• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.23-25
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• 2005

Infrared bolometer sensor's variation is detected by voltage drop between reference resistor and bolometer resistor in this architecture. One of the serious problems in this architecture is that these resistors value has a process variation. So common-mode level could be different from expectation in room temperature. Different common-mode level could lead to wrong output at the end of readout circuit. We suggest useful method to solve this problem. Difference correction using capacitor has reduced CM level difference to 86% for 1 $M\Omega$. bolometer and reference resistor's 10% variation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.41-44
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• 2022

Mean-Shift 영상 분할은 객체 검출을 위한 영상 전처리 방법으로써, 영상 처리 및 패턴 인식 분야에서 널리 사용되는 방법이다. 영상 분할은 영역 기반과 에지 기반 방식으로 나누어지며 대표적으로 FCM, Quickshift, Felzenszwalb, SLIC 알고리즘 등 이 있다. 언급한 영상 분할 방법들은 Mean-Shift 영상 분할에 비해서 빠른 속도로 실행시킬 수 있지만, 형태적 특징이 훼손되고 하나의 객체가 여러 세그멘테이션으로 분할된다는 단점을 가지고 있다. 본 논문에서는 소형 객체를 탐지하기 위한 고속화된 Mean-Shift 영상 분할과 객체의 형태적 특징을 이용하여 객체를 탐지하는 방법을 제안한다. 하드웨어 리소스가 제한된 신호처리기에 제안하는 알고리즘을 수행하기 위하여 Mean-Shift 영상 분할에서 필터링 과정을 고속화 하였고, 적외선 영상 내 영상 전처리 수행을 통해 잡음 제거 후 Mean-Shift 영상 분할 방법을 수행함으로써, 객체의 형태적 특징을 잘 살려서 영상 분할을 할 수 있도록 하였다. 또한 각 세그멘테이션의 크기, 너비, 높이, 밝기 정보와 형태적 특징점을 이용한 객체 탐지 방법을 제안한다.

• Composites Research
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• v.25 no.6
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• pp.236-240
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• 2012

The purpose of this study was to investigate the feasibility on the detection of dental composite delamination using a lock-in thermography method. Amplitude and phase images of detected thermal signals were analyzed according to the lock-in frequencies. At a lock-in frequency of 0.05 Hz, the ligament thickness of 0.5 mm in the specimen exhibited the highest amplitude contrast between defective area and sound area. For ligament thicknesses of 1 mm and 1.5 mm, delamination detection was possible at 0.025 Hz and 0.01 Hz through the amplitude differences. At lock-in frequencies of 0.006 Hz and 0.01 Hz, ligament thickness 0.5 mm exhibited the highest phase contrast. For ligament thicknesses of 1 mm and 1.5 mm, the phase contrast exhibited possible detection of delamination at 0.006-0.1 Hz.

• Journal of Sensor Science and Technology
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• v.12 no.4
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• pp.185-190
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• 2003

Recently, sensors which use the infrared light, supersonic waves, and electromagnetic waves have been used for many applications to detect information of the object. For these sensors, the accompanying system which utilizes the sensor should be systematically developed. In this paper, a general microwave radar sensor system is briefly described, and then basic applications of a CW doppler radar sensor system are introduced. For the CW doppler radar sensor applications, a highly-stable, low-cost Dielectric Resonator Oscillator (DRO) has also been designed and implemented, which can be used for commercial microwave sensor systems. The implemented DRO has output power of +5.33 dBm at 12.67 GHz and phase noise of -108.5 dBc/Hz at the 100 kHz offset frequency.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.417-422
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• 2014

A guitar pickup is a transducer that converts string vibration to an electrical signal. The magnetic and piezo pickups are the most commonly used for the respective electric and electroacoustic guitars. The magnetic pickups are prone to magnetic interference between the steel strings and permanent magnets, while the piezo ones are not free from signal inference between the strings. Thus, this paper presents the development of an optical pickup for the electroacoustic guitar. The proposed optical pickup has the top-to-bottom structure. It uses two of Infrared (IR) Light Emitting Diode (LED) and one photodetector. The developed optical pickup is subjected to the evaluation with commonly used piezoelectric pickup. It becomes obvious that SNR with the optical pickup is increased by 45 percent in average, compared with the piezoelectric pickup. It can be concluded that the developed optical pickup has a potential to be applied to the acoustic guitar.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.3
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• pp.11-16
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• 2000

In this paper, a real-time implementation of scene-based non-uniformity correction by digital technique is proposed for microscan-mode staring infrared cameras. Most scene-based non-uniformity correction algorithms, without sensor motion, can not be applied to stationary scenes because of image blurring and fading. Using microscanning effect, coupled with a modified version of Scribner's algorithm, the proposed technique can correct the artifacts and non-uniformities in real time Computer simulations and hardware experiments demonstrate substantial Improvement of image qualities in stationary as well as moving scenes.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.205-205
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• 2013

테라헤르쯔(terahertz: THz)파는 0.1~10 THz 의 범위로 적외선과 방송파 사이에 광대역 주파수 스펙트럼을 차지하고 있으며 직진성, 투과성, 그리고 낮은 에너지 (meV)를 가지고 있어 비 파괴적이고 무해한 장점을 지니고 있다. Ti:sapphire laser와 같은 femto-pulse source 등이 많은 발전이 되어 현재 많은 연구와 발전이 이루어지고 있다. femto-pulse source를 이용한 THz 응용에서는 높은 저항, 큰 전자 이동도, 그리고 아주 짧은 전하수명의 기판을 요구하는데 저온에서 성장한 (low-temperature grown : LT) GaAs는 격자 내에 Gallium 자리에 Arsenic이 치환 하면서 AsGa antisite가 발생하여 전하수명을 짧아지는 것을 응용하여 가장 많이 이용되고 있다. 현재 THz 응용분야에서 보다 작고 가격경쟁력이 있는 광통신을 이용한 THz photomixer등이 활발히 연구 하고 있다. 광섬유 내에서 손실과 분산이 최소값을 가지는 부분이 1.55 ${\mu}m$ 부근이고 In0.53Ga0.47As 기판을 이용하였을 때 여기에 완벽하게 만족하게 된다. 하지만 LT-InGaAs 의 경우 AsGa antisite로 인하여 carrier lifetime은 짧아지지만 높은 n-type 전하밀도를 가지게 된다. 이때 Be을 doping하여 전하밀도를 보상하여 높은 저항을 유지해야 하는데 Be의 활성화를 위해서는 열처리를 필요로 한다. 하지만 열처리를 하면 carrier lifetime이 길어지기 때문에 carrier lifetime과 저항을 적절히 조율해야 한다. 이는 물질자체의 특성이기 때문에 InGaAs는 GaAs보다 낮은 amplitude와 짧은 cut-off frequency를 가진다. 본 연구에서는 보다 높은 저항을 얻기 위하여 molecular beam epitaxy를 이용하여 semi-insulating InP:Fe 기판위에 격자 정합된 InGaAs:Be/InAlAs multi quantum well (MQW)를 온도별 ($250{\sim}400^{\circ}C$), 주기별 (50~150)로 성장을 하였고 이때 InGaAs layer의 Be doping level은 $2{\times}1018\;cm^{-3}$, Ex-situ annealing은 $550^{\circ}C$에서 10분으로 고정 하였다. THz 발생 실험에서는 InGaAs/InAlAs MQW은 4000 pA로 1,000 pA를 가지는 InGaAs epilayer보다 4배 높은 전류 신호를 얻을 수 있었고 모든 샘플이 2 THz에서 cut-off frequency를 가지고 있었다. THz 검출 실험에서는 LT-InGaAs:Be epilayer LT-InGaAs:Be/InAlAs, HT-InGaAs/InAlAs 샘플이 각각 180, 9000, 12000 pA의 전류신호를 가지고 있었고 모든 샘플이 2 THz에서 cut-off frequency를 가지고 있었다. HT-InGaAs/InAlAs MQW를 이용한 검출실험에서는 InGaAs layer가 defect free이지만 LT-InGaAs:Be/ InAlAs MQW 보다 높은 전류 신호를 얻을 수 있었다. 이는 InAlAs layer가 저항만 높이는 것뿐만 아니라 carrier trapping layer로써의 역할도 하는 것으로 사료된다.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.163-167
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• 2016

We have developed a millimeter-wave radiometer system for applications in the fields of medical imaging. In this paper, we introduced the brightness temperature measurement in the human body using Millimeter-wave Radiometer. Calibration of sensitivity of the radiometer system is essential to measure equivalent temperature (brightness temperature) of objects. We have developed, as a calibration source, a new type of black body for the millimeter wave region with temperature control capability. The system noise figure and temperature sensitivity of the system measured using the blackbody are 3.3 dB and 0.1 K, respectively. The brightness temperature of human body through clothes was measured to be around $38^{\circ}$[C].

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.94-101
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• 2009

In this paper, we propose design of hardware based on a high speed digital signal processor (DSP) and a field programmable gate array (FPGA) for real-time suppression of fixed pattern noise (FPN) using hardware neural networks (HNN) in cooled infrared focal plane array (IRFPA) imaging system FPN appears a limited operation by temperature in observable images which applies to non-uniformity correction for infrared detector. These have very important problems because it happen serious problem for other applications as well as degradation for image quality in our system Signal processing architecture for our system operates reference gain and offset values using three tables for low, normal, and high temperatures. Proposed method creates virtual tables to separate for overlapping region in three offset tables. We also choose an optimum tenn of temperature which controls weighted values of HNN using mean values of pixels in three regions. This operates gain and offset tables for low, normal, and high temperatures from mean values of pixels and it recursively don't have to do an offset compensation in operation of our system Based on experimental results, proposed method showed improved quality of image which suppressed FPN by change of temperature distribution from an observational image in real-time system.

• Korean Journal of Optics and Photonics
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• v.21 no.4
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• pp.133-138
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• 2010

All radiation thermometers have a size-of-source effect (SSE) and a self-radiation effect (SRE). The SSE,defined as dependence of the detector signal of a radiation thermometer on the diameter of a source, is critically dependent on the wavelength since diffraction is the main cause. In this paper, we have measured the SSE and the SRE of TRT2 (Transfer Radiation Thermometer 2, HEITRONICS) widely used as a transfer standard in low and middle temperature range. At $300^{\circ}C$, The radiation temperature difference between the 60 mm diameter blackbody and 10 mm diameter blackbody due to the SSE was estimated to be $3.5^{\circ}C$ in low temperature mode ($8-14\;{\mu}m$) and $0.5^{\circ}C$ in middle temperature mode ($3.9\;{\mu}m$). In addition, the measured radiation temperature difference of the blackbody due to the SRE was found to be 110 mK when the body temperature change of TRT2 was set at $2.6^{\circ}C$.