• Safety and Health at Work
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• v.14 no.3
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• pp.303-308
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• 2023

Background: Occupational workers at altitudes are more prone to falls, leading to catastrophic outcomes. Acrophobia, height-related anxiety, and affected executive functions lead to postural instabilities, causing falls. This study investigated the effects of repeated virtual height exposure and training on cognitive processing and height-related anxiety. Methods: Twenty-eight healthy volunteers (age 20.48 ± 1.26 years; mass 69.52 ± 13.78 kg) were recruited and tested in seven virtual environments (VE) [ground (G), 2-story altitude (A1), 2-story edge (E1), 4-story altitude (A2), 4-story edge (E2), 6-story altitude (A3), and 6-story edge (E3)] over three days. At each VE, participants identified occupational hazards present in the VE and completed an Attitude Towards Heights Questionnaire (ATHQ) and a modified State-Trait Anxiety Inventory Questionnaire (mSTAIQ). The number of hazards identified and the ATHQ and mSTAIQ scores were analyzed using a 7 (VE; G, A1, A2, A3, E1, E2, E3) x 3 (DAY; DAY 1, DAY 2, DAY 3) factorial repeated measures analysis of variance. Results: The participants identified the lowest number of hazards at A3 and E3 VEs and on DAY 1 compared to other VEs and DAYs. ATHQ scores were lowest at G, A1, and E1 VEs. Conclusion: Cognitive processing is negatively affected by virtual altitudes, while it improves with short-term training. The features of virtual reality, such as higher involvement, engagement, and reliability, make it a better training tool to be considered in ergonomic settings. The findings of this study will provide insights into cognitive dual-tasking at altitude and its challenges, which will aid in minimizing occupational falls.

• Korean Journal of Agricultural Science
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• v.16 no.2
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• pp.225-238
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• 1989

These studies were conducted to investigate the extraction, purification and characterization of oriental pear (Niitaka. Pyrus pyrifolia Nak.) protease, and the results obtained were as follows: 1. Oriental pear protease was effectively extracted by the method of homogenizing pear pulp with 0.7 volume of 0.1M-sodium phosphate buffer, pH 6.5 containing 5mM-cysteine, 40mM-2-mercaptoethanol and 2mM-EDTA at 10,000 rpm for 5 min. 2. The protease was purified by ammonium sulfate fractionation, Sephadex G-100 filtration and DEAE-Sephadex A-50 column chromatography, and the purified enzyme gave a single protein band on polyacrylamide gel electrophoresis. 3. The specific activity of purified enzyme was 29.65 unit/mg protein and the yield was 7.22%. 4. The moecular weight of the protease was estimated to be about 51,000 by SDS-polyacrylamide gel electrophoresis, and the enzyme had Km value of 54.5 mg/ml for casein. 5. The purified enzyme had a maximum activity at pH 6.0 and $50^{\circ}C$, and was stable from pH 5.5-6.5 and at temperatures below $50^{\circ}C$ 6. Casein was a better substrate for this protease compared to hemoglobin. 7. The enzyme activity was markedly inhibited by p-chloromercuribenzoic acid and heavy metal salts such as $HgCl_2$ and $MnSO_4$ also considerably inhibited the enzyme activity.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.553-555
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• 1996

This paper concerns with a method to improve the current and power waveforms of the variable speed $3{\Phi}$ AC motor system driven by the single-pulse PWM, and the current waveforms and $3{\Phi}$ power waveforms are analyzed by FFT under various running conditions. By the performance analysis through the experiments, the following results have been obtained. AC source of pseudo sine waveform can be obtained from the modulated alternating square voltage by means of the well designed LC filter. It is confirmed that current waveforms and $3{\Phi}$ power waveforms can be improved by utilizing the high order low pass LC filter than that of lower order. Especially, current waveforms and $3{\Phi}$ power waveforms tan be much improved at low frequency domain. $3{\Phi}$ power waveforms have a smatter ripple and bigger power by utilizing the high order low pass LC filter than that of lower order. Also, the running condition of $3{\Phi}$ AC motor is good at low frequency domain.

• Journal of Environmental Science International
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• v.13 no.2
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• pp.161-165
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• 2004

This study has been conducted to develop a new recycling technology of sewage sludge using a carbonization process. The carbonizing yield, the calorific value and EC(electric conductivity) of carbonized sewage sludge had a tendency to be decreased with increase of the carbonizing temperature and time, but pH and the C/N were increased with increase the carbonizing temperature and time. The whole pore volume of carbonized sludge processed in the carbonizing furnace was /g, which was smaller than that in the electric furnace. But, the rates of mesopore and macropore were found to account for 100% therein. Rate of color and organic materials removal for dyeing wastewater were determined 70~97%, 78~83% on cotton yarn, 88~96%, 69~80% on wool wastewater and 77~89%, 77~87% on towel compared with powder activated carbon. Effect of carbonized sludge on chrysanthemum growth was investigated. Plant height and number of leaves was better mixture of carbonized sludge than comparison.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1349_1350
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• 2009

Thin films of pp(ST-Co-VA) were fabricated by plasma deposition polymerization (PVDPM) technique. Properties of the plasma polymerized pp(ST-Co-VA) thin films were investigated for application to semiconductor device as insulator. Thickness, dielectric property, composition of the pp(ST-Co-VA) thin films were investigated considering the relationship with preparation condition such as gas pressure and deposition time. In order to verify the possibility of application to organic thin film transistor, a pentacene thin film was deposited on the pp(ST-Co-VA) insulator by vacuum thermal evaporation technique. Crystalline property of the pentacene thin film was investigated by XRD and SEM, FT-IR. Surface properties at the pp(ST-Co-VA)/pentacene interface was investigated by contact angle measurement. The pp(ST-Co-VA) thin film showed a high-k (k=4.6) and good interface characteristic with pentacene semiconducting layer, which indicates that it would be a promising material for organic thin film transistor (OTFT) application.

• Earthquakes and Structures
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• v.3 no.1
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• pp.1-15
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• 2012

An empirical predictive relationship correlating bracketed duration to earthquake magnitude, site-to-source distance, and local site conditions (i.e. rock vs. stiff soil) for stable continental regions of North America is presented herein. The correlation was developed from data from 620 horizontal motions for central and eastern North America (CENA), consisting of 28 recorded motions and 592 scaled motions. The bracketed duration data was comprised of nonzero and zero durations. The non-linear mixed-effects regression technique was used to fit a predictive model to the nonzero duration data. To account for the zero duration data, logistic regression was conducted to model the probability of zero duration occurrences. Then, the probability models were applied as weighting functions to the NLME regression results. Comparing the bracketed durations for CENA motions with those from active shallow crustal regions (e.g. western North America: WNA), the motions in CENA have longer bracketed durations than those in the WNA. Especially for larger magnitudes at far distances, the bracketed durations in CENA tend to be significantly longer than those in WNA.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.282-284
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• 1997

Ultrasonic motors using piezoelectric ceramics and brass metal endcaps were fabricated, which is operated by single - phase high frequency. The structure of the ultrasonic motors has the wind-mill type. The stator part consists of a piezoelectric disk and two metal endcaps slotted wind-mill type. According to the piezoceramic disk vibrates as a radial mode, two metal endcaps provide both longitudinal and torsional displacements simultaneously. Because the metal endcaps have a nonsymmetric structure. the principle of the ultrasonic motor is not well understood. The dimension of the ultrasonic motor is diameter in 12.7 mm and thickness in 2.0 mm, and especially the PMN-PT-PZ piezoelectric disk was used. The maximum revolution speed 700 rpm and the maximum torque 0.22 mN.m were obtained. The ultrasonic motor for rotation was Supplied only single phase AC.

• Journal of applied mathematics & informatics
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• v.29 no.3_4
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• pp.529-546
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• 2011

A deterministic tuberculosis model for theoretically assessing the potential impact of the combined effects of case detection in the presence of treatment is formulated. The qualitative features of its equilibria are analyzed and it is found that the disease-free equilibrium may not be globally asymptotically stable when the reproduction number is less than unity. This disease threshold number is further used to assess the impact of active TB case finding alone and in conjunction with treatment. A critical threshold parameter ${\Theta}$ say for which case detection will have a positive impact is derived. Using the Centre Manifold theory, the model may exhibit the phenomenon of backward bifurcation (coexistence of a locally stable endemic equilibrium with a stable disease-free equilibrium) when the reproduction number is less than unity. It is shown that the possibility of backward bifurcation occurring decreases with increase case detection. Graphical representations suggest that increase in case finding accompanied by treatment of detected TB cases, result in a marked decrease of TB cases (both latent and active TB).

• Phonetics and Speech Sciences
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• v.8 no.2
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• pp.73-80
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• 2016

The purpose of this study was to analyze perceptual and spectral/cepstral measurements in patients with adductor spasmodic dysphonia(ADSD). Sixty participants with gender and age matched individuals(30 ADSD and 30 controls) were recorded in reading a sentence and sustained the vowel /a/. Acoustic data were analyzed acoustically by measuring CPP, L/H ratio, mean CPP F0 and CSID, and auditory-perceptual ratings were measured using GRBAS. The main results can be summarized as below: (a) the CSID for the connected speech was significantly higher than for the sustained vowel (b) the G, R and S for the connected speech were significantly higher than for the sustained vowel (c) Spectral/cepstral parameters were significantly correlated with the perceptual parameters, and (d) the ROC analysis showed that the threshold of 13.491 for the CSID achieved a good classification for ADSD, with 86.7% sensitivity and 96.7% specificity. Spectral and cepstral analysis for the connected speech is especially meaningful on cases where perceptual analysis and clinical evaluation alone are insufficient.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.1
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• pp.23-30
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• 2011

This study was carried out to investigate the effect of aging treatment on the mechanical properties and damping capacity of 12Cr heat resistant steel with ferrite phase. While hardness values in ferrite phase was not changed, that in martensite phase was dramatically dropped in early stage of aging treatment and then gradually decreased with increase of aging time. As aging treatment was carried out, the precipitation was not detected in ferrite phase, while carbides were precipitated in martensite phase. With increasing the aging time, tensile strength eventually decreased while impact toughness increased rapidly in the early stage of aging and then gradually increased. Besides, it was confirmed that damping capacity was not changed in the early stage of aging and then gradually increased with increase of aging time.