• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 1999.04b
• /
• pp.381-385
• /
• 1999

To investigate the influence of the design and operating parameters of the headbox on hydrodynamics, a pilot headbox system and pressure monitoring apparatus were constructed. The pilot headbox system consisted of a circulating water reservoir, centrifugal pump, distributor, step diffusor and slice. The distributor was designed to function as a pressure attenuator. Flow rate to the headbox and MD and CD velocity profiles in the slice zone were monitored using an ultrasonic flowmeter and Pitot tubes, respectively. As the distance from the step diffusor increased, evener CD velocity profile was observed. Wall effect increased with the increase of the velocity. Flow stability in the headbox was evaluated by injecting a dye at the outlet of the distributor. Application of theoretical analysis based on CFD in designing headboxes is briefly discussed.

• Journal of the Korea Computer Industry Society
• /
• v.5 no.2
• /
• pp.217-226
• /
• 2004

This paper proposes the electric stimulus tactile apparatus system(TESTAS) loaded on the haptic interface using ultrasonic motors (USMs) To touch the virtual object like wall in graphic, the 6 DOF haptic interface provides force feedback to users as if it is real. But the case of sharp virtual object like a puncture, it could not provided the sense of pain, but only the reaction-force. After the TESTAS had been loaded on this haptic interface, it could provide not only the force but also the pain to users. In this way, when users take the haptic and tactile informations at the same time, they easily have a correct understanding of virtual object.

• The Journal of the Acoustical Society of Korea
• /
• v.1 no.1
• /
• pp.65-69
• /
• 1982

It is studied on the apparatus for detecting the amplitude and the frequency of the vidrating object by utilizing the Ultrasonic Doppler Effect, without having any effect on the vibratioinal cases. The output detected varing the distance between the transducers and the vibrating object, when the angles of the incidence and the reflection wave are equalized. AM demodulatioin is adapted for the detection of vibration, and the output errors are theoretically consideed. The accurate detection of vibration can be obtained, when the distance between them is 5cm to 20cm, the magnitude of amplitude is 1mm to 5mm, and the vibrational frequency range is 20Hz to 1KHz.

• Journal of Energy Engineering
• /
• v.6 no.2
• /
• pp.212-219
• /
• 1997

The objective of this study is to investigate the effects light diesel-water emulsified fuel on performance and exhaust emissions of the compression ignition engine. The experimental results of light diesel-water emulsified fuel operation with new type ultrasonic emulsification apparatus as compared with light diesel operation are very positive; maximum 28% reduction of SFC (in the case of 30% of water content), maximum 60% reduction of smoke (in the case of 30% of water content), maximum 79% reduction of CO emission (in the case of 30% of water content). However, comparing light diesel-water emulsified fuel and light diesel in the same engine under the same operating conditions, power and torque were lower in the case of emulsified fuel. In view of the results for the above mentioned, the mixing of water into light diesel in the form of emulsification proved to be the best means for reduction of specific fuel consumption and exhaust emissions of C.I. engines.

• Journal of radiological science and technology
• /
• v.27 no.4
• /
• pp.31-35
• /
• 2004

A new measuring system for ultrasonic spectroscopy was constructed, utilizing PVDF [poly(vinylidene fluoride)] polymer films as wideband transducers. In a test of its performance, this measuring system was successfully applied to study of the nematic-isotropic phase transition in MBBA(p-methoxybenzylidene-p-n-butylan iline) liquid crystal. We could be confirmed that the phase transition in MBBA is $47^{\circ}C$, which is agree with the exciting optical method. The dependence of frequency on the phase transition was not observed, and but Maximum ultrasonic amplitude is measured for the resonance frequency 2MHz in PVDF transducers, These results shows that the spectroscopy with PVDF transducers takes advantage of studying the transient phenomena. When our apparatus is applied in medical purposes, It will be possible diagnostic for sickle-cell anemia and arterial sclerosis.

• Journal of the Korean Vacuum Society
• /
• v.12 no.3
• /
• pp.157-161
• /
• 2003

Nowadays there are increasing demands for more accurate measurement of atmospheric pressure according to the development of environmental industries. One of the most important pressure gauges for satisfying these demands is a quartz resonance barometer. In order to calibrate such an accurate barometer, laser/ultrasonic mercury manometers have been used. However, complexity and cost of mercury manometers made it out of use gradually. As a substitute, a gas-operated pressure balance is used for calibration of precise barometers. In such a case, commercially available pressure balances cannot be entirely suitable because consequent exposure of the piston, cylinder and masses to the atmosphere causes the problem of contamination. In this paper a device for changing the masses in situ without breaking the vacuum is described. This device made it possible to add or remove weights in the absolute mode, thereby greatly reducing the time between observations. At the same time, we investigated the characteristics of a commercial precise barometer using this new apparatus.

• Resources Recycling
• /
• v.20 no.6
• /
• pp.50-55
• /
• 2011

Using ultrasonic irradiation, the separation and recovery of PV cell, made of silicon wafer, from PV module was carried out through selective decomposition of EVA used as an interlaminated binder. The ultrasonic cleaner of bath-type (Output: 130 W, Frequency: 40 kHz) was used as an ultrasonic apparatus in this research. With the fixed distance of 2 cm, from ultrasonic generator to PV cell, the experiment of EVA decomposition was performed in various organic solvents such as Toluene, Trichloroethylene, O-dichlorobenzene, Benzene. And also their concentrations and temperature was changed to survey the optimum conditions. However EVA can be decomposed perfectly at $55^{\circ}C$ within 160 min in 5 M of all kinds of solvent, PV cell may be recovered with being damaged or broken severely. This damage may be resulted from the swelling of EVA in the process of decomposition. Whereas, at the condition of 5 M at $65^{\circ}C$, PV cell can be recovered with the state of minor damage or crack. This implies that the decomposition rate of EVA increases with an increase of temperature, thereby EVA can be decomposed before the swelling of EVA layer. Conclusively, it is possible for PV cell to be recovered within 40 min, at $65^{\circ}C$ in 5 M, with less damage.

• Journal of Periodontal and Implant Science
• /
• v.46 no.2
• /
• pp.107-115
• /
• 2016

Purpose: The aim of this study was to evaluate and compare tooth surface characteristics in extracted human molars after cervical enamel projections (CEPs) were removed with the use of three rotating instruments. Methods: We classified 60 extracted molars due to periodontal lesion with CEPs into grade I, II, or III, according to the Masters and Hoskins' criteria. Each group contained 20 specimens. Three rotating instruments were used to remove the CEPs: a piezoelectric ultrasonic scaler, a periodontal bur, and a diamond bur. Tooth surface characteristics before and after removal of the projections were then evaluated with scanning electron microscopy (SEM). We analyzed the characteristics of the tooth surfaces with respect to roughness and whether the enamel projections had been completely removed. Results: In SEM images, surfaces treated with the diamond bur were smoothest, but this instrument caused considerable harm to tooth structures near the CEPs. The piezoelectric ultrasonic scaler group produced the roughest surface but caused less harm to the tooth structure near the furcation. In general, the surfaces treated with the periodontal bur were smoother than those treated with the ultrasonic scaler, and the periodontal bur did not invade adjacent tooth structures. Conclusions: For removal of grade II CEPs, the most effective instrument was the diamond bur. However, in removing grade III projections, the diamond bur can destroy both adjacent tooth structures and the periodontal apparatus. In such cases, careful use of the periodontal bur may be an appropriate substitute.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.13 no.9
• /
• pp.694-702
• /
• 2003

A cooling mechanism using acoustic streaming by ultrasonic vibrations and associated convective heat transfer enhancement is investigated experimentally and analytically. Acoustic streaming pattern and associated heat transfer characteristics are presented. Analytical transient temperature profile of the heated plate following Nyborgs theory is accomplished along with experimental measurement. A temperature drop of 30 C is obtained in 4 minutes with vibration amplitude of 10${\mu}{\textrm}{m}$. As the vibration amplitude is further increased to 25${\mu}{\textrm}{m}$ a temperature drop of 40 C is achieved that is the maximum temperature drop obtained with the current experimental apparatus. Analytical heat transfer solutions verified a temperature drop of 4$0^{\circ}C$ with a vibration amplitude of 25${\mu}{\textrm}{m}$ at 28.4 kHz which is experimentally obtained.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1879-1881
• /
• 2003

In this paper, acoustic signals in $SF_6$ gas were analyzed using wavelet transform. For this, the PD sources in the $SF_6$ gas were divided into corona discharge surface discharge void discharge and crossing particle and acoustic signals were used to detect the PD sources. The measured signals were time-frequency distribution by wavelet transform and the features were extracted from the PD sources. As a result the characteristics of the PD sources were different. And this results is going to be used for basis diagnosis of $SF_6$ gas insulated apparatus.