• 한국대기환경학회지
• /
• 제13권6호
• /
• pp.475-486
• /
• 1997

The characteristics of atmospheric aerosols were investigated as a function of particle size and water solubility. The atmospheric aerosols were sampled with classifying into 12 size ranges by the use of Andersen low-pressure impactor. Collected aerosol particles were extracted by ultrapure water and filtered to be separated into water-soluble and insoluble components. The concentrations 12 elements in both components were determined by PIXE analysis. And the concentrations of 8 ions in the soluble component were analyzed by ion chromatography. In general, the mass size distribution of particulate matter was represented as a bimodal distribution. The mass size distributions of S$(SO_4^{2-}), K(K^+), Zn and NH_4^+$ skewed to the smaller size range and those of Si, Ca$(Ca^{2+}), Fe, Na^+ and Mg^{2+}$ skewed to the larger size range. They had roughly one peak in the fine and coarse particle region,respectively. On the other hand, the mass size distribution of Ti, Mn, Ni, Cu, $Cl^- and NO_3^-$ were represented as the bimodal distribution. Fe and Si in the aerosol particles extracted into pure water are existing in high insoluble state. Conversely, almost the whole of S is dissolved in water.

• 한국해양환경ㆍ에너지학회지
• /
• 제1권2호
• /
• pp.71-81
• /
• 1998

이 논문에서는 홍도와 마라도에서의 파랑의 통계적 특성을 살펴보았다. 두 지역에서의 스펙트럼법과 시계열에서 얻은 유의파고를 이용하여 파고주기결합분포를 얻었으며 여러 가지 통계적인 특성을 살펴보았다. 주파수의 대역폭이 협대역이 아닌 경우에 개별 파고분포에 롱기히긴스가 제안한 수정레일리분포를 사용할 수 있다. 그러나 이 분포함수는 경험상수를 결정해야하는 불편함 때문에 널리 사용되지 않고 있었다. 본 논문에서는 수정레일리분포의 경험상수를 결정하는 간단한 방법을 제안하였다. 설계파고의 추정에서 서로 다른 분포함수 선택에 따른 영향은 크지 않다. 그러나 스펙트럼법과 시계열에서 얻은 파랑자료 사용에 따라서 한계파고의 추정치는 큰 차이를 보인다.

• 한국해양학회지:바다
• /
• 제23권4호
• /
• pp.179-191
• /
• 2018

황해 동부해역 표층퇴적물의 중금속 분포 특성을 파악하기 위하여 입도, 유기탄소(TOC)와 함께 중금속 원소들(Cu, Pb, Zn, Cd, Cr, Mn, As, Ni, Co, Li, Fe, Al)의 농도를 분석하였다. 연구결과에 따르면, 일부 정점에서 Pb, Mn, As를 제외하면 모든 중금속 농도의 분포는 입도 및 TOC의 분포와 유사하게 황해 중앙해역에서 상대적으로 높고, 한국 연안으로 갈수록 감소하는 경향을 보였다. 입도와 중금속 농도간의 관계를 통하여 대부분의 금속은 입도가 세립할수록 농도가 높게 나타나는 일반적인 경향을 보였다. 그러나 일부 정점에서 Pb은 조립질 퇴적물에서의 암석기원(feldspar) 영향, Mn은 생물기원($CaCO_3$) 영향, As는 중광물(pyrite) 특성에 따라 분포 양상이 다르게 나타났다. 과거에 조사한 자료(2000년)와 비교했을 때, 황해 동부해역에서 지난 15년 동안의 추가적인 중금속 농축은 없었고, 투기해역에 대한 저질환경은 과거에 비해 크게 개선되지 못한 것으로 나타났다. 연구해역 내 모든 중금속의 농도는 한국과 중국에서 규정하고 있는 최소기준(TEL, MSQ-1)보다 낮았지만, 농축지수(enrichment factor; EF), 농집지수(geo-accumulation index; $I_{geo}$), 생태위해성지수(ecological risk index; ERI)는 Cu, Pb, Zn, Cr이 황해 중앙해역에서 상대적으로 높게 나타났다.

• 한국환경보건학회지
• /
• 제50권1호
• /
• pp.66-72
• /
• 2024

Background: Vibrio vulnificus is a serious opportunistic human pathogen that has a worldwide distribution in a variety of marine and estuarine environments. Objectives: For this reason, we investigated the distribution of Vibrio vulnificus in coastal areas of Gyeonggido Province from 2018 to 2022. Also, we analyzed the correlation between V. vulnificus leading to infection and two marine environmental factors (water temperature and salinity). Methods: We collected a total of 266 samples from six coastal area points (i.e., seawater, mudflats). Specimens were isolated using selective plating media and isolated strains were identified by a VITEK 2 system. To find the relevance of the isolation rates of V. vulnificus and number of cases of V. vulnificus infection, we summarized the data on 48 cases of V. vulnificus infection from the open data of the Korea Disease Control and Prevention Agency. Results: Among the 266 samples taken during the investigation period, 47 strains were isolated, and the separation rates of V. vulnificus were 17.7%. The monthly isolation rates of V. vulnificus were ranked in the order of August (53.8%), September (33.3%), June (28.6%), and July (21.1%). There was a positive correlation with the temperature of seawater, but salinity was not significant. The number of cases of V. vulnificus infection reported in Gyeonggi-do Province were 18 (37.5%) in September, 14 (29.2%) in August, and eight (16.7%) in October. The proportion was 83.3%. It was relevant to the isolation rates of V. vulnificus in the marine environmental sources. Conclusions: Our data showed that the number of V. vulnificus infection cases could be affected by changes in the distribution of V. vulnificus due to rise the temperature of seawater in the marine environment.

• 한국대기환경학회지
• /
• 제27권1호
• /
• pp.117-125
• /
• 2011

There are many studies reporting the average carbon dioxide levels in various indoor spaces. However, there have been a few studies showing how carbon dioxide concentration varied at many measurement points in one indoor space. In this study, the changes of indoor carbon dioxide concentration at classroom, library, and kindergarten were reported to find its carbon dioxide distribution change at various locations and altitudes. The maximum carbon dioxide concentration of the 3 sites were measured as 2,684, 2,295, and 1,526 ppm, respectively. These values exceeded the guideline concentration of 1,000 ppm for public places. The concentration of carbon dioxide was higher at upper area than lower area, and this is probably due to the rise of warm breathing air generated from students. In the upper area, the carbon dioxide concentration was higher at center area than four corners. However, in the lower area, the carbon dioxide concentration was higher at four corners than center area. Therefore, it could be concluded that the center of upper area is the best place for the installation of ventilation or carbon dioxide removal system.

• 한국물환경학회지
• /
• 제38권3호
• /
• pp.133-142
• /
• 2022

Natural organic matter (NOM) is a heterogeneous mixture of organic matter with various polarities and molecular weights in an aquatic environment. This study investigated the effects of separation conditions (resin volume, organic matter, etc.) and the repeated use of the resin for the fractionation of organic components in the DAX resin fractionation method. The distribution characteristics of the organic components ((hydrophilic [Hi], hydrophobic acid [HoA], and hydrophobic neutral [HoN]) under the derived fractionation conditions were also analyzed. Constant fractionation results (i.e. HoA/Hi ratio) were obtained in the column capacity factor (i.e. the packed resin volume) in the range of 50 to 100. The resin-packed column maintained constant separation efficiency for up to two repeated uses. The above conditions were applied to wastewater and stream water samples (before and after rainfall). The results showed that the concentration of organic matter in the wastewater effluent was 2-15 times lower with an increased ratio of hydrophilicity to hydrophobicity (i.e. Ho/Hi) compared to the influent depending on the industrial wastewater classification. Particularly, HoN was found to have a high content distribution, 10.2-50.4% of the total dissolved organic matter (DOM), in the effluents. For the stream water, the content of Hi or HoN increased significantly after rainfall, suggesting a correlation with the distribution characteristics of pollutants from the stream watershed. The results provide useful data to enhance the reliability of the DAX resin fractionation and its application to environmental samples.

• 한국수산과학회지
• /
• 제55권5호
• /
• pp.514-523
• /
• 2022

Concentrations of perfluoroalkyl substances (PFASs) were measured in seawater, sediment, and biota collected from Gunsan coast, Korea to investigate their occurrence, distribution, and risk of exposure to humans through seafood consumption. The total concentrations of PFASs in seawater, sediment, and biota ranged from 5.97 to 74.9 ng/L, 0.01 to 13.3 ng/g dry weight, and 0.02 to 5.73 ng/g wet weight, respectively. Predominant PFAS compounds differed across matrices, indicating that the distribution of PFASs in multiple environmental samples is governed by their carbon-chain length. The concentrations of PFASs in seawater were significantly negatively correlated with salinity (P<0.01), suggesting terrestrial input (including land-used PFASs) as the major source of PFAS contamination in coastal environments. The estimated daily intakes (EDIs) of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) through seafood consumption were 0.05 and 0.06 ng/kg body weight/day, respectively. The EDIs of PFOA and PFOS measured in this study were lower those the proposed by the United States Environmental Protection Agency and Canada guidelines, indicating limited health risk for Korean population from PFASs through consumption of seafood from Gunsan coastal environment.

• 한국입자에어로졸학회지
• /
• 제18권3호
• /
• pp.69-77
• /
• 2022

In order to understand the characteristics of fine particles emitted from coal-fired power plant stacks, it is important to analyze the size distribution and components of particles. In this study, particle size distributions were measured using the ejector-porous tube dilution device and an ELPI system at a stack in a coal-fired power plant. Main elemental components of particles in each size interval were also identified through TEM-EDS analysis for the particles collected in each ELPI stage. Particle size distributions based on number and mass were analyzed with component distributions from 0.006 to 10 ㎛. The highest number concentration was about 0.01 ㎛. The main component of the particles consisted of sulfur, which indicated that sulfate aerosols were generated by gas-to-particle conversion of SO2. In a mass size distribution, a mono-modal distribution with a mode diameter of about 2 ㎛ was shown. For the components of PM1.0 (particles less than 1 ㎛), the abundance order was F > Mg > S > Ca, and however, for the components of PM10 (particles less than 10 ㎛), it was in the order of Fe > S > Ca > Mg. The elemental components by particle size were confirmed.

• 한국환경과학회지
• /
• 제33권5호
• /
• pp.283-296
• /
• 2024

This study examined the distribution of airborne metals concentrations and conducted a risk assessment in PM-10 in Gwangju from 2014 to 2022. There were a total of six points, and the concentration of heavy metals at each point was highest in the order of Pyeong-dong(1.5472 ㎍/m³ ) > Nongseong-dong(1.2093 ㎍/m³ ) > Geonguk-dong(1.0100 ㎍/m³ ) > Duam-dong(0.9684 ㎍/m³ ) > Seo-dong(0.9515 ㎍/m³ ) > Nodae-dong(0.8321 ㎍/m³ ). In recent years, the concentration of heavy metals in the atmosphere has generally risen, accompanied by an increase in heavy metals in the soil. The average seasonal concentrations were in the following order: spring(1.4448 ㎍/m³ ) > winter(1.2939 ㎍/m³ ) > fall(0.8303 ㎍/m³ ) > summer (0.5928 ㎍/m³ ). The atmospheric heavy metals most correlated with PM-10 were Ca(0.69), Fe(0.62), Al(0.62) and Mg(0.60). Within the acceptable risk level (1.0E-06) set in this study, heavy metals in the atmosphere were found to have the most excess cancer risk, and the integrated non-cancer risk was as low as 1 or less.

• 대한전기학회논문지:전력기술부문A
• /
• 제54권10호
• /
• pp.500-506
• /
• 2005

With the advent of electric power systems moving to a deregulated retail electricity market environment, calculating distribution service tariffs has become a challenging theme for distribution industries and tariff regulators. As distribution business remains as a monopoly, it is necessary to be regulated. And as multiple distribution companies compete with each other, it would be efficient to adopt competition to the determination of distribution service tariffs. This paper proposes a method to calculate distribution service tariffs using yardstick regulation, which can lead to competition among multiple distribution companies. The proposed method takes into account not only recovering revenue requirements but also the advantages of the yardstick regulation based on long-term marginal costs of distribution network expansion algorithms. A computer simulation is carried out to illustrate effectiveness of the proposed method and it is estimated that the algorithm can be applied to compute the distribution service tariffs under retail electricity markets.