• 천문학회보
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• 제37권1호
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• pp.88.2-88.2
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• 2012

We investigate solar flare occurrence rate and daily flare probability depending on McIntosh sunspot classification, its area, and its area change. For this we use the NOAA active region and GOES solar flare data for 15 years (from January 1996 to December 2010). We consider the most flare-productive 10 sunspot classification: 'Dko', 'Dai', 'Eai', 'Fai', 'Dki', 'Dkc', 'Eki', 'Ekc', 'Fki', and 'Fkc'. Sunspot area and its change can be a proxy of magnetic flux and its emergence/cancellation, respectively. we classify each sunspot group into two sub-groups: 'Large' and 'Small'. In addition, for each group, we classify it into three sub-groups according to sunspot group area change: 'Decrease', 'Steady', and 'Increase'. As a result, in the case of compact groups, their flare occurrence rates and daily flare probabilities noticeably increase with sunspot group area. We also find that the flare occurrence rates and daily flare probabilities for the 'Increase' sub-groups are noticeably higher than those for the other sub-groups. In case of the (M+X)-class flares of 'Dkc' group, the flare occurrence rate of the 'Increase' sub-group is three times higher than that of the 'Steady' sub-group. Mean flare occurrence rates and flare probabilities for all sunspot regions increase with the following order: 'Steady', 'Decrease', and 'Increase'. Our results statistically demonstrate that magnetic flux and its emergence enhance major solar flare occurrence. We are going to forecast solar flares based on these results and NOAA scale.

• 환경영향평가
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• 제28권6호
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• pp.568-579
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• 2019

연구는 서울시 도시대기 측정망의 월별 미세먼지 농도와 측정소 주변 버퍼별, 토지피복 유형별 비율의 관계를 분석하여 미세먼지 농도에 대한 토지피복의 영향을 규명하고자 하였다. 대분류 토지피복 유형과 미세먼지 농도의 월별 상관분석 결과 버퍼 3km에서, PM_2.5보다 PM₁₀에서 상관성이 잘 나타났고, 산림과 뚜렷한 음의 상관관계, 초지와 시가지는 PM₁₀과, 나지와 시가지는 PM_2.5와 일부 양의 상관관계를 나타냈다. 버퍼 3km 내 중분류 및 세분류 우세 피복유형의 월별 상관분석 결과 PM₁₀은 활엽수림과 뚜렷한 음의 상관관계를 나타냈고, 도로와 일부 양의 상관이 우세한 편이었다. PM_2.5는 활엽수림과 일부 음의 상관, 상업지역과 일부 양의 상관이 많은 편이었다. 그 밖에 초지 및 나지 세부 유형의 상관성은 매우 낮거나 없었다. 양의 상관 및 음의 상관관계의 각 대표 피복유형으로 단계선택법에 의한 월별 회귀분석을 실시한 결과 PM₁₀은 활엽수림 비율 증가에 의한 농도 감소 영향이 뚜렷하였고, 도로는 변수선택에서 제거되었다. PM_2.5는 일부 월별로 상업지역 비율 증가에 따른 농도 증가 영향 또는 활엽수림 비율 증가에 따른 농도 감소 영향을 받았지만, 그 영향력은 PM₁₀에 비해 낮았다. 연구결과 측정소 주변 토지피복은 미세먼지 농도 증감에 영향을 주었고, 그 영향은 PM₁₀에서 더 분명하였다. 산림 유형은 미세먼지 농도에 가장 크고, 분명한 영향을 주는 저감 요인이었다. 시가화지역 관련 유형들의 농도 증가 영향은 일부 확인되었다. 도심 산림의 미세먼지 저감 기능은 분명한 효과를 가진 것으로 보이며, 향후 녹지의 세부 특성과 복잡한 도시환경 요인의 작용을 규명하는 후속 연구가 필요하였다.

• Journal of the Korean Wood Science and Technology
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• 제52권3호
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• pp.289-299
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• 2024

The current study aimed to investigate the impact of CO₂ enrichment on the width of annual tree rings, earlywood and latewood, and the area of annual growth of Pinus densiflora Siebold & Zucc. grown in open-top chamber (OTC). To this end, two CO₂ enrichment cases were considered, namely 1.4 × increment (560 ppm in OTC-II) and 1.8 × (720 ppm in OTC-III) were compared with the current atmosphere (400 ppm in OTC-I). The CO₂ enrichment conditions for a period of 12 years (2010-2021) were considered, and all measurements were done through image analysis. The study showed that the increment in CO₂ concentrations positively affected the tree growth. The measurement data from the trees in OTC-III were considerably higher than those from OTC-I, whereas those from OTC-II were slightly higher than those from OTC-I. Decreasing patterns of the measured widths and area in 6-7 years after the beginning of CO₂ enrichment was found for all the OTCs. These patterns were possibly due to changes in the physiological features, such as aging. The findings of the present study can have potential uses as fundamental data for forest management considering CO₂ concentrations.

• 한국환경과학회지
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• 제29권2호
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• pp.177-189
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• 2020

We analyzed the recent characteristics of Particulate Matter (PM) including PM₁₀ (PM with diameter of less than 10 ㎛) and PM_2.5 (PM with diameter of less than 2.5 ㎛) observed in Busan metropolitan area, and compared them with those measured in Seoul metropolitan area. This analysis includes the monthly, seasonal, and annual variations and differences, in emissions and chemical compositions observed in both Busan and Seoul areas. Synoptic meteorological conditions were investigated at the time when high PM concentrations occurred in each of the two areas. The results showed clearly decreasing trends of annual mean concentrations with strong seasonal variations: lower in summer and higher in winter in both areas. In comparison with Seoul, the seasonal variation in Busan demonstrated relatively lower, but showed greater summer fluctuations than in Seoul metropolitan area. This is implying the importance of secondary generation of PM in summer via active photochemical reaction in Busan area. In high concentration days, Busan's chemical composition of sulfate was higher than that of nitrate in summer, whereas nitrate was higher than sulfate in Seoul. The ratios of NO₃^- to SO₄^2-(N/S ratio) showed lower in Busan approximately by a factor of 1/2(half of N/S ratio) in Busan compared with that in Seoul. Others such as synoptic characteristics and emission differences were also discussed in this study.

• 한국초전도ㆍ저온공학회논문지
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• 제23권4호
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• pp.14-18
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• 2021

The Mg-Powder-Compaction (MPC) process is proposed to fabricate the MgB₂ superconducting wires. Mg powder wall, similar to the Mg metal tube, inside the Nb outer sheath has been made and the stochiometric B powder was inserted into the wall. Even though the very high MgB₂ core density of 2.53 g/cm³ is obtained, the superconducting area fraction of MgB₂ is not high enough for the applications. In this work, an advanced MPC process was adopted by adding Mg powder into B powder. The Mg powder wall in the initial wire was fabricated by controlling the wall thickness while maintaining a constant density, and the mixture of B and Mg powder was filled into the Mg powder wall with the same filling density. It is found that the reduction in the area of the Mg powder wall proceeds similar to the wire, and the Mg powder wall is well maintained at the final wire diameter, which is advantage for the fabrication of long wires. With the advanced MPC process, as the added Mg is increased the densities of MgB₂ core is decreased and the porous structure is formed, it is found that the area fraction of superconducting MgB₂ increase up to the 37.7 % with the improved high critical current density (J_c) and the engineering critical current density (J_e).

• 대한교통학회지
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• 제22권2호
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• pp.109-119
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• 2004

COSMOS는 1990년부터 개발되어 현재까지 현장실험 및 시스템 검증과 여러 차례의 기능개선을 통하여 점차 안정화 되어가고 있으며, 그 효율성이 입증되어 서울시 전역으로 확산되고 있는 추세이다. 그러나 현재는 CI의 옵셋패턴이 한쪽 축 방향의 유입/유출 이동류에 의해서만 산출되고 있어, 다른 축방향에 속한 교차로는 자신과 무관한 옵셋패턴에 의해 운영되는 경우가 발생한다. 또한 Sub Area 결합/분리시 CI의 유입/유출 방향의 축에 속한 Sub Area와의 결합/분리만이 가능한 실정이다. 따라서 본 연구에서는 CI의 동서와 남북 축 각각의 유입/유출 방향을 설정하여, 두 축의 옵셋패턴과 현재 운영 주축을 계산하여 설정하도록 하였다. Sub Area 내의교차로들은 자신이 속한 축의 옵셋패턴에 의해 운영되며, 결합/분리시에는 주축방향간의 '결합'과 이외의 경우의 '연동'의 개념으로 운영되도록 하였다. 개선된 알고리즘은 COSMOS 운영 S/W에 탑재하여, 강남구 10여개 교차로를 대상으로 기능성 평가 및 효율성 평가를 실시하였다. 평가 결과 개선 알고리즘이 기존방식보다 통행시간을 감소시키는 것으로 나타났다.

• 대한가정학회지
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• 제37권1호
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• pp.29-44
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• 1999

The objectives of this study are (1) to identify sub-areas of the pro-environmental behavior, (2) to examine the level of the pro-environmental attitude and behavior, (3) to examine the degree of inconsistency between attitude and behavior, and (4) to investigate the reasons of the inconsistency. Data was collected from the questionnares with 299 married men and 378 married women and the deep interviews with 10 married women. The major findings are follows : (1) The pro-environmental behavior can be classified into 2 sub-areas : social-oriented area and individual-oriented area. (2) The level of pro-environmental attitude and behavior in the social-oriented area is lower than those in individual-oriented area. (3) The attitude-behavior inconsistency in the social-oriented sub-area is stronger than that in the individual-oriented sub-area. (4) The reasons of the pro-environmental attitude-behavior inconsistency are the lack of the sincere environmental consciousness and the existence of the pro-environmental behavior restriction factors.

• 한국환경과학회지
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• 제17권2호
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• pp.239-248
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• 2008

The purpose of this study is to examine appropriate sub-basin division numbers that best reflect the hydrological characteristics of the basin so as to propose the criterion for dividing the sub-basin in analyzing flood runoff in the future. The characteristics of flood runoff variations were based on the WMS HEC-1 model, and the area in the upstream of the Dongbyeon water level observatory and the Geum-ho water level observatory was chosen for analysis, and examined the characteristics of the changes in flood runoff. First of all, in the targeted basin, if the sub-basin division number was 4 (that is, the area of the divided sub-basin was about 25% of the total area). Next, as the sub-basin division number gradually increased, the peak rate of runoff increased as well, and in case the sub-basin was not divided, the peak rate of runoff occurred at the earliest time. Given these results, the spatial change characteristics will be best reflected when the sub-basin is divided for analysis of flood runoff in such a way that the area of the divided sub-basin is about 25% of the total area of the basin. However, as these results are based on a limited number (4) of storms, more storm events and other basins need to be included in the review of the sub-basin division methodology.

• 한국환경보건학회지
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• 제47권3호
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• pp.279-291
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• 2021

Objectives: This study investigated the association between air pollutant levels and medical usage rates for environmental disease in a general residential area during the period 2015-2017. Methods: Air pollutant (PM₁₀, PM_2.5, SO₂, NO₂, CO, O₃) data were collected from Air-Korea. Medical usage data on environmental disease (asthma, allergic rhinitis, atopic dermatitis) for the period 2015-2017 in a general residential area in Gyeongsangnam-do Province were provided by the National Health Insurance Corporation. Pearson correlation analysis and multiple regression analysis were conducted to investigate the association between air pollutant levels and medical usage rates (SAS 9.4). In the multiple regression analysis, environmental disease was set as the dependent variable and air pollutants were set as independent variables and analyzed using the General Linear Model. Results: Except for PM_2.5, the average concentration of air pollutants in the surveyed area was below than the air environment standards of Korea. NO₂ was higher than Korea's national average, but CO was similar. The others were lower than the Korea's national average. The daily medical usage rates for environmental disease were 1.38‰ for asthma, 9.90‰ for allergic rhinitis, and 0.32‰ for atopic dermatitis. As a result of correlation analysis, PM₁₀ and SO₂, NO₂ and CO were significantly correlated with asthma, PM₁₀ and NO₂ and CO were correlated with allergic rhinitis, and PM₁₀ and PM_2.5, SO₂, NO₂ and CO were correlated with atopic dermatitis. As a result of multiple regression analysis, PM₁₀ and SO₂ were found to have a higher effect on asthma, PM₁₀ and NO₂ on allergic rhinitis, and SO₂ and NO₂ on atopic dermatitis, compared to other air pollutants. Conclusion: According to these results, air pollutants such as PM₁₀ and SO₂ and NO₂ were associated with the medical usage rates of environmental disease even in relatively low concentrations. Therefore, continuous monitoring will be required for general residential areas.

• 한국결정성장학회지
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• 제31권5호
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• pp.218-227
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• 2021

저온 동시 소성용 후막 NTC 서미스터를 Mn_1.5Ni_0.4Co_0.9Cu_0.4O₄ 조성의 NTC 분말과 lead free frit 및 RuO₂를 이용하여 제조한 페이스트를 96 % 알루미나 기판 위에 인쇄와 소결을 통해 제조한 후, 이 후막 NTC의 전기적 특성에 미치는 프릿트 및 RuO₂의 영향을 연구하였다. 후막 NTC 서미스터의 저항은 동일한 온도에서 소결한 벌크 상에 비해 높게 나타났으나 저항-온도 특성에서 부 저항 온도 특성은 더 명확하게 직선적으로 나타남을 알 수 있었다. 한편, 소결온도 증가에 따라 면적저항은 감소하였고 프릿트 첨가량이 많을수록 면적저항은 높게 나타났다. 후막 NTC 서미스터의 B 정수는 3000 K 이상의 값 나타냈는데 그 중 프릿트를 5 wt% 첨가한 페이스트로 만든 후막 NTC를 900℃에서 소결한 시편의 B 정수가 가장 높게 나타남을 알 수 있었다. 또한, RuO₂ 첨가에 따라 면적저항의 감소가 나타남을 알 수 있었으며 RuO₂를 5 wt% 첨가한 페이스트를 900℃에서 소결한 후막 NTC 서미스터의 면적저항 감소의 변화가 가장 뚜렷이 나타남을 알 수 있었다.