• Journal of The Korean Astronomical Society
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• v.36 no.3
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• pp.213-222
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• 2003

We review recent observational results on early type galaxies obtained with high spatial resolution Chandra data. With its unprecedented high spatial resolution, Chandra reveals many intriguing features in early type galaxies which were not identified with the previous X-ray missions. In particular, various fine structures of the hot ISM in early type galaxies are detected, for example, X-ray cavities which are spatially coincident with radio jets/lobes, indicating the interaction between the hot ISM and radio jets. Also point sources (mostly LMXBs) are individually resolved down to Lx = a few x $10^{37}\;erg\;sec^{-1}$ and it is for the first time possible to unequivocally investigate their properties and the X-ray luminosity function. After correcting for incompleteness, the XLF of LMXBs is well reproduced by a single power law with a slope of -1.0 - -1.5, which is in contrast to the previous report on the existence of the XLF break at Lx, Eddington = 2 x $10^{38}\;erg\;sec^{-1}$ (i.e., Eddington luminosity of a neutron star binary). Carefully considering both detected and undetected, hidden populations of point sources we further discuss the XLF of LMXBs and the metal abundance of the hot ISM and their impact on the properties of early type galaxies.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.29-35
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• 2008

In this paper, The author present a load current feed-forward compensator by method that improve voltage controller of Step-down Chopper to get stable output voltage to sudden change of load current. To confirm the characteristics of a presented load current feed-forward compensator compared each transfer function of whole system that load current feed-forward compensator is added with transfer function of whole system that existent voltage controller is included using Mason gains formula in Root locus and Bode diagram. As a result the pole of system is improved, extreme point of the wave and system improves, and size of peak value and phase margin of break frequency in resonance frequency confirmed that is good. Therefore, presented control technique could confirm that reduce influence by perturbation and improves stationary state and dynamic characteristics in output of Step-down Chopper.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.486-490
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• 2004

Programmable logic controller (PLC) is widely used in manufacturing system or process control. This paper presents the design of a 32-bit microprocessor for a sequence control using an Application Specification Integrated Circuit (ASIC). The 32-bit microprocessor was designed by a VHDL with top down method; the program memory was separated from the data memory for high speed execution of 274 specified sequence instructions. Therefore it was possible that sequence instructions could be operated at the same time during the instruction fetch cycle. And in order to reduce the instruction decoding time and the interface time of the data memory interface, an instruction code size was implemented by 32-bits. And the real time debugging as single step run, break point run was implemented. Pulse instruction, step controller, master controllers, BIN and BCD type arithmetic instructions, barrel shit instructions were implemented for many used in PLC system. The designed microprocessor was synthesized by the S1L50000 series which contains 70,000 gates with 0.65um technology of SEIKO EPSON. Finally, the benchmark was performed to show that designed 32-bit microprocessor has better performance than Q4A PLC of Mitsubishi Corporation.

• Journal of Applied Tourism Food and Beverage Management and Research
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• v.13 no.2
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• pp.207-221
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• 2002

Wolaksan is a national park which has beautiful scenery with exposed rocks. The mountain is 1097 meters high and has 3 tops which are Jungang(the center), Arae(the lower part), Jjokduri. The highest point of the vertical cliff is 150m from the earth and the total circumferences of three tops is about 4km. These tops are easy to break by grains because they are from sedimentary rocks. Wolaksan is a bad mountain because the area is a Mosikjuk rocky area. However, the area around Wolaksan is thicky wooded and has many achievements and it makes good scenery. From top to southeastern, there are vertical cliff, The tops are originally from one but these are divided by partial weathering corrosion. The slide of path to Wolaksan is about 70。. The lower part of the mountain from Shinroksa to top has a gentle slope but there are a steep slope from the middle. Especially, the area has many rocks. The rocks of Wolaksan are almost granitic-gneiss or metamorphic rocks so it often fall down. Because of these fallen rocks, its valleys have great landscapes. The size of rock is less than 60cm. The landscapes of valleys such as Songgye, Dukju, Yonghwa are the main natural tourism resources.

• Elastomers and Composites
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• v.51 no.1
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• pp.24-30
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• 2016

Sole in the footwear usually modified with foaming agent on the polymer resin to improve the lightweightness and crush-cushion effect. In this study, we investigated rheological properties for polymer resin filled with the different type and concentration of foaming agent, capsule type foaming agent and organo-chemical foaming agent, under the time sweep test. Curing times of each polymer resin with different kind of foaming agent are delayed than reference material (epoxy resin with curing agent). In case of adding capsule type foaming agent, however, there is appropriate concentration to reduce the curing time, relatively. When foaming agent is activated, foaming force inflates the sample in contrast to condensation force of curing and then axial normal force develop to the (+) direction. Interestingly, by increase concentration of foaming agent, there is a specific point to break down the axial normal force development. The reason for this phenomenon is that coalescence of foams induce the blocking of axial normal force development.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.9
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• pp.783-789
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• 2003

The winding problems of traction motor are the major determinant of motor's life. The root cause of winding failure is gradual deterioration of the insulation due to thermal, electrical, mechanical and environmental stresses. The aging of the insulation reduces the electrical and mechanical strength of the insulation. At same point, a voltage surge or mechanical shock from a traction motor start will fracture or break down the insulation. To achieve the expected life usually requires extensive laboratory evaluation of the insulation systems and the use of accelerated aging tests. There are several nondestructive test available for checking, the condition of motor insulation, the probable extent of aging, and the rate of which aging is taking place. So the insulation characteristics of stator coil were each analyzed by measurement of dielectric loss(tan$\sigma$), capacitance and partial discharge. The method of diagnosis is able to analyze the insulation condition and evaluate the life of the traction motor.

• The Korean Journal of Applied Statistics
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• v.19 no.1
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• pp.97-110
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• 2006

Since it is well-established that even high quality data tend to contain outliers, one would expect fat? greater reliance on robust regression techniques than is actually observed. But most of all robust regression estimators suffers from the computational difficulties and the lower efficiency than the least squares under the normal error model. The weighted self-tuning estimator (WSTE) recently suggested by Lee (2004) has no more computational difficulty and it has the asymptotic normality and the high break-down point simultaneously. Although it has better properties than the other robust estimators, WSTE does not have full efficiency under the normal error model through the weighted least squares which is widely used. This paper introduces a new approach as called the reweighted WSTE (RWSTE), whose scale estimator is adaptively estimated by the self-tuning constant. A Monte Carlo study shows that new approach has better behavior than the general weighted least squares method under the normal model and the large data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.6
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• pp.596-605
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• 2007

The behavior of a non-buoyant turbulent round jet discharging horizontally was investigated experimentally. The instantaneous velocity field of the jet was obtained using the particle image velocimetry (PIV) method and used to calculate the mean velocity field by phase-averaging. This study tested regular waves with a relatively small wave height for a wavy environmental flow. The centerline and cross-sectional velocity profiles were reported to demonstrate the effect of the waves on the jet diffusion in respect of wave height and wave phase. The wave phase effect was studied for three phases: zero-upcrossing point, zero-downcrossing point, trough. From the results, it is found that the centerline velocity decreases and width of the cross-sectional profile increases as the wave height increases. In addition, the self-similarity of the cross-sectional profile appears to break down although the width of each case along the axial distance does not vary significantly. The phase effect is found to be relatively small compared to the wave height effect.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.6
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• pp.431-441
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• 2003

This paper presents the design of 32 bit microprocessor for a sequence control using a field programmable gate array(FPGA). The microprocessor was designed by a VHDL with top down method, the program memory was separated from the data memory for high speed execution of sequence instructions. Therefore it was possible that sequence instructions could be operated at the same time during the instruction fetch cycle. In order to reduce the instruction decoding time and the interface time of the data memory interface, an instruction code size was implemented by 32 bits. And the real time debug operation was implemented for easeful debugging the designed processor with a single step run, PC break point run, data memory break point run. Also in this designed microprocessor, pulse instructions, step controllers, master controllers, BM and BCD type arithmetic instructions, barrel shift instructions were implemented for sequence logic control. The FPGA was synthesized under a Xilinx's Foundation 4.2i Project Manager using a V600EHQ240 which contains 600,000 gates. Finally simulation and experiment were successfully performed respectively. For showing good performance, the designed microprocessor for the sequence logic control was compared with the H8S/2148 microprocessor which contained many bit instructions for sequence logic control. The designed processor for the sequence logic showed good performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.255-262
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• 2011

In a loss-of-coolantaccident, considerable debris may be generated and transported to the recirculation sump. The accumulation of debris will reduce the netpositivesuctionhead and threaten the safety of thenuclear power plant. Both NEI 04-07 and USNRC SER suggesteda CFD methodology. However, additional investigation is needed to consider the unique characteristics of nuclear power plants. The transport of the generated debris is strongly influenced by the break location and the plant characteristics, including the configuration.In this paper, a CFD methodology for blow-down transport evaluation is proposed and applied to an OPR1000 nuclear power plant. The results show that the percentage of small debris transported to the upper containment is 32%, which is 7% larger than the valuegiven in the NEI 04-07 baseline analysis. This result may be used as a point of reference in future analytical studies.