• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.948-954
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• 2008

Now, but task for stringing trolley wire is worked manually by a measurement of dip, we need to development the automatic control system for a safety and effective tasks. In this paper, in works of stringing trolley wire by a mobile of robot, a method is proposed tension control for the stringing trolley wire. On the basics of a wire model with hard nonlinear, ac servo motor model for torque generating and stringing wire tension, the tension control scheme is design and implemented with a detected wire tension by a load cell. We experimentally show that the performance of the tension response are satisfactory to regulator tension. The proposed system is simulated and experimented, results is verified the utilities.

• Computational Structural Engineering
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• v.6 no.1
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• pp.77-89
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• 1993

Current Bridge foundation design is based on Working Stress Design(WSD), but Load Factor Based on Optimum Reliability(LFBOR) design method is more rational than the WSD. For this reason, this study proposes a reliability based design criteria for the bridge foundation, which is most common type of bridge foundation(Shallow, Pile and Caission), and also proposes the theoretical basis of nominal safety factors of stability analysis by introducing the reliability theory. The limit state equations of stability analysis of bridge foundation and the uncertainty measuring algorithms of each equation are also derived by Cornell's MFOSM(Mean First Order 2nd Moment Methods)using the stability analysis fourmula Highway Bridge Design Codes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.806-809
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• 1996

The present development relates to an apparatus for loading or unloading a workpiece, and more particularly, to an apparatus for loading or unloading a workpiece from a press die or supplier An apparatus for loading or unloading a workpiece has been installed in a press in order to load or unload a workpiece from a press die. There has been known such a loading or unloading apparatus as the apparatus can feed a workpiece in not only the horizontal direction but also in the vortical direction. Press working system in automotive factories are now switching over to a transfer press work ing system. The current problem to be sieved immediately is to automate the existing manual press lines for the manpower saving and speedy production. “Automation system for press line”has just been developed to meet the above trend. The loader and unloader are development under the design concept for high performance, easy control and operational safety to meet the more extensive.

• Journal of the Ergonomics Society of Korea
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• v.25 no.4
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• pp.1-7
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• 2006

The purpose of this study is to develop an efficient algorithm for the management of the shift schedule in nuclear power plants in consideration with the ergonomic criteria and the regulatory codes. The ergonomic criteria considered are the work hours, overtime-work frequency and working time, start and finishing time of works, allocation of rest times and duty-offs, rotating of shifts, etc. to comply with the regulations such as the Labor Standard Act, the ILO Convention No. 171, 178, "the detailed content of a periodic safety review," enforcement regulations 19-2 of the Atomic Energy Act. The developed algorithm for the shift schedule program adopts a heuristic method to minimize the difference the workload for shift workers in nuclear power plants.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.5
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• pp.107-115
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• 2008

In this research, it has been developed the tongs mechanism by a friction force for curbstone working. This tongs apparatus was farmed to grip and rotate the rectangular curbstone. Specification of this tongs apparatus has been determined by considering a loading weight and reversal load preventing reversal of 1.5 ton excavator. And, specification of the linear actuator has been determined with considering mechanical structure and the operation power demanded by the grip pad friction of tongs apparatus. The safety of the part has been examined from the 3D numerical simulation of the tongs apparatus. The operation system has been arranged to grip and rotate curbstone by on-off switching. The prototype has been established to carry out experiment after installing 1.5 ton excavator.

• Journal of the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.127-132
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• 2005

The purpose of this study is to compare representative posture classification schemes of OWAS, RULA and REBA in terms of correctness for postural load. The comparison was based on the evaluation results by the three methods for 224 working postures sampled from steel, electronics, automotive, and chemical industries. The results showed that OWAS and REBA generally underestimated postural stress than RULA irrespective of industry type, work performed and whether or not leg posture is balanced. While about $71\%\;and\;73\%$ of the 224 posture were evaluated with the action category/level 1 or 2 by OWAS and REBA respectively, about $60\%$ of the postures were classified into the action level of 3 or 4 by RULA. The coincidence rate of postural stress category between OWAS and RULA was just $33.5\%$, while the rate between RULA and REBA was $46.0\%$. It is concluded from the findings of this study and the previous research that compared to OWAS and REBA, RULA more precisely evaluates postural stress.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.438-439
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• 2006

Porcelain insulators have generally been used in Korea to insulate a transmission line from the tower, and a highly polymerized compound polymer insulator which has superior stain proof characteristics, has also been used widely. Currently, a worker rides on the suspension insulator string for installation on towers and conductors but in case of polymer insulators, this will pollute and scratch the housing result in durability reduction by deterioration and corona. This study developed a high strength aluminum compound metal lauder designed to work on polymer insulators without riding, and a clamp type connecting device and safety gear for easy installation on the tower and conductor. These polymer insulator work device can be used for 154kV and 345kV polymer insulators through a strength and load test to secure safety. This paper presents field usage.

• Journal of the Ergonomics Society of Korea
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• v.29 no.2
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• pp.211-216
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• 2010

Fire service personnel and ambulance paramedics suffer musculoskeletal disorders as they lift and carry patients while performing Emergency Medical Services (EMS). The objective of the current study was performed to examine the association between working environment and musculoskeletal disorders of 119 paramedics and to analysis the EMS activities for them through basic survey (including task characteristics, risk factors, symptoms and illnesses). Observational job analysis of EMS activities indicated the squatting posture during first-aid performed on floor and the abrupt use of force during carrying heavy load including stretcher with patients on as hazard factors, and excessive low back twisting and bending during stairway transfer was observed. In addition, work-physiological assessment revealed various but rather high lumbar muscle usage rate among the study subjects, being 14.6~32.8% compared with Maximum Voluntary Contraction (MVC) during patients transfer work. Resting heart rate showed 65/min, on the other hand, heart rate on mobilization indicated maximum 124~156/min. Therefore, the results of analysis to the EMS activities, rescuer activities and medical tasks were accompanied with high possibility of accident and musculoskeletal disorders. Also, EMS activities indicated high muscle fatigue and energy consumption, and accumulated muscle fatigue with during continued work.

• Steel and Composite Structures
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• v.37 no.5
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• pp.517-532
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• 2020

This paper firstly developed a new type of Double Skin Composite (DSC) beams using novel enhanced C-channels (ECs). The shear behaviour of novel ECs was firstly studied through two push-out tests. Eleven full-scale DSC beams with ECs (DSCB-ECs) were tested under four-point loading to study their ultimate strength behaviours, and the studied parameters were thickness of steel faceplate, spacing of ECs, shear span, and strength of concrete core. Test results showed that all the DSCB-ECs failed in flexure-governed mode, which confirmed the effective bonding of ECs. The working mechanisms of DSCB-ECs with different parameters were reported, analysed and discussed. The load-deflection (or strain) behaviour of DSCB-ECs were also detailed reported. The effects of studied parameters on ultimate strength behaviour of DSCB-ECs have been discussed and analysed. Including the experimental studies, this paper also developed theoretical models to predict the initial stiffness, elastic stiffness, cracking, yielding, and ultimate loads of DSCB-ECs. Validations of predictions against 11 test results proved the reasonable estimations of the developed theoretical models on those stiffness and strength indexes. Finally, conclusions were given based on these tests and analysis.

• Steel and Composite Structures
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• v.38 no.5
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• pp.599-615
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• 2021

The ultimate strength behaviour of sandwich composite beams with J-hooks and normal weight concrete (SCSSBJNs) are studied through two-point loading tests on ten full-scale SCSSBJNs. The test results show that the SCSSBJN with different parameters under two-point loads exhibits three types of failure modes, i.e., flexure, shear, and combined shear and flexure mode. SCSSBJN failed in different failure modes exhibits different load-deflection behaviours, and the main difference of these three types of behaviours exist in their last working stages. The influences of thickness of steel faceplate, shear span ratio, concrete core strength, and spacing of J-hooks on structural behaviours of SCSSBJN are discussed and analysed. These test results show that the failure mode of SCSSBJN was sensitive to the thickness of steel faceplate, shear span ratio, and concrete core strength. Theoretical models are developed to estimate the cracking, yielding, and ultimate bending resistance of SCSSBJN as well as its transverse cross-sectional shear resistance. The validations of predictions by these theoretical models proved that they are capable of estimating strengths of novel SCSSBJNs.