• Environmental Engineering Research
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• 제23권1호
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• pp.28-35
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• 2018

$17{\alpha}-ethinylestradiol$ (EE2), a synthetic estrogen which interfere the endocrine and reproductive function in living organisms, has been found extensively to be deposited into municipal wastewater treatment plants and the environment via human excretion. EE2 has long been known to be efficiently cometabolized by ammonia-oxidizing bacteria (AOB) during ammonia ($NH_3$) oxidation. Current study aims to investigate the effect of culture history on the biotransformation of EE2 by nitrifying sludge which was enriched under different ammonia loading rates in continuous flow reactors. Result showed that past growth condition largely affected not only the metabolic rate of $NH_3$ oxidation but also EE2 cometabolism. Sludge previously acclimated with higher $NH_3$ loads as well as sludge dominated with AOB belong to high growth cluster (Nitrosomonas europaea-Nitrosococcus mobilis) showed higher rate of EE2 biotransformation than those one being acclimated with lower $NH_3$ loads because of its ability to provide more reducing power from $NH_3$ oxidation. Moreover, the correlation between the degradation rates of $NH_3$ and EE2 was higher in sludge being acclimated with higher load of $NH_3$ in comparison with other sludge. Implication of the findings emphasized the role of volumetric $NH_3$ loading rate in determining EE2 removal in wastewater treatment system.

• 천문학회보
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• 제38권1호
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• pp.32.2-32.2
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• 2013

We examine large-scale environmental effects on the formation and the mass growth of dark matter halos. To facilitate this, we constructed dark matter halo merger trees from a cosmological N-body simulation, which enabled us to trace the merger information and the assembly history of individual halos. In fact, since the massive halos are more likely to be distributed in denser regions than in less dense regions (Mo & White, 1996), the large-scale environment dependence of the properties of halos can be partly originated from the halo mass effect. In order to avoid such contamination, caused by the mass dependence of halo properties, we carefully measured the local overdensity as the indicator of large-scale environment, which was calculated to be as independent of halo mass as possible. Small halos (${\sim}10^{11-12}M_{\odot}$), which usually host isolated single galaxies, show a notable difference on the formation time of galaxies depending on their large-scale environments, which reconfirms halo assembly bias (Gao & White, 2007). Furthermore, we investigate how this environmental effect on small halos is correlated with the mass assembly history of galaxies by using our semi-analytic model. We found that assembly bias in small halos does not have significant effects on the formation time or on the star formation history of galaxies residing in those halos except for the individual stellar mass of galaxies at z = 0. On average, isolated galaxies in high-density regions tend to be slightly more massive than those in low-density regions. Although the observational data from the current galaxy surveys is not yet sufficient for testing this prediction, future galaxy surveys will be able to explore these small galaxies more thoroughly.

• 한국지진공학회논문집
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• 제25권2호
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• pp.83-91
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• 2021

Seismic designs for Korean nuclear power plants (NPPs) under earthquakes' design basis are noticed due to the recent earthquake events in Korea and Japan. Japan has developed the technologies and experiences of the NPPs through theoretical research and experimental verification with extensively accumulated measurement data. This paper describes the main features of the design-time history complying with the Japanese seismic design standard. Proper seed motions in the earthquake catalog are used to generate one set of design time histories. A magnitude and epicentral distance specify the amplitude envelope function configuring the shape of the earthquake. Cumulative velocity response spectral values of the design time histories are compared and checked to the target response spectra. Spectral accelerations of the time histories and the multiple-damping target response spectra are also checked to exceed. The generated design time histories are input to the reactor building seismic analyses with fixed-base boundary conditions to calculate the seismic responses. Another set of design time histories is generated to comply with Korean seismic design procedures for NPPs and used for seismic input motions to the same reactor containment building seismic analyses. The responses at the dome apex of the building are compared and analyzed. The generated design time histories will be also applied to subsequent seismic analyses of other Korean standard NPP structures.

• 한국환경보건학회지
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• 제37권3호
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• pp.182-192
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• 2011

Objectives: This study aims to identify the influential factors on the pulmonary function of targeted general residents in the areas surrounding Gwangyang Steel Mill. Methods: An PFT (Pulmonary Function Test) was conducted from May 2007 to November 2007 on 974 target residents (438 male, 536 female), including an exposed group (674 people) who resided within a radius of 5 km from Gwangyang Steel Mill in Gwangyang-si, Jeollanam-do and a control group (300 people) who resided outside a radius of 15 km. A survey related to personal characteristics, life habits, respiratory diseases and allergic symptoms, medical histories and living environments of the residents was also conducted to identify influential factors on pulmonary function. Results: As %$FEV_1$ and %FVC of the exposed group are 99.17% and 96.98%, respectively, and those of the control group are 105.47% and 101.91%, respectively, with the PFT values of the exposed group being lower than those of the control group (p<0.001), it turns out that the pollution in the industrial complex is likely to trigger a reduction in the pulmonary function of local residents. The odds ratio analysis result for asthma diagnosis history indicates that the odds ratios tend to be higher among surveyed residents who are living near above-average traffic volumes and are using beds, where it is statistically meaningful that especially the odds ratios are higher if the residences are closer to roads (p<0.01, CI=1.12-4.52). The factors that affect the FEV1 are identified as smoking, passive smoking, asthma diagnosis history, nasal congestion symptoms and allergic eye disease ($R^2$=0.154, p<0.001). The factors that affect the FVC are identified as smoking, passive smoking, asthma diagnosis history and allergic coryza ($R^2$=0.158, p<0.001). In addition, the analysis result for the relevance of air pollution levels to pulmonary function ($FEV_1$, FVC) shows that FEV1 and FVC tend to decrease as the concentration of $O_3$ increases. Conclusions: We believe that this study may provide preliminary data for the development of preventive measures for health effects on the residents and environmental health control measures for environmental pollution in the industrial complex area.

• 한국환경보건학회지
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• 제38권3호
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• pp.223-232
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• 2012

Objective: We performed this study to determine the association between childhood asthma and residential environment risk factors including VOCs and formaldehyde exposure. Methods: We selected an asthma group (30) and a control gorup (30) through physicain diagnosis and assessed the VOCs and formaldehyde levels of exposure of elementary school children in Seoul. Results: In the results, there were no significant differences in socioeconomic factors between case and control groups. However, there were significant differences in family asthma history, amount of sunlight, level of humidity and number of household residents (p < 0.05). The level of VOC (toluene, ethylbenzene, stylene, m,p-xylene) exposure level of the case group was significantly higher than that of the control group (p < 0.05) and the result of logistic regression showed that asthma family history, amount of humidity and number of household residents were significant predictors of childhood asthma (p < 0.05). Conclusion: Some residential environments such as lower amounts of sunlight, greater amounts of humidity and smaller numbers of household residents and VOC exposure were determinded as risk factors for childhood asthma.

• 한국지진공학회논문집
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• 제22권3호
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• pp.139-147
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• 2018

In the present study, effective hydrodynamic pressure modeling methods for three-dimensional earthquake safety analysis of a dam intake tower structure are investigated. Time history analysis results using the Westergaard added mass and Chopra added mass methods are compared with the one by the CASI (Coupled Acoustic Structural Interaction) method, which is accepted as giving almost exact solutions, to evaluate the difference in displacement response, stress and dynamic eccentricity. The 3D time history analysis of a realistic intake tower, which has the standard geometry widely used in Korea, shows that the Chopra added mass method gives similar results in displacement and stress and less conservative results in dynamic eccentricity to CASI ones, while the Westergaard added mass yields much more conservative results in all measures. This study suggests to use the CASI method directly for three-dimensional earthquake safety analysis of a dam intake tower, if computationally possible.

• 한국환경과학회지
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• 제17권1호
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• pp.119-128
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• 2008

Laboratory analytical results of 22 sets of hydrophobic adsorbent coils containing surface soil-vapor and two soil samples collected by conventional intrusive method from each boring location at two active dry cleaning facilities in the State of Illinois, U.S.A, were presented to evaluate the performance of soil-vapor survey. The most critical factor to determine the effectiveness of soil-vapor survey is the distance from the soil-vapor sampling device to the actual contamination, which is a function of soil porosity, permeability, primary lithology, and other geological and hydrogeological site-specific parameters. Also this factor can be affected by the history of contaminant-generating operations. The laboratory analytical results in this study showed longer dry cleaning operation history (i.e., 50 years) and presence of fine sand at the beneath Site B allow the contaminants to migrate farther and deeper over a fixed time compared to Site A(i.e., 35 years and silty clay) so that the soil-vapor survey is not likely the most effective environmental site investigation method alone for Site B. However, for Site A, the soil-vapor survey successfully screened the site to identify the location reporting the highest soil concentration of chlorinated solvents.

• 한국실내디자인학회논문집
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• 제13권5호
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• pp.154-161
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• 2004

When people visit other countries, the first place to go would be either a museum or an art gallery because it might be the most effective way that people could understand culture and history of the place in a short time. It can be alleged that a museum must be an important cultural space because people can experience their life, history and art there. According to these cultural importance, the purpose of this study is to suggest the environmental design of $\boxDr$Design Museum$\boxUl$ through the Transparency of the Cubism. The Transparency means a capability of transmitting light so that objects on the other side can be seen clearly. The Concept of the Transparency could be taken effects in architecture by overlapping facets or space. By understanding formative properties of the Cubism, which especially focused on Transparency, 1 would like to propose the environment as an art and the exhibition-environment as a way of communication. As it were, the study can be valued as a new approach on condition that formative feature is interpreted with modern terms and the ‘Digital technology’ is not used a tool of representation but a tool of thought in terms of design. Moreover, it has a great significance that formative language of the Cubism will be able to be applied to the environmental design through the experimental and creative design process.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.386-400
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• 2022

Seismic fragility analysis, a part of seismic probabilistic risk assessment (SPRA), is commonly used to establish the relationship between a representative property of earthquakes and the failure probability of a structure, component, or system. Current guidelines on the SPRA of nuclear power plants (NPPs) used worldwide mainly reflect the earthquake characteristics of the western United States. However, different earthquake characteristics may have a significant impact on the seismic fragility of a structure. Given the concern, this study aimed to investigate the effects of earthquake characteristics on the seismic fragility of concrete containments housing the OPR-1000 reactor. Earthquake time histories were created from 30 ground motions (including those of the 2016 Gyeongju earthquake) by spectral matching to the site-specific response spectrum of Hanbit nuclear power plants in South Korea. Fragility curves of the containment structure were determined under the linear response history analysis using a lumped-mass stick model and 30 ground motions, and were compared in terms of earthquake characteristics. The results showed that the median capacity and high confidence of low probability of failure (HCLPF) tended to highly depend on the sustained maximum acceleration (SMA), and increase when using the time histories which have lower SMA compared with the others.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4179-4188
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• 2021

This study identifies efficient earthquake intensity measures (IMs) for seismic performances and fragility evaluations of the reactor containment building (RCB) in the advanced power reactor 1400 (APR1400) nuclear power plant (NPP). The computational model of RCB is constructed using the beam-truss model (BTM) for nonlinear analyses. A total of 90 ground motion records and 20 different IMs are employed for numerical analyses. A series of nonlinear time-history analyses are performed to monitor maximum floor displacements and accelerations of RCB. Then, probabilistic seismic demand models of RCB are developed for each IM. Statistical parameters including coefficient of determination (R²), dispersion (i.e. standard deviation), practicality, and proficiency are calculated to recognize strongly correlated IMs with the seismic performance of the NPP structure. The numerical results show that the optimal IMs are spectral acceleration, spectral velocity, spectral displacement at the fundamental period, acceleration spectrum intensity, effective peak acceleration, peak ground acceleration, A95, and sustained maximum acceleration. Moreover, weakly related IMs to the seismic performance of RCB are peak ground displacement, root-mean-square of displacement, specific energy density, root-mean-square of velocity, peak ground velocity, Housner intensity, velocity spectrum intensity, and sustained maximum velocity. Finally, a set of fragility curves of RCB are developed for optimal IMs.