• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.91-94
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• 1995

A newly developed discrete-time control design method for impact machines is proposed. It is composed of identification and control using neural networks, where the optimal controller with saturationn and no use of velocity measurements is obtained. By computer simulation, the proposed method is demonstrated to be effective: as the training progresses, the cost function becomes smaller, the proposed control is superior to PID control tuned with Ziegler-Nichols (Z-N) parameters; robust performance with respect to uncertainty, disturbances and working time is so good.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.595-600
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• 2001

Thermal mass flow meter(TMF) and thermal mass flow controller(MFC) were used to measure and to control the mass flow rate of gases. TMF and MFC were designed for specified working pressure and gas. For the case of different working pressure and gases, the flow rate measurement accuracy decreased dramatically. In this study, a TMF and MFC was tested with three different gases and pressure range from 0.2 MPa up to 1.0 MPa. Effect of specific heat causes to increase flow measurement error as much as ratio of specific heat compared with reference gas. Changing of pressure causes to increase flow rate measurement error about -0.2% as the working pressure decreased 0.1 MPa. Response time of MFC was below 3.12 s for the case of increasing of flow rate. But the response time was increased up to 6.92 s for the case of decreasing of flow rate. When the solenoid valve was fully closed, a initial delay time of output of MFC was increased up to 1.36 s.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.1
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• pp.64-69
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• 1997

A study was conducted on the effects of ploughing on physiological responses of male and female Bali-cattle. A $2{\times}2{\times}6{\times}8$ factorial design (2 seasons, 2 sexes, 6 days and 8 consecutive time of measurements every 30 minutes) was employed. Responses during the cool/humid season were lower than hot/dry; respiration rate (RR) was 52 vs 75/min, rectal temperature(RT) was 39.1 vs $39.5^{\circ}C$ and skin temperature (ST) was 37.1 vs $37.6^{\circ}C$. Within sexes, males were less tolerant than females in that their RR (66 vs 61 breath/min), RT (39.4 vs $39.2^{\circ}C$) and ST (37.6 vs $37.1^{\circ}C$) were each higher than females during work. With increasing time, during the average 2.5 h working period gradual increases in RR, RT and ST were recorded and the overall increases of 84 breath/min, $1.9^{\circ}C$ and $13.8^{\circ}C$ respectively (p < 0.001). Packed cell volume (PCV) data indicated significant difference between sexes, time and season (p < 0.001, p < 0.05 and p < 0.001 respectively). Within time (before and after 2.5 h working) the PCV decreased from 27.4 to 25.6%.

• The Journal of Korean Physical Therapy
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• v.29 no.6
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• pp.303-306
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• 2017

Purpose: Gait variability is defined as the intrinsic fluctuations which occur during continuous gait cycles. Increased gait variability is closely associated with increased fall risk in older adults. This study investigated the influence of attention-demanding tasks on gait variability in elderly healthy adults. Methods: We recruited 15 healthy elderly adults in this study. All participants performed two cognitive tasks: a subtraction dual-task (SDT) and working memory dual-task (WMDT) during gait plus one normal gait. Using the $LEGSys^+$ system, we measured the coefficient of variation (CV %=$100{\times}$[standard deviation/mean]) for participants' stride time, stride length, and stride velocity. Results: SDT gait showed significant increment of stride time variability compared with usual gait (p<0.05), however, stride length and velocity variability did not difference between SDT gait and usual gait (p>0.05). WMDT gait showed significant increment of stride time and velocity variability compared with usual gait (p<0.05). In addition, stride time variability during WMDT gait also significantly increased compared with SDT gait (p<0.05). Conclusion: We reported that SDT and WMDT gait can induce the increment of the gait variability in elderly adults. We assume that attention demanding task based on working memory has the most influence on the interference between cognitive and gait function. Understanding the changes during dual task gait in older ages would be helpful for physical intervention strategies and improved risk assessment.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.5
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• pp.568-576
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• 2017

With an increase in the usage of LNG, there is a heightened interest about its safety aspects regarding the explosion of LNG carrier tank. The need for a cryogenic explosion-proof camera has increased. The camera has to work in cryogenic environment (below $-160^{\circ}C$) in LNG carrier. This study conducted design and heat transfer analysis of cryogenic camera to secure working time in limitation of heat source. The design with gap width of double pane windows was conducted based on simple vertical cavity model to insulate from cryogenic environment. The optimal gap width was 12.5 mm. For effective analysis considering convection within the camera, equivalent thermal conductivity method was adopted with ABAQUS. The working time of the camera predicted was over 10 h at warm-start condition. In cold-start condition, it required about 5 h of pre-warming time to work. The results of analysis were compared with the ones of the actual cryogenic test.

• Journal of Family Resource Management and Policy Review
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• v.27 no.1
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• pp.53-65
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• 2023

This study focused on Japanese families engaging in childrearing to discover changes in their daily lives, such as in the role division between husband and wife and hours spent on housework and childcare, caused by the unexpected crisis of COVID-19. An empirical analysis attempted to determine whether changes in the working environment, such as working and commuting hours, affected the role division between husband and wife, as well as housework and childcare hours spent. The data analyzed were extracted from the 2021 "3rd Survey on Changes in Lifestyle Awareness and Behavior Due to the Impact of COVID-19" conducted by the Japanese Cabinet Office. A total of 983 couples aged 20 or older, living with their spouse, having at least one child under the age of 18, and both employed were selected. The analysis results were as follows: First, the division of roles between husband and wife changed in the direction of increasing the husband's role in housework and childrearing. Second, the decrease in working and commuting hours increased the husband's role. Third, housework and childcare hours were more clearly related to changes in the working environments of husbands and wives than to changes in role division between husband and wife. In conclusion, changes in men's working and commuting hours had a greater impact on role division, as well as housework and childrearing hours in the family, than changes in women's working and commuting hours. In the future, an analysis that considers labor market factors is necessary.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.230-233
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• 1993

This paper described a relationship between motion speed and working accuracy of industrial articulated robot arms. Working accuracy of the robot arm deteriorates at high speed operation caused by a nonlinear transformation of the kinematics and the time delay of the robot arm dynamic. The deterioration of the following trajectory was expressed as a linear function of the squares of the robot arm motion speed, depending upon a posture of the robot arm and division interval of the objective trajectory.

• The Korean Journal of Health Service Management
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• v.1 no.1
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• pp.31-44
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• 2007

The purpose of this study is to shed light on the effect of work-family conflict on organizational effectiveness, focusing on the moderating effect of organizational support among married working women of health services organizations. Data were collected from 149 married working women of health services organizations located in Busan Metropolitan areas by structured self-administered questionnaire. Main results of this study is as the following: First, based on the type of work-household conflicts, namely time-based conflict(2.82 points), strain-based conflict(2.81 points) and behavior-based conflict(2.69 points), working women mainly experienced time and strain-based conflicts. The level of work-household conflicts was significantly higher among younger groups, highly educated, nurses, and regular workers. Second, the perceived organizational effectiveness found to be an above-average. Especially scores were high in the subcategories of customer orientation(3.84), followed by organizational commitment (3.42) and job satisfaction(3.19). The level of organizational effectiveness was significantly higher among older groups, medical technician and administrative job holders, day-time workers, and higher income groups. Third, the results of the regression analysis on the effects of work-household conflicts on organizational effectiveness showed that strain-based conflicts have a significant negative effect on organizational effectiveness such as job satisfaction and organizational commitment. Fourth, organizational support found to have a strong controlling effect for strain-based conflicts on organizational effectiveness. Above results imply that practical family-supportive policies for lessening the work-household conflicts is crucial for enhancing organizational effectiveness in health services organization.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.133-141
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• 2019

Crew rostering in railway operations is usually done by arranging a crew diagram in accordance with working standards every month. This study was done to identify the problems related to the creation of crew rosters in railway operations and to suggest an optimum crew rostering method that can be applied in railway operations planning. To do this, the work standards of a railway company were identified, and a genetic algorithm was used to develop an optimal roster with equal working time while considering actual working patterns. The optimization process is composed of analysis of the input data, creation of work patterns, creation of a solution, and optimization steps. To verify the method, the roster derived from the proposed process was compared with a manually created roster. The results of the study could be used to reduce the deviation of business hours when generating a roster because the standard deviation of working time is the objective function.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.1
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• pp.98-107
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• 2019

Objective: This study was carried out to examine factors influencing job stress and health promotion behavior of medical doctors, who play the important role for improving people's health. The data were collected from 340 medical doctors working in clinic and hospitals in Daegu using self-administered questionnaires over the period from July 1 to August 15, 2018. Methods: A multiple regression model was used to study the factors influencing job stress and health promotion behavior of medical doctors. Results: This study showed that average job stress level of the subjects was 3.06 out of 5 point. The medical doctors with carrying out surgery and longer working time tend to have higher job stress level compared to other groups without surgery and having short working time. And medical doctors generally do not have good health promotion behavior and average level of practice of health promotion behavior of the subjects was 2.30 out of 5. The groups with high rate of quitting job and working in hospital tend to have lower practice level of health promotion behavior compared to other groups. And it also showed that the groups with higher the job satisfaction rate and vocational aptitude tended to have the higher level of practice of health promotion behavior compared with other groups. Conclusions: Medical doctors tend to have higher job stress level, whereas they have relatively lower health promotion behavior compared with people with other jobs. Thus, strengthening of health education and counselling for medical doctors and improvement of work environment considering job's characteristics is needed. In particular, the education for job stress management and health promotion in regular continuing education program organized by medical doctors's association should be strengthened.