• Environmental Analysis Health and Toxicology
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• v.17 no.3
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• pp.219-224
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• 2002

This study was carried out to examine the effects of bis (tribytyltin)oxide (TBT), endocrine disrupting compounds (EDCs). on the changes of survival, growth and oxygen consumption rate in the oliver flounder, Paralichthys olivaceus. Oliver Flounders were exposed to sublethal concentration of TBT (0, 1.67, 3.20, 6.30 and 12.50 $\mu\textrm{g}$/L) during 6 weeks. Survival rate was decreased in a concentration and exposure period-dependent way and suddenly the reduction of more than 20% occurred at TBT concentration greater than 3.20 $\mu\textrm{g}$/L. after exposure 6 weeks. Growth rate and feed efficiency significantly decreased at concentration greater than 3.20 $\mu\textrm{g}$/L. Oxygen consumption rate was also decreased in a concentration-dependent way and significantly decreased to 17,48 and 67％ than that of the control at the TBT concentration of 3.20, 6.32 and 12.50 $\mu\textrm{g}$/L, respectively. This study revealed that high TBT concentration ($\geq$3.20 $\mu\textrm{g}$/L) reduced growth and oxygen consumption rates of the juvenile oliver flounder suggesting potential influence on the natural mortality of Paralichthys olivaceus in the coastal areas.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.214-215
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• 2007

Etch rates and surface chemistry of phenol formaldehyde-based photoresist after short time $O_2\;and\;N_2O$ radio frequency (RF) plasma treatment depending on exposure time were investigated. It was found that the etch rate of photoresist sharply increased after discharge turn on and reached a limit with increase in plasma exposure time in both gases. X-ray photoelectron spectroscopy (XPS) analysis showed that the surface chemical structure become nearly constant after the treatment of 15 sec. Concentration of surface oxygen-containing groups after processing both in oxygen and in $N_2O$ plasmas is similar.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.43-43
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• 2010

We have characterized the parametric and functional properties of live cell and cancer cell according to plasma treatment conditions using Atmospheric Pressure (AP) Plasma with uniquely designed low temperature arc-free unit. AP plasma system showed very highly efficient capabilities of reacting and interfacing directly with live and cancer cells. The parametric results with the types of gases, applied power, applied gap, and process times on cells will be presented in accordance with functional studies of the works. The growth of cancer cells is directly influenced by AP plasma exposure with evaluating plasma conditions in several human cancer cells and understanding how plasma exposure alters molecular signaling pathways. The cells exhibit a slower or faster growth rates compared with untreated cells, depending on the cell types. These results strongly support the conclusion that alterations in one or more of each gene are responsible, at least in part, for plasma-induced apoptosis in cancer cells. In addition, it also will be presented that AP plasma has an important role for the improvement of sensor performance due to excellent interface property between enzyme and metal electrode for bio sensor manufacturing process.

• Corrosion Science and Technology
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• v.21 no.4
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• pp.258-272
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• 2022

Steel structures exposed to the outdoors experienced several types of corrosion, which may reduce their thickness. Since atmospheric corrosion can induce economic losses, it is important to consider the atmospheric corrosion behavior of a variety of metals and alloys. This work performed outdoor exposure tests for 10 years at 14 areas in Korea and calculated the atmospheric corrosion rate of weathering steel. This paper discussed the atmospheric corrosion behavior of weathering steel based on various corrosion factors. The average corrosion rates in coastal, industrial, urban, and rural areas were found to range from (2.83 to 4.23) ㎛/y, (2.99 to 4.23) ㎛/y, (1.72 to 3.14) ㎛/y, and (1.57 to 2.85) ㎛/y respectively. It should be noted that the maximum corrosion rate was about 6.0 times greater than the average corrosion rate. Regardless of the exposure sites, the color differences were increased, but the glossiness was reduced and there was no relationship between the corrosion rate and environmental factors and the glossiness.

• Journal of Gastric Cancer
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• v.24 no.1
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• pp.99-107
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• 2024

Gastric cancer has been consistently decreasing worldwide, whereas cardia gastric cancer is on the rise. This indicates that the exposure rates to epidemiological causes are changing. In this study, we aim to review the risk factors for gastric cancer with respect to cardia and non-cardia types. One of the most significant risk factors for gastric cancer is Helicobacter pylori infection. H. pylori infection is known as a risk factor for non-cardia gastric cancer, and there have been results indicating that H. pylori infection is not associated with cardia gastric cancer. However, in the East Asian region, there is epidemiological evidence suggesting that H. pylori infection might be a risk factor for cardia gastric cancer. Smoking and alcohol consumption are known risk factors for gastric cancer, regardless of anatomical location. Obesity is considered a factor in the development of cardia gastric cancer. However, further research is needed to understand the specific relationship with non-cardia gastric cancer. The consumption of high-salt and processed meat is more distinctly associated with noncardia gastric cancer than in cardia gastric cancer. In addition to these factors, exposure to chemicals and radiation are considered risk factors for gastric cancer. Primary prevention of gastric cancer involves eliminating or avoiding risk factors such as H. pylori eradication and adopting a healthy lifestyle, including quitting smoking, reducing alcohol consumption, maintaining a healthy weight, and having a low-salt diet.

• Advances in nano research
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• v.17 no.1
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• pp.75-86
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• 2024

The insecticidal efficiency of orange (Citrus sinensis) peel essential oil (OP-EO) is limited because of its low stability under environmental conditions. Nanoemulsion formulations show promise in overcoming this limitation. Therefore, this study aimed to formulate and characterize the OP-EO nanoemulsion form (OP-EON) and investigate its insecticidal properties against two significant storage pests, Rhyzopertha dominica (Fabricius, 1792), and Tribolium castaneum (Herbst, 1797). The OP-EON (4:3:3:90 w/w, EO: Tween 80: Ethanol: water) was successfully created using an ultrasonic homogenizer. The major chemical components of the OP-EO were determined to be D-limonene (87.93%), myrcene (3.62%), and α-pinene (1.34%) through GC-MS analysis. The OP-EON was characterized using TEM (50-100 nm), Zeta sizer (the mean droplet particle size of 58.60 nm, the ζ-potential value of -12.6 mV, and the polydispersity index of 0.486), and FT-IR analysis. After 7 days, exposure to 500 ppm of the OP-EON resulted in 50% and 30% mortality rates in R. dominica and T. castaneum, respectively. Exposure to 1000 ppm of OP-EON resulted in 90% and 55% mortality in R. dominica and T. castaneum, respectively, after 7 days. Overall, these results clearly showed the potential to exceed the limits of the insecticidal activity of the OP-EO with its nanoemulsion form.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.1
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• pp.9-17
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• 2004

Objective: The aim of this study were to compare the effects of EG and PROH on cryopreservation of mouse and human embryos, and to find the optimal protocol for embryo freezing. Methods: Human embryos derived from fertilized eggs showing 3 pronuclei (PN) and mouse embryos were divided into two groups respectively: dehydrated with 1.5 M EG + 0.2 M sucrose or 1.5 M PROH + 0.2 M sucrose using the slow freezing method. Moreover mouse embryos were controlled the exposure time of cryoprotectant during dehydration or rehydration steps. Results: The survival rates of human embryos were 79.2% (84/106) in EG group and 77.9% (88/113) in PROH group. In mouse embryos, the survival and development rates up to blastocyst were 70.6% (245/347), 44.1% (123/279) in EG group and 62.1% (198/319), 45.1% (123/279) in PROH group, respectively. However, in EG group, partially damaged embryos after thawing were decreased compared to PROH group. In combination group, when the exposure time during dehydration and rehydration were reduced, the survival and embryonic developments were increased slightly, but not significant. Conclusion: Cryopreservation of mouse and human embryos at cleavage stage by using EG or PROH exhibited no statistical difference in the survival rate and/or developmental rate to blastocyst. However, the use of EG for cryopreservation of embryos might reduce the exposure time of the cryoprotectant because of a high permeation of EG and result in lessen its toxic effects.

• Journal of Radiation Protection and Research
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• v.44 no.4
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• pp.128-148
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• 2019

Massive environmental monitoring has been conducted continuously since the Fukushima Daiichi Nuclear Power accident in March of 2011 by different monitoring methods that have different features together with migration studies of radiocesium in diverse environments. These results have clarified the characteristics of radiological environments and their temporal change around the Fukushima site. At three months after the accident, multiple radionuclides including radiostrontium and plutonium were detected in many locations; and it was confirmed that radiocesium was most important from the viewpoint of long-term exposure. Radiation levels around the Fukushima site have decreased greatly over time. The decreasing trend was found to change variously according to local conditions. The air dose rates in environments related to human living have decreased faster than expected from radioactive decay by a factor of 2-3 on average; those in pure forest have decreased more closely to physical decay. The main causes of air dose rate reduction were judged to be radioactive decay, movement of radiocesium in vertical and horizontal directions, and decontamination. Land-use categories and human activities have significantly affected the reduction tendency. Difference in the air dose rate reduction trends can be explained qualitatively according to the knowledge obtained in radiocesium migration studies; whereas, the quantitative explanation for individual sites is an important future challenge. The ecological half-lives of air dose rates have been evaluated by several researchers, and a short-term half-life within 1 year was commonly observed in the studies. An empirical model for predicting air dose rate distribution was developed based on statistical analysis of an extensive car-borne survey dataset, which enabled the prediction with confidence intervals. Different types of contamination maps were integrated to better quantify the spatial data. The obtained data were used for extended studies such as for identifying the main reactor that caused the contamination of arbitrary regions and developing standard procedures for environmental measurement and sampling. Annual external exposure doses for residents who intended to return to their homes were estimated as within a few millisieverts. Different forms of environmental data and knowledge have been provided for wide spectrum of people. Diverse aspects of lessons learned from the Fukushima accident, including practical ones, must be passed on to future generations.

• Reproductive and Developmental Biology
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• v.30 no.1
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• pp.41-45
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• 2006

Electrical treatment has been widely used for porcine oocytes activation. However, developmental rates following electrical activation of porcine oocytes is relatively inefficient compared to other domestic animals. To investigate the effects of porcine oocytes on combined activation by both chemical and electrical treatment, in-vitro matured oocytes were activated by combined cycloheximide and electrical pulses treatment. Cumulus-free oocytes were exposed with NCSU-23 medium containing cycloheximide $(10{\mu}g/ml)$ for 0, 5, 10, 20, 30 min and then activated by electrical pulse treatment and cultured in PZM-3 for 8 days. Also effects of exposure to $6.25{\mu}M$ calcium ionophore for 2 min for cumulus-free oocytes were tested. The percentage of blastocyst formation in 10 min exposure to $10{\mu}g/ml$ cycloheximide and electrical pulse treatment was significantly increased (P<0.05) than in the control group. And exposure to $6.25{\mu}M$ calcium ionophore for 2 min with $10{\mu}g/ml$ cycloheximide for 10min and electrical pulse treatment significantly increased (P<0.05) the percentage of blastocyst developmental rates than the control group. In conclusion, activation by combined cycloheximide and electrical stimulation treatment promoted the subsequent development of porcine oocytes and improved the subsequence blastocyst development.

• The Korean Journal of Pesticide Science
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• v.11 no.2
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• pp.87-94
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• 2007

Pyrethroid insecticide have widely been used for agricultural sector and residential environments. To assess the exposure of insecticide which is absorbed through skin the analysis of urinary metabolite is essential. At present, the urinary 3-PBA was analyzed using liquid-phase extraction. But LPE have many limitations, such as long pre-treatment time and low recovery. So, this study was conducted to determine the optimum conditions for analysing 3-PBA in urine using solid phase extraction. Furthermore, this study intend to investigate the relation of concentrations of pyrethroid, deltamethrin in air and 3-PBA in urine. The optimum condition for hydrolysis was found to be done with hydrochloric acid for one hour. The recovery rates of 3-PBA were $84.6%{\pm}1.2%$, $54.8{\pm}0.9%$, $99.8{\pm}1.2%$ with XAD-2, XAD-7, XAD-16 using as the aborbents and acetone as eluents respectively. But acetonitrle and methanol gave low recovery rate and methyl cellosolve could not elute the compound. The amount of acetone for elution were 6mL, 9mL, 3mL for XAD-2, XAD-7, XAD-16 as absorbents respectively. The non-absorbed rates was $0.8{\pm}0.5%$, and $0.7{\pm}0.3%$ under XAD-16, mesh size 140-200, amount of resin 1.4g and the flow rate of eluent was 0.1mL/min. In the concentration process, we obtained 11 times higher concentration of material. The amounts of urinary 3-PBA were. The LODs of 3-PBA and deltamethrin were 0.004 mg/L, 0.038 mg/L, respectively. The further research of minute monitoring which include spray pattern, environmental condition is needed And more research about the relation between total pyrethroid exposure and urinary various metabolite are also necessary.