고속도로 줄눈 콘크리트 포장의 평탄성 모델 개발

박영훈,전범준,김영규,이승우 한국도로학회 2010 한국도로학회논문집 Vol.12 No.2

Roughness is the most important factor to maintain the road performance, and affects greatly on the design life in Jointed Plain Concrete pavements. Also, the factors the evaluate pavement's commonality is the three method such as functionality, safety and structural performance. In evaluating function of road, representative factors is the roughness, which has been used to determine maintenance time as key standard. As research for roughness is absence in pavement design. Applied roughness-model had a low-reliability in Korea. Therefore, it is needed to develop reliable model in road roughness. In this research, uniform specific is applied to distribute them after selecting the concrete pavements. Concrete pavement is divided by sections of 238. Total length of this sections has 281km and account for 16% of total road length in korean concrete pavements for selected sections. Considering the korean roughness-model, the evaluation of roughness is performed for the freezing index, average annual rainfall, condition for the base, the amount of traffic as well as spalling(%), cracking(%), age(year) at the selected section at the selected section. Also, additional sections is selected to evaluate various age which affects on the roughness. As a result of the analysis, it showed that spalling(%), cracking(%), age(year), and the condition of the base affected road roughness. When the correlation with the road roughness was analyzed, the reliable model for road roughness was proposed, and the ratio that can explain road roughness was R2-68.8% and P value-0 which is statistically meaningful. 평탄성은 도로 공용성을 확보하기 위한 중요한 인자이며, 줄눈콘크리트 포장에서 수명에 큰 영향을 미친다. 포장의 공용성을 평가하는 요소로는 크게 기능성 평가, 안정성 평가 및 구조적 성능 평가가 있다. 기능성 평가 가운데 가장 대표적인 평탄성은 유지보수를 위한 중요한 기준으로 이용되고 있으나 체계적인 연구를 통해 포장 설계시에 적용하기 위한 연구는 미흡한 실정이다. 따라서 신뢰성 있는 평탄성 모델의 개발이 필요하다. 본 연구에서는 국내 콘크리트포장의 노선별 총 연장 280.93km를 일정기준으로 나누어 238개의 섹션으로 선별하였다. 또한, 현재 국내 평탄성 모델에서 고려하고 있는 영향인자인 스폴링, 균열, 재령뿐만 아니라 동결지수, 연평균강수량, 기층조건, 교통량 등에 대한 검토가 이루어졌으며, 재령의 다양화를 위하여 추가적인 노선을 선별하여 평탄성에 영향을 미치는 인자들에 대한 분석이 이루어졌다. 분석결과는 스폴링(%), 균열(%), 재령(년), 기층이 평탄성에 영향을 미치는 것으로 나타났다. 이를 통해 평탄성과의 상관관계를 분석 한 결과 신뢰성 있는 평탄성 모델이 도출되었으며, 평탄성를 설명할 수 있는 비율은 68.8%로 나타나 통계적으로 유의한 것으로 판단된다.본 연구에서는 소입경 골재노출콘크리트포장의 시험시공을 실시하여 초기 공용성을 평가하였으며, 이를 통하여 적정 강도, 저소음 및 적정 미끄럼저항을 확보함을 확인하였다.

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.

Comparison of optimized roughness parameters of some artificially roughened solar air heaters

Cihan Yıldırım,Ibrahim Aydoğdu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10

In this study, theoretical investigation derived from experimental correlations and the artificial bee colony optimization method are used to determine the optimum geometrical parameters which maximize the termohydraulic efficiency of some artificially roughened solar air heaters. Nine different roughness types are considered, i.e., transverse wedge-shaped rib roughness, protrusion roughness, multiple v-ribs roughness, rib-grooved roughness, metal grit ribs roughness, compound turbulators roughness, v-shaped rib roughness, arc-shaped wire roughness, and discrete v-down ribs roughness. The effects of the artificial roughness element parameters on the best thermal performance and the thermohydraulic performance are compared. Optimum results are obtained with multiple v-ribs roughness for the low mass flow rate (MFR = 0.1 kg/s) and with protrusion roughness for the high mass flow rate (MFR = 0.5 kg/s). Optimum roughness parameters and corresponding thermal and thermohydraulic efficiencies are tabulated for each solar collector type. As expected, increased roughness geometry leads to higher pressure loss and reduces thermohydraulic efficiency.

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 $3.5{\mu}m$.

암석 절리면 거칠기 과소평가의 개선을 위한 새로운 측정방법의 적용

홍은수(Hong Eun-Soo),이주공(Lee Joo-Gong),이종섭(Lee Jong-Sub),이인모(Lee In-Mo) 대한토목학회 2006 대한토목학회논문집 C Vol.26 No.2

Many methods have been tried to more correctly measure rock joint roughness. However, true roughness may be distorted and underestimated due to the sampling interval and measurement method. Thus, currently used measurement methods produce a dead zone and distort roughness profiles. The purpose of this study is to suggest new roughness measurement method by a camera-type 3D scanner as an alternative of currently used methods. First, the underestimation of artificial roughness is analyzed by using the current measurement method such as laser profilometry. Second, we replicate eight specimens from two rock joint surfaces, and digitize by a 3D scanner. Then, the roughness coefficient values obtained from eight numbers of 3D surface data and from three hundred twenty numbers of 20 profiles data are analyzed by using current and new measurement methods. The artificial simulation confirms that the sampling interval is one of main factors for the distortion of roughness and shows that inclination of waviness may not be considered any current methods. The experimental results show that the camera-type 3D scanner produces 10% larger roughness values than current methods. As the proposed new method is a fast, high precision and more accurate method for the roughness measurement, it should be a promising technique in this area. 암석 절리면의 거칠기를 측정하는 수많은 방법이 제시되었지만 측정간격과 측정방법 때문에 항상 원래의 거칠기를 완벽하게 나타낼 수 없다는 한계가 있었다. 이와 같은 이유로, 현재 사용되고 있는 측정방법에서는 사각지대가 발생하며 거칠기를 왜곡시킨다. 이 연구에서는 현재 널리 사용되고 있는 방식의 대안으로써 카메라 방식의 3D 스캐너를 이용한 새로운 거칠기 측정법을 제시하려고 하였다. 먼저 인공 거칠기의 과소평가 문제를 레이저 프로파일러와 같은 기존의 방법에 의해 해석하였다. 또한, 8개의 시편을 2종의 암석 절리면에서 복제하고 3D 스캐너로 측정하였고, 얻어진 8개의 3D 표면 자료와 320개의 2D 프로파일 자료에 대한 거칠기 계수 값을 기존의 측정방법과 새로운 측정방법을 사용하여 분석 하였다. 해석결과 측정간격이 거칠기 왜곡현상의 원인이 될 수 있다는 것을 확인시켜 주었으며 만곡의 기울기는 기존의 방법으로는 고려할 수 없음을 알 수 있었다. 카메라 방식의 3D 스캐너를 측정방법으로 사용하면 기존의 방법에서 보다 거칠기가 10% 정도 더 크게 평가된 값을 얻을 수 있으며, 실제 프로파일의 형태를 좀 더 명확히 파악할 수 있는 것으로 나타났다. 따라서 새로운 방법이 빠르고 정밀하면서도 정확한 거칠기 측정방법이 될 수 있음을 확인할 수 있었다.

거친 표면의 돌기 방향성에 따른 EHL 해석

김태완(Tae-Wan Kim),조용주(Yong-Joo Cho) 한국트라이볼로지학회 2009 한국윤활학회지(윤활학회지) Vol.25 No.5

This paper presents EHL analysis for rough surfaces with directional roughness. Three different types of surfaces with pure longitudinal roughness, pure transversal roughness and isotropic roughness are generated. For the surfaces with longitudinal and transversal roughness, two cases are analyzed; one is a case of asperity peak on a spherical contact center, the other one is of valley on a spherical contact center. As a results, the surface with pure transversal roughness gives higher pressure and smaller minimum film thickness than the surface with pure longitudinal roughness, and the surface with isotropic roughness has similar EHL behavior with the surface with pure transversal roughness.

높은 표면 거칠기가 적층 제조 압축기 블레이드의 공력 성능에 미치는 영향

고영언,임석현,홍두남,송성진 한국유체기계학회 2024 한국유체기계학회 논문집 Vol.27 No.1

Additive manufacturing frequently yields components with relatively high surface roughness when compared to their subtractive manufacturing counterparts. This elevated surface roughness can have a profound impact on compressor performance by perturbing the boundary layer. Consequently, a comprehensive investigation into the influence of surface roughness on the aerodynamic performance of additively manufactured compressor blades becomes imperative. In this study, a linear cascade experiment is conducted to examine the effects of elevated surface roughness within a fully rough regime on compressor blades produced through additive manufacturing. Sandpaper is employed as a surrogate for surface roughness. Deviations and total pressure loss are assessed at the midspan using a 5-hole probe. Furthermore, numerical analysis is conducted using two models to simulate the ramifications of surface roughness via the commercial software, ANSYS CFX. In the linear cascade experiments, surface roughness on compressor blades results in a 27.9% increase in mass-averaged deviation at midspan and a 98.2% increase in mass-averaged total pressure loss at midspan. Numerical analysis results exhibit reasonable agreement regarding the increase in pressure loss coefficient due to surface roughness, albeit with a larger deviation than the experimental result. The results from both the experiment and numerical analysis conclusively establish that high surface roughness on additively manufactured compressor blades substantially elevates deviations and pressure loss.

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.

자동주행 조도 측정 장치를 활용한 레일 표면 조도의 유지보수 적용 가능성 고찰

이호현,최영태,여인호 한국철도학회 2023 한국철도학회논문집 Vol.26 No.6

Roughness of rail surface can cause various problems such as noise, vibration and impact. For this reason, many researchers have tried to measure and analyze roughness. In Korea, some research on roughness have been performed, but the topic was limited only to acoustic roughness. In this study, rail surface roughness of high speed rails and subway in Korea was measured and analyzed using an autonomous rail roughness checker. From the measured roughness some characteristics of surface defects such as corrugation were specified and can be utilized to make rail maintenance decisions. Moreover, if more advanced analysis is performed via additional research, roughness can be a more powerful tool for rail maintenance.

Roughness measures of locally finite covering rough sets

Elsevier 2019 International journal of approximate reasoning Vol.105 No.-

<P><B>Abstract</B></P> <P>The present paper defines four new kinds of measures of roughness of covering rough sets induced by <I>locally finite covering approximation</I> (<I>LFC</I>-, for brevity) spaces which are generalizations of finite covering approximation spaces. More precisely, consider an <I>LFC</I>-space ( U , C ) and a nonempty set X ( ⊆ U ) . Using a reduction of a given <I>LFC</I>-space ( U , C ) , the present paper firstly establishes two types of rough membership functions of the set <I>X</I> with respect to <I>LFC</I>-spaces ( U , C ) , where each of the cardinalities of the sets <I>U</I>, <B>C</B>, and <I>X</I> need not be finite. Next, it also develops another two kinds of notions of roughness of digital topological rough sets. Indeed, these notions are based on the concepts of accuracy of rough sets derived from <I>LFC</I>-spaces. Furthermore, we use them to the estimation of roughness of a covering rough set of X ( ⊆ U ) . Besides, we estimate roughness of a digital topological rough set, such as measures of roughness of the Khalimsky and Marcus–Wyse topological rough sets. Moreover, we compare between the measures of the Khalimsky topological and the Marcus–Wyse topological roughness.</P>