• Journal of Biosystems Engineering
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• 제33권6호
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• pp.404-409
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• 2008

Excessive presence of heavy metals in environment affects plants and fruits grown in the contaminated area. Rapid on-site monitoring of heavy metals can provide useful information for efficiently characterizing heavy metal-contaminated sites and for minimizing the exposure of the contaminated food crops to humans. This study reports on the evaluation of gold and glassy carbon (GC) electrodes with mercury or bismuth as a coating material for simultaneous determination of cadmium (Cd) and lead (Pb) in 0.1 M $HNO_3$ solution by anodic stripping voltammetry (ASV). The use of a square-wave voltammetric potential between a working electrode and a reference electrode caused Cd and Pb ions deposited on the electrode surface to be oxidized, thereby generating electric currents at different potentials. The mercury-coated gold electrode was not sensitive enough to detect the usable range of Cd concentrations (1 to 100 ppb). The GC electrodes with mercury or bismuth displayed well-defined, sharp and separate current peaks for Cd and Pb ions when the square-wave voltammetric potentials were applied. The peak currents measured with both mercury- and bismuth- coated GC electrodes were linearly proportional to Cd and Pb concentrations in the range of 1 to 200 ppb in 0.1 M $HNO_3$ with strong linear relationships between concentration and peak current ($R^2$ > 0.95), indicating that both of Cd and Pb ions could be quantitatively measured.

• 한국재료학회지
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• 제21권2호
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• pp.115-119
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• 2011

Si Nanowire (NW) field effect transistors (FETs) were fabricated on hard Si and flexible polyimide (PI) substrates, and their electrical characteristics were compared. Si NWs used as channels were synthesized by electroless etching method at low temperature, and these NWs were refined using a centrifugation method to get the NWs to have an optimal diameter and length for FETs. The gate insulator was poly(4-vinylphenol) (PVP), prepared using a spin-coating method on the PI substrate. Gold was used as electrodes whose gap was 8 ${\mu}m$. These gold electrodes were deposited using a thermal evaporator. Current-voltage (I-V) characteristics of the device were measured using a semiconductor analyzer, HP-4145B. The electrical properties of the device were characterized through hole mobility, $I_{on}/I_{off}$ ratio and threshold voltage. The results showed that the electrical properties of the TFTs on PVP were similar to those of TFTs on $SiO_2$. The bending durability of SiNWs TFTs on PI substrate was also studied with increasing bending times. The results showed that the electrical properties were maintained until the sample was folded about 500 times. But, after more than 1000 bending tests, drain current showed a rapid decrease due to the defects caused by the roughness of the surface of the Si NWs and mismatches of the Si NWs with electrodes.

• 박물관보존과학
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• 제19권
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• pp.69-82
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• 2018

국립청주박물관 소장 충북 영동 영국사 출토 금동여래입상과 동제여래입상의 과학적 조사와 보존처리를 하였다. 성분분석 결과, 금동여래입상은 구리, 주석, 납의 삼원계, 동제여래입상은 구리, 주석의 이원계 합금으로 확인되었다. 동제여래입상 성분분석 결과 금이 확인되어 금동여래입상으로 명칭이 수정되어야 할 것이다. 금동여래입상은 국내에서 생산된 납을 원료로 하여 제작되었을 것으로 유추할 수 있었고, 표면에 존재하는 개금을 위한 접착제로 보이는 물질은 분석을 통해 옻으로 추정되었다. 보존처리는 상태를 확인하여 물리적, 화학적 방법으로 최소한의 이물질을 제거하고, 안정화처리 및 보호 코팅의 과정을 거쳤다.

• 박물관보존과학
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• 제18권
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• pp.51-64
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• 2017

숭실대학교 한국기독교박물관이 소장한 자명종을 특별전 전시를 위해 보존처리 하였다. 보존처리를 위해 성분 분석을 하였으며 그 결과 본체는 황동에 아말감도금법으로 금을 도금하였고, 문자판은 순구리에 법랑을 씌운 것을 확인하였다. 그리고 시계 바늘의 재질은 철이었다. 이물질 제거를 통해 문자판의 테이프 자국 등을 없앴으며, 안정화를 위해 보호 코팅을 하였다. 원래의 형상에 가깝게 복원하기 위해 황동으로 부품을 제작하여 시계 바늘과 문자판을 연결하고, 아크릴 지지대를 만들어 문자판을 본체에 접합하였다. 재질 분석과 보존처리를 통하여 안정한 상태로 전시와 연구에 활용할 수 있도록 하였다.

• 보존과학회지
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• 제37권2호
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• pp.144-153
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• 2021

1979년 국가민속문화재로 지정된 광화당 원삼은 보존상태가 상당히 양호하다. 그러나 지정조사 시에는 없던 봉흉배가 부착되어 '봉흉배가 달린 유일한 자적원삼(紫赤圓衫)' 유물로 알려지면서 보존처리의 필요성이 제기되었다. 이에 지정문화재에 대한 잘못된 정보를 바로잡기 위한 과학적 분석과 동시에 지정 상태로의 원형 복원도 요구되었다. 본 연구를 통해 광화당 원삼에 대한 유물 이력을 조사하고, 현전하는 봉흉배와 봉흉배 수본(繡本) 등의 유물 조사를 병행하여 원형 복원에 대한 자료를 확보하였다. 직접적으로는 에너지 분산형 X선 형광분석을 실시하여, 봉흉배에 사용된 금속사가 은을 기본으로 티타늄 코팅한 것을 확인하였다. 티타늄으로 도금된 금사를 사용한 봉흉배는 1986년 광화당 원삼 사진에서는 확인되지 않았으며, TiN계 피막 도금법이 1990년대에는 여러 산업에서 활용되었다는 점에서 1990년대 초중반에 봉흉배가 부착된 것으로 추정할 수 있다. 특히 X선 형광분석을 활용한 금사의 과학적 분석 결과를 통해 보존처리의 핵심적인 근거자료를 확보하였다. 본고는 전세 유물 보존처리에 있어 유물 이력과 유사 유물 조사의 중요성에 대한 각성과 지정문화재에 대한 잘못된 정보를 바로잡을 수 있는 원형복원의 선례로서 의미가 있다.

• 대한치과보철학회지
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• 제45권2호
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• pp.169-181
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• 2007

Statement of problem: Titanium is well known as a proper metal for the dental restorations, because it has an excellent biocompatibility, resistance to corrosion, and mechanical property. However, adhesion between titanium and dental porcelains is related to the diffusion of oxygen to the reaction layers formed on cast-titanium surfaces during porcelain firing and those oxidized layers make the adhesion difficult to be formed. Many studies using mechanical, chemical and physical methods to enhance the titanium-ceramic adhesion have been actively performed. Purpose: This study meant to comparatively analyse the adhesion characteristics depending on different titanium surface coatings after coating the casts and wrought titanium surfaces with Au and TiN. Material and method: In this study, the titanium specimens (CP-Ti, Grade 2, Kobe still Co. Japan) were categorized into cast and wrought titanium. The wrought titanium was cast by using the MgO-based investment(Selevest CB, Selec). The cast and wrought titanium were treated with Au coating($ParaOne^{(R)}$., Gold Ion Sputter, Model PS-1200) and TiN coating(ATEC system, Korea) and the ultra low fusing dental porcelain was fused and fired onto the samples. Biaxial flection test was done on the fired samples and the porcelain was separated. The adhesion characteristics of porcelain and titanium after firing and the specimen surfaces before and after the porcelain fracture test were observed with SEM. The atomic percent of Si on all sample surfaces was comparatively analysed by EDS. In addition, the constituents of specimen surface layers after the porcelain fracture and the formed compound were evaluated by X-ray diffraction diagnosis. Result: The results of this study were obtained as follows : 1. The surface characteristics of cast and wrought titanium after surface treatment(Au, TiN, $Al_2O_3$ sandblasting) were similar and each cast and wrought titanium showed similar bonding characteristics. 2. Before and after the biaxial flection test, the highest atomic weight change of Si component was found in $Al_2O_3$ sandblasted wrought titanium(28.6at.% $\rightarrow$ 8.3at.%). On the other hand, the least change was seen in Au-Pd-In alloy(24.5at.% $\rightarrow$ 9.1at.%). 3. Much amount of Si components was uniformly distributed in Au and TiN coated titanium, but less amount of Si's was unevenly dispersed on Al2O3 sandblasting surfaces. 4. In X-ray diffraction diagnosis after porcelain debonding, we could see $Au_2Ti$ compound and TiN coating layers on Au and TiN coated surfaces and $TiO_2$, typical oxide of titanium, on all titanium surfaces. 5. Debonding of porcelain on cast and wrought titanium surface after the biaxial flection is considered as a result of adhesion deterioration between coating layers and titanium surfaces. We found that there are both adhesive failure and cohesive failure at the same time. Conclusion: These results showed that the titanium-ceramic adhesion could be improved by coating cast and wrought titanium surfaces with Au and TiN when making porcelain fused to metal crowns. In order to use porcelain fused to titanium clinically, it is considered that coating technique to enhance the bonding strength between coating kKlayers and titanium surfaces should be developed first.

• 센서학회지
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• 제25권4호
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• pp.247-251
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• 2016

Au/PDMS membranes are widely used to fabricate strain sensors which can detect input signals. An interfacial adhesion between metal films and polydimethylsiloxane (PDMS) substrates is one of the important factors determining the performance of strain sensors, in terms of robustness, reliability, and sensitivity. Here, we fabricate Au/PDMS membranes with (3-mercaptopropyl) trimethoxysilane (MPTMS) treatment. PDMS membranes were fabricated by spin-coating and the thickness was controlled by varying the spin rates. Au electrodes were deposited on the PDMS membrane by metal sputtering and the thickness was controlled by varying sputtering time. Owing to the MPTMS treatment, the interfacial adhesion between the Au electrode and the PDMS membrane was strengthened and the membrane was highly transparent. The Au electrode, fabricated with a sputtering time of 50 s, had the highest gauge factor at a maximum strain of ~0.7%, and the Au electrode fabricated with a sputtering time of 60 s had the maximum strain range among sputtering times of 50, 60, and 120 s. Our technique of using Au/PDMS with MPTMS treatment could be applied to the fabrication of strain sensors.

• 한국항공우주학회지
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• 제33권4호
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• pp.41-46
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• 2005

본 연구에서는 고 전력의 RF 신호용 직접 접촉식 스위치에서 문제가 되고 있는 접촉부위에서의 미소용접에 의한 점착 현상을 감소시키기 위해, 고 융점 금속인 텅스텐(W)과 몰리브덴(Mo)을 스위치 접촉 부위에 코팅하여 스위치의 성능을 분석하였다. 스위치의 삽입손실과 신호격리도, 전력 손실 등의 변화를 네트워크 분석기, 전력 측정기 등을 통하여 측정하였다. 측정결과로부터 RF 신호 전송에 있어서 낮은 입력 전력에서는 고융점 금속이 금(Au)보다 접촉저항이 더 크지만 입력 전력이 커지면 비교적 낮은 비저항의 고융점 금속을 사용하는 것이 고전력 전송 및 수명 연장에 있어서 유리함을 밝혀냈다.

• Restorative Dentistry and Endodontics
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• 제16권1호
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• pp.167-180
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• 1991

The purpose of theis study was to evaluate the effectiveness of ultrasonic instrumentation in removing debris and smear layer from the root canal walls. 54 extracted, permanent single rooted teeth were randomly divided into 6 groups of 9 teeth. After canal preparation, the teeth were longitudinally sectioned. The sepcimens were then naturally dried for 2 days, given a maximun thickness gold coating, and examined under the SEM (JSM-35C type, JAPAN). Photographs of all specimens were then taken of the middle and the apical third of the root canal wall. The results were as follows: 1. In all groups, debris and the smear layer were not completely removed from the canal wall 2. There were no significant differences between at the apical third and at the middle third in removing debris and the smear layer in all groups. 3. There were no significant difference between the step - back group and the ultrasound group in removing debris and smear layer. 4. In general, the step - back/ultrasonund groups showed greater canal debridement than the step - back group or ultrasound group. 5. The step - back/ultrasound group with a No. 25 file for 3 min. showed significantly greater canal debridement than the step-back group (p<0.05), or the other step - back/ultrasound groups(p<0.05).

• 한국안광학회지
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• 제15권4호
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• pp.361-366
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• 2010

목적: Hollow Cathode Discharge방법을 이용한 HCD 이온플레이팅 장비를 제작하였고, 이 장비를 이용하여 stainless steel 위에 TiN 박막을 질소 가스양을 변화하면서 코팅하였으며, 이때 TiN 박막의 미세색상변화를 분석하였다. 방법: 질소 가스에 대한 TiN박막의 미세색상변화를 광학적으로 관찰하기 위해 분광복사계와 분광광도계를 사용하였고, 질소 가스에 대한 TiN 박막의 성분 변화를 알기위해 XPS로 분석하였다. 결과: 질소가스 120 sccm의 TiN 박막의 CIE 색좌표는 (0.382, 0.372)로 은색과 금색의 혼합색으로 나타나고 질소 가스양이 증가함에 따라 x, y값 둘다 조금씩 커져 금색이 점점 진해지는 것을 알 수 있었다. 또한 분광광도계에 의한 TiN 박막의 반사율에 있어서 질소 가스양이 증가함에 따라 550 nm 파장근처에서의 반사율의 기울기가 대체적으로 점점 커지는 것을 알 수 있었다. 그리고 XPS를 사용하여 Ti scan 한 결과, $N_2$ 성분에서 유래된 458 eV의 조그마한 피크는 조금씩 더 들어가며 TiN 성분에서 유래된 455 eV의 큰 피크는 약간씩 커지는 것을 볼 수 있었다. 결론: 질소 가스양이 120 sccm인 TiN 박막에서는 표면에 있는 TiC 성분과 표면과 내부에 존재하는 $N_2$, TiN 성분으로 인해 은색과 금색의 혼합색으로 나타났으나, 질소 가스양이 증가함에 따라 TiN 성분이 다른 성분에 비해 점점 많아져 금색이 점점 진해진 것으로 유추할 수 있었다.