• Journal of Periodontal and Implant Science
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• v.31 no.3
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• pp.531-542
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• 2001

Periodontal debridement is most important procedure in periodontal treatment, because periodontal disease is the biofilm infection. The use of ultrasonic instrument has many clinical advantages compared to classical hand instrument. The introduction of newly developed ultrasonic scaler tips made the use of ultrasonic scaler popular. However the study of tooth substance removal according to the working parameters of ultrasonic scaler with newly developed tips is not sufficient. The purpose of this study is to evaluate the effects of working parameters of piezoelectric ultrasonic scaler with curette tip on casting gold removal. The working parameters was standardized by the sledge device which controls lateral force(0.5 N, 1.0 N, 2.0 N) and power setting was adjusted 2, 4, 8 in P mode and S mode and instrumentation time was 5 seconds. The defect depth and width were measured with profile meter and defect surface was examined by SME. The depth of defect was significantly large in S mode( $39.58{\pm}19.35{\mu}m$) compared to P mode( $8.37{\pm}6.98{\mu}m$). There was significant decrease of depth of defect between 1.0N($32.87{\pm}27.18{\mu}m$) and 2.0N( $14.86{\pm}15.04{\mu}m$). The area of defect was also significantly large in S mode($4482.42{\pm}3551.71{\mu}m^2$) compared to P mode( $922.06{\pm}960.32{\mu}m^2$). There was significant decrease of area of defect between 1.0N($3889.12{\pm}3936.00{\mu}m$) and 2.0N( $974.66{\pm}986.01{\mu}m$). The change of mode did not effect on the width of the defect. The change of power setting did not effect on the depth, width, and area of defect. In spite of limitation of this study it could be concluded that the use of piezoelectric ultrasonic scaler with curette tip on S mode could make significant tooth substance loss.

• Korean Journal of Metals and Materials
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• v.47 no.9
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• pp.580-585
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• 2009

The effects of shear speed and tip height on the high speed shear test of Sn-3.0wt.%Ag-0.5wt.%Cu ball joints were investigated. Solder balls of $450{\mu}m$ in diameter were reflowed at $245^{\circ}C$ on a FR4 PCB (Printed Circuit Board) in order to obtain a sample for the high-speed shear test. The UBM was comprised of Cu/Ni/Au, and the shear speed and tip height varied from 0.5 to 3.0 m/s, and from 10 to $135{\mu}m$, respectively. According to the experimental results, faster shear speed enhanced the shear strength of the solder joints, regardless of the tip height. The fraction of ductile (solder) fracture decreased when the shearing speed was raised from 0.5 to 3.0 m/s. With an increasing tip height from 10 to 50 and $135{\mu}m$, the fracture mode changed from pad lift to mixed (ductile and brittle) and ductile fracture, respectively, while the shearing energy also increased in the same order. The shear energy had a proportional relationship with the fraction of the solder fracture.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.552-555
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• 2004

The reliability issue of the probe tip/recording media interface is one of the most crucial concerns in the Atomic Force Microscope (AFM)-based recording technology. In this work, the tribological characteristics of the probe/media interface were investigated by performing wear tests using an AFM. The ranges of applied normal load and sliding velocity for the wear test were 10 to 50nN and 2 to 20$\mu$m/s respectively. The damage of the probe tip was quantitatively as well as qualitatively characterized by Field Emission Scanning Probe Microscope (FESEM) analysis and calculated based on Archard s wear equation. It was shown that the wear coefficient of the probe tip was in the order of 10$^{-4}$ ~ 10$^{-3}$ , and significant contamination at the end of the probe tip was observed. Thus in order to implement the AFM-based recording technology, tribological optimization of the probe/media interface must be achieved.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1478-1480
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• 1997

We investigated the breakdown characteristic of mineral oil according to applied voltage and tip radius. In this experiment, electrode system was point-plane geometry. The tip radius of needle was 5, 10, 20 and $25{\mu}m$, respectively. Applied voltage was AC and DC. We measured breakdown voltage for each tip radius with increasing electrode gap, 2mm to 10mm. Under nonuniform electric field, breakdown strength was higher when needle was negative than when needle was positive. Because it is polarity effects due to space charge. And the more sharp tip radius, whether we applied AC or DC, the higher breakdown strength. As tip radius increase, breakdown strength decreases exponentially.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.1-7
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• 1976

1) The decrease in strength of netting twines at the knot may be regarded to be due mainly to the frictional force acting on the tip of the knot. The knot strength T may be given by $$T=\frac{T_0}{1+{\mu}\frac{s}{\rho}\varrho^{\mu\theta}$$ were $T_0$ is the tensile strength of unknotted netting twines, $\mu$ the coefficient of friction beween two netting twines forming a knot, s the contact length between the tip and the netting twine compressing it, $\rho$ the radius of curvature of the compressing, and $\theta$ the angle at which the compressing rubs with another one in the vicinity of the opposite tip. 2) Knots are arranged in order of strength as follows : the reef knot pulled lengthwise $\risingdotseq$ the trawler knot pulled breadtwise the reef knot pulled breadthwise.

• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1544-1553
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• 2005

In this article, a micro cantilever array actuated by PZT films is designed and fabricated for micro fluidic systems. The design features for maximizing tip deflections and minimizing fluid leakage are described. The governing equation of the composite PZT cantilever is derived and the actuating behavior predicted. The calculated value of the tip deflection was 15 ${\mu}m$ at 5 V. The fabrication process from SIMOX (Separation by oxygen ion implantation) wafer is presented in detail with the PZT film deposition process. The PZT films are characterized by investigating the ferroelectric properties, dielectric constant, and dielectric loss. Tip deflections of 12 ${\mu}m$ at 5 V are measured, which agreed well with the predicted value. The 18 ${\mu}l/s$ leakage rate of air was observed at a pressure difference of 1000 Pa. Micro cooler is introduced, and its possible application to micro compressor is discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.5
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• pp.411-416
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• 2006

A new reading technology for the ultra-high density data storage device utilizing AFM technology was proposed and its experimental results were discussed in this paper. For the experiments, an about $2{\mu}m$ thick conductive polymer layer was spin-coated on the heavily doped n-type Si wafer and an about $0.1{\mu}m$ thick PMMA layer was also been spin-coated on it. After then, the $5{\times}5$ memory way was fabricated by making indents on the surface of the wafer with the heated AFM tip, and the data reading was performed by scanning the surface with the tip biased at 10 V and the measuring the current flowing out at the end of the tip. The experimental results clearly showed that the new data reading technology worked superbly. The current measured was about 0.92 pA at the cell with the indent, and it was not only below 0.31 pA at the cell without the indent, but also at the cell where the indent was erased.

• Journal of the Korean Wood Science and Technology
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• v.8 no.1
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• pp.22-27
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• 1980

Quantitative assessment of edge blunting of saw-teeth was carried out by TALYSURF. 1. Using the following equation, the real shape of a saw-tooth can be traced on the graph of TALYSURF. ${\frac{{\Delta}h}{h}}={\frac{V{\Delta}_x}{V_x}}$ {${\Delta}h$: vertical distance of stylus h: vertical distance in chart $V{\Delta}_x$: Velocity of stylus $V_x$: velocity of chart} 2. As shown on Fig 2, the error from stylus itself can be calculated by following equation. i) 13.8${\mu}{\leqq}$x<20.4${\mu}$ y=-0.2246x+4.59${\mu}$ ii) 0${\leqq}$x<13.8${\mu}$ y=${\sqrt{(-18{\mu})^2-x^2}}-1.42x+32.7{\mu}}$ 3. The relationship between profile of saw-tooth and error from stylus itself can be calculated by following equation. $E(%)=\frac{f(r){\times}{\frac{4}{18{\mu}}}}{f(R){\times}{\frac{R}{18.5{\mu}}}-f(r){\times}{\frac{r}{18{\mu}}}}{\times}100$ {E(%)${\frac{error\;of\;stylus}{dullness\;of\;saw\;tooth}}{\times}100$ r: radius of stylus tip R: radius of tip which is drawn in graph of talysurf f(r) : error of stylus f(R) : dullness of tip which is drawn in graph of talysurf} 4. The graph of maximum error and profile of saw-tooth was parabola.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1718-1723
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• 2007

The Probe Card is a test component which is to classify the good semiconductor chips before the packaging. The yield of semiconductor product can be better from analysis of probe test information. Recently the technology of the probe card needs narrow width and large amount of probe tip. In this research, the probe tip based on the MEMS(micro electro mechanical system) technology was designed and fabricated to improve the reliability of the test and to meet 2-dimensional Array of tip. The mechanical and electrical properties of proposed tip were evaluated and it has over 100,000 of repetition times in the condition of 5gf, $20{\mu}m$ Over Drive.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.681-684
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• 2002

To investigate thermal effects of silicon field emitter, we fabricated and characterized single silicon tips with various tip radii, which generate different joule heating. Through I-V and stability tests, the changes of emission characteristics and tip structures due to different tip heating were observed and discussed. From the results, we confirmed that the changes of emission characteristics due to thermal effects in silicon emitter could occur at relatively small emission currents and concluded that the thermal effects should be also considered under normal operation condition above 1 ${\mu}A$.