• The Korean Journal of Nuclear Medicine
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• v.3 no.1
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• pp.19-32
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• 1969

Radioisotope renography was carried out in 564 cases consisting of 150 normal controls, 140 hypertensives, 102 hypertensive nephropathys, 62 chronic renal diseases, non-functioning kidneys. It was aimed to study which parameter of the renogram is most applicable to any definite disease of the kidney. The analytical methods adopted were; Tobe, Spencer, Krueger, Matchida and Takeuchi. In the non-functioning kidney groups, the hemograms and serum nitrogen series were also studied to evaluate the relationships between the renograms and renal anemia. The parameters were; time of maximum amplitude (Tmax), half-time of maximum amplitude ($T\frac{1}{2}$), Kac value calculated from these two parameters in Tobe's method, slopes of Band C phase, B/A and B/C values in Spencer's method, total concentration (T.C.), minute concentration (M.C.) and minute excretion (M.E.) in Krueger's method, Matchida's K value and Takeuchi's renal function Index (R.F.I.). Following were the results: 1. In general, marked differences in the patterns of the renogram were observed between the normal controls and nephropathys. In Tobe's method, each parameter showed statistically significant delay or decrease in patients with hypertensive nephropathys and chronic renal diseases. In Spencer's method, slopes of B and C phase and B/C, also showed the statistically significant decrease in patients with hypertension, hypertensive nephropathys and chronic renal diseases. In Krueger's method, M.C. and ME showed the statistically significant differences between the control and patients with hypertension, hypertensive nephropathys and chronic renal diseases, In Matchida's method, K value showed the statistically significant differences between the control and patients with hypertensive nephropathys and chronic renal diseases. 2. It appeared, therefore, that Tobe's $T\frac{1}{2}$, Kac value, Spencer's slopes of Band C phase, B/A, B/C values, Krueger's T.C., M.C., and M.E. values, Matchida's K value are useful for the differentiation of various renal diseases, however, qualitative analysis of the renogram with one or two parameters is not accurate. 3. In bilateral non-functioning kidney groups, a positive correlation between anemia and nitrogen retention was observed, although the quantitative assessment of the degree of non-functioning was impossible.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.9
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• pp.39-46
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• 2007

This paper presents a programmable single-phase ac power source that provides a sinusoidal output voltage with an adjustable output amplitude and frequency over a wide range as well as an arbitrary waveform. The ac power source under consideration have a linear power amplifier. The desired output values can be programmed with a personal computer. The power source operates at 220[V]/60[Hz] mains and the output voltage is isolated from the input circuit. The system consists mainly of a power converter to generate and amplify the waveform signal, a controller to control the desired output signal and measure the output parameters, and a control program to set the desired output and display the values. The prototype ac power source was constructed and tested with the results demonstrating a good performance.

• Journal of Power Electronics
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• v.17 no.2
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• pp.533-541
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• 2017

This paper presents a novel Parameter-Independent Fictive-Axis (PIFA) approach for the Voltage-Oriented Control (VOC) algorithm used in grid-tied single-phase inverters. VOC is based on the transformation of the single-phase grid current into the synchronous reference frame. As a result, an orthogonal current signal is needed. Traditionally, this signal has been obtained from fixed time delays, digital filters or a Hilbert transformation. Nevertheless, these solutions present stability and transient drawbacks. Recently, the Fictive Axis Emulation (FAE) VOC has emerged as an alternative for the generation of the quadrature current signal. FAE requires detailed information of the grid current filter along with its transfer function for signal creation. When the transfer function is not accurate, the direct and quadrature current components present steady-state oscillations as the fictive two-phase system becomes unbalanced. Moreover, the digital implementation of the transfer function imposes an additional computing burden on the VOC. The PIFA VOC presented in this paper, takes advantage of the reference current to create the required orthogonal current, which effectively eliminates the need for the filter transfer function. Moreover, the fictive signal amplitude and phase do not change with a frequency drift, which results in an increased reliability. This yields a fast, linear and stable system that can be installed without fine tuning. To demonstrate the good performance of the PIFA VOC, simulation and experimental results are presented.

• Steel and Composite Structures
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• v.32 no.6
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• pp.753-767
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• 2019

Vibration control in mechanical equipments is an important problem where unwanted vibrations are vanish or at least diminished. In this paper, free vibration active control of the porous sandwich piezoelectric polymeric nanocomposite microbeam with microsensor and microactuater layers are investigated. The aim of this research is to reduce amplitude of vibration in micro beam based on linear quadratic regulator (LQR). Modified couple stress theory (MCST) according to sinusoidal shear deformation theory is presented. The porous sandwich microbeam is rested on elastic foundation. The core and face sheet are made of porous and three-phase carbon nanotubes/resin/fiber nanocomposite materials. The equations of motion are extracted by Hamilton's principle and then Navier's type solution are employed for solving them. The governing equations of motion are written in space state form and linear quadratic regulator (LQR) is used for active control approach. The various parameters are conducted to investigate on the frequency response function (FRF) of the sandwich microbeam for vibration active control. The results indicate that the higher length scale to the thickness, the face sheet thickness to total thickness and the considering microsensor and microactutor significantly affect LQR and uncontrolled FRF. Also, the porosity coefficient increasing, Skempton coefficient and Winkler spring constant shift the frequency response to higher frequencies. The obtained results can be useful for micro-electro-mechanical (MEMS) and nano-electro-mechanical (NEMS) systems.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.688-698
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• 2018

Quasi Z-Source Multilevel Inverter (QZMLI) topology has attracted grid connected Photovoltaic (PV) systems in recent days. So there is a remarkable research thrust in switching techniques and control strategies of QZMLI. This paper presents the mathematical analysis of Phase shift- Pulse Width Amplitude Modulation (PS-PWAM) for QZMLI and emphasizes on the advantages of the technique. The proposed technique uses the maximum and minimum envelopes of the reference waves for generation of pulses and proportion of it to generate shoot-through pulses. Hence, it results in maximum utilization of input voltage, lesser switching loss, reduced Total Harmonic Distortion (THD) of the output voltage, reduced inductor current ripple and capacitor voltage ripple. Due to these qualities, the QZMLI with PS-PWAM emerges to be the best suitable for PV based grid connected applications compared to Phase shift-Pulse Width Modulation (PS-PWM). The detailed math analysis of the proposed technique has been disclosed. Simulation has been performed for the proposed technique using MATLAB/Simulink. A prototype has been built to validate the results for which the pulses were generated using FPGA /SPARTAN 3E.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.955-956
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• 2014

Active noise control is noise reduction method by generate anti-phase control signal for destructive interference of through control speaker. purpose of this paper is create a virtual control source at a using the DBAP(Distance Based Amplitude Panning) algorithm which is one of the three-dimensional sound reproduction method, and verified through the experimentally for noise control method through the virtual control source. We compared active noise method by using one control speaker with active noise control method by using DBAP algorithm.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.392-396
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• 1994

A method which improves the efficiency of induction motor by controlling the input voltage by the three phase AC voltage controller is studied at the sides of theory and practice. At first, the principle of decreasing the input power and improving the efficiency by adjusting the amplitude of the input voltage according to the load rate is shown. Secondarily, the mathematical model of the three phase AC voltage controller-induction motor system is drived to translate the dynamic characteristics. The validity of the dynamic model is verified by simulation. The new driving method is also proposed, which regulates the rated speed's driving by the speed estimation from the firing angle and the magnitude reverse induced-voltage information. As a result, the digital control system is constructed. Expermintal results show desirable characteristics of proposed system.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.631-636
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• 1987

The design of ultrasonic transducer energy processing systems requires highly reliable command featuring mechanical frequency tracking and constant velocity control of the ultrasonic transducer with an acoustic load. This paper presents a new conceptional instantaneous current resultant control base high-frequency inverter using self turn-off devices driving an electrostrictive ultrasonic transducer system and its optimum control technique, which is implemented by feed-back of the ultrasonic transducer applied voltage and instantaneous velocity of the transducer vibrating system through a Phase-Locked-Loop control scheme. The feedback voltage corresponding to instantaneous velocity is averaged over a half-period with respect to constant amplitude/constant velocity control strategy. Described are the theory of this signal detection technique and the experimental set-up.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.6-13
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• 2009

For X-band phased array systems, a power amplifier, a 6-bit phase shifter, a 6-bit digital attenuator, and a SPDT transmit/receive (T/R) switch are fabricated and measured. All circuits are demonstrated by using CMOS 0.18 um technology. The power amplifier has 2-stage differential and cascade structures. It provides 1-dB gain-compressed output power ($P_{1dB}$) of 20 dBm and power-added-efficiency (PAE) of 19 % at 8-11 GHz frequencies. The 6-bit phase shifter utilizes embedded switched filter structure which consists of nMOS transistors as a switch and meandered microstrip lines for desired inductances. It has $360^{\circ}$ phase-control range and $5.6^{\circ}$ phase resolution. At 8-11 GHz frequencies, it has RMS phase and amplitude errors are below $5^{\circ}$ and 0.8 dB, and insertion loss of $-15.7\;{\pm}\;1,1\;dB$. The 6-bit digital attenuator is comprised of embedded switched Pi-and T-type attenuators resistive networks and nMOS switches and employes compensation circuits for low insertion phase variation. It has max. attenuation of 31.5 dB and 0.5 dB amplitude resolution. Its RMS amplitude and phase errors are below 0.4 dB and $2^{\circ}$ at 8-11 GHz frequencies, and insertion loss is $-10.5\;{\pm}\;0.8\;dB$. The SPDT T/R switch has series and shunt transistor pairs on transmit and receive path, and only one inductance to reduce chip area. It shows insertion loss of -1.5 dB, return loss below -15 dB, and isolation about -30 dB. The fabricated chip areas are $1.28\;mm^2$, $1.9mm^2$, $0.34\;mm^2$, $0.02mm^2$, respectively.

• Tribology and Lubricants
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• v.14 no.3
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• pp.24-31
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• 1998

A new type squeeze film damper is proposed and its dynamic characteristics are investigated experimentally. The new one has a pulsating flow supply system which properly adds high pressure oil to the oil film of the damper so that the rotor vibration can be controlled actively. As the result, the amplitude of the rotor vibration can be reduced considerably. The algorithm which compensates the phase lag of servo valve as well as the high-performance servo valve are required in order that a new type squeeze film damper can be more effective device to attenuate the rotor vibration than typical one.