• Journal of the Microelectronics and Packaging Society
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• v.13 no.1 s.38
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• pp.37-42
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• 2006

The preparation and processing of PVP-gate insulators on the device performance have been studied in the fabrication of organic thin film transistors (OTFTs). One of polyvinyl series, poly-4-vinyl phenol(PVP) was used as a solute and propyleneglycol monomethyl etheracetate(PGMEA) as a solvent in the formation of organic gate solutions. The cross-linking of organic insulators was also attempted by adding the thermosetting material, poly (melamine-co-formaldehyde) as a hardener in the compounds. From the measurements of electrical insulating characteristics of metal-insulator-metal (MIM) samples, PVP-based insulating layers showed lower leakage current according to the increase of concentration of PVP and poly (melamine-co-formaldehyde) to PGMEA in the formation of organic solutions. The PVP(20 wt%) copolymer with composition of 20 wt% PVP to PGMEA and cross-linked PVPs in which 5 wt% and 10 wt% poly (melamine-co-formaldehyde) hardeners had been additional]y mixed into PVP(20 wt%) copolymers were used as gate dielectrics in the fabrication of OTFTs, respectively. In our experiments, the maximum field effect mobility of $0.31cm^2/Vs$ could be obtained in the 5 wt% cross-linked PVP(20 wt%) device and the highest on/off current ratio of $1.92{\times}10^5$ in the 10 wt% cross-linked PVP(20 wt%) device.

• KSBB Journal
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• v.19 no.3
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• pp.215-220
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• 2004

A variety of solid bases such as inorganic bases, basic anion exchange resins, and resin-bound bases were tested as a catalyst for racemization of (S)-naproxen 2,2,2-trifluoroethyl thioester in isooctane at 45$^{\circ}C$. Among the various bases, DIAIOM WA30, which is a weakly basic anion exchange resin with a tertiary amine based on a highly porous type styrene-divinylbenzene copolymer, showed the highest catalytic activity. The second-order interconversion constant of DIAION WA30 was 8.6${\times}$10$\^$-4/ mM$\^$-1/h$\^$-1/ and about 3 times higher than that of trioctylamine under the same conditions. The rate of DIAION WA30-catalyzed racemization decreased with increasing an amount of water added to the reaction medium. Lipase-catalyzed kinetic resolution of racemic naproxen 2,2,2-trifluoroethyl thioester was successfully carried out under in situ racemization of substrate with DIAION WA30 in isooctane at 45$^{\circ}C$. More than 60% conversion and 99% enantiomeric excess for the desired (S)-naproxen product were obtained. Furthermore, such a solid base catalyst could be easily separated and reused in contrast to trioctylamine.

• Journal of Conservation Science
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• v.31 no.2
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• pp.105-114
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• 2015

In this study, an advanced epoxy putty which was as a multi-purpose restoration material being used to restore missing parts in the artifact preservation treatment process was developed. For the purpose of addressing the issues including the workability issue resulting from high strength, the drooping issue resulting from long hardening time during work process and the issue of contaminating the surface of artifact resulting from stained material on tools or gloves, a property comparison was conducted with existing materials to examine the properties of restoration materials in the form of epoxy putty currently being frequently used. For the purpose of addressing the issues of existing materials and allowing the developed epoxy putty to have similar properties, two types of hardeners with different properties were selected to conduct property experiments. As for the hardeners, mercaptan type hardener and aliphatic amine type hardeners in the total of two types were selected for the development. The result showed that the two types were both in the form of paste and their hardening time of 5-10 minutes were about 3-10 times shorter than that of existing materials, thereby improving the work convenience. In terms of abrasion rate to increase workability, it was improved by about 3 times to allow effective and convenient use. As for the issue of contaminating the artifact surface during the process, white micro-balloon was added as filler to address the issue to reduce the oil ingredient to develop multi-purpose restoration material with low shrinkage & high workability in coloring, light weight and cutting force.

• Journal of Conservation Science
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• v.26 no.4
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• pp.445-458
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• 2010

The deterioration and structural damage such as exfoliation, cracks, and separation of painted layer on the wall paintings of Maitreya Hall in Geumsan-sa temple have been accelerated since it was re-positioned to the original place after the dismantling from the building in 1993. The examination of which result and analysis described in this study, is a preliminary survey for establishing conservation plan of the wall paintings. It aimed at the understanding of the physical and chemical characteristics of the materials applied in the 1993 conservation. The research focused on the south walls which displayed the worst condition compared to other walls. Samples for the examination for the understanding of micro-structure, chemical composition, cristalisation, and particle distribution, were collected for finishing, middle, and consolidated layers of the walls between pillars and the ones between brackets. Those samples were collected from separated fragments of the walls. The sample analysis displayed that: 1. the 1993 conservation used the similar type of weathered soil as the original for the finishing layer, and such soil and sand for the middle layer; 2. those walls are composed of a group of mineral particles which are relatively equal in size and shape and in their distribution; 3. the mineral particles were cohered forming solid aggregate due to the application of acrylic resin for the reinforcement on the wall. The main composition of crystalisation on the first and the second reinforcement layers of the back walls were lime plaster ($CaSO_4{\cdot}2H_2O$). The overall examination confirmed that the priority of the future conservation treatment should be given to the removal of the first and the second layers of reinforcement and the treatment on the back walls which were partially consolidated.

• Composites Research
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• v.24 no.6
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• pp.56-63
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• 2011

The objective of this study is to investigate appropriate bonding methods of solar cells in order to apply solar cells, which have been receiving particular attention as a renewable energy due to fossil energy depletion and environment issues, to composite structures. Back-contact solar cells with approximately 24.2% energy conversion efficiency were used in this study. Since silicon-based solar cells are mechanically fragile, the secondary-bonding methods using adhesive were examined in this study. The experiment was conducted with three kinds of bonding materials such as EVA film, Resin film and elastic adhesive. The performance of solar cells for three types of adhesives under mechanical loading on test specimens is conducted. In addition, the measuring equipment was designed to evaluate the performance of the solar cells under mechanical loading in real time and the fracture characteristics depending on bonding materials were evaluated. The reason decreasing solar cells efficiency were analyzed and considered by Fractography. The results show that the solar cell performance is largely affected by bonding techniques. Moreover, the bonding method using elastic adhesive shows best solar cell efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.35-42
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• 2019

Risk assessment and analysis for a medium-to-small sized chemical plant that manufactures a polyester resin by the process of batch-type condensation reaction was conducted using K-PSR technique which is one of the risk assessment methods used to implement the Process Safety Management System (PSM). K-PSR is a risk assessment technique developed by KOSHA to compensate for difficulties caused by the lack of infrastructure of medium-to-small sized chemical plants in the re-evaluation. To apply the K-PSR technique, the entire process of a selected chemical palnt was classified in two review sections, i.e., the condensation reaction process and the dilution/filtration process, and the potential risks of the process about these review sections were identified and classified based on the four guide-words (release, fire.explosion, process trouble, and injury). As the results of the research, refer to recommend of risk rating has been confirmed that non-destructive testing of old facilities and the preparation of LOTO procedures for the electrical equipments are necessary as specific measures to prevent the risk of release and fire.explosion. It was also shown that pressure gauges and thermometers should be installed on the hot-oil supply piping to minimize the process trouble, and exhausting hood should be installed to prevent potential injury.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.2
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• pp.67-73
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• 2019

In this study, to optimize the production and utilization of biogas for organic waste resources, the precision monitoring of on-site facilities and the energy balance by facility were analyzed, and the solutions for field problems were investigated, and the design and operation guidelines for pretreatment facilities and generators were presented. Gas pre-treatment is required to solve frequent failures and efficiency degradation in operation of high quality refining facilities, and processing processes such as desulfurization, dehumidification, deoxidization, dust treatment, volatile organic compounds, etc. Since these processes are substances that are also eliminated from the high-quality process, quantitative guidelines are not presented in the gas pretreatment process, but are suggested to operate during the processing process as a qualitative guideline. In particular, dust, siloxane, and volatile organic compounds are the main cause of frequent failure of high-quality processes if they are not removed from the gas pretreatment process. Design of the biogas high-quality process. The operation guidelines provide quality standards [Methane content (including propane) of 95% or more] with 90% or more utilization of the total gas generation, two systems, and a margin of 10% or more. It also proposed installing gas equalization tank, installing thermal automatic control system for controlling equalization of auxiliary fuel, installing dehumidification device at the back of high quality for removing moisture generated in the process of gas compression, installing heat-resisting facilities to prevent freezing of facilities in winter and reducing efficiency, and installing membrane facilities in particular.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.258-264
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• 2018

In this study, the improved performance of sprayed green soil was evaluated by incorporating functional additives. The optimal mixing ratio of the thickener and super-absorbent polymer, as an additive for moisture supply to the growth of plants within the range of mixing ratios that gives sufficient strength of green soil, was 5% and 1%, respectively. Using Portland cement as a main binder, the pH of the green soil was 9.1. To solve this alkali problem, the mixing proportion was improved so that the pH of the green soil was approximately 7.2 by mixing more than 10% of the chelate resin. The soil conductivity was measured to be 280 ~ 350mS/m under all the mixing conditions. This satisfied the criterion of less than 1000mS/m on the slope surface. As a result of measuring the soil hardness of the green soil prepared under the optimal mixing conditions of functional additives, it satisfied the criteria of 18 ~ 23mm when sprayed under a 1 bar pressure. The rebound rate was less than 15% when spraying green soil on a 75 % slope, and the hardness of the sprayed green soil was more than 18 mm.

• 한국사회정책
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• v.24 no.4
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• pp.185-222
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• 2017

The purpose of this study is to investigate the effect of labor market policy on fiscal soundness of welfare state. The analysis was carried out using cross-sectional panel data regression analysis, stepwise mediating effect analysis and system GMM designed by Baron and Kenny(1986) based on the data from 1985 to 2015 for 20 OECD countries. In setting up the analysis model, this study considers the interaction effect between active and passive labor market policies as well as the time sequence of the outcomes which have been overlooked in the previous studies. The result shows that labor market policies have significant impacts on the fiscal condition of welfare states, which is measured as the levels of national debt in this study. Especially the expenditure on active labor market programs has a positive effect on improving the fiscal soundness of welfare states by promoting the employment rate. In contrast, passive labor market programs expenditure is negatively associated with employment rate growth and it exacerbates the burden of national debt in the short-term. However, when active labor market programs and passive labor market programs are combined, the negative impacts by passive pabor market policies on the fiscal soundness of welfare states are off-set. Therefore this study addresses that although the expansion of the labor market policies can be inimical to the fiscal soundness of welfare states in the short-term, in the long run, they can have effective roles in securing and promoting the fiscal soundness of the welfare states by promoting the employment rate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.119-125
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• 2020

Research on high-attenuation concrete for the vibration reduction performance by mixing epoxy-based synthetic resins and aggregates is actively being conducted. The curing time of high-attenuation concrete is very short because water is not used, and the physical and dynamic properties are very excellent. therefore, it is expected to be widely used in building structures requiring reduction of interior-floor noise and vibration. Furthermore, A way to expand the applicability of the high-damping concrete mixed with polymer in the field of reinforcement material have been variously studied. In order to replace polymer concrete with ordirnary concrete and existing anti-vibration reinforcement material, it is necessary to review overall vibration reduction performance considering physical properties, dynamic properties, productivity and field applicability. In this study, the physical and dynamic properties of polymer concrete by epoxy mixing ratio compared with ordirnary concrete. As a result, the elastic modulus was similar. On the other hand, polymer concrete for the compressive, tensile, and flexural strengths was quite more excellent. In particular, the measured tensile strength of polymer concrete was 4-10 times higher than that of ordirnary concrete. it was a big difference, and the frequency response function and damping ratio was studied through modal test and finite element analysis model. The dynamic stiffness of polymer concrete was 20% greater than that of ordirnary concrete, and the damping ratio of polymer concrete was approximately 3 times more than that of ordirnary concrete.