• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.244-247
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• 2005

Although several artificial disc designs have been developed for the treatment of discogenic low back pain and used clinically, biomechanical change with its implantation seldom studied. To evaluate the effect of artificial disc implantation on the biomechanics of lumbar spinal unit, nonlinear three-dimensional finite element model of L1-L5, S1 was developed and strain and stress of vertebral body and surrounding spinal ligaments were predicted. Intact osteoligamentous L1-L5, S1 model was created with 1-mm CT scan of a volunteer and known material property of each element were applied. This model also includes the effect of local muscles which was modeled with pre-strained spring elements. The intact model was validated with reported biomechanical data. Two models implanted with artificial discs, SB Charite or Prodisc, at L4/5 via anterior approach were also developed. The implanted model predictions were compared with that of intact model. Angular motion of vertebral body, force on spinal ligaments, facet joint contact force with $2\sim12$ Nm flexion-extension moment.

• Steel and Composite Structures
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• v.35 no.3
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• pp.439-447
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• 2020

This paper presents two sets of full three-dimensional thermoelastic finite element analyses of superimposed thermo-mechanically loaded Spar Wingskin Joints made with laminated Graphite Fiber Reinforced Plastic composites. The study emphasizes the influence of residual thermal stresses and material anisotropy on the inter-laminar delamination behavior of the joint structure. The delamination has been pre-embedded at the most likely location, i.e., in resin layer between the top and next ply of the fiber reinforced plastic laminated wingskin and near the spar overlap end. Multi-Point Constraint finite elements have been made use of at the vicinity of the delamination fronts. This helps in simulating the growth of the embedded delamination at both ends. The inter-laminar thermoelastic peel and shear stresses responsible for causing delamination damage due to a combined thermal and a static loading have been evaluated. Strain energy release rate components corresponding to the Mode I (opening), Mode II (sliding) and Mode III (tearing) of delamination are determined using the principle of Virtual Crack Closure Technique. These are seen to be different and non-self-similar at the two fronts of the embedded delamination. Residual stresses developed due to the thermoelastic anisotropy of the laminae are found to strongly influence the delamination onset and propagation characteristics, which have been reflected by the asymmetries in the nature of energy release rate plots and their significant variation along the delamination front.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.467-472
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• 2010

Individual vacuum pressure method is soft ground improvement technique, in which a vacuum pressure can be directly applied to the vertical drain board to promote consolidation and strengthening the soft ground. This method does not require a surcharge load, different to embankment or pre-loading method. In this study, given the inner displacement of the ground where the individual vacuum pressure is applied, this dissertation aimed to reproduce the state of stress in the ground that is subject to the constraints created by the depth of improvement area. Modified Cam Clay theory which made it possible to take into account the isotropic displacement of the ground was applied to the NAP-IVP used simulation; the conception of equivalent permeability proposed by Hird was also applied so that the 3-dimensional real construction effect of drain materials could be reflected in the analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2913-2921
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• 1994

In SMA(shape memory alloy), the degradation by fatigue is one of the most important problems to be overcome, when SMA is used for robot-actuator material. The actuator is operated repeatitively for long time and its repeating operation develops the fatigue degradation of SMA. The fatigue degradation changes the transformation temperature and deformation behavior and results in inaccurate operation control of robot. Accordingly, the changing behavior of transformation temperature and deformation which results from repeating operation is to be investigated in advance and the scheme to resolve those problems have to be made for the design of actuator. In this study, the fatigue tests were carried out on SMA specimens prepared to have different condition of aging time and pre-strain with the direct-current heating-cooling method, which was a general method of operation in robot actuators. The behavior of transformation temperature and deformation were examined and analyzed in each specimen and the study was performed to establish the optimistic manufacturing condition of SMA against the fatigue degradation.

• Journal of the Korean Wood Science and Technology
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• v.16 no.4
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• pp.54-60
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• 1988

Machinabilities means inherent properties of pinus densiflora at Chunyang district to be CNC machined easily or not, and processing abilities of the tool and machine together. This explanation signifies that machinabilities have two phases of signification, depended on considering and stress either materials or tools preferentially. This paper discuss machinabilities, the following items are usually employed as the indices of stress distribution at the cutting tool rake face. The stress distributions on the chip - tool contact surface at the early stage of the chip forming and under the stage of fringe pattern in wood cutting were analyzed the photoelastic method. The tool used in the present experiment was the special cutting tool H.S.S. one made in laboratory. And isochromatic fringe pattern and isolinic line of work piece by chip-behavior during the cutting operation were photographed with the feed camera continuously. The effects on the stress, distribution on the rake face of the epoxy tool and the strain distribution in the work piece of wood plate by chip behavior are cleared in pre cent experiment.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.05a
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• pp.83-114
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• 1998

The most widely accepted method for understanding the deformation mechanism of rock is from the use of computer simulation. However, if the changes in rock properties after excavation are significant this will prevent the computer simulation kent predicting the deformation with acceptable accuracy. If the deformations are, however, carefully measured in situ, the resulting data can be more useful far predicting the deformational behavior of underground openings, since the effect of the parameters which influence the deformational behavior are included in the measurement. In this study, extensive data analyses were carried out using the deformation measurements from the Waste Isolation Pilot Plant (WIPP), which is a permanent nuclear waste repository The results from computer simulations were compared with field measurements to evaluate the assumptions used in the computer simulations, For better description of the deformational behavior around underground excavations, several techniques were developed, namely: (a) the calculation of the zero strain boundary; (b) the evaluation of the influence of adjacent excavations on the deformational behavior of pre-excavated openings; (c) the description of the deformational behavior using in situ measurements; (d) the calculation of the shear stress distribution; and (e) the application of a Neural Network for the prediction of opening deformation.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.133-140
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• 2011

Muscle misuse dysphonia (MMD) is defined as a behavioral voice disorder resulting from inappropriate contractions of intrinsic and/or extrinsic laryngeal muscles. The purpose of this study was to investigate the effect of motor learning guided laryngeal motor control therapy (MLG-LMCT) which is designed to improve an existing LMT and further the effective voice treatment on people with muscle misuse dysphonia. Forty-six people with MMD (M:F=16:30) participated in this study. The voice samples of the participants were recorded to investigate the effect of MLG-LMCT before and after the voice therapy. Voice samples were analyzed via electro-glotto-graph (EGG). Contact quotient (CQ), speed quotient (SQ), and waveform were reported. In addition, perceptual and acoustical evaluation were conducted to determine the change of voice improvement after treatment. The experimenter massaged the tensioned muscles around the neck. In order to find more proper phonation the experimenter showed the subjects their EGG wave forms as to whether or not they are moving the vocal folds to the appropriate position. Therefore, the EGG wave forms were used as a type of visual feedback. With the wave form, the experimenter helped subjects move the vocal folds and laryngeal muscles to find more proper voice production. The sensory stimuli from the experimenter gradually faded out. A paired dependent t- test revealed that there was significant differences in CQ between pre- and post-therapy. Perceptually, overall, rough, breathy, strain, and transition were significantly reduced. Acoustically, there were significant differences in Fo, jitter, shimmer, and NHR. After using MLG-LMCT, most of the subjects showed improvements in voice quality. The results from this study led us to the following conclusions: Motor learning guided laryngeal motor control therapy (MLG-LMCT) has reduces muscle misuse dysphonia. These results may occur because a visual feedback from EGG wave form can maintain the effect of the muscle tension reduction from laryngeal manual therapy. In case of people with MMD who reduced muscle tension from the therapy (LMT) but, not appropriately manipulating the location of larynx or adducting the vocal folds, MLG-LMCT might be an alternative therapy approach.

• Research in Plant Disease
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• v.17 no.3
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• pp.302-310
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• 2011

Elsinoe fawcettii is one of major pathogenic fungi which cause citrus scab diseases, resulting in fruit blemishes that reduce the economic value of fruit. By increasing interest to safe products of crops, the alternative methods of disease control is highly required. We investigated whether the 215 bacterial strains isolated from Jeju Island possess antifungal effect or suppression effect on the symptom development by Elsinoe fawcettii on citrus. Among them, three bacterial strains THJ 609-3, MRL408-3, and TRH423-3 that exhibited antifungal capacity against Elsinoe fawcettii were selected. To illustrate the disease suppression mechanism, pre-inoculation with the selected bacterial strains was carried out whether could suppress the citrus crab on the leaves. The observation with a fluorescence microscope revealed that the selected bacteria could decrease the number of fungal spores. The ratio of germ tube formation was also decreased by the selected bacterial strains at one day after fungus challenge. The strain THJ 609-3 was identified as Pseudomonas putida as a result of analyzing the internal transcript spaces of the rhizobacterial rDNA. The strains MRL 408-3 and TRH 423-3 were identified as Burkholderia gladioli. Our results may be valuable when the selected rhizobacterial strains used as the environment-friendly microbe for biological control on citrus scab caused by Elsinoe fawcettii.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.1016-1020
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• 1997

Treatments of irradiation alone and/or in combination with heat were investigated for the sterilization of Escherichia coli O157: H7. D values of the strain were 129.2 min at $50^{\circ}C$, 27.1 min at $55^{\circ}C$, and 2.4 min at $60^{\circ}C$. The survival effect of E. coli O157:H7 during heating at various media was investigated. On heating at temperature of $60^{\circ}C$ for 10 min, the strain was generally more resistant in the media containg such chemical substrates such as 0.03 M cysteine, 1% sodium citrate or 5% sucrose, whereas this strain was appeared weaker in the chemical substrates added group such as 1% meat extract, 1% casein or 1% casamino acid. In the case of irradiation alone, $D_{10}$ value of E. coli O157:H7 was 0.116 kGy, and inactivation factors were $17{\sim}25$ at doses of 2 to 3 kGy. Pre-and post-irradiation heating showed the same $D_{10}$ value about 0.07 kGy. And Inactivation factors were $25{\sim}41$ at doses of 2 to 3 kGy. Therefore, combination treatment with heat and irradiation significantly increased in inactivation rate by increasing radiation sensitivity of E. coli O157:H7.

• Child Health Nursing Research
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• v.5 no.1
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• pp.70-83
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• 1999

The birth of a premature infant is distressing for its parents. The parents of a premature infant experience stress according to the infant's physical appearance and behavior, the environment of the neonatal intensive care unit (NICU) , and the alteration in the parental role. Especially, a mother of a premature infant feels distressed even after the discharge of the infant : therefore, she has difficulties in maternal role performance. The main purpose of this study is to identify the effects of the planned infant care information program in order to lower the stress level for mothers of premature infants caused by the birth and hospitalization in NICU of premature infants, to reduce the maternal role strain, and to promote the maternal role performance after the infants' discharge. This study employed two methods of research at the same time : quasi -experimental non-equivalent pre and post test to compare : non-equivalent post test to compare. The total number of subjects was 19 who were assigned to the research program : 12 mothers of premature infants at the NICU at the Ch university hospital and 7 at the NICU at the Y general hospital located in Chounju city. The data were collected for 79 days from August 18 to November 5, 1998. The questionnaire method was applied for the data collection, and the measures used in this study were Parental Stressor Scale : NICU(Miles, 1993), the Maternal Role Strain Measures ( Hobbs, 1968 ; Steffensmeier, 1982) , and Self Confidence Scale (Pharis, 1978). Research procedure is as follows : after preliminary examination, the experimental subjects, the mothers of premature infants at the Nl CU at Ch university hospital were provided with slide films and information developed by the researcher based on existing documents and data. It took two 60-minute sessions a week for two weeks, and the mothers' stress level was measured using the same instrument twice one week and two week after the infants' hospitalization. The stress level of the contrast subjects, the mothers at Y general hospital was measured during the same period. The experimental subjects were provided with booklets on matters that require attention after the infants' discharge and on developmental project, and they were educated to play the maternal role in person for 2-3 hours a week : breast-feeding, burping a baby, and changing diapers. One week after the infants' discharge, the maternal role strain and the maternal role performance were examined in two groups of the subjects. The analysis of collected data was done using descriptive statistics including real numbers, percentages, averages, and standard deviations. Mann-Whitney test ; x² test ; Repeated Measures Analysis of Variance ; ANCOVA Spearman's rho correlation coefficients. The results on this study were as follows. (1) The examination of the same quality showed that there were no differences in the general and obstetrical characters between the two groups. However, in terms of the characters of premature infants. just right after their birth, the infants at the contrast group weighed more than those at the experimental group(U=16.5, p=.02), and the former was in mother's womb longer than the latter(U=15.5, p=.02). (2) The stress level of the mothers provided with the plannned nursing intervention program became lower as time passed compared to the others'(F=16.61, p=.00) Even when the influence of weight at birth and the length of gestation was removed among the premature infants' characters, the mothers' stress levels made a statistical difference 2 weeks after the infants' hospitalization depending on treatment (F=8.00, p=.01) (3) The maternal role strain of the mothers provided with the planned nursing intervention program was lower than the others'(U=2.0, p=.00). Even when the influence of weight at birth and the length of gestation was removed among the premature infants' characters, the maternal role strain levels made a statistical difference 2 weeks after the infants' hospitalization, depending on treatment(F=14.72, p=.00). (4) The maternal role performance level of the mothers provided with the planned nursing program was higher than the others'(U=.0, p=.00). Even when the influence of weight at birth and the length of gestation was removed among the premature infants' characters, the mothers' stress levels made a statistical difference 2 weeks after the infants' hospitalization, depending on treatment(F=8.00, p=.01). (5) The correlation between a mother's stress level 2 weeks after her infant's hospitalization, the maternal role strain and the maternal role performance were compared : the stress and the maternal role strain were statistically irrelevant to each other(r=.33, p=.12) : the stress was found to be in inverse proportion to the maternal role performance(r=-.53, p=.02). The maternal role strain was in inverse proportion to the maternal role performance as well(r=-.50, p=.00). In conclusion, for the mothers provided with the planned nursing intervention program, their stress level was getting lower as time passed during the infants' hospitalization, their maternal role strain reduced when they took care of their infants after their discharge, and their maternal role performance level was high compared to the other mothers. Besides, the lower the stress level of mothers of premature infants was during the infants' hospitalization, the higher the maternal role performance after their discharge was. The lower maternal role strain was, the higher the maternal role performance was as well. These results of the study suggested that the nursing intervention program for the mothers of premature infants developed by the researcher would be effectively applied to nursing practice, and it would be a foundation for the development of this kind of program.