• Title, Summary, Keyword: 삽입손실

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Studies on Fabrication of Novel Micromachined SIR. Bandpass Filter Using DAMLs (DAML 구조를 이용한 새로운 형태의 SIR대역 통과 여파기의 설계 및 제작)

  • Baek Tae-Jong;Ko Baek-Seok;Kim Sung-Chan;Lim Byeong-Ok;An Dan;Kim Soon=Koo;Shin Dong-Hoon;Rhee Jin-Koo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.7
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    • pp.760-767
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    • 2005
  • In this paper, we proposed a new type SIR bandpass filter using DAMLs. This filter is consisted of 2 layers with MEMS resonator layer and CPW feed line. DAMLs ring resonator is elevated with $10{\mu}m$ height from GaAs substrate. Using MEMS processing, we are able to realize SIR bandpass filter easily. Furthermore it is useful to integrate on conventional MMICs because it has CPW interfaces and ring resonator is isolated from substrate by air-gap. We optimized and measured the results that $S_{21}$ attenuation at rejected band is over 15 dB, insertion loss is inside the limit of 3 dB, and relative bandwidth is about $10\%$ at 60 GHz.

Multi-Pole Low Pass Filter Embedded K-Band LTCC Upconverter (다중 폴 저역 통과 여파기가 내장된 K-대역 LTCC 주파수 상향 변환기)

  • Jeong, Jin-Cheol;Yom, In-Bok;Yeom, Kyung-Whan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.6
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    • pp.621-629
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    • 2008
  • This paper presents a low temperature co-fire ceramics(LTCC) Upconverter for a Ka-band OBS satellite transponder in order for size reduction which is one of the most important requirement for satellite components. A S-band low-pass filter(LPF), a K-band band-pass filter(BPF), and an upconverting MMIC mixer are embedded in the multi-layer structure of the upconverter. All spurious can be selectively rejected by employing a modified Elliptic low pass filter with a multi-pole structure for the S-band LPF. Also an improved performance of out-of-band rejection can be obtained. At the K-band BPF design a layer coupled configuration is employed. The upconverting mixer is an MMIC diode mixer with a double-balanced configuration. Conversion loss and isolation of the upconverter are 9 dB and 51 dBc, respectively. The size of the LTCC upconverter is only $8{\times}7{\times}0.6mm^3$ which is one-third for the thin-film based upconverter.

An Algorithm for Submarine Passive Sonar Simulator (잠수함 수동소나 시뮬레이터 알고리즘)

  • Jung, Young-Cheol;Kim, Byoung-Uk;An, Sang-Kyum;Seong, Woo-Jae;Lee, Keun-Hwa;Hahn, Joo-Young
    • The Journal of the Acoustical Society of Korea
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    • v.32 no.6
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    • pp.472-483
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    • 2013
  • Actual maritime exercise for improving the capability of submarine sonar operator leads to a lot of cost and constraints. Sonar simulator maximizes the capability of sonar operator and training effect by solving these problems and simulating a realistic battlefield environment. In this study, a passive sonar simulator algorithm is suggested, where the simulator is divided into three modules: maneuvering module, noise source module, and sound propagation module. Maneuvering module is implemented in three-dimensional coordinate system and time interval is set as the rate of vessel changing course. Noise source module consists of target noise, ocean ambient noise, and self noise. Target noise is divided into modulated/unmodulated and narrowband/broadband signals as their frequency characteristics, and they are applied to ship radiated noise level depending on the vessel tonnage and velocity. Ocean ambient noise is simulated depending on the wind noise considering the waveguide effect and other ambient noise. Self noise is also simulated for flow noise and insertion loss of sonar-dome. The sound propagation module is based on ray propagation, where summation of amplitude, phase, and time delay for each eigen-ray is multiplied by target noise in the frequency domain. Finally, simulated results based on various scenarios are in good agreement with generated noise in the real ocean.

Growth Characteristics of a Pyruvate Decarboxylase Mutant Strain of Zymomonas mobilis (Pyruvate decarboxylase 돌연변이 Zymomonas mobilis 균주의 생장 특성 연구)

  • Xun, Zhao;Peter L., Rogers;Kwon, Eilhann E.;Jeong, Sang Chul;Jeon, Young Jae
    • Journal of Life Science
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    • v.25 no.11
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    • pp.1290-1297
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    • 2015
  • Studies of the inactivation of a gene encoding pyruvate decarboxylase, pdc, in an ethanol-producing bacterium, Zymomonas mobilis, identified a mutant strain with 50% reduced PDC activity. To evaluate the possibility of a carbon-flux shift from an ethanol pathway toward higher value fermentation products, including pyruvate, succinate, and lactate, fermentation studies were carried out. Despite attempts to silence pdc expression in the wild-type strain ZM4 using cat-inserted pdc and pdc-deleted homologs by electroporation, the strain isolated showed partial gene activation. Fermentation experiments with the PDC mutant strain showed that the reduced expression level of PDC activity resulted in decreased rates of substrate uptake and ethanol production, together with increased pyruvate accumulation of 2.5 g l-1 , although lactate and succinate concentrations were not significantly enhanced in these modified strains. Despite numerous attempts, no strains were isolated in which complete pdc inactivation occurred. This result indicates that the ethanol fermentation pathway of this bacterium is totally dependent on the activity of the PDC enzyme. To ensure a redox balance of intracellular NAD and NADH levels, other enzymes, such as lactate dehydrogenase for lactate, and enzymes involved in the production of succinic acid, such as pyruvate dehydrogenase (PDH) and malic enzymes, may be needed for their increased end-product production.

A Miniaturized and Band Rejection Characteristic of Bow-Tie Monopole UWB Antenna (보우-타이 모노폴 UWB 안테나의 소형화 및 대역 저지 특성)

  • Choi, Hyung-Seok;Choi, Kyoung;Hwang, Hee-Yong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.3
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    • pp.300-305
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    • 2012
  • In this paper, a miniaturized bow-tie monopole UWB antenna with band rejection characteristic is proposed. To miniaturize the proposed antenna, a perfect magnetic wall(PMW) condition is applied to primitive bow-tie monopole antenna. An uneven ground patch, a tapered feeding structure and a edge-chopped main patch are adapted for impedance matching. A quater-lambda slot resonator is inserted at main patch to prevent interference in UWB band from another band. The proposed antenna is fabricated on Taconic RF60-A substrate with relative permittivity of 6.15. The size of the proposed antenna is $30.0{\times}39.7mm^2$, which is only 45 % of the conventional bow-tie monopole antenna. The proposed antenna covers full UWB band with return losses less than -10 dB and has band stop characteristic in 5 GHz WLAN band. The maximum gains are within -1.0~5.0 dBi, the group delay variations are within 1.0 ns and the radiation patterns show directivity characteristics in x-y plane.

Measuring Plate Thickness Using Spatial Local Wavenumber Filtering (국소 공간 웨이브넘버 필터링 기법을 이용한 평판 구조물 두께 측정)

  • Kang, To;Lee, Jeong Han;Han, Soon Woo;Park, Jin Ho;Park, Gyuhae;Jeon, Jun Young
    • Journal of the Korean Society for Nondestructive Testing
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    • v.36 no.5
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    • pp.370-376
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    • 2016
  • Corrosion on the surface of a structure can generate cracks or cause walls to thin. This can lead to fracturing, which can eventually lead to fatalities and property loss. In an effort to prevent this, laser imaging technology has been used over the last ten years to detect thin-plate structure, or relatively thin piping. The most common laser imaging was used to develop a new technology for inspecting and imaging a desired area in order to scan various structures for thin-plate structure and thin piping. However, this method builds images by measuring waves reflected from defects, and subsequently has a considerable time delay of a few milliseconds at each scanning point. In addition, the complexity of the system is high, due to additional required components, such as laser-focusing parts. This paper proposes a laser imaging method with an increased scanning speed, based on excitation and the measurement of standing waves in structures. The wavenumber of standing waves changes at sections with a geometrical discontinuity, such as thickness. Therefore, it is possible to detect defects in a structure by generating standing waves with a single frequency and scanning the waves at each point by with the laser scanning system. The proposed technique is demonstrated on a wall-thinned plate with a linear thickness variation.

A Study on Chloride Threshold Level of Blended Cement Mortar Using Polarization Resistance Method (분극저항 측정기법을 이용한 혼합 시멘트 모르타르의 임계 염화물 농도에 대한 연구)

  • Song, Ha-Won;Lee, Chang-Hong;Lee, Kewn-Chu;Ann, Ki-Yong
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.245-253
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    • 2009
  • The importance of chloride ions in the corrosion of steel in concrete has led to the concept for chloride threshold level (CTL). The CTL can be defined as the content of chlorides at the steel depth that is necessary to sustain local passive film breakdown and hence initiate the corrosion process. Despite the importance of the CTL, due to the uncertainty determining the actual limits in various environments for chloride-induced corrosion, conservative values such as 0.4% by weight of cement or 1.2 kg in 1 $m^3$ concrete have been used in predicting the corrosion-free service life of reinforced concrete structures. The paper studies the CTL for blended cement concrete by comparing the resistance of cementitious binder to the onset of chloride-induced corrosion of steel. Mortar specimens were cast with centrally located steel rebar of 10 mm in diameter using cementitious mortars with ordinary Portland cement (OPC) and mixed mortars replaced with 30% pulverized fuel ash (PFA), 60% ground granulated blast furnace slag (GGBS) and 10% silica fume (SF), respectively, at 0.4 of a free W/B ratio. Chlorides were admixed in mixing water ranging 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 2.0, 2.5 and 3.0% by weight of binder(Based on $C1^-$). Specimens were curd 28 days at the room temperature, wrapped in polyethylene film to avoid leaching out of chloride and hydroxyl ions. Then the corrosion rate was measured using the polarization resistance method and the order of CTL for binder was determined. Thus, CTL of OPC, 60%GGBS, 30%PFA and 10%SF were determined by 1.6%, 0.45%, 0.8% and 2.15%, respectively.

Comparison of the Uniaxial Tensile Strength, Elasticity and Thermal Stability between Glutaraldehyde and Glutaraldehyde with Solvent Fixation in Xenograft Cardiovascular Tissue (이종심혈관 조직에 대한 글루타알데하이드 및 용매를 첨가한 고정방법에 따른 장력, 탄력도 및 열성 안정성 비교연구)

  • Cho, Sung-Kyu;Kim, Yong-Jin;Kim, Soo-Hwan;Park, Ji-Eun;Kim, Wong-Han
    • The Korean Journal of Thoracic and Cardiovascular Surgery
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    • v.42 no.2
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    • pp.165-174
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    • 2009
  • Background: With the advances of cardiac surgery, the demand for an artificial prosthesis has increased, and this has led to the development and utilization of diverse alternative materials. We conducted this research to improve an artificial prosthesis by examining the changes of the physical qualities, the pressure related tensile strength, the change in elasticity and the thermostability of a xenograft valve (porcine) and pericardium (bovine, porcine) based on the type of fixation liquid we used. Material and Method: The xenograft valves and pericardium were assigned into three groups: the untreated group, the fixed with glutaraldehyde (GA) group and the glutaraldehyde with GA+solvent such as ethanol etc. group. The surgeons carried out each group's physical activities. Each group's uniaxial tension and elasticity was measured and compared. Thermostability testing was conducted and compared between the bovine and porcine pericardium fixed with GA group and the GA+solvent group. Result: On the physical activity test in the surgeon's hand, no significant difference between the groups was sensed on palpation. For suture and tension, the GA+solvent group was slightly firmer than the low GA concentration group. In general, the circumferential uniaxial tension and elasticity of the porcine aortic and pulmonary valves were better in the fixed groups than that in the untreated group. There was no significant difference between the GA and GA+solvent groups (p>0.05). Bovine and porcine pericardium also showed no significant difference between the GA group and the GA+solvent group (p>0.05). When comparing between the groups for each experiment, the elasticity tended to be stronger in most of the higher GA concentration group (porcine pulmonary valve, porcine pericardium). On the thermostability testing of the bovine and porcine pericardium, the GA group and the G+solvent group both had a sudden shrinking point at $80^{\circ}C$ that showed no difference (bovine pericardium: p=0.057, porcine pericardium: p=0.227). Conclusion: When fixing xenograft prosthetic devices with GA, adding a solvent did not cause a loss in pressure-tension, tension-elasticity and thermostability. In addition, more functional solvents or cleansers should be developed for developing better xenografts.

Compact Orthomode Transducer for Field Experiments of Radar Backscatter at L-band (L-밴드 대역 레이더 후방 산란 측정용 소형 직교 모드 변환기)

  • Hwang, Ji-Hwan;Kwon, Soon-Gu;Joo, Jeong-Myeong;Oh, Yi-Sok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.7
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    • pp.711-719
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    • 2011
  • A study of miniaturization of an L-band orthomode transducer(OMT) for field experiments of radar backscatter is presented in this paper. The proposed OMT is not required the additional waveguide taper structures to connect with a standard adaptor by the newly designed junction structure which bases on a waveguide taper. Total length of the OMT for L-band is about 1.2 ${\lambda}_o$(310 mm) and it's a size of 60 % of the existing OMTs. And, to increase the matching and isolation performances of each polarization, two conducting posts are inserted. The bandwidth of 420 MHz and the isolation level of about 40 dB are measured in the operating frequency. The L-band scatterometer consisting of the manufactured OMT, a horn-antenna and network analyzer(Agilent 8753E) was used STCT and 2DTST to analysis the measurement accuracy of radar backscatter. The full-polarimetric RCSs of test-target, 55 cm trihedral corner reflector, measured by the calibrated scatterometer have errors of -0.2 dB and 0.25 dB for vv-/hh-polarization, respectively. The effective isolation level is about 35.8 dB in the operating frequency. Then, the horn-antenna used to measure has the length of 300 mm, the aperture size of $450{\times}450\;mm^2$, and HPBWs of $29.5^{\circ}$ and $36.5^{\circ}$ on the principle E-/H-planes.

Analysis of Structural Safety of the Welded Pipe Columns Adopted in Paprika Greenhouse (파프리카 재배용 온실에서 용접 파이프 기둥재의 구조적 안전성 검토)

  • Suh, Won-Myung;Choi, Man-Kwon;Im, Jae-Un;Kwon, Sun-Ju;Kim, Hyeon-Tae;Kim, Young-Ju;Yoon, Yong-Cheol
    • Journal of agriculture & life science
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    • v.45 no.2
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    • pp.125-133
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    • 2011
  • This study was conducted on greenhouses whose side heights had been raised after the columns of 1-2W basic type greenhouses had been cut and welding with the same-sized pipes. When the wind load or snow load affects restructured pipe greenhouse like this, those parts will be structurally unsafe. To examine this, the bending strength of welded columns were measured through four stages and compared with the pipes in their original condition. Results are as follows. In the case of a bending test on welded joints about steel pipes used for greenhouses, satisfactory results couldn't be drawn because sections of both ends and the loading parts couldn't endure loads and sank regardless of loading methods. Partial problems could be solved by inserting inside pipe(steel bar) at the sections and the loading parts, but it was necessary to devise more satisfactory bending test methods. The strength of welded joints wasn't much different compared with original conditions and demonstrated only slight differences according to the sample production conditions. However, significant incompleteness in the welding process was expected to cause a decisive loss in strength. On the assumption that there were no problems in the welding process or with regard to the inclination of sub materials for columns after connection, it was deemed reasonable to assume that the strength of welded pipes was about 84~90% of the strength of the pipes in their original condition. Considering mid- and long-term strength decline following the onset of rust at joints or welding sections, structural changes in the main sub materials that are used for greenhouses at farmhouses have to be avoided to ensure structural safety, unless these changes are inevitable.