• ALGAE
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• v.22 no.3
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• pp.241-246
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• 2007

Cochtodinium votykrikoides -related red tide is the most notorious tidal bloom, resulting in mass mortality to marineanimals. This study aimed to test the effect of C. polyknkoides on the lethality to Haliotis discus hannai under con-trolled conditions. The oxygen demand of C. polykrikoides increases to reach its peak duhng the night, while the oxy-gen usage by H. discus hannai was continuously decreased with a threshold of 2 mg L U. The addition of C.polykrikoides did not effect the respiration of the H. discus hannai. However, the usage of oxygen by C. polykrikoidesduhng the night may lead to anoxia in the animal. With aeration, the level of dissolved oxygen (D.O.) was between6.06 and 7.28 mg LU; 90% of abalones survived even with a high concentration of C. potykrikoides (9000 cells mL U).Without aeration (3 mg LU of D.O.), however, the H. discus hannai suffocated immediately. Once 20 hours hadelapsed, all of the abalones were dead. The density of the H. discus hannai population contributed to their mortality.Therefore, aeration during the night and maintaining lower abalone densities is the best way to promote the sur-vivorship of H. discus hannai during a C. polykrikoides red tide.

• Korean Journal of Materials Research
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• v.15 no.8
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• pp.514-517
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• 2005

Effects of nitrogen and oxygen annealing on the carrier concentration, carrier mobility, electrical resistivity and PL characteristics as well as the crystallinity of ZnO films deposited on sapphire substrates by atomic layer deposition (ALD). X-ray diffraction (XRD), Scanning electron microscope (SEM), photoluminescence (PL) analyses, and Hall measurement were performed to investigate the crystallinity, optical properties and electrical properties of the ZnO thin films, respectively. According to the XRD analysis results the crystallinity of the ZnO film annealed in an oxygen atmosphere is better than that of the ZnO film annealed in a nitrogen atmosphere. Annealing undoped ZnO films grown by ALD at a high temperature above $600^{\circ}C$ improves the crystallinity and enhances W emission but deteriorates the electrical conductivity of the flms. The resistivity of the ZnO film annealed particularly at $800^[\circ}C$ in a nitrogen atmosphere is much higher than that annealed at the same temperature in an oxygen atmosphere.

• Journal of Environmental Science International
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• v.22 no.7
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• pp.915-923
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• 2013

Decomposition of non-biodegradable contaminants such as phenol contained in water was investigated using a dielectric barrier discharge (DBD) plasma reactor in the aqueous solutions with continuous oxygen bubbling. Effects of various parameters on the removal of phenol in aqueous solution with high-voltage streamer discharge plasma are studied. In order to choose plasma gas, gas of three types (argon, air, oxygen) were investigated. After the selection of gas, effects of 1st voltage (80 ~ 220 V), oxygen flow rate (2 ~ 7 L/min), pH (3 ~ 11), and initial phenol concentration (12.5 ~ 100.0 mg/L) on phenol degradation and change of $UV_{254}$ absorbance were investigated. Absorbance of $UV_{254}$ can be used as an indirect indicator of phenol degradation and the generation and disappearance of the non-biodegradable organic compounds. Removal of phenol and COD were found to follow pseudo first-order kinetics. The removal rate constants for phenol and COD of phenol were $5.204{\times}10^{-1}min^{-1}$ and $3.26{\times}10^{-2}min^{-1}$, respectively.

• Transactions on Electrical and Electronic Materials
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• v.7 no.4
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• pp.204-209
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• 2006

Photo Resist (PR) ashing process was carried out with the atmospheric pressure- dielectric barrier discharge (ADBD) using $SF_6/N_2/O_2$. Ashing rate (AR) was sensitive to the mixing ratio of the oxygen and nitrogen of the blower type of ADBD asher. The maximum AR of 5000 A/min was achieved at 2% of oxygen in the $N_2$ plasma. With increasing the oxygen concentration to more than 2% in the $N_2$ plasma, the discharge becomes weak due to the high electron affinity of oxygen, resulting in the decrease of AR. When adding 0.5% of SF6 to $O_2/N_2$ mixed plasma, the PR AR increased drastically to 9000 A/min and the ashed surface of PR was smoother compared to the processed surface without $SF_6$. Carbon Fluorinated polymer may passivate the PR surface. It was also observed that the glass surface was not damaged by the fluorine.

• Computers and Concrete
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• v.16 no.2
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• pp.261-274
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• 2015

This study established the standard recommended values and expansion fracture threshold values for the content of steel slag in controlled low-strength materials (CLSM) to ensure the appropriate use of steel slag aggregates and the prevention of abnormal expansion. The steel slags used in this study included basic oxygen furnace (BOF) slag and desulfurization slag (DS), which replaced 5-50% of natural river sand by weight in cement mixtures. The steel slag mortars were tested by high-temperature ($100^{\circ}C$) curing for 96 h and autoclave expansion. The results showed that the effects of the steel slag content varied based on the free lime (f-CaO) content. No more than 30% of the natural river sand should be replaced with steel slag to avoid fracture failure. The expansion fracture threshold value was 0.10%, above which there was a risk of potential failure. Based on the scanning electron microscopy (SEM) analysis, the high-temperature catalysis resulted in the immediate extrusion of peripheral hydration products from the calcium hydroxide crystals, leading to a local stress concentration and, eventually, deformation and cracking.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.3
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• pp.286-292
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• 2016

Objectives: This study aimed to evaluate the effects of chronical exposure to high-level dusts on cellular immune function. Methods: The subjects were 110 male workers, among whom 60 were chronically exposed to high-level dusts in mica, limestone and iron mines. The remaining 50 were office workers. Ambient total, respirable dust and crystalline silica in the workplace were sampled using personal air samplers and analyzed according to NIOSH method 0500. Serum levels of hydrogen peroxide, lipid peroxide and superoxide misutase activity were measured using absorption chromatography. The subpopulations of CD4+, CD8+, natural killer cells (CD16+) and CD3+ T-lymphocytes were examined by two-color staining using monoclonal antibodies. Results: The concentration of hydrogen peroxide was significantly higher in exposed workers and superoxide dismutase activity was significantly higher in control workers. No significant difference in numbers of T-lymphocyte subpopulations were observed between exposed and control workers. A significant correlation in exposed workers was observed among total dusts, respirable dusts and crystalline silica. Hydrogen peroxide was significantly correlated with total dust (r=0.720, p<0.01), respirable dust (r=0.770, p<0.01) and crystalline silica (r=0.678, p<0.01). Concentration of hydrogen peroxide showed a significantly negative correlation with numbers of CD8+ cells (r=-0.274, p<0.01), CD3+ cells (r=-0.222, p<0.01) and natural killer cells (r=-0.556, p<0.01). Conclusions: These results suggest that chronical exposure to high-level dust affects cellular immune function and effects might mediate through reactive oxygen species and inflammatory response.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.6
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• pp.811-817
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• 2013

A two-stage bioreactor system using sulfur-oxidizing bacteria was studied to abate high strength hydrogen sulfide ($H_2S$) from biogas. The two-stage bioreactor consisted of a $H_2S$ absorption column (0.5 L) and a microbial oxidation column (1 L) in series, and the liquid medium was continuously recirculated through the columns. The objectives of this study were to determine the feasibility of the bioreactor for biogas desulfurization and to investigate the effect of the medium circulation rate on the system performance. An averaged concentration of $H_2S$ introduced to the bioreactor was 530 ppm, corresponding to an overall loading rate of $44.4g/m^3/hr$. During the initial 20 days period at the medium recirculation rate of 8 reactor volumes per hour (12 L/hr), the dissolved oxygen (DO) concentration in the oxidation column was 6 mg/L, while the DO in the absorption column was 0.5 mg/L showing that the oxygen contents of the biogas stream was not altered. Because of the biological oxidation of $H_2S$ in the oxidation column, the sulfate concentration increased from 200 mg/L to 5,600 mg/L in the liquid medium. The removal efficiency of $H_2S$ was greater than 99% in the initial operation period. After the initial period, the medium recirculation rate between the two columns was stepwise changed eight times from 1.0 to 40 vol/hr (1.5~60 L/hr). At the recirculation rate of faster than 4 vol/hr, the $H_2S$ removal efficiencies were found to be high, but the efficiency declined at the lower recirculation rates than the threshold.

• 대한생식의학회:학술대회논문집
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• 2000.06a
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• pp.37-42
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• 2000

Objective: To determine whether particular semen characteristics in various clinical diagnoses of infertility are associated with high oxidative stress and whether any group of infertile men is more likely to have high seminal oxidative stress. Reactive oxygen species (ROS) play an important role in sperm physiological functions, but elevated levels of ROS or oxidative stress are related to male infertility. Design: Measurement of sperm concentration, motility, morphology, seminal ROS, and total antioxidant capacity (TAC) in patients seeking infertility treatment and controls. Setting: Male infertility clinic of a tertiary care center. Patient(s): One hundred sixty-seven infertile patients and 19 controls. Intervention(s): None. Main Outcome Measure(s): Semen characteristics, seminal ROS, and TAC in samples from patients with various clinical diagnoses and controls. Result(s): Fifteen patients (9.0%) were Endtz positive and 152(91.0%) Endtz negative. Sperm concentration, motility, and morphology were significantly reduced in all groups compared with the controls (P = .02), except in varicocele associated With infection group. Mean (${\pm}$SD) ROS levels in patient groups ranged from 2.2 ${\pm}$ 0.13 to 3.2 ${\pm}$ 0.35, signilicantly higher than controls (1.3 ${\pm}$ 0.3; P<.005). Patient groups had a significantly lower mean (${\pm}$SD) TAC from 1014.75 ${\pm}$ 79.22 to 1173.05 ${\pm}$ 58.07 than controls (1653 ${\pm}$ 115.28, P<.001), except ill the vaseclony reversal group (1532.02 ${\pm}$ 74.24). Sperm concentration was negatively correlated with ROS both overall and within all groups (P${\leq}$.007), with the exception of idiopathic infertility. Conclusion(s): Irrespective of the clinical diagnosis and semen characteristics, the presence of seminal oxidative stress in infertile men suggests its role in the pathophysiology of infertility. Medical or surgical treatments for infertility in these men should include strategies to reduce oxidative stress.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.253-260
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• 2024

In this study, ITO thin films were fabricated on a glass substrate at different thicknesses without introducing oxygen using RF sputtering system. The structural, electrical, and optical properties were evaluated at various thicknesses ranging from 50 to 300 mm. As the thickness of deposited ITO thin film become thicker from 50 to 100 mm, carrier concentration, mobility, and band gap energy also increased while the resistivity and transmittance decreased in the visible light region. When the film thickness increased from 100 to 300 mm, the carrier concentration, mobility, and band gap energy decreased while the resistivity and transmittance increased. The optimum electrical properties were obtained for the ITO film 100 nm. After optimizing the thickness, the ITO thin films were post-annealed at different temperatures ranging from 100 to 300℃. As the annealing temperature increased, the ITO crystal phase became clearer and the grain size also increased. In particular, the ITO thin film annealed at 300℃ indicated high carrier concentration (4.32 × 10²¹ cm^-3), mobility (9.01 cm²/V·s) and low resistivity (6.22 × 10^-4 Ω·cm). This means that the optimal post-annealing temperature is 300℃ and this ITO thin film is suitable for use in solar cells and display application.

• 연구논문집
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• s.33
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• pp.99-109
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• 2003

Recently the utilization of the ozone dissolved de-ionized water(DIW-$O_3$) in semiconductor wet cleaning process and photoresist stripping process to replace the conventional sulfuric acid and hydro peroxide mixture(SPM) method has been studied. In this paper, we propose the water-electrode type ozone generator which has the characteristics of the high concentration and purity to produce the high concentration DIW-$O_3$ for the photoresist strip process in the semiconductor fabrication. The proposed ozone generator has the dual dielectric tube structure of silent discharge type and the water is both used to electrode and cooling water. Through this study, we obtained the results of the 10.3 wt% of ozone gas concentration at the oxygen gas of 0.5 [liter/min.] and the DIW-$O_3$ concentration of 79.5 ppm.. Through the photoresist stripping test using the produced DIW-$O_3$, we confirmed that the photoresist coated on the silicon wafer was removed effectively in the 12 minutes.