• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.1 s.307
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• pp.1-6
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• 2006

The noncontact optical sensor using the hologram laser and automatic power controller is developed to measure a thickness of transparent objects and achieve excellent performance. Due to the contact between the tip of the sensor and the surface of objects, the tip is abraded. In addition the casting glass under high temperature results in extending the size of sensor body. The accuracy of the sensor is degraded due to these reasons. In this paper, to overcome these problems, we proposed a low cost non-contact optical sensor that is composed of a hologram laser unit used for optical pickup of CD player and a plastic lens. Therefore the problems caused by the contact sensor are solved by using the noncontact sensor. The noncontact sensor has to move toward the objects and obtain the focus error signal to measure a position of transparent objects. While the internal temperature of the sensor is controlled under ${\pm}0.1^{\circ}$, many trials shows ${\pm}2{\mu}m$ measurement error as excellent performance.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.4
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• pp.299-304
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• 2007

There are to be some cracks on the material degradation part or the stress concentration parts of the main members, which carry on over-loads, of structures. Because these cracks can be used to evaluate the structural health status, it is important to monitor the crack growth for maintaining the structural safety. In this study, the fiber Bragg grating sensor with a drop ball was developed as a sensor for crack growth detection of an existing crack. The crack growth detection sensor was constructed with three parts: a probe part, a wavelength controling light source and receiver part, and an impact part. The probe part was just formed with a fiber Bragg grating optical fiber The wavelength controling light source part was composed of a current supplying circuit, a DFB laser diode, and a TEC controling circuit for wavelength control. Also, the impact part was just implemented by dropping a steel ball. The performance of this sensor was confirmed by the experiments of the crack detection with an aluminum plate having one existing crack. According to these experiments, the difference of the sensor signal outputs was correlated with the crack length. So, it was confirmed that this sensor could be applied to monitor the crack growth.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.365-372
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• 1995

A signal processing technique for interferometric fiber-optic sensors is proposed. It does not require a any special optic components such as phase modulator, $3times3$ couplers,to obtain the full sensitivity of the interferometer. Instead, it requires a reference interferometer for phase referencing and a reference mirror for intensity referencing, but intensity referencing can be done without using the r reference mirror. The new technique utilizes the frequency chirping of the laser diode to process t the sensor signal with both wide dynamic range and high sensitivity of the interferometer. It was a applied to an internal-mirrored FP interferometric temperature sensor to obtain the system noise of $4\times10^{-3\circ}C$ from I cm FP Interferometor sensor device.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.381-383
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• 2013

This paper introduces what the interactive projection technology is, and how to use this technology to make a musical instrument. There have been many art works and business products completed by the interactive projection technology, but this technology seldom has been used in the musical field, so we want to make a simple instrument by interactive projection technology, and expect more people to develop this field in the future.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.47-50
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• 2000

Optical triangulation is one of the most common methods for acquiring range data. Using this method. We have developed a new type of Laser Displacement Sensor. We used Area CCD instead of linear CCD and PSD (Position Sensitive Detector). And we have developed the robust algorithm for increasing the accuracy and used USB instead of RS-232C for increasing speed. We present results that demonstrate the validity of our method using optical triangulation technique, Area CCD, and USB.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.98-105
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• 2008

In this paper, the system for monitoring process of aluminum laser welding was developed using the light signal emitted from the plasma which comes from interaction between material and laser. Photodiode for monitoring system was selected based on the spectrum analysis of light from plasma and keyhole. Behavior of plasma and keyhole was analyzed through the sensor signals. Value of sensor signal represented the light intensity and fluctuation of signal indicated the stability of plasma and keyhole. For the relation between welding condition and sensor signals, the input power and weld geometry greatly effected on the average of each sensor signals. Using the feature values of signals, estimation model for tensile strength of weld was formulated with neural network algorithm. Performance of this model was verified through coefficient of determination and average error rate.

• Journal of Sensor Science and Technology
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• v.10 no.3
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• pp.163-172
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• 2001

Fiber optic BOTDA (Brillouin Optical Time Domain Analysis) sensor was developed to be able to detect intrusion effect through several ten kilometer optical fiber. Fiber optic BOTDA sensor was constructed with 1 laser diode and 2 electro-optic modulators. The intrusion detection experiment was peformed by the strain inducing set-up installed on an optical table to simulating an intrusion effect. In the result of this experiment, the intrusion effect was well detected as the distance resolution of 3 m through the fiber length of about 4.81 km during 1.5 seconds.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.422-425
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• 2006

본 연구는 도체주변에 감겨진 광섬유 코일에 따라 선형편광축이 자기장에 의해 회전하는 Faraday Effect를 이용한 GIS(Gas Insulated Switchgear,이하 GIS) 용 광 전류센서의 구성과 DAQ(Data Acquisition,이하 DAQ)보드를 장착한 PC를 이용하여 실시간 데이터 취득, 분석 그리고 저장을 동시에 수행하였다 광원은 1310[nm]의 레이저 다이오드를 이용하였다. 센서부는 GIS에 맞게 원형으로 제작하였고 $9/125[{\mu}m]$규격 단일모드의 일반 통신용 광섬유를 지름 31[cm]의 센서부 코어에 20[회] 감아 설치하였다. PC기반의 실시간 데이터 분석 프로그래밍은 NI사의 Labview를 이용하여 코딩하였으며 PD(Photo Diode,이하 PD)의 전기적인 신호는 터미널 블록을 거쳐 NI사의 16bit DAQ M시리즈를 이용하여 수집되어진다. 직접 코딩한 프로그램을 이용하여 $700A\sim1400A$ 측정한 출력값 선형적인 증가추세를 보여주었다. 또한 OCS(Oscilloscope,이하 OCS)를 이용한 측정시스템과의 출력신호 및 정밀도를 비교 검토하였다. 그리고 Labview에서 지원하는 Web Tool기능을 이용하여 Web기반의 원거리 측정에서도 안정된 출력을 보여주었다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.379-380
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• 2013

본 논문은 중국전통문화 오행문무(五行文武)와 인터랙티브 미디어 아트 개념을 결합한다. 중국 전통악기 고금(古琴, Gu Qui)을 레이저 다이오드와 빛감지센서를 이용하여 현을 하드웨어적으로 구현하고, VVVV를 활용하여 센서 인식, 음향재생, 프로젝션 화면 영상 시각화에 해당하는 소프트웨어를 구현한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1023-1030
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• 2023

FMCW LiDAR system with robust target detection capabilities even under adverse operating conditions such as snow, rain, and fog is addressed in this paper. Our focus is primarily on enhancing the performance of FMCW LiDAR by improving the characteristics of the frequency-modulated laser, which directly influence range resolution, coherence length, and maximum measurement range etc. of LiDAR. We describe the utilization of an unbalanced Mach-Zehnder laser interferometer to measure real-time changes of the lasing frequency and to correct frequency modulation errors through an optical phase-locked loop technique. To extend the coherence length of laser, we employ an extended-cavity laser diode as the laser source and implement a laser interferometer with an photonic integrated circuit for miniaturization of optical system. The developed FMCW LiDAR system exhibits a bandwidth of 10.045GHz and a remarkable distance resolution of 0.84mm.