• Journal of Korea Multimedia Society
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• v.9 no.12
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• pp.1669-1680
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• 2006

This paper explains that the RF systems for hi-directional wireless capsule endoscopes were designed and implemented. The designed RF systems for a capsule endoscope can transmit the images of intestines from the inside to the outside of a body and the behavior of the capsules can be controlled by an external controller simultaneously. The hi-directional wireless capsule endoscope consists of a CMOS image sensor, FPGA, LED, battery, DC to DC Converter, transmitter, receiver, and antennas. The transmitter and receiver which were used in the hi-directional capsule endoscope, were designed and fabricated with $10mm(diameter){\times}3.2mm(thickness)$ dimensions taking into the MPE, power consumption, system size, signal to noise ratio and modulation method. The RF systems designed and implemented for the hi-directional wireless capsule endoscopes system were verified by in-vivo experiments. As a result, the RF systems for the hi-directional wireless capsule endoscopes satisfied the design specifications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.753-758
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• 2009

Recently the high-end CMOS image sensors are developed, conforming to the SMIA CCP2 specification, which is a high-speed low-power serial interface based on LVDS technology. But this kind of technology trend makes the existing equipments are no longer useful, although their capability is still good enough to handle the recent image sensors if there was no interfacing problem. In this paper, we propose and realize a data protocol conversion system that translates the SMIA CCP2 serial signals into the existing 10-bit parallel signals. The proposed system is composed of a de-serializer and a FPCA chip, and thus can be constructed on a small PCB which enables easy integration between the existing equipments and the new high-end image sensors. Besides, the maximum transfer rate by the SMIA specification is also achieved on the implemented system. So it is expected that the implemented system can be used as a general-purpose protocol converter in a variety of sensor-related application fields.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.22-28
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• 2001

This paper describes the implementation of a robust speaker position location system using the voice signal received by microphone array. To be robust to the reverberation which is the major factor of the performance degradation, low-frequency phase restoration algorithm which eliminates the influence of reverberations using the low-frequency information of the CPSP function is proposed. The implemented real-time system consists of a general purpose DSP (TMS320C31 of Texas instruments), analog part which contains amplifiers and filters, and digital part which is composed of the external memory and 12-bit A/D converter. In the real conference room environment, the implemented system that was constructed by the proposed algorithms showed better performance than the conventional system. The error of the TDOA estimation reduced more than 15 samples.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.24-27
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• 2016

In this study, a 1kW Solid Oxide Fuel Cell(SOFC) test system was developed. A SOFC is the most promising power system to provide the higher efficient(over 50%) for house application area(1~10kW). To develop the optimized test system, the temperature control module that controls the preprocess and reaction condition, the flow control module that controls of the mass of reactants, and the electric loader that tests the discharge performance condition, etc. The temperature control module was designed to provide the high control resolution(under $1^{\circ}C$ at $750^{\circ}C$ of operating temperature) using K-type thermal couple. The flow control module was designed control blower and heater precisely using the phase control method. And the electric loader is designed that provide CV, CC, CR discharge mode and minimized the operating error adopting the independent DC-DC converter on analog input and output module. The performance of the developed SOFC test system showed that the accuracy of stack voltage was 0.15% at 80V and stack current was 0.1% at 100A.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.2
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• pp.189-197
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• 2014

This work proposes a 12b 100 MS/s $0.11{\mu}m$ CMOS three-step hybrid pipeline ADC for high-speed communication and mobile display systems requiring high resolution, low power, and small size. The first stage based on time-interleaved dual-channel SAR ADCs properly handles the Nyquist-rate input without a dedicated SHA. An input sampling clock for each SAR ADC is synchronized to a reference clock to minimize a sampling-time mismatch between the channels. Only one residue amplifier is employed and shared in the proposed ADC for the first-stage SAR ADCs as well as the MDAC of back-end pipeline stages. The shared amplifier, in particular, reduces performance degradation caused by offset and gain mismatches between two channels of the SAR ADCs. Two separate reference voltages relieve a reference disturbance due to the different operating frequencies of the front-end SAR ADCs and the back-end pipeline stages. The prototype ADC in a $0.11{\mu}m$ CMOS shows the measured DNL and INL within 0.38 LSB and 1.21 LSB, respectively. The ADC occupies an active die area of $1.34mm^2$ and consumes 25.3 mW with a maximum SNDR and SFDR of 60.2 dB and 69.5 dB, respectively, at 1.1 V and 100 MS/s.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.81-86
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• 2016

Background: For positron emission tomography (PET) application, cadmium zinc telluride (CZT) has been investigated by several institutes to replace detectors from a conventional system using photomultipliers or Silicon-photomultipliers (SiPMs). The spatial and energy resolution in using CZT can be superior to current scintillator-based state-of-the-art PET detectors. CZT has been under development for several years at the Korea Atomic Energy Research Institute (KAERI) to provide a high performance gamma ray detection, which needs a single crystallinity, a good uniformity, a high stopping power, and a wide band gap. Materials and Methods: Before applying our own grown CZT detectors in the prototype PET system, we investigated preliminary research with a developed discrete type data acquisition (DAQ) system for coincident events at 128 anode pixels and two common cathodes of two CZT detectors from Redlen. Each detector has a $19.4{\times}19.4{\times}6mm^3$ volume size with a 2.2 mm anode pixel pitch. Discrete amplifiers consist of a preamplifier with a gain of $8mV{\cdot}fC^{-1}$ and noise of 55 equivalent noise charge (ENC), a $CR-RC^4$ shaping amplifier with a $5{\mu}s$ peak time, and an analog-to-digital converter (ADC) driver. The DAQ system has 65 mega-sample per second flash ADC, a self and external trigger, and a USB 3.0 interface. Results and Discussion: Characteristics such as the current-to-voltage curve, energy resolution, and electron mobility life-time products for CZT detectors are investigated. In addition, preliminary results of gamma ray imaging using 511 keV of a $^{22}Na$ gamma ray source were obtained. Conclusion: In this study, the DAQ system with a CZT radiation sensor was successfully developed and a PET image was acquired by two sets of the developed DAQ system.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.6
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• pp.35-41
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• 2000

This paper describes a merged-capacitor switching (MCS) technique to improve the signal Processing speed and resolution of CMOS analog-to-digital converters (ADCs). The proposed MCS technique improves a sampling rate by reducing the number of capacitors used in conventional pipelined ADCs. The ADC capacitor mismatch can be minimized without additional power consumption, die area, and the loss of sampling rate, when the size of each unit capacitor is increased as much as the number of capacitors reduced by the MCS technique. It is verified that the ADC resolution based on the proposed MCS technique is extended further by employing a conventional commutated feedback-capacitor switching (CFCS) technique.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.393-400
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• 2014

In this paper, we have designed the transmitter for earth station terminal operating with military geostationary satellite on Ka-band that is complied with MIL-STD-188-164A. The designed antenna of this terminal is dual-offset gregorian reflector which is consist of corrugated horn and iris polarizer, othermode transducer. This antenna meets radiation pattern and transmit EIRP spectral density requirements in this standard. The designed RF systems of this terminal are consist of Block Up Converter(BUC) converting frequency band from IF to Ka band and SSPA having low-power consumption and compact light-weight using the pHEMT MMIC compound devices. This RF systems applied with VSWR, spurious/harmonic suppression, output flatness and phase noise requirement in this standard.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.190-193
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• 2001

In order to verify the efficiency or availability and stability of photovoltaic(PV) generation systems, huge system apparatuses are needed, in general, in which an actual size of solar panel, a type of converter system and some amount of load facilities should be installed in a particular location. It is also hardly possible to compare a Maximum Power Point Tracking (MPPT) control scheme with others under the same weather and load conditions in an actual PV generation system. The only and a possible way to bring above-mentioned problem to be solved is to realize a transient simulation scheme for PV generation systems using real weather conditions such as insolation and surface temperature of solar cell. The authors, in this paper, introduces a novel simulation method, which is based on a real-time digital simulator (RTDS), for PV generation systems under the real weather conditions. Firstly, VI characteristic equation of a solar cell is developed as an empirical formula and reconstructed in the RTDS system, then the real data of weather conditions are interfaced to the analogue inputs of the RTDS. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation scheme in this paper. The results shows that the cost effective verifying for the efficiency or availability and stability of PV generation systems and the comparison research of various control schemes like MPPT under the same real weather conditions are possible.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.5
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• pp.413-417
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• 2010

Line to ground faults by deterioration of insulators has frequently occurred in power system, and the main cause is surface contamination of the insulators. The contamination of insulator is analyzed by monitoring the surface leakage current flowing them. The suspension insulator is monitored by installation of a zero-phase current sensor(ZCT), but the line-post insulator is impossible to apply the same method because of its large diameter structure. This paper proposed a detection method of surface leakage current for a line-post insulator, and it can easily be applied to new and/or built insulators. The leakage current is indirectly calculated from the potential difference between the metal electrode attached on the surface of insulator and the ground connector. To evaluate the performance of the proposed method, the leakage current is compared as a function of contamination condition controlled by the density of NaCl solution. The leakage current is proportioned to the density of NaCl solution, and the voltage detected by the electrode showed the same trend. From the experimental results, we designed and fabricated a monitoring device which is composed of a detection electrode, signal converter, microprocessor, and ZigBee, and its measurement range is $10{\mu}A{\sim}5mA$.