• 대한가정학회지
• /
• 제36권2호
• /
• pp.161-173
• /
• 1998

This study investigates why the Married Female Production Workers(MFPW) participate in their work and what is work load they take. This study uses an ecosystems approaches in order to explain the labor participation of the MFPW and their work load. MFPW participate in their work because of the labor markets need and economic need of their household rather than their personal choice. Due to the long working hours, low wage and bad labor conditions of MFPW's job, they suffer more severe work load both at the fob and at home than any other occupational groups.

• 한국산림과학회지
• /
• 제87권2호
• /
• pp.121-130
• /
• 1998

별도작업에서 작업원의 작업강도를 파악하기 위하여, 체인톱을 이용한 낙엽송 간벌작업에서 작업시간과 작업량을 조사하였으며, 작업시 심박수의 변화를 조사하였다. 또한, 작업원의 최대 작업수행 능력을 평가하기 위하여 최대산소섭취량을 조사하였다. 1일 실작업시간은 6시간 6분으로 오전작업시간이 약 3시간 12분, 오후가 2시간 54분으로 나타났고, 전체작업시간 중 실작업시간의 약 90% 정도를 차지하는 것으로 나타났으며, 실작업시간 중 요소작업 의 시간비율은 이동(Movement)의 비율이 평균 26.3%로 가장 큰 값을 보였다. 작업원의 작업량을 분석하기 위하며 시간당 벌목재적을 조사한 결과 평균 $2.62m^3/hr$로 나타났다. 작업원의 작업능력을 평가하기 위하여 최대산소섭취량을 분석한 결과, 평균 $2.42{\ell}/min$($46.5m{\ell}/kg/min$)으로 나타났으며, 작업시 심박수를 바탕으로 체인톱을 이용한 낙엽송 간벌작업 중 실동시간의 작업강도를 분석한 결과, 실동시간의 심박수 증가율은 평균 93.2%로 나타났고, 작업강도지수는 평균41.9%로 나타났다.

• Tribology and Lubricants
• /
• 제20권1호
• /
• pp.21-26
• /
• 2004

The average frictional coefficient was used generally to analyze the working process of the lubricated machine parts. But it is difficult of taking the correct frictional coefficient because the average frictional coefficient of it is progressed always unstably with a large amplitude on working condition. If the correct analysis of frictional coefficient on working condition for the lubricated machine parts can be possible, it can be effect on condition diagnosis of lubricated machine system. This study was carried out to get the optimum working condition of the hydraulic actuator parts using statistical techniques. From this result, it has the lowest friction coefficient in case of applied load of 3 kg and sliding speed of 120 mm/sec.

• Geomechanics and Engineering
• /
• 제24권3호
• /
• pp.227-235
• /
• 2021

A criterion and a method for solving a problem on the prevention of mine working fracture under the action of tectonic and gravitational forces are offered. Based on minimal criterion, theoretical analysis of the definition of the optimal shape of working in the rock mass weakened by arbitrarily located rectilinear cracks was carried out. A closed system of algebraic equations allowing to minimize the stress state and stress intensity factors depending on mechanical and geometrical characteristics of the rock, is constructed. The relation between the shape of the working and the stress intensity factors and also location and sizes of the cracks is obtained. The found optimal shape of working increases load-bearing capacity of the rock.

• 인지과학
• /
• 제21권2호
• /
• pp.359-386
• /
• 2010

본 연구는 공간작업기억과 비공간작업기억의 유지 처리에 대한 영역특수모형과 처리특수모형을 검증하고자 수행한 사건유관 fMRI 연구이다. 지연반응과제에서 얼굴자극을 표적자극으로 사용하고 표적자극의 수를 달리하여 기억부하를 조작하였으며 일정한 지연기간 후 위치 및 얼굴 재인판단을 요구하였는데, 지연 동안 정보유형(위치와 얼굴)이 기억부하효과의 신경상관물에 미치는 영향을 뇌영상 처리로 분석하였다. 독립변인은 정보유형(자극영역)과 기억부하(표적자극의 수)로서, 정보유형변인은 얼굴작업기억(비공간작업기억) 및 공간작업기억의 두 수준, 기억부하변인은 표적자극이 1개인 조건(저부하)과 3개인 조건(고부하)이었다. 행동수행 분석 결과, 재인정확도에 있어 얼굴작업기억과 공간작업기억 간에는 차이가 없었으며 두 작업기억 모두에서 동등한 정도의 기억부하효과가 확인되었다. 뇌 영상분석 결과, 유지단계에서 전전두피질의 하측 및 중/상측영역이 모두 얼굴작업기억과 공간작업기억 양자와 관련되고 특히 VLPFC가 두 작업기억에 공통적으로 관련된다는 것이 밝혀졌는데, 이러한 결과는 처리성분에 따른 전전두피질의 기능적 전문화를 주장하는 처리특수모형에 더 잘 부합된다.

• 해양환경안전학회지
• /
• 제29권7호
• /
• pp.950-957
• /
• 2023

선박이 부두에 안전하게 계류 및 예인하기 위해서는 관련 국제규정에 부합하는 설계를 해야 한다. 그러나 현재까지도 일부 소형 조선소 및 설계 회사에서는 그 내용을 정확히 숙지하지 못하고 있는 경우가 많다. 따라서 본 논문에서는 예인 및 계류설비에 관한 국제규정을 살펴보고, 최신 발효된 MEG4(Mooring equipment guideline 4) 기준에 만족하는 대표적인 계류 의장품인 볼라드(Bollard)와 쵸크(Chock)를 개발하고자 한다. 볼라드는 계류 밧줄을 선체에 고박하기 위한 의장품이며, 일반적으로 2개의 기둥으로, 대부분은 8자 매듭 형태로 사용하고 있다. 쵸크는 선외에서 선내로 들어오는 계류 밧줄의 방향을 전환하고, 밧줄의 손상을 방지하기 위하여 곡률을 갖는 주물방식으로 제작한다. 이 두 가지 계류 의장품은 선박의 선수와 선미, 중앙부 측면에서 많이 사용되고 있다. 최근 컨테이너선 및 LNG 운반선의 크기 증가로 인하여, 계류 밧줄 하중이 증가하고 있으며, 계류 의장품도 안전사용하중(Safe working load)이 변경되어야 한다. 본 연구에서는 유한요소해석 모델링을 통한 허용응력 평가법 결과를 정리하고, 분석하였다. 추가적으로 비선형 붕괴 거동 평가를 통하여, 안전사용하중 결정에 대한 검증을 수행하였고, 탄성영역 내 설계가 되었음을 확인하였다. 연구에서 제안하는 평가법 및 기준, 그리고 해석절차는 향후 유사 의장품 개발 시 참조가 가능하다.

• 한국기계가공학회지
• /
• 제20권5호
• /
• pp.111-120
• /
• 2021

A tractor is an agricultural machine that performs farm work, such as cultivation, soil preparation, loading, bailing, and transporting, through attached working implements. Farm work must be carried out on time per the growing season of crops. As a result, the reliability of a tractor's transmission is vital. Ideally, the transmission's design should reflect the actual load during agricultural work; however, configuring such a measurement system is time- and cost-intensive. The design and analysis of a transmission are, therefore, mainly performed by empirical methods. In this study, a tractor with a measurement system was used to measure the actual working load in the field. Its hydro-mechanical transmission was then analyzed using the measured load. It was found that the velocity factor, load distribution factor, lubrication factor, roughness factor, relative notch sensitivity factor, and life factor affect the gear strength of the transmission. Also, loading conditions have a significant influence on the reliability of the transmission. It is believed that transmission reliability can be enhanced by analyzing the actual load on the transmission, as performed in this study.

• 비파괴검사학회지
• /
• 제32권6호
• /
• pp.637-647
• /
• 2012

Bridges are ones of fundamental facilities for roads which become social overhead capital facilities and they are designed to get safety in their life cycles. However as time passes, bridge can be damaged by changes of external force and traffic environments. Therefore, a bridge should be repaired and maintained for extending its life cycle. The working load on a bridge is one of the most important factors for safety, it should be calculated accurately. The most important load among working loads is live load by a vehicle. Thus, the travel characteristics and weight of vehicle can be useful for bridge maintenance if they were estimated with high reliability. In this study, a B-WIM system in which the bridge is used for a scale have been developed for measuring the vehicle loads without the vehicle stop. The vehicle loads can be estimated by the developed B-WIM system with the reaction responses from the supporting points. The algorithm of developed B-WIM system have been verified by numerical analysis.

• 대한산업공학회지
• /
• 제28권2호
• /
• pp.223-231
• /
• 2002

Recently, work-related musculoskeletal disorders(WMSDs) have rapidly increased and have been a major issue in the field of industrial safety. Of several physical risk factors for WMSDs, which include postures, vibration, repetitive work, speed or acceleration of movements, etc., awkward postures have been known as one of the major causes of WMSDs. For reducing the potential for injury as a result of postures, cost effective quantification of the magnitude for physical exposure to poor working postures is important and needed. To do this, several postural classification schemes have been developed and used in industrial sites. It is known that perceived discomfort for joint motions and muscle strength for females were much less than those for males. However, the existing postural classification schemes were developed without considering these gender effects. This study aims to develop a new postural classification scheme for female workers, based on the perceived discomfort for joint motions. The result showed that there was significant difference between the schemes for female and male. It was also found that when compared with OWAS, RULA and REBA, postural load was quantified more precisely with the developed scheme. It is recommended that different schemes according to gender of workers involved in work be used in order to accurately evaluate postural load of work postures.

• Structural Engineering and Mechanics
• /
• 제17권3_4호
• /
• pp.291-302
• /
• 2004

In this paper, load monitoring technologies using U-shape Magnetoelastic (EM or ME) sensors have been exploited systemically for the first time. The steel rod to be tested is the Japan 7 mm piano steel rod. The load dependence of the magnetic properties of the piano steel rod was manifested. Two experimental designs of U-shape magnetoelastic sensors were introduced, one with double pick-up concentric coils wound on the rod to be tested, the other with pick-up coil on one yoke foot. The former design is used to derive the correlation of the relative permeability with elastic tension, while the latter is aimed to reflect the stress induced magnetic flux variation along the magnetic circuit. Magnetostatic simulations provide interpretations for the yoke foot sensing technology. Tests with double pick-up coils indicate that under proper working points (primary voltages), the relative permeability varies linearly with the axial load for the Japan 7 mm piano steel rod. Tests with pick-up coil on the yoke foot show that the integrated sensing voltage changes quadratically with the load, and error is more acceptable when the working point is high enough.