• 제목/요약/키워드: Wear-out points

검색결과 20건 처리시간 0.022초

직립마모 저감을 위한 원호형 차륜답면형상안 마모특성 분석 (Wear analysis of arc-type wheel profiles to reduce severe wheel flange wear)

  • 허현무;권성태;서정원;이찬우
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2004년도 춘계학술대회 논문집
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    • pp.720-725
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    • 2004
  • We proposed new arc-type wheel profiles to improve severe flange wear of conventional wheel profile coned 1:40. We designed many candidate wheel profiles and analyzed the geometric characteristics, dynamic performance and stress at contact points to draw out the final profiles. From the analysis result, we chose two cases of profiles and applied to wheels of test train. Tests carried out in service line to analyze the dynamic performance and verify the wear reduction for two cases of profiles. Test results shows the equal level of dynamic performance and the improvement of wheel flange wear compared with the conventional wheel profile.

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마모입자 분석기술을 이용한 초음속 항공기 엔진의 상태 예측에 관한 연구 (A Study on the Prediction of Engine Condition of Supersonic Aircraft through the Wear Debris Monitoring Technique)

  • 정병학;정동윤
    • Tribology and Lubricants
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    • 제13권2호
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    • pp.82-88
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    • 1997
  • This paper describes an empirical equation which can be used to predict the engine condition of supersonic aircraft. The equation, which is derived from the trend analysis of JOAP data, represents the concentration of Fe particles in the engine oil. The result of the trend analysis shows that the concentration of Fe particles is a function of running time of engine oil. Meanwhile the slope of Fe concentration is a function of running time of engine. Threfore, the empirical equation was derived as $w=a(t_e).t_o+b$. However, the equation could not enough to diagnose the damaged part of engine quantitatively. To make up for the weak points of the equation, qualitative analysis was carried out. For that purpose wear debris were collected from the abnormal engine and analyzed by EDS to detect the damaged parts of engine.

PERFORMANCE EVALUATION OF NEW SPACER GRID SHAPES FOR PWRS

  • Song, Kee-Nam;Lee, Soo-Bum;Lee, Sang-Hoon
    • Nuclear Engineering and Technology
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    • 제39권6호
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    • pp.737-746
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    • 2007
  • A spacer grid, which is one of the most important structural components in a PWR fuel assembly, supports its fuel rods laterally and vertically. Based on in-house design experience, scrutiny of the design features of advanced nuclear fuels and the patents of other spacer grids, KAERI has devised its own spacer grid shapes and acquired patents. In this study, a performance evaluation of KAERI's spacer grid shapes was carried out from mechanical/structural and thermohydraulic view points. A comparative performance evaluation of commercial spacer grid shapes was also carried out. The comparisons addressed the spring characteristics, fuel rod vibration characteristics, fretting wear resistance, impact strength characteristics, CHF enhancement, and the pressure drop level of the spacer grid shapes. The results show that the performances of KAERI's spacer grid shapes are as good as or better than those of the commercial spacer grid shapes.

로타리 압축기의 베인, 슬롯부 윤활해석 (Lubrication Analysis at the Vane & Slot Parts of Rotary Compressors)

  • 이상용;황선웅
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1997년도 제25회 춘계학술대회
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    • pp.136-141
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    • 1997
  • Rotary compressor is one of the most useful mechanism that is widely applied in refrigeration and air-conditioning systems. That is due to character of rotary compressor -compact, simple etc.While there is a lot of strong points, there is room for improvement because it is composed of many parts which have wear problem, friction losses and leakage. In this paper, theoretical investigation about vane and slot parts at which we observe severe wear is carried out. Through the study of lubrication, the behavior of vane during one cycle can be predicted and the cause of wear at slot will be discovered. To solve the equations, fletcher-powell method is applied. The result of analysis show that vane bevell to the slot part with discharge port before rotation of shaft is 180 degree and bevell to the slot part with suction port after 180 degree. The motion of vane is divided 3 mode that depends on behavior of vane. This paper define the first mode when vane tilt to the compression chamber, the second mode when vane tilt to the suction chamber, and the third mode when vane move straightway.

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우리나라 옷에 대한 현대인(現代人)의 의식(意識)과 춘용실태(春用實態)에 관(關)한 연구(硏究) - 서울 지역(地域)을 중심(中心)으로 - (A Study on Modern People's Consciousness and Wearing Practice of Korean Costumes)

  • 황춘섭
    • 복식
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    • 제1권
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    • pp.119-129
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    • 1977
  • It is significant for developing the future for us to know our present age. In order to preserve our Korean costume as a fola clothes retaining our distinguished independent characterisitics and to help design the tomorrow of our Korean costume playing a role as a racial to develop the world clothing culture, a survey was conducted to investigate modern people's conscious-ness and wearing practumes of Korean costume by questionaire and interviewing methods. The results of the survey were analyzed as follows: (1) At present, Korean costumes were purchased as customtailored(64.0%) and as ready-made(17.8%) and most of them were not made at individual homes. The laundry and ironing of them were carried out at laundry shops(68.8%). Considering our present economic, social and cultural aspects, sowing, laundryand ironing will not be carried out at homes again in the future and ready made costumes seen to be produced in a large scale in the future. Garment makers and laundry shop operators should be trained how to make our Korean costumes retain our traditional beauty in the course of their production and laundry and the makers of ready-made costumes must make research how to efficiently produce ideal ready-made costumes by adopting the synchro system in their wrk odisivion. (2) The age group wearing Korean costumes most frequently was the aged people over 60 (their wearing rate; 45%-50%) and the group wearing them most frequently next io the aged people over 60, was housewives(their wearing rate; 15%-20%). Excludign aged people and housewives, other respondentsdid not wear Korean costumes very frequently. Men's wearing rate was lower their wearing rate was the younger their ages were and the less their monthly incomes were. Korean costumes were used for holiday and festival(60%), wedding and funeral ceremonies (52%), visiting and working(22%), casual wear(12.8%) and home wear(9.2%). The use of Korean costumes as casual and home wears, was lower than the use for holday, festival, visiting and working, Under our present circumstances in which our Korean people use both Western style clothes and Korean costumer, our Korean costume has lostits position as a basic and necessary requiement in Korean people's daily life and become a ceremonical and fancy costume. It is natural that the times and life change everything in our daily life. Our costume has to be made as good ceremonial and fancy clothes satisfying modern sensibility according to its new role. In order for us to get close with our clothes, a keen study must be carried out to cleat the color, material, style, function and harmony of the Korean costume matching the of the times. (3) The 47.8% of the respondents answered that they were proud of our Korean costume as our folk clothes, 47.6% replied that thought them just common and 1.1% responded that they were ashamed of it. Most of them were affirmative in feeling pride with our Korean costume. (4) Considering the functional aspect of Korean costumes, their strong points were symetric beauty, rhythmical beauty, unity feeling, harmonical beauty and detailed decorations. Their common shortcomings were lack of individuality and inadequateness for active life. The shortcomings of woman costumes were suppressing breast, making resperation difficult and in adequnteness in summer time. The main reason not to wear our Korean costumes, was due to the fact that they are incomvenient for active life. As a measure to eliminate such shortcomings, 1) the suspension system of skirt to remove the suppression of breast should be generally adopted. 2) they should be simplified in their structure to make them convenient for active life and adepuate in wearing them in hot weather in an extent to which the traditional beauty of the costume may not be lostand 3) a new technique must be explored for showing individuality by wearing method and new arrangment of colors and decorations. (5) The reasons desiring to wear Korean costumes were classifide as follows: A. Korean costumes are our traditional clothes(43.4%). B. Korean costumes are noble and beautiful(26.8%). C. They are accustomed to wear Korean costumes by habit(19.5%). D. Korean costumes are necessary for attending ceremoneis(9.5%). E. Miscellaneous reasons(0.8%). Classifying these reasons into age groups, the high age group over 40 wore them because they were easy to wear by habit and the low age group of 10-30 never thought that they were east to wear by habit. Considering that even those who were accustomed to wear Korean costumes showed a low wearing rate and that the young generation were accustomed to wear Western style clothes rather than Korean costumes, the wearing rate of Korean costumes will be reduced in the future if such trend continues. It is urgent for us to make our best efforts in order to enhance the interest of young generation in Korean costumes and not to make them lose the strong points of Korean costume in the future. (6) Conicering the plan of the respondents on what kind of clothes they were going to wear in the future, among the age group over 50, those who wanted to wear only Korean costumes were 24.8%(men) and 35.1%(women), those who wanted to wear 49.7%(men) and 47.4(women), those who wanted to wear chiefly Western style clothes were 20.7% (men) and 14.4%(women) and those who wanted to wear only Western style clothes, were 2.4% (men) and 2.1%(women). This shows that the general tendency to wear only or chiefly Korean costumes is more prevalent than that to wear only Western style. Among the age group under 50, the tendency to wear Western style clothes was conspicuous and most of the respondent answered that they would wear chiefly Western style clothes and Korean costumes occasionally. Only 5.4% of the respondent answered that they would wear only Western style clothes and this shows that meny respondents still wonted to wear Korean costumes. Those who wanted their descendants to wear what they desire, were 50.1%(men) and 68.8% (women) and those who wanted their descendants to wear Koran costumes occasionally, were 85.8%(men) and 86.3%(women). This shows that most of respondents wanted their descendants to wear Korean costumes. In order to realize, it is necessory for us to make ourdescendants recognize the preciousness of our traditional culture and modify our Korean costumes according to their taste so that they may like wearing them.

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Condition Monitoring을 이용한 초음속 항공기 엔진의 상태예측에 관한 연구 (A Study on the Prediction of Engine Condition of Supersonic Aircraft by the Condition Monitoring Technique.)

  • 정병학;정동윤
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1996년도 제24회 추계학술대회
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    • pp.176-182
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    • 1996
  • This paper describes an empherical equation which is to predict the engine condition of the supersonic aircraft. The equation, which is a function of running time of engine and engine oil, is derived from the trend analysis of JOAP data. Qualitative analysis is carried out to make up for the weak points in the current JOAP system. Also wear debris collected from the abnormal engine is analyzed by EDS to detect the damaged parts of engine.

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호몰로지 설계를 이용한 원자로 핵연료봉 지지격자 스프링의 최적설계 (Optimization of a Nuclear Fuel Spacer Grid Spring Using Homology)

  • 이재준;송기남;박경진
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2006년도 정기 학술대회 논문집
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    • pp.828-835
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    • 2006
  • Spacer grid springs support the fuel rods in a nuclear fuel system. The spacer grid is a part of a fuel assembly. Since a spring has repeated contacts with the fuel rod, fretting wear occurs on the surface of the spring. Design is usually performed to reduce the wear. The conceptual design process for the spring is defined by using the Independence of axiomatic design and the design is carried out based on the direction that the design matrix indicates. For detailed design an optimization problem is formulated. In optimization, homologous design is employed to reduce fretting wear. The deformation of a structure is called homologous if a given geometrical relationship holds for a given number of structural points before, during, and after the deformation. In this case, the deformed shape of the spring should be the same as that of the fuel rod. 1bis condition is transformed to a function and considered as a constraint in the optimization process. The objective function is minimizing the maximum stress to allow a local plastic deformation. Optimization results show that the contact occurs in a wide range. Also, the results are verified by nonlinear finite element analysis.

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Optimal Burn-In Procedures for a System Performing Given Mission

  • Cha, Ji-Hwan
    • Journal of the Korean Data and Information Science Society
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    • 제17권3호
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    • pp.861-869
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    • 2006
  • Burn-in is a widely used method to improve the quality of products or systems after they have been produced. In this paper, the problem of determining optimal burn-in time for a system which performs given mission is considered. It is assumed that the given mission time is not a fixed constant but a random variable which follows an exponential distribution. Assuming that the underlying lifetime distribution of a system has an eventually increasing failure rate function, an upper bound for the optimal burn-in time which maximizes the probability of performing given mission is derived. The obtained result is also applied to an illustrative example.

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모(母)의 로하스 라이프스타일 태도가 친환경식자재 구매 및 건강식생활에 미치는 영향 연구 (A Study of the Effects on a Healthy Dietary Life and Purchase of Environmental-Friendly Food Materials According to Mother's LOHAS Lifestyle Attitudes)

  • 이연정
    • 한국식생활문화학회지
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    • 제25권6호
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    • pp.708-718
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    • 2010
  • This study was conducted to examine the effects of a healthy dietary life and purchase of environmental-friendly food materials according to a mother's lifestyles of health and sustainability (LOHAS) attitudes. The subjects consisted of 295 mothers. The findings are summarized as follows. The mother's LOHAS attitude index averaged 3.39 points out of 5 points. High LOHAS attitude items were "I participate actively in separating the trash collection" (4.16 points), and "I recycle dresses that I do not wear by taking them to the recycling center" (4.08 points). In contrast, LOHAS attitude items for "I do community service activity on the weekend" (2.57 points), and "I try to serve in the local community" (2.63 points) scored very low. A high LOHAS behavior index occurred for mothers who were "resource saving", whereas "social welfare" scored low. Mother's intention to purchase environmental-friendly food materials averaged 3.61 points. Mother's health dietary life attitude score averaged 3.52 points. When age, monthly income, and the environmental-friendly food materials purchase ratio of the mother was high, the health dietary life performance was high. The LOHAS attitude index of mothers had an impact on the purchase intention of environmental-friendly food materials in resource saving and environmental-friendly oriented propensity groups. The LOHAS attitude index of mothers impacted healthy dietary life in environmental-friendly, family and health oriented propensity groups.

환경요소면으로 본 의복의 인간공학적 연구 (I) - 인체동작후의 피부온 변화를 중심으로 - (A Human Engineering Study of Clothing in an Environmental Aspect (I) - Based on the Skin Temperature after Physical Exercise of Human Body -)

  • 이전숙
    • 대한가정학회지
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    • 제20권2호
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    • pp.65-71
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    • 1982
  • Comfort concept of heating and cooling between body and environment is modified by the clothing. So were can say the clothing is one of the environment. To maintain“pleasantness”, clothing must have the elements of comfort and function. This study carried out for the 1st step to describe the relation between clothing and the human body I aspect to the emvironmental elements of temperature and working part of the body. Observations of skin temperature were taken on young adults female subjects in training wear and the skin temperature was measured onto 9 points of the body while taking part in two physical exercise, with Rawing machine and Bicycle ergometer. The results obtained are as follows; 1. The skin temperature after physical exercise is lower than that after repose. 2. After physical exercise of the lower part of the body, the skin temperature is less than that after physical exercise of the upper part of the body. 3. After physical exercise of the upper part of the body, skin temperature of the lower part of the body rises a little, and vice versa.

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