• KSBB Journal
• /
• v.10 no.5
• /
• pp.482-490
• /
• 1995

The relationship between pressure drop and liquid flow rate, for an axial and a radial flow chromatographic column packed with compressible porous media was theoretically analyzed using modified Kozeny-Carman equation. The results were compared with experimental observations obtained using compressible DEAE-agarose as a model medium. At 2-9 psi range studied, the theoretical derivation accounting for 'gel compression' effect predicted simple Langmuirian type response of volumetric flow rate to changes in pressure drop. On the other hand, the experimental response was more or less sigmoidal. At the same pressure drop, radial column showed 2-3 times higher flow rates than those of axial column both theoretically and experimentally. Using r-HBsAg crude extract, protein resolution effects between the two types of columns at different flow rates were compared side-by-side. It turned out that, though general chromatographic behavior was very similar, axial column was somewhat superior in terms of r-HBsAg recovery yield and specificity. However, the number of theoretical plates analysis indicated the protein resolution effects were comparable.

• Journal of KIISE:Software and Applications
• /
• v.29 no.10
• /
• pp.736-746
• /
• 2002

Zero anaphora occurs frequently in Korean complex sentences, and it makes the interpretation of sentences difficult. This paper proposes splitting algorithms and zero anaphora recovery rules for the purpose of handling zero anaphora, and also presents a resolution methodology. The paper covers quotations, conjunctive sentences and embedded sentences out of the complex sentences shown in the newspaper articles, with an exclusion of embedded sentences of auxiliary verb. We manage the quotations using the equivalent noun phrase deletion rule according to subject person constraint, the nominalized embedded sentences using the equivalent noun phrase deletion rule, the adnominal embedded sentences using the relative noun phrase deletion rule and the conjunctive sentences using the conjunction reduction rule in reverse. The classified table of the endings which relate to a formation of the complex sentences is used for splitting the complex sentences, and the syntactic rules, applied when being omitted, are used in reverse for recovering zero anaphora. The presented rule showed the result of 83.53% in perfect resolution and 11.52% in partial resolution.

• Geophysics and Geophysical Exploration
• /
• v.14 no.4
• /
• pp.335-341
• /
• 2011

Most sensing and instrumentation systems should have very higher sampling rate than required data rate not to miss important information. This means that the system can be inefficient in some cases. This paper introduces two new research areas about information acquisition with high accuracy from less number of sampled data. One is Compressed Sensing technology (which obtains original information with as little samples as possible) and the other is Super-Resolution technology (which gains very high-resolution information from restrictively sampled data). This paper explains fundamental theories and reconstruction algorithms of compressed sensing technology and describes several applications to geophysical exploration. In addition, this paper explains the fundamentals of super-resolution technology and introduces recent research results and its applications, e.g. FRI (Finite Rate of Innovation) and LIMS (Least-squares based Iterative Multipath Super-resolution). In conclusion, this paper discusses how these technologies can be used in geophysical exploration systems.

• Investigative Magnetic Resonance Imaging
• /
• v.22 no.1
• /
• pp.56-60
• /
• 2018

Therapeutic hypothermia in cardiac arrest patients is associated with favorable outcomes mediated via neuroprotective mechanisms. We report a rare case of a 32-year-old male who demonstrated complete recovery of signal changes on perfusion-weighted imaging after therapeutic hypothermia due to cardiac arrest. Brain MRI with perfusion-weighted imaging, performed three days after ending the hypothermia therapy, showed a marked decrease in relative cerebral blood flow (rCBF) and delay in mean transit time (MTT) in the bilateral basal ganglia, thalami, brain stem, cerebellum, occipitoparietal cortex, and frontotemporal cortex. However, no cerebral ischemia was not noted on diffusion-weighted imaging (DWI) or fluid-attenuated inversion recovery (FLAIR) sequences. A follow-up brain MRI after one week showed complete resolution of the perfusion deficit and the patient was discharged without any neurologic sequelae. The mechanism and interpretation of the perfusion changes in cardiac arrest patients treated with therapeutic hypothermia are discussed.

• Journal of Yeungnam Medical Science
• /
• v.31 no.2
• /
• pp.152-156
• /
• 2014

We report on a patient who showed visual recovery following bilateral occipital lobe infarct, as evaluated by follow up functional magnetic resonance imaging (fMRI) and diffusion tensor tractography (DTT). A 56-year-old female patient exhibited severe visual impairment since onset of the cerebral infarct in the bilateral occipital lobes. The patient complained that she could not see anything, although the central part of the visual field remained dimly at 1 week after onset. However, her visual function has shown improvement with time. As a result, at 5 weeks after onset, she notified that her visual field and visual acuity had improved. fMRI and DTT were acquired at 1 week and 4 weeks after onset, using a 1.5-T Philips Gyroscan Intera. The fiber number of left optic radiation (OR) increased from 257 (1-week) to 353 (4-week), although the fiber numbers for right OR were similar. No activation in the occipital lobe was observed on 1-week fMRI. By contrast, activation of the visual cortex, including the bilateral primary visual cortex, was observed on 4-week fMRI. We demonstrated visual recovery in this patient in terms of the changes observed on DTT and fMRI. It appears that the recovery of the left OR was attributed more to resolution of local factors, such as peri-infarct edema, than brain plasticity.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.6
• /
• pp.529-535
• /
• 2023

Noise originating from incipient propeller cavitation is assumed to come from a limited number of sources emitting a broadband signal. Conventional methods for cavitation localization have limitations because they cannot distinguish adjacent sound sources effectively due to low accuracy and resolution. On the other hand, sparse Bayesian learning technique demonstrates high-resolution restoration performance for sparse signals and offers greater resolution compared to conventional cavitation localization methods. In this paper, an incipient propeller cavitation localization method using sparse Bayesian learning is proposed and shown to be superior to the conventional method in terms of accuracy and resolution through experimental data from a model ship.

• Journal of radiological science and technology
• /
• v.41 no.4
• /
• pp.321-327
• /
• 2018

The purpose of this study is to compare PET imaging performance with Fluorine-18 ($^{18}F$) and Gallium-68 ($^{68}Ga$) for influence of physical properties of PET tracer. Measurement were performed on a Siemens Biograph mCT64 PET/CT scanner using NEMA IEC body phantom and Flangeless Esser PET phantom containing filled with $^{18}F$ and $^{68}Ga$. Emission scan duration(ESD) was set to 1, 2, 3, 4 and 5min/bed for $^{68}Ga$ and 1min/bed for $^{18}F$. The PET image were evaluated in terms of contrast, spatial resolution. Under same condition, The percentage of contrast recovery measured in the phantom ranged from 16.88% to 72.56% for $^{68}Ga$ and from 27.51% to 74.43% for $^{18}F$ and The FWHM value to evaluate spatial resolution was 10.96 mm for $^{68}Ga$ and 9.19 mm for $^{18}F$. For this study, $^{18}F$ produces better image contrast and spatial resolution than $^{68}Ga$ due to higher positron yield and lower positron energy ($^{18}F$: 96.86%, 633.5 keV, $^{68}Ga$: 88.9%, 1899 keV), The physical properties of PET tracer effect on the PET image. $^{68}Ga$ image applying ESD of 3, 4, 5min/bed were showed similar to $^{18}F$ image with ESD of 1min/bed. This study suggests that increasing ESD for acquiring $^{68}Ga$ PET image seem to be similar to $^{18}F$ image.

• Proceedings of the Optical Society of Korea Conference
• /
• 1990.02a
• /
• pp.172-176
• /
• 1990

A high resolution picosecond absorption kinetic spectrometer utilizing dye emission and a streak camera is presented and compared with other methods of picosecond transient absorption measurements. Typical transient absorption and bleach recovery kinetics measured with this spectrometer are shown. Single wavelength transient absorption or ground state bleach recovery kinetics are determined on the basis of a single laser shot, so that the samples are relatively free frm decomposition by irradiation. Excellent kinetics may be obtained from the near UV to the near IR and are not subject to interference from luminescence of samples. The sensitivity of this spectrometer is very high and it is reasonably easy and convenient to set up and use.

• Proceedings of the KSRS Conference
• /
• 2008.10a
• /
• pp.365-367
• /
• 2008

A digital city model represents a 3D environment of a city with various city object information such as 3D building model, road, and land cover. Usually, at least two satellite images with some image overlap are necessary and a complex satellite-related computation needs to be carried out to create a city model. This is an expensive technique, because it requires many resources and excessive computational cost. The authors propose a methodology to create a digital city model including 3D building model and land cover information from a single high resolution satellite image. The approach consists of image pan-sharpening, shadow recovery, building occlusion restoration, building model extraction, and land cover classification. We create a digital city model using a single KOMPSAT-2 image and review the result.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.30 no.10 s.253
• /
• pp.929-934
• /
• 2006

The digital HPTV(holographic particle tracking velocimetry) velocity field measurement system consists of four steps: recording, numerical reconstruction, particle extraction and velocity extraction. In the velocity extraction process, we improved the two frame PTV algorithm to extract 3-D displacement information of each particle located in 3D space. Because a digital CCD camera was used, some factors such as spatial resolution, numerical aperture, and particle concentration influenced on the performance of the developed digital HPTV. Especially, the particle concentration $(C_o)$ affected the reconstruction efficiency and recovery ratio in the numerical reconstruction and particle extraction procedure. In this paper, the effect of particle concentration reconstruction efficiency and recovery ratio were analyzed experimentally. Optimal particle concentration was found to be in the range of $C_o=11{\sim}17\;particles/mm^3$.