• Safety and Health at Work
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• 제7권2호
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• pp.124-129
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• 2016

Background: Work-related fatigue has a strong impact on performance and safety but so far, no agreed upon method exists to detect and quantify it. It has been suggested that work-related fatigue cannot be quantified with just one test alone, possibly because fatigue is not a uniform construct. The purpose of this study is therefore to measure work-related fatigue with multiple tests and then to determine the underlying factorial structure. Methods: Twenty-eight employees (mean: 36.11; standard deviation 13.17) participated in five common fatigue tests, namely, posturography, heart rate variability, distributed attention, simple reaction time, and subjective fatigue before and after work. To evaluate changes from morning to afternoon, t tests were conducted. For further data analysis, the differences between afternoon and morning scores for each outcome measure and participant (${\Delta}$ scores) were submitted to factor analysis with varimax rotation and each factor with the highest-loading outcome measure was selected. The ${\Delta}$ scores from tests with single and multiple outcome measures were submitted for a further factor analysis with varimax rotation. Results: The statistical analysis of the multiple tests determine a factorial structure with three factors: The first factor is best represented by center of pressure (COP) path length, COP confidence area, and simple reaction time. The second factor is associated with root mean square of successive difference and useful field of view (UFOV). The third factor is represented by the single ${\Delta}$ score of subjective fatigue. Conclusion: Work-related fatigue is a multidimensional phenomenon that should be assessed by multiple tests. Based on data structure and practicability, we recommend carrying out further studies to assess work-related fatigue with manual reaction time and UFOV Subtest 2.

• 복식문화연구
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• 제12권2호
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• pp.279-289
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• 2004

This study was conducted to compare the hunting reaction of finger in the cold water. Finger skin temperature is measured the left middle finger tip immersion in cold water of 5℃ for 30 minutes and measurements were made on finger skin temperature(Ts), thermal comfort, and cold pain sensations during the experiment at the spring (March) and Winter(December). Results were follows. Is before immersion was at the highest in spring and at the lowest in winter and was closely related to the indoor temperature Ts during immersion and recovery. Mean of finger skin temperature(MST), the skin temperature at the first rise(TTR) and amplitude of finger skin temperature reaction during immersion(AT) were significant higher in spring than that in winter(P＜.01). The lowest skin temperature(LST) during the cold water immersion were significantly higher in spring than that in winter (P＜.05). The frequency of the appearance of cold-Induced vase dilation(CIVD) was higher in spring than that in winter. However, time for the first temperature(TTR) and recovery time(RT) had no seasonal variation. In addition, cold pains during immersion were felt more strongly in spring than in winter. Local thermal sensation, finger thermal sensation in dynamic state during hand immersion was different from that in the Winter. Spring was slowly cold in cold water immersion.

• The Journal of Korean Physical Therapy
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• 제33권6호
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• pp.265-271
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• 2021

Purpose: We aimed to analyze the reliability of the test for choice stepping reaction time (CSRT) under an unstable surface and determine whether there were differences in CSRT between support surface conditions (stable vs. unstable conditions) and between age groups (young adults vs. community-dwelling older adults). Methods: Twenty healthy community-dwelling older adults and twenty young adults performed the stepping task under an unstable condition over two visits. The mean of the two trials measured for each visit was used for the analysis. The test-retest reliability was analyzed using intra-class correlation coefficient (ICC) with a 95% confidence interval, standard error of measurement (SEM), and minimal detectable change (MDC). Differences in CSRT between support surface conditions and age groups were analyzed using the independent t-test with Bonferroni correction. Results: Excellent consistency was observed for ICC >0.90 in both groups. Moreover, the SEM and MDC values of the CSRT in older and young adults were 0.03 and 0.09 and 0.01 and 0.04, respectively. There was a significant difference in the CSRT between the age groups under stable (p<0.001) and unstable conditions (p<0.001). Conclusion: The findings demonstrated that the test for CSRT under an unstable condition had reliable results in both groups. Although older adults demonstrated longer reaction times than younger adults in all surface conditions, increasing the balance control demand by implementing a choice stepping task concomitant with a balance task had no influence on the reaction time in both age groups.

• 대한물리의학회지
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• 제8권2호
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• pp.281-287
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• 2013

PURPOSE: The study was designed to investigate the effects of visual, auditory, and visuoauditory cues on simple Serial Task Performance in heaithy adults. METHODS: Sixty-three right-handed heaithy adults without history of neurological dysfunction were participated. A modified version of the Serial Reaction Time Task (SRTT) using five blocks of perceptual motor sequences was administered. The blocked paradigm consisted of the five blocks with randomly repeated 8 digit sequences with 5 repetition. Three types of sensory cue were employed: visual cue, auditory cue and visuoauditory cue. All subjects were assigned to press the matched botton as quickly and accurately as possible, when one of 8 stimulations was presented(one, two, three, four, five, six, seven, eight). The reaction time, accuracy, and P300 latency were measured during serial task performance. The mean reaction time(ms), accuracy(%), and P300 latency(ms) were compared between three types of cue using ANOVA. RESULTS: The reaction time to auditory cue was significantly longer than visual and visuoauditory cues(p<.001). And accuracy to auditory cue was significantly lower than visual and visuoauditory cues(p<.001). All P300 latency(at Fz, Cz, Pz) were significantly longer than to visual and visuoauditory cues(p<.05). CONCLUSION: It is suggested that type of cues influence in choice reaction. These data may helpful in designing not only effective motor learning training programs for healthy persons but also reeducation programs for patients with neurological dysfunction.

• Asian-Australasian Journal of Animal Sciences
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• 제3권4호
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• pp.343-346
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• 1990

A study was conducted to determine the effect of prostaglandin $F_2$ alpha ($PGF_2$ alpha) on the reaction time and seminal characteristics of buffalo bulls. Semen was collected from three Murrah bulls in three periods: pre-treatment, treatment and post-treatment. During the treatment period each bull was administered 2 ml $PGF_2$ alpha (Synchrocept, Fenprostalene) im, 1 hour prior to semen collection. In the post-treatment, semen was collected 7 days after the last injection of $PGF_2$. Semen samples were evaluated immediately after collection. Pre-collection injection of $PGF_2$ alpha has no significant effect on reaction time, semen volume, percentage motility, sperm concentration and total number of sperms per ejaculate. Fluctuations in semen color and consistency were observed. There is a significant (p<0.05) increase in the mean percentage of normal spermatozoa during the treatment and post treatment periods. Likewise, administration of PG results into a significant (p<0.05) rise on the average percentage of live sperms but this effect was not manifested in the post-treatment period. Improvement in mass activity was observed during the treatment and post-treatment periods.

• 기본간호학회지
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• 제10권3호
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• pp.399-407
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• 2003

Purpose: This study was done to identify levels of physical fitness in student nurses and to ascertain the relationship among the different aspects of physical fitness of strength, power, muscle endurance, agility, balance and flexibility. Method: The participants were 266 students selected from one college of nursing. From May 1 to July 31 in 2003, physical constitution, muscle strength (grip strength, back strength), power (standing long jump), muscle endurance (sit-ups), agility (whole body reaction time-light, sound), balance (close-eyes foot-balance), and flexibility (sitting trunk flexion) were measured. Result: The mean(standard deviation) for grip strength was 22.59(3.93) kg., for back strength, 48.52(12.85) kg., for standing long jump, 135.29(20.54) m., for sit-up's, 23.66(9.35) per minute, whole body reaction time (light), 0.43(0.11) sec, whole body reaction time (sound), 0.50(0.16) sec, close-eyes foot-balance, 33.35(38.67) sec, and sitting trunk flexion 34.72(9.37) cm. Conclusion: This study showed that the physical fitness of student nurses is very low compared to the results in a report from the Korea Sports Science Institute. It is necessary to include exercise programs for student nurses in order to improve their physical fitness.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3312-3316
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• 2013

Single crystals of hexagonal graphenes were successfully grown on Cu foils using the atmospheric pressure chemical vapor deposition (CVD) method. We investigated the effects of reaction parameters, such as the growth temperature and annealing time, on the size, coverage, and density of graphene domains grown over Cu foil. The mean size of the graphene domains increased significantly with increases in both the growth temperature and annealing time, and similar phenomena were observed in graphene domains grown by low pressure CVD over Cu foil. From the comparison of micro Raman spectroscopy in the graphene films grown with different annealing times, we found that the nucleation and growth of the domains were strongly dependent on the annealing time and growth temperature. Therefore, we confirmed that when reaction time was same, the number of layers and the degree of defects in the synthesized graphene films both decreased as the annealing time increased.

• 대한산업공학회지
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• 제16권2호
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• pp.11-21
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• 1990

With a general trend toward larger and more complex systems with centralized control, an operator's role of supervisory decision making in the control room becomes more important. Identification of potential man-machine interface (MMI) problems with CRT-based process control systems was attempted using a structured questionnaire survey. Based on the survey results, a laboratory experiment was carried out to investigate the performance of alarm detection on a process control CRT display. The user performance was measured in terms of reaction time from the onset of an alarm sound until the completion of predefined response procedures. The results revealed that for a highly complex tasks, mean reaction time ($\bar{RT}$) with a color consistent display was 10.5% faster than that with the original display, and $\bar{RT}$ with a grouped display was reduced by 8.2% in comparison with the color consistent display.

• 한국분말재료학회지
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• 제11권3호
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• pp.224-232
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• 2004

Ni-diamond composite powders with nickel layer of round-top type on the surface of synthetic diamond (140/170 mesh) were prepared by the electroless plating method (EN) with semi-batch reactor. The effects of nickel concentration, feeding rates of reductant, temperature, reaction time and stirring speeds on the weight percentage and morphology of deposited Ni, mean particle size and specific surface area of the composite powders were investigated by Atomic Adsortion Spectrometer, SEM-EDX, PSA and BET. It was found that nucleated Ni-P islands, acted as catalytic sites for further deposition and grown into these relatively thick layers with nodule-type on the surface of diamond by a lateral growth mechanism. The weight percentage of Ni in the composite powder increased with reaction time, feeding rate of reductant and temperature, but decreased with stirring speed. The weight percentage of Ni in Ni-diamond composite powder was 55% at 150 min., 200 rpm and 7$0^{\circ}C$ .

• Journal of Electrochemical Science and Technology
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• 제11권1호
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• pp.60-67
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• 2020

In this study, copper (II) oxide powder for electroplating was prepared by recovering CuCl₂ from NaClO₃ type etching wastes via recovered non-sintering two step chemical reaction. In case of alkali copper carbonate [mCuCo₃·nCu(OH)₂], first reaction product, CuCo₃ is produced more than Cu(OH)₂ when the reaction molar ratio of sodium carbonate is low, since m is larger than n. As the reaction molar ratio of sodium carbonate increased, m is larger than n and Cu(OH)₂ was produced more than CuCO₃. In the case of m has same values as n, the optimum reaction mole ratio was 1.44 at the reaction temperature of 80℃ based on the theoretical copper content of 57.5 wt. %. The optimum amount of sodium hydroxide was 120 g at 80℃ for production of copper (II) oxide prepared by using basic copper carbonate product of first reaction. At this time, the yield of copper (II) oxide was 96.6 wt.%. Also, the chloride ion concentration was 9.7 mg/L. The properties of produced copper (II) oxide such as mean particle size, dissolution time for sulfuric acid, and repose angle were 19.5 mm, 64 second, and 34.8°, respectively. As a result of the hole filling test, it was found that the copper oxide (II) prepared with 120 g of sodium hydroxide, the optimum amount of basic hydroxide for copper carbonate, has a hole filling of 11.0 mm, which satisfies the general hole filling management range of 15 mm or less.