• Journal of the Korean earth science society
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• v.43 no.1
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• pp.77-90
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• 2022

Despite the decreasing trend of anthropogenic emissions in East Asia in recent years, haze days still frequently occur in spring. Atmospheric blocking, which occurs frequently in the northeastern Pacific, leads to persistent changes in large-scale circulation and blocks westerly flow in the East Asian region. During March 2019, frequent warm and stagnant synoptic meteorological conditions over East Asia were accompanied 6-7 days later by the Alaskan atmospheric blocking. The Alaskan atmospheric blocking over the period of March 18-24, 2019 led to high particulate matter (PM₁₀) severe haze days exceeding a daily average of 50 ㎍ m^-3 over the period of March 25-28, 2019 in South Korea. Although the high-PM₁₀ severe haze days were caused by warm and stagnant meteorological conditions, the regional contribution of anthropogenic emissions in eastern China was calculated to be 30-40% using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). The major regional contributions of PM₁₀ aerosols in the period of high-PM₁₀ severe haze days were as follows: nitrates, 20-25%; sulphates, 10-15%; ammonium, 5-10%; and other inorganics, 15-20%. Ammonium nitrate generated via gas-to-aerosol conversion in a warm and stagnant atmosphere largely contributed to the regional transport of PM₁₀ aerosols in the high-PM₁₀ severe haze days in South Korea.

• Atmosphere
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• v.34 no.2
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• pp.139-151
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• 2024

The Yeongdong region has suffered from severe snowstorms and the relevant damage such as traffic accidents on slippery roads, and the collapse of greenhouses and temporary buildings. While a lot of research on snowfall has been conducted, the detailed study of snow crystals' phase and habit through intensive observations and the relevant microphysical analysis is still lacking. Therefore, a snowflake camera, PARSIVEL, and intensive radiosonde soundings were utilized to investigate phase and habit changes in solid precipitation. Two remarkable episodes of phase and habit changes were selected such as 19 March 2022 and 15 February 2023. Both events occurred in the synoptic condition of the High in the north and the Low passing by the south, which was accompanied by rapid temperature cooling below 2.5 km. During the events of a short period between 3 to 6 hours, the temperature at 850 hPa decreased by about 4 to 6℃. This cooling led to a change in the main habit of snow particles from riming to aggregate, identified with both MASC and PARSIVEL. Meanwhile, the LDAPS model analyses do not successively represent the rapid cooling and short-term variations of solid precipitation, probably by virtue of overestimating low-level equivalent potential temperature during these periods. The underlying causes of these the low-level temperature variations within 6 hours, still remain unclear. It might be associated with mesoscale orographic phenomenon due to the mountains and East Sea effects, which certainly needs an intensive and comprehensive observation campaign.

• Atmosphere
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• v.31 no.5
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• pp.625-635
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• 2021

South Korea established the 2050 Carbon Neutral Plan in response to the climate crisis, and to achieve this policy, it is very important to monitor domestic carbon emissions and atmospheric carbon concentration. Both CO₂ and CO are emitted from fossil fuel combustion processes, but the relative ratios depend on the combustion efficiency and the strength of local emission regulations. In this study, the relationship between CO₂ and CO was analyzed using ground observation data for the period of 2018~2020 at Anmyeon-do site and the CO/CO₂ ratio according to regional origin during high CO₂ cases was investigated based on the footprint simulated from Stochastic Time-Inverted Lagrangian Transport (STILT) model. CO₂ and CO showed a positive correlation with correlation coefficient of 0.66 (p < 0.01), and averaged footprints during high CO₂ cases confirmed that air particles mainly originated from eastern and north-eastern China, and inland of Korean Peninsula. In addition, it was revealed that among the cases of high CO₂ concentration, when the CO/CO₂ ratio is high, the industrial area of eastern China is greatly affected, and when the ratio is low, the contribution of the domestic region is relatively high. The ratio of CO₂ and CO in this study is significant in that it can be used as a useful factor in determining the possibility of domestic and foreign origins of climate pollutants.

• Korean Journal of Optics and Photonics
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• v.34 no.3
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• pp.99-105
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• 2023

The performance of astronomical telescopes can be negatively affected by atmospheric turbulence. To address this issue, techniques for atmospheric turbulence correction have been developed, requiring the simulation of atmospheric turbulence in the laboratory. The most practical way to simulate atmospheric turbulence is to use a phase plate. When measuring a phase plate that simulates strong turbulence, a Shack-Hartmann wave-front sensor is commonly used. However, the laser power decreases as it passes through the phase plate, potentially leading to a weak laser signal at the sensor. This paper investigates the need to control the laser power when measuring a phase plate that simulates strong atmospheric turbulence, and examines the effects of the laser power on the measured wavefront. For phase plates with relatively high Fried parameter r₀, the laser power causes a variation of over 10% in r₀. For phase plates with relatively low r₀, the laser power causes a variation of less than 5%, which means that the influence of the laser power is negligible for phase plates that simulate strong atmospheric turbulence. Based on the system described in this paper, a phase plate simulating strong atmospheric turbulence can be measured at a laser power of 5 mW or higher. Therefore, controlling the laser's output power is necessary when measuring a phase plate for simulating atmospheric turbulence, especially for phase plates with low r₀ values.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.529-539
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• 2016

Modeling can be used to understand the atmospheric dispersion of air pollutants scientifically. Recent development of model computation enabled to simulate more diverse area. As flowing out from the emission source, the concentration profiles of air pollutants could be estimated in three dimensional space. This study used CALPUFF diffusion model to predict the diffusion of discharged NO2 and TSP on the atmosphere near a combined heat power plant and incinerator. It was investigated contribution concentration of the surrounding area by sources by comparing the actual measurement results and the results of the modeling. Contribution of emission sources to the local level of NO2 was found quite high particularly at the site, A-3. The estimated results by modelling revealed more significant effect on TSP at A-5.

• Journal of the Korean earth science society
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• v.21 no.6
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• pp.647-654
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• 2000

The purpose of this study is to investigate the types of concepts about atmospheric pressure of middle school students and to design a new method to improve students' understandings on atmospheric pressure. The second grade students of the middle school has been selected and examined their pre-concepts on atmospheric pressure through questionnaires and interviews. Two groups of students have been taught using the second grade science textbooks and experimental methods designed from this study, respectively. The results suggest that we need to develope various teaching methods that can improve alternative concept as well as experimental tools that can help students understand difficult scientific concepts. The reason is that once alternative concept is occupied, it is extremely difficult to fix it. In addition, the proposed experimental methods are effective in establishing the concept and understanding on atmospheric pressure.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.449-450
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• 1999

VOCs(volatile organic compounds)는 대기중에서 질소산화물과 함께 광화학반응에 참여하여 인체 및 동식물에 유해한 오존 등 2차 오염물질인 광화학산화물을 형성하는 전구물질로 작용한다. 1998년 8월 미국 EPA에서는 휘발성유기화합물과 지표 부근의 오존 또는 스모그의 발생량을 감소시키기 위해 페인트, 세제 및 살충제의 제조공법에 관한 새로운 규칙을 발표하여 휘발성 용제 사용 규제를 강호하고 있다(과학기술부, 1998).(중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.283-284
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• 2002

투명하고, 과학적으로 소각장을 관리하기 위해서는 소각장에서 배출되는 오염물질이 주변에 미치는 기여 영향도를 정확히 계산할 필요가 있다. 이와 같은 목적으로 현재 국내에서 사용되고 있는 대기환경 영향평가용 software는 미국환경청에서 제작된 software로써 DOS상에서 구동되기 때문에 사용이 불편하고 국내 지형 및 기상조건에 부적합한 문제점을 갖고 있다. 따라서 국내 여건에 적합하고, 사용하기 용이한 Windows GUI(Graphic User Interface)에서 공동되는 평가용 software개발이 필요하다. (중략)

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.107-112
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• 1996

원전의 환경방사선 영향평가(정상시/사고시)의 정확도 및 신뢰도를 제고하기 위해서는 보다 체계적이고 과학적으로 방사성 물질의 대기중 이동을 모사·예측할 수 있는 체제가 정립되어야 한다. 해안 지역에서 빈번히 발생하는 해륙풍이 대기확산에 미치는 영향을 규명하고, 대기확산모델의 바람장 자료로 이용되는 월성원전 주변지역의 해륙풍 데이터베이스를 구축하기 위한 일환으로 삼차원 상세 해륙풍 모델을 개발하였다. 봄철 약한 북풍의 지균풍이 부는 맑은 날에 대하여 해륙풍 모델을 수행시켜 월성원전 지역의 해륙풍 특성을 분석하고 해륙풍 모델결과와 관측결과를 비교하였다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.101-102
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• 2002

과거 50여년간 전산기는 성능과 효율면에서 획기적인 발전을 거듭하여 왔다. 더욱이 최근 20여년간 microcomputer와 PC 분야의 발전으로 저렴한 가격으로 전산자원을 활용할 수 있게 되었다. 그러나, 1개의 CPU로 도달할 수 있는 속도의 한계에 근접함에 따라서, CPU 성능의 향상 속도가 느려지고 있다. 현재 초고성능 전산기로도 많은 시간과 비용이 소요되는 문제가 과학 및 공학 분야에 아직 많이 있는 상황에서 이러한 전산속도 발전의 둔화는 심각한 문제가 되고 있다. (중략)