• Title/Summary/Keyword: Radius

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The Real Time Measurement of Dynamic Radius and Slip Ratio at the Vehicle (차량에서 실시간 동반경 및 슬립율 측정)

  • Lee, Dong-Kyu;Park, Jin-Il;Lee, Jong-Hwa
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.6
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    • pp.89-94
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    • 2006
  • The tire delivering power generated from engine to the ground pulls a vehicle to move. Radius of tires is changeable due to elasticity that depends on the speed of vehicle and traction force. The main objectives on this study are real time measurement of dynamic radius and slip ratio according to the speed and traction force. The dynamic radius is proportional to speed and traction force. According to measurement, the dynamic radius is increased about 3mm under 100km/h compared to stop. It is also increased about 1.5mm when a traction force is supplied as much as 4kN compared to no load state at low speed. There is no strong relationship between slip ratio and vehicle speed. The slip ratio is measured up to 4% under WOT at first stage gear. Through this research, the method of measuring dynamic radius and slip ratio is set up and is expected to be applied to the measurement of traction force in chassis dynamometer or accelerating and climbing ability.

A Study on the Effect of Tip Radius of Diamond Stylus Machined by Ion Sputter in Surface Roughness Measurement (이온스파터 가공한 다이아몬드 촉침의 선단반경이 표면거칠기 측정에 미치는 영향)

  • Han, Eung-Gyo;No, Byeong-Ok;Yu, Yeong-Deok
    • Journal of the Korean Society for Precision Engineering
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    • v.7 no.3
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    • pp.37-47
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    • 1990
  • In accordance with the high precision of mechanical elements, it has been required to high precision in surface roughness measurement and, therefore, stylus tip radius is manufa- ctured less than 2 .mu. m through ion sputter machining. In this experiment, by suing ion sputter machined stylus pf fine tip, radius and lapping machined stylus, surface roughness of standard specimens, silicon wafer were measured and then Rmax, Ra, RMS value were investi- gatedaccording to the variation of tip radius of stylus. As a result, measuring error due to the variation of stylus tip radius in surface roughness measurement was decreased by using ion sputter machined stylus and also the measuring accuracy was improved. And the measuring variation of Ra, RMS calculated from correlation coefficient lager than 0.9 on the wave of short period and amplitude using ion sputter machined stylus of fine tip radius.

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A STUDY ON TAYLOR FLOW ACCORDING TO RADIUS RATION AND ANGULAR VELOCITY (반경비 및 각속도의 변화에 따른 Taylor 유동에 관한 연구)

  • Bae, K.Y.;Kim, H.B.;Chung, H.T.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.10a
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    • pp.127-133
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    • 2007
  • This paper represents the numerical study on Taylor flow according to the radius ratio and the angular velocity for flow between tow cylinder. The numerical model is consisted of two cylinder which inner cylinder is rotating and outer cylinder is fix, and the axial direction is used the cyclic condition because of the length for axial direction is assumed infinite. The diameter of inner cylinder is assumed 86.8 mm, the numerical parameters are angular velocity and radius ratio. The numerical method is compared with the experimental results by Wereley, and the results are very good agreement. The critical Taylor number is calculated by theoretical and numerical analysis, and the results is showed the difference about ${\pm}10\;%$. As $Re/Re_c$ is increased, Taylor vortex is changed to wavy vortex, and then the wave number for azimuthal direction is increased. Azimuthal wave according to the radius ratio is showed high amplitude and low frequence in case of small radius ratio, and is showed low amplitude and high frequence in case of large radius ratio.

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Interworking between PPP CHAP and RADIUS Authentication Server on GPRS Network (GPRS 망에서 PPP CHAP과 RADIUS 인증 서버 연계 방안)

  • 박정현;이상호
    • Journal of KIISE:Computing Practices and Letters
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    • v.9 no.5
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    • pp.567-577
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    • 2003
  • We usually applied PPP CHAP (Point-to-Point Protocol Challenge Handshake Authentication Protocol) when the visited ISP subscriber accesses to authentication server in own home ISP network and IP Assignment for remote Internet service. But PPP CHAP doesn't support in case of visited ISP subscriber in GPRS network accesses to authentication server in own home ISP network for wireless Internet service. We suggest solution this problem with PPP CHAP improvement. For this we propose the modified PPP CHAP message format, PCO Message format at MT, and interworking message and format between GGSN and RADIUS in home ISP network for wireless internet service of mobile ISP subscriber at GPRS network in this paper. We also show authentication results when visited mobile ISP subscriber via PPP CHAP at GPRS network accesses the RADIUS server in home ISP network.

Study on Automatic External Defibrillators deployed at General Supermarkets

  • PARK, Sang-Kyu;KIM, Jee-Hee;UHM, Tai-Hwan
    • Journal of Distribution Science
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    • v.17 no.12
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    • pp.63-70
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    • 2019
  • Purpose: This study was to propose effective deployment of automatic external defibrillators (AEDs) installed at general supermarkets. Research design, data, and methodology : We conducted interview and data surveys on 72 large distributors in Seoul and Gyeonggi province in South Korea. The content of this survey was consisted of general status on the general supermarkets, AED deployment and management regarding public access defibrillation (PAD). GPower (v 3.1.9.4; Universität Kiel, Kiel, Germany) was also used to analyze statistical power. Radius and actual distance, radius and retrieval time were compared by t-test at α=.05. respectively. Results : Difference between the radius (102.7 meters) and the actual distance (187.8 meters) was 85.1m, it had statistically significant difference (p<.001). The actual distance was longer compared to the radius distance. Difference between the radius (114.1 seconds) and the retrieval time (208.7 seconds) was 94.6s, it had statistically significant difference (p<.001). The retrieval time took longer compared to the radius time as well. Conclusions : The finding shows that only 45.9% of the general supermarkets are satisfied with the actual AED coverage within 3 minutes. This needs to enhance AED deployment to reduce defibrillation time and AED management to boost application in South Korea.

Multiple objects focusing based on image segmentation using radius of PSF (점확산함수 반지름을 사용한 영상분할 기반 다중객체 자동초점)

  • 김기만;황성현;신정호;백준기
    • Proceedings of the IEEK Conference
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    • 2003.11a
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    • pp.7-10
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    • 2003
  • This paper proposes the multiple objects focusing algorithm. Given multiple objects at different distances from a camera, we assume that one object is well-focused and the others are out-of-focused. The proposed auto-focusing algorithm is summarized as follows: (i) detects edges from an input image, (ⅱ) estimates the radius of PSF (Point Spread Function) across the edge, (ⅲ) gather edge points having same radius of PSF, (ⅳ) segments the image into regions with the same radius of PSF, and (ⅴ) restores the each segmented region using the corresponding PSF.

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The Spectral Radii of Graphs with Prescribed Degree Sequence

  • Li, Jianxi;Shiu, Wai Chee
    • Kyungpook Mathematical Journal
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    • v.54 no.3
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    • pp.425-441
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    • 2014
  • In this paper, we first present the properties of the graph which maximize the spectral radius among all graphs with prescribed degree sequence. Using these results, we provide a somewhat simpler method to determine the unicyclic graph with maximum spectral radius among all unicyclic graphs with a given degree sequence. Moreover, we determine the bicyclic graph which has maximum spectral radius among all bicyclic graphs with a given degree sequence.

EFFICIENCY ANALYSIS OF A DOMAIN DECOMPOSITION METHOD FOR THE TWO-DIMENSIONAL TELEGRAPH EQUATIONS

  • Jun, Younbae
    • East Asian mathematical journal
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    • v.37 no.3
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    • pp.295-305
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    • 2021
  • In this paper, we analyze the efficiency of a domain decomposition method for the two-dimensional telegraph equations. We formulate the theoretical spectral radius of the iteration matrix generated by the domain decomposition method, because the rate of convergence of an iterative algorithm depends on the spectral radius of the iteration matrix. The theoretical spectral radius is confirmed by the experimental one using MATLAB. Speedup and operation ratio of the domain decomposition method are also compared as the two measurements of the efficiency of the method. Numerical results support the high efficiency of the domain decomposition method.

Estimations of Zeros of a Polynomial Using Numerical Radius Inequalities

  • Bhunia, Pintu;Bag, Santanu;Nayak, Raj Kumar;Paul, Kallol
    • Kyungpook Mathematical Journal
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    • v.61 no.4
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    • pp.845-858
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    • 2021
  • We present new bounds for the numerical radius of bounded linear operators and 2 × 2 operator matrices. We apply upper bounds for the numerical radius to the Frobenius companion matrix of a complex monic polynomial to obtain new estimations for the zeros of that polynomial. We also show with numerical examples that our new estimations improve on the existing estimations.