• Title/Summary/Keyword: reliability factors

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Analytical Prediction of Bearing Life and Load Distribution for Plugin HEV (플러그인 HEV용 베어링 수명 및 응력분포의 분석예측)

  • Zhang, Qi;Kang, Jae-Hwa;Yun, Gi-Baek;Lyu, Sung-Ki
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.11 no.5
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    • pp.1-7
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    • 2012
  • The transportation is almost dependent on a single fuel petroleum with transportation energy dilemma. Hybrid Electric Vehicle(HEV) technology holds more advantages on efficiency improvements for petroleum consumption at the transportation. And bearing is recognized as the important component of gearbox. Gearboxes for HEV transmission have been ensured the highest reliability over some years in withstanding high dynamic loads. At the same time, the demands of lightweight design and cost minimization are required by thought-out design, high-quality material, superior production quality and maintenance. In order to design a reliable and lightweight gearbox, it is necessary to analyze bearing rating life methods between standard and different bearing companies with calculation methods for modification factors. In this paper, the influence of life time of bearings will be pointed out. Bearing contact stress and load stress distribution of HEV gearbox are obtained and compared with Romaxdesigner and BearinX. And the unequal wear of the left bearing for the gearbox intermediate shaft is investigated between simulation and test.

A Study on Accelerated Life Test of Hypoid Gear Rotary Reducer (하이포이드 회전감속기의 가속 수명시험 방법에 관한 연구)

  • Yoon, Sang-hwan;Beak, Kwon-in;Kim, Heonkeong;Lyu, Sung-ki
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.3
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    • pp.63-68
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    • 2017
  • In order to process more complicated and higher-precision parts, generally, an additional axis for a machine tool is needed which was an approach to minimize the cost of tool modification. A table with a rotary reducer that can rotate through the axis of the gear system was employed to a machine tool to achieve the purpose of adding an extra motion axis. In general, the motion of the rotary reducer is driven by a worm/wheel or helical gear system, which is different from the hypoid helical gear structure that used in this research. Reliability of guarantee of high accurancy throughout the whole life cycle is on of the critical factors to evaluate a rotary reducer in this field. In this paper, in order to evaluate life-time of rotary reducer, a low-cost accelerated life test was developed to satisfy the demands of clients.

A Study on the Probabilistic Nature of Fatigue Crack Propagation Life(II) -The Distribution of Crack Propagation Rate- (피로크랙 진전수명의 확률특성에 관한 연구 II)

  • 윤한용
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.6
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    • pp.1561-1567
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    • 1990
  • Recently, some reports of experimental research on the distribution of fatigue crack propagation rate have been published, and the reliability evaluation using the results of research for the mechanical structure has been executed. Since the thicknesses of specimens used in the published reports are limited to the thin ones, the applicability of the results into the mechanical structure with another thickness seems to be doubtful. That is, not only the quantitative evaluation, but also qualitative evaluation of the effect of specimen thickness has not been executed. In this study, an experimental investigation has been done by using the new type automated multi-stage fatigue testing machine which was developed by the author. The influence of specimen thickness for the distribution of fatigue crack propagation rate with the results is discussed.

Characterization of Microscale Drilling Process for Functionally Graded M2-Cu Material Using Design of Experiments (실험계획법을 이용한 M2-Cu 기능성 경사 재료의 마이크로 드릴링 특성 평가)

  • Sim, Jongwoo;Choi, Dae Cheol;Shin, Ki-Hoon;Kim, Hong Seok
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.24 no.5
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    • pp.502-507
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    • 2015
  • In this study, a microscale drilling process was conducted to evaluate the cutting characteristics of functionally graded materials. A mixture of M2 and Cu powders were formed and sintered to produce disk specimens of various compositions. Subsequently, a microscale hole was created in the specimen by using a desktop-size micro-machining system. By using design of experiments and analysis of variance, it was found that the M2-Cu composition, spindle speed, and the interactions between these two factors had significant effects on the magnitude of cutting forces. However, the influence of feed rate on the cutting force was negligible. A mathematical model was established to predict the cutting force under a wide range of process conditions, and the reliability of the model was confirmed experimentally. In addition, it was observed that increasing the wt% of Cu in an M2-Cu specimen increased the high-frequency amplitude of cutting forces.

Performance Prediction & Analysis of MGT Co-generation System

  • Hur, Kwang-Beom;Park, Jung-Keuk;Rhim, Sang-Kyu;Kim, Jae-Hoon
    • New & Renewable Energy
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    • v.2 no.3
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    • pp.15-22
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    • 2006
  • As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This new market penetration using the distributed generation technology is linked to a large number of factors like economics and performance, safety and reliability, market regulations, environmental issues, or grid connection standards. KEPCO, a government company in Korea, has performed the project to identify and evaluate the performance of Micro Gas Turbine(MGT) technologies focused on 30, 60kW-class grid-connected optimization and combined Heat & Power performance. This paper describes the results for the mechanical, electrical, and environmental tests of MGT on actual grid-connection under Korean regulations. As one of the achievements, the simulation model of Exhaust-gas Absorption Chiller was developed, so that it will be able to analyze or propose new distributed generation system using MGT. In addition, KEPCO carried out the field testing of the MGT Cogeneration system at the R&D Center Building, KEPCO. The field test was conducted in order to respond to a wide variety of needs for heat recovery and utilization. The suggested method and experience for the evaluation of the distributed generation will be used for the introduction of other distributed generation technologies into the grid in the future.

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The Information Search Method According to Eating-out Motivation of College Students in Eastern Area of Kangwon Province (강원도 영동권 지역 대학생들의 외식동기에 의한 정보탐색방법)

  • Yoon Tae-Hwan
    • Korean journal of food and cookery science
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    • v.22 no.2 s.92
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    • pp.213-221
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    • 2006
  • Although motivation and information search have both been studied continuously and separately as important marketing strategies, the relation between cause and effect has received little research attention. Therefore the objective of this study was to research the causal relationships between motivation and information search method. Frequency analysis and reliability analysis, factor analysis, and SEM(Structure Equation Model) were adopted to analyze the data. Motivation was divided into 5 factors which significantly influenced information search method. Factor 1, 'Reception and congratulation', influenced information search positively through 'newspaper, magazine', and 'word of mouth' but negatively through 'TV-advertising' and 'Flyer, Press copy'. Factor 2, 'Change of dietary life', influenced positively 'TV-advertising'. Factor 3, 'Economic saving', influenced positively 'newspaper, magazine', and 'the e-mail's advertising' Factor 4, 'Preference motivation', influenced negatively 'word of mouth' Factor 5, 'Advertisement and companion's need', influenced positively 'newspaper, magazine', and 'the e-mail's advertising' but negatively 'TV-advertising' As a result, customers appeared to choose various information search methods according to their eating-out motivation. 'The e-mail's advertising', and 'word of mouth' are popular among customers' information search methods. Therefore, food-service corporations need to try eliminating negative images of various advertisements and activate positive word of mouth marketing, promotion through internet.

A Study on Expectation Factor and Level About Food Coordination in Restaurant - For Twenties to Thirties Customers (레스토랑에서의 푸드 코디네이션에 대한 기대요인과 수준에 관한 연구 -$20{\sim}30$대 이용고객을 대상으로-)

  • Ahn, Ji-Won;Kim, Heh-Young;Ko, Sung-Hee
    • Korean journal of food and cookery science
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    • v.23 no.6
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    • pp.930-939
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    • 2007
  • The purpose of this study was to suggest ways for practical food coordination, by examining restaurant-visitor' expectation factors for food coordination in restaurants. Statistical analyses were carried out based on the statistical data collected via survey from the restaurant. visitors. For the data analysis, factor analysis, reliability analysis, frequency analysis, t-test, and ANOVA were applied, using the SAS 9.1(ver.) program. In the results for the general perception of food coordination, the degree of recognition by restaurant visitors for food coordination is not high. However, necessity for food coordination is highly recognized and a 70% of the respondents were positive in their response about an expropriation price. Fitty percent of the respondents indicated a positive response regarding the relationship between the visual effect of the food and a re-visit to the restaurant. Therefore, most restaurant visitors believe food coordination is necessary in restaurants, and expect to pay for it in price.

Attitude, Role Perception and Nursing Stress on Life Sustaining Treatment among Intensive Care Unit Nurses (중환자실 간호사의 연명의료에 대한 태도, 역할인식 및 간호 스트레스)

  • Lee, Su Jeong;Kim, Hye Young
    • Korean Journal of Adult Nursing
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    • v.29 no.2
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    • pp.131-142
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    • 2017
  • Purpose: The aims of the study were to investigate relationships among intensive care unit (ICU) nurses' attitude, role perception, and nursing stress related to life sustaining treatment (LST), and secondly, to identify factors influencing nursing stress about LST. Methods: Participants were 202 conveniently sampled ICU nurses from general hospitals in Korea with over 300 beds. From December 1, 2015 to January 31, 2016, data were collected using structured questionnaires. The questionnaire was designed to measure nursing stress related to LST. Content validity and reliability was established for the instrument. Results: Relationships were found between attitude and role perception, and between role perception and nursing stress about LST. Participants' role perception, gender, education level, and the experience of dealing with family members of patients receiving LST accounted for 13% of variance in nursing stress about LST. Conclusion: Results confirmed that ICU nurses' role perception affects nursing stress about LST. Accordingly, the nursing education programs related to LST should aim to enhance role perception of nurses, and strategies to reduce the nursing stress about LST of the nurses in ICU need to be further developed.

Development of Simulator for Hierarchical Battery Management System (계층적 배터리 관리 시스템 시뮬레이션 기술 개발)

  • Kang, Hyunwoo;Ahn, SungHo;Kim, Dongkyun
    • IEMEK Journal of Embedded Systems and Applications
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    • v.8 no.4
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    • pp.213-218
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    • 2013
  • In this research, we report on the development of simulation system for performance verification of BMS(Battery Management System) which is utilized in electric vehicles. In the industrial circles, a manufacturer of BMS typically tests their system with real battery packs. However, it takes a long time to test all functions of BMS. Here, we develop BMU(Battery Managament Unit) as an embedded board, which will be installed in electric vehicle for controlling battery packs. All other environment factors for testing BMU are developed in softwares in order to reduce the term of test. Especially, the proposed system consists of cell simulator and CMU(Cell Management Unit) simulator which simulate real battery cells and control battery cells. These simulators enable the BMU to test more battery cells. In addition, proposed system provides diagnosis program in order to diagnose and monitor the condition of BMS which makes the test of BMS more easily. In order to verify the performance of the developed simulator, we have performed the experiment with real battery packs and our simulator. Through comparing two results of experiments, we verify that developed simulator shows better performance in terms of less amount of testing duration though having high reliability.

Service Scheduling for Workflow Based Applications in Grids (그리드에서 워크플로우 기반 어플리케이션을 위한 서비스 스케줄링)

  • Chin, SungHo;Lee, JongHyuk;Yu, HeonChang
    • The Journal of Korean Association of Computer Education
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    • v.9 no.6
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    • pp.89-98
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    • 2006
  • Recently, grid computing environment has being changed to the service-oriented grid integrated with Web Services. In this architecture, there is the service-oriented grid application in which Grid Services are executed according to the workflow of the grid application. This implies that the grid scheduling method needs to consider grid service characteristics. Therefore, we propose the grid service performance model based on factors such as service availability, accessibility, reliability, throughput, and slowdown, and develop service scheduling method to increase performance of the service-oriented grid application.

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