• International Journal of Precision Engineering and Manufacturing
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• v.2 no.4
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• pp.54-60
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• 2001

This paper deals with control design method having anticipation delay which is proposed for the discrete nonlinear engine where system dynamics is not accurate. Due to the induction-to-power delay in internal combustion(IC) engine having abrupt torque loss, underdamping and chattering in engine idle speed becomes a serious problem and it could make drivers uncomfortable. For this reason, Three types of the closed-loop controller are developed for the stable engine idle speed control. The inputs of the controllers are an engine idle speed and air conditioning signal. The output of the controllers is an duty cycle to operate the idle speed control valve(ISCV). The proposed controllers will be useful for improving actual vehicles since these shows good test

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.246-248
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• 2007

This paper presents fast locking PLL(Phase Locked Loop) that can improve a jitter noise characteristics and acquisition process by designing a PFD(Phase Frequency Detector) circuit. The conventional PFD has not only a jitter noise caused from such a demerit of the wide dead zone and duty cycle, but also a long delay interval that makes a high speed operation unable. The advanced PFD circuit using the TSPC(True Single Phase Clocking) circuit is proposed, and it has excellent performances such as 1.75us of locking time and independent duty cycle characteristic. It is fabricated in a 0.018-${\mu}m$ CMOS process, and 1.8v supply voltage, and 25MHz of input oscillator frequency, and 800MHz of output frequency and is simulated by using ADE of Cadence.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.470-475
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• 2002

Instantaneous following PWM control technique is pulsed nonlinear dynamic control method. This new control technique using analog integrator is proposed to control the duty ratio D of do-dc converter. In this control method, the duty ratio of a switch is exactly equal In or proportional to the control reference in the steady state or in a transient. Proposed control method compensates power source perturbation in one switching cycle, and the average value of the dynamic reference in one switching cycle. There is no steady state error nor dynamic error between the control reference and the average value of the switched variable. Experiments with buck converter have demonstrated the robustness of the control method and verified theoretical prediction. The control method is very general and applicable to all type PWM

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.378-381
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• 2002

Instantaneous following PWM control technique is pulsed nonlinear dynamic control method. This new control technique using analog integrator is proposed to control the duty ratio D of DC-DC converter. In this control method, the duty ratio of a switch is exactly equal to or proportional to the control reference in the steady state or in a transient. Proposed control method compensates power source perturbation in one switching cycle, and the average value of the dynamic reference in one switching cycle. There is no steady state error nor dynamic error between the control reference and the average value of the switched variable. Experiments with buck converter have demonstrated the robustness of the control method and verified theoretical prediction. The control method is very general and applicable to all type PWM.

• Journal of the Korean institute of surface engineering
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• v.47 no.4
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• pp.168-173
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• 2014

The paper presents the comparative results of TiAlN coatings deposited by DC and pulsed DC asymmetric bipolar magnetron sputtering systems. The results show that, with the decreasing duty cycle and increasing pulse frequency, the coating morphology changes from a columnar to a dense structure, with finer grains. Pulsed sputtered TiAlN coatings showed higher hardness, higher residual stress, and smaller grain sizes than dc prepared TiAlN coatings. Moreover residual stress of pulsed sputtered TiAlN coatings increased on increasing pulse frequency. Meanwhile, the surface roughness decreased continuously with increasing pulsed DC frequency up to 50 kHz.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.90.1-90.1
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• 2012

1934년 J. R. Winkler에 의해 처음으로 개발된 pulse current 도금은 연속적인 직류 단속을 이용한 전기도금으로써 종래의 연속적인 직류(direct current) 전기 도금이 가지는 다공성 및 거친 도금 등의 한계를 극복하기 위해 연구되고 있다. 최근 전기 전자 산업의 급속한 발달과 함께 Au, Pd, Rh 등의 귀금속 도금에 있어서 Pulse 도금은 광택, 다공도, 내부 응력, 불순물 및 수소 함유량의 감소와 같은 특성 향상을 가질 수 있으며 기존 DC 전기 도금의 문제점 해결책으로서 많은 연구가 이루어지고 있다. 하지만 현재까지 Pulse 도금의 정확한 기구(mechanism)에 대한 명확한 정립이 되어 있지 않아 모든 도금계에 적용할 수 있는 standard pattern이 없는 실정이다. 본 연구에서는 귀금속 도금 중 Ag pulse 도금에 있어서 Peak current density, duty cycle, time이 Ag 도금의 표면 형상, 두께, 열전도율에 미치는 영향에 대해 연구하였다.

• Journal of the Korean institute of surface engineering
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• v.48 no.4
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• pp.136-141
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• 2015

The paper presents the comparative results of NbN coatings deposited by DC and pulsed DC asymmetric bipolar magnetron sputtering systems. The results show that, with the decreasing duty cycle and increasing pulse frequency, the coating morphology changes from a columnar to a dense structure, with finer grains. The Pulsed sputtered NbN coatings showed higher hardness, higher residual stress, and smaller grain sizes than those of DC prepared NbN coatings. Moreover residual stress of pulsed sputtered NbN coatings increased on increasing pulse frequency. Meanwhile, the surface roughness decreased continuously with increasing pulsed DC frequency up to 50 kHz.

• Journal of the Korean institute of surface engineering
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• v.49 no.5
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• pp.461-466
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• 2016

Nanocrystalline vanadium nitride (VN) coatings were deposited using asymmetric bipolar pulsed dc sputtering to further understand the influence of the pulsed plasmas on the crystal structure, microstructure and mechanical properties. Properties of VN coatings were investigated with FE-SEM, XRD and nanoindentation. The results show that, with the increasing pulse frequency and decreasing duty cycle, the coating morphology changed from a porous columnar to a dense structure, with finer grains. Asymmetric bipolar pulsed dc sputtered VN coatings showed higher hardness, elastic modulus and residual compressive stress than dc sputtered VN coatings. The results suggest that asymmetric bipolar pulsed dc sputtering technique is very beneficial for the reactive sputtering deposition of VN coatings.

• Journal of the Optical Society of Korea
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• v.12 no.3
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• pp.205-209
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• 2008

We demonstrated a simple way of evaluating the duty cycle error in periodically polled lithium niobate(PPLN) based on the method of binary phase diffraction grating. To demonstrate this method, -Z face etched PPLN of desired periods were fabricated by the standard electric field poling technique. The etched PPLN was considered as a surface-relief binary phase grating. The diffraction patterns were recorded for different spatial locations along the length of the sample. The experimentally observed efficiencies of the diffracted orders were compared with the theoretically calculated values to estimate the duty cycle error.

• Journal of Biomedical Engineering Research
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• v.35 no.3
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• pp.62-67
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• 2014

The purpose of the study was to identify the effect of laser parameters on photocoagulation to maximize safety and efficacy during varicose vein treatment. CW and pulsed modes at 1470 nm were initially compared as a function of power on bovine liver tissue. In the pulsed mode, various parameters including repetition rate, duty cycle, and irradiation time were compared to evaluate tissue response during thermal treatment. The results demonstrated that CW and pulsed modes yielded almost similar coagulation development possibly due to shorter irradiation time of 5 sec. Regardless of laser mode, both repetition rate and duty cycle presented constant coagulation rate whereas longer irradiation time facilitated coagulation process.