• Tribology and Lubricants
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• v.39 no.4
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• pp.154-166
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• 2023

This study establishes a numerical analysis model of the finite element overhung rotor supported by a DTRB and describes the stiffness properties of the DTRB. The vibration characteristics and contact pressure of the RBR system are predicted according to the DTRB support characteristics such as the initial axial compression and roller profile. The stiffness of the DTRB significantly varies depending on the initial axial compression and external load owing to the occurrence of rollers under the no-load condition and increase in the Hertz contact force. The increase in the initial axial compression increases the rigidity of the DTRB, thereby reducing the displacement of the RBR system and simultaneously increasing the natural frequency. However, above a certain initial axial compression, the effect becomes insignificant, and an excessive increase in the initial axial compression increases the contact pressure. The roller crowning radius, which gives a curvature in the longitudinal direction of the roller, decreases the displacement of the RBR system and increases the natural frequency as the value increases. However, an increase in the crowning radius increases the edge stress, causing a negative effect in terms of the contact pressure. These results show that the DTRB support characteristics required for reducing the vibration and contact pressure of the RBR system supported by the DTRB can be designed.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.1
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• pp.47-57
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• 2016

In this paper, we measured human body signals in order to verify a active harness system that we developed for gait and balance training. The experimental procedure was validated by tests with 20 healthy male subjects. They conducted motions of Activities of Daily Living(ADL)(Normal Walking, Stand-to-Sit, Sit-to-Stand, Stair Walking Up, and Stair Walking Down) according to body weight support rates (0%, 30%, 50% of subjects' body weight). The effectiveness of the active harness system is verified by using the results of foot pressure distribution. In normal walking, the decrease of fore-foot pressure, lateral soleus muscle and biceps femoris muscle were remarkable. The result of stand-to-sit results motion indicated that the rear-foot pressure and tibialis anterior muscle activities exceptionally decreased according to body weight support. The stair walking down show the marked drop of fore-foot pressure and rectus femoris muscle activities. The sit-to-stand and stair walking up activities were inadequate about the effect of body weight support because the velocity of body weight support system was slower than male's activity.

• Journal of Korean Home Economics Education Association
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• v.19 no.4
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• pp.57-74
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• 2007

The purpose of this study was to investigate differences in adolescent's academic motivation, which is composed of intrinsic learning motivation and extrinsic learning motivation, by family strengths and parent's expectation styles. The subject of this study were 508 students who were selected at random from second, and third grade of middle school in Daegu. Factor analysis and MANOVA were employed for data analysis and Scheff test for post - hoc analysis. The main findings of this study were as follows: First, there were significant differences in learning motivation of adolescents according to the degree of family strengths. More specifically, adolescents who perceived their family strengths to be high had higher intrinsic learning motivation than adolescents who perceived their family strengths to be middle and low. Second, there were significant differences in intrinsic learning motivation of adolescents according to the parent's academic expectation styles. Adolescents who perceived their parent's academic expectation styles paternal support-maternal support, paternal pressure-maternal support, and paternal support-maternal pressure showed higher intrinsic learning motivation than adolescents who perceived their parent's academic expectation styles paternal pressure-maternal pressure. Third, there were significant differences in intrinsic learning motivation of adolescents according to the parent's academic expectation styles and the degree of family strengths. In adolescents group who perceived their family strengths to be low, adolescents who perceived their the parent's academic expectation styles to be paternal support-maternal support, paternal pressure-maternal support and paternal support-maternal pressure had higher intrinsic learning motivation than adolescents who perceived their the parent's academic expectation styles to be paternal pressure-maternal pressure.

• Korean Journal of School Psychology
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• v.16 no.2
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• pp.89-110
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• 2019

This study is to verify relative influence of individual, parent, peer, teacher-related variables as protective factors and risk factors of academic hatred. Surveys were conducted with 1,015 (women, 57.3%) high school third grade students across eight schools where are located in Seoul, Incheon, and Geyonggi province. Correlation analysis and hierarchical multiple regression analysis were performed. The findings are summarized as follows. Teacher's academic pressure did not have significant correlation with student's basic psychological needs, teacher's autonomy support, teacher's support, and peer support whereas other variables showed significant correlation each others. The hierarchical multiple regression analysis indicated that student's individual competence and autonomy, parent's academic support, and teacher's emotional support work as protective factors and that parent's academic pressure functions as a risk factor. The effects of peer support disappeared when teacher-related factors were included. In addition, the effects of teacher's autonomy support disappeared, while the effects of teacher's support strengthened when learner's basic psychological needs were input. This study is meaningful in that it clarified academic hatred which had not been studied in other research and that it provided theoretical foundation for subsequent studies on academic hatred by examining relative influence of related variables. Lastly, it presented its limitation, implications on intervening strategies in school counseling, and suggestions for later studies.

• The Journal of Information Systems
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• v.8 no.2
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• pp.129-143
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• 1999

A great number of companies are currently examining the opportunities made available through the internet. This research aims to identify the factors that influence the adoption of the internet market. The innovation-IT-diffusion theory provide the theoretical foundation for this study. Seven factors were found to influence the adoption level of the internet market. They are top management support, cost efficiency, inclination toward new technology, absorptive capacity, institutional support, competitors move and customer pressure. Nonparametric test was used to test hypotheses. The results shows that top management support is the most important factor, and institutional support is not related to the adoption of the internet market.

• Tuberculosis and Respiratory Diseases
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• v.41 no.4
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• pp.372-378
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• 1994

Background: Pressure support ventilation(PSV) is a new form of mechanical ventilatory support that assists spontaneous inspiraory effort of an intubated patient with a clinician-selected amount of positive airway pressure. Low level pressure support during inspiration can overcome the resistive component of inspiratory work imposed by an endotracheal tube. However the clinical efficacy of PSV as a weaning method has not been established yet. Object: The aim of study was to evaluate the efficacy of PSV when it is added to intermittent mandatory ventilation(IMV) in facilitating weaning precess compaired to IMV mode alone. Method: When the subject patients became clinically stable with their arterial blood gas analysis in acceptable range, they underwent weaning process either by IMV alone or by IMV plus PSV. The level of pressure support was held constant throught the weaning period. For the patients who required mechanical ventilation for less than 72 hr, 2h weaning trial was performed with IMV rate starting from 6/min. For the patients who required mechanical ventilation more than 72 hr, 7 hr weaning trial was performed with IMV rate starting from 8/min. For the patients who failed three consecutive trials of weaning, retrial of weaning was attempted over 3 days with IMV rate starting from 8/min. Clinical characteristics, APACHE II score and nutritional status were compared. For all patients, heart rate, mean blood pressure and respiratory rate were mornitored for 48 hrs after weaning trial started. Results: The total number of weaning trial was 37 in 23 patients(18 by IMV, 19 by IMV+PSV). Total ventilation time, APACHE II score and nutritional status were not statistically different between the two groups. The weaning success rate were not statistically different(38.3% by IMV, 42.1% by IMV+PSV) and the changes of mean blood pressure, heart rate, respiratory rate during first 48 hours were not different between the two groups. Conclusion: Low level PSV when added to IMV for weaning trial does not seem to improve the success rate of weaning from mechanical ventilation. PSV at 10cm $H_2O$ did not induce significant physiologic changes during weaning process.

• Geomechanics and Engineering
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• v.30 no.2
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• pp.153-167
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• 2022

This study proposes a method to analyze the distribution of coal porosity disturbances after the excavation of ultra-large-diameter water jet boreholes using a coal wetting and softening model. The high-pressure jet is regarded as a short-term high-pressure water injection process. The water injection range is the coal softening range. The time when the reference point of the borehole wall is shocked by the high-pressure water column is equivalent to the time of high-pressure water injection of the coal wall. The influence of roadway excavation with support and borehole diameter on the ultra-large-diameter jet drilling excavation is also studied. The coal core around the borehole is used to measure the gas permeability for determining the porosity disturbance distribution of the coal in the sampling plane to verify the correctness of the simulation results. Results show that the excavation borehole is beneficial to the expansion of the roadway excavation disturbance, and the expansion distance of the roadway excavation disturbance has a quadratic relationship with the borehole diameter. Wetting and softening of the coal around the borehole wall will promote the uniform distribution of the overall porosity disturbance and reduce the amplitude of disturbance fluctuations.

• 기술발표회
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• s.2006
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• pp.342-355
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• 2006

The Tunnel portal is designed on temporary support system which is composed by 28m height H-Pile method and Ground Anchor method. The tunnel has excavated about 30m from the portal, but some deformation is found on the surface ground just above the tunnel face. It was investigated very carefully to find out the causes of deformation. By the observation and study, two main causes of deformation are found out. The one is earth pressure increase compared with classical earth pressure theory. That was due to the direction of ground rock mass's discontinuities. It causes the increase of earth pressure that are activated by the direction of discontinuity. The other one is that present design method neglect the transferred force by removal of temporary support members and ground anchor within the tunnel contour line as the tunnel excavation proceeds As the result of removals of the member and anchor, some force transferred from removed systems to remaining supporting systems. In designing the portal support systems, lt must be considered the discontiunity of ground mass and the transfered force due to excation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4C
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• pp.147-154
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• 2011

Currently NATM tunnels are designed by applying the initial ground loads caused during construction to the primary supports, conisting of shotcrete, steel ribs and rock bolts. For long term considerations, it is assumed that the primary supports lose its functionality and therefore the secondary support, i.e. concrete lining, is design to resist against the entire ground loads. But the steel ribs, usually applied to bad ground conditions, are embedded in shotcrete causing very little corrosion and therefore the assumption that the primary support will lose all of its functionality is too conservative. Also even though shotcrete carbonates in long term, excluding it from design is also too conservative. In this study, we have, through analytical and numerical analysis, set a rational level of support pressure and allowable relaxed rock mass height sustainable by the primary support for long term design. Changes in sectional forces of the concrete lining considering the calculated support pressure of the primary supports was also carried out. Shallow subway tunnels were considered in the analysis with weathered rock and soft rock ground conditions. The analysis results showed that, by considering the support pressure of steel ribs, an economical design of the concrete lining is possible.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.63-68
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• 1990

The nature of fluctuating air pressure inside building was studied by testing a building model in a wind tunnel. The model has a single room and a sin81e window opening. Various opening conditions were tested in both laminar uniform wind and turbulent boundary-layer wind. The RMS and the spectra of the fluctuating internal pressure were measured. The test results support a recent theory which predicts the behavior of internal pressure under high wind based on aerodynamic analysis.