure its expected life. The most important factors are life. Especially on welded structure, fatigue strength is critical. So this study performed a research on Box and T shape weldment specimen to examine the influence of welding type. In this experiment, the results indicate Box shape was available in more than T shape. Fatigue tests were performed to evaluate the fatigue strength of the both as-welded and statically pre-loaded specimens by 3 point bending load. Fatigue life can be improved by using Ultrasonic Impact Treatment(UIT) effect. Ultrasonic Impact Treatment(UIT) is excellent for eliminating the tensile residual stresses and generating compressive residual stresses which elevate fatigue strength of welded structures. Also, this shows that welding part has better fatigue life and welding was performed well. In this study, to evaluate the Ultrasonic Impact Treatment(UIT) effect, for welding structure, the experiment was conducted at various levels of stress range between 100MPa and 500MPa. From the test results, it was indicated that fatigue performance was improving by Ultrasonic Impact Treatment(UIT)

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.396-401
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• 2002

A practical method for evaluating the possibility of the occurrence of cracking in actual thick-plate T-joint weldments is presented in this study. Systematic experiments based on the method of the design of experiment are conducted in order to investigate the crack tendency in relation to typical welding parameters such as diffusible hydrogen, restraint intensity, preheating temperature and so on. The elastic analysis using the [mite element techniques is employed to quantify the restraint intensities of the specimens. The defined restraint intensities are treated in numerical way for the sake of considering the most uncertain factor among some major factors that govern the cracking phenomena due to welding. The critical plane for judgment of the crack occurrence or crack density is presented as a function of typical welding parameters including determined restraint intensities. The results of numerical estimation by the proposed method for the experimental specimens show the usefulness as a practical tool in welding induced crack problem having extensive uncertainties.

• Progress in Superconductivity and Cryogenics
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• v.19 no.2
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• pp.29-32
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• 2017

The use of electronic devices such as mobile phones and tablet PCs has increased of late. However, the power which is supplied through wires has a limitation of the free use of devices and portability. Magnetic-resonance wireless power transfer (WPT) can achieve increased transfer distance and efficiency compared to the existing electromagnetic inductive coupling. A superconducting coil can be applied to increase the efficiency and distance of magnetic-resonance WPT. As superconducting coils have lower resistance than copper coils, they can increase the quality factor (Q-factor) and can overcome the limitations of magnetic-resonance WPT. In this study, copper coils were made from ordinary copper under the same condition as the superconducting coils for a comparison experiment. Superconducting coils use liquid nitrogen to keep the critical temperature. As there is a difference of medium between liquid nitrogen and air, liquid nitrogen was also used in the normal conductor coil to compare the experiment with under the same condition. It was confirmed that superconducting coils have a lower reflection-coefficient($S_{11}$) than the normal conductor coils.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.3
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• pp.19-30
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• 1978

Use of herbicides in Korean agriculture has increased rapidly in recent years accompanying with ever-increasing pressure of farm labor shortage. Herbicides occupied already the second place in the rank of pesticides consumption in 1977. The agricultural experiment stations have carried out over 50 trials of chemical weed control each year since 1968. These research works and registration trials contributed much to the present wide use of herbicides. The pesticide management act amended in 1977 requires reevaluation of pesticides for their efficacy every 5 year-term. However, the development of sound weed control program and recommendations has been hempered very much by the lack of qualified workers of weed control research in agricultural experiment stations and in the institute for pesticide registration trial. Critical review of the past research works on herbicide evaluation and the present status indicates strong need for 1) the characterization of the nature of local and national weed problem, 2) the improvement of ability of the staffs in charge of weed control research through appropriate training on the basics and experimental techniques, and 3) organization and activities of weed control research committee. Furthermore, the present article attempts to clarify commonly misled points in the establishment of herbicide evaluation plan, in the design and execution of field trials, and in the assessment of trial results of the past works from the viewpoint of the basic principles with some case studies for resolution of specific enigmas.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.2
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• pp.141-149
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• 2004

In this study, smoke movement in tunnel fire with natural and longitudinal ventilation systems has been investigated. Reduced-scale experiments were carried out under the Froude scaling using 14.55kW fire source with a wick and experimental data is obtained with 1/18 model tunnel test. Temperature profiles were measured under the ceiling and vertical direction along the center of the tunnel and poisonous gas was measured at emergency exit point. The results show that refuge time for 225m intervals of emergency exit in case of natural ventilation systems is 256 seconds and critical velocity for sufficient back-layer prevention is 2.8m/s for fire strength of 20MW.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.216-217
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• 2008

In recent years, scientific community has found renewed interest in hypersonic flight research. These hypersonic vehicles undergo severe aero-thermal environment during their flight regimes. During reentry and hypersonic flight of these vehicles through atmosphere real gas effects come into play. The analysis of such hypersonic flows is critical for proper aero-thermal design of these vehicles. The numerical simulation of hypersonic real gas flows is a very challenging task. The present work emphasizes numerical simulation of hypersonic flows with thermal non-equilibrium. Hyperbolic system of equations with stiff relaxation method are identified in recent literature as a novel method of predicting long time behaviour of systems such as gas at high temperature. In present work, Energy Relaxation Method (ERM) has been considered to simulate the real gas flows. Navier-Stokes equations A numerical scheme Advection Upstream Splitting Method (AUSM) has been selected. Navier-Stokes solver along with relaxation method has been used for the simulation of real flow over a circular cylinder. Pressure distribution and heat flux over the surface of cylinder has been compared with experiment results of Hannemann. Present heat flux results over the cylinder compared well with experiment. Thus, real gas effects in hypersonic flows can be modeled through energy relaxation method.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.5
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• pp.623-628
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• 2006

Laser material processing is a very fast advancing technology for various industrial applications. because of many advantages. Its major advantage of less and controlled heat input has been exploited successfully for the very critical application of aluminium alloy welding. This study suggested the occurrence source of weld-defects and its solution methods in a welding of lithium ion battery by pulsed Nd:YAG laser. In experiment. battery case has changed over joint geometry from welding of side position to flat one. In the case of a electrolyte injection hole in order to seal it. welding is carried out after pressing Al ball. At this time. an eccentric degree. contact length and gap are worked as a major parameters. As improving the method of Al ball pressing. it was able to reduce an eccentricity. increase the contact length and decrease gap. As a results of a experiment. a sound weld bead shape and crack-free weld bead can be obtained.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.339-343
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• 2005

Laser material processing is a very fast growing technology for various industrial applications, because of many advantages. Its major advantage of less and controlled heat input has been exploited successfully for the very critical application of aluminium alloy welding. This study suggested the occurrence source of weld-defects and its solution methods in a welding of lithium ion battery by pulsed Nd:YAG laser. In experiment, battery case has changed over joint geometry from welding of side position to flat one. In case of a electrolyte injection hole in order to seal it, welding is carried out after pressing Al ball. At this time, an eccentric degree, contact length and gap are worked as a major parameters. As improving the method of Al ball pressing, it was able to reduce an eccentricity, increase the contact length and decrease gap. As a results of a experiment, a sound weld bead shape and crack-free weld bead can be obtained.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.1
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• pp.1-5
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• 2000

Leaf area is critical for crop light interception, and thereby has a substantial influence on crop yield. This experiment was conducted to characterize the development of soybean [Glycine max (L.) Merr.] leaf area. Plastochron index and leaf relative growth rate of Jackson was contrasted with the PI416937, which also has demonstrated tolerance to drought. First, plastochron ratio (PR) and plastochron index (PI) were evaluated in greenhouse to compare the leaf growth rate between two genotypes under well-watered condition. There was reasonable constancy of PR between two genotypes. The PR means of Jackson and PI416937 were 0.41 and 0.44, respectively. A fairly smooth increase of PI during vegetative stage was observed. Second, the relative growth rates were graphed against leaf area, normalized with respect to final leaf area, under well-watered and water-deficit conditions. Leaf growth was sustained longer in well-watered condition than water-deficit condition and there was a sizable proportion of leaves which was ceased earlier their growth in water-deficit condition compared to well-watered condition. The leaf relative growth rate of Jackson until leaves had completed at 45% of their growth during water deficit period was higher than that of PI416937.