• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.7
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• pp.654-661
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• 2013

The dynamic characteristics of a free-piston stirling engine(FPSE) with regard to the working frequency is investigated from theoretical and experimental studies. The FPSE is modeled as a two degree-of-freedom linear vibration system. A theoretical expression on the working frequency is derived from the instability condition for self-excitation based on the linear vibration model. A ${\gamma}$-type free-piston stirling engine is fabricated for experimental studies, and its working frequency is measured on various heater temperatures. Comparisons between the theoretical and experimental results reveal that the working frequency of the test FPSE depends on both the temperature of the compression space and the temperature difference between the expansion and compression spaces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.567-571
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• 2009

This study was conducted in order to investigate the role of working memory in word recognition. As a preliminary step in tackling this topic, word frequency and working memory load were manipulated in a naming task. The results showed that word frequency is significantly involved with the working memory load. The effects of working memory load were greater in low-frequency word processing than in high-frequency word processing. These results indicat that working memory is involved more in the processing of low-frequency words. The implications for the teaching of children at the early reading acquisition stage are discussed in this paper.

• Human Ecology Research
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• v.56 no.4
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• pp.361-375
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• 2018

This study recognizes the changes of the father's role and the importance of family mealtimes as well as examines the individual, family and social contexts surrounding the father's family mealtime. This study analyzed the trend of the father's family mealtime frequency and factors affecting them in order to explore the current conditions of their father's work and family balance through family mealtimes. Data from 492 fathers who have school aged children were collected through an online survey. The overall trend of the frequency of father's family meals showed an average of 2.4 breakfasts and an average of 3.2 dinners per week. The frequency of the father's family meals showed statistically significant differences according to the father's age, children's school age, dual income, weekly working hours, working flexibility, leaving on-time and the priority of work and family. The analysis of hierarchical linear regressions was conducted to determine factors affecting the frequency of father's family mealtime to show that the frequency of father's family mealtime was best explained by father's working conditions and perception variables. Working conditions such as working hours, leaving work on time, working flexibility were significant variables in regards to the father's family mealtime frequency. The father's perception towards parental efficacy, wife's support, and work-family priority were significant factors in regards to the father's family mealtime frequency. This study is meaningful in that it provides basic data on policy making for the compatibility of the father's work and family.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1651-1656
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• 2005

This paper describes a natural frequency analysis conducted to find out a suitable working area for a spring-manipulator system generating a large vibrating force with mechanical resonance. Large force generation is one of the functions that we hope for a robot. For example, a weeding robot is required to generate a large force, because some weeds have roots spreading deeply and tightly. The spring-manipulator system has a spring element as an end-effector, so it can be in a state of resonance with the elasticity of the spring element and the inertial characteristics of the manipulator. A force generation method utilizing the mechanical resonance has potential to produce a large force that cannot be realized by a static method. A method for calculating a natural frequency of a spring-manipulator system with the generalized inertia tensor is proposed. Then the suitable working area for the spring-manipulator system is identified based on a natural frequency analysis. If a spring-manipulator system operates in the suitable working area, it can sustain mechanical resonance and generate a large vibrating force. Moreover, it is shown that adding a mass at the tip of the manipulator expands the suitable working area.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.579-587
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• 2008

Promotion of the line no.2 in Seoul Metro was changing from the existing signaling facilities for ATS(Automatic Train Stop) vehicles to the up-to-date signaling facilities for ATO(Automatic Train Operation). But, in consequence of conducting a trial run after being equipped with the ATO signaling facilities, the matter related to mix-operation with the existing ATS signaling facilities appeared. The operation of the existing ATS signaling system in combination with the ATO signaling system has made improper working related to frequency recognition of the ATS On-board Computerized Equipment. This obstructs operation of a working ATS vehicle. That is, as barring operation of an ATS vehicle that should proceed, it may make the proceeding ATS vehicle stop suddenly and after all, it will cause safety concerns. In this paper, we designed a wayside track occupancy detector that previously prevents improper working related to frequency recognition of the ATS On-board Computerized Equipment by gripping classification and working processes of operating trains throughout transmission of local signaling information from the existing facilities, which does not need to change or replace the existing signaling facilities. Furthermore, we described general characteristics of the wayside track occupancy detector and modeled the IFC(InterFace Contrivance) device and the logical circuit recognizing signal information. Then, we made an application program of PLC(programmable Logic Computer) based on the stated model. We, in relation to data transfer method, used the frame in TCP/IP transfer mode as the standard, and we demonstrated that ATO transmission frequency is intercepted.

• Korean Journal of Agricultural Science
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• v.48 no.1
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• pp.83-93
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• 2021

The 52-hour workweek policy in Korea is a system that limits the maximum working hours per week to 52 hours including holiday work, which has been treated separately from overtime work during a week. Although this policy is designed to improve the quality of life and create jobs, it may also reduce the income of some workers. In general, it can be assumed that reduced working hours increase consumption at home. This study analyzed the effect of the 52-hour work policy on meat consumption patterns with the ordered logit model. Major factors considered in this study include working hours, income, and consumption frequency. It distinguished domestic and workplace consumption. The results show that the policy has had an impact on meat consumption patterns both at home and at work. If there is no change in income and only the working hours decrease, meat consumption in households increases. On the other hand, if both income and working hours decrease, household meat consumption decreases. Moreover, reduced working hours decrease the frequency of office happy hour and meat consumption in the workplace. However, the 52-hour workweek policy applies only to workers working more than 52 hours per week; thus, it is difficult to determine the overall effect of the policy on national meat consumption patterns.

• Journal of Biosystems Engineering
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• v.25 no.5
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• pp.351-358
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• 2000

This study was conducted to develop a speed control system of a DC motor which drove a barley seeder mounted on a combine harvester. Barley seeder mounted on a combine has been known to reduce labor and cost of barley cultivation. However, development of the seeder has been unsuccessful because the combine, a dedicated rice and barley harvester has not enough space and proper power take-off for barley seeder. To develop a barley seeder, small powered motor speed controller was required. A proximity sensor for detecting working speed of the combine and a programmable one board microprocessor was used to develope a control system. Motor parameters and motor constant, relationship between seeding rate, motor speed, groove volumes of a tested roller, torque were measured. The proximity sensor sent a frequency signal to the microprocessor. In laboratory experiments, the excitation voltage of the motor was shown not to be proportional to the size of pulse width (duty ratio). A table transforming frequency signal, that represented for working speed to proper pulse width was developed from seeding rate experiments. However, seeding rate at low frequency signal was not proportional to the working speed. Seeding rate control proportional to the frequency signal was achieved by shifting of the frequency signal.

• Korean Journal of Community Nutrition
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• v.14 no.6
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• pp.789-797
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• 2009

In order to investigate the effects of frequent eating-out and breakfast skipping of working men on body mass index and nutrients intake status, working male adults aged 20 or over were selected (n = 1883) from the data of 2001 Korea national health and nutrition survey. The subjects were divided into 4 groups according to the eating-out frequency(high: once or more daily, low: less than once daily) and breakfast eating or not. Four groups were high eating-out with breakfast eating (n = 609), high eating-out with breakfast skipping (n = 192), low eating-out with breakfast eating (n = 877), and low eating-out with breakfast skipping (n = 205). High eating-out group showed higher body mass index (BMI) than low eating-out group, but the difference of BMI was disappeared when adjusted with age, residence region and family income. However high eating-out group in case of breakfast eating, compared with the low eating-out, showed higher intakes or densities of energy, fat, fat-energy% and higher ratio of energy-fat overintake, and also showed higher mean nutritional adequacy ratio and lower ratio of nutrients intake deficiency. Calcium, iron, vitamin A and C intakes were not affected by eating-out frequency, but were lowered by breakfast skipping. Breakfast skipping also decreased intake frequency of unprocessed cereals and increased those of ramyon and carbonated and alcoholic beverages. From the results frequent eating-out with breakfast eating caused increased intakes of energy and fat, but did not cause BMI increase. Breakfast skipping, but not eating-out, had negative influences on mineral and vitamin intakes. Accordingly good eating-out as well as breakfast eating should be exceedingly emphasized at nutrition education for the working males.

• Journal of the Korean Home Economics Association
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• v.33 no.3
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• pp.85-99
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• 1995

The major purpose of this research was to investigate the causal relationships among working wives' work-family conflict, socialization of housework, and home management satisfaction. the double ABCX model of family stress and adaptation provided the theoretical framework for this study. the data were recruited from working wives who had more than one pre-school child. The respondents were asked to complete the self-administered questionnaires, and the responses of 536 working wives were used for the final analysis. basically Cronbach's α to the reliability of major variables, frequencies, percentages, means, standard deviation, pearson's correlation coefficients, and LISREL 7 program were performed to test the research model. The results of this study can be summarized as follows : 1. The frequency of work-family conflict was affected by the flexibility of work time and wives' income. 2. The severity of wok-family conflict was directly influenced by the frequency of the conflict, the flexibility of work-time, and wives' education level. 3. The variables influencing the degree of socialization of housework were found to be the frequency and the severity of work-family conflict, wives' education, and the degree of husband's participation in housework. 4. The higher degree of home management satisfaction was associated with the higher level of family member's health status, the greater degree of the flexibility of work-time, and the greater degree of husband's participation in household labor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2906-2916
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• 2010

Purpose : The purpose of this study was to identify musculoskeletal symptom and pain related working posture with operation-room workers. Methods: The subjects of this study were 73 people who were working from hospital operating-room. A questionnaire consisting of general characteristics, pain symptoms, and pain frequency was given. Objective working posture analysis was done by using REBA after recording moving images in hospital operating-rooms. Results: The result were as follows. The risk level of musculoskeletal symptom related working posture was high, and the management level was at the least 2; 'some management was required for musculoskeletal symptom'. The frequency of pain was 3~4 times/week and the severe pain were experienced from legs, neck, and shoulder. The result of relation of general characteristics and pain were significant variable with sex, age, marital status, weight, past working history, average working time(hr/day), working style, and working department. Conclusion: These results contribute to a better understanding of operation-room workers have high possibility of musculoskeletal disease and are severe musculoskeltal pain related working posture.