• 대한치과교정학회지
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• 제24권1호
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• pp.105-114
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• 1994

The movement of teeth during orthodontic treatment requires bone remodeling process of bone formation and bone resolution. To find out the changes occuring in the cell itself, mechanical stress was applied to the cell populations involved in the bone metabolism. Bone tissue cell populations were isolated from fetal rat calvaria and divided into OC and OB groups. Following results were obtained from measuring the changes in acid & alkaline phosphatease activity, cyclic AMP and $PGE_2$ production in time lapse after the application of mechanical stress. 1. In case of the marker enzyme of specific bone tissue cell, acid phosphatase activity was high in OC group and alkaline phosphatase activity was high in OB group. 2. After the mechanical stress was applied, acid phosphatase activity was decreased in both OC and OB groups and alkaline phosphatase activity was increase in OB group. 3. When the mechanical stress was applied for 15, 30 and 60 minutes, the production of $PGE_2$ increased in both OC and OB groups, as the time span increased. 4. When the mechanical stress was applied for 20 and 40 minutes, the production of $PGE_2$ increased in both OC and OB groups, as the time span increased.

• 대한기계학회논문집B
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• 제31권7호
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• pp.588-595
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• 2007

The water transport inside a polymer electrolyte fuel cell (PEFC) varied according to the anodic supply mode. The performance characteristics of a PEFC which can be affected by the water transport were observed with the anodic supply mode. In the flow-through and recirculation mode the performance showed no reduction with time because the flow in the anode was not stagnated. In the dead-end mode, without any discharged gas, the water remains inside of the anode, which caused the reduction of the performance with the lapse of time. However, even in the dead-end mode, little reduction of the performance with time was shown when only the anode was humidified externally. It means that the back-diffusion was the major factor to the accumulation of water in the anode rather than external humidification.

• Journal of Ginseng Research
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• 제7권2호
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• pp.156-162
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• 1983

Stability of nitrogen compounds in the water-extract of ginseng has been investigated in terms of concentration and SDS-PAGE protein pattern as functions of times and temperature. The concentration of free amino-nitrogen in the extract of fresh ginseng varied with time at various temperatures. Especially at temperature over 90$^{\circ}C$, it showed a tendency of steady declease at a considerably fast rate. In the case of red ginseng which had been commercially processed and stocked for 1-7 years, it was found that the free amino-N concentration diminished gradually depending on the length of stock period of samples. This result may be comparative to another observation that the amount and density distribution of precipitate from extract varied with the lapse of stock time, based on accelerated sedimentation test. The number of SDS-PAGE protein bands was observed to be at least seven when determined with the extract of fresh ginseng. However, it tended to reduce finally to be one band when the extract was kept at a rather high temperature for a long time.

• 한국연소학회지
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• 제5권1호
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• pp.43-53
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• 2000

Experimental studies on determination of the supply leading time of propellants to combustion chamber have been made to stably and efficiently guarantee the ignition process with liquid rocket engine. The propellant used is a Jet A-1 as fuel and a liquid oxygen as oxidizer. Unlike impinging FOOF type of injectors are arranged radially and the designed O/F ratio is 2.34. The present experiment program also includes the stability on the quadlet type of ignitor using the triethylalumimum as an ignition source and injector life tests. Experimental results clarifies that the propellant supply through LOx leading to combustion chamber is proper for stable ignition and combustion processes based on the fuel and oxidizer manifold pressures, combustion chamber pressure, and the variation of flame length from the nozzle exit with lapse time, and shows that the leading supply time of propellants affects the engine performance little. The effect of positioning cooling holes is remarkable to protect the injector face.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 특별 심포지엄 논문집
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• pp.31-42
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• 2007

Dc resistivity monitoring has been increasingly used in order to understand the changes of subsurface conditions in terms of conductivity. The commonly adopted interpretation approach which separately inverts time-lapse data may generate inversion artifacts due to measurement error. Eventually the contaminated error amplifies the artifacts when reconstructing the difference images to quantitatively estimate the change of ground condition. In order to alleviate the problems, we defined the subsurface structure as four dimensional (4-D) space-time model and developed 4-D inversion algorithm which can calculate the reasonable subsurface structure continuously changing in time even when the material properties change during data measurements. In this paper, we discussed two case histories of resistivity monitoring to study the ground condition change when the properties of the subsurface material were artificially altered by injecting conductive materials into the ground: (1) dye tracer experiment to study the applicability of electrical resistivity tomography to monitoring of water movement in soil profile and (2) the evaluation of cement grouting performed to reinforce the ground. Through these two case histories, we demonstrated that the 4-D resistivity imaging technique is very powerful to precisely delineate the change of ground condition. Particularly owing to the 4-D inversion algorithm, we were able to reconstruct the history of the change of subsurface material property.

• 대한치과보철학회지
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• 제17권1호
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• pp.47-59
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• 1979

In order to study the morphologic changes of the unfixed odontoblasts suspended in phenol solution of several different concentrations, the author carried out the extraction of lower incisor of S-D strain rats to collect the odontoblasts, and the cells obtained were suspended immediately in saline solution. After observing the odontoblasts in fresh state, the saline solution was substituted with 0.125%, 0.25% 0.5%, 1% and 2% diluted phenol solutions. The morphologic changes were examined with phase contrast microscope at intervals of 10, 30, and 60 minutes. The results were as follows: 1. In saline solution the odontoblast showed cytoplasmic swelling, slender cytoplasmic process, thick rim nuclear membrane with increased dark contrast, and prominent nucleoli and chromatin granules with lapse of time intervals. In accordance with time intervals, blisters appeared in the supranuclear zone and increased its size and moved outward of the cytoplasmic membrane resulting detachment from the cell membrane. The phase dark cytoplasmic granules were increased in its dark contrast and in its size. 2. In 0.125% and 0.25% phenol solution, the odontoblasts and its nucleus shrunk immeidately and its contrast of cellular components was increased. With the lapse of time, the phase-dark granules in cytoplasm were aggregated, and several blisters were formed in and out of the cells. The outline of cytoplasmic membrane was also obscured. 3. In 0.5% phenol solution, the necleus shrunk at once, but soon after it revealed karyolysis accompanying dark contrast of neclear components such as nuclear membrane, nucleoli, and chromatin granules. On the contrary, the cytoplasmic granules showed aggregation and increased dark contrast, small and large blisters were formed in and out of the odontblasts and the outline of cytoplasmic membrane became obscured. 4. In 1% phenol solution, it showed shrinkage of odontblasts and its nuclei with thick rim nuclear membrane, aggregation of chromatin granules and occasional karyorrhexis. The dark contrast of cytoplasmic granules was increased and aggregated each other. But the blister formation could not be found. 5. In 2% phenol solution, it showed the shrinkage of odontoblasts and pyknotic nuclei with increased dark contrast of nucleoli and chromatin granules. The number of cytoplasmic granules was decreased by aggregation. But the blister formation could not be found as in 1% phenol solution.

• Asian-Australasian Journal of Animal Sciences
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• 제31권8호
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• pp.1183-1196
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• 2018

Objective: This study ascertained effects of roughage quality, period of day at meal termination and time lapse after feeding on digesta load in the rumen. Methods: Veld hay was untreated (poor roughage quality, PRQ), improved (improved roughage quality, IRQ) by treating with urea or semi-improved by spraying with urea (semi-improved roughage quality, SIRQ). Experiment 1a used four rumen fistulated sheep to determine in-sacco degradability. Twelve sheep ($56.3{\pm}4.59kg$) were blocked by weight and randomly allocated to IRQ (n = 6) and PRQ (n = 6) to determine solid and liquid passage rates. In experiment 1b, nine sheep ($37.6{\pm}9.34kg$) were blocked by weight and randomly allocated to IRQ (n = 4) and PRQ (n = 5) to determine digestibility. Sixteen sheep ($36.47{\pm}9.46kg$) were blocked by body weight and randomly allocated to IRQ (n = 8) and PRQ (n = 8). Two sheep were slaughtered for each sampling time in each treatment (IRQ and PRQ) at 0, 6, 12, and 24 h after feeding to determine rumen load. In experiment 2, eighteen goats ($25.4{\pm}9.08kg$) were blocked by weight and randomly allocated to IRQ (n = 6), SIRQ (n = 6), and PRQ (n = 6). Then all 18 goats were slaughtered soon after meal termination in the morning; afternoon and evening to determine the effect of period of day on rumen fill. Results: Rate of degradation and effective degradability were enhanced by improvement of roughage quality. Roughage quality had no effect on digestibility, but digestibility was higher in goats than sheep. Fractional passage rate of particles was higher for IRQ than PRQ, but similar for liquids. Digesta fractional clearance rates at 24 h after feeding were 0.018/h (IRQ) and 0.006/h (PRQ). Period of day had an influence on rumen load. Neutral detergent fibre load for goats were above 2.03 kg/100 kg body weight for all diet treatments. Conclusion: Following starvation, passage rate had negligible effects on emptying of rumen load.

• 한국전문물리치료학회지
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• 제4권3호
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• pp.17-33
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• 1997

The objective of this study was to identify pulmonary functional variations in relation to postural changes, lapse after changing position, and the use of abdominal band in the cervical cord injured. The subjects of this study were 19 quadriplegic patients who had been admitted to the department of the Rehabilitation Hospital, College of Medicine, Yousei University, from April, 1997 through May 3, 1997. A spiroanalyzer was used to measure pulmonary function in supine, standing, time after changing position, and recording to the position, application method, and tightness of the abdominal band. The data were analyzed by the repeated measure one-way ANOVA, and Wilcoxon signed rank test. The findings were as follows: 1. All phase of the patients' pulmonary function improved significantly in supine posture in contrast to standing (vital capacity by $0.46{\ell}$ and expiratory reserve volume by $0.09{\ell}$). 2. The longer the time lapsed from supine posture to standing, the patient's expiratory reserve volume, maximum ventilation volume, vital capacity, and forced expiratory volume increased. 3. When the patient lay in supine position, the maximum ventilation volume, vital capacity, and the forced vital capacity increased then the center line of the abdominal band was placed along iliac crest; on the other hand, when the patient was standing, placing the bottom line of the abdominal band along iliac crest increased the maximum ventilation volume, vital capacity, and forced expiratory volume. 4. In placing the abdominal band in the patients, leaving space between the top and bottom lines of the band helped increased in maximum ventilation volume, vital capacity, and forced vital capacity for patient in supine as well as in standing. 5. When placing the abdominal band to patients in supine posture, reducing the length of the band by 2.5% along the patient's waist line increased the patients' vital capacity, while reducing the length by 10% to patients in standing increased the maximum ventilation volume. The abdominal band should be placed in such a way that the bottom part of the band should be more tightly fastened while leaving enough room for a hand to be placed in between the body and the band for the top part of the hand. It should also be noted that in a supine position, the bottom line of the band should be placed along the iliac crest, while in standing, the center line should be placed along the iliac crest. The length of the band should also be reduced by 2.5% of the waist line in supine position, and in standing, the length should be reduced by 10%. It should also be noted that the pulmonary function of the patients should be measured at least 10 minutes after one position change.

• 한국세라믹학회지
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• 제56권6호
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• pp.521-525
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• 2019

A study was conducted to investigate the possibility of a composite material containing a composite resin as a matrix and hydroxyapatite (HAp) powder as a substitute material for tooth repair. As the content of HAp increased, hardness value (111.9 HV at 9%) increased and flexural strength (73.3 MPa at 9%) decreased. Observation of the microstructure after immersion in a simulated body fluid (SBF) solution confirmed a dense structure due to mutual coagulation and curing. It was thought that fine HAp recrystals were formed with the lapse of time, and they were entangled to form a condensation structure and had a dense structure. In addition, since the activity was shown by the ion migration on the surface of a tooth, it was highly likely that a biocompatible bond occurred during tooth contact. Therefore, it could be used as a substitute material for tooth repair.

• 한국식품위생안전성학회지
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• 제10권1호
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• pp.7-12
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• 1995

The inhibitory effects of vegetables, collected from Jinju district, on the growth of Listeria monocytogenes were investigated. Among 12 vegerables, garlic, leek, onion and cabbage were remarkably effective to inhibit the growth of the strain. Especially with the addition of extract equivalent 0.25g of raw garlic per ml broth, the population of the strain was decreased wignificantly, and completely inhibited with the addition of 0.625g or more. During the incubation with the addition of extract equivalent 0.25g of raw garlic per ml broth, the degree of inhibition was gradually increased with the lapse of time, and completely inhibited the growth of the strain after 48 hrs. While the pH value of treated broth remained unchanged almost, those of control were slightly reduced.