• Journal of the Optical Society of Korea
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• v.13 no.4
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• pp.428-433
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• 2009

A photonic crystal fiber with two large air holes outside the holey cladding region is fabricated to induce an effective long periodic grating (LPG) in the core by an electric arc discharge. We believe that the two large air holes lead to the asymmetric perturbation in the core under the electric arc discharge, thereby introducing the coupling to the first higher-order mode. The transmission characteristics of the PCF with the LPG for the external perturbation such as strain, curvature, and temperature are also investigated. It was found that the shift of resonance peak in the transmission spectrum depends on the bending direction. The curvature of 8.55 $m^{-1}$ results in the center wavelength shifts of 1.8, 4.3, and 11 nm for a vertical, diagonal, and horizontal direction of the curvature to the large air-hole alignment, respectively.

• Journal of Digital Contents Society
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• v.14 no.2
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• pp.275-282
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• 2013

In medical image processing field, object recognition is usually carried out by computerized processing of various input information such as brightness, shape, and pattern. If the information mentioned does not make sense, however, many limitations could occur with object recognition during computer processing. Therefore, this paper suggests effective object recognition method based on the magnetic resonance (MR) theory to resolve the basic limitations in computer processing. We propose the efficient method of robust gray-white matter segmentation by texture analysis through the Susceptibility Weighted Imaging (SWI) for contrast enhancement. As a result, an average area difference of 5.2%, which was higher than the accuracy of conventional region segmentation algorithm, was obtained.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.51-56
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• 2016

High brittleness is a characteristic of glass, and in many cases it is broken during the process of machining due to processing problems, such as scratches, chipping, and notches. Machining defects occur due to the vibration of the equipment. Therefore, design techniques are needed that can control the vibration generated in the equipment to increase the strength of tempered glass. The natural frequency of the machine tool via vibration analysis (computer simulation) must be accurately understood to improve the design to ensure the stability of the machine. To accurately understand the natural frequency, 3D modeling, which is the same as actual apparatus, was used and a constraint condition was also applied that was the same as that of the actual apparatus. The maximum speeds of ultrasonic and high frequency, which are 15,000 rpm and 60,000 rpm, respectively, are considerably faster than those of typical machine tools. Therefore, an improved design is needed so that the natural frequency is formed at a lower region and the natural frequency does not increase through general design reinforcement. By restructuring the top frame of the glass processing, the natural frequency was not formed in the operating speed area with the improved design. The lower-order natural frequency is dominant for the effects that the natural frequency has on the vibration. Therefore, the design improvement in which the lower-order natural frequency is not formed in the operating speed area is an optimum design improvement. It is possible to effectively control the vibrations by avoiding resonance with simple design improvements.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.2005-2011
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• 2012

Nopp140 is a highly phosphorylated protein that resides in the nucleolus of mammalian cell and is involved in the biogenesis of the nucleolus. It interacts with a variety of proteins related to the synthesis and assembly of the ribosome. It also can bind to a ubiquitous protein kinase CK2 that mediates cell growth and prevents apoptosis. We found that Nopp140 is an intrinsically unfolded protein (IUP) lacking stable secondary structures over its entire sequence of 709 residues. We discovered that mitoxantrone, an anticancer agent, was able to enhance the interaction between Nopp140 and CK2 and maintain suppressed activity of CK2. Surface plasma resonance studies on different domains of Nopp140 show that the C-terminal region of Nopp140 is responsible for binding with mitoxantrone. Our results present an interesting example where a small chemical compound binds to an intrinsically unfolded protein (IUP) and enhances protein-protein interactions.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3567-3572
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• 2010

Black pine barks from the southern region of Korea were extracted using pressurized hot water and the water soluble extracts were then separated in a stepwise fashion using a variety of solvents, column chromatography (CC), thin layer chromatography (TLC), and high pressure liquid chromatography (HPLC). The antioxidant activities of each fraction and the active compounds were determined based on the radical scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH), reductive potential of ferric ion, and total phenol contents. A DPPH test showed that the half maximal effective concentration ($EC_{50}$ value : $6.59{\pm}0.31\;{\mu}g/mL$) of the ethyl acetate fraction (ca. 0.67%) was almost the same as that of the control compounds and inversely proportional to the value of the total phenol contents. The cell viability of the water extracts was confirmed by methyl thiazol-2-yl-2,5-diphenyl tetrazolium bromide (MTT) with enzyme linked immune sorbent assay (ELISA). Catechin, epicatechin, quercetin and ferulic acid were isolated from the ethyl acetate fraction as active compounds and identified by nuclear magnetic resonance. The antioxidant activity as value of DPPH of each of the separated compounds was lower than the ethyl acetate fraction, and ferulic acid was the lowest among these compounds.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.622-627
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• 2017

In this study, the numerical analysis of propellant supply manifold of a sub-scale model combustor with the same combustion and acoustic resonance conditions as the real combustor was carried out. The analysis of the results is based on the shape of the manifold and the number and type of inflow channels. The manifold form of the main propellant was rounded so that the recirculation area was small and easy to manufacture. The liquid oxygen mainfold included a distributor to uniformly supply the flow, and since the kerosene manifold was directly in contact with the flame side, the inflow channel was formed at a radial $360^{\circ}$ so as to minimize the recirculation region. The liquid nitrogen manifold was configured as a radial inflow channel to reduce the velocity difference near the injector.

• Journal of Korean Neurosurgical Society
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• v.39 no.3
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• pp.176-182
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• 2006

Objective : This study concernes the usefulness of $^{11}C-methyl-L-and$ D-methionine[Met]-positron emission tomography[PET] for glioma grading and detection of recurrence in gliomas, compared with fluorine-18, 2-fluoro-deoxyglucose[FDG]-PET. Methods : Eighty patients underwent Met-PET study for evaluation of glioma : 37 astrocytomas [WHO grade II, 3; III, 8; IV, 26]. 27 oligodendrogliomas [WHO grade II, 16; III, 11]. and 12 suspicious recurrent gliomas. All images were taken within 2 weeks before operation. For suspicious recurrent cases on magnetic resonance images, both FDG-PET and Met-PET were performed. Results : In astrocytoma, Mean maximum standard uptake value[SUV] of region of interest[ROI] was not different between WHO grades [p=0.108]. but ROI/normal contralateral tissue SUV [T/N] ratio was statistically different between WHO grades [p=0.002]. T/N ratio was more closely related to visual scale than maximum SUV of ROI [p<0.001 and p=0.107 respectively]. In oligodendroglioma, there was no statistical difference between WHO grades in view of maximum SUV and T/N ratio. For recurrent gliomas, sensitivity of FDG-PET and Met-PET was 25% and 100%, while specificity of FDG-PET and Met-PET were 100% and 80%, respectively. Conclusion : Met-PET might be an appropriate tool for tumor grading in astrocytoma and be more sensitive for detection of recurrence in gliomas than FDG-PET.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.549-555
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• 2017

A lead slowing-down spectrometer (LSDS) system is under development to analyze isotopic fissile content that is applicable to spent fuel and recycled material. The source neutron mechanism for efficient and effective generation was also determined. The source neutron interacts with a lead medium and produces continuous neutron energy, and this energy generates dominant fission at each fissile, below the unresolved resonance region. From the relationship between the induced fissile fission and the fast fission neutron detection, a mathematical assay model for an isotopic fissile material was set up. The assay model can be expanded for all fissile materials. The correction factor for self-shielding was defined in the fuel assay area. The corrected fission signature provides well-defined fission properties with an increase in the fissile content. The assay procedure was also established. The assay energy range is very important to take into account the prominent fission structure of each fissile material. Fission detection occurred according to the change of the Pu239 weight percent (wt%), but the content of U235 and Pu241 was fixed at 1 wt%. The assay result was obtained with 2~3% uncertainty for Pu239, depending on the amount of Pu239 in the fuel. The results show that LSDS is a very powerful technique to assay the isotopic fissile content in spent fuel and recycled materials for the reuse of fissile materials. Additionally, a LSDS is applicable during the optimum design of spent fuel storage facilities and their management. The isotopic fissile content assay will increase the transparency and credibility of spent fuel storage.

• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.274-282
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• 2014

In this study, closely spaced Au nanoparticles which are arranged in nanocluster (heptamer) configurations have been employed to design efficient plasmonic subwavelength devices to function at the telecommunication spectrum (${\lambda}$~1550 nm). Utilizing two kinds of nanoparticles, the optical properties of heptamer clusters composed of Au rod and shell particles that are oriented in triphenylene molecular fashion have been investigated numerically, and the cross-sectional profiles of the scattering and absorption of the optical power have been calculated based on a finite-difference time-domain (FDTD) method. Plasmon hybridization theory has been utilized as a theoretical approach to characterize the features and properties of the adjacent and mutual heptamer clusters. Using these given nanostructures, we designed a complex four-branch ($1{\times}4$) Y-shape splitter that is able to work at the near infrared region (NIR). This splitter divides and transmits the magnetic plasmon mode along the mutual heptamers arrays. Besides, as an important and crucial parameter, we studied the impact of arm spacing (offset distance) on the guiding and dividing of the magnetic plasmon resonance propagation and by calculating the ratio of transported power in both nanorod and nanoshell-based structures. Finally, we have presented the optimal structure, that is the four-branch Y-splitter based on shell heptamers which yields the power ratio of 23.9% at each branch, 4.4 ${\mu}m$ decaying length, and 1450 nm offset distance. These results pave the way toward the use of nanoparticles clusters in molecular fashions in designing various efficient devices that are able to be efficient at NIR.

• Journal of radiological science and technology
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• v.41 no.6
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• pp.553-560
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• 2018

PET-CT and PET-MRI which integrates CT using ionized radiation and MRI using phenomena of magnetic resonance are determined to have the limitation to apply the semi-quantitative index, standardized uptake value (SUV), with the same level due to the fundamental differences of image capturing principle and reorganization, hence, their correlations were analyzed to provide their clinical information. To 30 study subjects maintaining pre-treatment, $^{18}F-FDG$ (5.18 MBq/㎏) was injected and they were scanned continuously without delaying time using $Biograph^{TM}$ mMR 3T (Siemens, Munich) and Biograph mCT 64 (Siemens, Germany), which is an integral type, under the optimized condition except the structural differences of both scanners. Upon the measurement results of $SUV_{max}$ setting volume region of interest with evenly distributed radioactive pharmaceuticals by captured images, $SUV_{max}$ mean values of PET-CT and PET-MRI were $2.94{\pm}0.55$ and $2.45{\pm}0.52$, respectively, and the value of PET-MRI was measured lower by $-20.85{\pm}7.26%$ than that of PET-CT. Also, there was a statistically significant difference in SUVs between two scanners (P<0.001), hence, SUV of PET-CT and PET-MRI cannot express the clinical meanings in the same level. Therefore, in case of the patients who undergo cross follow-up tests with PET-CT and PET-MRI, diagnostic information should be analyzed considering the conditions of SUV differences in both scanners.