• Title/Summary/Keyword: Roughness Index

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System Identification of In-situ Vehicle Output Torque Measurement System (차량 출력 토크 측정 시스템의 시스템 식별)

  • Kim, Gi-Woo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.2
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    • pp.85-89
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    • 2012
  • This paper presents a study on the system identification of the in-situ output shaft torque measurement system using a non-contacting magneto-elastic torque transducer installed in a vehicle drivline. The frequency response (transfer) function (FRF) analysis is conducted to interpret the dynamic interaction between the output shaft torque and road side excitation due to the road roughness. In order to identify the frequency response function of vehicle driveline system, two power spectral density (PSD) functions of two random signals: the road roughness profile synthesized from the road roughness index equation and the stationary noise torque extracted from the original torque signal, are first estimated. System identification results show that the output torque signal can be affected by the dynamic characteristics of vehicle driveline systems, as well as the road roughness.

Bearing capacity of foundation on rock mass depending on footing shape and interface roughness

  • Alencar, Ana S.;Galindo, Ruben A.;Melentijevic, Svetlana
    • Geomechanics and Engineering
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    • v.18 no.4
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    • pp.391-406
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    • 2019
  • The aim of this paper was to study the influence of the footing shape and the effect of the roughness of the foundation base on the bearing capacity of shallow foundations on rock masses. For this purpose the finite difference method was used to analyze the bearing capacity of various types and states of rock masses under the assumption of Hoek-Brown failure criterion, for both plane strain and axisymmetric model, and considering smooth and rough interface. The results were analyzed based on a sensitivity study of four varying parameters: foundation width, rock material constant (mo), uniaxial compressive strength and geological strength index. Knowing how each parameter influences the bearing capacity depending on the footing shape (circular vs strip footing) and the footing base interface roughness (smooth vs rough), two correlation factors were developed to estimate the percentage increase of the ultimate bearing capacity as a function of the footing shape and the roughness of the footing base interface.

Research on Die Machining using 3D Printing and CAM System (3D 프린팅시스템과 CAM시스템을 활용한 금형가공에 관한 연구)

  • Han, Kyu-Taek
    • Journal of Power System Engineering
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    • v.18 no.6
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    • pp.91-98
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    • 2014
  • The purpose of this research is to investigate optimum machining conditions to improve the quality of die using the CAD/CAM system(Power Shape/Power Mill) and 3D printing. Surface roughness is widely used as an index for processing degree of accuracy. The Power Shape was used to model the shape of product. And the model shape is confirmed by 3D printing system(BFB-3000). Also, tool path and NC-codes were generated using Power Mill. Finally, the product was cut using CNC machine(NBS-2025). The cutting time and surface roughness were measured by measuring instrument. And then this process was repeated by changing the conditions to find optimal machining conditions. The surface roughness behavior with regard to specific factors were analyzed. Through this study, the optimal machining condition can be obtained.

Study on the characteristics of nucleate boiling heat transfer with changing of surface roughness (표면거칠기의 변화에 따른 핵비등열전달의 특성에 관한 연구)

  • 김춘식;정대인;배종욱
    • Journal of Advanced Marine Engineering and Technology
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    • v.7 no.1
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    • pp.64-78
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    • 1983
  • In nucleate boiling, bubbles are created by the expansion of entrapped gas or vapor at small cavities in the surface of heat transfer. Namely, surface roughness is the important factor of heat transfer. This paper deals with the characteristics of boiling curve according to surface roughness. Freon-113 is used as the experimental fluid. The results are as follows; 1. In the case of the same as "q=C$\Delta$T$^{n}$ ", the lower numberical index "n", the larger heat transfer coefficient and the lower wall superheat "$\Delta$T" is obtained for the rougher surface. 2. In the working of every kind of heat transfer sruface with boiling, improvement of capabilities of heat transfer can be devised by adding suitable roughness on the heat transfer surface. 3. When the metal nets of moderate mesh number are established, the capabilities of heat transfer can be improved in evaporation of liquid in vessels. But in the case that the sucession of bubbles in checked by using the nets which are too tight, the generation of bubbles union decreases critical heat flux. decreases critical heat flux.

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Improvement of Brightness for AlGaInP High-brightness LEDs with Nano-scale Roughness on Top-GaP Surface (Top-GaP 상부에 나노 크기의 Roughness 처리에 의한 AlGaInP 고휘도 LED의 휘도 향상)

  • So, Soon-Jin;Ha, Hun-Sung;Park, Choon-Bae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.1
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    • pp.68-72
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    • 2008
  • AlGaInP high-brightness LEDs(HB-LEDs) have gained importance a variety of application operating in the red, orange, yellow and yellow-green wavelength. The light generated from inside LED chips should be emitted to the air through the surfaces of the chips. However, because of the differences between the semiconductor and air or epoxy's refractive index, some of the light was blocked so that caused lowering external quantum efficiency. In this study, nano-scale roughness on the top-GaP layer of AlGaInP epitaxial wafer was fabricated to improve' the brightness of AlGaInP LEDs. Nano-scale roughness was made by ICP dry etcher. Our AlGaInP LEDs with nano-scale roughness has higher brightness (about 28.5 %) than standard AlGaInP LEDs.

ASSESSMENT OF PUBLIC PERCEIVED ROADWAY SMOOTHNESS

  • Jamie Miller;Don Chen;Neil Mastin
    • International conference on construction engineering and project management
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    • 2013.01a
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    • pp.507-508
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    • 2013
  • International Roughness Index (IRI) has been widely used by state DOTs to quantify pavement smoothness. When pavement condition falls below certain IRI thresholds, corresponding pavement maintenance treatments should be considered for application. Selection of appropriate IRI thresholds is essential to tactical allocation of limited resources to improve the conditions of states' roadway systems. This selection process is often challenging, however, because IRI thresholds are largely determined by Perceived Ride Quality (PRQ), and PRQ differs in each state. In this paper, a framework is proposed to address this problem. Passenger raters will be randomly selected from predetermined geographic locations, and their PRQ ratings collected. Taking this perceived ride data, along with other data collected, a statistical analysis will be conducted to establish the relationship between measured IRI values and PRQ. Appropriate IRI thresholds will then be determined. Once this framework is implemented, state DOTs could make informative maintenance decisions, which are expected to greatly enhance the public perception of pavement conditions in today's challenging economy.

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Deformation Behaviors and Acoustic Emissions of Rock Joints in Direct Shear (직접전단시험을 통한 암석 절리의 변형거동 및 미소파괴음 발생에 관한 연구)

  • 김태혁;이상돈;이정인
    • Tunnel and Underground Space
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    • v.4 no.3
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    • pp.274-286
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    • 1994
  • Direct shear tests were on ducted in a laboratory setting in order to investigate the shear strength and deformation behavior of rock joints. Also, the characteristics of acoustic emissions (AE) during shearing of rock joints were studied. The artificial rock joints were created by splitting the intact blocks of Hwangdeung granites and Iksan marbles. Joint roughness profiles were measured by a profile gage and then digitized by Image analyzer. Roughness profile indices(Rp) of the joints were calculated with these digitized data. Peak shear strength, residual shear strength, shear stiffness and maximum acoustic emission(AE) rate were investigated with joint roughness. The peak shear strenght, the residual shear strength and the shear stiffness were increased as roughness popfile index or normal stress increased in the shear tests of granites. In the tests of marble samples, the shear deformation characteristics were not directly affected by joint roughness. As the result of two directional shear tests, the shear characteristics were varied with shear direction. AE count rates were measured during the shear deformation and the AE signals in several stages of the deformation were analyzed in a frequency domain. The AE rate peaks coincided with the stress drops during the shear deformation of joint. The dominant frequencies of the AE signals were in the vicinity of 100 kHz fo rgranite sample and 900 kHz for marble samples. The distribution of amplitude was dispersed with increasing normal stress.

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Uncertainty Quantification Index of SWMM Model Parameters (SWMM 모형 매개변수의 불확실성 정량화 지수 산정)

  • Chung, Gunhui;Sim, Kyu Bum;Kim, Eung Seok
    • Journal of Korea Water Resources Association
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    • v.48 no.2
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    • pp.105-114
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    • 2015
  • In the case of rapidly developed urban and industrial complex, the most area becomes impervious, which causes the increasing runoff and high probability of flooding. SWMM model has been widely used to calculate stormwater runoff in urban areas, however, the model is limited to interpreting the actual natural phenomenon. It has the uncertainty in the model structure, so it is difficult to calculate the accurate runoff from the urban basin. In this study, the model parameters were investigated and uncertainty was quantified using Uncertainty Quantification Index (UQI). As a result, pipe roughness coefficient has the largest total uncertainty and largest effect on the total runoff. Therefore, when the stormwater pipe network is designed, pipe roughness coefficient has to be calibrated accurately. The quantified uncertainty should be considered in the runoff calculation. It is recommended to understand the characteristics of each parameter for the prevention and mitigation of urban flood.