• 말소리와 음성과학
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• 제10권3호
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• pp.1-8
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• 2018

The vowel /o/ in Seoul Korean has been undergoing a sound change by altering the acoustic weighting of F2 and F1. Studies documented that this on-going change redefined the nature of a /o/-/u/ contrast as F2 differences rather than as F1 differences. The current study examined two cognitive factors namely executive function capacity (EF) and autistic traits, in terms of their roles in explaining who in speech community would adapt new acoustic forms of the target vowels, and who would retain the old forms. The participants, 55 college students speaking Seoul Korean, produced /o/ and /u/ vowels in isolated words; and completed three EF tasks (Digit N-Back, Stroop, and Trail-Making Task), and an Autism screening questionnaire. The relationships between speakers' cognitive task scores and their utilizations of F1 and F2 were analyzed using a series of correlation tests. Results yielded a meaningful relationship in participants' EF scores interacting with gender. Among the females, speakers with higher EF scores were better at retaining F1, which is a less informative cue for females since they utilized F2 more than they did F1 in realizing /o/ and /u/. In contrast, better EF control among male speakers was associated with more use of the new cue (F2) where males still utilized F1 as much as F2 in the production of /o/ and /u/ vowels. Taken together, individual differences in acoustic realization can be explained by individuals' cognitive abilities, and their progress in the sound change further predicts that cognitive ability influences the utilization of acoustic information which is non-primary to the speaker.

• 대한물리의학회지
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• 제7권4호
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• pp.541-550
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• 2012

PURPOSE: The purpose of this study was compare quadriceps femoris muscle activity while performing wall slide squats of four methods. METHODS: Forty subjects, with no history of patellofemoral pain, quadriceps injury, or other knee injury volunteered for this study. Muscle activation of the vastus medialis obliquus, rectus femoris, vastus lateralis muscles were recorded while subjects performed 10 consecutive wall slide squats. Subjects performed the wall slide squats during four different methods: (1) basic wall slide squat, (2) keep back upright against fitness ball, (3) standing of unstable surface, (4) squeezing ball between both knees. Statistical analysis were accomplished by utilizing the one-way ANOVA(Bonferroni's post-hoc test) by SPSS 20.0 program. Significance level was set at p<.05. RESULTS: Muscle activations induced wall slide squats of four methods compared and results showed that there was significant difference only in vastus medialis obliquus and rectus femoris but there was no significant difference in vastus lateralis. The vastus medialis obliquus was significantly different only keep back upright against fitness ball at post-hoc test. The rectus femoris was significantly different keep back upright against fitness ball and standing of unstable surface at post-hoc test. CONCLUSION: Based on these results, we conclude that quadriceps femoris muscle activations are differenced by performing wall slide squats of four different methods in healthy subjects. These data suggest that for quadriceps muscle strengthening, exercise professionals can perform the wall slide squats by altering several task variables. Further research is needed to determine the exact mechanism by which quadriceps function is altered.

• 대한물리치료과학회지
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• 제11권2호
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• pp.18-26
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• 2004

The purpose of this study was to compare difference of the static and dynamic balance in normal subject and LBP subject and recognizes about postural sway. The subjects of this study included 30 normal subjects and 30 LBP subjects. By using Active balance system, the static balance was measured by unit path length, circumference area, weight bearing, stabilometry length, while the dynamic balance was measured by step evaluation. Statistically analyzed using independent t-test to search static balance and dynamic balance difference in two groups. Postural sway appeared greatly in patient group than normal group in analysis result of static balance and postural sway was big in patient group of when closed eye and normal group and patient group did show statistical significance in unit path length, circumference area. Weight support of normal group was shared equally in weight bearing rate, but weight support of patient group stewed less to pain side. Anterior step time and Task achieve time of dynamic balance were spent more in patient group than normal group. Desire to be used to useful information to lay treatment policy about set-up and action of when quantification result of valued postural balance treats low back pain patient by objective tool, in the fixture, more researches in postural estimation desire that is enforced abuzz.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 춘계학술대회논문집
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• pp.90-94
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• 1997

Many workers like welders are working in squat sitting postures with te object on the ground for an entire work shift. It is suspected that such prolonged squat sitting without any supporting stool would gradually cause musculoskeletal injuries to workers. This study is to quantitatively evaluate the physical stress caused by the prolonged squat sitting and to recommend a safe work/rest schedule for the task with squat sitting posture based on the lab experiment. In this study, 8 healthy student subjects participated in the experiment. They maintained a squat sitting posture for 16 minutes with 4 different stool height conditions: no stool, 10cm hight, 15cm height, 20cm height. Every 2 minutes, the discomfort was subjectively assessed using the magnitude estimation method for the whole body, lower back, upper leg and lower leg. Based on discomfort rating, we found that 10cm height stool relieved the workload most. Discomfort rating results also indicated that 20cm height stool showed the heghest workload, and that there was no difference in workload between 15cm height and no stool. We recommend to provide the workers with 10cm height stool for prolonged squat sitting tasks.

• 한국안전학회지
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• 제12권4호
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• pp.209-213
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• 1997

Manual lifting techniques are commonly defined in terms of the postures adopted at the start of the lift. Quantitative definition is problematic, however, because the absolute joint angles adopted to lift an object are influenced by task parameters, such as the initial height of the load. The main objective of this study is to investigate the grip strength of the both hands at the initial lifting points. The survey is conducted by measuring the compression force, anthropometric data and grip strength at the lifting postures for the subjects(n=50) who is assigned to their job as usual. The experiment is peformed at the four lifting postures which involving the combination of two horizontal factors(H1 : 35 cm, H2 : 55 cm) and two vertical factors(V1 : 20~80 cm, V2 : 47~102 cm). The analysis result of lifting posture indicated that each H1-V1, H2-V1 combinations are about 60$^{\circ}$ and each H1-V2, H2-V2 combinations are about $30^{\circ}$. There are significant differences on grip strength between $60^{\circ}$ and $30^{\circ}$ stooped posture. The results of this study can be provided a method defining lifting postures at the minimum grip strength. Also, it is eliminated a hazard of the injuries which are cumulative trauma disorders(CTDs) and back pain, increased a productivity and improved a welfare of workers.

• Physical Therapy Rehabilitation Science
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• 제9권2호
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• pp.74-81
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• 2020

Objective: To prevent low back pain, an objective evaluation tool to evaluate pelvic mobility and exercise to improve the flexibility of the lumbar region is needed. The purpose of this study was to compare the results of pelvic mobility measurements using the Wii Balance Board (WBB) and Sensbalance Therapy Cushion (STC), evaluate the usefulness of the STC as a tool for measuring pelvic mobility. Design: Cross-sectional study. Methods: Fifty healthy subjects participated in this study. The subjects performed pelvic mobility range, proprioception, reaction time and reach of the arm using the STC. The pelvic movement parameter was measured two times to determine the intra-rater reliability. To measure the correlation between lumbar muscle tension and pelvic mobility, Myovision was used to measure tension of L4, L5 level erector spinae muscle. Correlations between measured variables were checked to determine the validity of the pelvic mobility assessment tool. Results: STC showed high test-retest reliability in pelvic tilt measurement and reaching task [intraclass correlation coefficients (3,1)=0.804-0.915]. The relationship between WBB and STC showed a significant positive correlation with the pelvic tilt and reaching task (p<0.05). Posterior tilt and erector spinae activation (Lt. L5) showed a significant negative correlation (p<0.05). Left, right tilt and erector spinae activation (L5) showed a significant negative correlation (p<0.05). Conclusions: This study confirmed the advantages of the STC and found efficiency as an objective measuring device of pelvic mobility.

• 한국산업보건학회지
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• 제8권1호
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• pp.1-23
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• 1998

Work-related Low Back Pain(LBP) is one of tile most important Issues in the field of industrial safety and health. Particularly, manual lifting is known as a major cause of work-related LBP and impairment. Total number of 163 manual lifting tasks in motor assembly processes were investigated. The 1981 and the 1994 equations developed by National Institute for Occupational Safety and Health(NIOSH) were applied to evaluate potential hazards of lifting-related LBP. Comparisons between the 19R I and 1994 NIOSH criteria were made. The relationships between the NIOSH criteria and lifting-related LBP were also analyzed. The results of this study are as follows: 1. The values of Action Limit(AL) by the NIOSH 1981 lifting equation. Recommended Weight Limit(RWL) by the 1994 equation and the weight of the load handled at each manual lifting task were shown log-normal distributions. 2. LI'(the weight of tile load/AL) and LI(the weight of the load/RWL) were calculated estimate the physical stress imposed by each individual lifting task. As a result. 76.7% of the total LI' value exceeded 1 and 12.9% exceeded 3, and 84.7% of the total LI values exceeded 1 and 20.9% exceeded 3. 3. Bus 2 Department showed the highest rate of LI'>1 and LI>1 and Bus 1 Department showed the highest rate of LI'>3 and LI>3 4. In general, the RWLs by the 1994 equation were found lower than the ALs by the 1981 equation. It is assumed to he resulted from the fact that the 1994 equation includes methods evaluating asymmetrical lifting tasks and lifts of objects with less then optimal hand-container couplings, and also covers a larger range of work durations and lifting frequencies than the 1981 equation. 5. Significant correlations were found between LI' and incidence of LBP (R=0.734, p<0.05). LI and incidence of LBP(R=0.671. p<0.10) and load-weights and incidence of LBP(R=0.797, p<0.05). 6. Control measures are required to achieve the value of LI less than 1 for some tasks having high LI values. Engineering control is highly recommended for some tasks having the value of LI above 3.

• International Journal of Korean Welding Society
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• 제1권1호
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• pp.17-22
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• 2001

Because the quantitative relationships between welding parameters and welding result are not yet blown, optimal values of welding parameters for $CO_2$ robotic arc welding is a difficult task. Using the various artificial data processing methods may solve this difficulty. This research aims to develop an expert system for $CO_2$ robotic arc welding to recommend the optimal values of welding parameters. This system has three main functions. First is the recommendation of reasonable values of welding parameters. For such work, the relationships in between the welding parameters are investigated by the use of regression analysis and fuzzy system. The second is the estimation of bead shape by a neural network system. In this study the welding current voltage, speed, weaving width, and root gap are considered as the main parameters influencing a bead shape. The neural network system uses the 3-layer back-propagation model and a generalized delta rule as teaming algorithm. The last is the optimization of the parameters for the correction of undesirable weld bead. The causalities of undesirable weld bead are represented in the form of rules. The inference engine derives conclusions from these rules. The conclusions give the corrected values of the welding parameters. This expert system was developed as a PC-based system of which can be used for the automatic or semi-automatic $CO_2$ fillet welding with 1.2, 1.4, and 1.6mm diameter the solid wires or flux-cored wires.

• 대한간호학회지
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• 제27권4호
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• pp.831-842
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• 1997

The purpose of the study was to test the reliability and validity of the Korean version of Task Self-Efficacy Scale for activities of dally living (ADL). The Task Self-Efficacy Scale was developed by Roberts(1996) for low-intensity exercise study with older people to predict their performance of ADL. The scale was translated and back translated by bilingual persons, and then was modified to resolve variations in the translations. The Korean version of Self-Efficacy Scale for ADL was then administered to 193 elderly people including 95 hospitalized patients and 98 outpatients or healthy people. Face to face interview was used to fill out the structured questionnaire, and each interview took approximately 30 minutes. The subjects for the study were 80 women and 112 men with an age range of 65 to 95 years(M=71 years) of whom 82.6% classified themselves as moderate or quite active Most subjects(80.2%) had an education level of elementary school or less. The Self-Efficacy Scale for ADL is measured on a 0 to 10 VAS, assessing three areas of ADL : self care activities, household tasks, and motor tasks. The higher the score is, the higher person's confidence in performing ADL. Psychometric testing revealed that the scale was found to be internally consistent, showing a Cronbach's alpha of .97 The scale was significantly correlated with subjects' level of activity and subjective assessment of their health status. Moderate correlation with health-related hardiness scale also supported the validity. Factor analysis was performed to confirm whether the scale represents the three sub-areas as suggested in the literature. The results of the factor analysis led to a three factor solution according to Kaiser's criterion, but the items were not strongly and cleanly loaded for the third factor. This can be explained in that, among the three sub-ADL areas of the self-efficacy scale, the areas of self care activities and household tasks seem to have similar levels of difficulty in performance with not enough differences for the self-efficacy scale to distinguish between the two areas. Therefore, one factor solution was suggested since ADL can be seen as a unit of activities at similar level of difficulty in performance. One factor solution explained 68.1% of variance of the 19-item scale and all items were correlated over .6 with the factor, showing that the selected factor solution fits the model. The results indicated that the Korean version of Task Self-Efficacy Scale for ADL was reliable and valid in producing useful information to evaluate the effects of various interventions toward promoting health and quality of life for elderly people.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2006년도 추계학술발표대회 논문집
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• pp.17-20
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• 2006

In the remote welding system using $CO_2$ laser, laser beam is rapidly deflected by moving mirrors of scanner system and has focusable distance over 1000mm from workpiece. From such arrangement, various advantages and disadvantages arise. Remote welding is a highly efficient laser process. As the mirrors of the scanner system allow positioning speeds exceeding 700m/s, it becomes possible to reduce the welding cycle time. On the other hand, as there no the provision of shielding gas which is normally required for beam powers exceeding 3kW, may become difficult task. Therefore, In this study, the influence of the various penetration of back bead by the different laser welding speed on the weld seam formation without shielding gas was investigated.