• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1542-1547
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• 2007

Laser surface treatment technologies have been used to improve characteristics of wear and to enhance the fatigue resistance for mold parts. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with a uniform hardness. The objective of this research work is to investigate the influence of the process parameters, such as power of laser and defocused spot position, on the characteristics of laser surface treatment for the case of SKD61 steel and SCM4 steel. From the results of the experiments, it has been shown that the maximum average hardness is approximatly 700${\sim}$780 Hv when the power, focal position and the travel of laser are 1,095 W, 0mm and 0.3 m/min, respectively. In samples treated with lower scanning speeds, some small carbide particles appear in the interdendritic regions. This region contains fine martensite and carbide in proportions which depend on the local thermal cycle.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.113-113
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• 1998

C CdTe와 HgCdTe는 광전소자나 태양전지,x 선 및 y 선 감지 소자 그리고 적외선 감지소 자로의 웅용둥으로 인하여 많은 연구가 진행되고 있다. 광전소자를 제작함에 있어서 깊은 준위나 얄은 준위에 있는 몇들은 운반자 수명에 매우 큰 영향을 미치고 있음에도 불구하고 광전도도 측정에 의한 운반자 수명 연구에 대하여는 보고된 것이 별로 없다. 이에 본 논문에서는 CdTe 시료의 광전도도를 측정하여 운반자 수명 및 깊은 준위의 위치를 알아보았다 M MBE방법을 이용하여 CdTe 기판위에 In을 도핑한 CdTe를 성장하였다. 광전도 붕괴(PCD) 측정은 300 K에서부터 400 K까지 온도를 변화시켜주면서 측정을 하였고 광원으로서 G GaP- LED를 사용하였으며 전압 신호를 읽기 위하여 Tektronix 2430A 오실로스코프를 이용하 였다 .. Fig. 1. 에서 보인바와 같이 광전도 붕괴곡선은 접선으로 나타낸 하나의 지수 함수적 붕 괴(a2exp( -t/ r 2))보다는 설선으로 나타낸 두 개의 지수함수적 붕괴(alexp( νr 1)+a2exp( -νr 2)) 가 더욱 잘 실험결과와 일치함을 알 수 있었다. 이러한 것은 과잉 전하에 대한 깊은준위를 가 지고 있는 반도체물질에서 일반적으로 관찰되는 것으로 시료가 n 형이기 때문에 소수 운반자 인 정공의 벚에 의한 것으로 생각된다 .. Fig. 2. 에서는 운반자 수명의 온도에 대한 변화를 나타 낸 것이다. 온도가 증가함에 따라 운반자 수명이 감소하는 경항올 보이고 있으며 이것올 이용 하여 딪익 활성화 에너지를 계산 하여 본 결과 0.35 eV 와 0.43 eV염을 알수 있었다.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.4 s.193
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• pp.57-67
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• 2007

Laser surface hardening technologies have been used to improve characteristics of wear and to enhance the fatigue resistance fur mold parts. The objective of this research work is to investigate the influence of the process parameters, such as power of laser and defocused spot position, on the characteristics of laser surface hardening for the case of SKD61 steel. CW Nd:YAG laser is selected as the heat source. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with a uniform hardness. From the results of the experiments, it has been shown that the maximum average hardness is approximatly 780 Hv when the power, focal position and the travel of laser are 1,095 W, 0mm and 0.3 m/min, respectively. In samples treated with lower scanning speeds, some small carbide particles appear in the interdendritic regions. This region contains fine martensite and carbide in proportions which depend on the local thermal cycle.

• 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 Sensor Science and Technology
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• v.16 no.6
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• pp.475-483
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• 2007

This paper proposes a readout integrated circuit (ROIC) for $32{\times}32$ infrared focal plane array (IRFPA) detector, which consist of reference resistor, detector resistor, reset switch, integrated capacitor and operational amplifier. Proposed ROIC is designed using $0.35{\;}{\mu}m$ 2P-4M (double poly four metal) n-well CMOS process parameters. Low noise folded cascode operational amplifier which is a key element in the ROIC showed 12.8 MHz unity-gain bandwidth and open-gain 89 dB, phase margin $67^{\circ}$, SNR 82 dB. From proposed circuit, we gained output voltage variation ${\Delta}17{\};mV/^{\circ}C$ when the detector resistor varied according to the temperature.

• 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.

• Journal of Ocean Engineering and Technology
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• v.28 no.3
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• pp.254-259
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• 2014

The infrared signature of a ship is largely influenced by the ocean environment of the operating area, which has been known to cause large changes in the signature. As a result, the weather condition has to be clearly set for an analysis of the infrared signatures. It is necessary to analyze meteorological data for all the oceans where the ship is supposed to be operated. This is impossibly costly and time consuming because of the huge size of the data. Therefore, the creation of a standard environmental variable for an infrared signature research is necessary. In this study, we compared and analyzed sampling methods to represent ocean data close to the Korean peninsula. In order to perform this research, we collected ocean meteorological records from KMA (Korea Meteorological Administration), and sampled these in numerous ways considering five variables that are known to affect the infrared signature. Specifically, a simple random sampling method for all the data and 1-D, 2-D, and 3-D stratified sampling methods were compared and analyzed by considering the mean square errors for each method.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.1
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• pp.108-114
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• 2014

This paper describes a method to set an intensity-based initial validation gate for tracking filter while preserves the ability of tracking a target with maximum speed. First, we collected real data set of signal versus distance of an airplane target. And at each data point, we computed maximum distance the target can move. And a function is modeled to expect the maximum moving pixels on the lateral direction based on the intensity of the detected target in IR image sequence. The initial prediction error covariance can be computed using this function to decide the size of the initial validation gate. The simulation results show the proposed method can set the appropriate initial validation gates to track the targets with the maximum speed.

• Journal of Convergence for Information Technology
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• v.9 no.3
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• pp.30-35
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• 2019

An unattended recording system based on smartphone based image image tracking is rapidly developing. Among the existing products, a system that automatically tracks and rotates the object to be photographed using an infrared signal is very expensive for general users. Therefore, this paper proposes a mobile unattended recording system that enables automatic recording by anyone who uses a smartphone. The system consists of a commercial mobile camera, a servomotor that moves the camera from side to side, a microcontroller to control the motor, and a commercial wireless Bluetooth Earset for video audio input. In this paper, we designed a system that enables unattended recording through image tracking using smartphone.