• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.305-324
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• 1997

Numerous materials such as amalgam, IRM, SuperEBA, dessicated ZOE, and Ketac-Silver have been used as a root-end filling material or to repair furcation perforations. But so far no material has been found to satisfy all of the requirements of an ideal restorative material. Recently, mineral trioxide aggregate (MTA) has been suggested for use as a root end filling material and for the repair of furcation perforations. The purpose of this study was to compare the effect of MTA on the proliferation of MC3T3/E1 osteoblastic cell, formation of bone nodule, alkaline phosphatase activity, and finally the tissue reaction of bone with those of amalgam, IRM, SuperEBA, dessicated ZOE, and Ketac-Silver. The following conclusions were drawn within the limits of the experimental results : 1. MTA showed a excellent proliferation of osteoblastic cell and Ketac-Silver showed moderate proliferation of osteoblastic cell. The rest of test materials showed no proliferation of osteoblastic cell. 2. Many of definite bone nodules were found in the MTA group. In contrast, Ketac-Silver group showed no definite bone formation but only showed mild sign of bone formation. 3. Alkaline phosphatase activity of Ketac-Silver and MTA showed similar results. But both of them showed higher activity than that of other materials (p<0.005). 4. The tissue reaction to implanted MTA in the calbarium of mouse was milder than that observed with other materials. The tissue reaction of dessicated ZOE showed the worst results among the test materials.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.4
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• pp.373-379
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• 2016

The thermal control device for the periodic working component combined solid-liquid phase change material (PCM) with heat pipes is designed and numerically studied. Due to high latent heat and retaining constant temperature during melting process the component peak temperature, not withstanding small radiator size, is reduced. The warm-up heater power consumption to keep the minimum allowed temperature is also cut down since the accumulated thermal energy is released through the solidification. The thermal buffer mass (TBM) made of Al can give the similar effect but the mass and power consumption of warm-up heater should increase compared to PCM. The amount of PCM can be optimized depending on the component heat dissipation and on/off duty time.

• 보존과학연구
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• s.14
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• pp.94-108
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• 1993

The cultural properties of cloth are of animal orgin (silk), or of vegetable orgin(cotton, hemp, ramie). As clothes are of an orginic material, they were subjected to damage by chemical, phisigical or biological factors, viz, moulds insects, lights, humidity and temperature changes, etc. And these factors promote that clothes generally result from various types of deterioration. In 1992, We were performed the conservation treatments for total 9 pieces of cloth, such as 3 pieces of General PAK SHIN-RYONG(Important Folklore Material No.110) 3 pieces of Madam Jung(Important Folklore Material No.115) and 1 piece of King Se-jo(Important Folklore Material No.219). The procedure of the conservation treatment for clothes describe the following below. 1) The washing and dry-cleaning to remove the contaminated substances from cloth was used 0.2% stearyl potassium soap solution and the mixture solution compound of n-Hexane, C6H14. and n-Decane, C10H22. And after the washing and dry-cleaning, the dry of clothes was carried out in a warm condition. These steps were repeated in 2 times over for each cloth. 2) The repair of clothes was attached the similar textiles to stronger fabric linings by needlework.3) The reprodution was made for cloth of King Se-jo to equalize the type, color, quality and skill of materials. 4) After these above procedures, all clothes fumigated to prevent the biodeterioration by using the mixed gas of methyl bromide and ethylene oxide as insecticide and fungicide. 5) Finally for the purpose to keep in a safety long-term condition, the treated clothes sealed with Biaxially Oriented Polyvinylacohol Film(BO-PVA film) and Helium, purity 99.999%, filled up in sealed BO-PVA film bag.

• Fire Science and Engineering
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• v.33 no.4
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• pp.89-96
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• 2019

In this study, alarm sound generated as a priority alert system propagation through an elevator shaft in apartment buildings were simulated using room acoustic simulation software. The simulations were conducted on three kinds of elevator hall plan with a different number of elevators and placement. First, the elevator shaft without sound absorption material was simulated as a condition of the present. When the distance from the alarm sound generating floor became farther, alarm sound level was decreased. However, the alarm sound level three-floor distance was about 54 dB(A)~56 dB(A) which were louder than a background sound level of typical apartment buildings. Sound absorption material placement proposed by previous studies were simulated and the alarm sound levels were decreased about 12 dB~16 dB. These levels were similar or lower than the background level of apartment buildings. From these results, it can be concluded that placing sound absorption material on the surface of the elevator shaft wall can be one of the methods to control the alarm sound as regulated in NFSC.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.6 no.2
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• pp.20-27
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• 2010

In order to prevent the corrosion of component contacted primary water designed alloy 600 material in the nuclear power plant. But the primary water stress corrosion cracking(PWSCC) of alloy 600 and weld area occurs continuously due to the residual stress. The leakage accident resulted from PWSCC in the drain nozzle of the steam generator of domestic power plants. Heater sleeves of the pressurizer are welded with alloy 600 weld material and therefore exposed to the primary water environment. PWSCC occurred in heater sleeve material and weld area of many foreign power plants. The current issue of domestic nuclear power plants are consequently concentrated to PWSCC of similar material. In order to improve the detection and the sizing of the PWSCC in the welding sleeve of the pressurizer, the automatic UT system and multi-directions probe sets have been developed. The experimental studies have been performed using the mock-up block containing artificial reflectors(ID connected EDM notch) and semi-artificial cracks made from thermal fatigue. The automatic UT System is applied in the detection and the length sizing of the ID/OD on the tube and the J-groove weld area of the artificial reflectors and results of the detection and the sizing are compared respectively. Also, the developed automatic UT system is successfully accomplished to inspect the heater sleeve and the J-groove weld area on the pressurizer for the detection of PWSCC.

• Restorative Dentistry and Endodontics
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• v.43 no.3
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• pp.24.1-24.12
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• 2018

Objectives: The aim of this in vitro study was to evaluate the biocompatibility of newly proposed root-end filling materials, Biodentine, Micro-Mega mineral trioxide aggregate (MM-MTA), polymethylmethacrylate (PMMA) bone cement, and Smart Dentin Replacement (SDR), in comparison with contemporary root-end filling materials, intermediate restorative material (IRM), Dyract compomer, ProRoot MTA (PMTA), and Vitrebond, using human periodontal ligament (hPDL) fibroblasts. Materials and Methods: Ten discs from each material were fabricated in sterile Teflon molds and 24-hour eluates were obtained from each root-end filling material in cell culture media after 1- or 3-day setting. hPDL fibroblasts were plated at a density of $5{\times}10^3/well$, and were incubated for 24 hours with 1:1, 1:2, 1:4, and 1:8 dilutions of eluates. Cell viability was evaluated by XTT assay. Data was statistically analysed. Apoptotic/necrotic activity of PDL cells exposed to material eluates was established by flow cytometry. Results: The Vitrebond and IRM were significantly more cytotoxic than the other root-end filling materials (p < 0.05). Those cells exposed to the Biodentine and Dyract compomer eluates showed the highest survival rates (p < 0.05), while the PMTA, MM-MTA, SDR, and PMMA groups exhibited similar cell viabilities. Three-day samples were more cytotoxic than 1-day samples (p < 0.05). Eluates from the cements at 1:1 dilution were significantly more cytotoxic (p < 0.05). Vitrebond induced cell necrosis as indicated by flow cytometry. Conclusions: This in vitro study demonstrated that Biodentine and Compomer were more biocompatible than the other root-end filling materials. Vitrebond eluate caused necrotic cell death.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.469-472
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• 1999

CeO$_2$ thin films have used in wide applications such as SOI, buffer layer, antirflection coating, and gate dielectric layer. CeO$_2$takes one of the cubic system of fluorite structure and shows similar lattice constant (a=0.541nm) to silicon (a=0.543nm). We investigated CeO$_2$films as buffer layer material for nonvolatile memory device application of a single transistor. Aiming at the single transistor FRAM device with a gate region configuration of PZT/CeO$_2$ /P-Si , this paper focused on CeO$_2$-Si interface properties. CeO$_2$ films were grown on P-type Si(100) substrates by 13.56MHz RF magnetron sputtering system using a 2 inch Ce metal target. To characterize the CeO$_2$ films, we employed an XRD, AFM, C-V, and I-V for structural, surface morphological, and electrical property investigations, respectively. This paper demonstrates the best lattice mismatch as low as 0.2 % and average surface roughness down to 6.8 $\AA$. MIS structure of CeO$_2$ shows that breakdown electric field of 1.2 MV/cm, dielectric constant around 13.6 at growth temperature of 200 $^{\circ}C$, and interface state densities as low as 1.84$\times$10$^{11}$ cm $^{-1}$ eV$^{-1}$ . We probes the material properties of CeO$_2$ films for a buffer layer of FRAM applications.

• Journal of Environmental Science International
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• v.27 no.7
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• pp.611-620
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• 2018

In this study, a metal-organic framework (MOF) material $NH_2$-MIL-101(Fe) was synthesized using the solvothermal method, and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-visible spectrophotometry, field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and surface area measurements. The XRD pattern of the synthesized $NH_2$-MIL-101(Fe) was similar to the previously reported patterns of MIL-101 type materials, which indicated the successful synthesis of $NH_2$-MIL-101(Fe). The FT-IR spectrum showed the molecular structure and functional groups of the synthesized $NH_2$-MIL-101(Fe). The UV-visible absorbance spectrum indicated that the synthesized material could be activated as a photocatalyst under visible light irradiation. FE-SEM and TEM images showed the formation of hexagonal microspindle structures in the synthesized $NH_2$-MIL-101(Fe). Furthermore, the EDS spectrum indicated that the synthesized material consisted of Fe, N, O, and C elements. The synthesized $NH_2$-MIL-101(Fe) was then employed as an adsorbent and photocatalyst for the removal of Indigo carmine and Rhodamine B from aqueous solutions. The initial 30 min of adsorption for Indigo carmine and Rhodamine B without light irradiation achieved removal efficiencies of 83.6% and 70.7%, respectively. The removal efficiencies thereafter gradually increased with visible light irradiation for 180 min, and the overall removal efficiencies for Indigo carmine and Rhodamine B were 94.2% and 83.5%, respectively. These results indicate that the synthesized MOF material can be effectively applied as an adsorbent and photocatalyst for the removal of dyes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.1-8
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• 2012

Since the cement industry is expected to face serious setbacks in the near future associated with environmental concerns. With the advent of new technologies and increased public awareness about global environmental issues, the cement industry is actively seeking to adopt new technologies as part of an effort to diversity its resources. This study is designed to assess the fundamental properties of zeolite cement concrete which consists mainly of natural zeolite, which is known for removal of and harmful gas, ion exchange capacity removing cation contaminant including heavy metals and ammonia, absorptive capacity and molecular sieving effect together with excellent insulation capacity as a porous material, and recently draws much attention for its possibility as an alternative material to cement. The study was conducted to show the compressive strength of concrete, slump, bleeding and air volume according to the changes of natural zeolite and alkali activator(NaOH). As a result of measuring the compressive strength of natural zeolite concrete, it was almost 40MPa and displayed similar to general concrete in the tests of slump, bleeding and air volume, with which it was considered that it may be used as a future high performance, high performance construction material.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.725-730
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• 2005

In the development of biomaterials as a substitute of hard tissues, the biocompatibility and osteoconductivity of the biomaterial are considered to be one of the most significant considerations. These biological properties of a material can be greatly improved by the modification of the surface properties by the depositing calcium phosphate thin films on the material since calcium phosphate films possess similar chemical compositions to hard tissues. The success of a material as a biomaterial will be determined by the interaction of the surface of the material with the adhesion molecules which induce cellular adhesion and biological responses of the adherent cells. Depending on the adsorption mechanisms and adsorbed conformation of the adhesion molecules on the surface of the biomaterial, cellular responses, such as adhesion, proliferation and differentiation of osteoblast cells, can be promoted or restricted. It has been reported that materials of which surfaces were modified with thin films of calcium phosphate appeared to be more osteoconductive. Rapid formations of bone nodule in addition to higher differentiations of osteoblast have been observed on the calcium phosphate thin films.