• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.5
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• pp.217-222
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• 2023

The purpose of this paper was to synthesize a polymer organic hard mask that simplifies the manufacturing process, reduces process time significantly, and thereby lowers manufacturing costs. The results of measuring residual metals through vapor refining showed that 9-Naphthalen-1-ylcarbazole(9-NC) measured 101.75ppb in the 4th zone, 2-Naphthol (2-NA) measured 306.98ppb in the 5th zone, and 9-Fluorenone(9-F) measured between 129.05ppb across the 4th and 5th zones. After passing through a filtration system, the synthesized organic hard mask measured residual metals in the range of 9 to 7ppb. Additionally, the thermal analysis indicated a decrease of 2.78%, a molecular weight of 942, carbon content of 89.74%, and a yield of 72.4%. The etching rate was measured at an average of 18.22Å/s, and the coating thickness deviation was averaged at 1.19. For particle sizes below 0.2㎛ in the organic hard mask, no particles were observed. By varying the coating speed at 1,000, 1,500, and 1,800rpm and measuring the resulting coating thickness, the shrinkage rate ranged from 17.9% to 20.8%. The coating results demonstrated excellent adhesion to SiON, and it was evident that the organic hard mask was uniformly applied.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.77-77
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• 2016

Thin films synthesized by plasma processes have been widely applied in a variety of industrial sectors. The structure control of thin film is one of prime factor in most of these applications. It is well known that the structure of this film is closely associated with plasma parameters and species of plasma which are electrons, ions, radical and neutrals in plasma processes. However the precise control of structure by plasma process is still limited due to inherent complexity, reproducibility and control problems in practical implementation of plasma processing. Therefore the study on the fundamental physical properties that govern the plasmas becomes more crucial for molecular scale control of film structure and corresponding properties for new generation nano scale film materials development and application. The thin films are formed through nucleation and growth stages during thin film depostion. Such stages involve adsorption, surface diffusion, chemical binding and other atomic processes at surfaces. This requires identification, determination and quantification of the surface activity of the species in the plasma. Specifically, the ions and neutrals have kinetic energies ranging from ~ thermal up to tens of eV, which are generated by electron impact of the polyatomic precursor, gas phase reaction, and interactions with the substrate and reactor walls. The present work highlights these aspects for the controlled and low-temperature plasma enhanced chemical vapour disposition (PECVD) of Si-based films like crystalline Si (c-Si), Si-quantum dot, and sputtered crystalline C by the design and control of radicals, plasmas and the deposition energy. Additionally, there is growing demand on the low-temperature deposition process with low hydrogen content by PECVD. The deposition temperature can be reduced significantly by utilizing alternative plasma concepts to lower the reaction activation energy. Evolution in this area continues and has recently produced solutions by increasing the plasma excitation frequency from radio frequency to ultra high frequency (UHF) and in the range of microwave. In this sense, the necessity of dedicated experimental studies, diagnostics and computer modelling of process plasmas to quantify the effect of the unique chemistry and structure of the growing film by radical and plasma control is realized. Different low-temperature PECVD processes using RF, UHF, and RF/UHF hybrid plasmas along with magnetron sputtering plasmas are investigated using numerous diagnostics and film analysis tools. The broad outlook of this work also outlines some of the 'Grand Scientific Challenges' to which significant contributions from plasma nanoscience-related research can be foreseen.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1702-1705
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• 2016

We propose a novel hydrogen-reduced p-type amorphous silicon oxide buffer layer between $TiO_2$ antireflection layer and p-type silicon window layer of silicon thin film solar cells. This new buffer layer can protect underlying the $TiO_2$ by suppressing hydrogen plasma, which could be made by excluding $H_2$ gas introduction during plasma deposition. Amorphous silicon oxide thin film solar cells with employing the new buffer layer exhibited better conversion efficiency (8.10 %) compared with the standard cell (7.88 %) without the buffer layer. This new buffer layer can be processed in the same p-chamber with in-situ mode before depositing main p-type amorphous silicon oxide window layer. Comparing with state-of-the-art buffer layer of AZO/p-nc-SiOx:H, our new buffer layer can be processed with cost-effective, much simple process based on similar device performances.

• Transactions on Electrical and Electronic Materials
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• v.12 no.5
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• pp.218-221
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• 2011

We modified the optical properties of the $CuInS_2$ nanocrystal (NC) by alloying. Nanocrystals (NCs) with alloyed cores were synthesized by refluxing the as-synthesized $CuInS_2$ NCs with a mixture of cadmium acetate, zinc acetate and palmitic acid. The shift in emission wavelength of the NCs after shell layer formation was minimized by alloying. The photoluminescence (PL) spectra showed significant reduction of emission intensity. A detailed study on the emission process of NCs implies that the formation of shell layers with small lattice mismatch minimized the mismatch strain generated from the shell layers in contrast to core alloyed NCs. In particular, time-resolved PL spectra of the NCs showed a significant increase in the lifetime of excited carriers by modifying the band alignment of the NCs by modifying the shell composition.

• Computers and Concrete
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• v.18 no.6
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• pp.1065-1082
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• 2016

The main aim of this study is to predict the compressive and flexural strengths of self-compacting mortar (SCM) containing $nano-SiO_2$, $nano-Fe_2O_3$ and nano-CuO using wavelet-based weighted least squares-support vector machines (WLS-SVM) approach which is called WWLS-SVM. The WWLS-SVM regression model is a relatively new metamodel has been successfully introduced as an excellent machine learning algorithm to engineering problems and has yielded encouraging results. In order to achieve the aim of this study, first, the WLS-SVM and WWLS-SVM models are developed based on a database. In the database, nine variables which consist of cement, sand, NS, NF, NC, superplasticizer dosage, slump flow diameter and V-funnel flow time are considered as the input parameters of the models. The compressive and flexural strengths of SCM are also chosen as the output parameters of the models. Finally, a statistical analysis is performed to demonstrate the generality performance of the models for predicting the compressive and flexural strengths. The numerical results show that both of these metamodels have good performance in the desirable accuracy and applicability. Furthermore, by adopting these predicting metamodels, the considerable cost and time-consuming laboratory tests can be eliminated.

• Journal of Ginseng Research
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• v.30 no.3
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• pp.112-116
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• 2006

To investigate the protective effect of saponin from red ginseng extract, 2,3,7,8-tetrachlorodibenzo--dioxin (TCDD) was exposed to female guinea pigs and then femur weights was measured. Forty eight female guinea pigs ($820{\pm}25\;g$) were divided into 6 groups. Normal control group (NC) received vehicle and saline; only TCDD-treated group (TT) received TCDD ($5.0\;{\mu}g/kg$, single dose) intraperitoneally; pretreated group of saponin 10 (PE 10) received 10 mg/kg of saponin i.p. for 4 weeks from 1 week before TCDD-exposure; pretreated group of saponin 20 (PE 20) also received 20 mg/kg of saponin i.p. for 4 weeks from 1 week before TCDD-exposure. While, post-treated group of saponin 10 (CE 10) received 10 mg/kg of saponin i.p for 3 weeks after TCDD-exposure. Post-treated group of saponin 20 (CE 20) received 20 mg/kg saponin i.p for 3 weeks after TCDD-exposure. Body weight of TT group was significantly decreased after TCDD-exposure. However, body weight in all saponin-treated groups increased throughout the experimental period, although the increasing rate was slower than that of NC group. Body weights of PE 10 and 20 groups showed more higher increase than those of CE groups during the experimental period. Decrease of femur weights in female guinea pigs by TCDD intoxification was significantly recovered by the saponin treatment. Decrease of $Ca^{2+}$ level of femurs in female guinea pigs exposed TCDD also recovered by the treatment of saponin from red ginseng extract. Especially, PE20 group showed the highest increase of the $Ca^{2+}$ level in femur among the saponin treated groups. These results suggest that ginseng saponin might be a useful protective agent against femur damage caused to decrease of $Ca^{2+}$ by TCDD.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.181-189
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• 2012

We developed a new high-yield synthesis method of free-standing germanium nanocrystals (Ge NCs) by means of the gas-phase photolysis of tetramethyl germanium in a closed reactor using an Nd-YAG pulsed laser. Size control (5-100 nm) can be simply achieved using a quenching gas. The $Ge_{1-x}Si_x$ NCs were synthesized by the photolysis of a tetramethyl silicon gas mixture and their composition was controlled by the partial pressure of precursors. The as-grown NCs are sheathed with thin (1-2 nm) carbon layers, and well dispersed to form a stable colloidal solution. Both Ge NC and Ge-RGO hybrids exhibit excellent cycling performance and high capacity of the lithium ion battery (800 and 1100 mAh/g after 50 cycles, respectively) as promising anode materials for the development of high-performance lithium batteries. This novel synthesis method of Ge NCs is expected to contribute to expand their applications in high-performance energy conversion systems.

• Health Policy and Management
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• v.27 no.4
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• pp.315-323
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• 2017

Background: This study was purposed to analyze the effect of spatial accessibility to the psychiatry department in general hospital on the outpatient visit of mental patients. Methods: Data was provided from the Statistics Korea and Statistical Geographic Information Service, National Health Insurance Service, Health Insurance Review and Assessment Service, and Korea Transport Institute in 2015. The study regions were 103 administrative regions such as Si and Gu. The 103 regions had at least one general hospitals with a psychiatry department. The number of outpatient visit of mental patients in regions was used as the dependent variable. Spatial accessibility to mental general hospital was used as the independent variable. Control variables included such as demographic, economic, and health medical factors. This study used network analysis and multi-variate regression analysis. Network analysis by ArcGIS ver. 10.0 (ESRI, Redlands, CA, USA) was used to evaluate the average travel time and travel distance in Korea. Multi-variate regression analysis was conducted by SAS ver. 9.4 (SAS Institute Inc., Cary, NC, USA). Results: Travel distance and time had significant effects on the number of outpatient visits in mental patients in general hospital. Average travel time and travel distance had negative effects on the number of visits. Variables such as (number of total population, percentage of aged population over 65, and number of mental general hospital) had significant effects on the number of visit in mental patients. Conclusion: Health policy makers will need to consider the spatial accessibility to the mental healthcare organization in conducting regional health planning.

• Molecules and Cells
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• v.37 no.7
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• pp.540-546
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• 2014

Several types of genetic and epigenetic regulation have been implicated in the development of drug resistance, one significant challenge for cancer therapy. Although changes in the expression of non-coding RNA are also responsible for drug resistance, the specific identities and roles of them remain to be elucidated. Long non-coding RNAs (lncRNAs) are a type of ncRNA (> 200 nt) that influence the regulation of gene expression in various ways. In this study, we aimed to identify differentially expressed lncRNAs in 5-fluorouracil-resistant colon cancer cells. Using two pairs of 5-FU-resistant cells derived from the human colon cancer cell lines SNU-C4 and SNU-C5, we analyzed the expression of 90 lncRNAs by qPCR-based profiling and found that 19 and 23 lncRNAs were differentially expressed in SNU-C4R and SNU-C5R cells, respectively. We confirmed that snaR and BACE1AS were down-regulated in resistant cells. To further investigate the effects of snaR on cell growth, cell viability and cell cycle were analyzed after transfection of siRNAs targeting snaR. Down-regulation of snaR decreased cell death after 5-FU treatment, which indicates that snaR loss decreases in vitro sensitivity to 5-FU. Our results provide an important insight into the involvement of lncRNAs in 5-FU resistance in colon cancer cells.

• Biomedical Science Letters
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• v.9 no.1
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• pp.51-58
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• 2003

This study was carried out to investigate the preventive and therapeutic effect of Panax ginseng water extract (PG-WE) on the toxicity induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), one of the most notorious toxic environmental pollutants belonging to the group of polyhalogenated aromatic hydrocarbons. Normal control (NC) group guinea pigs (180~200 g) received vehicle and saline, and TCDD-treated (TT) group was given TCDD and saline. P100 and P200 group animals received PG-WE for 28 days since 1 week before TCDD exposure at daily doses of 100 mg/kg b.w. and/or 200 mg/kg b.w., respectively. C100 and C200 group received PG-WE for 14 days starting 1 week after TCDD-exposure. Toxicity was induced by a single intraperitoneal injection of TCDD (1 $\mu\textrm{g}$/kg b.w.). Abnormal increase in AST and ALT activities in TT group was significantly improved by the administration of PC-WE. Microscopically, there were mild to moderate swelling of hepatocytes, hyperchromatism of individual cells, acidophilic cytoplasm and cytoplasm vacuolation of some hepatocytes, slight to moderate variations of staining density, occasional single cell necrosis, variable size and shape of some hepatocytes, small groups of degenerating hepatocytes surrounded by mononuclear cells, dilated sinusoids of centrilobular zone and some loss of lobular architecture in TT group liver. From these results, we could find the protective and therapeutic role of PG-WE in TCDD-induced liver toxicity by examining the blood chemical parameters and histopathological observation.