• Journal of Biomedical Engineering Research
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• v.27 no.1
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• pp.22-29
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• 2006

This paper proposes an efficient array beamforming method using spatial matched filtering for ultrasound imaging. In the proposed method, ultrasound waves are transmitted from an array subaperture with fixed transmit focus as in conventional array imaging. At receive, radio frequency (RF) echo signals from each receive channel are passed through a spatial matched filter that is constructed based on the system transmit-receive spatial impulse response. The filtered echo signals are then summed. The filter remaps and spatially registers the acoustic energy from each element so that the pulse-echo impulse response of the summed output is focused with acceptably low side lobes. Analytical beam pattern analysis and simulation results using a linear array show that the proposed spatial filtering method can provide more improved spatial resolution and contrast-to-noise ratio (CNR) compared with conventional dynamic receive focusing (DRF) method by implementing two-way dynamically focused beam pattern throughout the field.

• BMB Reports
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• v.54 no.10
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• pp.489-496
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• 2021

Chromatin has highly organized structures in the nucleus, and these higher-order structures are proposed to regulate gene activities and cellular processes. Sequencing-based techniques, such as Hi-C, and fluorescent in situ hybridization (FISH) have revealed a spatial segregation of active and inactive compartments of chromatin, as well as the non-random positioning of chromosomes in the nucleus, respectively. However, regardless of their efficiency in capturing target genomic sites, these techniques are limited to fixed cells. Since chromatin has dynamic structures, live cell imaging techniques are highlighted for their ability to detect conformational changes in chromatin at a specific time point, or to track various arrangements of chromatin through long-term imaging. Given that the imaging approaches to study live cells are dramatically advanced, we recapitulate methods that are widely used to visualize the dynamics of higher-order chromatin structures.

• Applied Microscopy
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• v.51
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• pp.12.1-12.12
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• 2021

Intravital video microscopy permits the observation of microcirculatory blood flow. This often requires fluorescent probes to visualize structures and dynamic processes that cannot be observed with conventional bright-field microscopy. Conventional light microscopes do not allow for simultaneous bright-field and fluorescent imaging. Moreover, in conventional microscopes, only one type of fluorescent label can be observed. This study introduces multispectral intravital video microscopy, which combines bright-field and fluorescence microscopy in a standard light microscope. The technique enables simultaneous real-time observation of fluorescently-labeled structures in relation to their direct physical surroundings. The advancement provides context for the orientation, movement, and function of labeled structures in the microcirculation.

• 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.

• Journal of Broadcast Engineering
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• v.23 no.5
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• pp.714-717
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• 2018

This paper presents a method of HDR imaging with adaptive saturation compensation for brightness change. The saturation of HDR images were lighten on dark region because conventional HDR methods have focused on brightness change. Therefore, the proposed HDR method compensates saturation adaptively according to brightness change. For experiments of several images, the proposed algorithm is superior to conventional HDR methods qualitatively and quantitatively in terms of color saturation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.83-86
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• 2004

Carbon nanotube (CNT) tips in tapping mode atomic force microscopy (AFM) enable very high-resolution imaging, measurements, and manipulation at the nanoscale. We present recent results based on experimental analysis that yield new insights into the dynamics of CNT probe tips in tapping mode AFM. Experimental measurements are presented of the frequency response and dynamic amplitude-distance data of a high-aspect-ratio multi-walled (MW) CNT tip to demonstrate the non-linear features including tip amplitude saturation preceding the dynamic buckling of the MWCNT. Surface scanning is performed using a MWCNT tip on a SiO$_2$ grating to verify the imaging instabilities associated with MWCNT buckling when used with normal control schemes in the tapping mode. Lastly, the choice of optimal setpoints for tapping mode control using CNT probe tip are discussed using the experimental results.

• Transactions of the Society of Information Storage Systems
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• v.5 no.2
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• pp.89-95
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• 2009

We setup the system to measure the noise characteristics of the 5M complementary metal-oxide semiconductor (CMOS) image sensor by generic measurement indicator of Standard mobile imaging architecture (SMIA) which is one of internal standard of mobile imaging architecture. To evaluate the effect of environment and setting parameters, such as temperature and integration time, we measure the variation of the dark signal, dynamic range and fixed pattern noise of image sensor. We also detect the number of defective pixels and cluster defects defined as adjacent single defect pixels at 5M CMOS image sensor. Then, we find the existence of some cluster defects in experiment, which are not expected in calculation.

• Molecules and Cells
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• v.41 no.9
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• pp.809-817
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• 2018

Discovery of the naturally evolved fluorescent proteins and their genetically engineered biosensors have enormously contributed to current bio-imaging techniques. These reporters to trace dynamic changes of intracellular protein activities have continuously transformed according to the various demands in biological studies. Along with that, light-inducible optogenetic technologies have offered scientists to perturb, control and analyze the function of intracellular machineries in spatiotemporal manner. In this review, we present an overview of the molecular strategies that have been exploited for producing genetically encoded protein reporters and various optogenetic modules. Finally, in particular, we discuss the current efforts for combined use of these reporters and optogenetic modules as a powerful tactic for the control and imaging of signaling events in cells and tissues.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.39.1-39
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• 2001

Impedance tomography (EIT) is a relatively new imaging modality in which the internal impedivity distribution is reconstructed based on the known sets of injected currents through the electrodes and induced voltages on the surface of the object. We describe a dynamic EIT imaging technique for the case where the resistivity distribution inside the object changes rapidly within the time taken to acquire a full set of independent measurement data, In doing so, the inverse problem is treated as the nonlinear state estimation problem and the unknown state (resistivity) is estimated with the aid of extended Kalman filter in a minimum mean square error sense. In particular, additional electrodes are attached to the known internal structure of the object ...

• Journal of the Korean Society of Visualization
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• v.22 no.2
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• pp.82-89
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• 2024

In this study, experiments were conducted to visualize and analyze the dynamic characteristics of splash and residual liquid film formation during and after the injection of water droplets onto vertically situated solid substrates with varying surface wettability, elasticity, and microtexture. As wettability decreased (higher contact angle), more splash droplets formed, and the residual liquid film decreased. Low contact angles resulted in thin residual films and less splash. Surface elasticity absorbed the impact forces of droplets, thereby decreasing splash phenomena and significantly reducing the formation of residual liquid films due to surface vibration. Surfaces with microtextures demonstrated control over droplet splash direction, guiding the liquid along desired pathways. High-speed imaging provided detailed insights, showing that surface properties critically influence splash dynamics and residual liquid film formation.