• 한국CDE학회논문집
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• 제16권4호
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• pp.249-259
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• 2011

In this paper we present our work on the parameterized construction of virtual drivers' reach motion to seat belt, by using motion capture data. A user can generate a new reach motion by controlling a number of parameters. We approach the problem by using multiple sets of example reach motions and learning the relation between the labeling parameters and the motion data. The work is composed of three tasks. First, we construct a motion database using multiple sets of labeled motion clips obtained by using a motion capture device. This involves removing the redundancy of each motion clip by using PCA (Principal Component Analysis), and establishing temporal correspondence among different motion clips by automatic segmentation and piecewise time warping of each clip. Next, we compute motion blending functions by learning the relation between labeling parameters (age, hip base point (HBP), and height) and the motion parameters as represented by a set of PC coefficients. During runtime, on-line motion synthesis is accomplished by evaluating the motion blending function from the user-supplied control parameters.

• 한국산업보건학회지
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• 제16권4호
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• pp.385-397
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• 2006

A high prevalence of farmer's work-related musculoskeletal disorders(MSDs) have been reported in precedent studies. To offer the basic data for reducing the melon farmer's MSDs, a questionnaire survey about MSDs symptoms and work loaded body part and video analysis by 3 checklist(REBA, RULA, OWAS) for musculoskeletal risk assessment were carried. 94 melon farmers for this questionnaire and 1 typical farm for risk assessment were participated. A total of 80.9% of the farmers reported musculoskeletal symptoms and 60.6% reported musculoskeletal symptoms over NIOSH standard. The mainly symptom body part is low back, knee and shoulders. Main risk factors in melon farm are awkward postures, heavey/frequent lifting and repetitive hand/arm motions. The high risk tasks induced by video analysis were harvesting, removing the sprouts and covering with rags. These result can be used practically for planning intervention strategy and programs to prevent farmer's MSDs.

• 산업공학
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• 제17권2호
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• pp.218-225
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• 2004

This study aims to investigate effect of external load and motion repetitiveness on perceived discomfort. An experiment was performed for measuring discomfort scores at varying conditions, in which external load, motion repetitiveness and arm posture were employed as experimental variables. The arm posture was controlled by shoulder flexion and abduction, and by elbow flexion. Fifteen healthy college-age students without history of musculoskeletal disorders voluntarily participated in the experiment. The results showed that the effect of external load, motion repetitiveness and shoulder posture on discomfort were statistically significant, but that elbow posture did not significantly affect discomfort ratings. The effect of external load was much larger than that of any other variables, and that of repetitiveness was second only to external load. Discomfort scores significantly increased linearly as the levels of external load and motion repetitiveness increased. This implies that although they were not fully reflected in the existing posture classification scheme such as OWAS, RULA, etc., the effect of external load and motion repetitiveness should be taken into consideration for precisely quantifying work load in industry. Based on regression analysis, equivalent values of external load and motion repetitiveness in terms of discomfort scores were provided, which would be useful for better understanding the degree of their effect on work load.

• 대한인간공학회지
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• 제35권5호
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• pp.413-423
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• 2016

Objective:The aims of this study are to understand the effects of task (pushing, pulling, and clockwise and counter clockwise twisting) direction on the maximal output and their grip forces and to explore the relationship between the maximal output and the grip forces. Background: Knowing the normative maximal grip force is not enough to design a good hand tool. The industrial designers should understand the required grip forces in various motions toward a specific direction to make an effective and efficient hand tool. Method: Eighteen healthy volunteers participated in the series of isometric maximal output force tests. A custom-made force measuring equipment collected the output and the grip forces for three seconds. Force measurements along the vertical, coronal and sagittal axes were randomly repeated three times. Results: The pulling was strongest and the pushing was weakest in all directions. The effect of motion on the output forces varied in different directions. The corresponding grip force increased in the order of pushing, pulling, clockwise twisting, and counter clockwise twisting in all directions. The maximal output and their grip forces were highly correlated but the relationship was affected by motion and direction. The regression coefficient was greatest in pulling and smallest in clockwise twisting. Conclusion: The effect of motion on the output forces varied in different directions. The maximal output and their grip forces were correlated but the relationship was affected by motion and direction. Application: Findings of this study can be valuable information for industrial designers to develop more productive hand tools and work stations to help preventing the musculoskeletal disorders at work.

• 대한기계학회논문집B
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• 제28권2호
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• pp.174-180
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• 2004

Failure of tube bundles due to excessive flow-induced vibrations continues to affect the performance of nuclear power plant Early experimental studies concentrated on rigid structures and later investigators dealt with elastic structures because of their importance in many engineering fields. On the other hand, much less numerical work has been carried out, because of the numerical complexity associated with the problem. Conventional approaches usually decoupled the flow solution from the structural problem. The present numerical study proposes the methodology in analyzing the fluidelastic instability occurring in tube bundles by coupling the Computational fluid Dynamics (C%) with the tube equation of motions. The motion of the structures is modeled by a spring-damper-mass system that allows transnational motion in two directions (a two-degree-of-freedom system). The fluid motion and the cylinder response are solved in an iterative way, so that the interaction between the fluid and the structure can be accounted for property. The aim of the present work is to predict the fluidelstic instability of tube bundles and the associated phenomena, such as the response of the cylinder, the unsteady lift and drag on the cylinder, the vortex shedding frequency.

• 대한인간공학회지
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• 제29권4호
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• pp.487-493
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• 2010

Work related musculoskeletal disorders (WMSDs) became a major problem since 2000 in shipbuilding industry. WMSDs are known to be resulted from awkward postures, high repetitive motions, excessive forces, mechanical stress and vibration. Korean government enacted a law to require companies to take measures to prevent musculoskeletal disorders at work. If there are more than 10 incidences of WMSDs or 5 incidences which are more than 10 percent of all workers in a company, this law requires a company to implement an ergonomics program. A few large companies in shipbuilding industry have already implemented or are in the process of implementing an ergonomics program. This paper presents a case study of an implementation of an ergonomics program in a Korean shipbuilding company. We audited the process of the ergonomics program in this shipbuilding company four times for 3 years. Based on the findings, this paper presents effects and problems of an ergonomics program and improvement measures of them. These findings will help companies which want to implement an ergonomics program in the future.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2001년도 춘계 학술대회 논문집
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• pp.31-35
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• 2001

Simulation --- The ideal tool for BPR. Work now and CASE tools are static modeling tools. Based on our own customers surveys, we have discovered that the use of process modeling tools thus far has focused on modeling the current(What-Is) state of a business. We have found that 90 percent of reengineering projects, the modeling tools of choice have been flowcharting tools. Static models offer help in understanding the overall nature of an existing process. However, static models can not really help you see the step by step motions towards completion of your goals. In static modeling, you see two pictures in time, usually taken at the current state and final state models of your reengineering project. Static models are usually not object oriented, therefore can not show facility or office layout and movement of entities and objects throughout the facility. However, this does not mean that static modeling does not have its application nor add value to the user as in a few success stories. Simulation helps the team analyze the complex aspects of the project. Many times a plan that looks good on paper might turn out entirely different when put into action. Therefore, simulation helps you look at how situations might work before actual implementation. In particular, computer simulation models help you view a reengineered condition before they are rolled-out. Items such as a lead time and resource allocation.

• Advances in robotics research
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• 제2권3호
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• pp.183-199
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• 2018

This paper presents the development of a 3D printed humanoid robotic hands of SignBot, which can perform Malaysian Sign Language (MSL). The study is considered as the first attempt to ease the means of communication between the general community and the hearing-impaired individuals in Malaysia. The signed motions performed by the developed robot in this work can be done by two hands. The designed system, unlike previously conducted work, includes a speech recognition system that can feasibly integrate with the controlling platform of the robot. Furthermore, the design of the system takes into account the grammar of the MSL which differs from that of Malay spoken language. This reduces the redundancy and makes the design more efficient and effective. The robot hands are built with detailed finger joints. Micro servo motors, controlled by Arduino Mega, are also loaded to actuate the relevant joints of selected alphabetical and numerical signs as well as phrases for emergency contexts from MSL. A database for the selected signs is developed wherein the sequential movements of the servo motor arrays are stored. The results showed that the system performed well as the selected signs can be understood by hearing-impaired individuals.

• International Journal of Quality Innovation
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• 제9권1호
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• pp.22-40
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• 2008

Unnatural working postures usually cause musculoskeletal problems for workers in work field, especially in traditional industry. Many analysis and survey methodologies have been developed to identify unnatural postures and disorder risks in workplaces. The Ovako Working Posture Analyzing System (OWAS) and Nordic Musculoskeletal Questionnaire (NMQ) are the representative methods and applied widely. This study applied the both tools to investigate the work field of a manufacturing factory of the water heater's case. We divided the manufacturing process into nine workshops, took the pictures of working motions by DV camera and analyzed the postures on OWAS. From the OW AS results, we could identify the risks level of musculoskeletal symptoms as four Action Categories (AC). And from the comparison of OWAS and NMQ results, we could provide the suggestions to improve the working methods and environment. From the results of OWAS, we found that the operators' head/neck and back were above AC3 in some workshops. If the situation continued in long period, the operators might have the risk to get musculoskeletal symptoms. From the investigation of NMQ, we also found that the percentage of aches on neck, shoulders and lower back were higher than other parts of body. The correlation between aches and jobs was more than 75%. So we provided some suggestions to improve: work rotation and adjustment of work surface/height to fit in with Ergonomics. Then the risks of musculoskeletal symptoms would be reduced.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.189-189
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• 2009

This work was focused on the dielectrophoretic force of fullerenes dispersed in liquid crystal host medium, which are investigated in the homogeneously aligned liquid crystal (NLC) cells driven by external electric field. A fullerene of 10 wt% was doped into the LC medium and its electric field induced motion was controlled by both in-plane and vertical electric field. When the electric field was applied, the fullerene start to move in direction of applied electric field. The dark, grey and white states in the proposed device can be obtained by suitable combination of the polarity of applied electric field. The w and l are the width and distance between the electrodes. The reflectance at different l was measured and was found to be increased with increasing l. The dynamical motions of fullerene particles in LC medium suggest that fullerene can be designed for electronic-paper like displays.