• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.126-126
• /
• 2014

Label-free biomolecular assay based localized surface plasmon resonance (LSPR) of noble metal nanoparticles enables simple and rapid detection with the use of simple equipment. Nanosized metal nanoparticles exhibit a strong absorption band when the incident light frequency is resonant with the collective oscillation of the electrons, which is known as the LSPR. Here we demonstrate localized surface plasmon resonance (LSPR) substrates such as plasmonic Au nanodisks fabricated by a nanoimprinting process and gold nanorod-immobilized surfaces and their applications to highly sensitive and/or label-free biosensing. To increase detection sensitivity various bioreceptors weree designed. A single chain variable fragment (scFv) was used as a receptor to bind C-reactive protein (CRP). The results of this effort showed that CRP in human serum could be quantitatively detected lower than 1 ng/ml. Aptamers, which were immobilized on gold nanorods, were used to detect mycotoxins. The specific binding of ochratoxin A (OTA) to the aptamer was monitored by the longitudinal wavelength shift of LSPR peak in the UV-Vis spectra resulting from the changes of local refractive index near the GNR surface induced by accumulation of OTA and G-quadruplex structure formation of the aptamer. According to our results, OTA could be quantitatively detected lower than 1 nM level. Additionally, aptamer-functionalized GNR substrate was quite robust and can be regenerated many times by rinsing at 70 OC to remove bound target. During seven times of washing steps, the developed OTA sensing system could be reusable. Moreover, the proposed biosensor exhibited selectivity over other mycotoxins with an excellent recovery for detection in grinded corn samples, suggesting that the proposed LSPR based aptasensor plays an important role in label-free detection of mycotoxins.

• 보존과학회지
• /
• 제36권4호
• /
• pp.296-305
• /
• 2020

Konbaung Dynasty was the last unified dynasty that ruled Myanmar from 18^th to 19^th century. During this time Buddhist art flourished in Myanmar due to the interest of the rulers toward their traditional culture. Metal decorative artifacts in the 18^th century are classified into structures and Buddha statues. They are further subdivided into gilt-bronze and bronze objects, depending on their material component. Three-dimensional gilt-bronze decorative artifacts were cast with a brass alloy of Cu-Zn-Sn-Pb and their surfaces were gilded with extremely thin gold leaves (less than 1 ㎛ in thickness). The gilded layer approximately comprised 10 wt% silver in addition to the main element, gold. The lack of Hg in the gilded layer, indicated that the amalgam gilding technique was not applied. The analysis results indicated that the lacquered gilding technique was applied to the objects. Bronze decorative artifacts without gilding were cast with materials containing Cu-Sn-Pb. The bronze pavilions and bronze Buddha staues were crafted using the same alloy of high-tin bronze, which approximately contained 20 wt% Sn. No heat treatment was applied to reduce the brittleness of the objects after they were cast with a large amount of Sn. The most significant difference between the gilt-bronze and bronze decorative artifacts lie in their elemental compositions. The gilt-bronze decorative artifacts with their gilded surface were manufactured using brass containing zinc, while the unplated bronze decorative artifacts were composed of bronze containing tin. Artifacts of the same type and size are classified differently depending on the materials utilized in the surface treatment such as gilding.

• 센서학회지
• /
• 제27권1호
• /
• pp.55-58
• /
• 2018

Low-cost and large-scale fabrication method of nanohole array, which comprises nanoscale voids separated by a few tens to a few hundreds of nanometers, has opened up new possibilities in biomolecular sensing as well as novel frontier optical devices. One of the key aspects of the nanohole array research is how to control the hole size following each specific needs of the hole structure. Here, we report the extensive study on the fine control of the hole size within the range of 500-2500 nm via surface-catalyzed chemical deposition. The initial hole structures were prepared via conventional photo-lithography, and the hole size was decreased to a designed value through the surface-catalyzed chemical reduction of the gold ion on the predefined hole surfaces, by simple dipping of the hole array device into the aqueous solution of gold chloride and hydroxylamine. The final hole size was controlled by adjusting reaction time, and the optimal experimental condition was obtained by doing a series of characterization experiments. The characterization of size-controlled hole array was systematically examined on the image results of optical microscopy, field emission scanning electron microscopy(FESEM), atomic-force microscopy(AFM), and total internal reflection microscopy.

• 대한치과기공학회지
• /
• 제39권1호
• /
• pp.43-52
• /
• 2017

Purpose: Physical and chemical properties of gold is most suitable to be restored of teeth to its original state. Recently zirconia was used instead of gold because of esthetical and intimacy of human body. Because of high strength and high abrasion resistance of zirconia, all zirconia artificial tooth lead to wear the original tooth of opposite site. To preserve this original tooth, zirconia artificial tooth covered with dental ceramic glass was used. When joining the zirconia core and dental ceramic glass, difference of their thermal expansion coefficient and wetting ability is generated the residual stress at interface lead to crack. In order to solve this problem, intermediate layer what is called zir-liner was imported to decrease the residual stress and increase the bonding strength. Methods: In this study, to identify the optimum conditions for manufacturing process, various methods to rough the surface of zirconia core were adopted, and vary the thickness of interlayer, and analyzed bond strength. Results: Bond strength of sanding specimens group showed higher than that of non-sanding specimens group, and once applied intermediate layer with sanding specimens showed highest bond strength with 28 MPa. SEM photomicrographs of zirconia cores fired at $1500^{\circ}C$ showed parallel straight lines in sanding and pockmarked surface in blasting surfaces as abrasion traces. Observation of the destruction section after shear test by SEM were carried out. Liner applied non-sanding group and non-liner applied sanding group all showed interfacial crack. Sandblasting group with non-liner showed remained dental ceramic glass on the surface of zirconia. Sandblasting group with once applied liner showed partially remained liner and dental ceramic glass on the surface of zirconia. XRD analysis revealed that sandblasting group showed higher monoclinic peaks than other specimens group and this result was due to the high collision energy for stress induced phase transformation. Conclusions: A study on the improvement of bonding strength between zirconia and dental ceramic glass steadily carried out for the future to practical use.

• 한국진공학회지
• /
• 제19권4호
• /
• pp.300-306
• /
• 2010

소수성 고분자를 사용하여 제작한 마이크로구조에 금 나노입자를 마스크로 이용하는 반응성이온식각(RIE: Reactive Ion Etching)을 적용하여 초소수성을 갖는 마이크로-나노 혼성구조를 제작하였다. 소수성 고분자로는 PFPE (perfluoropolyether bisurethane methacrylate)를 사용하였으며 마이크로 단일구조는 PDMS (polydimethylsiloxane) 몰드를 사용하는 스탬핑 방식으로 제작하였다. 다양한 형태로 제작한 PFPE 마이크로 단일구조와 마이크로-나노 혼성구조의 표면 접촉각을 측정하여 표면 미세구조에 따른 소수성의 변화를 관찰하였다. 마이크로 단일구조의 경우 접촉각은 안정적인 값을 보이지 못하였으나 단일 구조에 나노입자를 사용한 식각을 적용해 나노구조가 형성됨에 따라 $150^{\circ}$ 이상의 접촉각을 갖는 초소수성 표면이 매우 높은 재현성으로 용이하게 형성되었다.

• 대한금속재료학회지
• /
• 제49권3호
• /
• pp.237-242
• /
• 2011

The effect of shearing speed on the shear force and energy of Sn-0Ag-0.5Cu solder ball was investigated. Various UBM (under bump metallurgy)'s on Cu pads were used such as ENEPIG (Electroless Nickel, Electroless Palladium, Immersion Gold; Ni/Pd/Au), ENIG (Electroless Nickel, Immersion Gold; Ni/Au), OSP (Organic Solderability Preservative). To fabricate a shear test specimen, a solder ball, $300{\mu}m$ in diameter, was soldered on a pad of FR4 PCB (printed circuit board) by a reflow soldering machine at $245^{\circ}C$. The solder bump on the PCB was shear tested by changing the shearing speed from 0.01 m/s to 3.0 m/s. As experimental results, the shear force increased with a shearing speed of up to 0.6 m/s for the ENIG and the OSP pads, and up to 0 m/s for the ENEPIG pad. The shear energy increased with a shearing speed up to 0.3 m/s for the ENIG and the OSP pads, and up to 0.6 m/s for the ENEPIG pad. With a high shear speed of over 0 m/s, the ENEPIG showed a higher shear force and energy than those of the ENIG and OSP. The fracture surfaces of the shear tested specimens were analyzed, and the fracture modes were found to have closer relationship with the shear energy than the shear force.

• Restorative Dentistry and Endodontics
• /
• 제23권1호
• /
• pp.468-476
• /
• 1998

The purpose of this study was to observe the morphologic change of dentinal surface, adhesion in interface between dentin and bonding agents, and penetration pattern of resin tags into dentinal tubles according to bonding procedure of ONE-STEP universal adhesive system. Ten extracted human molars were mounted in dental stone and sectioned to expose mid-coronal occlusal dentin and again sectioned tooth crown apically. Specimens were randomly assigned to three groups for dentin conditioning with 32% phoshoric acid, two coats of bonding agents after dentin conditioning, and bond of composite resin. The surfaces of dentin were treated with etch ant and applied bonding agent, and bonded composite resin according to the directions of manufacturer. Specimens which were boned composite were sectioned longitudinally for observing interfaces between resin and dentin. Two of specimens which were sectioned longitudinally were immersed in 6 N HCL for 30 seconds and 1% NaOCL for 12 hours to partially demineralize and deproteinize the dentin substrate. Each specimen was mounted on a brass stub, sputter-coated with gold and observed under SEM. The result were as follows : 1. On the dentinal surface which was conditioned with 32% phosphoric acid. the smear layer was completely removed. orifices of dentinal tubules were opened 3-$5{\mu}m$ wide. and dentinal surface was irregular. 2. On the dentinal surface which was applied ONE-STEP. bonding agent. resin particles were observed on the orifices of dentinal tubules and intertubular dentin. 3. There were close adaptation between dentin and resin and were the pattern which composite invaded into dentin. 4. 1-$3{\mu}m$-wide hybrid layer was visible in the interface between dentin and resin. 5. Long and funnel shaped resin tags were observed in demineralized specimens. and the surfaces of tags were rough.

• Restorative Dentistry and Endodontics
• /
• 제23권2호
• /
• pp.618-629
• /
• 1998

CAD/CAM-fabricated ceramic restorations nowadays are used as alternatives of amlagam and posterior composite resin restorations, especially in the cases of inlay restorations. But the reported results on marginal and internal fit of CAD/CAM-fabricated ceramic inlay have showed considerable difference. In this study, to evaluate the marginal and internal fit of CEREC2-fabricated ceramic inlay restoration and to compare with the fit of gold inlay and amalgam restoration, standardized Class II MO cavities were prepared in forty extracted caries-free human premolars. The teeth with prepared cavities were divided into 4 groups of ten teeth each. In group 1, CEREC2-fabricated ceramic inlays were treated with Scotchbond Multi-Purpose Plus(SMP plus) and cemented with Scotchbond Resin Cement. In group 2, casted gold inlays were cemented in the same method as in group 1. In group 3, casted gold inlays were cemented with zinc-phosphate cement. And in group 4, the prepared cavities were restored with amalgam. Restored teeth were thermocycled, stored in 1% methylene blue for 24 hours, and sectioned faciolingually and mesiodistally using EXAKT. Sectioned surfaces were observed with stereomicroscope and the gaps were measured at 9 points of mesiodistally sectioned surface and 7 points of faciolingually sectioned surface. The measured data were treated by Kruskal-Wallis one way ANOVA and Student-Newman-Keuls test. 1. The differences among measured gaps at each points were statistically significant for 4 experimental groups (P<0.05). 2. There were statistically significant differences in the measured gaps at each points between group 1 and group 2, group 1 and group 3, group 1 and group 4, group 2 and group 4, and group 3 and group 4 (P<0.05). 3. There were not statistically significant differences in the measured gaps at each points between group 2 and group 3 (P>0.05). 4. In the cases of inlay restorations(group 1, group 2, group 3), the gaps at internal line angle(distopulpal, axiogingival, faciopulpal, linguopulpal line angle) had a tendency to increase. In the cases of amalgam restorations(group 4), the gaps at occlusal margin, gingival margin and axiogingival line angle were greater than those at the other parts of cavities. 5. In CEREC2-fabricated ceramic inlays which were treated with Scotchbond Multi-Purpose Plus and cemented with Scotchbond Resin Cement, the mean gaps were $111{\mu}m$ at cavity margins, $168{\mu}m$ at vertical walls of cavities, $225{\mu}m$ at internal line angles and $123{\mu}m$ at cavity floors.

• 한국전산구조공학회논문집
• /
• 제31권1호
• /
• pp.17-21
• /
• 2018

오늘날까지 적층 마이크로 외팔보의 고유진동수에 대하여 연구가 진행되었다. 마이크로 보는 실리콘 재질로 만들어 지지만, 그것의 상하 표면은 얇은 금 박막층(~30nm)이 증착되어 있다. 초음파 검사를 위해 초음파 테스트 플랫폼을 사용했으며, 시간영역 신호는 광학적으로 측정되었다. 고유진동수는 파형을 고속 Fourier 변환을 통해 정량화하였으며, 결과적으로 고전적인 보 이론과 일치하는 결과를 보여 주었다. 본 연구는 마이크로/나노스케일 재료와 마이크로 구조에 대한 동적평가기법을 제공할 것으로 기대된다.

• Journal of the Optical Society of Korea
• /
• 제19권4호
• /
• pp.346-350
• /
• 2015

We report a measurement of the effective refractive index of a nematic liquid crystal (NLC) inside a Fabry-Perot (FP) etalon according to the applied electric fields. The effective refractive index of the NLC depends on the intensity of the applied electric field. A wavelength-swept laser with a polygon-scanner-based wavelength filter is used as a wide-band optical source to measure the effective refractive index of the NLC. The bandwidth of the optical source is greater than 90 nm around 1300 nm. The fabricated NLC FP etalon consists of glass substrates, gold layers as the electrodes with highly reflective surfaces, polyimide layers as the planar alignment layers, and an LC layer. Furthermore, we measured the Freedericksz transition voltages for three types of NLC FP etalons having thicknesses of $30.6{\mu}m$, $55.4{\mu}m$, and $108.8{\mu}m$. The Freedericksz transition voltages in the three cases are nearly equal. The measured effective refractive indices in the three cases decreased from 1.67 to 1.51 as the applied electric field intensity was increased. Beyond the threshold electric field, the effective refractive indices quickly decreased and eventually saturated at a value of 1.51 for all cases.