• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.242-247
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• 2004

An Experimental study was conducted on spray combustion using dual swirlers at different outlet angle; co-swirl and counter-swirl. To understand the characteristics of turbulent spray combustion of dual swirl flow (DSF), the axial helical annular vaned swirlers with various swirl ratios and combination of angle and direction were designed. and temperature measurements of a rapidly thermocouple insertion and measurements of soot volume fraction and microrstructure using thermophoretic sampling particle diagnostic (TSPD) as TEM were carried out. The NOx, $CO_2$, $O_2$, etc. was analyzed using emission gas analyzer. The results show that flame stability were maintained under very lean condition. for both co-swirl and counter-swirl case. And though Counter-swirl case kept the higher temperature region compared to co-swirl case, Counter-swirl combustion represented less NOx emission and soot formation than co-swirl case.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.629-632
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• 2003

This paper has been studied analysis and design of microstrip Rotman lens operating over wide band and wide steering angle by the contour integral method along with the segmentation method. All mutual coupling, internal reflections between ports with exponential taper are taken into account. Equally spaced ports are designed and realized which gives less amplitude ripple at array ports. The measured results of 12 input and 12 output lens show $\pm$1.8 dB insertion loss deviation over 6~18GHz wide frequency range and beam steering accuracy less than 1$^{\circ}$ over $\pm$53$^{\circ}$ angle and agrees well with the analysis results.

• Journal of the Korean Society of Combustion
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• v.5 no.1
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• pp.67-79
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• 2000

An Experimental study was conducted on spray combustion using dual swirlers at different outlet angle; co-swirl and counter-swirl. To understand the characteristics of turbulent spray combustion of dual swril flow(DSF), the axial helical annular vaned swirlers with various swirl ratios and combination of angle and direction were designed. and temperature measurements of a rapidly thermocouple insertion and measurements of soot volume fraction and microstructure using thermophoretic sampling particle diagnostic(TSPD) as TEM were carried out. The NOx, $CO_2,\;O_2$, etc. was analyzed using emission gas analyzer. The results show that flame stability were maintained under very lean condition. for both co-swirl and counter-swirl case. And though Counter-swirl case kept the higher temperature region compared to co-swirl case, Counter-swirl combustion represented less NOx emission and soot formation than co-swirl case.

• Transactions of Materials Processing
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• v.11 no.7
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• pp.589-595
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• 2002

Up to now, Collimators have been generally produced by handwork and only a few companies have produced by semi-automatic system. Under this situation, automatic system for assembly of optical collimator has risen as a most essential technique in the development of optical communication components. In this study, it was constructed to develop optical collimators with high functionality and We manufactured optical collimators with a GRIN rod lens using automatic system. Therefore, we worked a performance test through a comparison of collimators made by automatic system and handwork with angle alignment, beam size. Also we compared common product with auto-manufactured sample. As a result, it brought a reduction of the tact time and an improvement of an efficiency and a productivity of optical collimators. therefore it was found that automatic system was indispensable for materialization of optical collimators with high functionality.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.11
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• pp.1161-1170
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• 2009

In this paper, dielectric, drude model and ideal metamaterial are applied to core of A-Sandwich radome and each radome is analyzed using recursive method in Ku band. The main parameters of radome performance are insertion loss, insertion phase delay and depolarization. In case of ideal metamaterial, the radome using ideal metamaterial dose not generate depolarization because insertion loss, insertion phase delay and loss for incidence angle of wave do not happened. If circular polarization wave is incident on radome with meta material, transmitted wave also keeps circular polarization. In case of the dispersive metamaterial, the performance of radome using dispersive metamaterial is better than it of radome using dielectric in a part of frequency band. From these results, it is showed that metamaterial can be applied to various radome structure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.500-506
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• 2002

This paper presents a design of wide angle steering microstrip Rotman lens operating over broadband frequency range for Electronic Warfare equipments. It has a compact and simple structure which it is easy to manufacture repetitively. The lens is modelled as a 2-dimension planar circuit, the contour integral method is performed over entire lens contour and the transmission coefficients from 8 beam ports to 8 array ports are found. The measured results are well agreed with those of analysis. Prediction of the multibeam array pattern fed by linear array antenna shows $\pm$65$^{\circ}$ of beam steering and $\pm$5 dB insertion loss deviation over 3:1 frequency range.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.2
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• pp.149-157
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• 2004

Implicit finite element analysis of the flat surface-straight edge hemming process is performed by using a commercial code ABAQUS/Standard. Methods of finite element modeling for springback simulation and contact pair definition are discussed. An optimal mesh system is chosen through the error analysis that is based on the smoothing of discontinuity in the state variables. This study has focused on the investigation of the influence of process parameters in flanging, pre-hemming and main hemming on final hem quality, which can be defined by turn-down, warp and roll-in. The parameters adopted in this parametric study are flange length, flange angle, flanging die corner radius, face angle and insertion angle of pre-hemming punch, and over-stroke of pre-hemming and main hemming punches.

• The Journal of the Korean dental association
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• v.55 no.8
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• pp.528-536
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• 2017

Treatment with removable partial denture is effective for partially edentulous patients who are unable to obtain sufficient retention and stability for functional and esthetic restoration. There are several cases reporting the improvement of retention and stability of the partial denture using a small number of implants. However, there are limited studies on the implant-assisted removable partial denture using a small number of remaining teeth and the bar locator system. The bar locator system has an advantage in that it could compensate the angle of insertion of removable prosthesis on implant with inconsistent placement angle due to anatomical constraints compared to when using the locator only. This case report describes the patient with $Parkinson^{\circ}$Øs disease who was treated with the Locator bar system using two previously placed implants and two remaining teeth on maxilla. No additional implants could be placed because of the medical and economic condition of the patients, and the angle of one of two implants could not be matched with the direction of the removable partial denture insertion. Considering the angle of the implants, the patient was treated with implant-assisted RPD using the Locator bar system and had satisfactory results in the aspect of esthetics, masticatory function, and oral hygiene maintenance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.3
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• pp.279-287
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• 2002

In this paper, a symmetric microwave lens to steer wide angle and to operate at broad band frequency range for a linear phased array transmitter was designed. To get accurate beam steering performance far a linear phased array transmitter, uniform amplitude transmission characteristics of microwave lens was focused. The measured result for the insertion loss deviation between Input and output ports of microstrip lens with 8 beam ports and 8 array ports was $\pm$3.1 ㏈ over 6~18 ㎓ band, which was very uniform characteristics. Using 8 elements linear array antenna, it was confirmed the radiation beam could be steered over $\pm$60$^{\circ}$ in azimuth. And the measured lens performance data and multi-beam steering pattern were presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.878-883
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• 2003

New feeding structures using linearly and exponentially tapered lines to planar microstrip resonators are proposed. These can overcome the design problems from coupling losses and impedance mismatching by increasing the coupling efficiency. The variation of its feeding angle is evaluated for the insertion loss and bandwidth and the feedline length is optimized at ${\lambda}_g$/2. The ring resonators and patches fed by the tapered line have been designed and implemented. The experimental results show that the insertion loss is enhanced by about 7 dB. Both rings and antennas are better matched, without disturbing the single-mode resonance or distorting their radiation pattern