광섬유센서에 의한 간이 비접촉 표면조도 측정기의 개발

홍준희 대한공업교육학회 2009 대한공업교육학회지 Vol.34 No.2

The purpose of this study was to develop the handy non-contact measurement device of the surface roughness by using the optical fiber sensor. The advantages of fiber optic sensors are high-speed responsibility, non-effect of the magnetic, convenience of the product and high precision. The measurement theory for surface roughness of optical fiber sensor is one to one correspondence between the reflected light intensity based on the surface roughness of the object and the measurement value of previously known for surface roughness. The reflected light intensity was determined using the distance to the surface from the sensor probe and the limit reflection angle based on the surface roughness. Therefore, in this study, the sensor probe was produced for determining the value of surface roughness only using the limit reflection angle based on the surface roughness with the fixed distance from the surface. A prototype measurement system was composed of a transmitting part, a receiving part and a signal processing circuit. The materials of standard measurement which was used in this experiment were SM45C, STS303 and Al60. According to the results of this study, approximation surface roughness formulas which was deduced from the correlation of between the standard surface roughness and the sensing output were verified that they were effect against the surface roughness measurement value of the option sample. And handy optical fiber surface roughness measurement device which was produced by an order was verified that it was effect for measuring of the precision surface roughness. 본 연구는 광섬유센서를 이용하여 표면조도의 간이 비접촉 측정기를 개발하 는데 목적이 있다. 광섬유 센서의 장점은 우수한 고속 응답성, 자기의 무영향, 제작의 편이성 이다. 광섬유센서 표면조도 측정 원리는 측정물의 표면조도에 따라 반사되는 광의 세기와 기지의 표면조도 값을 일대일 대응시키는 것이다. 반사광의 세기는 센 서 프로브로부터 표면까지의 거리와 표면조도에 따른 반사한계각에 따라 결정 되는데 본 연구에서는 표면까지의 거리를 일정하게 하여 표면조도에 따른 반 사한계각만을 가지고 표면조도가 결정되도록 측정 프로브를 제작하였다. 측정 시스템은 발광부, 수광부과 신호처리부로 구성되었다. 이 실험에서 사 용된 표준 측정 재료는 SM45C, STS303과 Al60이었다. 연구결과 첫째, 재료에 따른 표면조도와 센서출력의 상관관계로부터 근사표 면조도식을 도출하고 임의 가공된 시료의 표면조도 측정을 통해 근사표면조도 식이 유효함을 입증하였다. 둘째, 실제 제작한 간이 광섬유센서 표면조도 측정 기가 유용함을 입증하였다.

연마 과정에 따른 열중합 의치상 레진의 표면 거칠기 평가

황성식,임용운,김시철,한민수 대한치과기공학회 2015 대한치과기공학회지 Vol.37 No.4

Purpose: The objective of this study was to compare the surface roughness according to polishing process in conventional laboratory techniques used for polishing three different acrylic denture base resins. Materials and methods: Specimen preparation and surface polishing procedures were conducted to manufacturer’s recommendation with three heat-polymerized denture base resins. Surface roughness and gloss were measured by a contact type tester and a LED gloss checker using thickness 2 mm and diameter 10 mm. There were five specimens for each acrylic resin material and polishing procedures. Mean average surface roughness (Ra) values of each specimen group were analyzed using a one-way ANOVA analysis of variance and Scheffe’s post hoc test. Surfaces after surface roughness and gloss testing according to each polishing process were evaluated under a stereoscopic microscope. Results: The highest mean average surface roughness was measured (Ra=2.43± 0.47) for surfaces finished with a denture tungsten carbide bur in Triplex. The lowest surface roughness values (Ra=0.11 ±0.07) were determined in Vertex polished with a lathe. In addition, all materials revealed that surface roughness determined highly in HP1 and HP2 than other procedures. All correlation between surface roughness and gloss showed highly with three heat-polymerized resins. Specially, topmost correlation revealed than other material in Triplex. Significant differences in mean average surface roughness were found between polishing process used high speed lathe and low speed hand-piece. Conclusions: Laboratory polishing used to high speed was found to produce the smoothest surface of heat-polymerized denture base acrylic resin. Therefore, we recommended that high polishing process need to get smooth surface.

Parameterization of Rain Induced Surface Roughness and Its Validation Study Using a Third Generation Wave Model

R. Rajesh Kumar,B. Prasad Kumar,D. Bala Subrahamanyam 한국해양과학기술원 2009 Ocean science journal Vol.44 No.3

The effect of raindrops striking water surface and their role in modifying the prevailing sea-surface roughness is investigated. The work presents a new theoretical formulation developed to study rain-induced stress on sea-surface based on dimensional analysis. Rain parameters include drop size, rain intensity and rain duration. The influences of these rain parameters on young and mature waves were studied separately under varying wind speeds, rain intensity and rain duration. Contrary to popular belief that rain only attenuates surface waves, this study also points out rain duration under certain condition can contribute to wave growth at high wind speeds. Strong winds in conjunction with high rain intensity enhance the horizontal stress component on the sea-surface, leading to wave growth. Previous studies based on laboratory experiments and dimensional analysis do not account for rain duration when attempting to parameterize sea-surface roughness. This study signifies the importance of rain duration as an important parameter modifying sea-surface roughness. Qualitative as well quantitative support for the developed formulation is established through critical validation with reports of several researchers and satellite measurements for an extreme cyclonic event in the Indian Ocean. Based on skill assessment, it is suggested that the present formulation is superior to prior studies. Numerical experiments and validation performed by incorporating in state-of-art WAM wave model show the importance of treating rain-induced surface roughness as an essential pre-requisite for ocean wave modeling studies. The effect of raindrops striking water surface and their role in modifying the prevailing sea-surface roughness is investigated. The work presents a new theoretical formulation developed to study rain-induced stress on sea-surface based on dimensional analysis. Rain parameters include drop size, rain intensity and rain duration. The influences of these rain parameters on young and mature waves were studied separately under varying wind speeds, rain intensity and rain duration. Contrary to popular belief that rain only attenuates surface waves, this study also points out rain duration under certain condition can contribute to wave growth at high wind speeds. Strong winds in conjunction with high rain intensity enhance the horizontal stress component on the sea-surface, leading to wave growth. Previous studies based on laboratory experiments and dimensional analysis do not account for rain duration when attempting to parameterize sea-surface roughness. This study signifies the importance of rain duration as an important parameter modifying sea-surface roughness. Qualitative as well quantitative support for the developed formulation is established through critical validation with reports of several researchers and satellite measurements for an extreme cyclonic event in the Indian Ocean. Based on skill assessment, it is suggested that the present formulation is superior to prior studies. Numerical experiments and validation performed by incorporating in state-of-art WAM wave model show the importance of treating rain-induced surface roughness as an essential pre-requisite for ocean wave modeling studies.

타이타늄의 표면거칠기가 도재의 결합강도에 미치는 영향

김상훈,방몽숙,양홍서,박상원,박하옥,임현필,오계정,Kim, Sang-Hun,Vang, Mong-Sook,Yang, Hong-So,Park, Sang-Won,Park, Ha-Ok,Lim, Hyun-Pil,Oh, Gye-Jeong 대한치과보철학회 2007 대한치과보철학회지 Vol.45 No.2

Statement of problem: Titanium has many advantages of high biocompatibility, physical properties, low-weight, low price and radiolucency, but it is incompatible with conventional dental porcelain due to titanium's oxidative nature. Many previous studies have shown that they used the method of sandblast for surface treatment prior to porcelain application, the researches are processing about the method of acid etching or surface coating. Purpose: The purpose of this research is to study the effect on bond strength of surface roughness between titanium and porcelain with the same surface topography. Material and method: In this study, we evaluated the bond strength by using 3-point bending test based on ISO 9693 after classified 8 groups - group P : polished with #1200 grit SiC paper, group S10 : $1.0{\mu}m$ surface roughness with sandblasting, group S15 : $1.5{\mu}m$ surface roughness with sandblasting, group S20 : $2.0{\mu}m$ surface roughness with sandblasting, group S25 : $2.5{\mu}m$ surface roughness with sandblasting, group S30 : $3.0{\mu}m$ surface roughness with sandblasting, group S35 : $3.5{\mu}m$ surface roughness with sandblasting, group E : $1.0{\mu}m$ surface roughness with HCl etching. Results: Within the confines of our research, the following results can be deduced. 1. In the results of 3-point bending test, the bond strength of sandblasting group showed significant differences from one of polishing group, acid etching group(P<.05). 2. The bond strength of sandblasting groups did not show significant differences. 3. After surface treatments, the group treated with sandblasting showed irregular aspect formed many undercuts, in the SEM photographs. The bond strength of sandblasting group was higher than 25 MPa, the requirement of ISO 9693. Conclusion: In above results, bond strength of titanium and low-fusing porcelain is influenced more to surface aspect than surface roughness. And titanium has clinically acceptable bond strength below surface roughness of $3.5{\mu}m$.

Study on the Pool Boiling Heat Transfer Characteristics of Aluminum Plate with Directional Surface Roughness

김준(Jun Kim),홍동인(Dong In Hong),김석민(Seok Min Kim) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.5

Rolled and extruded aluminum (Al) products have been widely used in heat exchanging systems using the boiling heat transfer (BHT) mechanism. The BHT coefficient can be increased on a rough surface due to the activation of the nucleation sites. In this study, the BHT characteristic of an Al plate with directional surface roughness (bare Al plate), which was generated in rolling or extrusion process, was measured and compared with the polished Al plates with non-directional surface roughness. The BHT coefficient of polished Al plate was increased with increasing surface roughness, saturated at ~300 nm (Sa). Although the surface roughness of the bare Al plate was 380-430 nm (Sa), the BHT coefficient of bare Al plates were lower than the polished Al plates with similar surface roughness. To examine the lower BHT coefficient of bare Al plate, the directional surface roughness was characterized by vertical and horizontal surface roughness values to the production direction, and we experimentally concluded the lower surface roughness value (horizontal surface roughness) was the dominant factor for the BHT characteristic of a rolled or extruded Al plate with directional surface roughness.

수면 거칠기에 따른 수면 경로의 시변 통신채널 통계적 특성 분석

황인성,최강훈,최지웅 한국음향학회 2023 韓國音響學會誌 Vol.42 No.6

해수면 거칠기에 의해 해수면 산란이 발생하면 통신신호의 주파수 확산과 통신채널 시변동성을 야기하여통신성능을 악화시킨다. 수면 거칠기에 따른 통신채널의 시변동성 차이를 비교하기 위하여 한양대학교 해양음향공학연구실 수조에서 실험을 수행하였다. 수조에서 인위적인 수면 거칠기를 생성하고 대역폭에 따른 차이를 비교하기 위하여 3가지 대역폭을 갖는 통신신호를 사용하였다. 측정된 수면 거칠기는 레일리 파라미터로 변환하여 거칠기에 대한파라미터로써 사용하였으며, 수면 경로의 시변 채널 특성은 도플러 확산과 상관시간을 이용하여 통계적 분석을 수행하였다. 수면 경로의 도플러 확산은 통신신호의 반송 주파수와 대역폭의 영향을 보정한 가중 유효 도플러 확산(Weighted Root Mean Square Doppler spread, )을 사용하였다. 수면 경로의 상관시간과 직접 경로와 수면 경로의 에너지 비율을 이용하여 전체 채널의 상관관계를 모의하고 측정된 전체 채널의 상관시간과 비교하였다. 본 연구에서는 해수면 거칠기에 따른 해수면 경로의 시변 채널특성을 이용하여 임의의 해양환경에서 효율적인 통신신호 설계를위한 방법을 제안한다. Scattering by Sea surface roughness occurs due to sea level roughness, communication performance deteriorates by causing frequency spread in communication signals and time variation in communication channels. In order to compare the difference in time variation of underwater acoustic communication channel according to the surface roughness, an experiment was performed in a tank owned by Hanyang University Ocean Acoustics Lab. Artificial surface roughness was created in the tank and communication signals with three bandwidths were used (8 kHz, 16 kHz, 32 kHz). The measured surface roughness was converted into a Rayleigh parameter and used as a roughness parameter, and statistical analysis was performed on the time-varying channel characteristics of the surface path using Doppler spread and correlation time. For the Doppler spread of the surface path, the Weighted Root Mean Square Doppler spread ( ) that corrected the effect of the carrier frequency and bandwidth of the communication signal was used. Using the correlation time of the surface path and the energy ratio of the direct path and the surface path, the correlation of total channels was simulated and compared with the measured correlation time of total channels. In this study, we propose a method for efficient communication signal design in an arbitrary marine environment by using the time-varying characteristics of the sea surface path according to the sea surface roughness.

Investigation of Floor Surface Finishes for Optimal Slip Resistance Performance

Kim, In-Ju Occupational Safety and Health Research Institute 2018 Safety and health at work Vol.9 No.1

Background: Increasing the slip resistance of floor surfaces would be desirable, but there is a lack of evidence on whether traction properties are linearly correlated with the topographic features of the floor surfaces or what scales of surface roughness are required to effectively control the slipperiness of floors. Objective: This study expands on earlier findings on the effects of floor surface finishes against slip resistance performance and determines the operative ranges of floor surface roughness for optimal slip resistance controls under different risk levels of walking environments. Methods: Dynamic friction tests were conducted among three shoes and nine floor specimens under wet and oily environments and compared with a soapy environment. Results: The test results showed the significant effects of floor surface roughness on slip resistance performance against all the lubricated environments. Compared with the floor-type effect, the shoe-type effect on slip resistance performance was insignificant against the highly polluted environments. The study outcomes also indicated that the oily environment required rougher surface finishes than the wet and soapy ones in their lower boundary ranges of floor surface roughness. Conclusion: The results of this study with previous findings confirm that floor surface finishes require different levels of surface coarseness for different types of environmental conditions to effectively manage slippery walking environments. Collected data on operative ranges of floor surface roughness seem to be a valuable tool to develop practical design information and standards for floor surface finishes to efficiently prevent pedestrian fall incidents.

침질침탄시 화합물층의 성장에 따른 표면조도 변화에 관한 연구

송경석 ( Song Gyeong Seog ),문경일 ( Mun Gyeong Il ),김성완 ( Kim Seong Wan ) 한국열처리공학회 2003 熱處理工學會誌 Vol.16 No.5

N/A In this study, to find out the reason of deterioration in surface roughness of steel and cast iron after Tufftride, it has been investigated on the relation between the surface roughness and various factors such as the evolution of compound layer, surface morphology, and surface hardness, and change of pore ratio in the com pound layer during Tufftride at 580 C. It is found that the surface roughness was increased with the evolution of compound layer during Tufftride of steel and cast iron. The change of surface roughness after Tufftride was reduced with decreasing the content of carbon and cementite (Fe3C) in the materials. In the cast irons, the various shaped graphites that was exposed to the surface should induce the discontinuous growth of the compound layer, and this resulted in the incoherent interfaces between matrix and wmpound layer and the deterioration of surface roughness. In the steels, the existence of cementites in the matrix resulted in the inwherent interfaces between matrix and compound layer. It is considered that during Tufftride the surface roughness must be mainly influenced by the formation of the incoherent interface between compound layer and matrix that is affected by some factors such as the microstructure, the composition, and the hardness of the matrix.

Investigation of Floor Surface Finishes for Optimal Slip Resistance Performance

김인주 한국산업안전보건공단 산업안전보건연구원 2018 Safety and health at work Vol.9 No.1

Background: Increasing the slip resistance of floor surfaces would be desirable, but there is a lack of evidence on whether traction properties are linearly correlated with the topographic features of the floor surfaces or what scales of surface roughness are required to effectively control the slipperiness of floors. Objective: This study expands on earlier findings on the effects of floor surface finishes against slip resistance performance and determines the operative ranges of floor surface roughness for optimal slip resistance controls under different risk levels of walking environments. Methods: Dynamic friction tests were conducted among three shoes and nine floor specimens under wet and oily environments and compared with a soapy environment. Results: The test results showed the significant effects of floor surface roughness on slip resistance performance against all the lubricated environments. Compared with the floor-type effect, the shoe-type effect on slip resistance performance was insignificant against the highly polluted environments. The study outcomes also indicated that the oily environment required rougher surface finishes than the wet and soapy ones in their lower boundary ranges of floor surface roughness. Conclusion: The results of this study with previous findings confirm that floor surface finishes require different levels of surface coarseness for different types of environmental conditions to effectively manage slippery walking environments. Collected data on operative ranges of floor surface roughness seem to be a valuable tool to develop practical design information and standards for floor surface finishes to efficiently prevent pedestrian fall incidents.

고온 프레스에 의해 제조된 Cu/Al 클래드재의 접합계면 특성에 미치는 표면조도의 영향

이상목 ( Sang Mok Lee ),이종섭 ( Jong Sup Lee ),김용배 ( Yong Bae Kim ),이근안 ( Geun An Lee ),이상필 ( Sang Pill Lee ),손인수 ( In Soo Son ),이진경 ( Jin Kyung Lee ),배동수 ( Dong Su Bae ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.9

This study investigates the effect of surface roughness on bonding interface properties, such as micro hardness, diffusion layer thickness, intermediate phases, bonding strength, etc., in hot pressed Cu/Al clad material for electric conductors. Different surface roughnesses at the bonding surfaces of oxygen free copper (OFC) and Al 1050 matrix materials were obtained by emery paper grinding and buff polishing. The Cu/Al clad materials were prepared by hot-pressing under 200 MPa at 450 ℃ for 15 min. Microstructures of the Cu/Al interfaces were observed using an optical micrograph (OM), a Field Emission Gun-Scanning Electron Microscope (FEG-SEM) and an Energy Dispersed X-ray Analyser (EDX) in order to investigate the effects of surface roughness on the bond properties of the Cu/Al clad materials. A shear fracture test was performed to evaluate the bonding strengths of the Cu/Al clad materials. A Micro Knoop hardness test was used to measure the micro hardness in the diffusion layer at the Cu/Al interface. The 3-layer diffusion layer was observed at the Cu/Al interfaces. The thickness of the diffusion layer decreased and an additional intermediate phase ξ2 was formed with the increase of surface roughness. The Micro Knoop hardness increased rapidly mainly due to the formation of η2 and ξ2 phases and then decreased gradually with the increase of surface roughness. The bonding strength of the Cu/Al interface increased rapidly in the initial stage and increased slowly up to the peak value and then decreased slightly with the increase of surface roughness. The shear fracture surfaces of the Cu/Al bonding interface were flat and had an even shape in the sample with a low surface roughness, but had a rough and uneven shape in high surface roughness conditions.