• Title/Summary/Keyword: Variable working conditions

Search Result 90, Processing Time 0.03 seconds

A Study on the Lubrication Characteristics of Spool Valve with Spiral Groove (스파이럴 그루브가 가공된 스풀밸브의 윤활 특성 연구)

  • Hong, Sung-Ho;Son, Sang-Ik;Kim, Kyung-Woong
    • Tribology and Lubricants
    • /
    • v.28 no.6
    • /
    • pp.303-314
    • /
    • 2012
  • In this research, spool valves with spiral grooves are suggested and their lubrication characteristics are investigated by numerical analysis. The three-dimensional flow field is obtained by solving the Navier-Stokes equations in dimensionless form, so that the performance variables such as lateral force, friction force and volume flow rate are determined. Also, the lubrication characteristics of spool valves with spiral grooves are compared with those with typical grooves under variable working conditions. It is shown that spool valves with spiral grooves can get better performance in aspect of mitigation of uneven pressure distribution surrounding spool. Moreover, it is found that the minimum distance between spool edges and grooves, the type of spiral groove, and the groove angle have noticeable effect on the lubrication characteristics.

Excavation Control of a Hydraulic Excavator with Fuzzy Logic Controller (퍼지 제어기를 이용한 유압 굴삭기의 굴삭 제어)

  • Seo, Sam-Jun;Kim, Dong-Sik;Park, Gwi-Tae
    • Proceedings of the KIEE Conference
    • /
    • 2000.07d
    • /
    • pp.2763-2765
    • /
    • 2000
  • The interactions between the excavation tool and the excavation environment are dynamic, unstructured and complex. In addition. operating modes of an excavator depend on working conditions, which makes it difficult to derive the exact mathematical model of excavator. Even after the exact mathematical model is established, it is difficult to design of a controller because the system equations are highly nonlinear and the state variable are coupled. The objective of this study is to design a fuzzy logic controller (FLC) which controls the position of excavator's attachment. This approach enables the transfer of human heuristics and expert knowledge to the controller. Expeiments are carried out to check the performance of the FLC.

  • PDF

Program development for composition of construction safety management expenses (건설안전관리비 산정 프로그램 개발)

  • Hong, Sung-Man;Lee, Jung-Gi;Park, Peom
    • Journal of the Korea Safety Management & Science
    • /
    • v.4 no.2
    • /
    • pp.23-32
    • /
    • 2002
  • The small-and-medium sized construction sites are in weak state of safety management because of the variable working environments, the lack of safety techniques and the weak economic conditions, and industrial accidents of these sites were occupied 60% of the total construction accidents. Recently, the safety engineer's number are not to be enough at the small-and-medium sized construction sites. Therefore, the safety engineer's works are addition to more and more. This paper is a development of the integrated program which using composition of construction safety management expenses. It is an management tool which helps to saving time of construction safety engineer. A method of development composition, to used Brain Storming for a place of meeting to construction safety management counselors.

A study on the characteristics of a frozen start up for a variable conductance heat pipe (가변전열 히트파이프의 저온 시동특성에 관한 연구)

  • Hong, Sung-Eun;Kang, Hwan-Kook;Cho, Kwang-Cheal
    • Proceedings of the SAREK Conference
    • /
    • 2006.06a
    • /
    • pp.339-345
    • /
    • 2006
  • This these was conducted to investigate tile characteristics of a frozen start up for a VCHP which has water as a working fluid and Nitrogen as a non-condensible gas. The tested heat pipe was made of a copper tube with the outer diameter of 12.7 mm, the length of 340 mm, and the sintered metal wick had the thickness of 0.7 mm. This experiment was conflicted under the thermal load, inclined angle and cooling conditions.

  • PDF

Study on the Impact of use of Technology on Work Environment and the Health of Workers (기술사용이 근로환경과 근로자 건강에 미치는 영향력에 대한 연구)

  • Kim, Young Sun;Rhee, Kyung Yong;Jin, Ju Hyeon;Kim, Ki-Sik
    • Journal of the Korean Society of Safety
    • /
    • v.29 no.5
    • /
    • pp.146-153
    • /
    • 2014
  • This study looks at the impact of psychological and physical factors of the working conditions on the health of workers depending on whether technology is used by such workers. The data used for the study is the third work environment survey. Out of 50,032 respondents, a total of 29,711 paid workers were used as analysis subjects. Although it was anticipated that the use of technology was a factor that hindered job autonomy and teamwork autonomy. However, the analysis results showed low levels of job autonomy and teamwork autonomy in the group that did not use technology. The study assumes a regression analysis model about work environment and work organizational practices of workspaces that have an impact on musculoskeletal complaints, stress symptoms and level of work satisfaction by controlling the social demographic variable that represents the level of individual sensitivity. As a result of the study, ergonomic risk had a significant effect on both groups that did or did not use technology with respect to stress symptoms, musculoskeletal complaints and level of work satisfaction. In particular, as workspace practices and work environment had an effect on the development of musculoskeletal complaints in the group that used machines, there is a need to improve such situation. The autonomous team work or level of job autonomy within the group that used technology may act as a risk factor to the health and welfare of workers. However, because it may also act as a buffer factor, there is a need for a change to reduce stress symptoms and increase the level of work satisfaction by improving autonomous team work and the level of job autonomy.

Actual Conditions of Smoking of Public Workers within Nonsmoking Areas (공공기관 근무자의 금연구역내 흡연실태)

  • 백윤자;정문숙;권진희
    • Korean Journal of Health Education and Promotion
    • /
    • v.17 no.2
    • /
    • pp.229-237
    • /
    • 2000
  • The purpose of this study was to be useful in working out plans for improving national health by identifying public workers' knowledge of and attitude to smoking, actual conditions of smoking within nonsmoking areas, and related factors. For the purpose, the questionnaire was carried out with 761 public officials of the division manager-level and lower working in Taegu Metropolitan City Hall in september, 1998. The results are summarized as follows; Smokers of the subject group accounted for 55.1%, and the smoking rate had a significant relation with age and religion. In view of the time when smokers started smoking, smokers who started smoking after graduation from a high school accounted for 70.6%. Smokers who smoke one pack of cigarettes per day and a cigarette to its two-thirds length was the most. In the smoking place of smokers at home, 54.9% of the smokers responded that they smoke in an outdoor space The rate of smoking in an office was 68.3% and the rate of smoking within the nonsmoking areas of other public institutions was 43.0%. The results of multiple regression analysis with the actual state of smoking within the nonsmoking area of other public institutions as an independent variable revealed that smokers who check for a nonsmoking area before smoking in the public institutions and who do not smoke in an office do not smoke within the nonsmoking areas of other public institutions. In conclusion, more smoking and health education for public workers is needed to reduce the rate of national smoking and allow people to have a good smoking attitude, and it is required to arrange an institutional system who can strictly control public workers' smoking in their offices or public places and to stress a function of surveillance and monitoring by nonsmokers.

  • PDF

Robust Optimum Design of Resonance Linear Electric Generator for Vehicle Suspension (차량 노면 진동을 이용한 공진형 선형 발전기 시스템의 강건최적설계)

  • Choi, Ji Hyun;Kim, Jin Ho;Park, Sang-Shin;Seo, TaeWon
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.23 no.4
    • /
    • pp.403-407
    • /
    • 2014
  • To use vibration energy to generate electricity, a resonance vertical linear electric generator was applied to the suspension of a vehicle in a previous paper. However, the working conditions, including mass change in the vehicle body related to the cargo on board, number of passengers and the temperature difference caused by the operating environment, can influence the permanent magnet, which is the main component of the electric generator. Therefore, a robust optimum design is required to minimize the influences from the diverse operation conditions and maximize the electromotive force of the electric generator. In this paper, a resonance linear electric generator is introduced. Vibration response analysis to find the input velocity of the electric generator and an electromagnetic transient analysis to apply changes in the performance of the permanent magnet are performed. Finally, the optimum value of each design variable is derived using a Taguchi method.

Micro structural characteristics of Bragg reflector of SMR type FBAR device deposited by RF magnetron sputtering (RF 마그네트론 스퍼터링에 의해 증착된 SMR 구조 FBAR 소자의 Bragg 반사층의 미세구조 특성에 관한 연구)

  • Park, Sung-Hyun;Lee, Sun-Beom;Lee, Neung-Heon;Shin, Young-Hwa
    • Proceedings of the KIEE Conference
    • /
    • 2005.07c
    • /
    • pp.1992-1994
    • /
    • 2005
  • In this study, Bragg reflector was formed as tungsten(W) and $SiO_2$ deposited by RF magnetron sputtering according to variable conditions of RF power and working pressure to apply to the SMR type FBAR device, one of the next generation mobile communication devices. The micro-structural properties such as a crystal orientation, roughness and micro- structure were measured by XRD, AFM and SEM and the best condition of Bragg reflector was elicited with analyzing that results of the thin films about each conditions. Finally, FBAR device was fabricated with applying the Bragg reflector was formed on the best condition and measured the resonance properties and compared other research and considered it.

  • PDF

A Study on Status Analysis and Improvement of Heavy Cargo Logistics (중량물 물류 실태 분석 및 개선 방안에 관한 연구)

  • Park, Du-Seon;Lee, Cheong-Hwan;Choi, Kyung-Hoon;Park, Gyei-Kark
    • Journal of Korea Port Economic Association
    • /
    • v.33 no.3
    • /
    • pp.35-52
    • /
    • 2017
  • Interest and demand in heavy cargo logistics is increasing and becoming more diverse as economic scales have expanded and manufacturing activity has increased. Although cargo moves via maritime and/or land transportation, there is currently insufficient research on the actual condition of heavy cargo logistics. The purpose of this study is to carry out an in-depth analysis of heavy cargo laws, systems, logistics patterns, and current transportation status. By proposing measures to solve existing problems, this study aims to make an important and ongoing contribution to the scarcely studied field of heavy cargo logistics. The result of regression analysis on the main seven factors show that transportation frequency and law/system structure have a positive effect on working conditions. Furthermore, the result of correlation analysis on the main seven factors show that the cargo weight variable is highly positively correlated with cargo size. Also, the working conditions variable is highly positively correlated with the law/system structure. Detailed proposal measures to solve existing problems are summarized as follows. First, it is necessary to establish a clear concept of heavy cargo as numerous existing definitions differ. Second, laws and provisions relating to maritime and land transportation of heavy cargo need to be established and consolidated as current applicable legislation is insufficient. Third, the classification system for heavy cargo transportation needs improvement. Fourth, it is necessary to improve transportation performance statistics and the aggregate criteria system. Finally, the management system of heavy cargo also needs improvement.

A Study on the Working Environment Recognition and the Caracter Disposition of Nurse Aides (간호조무사의 근무환경인식과 성격성향에 관한 연구)

  • Lee Sun Yi
    • Journal of Korean Public Health Nursing
    • /
    • v.4 no.1
    • /
    • pp.57-74
    • /
    • 1990
  • As the whole world took on the tendency to be highly industrialized, it became necessary for each field of occupation to require professional man power. Especially, since the World War n, the participation of woman power in economic activities has been continually increasing. In our country also, because of the rapid economic growth, change in the way of thinking of women as well as their participation in economic activities are increasing. Thus, woman power is being utilized in various occupational fields from simple physical labor to those that require high-professional skill. Also, continued economic development policies, by setting the establishment of welfare society as the ideology to be fulfilled, brought expansion of medical facilities in the field of public health and increase in man power in that field. As for the nursing specialists, more than 6000 have been being produced per year and as of the end of 1988, the total number of nursing specialists, reached 123, 115. Therefore, this study is done to recognize the professional knowledge and ability of nursing specialists, who take up $40\%$ of the total public-health related man power in our country, through evaluating their working environment and their disposition of character. This study, which was done from September 18th to September 30th 1989, took on the method of using formed questionnaires that had been amended and supplemented during two preparatory investigations, 322 of such questionnaires were used as an analytical material. In the formation of questionnaires, 12 questions were related to the working environment, and 26 in fortotal were related to the disposition of character, 5 for wise-disposition, 11 for activedisposition and 10 for open-disposition. The measuring method, which used 5-point-standard, allowed 5 points for affirmative recognition of the working environment, also 5 points for showing wise, active and open disposition of character and only point in opposite cases. Collected materials were analyzed, through an electronic calculation, into the average value, the standard deflection percentage, pearson corelative number and stepwise multiple regression. Summarizing the results from this study is as follows: 1. It was shown that the nursing specialists with the average of 3.07 have affirmative recognition of their working environment. The questions which drew most affirmative reaction were those concerning finance-management system such as hand, the questions that received negative reaction were those concerning communication method with the average of 2.49. Such reaction seems to have resulted from the cramming regulation by the superior authorities. Concerning the recognition of working environment in relation to employment conditions, more affirmative recognition is shown with the average of 3.14. at hospitals where injection job is not performed. The nursing specialists working at regular hospitals show more affirmative recognition than those at general hospitals, the averages being respectiely 3.16 and 3.03. 2. As for the disposition of character of the nursing specialists, active-disposition was highest with the average of 3.38, next was wise-disposition with 3.20 and the lowest was open-diposition with 2.98. Variable-wise disposition of character shows that wise-disposition and academic background are beneficially correlated by 0.12. Ative-disposition and open-disposition show correlation to the office term by respectively 0.16 and 0.21. In other words. better academic background leads to higher wise-disposition and more - experience results in higher active and open disposition. Also, the class that performs the injection job, in relation to the working environment, might cause change in the self-conceit that identify those in that class with the nurses; however, as far as professional judgment and action, in dealing with nursing job, being wise, active and open is concerned, not much effect is made. 3. The relation between the recognition of the working environment and the disposition of character is that more afirmative recognition- a nursing specialist has about her working environment, the higher the active-disposition becomes by 0.13. The degrees of the relation between recongnition of environment and wise and open dispositions show respectively 0.06 and -0.06 and -0.06. That is to say that when having more affirmative recognition of the working environment, a nursing specialist shows wise but closed disposition of character. This, howerver, didn't mean much statistically. When observing the results mentioned above, it is conspicuous that the nursing specialists, working as substitutes for the nurse at medical institutions of various sizes, get the feeling of being somewhat equal to the nurses and to some extent, fulfill their desire to accomplish their ego; however, as far as professional ability expansion if concerned. they lack wise and open dispositions. Therefore, considiering upon the results of this study, in medical institutions where the work of nursing specialists is regaded equal to that of the nurses, as a medical member who deals with human lives, it is desirable to make the nursing specialists work under the supervision of the nurses and to offer them continuous education to strengthen and improve their natural dispositions.

  • PDF