• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1993년도 추계학술대회논문집
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• pp.133-144
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• 1993

Psychophysical data, in general, belong to one of the four scale categories : Nominal, Ordinal, Interval, and Ratio Scale. This paper introduces properties of the four scale categories and describes some psychophysical scales that attempt to measure subjective feeling or opinion of human. In addition, guidelines of analyzing and interpreting measured data are suggested. Some examples of analyzing and interpreting paychophysical data inappropriately are presented especially with category scales which have been used most widely in measuring subjective information.

• 한국안전학회지
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• 제27권4호
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• pp.96-100
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• 2012

Low back pain (LBP) is a major issue in modern industrialized society which is mainly caused by manual material handling (MMH) tasks. The objective of this study was to provide scientific data for establishing work standard for Korean workers throughout the laboratory experiment including some specific lifting tasks. Thirty male college students were recruited as participants. The maximum voluntary contraction (MVC), recommended weight limit (RWL), and psychophysical safety weight using Borg's CR-10 scale were studied. Results showed that the RWL was 8.4% MVC higher than the proposed psychophysical safety weight. Based on this result, it is suggested that the NIOSH lifting equation (NLE) should not be directly applied to Korean without reasonable modifications. The ratio of psychophysical safety weight to MVC was ranged from 20.1 to 26.4%. It is expected that use of the methodology in this study may provide better expectation of the work ability of Korean for reducing lower back pains caused by MMH.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1994년도 춘계공동학술대회논문집; 창원대학교; 08월 09일 Apr. 1994
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• pp.561-568
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• 1994

A man model can be used as an effective tool to design ergonomically sound products and workplaces, and subsequently evaluate them properly. For a man model to be truly useful, it must be integrated with a posture prediction model which should be capable of representing the human arm reach posture in the context of equipments and workspaces. Since the human movement possesses redundant degrees of freedom, accurate representation or prediction of human movement was known to be a difficult problem. To solve this redundancy problem, a psychophysical cost function was suggested in this study which defines a cost value for each joint movement angle. The psychophysical cost function developed integrates the psychophysical discomfort of joints and the joint range availability concept which has been used for redundant arm manipulation in robotics to predict the arm reach posture. To properly predict an arm reach posture, an arm reach posture prediction model was then developed in which a posture configuration that provides the minimum total cost is chosen. The predictivity of the psychophysical cost function was compared with that of the biomechanical cost function which is based on the minimization of joint torque. Here, the human body is regarded as a two-dimensional multi-link system which consists of four links ; trunk, upper arm, lower arm and hand. Real reach postures were photographed from the subjects and were compared to the postures predicted by the model. Results showed that the postures predicted by the psychophysical cost function closely simulated human reach postures and the predictivity was more accurate than that by the biomechanical cost function.

• 대한인간공학회지
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• 제18권1호
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• pp.1-12
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• 1999

The objective of this study was to investigate the metabolic energy consumption rate of the psychophysical Maximum Acceptable Weight of Loads (MAWLs) for different manual materials handling tasks. Lifting activities with four different lifting frequencies (2, 5, 8, 11 lifts/min) for a lifting range (from floor to 76cm height) were studied. The oxygen consumption rate and heart rate were measured or recorded while subjects were lifting their MAWLs. It was found that the relationship between MAWL and frequency can be described best by the exponential function with the R-sq value 0.9865 for this study. Psychophysical MAWL decreased from 22.38 to 7.48 kg, while the oxygen consumption rate with the MAWL increased from 717.8 to $1114.7m{\ell}-O_2/min$ as the frequency increased from 2 to 11 lifts/min. Heart rate also increased from 104.5 to 120.7 bpm. The ratio of oxygen consumption for the MAWL to the Physical Work Capacity (PWC) ranged from 28 to 43%. The MAWLs were greater than or equal to the Maximum Permissible Limits (MPLs) when the frequencies were higher than 8 lifts/min. It seems that the MAWLs by psychophysical approach when the frequencies were higher than 8 lifts/min tend to be overestimated from the viewpoint of the physiological criterion of the oxygen consumption rates. From these findings it is suggested that the NIOSH Guideline should not be directly applied to Korean without reasonable modifications.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 춘계학술대회논문집
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• pp.39-49
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• 1997

The objective of this study was to make comparison of the psychophysical MAWLs for different manual materials handling tasks. Lifting activities with four different lifting frequencies (2, 5, 8, 11 lifts/min) for one lifting range from floor to 76cm height were studied. The oxygen consumption rate and heart rate were measured or recorded while subjects were lifting their MAWLs. Psychophysical MAWL decreased from 22.38 kg to 7.48 kg, while th oxygen consumption rate with the MAWL increased from 717.8 ml/min to 1114.7 ml/min as the frequency increased from 2 to 11 Lifts/min. Heart rate also increased from 104.5 to 120.7 bpm. It was found that the relationship between MAWL and frequency can be described best by the exponentaial function with the R-sq value 0.9865 for this study. The percent ratio of oxygen consumption rate with the MAWL and PWC ranged from 28% to 43%.

• 산업경영시스템학회지
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• 제22권50호
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• pp.65-73
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• 1999

Most psychophysical studies in manual material handling (MMH) have paid more attention to two-handed MMH activities than to one-handed MMH activities. Also, studies are involved only with single MMH activities - lifting, lowering, carrying, holding, pushing or pulling. Very few studies are reported on the determination of workers' capacities for combinations of one-handed MMH activities (lifting a box, then carrying the box, and lowering the box). The objective of this study was to find the psychophysical and physiological responses of human subjects from a simulated industrial task involving one-handed and two-handed combined tasks. The capacities that were determined as the maximum acceptable weight workloads for 1 hr work period for one-handed and two-handed combined tasks - lifting a box from floor to knuckle height, carrying the box for 4.3 m, and lowering the box from knuckle to floor height - were determined psychophysically under three frequencies: six handlings per minute, one handling per minute and one handling per five minutes. In addition to maximum acceptable weight, heart rate and RPE values on wholebody, back, and arm were also measured as responses.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2008년도 추계학술대회
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• pp.143-146
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• 2008

The objectives of this study were to evaluate color sensation for yellowish natural dye fabrics using magnitude estimation to determine physical colorimetric factors significantly related to human sensibility by establishing power function in psychophysical analysis. Fourteen different yellowish fabrics dyed with natural colorants were selected as stimuli and subjective color sensations including brightness, heaviness, softness, strength, warmth, activeness, classicalness, femininity, and pleasantness for each stimulus were evaluated. As results, yellowish natural dye fabrics in general seemed to evoke feeling of brightness, femininity, and pleasantness more strongly than that of heaviness and classicalness. Most of color sensation were significantly related with more than one of physical color properties, which leads to establishing reliable power functions between them. In the power functions, these relationships could be utilized to design color-sensible natural dye textiles.

• 한국의류산업학회지
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• 제21권1호
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• pp.88-95
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• 2019

The purpose of this study was to figure out the various characteristics of the thickness sensation among elements of tactile sensation using psychophysical method. Firstly, panel screening was processed to select sensitive thickness panel using the triangle test. As a result of discriminating the paper thickness difference from 1 to 4 pieces, the female students perceived the thickness difference more sensitively than the male students (p<.05). Secondly, JND (Just Noticeable Difference) was obtained at percentage of stimulus detection rate in order to detect the degree of thickness difference by psychophysical method. It was found that the difference threshold of the entire group was about 0.125mm, with male group being about 0.178mm and female group being about 0.095mm. Thirdly, Weber's law was used to find the minimum discrimination difference between the stimuli. The experiments were conducted by increasing the paper's base thickness from 1.950mm to 1.330mm, and it was found that the difference tendency increased when the size of the basic stimulus increased. At this time, the minimum discrimination difference increased, but the Weber' fraction was not proportional to the magnitude of the stimulus. The significance of this study was that sensory evaluation was applied to research in the fields of clothing science and it seems effective to further screen and train sensitive students as material discrimination experts.

• 산업공학
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• 제17권1호
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• pp.46-55
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• 2004

Various characteristics of the object being lifted are known to affect the biomechanical, physiological, and psychophysical stresses. The object characteristics to be considered in the design process of lifting tasks are weight, shape, stiffness, and availability of handles and similar coupling devices. In this study, a prototype Polypropylene laminated bag with carrying handles was designed to decrease the physical stress of people who handle these bags. Physiological and psychophysical approaches as well as subjective ratings were applied to evaluate the effects of handles provided on the designed PP laminated bag. Statistical analysis showed that the VO2, heart rate, blood pressure, and Borg-RPE score for PP laminated fertilizer bag with carrying handles were significantly lower than those bags without handles. Moreover, Maximum Acceptable Lifting Endurance Time(MALET) measure, newly developed in this study, for bags with handles was significantly higher than those for bags without handles. It is thus recommended that the various types of bags and boxes be equipped with handles to reduce the musculoskeletal, physiological, psychophysical, and subjective perceived stresses.

• 대한인간공학회지
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• 제29권1호
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• pp.145-153
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• 2010

Activity of lifting has been a major issue in many research area related in manual materials handling tasks. However, the opposite activity of lifting, lowering, has received much less attention. It is known that 52% of all box-handling tasks were lowering in nature. The difference in stress between lifting and lowering activity is not well understood. A simple assumption that these two activities are very similar has been established and widely used. However, this simple assumption may be questionable. The objective of this study was to compare a lifting activity and a lowering activity based on the three different ergonomic approaches; (1) biomechanical, (2) physiological, (3) psychophysical approach. It was found that the stress of lowering activity was from 65% to 93%, from 87% to 97%, and from 87% to 96% according to the biomechanical, physiological, and psychophysical point of view, respectively. It is concluded from the result of this study that the stress of lowering activity is lower than that of the lifting activity. The maximum compressive force on the lumbro-sacral joint (L5/S1) was 158% and 108% respectively, for lifting and lowering activity of which the work load is the 58% of Action Limit. It is suggested that the NIOSH AL and RWL and biomechanical criteria should be reconsidered especially for the low frequency of lifting activities.