• Journal of the Korean Magnetic Resonance Society
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• v.24 no.4
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• pp.136-142
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• 2020

Apolipoprotein B-100 (apo B-100), the main protein component that makes up LDL (Low density lipoprotein), consists of 4,536 amino acids and serves to combine with the LDL receptor. The oxidized LDL peptides by malondialdehyde (MDA) or acetylation in vivo were act as immunoglobulin (Ig) antigens and peptide groups were classified into 7 peptide groups with subsequent 20 amino acids (P1-P302). The biomimetic peptide P99 (KGTYG LSCQR DPNTG RLNGE) out of B-group peptides carrying the highest value of IgM antigens were selected for structural studies that may provide antigen specificity. Circular Dichroism (CD) spectra were measured for peptide secondary structure in the range of 190-260 nm. Experimental results show that P99 has pseudo α-helice and random coil structure. Homonuclear (COSY, TOCSY, NOESY) 2D-NMR experiments were carried out for NMR signal assignments and structure determination for P99. On the basis of these completely assigned NMR spectra and proton distance information, distance geometry (DG) and molecular dynamic (MD) were carried out to determine the structures of P99. The proposed structure was selected by comparisons between experimental NOE spectra and back-calculated 2D NOE results from determined structure showing acceptable agreement. The total Root-Mean-Square-Deviation (RMSD) value of P99 obtained upon superposition of all atoms were in the set range. The solution state P99 has mixed structure of pseudo α-helix and β-turn(Gln[9] to Thr[13]). These NMR results are well consistent with secondary structure from experimental results of circular dichroism. Structural studies based on NMR may contribute to the prevent oxidation studies of atherosclerosis and observed conformational characteristics of apo B-100 in LDL using monoclonal antibodies.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.2
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• pp.141-148
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• 2023

The thermodynamic performance of the electrochemical hydrogen compressor was analyzed to perform a comparative analysis with the performance of the mechanical compressor. The performance was analyzed through the applied current and the measured voltage value. The test results showed that the efficiency of the electrochemical hydrogen compressor was high in the low current density range. In addition, it was confirmed that the amount of increasing compress work of the electrochemical hydrogen compressor is smaller than that of the mechanical compressor. Therefore, it is expected to have higher efficiency than mechanical compression when compressed with a sufficiently high-pressure range.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2613-2620
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• 2023

Excellent thermal neutron absorption performance of boron expands the potential use of boron rich slag to prepare epoxy resin matrix nuclear shielding composites. However, shielding attenuation behaviors and mechanism of the composites against gamma rays are unclear. Based on the radiation protection theory, Phy-X/PSD, XCOM, and ⁶⁰Co gamma ray source were integrated to obtain the shielding parameters of boron rich slag/epoxy resin composites at 0.015-15 MeV, which include mass attenuation coefficient (µ_t), linear attenuation coefficient (µ), half value thickness layer (HVL), electron density (N_eff), effective atomic number (Z_eff), exposure buildup factor (EBF) and exposure absorption buildup factor (EABF).µ_t, µ, HVL, N_eff, Z_eff, EBF and EABF are 0.02-7 cm²/g, 0.04-17 cm^-1, 0.045-20 cm, 5-14, 3 × 10²³-8 × 10²³ electron/g, 0-2000, and 0-3500. Shielding performance is BS4, BS3, BS3, BS1 in descending order, but worse than ordinary concrete. µ and HVL of BS1-BS4 for ⁶⁰Co gamma ray is 0.095-0.110 cm^-1 and 6.3-7.2 cm. Shielding mechanism is main interactions for attenuation gamma ray by BS1-BS4 are elements with higher content or higher atomic number via Photoelectric Absorption at low energy range, and elements with higher content via Compton Scattering and Pair Production in Nuclear Field at middle and higher energy range.

• Korean Journal of Environment and Ecology
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• v.37 no.6
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• pp.439-449
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• 2023

This study was conducted to verify the role of forest roads in the extinction of large forest fires in Korea. The study area was the forest fire-damaged area of Gangneung City, Gangwon Special Self-Governing Province, in April 2023, which is one of the areas with the highest road density among the major forest fires that have occurred so far. The scope of the forest fire damage area was confirmed through on-site survey, and the intensity of the fire was carried out through Sentinel-2 satellite imagery analysis. After that, the relationship between the damage range and intensity and the forest road was examined. About 59.6 km of roads were built within 50 m from the boundary of the forest fire damage area, which can easily access the entire 149.1 ha of forest fire damaged area. The road density is as high as 168.9 m/ha. All forests that were fragmented by roads were fragmented into 83 places, and all of these forests could be judged to have spread by spotting fire. As a result of analyzing the distribution of damage intensity by distance from the road to see the extent of damage according to the ease of access of fire extinguishing vehicles, it was confirmed that the proportion of areas with low-intensity damage has increased sharply even from 75 m or more away from the road. The results of analyzing the distribution of damage intensity by altitude to see the extent of damage according to the ease of access of fire extinguishing showed that the proportion of areas with low-intensity damage increased as the altitude increased, while the proportion of areas with damage of more than strong intensity decreased as the altitude increased. It was confirmed that there is no data that roads inside or adjacent to forests in the forest fire area of Gangneung City are effective in extinguishing forest fires. These results are contrary to the logic that increasing the road density in forests is effective in extinguishing forest fires. In the case of this fire area in Gangneung City, the road density is 43 times higher than the current road density in Korea claimed by the Korea Forest Service of 3.9 m/ha. This study suggests that roads can be a hindrance to extinguishing forest fires.

• The Journal of Engineering Geology
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• v.12 no.2
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• pp.167-178
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• 2002

Properties of discontinuity for Seoul Granite in northeastern part of Seoul City were analyzed by dividing structural domains into Surak and Bulam Mtn. areas. Important parameters measured among several engineering properties of a rock during tunnel excavation and road construction are as follows: 1) Orientation of joint, 2) joint spacing, 3) joint density, and 4) uniaxial compressive strength. Orientation, spacing, and density of joints can be directly measured during field investigation using scanline survey, circle-inventory method, and window survey. Uniaxial compressive strength of the rock was calculated by a simple correlation equation although it is originally necessary to prepare core samples in measuring it. Major orientations of joints measured from both areas are 3 sets of joints with different orientations. In other words, they are 2 sets of orthogonal joint and 1 set of sheet joint that is dipping at low angle, and have very similar orientations in both areas. Joint densities in both areas range from 0.039 and 0.066/cm, and average joint length are between 1.30 and 4.52m. Average joint spacing also has values from 10.3cm up to 59.6cm, and shows significant difference along specific orientation of scanlines measured. Values of uniaxial compressive strength calculated on the basis of Schmidt hammer rebound values range from 217 to 335 MPa, which indicates very strong rock type by classification of wall strength.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.857-860
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• 2005

We reported 94 GHz, low conversion loss, and high isolation single balanced active-gate mixer based on 70 nm gate length InGaAs/InAlAs metamorphic high electron mobility transistors (MHEMTs). This mixer showed that the conversion loss and isolation characteristics were 2.5 ${\sim}$ 2.8 dB and under -30 dB, respectively, in the range of 93.65 ${\sim}$ 94.25 GHz. The low conversion loss of the mixer is mainly attributed to the high-performance of the MHEMTs exhibiting a maximum drain current density of 607 mA/mm, a extrinsic transconductance of 1015 mS/mm, a current gain cutoff frequency ($f_t$) of 330 GHz, and a maximum oscillation frequency ($f_{max}$) of 425 GHz. High isolation characteristics are due to hybrid ring coupler which adopted dielectric-supported air-gapped microstrip line (DAML) structure using surface micromachined technology. To our knowledge, these results are the best performance demonstrated from 94 GHz single balanced mixer utilizing GaAs-based HEMTs in terms of conversion loss as well as isolation characteristics.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.1
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• pp.49-54
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• 2011

In order to develop the methods for exposure assessment and find susceptibility markers for the workers who are exposed to low doses of toluene, xylene and other chemical in petroleum industries, we investigated the application of P-450 expression in human lymphocytes utilizing mouse monoclonal anti-rat CYP2B1/2, the levels of toluene and xylene in air and their metabolite levels in urine with the levels of expressed CYP2B1/2 proteins. The general characteristics such as age, smoking and drinking habit were no significant difference between the control and exposed workers, but the working durations and working hours were significantly different. Workers in exposed group were exposed to the mean of 2.1 ppm (range, 0.00-4.54) of toluene and 0.3 ppm (rang, 0.00-1.23) of xylene. The mean concentration of urinary hippuric acid was low and less than 1/5 of the biological exposure index recommended by the Ministry of Employment and Labor Korea. Methyl hippuric acid in urine was not detected in control and exposed workers. Also, there were no significant differences in the levels of the urinary metabolites between the control and exposed group. When chemiluminescence dot blottings were carried out utilizing mouse monoclonal antibody against CYP2B1/2, the strong density dots corresponding to a mouse monoclonal antibody was observed in the human lymphocytes from the exposed workers. These results suggested that the chemiluminescence dot blot assay for CYP of lymphocytes should be valuable for identifying CYP expression as biomarkers in the workers exposed to toluene and xylene.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.2
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• pp.49-56
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• 2007

MEMS-based storage is being developed as a new storage media. Due to its attractive features such as high-bandwidth, low-power consumption, high-density, and low cost, MEMS storage is anticipated to be used for a wide range of applications from storage for small handhold devices to high capacity mass storage servers. However, MEMS storage has vastly different physical characteristics compared to a traditional disk. First, MEMS storage has thousands of heads that can be activated simultaneously. Second, the media of MEMS storage is a square structure which is different from the platter structure of disks. This paper presents a new request scheduling algorithm for MEMS storage that makes use of the aforementioned characteristics. This new algorithm considers the parallelism of MEMS storage as well as the seek time of requests on the two dimensional square structure. We then extend this algorithm to consider the aging factor so that starvation resistance is improved. Simulation studies show that the proposed algorithms improve the performance of MEMS storage by up to 39.2% in terms of the average response time and 62.4% in terms of starvation resistance compared to the widely acknowledged SPTF (Shortest Positioning Time First) algorithm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.9
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• pp.613-620
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• 2016

In order to scrutinize the fluid conductivity effects on the electromagnetic flowmeter(EMF) characteristics, a small scale EMF was designed and fabricated. The measuring tube has a $3mm{\times}4mm$ rectangular cross-section, 9 mm length, and a $2mm{\times}3mm$ plate electrode and a ${\Phi}1.5mm$ point electrode. The design parameters, such as the magnetizing frequency and the number of coil turns, and the diameter were optimized. The EMF was tested with a gravimetric calibrator and showed good linearity in the range of 0 to $1.17{\times}10^{-5}m^3/s$. The fluid conductivity was varied between 3 and $11{\mu}S/cm$, and the magnitude of the flow signal was proportional to the fluid conductivity and the wetted area of the electrode. The design information and the test results provide flow measurement techniques for very low flowrate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.96-116
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• 2016

Sensing coverage is a fundamental issue for Wireless Sensor Networks (WSNs). Several coverage configuration protocols have been developed; most of them presume the availability of precise knowledge about each node location via GPS receivers. However, equipping each sensor node with a GPS is very expensive in terms of both energy and cost. On the other hand, several GPS-less localization algorithms that aim at obtaining nodes locations with a low cost have been proposed. Although their deep correlation, sensing coverage and localization have long been treated separately. In this paper, we analyze, design and evaluate a novel integrated framework providing both localization and coverage guarantees for WSNs. We integrate the well-known Coverage Configuration Protocol CCP with an improved version of the localization algorithm AT-Dist. We enhanced the original specification of AT-Dist in order to guarantee the necessary localization accuracy required by CCP. In our proposed framework, a few number of nodes are assumed to know their exact positions and dynamically vary their transmission ranges. The remaining sensors positions are derived, as accurately as possible, using this little initial location information. All nodes positions (exact and derived) are then used as an input for the coverage module. Extensive simulation results show that, even with a very low anchor density, our proposal reaches the same performance and efficiency as the ideal CCP based on complete and precise knowledge of sensors coordinates.