• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.397-402
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• 1996

A compact excimer laser was developed with coaxial type which the one line cross flow fan is only used. At 1 kHz repetitive operation, average power of KrF laser is 56 watt. In this paper, Design parameter and CR characteristic are investigated for attainment of the compact 1 kHz excimer laser. We have obtained overall efficiency of 1.2% with KrF laser gas. At this time, CR and the variation of laser output are 2.97, $\pm$9%. Laser gas volume and active volume are 10 liter, 1.8(H)$\times$1.2(W)$\times$30(L)=64.8 ㎤, respectively.

• Korean Journal of Computational Design and Engineering
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• v.17 no.5
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• pp.312-323
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• 2012

Planetary gearing is a gear system consisting of one or more planet gears, revolving about a sun gear. While the planetary gear system has many advantages- for example, high power density, large reduction in a small volume, multiple kinematic combinations, pure torsional reactions, and coaxial shafting, it has not been widely used because of its high bearing loads, inaccessibility, and design complexity. It is also necessary to shift several pairs of gear profiles at a same time. Therefore, designing profile shifted planetary gear system is a difficult and know-how dependent job. This study provides a practical solution to design a profile shifted gear system by the procedural design scheme, and proposes a bearing integrated structure of the dual stage profile shifted gear system with a robust output end. A dual stage profile shifted gear system with the bearing integrated structure is manufactured by the proposed design scheme in this study. This gear system is verified that it is good enough to commercialize, because it has high performance with high gear ratio and robust output end against axial and radial directional runouts in a small space.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.130-133
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• 2009

The sequence of the propellant supply is very important for the reliable and safe operation of a LRE combustion test. So combustion performance tests were performed to find an optimum test sequence by changing supply time of propellants and purge gas in the moment of ignition and extinction. The liquid rocket engine consisted of a catalytic ignitor and six swirl-coaxial injectors which used hydrogen peroxide and kerosene. Conclusively, an optimum sequence was found for stable combustion in the moment of ignition and extinction.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.134-137
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• 2009

Combustion tests of a low thrust rocket engine was performed to get combustion characteristics, which used a high concentrated hydrogen peroxide and kerosene as the oxidizer and fuel. The engine consisted of multi injector(six coaxial swirl injectors), chamber, nozzle and catalyst ignition system. The test was carried out by changing O/F ratio from 3.8 to 11.0. The experimental results showed that combustion efficiency was highest at O/F ratio from 5 to 6 and pressure fluctuations of all the range were lower than 5%.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1271-1276
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• 2020

The geometrical efficiency of a source-to-detector configuration is considered to be necessary in the calculation of the full energy peak efficiency, especially for NaI(Tl) and HPGe gamma-ray spectroscopy detectors. The geometrical efficiency depends on the solid angle subtended by the radioactive sources and the detector surfaces. The present work is basically concerned to establish a new mathematical approach for calculating the solid angle and geometrical efficiency, based on conversion of the geometrical solid angle of a non-axial radioactive point source with respect to a circular surface of the detector to a new equivalent geometry. The equivalent geometry consists of an axial radioactive point source with respect to an arbitrary elliptical surface that lies between the radioactive point source and the circular surface of the detector. This expression was extended to include coaxial radioactive circular disk source. The results were compared with a number of published data to explain how significant this work is in the efficiency calibration procedure for the γ-ray detection systems, especially in case of using isotropic radiating γ-ray sources in the form of point and disk shapes.

• Journal of the Korean Ceramic Society
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• v.44 no.8
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• pp.430-436
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• 2007

Rheological properties of cement paste containing ultrafine blastfurnace slag (UBS, $9600cm^2/g$) were investigated by mini-slump test, pH meter, conduction calorimeter and coaxial cylinder viscometer. In order to improve rheological properties of the cement paste, granulated blastfurnace slag (GBS, $3500cm^2/g$) and polycarboxylate type superplasticizer (PC) were also used in this experiment. The fluidity of cement paste containing UBS was decreased. The yield stress and plastic viscosity of cement paste was increased with increasing UBS. But the rheological properties were improved when GBS and PC were added to UBS blended cement paste. In the relationship between the yield stress and the plastic viscosity or the mini-slump value, the yield stress of the cement paste was proportional to the plastic viscosity of it. However the cement paste mini-slump value was in inverse proportional to the yield stress.

• 연구논문집
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• s.29
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• pp.111-121
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• 1999

Weft insertion and Beating mechanism which weaves fabric with completion the pattern of warp yarn and weft yarn in the high speed rapier loom is driven by cam operating method. This mechanism has 4 cams on the coaxial line for driving. These cams form a pair by two. and perform a conjugate motion with each other. By this reason, it is necessary for two pairs to realize the synchronized motion through exact and optimal design. From this viewpoint, to analysis the whole cams' movement and to realize the high speed of rapier loom, I tried to develop the computer aided simulation program. In this study, I would like to introduce the simulation program about above-mentioned 4 kinds of cam mechanism which can display the profiles of 2 pairs of cam mechanism not to speak of mutual relationships of their movement on the monitor.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1183-1187
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• 2005

In this paper, a weathercock-shaped microstrip patch antenna for application in 5.25GHz band wireless LAN is designed and fabricated. To obtain sufficient bandwidth in VSWR<2, the T-slot is inserted on the patch, the coaxial probe source is used. The measured result of fabricated antenna obtained 350MHz or about $7.62\%$ bandwidth in VSWR<2 referenced to the center frequency, the gain of 5.25${\~}$6.70dBi. The experimental 3-dB beam width is shown to be broad across the pass band in azimuth and elevation at $80.32^{\circ}$ and $83.88^{\circ}$, in several.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1484-1486
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• 1998

Recently, extending the local broadcasting and increasing lots of informations, the low-loss communication cable is required in proportion as frequency. The reason of transportation loss causes to using the high frequencies like hundreds of MHz or decades of GHz. For the low transportation loss, it is required the developing-technology of foaming and the high foamed insulator with the dielectric ratio of the nearest to 1. Therefore, there is the purpose of developing the insulating materials for the low dielectric ratio. Also it is important to measure the attenuation, which is one of the important parameters, as the evaluation of transportation characteristic with frequency in the communication cable. In this paper, the result showed that the dielectric ratio(1.4) of the nearest to 1 and low attenuation with high frequency were very related to the transportation and reflection characteristics such as propagation velocity(82.27%), delay time and voltage standing wave ratio(VSWR).

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2149-2151
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• 2004

The time-frequency domain reflectometry(TFDR) is well known to detect and locate a fault in a coaxial cable[3]. Traditional reflectometry methods have been achieved in either the time domain or frequency domain only. However, the time-frequency domain reflectometry utilizes time and frequency information of a reflected signal passed through a cable to detect and locate the fault. The purpose of this paper is to find appropriate time-frequency distribution function suitable for a TFDR system. Choosing the appropriate time-frequency distribution function implies one can detect the fault and estimate the location accurately. We consider and compare adequate time-frequency distribution function on the basis of experimental results.