• 터널과지하공간
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• 제32권4호
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• pp.243-253
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• 2022

본 연구에서는 회전식 절삭시험기를 활용하여 TBE (Tunnel Boring Extender)의 굴착효율을 평가하였다. 회전식절삭시험에서 TBE에 의한 굴착과정을 모사하기 위하여 중앙부가 선행 굴착되어 있는 중공형의 암석모사시험체를 모르타르를 이용하여 제작하였다. 회전식 절삭시험기에 설치된 언더커팅 디스크(undercutting disc cutter, UDC)를 이용하여 나선궤적을 따라 암석을 절삭함으로써 TBE에 의한 굴착과정을 모사하였으며, 언더커팅 디스크의 절삭조건을 변화시켜가며 절삭조건들이 커터작용력 및 비에너지에 미치는 영향을 살펴보았다. 시험결과로부터 UDC의 커터작용력은 반경압입깊이와 수직압입깊이가 증가함에 따라 선형적으로 증가하는 경향을 확인할 수 있었으며, 세 방향의 작용력 중 수직력의 비중이 매우 크게 나타났다. 반면 비에너지는 반경방향과 수직방향 압입깊이에 따라 지속적으로 감소하는 경향을 나타내었고, 특히 두 압입깊이의 비에 따라 비에너지가 최소화되는 지점이 나타날 것으로 판단되었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
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• pp.107-110
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• 2000

In this experiment, we fabricated pyramid-type silicon tunneling devices in which a tunneling current flow between a micro-tip and Si$_3$N$_4$ thin film membrane. A MEMS process was used for the fabrication of the tunneling devices. The micro-tips were formed on Si wafers by undercutting a differently oriented square of SiO$_2$ with KOH. The stiffness of the Si$_3$N$_4$ films were observed and the model for the stiffness calculation, which is useful in predicting the stiffness even when the stiffness ranges beyond the scope of the normal experimental condition, was suggested.

• 센서학회지
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• 제3권1호
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• pp.19-25
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• 1994

KOH와 같은 이방성 식각수용액를 사용하여 직각모양의 볼록한 가장자리를 식각할 때, 언더컷팅에 의해 가장 자리가 뭉개어지는 현상이 나타난다. 그래서 이 현상을 방지하기 위해 mass 패턴을 수정할 필요가 있어 보상법에 관한 실험을 하였다. 가속도센서 소자공간을 고려할 경우 정사각형의 보상구조로 mass를 보상하는 것이 적당하다는 결과를 얻었다. 이 결과를 기초로, SDB 웨이퍼를 이용하여 사각뿔 형태의 mass 보상된 실리콘 압저항형 가속도센서를 제조하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.23-26
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• 1997

This work presents the TMAH/IPA anisotropic etching characteristics with addition of Pyrazine. (100) Si etching rate of 0.747 ${\mu}{\textrm}{m}$/min at 8$0^{\circ}C$ was obtained using TMAH 25 wt.% / IPA 17 vol.% / pyrazine 0.1 g. The etching rate of (100) Si is increased about 52% compare to pure TMAH 25 wt.%. But etching rate of (100) Si is decreased with increasing Pyrazine additive. Activation energy of TMAH/IPA/pyrazine is much lower than TMAH and TMAH/IPA solutions. Addition of Pyrazine does not effect on surface flatness and decreases undercutting ratio about 20 %. Therefore, TMAH/IPA/pyrazine is an attractive anisotropic etchant because of alkaline-ion free.

• 한국정밀공학회지
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• 제15권4호
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• pp.7-14
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• 1998

Noncircular gears have been used for obtaining the modified anglualr velocity ratio between parallel axes. The elliptical gear, which is a kind of noncircular gears, makes use of ellipse as a pitch curve, and is applied for the measurement of the discharge of liquid. The applications of an elliptical gear are more advantageous than any other mechanism as like a crank-slider linkage or a cam mechanism in view of the accuracy and the reliability to transmit the prescribed motion. In this paper, acceding to the theoretical involute tooth profile, two pairs of the elliptical gears were manufactured by using CNC wire electronic discharge machine. The proper ranges of the operating pressure angle and of module not to generate under cutting are studied on the change of the eccentricity, because it is the eccentricity of the pitch curve that determines most of the characteristics of the elliptical gear and then the vibration analysis is executed for the verification of harmonious rotating.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1224-1226
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• 2003

In this work, we developed a high resolution printing technique based on transferring a pattern from a PDMS stamp to a Pd and Au substrate by microcontact printing Also, we fabricated various 2D metallic and polymeric nano patterns with the feature resolution of sub-micrometer scale by using the method of microcontact printing (${\mu}$CP) based on soft lithography. Silicon masters for the micro molding were made by e-beam lithography. Composite poly(dimethylsiloxane) (PDMS) molds were composed of a thin, hard layer supported by soft PDMS layer. From this work, it is certificated that composite PDMS mold and undercutting technique play an important role in the generation of a clear SAM nanopattern on Pd and Au substrate.

• Journal of Chest Surgery
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• 제33권4호
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• pp.316-319
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• 2000

Double-outlet left ventricle with ventricular septal defect and pulmonary stenosis was conventionally repaired with extracardiac conduit or pulmonary artery translocation. Here, we report an anatomically repaired double-outlet left ventricle without extracardiac conduit or pulmonary artery translocation in an 11 month old patient who had undergone palliative systemic-pulmonary shunt at a nonatal period. The location of ventricular septal defect, both great arteries and coronary arteries made it possible to reconstruct the right ventricular outflow tract using on-lay patch after incision and undercutting the tissue between the ventriculotomy and the pulmonary arteriotomy.

• Journal of Korean Vacuum Science & Technology
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• 제3권1호
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• pp.24-29
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• 1999

The characteristic behaviors of CH3Br were examined first for the dry etching of polysilicon in a Cl2/CH3Br/O2 plasma. CH3Br is revealed one of the excellent additive gases to control anisotropy of etching profile and to give no undercutting for various typed of polysilicons. CH3Br acts as a passivation precursor on the side wall in etch cavity by forming polymer-like films such as CHxBry(x+y=1,2). The decrease of etch selectivity due to the reaction if the C-containing species from CH3Br with the surface O atoms of SiO2 was overcome by the addition of O2 into plasma, resulting that the selectivity increased by 2~3 times. According to the results of optical emission signals, CH3Br should be dissociated into several fragments to give more hydrogen atoms than bromine atoms in our helical resonator system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.334-337
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• 1996

Si anisotropic etching is a key technology for micromachining. The main advantages of tetramethyl ammonium hydroxide (TMAH)-based solution are their full compatibility with IC process. In this work the anisotropic etching of single crystal Si in a TMAH (($CH_3$)$_4$NOH) based solution was studied. The influence of the addition of IPA to TMAH solution on their etching characteristics was also presented. The crystal planes bounding the etch front and their etch rates were determined as a function of temperature, crystal orientation, and etchant concentration. The etch rates of (100) oriented Si crystal planes decreased linearly with increasing the IPA concentration, The etched (100) planes were covered by Pyramidal-shaped hillocks below 15 wt.%, but very smooth surfaces were obtained above 20 wt.%. The addition of IPA to TMAH solution leads to smoother surfaces of sidewalls etched planes.

• Journal of Welding and Joining
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• 제35권1호
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• pp.43-48
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• 2017

Pulse TIG (Tungsten Inert Gas) welding is often considered the most difficult of all the welding processes commonly used in industry. Because the welder must maintain a short arc length, great care and skill are required to prevent contact between the electrode and the workpiece. Pulse TIG welding is most commonly used to weld thin sections of stainless steel, non-ferrous metals such as aluminum, magnesium and copper alloys. It is significantly slower than most other welding techniques and comparatively more complex and difficult to master as it requires greater welder dexterity than MIG or stick welding. The problems associated with manual TIG welding includes undercutting, tungsten inclusions, porosity, Heat affected zone cracks and also the adverse effect on health of welding gun operator due to amount of tungsten fumes produced during the welding process. This brings the necessity of automation. Hence, In this paper an attempt has been made to build a customerized setup of Pulse TIG welding based on through review of Pulse TIG welding parameters. The cost associated for making automated TIG is found to be low as compared to SPM (Special Purpose machines) available in the market.