• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2007.04a
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• pp.145-148
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• 2007

The Korea Multi-Purpose Satellite-2 (KOMPSAT-2) was launched in July 2006 and The main mission of the KOMPSAT-2 is a high resolution imaging for the cartography of Korea peninsula by utilizing Multi Spectral Camera (MSC) images. The camera resolutions are 1 m in panchromatic scene and 4 m in multi-spectral imaging. KOMPSAT-2 measure the position, velocity and attitude data of satellite using by star sensor, gyro sensor, and GPS sensor. This paper provides an initial geometric accuracy assessment of the KOMPSAT-2 high resolution image, both geometric Cal/Val overview.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.83.4-84
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• 2015

We report that a strong downflow event caused three-minute oscillations in the solar atmosphere. Our observations were carried out by using the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST) and the Interface Region Imaging Spectrograph (IRIS). Our main findings are as follows: (1) The strong downflow was seen at the $H{\alpha}$ absorption line at first, and then appeared at the Si IV and C II emission lines. It seems that the characteristics of the downflow are consistent with a coronal rain event. (2) After the event, oscillations of velocity were identified in the chromospheric lines and transition region lines. (3) The amplitudes of oscillations were 2km/s at Mg II line and 3km/s at C II and Si IV lines and decreased with time. (4) The period of the oscillation was 2.67 minutes at first, but gradually increased with time. Our findings are in agreement with Chae & Goode (2015)'s theory that of acoustic waves generated by a disturbance in a gravitationally-stratified medium.

• Korean Journal of Veterinary Research
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• v.55 no.3
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• pp.209-211
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• 2015

An 8-year-old spayed female Maltese (2.5 kg of body weight) presented with the primary complaint of loud heart murmur and exercise intolerance. Diagnostic imaging revealed severe pulmonic stenosis (peak velocity 5.2 m/s) with right ventricular hypertrophy. The dog revisited after 2 years, at which time, diagnostic imaging revealed severe biventricular hypertrophy, dynamic left ventricular outflow tract obstruction, left atrial dilation and pulmonary hypertension with worsened pre-existing pulmonic stenosis. Postmortem investigation revealed hypertrophic cardiomyopathy and regional myocardial infarction. The case was diagnosed as hypertrophic cardiomyopathy secondary to severe right and left ventricular outflow tract obstruction.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.480-483
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• 1997

In this paper, we have proposed an automatic inspection system for cracks on the surface of a structure. The proposed system consists of the imaging system and the veh~cle system. The imaging system. a set of optical sensor, lens, illuminator, storage and their configuration, images the scene and store it on the hard disk. We adopted a linescan camera of 5000 pixel density to achieve high resolution without loss of simplicity. The vehicle system that moves the optical system IS ~mplemented by an AGV. The AGV moves forward at constant velocity and avoid obstacles to acquire a stable image. We have cmplemented an experimental system and have acquired images of the wall of hallway. The image is of 0.1-mmipixel resolution and the scanning time IS about 1 mlsec. The allow able scan.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.61-71
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• 2002

Color-code imaging should be one of the best display tools for the quick perception of both damage area and its intensity, In this study we proposed the standard color code corresponding to maximum observed acceleration value. Since the acceleration value changes with frequency contents, we suggested to limit the frequency band less than 10Hz. The background considerations of this limitation, magnitude vs. dominant frequency, natural characteristics of artificial noises and the relationship between velocity and acceleration, were reviewed in detail. The standard of color code was assigned from 0.001%g to 20%g based on the possible earthquakes at Korean peninsula and the color imaging given by RGB value was shown to be very consistent, irrespective of hardware configuration.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3693-3696
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• 2010

We experimentally measure the kinetic energy and angular distributions of photoelectrons of $N_2$ as a function of 410 nm femtosecond laser intensity by using velocity map imaging technique. The strong-field multiphoton ionization of molecules shares many of the characteristics with those of atoms. Electron kinetic energies are nearly independent of laser intensities. The independence suggests that the electron peaks in the photoelectron spectrum actually result from a two-step process, indicative of the occurrence of real population in the intermediate states. The relative amplitudes of electron peaks indicate that in the two-step process, nonresonant population transfer dominates for low intensities, while resonant population transfer dominates for higher intensities.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.515-525
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• 2000

A new acoustic field visualization technique is introduced in this study. Small particles of which density is small enough to follow up the air used for the noise field visualization. In order to quantify the noise, PIV(Particle Imaging Velocimetry) has been constructed. When the driving frequency is in the vicinity of the resonance frequency of the simplified 2-dimensional muffler system, an acoustic streaming is shown and of which velocity distribution is obtained through PIV technique. It is experimentally proved that the present technique is able to visualize and quantify the acoustic fields.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.898-905
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• 2018

In this work, infrared targets for a developed hardware-in-the-loop simulation(HILS) system are proposed for a performance test of a dual-sensor imaging seeker equipped with an infrared and a visible sensor that can lock and track for ground and air targets. This integrated system is composed of 100 modules of heat and light sources to simulate various kinds of target and the trajectory of moving targets based on scenarios. It is possible to simulate not only the position, velocity, and direction for these targets but also background clutter and jamming environments. The design and measurement results of an infrared target, such as the HILS system configuration, developed for testing and evaluation of a dual-sensor imaging seeker are described. In the future, it is planned to test the lock-on and tracking performance of an imaging seeker equipped with single or dual sensors dynamically in real time based on a simulation flight scenario in the developed HILS system.

• Investigative Magnetic Resonance Imaging
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• v.5 no.1
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• pp.38-42
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• 2001

Dark band artifacts are often observed in angiograms of arteries obtained by 2D time-of-flight (TOF) angiography with saturation of veins by presaturation RF pulses. At some arteries the arterial blood velocity varies in a triphasic pattern during a cardiac cycle. The arterial blood, that is saturated by presaturation RF pulses in the saturation band, can flow back into the imaging slice during the retrograde flow phase of the triphasic variation. When such saturated retrograde flow occurs during the acquisition of the central part of the K space, a signal void can result in base images and consequently dark band artifacts can appear in angiograms. This phenomenon is experimentally demonstrated by varying the gap between the imaging slice and the saturation band. Furthermore, a new pulse sequence is proposed to eliminate the dark band artifacts by changing the profile of the saturation band front a rectangle to a ramp.

• Imaging Science in Dentistry
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• v.48 no.3
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• pp.153-160
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• 2018

Purpose: This study aimed to assess the reliability of ultrasonography (US) in comparison with cone-beam computed tomography (CBCT) as a tool for monitoring the healing of jaw lesions. Materials and Methods: Twenty-one radiolucent lesions in jaws referred to the Oral Surgery Department at our institution were selected for this study. All lesions underwent CBCT and US examinations. The anteroposterior, superoinferior, and mesiodistal dimensions of the lesions were measured on CBCT and US images before surgery and at 6 months after surgery. The dimensions were compared between the US and CBCT images. Blood-flow velocity around the lesions was measured by color Doppler before surgery and at 1 week and 6 months after surgery to assess the capability of US to show changes in blood-flow velocity around the lesion. Results: Before surgery, there were no significant differences between US and CBCT in the mesiodistal and anteroposterior dimensions, although a significant difference was found in the superoinferior dimension (P<.05). However, at 6 months after surgery, significant differences were found between US and CBCT in all dimensions, and it is likely that the US measurements more accurately reflected the extent of healing. The average blood-flow velocity increased at 1 week after surgery (5.84 cm/s) compared with the velocity before surgery (4 cm/s) (P<.05). Then, at 6 months after surgery, the blood-flow velocity significantly decreased (3.53 cm/s) compared to the velocity measured at 1 week after surgery (P<.05). Conclusion: US with color Doppler was confirmed to be a more efficient tool than CBCT for monitoring bone healing.