• Microbiology and Biotechnology Letters
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• v.2 no.1
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• pp.45-50
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• 1974

1 With cysteinedesulfhydrase (E. C.4.4.1.1.) from Aerobactor aerogenes, an enzyme which catalyzes the stoichiometric conversion of L-cysteine to pyruvate, ammonia and sulfide, reversibility of the degradation of L-cysteine was investigated. It was found that the enzyme also catalized the reverse reaction of $\alpha$, $\beta$-elimination to synthesize L-cysteine derivatives from pyruvate, ammonia and sulfides when large amounts of substrates were added to the reaction mixtures. 2. The synthetic reaction by cysteinedesulfhydrase proceeded linearly with incubation time and enzyme concentrations. The optimal pH for the synthetic reaction was 10.0. 3. The results of the isolation and identification of the products showed that the L-cysteine derivatives synthesized by this enzymatic method were identical with S-methyl-L-cysteine and S-ethyl-L-cysteine respectively.

• Nuclear Engineering and Technology
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• v.44 no.1
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• pp.53-60
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• 2012

The aim of this study was to explore the spatial and energy resolutions of a PET scanner that we have recently developed. The scanner, which consists of six detector modules with 1-layer LGSO crystals, has a hexagonal configuration with a faceto- face distance of 86.4 mm between two opposite PET modules; such properties facilitate the imaging of small animals. A $^{22}Na$ point source was employed to estimate horizontal and vertical spatial resolutions. To assess the energy resolution, a uniform $^{18}F$ cylindrical phantom was scanned. A software-based spectrum analysis of list-mode data was used to assign a local energy window centered on the photopeak position for every single crystal. For the image reconstruction, an ML-EM algorithm was used. The spatial resolutions at the center of the scanner were 0.99 mm in the horizontal direction and 1.13 mm in the vertical direction. The energy resolution averaged over each PMT ranged from 13.3%-14.3%, which gave an average value of 13.8%. These results show that this simple system is promising for small animal imaging with excellent spatial and energy resolutions.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.6
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• pp.391-400
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• 2016

For earthquake loss estimation of building structures in Gangnam-Gu district in Seoul, three scenario earthquakes were selected by comparison of the response spectra of these scenario earthquakes with the design spectrum in Korean Building Code (KBC 2009), and then direct losses of the building structures in the Gangnam-Gu district under each scenario earthquake are estimated. The following conclusions are drawn from the results of damage and loss in the second scenario earthquake, which has a magnitude = 6.5 and epicentral distance =15 km: (1) The ratio of building stocks undergoing the extensive and complete damage level is 40.0% of the total. (2) The amount of direct economic losses appears approximately 19 trillion won, which is 1.2% of the national GDP of Korea. (3) About 25% of high-rise (over 10-story) RC building wall structures, were inflicted with the damage exceeding moderate level, when compared to 60% of low-rise building structures. (4) From the economical view point, the main loss, approximately 50%, was caused by the damage in the high-rise RC wall building structures.

• Korean Journal of Optics and Photonics
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• v.3 no.2
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• pp.77-85
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• 1992

The design of a flat-field XUV spectrograph is optimized for a high throughput, aberration-corrected spectral image in the wavelength region of 50-300 $\AA$ The varied-line spacing (VLS) concave grating theory for an XUV spectrograph with a toroidal mirror in front of an entrance slit is derived. Since the derived theory includes the arbitrary shaped source, it is able to correct the limit of the simple optimization theory which considers only a point source at the center of the entrance slit. The reflection matrix at the toroidal mirror and the diffraction matrix at VLS grating are derived and compared with those of a holographic grating. The absolute energy efficiency of a flat-field spectrograph is calculated by considering the reflectivities of the toroidal mirror and the Au coated concave grating and the grating efficiency. The alignment sensitivity of the toroidal mirror and the concave grating is investigated, and the method to achieve the best imaging of XUV spectrum is discussed. The calculated resolving power of the flat-field XUV spectrograph is more than 4000 in the aberration-corrected wavelength range. The focused spot size at the dispersion plane is less than $20\mu \textrm m\times \mu \textrm m$at the wavelength 100$\AA$ It is shown that a high throughput characteristic can also be achieved through a careful adjustment of alignment parameters.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.4
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• pp.305-312
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• 1995

In general, the radiation stresses based on the linear wave theory are overestimated which result in the discrepancy between the computed results and laboratory data of mean water level in the surf zone. Oh (1995) estimated the mean water level by using Svendsen's radiation stress model (1984) and compared with the experimental data. In this study. the computed results showed good agreements with the experimental data in the case of small wave steepness. while the results were overestimated in the case of large wave steepness. In this paper. the dimensionless radiation stress proposed by Svendsen (1984) is expressed in terms of relative water depth at breaking point and deep water wave steepness. The computed results are compared with the results calculated by d linear wave theory, Stive's model (1984). Sawaragi et al's model (1984) based on the spectrum of breaking wave components. and published laboratory data. The computed results of the modified Svendsen's model arc favourably compared with the laboratory data.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.58
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• pp.38-49
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• 2006

In order to increase the spectrum efficiency, recently, there is the number of studies for CR technology. For instance, IEEE 802.22 WRAN(Wireless Regional Area Network) WG considered the CR technology as a solution of WRAN system to serve the high speed internet service(1.5 Mbps down stream and 384 kbps up stream) in 100 km overall coverage and 54 MHz-746 MHz band. Basically, in MAC point of view, the WRAN system have been standardizing based on the IEEE 802.16 MAC layer features such as Data transmission method, QoS provision and Bandwidth request schemes. Additionally, the WRAN system further include CR nature functions such as incumbent user protection, self coexistence which would be importantly considered. Also, the inherent WRAN functions are added such as channel bonding and fractional bandwidth usage. This paper mainly explained frame structure, IU protection, self coexistence which are key functions of WRAN system. Finally, in this paper, we expressed a prospect of IEEE 802.22 WRAN standardization.

• Korean Journal of Microbiology
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• v.27 no.4
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• pp.348-356
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• 1989

An extracellular peroxidase found in culture broth of Pleurotus ostreatus was induced by syringic acid. This enzyme was fractionated by DEAE Sephadex A-50 ion exchange chromatography and gel filtration chromatogrphy on Sephadex G-150. The enzyme is a glycoprotein containing 35.7% carbohydrate. The results of SDS-linear polyacrylamide gradient gel electrophoresis and gel filtration indicate that the enzyme is a dimer consisted of identical subunits (Mr=72,400). The absorption spectrum of the enzyme indicates the presence of one mole of iron protoporphyrin IX per one mole of subunit. Isoelectric point of the enzyme is 4.26 and $K_m$ values for $H_2O_2$ is $7.2{\mu}M$. The enzyme showed its optimal activity at pH 3.5-4.0 and at $40^{\circ}C$. The Km values of this enzyme for ferulic acid and sinapic acid are 2.4 and 12.3 times higher than those of horseradish peroxidase, respectively.

• Korean Journal of Radiology
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• v.20 no.1
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• pp.126-133
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• 2019

Objective: To compare the lumbar vertebral bone marrow fat-signal fractions obtained from six-echo modified Dixon sequence (6-echo m-Dixon) with those from single-voxel magnetic resonance spectroscopy (MRS) in patients with low back pain. Materials and Methods: Vertebral bone marrow fat-signal fractions were quantified by 6-echo m-Dixon (repetition time [TR] = 7.2 ms, echo time (TE) = 1.21 ms, echo spacing = 1.1 ms, total imaging time = 50 seconds) and single-voxel MRS measurements in 25 targets (23 normal bone marrows, two focal lesions) from 24 patients. The point-resolved spectroscopy sequence was used for localized single-voxel MRS (TR = 3000 ms, TE = 35 ms, total scan time = 1 minute 42 seconds). A 2 × 2 × 1.5 cm³ voxel was placed within the normal L2 or L3 vertebral body, or other lesions including a compression fracture or metastasis. The bone marrow fat spectrum was characterized on the basis of the magnitude of measurable fat peaks and a priori knowledge of the chemical structure of triglycerides. The imaging-based fat-signal fraction results were then compared to the MRS-based results. Results: There was a strong correlation between m-Dixon and MRS-based fat-signal fractions (slope = 0.86, R² = 0.88, p < 0.001). In Bland-Altman analysis, 92.0% (23/25) of the data points were within the limits of agreement. Bland-Altman plots revealed a slight but systematic error in the m-Dixon based fat-signal fraction, which showed a prevailing overestimation of small fat-signal fractions (< 20%) and underestimation of high fat-signal fractions (> 20%). Conclusion: Given its excellent agreement with single-voxel-MRS, 6-echo m-Dixon can be used for visual and quantitative evaluation of vertebral bone marrow fat in daily practice.

• The Journal of Engineering Geology
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• v.2 no.2
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• pp.155-165
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• 1992

The purpose of this study is to evaluate compatability of seismic source characteristics of the Kern County earthquake to those of Korean Peninsula seismotectonics. The compatability could be used to make Korean type response spectrum from the strong ground motions observed from the assingned earthquake. The July 21, 1952, Kern County, California, earthquake is the largest earthquake to occur in the western U.S. since 1906, and the repeat of this event poses a significant seismic hazard. The Kern County event was a complex thrusting event, with a surface rupture pattern that varied from pure leftlateral strike-slip to pure dip-slip. A time dependent moment tensor inversion was applied to ten observed teleseismic long-period body waves to investigate the source complexity. Since a conventional moment tensor inversion(constant geometry through time) returns a non-double-couple source when the seismic source changes(fault orientation and direction of slip) with time, we are required to use the time dependent moment tensor which allows a first-order mapping of the geometric and temporal complexity. From the moment tensor inversion, a two-point seismic source model with significant overlap for the White Wolf fault, which propagates upward(20 km to 5 km) from SW to NE, fits most of the observed seismic waveforms in the least squares sense. Comparison of P, T and B axes of focal mechanisms and focal depths suggests that seismic source characteristics of the Kern County earthquake is consistant with those of Korean Peninsula Seismotectonics.

• Journal of the Korean Wood Science and Technology
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• v.28 no.1
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• pp.36-41
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• 2000

This study was carried out to introduce functional groups onto wood by reacting with 2-methacryloyloxyethyl isocyanate(MOI). The effects of the catalyst and the reaction conditions(temperature and time) on the treatment were investigated. The evidence of bonding between wood and MOI were examined by infrared(IR) spectroscopy. The change in surface characteristics of MOI treated wood was examined by water contact angle measurement and X-ray photoelectron spectroscopy(XPS). Wood reacted quickly with MOI in the presence of di-n-butiltin dilaurate catalyst. Especially, the increase in weight percent gain(WPG) with increasing in reaction time was remarkable at the reaction temperature of over $50^{\circ}C$. The IR spectrum of wood reacted with MOI showed a strong urethane absorption(1715 $cm^{-1}$) but no isocyanate(2235 $cm^{-1}$) absorption. It also showed a sharp olefinic C=C double bond absorption at 1635 $cm^{-1}$. This means that an introduced methacrylate group becomes the starting point of further graft copolymerization with another vinyl monomers. The wood modified with MOI showed a gradual increase in contact angle with increasing in WPG, which means that the hydrophilic wood surface become quite hydrophobic. Also, it was cleared that most parts of the wood surface were modified with MOI by XPS analysis.