• 한국환경과학회지
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• 제26권6호
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• pp.751-765
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• 2017

This research investigates the characteristics of meteorological variation and fine particles ($PM_{10}$ and $PM_{2.5}$) for case related to the haze occurrence (Asian dust, long range transport, stationary) in Busan. Haze occurrence day was 559 days for 20 years (from 1996 to 2015), haze occurrence frequency was 82 days (14.7%) in March, followed by 67 days (12.0%) in February and 56 days (10.0%) in May. Asian dust occurred most frequently in spring and least in winter, whereas haze occurrence frequency was 31.5% in spring, 29.7% in winter, 21.1% in fall, and 17.7% in summer. $PM_{10}$ concentration was highest in the occurrence of Asian dust, followed by haze and haze + mist, whereas $PM_{2.5}$ concentration was highest in the occurrence of haze. These results indicate that understanding the relation between meteorological phenomena and fine particle concentration can provide insight into establishing a strategy to control urban air quality.

• 한국멀티미디어학회논문지
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• 제25권9호
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• pp.1266-1272
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• 2022

With the recent development of computer vision technology, image processing-based mechanical devices are being developed to realize autonomous driving. The camera-taken images of image processing-based machines are invisible due to scattering and absorption of light in foggy conditions. This lowers the object recognition rate and causes malfunction. The safety of the technology is very important because the malfunction of autonomous driving leads to human casualties. In order to increase the stability of the technology, it is necessary to apply an efficient haze removal algorithm to the camera. In the conventional haze removal method, since the haze removal operation is performed regardless of the haze concentration of the input image, excessive haze is removed and the quality of the resulting image is deteriorated. In this paper, we propose an automatic haze removal method that removes haze according to the haze density of the input image by applying Ngo's Haziness Degree Evaluator (HDE) to Kim's haze removal algorithm using Hazy Particle Map. The proposed haze removal method removes the haze according to the haze concentration of the input image, thereby preventing the quality degradation of the input image that does not require haze removal and solving the problem of excessive haze removal. The superiority of the proposed haze removal method is verified through qualitative and quantitative evaluation.

• 한국환경과학회지
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• 제22권6호
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• pp.651-666
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• 2013

This study introduces a novel approach to the differentiation of two phenomena, Asian Dust and haze, which are extremely difficult to distinguish based solely on comparisons of PM10 concentration, through use of the Optical Particle Counter (OPC), which simultaneously generates PM10, PM2.5 and PM1.0 concentration. In the case of Asian Dust, PM10 concentration rose to the exclusion of PM2.5 and PM1.0 concentration. The relative ratios of PM2.5 and PM1.0 concentration versus PM10 concentration were below 40%, which is consistent with the conclusion that Asian Dust, as a prime example of the coarse-particle phenomenon, only impacts PM10 concentration, not PM2.5 and PM1.0 concentration. In contrast, PM10, PM2.5 and PM1.0 concentration simultaneously increased with haze. The relative ratios of PM2.5 and PM1.0 concentration versus PM10 concentration were generally above 70%. In this case, PM1.0 concentration varies because a haze event consists of secondary aerosol in the fine-mode, and the relative ratios of PM10 and PM2.5 concentration remain intact as these values already subsume PM1.0 concentration. The sequential shift of the peaks in PM10, PM2.5 and PM1.0 concentrations also serve to individually track the transport of coarse-mode versus fine-mode aerosols. The distinction in the relative ratios of PM2.5 and PM1.0 concentration versus PM10 concentration in an Asian Dust versus a haze event, when collected on a national or global scale using OPC monitoring networks, provides realistic information on outbreaks and transport of Asian Dust and haze.

• 한국환경과학회지
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• 제26권6호
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• pp.767-778
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• 2017

This research investigates the characteristics of metallic and ionic elements in $PM_{10}$ and $PM_{2.5}$ on haze day and non-haze day in Busan. $PM_{10}$ concentration on haze day and non-haze day were 85.75 and $33.52{\mu}g/m^3$, respectively, and $PM_{2.5}$ on haze day and non-haze day were 68.24 and $23.86{\mu}g/m^3$, respectively. Contribution rate of total inorganic water-soluble ion to $PM_{10}$ mass on haze day and non haze day were 58.2% and 61.5%, respectively, and contribution rate of total water-soluble ion to $PM_{2.5}$ mass on haze day and non haze day were 58.7% and 64.7%, respectively. Also, contribution rate of secondary ion to $PM_{10}$ mass on haze day and non haze day were 52.1% and 47.5%, respectively, and contribution rate of secondary ion to $PM_{2.5}$ mass on haze day and non haze day were 54.4% and 53.6%, respectively. AC (anion equivalents)/CE (cation equivalents) ratio of $PM_{10}$ mass on haze day and non haze day were 1.09 and 1.0, respectively, and AC/CE ratios of $PM_{2.5}$ mass on haze day and non haze day were 1.12 and 1.04, respectively. Also, SOR (Sulfur Oxidation Ratio) of $PM_{10}$ mass on haze day and non haze day were 0.32 and 0.17, respectively, and SOR of $PM_{2.5}$ on haze day and non haze day were 0.30 and 0.15, respectively. Lastly, NOR (Nitrogen Oxidation Ratio) of $PM_{10}$ on haze day and non haze day were 0.17 and 0.08, respectively, and NOR of $PM_{2.5}$ on haze day and non haze day were 0.13 and 0.06, respectively.

• 한국대기환경학회지
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• 제31권2호
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• pp.131-142
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• 2015

This study investigated physicochemical and optical characteristics for three episodes of Asian dust, stagnant haze and long-range transport haze and for one clean day. $PM_{10}$ mass concentration during Asian dust and two haze days was increased by 2~9 times compared to that of clean episode. During Asian dust episode, coarse particle concentration was increased and the mass concentration of calcium in a coarse mode ($1.8{\sim}10{\mu}m$) was $5.4{\mu}g/m^3$ which was 7 times higher than that of clean episode. The calcium was presented as a form of $CaCO_3$ in a coarse mode. During the two haze episodes, fine particle (< $1.8{\mu}m$) concentration was increased and secondary inorganic pollutants such as sulfate, ammonium and nitrate composed of 90% of the total ions. $(NH_4)_2SO_4$ and $NH_4NO_3$ were dominant in a fine mode for stagnant haze episode. But they were the most dominant form in both fine mode and coarse mode for long-range transport haze episode. According to the optical properties for each episode (Asian dust, stagnant haze and long-range transport haze) were classified as dust, black carbon and mixture, respectively.

• 공업화학
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• 제19권6호
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• pp.685-689
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• 2008

충전제의 종류 및 분산 시간에 따른 박막의 특성 평가를 실시하였으며, 그 결과 투과도 측면에서 유리한 중공 실리카를 선택하여 충전제의 함량별 그리고 코팅 두께별 haze, 투과도, 그리고 광택도에 대한 실험을 각각 실시하였다 그 결과, 충전제의 함량이 증가할수록 haze값은 증가하고 광택도 값은 이와는 반대로 감소하였다. 또한, 필름 표면에의 코팅 두께가 증가할수록 충전제의 함량변화 때와는 정 반대로 haze값은 감소하고 광택도는 증가하였다. 그리고 투과도의 경우에는 두 가지 경우 모두 거의 일정한 수준으로 변화를 보이지 않았다. 결론적으로 충전제로서 중공 실리카를 사용할 경우 함량 증가와 투과도면에서 매우 유리함을 알 수 있었다.

• 한국대기환경학회지
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• 제27권1호
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• pp.73-86
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• 2011

Haze phenomena were analyzed to assess the impact of long range transport process on the air quality of Seoul and Busan. We statistically classified haze days observed in both Seoul and Busan into two types of haze cases: stagnant case and long-range transport case, and analyzed the air pollutant levels comparatively for each of the two cases for the period of 2000~2007. The results showed that the long-range transport haze case occurs less frequently with the occurrence frequency of 35.5% than stagnant case with the occurrence frequency of 64.5%. During the observed all haze days, all pollutants have high concentration in comparison with those under other meteorological conditions (Rain, Mist, Dust, Clear, Rain+Mist) except for only $PM_{10}$ of Dust case where its level shows highest among total 6 categorized conditions. The long range transport haze case shows similar levels of $PM_{10}$ and $NO_2$, but higher $SO_2$ and lower $O_3$ compared with stagnant haze cases, suggesting the importance of sulfur chemistry for long range transport haze case and local photochemistry for stagnant haze case. In addition, by employing the NOAA/HYSPLIT-4 backward trajectory model, we subdivided the long range transport haze cases into two different sources: urban anthropogenic high emission areas of central China, and natural emission sources over north China and/or Mongolia. The former long range transport haze case shows higher occurrence (with Seoul 70% and Busan 85%) than the latter haze case (with Seoul 30% and Busan <10%). This is also implying that the long haze phenomena occurred over Korea have been influenced by not only the anthropogenic emissions but also the natural dust emissions. These both emission sources can be good contributors in calculating the source-receptor relationship over Korean atmospheric environment.

• Journal of information and communication convergence engineering
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• 제22권1호
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• pp.70-79
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• 2024

Bad weather conditions such as haze lead to a significant lack of visibility in images, which can affect the functioning and reliability of image processing systems. Accordingly, various single-image dehazing (SID) methods have recently been proposed. Existing SID methods have introduced effective visibility improvement algorithms, but they do not reflect the image's perspective, and thus have limitations that distort the sky area and nearby objects. This study proposes a new SID method that reflects the sense of space by defining the correlation between image brightness and haze. The proposed method defines the haze intensity by calculating the airlight brightness deviation and sets the weight factor of the depth map by classifying images based on the defined haze intensity into images with a large sense of space, images with high intensity, and general images. Consequently, it emphasizes the contrast of nearby images where haze is present and naturally smooths the sky region to preserve the image's perspective.

• Journal of Platform Technology
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• 제11권6호
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• pp.68-78
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• 2023

본 연구에서는 안개(haze)가 존재하는 영상에서의 색상 왜곡에 대하여 분석하고자 한다. 장면에 안개가 포함되는 경우, 장면에서 반사되는 칼라 신호는 안개 성분에 따른 투과율의 영향으로 색상의 왜곡이 수반된다. 통상적인 안개 제거(de-hazing) 방법으로 안개의 영향을 배제하는 경우 색상의 왜곡이 충분히 해소되지 않는 경향이 있다. Khoury 등은 많은 연구에서 언급되는 안개 모델인 다크-채널-프라이어(dark channel prior) 기법을 이용하여 색상의 왜곡 정도를 파악하였다. 그러나 색 오차 값 등 왜곡의 경향성 만을 확인하였고, 구체적인 색 왜곡에 대한 분석을 하지 않았다. 본 논문에서는 색 왜곡의 형태를 분석하고, 색상의 왜곡을 줄일 수 있는 복원 방법을 제안하였다. Khoury 등이 사용한 데이터베이스의 입력 영상에는 표준 칼라 도구인 맥베스 칼라체커(Macbeth color checker)가 포함되어 있다. 맥베스 칼라체커(Macbeth color checker)의 칼라 값들을 이용하여 안개 농도의 변화에 따른 색상 왜곡을 분석하고, 모델링을 통하여 새로운 색상 왜곡 모델을 제시하였다. 제안한 방법은 안개 농도 변화에 따른 단계별 색도(chromaticity)의 변화와 기준 정보(ground truth)의 색도를 이용하여 사상(mapping) 함수를 구하는 것이다. 색 왜곡의 형태가 안개 농도에 비례하여 단계별로 차이가 있으므로 모든 단계에서 안정적으로 작동하는 통합적인 사상 함수를 구하는 것이 필요하다. 본 논문에서는 제안한 방법을 통한 색상 왜곡의 개선을 각도 오차(angular error)의 값을 기준으로 추정하였으며, 기존 방법에 비하여 15% 정도의 개선효과가 있음을 검증하였다.

• 한국대기환경학회지
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• 제30권5호
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• pp.434-448
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• 2014

The aerosol characteristics between haze episode and Asian dust event were identified in January and March, 2013 in Gwang-ju of Korea to investigate the metal elements, ionic concentrations and carbonaceous particles of $PM_{2.5}$ and $PM_{10}$. In the haze episode, the concentrations were increased 1~3.2 times of ionic species and 1.6~2.7 of metal elements. Especially, the concentration of $NO{_3}{^-}$, $SO{_4}{^2-}$ and $NH{_4}{^+}$ consists of 50 percent in ionic species during haze episode that was higher than Asian dust event. This suggests that secondary aerosols from anthropogenic air pollution were mainly contributed by haze episode. During the Asian dust event, increase of metal concentrations was higher than haze episode because of remarkable increase of Ti, K and Fe originated from soil. The concentrations of carbonaceous particles were increased 2.5 times during haze episode, and 2.4 times of OC and 2.1 times of EC during Asian dust event in $PM_{2.5}$. However, these aerosol mass concentration does not affect the OC/EC ratio. The average equivalence ratios of cations/anions in $PM_{2.5}$ were 0.99 in haze episodes and 0.94 during non-event day. The neutralization factor of $NH_3$ was higher than that of $CaCO_3$. Futhermore, $NH{_4}{^+}$ aerosol was aged due to atmospheric stagnation that might be affected by the haze episode.