• Transactions of Materials Processing
• /
• v.28 no.6
• /
• pp.335-346
• /
• 2019

Thick plate forming is presented to manufacture a large and curved member of steam turbine diaphragm. Due to three-dimensional asymmetry of target geometry, it is hard to consistently keep the blank position in die cavity between forming punch and die. In order to relieve the position instability of the blank during the thick plate forming, a blank support structure is proposed to be composed of guide pins and linear bearing, and blank guide arm enlarged from both longitudinal ends of the thick blank. In this study, parametric investigations with regard to the geometric position and width of the blank guide arm are carried out. As main geometric parameters, 2 positions such as maximum curvature region and minimum one on a curved cross-section profile of the target shape are selected, and 14 widths of the blank guide arm are considered. Using 28 variable combinations, three-dimensional numerical simulations are performed to predict the appropriate range of the process parameters. The compatibility and validity of the blank support structure with the blank guide arm for the thick plate forming is verified through the thick plate forming experiments.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.11
• /
• pp.2260-2266
• /
• 2009

In this paper, the problem of electromagnetic coupling between a slit fed by a flanged parallel-plate waveguide (FPPW) and a nearby conducting strip parallel to the slit is studied as a simplified problem for a near-field scanning microscopy (NSM). The characteristics of the FPPW are investigated from the results for the variations of the equivalent slit admittance, the reactive powers near the slit inside and outside the FPPW, the magnitude and phase of the voltage reflection coefficient of the TEM wave. The performance of the proposed apparatus as an NSM is tested by examining the effects of various geometrical parameters such as guide height, slit width, strip width, distance between slit and strip, and the ratio of slit width to guide height on the magnitude and phase of the voltage reflection coefficient of the TEM wave. From the results for the voltage reflection coefficient against the strip offset from the slit, it is found that a slit in the FPPW with smaller guide height gives higher scanning resolution and the phase variation is more sensitive than the magnitude variation.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.10
• /
• pp.581-586
• /
• 2002

To improve the current waveform of diode rectifiers, we propose a new operating principle for the voltage-doubler diode rectifiers. In the conventional voltage-doubler rectifier circuit, relatively large capacitors are used to boost the output voltage, while the proposed circuit uses smaller ones and a small reactor not to boost the output voltage but improve the input current waveform. A circuit design method is shown by experimentation and confirmed simulation. The experimental results of the proposed diode rectifier satisfies the harmonic guide lines. A high input power factor of 97(%) and an efficiency of 98[%] are also obtained. The new rectifier with no controlled switches meet the harmonic guide lines, resulting in a simple, reliable and low-cost at-to dc converters in comparison with the boost-type current-improving circuits. This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage. And this paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit is constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduction and the power factor improvement. Half pulse-width modulated (HPWM) inverter was explained compared with conventional pulse width modulated(PWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.1037-1038
• /
• 2006

This paper treats the guide path tracking problem of an experimental automated guided vehicle. An experimental guide path is made of aluminium foil which has width of 2[cm]. A digital Proportional and Derivative controller is used to manipulate the steering system and it is verified by laboratory experiments that the designed AGV tracks the guide path withen the range of 3.2[cm] deviation.

• Journal of the Korean Society of Safety
• /
• v.23 no.2
• /
• pp.1-6
• /
• 2008

The present study investigates on improvement of inhalation efficiency of hood in ventilation system for elimination of industrial dust. The hood, one of local exhaust ventilation system, has an important function to inhale a pollution source such as harmful dust and industrial waste. In this study, in order to improve the inhalation efficiency of the industrial hood, a new device named "gas-guide-device" was attached to inside of hood. The thermal fluid commercial code "Phoenics ver 3.1" was used to analyze the flow velocity distribution at the hood inlet and around the hood after gas-guide-device was installed. And the flow velocity on each position inside and around the hood was actually measured using the hot wire type anemometer under the same condition as that of numerical analysis. Also, in order to identify the optimum shape of gas-guide-device, numerical analysis and experiments are performed under various conditions and their results are presented. The results of this study revealed that the hood attached with gas-guide-device was higher the inhalation efficiency than that for without one and can be possible to improve the capture velocity of the industrial dust. And the optimum shape of gas-guide-device was identified that the ratio of two sizes of gas-guide-device, X to Y, has 4 to 6 on the basis of the hood size in use and the width (b) of gas-guide-device.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.147-150
• /
• 2002

A light guide panel is an element of the LCD backlight module that is often used for the display of compact electronic devices. In this study, a laser marking system is proposed to fabricate light guide panel, which can be replaced of other manufacturing methods such as silk printing, stamping, and v-cutting methods. The objectives of this research are the establishment of laser marking system, evaluation of laser marking parameters, understanding marking process, application to PMMA, reliability test and quality inspection. A 50W $CO_2$ laser (CW) was used to perform different experiments in which, the influence of some processing parameters (average power, scanning speed) on the geometry and quality of groove pattern was studied. The width of the etched grooves increases with increasing a laser power and decreasing a scan speed. In order to analyze surface characteristics and optical properties (luminance, uniformity), SEM photography and BM7 (luminance measuring system) were used. As a result, the optimal conditions of the process parameters were determined.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.3
• /
• pp.47-52
• /
• 2011

Directional couplers based on plasmonic waveguides with nano-scale three channels are designed by utilizing mode coupling effect as well as rib-guiding structure. Longitudinal modal transmission-line theory(L-MTLT) is used for simulating the light propagation and optimizing the design parameters. The designed plasmonic coupler operating as power splitter has nano-scale size of about 200~250 nm width. In order to achieve the desired power splitting ratio, the refractive index of guiding modes is evaluated along the width variation of center channel. Finally, a power splitter based on triple rib directional coupler, which ensures maximum power transfer from one outermost guide to the other outermost guide, is designed.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.11 no.4
• /
• pp.377-383
• /
• 2017

In this study, it is proposed and developed a shot accuracy trainer for wheelchair curling. This trainer is developed to improve curling shot accuracy by supplying functions of changing guide width in which curling stone passes by and of time mesurement of Hack to Hog. And it also can supply training video of athlete to coach to analyze. From the pilot test from coaching staff of wheelchair curling team, association executives and icemaker of rink, we tried to verify the usability of proposed system.

• International Journal of Highway Engineering
• /
• v.16 no.2
• /
• pp.99-106
• /
• 2014

PURPOSES : This study is to develop Right-Turning Channelization Design Models of Semitrailer at Intersections by regression of vehicle tracking simulation. METHODS : Based on the literature review, it was indicated that right-turning channelization design guide of semitrailer is too complex and is not reflected turning speed and approach angle. To verify effectiveness of right turning semitrailer trajectories according to the changing turning speed and approach angle, vehicle tracking simulation was executed. And then, simulation results were analyzed for modeling design elements; minimum turning radius, swept path width, arc length, width of triangle island, of right-turning channelization using regression methods. RESULTS : When the turning speed is getting higher, minimum turning radius, arc length, width of triangle island increased and the approach angle lower, swept path width, arc length, width of triangle island reduced. The turning radius completely reflected by turning speed. CONCLUSIONS : In this research, it was investigated how much design elements are changed according to the turning speed and the approach angle of semitrailer. The developed right-turning channelization design models can help engineers to easy and comfortable design at various conditions.

• Archives of Plastic Surgery
• /
• v.38 no.2
• /
• pp.173-181
• /
• 2011

Purpose: Masseter muscle is an important muscle of mastication. Because it has a great influence on the shape of low facial contour, patients who have masseteric hypertrophy show square-shaped jaw appearance. As aesthetic procedures for the reduction of the masseter muscle volume, radiofrequency ablation or botulinum toxin injection is at the center of attention. Authors studied the anatomical measurement of the thickness and width of masseter muscle and the surface mapping of the maximal thickness point using computed tomography (CT) scan to identify the useful guide for the injection of botulinum toxin in masseteric hypertrophy patients. Methods: We analyzed 2 mm-thickness OMU (ostiomeatal unit) CT of 112 normal people (224 masseter muscles) taken from June 2009 to May 2010. First, we measured the thickness, width and depth of the masseter muscle from the skin surface and analysed each by side, sex and age, respectively. The distribution of the thickness of the muscle and the correlation of thickness and width of the muscle were studied also. Second, we underwent surface mapping of the maximal thickness point using CT analysis by means of checking the vertical and horizontal distance from the angle of the mandible. Results: The average thickness and width of the masseter muscle was 17.73 mm and 40.78 mm in the male patients and were 14.33 mm and 37.42 mm in the female patients. Statistically, both figures of the male patients were larger than those of the female patients. However, the depth of the muscle from the skin surface in female patients (7.37 mm) was larger than that of the male patients (6.15 mm). There were no statistical difference in side or age. The width and thickness of the masseter muscle were in the positive correlation. The location of maximal thickness point of the masseter muscle was 27.77 mm vertically and 27.68 mm horizontally in the male patients, and 25.19 mm vertically and 25.42 mm horizontally in the female patients from the angle of mandible. Conclusion: We were able to present statistical evidence of the diagnosis and treatment of the masseteric hypertrophy regarding the anatomical measurements such as the thickness and width. And the maximal thickness point of the masseter muscle may be a useful guide for the clinical procedures of botulinum toxin injection.