• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.380-383
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• 1998

Amplitude Modulation PWM Technique which has characteristics such as the switching loss and Harmonic distortion reduction is compared in this paper. And also Harmonic components only carrier frequencies. And as it is showed Harmonic components only carrier frequencies via simulation results. Am-pwm is applied to the inverter system of High-speed induction motor.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.991-994
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• 2009

This paper reports of camera detection of Mura. The type, location, size, orientation and amplitude are found. As the luminance variation in Mura is down to less than app. 0.3 %, measurement apparatus, techniques and algorithms are developed to measure low noise data and to extract the Mura from data with the residual noise in the same magnitude as the Mura.

• Journal of Oral Medicine and Pain
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• 제21권1호
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• pp.67-78
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• 1996

This study was performed to compare the TMJ sounds by means of vibration-related items by Sonopak such as integral, high integral, above 300/(0-300) ratio, peak amplitude, peak frequency and median frequency before and after occlusa1 splint therapy as well as counselling, physical modalities. For this study 22 patients with craniomandibular disorders (CMDs) were selected and examined by routine diagnostic procedure for CMDs including Transcranial and Panoramic radiographs and were classified into 3 CMDs subgroups : disc displacement with reduction, disc displacement without reduction, and degenerative joint disease. Visual analogue scale (VAS) about joint sound was recorded during treatment period and VAS treatment index (VAS Ti) was calculated from the VAS data and treatment duration. The author evaluated and compared treatment results by several parmeters such as symptom duration, timing of joint sound, parafunctional habits, trauma, and diagnostic classification. The obtained results were as follows : 1. Before the treatment, the highest value of peak amplitude was observed in disc displacement with reduction group and value of median frequency was highest in degenerative joint disease group. In addition the highest values of peak frequency and ratio ware observed in degenerative joint disease group, though they were not significant. Furthermore the lowest value of high integral was observed in disc displacement without reduction group and though it was not significant, value of integral was lowest in that group. 2. Among 3CMDs subgroups disc displacement with reduction group showed the significantly decreased value of high integral and degenerative joint disease group had the significantly decreased value of integral after conservative treatment including occlusal splint therapy. Conclusively conservative treatment including occlusal splint therapy vay be effective in the treatment of CMDs including TMJ sound. 3. Fair prognosis for conservative treatment was observed in acute group under 6 months than chronic group, 6 months over in symptom duration but there was no statistical difference. The result for conservative treatment was observed slightly poor in subjects with bruxism, clenching, unilateral chewing habit and trauma history but there were no statistical differences.

• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.1104-1110
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• 2003

The present study investigates the hemorheological characteristics of blood flow with applying vibration to a non-aggregating red blood cell suspension. In order to obtain the non-aggregating RBC suspension, blood samples were treated with vibration at a specified condition, which viscosities were taken before and after the treatment, respectively. The viscosity of the blood samples after treatment was higher than before treatment. These treated blood samples were forced to flow through a capillary tube that was vibrated perpendicularly to the direction of the flow. The experimental results showed that vibration caused a reduction of the flow resistance of the non-aggregated blood. The reduction of the flow resistance was strongly dependent on both frequency and amplitude of vibration. These results show potential in treating various diseases in the microcirculation associated with blood cell aggregation.

• 소성∙가공
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• 제25권6호
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• pp.373-378
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• 2016

Recent researches have reported that the superposition of ultrasonic vibrations in metal forming provides beneficial effects such as the reduction of forming load, flow stress and interfacial friction which improves the surface quality of end products. This paper presents experimental investigations on the effects of ultrasonic vibrations in upsetting tests of aluminum. The ultrasonic exciting system consists of piezoelectric transducer and resonator was designed and constructed to superimpose high frequency oscillation on the forming tools. Ultrasonic vibration-assisted upsetting tests were performed for three vibration modes five amplitudes, and the results were compared with those of conventional upsetting tests. The results showed that the superimposition of ultrasonic vibration reduces the upsetting load, and the load reduction is only dependent on the amplitude of the applied vibration regardless of deformation histories and vibration modes.

• Journal of Electrochemical Science and Technology
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• 제15권2호
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• pp.261-267
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• 2024

An unconventional fabrication technique of nanoelectrode was developed using atomic force microscopy (AFM) and hydrogel. Until now, the precise control of electroactive area down to a few nm² has always been an obstacle, which limits the wide application of nanoelectrodes. Here, the nanometer-sized contact between the boron-doped diamond (BDD) as conductive AFM tip and the agarose hydrogel as solid electrolyte was well governed by the feedback amplitude of oscillation in the non-contact mode of AFM. Consequently, this low-cost and feasible approach gives rise to new possibilities for the fabrication of nanoelectrodes. The electroactive area controlled by the set point of AFM was investigated by cyclic voltammetry (CV) of the ferrocenmethanol (FcMeOH) combined with quasi-solid agarose hydrogel as an electrolyte. Single copper (Cu) nanoparticle was deposited at the apex of the AFM tip using this platform whose electrocatalytic activity for nitrate reduction was then investigated by CV and Field Emission-Scanning Electron Microscopy (FE-SEM), respectively.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1116-1122
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• 2008

The reciprocating type hydrogen compressor has a pulsation due to the reciprocative characteristics which results in noise and vibration. Snubber is installed for the relaxation of pulsation, but it causes reduction of compressor efficiency because of pressure loss. Five types of snubber were modeled for the numerical investigation of the effect of the relative position of inlet and outlet and buffer angle on the pulsation amplitude and pressure loss. MSC/NASTRAN is used as a numerical tool to identify the vibration characteristic of each type. Frequency responses in forced vibration mode are compared for various cases and buffer angles.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.415-419
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• 2003

This paper focuses on a simple technique to reduced torque ripple in the direct torque control inverter for PMSM drive. It is actually impossible to raise the inverter switching frequency in the conventional system, although the hysterisis bandwidths for the stator flux and torque control are sufficiently diminished, because of the sampling Interval and the delay in estimating the flux and the torque In order to overcome the problem, the proposed method introduces a dithering technique into the conventional system by superposing triangular waves with high frequency and minute amplitude on the torque error. And the programable 3- stage lowpass filter is added instead of pure Integrator. Simulation results prove the feasibility of proposed strategy compared with conventional method.

• 한국정밀공학회지
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• 제33권9호
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• pp.731-737
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• 2016

In the quest for improved capacity and accelerated dehydration speed of drum type washing machines, an increase in vibration emerges as a major challenge. In an attempt to derive a new design with reduced vibration, a full finite element model of washing machine has been developed, with experimental verification. After modal analyses of several design variants, a new design of the cabinet has been proposed. Forced vibration analysis of the new model suggests that 19% reduction in cabinet vibration amplitude can be achieved with this design.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권8호
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• pp.2783-2795
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• 2014

Orthogonal frequency division multiplexing with offset quadrature amplitude modulation (OFDM-OQAM) technique has drawn significant interests in recent years. However, most of the existing OFDM peak-to-average ratio (PAPR) reduction schemes cannot be used in the OFDM-OQAM system directly. In this paper, a modified scheme called overlapped segmental clipping (OS-clipping) is proposed to deal with the high PAPR problem specifically in the OFDM-OQAM system. For the proposed OS-clipping scheme, the input signals are divided into a number of overlapped segments and then the clipping operation is processed on each segment. Simulation results show that the modified scheme used in the OFDM-OQAM system can provide better performance than conventional clipping scheme directly used in the OFDM-OQAM system, and even outperforms conventional clipping scheme applied in the OFDM system.