• International Journal of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.330-338
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• 2024

In this paper, a Ka-band high-output active phased array antenna device applicable to small radars and seekers was designed, and the improved performance was studied. The radiation device assembly consists of 1x8 arrangements, and the step flared notch antenna type. It shows low active reflection loss characteristics in broadband, and low loss characteristics by applying the air-strip feeding structure, and is designed to enable beam steering up to 45 degrees. The TRM(transmit receive module) output power is more than 2.0W per channel using GaN HPA in the transmitting path, and satisfies more than 25.0 dB gain and less than 6.0 dB noise figure in the receiving path. Accordingly, the Effective Isotropically Radiated Power(EIRP) of the antenna unit shows the performance of 0.00 dB or more and the receive gain-to-noise temperature ratio(G/T) of 0.00 dB/k or more. For demonstration, we have designed aforementioned planar array antenna which consists of 64 radiating elements having a size within 130 mm x 130 mm x 300 mm and weight of less than 4.9 kg..

• Journal of Biosystems Engineering
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• v.23 no.1
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• pp.83-90
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• 1998

In this paper the automatic system for dairy cattle has been desisted such as body temperature measuring unit, feed supplying unit and temperature control unit. Since e disease is strongly related to the body temperature of cattle, early detection of the abnormal temperature would prevent the severe problems which nay occur in dairy farms. An electronic component AD590J is used as temperature sensor for the system, The device is highly robust against the noise since the output signal is the current so it can be applied to a long distance sensing The resolution of signal is 0.1$^{\circ}C$ and the current is 10㎷ Also 12-bit A/D converter is desisted fir interfacing the sensor with a one-chip microprocessor. A temperature measuring experiment using the developed system has been done for measuring the temperature of human beings and the system was proven to be useful for measuring the body temperature of dairy cattle properly. A geared AC motor is used for the feed supplying unit The heater and fm are used as temperature control unit. The feed supplying unit and temperature control unit are well operating in the laboratory experiment.

• Journal of Power Electronics
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• v.18 no.1
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• pp.266-276
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• 2018

This paper presents a new step-up and step-down multi-pulse auto-transformer rectifier unit (ATRU) topology. This structure can achieve a wide range of output voltages, which solves the problem of auto-transformer output voltage being difficult to regulate. Adding middle taps to the primary winding and reasonably setting the number of auto-transformer windings, constituted two groups of three-phase output voltages with a $30^{\circ}$ phase difference. Multi-pulse output DC voltage is obtained after a three-phase output voltage across two rectifier bridges and inter-phase reactor. Thus, the output DC voltage is related to the number and configuration of the auto-transformer winding. In this paper, the relationship between the voltage ratio of the auto-transformer and the ratio of winding, input current and auto-transformer kilovoltampere rating are deduced and validated by simulations. On this basis, the output voltage range is optimized. An experiment on two different voltage ratio principle prototypes was carried out to verify the correctness of the analysis design.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.267-271
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• 2012

In this paper a power management unit for solar energy harvesting is proposed. If solar energy is sufficient, Power Management Unit(PMU) directly supplies load with solar energy. By contrast, if solar energy is insufficient to operate sensor nodes, voltage booster(VB) boosts the solar cell's output voltage, and then PMU supplies load with the harvested energy. The designed circuit had been fabricated using a 018um CMOS process. In the first case, the PMU supplies load with more energy than in the second case. In the second case where a VB is used, the PMU operates to supply load with solar energy even when illumination is low and minimum solar cells with very low output voltage are used.

• Journal of IKEEE
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• v.25 no.1
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• pp.156-167
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• 2021

In this paper, we propose a digital transceiver unit design for in-building of 5G optical repeaters that extends the coverage of 5G mobile communication network services and connects to a stable wireless network in a building. The digital transceiver unit for driving the proposed 5G optical repeater is composed of 4 blocks: a signal processing unit, an RF transceiver unit, an optical input/output unit, and a clock generation unit. The signal processing unit plays an important role, such as a combination of a basic operation of the CPRI interface, a 4-channel antenna signal, and response to external control commands. It also transmits and receives high-quality IQ data through the JESD204B interface. CFR and DPD blocks operate to protect the power amplifier. The RF transmitter/receiver converts the RF signal received from the antenna to AD, is transmitted to the signal processing unit through the JESD204B interface, and DA converts the digital signal transmitted from the signal processing unit to the JESD204B interface and transmits the RF signal to the antenna. The optical input/output unit converts an electric signal into an optical signal and transmits it, and converts the optical signal into an electric signal and receives it. The clock generator suppresses jitter of the synchronous clock supplied from the CPRI interface of the optical input/output unit, and supplies a stable synchronous clock to the signal processing unit and the RF transceiver. Before CPRI connection, a local clock is supplied to operate in a CPRI connection ready state. XCZU9CG-2FFVC900I of Xilinx's MPSoC series was used to evaluate the accuracy of the digital transceiver unit for driving the 5G optical repeater proposed in this paper, and Vivado 2018.3 was used as the design tool. The 5G optical repeater digital transceiver unit proposed in this paper converts the 5G RF signal input to the ADC into digital and transmits it to the JIG through CPRI and outputs the downlink data signal received from the JIG through the CPRI to the DAC. And evaluated the performance. The experimental results showed that flatness, Return Loss, Channel Power, ACLR, EVM, Frequency Error, etc. exceeded the target set value.

• Journal of The Korea Institute of Healthcare Architecture
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• v.12 no.2
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• pp.69-77
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• 2006

Angiography means that a check up to know an abnormal condition in all the blood vessels include from the heart, aortae, cerobrovascular and abdonominal artery to hands and feet. Main examples of this are cerebral angiography, abdominal, liver for urinary anomaly, renovascular angiography, and artery and vein in arms and legs. Angiography uses radial rays or angiography equipment for an image output during interventional procedure and compositive diagnosis. The acts which performed in a projection room have changed drastically. In general, it is performed by using equipment which is attached one or two C-arms and the method of inserting catheter in vein after anesthesia. For this reason, some rooms that consist of angiography room units should be planned not only for expensiveness equipment and facilities also to be germ-free. Nowadays, in the angiography unit case, it is placed independently as the central part of many hospitals. It does not belong to the imaging medical department any more as considering raising filming times and the relation between C.C.U.(coronary care unit) and operation unit. This means the acts performed are diversified and well-organized rooms in support of diagnosis are required. However, it is difficult to plan the angiography room unit due to domestic researches and data on this unit are not enough. Therefore, this study aims at bringing up basic issue for architectural planning of the angiography unit in general hospital.

• Journal of Digital Convergence
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• v.10 no.4
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• pp.37-43
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• 2012

LED TV integration test unit are the equipment for testing LED BLU as LED BLU's operation, error check, AGING work. The previous test unit were inconvenient because it must change test unit in production line according to LCD's kind and size. This paper develops by integration style test unit that can accommodate various LED TV BLU model of 32 ~ 52 inch that is not one LED TV BLU model. We make that output current is various to dimension of 80 ~ 215 mA. We make functions that are LED BLU state check, Diming and heat occurrence mitigation. Also we develop firmware program and that the program can be upgraded and that can support new panel.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.577-580
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• 2014

In this paper an auto-switching dual-input energy harvesting circuit is proposed. Since the maximum power points of a thermoelectric generator(TEG) output and a vibration device(PEG) output is 1/2 of their open-circuit voltage, an identical MPPT controller can be used for both energy sources. The proposed circuit monitors the outputs of the TEG and PEG, and chooses the energy source generating a higher output using an auto-switching controller, and then harvests the maximum power from the selected device using a MPPT controller. The harvested energy is boosted through a charge pump and stored in a storage capacitor. The stored energy is provided to a load through a PMU(Power Management Unit). The proposed circuit is designed in a $0.35{\mu}m$ CMOS process and its functionality has been verified through extensive simulations. The designed chip occupies $1.4mm{\times}1.2mm$ including pads.

• Journal of Sensor Science and Technology
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• v.28 no.2
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• pp.71-75
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• 2019

This paper proposes the extension of the dynamic range in complementary metal oxide semiconductor (CMOS) image sensors (CIS) using switching operation of in-pixel inverter. A CMOS inverter is integrated in each unit pixel of the proposed CIS for switching operations. The n+/p-substrate photodiode junction capacitances are added to each unit pixel. When the output voltage of the photodiode is less than half of the power supply voltage of the CMOS inverter, the output voltage of the CMOS inverter changes from 0 V to the power supply voltage. Hence, the output voltage of the CMOS inverter is adjusted by changing the supply voltage of the CMOS inverter. Thus, the switching point is adjusted according to light intensity when the supply voltage of the CMOS inverter changes. Switching operations are then performed because the CMOS inverter is integrated with in each unit pixel. The proposed CIS is composed of a pixel array, multiplexers, shift registers, and biasing circuits. The size of the proposed pixel is $10{\mu}m{\times}10{\mu}m$. The number of pixels is $150(H){\times}220(V)$. The proposed CIS was fabricated using a $0.18{\mu}m$ 1-poly 6-metal CMOS standard process and its characteristics were experimentally analyzed.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.255-258
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• 2001

This paper proposes a new structure of a fiber-optic illuminator using high Lux RGB LEDs. A simulation program, LightTools, is used for the verification of the model. An LED mounting holder containing 74 RGB LEDs is used as a basic part of its light collector. Since the light output level of current LED lamps is still far below that of conventional lamps, it is required to double the right output in order to replace a conventional illuminator with a halogen lamp. An additional cone-type reflector is installed hemispherically and the resulting structure comprises a basic collector unit. To further increase the output two collector units are connected together in series. As the result, the light output increases nearly 70% with compared to a collector with a basic structure. The system efficiency can be increased more than 8 times with compared to conventional one.