• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.86-92
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• 2011

ITS(Intelligent Transport System) has been researched actively to guarantee the smooth traffic and the safety of the vehicle. In recent, as the sensor for the measurement of distance between vehicles, the FMCW radar system in millimeter wave band has been interested in ITS. Actually, 47, 60, 77, 94 and 139 GHz have been assigned for the vehicle radar frequencies in Europe and Japan. However, the performances of the FMCW radar are deteriorated due to the interferences from the surrounding radars and mobile devices. In this paper, in order to model and simulate the performance of FMCW radar under the exterior interference, we propose a new performance parameter, RER(Radius Error Rate), which contains the information of the range error due to the interferences, and show the effectiveness of the proposed parameter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1297-1306
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• 2012

This work presents a 77 GHz radar transmitter for the automotive radar system. An integrated 13 GHz frequency synthesizer fabricated using 130 nm RF CMOS process drives a commercial W-band compound semiconductor monolithic multifunction amplifier(MPA), which includes a frequency multiplier by six to generate 77 GHz transmitting signal. The 13 GHz frequency synthesizer includes a high efficiency injection buffer of 4 dBm output power to drive the MPA. The output power of 77 GHz radar transmitter is higher than 13.99 dBm and the magnitude of the reference spur relative to the carrier is -36.45 dBc. The phase noise is -81 dBc/Hz at 1 MHz offset frequency from the carrier.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.54.2-54.2
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• 2016

Korea Microlensing Telescope Network (KMTNet) is the first optical survey system of its kind in a way that three KMTNet observatories are longitudinally well-separated, and thus have the benefit of 24-hour continuous monitoring of the southern sky. The wide-field and round-the-clock operation capabilities of this network facility are ideal for survey and the physical characterization of small Solar System bodies. We obtain their orbits, absolute magnitudes (H), three dimensional shape models, spin periods and spin states, activity levels based on the time-series broadband photometry. Their approximate surface mineralogy is also identified using colors and band slopes. The automated observation scheduler, the data pipeline, the dedicated computing facility, related research activity and the team members are collectively called 'DEEP-South' (DEep Ecliptic Patrol of Southern sky). DEEP-South observation is being made during the off-season for exoplanet search, yet part of the telescope time is shared in the period between when the Galactic bulge rises early in the morning and sets early in the evening. We present here the observation mode, strategy, software, test runs, early results, and the future plan of DEEP-South.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1932-1938
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• 2012

The impedance cardiogram has been proposed as a non-invasive, continuous, operator independent, and cost-effective method for cardiac output monitoring. However, it can not be completely considered as non-restrictive method because of attached spot and band type electrodes. Therefore, we developed a improved convenient hand-held typed measurement system for cardiac output by electrical impedance technique. 80 subjects from Yonsei University and the surrounding areas, participated. All subjects measured stroke volume and cardiac output through Physioflow and developed system. To verify the developed system, statistical methods such as correlation, Wilcoxon signed ranks test, and the Bland-Altman analysis were used. The proposed system showed significant correlation in both male and female stroke volume(r=0.715, r=0.704) and cardiac output(r=0.826; r=0.804). From these results, it can be concluded that stroke volume and cardiac output could be improved convenient measurement using the both hands without the help of a specialist.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.141.1-141.1
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• 2012

CIBER (Cosmic Infrared Background ExpeRiment) is a sounding-rocket borne experiment which is designed to find the evidence of the First stars (Pop.III stars) in the universe. They are expected to be formed between the recombination era at z ~ 1100 and the most distant quasar (z ~ 8). They have never been directly detected due to its faintness so far, but can be observed as a background radiation at around $1{\mu}m$ which is called the Cosmic Near-Infrared Background (CNB). The CIBER is successfully launched on July 10, 2010 at White Sands Missile Range, New Mexico, USA. It consists of three kinds of instruments. One of them is a LRS (Low Resolution Spectrometer) which is a refractive telescope of 5.5 cm aperture with spectral resolution of 20 ~ 30 and wavelength coverage of 0.7 to $2.0{\mu}m$ to measure the spectrum of the CNB. Since LRS detects not only CNB but also stellar components, we can study their spectral features with the broad band advantage especially at around $1{\mu}m$ which is difficult at ground observations because of the atmospheric absorption by water vapor. I identified around 300 stars from observed six fields. If we can classify their spectral types with SED fitting, we can study their physical conditions of the stellar atmosphere as well as making a stellar catalogue of continuous stellar spectrum.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.901-908
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• 2012

In an intelligent automated manufacturing environment, an administrator may use M2M (Machine-to-Machine) communication to recognize machine movement and the environment, as well as to respond to any potential dangers. However, commonly used wireless protocols for this purpose such WLAN (Wireless Local Area Network), ZigBee, and Bluetooth use the same ISM (Industrial Science Medical) band, and this may cause frequency interference among different devices. Moreover, an administrator is frequently exposed to dangerous conditions as a result of being surrounded by densely distributed moving machines. To address this issue, we propose in this paper to employ a location-based frequency interference management using fingerprinting scheme in industrial environments and its advanced localization schemes based on k-NN (Nearest Neighbor) algorithms. Simulation results indicate that the proposed schemes reduce distance error, frequency interference, and any potential danger may be responded immediately by continuous tracing of the locations.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.453-454
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• 2003

Most research materials (data), which are used for the study of digital mapping and digital elevation model (DEM) in the field of Remote Sensing and Aerial Photogrammetry are aerial photographs and satellite images. Additionally, they are also used for National land mapping, National land management, environment management, military purposes, resource exploration and Earth surface analysis etc. Although aerial photographs have high resolution, the data, which they contain, are not used for environment exploration that requires continuous observation because of problems caused by its coastline, as well as single - spectral and long-term periodic image. In addition to this, they are difficult to interpret precisely because Satellite Images are influenced by atmospheric phenomena at the time of photographing, and have by far much lower resolution than existing aerial photographs, while they have a great practical usability because they are mulitispectral images. The PKNU 2 is an aerial photographing system that is made to compensate with the weak points of existing aerial photograph and satellite images. It is able to take pictures of very high resolution using a color digital camera with 6 million pixels and a color infrared camera, and can take perpendicular photographs because PKNU 2 system has equipment that makes the cameras stay level. Moreover, it is very cheap to take pictures by using super light aircraft as a platform. It has much higher resolution than exiting aerial photographs and satellite images because it flies at a low altitude about 800m. The PKNU 2 can obtain multispectral images of visible to near infrared band so that it is good to manage environment and to make a classified diagram of vegetation.

• Land and Housing Review
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• v.2 no.4
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• pp.407-413
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• 2011

This paper reports a novel structural health monitoring (SHM) technique for detecting de-bonding between a concrete beam and CFRP (Carbon Fiber Reinforced Polymer) sheet that is attached to the concrete surface. To achieve this, a multi-scale actuated sensing system with a self-sensing circuit using piezoelectric active sensors is applied to the CFRP laminated concrete beam structure. In this self-sensing based multi-scale actuated sensing, one scale provides a wide frequency-band structural response from the self-sensed impedance measurements and the other scale provides a specific frequency-induced structural wavelet response from the self-sensed guided wave measurement. To quantify the de-bonding levels, the supervised learning-based statistical pattern recognition was implemented by composing a two-dimensional (2D) plane using the damage indices extracted from the impedance and guided wave features.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.321-326
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• 2003

We constructed grating- tuned external cavity semiconductor lasers using Littman and Littrow configuration, for which the wavelengths are tuned by rotation of the grating. This wavelength tunable semiconductor laser is one of the main devices of WDM optical communication. In Littman configuration, the wavelength range of about 60 nm (The C- and L-band range of 1,530~1,590 nm) was obtained by changing the incidence angle of the grating about $\pm$1$^{\circ}$ from the incidence angle of 70$^{\circ}$. In the 40 nm tuning range, the output power variation was less than 1.25 ㏈ and the side mode suppression ratio(SMSR) was 32 ㏈. In Littrow configuration (The incidence angle and the first order diffraction angle is the same, i.e. $\alpha$=$\delta$), the wavelength tuning range was about 80 nm for the same conditions used in Littman configuration except the incidence angle ($\alpha$=49$^{\circ}$). In 60 nm tuning range, the output power variation was less than 1.5 ㏈ and SMSR was 35 ㏈.

• Phonetics and Speech Sciences
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• v.13 no.3
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• pp.31-37
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• 2021

The fundamental frequency, or f0, is an important acoustic measure in the prosody of human speech. The current study examined the f0 distribution of a corpus of spontaneous speech in order to provide normative data for Korean speakers. The corpus consists of 40 speakers talking freely about their daily activities and their personal views. Praat scripts were created to collect f0 values, and a majority of obvious errors were corrected manually by watching and listening to the f0 contour on a narrow-band spectrogram. Statistical analyses of the f0 distribution were conducted using R. The results showed that the f0 values of all the Korean speakers were right-skewed, with a pointy distribution. The speakers produced spontaneous speech within a frequency range of 274 Hz (from 65 Hz to 339 Hz), excluding statistical outliers. The mode of the total f0 data was 102 Hz. The female f0 range, with a bimodal distribution, appeared wider than that of the male group. Regression analyses based on age and f0 values yielded negligible R-squared values. As the mode of an individual speaker could be predicted from the median, either the median or mode could serve as a good reference for the individual f0 range. Finally, an analysis of the continuous f0 points of intonational phrases revealed that the initial and final segments of the phrases yielded several f0 measurement errors. From these results, we conclude that an examination of a spontaneous speech corpus can provide linguists with useful measures to generalize acoustic properties of f0 variability in a language by an individual or groups. Further studies would be desirable of the use of statistical measures to secure reliable f0 values of individual speakers.