• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.382-383
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• 2008

In this paper we presented experimental results of a gas sensor utilizing multi-walled carbon nanotube (MWNT)composites for the alcohol detection which is useful to checking drinking and driving, for example. The MWNT-composites were deposited using spray method on PES substrates suitable for use in low-cost and flexible sensors. We observed the variation of conductance from the sensors exposed to alcohol vapors evaporated at 37C equal to the human body temperature to match real condition. As the result, the conductance was decreased with the increase of ethanol vol% diluted in water. The sensors showed good sensitivity and linearity.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.123-129
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• 1998

Ceramic and CBN tools are available for the difficult-to -cut-materials such as hardened carbon tool steel. stainless steel and etc. Ceramic tools are suitable for continuous turning cut, not for intermittent milling cut. Ceramic tools are likely to be chipped and abruptly broken before the appearance of normal wear in turning. In this study, TiN coated ceramic tools were found to restrain the chipping, breaking and early fracture and to increase the critical cutting velocity owing to TiN coating in PVD method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.173-174
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• 2006

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.115-121
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• 2007

Phase contrast imaging in atomic force microscopy showed a promise as an effective tool for better understanding of micromechanical properties of surfaces at nano scale. A qualitative estimation model for phase contrast images obtained with a tapping mode AFM was developed. This investigation demonstrated the high efficiency of combined analysis of topography and phase contrast images for characterizing nanosurfaces. Phase contrast images allowed estimation of relative stiffness(elastic modulus) of the sample surface. The phase contrast images revealed a significant inhomogeneity of the nano scale worn surfaces. Phase contrast images are also capable of revealing the formation of tribofilms.

• Journal of Welding and Joining
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• v.20 no.4
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• pp.538-543
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• 2002

M/S TB(Mash Seam Tailored Blank) is a production method for blanks by welding together blanks of different material, thickness and coating, and is an attractive method for manufacturing car body because it makes parts lighter and can save the cost and time to manufacture. However, there have not been quantified criteria to evaluate the quality of TB weld. This study introduced FHR (failure height ratio) in order to assess formability or/and weldability of the M/S welds and the applicability of FHR was confirmed by actual auto body forming and FLD tests. Furthermore, a new parameter, HN(heat number) based on the heat input of "$Q=I^2Rt$" was proposed and assessed. It was found that the concept of HN could be utilized to evaluate the soundness of M/S welds without any destructive tests.ive tests.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.307-314
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• 1999

By using AIP(Arc Ion Plating) of a physical vapor deposition for the first time in Korea a ceramic tool whose surface is coated single layeredly with TiN is developed. In addition, cutting resistance appearing in the process of finishing cut of hardened carbon tool steel, STC3 is studied. The principal and radial components of cutting resistance in those cutting conditions appear to be the same or similar, and the feed component is relatively small. The feed component is found to be in proportion to cutting width, and the radial component in proportion to cutting thickness. Owing to coating the cutting resistance of a TiN coated ceramic tool increases compared with that of a general ceramic tool.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.65-66
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• 1994

This paper describes study on the preparation of ferrite powder for bonded mallets. The specimen which has the basic composition of SrO$.$nF$_2$O$_3$ with n=5.9 is in nonstoichiomatric region. Calcination is performed under N$_2$ atmosphere 1175$^{\circ}C$, 1200$^{\circ}C$, 1225$^{\circ}C$, 1250$^{\circ}C$ and 1275$^{\circ}C$ respectively. Then, Cooling is carried out in the furnace. In order to increase coecivity and obtain uniform grain size, we add to the specimen 0.7wt%CaCO$_3$, 0.3wt % SiO$_2$, 0.5wt%Na$_2$SiO$_3$ and 0.5wr% Al$_2$O$_3$. Also, in order to increase milling effect, carbon coating on sample particles is tried. As the result, single magnetic domain partic1e with Size of 1$\mu\textrm{m}$ in obtained and magnetic properties are improved.

• Journal of Surface Science and Engineering
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• v.24 no.1
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• pp.8-8
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• 1991

To investigate the effects of substrate on transverse-rupture strength(TRS) and bonding strength between substrate and TiC layer coated by CVD, two kinds of substrate (substrate A:WC-9.5wt%Co-MC*[low C], substrate B: WC-6wt% Co-MC*[high C] were studied in terms of Cobalt and C contents respectively. For preparation of test samples the coating parameters of deposition time, deposition temperature and deposition pressure were varied. The result show that the carbon contents in substrates have greater effects on the TRS of the CVD TiC coated cemented carbide than Co contents in substrates.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.4
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• pp.369-374
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• 2009

In micro/nano-scale contacts in MEMS and NEMS, capillary and van der Waals forces generated around contacting micro-asperities significantly influence the performance of concerning device as they are closely related to adhesion and stiction of interacting surfaces. In this regard, it is of prime importance to accurately estimate the magnitude of surface forces so that an optimal solution for reducing friction and adhesion of micro/nano-surfaces may be obtained We introduced an effective method to calculate these surface forces based on topography information obtained from an atomic force microscope. This method was used to calculate surface forces generated in the contact interface formed between diamond-like carbon coating and $Si_3N_4$ ball. This method is shown to effectively demonstrate the influence of capillary force in the contact area, especially in humid atmosphere.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.92-92
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• 2000

Ni을 coating 하지 않은 Si 기판에 바이어스를 인가하여 기존의 아이아몬드 결정입자가 아닌 탄소 튜브와 유사한 whisker 형태의 탄소 막을 Hot filament CVD 법으로 증착하였다. 제작된 시료는 SEM, Raman, 그리고 XRD로 형상과 성분, 그리고 결정구조를 분석하여 전계 방출 소자로 이용하기 위한 기본적인 전계방출 특성을 조사하였다. Raman 스펙트럼에 의한 조사 결과 whisker의 구성성분은 비정질 흑연임을 확인하였다. 증착 시 바이어스 전압이 높아짐에 따라 whisker의 형태가 가늘고 길어지는 경향을 보였으며 CH4 농도와 기판 온도가 증가할수록 whisker의 지금이 커지는 현상을 나타내었다. 방출전류밀도는 가늘고 긴 whisker 일수록 증가하는 경향을 나타내었다. 또한 NH3를 첨가한 결과 매우 뾰족한 원뿔의 형태로 증착되었으며 구동전압이 2 V/$\mu$m의 낮은 값을 나타내었다. 따라서 whisker를 전계 방출 소자로 사용할 경우 구성성분이 흑연이며 그 형태가 침상 또는 원뿔이므로 구동전압이 낮아지고 방출 전류가 증가하는 등 향상된 전계 방출 특성을 나타내었다.