• The korean journal of orthodontics
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• v.26 no.6
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• pp.647-655
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• 1996

In discussing the effects of adenoids on the development of the face and dentition, it is important to note their influence on the mode of breathing and to relate this to specific facial types and dentition. This study, therefore, assumed that the ability to adapt to individual's neuromuscular complex is various. And tried to investigate the effects of reduced nasal respiratory function on the development of dentition by facial type. This paper is based on children patients with enlarged adenoids and comparing them to data taken from a control group with normal respiratory function. Among the three facial types, the most statistical significant difference was observed from dolichofacial type between experimental and control group. In dolichofacial type, the experimental group showed labioversion of upper incisor, decrease in the width of upper arch, increase in overjet, increase in the rate of cross-bite, and increase in the height of palatal vault. No significant difference was observed between the two groups in the inclination of upper and lower incisors in mesofacial type, but the experimental group was observed to show decrease in the width of upper arch and increase in the height of palatal vault. On the other hand, in brachyfacial type, no significant difference was observed between the two groups in dentition variables except showing linguoversion of upper incisor. The results, which were observed in dolichofacial type, consist with Nordlund's theory of Compression.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.514-517
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• 1996

Zero current switching(ZCS) series resonant converter is used to control laser power density in a pulsed Nd:YAG laser power supply. The high power and high repetition rate paused Nd:YAG laser is designed and fabricated to control current pulse width and pulse repetition rate in the double elliptical laser oscillator. In order to find out operational characteristics of pulsed Nd:YAG laser, the electrical properties of driving power supply and laser output power are investigated and experimented by changing of the current pulse width from 200uS to 350uS(step 50uS) and pulse repetition rate range of 500pps(pulse per second) to 1150pps. From that result, we obtaind maximum efficiency of 1.83% and maximum laser output or 220W at the condition of 350 uS and 1150pps with one Nd:YAG rod), and obtained that of more than 400W with two laser head connecting series.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.4
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• pp.397-402
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• 2003

This paper concerns a pulse-width-modulation (PWM) controller design technique using digital redesign. Digital redesign is to convert a well-designed analog controller into an equivalent pulse-amplitude-modulation (PAM) controller maintaining the original analog control system in the sense of state-matching. In similar line of conversion concept, the redesigned PAM controller is converted into a PWM controller using the equivalent area principle. To convincingly visualize the proposed technique, an computer simulation example-attitude control of artificial satellite system is included.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.129-135
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• 2015

This paper shows significant methods that improve the lifespan of LED modules as well as efficiently using an aluminum heat-sink for LED module in high power. It proposes a method that raises stability and lifespan to protect LED modules and the power unit when the LED module has been used for a long hours at high temperatures. During the research, we applied a method of pulse-width modulation (PWM) in order to prevent the phenomenon that the entire power of a system is turned off and the lifespan is reduced when the LED nodule reacts to the high temperatures. To protect the LED module and SMPS based on high efficiency, a temperature sensor is attached underneath the circuit board and the sensor measures the temperature of circuit board when the LED module is powered on. The electrical power connected to SMPS is controlled by PWM when the temperature of the LED module reaches a particular temperature.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.12 no.2
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• pp.133-139
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• 2001

Background and Objectives : There are so many methods to investigate the causes of voice disorders. However, they were almost invasive or non-physiologic methods. And none of them showed the laryngeal movements. Phonation pharyngogram is non-invasive method to see the laryngeal movement directly. Authors studied to evaluate the availability of phonation pharyngogram in laryngeal nodule. Materials and Methods : 30 laryngeal nodules and 10 control groups were evaluated. Acoustic analysis and maximum phonation time were measured and pharyngogram was taken during sustaining /a/ phonation immediately after swallowing the barium. We measured the width of hypopharyngeal wall, shape of hypopharyngeal wall and pyriform sinus apex, level difference between both true vocal folds, angle of subglottis, location of true vocal folds, elevated distance of vocal folds and shape of c-spine. Results : Jitter, Shimmer of laryngeal nodule were higher than control group and maximum phonation time was shorter in laryngeal nodule. There was a significance in width of hypopharyngeal wall, shape of pyriform sinus apex, level difference between both true vocal folds, elevated distance of vocal folds and shape of c-spine. Conclusions : Authors knew that there were differences when we used the phonation pharyngogram between normal group and laryngeal nodule group.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1700-1704
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• 2004

In this paper a novel power converter for some notches generation in the point of common coupling is described. The magnitude, width, polarity, and position of the notches generated by the proposed scheme can be varied arbitrary with simple control. The scheme has good features of simple structure, high reliability, low cost, high efficiency, and the capability of arbitrary several notches generation. The converter can be used for the test of custom power devices such as UPS, DVR, active power filter, etc. The circuit operation is described and the usefulness of the scheme is verified through simulations.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.167-173
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• 1996

Laser distance meter and x-y robot employed in the extraction of three dimensional image recognition of muskmelon net and recognized the characteristics of that. All data measured transmitted to the PC/AT in the computer room and programmed with Visual Basic(Microsoft). Alteration of the concentration and application time of nutrient solution modified the net height and width of hydroponically grown muskmelon. Net height and width which are the characteristics of muskmelon depended on the concentration of nutrient solution used. Decreasing with the concentration of nutrient solution lowered the occupying ratio of net and also observed the tendency of widening of muskmelon net.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.2
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• pp.315-322
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• 2008

Titanium and its alloys have excellent corrosion resistance, high strength to weight ratios and creep properties in high temperature, which make them using many various fields of application. Especially, pure titanium, which has outstanding resistance for the stress corrosion cracking, crevice corrosion, pitting and microbiologically influenced corrosion, brings out to the best material for the heat exchanger, ballast tank, desalination facilities, and so on. Responding to these needs, welding processes for titanium are also being used GTAW, GMAW, PAW, EBW, LBW, resistance welding and diffusion bonding, etc. However, titanium is very active and highly susceptible to embrittlement by oxygen, nitrogen, hydrogen and carbon at high temperature, so it needs to shield the weld metal from the air and these gases during welding by non-active gas. In this study, it was possible to get sound beads without humping and spatter with a decrease of peak power according to increase of pulse width, change of welding speed and overlap rate for heat input control, and shield conditions at pulsed laser welding of titanium plates for Lap welding.

• Wind and Structures
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• v.26 no.5
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• pp.317-329
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• 2018

Wake characteristics of the flow over a finite square prism at different incidence angles were experimentally investigated using an open-loop wind tunnel. A finite square prism with a width D = 15 mm and a height H = 7D was vertically mounted on a horizontal flat plate. The Reynolds number was varied from $6.5{\times}10^3$ to $28.5{\times}10^3$ and the incidence angle ${\alpha}$ was changed from $0^{\circ}$ to $45^{\circ}$. The ratio of boundary layer thickness to the prism height was about ${\delta}/H=7%$. The time-averaged velocity, turbulence intensity and the vortex shedding frequency were obtained through a single-component hotwire probe. Power spectrum of the streamwise velocity fluctuations revealed that the tip and base vortices shed at the same frequency as that ofspanwise vortices. Furthermore, the results showed that the critical incidence angle corresponding to the maximum Strouhal number and minimum wake width occurs at ${\alpha}_{cr}=15^{\circ}$ which is equal to that reported for an infinite prism. There is a reduction in the size of the wake region along the height of the prism when moving away from the ground plane towards the free end.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.1
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• pp.5-9
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• 2004

In this paper, pulsed discharge is used to control the luminous color in gas discharge tubes. The luminous color of the positive column in gas discharge tubes filled with Hg-Ar-Ne (1: 9, 60［Torr］) and having no phosphor material, varies from red to blue emitted by the Ne and Hg from the pulsed discharge. With changing of pulse-width and frequency, the electron temperature in the transient period affects changes to the residual ion and metastable atom densities. The first metastable atoms containing energy levels of about 16.6 ［eV］have a very high probability that a collision will result in the ionization potential of Ar being 15.8 [eV]. The change of locus in the CIE chromaticity diagram with increasing pulse-width and frequency approves the variation of luminous color.