• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.848-849
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• 2006

Bulk metallic glass (BMG) composites combining a $Cu_{54}Ni_6Zr_{22}Ti_{18}$ matrix with brass powders or $Zr_{62}A_{l8}Ni_{13}Cu_{17}$ metallic glass powders were fabricated by spark plasma sintering. The brass powders and Zr-based metallic glass powders added for the enhancement of plasticity are well distributed homogeneously in the Cu-based metallic glass matrix after consolidation. The BMG composites show macroscopic plasticity after yielding, and the plastic strain increased to around 2% without a decrease in strength for the composite material containing 20 vol% Zr-based amorphous powders. The proper combination of strength and plasticity in the BMG composites was obtained by introducing a second phase in the metallic glass matrix.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.343-343
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• 2008

Newly designed structure of a thin ultrasonic rotary motor was proposed. Thin brass plate was used as a cross shaped vibrator and eight ceramic plates were attached on the upper and bottom sides of the brass plate as in Figure 1. The thin type ultrasonic motor has the structure adherent piezoelectric ceramic on the top and bottom surface of the thin elastic body. The direction of polarization is decided so as to occur the elliptical displacement in regular sequence at touch point A, B, C and D of stator contacted with rotor. By applying two electric fields which have 90 degree phase difference on the ceramics, each contact points make rotational displacements as in figure 2. Finite element analysis program ATILA was used to find the optimal size of the stator. As a result of the simulation, elliptical displacements of the tips were obtained at off-resonance frequencies. The maximum displacements of the contact tips were obtained at the length of 16[mm], width of 6[mm] and thickness of 0.4[mm]. Changes of the resonance frequencies were inversely proportional to the length of ceramic and proportional to the width of ceramic. Elliptical motions of the contact tips. of the stator were consistently obtained at off resonance frequencies. From a prototype motor, speed of 600[rpm] was obtained at 20[Vrms].

• 대한치과보철학회지
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• 제16권1호
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• pp.17-21
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• 1978

The object of this study was to measure of the distortion of various dental waxes under condition simulating clinical usage. Eleven commercial product (table) including the inlay and baseplate waxes were tested, and compared in the study. Test specimens were prepared $5{\times}5{\times}65mm$. split brass mold. Placed this rod wax specimens and the brass wax distortion test mold into the water bath and tested the distortion values for waxes at $35^{\circ}C,\;40^{\cric}C,\;45^{\circ}C\;and\;50^{\circ}C$. Measured the distortion as the difference between the final (Df) and original (Do) distance between the ends of the specimen. Recorded Df, Do and Df-Do (Distortion) to the nearest 0.5mm. A minimum of five specimens were tested for each material. The following conclusions may be drawn from this study. 1) It can be seen that, a significant wax distortion was obtained with the temperature of forming the pattern, and the length of time and the temperature at which it was stored. 2) It was found that, when the storage time was increased, the wax distortion was correspondingly increased. At the sametime, the higher the storage time was employed, the distortion was obviously much greater. 3) It can be observed that the higher the temperature at which the wax was manipulated, the less was the resulting distortion upon storage.

• 한국표면공학회지
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• 제17권4호
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• pp.106-119
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• 1984

Brass was electrodeposited over the range of the current densities from 2 to 8 A/$dm^2$ in cyanide bath at 20 and 40$^{\circ}C$. The cathode overpotential increased and the cathode efficiency was decreased respectively with decreasing temperature, increasing current density and addition of organic substance. The perferred orientation of the deposits were associated with the cathode overpotential and the nucleation energy of lattice planes. The (111) preferred orientation developed at the low current density and low cathode overpotential (440-520mV). On the other hand, the (111)+(100) preferred orientation developed at higher cathode overpotential (528-680mV). The (111)+(100) preferred orientation developed over the whole range of overpotential in the cyanide solution with organic additive. The copper content of deposit decreased with increasing current density and decreasing temperature. The morphology of the deposits with no additive was the polygonal body type of structure and the structure of the cross section was columnar structure. The morphology of the deposits with additive, on the other hand, was fine crystallite type of structure. And the structure of the cross section of them was the finer granular structure.

• 보존과학회지
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• 제37권4호
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• pp.402-410
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• 2021

Woolen tapestry curtains possessed by the Seoul Museum of Craft Art were used to hung on the wall or used for carpets in the winter season in the late Joseon dynasty. Since similar artifacts were only used for the curtain as functional aspects, woolen tapestry curtains were a rare case. In this study, scientific analysis on the accessory ornament of woolen tapestry curtains such as components of metal accessories and frame bar were conducted with the microscope, p-XRF, and SEM. Result of frame bar pigments, organic pigments such as ink stick were likely been used in woolen tapestry curtain 1. In woolen tapestry 2, lead red (Minium) was used in the frame bar. The result of metal parts, copper, and zinc were analyzed by p-XRF. This suggests that metal accessories were crafted using brass. Frame bar of woolen tapestry curtain 2 was made of soft pine (Pinus spp.) analyzed with the scanning electron microscope. Artifacts like woolen tapestry curtains are rare in Korea and scientific analysis databases were scarce, so it is important to construct components analysis data of woolen tapestry curtains. It is expected that additional scientific analysis and interpretation on the artifact's crafting technique can be merged with the analytical data gathered in this study to be utilized on the conservation and restoration of not only woolen curtains but curtain artifacts of the late Joseon dynasty in general.

• 한국초전도ㆍ저온공학회논문지
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• 제20권4호
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• pp.36-40
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• 2018

In this study, the electromechanical properties in Sn-Cu double layer stabilized GdBCO coated conductor (CC) tapes with and without external lamination under uniaxial tension were examined at 77 K and self-field. Their irreversible stress and strain limits were determined using a loading-unloading scheme based on different critical current ($I_c$) recovery criteria. The repeated tests were performed and statistical estimation was done to check the reproducibility depending on the criterion adopted in evaluating the electromechanical properties. From the results, it showed that the Sn-Cu double-layer stabilized CC tapes have the higher irreversible stress limit, but lower irreversible strain limit as compared to brass laminated ones. Through the repeated tests, it can be found that a small scattering of irreversible limits existed in both CC tape samples. Finally, similar strain sensitivity of $I_c$ in both CC tapes was obtained.

• 대한방사선기술학회지:방사선기술과학
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• 제47권2호
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• pp.97-105
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• 2024

The examination needle used in ultrasound biopsy is a medical device used to determine whether there is an abnormality in the tissue. Typically, stainless steel is the standard material used for such needles; however, this study wanted to identify a material that could better enhance sound compared to traditional stainless steel. In this study, six types of needle materials available with the biopsy gun were inserted into pork and ultrasound images according to the curved probe and linear probe were evaluated using ultrasound equipment. The findings revealed significant improvements in ultrasound acoustic enhancement with alternative materials compared to stainless steel (p<0.05). The results regarding the depth of each ultrasound image using the curved probe showed that tungsten and brass had high sound enhancement(p<0.05), while with the linear probe, sound enhancement was high in brass, pla, aluminum, and copper(p<0.05). Due to these results, the previously used stainless needle showed lower ultrasound acoustic enhancement than the five types of materials being compared. Consequently, the outcomes of this study provide valuable insights for the development of new needle technologies aimed at minimizing patient risks and improving diagnostic accuracy.

• 한국의학물리학회지:의학물리
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• 제26권4호
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• pp.250-257
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• 2015

양성자 치료를 위해서는 Snout이 부착된 받침대(gantry)를 사용하는데 빔의 형태를 만들기 위해 환자 종양의 크기와 거리에 맞게 황동 차폐체(aperture)가 많이 사용된다. 또한 빔의 거리를 보정하기 위해 PMMA를 이용한 거리 보상체도 사용된다. 이렇게 황동으로 만들어진 차폐체의 경우 가공하는데 많은 시간이 소요되며 비용 발생이 높다. 또한 치료 사용되었던 차폐체의 방사선 노출에 따라 재사용이 어렵다. 이러한 단점을 보안하기 위해 황동 차폐체 대신 X-선 치료에서 사용되는 수동형 다엽 콜리메이터 시스템을 도입하였다. 수동형 다업 콜리메이터는 여러 개의 황동판을 조립하여 차폐체를 제작하는 방식이다. 본 연구는 제작된 수동형 다엽 콜리메이터의 방사화 실험 및 필름을 이용해 선량측정을 진행하였다. 다엽 콜리메이터를 투과한 2차 발생 선량 1% 이하였으며, 여러 번의 230 MeV의 빔에서도 방사화가 2시간 이내에서 감소하였다. 이렇게 개발된 수동형 다엽 콜리메이터를 임상에 적용하여 일반 차폐체와 수동형 다엽 콜리메이터를 감마지표 분석을 했을 시 99.74%의 높은 일치도가 측정되었다. 또한, 일반 황동 차폐체에 비해 수동형 다엽 콜리메이터를 제작하는데 소요되는 비용과 시간을 1/10 이상 단축시킬 수 있다. 개발된 수동형 다엽 콜리메이터는 성공적으로 양성자 환자치료에 사용하고 있다.

• Annals of Clinical Microbiology
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• 제21권4호
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• pp.80-85
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• 2018

배경: 본 연구는 국내 병원에서 분리된 methicillin 내성 Staphylococcus aureus (MRSA), vancomycin 내성 Enterococcus faecium (VREFM) 및 다제 내성 multidrug-resistant Pseudomonas aeruginosa (MRPA) 등에 대한 구리, 유기(구리 78%, 주석 22%), stainless steel의 살균력을 비교 실험하여, 국내 병원 환경에 의한 항생제 내성 균주 교차 감염을 예방하는 데 구리와 유기의 활용성을 분석하고자 하였다. 방법: MRSA, VREFM, MRPA 균주는 2017년 의정부성모병원에서 분리 동정된 wild type 3균주씩을 혼합하여 사용하였으며 모두 항생제 다제 내성 균주로 나타났다. MRSA, VREFM, MRPA 균주 각각을 Tryptic soy broth (Oxoid, England)에 접종하여 $35^{\circ}C$에서 24시간 배양한 후, 각각 초기 접종균액의 균수를 $10^5\;log\;CFU/mL$로 조정하였다. 구리, 유기, stainless steel 용기에 준비된 MRSA, VREFM, MRPA 접종균액 100 mL씩을 각각 접종한 후, 습도가 유지되도록 덮개를 덮은 후 $35^{\circ}C$ incubator에서 초기부터 9일까지 생존균수를 측정하였다. 결과: 본 연구결과 국내에서 분리된 항생제 다제 내성 MRSA, VREFM, MRPA 균주에 대한 구리 및 유기의 살균효과를 확인하였다. Stainless steel의 살균력은 구리 및 유기에 비해 매우 미약하였고, MRSA 및 VREFM에 비해 MRPA의 살균효과가 크게 나타났다. 결론: 교차감염을 예방하기 위하여 병원 내 문손잡이, 수도꼭지, 침대레일 등에 구리나 유기를 적용하여, 장기간 실험을 진행하고 있는 국외 사례와 같이, 국내 병원에서도 구리와 유기를 이용한 병원 내 교차 감염 예방 연구가 필요하다고 생각한다.

• 한국방사선학회논문지
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• 제14권7호
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• pp.891-898
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• 2020

최근 납으로 제작된 차폐체의 문제점이 대두되면서 대체 할 수 있는 차폐체 연구는 필수적이며 3D프린터로 진단용 X선 차폐체 제작에 관한 연구도 활발히 이루어지고 있다. 최근 금속 혼합 필라멘트의 개발로 쉽게 차폐제 제작이 가능해졌지만 3D 프린터의 노즐 크기나 출력설정에 관한 연구는 미비하다. 이에 본 연구는 Brass filament와 3D프린터로 노즐 크기와 층 높이에 따라 차폐체를 출력하고 진단용 방사선 발생장치를 이용하여 차폐율 실험을 통해 결과를 비교분석 하고자 한다. 노즐 크기는 0.4, 0.8 mm, 층 높이 0.1, 0.2, 0.3, 0.4 mm로 변화하여 출력하였고, 차폐율 시험은 40 mAs로 고정하고, 60, 80, 100 kVp로 각각 실험하여 차폐율을 분석하였다. 분석결과 노즐 크기와 층 높이에 따라 출력시간을 1/10로 줄일 수 있었으며, 1% 이상 차폐율도 높일 수 있는 것으로 분석되었다.