• 한국표면공학회지
• /
• 제55권6호
• /
• pp.390-397
• /
• 2022

Parylene-C which was mainly used for industries such as electronics, machinery and semiconductors has recently been in the spotlight in the medical field due to its properties such as corrosion resistance and biocompatibility. In this study we intend to derive a plan to improve the bonding strength of Parylene-C coating with the SUS304 base material for medical use which can be applied to various medical fields such as needles, micro needles and in vitro diagnostic device sensors. Through plasma pretreatment the bonding strength between Parylene-C and metal materials was improved. It was confirmed that the coated surface was hydrophobic by measuring the contact angle and the improvement of the surface roughness of the sample manufactured through CNC machining was confirmed by measuring the surface roughness with SEM. Through the above results, it is thought that it will be effective in increasing usability and reducing pain in patients by minimizing friction when inserting medical devices and in contact with skin. In addition it can be applied to various application fields such as human implantable stents and catheters, and is expected to improve the performance and lifespan of medical parts.

• 대한기계학회논문집A
• /
• 제29권9호
• /
• pp.1276-1281
• /
• 2005

Compound semiconductors are the semiconductors composed of more than two chemical elements. Lithium Tantalate$K_I$ wafer is used for several optical devices, especially surface acoustic wave(SAW) device. Because of the lithography in SAW device process, $LiTaO_3$ polishing is needed. In this paper, the commercial slurries $(NALC02371^{TM},\; ILD1300^{TM},\;ceria slurry)$ used for chemical mechanical polishing(CMP) were tested, and the most suitable slurry was selected by measuring material removal rate and average centerline roughness$(R_a)$. From these result, it was proven that $ILD1300^{TM}$ was the most suitable slurry for $LiTaO_3$ wafer CMP due to the chemical reaction between solution in slurry and material.

• 한국기계가공학회지
• /
• 제12권4호
• /
• pp.75-80
• /
• 2013

Single crystal sapphire being used in high technology industry is a brittle material with a high hardness and excellent physical properties. ELID(Electrolytic In-Process Dressing) grinding technology was applied to material removal machining process of single crystal sapphire wafer. Ultrasonic vibration which added to material using ultrasonic table was adopted to efficient ELID grinding of sapphire materials. The evaluation of the ground surface of single crystal sapphire wafer was carried out by means of surface measuring by using AFM(Atomic Force Microscope), surface roughness tester and optical microscope device. As the results of experiment, it was shown that more efficient grinding was conducted when using ultrasonic table. In case of using #170 grinding wheel, surface roughness of ELID ground specimen in using ultrasonic table was superior to ELID ground specimen without ultrasonic table. However, In case of using #2000 grinding wheel, surface roughness of ELID ground specimen in using ultrasonic table was inferior to ELID ground specimen without ultrasonic table.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2004년도 춘계학술대회 논문집
• /
• pp.34-41
• /
• 2004

The purpose of this paper is to look at the characteristics of surface finishing which is one of the form accuracies and to obtain the fundamental technical data from the process of machining with diamond tool through experiment and theoretical analysis. The experiments were conducted with domestic made ultra-precision machine and MCD.PCD tool, with aluminum alloyed material and brass being used for the work pieces. The goal of the size accuracy was set to 100nm. The most suitable tool nose radius and machining conditions were selected, and the variations of the surface roughness were observed using SEM method while machining the distance of up to 500km. These data were evaluated and they examined the variation of the machined surfaces while cutting up to 500km of machining distance. At the same time, the state for the wear of diamond tool nose was analyzed and carefully examined through the newest measuring device. Additionally, the characteristics of ultra-precision machining technology were studied through visual analysis.

• 한국생산제조학회지
• /
• 제23권6호
• /
• pp.590-595
• /
• 2014

We have investigated anamorphic prism lenses with distortions of 0.3-0.5%. We designed the plastic triangular lens and confirmed the minimum resolution using MTF graphs. Also we confirmed that the SVGA optical system can realize a resolution of $864{\times}648$ 56 megapixels. A distortion of about 0.5% aberration appears in the maximum field, and a finite beam aberration of about $15{\mu}m$ is confirmed. We made a mold based on the design data and completed the prism lens through exodus molding. We confirmed the shape error (< $30{\mu}m$) and surface roughness (> 40 nm) of the three sides. We made the video-information-display prototype glasses using prism lens by measuring the performance, we determined the distortion aberration (0.3%) and SVGA resolution. Our approach will enable fabrication of a portable large-screen display device for glasses and sunglasses for the domestic market and, after 2015, for the world market.

• 한국산학기술학회논문지
• /
• 제20권1호
• /
• pp.290-296
• /
• 2019

차량용 HUD는 자동차 전면 유리창에 안전 운전과 편의 운전 관련 다양한 정보를 표시해 주는 장치로 중요한 역할을 수행한다. 본 논문에서는 증강현실 기술에 적용이 가능한 대면적 비구면 자유형상 미러를 가공하기 위해 초정밀 가공기를 이용하여 가공을 실시하였고 그 결과를 측정하였다. 초정밀 다이아몬드 절삭은 정밀도가 높을 뿐만 아니라 표면 거칠기와 잔류 응력을 낮게 할 수 있어서 우수한 표면 무결성을 갖는 고급 부품의 생산에 유리하다. 또한 비구면 자유 형상의 몰드를 사용함으로써 광학 전달 함수의 개선, 왜곡 경로의 감소 및 특수 이미지 필드 곡률의 실현과 같은 장점을 얻을 수 있다. 이와 같은 비구면 자유형상 금형을 가공하기 위한 방법으로는 초정밀가공기를 이용한 다이아몬드 절삭 방법을 사용하였으며, 제작된 비구면 자유형상 미러 금형의 평가는 비구면 형상 측정기를 이용하여 실시하였다. 이러한 방법에 의해 $1{\mu}m$ 이하의 형상 정밀도(PV)와 $0.02{\mu}m$ 이하의 표면 거칠기(Ra)를 갖는 비구면 자유형상 금형을 제작할 수 있었다.

• 대한치과보철학회지
• /
• 제37권4호
• /
• pp.465-473
• /
• 1999

Bond strength of luting cements to dentin is a critical consideration for success of complete cast crowns. This study was performed to evaluate the relationship between surface characteristics of teeth prepared for complete cast crowns and retention of cemented restorations. Eighty artificial crowns were cast for standardized complete crown tooth preparations accomplished with the use of a special device on recently extracted human teeth. Coarse diamond(#102R, Shofu) and superfine finishing diamond(#SF102R, Shofu) burs of similar shape were used. Crowns in each group were randomly subdivided into few subgroups of 10 for luting cements selected for this study: zinc phosphate cement (FLECK' S), polycarboxylate cement (Poly-F), rein-forced glass ionomer cement (Fuji PLUS). and adhesive resin cement (Panavia 21). Retention was evaluated by measuring the tensile load required to dislodge the artificial crown from tooth preparations with an Instron testing machine, and analysed by one-way ANOVA and Student's t-test. The obtained results were as follows ; 1. When tooth preparation was done with coarse diamond bur, retentive force was diminished in order of Panavia 21 Fuji PLUS, FLECK'S, and Poly-F. Retentive forces showed the significant difference between Fuji PLUS group and FLECK'S group(p<0.001). 2. When tooth preparation was done with superfine diamond bur, retentive force was diminished in order of Fuji PLUS, Panavia 21, FLECK'S, and Poly-F. Retentive forces showed the significant difference between Panavia 21 group and FLECK'S group(p<0.001). 3. Retentive force in coarse tooth surfaces was significantly higher than that in superfine tooth surface with all luting cements(p<0.001), and cement residues were almost retained with-in the cast crown in all groups.

• 대한화장품학회지
• /
• 제31권3호
• /
• pp.253-257
• /
• 2005

피부노화의 정도를 판정하기 위해 사용되는 주름측정법들은 객관성과 재현성의 확보가 중요한 요소이다. 최근의 경향은 주름의 형태나 깊이에 주는 영향을 최소화하기 위해 주름 측정시 피부에 직접 기계나 도구를 접촉하지 않고 측정하는 비접촉식 측정방법으로 빠르게 전환되고 있는 상황이다. 저자들은 주름측정 기술의 변천 과정을 간단히 살펴보고, 비접촉식 fringe projection 방식의 미세주름 측정기기인 PRIMOS를 중심으로 측정원리, 특징들을 접촉식 측정방법인 모사판을 이용한 방법과 비교하였다.

• Structural Engineering and Mechanics
• /
• 제71권4호
• /
• pp.391-405
• /
• 2019

Compared to the ambient vibration test mainly identifying the structural modal parameters, such as frequency, damping and mode shapes, the impact testing, which benefits from measuring both impacting forces and structural responses, has the merit to identify not only the structural modal parameters but also more detailed structural parameters, in particular flexibility. However, in traditional impact tests, an impacting hammer or artificial excitation device is employed, which restricts the efficiency of tests on various bridge structures. To resolve this problem, we propose a new method whereby a moving vehicle is taken as a continuous exciter and develop a corresponding flexibility identification theory, in which the continuous wheel forces induced by the moving vehicle is considered as structural input and the acceleration response of the bridge as the output, thus a structural flexibility matrix can be identified and then structural deflections of the bridge under arbitrary static loads can be predicted. The proposed method is more convenient, time-saving and cost-effective compared with traditional impact tests. However, because the proposed test produces a spatially continuous force while classical impact forces are spatially discrete, a new flexibility identification theory is required, and a novel structural identification method involving with equivalent load distribution, the enhanced Frequency Response Function (eFRFs) construction and modal scaling factor identification is proposed to make use of the continuous excitation force to identify the basic modal parameters as well as the structural flexibility. Laboratory and numerical examples are given, which validate the effectiveness of the proposed method. Furthermore, parametric analysis including road roughness, vehicle speed, vehicle weight, vehicle's stiffness and damping are conducted and the results obtained demonstrate that the developed method has strong robustness except that the relative error increases with the increase of measurement noise.

• 대한치과보철학회지
• /
• 제38권5호
• /
• pp.704-723
• /
• 2000

This study was undertaken to evaluate the tensile bond strength of In-Ceram alumina core treat-ed by ion assisted reaction(IAR). Ion assisted reaction is a prospective surface modification technique without damage by a keV low energy ion beam irradiation in reactive gas environments or reactive ion itself. 120 In-Ceram specimens were fabricated according to manufacturer's directions and divided into six groups by surface treatment methods of In-Ceram alumina core. SD group(control group): sandblasting SL group: sandblasting + silane treatment SC group: sandblasting + Siloc treatment IAR I group: sandblasting + Ion assisted reaction with argon ion and oxygen gas IAR II group: sandblasting + Ion assisted reaction with oxygen ion and oxygen gas IAR III group: sandblasting + Ion assisted reaction with oxygen ion only For measuring of tensile bond strength, pairs of specimens within a group were bonded with Panavia 21 resin cement using special device secured that the film thickness was $80{\mu}m$. The results of tensile strength were statistically analyzed with the SPSS release version 8.0 programs. Physical change like surface roughness of In-Ceram alumina core treated by ion assistad reaction was evaluated by Contact Angle Measurement, Scanning Electron Microscopy, Atomic Force Microscopy; chemical surface change was evaluated by X-ray Photoelectron Spectroscopy. The results as follows: 1. In tensile bond strength, there were no statistically significant differences with SC group, IAR groups and SL group except control group(P<0.05). 2. Contact angle measurement showed that wettability of In-Ceram alumina core was enhanced after IAR treatment. 3. SEM and AFM showed that surface roughness of In-Ceram alumina core was not changed after IAR treatment. 4. XPS showed that IAR treatment of In-Ceram alumina core was enabled to create a new functional layer. A keV IAR treatment of In-Ceram alumina core could enhanced tensile bond strength with resin cement. In the future, this ion assisted reaction may be used effectively in various dental materials as well as in In-Ceram to promote the bond strength to natural tooth structure.