• The Plant Pathology Journal
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• 제16권1호
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• pp.19-24
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• 2000

The direct effects of acute $\textrm{O}_3$ on the growth, sporulation and infection of Pyricularia grisea, rece blast pathogen, were investigated to understand the interactions between ozone and the pathogen. Acute exposure of 200 nl $\textrm{l}^{-1}$ ozone for 8 h significantly reduced conidia germination on water atar. Ozone exposure of 200 nl $\textrm{l}^{-1}$ for 8h per day for 5 days had no effect on increase in colony diameter, but severely damaged actively growing aerial mycelia. However, the damage to mycalia was recovered during the following 16 h exposure of unpolluted air. Conidial production was also stimulated by the acute ozone exposure for 5 days. The conidia exposed to the acute ozone for 5 days normally germinates but slightly reduce appressoria formation on rice leaf. However, the conidia produced by artificial stimulation under the same ozone concentration for 10 days showed significant reduction in appressorea for mation on a hydrophobic film. This study suggests that the acute ozone could ingibit appressoria formation as well as vegetative growth of the pathogen, resulting in decrease in rece blast development in the field during summer when high ozone episodes could occur occasionally.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권7호
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• pp.335-342
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• 2003

This paper presents a forward type high voltage pulse power supply for high voltage small current, which can be designed as a simple circuit configuration and managed easily using Power-MOSFET in the view of commercialization. According to the switching frequency, coupling factor(k) and duty ratio(D), the Principle of basic operation and the characteristics of the proposed pulse power supply are estimated. Simulation results have demonstrated the feasibility of the proposed pulse power supply. Also experimental results are presented to verify theoretical discussion with a lamp type ozonizer as a load. For studying the application at the part of environment of water, When ozonizer gas reacts with a colon bacillus, the sterilization characteristics of a colon bacillus according to the ozone concentration and response time have been investigated. This proposed pulse power supply will be able to be practically used as a pulse power supply in various environment improvement facilities like sterilization of colon bacillus, deodorization, and Nox gas elimination.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.562-564
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• 2000

The optimization of electrode geometry is the most important technology for producing the ozone with high concentration and efficiency. An optimization method for a discharge gap, an air cleaner equipment, voltage apply device, pressure and air flow quantity. In our experiments, the high frequency power were applied to the discharge gap with 23-1G(Silent Discharge). The ozone characteristics was measured with air as a supplied gas, which can be used as basic data for the development of small size ozone generator.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권12호
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• pp.673-678
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• 2000

The dielectric barrier discharge(DBD) is a common method to create a nonthermal plasma in which electrical energy is used to create electrons with a high average kinetic energy. The unique aspect of dielectric barrier discharges is the large array of short lifetime(10ns) silent discharges created over the surface of the dielectric. A silent discharge is generated when the applied voltage exceeds the breakdown voltage of the carrier gas creating a conduction path between the applied electrode and grounded electrode. As charge accumulates on the dielectric, the electric field is reduced below the breakdown field of the carrier gas and the silent discharge self terminates preventing the DBD cell from producing a thermal arc. In fact, the most significant application of dielectric barrier discharges is to generate ozone for contaminated water treatment. Therefore, experiments were perfomed at 1∼2[bar] pressure using a coaxial geometry single dielectric barrier discharge for ozone concentrations and energy densities. The main result show that the concentration and efficiency of ozone are influenced by gas nature, gas quantity, gas pressure, supplied voltage and frequency.

• 한국환경과학회지
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• 제11권6호
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• pp.497-506
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• 2002

A Photochemical-Trajectory model was used to understand the production of ozone in the atmospheric boundary layer. This model was composed of the trajectory and the photochemical models. To calculate trajectories of air parcels, winds were obtained from the three-dimensional nonhydrostatic mesoscale model (PSU/NCAR MM5V2), and the results were interpolated into constant height surfaces. Numerical integration in the trajectory model was performed by the Runge-Kutta method. The photochemical model consisted of chemical reactions and photodissociation processes. Chemical equations were integrated by the semi-implicit Bulirsch-Stoer method. We performed our experiments from 21 July to 23 July 1994 during the summer time for Seoul area. During the time of maximum ozone concentration in Seoul, four trajectories of air parcels which traveled from Inchon to Seoul were selected. Ozone concentrations estimated by two models are compared with observed one in Seoul area and the photochemical-trajectory model is better fitted than pure photochemical model. During the selected period, high ozone concentrations in Seoul area were more influenced by transferred pollutants from Inchon than emitted pollutants in Seoul.

• 한국대기환경학회지
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• 제34권5호
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• pp.708-726
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• 2018

In this study, we examined the contribution of nitrogen oxides and volatile organic compounds emitted from China and Japan to ozone concentrations over Gwangyang-bay, South Korea. We used a chemical transport model, Community Multi-scale Air Quality model, and its instrumented sensitivity tool, High-order Decoupled Direct Method. Intercontinental Chemical Transport Experiment-Phase B 2006 for East Asia and Clean Air Policy Support System 2007 emissions inventories for South Korea were used for the ozone simulation. During the study period, May 2007, the modeled maximum daily 8-hr average ozone concentration among seven air quality monitors in Gwangyang-bay was 68.8 ppb. The contribution of $NO_x$ emissions from China was 19.5 ppb (28%). The highest modeled ozone concentrations and Chinese contributions appeared when air parcels were originated from Shanghai area. The observed 8-hr average ozone concentrations in Gwangyang Bay exceeded the national ambient air quality standard (60 ppb) 203 times by daytime and 56 times by nighttime during the period. It was noticed that many exeedances happened when contribution of Chinese emissions to ozone concentrations over the area increased. Sensitivity analysis shows that a reduction in Chinese $NO_x$ and VOC emissions by 15% could lessen the total exceedance hours by 24%. This result indicates that high ozone concentrations over Gwangyang-bay are strongly enhanced by Chinese emissions.

• 한국환경과학회지
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• 제8권1호
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• pp.33-43
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• 1999

This paper aims to describe the characteristics of air pollution using air pollutants concentration and meteorological data observed at Kimhae from December 1996 to November, 1997. The results are as follows : The concentration distribution of sulfur dioxide($SO_2$), carbon monoxide(CO), particulate matter(PM-10), and nitrogen dioxide($NO_2$) is high during the late fall and winter and low during the summer, but ozone concentration is low during the winter season and high during summer season except Jangma period and these distributions appear to be closely connected with insolation and the number of clear day. Diurnal variation of concentrations for sulfur dioxide, particulate matter, and carbon monoxide are high during the rush hours and nighttime and low during the daytime and these variations are distinct toward the winter season. And diurnal variation of nitrogen dioxide concentration has also same pattern and these patterns are closely related to the increasing traffic volume at rush hours. Diurnal variation of ozone concentration is generally increase for daytime and decrease for the late afternoon and are closely related to the insolation and photochemical reaction. The 24 hour average concentrations of air pollutant observed at Kimhae represented a positive correlation and a negative correlation for $O_3$ and also a negative correlation for the meteorological elements such as wind speed and cloud cover.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권3호
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• pp.77-80
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• 2003

An innovative ozonizer has been developed using a high frequency, surface discharge and a high purity Ti-Si-AI ceramic catalyst as a dielectric component. Using a type of thin film, a thin cylindrical compound ceramic catalyst layer was adhered to the outside surface of its inner electrode. An alternating current (AC) exciting voltage with frequencies from 0.6 KHz to 1.0 KHz and peak-to-peak voltages of 4-6 ㎸ was applied between the electrodes to produce a stable high-frequency silent discharge. A substantial reduction of the exciting voltage was also enabled by means of a thin Ti-Si-Al ceramic catalyst tube. As a result, the ozonizer can effortlessly obtain the required ozone concentration (50-60 g/$m^2$ for oxygen) and high ozone efficiency consumption power (180 g/kWh for oxygen) with-out the assistance of any particular methods. For purposes of this experiment, oxygen gas temperature was set at 2$0^{\circ}C$, with an inner reactor pressure of 1.6 atm at 600 Hz and a flow rate of 2 l/min.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1230-1233
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• 2004

Ozone is useful oxidizing gas for the fabrication of oxide thin films. Accordingly researching on oxidizing gas is required. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper oxidation property was evaluated relation between oxide gas pressure and inverse temperature(CuO reaction). The obtained condition was formulated by the fabrication of Cu metal thin film by co-deposition using the ion Beam Sputtering method. Because the CuO phase peak appeared at the XRD evaluation of the CuO thin film using ozone gas, this study has succeeded in the fabrication of the CuO phase at $825^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 제6회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.35-38
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• 2004

Ozone is useful oxidizing gas for the fabrication of oxide thin films. Accordingly researching on oxidizing gas is required. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper oxidation property was evaluated relation between oxide gas pressure and inverse temperature(CuO reaction). The obtained condition was formulated by the fabrication of Cu metal thin film by co-deposition using the Ion Beam Sputtering method. Because the CuO phase peak appeared at the XRD evaluation of the CuO thin film using ozone gas, this study has succeeded in the fabrication of the CuO phase at $825^{\circ}C$.