• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.870-877
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• 1998

With impedance spectrum measurements, impedance was studied in the interface between sample solutions for $K^+-ion$ selective PVC membrane electrode containing neutral carriers [dibenzo-18-crown-6 (D18Cr6) and valinomycine (Val)]. Response characteristics of electrode were examined by measuring AC impedance spectra that were resulted from the chemical structure and the content of carrier, variation of plasticizer, membrane thickness, doping of base electrolytes, and concentration variation of sample solution. Transport characteristics of PVC membrane electrode were also studied. It was found that the equivalent circuit for the membrane in $K^+$ solution could be expressed by a series combination of solution resistance and a parallel circuit consisting of the bulk resistance and geometric capacitance of the membrane system. But the charge transfer resistance and Warburg resistance were overlapped a little in the low concentration and low frequency ranges. The carrier, D18Cr6 was best for electrode and impedance characteristics, and ideal electrode characteristics were appeared especially in case of doping of the base electrolyte[potassium tetraphenylborate(TPB)]. The optimum carrier content was about 3.23 wt% in case of D18Cr6 and Val. DBP was best as a plasticizer. As membrane thickness decreased the impedance characteristics was improved, but electrode characteristics were lowered for membrane thickness below the optimum. In the case of D18Cr6, the selectivity coefficients by the mixed solution method for the $K^+$ ion were the order of $NH_4{^+}>Ca^{2+}>Mg^{2+}>Na^+$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3474-3481
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• 2013

In this work, a new high frequency transmission line structure combined with defected ground structure (DGS) and artificial dielectric substrate (ADS) structure is proposed. DGS patterns give add the additional inductance to transmission lines and results in the increased characteristic impedance for a given line width. To the contrary, ADS presents increased capacitance and reduced line impedance. So both play a role in reducing the length of transmission lines commonly, but in preserving the line impedance complementarily. This means that the length of transmission lines can be reduced furtherly by DGS and ADS without a critical change of line width compared to the cases when one of DGS and ADS is used only. As examples, $35{\sim}100{\Omega}$ transmission lines having DGS and ADS are designed, fabricated, measured, and compared to the simulation results. A good agreement between the simulated and measured line impedances is presented. In addition, the physical lengths of the proposed transmission lines are only 55.4~76.9% of those of the normal microstrip lines for the same electrical lengths.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.10
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• pp.67-75
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• 1998

This paper examined the geometrical variables of microstrip to control the characteristic impedance of MCM interconnect and also with respect to the practical requirements, evaluated the critical lengths for attenuation, propagation delay, and crosstalk at 500 MHz frequency compared to at 50 MHz frequency. With the illustration of each MCM-L and MCM-D interconnect having 50 characteristic impedance, it was revealed that the most important geometrical variables to control the characteristic impedance of microstrip are eventually dielectric thickness and line width. In particular, the dielectric thickness of MCM-D interconnect must be controlled with tolerance below 2 m. It is clear that the attenuation does not give rise to signal distortion in the range of up to 500MHz frequency for both MCM-L and MCM-D interconnects. However, the propagation delay is so significant that both MCM-L and MCM-D interconnects should be matched with load at the 500 MHz frequency. For the MCM-D interconnect, the crosstalk voltage would not be high to generate the wrong signal on the neighboring line at 500 MHz frequency, but the MCM-L interconnect could not be used due to severe crosstalk. Eventually, it is clear that the transmission line behavior must be studied for the design of MCM substrate at the 500 MHz frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.401-412
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• 2003

In this paper, a broadband phase shifter structure using a new switched network was proposed. A new reference network is composed of coupled lines and 45$^{\circ}$open and short stubs, which are shunted at the edge points of a main line, respectively, A delay network is composed of only a standard transmission line. It is possible to design a broadband 180$^{\circ}$phase shifter that phase dispersive characteristics by an impedance ratio R of coupled lines and greater phase dispersive characteristics by characteristic impedances Zm, Zs of a main line and stubs are used together. By considering a structure symmetry, the even and odd mode analysis was performed to obtain theoretical S-parameters of the proposed phase shifter. Also, through computer simulation on the basis of derived equations, design graphs were presented to optimally design a 180$^{\circ}$broadband phase shifter. Design graphs provide the values of characteristic impedances Zm, Zs, and I/O match and phase bandwidths. To verify electrical performances of the broadband phase shifter proposed in this paper, low different 180$^{\circ}$phase shifters, operated at the center frequency 3 GHz were designed and fabricated using design graphs, and were experimented. One of them was designed as a standard Schiffman structure to compare with electrical performances. Measured results of each phase shifter to satisfy simultaneously design conditions of I/O match （VSWR=1.15:1) and maximum phase deviation $({\varepsilon}_{{\Delta}{\phi}}＝{\pm}2^{\circ})$ were well in agreement with corresponding simulation results over impedance match and phase error bandwidths, and showed broadband characteristics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.72-77
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• 2006

This paper presents the transient impedance behaviors according to the length of down conductors of grounding systems to lightning impulse currents. The potential rise and effective impulse ground impedance of the deeply-driven ground rod and grounding grid subjected to the impulse currents were measured and analyzed as a function of the rise time of impulse currents and lengths of down conductor. The transient ground impedances strongly depend on the configuration and size of grounding electrodes, the waveform of impulse currents and the length of down conductors, and the installation methods reducing the inductance of down conductors are an important factor to decrease the transient ground impedances.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.389-392
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• 2000

본 연구에서는 1, 2단자쌍 회로망의 임피던스 정합회로를 간단하고 빠르게 구할 수 있는 방안을 개발하였다. 우선 회로망의 전체 전달함수를 F 행열로 부터 계산하고, 이를 이용하여 양단의 부하저항 및 정합회로가 포함된 각각의 단자의 입출력 임피던스를 구하였으며, 이 식으로부터 정합용 소자의 정확한 값을 계산하였다. 본 연구의 타당성을 검증하기 위해 CDMA용 소자로 널리 사용되는 중간주파수 대역 withdrawal 가중형 SAW 필터에 본 연구의 결과를 적용하여 임피던스 정합 전후의 특성변화를 시뮬레이션과 실험을 통하여 동시에 확인하였다 그 결과 85.38 MHz의 중심주파수에서 비대역폭이 $1.2\%$, 삽입손실이 29dB, VSWR이 80인 필터를 본 연구방법을 이용하여 정합 한 경우, 각각 $1.8\%$, 9dB, 3으로 향상됨을 시뮬레이션과 실험을 통해 확인하였다. 본 연구결과는 SAW 디바이스의 정합에 매우 용이하게 이용될 수 있을 뿐만 아니라 일반적인 1, 2단자쌍 회로망의 임피던스 정합에도 널리 사용될 수 있다

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.1
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• pp.18-22
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• 2013

Input impedance of the inverted L antenna which is modified from a monopole antenna varies to very high input impedance value when the ratio of vertical height to horizontal length is reduced. So its impedance matching becomes very difficult. In this paper, we analyzed the input impedance variation range depending on the ratio of vertical height to horizontal length in the normal and ferrite thin film added configuration for the input impedance control. For the exact analysis involving the permittivity, permeability and conductivity of ferrite material, FDTD numerical method is used.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.181-187
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• 2004

With the proliferation of nonlinear loads, high neutral harmonic currents in three-phase four-wire distribution system have been observed. It has been known that the ground impedance has an effect on the neutral currents of a system which operates with harmonics present. On-site measurements of harmonic currents and voltages according to the fall-of-potential method under case study system were made and the ground impedance modeling using the pattern search method for the harmonic analysis was developed The ground impedance model obtained by the proposed method was compared with the frequency characteristics by field tests and has shown appropriate results, and would be applicable to evaluate the harmonic and transient response characteristics of the ground system.

• Resources Recycling
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• v.13 no.6
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• pp.26-30
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• 2004

Input impedance of the inverted L antenna which is modified from a monopole antenna varies to very high input impedance value when the ratio of vertical height to horizontal length is reduced. So its impedance matching becomes very difficult. In this paper, we analyzed the input impedance variation range depending on the ratio of vertical height to horizontal length in the normal and ferrite thin film added configuration for the input impedance control. For the exact analysis involving the permittivity, permeability and conductivity of ferrite material, FDTD numerical method is used.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.65-70
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• 2006

This paper presents the transient behaviors of grounding system impedance against lightning impulse currents. The dynamic characteristics of the deeply driven ground rod and grounding grid subjected to the impulse current were investigated. The transient ground impedance strongly depends on the configuration and size of grounding electrodes and the shapes of impulse currents, and the inductance of grounding electrodes has a significant affect on the transient ground impedance of grounding system Also, the deeply-driven ground rod was effective to reduce the transient ground impedance in time domain of miceroseconds.