• Journal of Advanced Marine Engineering and Technology
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• v.34 no.5
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• pp.645-652
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• 2010

The aim of this investigation was study on the non-evaporation diesel spray characteristics injected through a common-rail diesel injector under various ambient pressure. The diesel spray was investigated with observation of macroscopic characteristics such as spray tip penetration and spray cone angle by the shadowgraph and the image processing method. The numerical study was conducted using a computational fluid dynamics code, AVL-FIRE. The breakup models used were WAVE model and standard $k-{\varepsilon}$ turbulence model was applied. The numerical study used input data which spray cone angle and fuel injection rate was achieved by Zeuch's method. Comparison with experimental result such as spray tip penetration was good agreement. Distribution of droplet diameter were conducted on four planes where the axial distances were 5, 15, 39 and 49mm respectively downstream from the orifice exit.

• Journal of radiological science and technology
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• v.30 no.3
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• pp.281-287
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• 2007

Contrast media may cause tissue injury by extravasation during intravenous automated injection during CT examination. Here, we present a study in which contrast media extravasation was detected and localized in the neck and thorax by three-dimensional(3D) CT data reformation. The CT studies of the extavasation site were performed using a 3D software program with four different display techniques axial, multi planar reformation(MPR), maximum intensity projection(MIP), and volume rendering displays are currently available for reconstructing MDCT data. 3D image reconstructions provide accurate views of high-resolution imaging. This paper introduces extravasation with the MDCT and 3D reformation findings of contrast media extravasation in neck ant thorax. The followed injection of the external jugular vein into an existing intravenous catheter and a large volume of extravasation was demonstrated on by 3D MDCT.

• The Korean Journal of Pain
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• v.36 no.1
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• pp.98-105
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• 2023

Background: Ultrasound-guided first sacral transforaminal epidural steroid injection (S1 TFESI) is a useful and easily applicable alternative to fluoroscopy or computed tomography (CT) in lumbosacral radiculopathy. When a needle approach is used, poor visualization of the needle tip reduces the accuracy of the procedure, increasing its difficulty. This study aimed to improve ultrasound-guided S1 TFESI by evaluating radiological S1 posterior foramen data obtained using three-dimensional CT (3D-CT). Methods: Axial 3D-CT images of the pelvis were retrospectively analyzed. The radiological measurements obtained from the images included 1st posterior sacral foramen depth (S1D, mm), 1st posterior sacral foramen width (S1W, mm), the angle of the 1st posterior sacral foramen (S1A, °), and 1st posterior sacral foramen distance (S1ds, mm). The relationship between the demographic factors and measured values were then analyzed. Results: A total of 632 patients (287 male and 345 female) were examined. The mean S1D values for males and females were 11.9 ± 1.9 mm and 10.6 ± 1.8 mm, respectively (P < 0.001); the mean S1A 28.2 ± 4.8° and 30.1 ± 4.9°, respectively (P < 0.001); and the mean S1ds, 24.1 ± 2.9 mm and 22.9 ± 2.6 mm, respectively (P < 0.001); however, the mean S1W values were not significantly different. Height was the only significant predictor of S1D (β = 0.318, P = 0.004). Conclusions: Ultrasound-guided S1 TFESI performance and safety may be improved with adjustment of needle insertion depth congruent with the patient's height.

• Composites Research
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• v.26 no.4
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• pp.259-264
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• 2013

This study manufactured the radiating element of multi-band antenna skin structure which satisfy electrical and mechanical performance and is made by double injection molding process. Structural test including impact and buckling test is carried out and stress analysis is simulated to evaluate safety of radiating element for the axial and shear loads, when changing of the skin structure is occurred by the external force. To predict allowable load of structure and evaluate safety on impact and buckling, experimental and analytic method is used in strength analysis of structure.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.217-228
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• 2000

Circulating Fluidized Bed Combustor(CFBC) has been used for the incineration of waste sewage sludge and for the power generation. In this study hydrodynamic characteristics of two phase flow have been studied in a riser section of CFBC. A lab-scale riser is designed and SiC (Geldart type B) is used for solid particles. Experiments are performed by controlling the fluidization parameters including superficial velocity and secondary air to primary air ratio for determination of solid holdup profiles in the riser. Superficial velocities of each fluidization regime are well agreed with results predicted by a theoretical model. The results show that the axial solid holdup distributions calculated by measuring differential static pressures in the riser are found to show a basic profile described by a simple exponential function. Our flow regime during experiments mainly belongs to fast fluidization regime for particle size of 300${\mu}m$. As the SA/PA ratio increases, solid holdup in the lower dense region of the riser increases.

• Journal of ILASS-Korea
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• v.3 no.2
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• pp.42-50
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• 1998

The effect of swirl flows un the fuel spray characteristics were investigated for various swillers in a model combustor. The interaction between the flow field and fuel spray in the main combustion tone made by frontal devices including fuel injection nozzles and swirlers. which were characterized by flow velocities, fuel droplet sizes and their distributions which were measured by APV(Adaptive Phase/Doppler Velocimetry) under atmospheric condition at 320cc/min kerosine fuel flow and 0.04kg/sec air supply. A dual swirler with circumferential two-stage swirl vanes of $40^{\circ}\;and\;45^{\circ}$ vanes in different directions and two single-stage swillers of $40^{\circ}$ vanes with 12 and 16 vanes were tested. It was found that the dual swirler has the largest recirculating zone with highest reverse flow velocity. The strongest swirl flow was found at the boundary of recirculation zone. Small fuel droplets were observed in the main axial stream and inside the recirculation zone when swirling flow field were generated by the frontal devices. These findings could give the tips on the optimal design of frontal devices to realize low emissions in gas turbine combustion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.196-199
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• 2012

Generally the piezo-composites have superior hydrostatic response characteristics than PZT ceramics due to both the stress amplification effect in axial direction and stress reduction effects in radial direction. This paper described material properties of a 1-3 type piezo-composite that fabricated with ceramic injection molding (CIM) technology. The electro-mechanical performances of the composite have been analyzed using FEM and the physical properties of the composite have been measured with the vol. % of the PZT ceramics. Based on the results, the $k_t$ increased rapidly as the vol. % of the PZT ceramics increased up to 30 vol. % and saturated the constant value in the above region. Also the experimental results have good agreement with the simulation values of the composite. Finally we developed the composites having high piezoelectric properties than the PZT ceramics with the CIM technology.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.454-454
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• 2007

Eye Glass Display (EGD) with microdisplay to realize the virtual display can make the large screen, so virtual image has been developed by using microdisplay panel. This paper shows study of spherical prism lens design and manufacture of a small size and light weigh EGD with 0.59" OLED panel. Code V is used and it designed an aspherical prism lens about eye relief 25mm and 42 degree of filed of view (FOV). With the application this aspheric prism lens to OLED type's microdisplay, virtual image showed 60 inch at 2m. It had less than 2% of distortion value and modulation transfer function in axial had 30% of resolution with 32 lp/mm spatial frequency. We made an injection molding bases to lens designed.

• Korean Journal of Optics and Photonics
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• v.3 no.1
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• pp.43-49
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• 1992

A microwave free electron laser which consists of Marx generator, vacuum diode, bifilar helical wiggler, and guide solenoid was designed and constructed. The analysis of the magnetic field distributions of the bifilar helical wiggler and computer simulation of electron trajectories with the perpendicular effect of space charges led to the conclusion that the magnetic field distributions are suitable for the electron beam injection. Output frequency in a single $TE_{11}$

• Medical Lasers
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• v.10 no.3
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• pp.123-131
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• 2021

Optical imaging modalities with properties of real-time, non-invasive, in vivo, and high resolution for image-guided surgery have been widely studied. In this review, we introduce two optical imaging systems, that could be the core of image-guided surgery and introduce the system configuration, implementation, and operation methods. First, we introduce the optical coherence tomography (OCT) system implemented by our research group. This system is implemented based on a swept-source, and the system has an axial resolution of 11 ㎛ and a lateral resolution of 22 ㎛. Second, we introduce a fluorescence imaging system. The fluorescence imaging system was implemented based on the absorption and fluorescence wavelength of indocyanine green (ICG), with a light-emitting diode (LED) light source. To confirm the performance of the two imaging systems, human malignant melanoma cells were injected into BALB/c nude mice to create a xenograft model and using this, OCT images of cancer and pathological slide images were compared. In addition, in a mouse model, an intravenous injection of indocyanine green was used with a fluorescence imaging system to detect real-time images moving along blood vessels and to detect sentinel lymph nodes, which could be very important for cancer staging. Finally, polarization-sensitive OCT to find the boundaries of cancer in real-time and real-time image-guided surgery using a developed contrast agent and fluorescence imaging system were introduced.