• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.97-100
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• 1997

A new control method for the robust position control of a brushless DC(BLDC) motor using the asymptotically stable adaptive load torque observer is presented. A precision position control is obtained for the BLDC motor system approximately linearized using the field-orientation method. And the application of the load torque observer is published in [1] using fixed gain. However, the flux linkage is not exactly known for a load torque observer. Therefore, a model reference adaptive observer is considered to overcome the problem of the unknown parameter in this paper. And stability analysis is carried out using Liapunov stability theorem. As a result, asymptotically stable observer gain can be obtained without affecting the overall system response. The load disturbance detected by the asymptotically stable adaptive observer is compensated by feedforwarding the equivalent current having the fast response.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.214-216
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• 2005

The PAL (Pohang Accelerator Laboratory) is persuading to construct a SASE-XFEL facility (PAL XFEL) that supplies coherent X-rays. The bright and stable electron beam is essential for the PAL XEL. The electron beams has to have an emittance of 1.0 mm-mrad, a peak current of 3 kA, and a low energy spread of 1.0 MeV. In order to provide reasonably stable SASE output, the RF stability of 0.02% rms is required for both RF phase and amplitude. This is a technologically challenging issue for PAL XFEL. An inverter technology is to be applied to charge the PFN of a new modulator. Therefore, a new inverter system should provide very stable charging performances. This paper presents the development of an ultra stable klystron-modulator with an inverter power supply.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.245-250
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• 2004

The discharge current oscillation has been measured for various hollow anode widths and its axial positions using a 1㎾-class anode layer hall thruster. As a result, there were thresholds of magnetic flux density for stable discharge. The plasma structure inside the hollow anode was numerically analyzed using the fully kinetic 2D3V Particle-in-Cell (PIC) and Direct Simulation Monte Carlo (DSMC) methods. The results reproduced both stable and unstable operation modes. In the stable operation case, which corresponds to the case with low magnetic flux, the plasma penetrated into the hollow anode deeper than the case with higher magnetic flux density case. This suggests that comparably large substantial anode area should contribute to stable operation.

• Journal of Microbiology and Biotechnology
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• v.29 no.1
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• pp.55-58
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• 2019

Development of stable rCHO cell lines is still time consuming and labor intensive, although it is a critical step in the commercial development of recombinant antibodies. The current work demonstrates, for the first time, that electroporation of CHO cells with DMSO can enhance stable expression of recombinant antibodies in rCHO cells. Electroporation with DMSO resulted in an average 3.7-fold and 2.8-fold increases in expression levels of aflibercept and pembrolizumab, respectively, in pools of stable rCHO cells. It also resulted in an average of 2.2-fold and 2.6-fold increases in the expression of aflibercept and pembrolizumab, respectively, in single-cell derived rCHO clones. Simple batch cultures of rCHO cell clones with the highest expression produced 1.0 g/l for aflibercept and 1.4 g/l for pembrolizumab without a time-consuming gene amplification process. Electroporation with DMSO also shortened the development of rCHO cell lines to 2-3 months, allowing rapid establishment of stable rCHO cell lines with a desirable expression level antibodies.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.117-122
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• 2015

Our research team proposed a flux-offset type fault current limiter as a new limiter. The flux-offset type fault current limiter uses a fault current limit technology based on the flux offset principle of the primary and secondary windings of a transformer. Stable fault current limit characteristics were achieved through a preliminary study. However, it was discovered that the initial fault current was not limited. Therefore, in this paper, a high-speed interrupter and a superconducting element were separately applied to the secondary winding of the flux-offset type fault current limiter and the operating characteristics were comparatively analyzed. In the experiment, when the superconducting element was applied to the secondary winding of the transformer, the initial fault current was limited while the limitation in the operation time was further shortened.

• Journal of Environmental Science International
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• v.22 no.8
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• pp.999-1007
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• 2013

Electrochemical degradation of phenol was evaluated at DSA (dimensionally stable anode), JP202 (Ru, 25%; Ir, 25%; other, 50%) electrode for being a treatment method in non-biodegradable organic compounds such as phenol. Experiments were conducted to examine the effects of applied current (1.0~4.0 A), electrolyte type (NaCl, KCl, $Na_2SO_4$, $H_2SO_4$) and concentration (0.5~3.0 g/L), initial phenol concentration (12.5~100.0 mg/L) on phenol degradation and $UV_{254}$ absorbance as indirect indicator of by-product degraded phenol. It was found that phenol concentration decreased from around 50 mg/L to zero after 10 min of electrolysis with 2.5 g/L NaCl as supporting electrolyte at the current of 3.5 A. Although phenol could be completely electrochemical degraded by JP202 anode, the degradation of phenol COD was required oxidation time over 60 min due to the generation of by-products. $UV_{254}$ absorbance can see the impact of as an indirect indicator of the creation and destruction of by-product. The initial removal rate of phenol is 5.63 times faster than the initial COD removal rate.

• Journal of Welding and Joining
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• v.29 no.6
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• pp.77-81
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• 2011

In most industry, manual GTAW welding is preferred for formation of stable back bead in root weld of butt joint. However, manual GTAW welding has low productivity as compared with GMAW, also it has unstable bead quality which depend on skilled workers. So it is necessary to develop process of root pass welding by using automation GMAW that have stable back bead formation and high productivity. In this paper, the design of U-groove with 3mm root face was applied to extend the tolerance of misalignment in condition of standard root gap 1.5mm. Consequently, for the formation of stable back bead in root pass of butt welding, in case of the narrow root gap(0.5mm) the large arc force was applied by increasing the current and voltage. In case of the large root gap(2.5mm), the small arc force was applied by decreasing the current and voltage. Considering the various root gap, the required deposited metal was controlled by welding speed only.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.67-68
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• 2016

The accurate measurement of magnet power supplies (MPS) output currents is essential to delivering stable and repeatable currents to magnets in particle accelerators. An essential element in guaranteeing and evaluating the required performance is the current measurement device and methode. In this paper, we discuss instrument and methods for precision current measurement and performance of the PLS-II MPS.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.523-524
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• 2008

Proposed battery charger is a economic candidate because that is simple and small size. The circuit has linearly operational power stage. That use small size buffer with small driving current and large power MOS gate capacitance. The simulation result show that charging current is stable and has low ripple.

• Journal of Welding and Joining
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• v.20 no.5
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• pp.127-133
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• 2002

In this study, metal transfer characteristics in pulsed current metal inert gas (MIG) welding of aluminum was investigated. Based on the metal transfer characteristics from direct current electrode negative MIG welding, the one drop per one pulse(ODOP) condition was predicted and compared with experimental data. The results indicated that experimental pulse range for the ODOP condition is wider than that predicted from the DCEP MIG welding data. In addition, more stable metal trnasfer behavior was obtained at the higher end of the ODOP condition.