• Fibers and Polymers
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• v.3 no.2
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• pp.55-59
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• 2002

The thermal reaction of acetoacetanilide in the presence of aniline or phenol yielded carbanilide in quantitative yields. This reaction was applied to the synthesis of polyurea. Bisacetoacetamides were prepared from diamines and diketene in DMF. They were thermally polymerized in the presence of phenol or a diamine (6FDA) to yield polyureas of low molecular weights. The polymers were soluble in DMSO and NMP. $^1{H-NMR}$ analysis showed that they had amino group terminated structures. Poly(urea-imide) was synthesized by the reaction of an oligourea diamine with pyromellitic dianhydride in NMP. The concentration of terminal amino groups was determined by an acid-base titration. The thermal property of poly(urea-imide) was evaluated by thermogravimetric analysis (TGA). Initial decompisition took place at 332-$350^{\circ}C$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.137-138
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• 2019

To overcome the limitation in relation to thermal insulator's selection and installation method that is suitable for exterior insulation and waterproof construction methods, a production basis of thermal insulators of which manufacturing knowhow is held by companies was ensured and future-oriented construction methods to adopt new materials were applied. Performance verification was conducted through performance and mock-up tests of thermal transmittance on the cross sections where the flexible insulators were applied based on the improved prototype and performance data were obtained. To overcome the biggest drawbacks (walking feeling and damage etc.) in the exterior insulation and waterproof construction method, inserting a protective layer between thermal insulator and water-proof layer was proposed, and polypropylene corrugated cardboards.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.177-178
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• 2018

In the case of conventional ultra-fast hardness membrane waterproofing material (polyurea, etc.), damage such as breakage or tearing occurred frequently at the time of cracking of the surface after waterproofing. In this study, it is suggested that a waterproof layer can not cope with the occurrence of cracks at the same time by applying the soft type waterproofing material of soft type at the lower part of the construction method (securing of elongation) To minimize the possibility of water resistance.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1206-1212
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• 2000

This study was conducted to know whether Gamiyookmijihwangtang(GY) which is Yookmijihwang added with Liriopis tuber, Anemarrhenae rhizoma and Phellodendri cortex can remedy the overt diabetes in diabetes-prone BB(BBDP) rats. The rats were given GY through the mother from the fetal stage until birth. After birth they received GY through breast feeding until 20 days old. From 21 days old which is the beginning of the weaning period 60 BB rats(30 males and 30 females) were divided into 2 experimental groups(BBDP and BBDP-GY) and placed individually in metabolic cages. BBDP was the control group which didn't receive any GY and BBDP-GY received 16 mL/㎏ B.W./day of GY until 120 days old. The antidiabetic effects of GY were characterized by the clinical features such as polyurea, polydipsia, hyperglycaemia and the rapid loss of body weight. Body weight, water consumption, urine volume and blood glucose level showed no signs of impending diabetes but after onset there were big changes in those parameters. The onset of diabetes was delayed and the incidence of diabetes was also much decreased with GY but after onset there were no beneficial effects from it.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.151-152
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• 2015

Concrete parking slab is often deteriorated severely after winter season because of concrete's freezing and thawing phenomenon. In this study, some methods to improve resistance against freezing-thawing is experimentally tested.: 1) concrete strength, 2) air content in concrete, 3) saw-cut effect and finish material. After experiment, in case of no finishes, 24MPa concrete with 4% air content is tested best result in terms of relative elastics modulus among testes ones. In case of concrete with finishes, all specimens are improved regardless of finishes compared to concrete with no finishes. Improvement degree compared to no finish is as follows : Polyurea > Resin-mortar > hardener and the number of improvement degree is 5, 4, 2% respectively. Further work is required considering construction site condition such as gaining water on surface and remicon in order to reflect site condition.

• Transactions on Electrical and Electronic Materials
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• v.8 no.1
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• pp.36-40
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• 2007

Inorganic layers, such as SiOxNy and SiOx deposited using plasma sublimation method, were tested as passivation layer for organic thin-film-transistors (OTFTs). OTFTs with bottom-gate and bottom-contact structure were fabricated using pentacene as organic semiconductor and an organic gate insulator. SiOxNy layer gave little change in characteristics of OTFTs, but SiOx layer degraded the performance of OTFTs severely. Inferior barrier properties related to its lower film density, higher water vapor transmission rate (WVTR) and damage due to process environment of oxygen of SiOx film could explain these results. Polyurea and polyvinyl acetates (PVA) were tested as organic passivation layers also. PVA showed good properties as a buffer layer to reduce the damage come from the vacuum deposition process of upper passivation layers. From these results, a multilayer structure with upper SiOxNy film and lower PVA film is expected to be a superior passivation layer for OTFTs.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.725-736
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• 2016

There is a growing concern on the improvement of water distribution pipeline for multi-regional water supply system in Korea along with its aging infrastructure. Rehabilitation of large diameter pipeline is more efficient in cost and time compared to replacement with trenching. The procedure for rehabilitation are diagnosis, cleaning, spraying coating material, and final inspection. The internal state of pipeline was carefully diagnosed and got C grade, which required rehabilitation. We found that 17,274,787,000 Korean won could be saved after pipe surface coating because of increased C coefficient of Hazen-Williams equation. Optimal coating material was D polyurea. We also found optimal distance between spraying nozzle and pipe wall to be 70 - 80 cm, which were critical factors for coating quality. This study also illustrated the time for spray drying to be more than 30 min. These results could be used in the quality control process during rehabilitation of aged pipelines.

• Journal of the Korea Institute of Building Construction
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• v.15 no.6
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• pp.579-587
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• 2015

In this paper, microencapsulated healing agent was embedded in the polymer matrix to obtain self healing properties. Microencapsulation of methacrylate using polyurea-formaldehyde as a shell material and studied the effect of agitation rate on capsule characteristics such as size, shell thickness, and surface morphology. The formation of microcapsules was confirmed by FTIR and TGA, and capsule characteristics were studied by optical microscopy and SEM. The self-healing effect was evaluated using permeability measurements and further confirmed by surface analytical tools including optical microscope. According to the experimental results, the microencapsulated healing system has the self-heaing ability for artificial cracks.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.1034-1040
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• 2020

The mechanical properties of NATM resin of synthetic polyurethane-epoxy resin for stainless steel were measured by SEM, FT-IR, tensile properties, and specific mass loss by EIS analysis, etc. As interest in eco-friendly medium coatings increased, the Heavy duty coatings were synthesized for various metals such as stainless steel composed of Polyol, MDI, water bored Epoxy resin, filling agent, silicon surfactant, catalyst etc. The coatings of synthetic NATM resin were increased tensile strength due to various temperature change, and the low-Specific Mass Loss was measured in a highly electrolytic solution. In conclusion, the NATM coatings composed of polyurethane and waterbored Epoxy, polyurea resin were synthetic microstructure with cross linkage can be good material for coating of anticorrosion of metal substrates such as stainless steel.

• The Journal of Internal Korean Medicine
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• v.28 no.3
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• pp.544-559
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• 2007

Objectives : This study was designed to evaluate the anti-diabetes and vasoelasticity effects of Mori Folium and Aurantii Fructus in streptozotocin-induced type II diabetes mellitus model. Methods : The anti-diabetic effect of Mori Folium and Aurantii Fructus on rats induced with diabetes by streptozotocin was investigated through analyses of changes in body weight, blood glucose, urine volume of rats, viability of human umbilical vein endothelial cells(HUVECs), and elasticity of descending thoracic aorta in rats. The subjects in this study were divided into four groups(n=15): a normal group without any treatment (Con), a normal group with Mori Folium and Aurantii Fructus treatment(Con+P), a diabetes group induced by streptozotocin(STZ), and a Mori Folium and Aurantii Fructus treatment group under diabetes induced by streptozotocin(STZ+P). Rats were administered streptozotocin to induce diabetes. Results : The study showed that Mori Folium and Aurantii Fructus significantly reduced highly increased blood glucose levels(p<0.01) and prevented the diabetic rats from weight loss(p<0.01) and polyurea(p<0.05), Mori Folium and Aurantii Fructus also recovered decreased viability of HUVECs(p<0.01) and damaged elasticity of aorta induced by the streptozotocin (p<0.01). Conclusions: It was concluded from the results that Mori Folium and Aurantii Fructus have a distinct anti-diabetes effect and they also prevent damage of blood vessel induced by diabetes. resulting in prevention of cardiovascular diseases ascribed to diabetes.