• Proceedings of the Materials Research Society of Korea Conference
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• 한국재료학회 1994년도 춘계 학술발표 강연 및 논문 개요집
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• pp.54-54
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• 1994

• Journal of Korean Society of Environmental Engineers
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• 제30권3호
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• pp.331-338
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• 2008

Coal-tar enamel, blown asphalt and polyethylene have been used as wrapping materials of steel pipe in Korea. Currently, every manufacturer produces wrapped steel pipes with different materials and methods, and little research has been performed to get on wrapping methods and materials. In this research, properties of wrapping material of steel pipe used for water supply have been evaluated. All of the materials tested in this work were found to meet the standard. Among the wrapping materials of steel pipe tested, blown asphalt and coal-tar enamel were reasonable in price, and their mechanical properties were excellent. The quality of the wrapped steel pipes was being melted easily in organic solvent. When coated thick, the load of the steel pipes was higher than necessary. Tensile strength of cathode exfoliation and PE 3-layer wrapping method was excellent. The pulling intensity of T-Die PE 3-layer was stronger than PE fluidized in PE wrapping method. Cathode exfoliation area was smaller than PE fluidized. Mechanical property and thermo-property of T-Die PE 3-layer were excellent and its anti-chemical property was great. Liquid epoxy can change the property of coating materials depending on the hardening condition and resin selection. Polyurethane used in this test showed a less adhesive strength with steel pipes than epoxy. Moisture absorbance rate was higher than Epoxy's, however. To utilize polyurethane as wrapping materials, basic property of the matter should be improved followed by finding the best suited coating condition. The method of PE 3-layer by extrude method appeared to be the best in this study. However, identification of other wrapping materials requires further additional tests.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.360.1-360.1
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• 2016

Hydroxyapatite (Ca10(PO4)6(OH)2, HAP) particles have attracted a great deal of attention in biomedical fields due to their good biocompatibility, bioactivity and fairly broad applications as drug delivery, dental implant, bone cement, and etc. Thus, many researchers have made an effort to add new functionalities such as luminescence, drug delivery, and bone regeneration properties up to HAP powders by controlling their nanostructure as well as composition. In this research, the mesoporous strontium substituted HAP (Sr-HAP) microspheres were synthesized using a hydrothermal method. In this synthesis, aspartic acid monomers were utilized to form microsphere by controlling surface energy of HAP particles and Sr ions were substituted into Ca ion sites, which induced luminescence property in HAP powders. Moreover, the change in the amount of Sr substitution was found to influence the particle size, morphology, and concurrently surface area, which led to changing drug loading as well as drug release property. The amount of Sr influences the morphology, luminescent properties, particle size, surface area cell viability and drug loading property, which are investigated by SEM, TEM, XRD, FTIR, BET, XPS and in vitro test such as MTT assay and drug release test. In particular, the multifunctional Sr-HAP with molar ratios of 0.25 (Sr/(Ca+Sr)) possessed the strongest luminescent property as well as the superior drug loading and sustained release properties that were correspondent with large surface area and pore size. Our study indicates that the fabricated multifunctional Sr-HAP microspheres are quite useful for bone regeneration and drug delivery.

• Korean Journal of Materials Research
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• 제14권12호
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• pp.863-869
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• 2004

The purpose of this research is to investigate the mechanical property and ductile-brittle transition temperature of Ti-Nb-P added extra low carbon interstitial free steel having a tensile strength of 440 MPa. The mechanical property and transition temperature of hot rolled steel sheets were more influenced by the coiling temperature rather than by the small amount of alloying element. Further, at the same composition, the property of the specimen coiled at low temperature was superior to that obtained at higher coiling temperature. The fracture surface of 0.005C-0.2Si-1.43Mn steel coiled at $630^{\circ}C$ showed a ductile fracture mode at $-100^{\circ}C$, but coiling at $670^{\circ}C$ showed a transgranular brittle fracture mode at $-90^{\circ}C$. The galvannealed 0.006C-0.07Si-1.33Mn steel sheet annealed at $810^{\circ}C$ has tensile strength and elongation of 442.8 MPa and $36.6\%$, respectively. The transition temperature of galvannealed 0.006C-0.07Si-1.33Mn steel sheet was increased with a drawing ratio, and the transition temperature of the galvannealed 0.006C-0.07Si-1.33Mn steel was $-60^{\circ}C$ at a drawing ratio of 1.8

• Korean Journal of Materials Research
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• 제22권5호
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• pp.227-236
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• 2012

Ionomer is a thermoplastic that is composed of covalent bonds and ionic bonds. It is possible to use this material in processes such as injection molding or extrusion molding due to the material's high oil resistance, weatherproof characteristics, and shock resistance. In this study, a new ionomer having a multifunctional group was prepared by a stepwise neutralization system with the addition of acidic and salt additives. In step I, to increase the contents of the multifunctional group and the acid degree in ethylene acrylic acid (EAA), MGA was added to the ionomer resin (EAA). A new ionomer was prepared via the traditional preparation method of the ionic cross-linking process. In step II, metal salt was added to the mixture of EAA and MGA. The extrusion process was performed using a twin extruder (L/D = 40, size : ${\varphi}30$). Ionomer film was prepared for evaluation of gas permeability by using the compression molding process. The degree of neutralized and ionic cross-linked new ionomer was confirmed by FT-IR and XRD analysis. In order to estimate the neutralization of the new ionomer film, various properties such as gas permeation and mechanical properties were measured. The physical strength and anti-scratch property of the new ionomer were improved with increase of the neutralization degree. The gas barrier property of the new ionomer was improved through the introduction of an ionic site. Also, the ionic degree of cross-linking and gas barrier property of the ionomer membrane prepared by stepwise neutralization were increased.

• Composites Research
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• 제28권6호
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• pp.402-407
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• 2015

It is well known that the polymer matrix composite materials have good specific strength, making them appropriate for use in transport vehicle. Since the property of composite materials can be obtained only after manufacturing parts, the property depends on greatly on the fabrication process, which is different from metallic system. Therefore, in order to use composite materials for aircraft, the certifying agency requires a robust database with extensive tests and proof of the process unlike metals. Recently developed material qualification methodology by NCAMP (National Center for Advanced Materials Performance) has been accepted by FAA and EASA and can be applied to type certificate reducing time and cost of developing a composite materials database for aircraft application. This paper summarizes a study to establish the composite materials database to apply the NCAMP methodology to composite materials characterization for composite aircraft and to provide the effective materials database through Aerospace Composite Materials Data Center to be approved by Korea Civil Aviation Certification Agency.

• Proceedings of the Materials Research Society of Korea Conference
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• 한국재료학회 2005년도 춘계학술발표대회 및 제8회 신소재 심포지엄 논문개요집
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• pp.245-245
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• 2005

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.265-266
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• 2006

It was well known that thermopile was quiet a competent sensor using to probe the temperature of "hot point" where the temperature can be off the temperature-limitation for normal operation of the main electrical power equipment. In the present work, we aimed for developing new Ge-thermopile materials which can be using a non-contact temperature sensors at various hot-point of the power equipment and evaluation of its output property. As a results of the present works, a new thermopile which were composed Ga-poded p-type and Sb-doped n-type in Ge-semiconductor were designed and manufactured by MBE(Molecular Beam Epitaxy) process and showed superior sensitivity at room temperature.

• Proceedings of the Polymer Society of Korea Conference
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.288-288
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• 2006

Natural rubbers (NR) reinforced by multi-wall carbon nanotubes (MWCNT) was found to show extraordinary improvement of mechanical property. We speculated that this was owing to the interfacial phase that surrounded CNT and investigated about the phase by atomic force microscopy (AFM). Using force modulation mode and force-distance curve analyses, we succeeded in obtaining the information of its nanometer-scale rheological property. We found that was actually surrounded by the interfacial phase, that had softer modulus than NR matrix.

• Journal of the Korean Society for Precision Engineering
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• 제28권4호
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• pp.398-403
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• 2011

Terfenol-D is one of several magnetostrictive materials with property of converting energy into mechanical motion, and vice versa. Magnetostriction is the property that causes certain ferromagnetic materials to change shape in a magnetic field. Terfenol-D is said to produce giant magnetostriction, strain greater than any other commercially available smart material. In this paper, fundamental characteristics analysis of giant magnetostrictive materials(Terfenol-D) has been investigated. The magnetic field analysis is carried out by using finite element method simulation ANSYS. The results show 223N in force and 9.5T in maximum magnetic flux density and 7.56 $10^6A/m$ in maximum magnetic field intensity 1A current. Through the analysis, basic data of Terfenol-D for the application of mechanical system are obtained.