• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.676-680
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• 2008

TiN thin films were deposited on a $SiO_2(2000{\AA})/Si$ substrate by radio-frequency(rf) magnetron sputtering. TiN films were prepared under varying $N_2$ concentration in $N_2/Ar$ gas mix, rf power and gas pressure, and investigated in terms of deposition rate, resistivity and surface morphology. As $N_2$ concentration increased, the deposition rate and the surface roughness of the films decreased and the resistivity increased. With increasing rf power, the deposition rate increased but the resistivity was decreased. As gas pressure increased, little change in deposition rate was obtained but the resistivity rapidly increased. TiN film with resistivity of $2.46{\times}10^{-4}{\Omega}cm$ at 1 mTorr was formed. It was observed that there existed a correlation between the deposition rate and resistivity. In particular, the gas pressure has a strong influence on the resistivity of thin films.

• Journal of the Korean Geographical Society
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• v.42 no.4
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• pp.506-525
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• 2007

Incision into bedrock channel is the primary control of landform evolution, but research into bedrock incision process stagnated for long time. Due to the scaling problem of the application of results from flume studies to bedrock channel, there is a strong need to simulate the bedrock incision process with more realistic models. As a part of investigation into controls of bedrock channel incision, three-dimensional changes of rock surface with abrasion was investigated with physical modelling. 18 rock plates were abraded with various sediment particle size and sediment load and abraded surfaces of the plates were scanned with high resolution 3-D scanner. To identify the spatial pattern of erosion of the rock plates, various methods were used. There was no synthetic or holistic method that showed all features of bedrock plate produced by abrasion, so each plate was analyzed using some available methods. Contour maps, shaded relief maps and profiles show that abrasion concentrated on the centre of plate (cross profile) and upstream and downstream edges (longitudinal profile) and eroded area extended inwards. It also found that the cracks and boundaries of forming materials easily eroded than other parts. Changing patterns of surface roughness were investigated with profiles, regression analysis and spectral analysis. Majority of plates showed decrease in small-scale roughness, but it depends on microstructures of the plates rather than general hardness or other factors. SEM inspection results supported this idea.

• Tunnel and Underground Space
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• v.16 no.2 s.61
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• pp.166-178
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• 2006

Recently, the frequency of occurring dynamic events such as earthquakes, explosives blasting and other types of vibration has been increasing. Besides, the chances of exposure for rock discontinuities to free faces get higher as the scale of rock mass structures become larger. For that reason, the frictional behavior of rock joints under dynamic conditions needs to be investigated. In this study, artificially fractured rock joint specimens were prepared in order to examine the dynamic frictional behavior of rough rock joint. Roughness of each specimen was characterized by measuring surface topography using a laser profilometer and a series of shaking table tests was carried out. For mated joints, the static friction angle back-calculated ken the yield acceleration was $2.7^{\circ}$ lower than the tilt angle on average. The averaged dynamic friction angle for unmated joints was $1.8^{\circ}$ lower than the tilt angle. Displacement patterns of sliding block were classified into 4 types and proved to be related to the first order asperity of rock joint. The tilt angle and the static friction angle for mated joints seem to be correlated to micro average inclination angle which represents the second order asperity. The tilt angle and the dynamic friction angle for unmated Joints, however, have no correlation with roughness parameters. Friction angles obtained by shaking table test were lower than those by direct shear test.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.254-259
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• 1997

The measurement of surface roughness and waviness by means of noncontact method is an important area to be developed for GAC(Geometrical Adaptive Control) system. This paper deal with the design of noncontact in-process measurement system which measures the surface roughness and waviness during cylindrical grinding. This measuring system is simple and the apparatus proposed is composed of a laser unit, photodetector and optical system. During operation, the surface of a workpiece is continuously scanned by a laser beam. This method makes it possible to detect the surface roughness and waviness along the feed direction by control the spot diameter of laser beam. The experimental results show that the presence of chattering, loading and glazing can be detected sensitively along the feed directions.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1443-1444
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• 2011

플렉시블 OLED 소자에서 주요한 역할을 하는 기판은 디스플레이의 성능, 신뢰성과 가격을 결정한다. 플렉시블 OLED소자의 기판으로는 PET, PC, PES, PEN과 같은 고분자 계열의 기판이 많이 사용되고 있지만 거칠기 등의 문제가 있는 것으로 알려져 있다. 본 논문에서는 셀룰로오스 종이를 사용하는 투명 플렉시블 OLED 소자를 개발하였다. 본 논문에서는 개발한 셀룰로오스 종이의 표면 거칠기는 $3.1{\AA}$이었으며, 투과도는 97.6%로서 PET기판 보다 우수한 특성을 보여주었다. 셀룰로오스 종이를 기판위에 양극으로 Ni을 이용하는 녹색 발광 플렉시블 OLED소자를 구현하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.182-187
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• 1994

트위스트 드릴을 사용한 구멍은 구멍가공중 가장 경제적인 방법중의 하나이다. 그러나 트위스트 드릴에 의한 가공은 길이에 대한 구멍경의 비가 한정되어 있다. 깊이/직경(L/D)의 비가 통상 5배 이상의 경우의 적절한 가공방법은 거압력의 절삭유를 공급할 수 있는 공구를 사용하여 가공하고 있으며, 그 대표적인 방법은 Long drull, Gun drill, BTA drill 및 Ejector drill등이 있다. 이들 방법중 BAT drill은 다른 가공공구에 비하여 우수한 가공능율을 갖고 있다. 그러나 BAT드릴에 의한 심공가공은 1회 가공에 의하여 요구되는 품질을 만족시켜야 함으로 이에 대응한 연구가 요구되고 있다. 따라서 본 연구는 BAT드릴링 시스템에 BAT drrill을 사용하여 심공가공할때 공작물의 형상 즉 표면 거칠기 및 지원도등 미치는 영향에 대하여 실험을 통하여 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.192.1-192.1
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• 2013

본 연구는 기존의 Sputtering 방식에 Modulation 방식을 적용한 Modulated Sputtering System (MSS)에 관한 특성 관찰과 이를 이용한 박막 증착 및 분석에 관한 내용이다. MSS에 인가하는 전압은 pulse on 시간동안 타겟에 음의 전압이 인가되어 sputtering에 의한 박막이 증착되고, pulse off 시간동안에는 양의 전압을 인가하여 증착된 박막에 양이온을 입사시켜 에너지 전달에 의한 박막의 특성을 향상시키고 자한다. MSS에 인가되는 전압과 주파수, 그리고 펄스폭을 변화시키며 전압과 전류, 그리고 기판에 입사하는 이온에너지 특성을 관찰하였다. 또한 MSS를 이용하여 티타늄(Ti), 탄소(C), 알루미늄이 도핑된 산화아연(AZO) 박막을 증착하였다. 증착된 박막은 a-step, SEM, XRD, AFM, 4 point probe를 이용하여 박막의 두께, 결정성장면, 표면 거칠기, 비저항 등을 분석하였다. Ti 박막에서는 기판에 입사되는 양이온의 에너지가 증가함에 따라 결정 방위면이 (002)에서 (001)로 변화함을 확인하였고 탄소 박막과 AZO 박막의 경우에는 기판에 입사되는 양이온의 에너지 변화에 따라 박막의 전도도를 조절할 수 있음을 확인하였다.

• International Journal of Highway Engineering
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• v.10 no.1
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• pp.135-144
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• 2008

The dynamic loads imposed by moving vehicles have variations in the magnitude due to the surface roughness of the pavement systems and the larger dynamic loads than the design loads may affect the pavement performance. This paper presents variations of the moving dynamic vehicle loads due to the pavement surface roughness. This study was performed as a basic study to apply the pay factor to the surface roughness for the improvement of pavement quality and performance. The profile data was obtained from the old and new pavements and the analysis was performed to investigate the dynamic loads when vehicles move on the pavements having those profiles. The artificial profiles were also developed to find the effects of the vehicle speed, wavelength and amplitude of the surface roughness on the dynamic vehicle loads. The increase in the load magnitude due to the surface roughness affects the stresses and strains of pavements and finally reduces the pavement life. The methodology to obtain the relationship between the surface roughness and the pavement performance was proposed in this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2735-2738
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• 2011

To obtain the Si solar cells, the Si-wafers were textured by using the IPA+DI water mixed solution with KOH acids during the various 1~40 minutes at the temperature with $80^{\circ}C$, respectively. The samples were analyzed by the scanning electron microscopy for the surface images and the solar simulation for I-V measurement system. It was researched the correlation between the efficiency of solar cells and the effect of texturing. From the results of the surface images obtained by SEM, the efficiency was increased at the sample textured uniformly, and the efficiency of over etched-samples decreased.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.3
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• pp.127-132
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• 2020

In this study, the process of providing information necessary to remove physical barriers such as road slopes that obstruct the activities of the disabled is in progress. Through experiments, we implement a quantified road surface roughness index that enables the implementation of IoT-based systems necessary for the elderly and the disabled to safely move to their destination. As a preliminary study, a road surface measurement device using a gyroscope was devised. To check the roughness and flatness of the road surface, X, Y displacement, and acceleration displacement were measured using a gyroscope. By calculating the measured data, the roughness and flatness of the road surface were quantified from 0 to 100. We implemented an algorithm that divides this index into 4 stages, displays it on a map, and provides it to users. Finally, a system for the disabled and elderly electric wheelchair users to secure basic mobility was established.