• 한국재료학회지
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• 제15권6호
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• pp.370-374
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• 2005

Doppler broadening spectrometer for positron annihilation experiment(DBPAS) has been used to characterize nano size defect structures in materials. DBPAS measures the concentration, spatial distribution, and size of open volume defects in the rare-earth intensifying screen materials. The screens were exposed by X-ray varying the exposed doses from 3, 6, 9, and 12 Gy with 6 W and 15 MV respectively and also irradiated by 37 MeV proton beams ranging from 0 to $10^{12}ptls$. The S parameter values increased as the exposed time and the energies increased, which indicated the defects were generated more. The S parameters of the samples with X-rays varied from 0.5098 to 0.5108, on the other hand, as proton beams varied from 0.4804 to 0.4821.

• 한국수산과학회지
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• 제36권5호
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• pp.463-468
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• 2003

This study observed change of survival rate, activity and foot structure of the equilateral venus (Gomphina veneriformis) exposed to cadmium. Survival rate and activity of the clam exposed to cadmium was reduced with increase of exposure duration and concentration. Change of survival rate and activity was observed in the early exposure time (7 days) in the condition of above 1 77 mg/L and 0.88 mg/L, respectively. Activity reduction of the clam exposed to cadmium seems to be caused by epidermal layer deformation, muscle fiber fragmentation and muscular layer collapse of the foot.

• 환경위생공학
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• 제11권3호
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• pp.1-7
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• 1996

Mandelic acid is the major metabolite and phenylglyoxylic acid is the minor metabolite of styrene in human. This study was conducted to investigate the correlation between exposure concentrations of styrene and concentration of the metabolites in urine The concentrations of metabolites in urine and exposure concentrations were measured in 60 workers who were occupationally exposed to styrene in FRP industry as well as paint industry and musical instrument manufacturing industry and the concentrations of metabolites in urine ware measured in 90 workers not occupationally exposed to styrene for review the background level in the unexposed population. The results obtained were as follows; 1. The mean exposure concentration is 16.6 $\pm $12.2 ppm (range 0.4-49.9ppm) in the styrene exposed workers. 2. The concentration of mandelic acid in urine collected at the end of shift from worker exposed 8 hours to 50ppm of styrene, based on extrapolation from correlation equations was 578.5 mg/g creatinine and 176.8 mg/g creatinine for next morning urine, the concentration of phenylglyoxylic acid in urine collected at the end of shift was 291.1 mg/g creatinine, 177.9 mg/g creatinine in next morning urine. In the sum of mandelic acid and phenylglyoxylic acid in the urine 870.2 mg/g creatinine in urine sampled at the end of shift corresponds to an exposure of 50ppm of styrene and 366.0 mg/g creatinine for next morning sample corresponds to 50ppm. 3. The correlation of the degree of exposed with sum concentration of mandeliacid and phenylglyoxylic acid in the urine was better(r=0.079 for end of shift, r=0.78 for next morning) than the correlation with single determinant measurement in urine(r=0.75 for mandelic acid at end of shift, r=0.73 for mandelic acid at next morning, r=0.69 for phenylglyoxylic acid at end of shift, r=0.62 for phenylglyoxylic acid at next morning). The monitoring of sum concentration of mandelic acid and phenylglyoxylic acid in urine is a valuable indicator of time weighted average daily exposure ti styrene. And the exposure standard of urinary metabolites produced by styrene should be set, in distinction urine at the end of shift from urine at next morning.

• Coupled systems mechanics
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• 제9권2호
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• pp.163-182
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• 2020

Coupled thermo-mechanical analysis of reinforced concrete slab at elevated temperatures from a fire accounting for nonlinear thermal parameters is carried out. The main focus of the paper is put on a one-way continuous reinforced concrete slab exposed to fire from the single (bottom) side as the most typical working condition under fire loading. Although contemporary techniques alongside the fire protection measures are in constant development, in most cases it is not possible to avoid the material deterioration particularly nearby the exposed surface from a fire. Thereby the structural fire resistance of reinforced concrete slabs is mostly influenced by a relative distance between reinforcement and the exposed surface. A parametric study with variable concrete cover ranging from 15 mm to 35 mm is performed. As the first part of a one-way coupled thermo-mechanical analysis, transient nonlinear heat transfer analysis is performed by applying the net heat flux on the exposed surface. The solution of proposed heat analysis is obtained at certain time steps of interest by α-method using the explicit Euler time-integration scheme. Spatial discretization is done by the finite element method using a 1D 2-noded truss element with the temperature nodal values as unknowns. The obtained results in terms of temperature field inside the element are compared with available numerical and experimental results. A high level of agreement can be observed, implying the proposed model capable of describing the temperature field during a fire. Accompanying thermal analysis, mechanical analysis is performed in two ways. Firstly, using the guidelines given in Eurocode 2 - Part 1-2 resulting in the fire resistance rating for the aforementioned concrete cover values. The second way is a fully numerical coupled analysis carried out in general-purpose finite element software DIANA FEA. Both approaches indicate structural fire behavior similar to those observed in large-scale fire tests.

• 보건교육건강증진학회지
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• 제16권1호
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• pp.127-135
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• 1999

The purpose of this study was to verify the effects of the developed exercise prescription program by utilizing PRECEDE(Predisposing, Reinforcing, and Enabling Causes in Educational Diagnosis and Evaluation} model on adult's knowledge related to health, attitudes, behaviors and serum lipoprotein values. This study employed 20 males(40-47 yrs) without any apparent physical defects, who did not experience such physical activities. They were divided into experimental groups and control groups, each group consisted of 10 subjects who performed Jogging. The experimental design of the study utilized “two-way ANOVA Design” conducted by the repeated measurement two time(pre and post-test). As the results of the data, the conclusions were as follows: 1. There were statistically significant effects of the health module exposed to the experimental groups on the higher means of knowledge score in the experimental groups than those in the control groups. 2. There were statistically significant effects of the module exposed to the experimental groups on the positive changes of their attitudes. 3. There were significant changes on the behaviors of the health by doing the health program. Therefore the developed health program formed the improved knowledge about the health and the desirable attitudes and behaviors. 4. There were statistically significant effects of the exercise prescription program exposed to the experimental groups on the reduction of the resting heart rate and systolic blood pressure. 5. There were statistically significant effects of the exercise prescription program exposed to the experimental groups on the positive changes of their plasma TC / HDL-C ratio and triglycerides.

• Journal of Preventive Medicine and Public Health
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• 제27권3호
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• pp.557-567
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• 1994

This study was conducted to examine the effect of chronic low dose organic solvent exposures in the industries towards then neurobehavioral functions of workers. Subjective symptoms on neurobehavioral function as well as a visual reaction time test (Flicker test) were administered to 94 exposed and 162 unexposed workers in a oil refinery and some other auto-repair shops. The results obtained were as follows : 1. Symptom complaints were higher and Flicker test values were lower in exposed workers than in unexposed workers. 2. Flicker valus were Inversely correlated with urinary Hippuric acid concentration in exposed workers(r=-0.26, p<0.05). 3. Flicker valus were inversely co..elated with Subjective symptom score(r=-0.15, p<0.05). Low Flicker value were also related with some subjetive symptoms such as 'Dimmed vision', 'Nightmare', 'Weakness on extrimity' in workers as a whole. While symptoms of 'Dimmed vision ', 'Nightmare' only observed among exposed workers.

• Restorative Dentistry and Endodontics
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• 제12권2호
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• pp.73-80
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• 1987

The present study was designed to help elucidate the effect of glass ionomer cements on the exposed dental pulp by means of histologic examination. A total of 40 cavities of class V were prepared on the teeth of 4 dogs with exposure of 1mm in diameter on the bases of them. 20 cavities were filled with glass ionomer cement as the experimental group and the other 20 cavities were filled with zinc oxide eugenol cement as the control group. The dogs were sacrificed at one, two, three, and four weeks after filling, and the specimens were routinely prepared and stained with Hematoxylin-Eosin. The obtained microscopic findings were as follows: Inflammatory cell infiltrations were observed in control in 1 week, which decreased markedly with time. In all control groups, hemorrhage around exposed pulp tissue and coagulation change of pulp were observed. Secondary dentin formation and thickened predentin were observed in 4 week cases, and the recovery of pulp tissue was favorable on the whole. Inflammatory cell infiltration was observed in all GIC groups. Proliferation of blood vessel and congestion were observed with coagulation changes around the exposed pulp tissue. Secondary dentin formation and thickened predentin were observed in 3 weeks. In the experimental 4 week case, secondary dentin formation was evident. On the whole, pulpal irritation of glass ionomer cement was relatively severe. Recovery of pulp tissue in GIC groups was less favorable compared with that of ZOE groups.

• Forest Science and Technology
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• 제14권4호
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• pp.153-159
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• 2018

Seedlings of Pterocarpus indicus were grown in both well-watered and drought stress conditions in phytotron. Seedlings grown under well-watered and drought stress conditions were exposed to either combined or without ozone of 200 ppb for one month. First, the physiological responses to elevated ozone levels indicated a decreased biomass. The seedlings grown in arid soil and exposed to ozone showed less biomass than those grown in arid soil but not exposed to ozone. Moreover, all the seedlings except the well-watered and unexposed ones showed a significantly lower photosynthetic rate ($P_N$) over time. However, with the accumulation of ozone injuries, the antioxidant enzyme activities increased overall. In the study results, when exposed to ozone, the well-watered seedlings exhibited more antioxidative enzyme activity than did the seedlings grown in arid soil. Generally, P. indicus in arid soil suffered less damage from elevated ozone than did the well-watered plants.

• 한국동물위생학회지
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• 제21권1호
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• pp.41-56
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• 1998

These experiment was carried out to investigate the pulmonary lesions and the function of alveolar macrophages in rats exposed to cement dusts. 1. The number of total cells in bronchoalveolar lavage fluid(BAL) increased remarkably in 1st month. As time goes by, tend to less and less in numbers. 2. The number of neutrophil and lymphocytes obtaining from the total cell of BAL increased remarkably in first month, but as time goes by, they tended to grow less and less in number. Macrophages decreased gradually after being temporarily augmentation. 3. Histipathologically, the thickening of alveolar walls, alveolar interstitial, and infiltrated macrophages containing cement dusts.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.560-572
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• 2004

Aeroelastic response and control of airfoil-flap system exposed to sonic-boom, blast and gust loads in an incompressible subsonic flowfield are addressed. Analytical analysis and pertinent numerical simulations of the aeroelastic response of 3-DOF airfoil featuring plunging-pitching-flapping coupled motion subjected to gust and explosive pressures in terms of important characteristic parameters specifying configuration envelope are presented. The comparisons of uncontrolled aeroelastic response with controlled one of the wing obtained by feedback control methodology are supplied, which is implemented through the flap torque to suppress the flutter instability and enhance the subcritical aeroelastic response to time-dependent excitations.