• 한국가스학회지
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• 제4권2호
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• pp.1-6
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• 2000

가스중에 포함되어 있는 NOx를 안전하게 처리하기 위하여 침상전극을 취부한 플라즈마 반응기를 제작하여 장치의 특성을 실험적으로 조사하여 유효성을 검정하였다. 반응가스는 $NO/N_2$ 혼합가스와 $N_2/O_2$ 혼합가스를 이용하여 초기 NO농도를 설정하고, 유속을 2${\iota}$/min으로 공급하였다. NOx의 반응특성은 방전주입전력이 높을때는 NO의 농도가 감소하였으며, 산소의 농도 증가시에 NO의 분해가 용이하고 NO의 분해에너지 효율이 높았다. 또한 NO의 농도가 증가할 수록 NO의 분해에너지 효율은 높으나 분해율은 낮았다. 오존의 특성은 방전주입전력이 높을수록 오존의 생성이 증가하고, $NO/N_2$의 농도가 증가할 수록 오존의 생성량이 감소하였다.

• 한국지능시스템학회논문지
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• 제17권4호
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• pp.435-442
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• 2007

대기중의 고농도 오존의 피해를 줄이기 위해서, 고농도 오존 발생 전에 미리 오존 농도를 예측하기 위한 연구가 진행되었다. 하지만, 고농도 오존은 그 발생 빈도가 매우 희소하고, 대기 오존 생성 과정이 매우 비선형적이며 복잡한 특징이 있다. 이러한 특징을 극복하고 보다 정확한 예측 모델을 개발하기 위하여, 본 논문에서는 다양한 데이터 처리 기법을 도입하였다. 데이터 전처리과정에서 FCM(Fuzzy C-mean) 방법을 이용하여 오존 농도별 데이터 클러스터링을 시도하였으며, 결측 또는 비정상 데이터를 처리할 목적으로 Rejection 표본 추출법을 이용하였고, 모델의 입력과 출력의 상관관계를 향상시키기 위해서 로그 변환기법을 응용하였다. 오존 예측을 위한 모델링 기법은 DPNN(Dynamical Polynomial Neural Networks)을 이용하였으며, 최소 바이어스 판별법(Minimum Bias Criterion)으로 최적화된 모델을 선택하였다. 끝으로, 본 논문에서는 로그 변환기법이 예측 모델에 미치는 영향을 보이기 위해서 입력 데이터를 두 개의 집합으로 나누어 다양한 방법으로 예측 결과를 평가했다. 결과적으로 계절적 영향에 의해 특정 분포를 가지는 오존 관련 데이터에 있어서 로그 변환 방법이 모델의 성능을 향상시킬 수 있다는 것을 보였다.

• 한국식품위생안전성학회지
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• 제10권1호
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• pp.45-51
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• 1995

Ozone treatment was applied to ginseng powder for the improving hygienic quality of ginseng powder. A bacterial strain was isolated form ginseng powder contaminated. The strain designated as GT4, was identified as Escherichia coli species by IMVIC test method. Ozone inhibited strongly total bacteria and coliforms in ginseng powder(initial concentration 103/g) at 0.35 ppm. High ozone concentration reduced death time of the total bacteria in ginseng powder. However, ozone treatment caused significant degradation in saponins of ginseng powder. Ozone treatment also caused a increase in Hunter's color L value and decrease in a and b values of ginseng powder.

• 한국대기환경학회지
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• 제20권2호
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• pp.215-224
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• 2004

We report the high concentration episodes for PM$_{10}$, SO$_2$, NO$_2$, and $O_3$ in many urban areas Korea during 2002. The high concentration episodes are identified based on the National Ambient Air Quality Standards and the observations obtained from the Regional Air Monitoring Network composed of approximately 160 air pollution monitoring stations located in a number of major or big cities in South Korea including Seoul, Pusan, Daegu, and Incheon cities. The results show that the twenty cases of high concentration episodes in 2002 consists of both ozone warning episodes (6 cases) and high PM$_{10}$ concentration cases (14 cases), and one half of the latter are found to occur in association with the Yellow Sand (Asian Dust) phenomena. The most outstanding characteristics of the reported episodes are the excessively high levels of maximum PM$_{10}$ concentrations during the Yellow Sand period (i.e., exceeding 3,000$\mu\textrm{g}$/㎥ in April, 2002) and their variable occurrence frequencies across seasons. The high ozone concentration episode days are mainly resulting from both the high photochemical reactions and poor ventilations. The high PM$_{10}$ concentration days during non Yellow Sand periods, however, mostly occurred under the influence of synoptic meteorological conditions such as stagnant or slowly passing high pressure centers, and consequently prevailing weak wind speeds over the Korean peninsula. The overall results of our study thus suggest the importance of both synoptic and local meteorological factors for high concentration levels in the major and/or big cities in Korea.n Korea.

• 한국대기환경학회지
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• 제14권6호
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• pp.545-554
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• 1998

The diurnal variation of O3 concentration shows two peaks, the first peak at noontime and the secondary peak at night. In order to show why the secondary peak, high nocturnal O3 concentration, occurs without sunlight which is a essential factor of a photochemical response, the O3 concentration, several weather elements and synoptic weather map were used for June∼September at 1995, 1996. The mean concentration of high nocturnal O3 concentration days is higher by 5.4 ppb than that of low nocturnal O3 concentration days. The nocturnal O3 concentration is higher than that of diurnal O3 concentration during high nocturnal O3 concentration days, at July, 1995 and June, 1996. The high nocturnal O3 concentration is related to low air pressure, high cloud cover and high wind speed. The correlation coefficient, r. between nocturnal O3 concentration and wind speed, pressure and cloud cover is 0.387, -0.218, and 0.194, respeftiviely. It is interesting that the O3 concentration increases at Pusan when the typhoon passes by. The same result showed at Taegu when the typhoon FAYE passed by. According to the analysis of nocturnal O3 concentration for June∼September at 1995 and 1996, it seems that the high nocturnal O3 concentration relates to the trough and cyclones passing by Pusan.

• 한국전기전자재료학회논문지
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• 제17권11호
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• pp.1143-1148
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• 2004

In this study, photoresist stripping in semiconductor or LCD (liquid crystal display) fabrication processes using DIO, was investigated. In order to obtain the high PR stripping efficiency of DIO. we have developed new ozone-generating system with high ozone concentration and ozone-resolving system with high contact ratio. In this study, we obtained ozone gas concentrations of 11 % by new ozone-generating system, ozone-resolving efficiency of 99.5 % and maximum solubility of 130 ppm in deionized water. We applied the newly designed equipments to photoresist stripping processes and obtained similar results to SPM(sulfuric-peroxide mixture) process characteristics.

• 한국대기환경학회지
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• 제12권1호
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• pp.55-66
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• 1996

One-hour average concentrations of ground-level ozone from around 80 monitoring stations in Korea during 1991 to 1993 were analyzed to examine characteristics of the ozone concentration variations. Two types of variations were observed: one was for the Capital area typified by Kwanghwmun, and the other was for the south and east seashore region typified by Tongkwangyang. In the Capital area including Seoul, Inchon, Kyonggi-do and Chunchon, mean daily 1-hout maximum was the highest in June following high monthly averages in spring. But frequent precipitation prevented further rise of daily maximum in July and August even though there were frequent episodes of high concentration exceeding 100ppb. In the south and east seashore region, average concentration was the highest throughout the year, and daily maximum and minimum simultaneously changed owing to small contributions from photochemical reactions. The typical annual variation was spring peak, summer down, and fall rise. Spring peak accompanied an usual observations of background variations at remote sites in the Northern Hemisphere. Riess of average and daily maximum with lower daily minimum in fall were attributable to photochemical reactions.

• 한국환경과학회지
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• 제6권4호
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• pp.335-350
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• 1997

Numerical simulations of photochemical air pollution (CBM: Carbon-Bond Mechanisms under a theoretical three-dimensional local wind system are carried to clarify the fundamental characteristics of the effects of local wind on photochemical air pollution. According to the AWS data of Pusan coastal area and KMA, the surface wind of Pusan during summertime showed a very remarkable land and sea breeze circulation. The ozone concentration distribution using local wind model showed that high ozone concentration zone near coastal area moved toward inland In the afternoon. This change implies a sea breeze Increases the ozone concentration, but a land breeze decreases it in Pusan coastal area.

• Asian Journal of Atmospheric Environment
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• 제9권2호
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• pp.114-127
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• 2015

In the Mexico City Metropolitan Area (MCMA), ozone ($O_3$) concentration is still higher than in other urban areas in developed countries. In order to reveal the current state of photochemical air pollution and to provide data for validation of chemical transport models, vertical profiles of meteorological parameters and ozone concentrations were measured by ozonesonde in two field campaigns: the first one, during the change of season from wet to dry-cold (November 2011) and the second during the dry-warm season (March 2012). Unlike previous similar field campaigns, ozonesonde was launched twice daily. The observation data were used to analyze the production and distribution of ozone in the convective boundary layer. The observation days covered a wide range of meteorological conditions, and various profiles were obtained. The evolution of the mixing layer (ML) height was analyzed, revealing that ML evolution was faster during daytime in March 2012 than in November 2011. On a day in November 2011, the early-morning strong wind and the resulting vertical mixing was observed to have brought the high-ozone-concentration air-mass to the ground and caused relatively high surface ozone concentration in the morning. The amount of produced ozone in the MCMA was estimated by taking the difference between the two profiles on each day. In addition to the well-known positive correlation between daily maximum temperature and ozone production, effect of the ML height and wind stagnation was identified for a day in March 2012 when the maximum ground-level ozone concentration was observed during the two field campaigns. The relatively low ventilation coefficient in the morning and the relatively high value in the afternoon on this day implied efficient accumulation of the $O_3$ precursors and rapid production of $O_3$ in the ML.

• 한국대기환경학회지
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• 제16권6호
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• pp.607-623
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• 2000

Major trends of ozone concentration variations in Korea were investigated by using observation data from around 100 stations for the period of 1991∼1997. In addition, important regulating those variations were inferred. Three measures such as the number of days exceeding 80ppb, the 95th percentile of daily maxima, and the annual average concentration were used for the analysis of multi-scale ozone concentration variations. Three areas in the southwest (Sosan, Mokpo, and Cheju) of which monitoring has been operated since 1995 showed the highest annual average concentrations over; this was noted because of the high annual average in the Yosu area in the early 1990s. Large increases in annual average concentrations were observed along the relatively cleaner areas connecting Kangnung and Kwangju(northeast to southwest), in contrast to polluted areas connecting Seoul and Pusan(northeast to southeast). Both the number of exceedance days and the daily maximum concentration were nearly constant in the Greater Seoul Area in spite of interannual flucturations associated with year-to-year changes in air temperature. Within the Greater Seoul Area, all three measures usually showed the same trend; they decreased in the middle and west and increased in the east and northeast. All three measures including the number of exceedance days increased largely at Sillim where the average concentration was high but no exceedance days were recorded in the early 1999s, Nationwide ozone concentration variations appear to be determined by the competitive influence of long-range transport and local urban emissions, Within the city including the Greater Seoul Area, changes in emission which accompany changes in population and in the number if vehicles ( in the process of urban development) were found to be important components of ozone concentration variations.