• Journal of Advanced Marine Engineering and Technology
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• v.29 no.8
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• pp.938-945
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• 2005

The microstructure evolution in hot forging process is composed of dynamic recrystallization during deformation as well as grain growth during dwell time. Therefore, the control of forging parameters such as strain, strain rate. temperature and holding time is important because the microstructure change in hot working affects the mechanical properties. Modeling equations are developed to represent the flow curve. grain size. recrystallized volume fraction and grain growth phenomena by various tests. The developed modeling equations were combined with thermo-viscoplastic finite element modeling to predict the microstructure change evolution during hot forging process. The large exhaust valve spindle (head diameter of 512mm) was simulated by closed die forging with hydraulic press and cooled in air after forging. The preform was heated to each 1080 and 1150$^{\circ}C$. Numerical calculation was performed by DEFORM-2D. a commercial finite element code. Heat transfer can be coupled with the deformation analysis in a non-isothermal deformation analysis. In order to obtain the fine and homogeneous microstructure and good mechanical properties in forging. the FEM would become a useful tool in the simulation of the microstructure development. In forging, appropriate temperature, strain and strain rate and rapid cooling are required to obtain the fine grain microstructure The optimal forging temperature and effective strain range of Nimonic 80A for large exhaust valve spindle are about 1080$\∼$l120$^{\circ}C$ and 150$\∼$200$\%$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1611-1619
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• 2015

This study examined the toughness improvement of a track shoe used as the undercarriage of excavator and bulldozer parts. The excavator is operated under poor conditions, such as the build-up field and quarry. Therefore, the track shoe requires high strength and impact toughness to endure immense shock while at work. The track shoe was made of heat treated boron steel. The sufficient possibility of hardenability with the theoretical Jominy curve for boron steel was confirmed while quenching. The Taguchi orthogonal array experiment method was used to optimize the process variables, such as area reduction ratio and heat treatment conditions (tempering temperature and holding time), to achieve toughness improvement. The toughness of the track shoe increased with increasing area reduction, and a tempering temperature of $210^{\circ}C$ and a tempering time of 80 min are beneficial for improving the toughness of the track shoe.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.1
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• pp.1-10
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• 2010

This was conducted to investigate the dietary assessment, food preferences, snack intake, priority order in food purchase, and knowledge of diet of full-time housewives and working housewives through the use of a questionnaire. The participants (127 working housewives and 86 housewives) were selected at random from Seoul and its vicinity. The predominant job reported by working housewives was saleswomen and specialized job (20.7%). The average monthly income of both housewives and working housewives ranged from 3,000,000 to 5,000,000 won. Forty percent of housewives consumed more meat, fish, eggs, beans, and tofu, while 50.0% of housewives ate vegetables other than kimchi at every meal, 51.2% of housewives consumed one serving of fruit and one cup of fruit juice, 45.3% of housewives consumed three regular meals, and 60.5% of housewives consumed a balanced diet when compared with working housewives (p<0.05). Working housewives consumed beverages, ice cream, milk, and dairy products, while housewives consumed breads, sweet potato, potato, and fruit as snacks. The preference that most often led to food selection was flavor among working housewives (67.7%) and housewives (64.0%). Both working housewives and housewives always confirmed the day of food production. Generally, housewives were more interested in learning about food, creating a dietary plan, nutrient loss during cooking and reducing waste food when compared with working housewives. Housewives appeared to have better dietary assessment and knowledge than working housewives. Accordingly, it is advisable to prepare more systemic education programs for working housewives.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.6
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• pp.88-100
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• 1998

In this paper, an algorithm for a real-time automatic fingerprint identification system is proposed. The fingerprint feature volume is extracted by considering distinct and local characteristics(such as intensity and image quality difference etc.) in fingerprint images, which makes the algorithm properly adaptive to various image acquisitionj methods. Also the matching technique is designed to be invariant on rotation, scaling and translation (RST) changes while being capable of real-time processing. And the classification of fingerprints is performed based on the ridge flow and the relations among singular points such as cores and deltas. The developed fingerprint identification algorithm has been applied to various sets of fingerprint images such as one from NIST(National Institute of Standards and Technology, USA), a pressed fingerprint database constructed according to Korean population distributions in sex, ages and jobs, and a set of rolled-than-scanned fingerprint images. The overall performance of the algorithm has been analyzed and evaluated to the false rejection ratio of 0.07% while holding the false acceptance ratio of 0%.

• Journal of Welding and Joining
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• v.21 no.3
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• pp.78-84
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• 2003

The changes of microstructure and hardness of TLP bonds of directionally solidified Ni base superalloy, GTD-111, with variation of homogenizing and aging treatment were investigated. The specimens were bonded at 1403K for 7.2ks using different insert metals such as MBF-50, MBF-80 and MBF-90 and they were homogenized at 1393K with various holding time. At center of bonded interlayer homogenized for hold time 30h, the contents of aluminum and titanium were approximately 90% and 95% of base metal, respectively. In this study, aging was performed at three different kinds : one step aging ; 1113K $\times$ 16h, two step aging ; 1113K $\times$ 10h ⇒ 1103K $\times$ 10h, three step aging ; 1113K $\times$ 10h ⇒ 1103K $\times$ 8h ⇒ 922K $\times$ 24h. ${\gamma}$' volume fraction and hardness of joints were high in the sequence of one step, two step and three step aging, whereas ${\gamma}$' volume fraction and hardness of joints obtained by three step aging treatment were higher than those of raw material. Tensile properties of joints bonded with MBF-80 and MBF-90, homogenized at 1393K for 30h and then three step aged became excellent than those of raw material, however, joint bonded with MBF-50 was poor.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.1053-1055
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• 2002

Recently CRT is getting large-sized, Flatness and High Fine Pitched in the meantime the raw material for shadow mask is in rapid progress of thinness, Low Thermal Expansion and high strength.Until now we have used AK(Aluminum Killed) & Invar(Fe-Ni alloy) materials for main raw material of shadow mask component. However recently Nb and Co addition and Nb+Co addition, which has advantage of Low Thermal Expansion and High Strength. has been developed as well as applying in mass production as CRT's trend has become more flat and fine pitch. Among of them, Co addition has been mass production as forming type (Flat CRT) with the beneficial effect of low thermal expansion & high strength for the first time. Since then Nb+Co addition has been used in mass production by the request of much higher strength of shadow mask component. In case of Nb addition, It's thermal expansion coefficient is a little lower than normal Invar and a little higher than Co addition, meanwhile Its Mechanical property is almost similar to Co Addition. The used samples of this experiment are 36%Ni + Fe, 32%Ni + 5%Co + Fe, 32%Ni + 5%Co + 0.3%Nb + Fe, 32%Ni + 0.3%Nb + Fe with heat treatment temperature of 600$^{\circ}C$, 650$^{\circ}C$, 700$^{\circ}C$, 750$^{\circ}C$, 800$^{\circ}C$, 850$^{\circ}C$, 900$^{\circ}C$ respectively under the condition of 15min holding time. After heat treatment, we have observed the change of mechanical property with addition of small elements through mechanical property investigation and metal structure observation as well as transition of thermal expansion coefficient by measuring of thermal expansion coefficient at 850$^{\circ}C$. In conclusion, 5%Co addition indicates that its thermal expansion coefficient is very similar under the condition of at 850$^{\circ}C$ for 15min 's heat treatment. From the experimental result it is suggested that Co addition is mostly suitable for Doming property and Nb addition is mostly suitable for Drop property.

• Korean Journal of Veterinary Research
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• v.34 no.1
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• pp.37-47
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• 1994

The effects of the novel compound GS-386 on the calcium current were investigated in rabbit atrial myocytes. The calcium current was recorded during various depolarizations of 200 ms duration from a holding potential of -40 mV using the whole cell patch clamp technique. The calcium current was activated from -30 mV, reached maximum amplitude at +10 mV and almost disappeared at +50 mV. Superfusion of GS-386 led to a reduction of the calcium current amplitude dose-dependently and $ED_{50}$ was $2.5{\times}10^{-7}M$. But the dependence of the calcium current on the membrane potential was not altered by GS-386. The inactivation of the calcium currents showed single exponential curves in both before and after application of GS-386. The inactivation time constants before and after application of GS-386 were almost the same(35 ms and 32.5 ms). The steady-state inactivation curve of the calcium current was not shifted by GS-386. The calcium currents both before and after application of GS-386 recovered completely in 1 sec and the recovery time constants were about 200 ms in both cases. From the above results it is concluded that the novel compound GS-386 has calcium antagonistic property decreasing the calcium current.

• Food Science of Animal Resources
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• v.32 no.3
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• pp.268-273
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• 2012

The aim of this study was to evaluate the effects of tumbling condition (time and temperature) on the quality characteristics of restructured chicken breast ham. Tumbling conditions were 10, 30, and 60 min at 3 or $-3^{\circ}C$, respectively. After tumbling, quality characteristic regarding the treatments processed by each condition were measured. There were no significant differences in pH levels among tumbling time or temperature. Treatments involving 60 min of tumbling had significantly higher water holding capacity (WHC) than that tumbled for 10 min, but WHC was not affected by the tumbling temperature. The tumbling condition at $-3^{\circ}C$ for 60 min demonstrated the most effective cooking yields for restructured chicken breast ham. Myofibrillar protein solubility of treatments tumbled for 60 min had the highest value of all, regardless of tumbling temperature. The hardness of treatments tumbled at $-3^{\circ}C$ were lower than those at $3^{\circ}C$; however, the springiness of treatments tumbled for 60 min were significantly higher than those regarding the treatments tumbled for 10 and 30 min. Therefore, tumbling technology for 30 min or more at $-3^{\circ}C$ can produce restructured chicken breast ham of excellent quality.

• Journal of Welding and Joining
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• v.25 no.5
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• pp.45-50
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• 2007

The Ni-base superalloy GTD111 DS is used in the first stage blade of high power land-based gas turbines. Advanced repair technologies of the blade have been introduced to the gas turbine industry over recent years. The effect of the filler metal powder on Transient Liquid Phase bonding phenomenon and tensile mechanical properties was investigated on the GTD111 DS superalloy. At the filler metal powder N series, the base metal powders fully melted at the initial time and a large amount of the base metal near the bonded interlayer was dissolved by liquid inter metal. Liquid filler metal powder was eliminated by isothermal solidification which was controlled by the diffusion of B into the base metal. The solids in the bonded interlayer grew from the base metal near the bonded interlayer inward the insert metal during the isothermal solidification. The bond strength of N series filler metal powder was over 1000 MPa. and ${\gamma}'$ phase size of N series TLP bonded region was similar with base metal by influence of Ti, Al elements. At the insert metal powder M series, the Si element fluidity of the filler metal was good but microstructure irregularity on bonded region because of excessive Si element. Nuclear of solids formed not only from the base metal near the bonded interlayer but also from the remained filler metal powder in the bonded interlayer. When the isothermal solidification was finished, the content of the elements in the boned interlayer was approximately equal to that of the base metal. But boride and silicide formed in the base metal near the bonded interlayer. And these boride decreased with the increasing of holding time. The bond strength of M series filler metal powder was about 400 MPa.

• Elastomers and Composites
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• v.49 no.3
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• pp.210-219
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• 2014

In this study, the acrylic pressure sensitive adhesive (PSA) for the optical functionality sheet was prepared by blending liquid isoprene rubber. The acrylic PSA was synthesized with butyl acrylate, acrylic acid, 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate. Toluene was used to a solvent for polymerization. Liquid isoprene rubber (LIR-50) was blended with the acrylic PSA and blend ratio was 0 ~ 50 wt%. According to the results, the adhesive transfer, which was the big problem of acrylic adhesive, was reduced with the addition of LIR-50. The secondary bonding of LIR-50 with substrate did not occurred due to absence of polar group in LIR-50. The peel strength and adhesive transfer were decreased by UV curing and the degreed of decrease depended on the amounts of photoinitiator and UV irradiation time. On the other hand holding power increased drastically by increasing amounts of photoinitiator and UV irradiation time.