• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2012년도 추계학술논문요약집
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• pp.175-176
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• 2012

• 한국안전학회지
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• 제32권1호
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• pp.90-97
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• 2017

Overhead cranes are the most widely used and have been identified as one of the main causes of fatal accidents. Although structural, mechanical and electrical safety standards for overhead cranes have been established to some extent, ergonomic standards related to crane controllers are rarely established. As a result, many crane accidents are reported to be caused by operator's error. To investigate the actual use of crane controllers in the industrial field, we surveyed 82 overhead cranes in 15 workplace and interviewed workers operating them. This study has presented the ergonomic problems related to the crane controllers in the field. As a result of investigation, it was found that the direction control signs, the sign language, and the button layout on the pendant switches and remote controllers are not standardized, which can cause a human error. To reduce human errors in overhead crane operation, ergonomic standards for controllers should be reflected on the government legislation or standards.

• 한국정밀공학회지
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• 제22권4호
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• pp.128-135
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• 2005

Overhead crane systems consist of trolley, girder, rope, objects, trolley motor, girder motor, and hoist motor. The dynamic system of these systems becomes a nonlinear state equations. These equations are obtained by the nonlinear equations of motion which are derived from transfer functions of driving motors and equations of motion for objects. From these state equations, Lyapunov functions of overhead crane systems are derived from integral method. These functions secure stability of autonomous overhead crane systems. Also constraint equations of driving motors of trolley, girder, and hoist are derived from these functions. From the results of computer simulation, it is founded that overhead crane systems is secure.

• 한국정밀공학회지
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• 제30권7호
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• pp.717-724
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• 2013

Industrial cranes are indispensable equipment in heavy industry. However, unwanted vibrations in cranes often cause accidents. Input shaping is widely accepted as a useful tool for removing residual vibration in cranes. A unity magnitude zero vibration (UMZV) input shaper is often used for cranes driven by on-off-type motors. However, although a UMZV input shaper minimizes residual vibration, the input shaper cannot prevent the crane from moving slightly further than expected from the original command. This paper describes an improved method of input shaping that can compensate for position inaccuracies, as well as remove the residual vibration of cranes. Experiments were performed to validate the proposed input-shaping method, illustrated through numerical simulations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.395-398
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• 1996

In this study, when the nonlinear overhead crane which allows simultaneously travel and traverse motion moves a desired transport route, the object suspended the end of rope does undesirable swing motion. Nonlinear overhead crane pertubes in the vicinity of an operating point, therefore the nonlinear overhead crane is modified to linear overhead crane for the operating point. The linear overhead crane was controlled to swing angles of the object by the ratio of torque inputs to motors of the girder and the trolley. As a basis for the result of the linear overhead crane, the nonlinear overhead crane was controlled swing angles of the object and positions of the overhead crane without collision with environmental equipment by partial state feedback control.

• 한국산업보건학회지
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• 제25권3호
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• pp.301-311
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• 2015

Objectives: Operators of overhead traveling crane in a ship assembly factory perform work to transmit large vessel blocks to an appropriate working process. Hazardous matters such as metal dusts, carbon monoxide, carbon dioxide, ozone, loud noise and fine particles are generated by variable working activities in the factory. The operators could be exposed to the hazardous matters during the work. In particular, welding fumes comprised of ultra fine particles and heavy metals is extremely hazardous for humans when exposing a pulmonary through respiratory pathway. Occupational lung diseases related to welding fumes are increasingly on an upward tendency. Therefore, the objective of this study is to assess properly unknown occupational exposure to the welding fumes among the operators. Methods: This study intended to clearly determine an equivalence check whether or not chemical constituents and composition of the dusts, which existed in the driver's cab, matched up with generally known welding fumes. Furthermore, computational fluid dynamics program(CFD) was used to identify a ventilation assessment in respect of a contamination distribution of welding fumes in the air. The operators were investigated to assess personal exposure levels of welding fumes and respirable particulate. Results: The dust in an operation room were the same constituents and composition as welding fumes. Welding fumes, which caused by the welding in a floor of the factory, arose with an ascending air current up to a roof and then stayed for a long time. They were considered to be exposed to the welding fumes in the operation room. The personal exposure levels of welding fumes and respirable particulate were 0.159(n=8, range=0.073-0.410) $mg/m^3$ and 0.138(n=8, range=0.087-0.178) $mg/m^3$, respectively. They were lower than a threshold limit value level($5mg/m^3$) of welding fumes. Conclusions: These findings indicate that an occupational exposure to welding fumes can exist among the operators. Consequently, we need to be keeping the operators under a constant assessment in the operator process of overhead traveling crane.

• 대한인간공학회지
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• 제26권2호
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• pp.45-59
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• 2007

The operating tasks of overhead crane have caused undue stress to the operators from physical, mental, and environmental workload. Existing workload assessment models for musculoskeletal disorders such as OWAS, RULA, and QEC have limited applicability to the crane operating tasks because they focus mainly on physical factors and do not consider the relative importance of each factor. The present study was to develop a workload assessment model customized to overhead crane operation, following a systematic process: (1) analyzing task characteristics, (2) selecting workload factors, (3) developing assessment methods, (4) establishing action levels, and (5) computerizing the assessment model. Based on literature review, worksite survey, and focus group interview, 4 physical factors (awkward posture, static posture, repetitive motion, and excessive force), 6 mental factors (visual demand, auditory demand, task complexity and difficulty, time urgency, work schedule related stress, and safety related stress), and 4 environmental factors (noise, vibration, dust, and temperature) were selected and their rating scales and relative weights were determined. Then, based on the workload assessment results of 8 overhead cranes operated at different workplaces, the action levels of each factor category were established. Finally, the crane operation assessment model was computerized for effective analysis and report preparation. The present approach is applicable to develop a customized workload assessment model for an operating task under consideration.

• 한국항해항만학회지
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• 제42권1호
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• pp.47-56
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• 2018

초대형선박의 등장으로 컨테이너 터미널 생산성의 한계에 직면하고 있으며 이를 해결하기 위한 새로운 개념의 터미널시스템들이 제안되고 있다. 본 논문에서는 개념설계 중인 레일기반 컨테이너 이송시스템을 대상으로 연구한다. 이는 레일 위를 움직이는 무인반송차인 플랫카와 천장형 레일을 따라 움직이는 셔틀크레인으로 구성된 시스템이다. 자동화된 컨테이너 터미널에서 컨테이너 수송 기능을 담당하는 무인반송차의 운영 시 교착과 같은 병목현상은 오랫동안 중요한 문제로 잘 알려져 있다. 따라서 초대형 선박과 같이 대량의 컨테이너 취급하는 신개념의 레일기반 컨테이너 이송시스템에서 발생 가능한 교착 현상을 정의하고 해결방안에 대해 논한다. 교착 현상은 이종장비 간 교착과 플랫카 간 교착문제로 구분하여 소개한다. 본 연구는 시뮬레이션 접근법을 사용하여 레일기반 컨테이너 시스템 모델을 개발한다. 개발된 시뮬레이션 모델의 실행을 통하여 수송구간에서 발생 가능한 교착 상태를 확인하고 이를 해소하기 위한 교착 회피 규칙을 개발한다. 시뮬레이션 실험을 통하여 교착발생 빈도를 기준으로 교착 회피 규칙들의 성능을 비교한다.