Identification of V-belt power losses with temperature measurement

László Kátai,István Szabó 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8

The efficiency of V-belt drives is determined by several factors collectively: the slip occurring during drive transmission, the externalfriction occurring when the belt enters and exits the pulley as well as the hysteresis loss resulting from inner friction. An experimentalapparatus and calculation method was developed in order to determine the increase in temperature emerging from the contact of the beltand the pulley in idling mode. The tested V-belt piece was bent on a pulley performing alternating motion while the temperature of theV-belt was measured. During the testing the temperature generated in the V-belt was measured as a function of changes in three parameters(Pretension, diameter of pulley and bending frequency). On the one hand, the temperature generated in the V-belt can be estimatedwith the assistance of the function determined on the basis of the testing results. On the other hand the so-called damping factor characterizingthe contact with the pulley (The external friction when entering and exiting the groove) and the hysteresis loss (Inner friction) arealso determined. On the basis of the damping factor (x≈400 Ns/m2) of the V-belt involved in the experiments the other losses (Poth) occurringfrom the pulley-V-belt contact and internal friction may be estimated. With the help of the mathematical models defined for thepulley diameter and belt frequency, taking into consideration the minimization of heat generation, optimal parameters can be calculatedthat serve as beneficial references for designing and tuning V-belt drives.

모터 제어 정밀도 향상을 위한 정지 마찰력 보상

류정래(Jung Rae Ryoo),도태용(Tae-Yong Doh) 제어로봇시스템학회 2014 제어·로봇·시스템학회 논문지 Vol.20 No.2

DC motor is a representative electric motor commonly utilized in various motion control fields. However, DC motor-based motion control systems suffer from degradation of position precision due to nonlinear static friction. In order to enhance control precision, friction model-based compensators have been introduced in previous researches, where friction models are identified and counter inputs are added to control inputs for cancelling out the identified friction forces. In this paper, a static friction compensator is proposed without use of a friction model. The proposed compensation algorithm utilizes internal state manipulation to generate compensation pulses, and related parameters are easily tuned experimentally. The proposed friction compensator is applied to a DC motor-based motion control system, and results are presented in comparison with those without a friction compensator.

내경 플라즈마 용사법에 의한 과공정 Al-Si 합금의 실린더 블록 보어 개발을 위한 기초연구

김병희,이형근,김혜성,Kim, Byeong-Hui,Lee, Hyeong-Geun,Kim, Hye-Seong 한국재료학회 2001 한국재료학회지 Vol.11 No.11

The objective of this study is to investigate the characteristics - microstructure, hardness, adhesive strength and friction coefficient - of the coatings with aging - treatment after optimizing internal- plasma spraying parameters for Al-30wt%Si powder as a basic research to manufacture the cylinder block bore for Al engine composed of Al-30wt%Si alloy on Al alloy, The optimum internal-plasma spraying parameters of Al-30wt%Si alloy are summarized as follows: voltage: 37.5V, current: 160A, working distance: 25mm, gun traverse speed: 4.5mm/s, rotating speed: 518m/min. The primary Si particles grew aggressively with increasing heat-treating temperature. The hardness of the as-sprayed coating was about Hv=275 but this value was abruptly decreased with increasing heat-treating temperature. And average friction coefficient of the coating was below 0.08 after heat treatment for 48h at $175^{\circ}C$.

기일 전 증거개시(pre-trial discovery)로 인한 국제적 사법마찰의 해결에 관한 연구

김효정 ( Kim Hyo Jung ) 사법정책연구원 2022 연구보고서 Vol.2022 No.14

In principle countries in the civil law system such as Korea do not allow fishing expedition in the evidence-taking, whereas the United States widely permits the submission of materials for the purpose of fishing expedition through pre-trial discovery procedure. Korea made a particularized declaration pursuant to Article 23 of the “Convention on the Taking of Evidence Abroad in Civil or Commercial Matters (hereinafter “HCCH Evidence Convention”)” that it will not execute letters of request issued for the purpose of obtaining pre-trial discovery of documents under certain conditions at the time of accession. Therefore, the United States shall not request Korea to submit the documents for the purpose of pre-trial discovery within the scope that Korea has expressly excluded through the above declaration. Nevertheless, the U.S. courts are requesting the other Contracting States of the HCCH Evidence Convention that have made a Article 23 reservation, including Korea, to submit the documents in spite of going against the purpose of its declarations. Furthermore, even in cases to which the HCCH Evidence Convention applies, the U.S. courts issue pre-trial discovery orders based on the Federal Rules of Civil Procedure (hereinafter “FRCP”), thereby ensuing the unavoidable judicial friction. Against this backdrop, this study is aiming at solving two main problems. Firstly, it will establish the criteria regarding the execution of a request for pre-trial discovery of documents under the HCCH Evidence Convention, and secondly, it will The criteria for determining whether to execute the United States’ letter of request issued for the purpose of obtaining pre-trial discovery of documents under the HCCH Evidence Convention would be proposed as follows. First, since ‘evidence’ that is subject to the HCCH Evidence Convention is materials for proving the issues of litigation, if the documents listed in the letter of request are found to be irrelevant to the litigation issue, the execution shall be refused. Next, according to Korea’s qualified exclusion under Article 23 of the HCCH Evidence Convention, statements regarding the possession or custody of documents are included in the object of refusal to execute. Therefore, the execution of deposition regarding these statements can be refused. In addition, submission of documents not specified in the letter of request should be rejected. However even if a number of documents are described collectively, individual documents corresponding to each case are clearly described, the documents should be considered particularized and specified. On the other hand, refusing the execution of the letter of request based on Article 9 of the HCCH Evidence Convention by interpreting the pre-trial discovery procedure as incompatible with the procedures of domestic law should not be allowed as it may defeat the legislative intent of Article 23 of the HCCH Evidence Convention. Lastly, even if the scope of request is wide, unless it falls under the grounds for refusal of execution as stipulated in the HCCH Evidence Convention and it does not fall within the scope of Article 23 reservation as well, Korea should neither arbitrarily reduce the scope of request nor execute just a part of it. As for the countermeasures to the U.S. court’s pre-trial discovery order according to the FRCP, (ⅰ) enacting a blocking statute, (ⅱ) filing for a protective order predicated on the Korean court’s decision on the provisional disposition to enjoin the submission of materials, and (ⅲ) concluding a bilateral treaty with the United States have been reviewed. The U.S. court has maintained its position of not considering blocking statues such as France’s blocking statute or EU General Data Protection Regulations. In addition, parties or a third party who are required to submit materials under the pre-trial discovery order of a U.S. court will get stuck in a contradictory situation. This is because if they comply with the pre-trial discov ery order, they will be sanctioned against violating the blocking statute, whereas if they do not comply with the order, they will face sanctions prescribed by the FRCP. So enacting a blocking statute is not an appropriate countermeasure against the U.S. courts’ pre-trial discovery order. Filing for a protective order to the U.S. court premised on the Korean court’s decision on the provisional disposition to enjoin the submission of materials would be a realistic and practicable countermeasure. A party to the lawsuit may apply for an injunction with the Korean court against a third party who has been requested to submit materials in the pre-trial discovery procedure of the U.S. court. After receiving the decision on the provisional disposition by the Korean court, the party could seek a protective order with the U.S. court on such a ground. The party needs to prove the necessity for personal information protection for which the provisional disposition has granted and the difficulties arising from the conflicting legal obligations, rather than the fact that the provisional disposition to enjoin the submission of materials exists. Since judicial friction arising from pre-trial discovery order under the FRCP is characterized as a dispute that can only be resolved by joint efforts with the United States, it is ultimately desirable for Korea to conclude a bilateral treaty with the United States. When concluding a bilateral treaty, Korea needs to strongly insist that the following contents be inserted into the bilateral treaty. First, in cases to which the HCCH Evidence Convention applies, the method of requesting for examination of evidence stipulated by the HCCH Evidence Convention instead of domestic law should be followed. Second, the submission of materials directly related to the issues of litigation should be requested. Third, the individual documents requested to be submitted in the letter of request must be precisely specified. Last but not least, if the submission of materials according to the pre-trial discovery order is contrary to the Korean domestic law or the decision of the provisional disposition, the protective order should be affirmatively issued in consideration of the difficulty faced by the party who has to comply with the conflicting legal obligations. Along with this study, it is hoped that studies both on the current state of judicial friction between the United States and Korea arising from pre-trial discovery of United States and Korea’s countermeasures thereto would be more actively conducted and accumulated. Furthermore on the basis of such studies, it is expected that international judicial cooperation in civil matters would work better to streamline the investigation of evidence between the United States and Korea.

사면하부지반의 강도정수에 따른 억지말뚝 적용성 연구

이승현(Seung-Hyun Lee),장인성(In-Sung Jang) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.10

높이가 5m와 10m인 사면부와 사면하부지반으로 이루어진 지반조건에 대하여 여러 가지 강도정수를 갖는 사면하부 지반을 가정하고 안정해석을 수행한 결과 사면하부 끝단에 억지말뚝을 설치할 수 있는 사면하부지반의 강도정수의 범위를 얻을 수 있었고 표로써 제시하였다. 사면높이가 5m인 경우 사면하부지반의 점착력이 10kPa일 때 내부마찰각은 15°인 경우까지 억지말뚝의 설치가 가능하며 점착력이 20kPa와 25kPa인 경우 내부마찰각이 0°일 때만 억지말뚝의 설치가 가능하였다. 사면높이가 10m인 경우 사면하부지반의 점착력이 10kPa일 때 내부마찰각은 20°인 경우까지 억지말뚝의 설치가 가능하며 점착력이 40kPa, 45kPa 그리고 50kPa인 경우에는 내부마찰각이 0°인 경우만 억지말뚝의 설치가 가능함을 알 수 있었다. 가정한 사면에 적용한 억지말뚝에 대한 해석결과에 따르면 억지말뚝의 길이와 최대 휨모멘트의 크기는 내부마찰각의 존재여부에 큰 영향을 받음을 알 수 있었다. 사면하부지반의 내부마찰각이 0°인 경우 필요한 억지말뚝의 길이 Ds 와 d는 각각 내부마찰각이 5°인 경우에 비해 4.6배와 8.0배 컸다. 사면하부지반의 내부마찰각이 0°인 경우 억지말뚝에 발생하는 최대 휨모멘트는 내부마찰각이 5°인 경우에 비해 24.6배 컸다. 억지말뚝을 적용한 사면하부지반의 내부마찰각이 0°인 경우 억지말뚝의 길이 및 억지말뚝에 발생하는 최대 휨모멘트의 크기가 상당히 커서 억지말뚝의 적용을 어렵게 함을 알 수 있었다. 본 연구결과를 통해 볼 때 비배수상태에 있는 포화점토지반상에 성토를 하는 경우에는 압밀이 발생하는 시간적 여유를 갖도록 완속 성토함으로써 억지말뚝의 길이와 발생 최대 휨모멘트를 대폭적으로 감소시킬 수 있을 것으로 기대된다. Several foundation soil conditions below a homogeneous sand slope were assumed and slope stability analyses were conducted to determine the soil condition, in which a stabilizing pile can be used to increase the factor of safety against sliding. The assumed heights of the sand slope were 5m and 10m. For a 5m slope height, a stabilizing pile can be used in the foundation soil with a 15° internal friction angle and a cohesion of 10kPa. For a 10m slope height, a stabilizing pile can be used in the foundation soil with a 20° internal friction angle and a cohesion of 10kPa and a stabilizing pile can be used in the foundation soil with a 0° internal friction angle and 40kPa, 45kPa and 50kPa of cohesion. According to the analysis results of stabilizing pile-reinforced foundation soil, the length of the stabilizing pile and magnitude of the maximum bending moment were strongly affected by the internal friction angle of the foundation soil. The lengths of stabilizing pile, for an internal friction angle of 0° were 4.6, 8.0 times greater than those with an internal friction angle of 5°. The magnitude of the maximum bending moment of the stabilizing pile for an internal friction angle of 0° was 24.6 times greater than that for an internal friction angle of 5°. Practically, a stabilizing pile cannot be used for foundation soil with an internal friction angle of 0°. Considering the results derived from this study, the effects of a stabilizing pile can be maximized for soft foundation soil that is embanked with a slow construction speed.

A Comprehensive Prediction Method for the Saturated Internal Friction Angle of Sliding Zone Soils Based on Landslide Engineering Requirements

Mengfei Qu,Yu Bai,Qijun Hu,Leping He,Enxi Qiu,Xusheng Wan 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11

The measurement of the saturated internal friction angle of landslide sliding zone soils during the geological investigation could assist in engineering design, as it is a crucial parameter for landslide control. This research developed a comprehensive method to predict the saturated internal friction angle based on the support vector machine (SVM), after investigating the relationship between the saturated internal friction angle and the factors that affect the saturated internal friction angle. The procedure mainly consists of exploratory data analysis, influencing factors analysis, and prediction model set-up. Among the 18 factors, the evolution stage, gravel content, plasticity index, and dry unit weight were the most relevant factors predicting the saturated internal friction angle. The proposed method was illustrated and verified by a model accuracy test with the mean absolute error of the radial basis functions (RBF) kernel function was 0.90°, and the mean relative error was 8.77%. Therefore, this method could provide a reliable saturated internal friction angle in assisting engineers during landslide control.

Dynamic Young's Modulus and Internal Friction in Polycrystalline Copper

Kang, Chang-Seog,Chang, Si-Young,Hong, Sung-Kil 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.5

An attempt has been made to measure the temperature dependence of dynamic Young's modulus together with the related variation of internal friction in polycrystalline copper. A mechanical spectroscopy study was employed using a standard servo hydraulic fatigue testing machine equipped with a scanning laser extensometer. Dynamic Young's modulus and internal friction were measured over a temperature range of 298 to 873 K at very low frequencies of 0.1, 0.05, and 0.01 Hz. One internal friction peak was observed over the ranges 450 to 700 K, together with marked decreases in the dynamic Young's modulus in the same temperature range. From a quantitative analysis of the experimental data with the relaxation strength, relaxation time, and activation energy, it is concluded that the peak phenomenon is due to grain-boundary sliding relaxation.

An Alternative Approach for Determination of Rock Material Cohesion and Internal Friction Angle: Case Study of Marble from Peninsular Malaysia

( Goh Thian Lai ),( Abdul Ghani Rafek ),( Ailie Sofyaiana Serasa ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

The determination of rock material cohesion, c and the internal friction angle, Φ requires triaxial testing where expensive triaxial testing equipment as well as complicated testing procedures are needed. As an alternative approach, uniaxial compression with tensile strength testing can determine these two parameters. As part of an overall research programme characterising Malaysian rock mass parameters, sites composed of marble were also investigated. For Gunung Lang site; the average values of cohesion of triaxial testing, uniaxial compression & tensile strength testing at low stress regime and high stress regime are 14.5 MPa, 8.8 MPa and 14.3 MPa. The average friction angles are 49.7°, 50.3° and 35.3°. For Gunung Keriang site; the average values of cohesion for triaxial testing, uniaxial compression & tensile strength testing at low stress regime and high stress regime are 12.0 MPa, 9.6 MPa and 15.2 MPa. The average friction angles are 55.0°, 57.6° and 39.0°. For Gunung Rapat site; the average values of cohesion for triaxial testing, uniaxial compression & tensile strength testing at low stress regime and high stress regime are 20.0 MPa, 12.0 MPa and 18.0 MPa. The average friction angles are 50.0°, 48.0° and 35.5°. From this comparison, it can be seen that the use of uniaxial compression and tensile strength offers a viable option to determine cohesion, c and internal friction angle, Φ of rock.

붕괴된 암반사면에서 역해석에 의한 내부마찰각의 추정

이달원 ( Lee Dal Won ),김갑중 ( Kim Kap Jung ) 한국농공학회 2003 韓國農工學會誌 : 전원과 자원 Vol.45 No.6

In this study, the back analysis was performed by means of stereo-net, plane failure and block failure method to collapsed fields among the rock slopes designed by standardized criterion, and the internal frictions from the back analysis were compared with those used to reinforcement design. It was concluded that in the result of the analysis by means of stereo net, plain failure and block failure methods, the internal frictions used to re-design of collapsed slope underestimated 10℃, 5℃ and 10℃ in average. At present, the internal friction on the design is used the experience value according to the state of weathering, but internal friction angle by the back analysis on collapsed slope with various methods were more reliable values than those from the present method. And it was concluded that re-design was made extravagantly because the internal friction used to re-design for reinforcement of the collapsed slope was less than back analysis.

펀치각도가 팽창튜브의 에너지흡수특성에 미치는 영향에 대한 실험적 연구

최원목(Wonmok Choi),권태수(Taesoo Kwon) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4

Expansion tube is used as crash energy absorber when a crash accident occurs. The expansion tube dissipates the kinetic energy as friction and internal(plastic) energy, which are generated by expanding the tube with punch. In this paper the effect of conical angle of punch on energy absorbing characteristic of SCM440 expansion tube was studied in qusi-static experiments with three punches having different conical angles(15°, 30°, 45°). Finite element analysis were performed to confirm the effect of the conical angles on friction and internal energy. Two friction models, coulomb friction and constant shear friction, were used in the finite element analysis to confirm the variation of each friction coefficient(μ, m) with respect to the conical angles. The results of the experiment and finite element analysis indicate that the energy absorbed by tube were very sensitive to the change of the conical angles. Friction coefficient and friction energy decreased with increase of the conical angles. The internal energy, however, increased with increase of the conical angles.