• 자원리싸이클링
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• 제28권6호
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• pp.87-95
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• 2019

본 연구에서는 인쇄회로기판(PCB) 제조 공정 중 발생한 슬러지 내 구리를 회수하기 위한 건식야금 공정 변수에 대해 조사하였다. 에칭 및 도금 공정에서 발생한 슬러지는 전처리 공정을 통해 수분과 유기물을 제거하였다. 열역학 상평형 계산을 통해 평형상과 슬래그 시스템을 선정하였으며, 유가금속 회수율에 미치는 건식야금 공정 변수에 대하여 조사하였다.

• 열처리공학회지
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• 제28권3호
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• pp.139-145
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• 2015

Effects of austenitizing, cryogenic treatment and tempering conditions on the phase change, microstructure and Vickers hardness value have been studied in STD11 steel for tool and die. The volume fraction of retained austenite increased with a rise in austenitizing temperature, while the volume fraction of eutectoid $M_7C_3$ carbides decreased. The retained austenite could be reduced by cryogenic treatment i.e., maintaining at $LN_2$ temperature ($-196^{\circ}C$) for 12hrs but a little amount of retained austenite did not transform to martensite further although holding time increased to 24 hrs or more. The microstructure of the quenched and then cryogenictreated specimen showed nano-sized and needle-shaped carbides in matrix due to the decomposition of martensite by tempering, but that of the one without cryogenic treatment still revealed retained austenite by tempering even at $500^{\circ}C$.

• 대한기계학회논문집
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• 제19권4호
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• pp.1023-1032
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• 1995

The multiple cooperating robot system plays an important role in the research of modern manufacturing system as the emphasis of production automation is more on the side of flexibility than before. While the kinematic and dynamic analysis of a single robot is performed as an open-loop chain, the dynamic formulation of robot in a multiple cooperating robot system differs from that of a single robot when the multiple cooperating robots form a closed kinematic chain holding an object simultaneously. The object may be any type from a rigid body to a multi-joint linkage. The mobility of the system depends on the kinematic configuration of the closed kinematic chain formed by robots and object, which also decides the number of independent input parameters. Since the mobility is not the same as the number of robot joints, proper constraint condition is sought. The constraints may be such that : the number of active robot joints is kept the same as mobility, all robot joints are active and have interrelations between each joint forces/torques, two robots have master-slave relation, or so on. The dynamic formulation of system is obtained. The formulation is based on recursive dual-number screw-calculus Newton-Eulerian approach which has been used for single robot analysis. This new scheme is recursive and compact symbolically and may facilitate the consideration of the object in real time.

• 한국세라믹학회지
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• 제46권1호
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• pp.53-57
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• 2009

The h-BN powder was synthesized by amorphous $B_2O_3$ and activated carbon at $1550^{\circ}C$ in nitrogen atmosphere, whose properties were examined according to $MgB_6$ addition. Amount of $MgB_6$ addition was varied in the range of $0{\sim}$10\;wt% of the initial mixture. It was observed that $MgB_6$ addition led to an increase in the amount and the grain size of h-BN and decrease in the amount of $B_4C$ forming. When $MgB_6$ added 5 wt%, the amount and crystallinity of h-BN increased as the holding time at the synthesis temperature was prolonged. It was also confirmed that the regularity of three-dimensional ordering of h-BN increases.

• Journal of Welding and Joining
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• 제24권6호
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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.

• 열처리공학회지
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• 제12권1호
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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.

• 한국축산식품학회지
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• 제18권1호
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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).

• 한국식품과학회지
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• 제25권2호
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• pp.171-173
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• 1993

냉장고내 공기의 청정장치로 자외선 공기순환식 살균장치를 개발할 목적으로 6 watt 자외선 램프와 순환 fan을 사용하여 공기 청정장치를 설계, 제작하였다. 자외선량은 Bacillus subtilis 포자의 D value의 5배에 이르게 하였으며 순환공기의 유속은 0.785 m/s이었으며 공기의 살균부 체류시간은 0.382 s이었다. 동 장치를 실내공기, 부패 건초 분말과 Bacillus subtilis 포자 현탁액으로 오염시킨 공기를 실온에서 80% 청정시키는 살균효과를 거두어 냉장고용 공기청정기를 설계하는데 필요한 자료를 얻었다.

• 한국정밀공학회지
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• 제28권9호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
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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.