• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.4
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• pp.38-42
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• 2010

In this paper, a design method of the compact narrow band filter on the microstrip board is proposed using slot-type split spiral resonators. The design technique of this filter is based on cascading filter stages consisting of the combination of slot-type split spiral resonators, capacitive gaps between patches, and inductive grounded stubs with the meander configuration. By these means, it was possible to get the nearly symmetric frequency responses, adjustable bandwidths, compact sizes. And also excellent characteristic of the out-of-band rejection is achieved in contrast to the conventional filter design technique. The measured insertion loss shows good results about -3.47dB at the center frequency($f_0$=1GHz) and passband return loss is less than -12.62dB. The 3dB fractional bandwidth(FBW) is approximately 7.3%. The results of the frequency response measured on the fabricated band pass filter substrate show satisfactory agreement with the simulated frequency responses by the MWS(Microwave Studio) of CST in the region of interest.

• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.108-116
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• 2018

In this paper, a method of designing a Vivaldi type phased array antenna (PAA) which operates at S-band (2.8-3.3 GHz) is presented. The presented antenna uses broadside coupled split ring resonators (BC-SRRs) for high isolation, wide field of view, and good active S-parameter characteristics. As an example, we design a $1{\times}8$ array antenna with various BC-SRR structures using theory and EM simulations. The antenna is fabricated and measured to verify the design. With the BC-SRR implemented between the two radiating elements, the isolation is shown to be enhanced by 6 dB, up to 23 dB. The scan angle is shown to be within ${\pm}53^{\circ}$ based on a -10 dB active reflection coefficient. The operation of the scan angle is possible within ${\pm}60^{\circ}$ with a little larger reflection coefficient (-7 dB to -8 dB). The proposed design with BC-SRRs is expected to be useful for PAA applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.247-255
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• 2018

In this work, glucose solution and sodium chloride solution were distinguished noninvasively using a microwave complementary split-ring resonator (CSRR). Based on the electrical properties of the two solutions measured using a open-ended coaxial probe, a CSRR was designed and fabricated for operation at a specific frequency that facilitates differentiating the two solutions. Furthermore, a polydimethylsiloxane mold was fabricated to concentrate the solution at a region where the electric field of the resonator was strongest, and a laminating film was used to prevent contact between the solution and resonator. Experiments were performed by dropping $50{\mu}L$ of the solution in steps of 100 mg/dL up to a maximum human blood glucose level of 400 mg/dL. Our experiments confirmed that the transmission coefficients ($S_{21}$) of glucose solution and sodium chloride solution exhibit variations of -0.06 dB and 0.14 dB, respectively, per 100 mg/dL concentration change at the resonance frequency. Thus, the opposite trends in the variation of $S_{21}$ with change in the concentration of the two solutions can be used to distinguish between them.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.212-223
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• 1995

To improve the efficiency of a power transmission system with slip elements, power split/circulation system is applied. The performance of a power split/circulation system varies widely by the change of the followings; the layout of system, the type and gear ratio of planetary gear, the performance of slip element, etc. Therefore, when one designs such a power transmission system or when one determines the economic/power mode of system, a certain performance prediction method is needed. In this study, the internal power flow pattern of a power split/circulation system is theoretically analyzed on several transmission systems. And an effective performance prediction method(so called performance locus diagram) is presented. By this method, the effects of design factors can be easily understood and the qualitative performances of system can be clearly evaluated.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.52-53
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• 2012

This paper presents a new control scheme for a three-phase split DC-link capacitor inverter as an AC power supplies. The proposed control method can maintain the balanced sinusoidal output voltage under unbalanced and nonlinear load conditions. The validity of the control method has been verified by simulation results.

• Journal of Environmental Impact Assessment
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• v.19 no.3
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• pp.223-230
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• 2010

Trajectory dispersion models are used for the dispersion calculations in air quality assessments, Yellow-sand modeling, environmental planning and the emergency response. Meso-scale forcing and coastal circulations are calculated by trajectory model in the East Asia region. In this study the meteorological fields (GDAS and MM5) coupled to the trajectory model (HY-SPLIT) are applied to simulate the transport and the dispersion. Seoul is selected as a starting point of the HY-SPLIT. The sensitivity studies are performed by conducting an ensemble of simulations using the GDAS and the MM5 model for the same dispersion cases. The results in this study show a significant difference depending on the resolution of meteorological models. Additionally, in most cases of the compared tionally,results from MM5 and GDAS, the absolute and relative distance, shows significant difference and the difference increased with the increasing distance of HY-SPLIT. Therefore, for the case of small domai for twi d field distefbution over complex terrai, should be used only high model temporal or spatial resolution to improve the HY-SPLIT model results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.7
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• pp.818-825
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• 2004

In this paper, the study of effects of flow parameters on flame structure and NOx emission concentration was performed in co-axial. laminar partially premixed methane/air flames. Such (low parameters as equivalence ratio(${\Phi}$), fuel split percentage($\sigma$), and mixing distance(x/D$\_$i/) were defined as a premixing degree and varied within ${\Phi}$=1.36∼9.52, $\sigma$=50∼100, and x/D$\_$i/=5∼20. The image of OH$\^$*/ and NOx concentration were obtained with an ICCD camera and a NOx analyzer. The flame structure observations show a categorization of partially premixed flames into three distinct flame regimes corresponding to ${\Phi}$<1.7(premixed flame structure), 1.7<${\Phi}$<3.3(hybrid structure), and ${\Phi}$>3.3(diffusion flame structure existing a luminous sooting region) at $\sigma$=75%, and x/D$\_$i/=10. As o decreases from 100% to 50%, and x/D$\_$i/ decreases, nonpremixed flame structure appear at low equivalence ratio relatively. In addition, the measured emissions for NOx rise steeply from ${\Phi}$=1.7, to ${\Phi}$=3.3, then constants ${\Phi}$>4.76. NOx emissions decrease with increase the level of premixing level. In conclusion, the main effect on flame structure and NOx production was at first equivalence ratio(${\Phi}$), and next fuel split percentage($\sigma$), and finally mixing distance(x/D$\_$i/).

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.3
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• pp.41-51
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• 2001

Combustion characteristics of a KSR-III liquid rocket engine with split-triplet (F-O-O-F) type injector elements are investigated numerically from the viewpoints of engine performance and combustion flowfield. To evaluate numerical analysis of liquid rocket engine with radial type injector arrangement, 2-D axisymmetric and 3-D calculations are carried out and the prediction of engine performance for design and off-design conditions is in a good agreement with hot-firing tests. According to 2-D axisymmetric and 3-D calculations, the prediction error is 3∼5 % from the standpoint of performance. Numerical results of combustion characteristics calculated through 3-D analysis agree well with hot-firing tests qualitatively at injector plate. Decreasing impinging angle and changing radial type injector arrangement to H type injector arrangement reduce effectively local high-temperature region. Also, it is examined that those affect the performance seriously. In conclusion, it is revealed that both injector arrangement and impinging angle are critical parameters to affect the performance and combustion characteristics of the liquid rocket engine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.729-730
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• 2007

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.4
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• pp.22-31
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• 2010

In this paper, a new split ring resonator using left-handed meta-material adapted in a bandpass filter with 2-stages is suggested. In this proposed bandpass filter, the size of the novel resonator can be easily controlled. Also, the bandwidth can be adjusted with the position of the tapped-line. The proposed resonator and filter has the center frequency of 10 GHz for I-band in military-satellite communication system with the Qe value of 184. The experimental results of the filter show that the insertion and return losses are 1.43 dB and 16.8 dB with bandwidth of 10 %, respectively.