• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.5
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• pp.368-374
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• 2016

This paper presents an experimental study on an electrical circuit model of the TiO2-based nano-wired memristor device for neuromophic applications. The electrical circuit equivalent model of the proposed memristor device consists of several electronics components and some passive devices including operational amplifiers, multipliers, resistors and capacitors. In order to verify the proposed design, both of simulation (using PSPICE) as well as hardware implementation were performed for the analysis of the memristor circuit with time waveforms, frequency spectra, I-V curves and power curves. The gained results from the measured data showed a good agreement with the simulation result that confirm the proposed idea.

• Journal of Environmental Policy
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• v.12 no.1
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• pp.101-123
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• 2013

This research aims to find out the existence of considerable induced effect that the conventional I-O model cannot. First, we construct an environmental Social Accounting Matrix for Korea by combining statistics on the Korean GDP and I-O with physical data on the fossil energy consumption and $CO_2$ emissions. The impacts of productive activities on fossil energy consumption and $CO_2$ emissions are evaluated by calculating the e-SAM multipliers. By applying decomposition technique further, we get direct, indirect, and induced effects of production activities by industry. The result of decomposing the e-SAM shows that while the direct effect of the electricity industry is large, its indirect effect is very small. In the case of the primary metal industry, both the direct and the indirect influence of this industry were very large. On the contrary, in case of the service industry, the induced effect of fossil energy consumption was as high as 50% of the gross effect. These results suggest that different energy policies should be established for different industries. Also, the findings show the e-SAM model is better than I-O model in analyzing implications of policies on energy use in the economy.

• Journal of Forest and Environmental Science
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• v.12 no.1
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• pp.37-44
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• 1996

Two dilignols composed of ${\beta}$-O-4 structure, a important substructure compound in lignin, was synthesized in high yield in a series of the synthetic studies of lignin model compounds. The dimers were identified with $^1H$ and $^{13}C$-NMR and Mass spectroscopy. The important compound of among them, the final synthetic compound [IV].is called 1-(3,4-dimethoxyphenyl)-2-(2'-methoxy-4'-hydroxymethylphenoxy)-propanediol-l,3. This dimeric lignin model compounds should be usefull for the studies of lignin reactions such as pulping, bleaching, pyrolysis, hydrogenolysis, oxidation, reduction, biodegradation, and chemical utilization.

• Nuclear Engineering and Technology
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• v.41 no.7
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• pp.875-884
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• 2009

We present three nuclear/hydrogen-related R&D activities being performed at KAIST: air-ingressed LOCA analysis code development, gas turbine analysis tool development, and hydrogen-production system analysis model development. The ICE numerical technique widely used for the safety analysis of water-reactors is successfully implemented into GAMMA, with which we solve the basic equations for continuity, momentum conservation, energy conservation of the gas mixture, and mass conservation of 6 species (He, N2, O2, CO, CO2, and H2O). GAMMA has been extensively validated using data from 14 test facilities. We developed a tool to predict the characteristics of HTGR helium turbines based on the throughflow calculation with a Newton-Raphson method that overcomes the weakness of the conventional method based on the successive iteration scheme. It is found that the current method reaches stable and quick convergence even under the off-normal condition with the same degree of accuracy. The dynamic equations for the distillation column of HI process are described with 4 material components involved in the HI process: H2O, HI, I2, H2. For the HI process we improved the Neumann model based on the NRTL (Non-Random Two-Liquid) model. The improved Neumann model predicted a total pressure with 8.6% maximum relative deviation from the data and 2.5% mean relative deviation, and liquid-liquid-separation with 9.52% maximum relative deviation from the data.

• Korean Journal of Materials Research
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• v.34 no.3
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• pp.152-162
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• 2024

In this study, we introduce a novel TiN/Ag embedded TiO₂/FTO resistive random-access memory (RRAM) device. This distinctive device was fabricated using an environmentally sustainable, solution-based thin film manufacturing process. Utilizing the peroxo titanium complex (PTC) method, we successfully incorporated Ag precursors into the device architecture, markedly enhancing its performance. This innovative approach effectively mitigates the random filament formation typically observed in RRAM devices, and leverages the seed effect to guide filament growth. As a result, the device demonstrates switching behavior at substantially reduced voltage and current levels, heralding a new era of low-power RRAM operation. The changes occurring within the insulator depending on Ag contents were confirmed by X-ray photoelectron spectroscopy (XPS) analysis. Additionally, we confirmed the correlation between Ag and oxygen vacancies (V_o). The current-voltage (I-V) curves obtained suggest that as the Ag content increases there is a change in the operating mechanism, from the space charge limited conduction (SCLC) model to ionic conduction mechanism. We propose a new filament model based on changes in filament configuration and the change in conduction mechanisms. Further, we propose a novel filament model that encapsulates this shift in conduction behavior. This model illustrates how introducing Ag alters the filament configuration within the device, leading to a more efficient and controlled resistive switching process.

• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.122-135
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• 2018

Listeriolysin O (LLO), one of the most immunogenic proteins of Listeria monocytogenes and its main virulence factor, mediates bacterial escape from the phagosome of the infected cell. Thus, its expression in a nonpathogenic bacterial host may enable effective delivery of heterologous antigens to the host cell cytosol and lead to their processing predominantly through the cytosolic MHC class I presentation pathway. The aim of this project was to characterize the delivery of a model antigen, chicken egg ovalbumin (OVA), to the cytosol of dendritic cells by recombinant Bacillus subtilis vegetative cells expressing LLO. Our work indicated that LLO produced by non-sporulating vegetative bacteria was able to support OVA epitope presentation by MHC I molecules on the surface of antigen presenting cells and consequently influence OVA-specific cytotoxic T cell activation. Additionally, it was proven that the genetic context of the epitope sequence is of great importance, as only the native full-sequence OVA fused to the N-terminal fragment of LLO was sufficient for effective epitope delivery and activation of $CD8^+$ lymphocytes. These results demonstrate the necessity for further verification of the fusion antigen potency of enhancing the MHC I presentation, and they prove that LLO-producing B. subtilis may represent a novel and attractive candidate for a vaccine vector.

• The KIPS Transactions:PartA
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• v.9A no.2
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• pp.147-162
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• 2002

Multi-processor system with fast I/O devices improves processing performance and reduces the bottleneck by I/O concentration. In the system, the Performance influenced by shared memory used for exchanging data between processors varies with configuration and utilization. This paper suggests a prediction model for buffer and shared memory optimization under interrupt recognition method using mailbox. Ethernet (IEEE 802.3) packets are used as the input of system and the amount of utilized memory is measured for different network bandwidth and burstiness. Some empirical studies show that the amount of buffer and shared memory varies with packet concentration rate as well as I/O bandwidth. And the studies also show the correlation between two memories.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.176-176
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• 2003

The effects of oxide thickness and gate length of MgO/GaN metal oxide semiconductor field effect transistors (MOSFETs) on I-V, threshold voltage and breakdown voltage characteristics were examined using a drift-diffusion model. The saturation drain current scales in an inverse logarithmic fashion with MgO thickness and is < 10$^{-3}$ A.${\mu}{\textrm}{m}$$^{-1}$ for 0.5 ${\mu}{\textrm}{m}$ gate length devices with oxide thickness > 600 $\AA$ or for all 1 ${\mu}{\textrm}{m}$ gate length MOSFETs with oxide thickness in the range of >200 $\AA$. Gate breakdown voltage is > 100 V for gate length >0.5 ${\mu}{\textrm}{m}$ and MgO thickness > 600 $\AA$. The threshold voltage scales linearly with oxide thickness and is < 2 V for oxide thickness < 800 $\AA$ and gate lengths < 0.6 ${\mu}{\textrm}{m}$. The GaN MOSFET shows excellent potential for elevated temperature, high speed applications.

• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.507-522
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• 2015

In this study, some of the model verification results of STREAM (Spatio-Temporal River-basin Ecohydrology Analysis Model), a newly-developed hybrid watershed model, are presented for the runoff processes of nonpoint source pollution. For verification study of STREAM, the model was applied to a test watershed and a sensitivity analysis was also carried out for selected parameters. STREAM was applied to the Mankyung River Watershed to review the applicability of the model in the course of model calibration and validation against the stream flow discharge, suspended sediment discharge and some water quality items (TOC, TN, TP) measured at the watershed outlet. The model setup, simulation and data I/O modules worked as designed and both of the calibration and validation results showed good agreement between the simulated and the measured data sets: NSE over 0.7 and $R^2$ greater than 0.8. The simulation results also include the spatial distribution of runoff processes and watershed mass balance at the watershed scale. Additionally, the irrigation process of the model was examined in detail at reservoirs and paddy fields.

• The Journal of Korean Medicine
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• v.30 no.5
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• pp.61-76
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• 2009

Background: Membranous nephropathy (MN) is the most common cause of adult nephrotic syndrome worldwide and has been defined as granular subepithelial deposition of immune complexes along the glomerular basement membrane (GBM). MN has few known treatments and gives rise to side effects under treatment with steroids and immunosuppressives. Objective: The purpose of this experimental study was to demonstrate the effects of Scutellariae Radix extract (SRE) treatment on MN mouse model induced by cBSA. Methods: We divided mice into 4 groups. The Normal group had no treatment. We induced MN mouse model to the other 3 groups by injecting cBSA into the abdominal cavity. The control group was treated with cBSA (10 mg/kg, i.p.) only. The second group, 'SRE-250', was treated with cBSA (10 mg/kg, i.p.) and SRE (250 mg/kg, p.o.). The third group, 'SRE-500', was treated with cBSA (10 mg/kg, i.p.) and SRE (500 mg/kg, p.o.). After cBSA and SRE treatment for 4 weeks, gain in body weight, 24hrs proteinuria, serum albumin, total cholesterol, triglyceride, BUN and creatinine of all groups were measured. TNF-$\alpha$, IL-6, IL-1$\beta$, IL-10, IFN-$\gamma$, IgA, IgM and IgG levels of all groups were gauged. H&E staining and electron microscopy of the kidney were observed. Results: SRE showed significant decrease in the 24hrs proteinuria, serum triglyceride, BUN, TNF-$\alpha$, IL-6, serum IgA, IgM and IgG levels compared with the control group. SRE showed increase in the serum IL-10 and IFN-$\gamma$ levels compared with control on RT-PCR. SRE considerably decreased in the thickening of the GBM on H&E staining and deposition of electron-density on electron microscopy of the kidney compared with the control. Conclusions: According to the above results, it is suggested that SRE decreases the symptoms of MN induced by cBSA in mouse model. Therefore, SRE seems to be applicable to MN in clinical practice.