• Title/Summary/Keyword: High reliability

Search Result 6,482, Processing Time 0.03 seconds

A relevant factor analysis on dental treatment fear in some high school students (일부 고등학생의 치과치료 공포감에 대한 관련요인분석)

  • Hong, Sun-Hwa;Oh, Jung-Suk
    • Journal of Korean society of Dental Hygiene
    • /
    • v.12 no.4
    • /
    • pp.741-749
    • /
    • 2012
  • Objectives : High school students to measure fear of dental treatment, dental health care workers according to the level of reliability of this study is to determine the extent of terror was carried out. Methods : Located in Gwangju, 165 high school students were surveyed. SPSS windows ver. 11.0 by demographic characteristics and oral health characteristics of the frequency and percentage, and dental health care workers about the reliability of the Chi-square test, the general characteristics and oral health characteristics by dental fear of the t-test and one way ANOVA and were factors associated with dental fear of the stepwise multiple regression analysis was performed. General characteristics, except Cronbach-${\alpha}$ coefficient was 0.911. Results : According the general fear of Dental Treatment Fear Factor item 4, you'll feel the highest fear when you feel the muscle tension and the needle pricks your skin. The reliability of dental health care workers if the dentist lower the higher the grade, subjective oral health status is considered more reliable health was higher, the stronger the reliability of pain was significantly lower (p<0.05). Other care coordination include the reliability of sources of interest in subjective oral health history, no past experience in treating pain and increase the number of reliability was low (p<0.05), past experience and increase the number of pain during treatment the stronger the fear of more pain showed an increase (p<0.05). Conclusion : According the related factors about the fear of dental treatment, stimulus-response and fear of dental office have increased, the fear of dental treatment increase.

An Analytical Study of the Flexural Deformation for High Strength Concrete Structures using Reliability Theory (신뢰성 이론을 이용한 500kgf/$\textrm{cm}^2$의 고강도콘크리트 구조물에 대한 휨변형의 해석적 연구)

  • 송재호;최광진;김민웅;홍원기
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1995.04a
    • /
    • pp.231-236
    • /
    • 1995
  • The object of this thesis is an analytical study on flexural deformation of high strength concrete structures using reliability theory. Using the established experimental data that have been presented in various documents the stress-strain relationship curves of high strength(500kgf/$\textrm{cm}^2$)models are proposed. Based on both methods of logarithm regression analysis and multiple regression analysis adopted in order to establish the relationships between design parameters, response random variables and flexural deformation analyzed using Monte Carlo simulation and Simpson composite formula. Additional random variables are introduced to incorporate both the confidence in the analytical accuracy of engineering mechanics associated with structural response quantities and the uncertainty in the construction quality control. The result is expected to accomodate other important design parameter of high strength concrete design in treating reliability theory that practicing engineers, structural engineering often face.

  • PDF

A Study on the High-Accuracy Power Meter and Reliability Verification Plan (고정밀 전력미터의 개발과 신뢰성 확보 방안에 대한 연구)

  • Lee, Sanghun;LEE, Changhwa
    • Journal of Korea Multimedia Society
    • /
    • v.20 no.7
    • /
    • pp.1046-1053
    • /
    • 2017
  • We propose a design method of high accuracy power measuring device and the method of securing the reliability of the measured data. As a design method for the development of the high accuracy power measuring device, the circuit was made by reflecting the high accuracy power measuring ICs and the CT (Current Transformer). To ensure the reliability of the power meter, we requested to the watt-hour meter certified testing organization to measure the error rate, and the error rate of active power based on the "Wattmeter Technical Standard(Revision notify 2014-283)" was measure, and the error rate was confirmed to be less than 0.1%.

Application of Low Voltage High Resistance Grounding in Nuclear Power Plants

  • Chang, Choong-Koo;Hassan, Mostafa Ahmed Fouad
    • Nuclear Engineering and Technology
    • /
    • v.48 no.1
    • /
    • pp.211-217
    • /
    • 2016
  • Most nuclear power plants now utilize solid grounded low voltage systems. For safety and reliability reasons, the low voltage (LV) high resistance grounding (HRG) system is also increasingly used in the pulp and paper, petroleum and chemical, and semiconductor industries. Fault detection is easiest and fastest with a solidly grounded system. However, a solidly grounded system has many limitations such as severe fault damage, poor reliability on essential circuits, and electrical noise caused by the high magnitude of ground fault currents. This paper will briefly address the strengths and weaknesses of LV grounding systems. An example of a low voltage HRG system in the LV system of a nuclear power plant will be presented. The HRG system is highly recommended for LV systems of nuclear power plants if sufficient considerations are provided to prevent nuisance tripping of ground fault relays and to avoid the deterioration of system reliability.

Design and Analysis of MEMS Vibrating Ring Gyroscope Considering High-g shock reliability (고내충격용 MEMS 진동형 링 자이로스코프 설계 및 분석)

  • Yoon, Sung-Jin;Park, U-Sung
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.64 no.10
    • /
    • pp.1440-1447
    • /
    • 2015
  • This paper describes a study for anti high-shock design of MEMS vibrating ring gyroscope. Structure models was made by MEMS technology processing. MEMS Vibrating Ring Gyroscope mechanical structure were not only anti-high shock simulated with the LS Dyna Ver 971 software but also with mathematical analysis and the finite element method in order to confirm the shock reliability. Shock test result of a MEMS vibrating gyroscope being developed to have gun-hardened survivability while maintaining tactical grade navigation performance for application to various guided projectiles.

A Study on the Reliability of an Air Foil Journal Bearing for High Speed Turbomachinery (고속 터보기계용 공기 포일 저널 베어링의 신뢰성에 관한 연구)

  • Lee, Yong-Bok;Kim, Tae-Ho;Kim, Chang-Ho;Lee, Nam-Soo
    • 유체기계공업학회:학술대회논문집
    • /
    • 2002.12a
    • /
    • pp.199-206
    • /
    • 2002
  • This paper describes a reliability characteristics of an air foil journal bearing for high speed turbomachinery at room temperature. To verify the reliability of air foil journal bearing, lift-off characteristics, load carrying capacity, and 10,000 cycle start-stop test were performed with motor driven test rig. Lift-off test shows the relationship between the rotating speed of the shaft and the frictional torque with bearing surface. About load carrying capacity, the tested air foil journal bearing produced a load capacity of 500N at an operating speed of 15,000rpm, which is compared with results of numerical analysis and empirical coefficients. Finally, The trends in change of start torque, stop torque, and bearing temperature were shown during 10,000 cycle start-stop test of an air foil journal bearing. from the results of this work, an air foil bearing will be done well, as a supported bearing for high speed turbo-compressor.

  • PDF

A Study on the Proper Number of Banks of Parallel Operation of Transformer in Large-scale Power Plants Using the High Temperature Fuel Cell Considering the Internal Failure (내부고장을 고려한 고온형 연료전지 대규모 발전단지의 병렬운전 변압기 적정 뱅크수에 관한 연구)

  • Chong, Young-Whan;Chai, Hui-Seok;Sung, In-Je;Kim, Jae-Chul
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.28 no.3
    • /
    • pp.26-31
    • /
    • 2014
  • High temperature fuel cell system, such as molten carbonate fuel cells(MCFC) and solid oxide fuel cells(SOFC), are capable of operating at MW rated power output. The power output change of high temperature fuel cell imposes the thermal and mechanical stresses on the fuel cell stack. To minimize the thermal-mechanical stresses on the stack and increase the systems reliability, we should divide the power plant configuration to several banks. However, the improvement of reliability in fuel cell power plant system causes an increase of the investment cost, for example, replacement costs, labor costs, and so on. For this reason - the balance between investment and reliability improvement - many studies about the appropriate level of investment have been conducted. In this paper, we evaluate the cost for operation and installation, the benefit for electric energy and thermal energy sales, and the system reliability for several cases : these cases relate with the bank configuration.

A Study on the Reliability of an Air Foil Journal Bearing for High Speed Turbomachinery (고속 터보기계용 공기 포일 저널 베어링의 신뢰성에 관한 연구)

  • Kim, Tae-Ho;Lee, Yong-Bok;Kim, Chang-Ho;Lee, Nam-Soo
    • The KSFM Journal of Fluid Machinery
    • /
    • v.6 no.2 s.19
    • /
    • pp.7-14
    • /
    • 2003
  • This paper describes reliability characteristics of an air foil journal bearing for high-speed turbomachinery at a room temperature. To verify the reliability of air foil journal bearing, lift-off characteristics, load carrying capacity, and 10,000 cycle start-stop test were performed with a motor-driven test rig. A lift-off test shows the relationship between the rotating speed of the shaft and the frictional torque with bearing surface. About a load-carrying capacity, the tested air foil journal bearing produced a load capacity of 500N at an operating speed of 15,000rpm, which is compared with results of numerical analysis and empirical coefficients. Finally, the trends in change of start torque, stop torque, and bearing temperature were shown during a 10,000-cycle start-stop test of an air foil journal bearing. We found that an air foil bearing performs well, as a supported bearing for the high-speed turbocompressor.

The Effect of Repurchase Intention on Baker Shop Customer's Service Quality Satisfaction (베이커리 이용객의 서비스 품질 만족도가 재 구매에 미치는 영향)

  • Kim, Yong-Sik;Park, Sang-Jun
    • Culinary science and hospitality research
    • /
    • v.11 no.3 s.26
    • /
    • pp.40-55
    • /
    • 2005
  • The purpose of this study was to understand the effect of customers' repurchase intention, extract important factors, systematically analyze them and suggest the direction of bakery industry through studying the customers' satisfaction with bakeries. The researcher modified the questionnaire developed by Park, CH(1998), Lee, JH(2000), Yoon, YC(2000), and Kim SE(2002). In order to assess the level of customers' satisfaction with bakeries, a five point Likert scale was used. The used statistical methods for the data analysis were frequency analysis, reliability analysis, t-test factor analysis, ANOVA, multiple regression analysis. For all analyses of the research question, an alpha level of.05 was used. The major findings obtained from this study were as fellows. First on the factors of reliability and service ability, there was a high difference between males and females, and singles and the married. Second, on the factors of accessibility using convenience, service ability, and service response, there was a high difference among using frequence. Third, on the reliability factors, there was a high difference among average using amount per month. Forth, on the factors of accessibility using convenience, and service response, there was a high difference among types of customers' residing styles. Fifth, on the factors of income level, there was statistically no difference. Lastly, on the factors of accessibility using convenience, tangibleness, and service response, these factors significantly influenced customers' repurchase intention.

  • PDF

Reliablity of Distributed Feedback Laser Diodes for High-speed Optical Communication Systems (고속 광통신 시스템용 비대칭 분포귀환형 레이져 다이오드의 신뢰성에 관한 연구)

  • Jeon, Su-Chang;Joo, Han-Sung;Yun, Il-Gu
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2005.05a
    • /
    • pp.96-99
    • /
    • 2005
  • As the demand of internet networks using backbone communication systems recently increased, the researches on the high-speed wideband optical communication systems are required. For high-speed optical communication systems, asymmetric sampled grating distributed feedback laser diodes (DFB-LDs) are developed and the reliability of DFB-LDs is examined. The reliability of DFB-LDs is performed by monitoring I-V and L-I characteristics and two degradation phenomena related to the electrical characteristics of LDs are observed during the life tests. The first degradation phenomenon by increasing the reverse current is considered as a formation of leakage current path enough to prevent lasing operation in lateral blocking layer near active region of lasers. The second degradation phenomenon by decreasing the forward current is considered as activation of non-radiative Auger recombination process by thermal energy and the second degradation phenomenon is recovered after the off-test period at room temperature Eventually, evaluating the reliability of DFB LDs can allow us to improved the manufacturability in high-volume manufacturing.

  • PDF