• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.7
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• pp.327-333
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• 2002

In this study, we developed a snoring detection algorithm that detects snores automatically. It consists of preprocessing and snoring detection part. The preprocessing part is composed of a noise removal part using spectrum subtraction, and segmentation part, and computation part of temporal and spectral features. And the snoring detection part decides whether detected blocks are snores with BPNN(Back-Propagation Neural Network). BPNN with one hidden layer and one output layer, is trained with data of 7 subjects and tested with data of 11 subjects of total 18 subjects. The proposed algorithm showed a Sensitivity of 90.41% and a Predictive Positive Value of 84.95%.

• Transactions on Electrical and Electronic Materials
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• v.1 no.1
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• pp.6-11
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• 2000

The hydrogen plasma treatment of silicon wafers in the reactive ion-etching mode was studied for the application to silicon-on-insulator wafers which were prepared using the wafer bonding technique. The chemical reactions of hydrogen plasma with surface were used for both surface activation and removal of surface contaminants. As a result of exposure of silicon wafers to the plasma, an active oxide layer was found on the surface. This layer was rendered hydrophilic. The surface roughness and morphology were examined as functions of the plasma exposing time and power. In addition, the surface became smoother with the shorter plasma exposing time and power. The value of initial surface energy estimated by the crack propagation method was 506 mJ/㎡, which was up to about three times higher as compared to the case of conventional direct using the wet RCA cleaning method.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1475-1477
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• 1998

In this paper, breakdown strength and time to breakdown are experimented under semiconducting layer/needle electrode in XLPE which is used for power cable insulator. Shape and scale parameters of obtained data are estimated using 2-parameters Weibull distribution. Life-time coefficient(n-value) using shape parameters for breakdown strength and time to breakdown tests is estimated. n-value of 1000 hour aged XLPE showed higher value than that of virgin XLPE. Increase of n-value is estimated by the stability due to removal of by-product and residue gas in XLPE by heating.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.235-235
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• 2010

The Anti-reflection coating(ARC) properties can be formed on silicon substrate using a simple electrochemical etching technique. This etching step can be improve solar cell efficiency for a solar cell manufacturing process. This paper is based on the removal of silicon atoms from the surface a layer of porous silicon(PSi). Porous silicon is form by anodization and can be obtained in an electrolyte with hydrofluoric. It have demonstrated the feasibility of a very efficient porous Si layer, prepared by a simple, cost effective, electrochemical etching method. We expect our research can results approaching to lower than 10% of reflectance by optimization of process parametaer.

• Transactions of Materials Processing
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• v.21 no.6
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• pp.354-359
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• 2012

Effects of a nitriding treatment on the tensile and high cycle fatigue properties were investigated by conducting ion-nitriding and gas nitro-caburizing treatments on the spheroidized SCr430B medium-carbon steel and performing tensile and tension-tension high cycle fatigue tests. The nitrided samples showed much lower strength and ductility compared to those in the initial as-spheroidized state and premature fracture occurred at the hardened layers. The micro-voids in the compound layer caused fatigue crack initiation. Thus, the removal of the compound layer with micro-voids remarkably improved the fatigue resistance to even beyond that of the as-spheroidized sample.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.574.2-574
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• 2001

The objective of this study was to evaluate the effect of EDTA irrigant depending on application times and temperatures. 31 human mature extracted teeth with a single canal and a closed apex were sectioned with microtome in 3mm thickness. They were distributed randomly into 6 groups of 10 specimens each and control group of 2 specimens. Each specimen was prepared with $GT^{TM}$ rotary file (Dentsply, Maillefer Co., Swiss) and irrigated with 3ml sodium hypochlorite every minute. Then smear layer wasn removed with EDTA solution ($PULPDENT^{\circledR}$, PULPDENT Co., USA.) except two control specimens. Specimens of each group were irrigated with 17％ EDTA.(omitted)

• Journal of Welding and Joining
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• v.32 no.1
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• pp.108-111
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• 2014

Low arc weldability of aluminum alloy is enhanced by applying variable polarity TIG and the result is theoretically investigated to figure out the mechanism. Conventionally, it is well known fact that DCEP (reverse polarity) arc is effective on aluminum welding. The reason is due to oxide layer removal by plasma ion bombardment and therefore it is named as cleaning effect. Another fact of polarity characteristic is that DCEN shows higher heat input efficiency therefore conventional variable polarity arc used to apply DCEP portion as small as possible. However, higher DCEP portion shows bigger weldment in this research and it is explained by adopting a theory of arc concentration on oxide layer with tunneling effect which was not clearly mentioned before in several variable polarity TIG welding research. Disagreement between variable polarity TIG welding result and conventional arc polarity theory is rationally explained for the first time with help of electron emission theory.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.22-29
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• 2004

As a result of high integration of semiconductor device, the global planarization of multi-layer structures is necessary. So the chemical mechanical polishing(CMP) is widely applied to manufacturing the dielectric layer and metal line in the semiconductor device. CMP process is under influence of polisher, pad, slurry, and process itself, etc. In comparison with the general CMP which uses the slurry including abrasives, fixed abrasive pad takes advantage of planarity, resulting from decreasing pattern selectivity and defects such as dishing & erosion due to the reduction of abrasive concentration especially. This paper introduces the manufacturing technique of fixed abrasive pad using hydrophilic polymers with swelling characteristic in water and explains the self-conditioning phenomenon. And the tungsten CMP using fixed abrasive pad achieved the good conclusion in terms of the removal rate, non-uniformity, surface roughness, material selectivity, micro-scratch free contemporary with the pad life-time.

• Journal of Surface Science and Engineering
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• v.32 no.3
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• pp.410-415
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• 1999

The adhesion strength of sputtered copper films to Inconel substrates has been studied using the scratch test. The effects of substrate treatments before deposition such as chemical or ion bombardment etching were investigated by means of a mean critical load derived from a Weibull-like statistical analysis. It was found that the mean critical load was very weak unless the amorphous layer produced by mechanical polishing on the substrate surface was eliminated. Chemical etching in a nitric-hydrochloric acid bath was shown to have practically no effect on the enhancement of the adhesion. In contrast, the addition in this bath of nickel and copper sulphates allowed removal of the amorphous layer and an increase in the values of the mean critical load. However, it was observed that excessive chemical etching could cancel out the mean critical load enhancement. The results obtained in the case of ion bombardment etching pretreatments could be far higher than those obtained with chemical etching. Moreover, for a sufficiently long period of ion bombardment etching, the adhesion strength was so high that it was impossible to observe evidence of an adhesion failure.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.2
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• pp.149-155
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• 1997

잔류응력을 측정하는 비파괴 방법중 Neutron diffraction technique의 발달로 인하여 기존의 X-ray diffraction technique에 비하여 잔류응력 측정가능 두께가 대부분의 물질에 있어서 훨씬 깊어졌다. 비파괴 방법으로 부품내의 잔류응력 분포가 측정되어진 경우, 부품의 가공시 잔류응력의 재분포로 인한 형상의 변화를 정량적으로 예측할 수 있는 방법에 대해 어떠한 경우도 논의된 바 없다. 본 연구에서는 축 방향의 잔류응력이 내재하는 strip의 층 가공시 일어나는 strip의 곡율변화를 정량적으로 예측할 수 있는 수식을 제시하였다. 간단히 컴퓨터 프로그램화 할 수 있는 수식을 전개하므로 써 현장에서 유용하게 이용할 수 있게 하였다.