• The Korean Journal of Ecology
• /
• v.26 no.4
• /
• pp.165-172
• /
• 2003

The objectives of this study were to examine the physiological responses to ozone and to measure ozone uptake rates of Betula species exposed to relatively high concentration of pollutants. At the end of the growing season, photosynthesis, pigments contents, antioxidants (SOD and GR) and ozone uptake rates were measured or estimated at the leaves of five Betula species (Betula costata, B. davurica, B. platyphylla var. japonica, B. schmidtii and B. ermanii) exposed to 100ppb ozone concentration. On the termination of the experiment, growth effects were determined by measuring leaf area and dry weights of leaf, stem and root. Ozone treatment showed the significant reduction the leaf area and dry weight of four Betula species, except for B. ermanii. Shoot / root (SR) ratio of five species represented two different types. SR ratio of B. costata and B. davurica were lower than control, in contrast, SR ratio of B. platyphylla var. japonica, B. schimidtii and B. emani, were higher than that of control. The photosynthetic responses of five species were different in responses to ozone exposure. Four species, except for B. emanii, maintained or increased the stomatal conductance, but B. emanii decreased both stomatal conductance and photosynthesis. SOD activities of five species decreased by the ozone exposure, especially B. ermanii showed the largest reduction, GR activities of B. platyphylla var. japonica and B. schmidtii increased, B. costata and B. emanii decreased. Instantaneous ozone uptake rate was the highest at the leaves of B. ermanii and B. costata, ozone uptake per seedling was the highest at the leaf of B. schmidtii and B. emanii. It was concluded that B. costata, B. davurica and B. platyphylla var. japonica, appeared the growth reduction and visible ozone injury, were sensitive species to ozone, and B. schmidtii with the increased antioxidant activity and B. ermanii without the growth reduction were relatively resistant species to high ozone concentration at the early growing stage.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.32 no.3
• /
• pp.543-549
• /
• 2005

The maxillary canine is especially important as it has the longest root, provides guidance for lateral movement of the mandible and masticatory function and is a key in esthetics due to its position. Maxillary canine has the longest time to develop and a complex route from the place of formation to the site of eruption, and so it is prone to impaction more than other teeth. The clinician should consider the various treatment options : (a) No treatment and observation, (b) surgical exposure and orthodontic traction (c) autotransplantation (d) extraction. Surgical exposure of the canine and orthodontic treatment to bring the tooth into the line of occlusion is considered the most desirable approach. This case presents the results of treatment for impacted maxillary canine by surgical exposure and orthodontic tooth movement.

• Korean Journal of Soil Science and Fertilizer
• /
• v.50 no.3
• /
• pp.179-186
• /
• 2017

This study was conducted to identify characteristics of domestic pine forest soils and to elucidate major soil influencing factors for natural regeneration. We analyzed the physico-chemical characteristics of the soil samples collected from 23 pine forests and confirmed the similar results with the forest soil characteristics. Soil pH, organic matter content, total nitrogen, exchangeable Ca, silt content, and exchangeable Al were selected as the major soil factors among the exposed soils through 10 days of pine seedlings exposure and cultivation experiments and statistical analysis. Multiple regression analysis showed that soil pH had a positive effect on specific root length (SRL) of red pine seedlings and exchangeable Al was a significant factor affecting negative change in SRL. Taken together, the reduction of exchangeable Al by soil pH adjustment would be helpful for natural regeneration by restoring the forest and improving the fine root and root integrity of pine seedlings. Therefore, soil pH and exchangeable Al could be recommended as a major soil factor to be carefully considered in the monitoring and management of soil in pine forests that need to be renewed in the future.

• Journal of Ginseng Research
• /
• v.20 no.3
• /
• pp.331-338
• /
• 1996

This study was conducted to screen the antagonistic plants on northern root-knot nematode (Meloidogyne) and to utilize those in its control. Egg hatching of M. hapla was found to be inhibited by 17 plant methanol extracts, and 11 plant extracts among them were also toxic to M. hapla second stage juvenile. Egg hatching of iW. hapla was also found to be inhibited by squeezed extracts of Cassia tora and Zea mays, and they were also toxic to M. hapla second stage juvenile. Extracts of Achyranthes japonica, Melia axedrach and Acorus graminens were toxic to M. hapla second stage with a juvenile mortality above 70clc at the 10 folds diluted concent ration and A. graminens was toxic to tested juvenile mortality above 50% at the 100 folds diluted concentration. The toxicity was directly propotional to the diluted concentration of the plant extracts and to the exposure period. Punica granatum, Acorns graminens and Melia axedrach were effective in inhibiting root penetration of JW. hapla juveniles, among of them p. granatum is most effective Percent inhibition of penetration by second and third stage juveniles into tomato slants penetrating by it was 72.7 and 82.4%, respectively.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.19 no.1
• /
• pp.127-136
• /
• 2024

Because the hazardous working environments and high labor intensity of the root industry can potentially impact the health of workers, current regulations have focused on measuring and controlling environmental factors, on a semi-annual basis. However, there is a lack of quantitative criteria addressing workers' health conditions other than the physical work environment. This gap makes it challenging to prevent occupational diseases resulting from continuous exposure to harmful substances below regulatory thresholds. Therefore, this paper proposes a machine learning-based method for determining the peak level of risk in root industry work environments and enables real-time safety assessment in workplaces utilizing this approach.

• Journal of Environmental Health Sciences
• /
• v.48 no.3
• /
• pp.151-158
• /
• 2022

Background: Chemical emissions in the environment have rapidly increased with the accelerated industrialization taking place in recent decades. Residents of industrial complexes are concerned about the health risks posed by chemical exposure. Objectives: This study was performed to suggest modeling methods that take into account multimedia and multi-pathways in human exposure and risk assessment. Methods: The concentration of benzene emitted at industrial complexes in Daesan, South Korea and the exposure of local residents was estimated using the Caltox model. The amount of human exposure based on inhalation rate was stochastically predicted for various activity stages such as resting, normal walking, and fast walking. Results: The coefficient of determination (R²) for the CalTOX model efficiency was 0.9676 and the root-mean-square error (RMSE) was 0.0035, indicating good agreement between predictions and measurements. However, the efficiency index (EI) appeared to be a negative value at -1094.4997. This can be explained as the atmospheric concentration being calculated only from the emissions from industrial facilities in the study area. In the human exposure assessment, the higher the inhalation rate percentile value, the higher the inhalation rate and lifetime average daily dose (LADD) at each activity step. Conclusions: Prediction using the Caltox model might be appropriate for comparing with actual measurements. The LADD of females was higher ratio with an increase in inhalation rate than those of males. This finding would imply that females may be more susceptible to benzene as their inhalation rate increases.

• Advances in concrete construction
• /
• v.16 no.3
• /
• pp.155-167
• /
• 2023

The penetrated chloride in concrete has different behavior with mix proportions and local exposure conditions, even in the same environments, so that it is very important to quantify surface chloride contents for durability design. As well known, the surface chloride content which is a key parameter like external loading in structural safety design increases with exposure period. In this study, concrete samples containing OPC (Ordinary Portland Cement), GGBFS (Ground Granulated Blast Furnace Slag), and FA (Fly Ash) had been exposed to submerged, tidal, and splash area for 5 years, then the surface chloride contents changing with exposure period were evaluated. The surface chloride contents were obtained from the chloride profile based on the Fick's 2nd Law, and the regression analysis for them was performed with exponential and square root function. After exposure period of 5 years in submerged and tidal area conditions, the surface chloride content of OPC concrete increased to 6.4 kg/m³ - 7.3 kg/m³, and the surface chloride content of GGBFS concrete was evaluated as 7.3 kg/m³ - 11.5 kg/m³. In the higher replacement ratio of GGBFS, the higher surface chloride contents were evaluated. The surface chloride content in FA concrete showed a range of 6.7 kg/m³ to 9.9 kg/m³, which was the intermediate level of OPC and GGBFS concrete. In the case of splash area, the surface chloride contents in all specimens were from 0.59 kg/m³ to 0.75 kg/m³, which was the lowest of all exposure conditions. Experimental constants available for durability design of chloride ingress were derived through regression analysis over exposure period. In the concrete with GGBFS replacement ratio of 50%, the increase rate of surface chloride contents decreased rapidly as the water to binder ratio increased.

• Parasites, Hosts and Diseases
• /
• v.54 no.1
• /
• pp.61-66
• /
• 2016

It has been known that Arak, Salvadora persica, has a number of medicinal properties. We tried to investigate in vitro scolicidal effect of root extracts of this plant against protoscolices from hydatid cysts of Echinococcus granulosus. Protoscolices were aseptically collected from sheep livers containing hydatid cysts. S. persica root extract was used in 10, 30, and 50 mg/ml concentration for 10, 20, and 30 min. The viability of protoscolices was ascertained by 0.1% eosin staining. Scolicidal activity of S. persica extract at a concentration of 10 mg/ml was 36.3%, 50.3%, and 70.8% after 10, 20, and 30 min of exposure, respectively. The scolicidal effect of this extract at a concentration of 30 mg/ml was 52.9%, 86.7%, and 100% after 10, 20, and 30 min of exposure, respectively. S. persica extract at a concentration of 50 mg/ml, meanwhile, killed 81.4%, 100%, and 100% of protoscolices after 10, 20, and 30 min, respectively. Also, the cytotoxic potential of S. persica was assessed on human liver cells (HepG2) using trypan blue exclusion test. No cytotoxic effect was observed on HepG2 cell line. The present study confirmed for the first time that the ethanolic extract of S. persica has high scolicidal power in vitro. However, in vivo effect of this material remains to be studied for treatment of echinococcosis in humans and herbivorous animals.

• The Journal of Korean Academy of Prosthodontics
• /
• v.32 no.3
• /
• pp.455-469
• /
• 1994

Regular radiographic examination has been considered an essential diagnositic method for osseointegrated dental implantation. This study investigated marginal bone loss through the measurement on periapical radiographs and changes in bone density through digital subtraction image radiographic method around 88 endoseous root-form dental implants in 43 human subjects. Four types of endosseous dental implants were investigated : Standard series, Mini series and Hex-lock system of Steri-Oss Dental implant system, and $Br{\aa}nemark$-type implant from 3i dental implant system, in a 3 month interval for a total period of 12 months. The results were as follows : 1. Rapid bone loss occurred in the first 3 months in all 4 groups, and the bone level stabilized at the first thread of the implant fixtures. Amount of bone loss for 12 months showed correlation with the length of the polished neck portion. 2. Most of the implant systems showed resorption of alveolar bone up to the polished neck portion although a long polished neck could delay the resolution. 3. Alveolar bone loss apical to the polished neck portion stabilized at the first thread of the fixtures with no correlation to either the time of exposure of the polished neck or types of implant systems. 4. No changes in bone density around the implant threads were observed throughout the experimental period. Bone density decreased at the marginal bone, and increased at the newly-formed alveolar crest. These results indicate that most of the alveolar bone loss occur within the first 12 months after installation of endosseous root-form dental implants resulting in the exposure of polished neck portions, and the bone level stabilizes thereafter at the first thread portions of the implant fixtures. The experimental period of 12 months seems insufficient for observing changes in bone density, and a long-term observation should be needed.

• Journal of Periodontal and Implant Science
• /
• v.29 no.4
• /
• pp.847-863
• /
• 1999

The present study was performed to evaluate the effect of EDTA on diseased root surfaces with regard to the removal of the smear layer, exposure of dentinal tubule openings, and demineralization of the peritubular dentin. 20 periodontally involved single rooted teeth were used. After scaling and root planing, root conditioning was carried out with 3%, 17%, and 24% EDTA solution for 20 sec., 3 min., and 5 min. respectively. Then, the specimens were rinsed with tap water for 5 min. and processed for scanning electron microscopic observation. The following results were obtained. 1. In control group which was conditioned with cotton pellets soaked with saline for 3 min., the surface showed an amorphous irregular coating. The tubule orifices seemed to be com-pressed in the direction of the curette strokes. 2. In test group which was conditioned with EDTA solution, the number of opening dentinal tubules and the extent of the dentinal tubule opening increased with time irrespective of the concentration of EDTA solution. 3. In the group which was conditioned with EDTA solution for 20 sec., the smear layer was not completely removed. 4. If the time of root conditioning is above 3 min., collagen-like fibers covering the circum tubular dentin surface were shown even in the group which was conditioned with 3% EDTA solution. In conclusion, EDTA solution was a very effective root conditioning agent like low pH root conditioning agents which had various disadvantages. Therefore, using EDTA solution, more successful periodontal regeneration could be obtained.