• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.224-226
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• 2016

With the technical development and rapid increase of private demand, the new market for unmanned vehicle combined with the characteristics of 'unmanned automation' and 'vehicle' is rapidly growing. Even though the pilot driving is currently allowed in some countries, there is no country that has institutionalized the formal driving of self-driving cars. In case of the existing vehicles, safety incidents are frequently happening due to the frequent malfunction of the rear sensor, blind spot of the rear camera, or drivers' carelessness. Once such minor flaws are complemented, the relevant regulations for the commercialization of self-driving car and small drone could be relieved. Contrary to the ultrasonic and laser sensors used for the existing vehicles, this paper aims to attempt the distance measurement by using the depth sensor. A depth camera calculates the distance data based on the TOF method calculating the time difference by lighting laser or infrared light onto an object or area and then receiving the beam coming back. As this camera can obtain the depth data in the pixel unit of CCD camera, it can be used for collecting depth data in real-time. This paper suggests to solve problems mentioned above by using depth data in real-time and also to design the obstacle avoidance system through distance measurement.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.3
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• pp.139-146
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• 2004

A 2D/3D complex optical system and its vision inspection algerian is proposed and implemented as a single probe system for high speed, precise vision inspection of the solder pastes. One pass un length labeling algorithm is proposed instead of the conventional two pass labeling algorithm for fast extraction of the 2D shape of the solder paste image from the recent line-scan camera as well as the conventional area-scan camera, and the optical probe path generation is also proposed for the efficient 2D/3D inspection. The Moire interferometry-based phase shift algerian and its optical system implementation is introduced, instead of the conventional laser slit-beam method, for the high precision 3D vision inspection. All of the time-critical algorithms are MMX SIMD parallel-coded for further speedup. The proposed system is implemented for simultaneous 2D/3D inspection of 10mm${\times}$10mm FOV with resolutions of 10 ${\mu}{\textrm}{m}$ for both x, y axis and 1 ${\mu}{\textrm}{m}$ for z axis. Experiments conducted on several nBs show that the 2D/3D inspection of an FOV, excluding an image capturing, results in high speed of about 0.011sec/0.01sec, respectively, after image capturing, with $\pm$1${\mu}{\textrm}{m}$ height accuracy.

• Journal of the Korean Vacuum Society
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• v.21 no.5
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• pp.264-272
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• 2012

In this paper, we report THz generation and detection characteristics investigated by InGaAs semiconductor epilayers, as results of a basic study obtained from the InGaAs-based THz transmitter/receiver (Tx/Rx). High-temperature and low-temperature (LT) grown InGaAs epilayers were prepared by the molecular beam epitaxy technique for the characterization of THz generation and detection, respectively, and the surface emission based on the photo-Dember effect was tried for THz generation. THz wave was generated by irradiation of a Ti:Sapphire fs pulse laser (60 ps/83 MHz), and a LT-GaAs Rx was used for the THz detection. The frequency band shown in the spectral amplitudes Fourier-transformed from the measured current signals was ranging in 0.5~2 THz, and the signal currents were exponentially increased with the Tx beam power. The THz detection characteristics of LT-InGaAs were investigated by using an Rx with dipole (5/20 ${\mu}m$) antenna, and the cutoff frequency was ~2 THz.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.74-79
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• 1994

The characteristics of the type I and type II SHG in LiB305 crystals grown by TSSG method have been investigated using 1064 nm beam from a Q-switched Nd:YAG laser. The measured phase matching angles and angular acceptance bandwidths were $\theta_m=90^{\circ}, \phi_m=11.6^{\circ}$, <$\delta\theta_{int}L_{1/2}=3.3^{\circ}-cm^{1/2}, \theta\phi_{int}L=0.27^{\circ}-cm^{1/2}$ for type I SHG and $\theta_m=20^{\circ}, \phi_m=90^{\circ}$, TEX>$\delta\theta_{int}L_=0.65^{\circ}-cm, \theta\phi_{int}L^{1/2}=3.5^{\circ}-cm^{1/2}$ for type II SHG, respectively. Thp. type I NCPM temperature of 1064 nm beam was found to be $149^{\circ}C$ with the temperature bandwidth $\DeltaTL$of $4.8^{\circ}C-cm$. An energy conversion efficiency of about 1.8% with 2.6 mm thick LBO crystal at an incident power of TEX>$171 MW/\textrm{cm}^2$ was demonstrated. The measured $d_{32} was 0.74\pm0.05 pm/V$..

• Journal of the Korean Vacuum Society
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• v.21 no.6
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• pp.342-347
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• 2012

The optical properties of InAs quantum dots (QDs) grown on a GaAs substrates by migration enhanced molecular beam epitaxy method have been investigated by using photoluminescence (PL) and time-resolved PL measurements. The luminescence properties of InAs/GaAs QDs have been studied as functions of temperature, excitation laser power, and emission wavelength. The PL peak of InAs QDs capped with $In_{0.15}Ga_{0.85}As$ layer (QD2) measured at 10 K is redshifted about 80 nm compared with that of InAs QDs with no InGaAs layer (QD1). This redshift of QD2 is attributed to the increase in dot size due to the diffusion of In from the InGaAs capping layer. The PL decay times of QD1 and QD2 at 10 K are 1.12 and 1.00 ns taken at the PL peak of 1,117 and 1,197 nm, respectively. The reduced decay time of QD2 can be explained by the improved carrier confinement and enhanced wave function overlap due to increased QD size. The PL decay times for both QD1 and QD2 are independent on the emission wavelength, indicating the uniformity of dot size.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.133-135
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• 2006

We propose and fabricate a novel fiber optic sensor for the detection of abnormal structural signals from various constructions. It's advantages are highly sensitive. small in dimension and electro-magnetic immune. Since this sensor was simply constructed with a single-mode fiber at infra-red wavelength and a laser-diode with the wavelength of 625 nm, the modes in the end of the optical fiber were not show as Gaussian distributed. So, we used the change of the mode distribution to get the sensor output by the external abnormal effect of structures. We investigated the resonance by performing the bending test of an aluminum beam attached with the fiber sensor. In the test, we could obtained a feasible signal to sense the abnormal condition of structures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6C
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• pp.793-800
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• 2004

In this paper, we propose a new automatic pipe grading algorithm for an efficient management of transmission pipe under the ground. Since the conventional transmission pipe evaluation was conducted by subjective decision made by an individual operator, it was difficult to grade them by means of numerical methods and also hard to realistically construct numerical database system. To solve these problems, we Int obtain some information on the current condition of pipes' sections by shooting laser beam at a regular rate and then apply grading algorithm after complete calculation of minimum diameter of pipe. We use some of preprocessing techniques to reduce noise and also use various color models to consider special conditions of each inner pipe. The measurement of pipes' minimum diameter and decision of grade are performed through a detailed processing stages. By some experimental results performed in the field, we show that over 90 percent of correct grade decisions are made by the proposed algorithm.

• Journal of Biomedical Engineering Research
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• v.24 no.2
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• pp.83-89
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• 2003

The gas electron multiplier placed in the drift volume of conventional gas detectors, is a conceptually simple device for producing a large gas gain by concentrating the drift electric field over a very short distance to the point that electron avalanching occurs(〉 10$^4$ V/cm), greatly increasing the number of drifting electrons. This device consists of a thin insulating foil of several tens of urn in thickness. covered on each side with a thin metal layer(Cu), with tiny holes, usually 100 ${\mu}{\textrm}{m}$ or less in diameter. and with a spacing of 100-200 ${\mu}{\textrm}{m}$ through the entire foil. perforated by using chemical etching or high-powered laser beam technique In this study, we have investigated its operating properties with various experimental conditions, and demonstrated the possibility of using this device as a digital X-ray imaging sensor, by acquiring X-ray images based on the scintillation properties of the gas electron multiplier with standard CCD camera.

• Journal of Environmental Science International
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• v.21 no.1
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• pp.1-9
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• 2012

A thermal-optical transmittance carbon analyzer has been developed to determine particulate organic (OC) and elemental (EC) carbon. Several analysis factors affecting the sensitivity of OC and EC determination were investigated for the carbon analyzer. Although total carbon (TC) is usually consistent in the determination, OC and EC split is sensitive to adopted analysis protocol. In this study the maximum temperature in oxygen-free He in the analysis was examined as a main cause of the uncertainty. Prior to the sensitivity analysis consistency in OC-EC determination of the carbon analyzer and the uniformity of carbonaceous aerosol loading on a sampled filter were checked to be in acceptable range. EC/TC ratios were slightly decreased with increasing the maximum temperature between $550-800^{\circ}C$. For the increase of maximum temperature from $500^{\circ}C$ to $800^{\circ}C$, the EC/TC ratio was lowered by 4.65-5.61% for TC loading of 13-44 ${\mu}g/cm^2$ with more decrease at higher loading. OC and EC determination was not influenced by trace amount of oxygen in pure He (>99.999%), which is typically used in OC and EC analysis. The facing of sample loaded surface to incident laser beam showed negligible influence in the OC-EC split, but it caused elevated PC fraction in OC for forward facing relative to backward facing.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.3
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• pp.175-184
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• 2009

We are entering into a era of enterprise computing that is characterized by an emphasis on broadband convergence, knowledge s haring, and calm services. Some people refer to this as the "ubiquitous" computing because its focus is on a high degree of connectivity between a company and its customers, suppliers, and channel partners. Ubiquitous computing technology, "RF" stands for "radio frequency"; the "ID" means "identifer". The tag itself of a computer chip and an antenna. The shortest metaphor is that RFID is like a bar-code but is read with an electromagnetic field rather than by a laser beam. Much has already been written about the use of RFID. But there is no has written about the use of RFID in the convention industry. Therefore this study have specific objectives as follows. 1. To give details on the use of RFID in convention. 2. To introduces the key concepts behind RFID technology. 3. To identify advantage & disadvantage of RFID technology using a BEXCO CASE study. 4. To study on ubiquitous convention using RFID and effective operation methods such as entrance identification system, session management, machine management, CRM management, visitor management, and contents management. This results provide into the current status of ubiquitous computing technology in convention industries. Specific advantages by using ubiquitous computing technology(RFID) are one-stop differentiate service, wireless internet service, use of visitor management system, entrance by tag, and U-logistics. On other side, disadvantages are security, stabilization of RFID system, higher price of RFID tag, and commercial scale. Convention by using of RFID technology is currently at an early stage. Convention company as BEXCO need to have the capabilities to adapt, to customize, to commercialize, and to modify technology to suit our circumstances.