• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.2110-2121
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• 1993

A numerical investigation has been carried out for the flow characteristics after exchange of some filters from the original layer to the new low pressure loss layer with equal filtering efficiency. The solution domain includes upper plenum, filter layer, clean space, access panels, and lower plenum. The concept of the distributed pressure resistance was applied to describe the momentum loss in filter layer and access panels. The evolution of the flow field is simulated using the low Reynolds number k-.epsilon. over bar turbulent model and SIMPLE algorithm based on the finite volume method. As a result, after the exchange of filter layer the power requirement can be reduced by 8-9 percent. The results also demonstrate that the perpendicularity of the flow near access panels may become worse at new filter layer than origianl filter layer. But the situation can be recovered by adjusting the jopening ratio of access panels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5696-5703
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• 2012

In this study, the characteristics of filter that make up the automotive airbag system were analyzed. The gas pressure change of airbag is directly impacted by the filter. However, it is uncertain how much the design factors of filter affect the pressure of airbag. And it is difficult to access the pressure loss coefficient in the respect of characteristics of the airbag filter in the simulation method. To solve this problem, this study suggests pressure loss coefficient of the filter using simulation analysis. But it is impossible to interpret a sudden increase of pressure such as airbag filter. To solve this problem, by applying interpolation and scale down method, analysis was processed. Also, through the simulation interpretation of airbag filter's pressure loss coefficient, the guidelines for the filter design could be suggested.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.621-624
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• 1998

This paper presents a new configuration of dielectric bandpass filter using the comb-line filter design theory. This filter is composed of a homogeneous dielectric monoblock $(\varepsilonr=35.5)$ with two metal post and a dielectric sheet $(\varepsilonr=9.8).$ In this structure, the RF leakage is suppressed without other shield housing. For the fabricated filter, insertion loss value in the passband region was 0.9dB(Max.) and return loss value was 19dB(Min). Also, this filter has a attenuation pole in the stopband.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.6
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• pp.19-28
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• 1995

In this paper, measured iris transmission loss data and simulated data by using 3-dimension full-wave analysis S/W are presented and compared with Marcuvitz's theory. And by using measured iris data, dual-mode narrow-band channel filters can be successfully implemented. This paper shows that there is severe difference between the transmission loss of iris calculated by using Marcuvitz's equation to calculate iris dimension, if the length of slot iris is longer than .lambda./.pi., and in the long urn the response of channel filter is distorted. Experimental result shows that the characteristic response of implemented channel filter by using the iris transmission loss graph presented here matches well the design specfications. In conclusion, iris transmission loss measurement method will be very useful to design channel filter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.565-573
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• 2000

In this paper, a interdigital microstrip bandpass filter is designed. A interdigital microstrip bandpass filter has many advantages such as insertion return loss, lower return loss, higher frequency selectivity and smaller in size in comparison with the conventional coupled line filter. A interdigital microstrip bandpass filter consists of quasi TEM-mode strip line resonators between parallel ground plant. Each resonator element is a quarter wavelength long of the center frequency and is short circuited at one end and open circuited at the other end. In the filter design, Ensemble software is used. Experimental results show that the bandwidth of interdigital microstrip bandpass filter is 2.52GHz, insertion loss is -1.8dB and return loss is -17.0dB at 11.20Hz.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.498-507
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• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1502-1511
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• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.41-47
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• 2009

In this paper, a band pass filter with a rejection band is proposed for UWB(Ultra Wide Band) communication system. First, low pass filter accessed cut off frequency of 10.2 GHz was designed using structure stepped impedance. And high pass filter accessed cut of frequency of 3.2 GHz was designed using parallel short-stub. There was implemented composite connection of designed low pass filter and high pass filter. The relative dielectric constant, the height, the loss tangent of the PCB substrate were ${\varepsilon}_r$=2.2, h=0.508 mm and loss tangent = 0.0009 respectively. The fabricated band pass filter shows a compact size of 3 cm. The fabricated band pass filter was characterized using 37169A VNA(Vector Network Analyzer). And measured result were obtained 7.5 GHz of bandwidth and -10 dB of return loss and -3 dB of insertion loss from pass band. The result of the research can be used for the UWB communications and MIC/MMIC, RFIC system.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.2
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• pp.186-195
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• 1998

The objective of this study was to determine if MWF(metalworking fluids) mass sampled on PVC filter lose during flowing airstream and desiccating and to present direction to correct the underestimated MWF mass. Flowing airstream caused MWF sampled on PVC filter to be breakthrough and lost. Loss of MWF on PVC filter increased in proportion to time of flowing airstream. Meanwhile, loss of MWF was observed during desiccating without flowing airstream. Vapor pressure of MWF is so low that it would not normally be thought to evaporate. However, MWF mist sampled on PVC filter has so great a surface area that loss by flowing airstream and evaporation can be appreciable. Loss between fresh and used MWF was also different. Those study results mean that NIOSH method(#0500 method) to take airborne MWF mist with PVC filter is not valid. Media to sample airborne MWF accurately still have not been introduced. It seems to be needed to estimate how much MWF on PVC filter may be lost during sampling. Regression model between sampling time including 1 day desiccating and total loss of MWF was "Total loss(%)=18.4%+0.06 sampling time(p=0.000, r2=49.6%)". This model help correct MWF lost when one measures airborne MWF using NIOSH # 0500 method.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.495-502
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• 2004

We proposed an analysis model for a Fabry-Perot cavity constructed with a plane-mirrored optical fiber and a concave-mirrored one. We presented the analysis results calculated by inserting practical values into the equations derived. The coupling loss of the cavity and the mirror loss are the most important parameters in reducing the insertion loss of the filter. In order to build a filter of finesse 600, FSR 57 nm, and insertion loss < 3 dB, the plane-concave cavity using mirrors of loss < 0.09% should be aligned for the coupling loss to be less than 0.1 %.