• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2007.10a
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• pp.19-36
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• 2007

When the trains runs at a high speed in the tunnel, passengers feel a pain in the ear that fast pressure fluctuation inside the tunnel being delivered with pressure fluctuation inside the passenger car. These phenomena are called "aural discomfort". Aural discomfort increase the passengers' uncomfort so that it is decreased a service level and serious case, it is able to damage the ear of the passenger. therefore aural discomfort must be considered the high-speed railroad tunnel cross-section design. To solve the problem of aural discomfort in a railway tunnel, some countries have standards on aural discomfort. It has been studied that different countries have different standards on aural discomfort. For that reason, the criteria of aural discomfort was reviewed through the standards of Kyungbu HSR line and different countries in this paper. And then Numerical Analysis of the Characteristics with tunnel cross-section change has been used for the selection of the optimum cross-section of Honam. The numerical analysis results were compared to field test results in order to verifying the reliability of the numerical analysis.

• Journal of The Korean Society of Integrative Medicine
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• v.12 no.2
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• pp.25-32
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• 2024

Purpose: This study utilizes big data from the 8th (2021) National Health and Nutrition Examination Survey to determine first, the relationship between chewing discomfort in the elderly and some systemic diseases and second, whether oral diseases and oral health problems are related to systemic diseases. Since this may have an impact, we aim to provide basic data to facilitate the expansion and emphasize the importance of integrated health management education. Methods: Original data from the 8th (2021) National Health and Nutrition Survey, conducted by the Korea Centers for Disease Control and Prevention, were analyzed using SPSS Version 21.0 (IBM). A complex sample frequency analysis was conducted to confirm the general and health-related characteristics of the study subjects, and a complex sample cross-analysis was conducted to determine chewing discomfort according to both general and health-related characteristics. Complex sample multiple logistic regression analysis was conducted to determine the effect on chewing discomfort. Results: In order to analyze the factors that affect chewing discomfort, the general characteristics that showed significant differences in chewing discomfort were adjusted for age, personal income, education level, basic livelihood security, high blood pressure, subjective health status, and subjective oral health. It was found that the condition had a statistically significant effect on chewing discomfort. Conclusion: The findings of this study demonstrate that high blood pressure, subjective health status, and subjective oral health status affect chewing discomfort; hence, measures such as developing and operating programs to improve national oral health are needed. We hope that our study will be used as basic data for research into chewing discomfort and systemic diseases in the elderly.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.50-57
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• 2007

Shocks are excited by impulsive forces and cause discomfort in vehicles. Current standards define means of evaluating shocks and predicting their discomfort, but the methods are based on research with a restricted range of shocks. This experimental study was designed to investigate the discomfort of seated subjects exposed to a wide range of vertical shocks. Shocks were produced from the responses of one degree-of-freedom models, with 16 natural frequencies (from 0.5 to 16 Hz) and four damping ratios (0.05 0.1, 0.2 and 0.4), to a hanning-windowed half-sine force inputs. Each type of shock was presented at five vibration dose values in the range $0.35\;ms^{-1.75}$ to $2.89\;ms^{-1.75}$. Fifteen subjects used magnitude estimation method to judge the discomfort of all shocks. The exponent in Stevens' power law, indicating the rate of growth in discomfort with shock magnitude, decreased with increasing fundamental frequency of the shocks. At all magnitudes, the equivalent comfort contours showed greatest sensitivity to shocks having fundamental frequencies in the range 4 to 12.5 Hz. At low magnitudes the variations in discomfort with the shock fundamental frequency were similar to the frequency weighting $W_b$ in BS 6841, but low frequency high magnitudes shocks produced greater discomfort than predicted by this weighting. At some frequencies, for the same unweighted vibration dose value, there were small but significant differences in discomfort caused by shocks having different damping ratios. The rate of increase in discomfort with increasing shock magnitude depends on the fundamental frequency of the shock. In consequence, the frequency-dependence of discomfort produced by vertical shocks depends on shock magnitude. For shocks of low and moderate discomfort, the current methods seem reasonable, but the response to higher magnitude shocks needs further investigation.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.265-272
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• 2001

The human arm is modeled by three rigid bodies(the upper arm, the forearm and the hand)with seven degree of freedom(three in the shoulder, two in the elbow and two in the wrist). The objective of this work is to present a method to determine the three-dimensional kinematics of the human elbow joint using a magnetic tracking device. Euler angle were used to determine the elbow flexion-extension, and the pronation-supination. The elbow motion for the various driving conditions is measured through the driving test using a simulator. Discomfort levels of elbow joint motions were obtained as discomfort functions, which were based on subjects' perceived discomfort level estimated by magnitude estimation. The results showed that the discomfort posture of elbow joint motions occurred in the driving motion.

• Journal of the Korean Society of Safety
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• v.16 no.1
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• pp.73-78
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• 2001

It has been proposed that the acceptable level of discomfort was a valid measure of postural loading. Although the number of women employees has increased at a much faster rate than men workers did and female workers are thought to be more vulnerable to musculoskeletal disorders, most previous studies dealt with perceived discomforts for joint motions focused on male subjects. This study aims to measure perceived discomfort ratings of females for static joint motions. Ten female subjects participated in the experiment measuring perceived discomforts, in which almost every possible joint motion was included and the free modulus method of the magnitude estimation was employed. The results showed that discomfort levels were dependent on the joint motions and joints, and subjective discomfort ratings of women were significantly larger than those of men.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.2
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• pp.99-104
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• 2013

With diversity of mobile services (e.g., messenger, and social network service) on smartphone, the demand of text input using a soft keyboard is increasing. However, studies on subjective and physiological responses of users for various touch locations are lacking. The present study investigated the ergonomic effects according to touch locations of a soft keyboard on smartphone. The experiment of the present study measured perceived discomfort using Borg's CR-10 scale and electromyography (EMG) on forearm (abductor pollicis longus, and extensor digitorum communis) and thumb (abductor pollicis brevis, and first dorsal interossei) muscles. Perceived discomfort was significantly varied from 0.7 (extremely weak discomfort) to 2.5 (weak discomfort) depending on touch locations. %MVC according to touch locations was only significant at abductor pollicis brevis which varied from 10% to 23%. The experimental results of the present study can be utilized in the ergonomic design of a soft keyboard.

• Journal of the Ergonomics Society of Korea
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• v.35 no.5
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• pp.439-447
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• 2016

Objective: The purpose of this study is to design a snow-removing tool using an ergonomic approach. Background: It is necessary to remove snow on the garden of a house or side street to prevent a fall hazard. When a user removes snow using a snow-removing tool, he or she experiences lots of physical discomfort. Therefore it is necessary to design a snow-removing tool to reduce a user's physical discomfort. Method: In this study, a new design for a snow-removing tool was developed considering user needs. The design prototype was compared with an existing tool through electromyography and subjective evaluation. Results: From the comparison evaluation, significant differences between the new design and the existing tool were identified in both muscle fatigue and subjective rating of discomfort. Conclusion: The result showed that the new design is better from the aspect of easing physical discomfort. Application: A new snow-removing tool can be developed using the design so that it can reduce a user's physical discomfort.

• Journal of the Ergonomics Society of Korea
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• v.13 no.2
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• pp.13-24
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• 1994

The objectives of this study are twofold : (1) to investigate musculoskeletal discomfort for sedentary workers in offices ane (2) to revise the Korean Standard for the design of office chairs in order to reduce or eliminate the physical discomfort or the office workers. Two hundred seventy-one office workers from nineteen different companies companies were selected to evaluate the musculoskeletal discomfort and indibidual features of chair design. A statistical analysis of the survey rebealed that the office currently being used had two major deficiencies such as insufficient adjustability and inappropriate design specifications in ergonomic sense. A stepwise regression analysis showed that the deficiencies on the musculoskeletal discomfort of the workers. Based on the ergonomic design pronciples, was debeloped to revise the Korean Standard for the design specifications of office chairs. An application of the methodology was made amend the design specifications of the four factors such as seat pan height, seat pan width, and seat pan inclunation. Their effects were evident in the musculoskeletal discomfort of the workers.

• IE interfaces
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• v.16 no.1
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• pp.85-93
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• 2003

The purposes of this study are to investigate perceived discomfort for static joint motions, and to propose rankings for the joint motions based on the perceived discomfort. The perceived discomfort was measured through an experiment using the free modulus method of the magnitude estimation, in which ten healthy college-age female students participated. The results showed that joints, joint motions and their levels significantly affected the perceived discomfort at $\alpha$=0.01, and that the interaction of joints and joint motion levels was also significant. Based on the experimental results, three rankings were proposed by joint and joint motions, by joints and by joint motions, which were very different from the existing ones. Especially, the proposed rankings were different from the males' published before in their order and magnitude. These rankings can be used as a valuable tool for better understanding potentially adverse effects of poor working postures in industrial sites, and as basic data for developing the postural classification scheme.

• KIEAE Journal
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• v.7 no.5
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• pp.29-34
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• 2007

Discomfort glare from windows is an important issue in window and daylighting design. This study aims to investigate the effect of luminance difference between the lower and the upper part of a large glare source. Experiments were conducted using a luminous body divided into two parts, the upper part and the lower part. The degree of discomfort glare from the luminous body was examined. The result shows that the part with lower luminance is perceived as a glare source when the part has higher luminance then the background luminance. The degree of discomfort glare was estimated for the experimental conditions, and compared to the observations. The estimation was made using two methods: one summed the glare sensation for each section, and the other used the average luminance of the whole luminous body. The result of the comparison shows that the method using the average luminance has approximate values to the observations. Consequently, the use of the average luminance was proposed for evaluation of discomfort glare from non-uniform large glare sources.