• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권7호
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• pp.3566-3582
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• 2019

In intelligent warehouse picking system, the allocation of tasks has an important influence on the efficiency of the whole system because of the large number of robots and orders. The paper proposes a method to solve the task allocation problem that multi-robot task allocation problem is transformed into transportation problem to find a collision-free task allocation scheme and then improve the capability of task processing. The task time window and the power consumption of multi-robot (driving distance) are regarded as the utility function and the maximized utility function is the objective function. Then an integer programming formulation is constructed considering the number of task assignment on an agent according to their battery consumption restriction. The problem of task allocation is solved by table working method. Finally, simulation modeling of the methods based on table working method is carried out. Results show that the method has good performance and can improve the efficiency of the task execution.

• Journal of Preventive Medicine and Public Health
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• 제26권1호
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• pp.20-36
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• 1993

Work-related low back pain is one of the major factors that cause the loss of working power especially in actively working age, therefore controlling the work-related low back pain is one of the major issues in the field of industrial safety and health. This study was performed for detecting the risk factors and proposing the efficient control program of the work-related low back pain. The subjects were male workers employed at the manufacturing industry in Pusan with longer than 6 months' working duration. The data was collected by self-reported questionnaire and interview from May 1 to October 31,1992. The contents of questionnaire were as follows:. the experience of low back pain within the recent one month, general characteristics(age, marital status, education level, religion, regular exercise), physical characteristics(height, weight), employment status(working duration, daily working hours, rest during work, satis(action fur the job), type of work and working environments(posture, forward bending, lifting and movement, satisfaction for table and chair). The result was analyzed for 608 entire respondents by case-control comparative method. The number of cases was 152 with a history of work-related low back pain, so the relative frequency of self-reported work-related low back pain was 25.0%, and the number of controls was 344 without any history of low back pain. As a result, two characteristics of the employment status(working duration, satisfaction fur the job) and all characteristics of type of work and working environments showed a statistical significance between the case and control groups(p<0.01). The Oddb ratios of these variables for Work-related low back pain were calculated. They were 7.88 for the satisfaction fur chair, 7.86 for lifting and movement,3.31 for satisfaction for table, and 2.22 fur bending forward(p<0.01). And for the multivariate logistic regression analysis confirmed that unsatisfaction for table was independent risk factor for Work-related low back pain. In summary, though this study was based upon the self-reported questionnaire and the subjective complaints, the satisfaction for chair, lifting and movement, satisfaction for table, and bending forward concerned with the type of work and working environments were considered as the main factors causing the work-related low back pain, and the work-related low back pain may be preventable by the ergonomic control of these factors.

• 복식
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• 제41권
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• pp.185-206
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• 1998

The purpose of this study was to improve productivity for maximum effects with the present equipments and staff. This study compared and analyzed the mea-sured time by using stop watch method and MTM, which was the new measuring method. The flow and results of this study were as follows: 1. This study investigated the theoretical background the efficiency for production management, and the way of productivity improvement through documentary research. 2. Setting up the standard flow on the experi-mental company production, making out a process chart and measuring the actual working hour. 3. The study measured the allowance time applying work sampling. 4. Each process of the movement analysis was filmed by video to use basic data. 5. MTM analysis was taken by choosing 10 processes from front bodice according to the basic movement of MTM. Through the results, this study exclude unneccesary movements and suggest a method for working ways. 6. Using the actual working hour measured by a stop watch calculated the pitch time and presumed the amount of daily productivity. 7. The result of the work sampling came out as 38% of allowance rate. It was 13% higher than the standard amount of woman's jacket allowance rate, which was 25%. The most influencing factor was work discussion. That was because there were commuication problem of the work way between the operator and leader. More adequate use of flow table and level passing table was needed. There were the problems that inappropriate places and sizes made the distance of movements longer and often needed more adjustment of works and surroundings. To prevent breakdowns equipments check ups were necessary before works. 8. The results of MTM analysis were as follow : the time was reduced 40% than the actual measured time by a stop watch. This was because the leveling of the operator was included in the real calculation. Also, leveling was included in MTM analysis and all the conditions were standarized. Therefore MTM method was a scientidic measuring way of establishing the standard time. The presented method of this study, suggested an ideal method eliminating unneccesary motions, and presented standardization of works. Improvement of working methods, work condition and simplifying motions in each 10 processes reduced the working time from total 656 seconds to 301 seconds. 9. The way and time of working was linked together in the MTM analysis methods. Thus data from MTM help suggest not only establishing standard time but also establishing stan-dard work. Plus it includes various ability for improvements of working ways. So it is an objective method which can be widely used in other work studies. 10. The function of a time study is to determine the amount of work produced with a given method. The work rate is used to establish the cost of labor. The wage of worker must be calculated per unit time which is deter-mined before the time study is made. This study tried to introduce the incentive rule for deciding wages according to the standard time by MTM method.

• 한국재료학회지
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• 제15권11호
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• pp.705-710
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• 2005

NIL (nanoimprint lithography) technique has demonstrated a high potential for wafer size definition of nanometer as well as micrometer size patterns. During the replication process by NIL, the stiction between the stamp and the polymer is one of major problems. This stiction problem is moi·e important in small sized patterns. An antistiction layer prevents this stiction ana insures a clean demolding process. In this paper, we were using a TCP (transfer coupled plasma) equipment and $C_4F_8$ as a precursor to make a Teflon-like antistiction layer. This antistiction layer was deposited on a 6 inch silicon wafer to have nanometer scale thicknesses. The thickness of deposited antistiction layer was measured by ellipsometry. To optimize the process factor such as table height (TH), substrate temperature (ST), working pressure (WP) and plasma power (PP), we were using a design of experimental (DOE) method. The table of full factorial arrays was set by the 4 factors and 2 levels. Using this table, experiments were organized to achieve 2 responses such as deposition rate and non-uniformity. It was investigated that the main effects and interaction effects between parameters. Deposition rate was in proportion to table height, working pressure and plasma power. Non-uniformity was in proportion to substrate temperature and working pressure. Using a response optimization, we were able to get the optimized deposition condition at desired deposition rate and an experimental deposition rate showed similar results.

• 한국생산제조학회지
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• 제8권6호
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• pp.55-63
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• 1999

The acceleration of the performance of machine tools influences the development of the semi-conductor and optical technology as the development of NC and measurement technology. Because the measurement has been done to unload condition without considering of mechanical stiffness in the case of machining center as we measure the quasi-static error of machine tools on general study people who works on the spot has many problems on the data value. Also there are no satisfiable results until now in spite of many studys about this because the deflections of the table and the shaft supporting a workpiece influence, influence the accuracy of the table and shaft supporting a workpiece influence the accuracy of the workpiece. And there is doubt about the inspection method of measured error. In this paper Therefor we will help working more accurately on the spot by measuring analyzing displaying the defoec-tion of the table and support shaft when we load on the table and the support shaft of machining center using laser interfer-ometer. Also we try to settle new conception of the measurement method and more accurate grasp of the deflection tenden-cy by verifing the tendency of the error measured through the comparison of the simulated error measured through the comparison of the simulated error using ANSYS a common finite element analysis program which is able to measure heat deformation material deformation and error resulted from this study.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.204-209
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• 1998

The acceleration of the performance of machine tools influences the development of the semi-conductor and optical technology as the development of NC and measurement technology. We can mention that a traction role of the acceleration for the development like that depends on the development of the measurement technics Stylus instrument method, STM, SEM, Laser interferometer method which are used for measuring the quasi-static error of machine tools. Because the measurement has been done to unload condition without considering of mechanical stiffness in the case of machining center as we measure the quasi-static error of machine tools on general studies, people who works on the spot has many problems on the data value. Therefor we will help working more accurately on the spot by measuring, analyzing, displaying the deflection of the table and support shaft when we load on the table and the support shaft of machining center using laser interferometer. Also we try to settle new conception of the measurement method and more accurate grasp of the deflection tendency by verifing the tendency of the error measured through the comparison of the simulated error using ANSYS, a common finite element analysis program, which is able to measure heat deformation, material deformation, and error resulted form this study.

• 대한안전경영과학회지
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• 제9권2호
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• pp.1-8
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• 2007

Safety check-up and individual education, safety status wishes to present included safety assessment table for safety management assessment system construction about unit work process in Study. Safety management assessment table gives each grades about worker of unit work process, safety check-up, education, management and identifies merits and demerits of unit work process, it is that propose safety management assessment system that can reduce accident occurrence possibility.

• 한국인구학
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• 제9권2호
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• pp.13-29
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• 1986

This study was carried out to calculate working life expectancy and its potential gains according to the degree of reduction in the specific causes of death. It sought to ascertain what potential gains in labor force longevity might be reasonably achieved through efforts to reduce mortality from injuries and poisoning, diseases of circulatory system, neoplasms and the other causes of death. The data were drawn from the three sources such as "The 1982 Causes of Death Statistics," "Abridged Life Table for Korea 1978~'79" and "The 1982 annual Report of Economically Active Population" issued by Economic Planning Board. Analytical tools used in this study were the cause-deleted life table and the Wolfbein Wool's working life table method. Partial life expectancy was adopted as an index of this study, This application will be widely used as a good demographic tool for analyzing the dynamics of labor force and causes of death. Some of the findings are summerized as follows. 1. Partial life expectancies from initial age 15, 25, and 45 respectively to terminal age 65 are 44.86, 35.59 and 17.41 year in life expectancy itself, 37.08, 32.83 and 15.21 year in working life expectancy, 7.78, 2.76 and 2.20 years in inactive life years. 2. Potential gains in working expectancy from initial age 15, 25 and 45 to terminal age 65 by the complete elimination of the specific causes of death are 1.36, 0.94 and 0.27 years in injuries and poisoning, 0.88, 0.83 and 0.54 years in diseases of circulatory system, 0.56, 0.54 and 0.37 years in neoplasms, 1.13, 1.02 and 0.58 years in the other causes of death. The relationship between degree of reduction in causes of death and potential gains in working life years is in direct proportion. The prime orders of reduction effectiveness in age groups by the causes of death are injuries and poisoning in age 15-24, the other causes of death in age 25-49 and diseases of circulatory system in age 50 and over. 3. If it were possible to reduce 25%, 50% and 75% in mortality condition 1978~'79, the average length of working life would be 38.08, 39.13 and 40.17 years in age 15, and 33.68, 34.57 and 35.44 years in age 25, and 15.67, 16.14 and 16.63 years in age 45.

• 한국정밀공학회지
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• 제32권2호
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• pp.179-184
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• 2015

In the recent field of Machining, with the improving efficiency of processing, the index table is a key unit according to the increase of parts in available processing when working with the three axes at the same time. As an essential product of MCT, the index tables effect an influence on product quality of machined parts. Therefore, it is necessary to design the shape of index table with stability, high stiffness, lightweight structure. In this study, the optimal shape of index table was proposed using by design of experiment. The maximum displacement and stress analysis were carried out by using FEM software. The optimized shape was verified by using the statistical software. The results of shape optimization were confirmed that both displacement and stress were reduced in comparison with initial model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.241-244
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• 2002

Deburring is conducted using MAF(magnetic abrasive finishing) method. Magnetic inductor is designed and manufactured to generate proper magnetic induction far deburring the burr formed in drilling SM45C. Rotational speed, table feed rate, grain size of powder and working gap are changed to investigate the effect on deburring.