• International Journal of Precision Engineering and Manufacturing
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• v.6 no.2
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• pp.55-60
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• 2005

In order to develop the hydrostatic guideways driven by a core less linear motor for ultra precision machine tools, a prototype of guideway is designed and tested. A coreless linear DC motor with a continuous force of 156 N and a laser scale with a resolution of 0.01 ㎛ are used in the system. Experimental analysis on the static stiffness, motion errors, positioning error and its repeatability, micro step response and velocity variation of the guideway are performed. The guideway shows infinite stiffness within 50 N applied load in the feed direction, and by the motion error compensation method using the Active Controlled Capillary, 0.08 ㎛ linear motion error and 0.1 arcsec angular motion error are acquired. The guideway also reveals 0.21 ㎛ positioning error and 0.09 ㎛ repeatability, and it shows stable responses following a 0.01 ㎛ resolution step command. The velocity variation of feeding system is less than 0.6 ％. From these results, it is estimated that the hydrostatic guideway driven by a coreless linear motor is very useful for the ultra precision machine tools.

• Transactions of Materials Processing
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• v.17 no.1
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• pp.52-58
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• 2008

Tube hydroforming process is generally consisted with pre-bending, preforming and hydroforming processes. Among forming defects which may occur in tube hydroforming such as buckling, wrinkling and bursting, the wrinkling and bursting by local instability under excessive tensile stress mode were mainly caused by thinning phenomenon in the manufacturing process. Thus the accurate prediction and suitable evaluation of the thinning phenomenon play an important role in designing and producing the successfully hydroformed parts without any failures. In this work, the formability on hydroformed part for automobile, i.e. engine cradle, was evaluated using finite element analysis. The initial tube radius, loading path with axial feeding force and internal pressure, and preformed configuration after preforming process were considered as the dominant process parameters in total tube hydroforming process. The effects on these process parameters could be confirmed through the numerical experiments with respect to several kinds of finite element simulation conditions. The degree of enhancement on formability with each process parameters such as initial tube radius, loading path and preform configuration were also compared. Therefore, it is noted that the evaluation approach of the formability on hydroformed parts for lots of industrial fields proposed in this study will provide one of feasible methods to satisfy the increasing practical demands for the improvement of the formability in tube hydroforming processes.

• Korean Management Science Review
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• v.30 no.1
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• pp.125-137
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• 2013

The U.S. Army is capable and ready to deploy full-spectrum armed forces anywhere in the world as we have seen in Iraq and Afghanistan. This commitment is within the realm of logistics support that the readiness to support MRE(Meal Ready to Eat), according to the environment where the operation is on going. ROKA(Republic Of Korea Army) proceeds with the program to develop and reserve various MRE under the assumption of distinctive warfare operating environment. This study investigates to determine the amount of MRE consumption within various operating environment and details are as follows. First we ponder the concept of MRE and identified problems of the existing program. Second we also establish feeding rations by the types of MRE that is the base for calculation. Third we introduce MRE consumption algorithm and formula. Fourth and last we have applied our model to the program and analyzed the results. The present state of the estimation didn't reflect various warfare operating environment. Therefore we simulates theater wargame model to determine the consumption under various warfare operating environment. The result of this study is anticipated to contribute largely to the force enhancement as it mirrors of every circumstances of operating environment.

• Journal of the Semiconductor & Display Technology
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• v.13 no.1
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• pp.7-12
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• 2014

In this study, we investigate the effects of corona-discharge pre-treatment on the properties of carbon nanotubes (CNTs) which are used as flexible transparent electrodes. The CNTs are deposited on PET (polyethylene terephthalate) substrates using a spray coating method. Prior to the deposition of CNTs, the PET substrates are corona-treated by varying the feeding directions of the PET substrate and the numbers of treatments. The variations in the surface morphologies and roughnesses of the PET substrates due to corona-treatment are characterized via atomic force microscopy (AFM). Dynamic contact angles (DCAs) of the corona-treated PET substrates are measured and analyzed as functions of the treatment conditions. Also, the sheet resistances and visible-range transmittances of the CNTs deposited on PET substrates are measured before and after bending test. The experimental results obtained in this study provide strong evidences that the adhesive forces between CNTs and PET substrates can be substantially enhanced by corona-discharge pretreatment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.103-109
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• 2021

Fine chips generated by machining have an impact on machine failure and quality of machined products, it is necessary to remove the chips, so the microchip collection and removal device by rotating conveyor belt with neodymium permanent magnets was developed. In this research, to solve the problem for reducing the existing microchips in the tank, a micro-chip removal device by rotating conveyor belt with neodymium permanent magnets developed. In the development of micro-chip removal device, 3D CATIA modeling was used, and the flow analysis and the electromagnetic force analysis were performed with COMSOL Multiphysics program. To evaluate the performance of the prototypes produced, design of experiments (DOE) is used to obtain the effect of neodymium conveyor movement speed on chip removal for the ANOVA analysis of recovered powders. An experiment was conducted to investigate the effect of the conveyor feed rate on the chip removal performance in detail. As a result of the experiment, it was confirmed that the slower the feeding speed of the fine chip removing device, the more efficient the chip removal.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.165-170
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• 2013

An external gelation method in place of an internal gelation method applied to the fabrication process of an intermediated compound of Uranium Oxy-Carbide (UCO) kernel spheres for Very High Temperature Reactor (VHTR) fuel preparation is under development in Korea. For the preliminary experiments of the UCO kernel sphere preparation using an external gelation method, the carbon black dispersion experiments were carried out using a simulated broth solution. From the selection experiments of various kinds of carbon black through dispersion experiments in a viscous metal salt solution, Cabot G carbon black was selected owing to its dispersion stability, and the homogeneous dispersing state of carbon black particles in our system. For the effective dispersion of nano-size aggregated carbon black particles in a high viscous liquid, the carbon black particles in a metal salt solution were first de-aggregated with ultrasonic force. The mixed solution was then dispersed secondly by the use of the extremely high-speed agitation with a mechanical mixer of 6000 rpm after feeding the Poly Vinyl Alcohol (PVA) in the solution. This results in the broth solution with good stability and homogeneity alongside no further changes in physical properties.

• Journal of Animal Science and Technology
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• v.46 no.1
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• pp.97-106
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• 2004

The study was conducted to investigate the effects of practical variations in feed restriction, pre-slaughter handing and chilling regime on pork quality during ageing. A total of twenty male landraces were allocated into three treatments(i.e., pre-slaughter feeding, stress and chilling regime) in a factorial arrangement. pH, temperature, free calcium ions, WB-shear force, sarcomere length, cooking loss, drip loss and objective color were determined during rigor development and/or 1, 3, 7 d postmortem. Pre-slaughter chasing stress for approximately 15 min had no effects on pH/temperature profile and objective meat quality. There was an interaction(P < 0.05) between the fasting treatment and chi1ling regime for muscle temperature at pH 6.2. Sarcomere length indicated that the current experiment conditions did not induce muscle shortening, with 1.7 to 1.8 ${\mu}m$, in spite of a significant effect of the fasting treatment (P<0.01). Pigs fed until the morning of slaughter showed a low WB-shear force(P < 0.05) until 3 d at I "C. The treatment also resulted in a higher Hunter L* and a*(P < 0.05) at 24 h and 7 d. Fasted pigs showed a significantly(P < 0.05) reduced cooking loss. The current results indicated that feeding upon the morning of slaughter became detrimental on meat color and the negative effect on cooking loss were linearly elevated with increased ageing time. On the other hand, WB-shear force did not distinguishable after 3 d. Collectively, it appeared that feed restriction from a day before slaughter could produce more a desirable meat quality at the time of consuming. However, the limited effect of animal handling and chilling rate on meat quality is not necessarily to extend to that these do not affect pork quality, as that largely depends on experimental design.

• Journal of Life Science
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• v.22 no.5
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• pp.587-594
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• 2012

TMR (total mixed ration) feed was developed by adding mugwort and was fed to Korean black cattle. The effects on the physicochemical properties of the Korean black cattle, when fed mugwort, were investigated, as was the feasibility of producing beef with high quality and functionality. Korean black cattle were reared by using basal TMR (control) and basal TMR supplemented with mugwort of middle fattening 4.6% and late fattening 6.5% (treatment). The content of total catechin in Korean black cattle fed with the control and treatment was 0.262 and 0.379 mg/kg, respectively, while the content of epicatechin was 0.042 and 0.059 mg/kg, respectively, both of which were a significant increase from feeding the cattle TMR with mugwort ($p$ <0.05). There was no significant difference between the control and treatment in terms of $L^*$ (lightness), $b^*$ (yellowness), pH, VBN (volatile basic nitrogen) content, bacterial counts, water-holding capacity, freezing loss, thawing loss, cooking loss, cohesiveness, chewiness, shear force, and sensory score. TBARS (2-thiobarbituric acid reactive substances) and springiness for the control were significantly higher than the treatment ($p$ <0.05). The $a^*$ (redness), EDA (electron donating ability), hardness, and gumminess for the treatment were significantly higher than for the control ($p$ <0.05). These results suggest that the feed containing mugwort can be used to improve color and increase antioxidant ability as functional feed.

• Food Science of Animal Resources
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• v.27 no.2
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• pp.203-208
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• 2007

Organic duck's carcass weight was lower than general duck's because of the differences in breed and feeding method, but there was no difference in carcass percent among them. The rate of organic duck's fresh breast meat(17.62%) was significantly higher than that of general duck's(11.95%)(p<0.05). The rate of fresh leg meat rate was lower in organic duck, but there was no significant difference among them(p>0.05). The pH of breast and leg measured immediately after butchering were 6.48 and 6.73 in organic duck, respectively and there was significant difference among them(p<0.05). According to the sensory test, the texture, odor, tenderness, and taste showed better preference in organic duck than those of broiler chicken. According to above physicochemical analysis and sensory test, organic duck showed higher pH, higher shear force, and lower cooking loss. Therefore, it is considered to be very valuable to develop the exploitation of meat product in organic duck which had good quality and tastiness.

• Food Science of Animal Resources
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• v.29 no.1
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• pp.114-120
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• 2009

This study was conducted to determine the effect of feeding complex of wild chrysanthemum powder, probiotics and selenium on meat quality in finishing pigs ($LY{\times}D$). 25 pigs were randomly alloted to two treatments; C (basal diet), T (C diet added 0.3% wild chrysanthemum powder, 0.1% probiotics and 0.1% selenium). Pigs were slaughtered at approximately 110 kg final weight and chemical composition, physico-chemical characteristics, fatty acid composition and sensory test were measured in pork loin. Proximate composition, pH, water holding capacity, cooking loss, shear force and color were no differences among the tested samples. Texture properties of hardness in treatment were significantly higher than the control (p<0.05). Fresh meat of overall acceptance and cooked meat of tenderness, juiciness and overall acceptability in T were significantly higher than the control. Fatty acid compositions of myristic acid, palmitoleic acid, oleic acid, unsaturated fatty acid and monounsaturated fatty acid in T were significantly higher than the control.