• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.3
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• pp.362-370
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• 1995

Human plasma low density lipoprotein(LDL) is the main carrier for cholesterol, and recent studies suggest the normal LDL can be readily oxidized by free radical and not interact with LDL receptor. Lipoprotein pariticles are consisted of lipid andprotein, and fatty acids of lipoproteins are prone to oxidation. LDL particles readily undergo oxidative modification by copper. From the results, oxidized LDL altered its biological properties. A marked increase in the electrophoretic mobility of LDl on agarose gel indicated that negative surface charge of the LDL particles was increased. Also, the results from the HPLC showed that oxidized LDL was degraded into several polypeptides nonenzymatically. Degradation tests which measured the amount of 5-IAF labelled oxidized LDL were carried out by monocyte and hepatocyte cell culture. Hepatocyte cell culture of modified LDL did not show consistent pattern. However, binding rate of modified LDL with HMDM(human monocyte derived macrophage) was enhanced with oxidation, but was retarded by addition of antioxidants(hyaluronic acid, vitamin A, vitamin E). Also comparisons of oxidized-LDL, acetyl-LDL and MDA-LDL showed significant differences in the chemical properteis and binding affinity to HMDM. Thus, modificaition of normal LDL altered its biological properties.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.8
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• pp.17-24
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• 2004

Quantum effects in the poly-gate are analyzed in two dimensions using the density-gradient method, and their impact on the short-channel effect of double-gate MOSFETs is investigated. The 2-D effects of quantum mechanical depletion at the gate to sidewall oxide is identified as the cause of large charge-dipole formation at the corner of the gate. The bias dependence of the charge dipole shows that the magnitude of the dipole peak-value increases in the subthreshold region and there is a large difference in carrier and potential distribution compared to the classical solution. Using evanescent-nude analysis, it is found that the quantum effect in the poly-gate substantially increases the short-channel effect and it is more significant than the quantum effect in the Si film. The penetration of potential contours into the poly-gate due to the dipole formation at the drain side of the gate corner is identified as the reason for the substantial increase in short-channel effects.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.379-379
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• 2010

Recent technical advances in OLEDs (organic light emitting devices) requires more and more the improvement in low operation voltage, long lifetime, and high luminance efficiency. Inverted top emission OLEDs (ITOLED) appeared to overcome these problems. This evolved to operate better luminance efficiency from conventional OLEDs. First, it has large open area so to be brighter than conventional OLEDs. Also easy integration is possible with Si-based driving circuits for active matrix OLED. But, a proper buffer layer for carrier injection is needed in order to get a good performance. The buffer layer protects underlying organic materials against destructive particles during the electrode deposition and improves their charge transport efficiency by reducing the charge injection barrier. Hexaazatriphenylene-hexacarbonitrile (HAT-CN), a discoid organic molecule, has been used successfully in tandem OLEDs due to its high workfunction more than 6.1 eV. And it has the lowest unoccupied molecular orbital (LUMO) level near to Fermi level. So it plays like a strong electron acceptor. In this experiment, we measured energy level alignment and hole current density on inverted OLED structures for hole injection. The normal film structure of Al/NPB/ITO showed bad characteristics while the HAT-CN insertion between Al and NPB greatly improved hole current density. The behavior can be explained by charge generation at the HAT-CN/NPB interface and gap state formation at Al/HAT-CN interface, respectively. This result indicates that a proper organic buffer layer can be successfully utilized to enhance hole injection efficiency even with low work function Al anode.

• Journal of Surface Science and Engineering
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• v.56 no.4
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• pp.265-272
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• 2023

Photoelectrochemical (PEC) water splitting is one of the promising methods for hydrogen production by solar energy. Iron oxide has been effectively investigated as a photoelectrode material for PEC water splitting due to its intrinsic property such as short minority carrier diffusion length. However, iron oxide has a low PEC efficiency owing to a high recombination rate between photoexcited electrons and holes. In this study, we synthesized nanoporous structured iron oxide by anodization to overcome the drawbacks and to increase surface area. The anodized iron oxide was annealed in Ar atmosphere with different purging times. In conclusion, the highest current density of 0.032 mA/cm² at 1.23 V vs. RHE was obtained with 60 s of pursing for iron oxide(Fe-60), which was 3 times higher in photocurrent density compared to iron oxide annealed with 600 s of pursing(Fe-600). The resistances and donor densities were also evaluated for all the anodized iron oxide by electrochemical impedance spectra and Mott-Schottky plot analysis.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.1
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• pp.31-39
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• 2014

For mobile application, semiconductor packages are increasingly moving toward high density, miniaturization, lighter and multi-functions. Typical wafer level packages (WLP) is fan-in design, it can not meet high I/O requirement. The fan-out wafer level packages (FOWLPs) with reconfiguration technology have recently emerged as a new WLP technology. In FOWLP, warpage is one of the most critical issues since the thickness of FOWLP is thinner than traditional IC package and warpage of WLP is much larger than the die level package. Warpage affects the throughput and yield of the next manufacturing process as well as wafer handling and fabrication processability. In this study, we investigated the characteristics of warpage and main parameters which affect the warpage deformation of FOWLP using the finite element numerical simulation. In order to minimize the warpage, the characteristics of warpage for various epoxy mold compounds (EMCs) and carrier materials are investigated, and DOE optimization is also performed. In particular, warpage after EMC molding and after carrier detachment process were analyzed respectively. The simulation results indicate that the most influential factor on warpage is CTE of EMC after molding process. EMC material of low CTE and high Tg (glass transition temperature) will reduce the warpage. For carrier material, Alloy42 shows the lowest warpage. Therefore, considering the cost, oxidation and thermal conductivity, Alloy42 or SUS304 is recommend for a carrier material.

• Resources Recycling
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• v.13 no.1
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• pp.14-21
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• 2004

Spent catalysts containing platinum were generated in petroleum refinery and other chemical industries. The reclamation of platinum metals from such wastes has long been attempted in view of their rare, expensive and indispensable nature. In this study, the recovery of platinum from petroleum catalysts was attempted by a method consisting mainly of dissolving alumina carrier with sulfuric acid thereby concentrating insoluble platinum. Also, platinum dissolved partially in sulfuric acid was recovered by a cementation method using aluminum metal as a reductive agent. The effect of temperature, time, concentration of sulfuric acid, and pulp density on the dissolution of carrier was investigated. When the carrier of platinum catalyst was $\Upsilon-Al_2$O$_3$ about 95% alumina was dissolved in 6.0 M sulfuric acid at $100^{\circ}C$ for 2 hours. When the carrier was the mixture of $\Upsilon-Al_2$$O_3$ and $\alpha$-$Al_2$$O_3$ about 92% was dissolved after 4 hours. As a result, more than 99% of platinum could be recovered by this method and aluminum sulfate was also obtained as byproduct.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.279-285
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• 2017

The study on 'support for V2V(Vehicle to Vehicle) services based on LTE sidelink' has been carried out in 3GPP RAN working group. The conventional LTE sidelink technology is not adequate for high speed V2V communications because the conventional DM-RS(Demodulation Reference signal) structure is developed for pedestrian environment. While the typical speed of pedestrian environment is 3km/h, that of V2V communications is 120 km/h and the information on channel estimation is not sufficient with legacy DM-RS structure. In this paper, improved DM-RS structures for V2V communications that have rapid channel variation are introduced and the performance of channel estimation accuracy is analyzed. Simulation results show that the performance improvement of channel estimation can be achieved based on extended sub-carrier spacing structure resulted from reduced inter-carrier interference. However, the extended sub-carrier spacing requires the longer cyclic prefix and higher overhead. As a results of considerations on DM-RS modification, the sub-carrier spacing is maintained and the high density of DM-RS is applied for V2V communications.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.2
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• pp.100-116
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• 2002

There are several purpose to introduce microorganism into the Soil. The major purpose is to promote plant growth and inhibit plant pathogens. The model example is to put in nitrogen fixing symbiotic bacteria, Pythium and Rhizobium. In order to achieve the intended goal, the introduced microorganism should survive and colonize with sufficient density. The survival of introduced microorganism depend upon biotic and abiotic factors. Predation and competition are important among biotic factor. Water tension, organic carbon, inorganic nutrients(N, P), pH are important factor among abiootic factor. Soil texture and distribution of soil pore are also important in the survival and colonization of introduced microorganism. Selection by soil ecosystem for inoculant is a crucial factor for colonization. Good example are control of autochtonous microorganism and the introduction of surfactant biodegrading Pseudomonas. Sometimes, carriers such as peat and montmorillonite can be added to help colonization. Carriers can protect introduced microorganism by supplying protective microhabitat. Organic polymer is also used as a carrier to immobilize bacteria or industrial enzymes. Examples of these carrier are calcium alginate, agarose and k-carrageenan. The function of these carrier is to provide microhabitat and help colonization for introduced microorganism.

• Pediatric Infection and Vaccine
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• v.7 no.1
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• pp.143-151
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• 2000

Purpose : The accuracy of bacteriologic diagnosis of beta-hemolytic streptococcal pharyngotonsillitis depends on the degree of carrier rate in that area where the throat swabs are obtained and the evaluation of serological T typing as an epidemiologic marker is important to understand epidemiology of streptococcal infection. The purpose of this study is to know the carrier rates of group A streptococcus in normal children form four different areas and to find out the epidemiologic characteristic in distribution of the serotypes for 3 years. Method : Throat swabs were obtained from the tonsillar fossa of normal school children in four different areas(Uljin, Seoul, Osan, Kunsan) from March to May 1996, in Uljin in April 1997, and in Uljin in April 1998. The samples were plated on a 5% sheep blood agar plate and incubated overnight at $37^{\circ}C$ before examination for the presence of beta-hemolytic colonies. All isolated beta-hemolytic streptococcus were grouped and serotyped by T agglutination. Results : The carrier rate of beta-hemolytic streptococci and group A streptococci in 1996 were 27.6%, 18.6% at Uljin; 16.4%, 2.7% at Seoul; 33.0%, 26.0% at Osan; 20.0%, 12.3% at Kunsan, respectively. Among 1,192 normal school children from 4 different areas, we obtained 179 strains of group A streptococci. Fifty two percent of the strains were typable by T agglutination in 1996. Common T-type in 1996 were NT, T1, T3, T2 at Uljin; T12, T25 at Seoul; NT, T6, T28 at Osan; T25, T4, NT, T5 at Kunsan, in decreasing order, respectively. At Uljin, T1, T3, T25 accounted for 69% of strains in 1996, T1, T12, T25 accounted for 70% in 1997, and T12, T4 accounted for 88% in 1998. Conclusion : Higher carrier rates were found in Uljin and Osan, where there are a lower population density with scanty of medical facilities compared with another areas. We supposed that low carrier rates is likely to be related to antibiotic abuse or some epidemiologic factor. The periodic and seasonal serotyping analysis is important in monitoring and understanding the epidemiologic patterns of group A streptococci.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.2
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• pp.110-117
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• 2000

Relationship between monoclonal antibody (MAb) productivity and growth rate, and effects of high cell density on MAb production rate increased with increasing specifis growth rate in both suspended and immobilized continuous cultures indicate a positively growth-associated relationship between MAb productivity and growth rate. moreover, the specific production rate was higher in the immobilized cell culture than that in suspended one at all dilution rates. In order to clarify these phenomana, MAb mPNA experession and cell cycle distribution were investigated in bacth cultures with immobilized cells and suspended cells. RT-PCR was used for observation of MAb mRNA expression and a two-color bromodeoxyuridine (BrdU)/propidium iodide (PI) flow cytometry method for determination of cell cycle distribution. The results revealed that MAb nRNA expression until dead phase, which was longer than in suspended cell. The cell cycle distribution patterns were observed almost the same for both immobilized and suspended cells. Such results may imply that a high cell density state has positive influence on the mRNA expression and on growth-associated Mab productivity of T0405 cells.