• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.196-203
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• 2005

In this paper, a digital controller for satisfying time response requirements for UPS inverters is designed in a fixed sampling time. The CRA (Characteristic Ratio Assignment) is used as the continuous time design method to deal with the problems of overshoot and settling time. The main design approaches are the inward and outward approaches based on a double-loop feedback structure. The continuous-time controller is discretized by the emulation method. The performances of the proposed controller are evaluated through several simulations carried out with Simpower System Toolbox 3.0 from Simulink$^{(R)}.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.5
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• pp.462-467
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• 2013

This paper presents a modified disturbance observer (MDOB) for controlling two arms of a manipulator designed for a home service robot. The MDOB is slightly different from the original DOB in that it uses an accelerometer to measure acceleration of the robot arm. Then it uses the acceleration to estimate the disturbance to cancel out in the control loop. Relying on the acceleration information of the robot arm, a partial model-based control structure is formed. Experimental studies of position control of 2 DOF robot arm are conducted to evaluate the performance of the proposed position control by an MDOB method.

• ETRI Journal
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• v.31 no.5
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• pp.616-618
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• 2009

In this letter, a novel hybrid planar inverted-F antenna (PIFA) with a T-shaped slot on the ground plane is proposed. The loop structure formed by the feed line and shorting pin can be operated as a series and shunt inductance for the PIFA and the T-shaped slot antenna, respectively. The PIFA operates at a frequency of 1.75 GHz, while the T-shaped slot on the ground plane operates at 2.4 GHz by the same voltage feeding source. The height of the PIFA is 6.5 mm, and the size of an upper patch is designed to be 30 mm${\times}$16 mm. The measured relative impedance bandwidth of the PIFA and the T-shaped slot are about 12% and 21%, respectively. In addition, good antenna performance was achieved.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.79-85
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• 2010

In this paper, a directive antenna design with a combination of electric-magnetic radiators for an radio frequency identification(RFID) system is presented. To generate a directive antenna radiation pattern, a structure combining a dipole and loop antenna is presented. A reader antenna and tag antenna are proposed for the RFID system. For the reader antenna, the frequency bandwidth defined by $S_{11}$<-10 dB is approximately from 820~990 MHz. The forward and backward gain differences are 1.5~2 dBi. For the tag antenna, the frequency bandwidth is approximately from 860~920 MHz with a maximum gain of 3.58 dBi at 910 MHz. In both cases, directive radiation characteristics are observed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.552-555
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• 2008

The purpose of this study was to find a best condition of fabricating lead zirconate thin film by sol-gel method, especially to find mol ratio and post annealing temperature. Lead zirconate thin film was made by spin coating method. The ratios of Pb and Zr of precursors were 1:0.8, 1:1.0, and 1:1.2. Annealing temperature of films were $600^{\circ}C$, $700^{\circ}C$, and $800^{\circ}C$ for 1 minute. Crystal structure was observed from XRD and antiferroelectricity was observed from hysteresis curves. The optimum mol ratio of Pb:Zr is 1:0.8 and annealing temperature is $800^{\circ}C$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.462-465
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• 1995

In this research a 2-dimensional motion producer based on two linear motors was developed. When the tester provides some motion through the level attached to the upper moving part of the motion producer, it provides the arbitrary intertia, damping and stiffness characteristics without actual change in physical structure of the motion producer. That is, the active impedance is implemented by controlling input currents supplied to the linear motors. A PID controller with feedforward loop was used to control the currents and pre-processing of input velocity and accleration singals from the encoder and the current singnal from the motor driver circuit are conducted to improve the performance.

• Korean Institute of Interior Design Journal
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• no.13
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• pp.18-24
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• 1997

Museums after '70's shows remarkable development in public area as well as exhibiiton area. One of the main changes in recent museums is to extend the concept of circulatin area, which regarded solely as a corridor connecting exhibition areas, as a multiple function area with various service facilities. This study aims to outline atypological classification of exhibition area considering with circulation area in museum. On the base of two principal types of exhibition area, that is room type vs open plant type, 30 representative worldwide museums are analyzed and four different types are identified as a result. 1) Loop type as a rotating structure of serial exhibition rooms 2) Cluster type which produce complicated circulation with rooms lied one upon another 3) Centrum type which is specially available to multistory exhibition area 4) Loft type with maximum flexibi쇼 and accessbility.

• Journal of the Korean Society of Industry Convergence
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• v.11 no.2
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• pp.49-58
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• 2008

This study aims to identify the structure and system to make close relationship among planning elements, legal regulation and evaluation index toward sustainable development in the ecological housing estate. Through these close relationships the ecological housing estate could get more sustainability. With this consideration, this study consists of following three parts. First, we review the key issues of sustainability in ecological housing which are focused on the energy-efficient planning. Second, we extract the planning elements, legal regulation and evaluation index using the qualitative system dynamics that is found out all phenomenons from viewpoint of closed loop thinking and circular feedback system. Third, we analyse the correlationship among them in terms of energy efficient planning in the ecological housing estate. Finally, we summarize the findings toward sustainability in ecological housing estate through these analysis.

• Membrane and Water Treatment
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• v.9 no.1
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• pp.33-42
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• 2018

Microscopic examination of the activated sludge and morphological characterization of the flocs provides detailed information about the treatment process. The aim of this study is to investigate the morphological parameters of flocs obtained from a thermophilic jet loop membrane bioreactor (JLMBR) in different sludge retention times (SRTs), considering EPS and SMP concentration, hydrophobicity, zeta potential. The results showed that irregularity decreased with the increasing SRT. The compactness value was calculated to be less than 1 for all SRTs. However, the sludge had a more compact structure when the SRT increased. Zeta potential increased whereas hydrophobicity and floc size reduced, with increasing SRT. Furthermore, 2-D porosity calculated using the hole ratio was higher at greater SRTs. Hence, there was a significant correlation between the results obtained using the imaging technique and operation conditions of thermophilic JLMBR.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.235-237
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• 2006

In this paper, the previous 2-D gradient coil design method using loop current elements is extended to 3-D or multi-layer structures which is useful for various MRI applications including MR microscopic imaging where relatively large space may be available for the implementation of the gradient coils. Either the power consumption or the stored energy (thus, inductance), or the combination of the two can be minimized with a set of chosen target field constraints. Complete 3-D design equations for the optimization as well as inductance or resistance calculation are derived. An effective coil shape correction method for a curved current pattern is also developed. The design method can also be easily extended to the active shielding structure.