• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.45-46
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• 2006

In this paper, a dual stage servo mechanism has been developed for image tracking system to improve transient control performances such as small rise time, small overshoot, small settling time, etc. A secondary stage, a platform, actuated by a pair of electro-magnets is mounted on a conventional elevation gimbal. In this mechanism, the gimbal provides large range but slow motion and the platform provides small range but fast positioning. A sliding mode control is applied to the platform positioning to attain robust performances and stability in the presence of the disturbance related to dynamic coupling of the gimbal and the platform. Results from experiments illustrate that the suggested dual stage mechanism controlled by the sliding mode control is effective in improving transient responses and attenuating the disturbance related with dynamic coupling.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제32권3호
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• pp.85-92
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• 2021

Attention-deficit/hyperactivity disorder (ADHD) leads to functional decline in academic performance, interpersonal relationships, and development in school-aged children. Early diagnosis and appropriate intervention can significantly reduce the functional decline caused by ADHD. Currently, there is no established biological marker for ADHD. Some studies have suggested that various indicators from the quantitative electroencephalogram (QEEG) may be useful biological markers for the diagnosis of ADHD. Until the 2010s, theta/beta ratio (TBR) was a biomarker candidate for ADHD that consistently showed high diagnostic value. However, limitations of TBR have recently been reported. Studies have demonstrated that phase-amplitude coupling, especially theta phase-gamma amplitude coupling, are related to cognitive dysfunction and may assist in the diagnosis of ADHD. As yet, the underlying mechanism is not clearly established, and the clinical efficacy of these biomarkers needs to be proven through well-controlled studies. Based on the heterogeneous characteristics of ADHD, subgrouping through QEEG plays a key role in diagnosis and treatment planning. Sophisticated, well-designed studies and meta-analyses are necessary to confirm these findings.

• ETRI Journal
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• 제30권6호
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• pp.877-879
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• 2008

A novel differential dual-frequency antenna using proximity coupling is proposed. Dual bands are realized by a slot in the ground plane. The lower resonant frequency is controlled by the slot in the ground plane, and the upper resonant frequency is mainly determined by the dimensions of the radiating patch. Measured results show that the proposed antenna can operate at 2.51 GHz and 5.38 GHz.

• 한국산업융합학회 논문집
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• 제20권5호
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• pp.419-424
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• 2017

The purpose of this study is to develop a virtual testbed capable of predicting the functional performance of a linear electromagnetic actuator for a high voltage relay in order to reduce its development costs and time. The virtual testbed is defined by a multiphysics coupling approach in order to consider the complex interactions of multi-domains such as the solenoid model of electromagnets, the mass-spring-damper model of mechanical systems, the electric circuit model for an external control unit, and the thermal model for predicting temperature variations. The performances of the existing high voltage relay were estimated by the virtual testbed, and then the effectiveness and validation of the proposed testbed were discussed in comparison with the experimental test results. This study showed that the virtual testbed can be applied in design, optimization, and investigation of high voltage relays.

• 전기학회논문지
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• 제57권11호
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• pp.2127-2130
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• 2008

In this paper, a tunable bandpass filter with mutual inductive coupling circuits is newly designed and demonstrated for UHF TV tuner ranged from Ch.14(473MHz) to Ch.69(803MHz) applications. Conventional HF tuning circuit with an electromagnetic bandpass filter has several problems such as large size, high volume and high cost, since the electromagnetic filter is comprised of several passive components and air core inductors to be assembled and controlled manually. To address these obstacles, peaking chip inductor was newly applied for constructing the mutual inductive coupling circuit. The proposed circuit was newly and optimally designed, since the chip inductor showed lower components Q-value than the air core inductor. A varactor diode has been also used to fabricate the proposed tunable bandpass filter for RF tuning circuit. The fabricated tunable filter exhibited low insertion loss of approximately -3dB, high return loss of below -10dB, and large tuning bandwidth of 330MHz.

• ETRI Journal
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• 제32권1호
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• pp.148-150
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• 2010

This letter presents the design of a compact bandstop filter (BSF) operating at two frequencies. The proposed BSF consists of open-ended stepped impedance resonators (OSIR) and an end-shorted parallel-coupled microstrip line (E-PCML). The OSIRs are used to achieve the impedance-controlled stopband positions. The wide BSF bandwidths are achieved through enhanced coupling of the E-PCML. Explicit design guidelines are derived using a lossless transmission line model. To validate theoretical predictions, a prototype dual-band BSF operating at 900 MHz and 2,100 MHz with fractional bandwidths of 72% and 36%, respectively, is implemented in microstrip.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권2호
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• pp.125-131
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• 2001

When the program voltage is applied to a word line, a part of the boosted channel charge in inhibited bit lines is lost due to the coupling between the string select line (SSL) and the adjacent word line. This phenomenon causes the program disturbance in the cells connected to the inhibited bit lines. This program disturbance becomes more serious, as the word line pitch is decreased. To reduce the word line coupling, the rising edge of the word-line voltage waveform was changed from a pulse step into a ramp waveform with a controlled slope. The word-line ramping circuit was composed of a timer, a decoder, a 8 b D/A converter, a comparator, and a high voltage switch pump (HVSP). The ramping voltage was generated by using a stepping waveform. The rising time and the stepping number of the word-line voltage for programming were set to $\mutextrm{m}-$ and 8, respectively,. The ramping circuit was used in a 512Mb NAND flash memory fabricated with a $0.15-\mutextrm{m}$ CMOS technology, reducing the SSL coupling voltage from 1.4V into a value below 0.4V.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.194-199
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• 1992

In this paper, each section of an Electrolytic Tinning Line is mathematically modelled with the coupling effect accounted for. Based on the modelling, PI and feedforward controllers are designed for speed control or tension control of each section of the process line. It is shown through simulatios that the tension of the stip is controlled precisely along the entire line and the contituety of the process is insured when using the efficient control of loop towers.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.151-154
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• 2001

Shape memory alloy (SMA) has demonstrated its potentials for various smart structure applications. SMA wires undergo a reversible phase transformation from martensite to austenite as temperature increases. This transformation leads to shape recovery and associated recovery strains. If SMA actuators are embedded off the neutral surface and are oriented in arbitrary angles with respect to a beam axis, then the beam bends and twists due to the coupling effects of recovery strains activated. In this study, the bending and twisting of a SMA/Composite beam were controlled by both electric resistive heating and passive elastic tailoring. 3-dimensional finite element formulations were derived and validated to analyze the responses of the SMA/Composite beam. Numerical results show that the shape of the SMA/Composite beam can be controlled by judicious choices of control temperatures, SMA angles, and elastic tailoring.

• 한국정보통신학회논문지
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• 제5권6호
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• pp.1175-1183
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• 2001

본 연구에서는 간단한 전자회로로 카오스 특성을 나타내는 Chua 회로 대신 더욱 유연성이 있는 SC-CNN(State-Controlled CNN)을 이용해서 2-double scroll 과 3-double scroll 회로를 구성하고 이를 이용 하여 하이퍼카오스 회로를 제작하였다. 제작된 하이퍼카오스 회로로 두 개 이상의 카오스 어트렉터가 약한 결합을 하는 과정에서 발생하는 위상차를 이용하여 동기화를 이루고, 동기화된 하이피카오스 신호에 정보신호를 합성하여 전송한 후 수신부에서 이를 복조하는 하이퍼카오스 비밀통신을 수행하였다.