• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.2
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• pp.136-143
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• 1988

This study was performed to provide the optimal conditions of quantitative analysis for free amino acid in fermented protein foods. The water extractable free amino acid from dairy fermented foods was extracted effectively at $75^{\circ}C$ for 40 min., while it were extracted from fermented soy products at $40^{\circ}C$ for 3 hours. A close results of free amino acid content to those from amino acid analyzer were obtained using OPDA method with lysine standard after deproteinizing with 1% picric acid. 95% ethanol used as a deproteinizing reagent could give a comparable results to those from picric acid treatment in determining free amino acid content using OPDA method. Therefore, ethanol treatment was more recommendable than picric acid treatment which has some troubles in removing excess picric acid through Dowex resin column. The most desirable precipitation method for free amino acid determination using TNBS method was 95% ethanol treatment among the various deproteinizing procedure. The copper salt method was not suitable owing to its lacking reproducibility and pronounced discrepancy in determining free amino acid.

• Elastomers and Composites
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• v.45 no.2
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• pp.94-99
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• 2010

340 nm UV radiation of $2500\;kJ/m^2$ irradiated a thermoplastic elastomer (TPE) specimen used for interior and exterior materials of a car. After the UV irradiation, the black sample surface was changed to gray. Materials on the aged sample were collected and analyzed using GC/MS, but significant materials were not found. Lots of small cracks were found on the aged specimen surface. Whitening phenomenon of the aged sample disappeared by brushing or searing with a fire on the aged surface. After brushing or searing with a fire, small cracks on the surface vanished. Samples before and after the aging, and the treated samples with brush or fire were analyzed using image analyzer, SEM, EDX, and ATR and the results were compared. The vanished whitening phenomenon by brushing or searing was explained with filling the small cracks by polypropylene of TPE.

• Journal of Animal Science and Technology
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• v.51 no.1
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• pp.53-60
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• 2009

Thirty one Hanwoo steers were used in a completely randomized design experiment to see the effects of concentrate feeding method (group vs. individual feeding) and age at slaughter (26 vs. 28 months of age) on growth performance, feed intake and carcass characteristics. Steers were randomly assigned to one of four groups, G26 (group feeding slaughtered at 26 months of age), G28 (group feeding slaughtered at 28 months of age), I26 (individual feeding slaughtered at 26 months of age) or I28 (individual feeding slaughtered at 28 months of age). Amount of concentrate were restricted to 1.5% of BW for the growing period and 1.8% of BW for the early fattening period in both groups. For the late fattening period, concentrate were given ad libitum for G26 and G28, but were given up to 1.7% of BW for I26 and I28. Average daily gains were higher in individual feeding groups (I26 and I28) than those in group feeding groups (G26 and G28) for the early fattening period (p<0.05). ADGs were higher in group feeding groups than those in individual feeding groups (p<0.05). Concentrate intake in individual feeding groups tended to be higher compared to that in group feeding groups for the early fattening period, but tended to be higher in group feeding groups compared to that in individual feeding groups for the late fattening period. Feeding method or slaughter age had no significant effects on carcass characteristics, yield grade and quality grade. Shear force and tenderness of longissmus muscle were higher in groups slaughtered at 28 months of age than in groups slaughtered at 26 months of age (p<0.05). Feeding method or slaughter age had no effects on cooking loss, water holding capacity, juiciness, flavor, moisture, protein and fat of longissmus muscle.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.342-349
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• 1998

A multipurpose TLD readout system for radiation dosimetry and thermoluminescence study is constructed and its characteristics are investigated. The thermoluminescent lights are measured by a PM tube and the current-to-frequency converter. TLDs are heated by platinum heater and the heating rate is linearly varied. Measurement of the glow curve and control of the whole system have been done by a personal computer equipped with an interface board. The automatic gain control can be done by the control software. The lower detection limit of the system is about $10\;{\mu}Gy$ and dose response is linear.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.715-723
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• 1999

Magnesium has been used as wheel materials in the automotive industry for more than 20 years. The magnesium wheels, which are lighter by 25% than aluminum wheels, provide easy controllability providing excellent road holding by the reduction of weight. The purpose of this work is to develop cast AZ91D alloy wheel by sand cast and permanent mold cast. The fluxless melting with the protective gas $(SF_6+CO_2)$ was Performed to eliminate oxidation of melt and impurity. The transfer of molten magnesium to the mold was done by using gas-pressurized Pump system through the heated pipe. The mechanical properites of AZ91D alloy wheel were investigated as a function of heat treatment, ingot composition.

• Journal of Welding and Joining
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• v.28 no.1
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• pp.92-99
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• 2010

For the last couple of decades many studies have been carried out to find out solutions to improve the effectiveness and productivity of the plate forming process. The practical way for the automation of the plate forming process has not been, however, developed yet. Since the characteristics of heating machines may be different form each other, it is necessary to investigate the thermal deformation characteristics of the heating machine to be used in the automation system. And their characteristics may be updated as new information about thermal deformation by heating is accumulated. In this paper, data base system has been constructed based on the results of experiments and numerical analyses, which will be used in deriving the deformation estimation formula. The computer code which can automatically derive the deformation estimation formula has been also developed. This paper also illustrates how the formula is updated as experimental data are added. From the present findings, it can be said that the automatic deriving procedure may be important in the automated plate forming system since the heating line information to be generated must be directly influenced by the deformation estimation formula.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.51-57
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• 1998

This paper proposed a novel SIT high frequency resonant inverter having drive signal phase shift control function. Phasor control type inverters using SIT can realize a power conversion on the high switching frequency with low switching loss. Especially, the high output power can be abstained by connecting the output voltage of two unit inverters In serIes. The stability of system using protection circuit for over current and the automatic follow-up control with load variation by PLL is presented. This inverter produce approximately sinusoidal waveform at a high frequency, switching frequency ranging from 180[kHz] to 220[kHz], and is applied to the 2[kW] induction heating. The operating characteristics of this inverter circuit are discussed from a theoretical point of view and compared with experimental results. results.

• The Journal of the Petrological Society of Korea
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• v.20 no.3
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• pp.161-172
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• 2011

Open beaker digestion method is routinely used as the sample preparation technique for trace element determination of rock samples by inductively coupled plasma mass spectrometry, With this method, however, dissolution of Zr and Hf is not always guaranteed especially when the samples contain refractory minerals. In this study, glass bead digestion technique was compared with conventional open beaker digestion technique for the sample preparation of three USGS rock standards such as AGV-2, BHVO-2, and G-3. Thirty trace elements including rare earth elements were analysed by ICP-MS and ICP-AES. There were no clear differences in analytical results for the AGV-2 and BHVO-2 standards between the two techniques, but Zr, Hf, Y, and middle- to heavy- rare earth element concentrations of the G-3 standard prepared by open beaker digestion technique were significantly lower than the recommended values. This can be attributed to the presence of refractory mineral zircon. On the contrary, all the analytical results of the G-3 standard prepared by glass bead digestion technique were in good agreement with the recommended values, indicating complete dissolution of zircon. The analytical results show that the volatile elements such as Pb and Zn were not lost during the preparation of glass bead. Low dilution glass bead digestion technique described here will be very helpful to enhance precision and accuracy of trace element analysis for geological samples containing refractory minerals.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.513-520
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• 2020

Here, we evaluated the functional properties of histidine-containing low-molecular-weight (LMW) peptides obtained from tuna waste meats. As with histidine-related components composed of histidine, 1-methyl histidine and anserine, histidine-containing LMW peptides exhibited high α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging effect in a dose-dependent manner. Among the histidine-related dipeptides, anserine exhibited the highest reducing power followed by carnosine. By comparison with dipeptides, tuna extracts also showed similar reducing power and the activity was in a dose-dependent manner. In addition, the antioxidant activities of tuna extracts such as DPPH radical scavenging effect, reducing power, superoxide dismutase activities, and peroxide value of linoleic acid were affected by the various extraction methods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1289-1298
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• 2014

Pavement crack sealing method, which is one of the methods to maintain and repair the road, prevents the extending of cracks by repairing cracks in its early occurrence and has already been applied to many roadworks in advanced foreign country for a long time. But in the conventional crack sealing method, traffic accidents occur frequently during the repair because it's commonly performed on the heavy traffic road or highway. It also has some difficulties in securing the safety of workers from the risk of burns caused by heated sealant. In an effort to solve these problems, automated pavement crack sealing machines such as ARMM, OCCSM, TTLS have been developed in advanced foreign country since early 1990s. Also APCS in 2004 and ACSTM in 2013 were already developed domestically. However, since these automated crack sealers developed from a number of research institutions have different test-bed conditions and productivity measurement models, it's difficult to compare and evaluate them objectively. In this study, the image processing time of the respective machines and the movement time of each motion on the work process were estimated by using fully autonomous mapping and semi-automatic mapping in order to measure the productivity in the same environmental conditions. In addition, the productivity measurement test-bed reflected domestic road characteristics was designed to estimate and compare the productivity of the automated crack sealing machines.