• 센서학회지
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• 제15권4호
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• pp.277-283
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• 2006

We presented that fabrication process and characteristics of 3 axes flexible tactile sensor available for normal and shear force fabricated using Si micromachining and packaging technologies. The fabrication processes for 3 axes flexible tactile sensor were classified in the fabrication of sensor chips and their packaging on the flexible PCB. The variation rate of resistance was about 2.1 %/N and 0.5 %/N in applying normal and shear force, respectively. The flexibility of fabricated 3 axes flexible tactile sensor array was good enough to place on the finger-tip.

• 센서학회지
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• 제18권5호
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• pp.377-384
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• 2009

The ultrasonic hyperthermia for oncology has been developed and studied. The HIFU(high intensity focused ultrasound) is the most recent method to treat the tumor by using ultrasound. In this study, an insertion-type transducer for treating a prostate cancer, which can focus the ultrasonic beam mechanically and electrically, was designed and developed. The developed transducer was composed of three arrays, and each array has 32 elements. For the purpose of the mechanical focusing, both side arrays are slanted to the center array by $15^{\circ}$. With this structure, NFL(near field length) was set up as 30 mm. The PZT-4 and two matching layers were used, and the backing layer was excepted to prevent energy losses. The acoustic field analysis and the heating test were performed to evaluate the performance of developed transducer. The shape of an acoustic field, peak pressure, and acoustic pressure distribution were compared with numerical simulation. The NFL was 32 mm, the beam width was 5 mm, focal area was $40\;mm^2$, and peak pressure was 5.5 MPa. With heating by using developed transducer, the temperature increased up to $33^{\circ}C$ at focal zone. As a result of this study, the usefulness of suggested transducer for prostate cancer hyperthermia was confirmed by the acoustic field analysis and the heating test with TMM(tissue mimicking) phantom.

• 한국조명전기설비학회지:조명전기설비
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• 제10권4호
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• pp.78-84
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• 1996

본 논문에서는 초음파센서 배열과 신경회로망 및 불변모멘트 벡터를 이용하여 물체의 위치이동에 무관한 3차원 물체인식과 복원을 연구함으로서 추차관리 시스템의 차종인식 응용가능성에 대하여 검토하였다. 초음파센서 배열로부터 얻어진 16$\times$8 픽셀의 데이터를 이용하여 물체의 불변모멘트 벡터를 계산하고 이를 SCL(Simple Competitive Leverning)신경회로망에 입력하여 3차원 물체를 분류하였으며, 저해상도인 16$\times$8 픽셀의 물체정보를 SCL 수정형 신경회로망에 입력하여 32$\times$32 픽셀로 해상도를 향상시켜 3차원 물체복원을 하였다. 물체의 위치가 변하여도 불변모멘트 벡터는 일정한 값을 유지하였고, 학습 후 인식율은 학습데이터의 경우는98[%]이고 시험데이터의 경우 95[%]이었으며, 3차원 32$\times$32 픽셀의 고해상도 물체정보로 복원하였다. 실험결과로부터 신경회로망과 연계된 초음파 센서는 차량의 감지뿐만 아니라 차종의 구분에도 응용가능할 것으로 생각된다.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3790-3797
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• 2021

Although the individual channel readout method can improve the performance of PET detectors with pixelated photo-sensors, such as silicon photomultiplier (SiPM), this method leads to a significant increase in the number of readout channels. In this study, we proposed a novel multiplexing method that could effectively reduce the number of readout channels to reduce system complexity and development cost. The proposed multiplexing circuit was designed to generate bipolar pulses with different zero-crossing points by adjusting the time constant of the high-pass filter connected to each channel of a pixelated photo-sensor. The channel position of the detected gamma-ray was identified by estimating the width between the rising edge and the zero-crossing point of the bipolar pulse. In order to evaluate the performance of the proposed multiplexing circuit, four detector blocks, each consisting of a 4 × 4 array of 3 mm × 3 mm × 20 mm LYSO and a 4 × 4 SiPM array, were constructed. The average energy resolution was 13.2 ± 1.1% for all 64 crystal pixels and each pixel position was accurately identified. A coincidence timing resolution was 580 ± 12 ps. The experimental results indicated that the novel multiplexing method proposed in this study is able to effectively reduce the number of readout channels while maintaining accurate position identification with good energy and timing performance. In addition, it could be useful for the development of PET systems consisting of a large number of pixelated detectors.

• 한국군사과학기술학회지
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• 제24권1호
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• pp.50-60
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• 2021

For conventional AESA radars, DC-DC power modules using 300 Vdc have low efficiency, high volume, heavy weight, and high price, which have problems in modularity with T/R module groups. In this paper, to improve these problems, we propose a distributed DC-DC power module with high-voltage 800 Vdc and high-efficiency Step-down Converter. In particular, power requirements for modern and future marine weapons systems and sensors are rapidly evolving into high-energy and high-voltage power systems. The power distribution of the next generation Navy AESA radar antenna is under development with 1000 Vdc. In this paper, the proposed highvoltage, high-efficiency DC-DC power modules increase space(size), weight, power and cooling(SWaP-C) margins, reduce integration costs/risk, and reduce maintenance costs. Reduced system weight and higher reliability are achieved in navy and ground AESA systems. In addition, the proposed architecture will be easier to scale with larger shipboard radars and applicable to other platforms.

• 한국항행학회논문지
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• 제26권2호
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• pp.78-84
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• 2022

본 논문에서는 다중 신호원이 존재하는 경우에 닫힌 형태 기반의 3차원 위치 추정 기법을 제안한다. TDOA나 AOA, FDOA와 같은 일반적인 위치 추정 기술은 단일 신호원이 존재하는 경우에 위치를 추정할 수 있으며, 미상의 다중 신호원이 존재하는 경우에 이를 구분하여 위치를 추정하는데 한계가 있다. 제안된 기법은 배열 안테나를 갖는 센서에 수신된 신호의 상호상관 벡터를 계산하고, 상호상관 값으로부터 TDOA값과 AOA값을 추정한다. 그리고 기준 센서의 위치를 이용하여 좌표 변환을 수행하고, 변환된 좌표에 대해 추정된 AOA값을 이용하여 좌표 회전을 수행한 후 각 신호원에 대한 3차원 위치를 추정한다. 제안된 기법은 컴퓨터 모의실험을 통해 그 성능을 검증한다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.639-641
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• 2022

사회적으로 고령화 문제가 심화되면서, 독거노인 모니터링 시스템에 관한 연구가 활발히 진행되고 있다. 일반적으로 모니터링 시스템은 영상, 센서, 계측값 등의 정보를 바탕으로 서버에서 연산을 수행하여, 사용자에게 모니터링 서비스를 제공한다. 서버를 이용하는 시스템의 구조상 데이터 유출의 위험이 존재하며, 데이터 보안을 고려한 설계가 필수적이다. 본 논문에서는 영상보안 구조 기반의 지능형 독거노인 모니터링 시스템을 제안한다. 제안하는 시스템은 Edge AI 모듈을 사용하여 카메라 모듈과 서버 간의 통신을 차단하는 구조를 통해 높은 보안성을 보장한다. Edge AI 모듈은 Verilog HDL로 설계되었으며, Field Programmable Gate Array (FPGA)를 통해 기능을 구현하였다. 본 시스템을 검증하기 위해 5,144개의 프레임 데이터에 대해 실험하였으며, 사람의 움직임이 일정 시간 감지되지 않았을 때 위험 감지 신호가 올바르게 발생하는 것을 확인하였다.

• 한국전자통신학회논문지
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• 제18권6호
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• pp.1245-1258
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• 2023

산림자원의 효율적인 관리를 위한 정보획득을 위해서는 서로 다른 센서를 장착한 다수의 무인항공기가 동시에 운영되어야 한다. 이에 따라 지상제어국 안테나는 지속적으로 대국에 대한 추적을 수행해야 할 뿐만 아니라 타 무인항공기에 대한 전파간섭 영향을 억제해야 한다. 본 논문에서는 위상배열안테나 시스템을 기반으로 구축된 지상제어국에 있어, VPR 알고리즘을 기반으로 지속적인 추적 및 전파간섭 억제를 위한 빔 형성 기법에 관하여 연구하였다. 다양한 무인항공기 운영 환경에 대한 모의실험 결과, 제시된 기법을 기반으로 운항중인 무인항공국에 대한 지속적인 추적을 할 수 있을 뿐만 아니라, 다수의 전파간섭원에 대해 지속적인 패턴 널을 형성하여 전파간섭을 억제할 수 있음을 확인하였다.

• 센서학회지
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• 제27권2호
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• pp.93-98
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• 2018

In this paper, an energy-efficient 11.49-bit successive approximation register (SAR) capacitance-to-digital converter (CDC) for capacitive sensors with a figure of merit (FoM) of 31.6 pJ/conversion-step is presented. The CDC employs a SAR algorithm to obtain low power consumption and a simplified structure. The proposed circuit uses a capacitive sensing amplifier (CSA) and a dynamic latch comparator to achieve parasitic capacitance-insensitive operation. The CSA adopts a correlated double sampling (CDS) technique to reduce flicker (1/f) noise to achieve low-noise characteristics. The SAR algorithm is implemented in dual operating mode, using an 8-bit coarse programmable capacitor array in the capacitance-domain and an 8-bit R-2R digital-to-analog converter (DAC) in the charge-domain. The proposed CDC achieves a wide input capacitance range of 29.4 pF and a high resolution of 0.449 fF. The CDC is fabricated in a $0.18-{\mu}m$ 1P6M complementary metal-oxide-semiconductor (CMOS) process with an active area of 0.55 mm2. The total power consumption of the CDC is $86.4{\mu}W$ with a 1.8-V supply. The SAR CDC achieves a measured 11.49-bit resolution within a conversion time of 1.025 ms and an energy-efficiency FoM of 31.6 pJ/step.

• Journal of Biosystems Engineering
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• 제34권5호
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• pp.382-389
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• 2009

An in-situ probe-based spectrophotometer has been developed. This system used two spectrometers to measure soil reflectance spectra from 450 nm to 2200 nm. It collects soil electrical conductivity (EC) and insertion force measurements in addition to the optical data. Six fields in Kansas were mapped with the VIS-NIR (visible-near infrared) probe module and sampled for calibration and validation. Results showed that VIS-NIR correlated well with carbon in all six fields, with RPD (the ratio of standard deviation to root mean square error of prediction) of 1.8 or better, RMSE of 0.14 to 0.22%, and $R^2$ of 0.69 to 0.89. From the investigation of carbon variability within the soil profile and by tillage practice, the 0-5 cm depth in a no-till field contained significantly higher levels of carbon than any other locations. Using the selected calibration model with the soil NIR probe data, a soil profile map of estimated carbon was produced, and it was found that estimated carbon values are highly correlated to the lab values. The array of sensors (VIS-NIR, electrical conductivity, insertion force) used in the probe allowed estimating bulk density, and three of the six fields were satisfactory. The VIS-NIR probe also showed the obtained spectra data were well correlated with nitrogen for all fields with RPD scores of 1.84 or better and coefficient of determination ($R^2$) of 0.7 or higher.