양극산화와 열수처리한 니오비움 금속의 표면특성

원대희,김영순,윤동주,이민호,배태성,Won Dae-Hee,Kim Young-Soon,Yoon Dong-Joo,Lee Min-Ho,Bae Tae-Sung 한국재료학회 2005 한국재료학회지 Vol.15 No.2

This study was performed to investigate the surface properties of electrochemically oxidized pure niobium by anodic oxide and hydrothermal treatment technique. Niobium specimens of $10mm\times10mm\times1.0mm$ in dimension were polished sequentially from $\#600,\;\#800,\;\#1000$ emery paper. The surface of pure niobium sperimens was anodized in an electrolytic solution that was dissolved calcium and phosphate in water. The electrolytic voltage was set in the range of 250 V and the current density was $10mA/cm^2$. The specimen was hydrothermal treated in high-pressure steam at $300^{\circ}C$ for 2 hours using an autoclave. And all specimens were immersed in the in the Hanks' solution nth pH 7.4 at $37^{\circ}C$ for 30 days. The surface of specimen was characterized by surface roughness, scanning electron microscope(SEM), energy dispersion X-ray analysis(EDX), X-ray photoemission spectroscopy(XPS) test. The value of surface roughness was the highest in the anodized sample and $0.41{\pm}0.04\;{\mu}m$. The results of the SEM observation show that oxide layers of the multi porosity in the anodized sample were piled up on another, and hydroxyapatite crystal was precipitate from the surface of the hydrothermal treated sample. In the XPS analysis, O, Nb, C peak and small amounts of N peak were found in the polished specimens while Ca and P peak in addition to O, Nb, C and peak were observed in the hydrothermal treated sample.

양극산화와 열수처리한 순수 니오비움 금속의 생체활성 평가

원대희,최운재,이민호,배태성 대한치과기공학회 2005 대한치과기공학회지 Vol.27 No.1

This study was performed to investigate the surface properties of electrochemically oxidized pure niobium by anodic oxide and hydrothermal treatment technique. Niobium specimens of 10 10 in dimension were polished sequentially from #600, #800, #1000 emery paper. The surface pure niobium specimens were anodized in an electrolytic solution that was dissolved calcium and phosphate in water. The electrolytic voltage was set in the range of 250 V and the current density was 10 / . The specimen was hydrothermal treated in high-pressure steam at 300 for 2 hours using an autoclave. Then, specimens were immersed in the Hanks' solution with pH 7.4 at 37 for 30 days. The surface of specimen was characterized by scanning electron microscope(SEM), energy dispersive X-ray microanalysis(EDX), potentiostat/galvanostat test, and cytotoxicity test. The results obtained was summarized as follows; According to the result of measuring corrosion behavior at 0.9% NaCl, corrosion resistance was improved more specimens treated with anodic oxide than in hydrothermal treated ones. The multi-porous oxide layer on surface treated through anodic oxidation showed a structure that fine pores overlap one another, and the early precipitation of apatite was observed on the surface of hydrothermal treated samples. According to the result of EDX after 30 days deposition in Hanks solution, Ca/P was 1.69 in hydrothermal treated specimens. In MTT test, specimens treated through anodic oxidation and hydrothermal treated ones showed spectrophotometer similar to that of the control group. Thus no significant difference in cytotoxicity was observed (P>0.05).

Zr 함량 변화에 따른 Zr-xZr계 타이타늄 합금의 특성 평가

원대희,윤동주,박영준,김양수,김병일 대한치과재료학회 2011 대한치과재료학회지 Vol.38 No.2

This study was purposed to develop a titanium alloy with low elastic modulus to be used as dental implant. The new titanium alloy was prepared as a binary alloy system by adding varying content of zirconium (Zr) into the Ti-XZr system alloy. For designing the new titanium alloy, two physical variables of bond order (Bo) and d-electron orbit energy level (Md) were varied. The mean bond order (B_o) was around 2.7931~2.8098, and the mean d-electron orbit energy level (M_d ) was 2.4522~2.4795. The elastic modulus of the developed titanium alloy was 106.02~115.71 GPa. In the results of X-ray diffraction analysis, α-phase was observed in all the specimens. In TEM analysis, additional feature was identified for Ti-12Zr alloy in addition to the α-phase. The deformation twinning was observed in Ti-12Zr alloy.

열가압 성혈 글라스 세라믹의 파괴인성에 미치는 반복 열가압 성형의 영향

원대희 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.4

This study was performed to evaluate the effects of repeating the heat pressing procedure on the fracture toughness of heat-pressable glass-ceramics. Three commercially available ingots of Authentic(Ceramay GmbH), Empress and Empress 2(deutsche Ivoclar Dental GmbH) were used. Crystal phases of these glass-ceramics were investigated by means of X-ray diffraction analysis (XRD) and morphology and microstructure were studied using scanning electron microscopy (SEM). Fracture toughness was calculated using the length of radial crack formed on the Vickers-produced indentation crack by means of the indentation fracture method. According to the result of X-ray diffraction analysis, the test groups of Authentic and Empress did not show the change in crystal peak intensity, but the test group of Empress 2 showed increase in crystal peak intensity after repeating the heat pressing procedure. Fracture toughness values of the test groups of Authentic and Empress showed the aspect of increase after repeating the heat processing procedure but that of Empress 2 group showed decrease.

광중합형 복합레진의 압축강도에 미치는 레진과 필러의 영향

원대희 대한의용생체공학회 1997 의공학회지 Vol.18 No.1

This study was performed to evaluate the effect of resin and filler type on the compressive strength of light-activated composite resins. Experimental composite resins containing either amorphous spherical silica or crushed quartz in two matrix resins of BisGMA/TEGDMA and UTMA/TEGDMA were prepared and the specimens of 3 m in diameter and 6m in length were made. Compressive test was subjected to a crosshead speed of 0.5 mm/min, and the fracture surFaces were examined by SEM. The compressive strength of UTMA-based composite resin was higher than that of BisGMA-based composite resin. The loading rate of spherical silica was higher than that of crushed silica when the size dis- tribution of fillers was same. Strength decrease of Bis-GMA-based composite resin was severer than that of UTMA-based composite resin in a $37^{\circ}$c water environment. Fracture surface showed that the composite resin failure developed along the matrix resin and the filler/resin interface region.

클래드 재료에 대한 열전도도 측정

원대희,박영상 한국기계기술학회 2017 한국기계기술학회 학술대회논문집 Vol.2017 No.04

In this study, cladding materials were prepared by explosion pressure welding of materials with different thermal conductivity to fabricate heating block for 3D printing. The following conclusions were obtained as a result of measuring the thermal conductivity of the clad material. Experimental results show that the lowest thermal conductivity of aluminum and titanium is 116.3 ± 0.4 W / mK.

마그네슘 판재 연마장치 개발

원대희,이문수,손수지 한국기계기술학회 2018 한국기계기술학회지 Vol.20 No.5

In this study, attention has been focused on magnesium materials, which are widely used for lightening of electronic products and mobile phones. Therefore, a polishing apparatus was fabricated by replacing the SiC abrasive used for polished surface of magnesium plate with a ceramic abrasive. The following conclusions were obtained. It is believed that the increase in productivity of 50% compared to the conventional cross-sectional polishing due to the double-side polishing of magnesium sheet can contribute to increase the company's sales. The surface roughness was measured by polishing the plate using a magnesium plate mirror polisher. The Ra, Rmax and Rz values were 0.43, 0.54 and 0.54, respectively. In this study, the optimum polishing speed was 800 m/s when the surface was polished with a magnesium surface polishing device designed and manufactured as a prototype.

굴림석 제작을 위한 석재 컷팅기 개발

원대희 한국기계기술학회 2016 한국기계기술학회 학술대회논문집 Vol.2016 No.05

The purpose of this study was produced after the design of new equipment in order to cut the stone roll prototype. The newly designed equipment is designed and manufactured to be dressed in rolls automatically through the use of a conveyor belt. The introduction of new stone cutters were expected to be achieved productivity improvements of 15% compared to conventional production methods.

열교환법을 이용한 양자점 합성

원대희,황선태,이영기 한국기계기술학회 2018 한국기계기술학회 학술대회논문집 Vol.2018 No.05

실리콘 식각 공정시 발생하는 격자결함 관찰 및 제거동향 연구

원대희,이주훈,김지형,염근영,이주욱,이정용,Won, Dae-Hui,Lee, Ju-Hun,Kim, Ji-Hyeong,Yeom, Geun-Yeong,Lee, Ju-Uk,Lee, Jeong-Yong 한국재료학회 1996 한국재료학회지 Vol.6 No.5

차세대 소자고립구조로서 연구되고 있는 trench isolation 공정 등에는 실리콘 식각이 요구되며 실리콘 식각 공정중에는 반응성 이온에 의해 격자결함이 발생할 수 있다. 이와같이 생성된 결함은 소자의 전기적 성질을 열화시키므로 열처리를 통하여 제거하여야만 한다. 따라서 본 연구에서는 Ar,Ar/H2 플라즈마로 격자결함을 인위적으로 발생시켜 20$0^{\circ}C$-110$0^{\circ}C$ 질소분위기에서 30분간 열처리에 따른 생성된 격자결함의 소거거동을 관찰하였다. 실리콘 표면에 Schottky 다이오드를 제작하여 I-V, C-V 특성을 측정하므로써 잔류하는 전기적인 손상의 정도를 평가하였다. Ar으로 식각한 경우에는 110$0^{\circ}C$ 30분간 열처리한 결과 모든 격자결함이 제거되나 Ar/H2로 식각한 경우에는 격자결함이 완전히 제거되지 않고 (111)적층결함이 남아있었다.