• Journal of Welding and Joining
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• v.24 no.6
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• pp.13-20
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• 2006

Resistance spot welding is widely used for joining sheet metals in the automotive manufacturing process. Recently, servo-gun is used to increase the productivity and precise control the acting force. However, force control mechanisms have not been investigated with servo-guns until now. In this paper, it is proved that servo-motor current is proportional to torque and by experiment, experimental equation between servo-motor current and electrode force was derived. Algorithm for feedback control of electrode force was suggested using current measurement. In addition, applying soft touch method to this system the impact between electrode and specimen, which is the problem of air gun, could be reduced. Indentation made the force decrease in holding time of resistance spot welding. In order to overcome this problem, force compensation using the servo gun was used and it improved weld strength in good welding current range.

• Journal of the Korean Society for Heat Treatment
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• v.12 no.1
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• pp.9-20
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• 1999

The effect of post oxidation, water-quenched after holding in air for 5~420 seconds or cooling or furnace cooling, on corrosion resistance and phase formation characteristics of the surface layer of SM20C and SM45C carbon steels after gas nirtrocarbursing in the $NH_3-5%CO_2-N_2$ gas atmosphere at $580^{\circ}C$ for 3hours is studied. The compound layers of two steels consist of ${\varepsilon}-Fe_{2-3}N$, ${\gamma}^{\prime}-Fe_4N$ and $Fe_3O_4$, phases, however, the quantity of ${\gamma}^{\prime}-Fe_4N$ phase increases for the furnace cooled specimen compared to that of air cooling specimen. With increasing $NH_3$ content in the gas mixture and also increasing the keeping time in the air after gas nitrocarburising, the ${\varepsilon}-Fe_{2-3}N$ phase of compound layer increases, while the decreased current density recognizing the improvement of corrosion resistance are shown. the passive current density of SM45C steel is lower than that of SM20C steel at the same nitrocarburising conditions.

• Food Science of Animal Resources
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• v.18 no.1
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• pp.19-26
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• 1998

In order to study the tenderizing effect of the proteolytic enzyme, ficin, from fig fruit (Ficus carica L), the enzyme was purified from fig latex by precipitation and chromatography. The ficin separated from Bongraesi showed single band on SDS-PAGE. However, the ficin from Masui showed tow bands. The specific activity of ficin purified from Bongraesi species was 2.8 unit/mg protein and that from Masui species was 6.5 unit / mg protein. The amounts of ficin purified from 50 mL of crude latex of Bongraesi and Masui were 1,760 mg and 657 mg, respectively. the water holding capacity of beef decreased to the large extent, when sugar Bongraesi latex and Masui latex were added. The hardness of beef showed decreasing tendency with the time, however, after 60 min, it decreased and thereafter increased a little after 120 min. the hardness of beef decreased sharply with addition of the latex of Bongraesi and Masui. The Masui has more tenderizing effect than the Bongraesi. When meat was mixed with tenderizing agent(ficin) and not heated, the change of color showed significant difference (p＜0.01). when meat was mixed with tenderizing agent(ficin) and heated, the toughness showed significant difference (p＜0.01) and the softness showed significant difference (p＜0.001).

• Korean Journal of Food Science and Technology
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• v.25 no.2
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• pp.171-173
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• 1993

UV-ray air cleaner consisted of 6 watt UV lamp and fan was developed to sanitize air of refrigerator. Light intensity of the lamp showed 5 times of D value of Bacillus subtilis and air velocity around the lamp in holding section was 0.7 m/s, giving 0.33s of the resident time. The performance of air cleaner was tested with bacterial contaminator sprayed with suspension of Bacillus subtilis and hey powder. The device effectively decreased 80% of the population of airborn spore after 100 min operation at room temperature.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1086-1093
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• 2011

To fabricate the aluminum alloys with good drawability, the textures evolution of the AA5182 sheets due to the change of lid parameter after rolling and subsequent annealing was studied. The measurement of the deformation textures was carried out for the sheets with high reduction ratio and the change of the recrystallization texture was investigated after heat-treatments of the rolled sheets in various I/d parameters. Rolling without lubrication and subsequent annealing led to the formation of favorable rot-$C_{ND}$ {001}<110> and ${\gamma}$-fiber ND//<111> textures in AA5182 sheets. From the results, the ${\gamma}$-fiber ND//<111> component well evolved during rolling at high lid parameter of 6.77. The initial shear deformation texture, especially, ${\gamma}$-fiber ND//<111> was not rotated during heat treatment in holding time of 180~7,200 seconds on AA5182 with I/d parameter of 6.77. Therefore, the AA5182 sheets were fabricated by controlling I/d parameter having well evolved ${\gamma}$-fiber ND//<111> which was advantageous in good drawability of the sheets.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.63-65
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• 2007

Recently with increase consumption of electric power, the scale of the electric system becomes bigger and complex. Then, it is increasing the hardship in the operation of electric system and the continuance of stability. Especially, as the differences between demand and supply in electric power keeping low frequency oscillating attenuation from electric power have been very important in the continuance part of stability. The more control time of electricity system is getting faster with digitalization the more stability of electricity system is getting worse. As solutions of these problems, by establishing Power System Stabilizing Controller putting PSS output signal and putting damping to vibration of the rotor at generators's AVR in area where is oscillated, We are willing to contribute the electricity system by holding in generator output vibration.

• Journal of Korea Multimedia Society
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• v.11 no.3
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• pp.323-330
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• 2008

In this paper, we propose a new fingerprint sensing method that can reduce orientation error. General fingerprint input methods need finger to be put on the surface of a sensor. It can cause of rotation problem and it affects the recognition result significantly. This improved input method can minimize the rotation of a finger by holding double-sided sensor with both thumb and index finger at the same time. Whenever fingerprint is impressed, it has nearly the same orientation because sensors are located between two fingers. As a result, we can get a better performance in fingerprint recognition system, but it may need more hardware cost.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.49
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• pp.379-405
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• 2011

With the fast growing of international trade and ever-changing trade environment Korea is facing more risks in international trade and they are getting more diverse and happen more frequent with high severity. Big firms of international trade are ready and treat the risks quite well, but small and medium size firms have hard time to manage the risks due to their poor understanding, not much capital to spend, and weak skills of risk management. Holding significant size of international trade of Korea, the small and medium size firms need systematic and integrated risk management and the K-sure(former Korea Export Insurance) can make a significant contribution to help them manage risks in international trade business. This study is proposing the adoption of ERM(Enterprise Risk Management) for international trade business of Korea. Especially for small and medium size firms of international trade, the K-sure may set up integrated risk management system to help them and promote the export growth, which is a great mission of K-sure.

• Journal of Powder Materials
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• v.23 no.1
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• pp.1-7
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• 2016

Cu-Mn compacts are fabricated by the pulsed current activated sintering method (PCAS) for sputtering target application. For fabricating the compacts, optimized sintering conditions such as the temperature, pulse ratio, pressure, and heating rate are controlled during the sintering process. The final sintering temperature and heating rate required to fabricate the target materials having high density are $700^{\circ}C$ and $80^{\circ}C/min$, respectively. The heating directly progresses up to $700^{\circ}C$ with a 3 min holding time. The sputtering target materials having high relative density of 100% are fabricated by employing a uniaxial pressure of 60 MPa and a sintering temperature of $700^{\circ}C$ without any significant change in the grain size. Also, the shrinkage displacement of the Cu-Mn target materials considerably increases with an increase in the pressure at sintering temperatures up to $700^{\circ}C$.

• Journal of Biosystems Engineering
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• v.15 no.2
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• pp.110-122
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• 1990

This study was undertaken to develop the feed rate control system for the head feed thresher by making use of the microprocessor and to evaluate the response of the system to a various threshing conditions. The control unit was composed of one-board microcomputer. The speed of the wet-paddy feeding chain was controlled by dc moter with PI controller. It was used the adaptive control method to maintain the constant feed rate regardless of the fed rice varieties. The sliding type potentiometer was used as the feed rate sensor, which was attached on the sheaf-holding apparatus. The mathematical models of the system components were derived and computer simulation was developed for investigating the parameters affecting on control performance and for estimating the response of the system. A one-board microcomputer-based feed rate control system developed in this study was properly functioned and assessed as adequate for the feed rate control system of the head feed thresher. Based on the simulation for the bundle feed, it was anticipated that the lower setting value of the cylinder speed(RL) is to be set higher than the limiting operational speed. In addition, the higher setting value of the cylinder speed(RH) is to be set lower than the limiting cylinder speed for threshing. The computer simulation for the continuous spread feed showed that the lower the setting value of straw layer thickness(LL) was set, the shorter the correction time. However, if too low LL may be established, the feed rate could not reach to its desired rate.