• Geophysics and Geophysical Exploration
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• v.23 no.1
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• pp.13-21
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• 2020

The acquisition and processing of long-offset data are essential for imaging deep geological structures in marine seismic surveys. It is challenging to derive an accurate subsurface image by employing conventional data processing to long-offset data owing to the normal moveout (NMO) stretch and non-hyperbolic moveout phenomena induced by seismic anisotropy. In 2017, the Korea Institute of Geoscience and Mineral Resources conducted a simultaneous two-dimensional multichannel streamer and ocean-bottom seismic survey using a 5.7-km streamer and an ocean-bottom seismometer to identify the deep geological structure of the Ulleung Basin. Herein, the actual geological subsurface structure was obtained via the sequential iterative updating of the velocity and anisotropic parameters of the long-offset data obtained using a multichannel streamer, and anisotropic prestack Kirchhoff migration was performed using the updated velocity and anisotropic parameters as input parameters. As a result, the reflection energy in the long-offset traces, which showed non-hyperbolic moveout owing to seismic anisotropy, was well aligned horizontally and NMO stretches were also reduced. Thus, a more precise and accurate migrated image was obtained, minimizing the distortion of reflectors and mispositioned reflection energy.

• Conservation Science in Museum
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• v.27
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• pp.103-124
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• 2022

This study examined the properties of the materials used in the three-story pagoda at Jangha-ri, Buyeo. It was performed in order to identify the objective condition of the pagoda and establish an appropriate plan for the conservation treatment of the pagoda. According to the study, the average total magnetic susceptibility was 3.71 (10^-3 SI unit), and at least four types of granite with different origins were likely used in the production of the pagoda. The ultrasonic velocity averaged 1,519m/s, and the coefficient of weathering showed an average of grade 4. The thermal gradient between the cement (restoration materials) and original materials was identified through thermal imaging. In some areas, the cement restoration materials required replacement with new stone materials with properties similar to those of the original stone materials. Taking into account these results, a map of weathering damage was prepared and appropriate conservation treatment plans were established based on the findings of previous studies. Since the pagoda had suffered severe biological damage and discoloration, surface contaminants were removed through wet cleaning with distilled water and a brush. The exfoliated areas were reinforced on the site by mixing epoxy resin with powdered stone with the same properties as the original stone materials of the pagoda.

• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.41-54
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• 2024

Regular monitoring plays a crucial role in ensuring the safety of geotechnical structures. Currently, nondestructive methods are employed to monitor such structures to minimize the impact, e.g., sensor-based accelerometers, displacement meters, image-based lasers, and drone imaging. These technologies can observe surface changes; however, they frequently suffer difficulties in terms of identifying changes in internal properties. To monitor changes in internal properties, in situ geotechnical investigations can be employed. A nondestructive test that can be used for this purpose is the spectral analysis of surface wave (SASW) test using geophones. The SASW test is a nondestructive method; however, due to the time required for data interpretation and the difficulty in analyzing the data, it is challenging to use the SASW test for monitoring applications that require frequent observations. However, it is possible to apply the first-step analysis, which yields the dispersion curve, for monitoring rather than the complete SASW analysis, which yields the shear wave velocity. Thus, this paper presents a fundamental study on the phase difference that derives the dispersion curve to utilize the SASW test for monitoring. The reliability of each phase difference interval is examined to determine the boundary to the subjected monitor. The study used phase difference data obtained using a geophone from a single-layered, homogeneous ground site to evaluate reliable boundaries. The findings of this study are expected to improve the utility of monitoring by identifying the ideal boundary for phase difference data.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.4
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• pp.239-247
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• 2001

The Fluorescence-Activated Cell Sorter (FACS) is a well-established instrument used for identifying, enumerating, classifying and sorting cells by their physical and optical characteristics. For a miniaturized FACS device, a disposable plastic microchip has been developed which has a hydrodynamic focusing chamber using soft lithography. As the characteristics of the spatially confined sample stream have an effect on sample throughput, detection efficiency, and the accuracy of cell sorting, systematic fluid dynamic studies are required. Flow visualization is conducted with a laser scanning confocal microscopy (LSCM), and three-dimensional flow structure of the focused sample stream is reconstructed from 2D slices acquired at $1\mutextrm{m}$ intervals in depth. It was observed that the flow structure in the focusing chamber is skewed by unsymmetrical velocity profile arising from trapezoidal cross section of the microchannel. For a quantitative analysis of a microscopic flow structure, Confocal Micro-PIV system has been developed to evaluate the accelerated flow field in the focusing chamber. This study proposes a method which defines the depth of the measurement volume using a detection pinhole. The trajectories of red blood cells (RBCs) and their interactions with surrounding flow field in the squeezed sample stream are evaluated to find optimal shape of the focusing chamber and fluid manipulation scheme for stable cell transporting, efficient detection, and sorting

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.97-103
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• 2014

Signal processing technique of linear frequency modulation-frequency shift keying (LFM-FSK) waveform has been introduced for rear view radars of an automobile. LFM-FSK waveform consists of two sequential stepped frequency waveforms with some frequency offset, and thus, can be used to generate inverse synthetic aperture radar (ISAR) images of rear view target of an automobile. However, ISAR images can often be blurred due to inter-pulse phase errors. To resolve this problem, one-dimensional (1-D) entropies of high resolution range profiles (HRRP) are minimized with the help of particle swarm optimization (PSO). The searching space used in PSO is adaptively adjusted by the use of information on the target's velocity obtained from LFM-FSK waveforms. Simulation results show that the proposed method can generate well-focused ISAR images.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.5
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• pp.1167-1174
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• 2015

As the market share of smartphone exponentially increases in mobile market, a number of manufacturers have developed their own operating system. Firefox OS is an open source operating system for the smartphone and tablet which is being developed by the Mozilla Foundation. This OS is designed using JavaScript and operated based on HTML5. Even though the number of manufacturers which release the Firefox OS smartphone is consistently increasing, However it is difficult to analyze artifacts in a smartphone in terms of investigation since existing researches on Firefox OS focused on imaging velocity according to abstract forensic process and block size. In this paper, we propose how to collect data in Firefox OS while minimizing data loss and forensic analysis framework based on analysis results on system and user data leaving in a smartphone.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.2
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• pp.218-225
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• 2015

Inverse synthetic aperture radar(ISAR) is coherent imaging system formed by conducting signal processing of received data which consists of radar cross section(RCS) reflected from maneuvering target. A novel algorithm is proposed to compensate inter-pulse motion(IPM) for the purpose of forming an well-focused ISAR image through signals generated by stepped chirp waveform( SCW). The velocity and acceleration of the target related to IPM are estimated based on particle swarm optimization (PSO) which has been widely used in optimization technique. Furthermore, a modified PSO which enables us to improve the performance of PSO is used to compensate IPM in a very short-time. Simulation results using point scatterer model of a Boeing-737 aircraft validate the performance of the proposed algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.784-790
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• 2009

A forward-looking automotive radar typically utilizes the frequency modulated continuous wave(FMCW) or pulsed-Doppler waveform for the Information acquisition of the target range and velocity. In order to obtain the high resolution target information, however, a narrow pulse width and wide bandwidth are inherently required, thus resulting in high peak power and high speed digital converter processing. In this paper, a stepped-frequency pulsed-Doppler(SFPD) waveform algorithm is proposed for high resolution forward looking automotive radar application. The performance of the proposed SFPD waveform technique is analyzed and compared with the conventional FMCW and PD method. Since this technique can be used for the high resolution target imaging with arbitrary range and Doppler resolution, it is expected to be useful In automotive radar target classification for the precision collision avoidance applications in the future.

• Journal of Veterinary Clinics
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• v.27 no.6
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• pp.735-739
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• 2010

An 8 month old female Maltese (body weight 3.6 kg) was referred with primary complaints of dyspnea and exercise intolerance. Diagnostic imaging studies revealed marked cardiomegaly and prominent main pulmonary trunk dilation on thoracic radiography, abnormally arisen aortic roots (toward right ventricle) with left-to right shunted perimembraneous ventricular septal defect located underneath of aortic root, aortic root was located to predominantly to the right ventricle and pulmonary regurgitation (peak velocity 4.7 m/s, pressure gradient ~88 mmHg) from pulmonary over-circulation and hypertension on echocardiography, indicating double outlet right ventricle (DORV). The dog was treated with furosemide (1 mg/kg, BID) for reducing volume overload at right ventricle, spironolatcone (1 mg/kg) and enalapril (0.5 mg/kg) for minimizing deleterious cardiac remodeling, and sildenafil (1 mg/kg) for lessening pulmonary over-circulation and hypertension. The clinical condition of this dog was improved after 1 week of medical treatment. The dog is currently survived and regularly monitored.

• Journal of Veterinary Clinics
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• v.31 no.2
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• pp.112-116
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• 2014

A 2-month-old intact male Pitbull terrier (weighing 1.01 kg) were referred with primary complaints of severe abdominal distension, exercise intolerance, retarded growth, yellow nasal discharge and anorexia. Diagnostic imaging studies found enlarged right atrium partitioned by abnormal membrane, severe pulmonic systolic jets (5.66 m/s of peak velocity) and right-to-left blood shunt at the inter-atrial septum. Based on clinical and diagnostic findings, the case was diagnosed as cor triatriatum dexter complicated with severe pulmonic stenosis and right-to-left shunted patent foramen ovale. Either surgical or interventional therapy has not been attempted, because of unstable patient's condition. Using blood transfusion, oxygen supply and cardiac medications (i.e., sildenafil, spironolactone, enalapril), the dog was recovered.