• Clean Technology
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• v.28 no.3
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• pp.203-209
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• 2022

An environmental evaluation was conducted by employing LCA methodology for a mechanical seal manufacturing process that uses recycled silicon recovered from end-of-cycle PV modules. The recycled silicon was purified and reacted with carbon to synthesize β-SiC particles. Then the particles underwent compression molding, calcination and heat treatment to produce a product. Field data were collected and the potential environmental impacts of each stage were calculated using the LCI DB of the Ministry of Environment. The assessment was based on 6 categories, which were abiotic resource depletion, acidification, eutrophication, global warming, ozone depletion and photochemical oxidant creation. The environmental impacts by category were 45 kg CO₂ for global warming and 2.23 kg C₂H₄ for photochemical oxide creation, and the overall environmental impact by photochemical oxide creation, resource depletion and global warming had a high contribution of 98.7% based on weighted analysis. The wet process of fine grinding and mixing the raw silicon and carbon, and SiC granulation were major factors that caused the environmental impacts. These impacts need to be reduced by converting to a dry process and using a system to recover and reuse the solvent emitted to the atmosphere. It was analyzed that the environmental impacts of resource depletion and global warming decreased by 53.9% and 60.7%, respectively, by recycling silicon from end-of-cycle PV modules. Weighted analysis showed that the overall environmental impact decreased by 27%, and the LCA analysis confirmed that recycling waste modules could be a major means of resource saving and realizing carbon neutrality.

• Journal of Life Science
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• v.33 no.1
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• pp.34-42
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• 2023

In a signal transduction network, from the perception of stress signals to stress-responsive gene ex- pression, binding of various transcription factors to cis-acting elements in stress-responsive promoters coordinate the adaptation of plants to abiotic stresses. Among the AP2/ERF transcription factor family genes, group VII ERF genes, such as RAP2.12, RAP2.2, RAP2.3, AtERF73/HRE1, and AtERF71/ HRE2, are known to be involved in the response to hypoxia stress in Arabidopsis. In this study, we dissected the HRE1 promoter to identify hypoxia-responsive region(s). The 1,000 bp upstream promoter region of HRE1 showed increased promoter activity in Arabidopsis protoplasts and transgenic plants under hypoxia conditions. Analysis of the promoter deletion series of HRE1, including 1,000 bp, 800 bp, 600 bp, 400 bp, 200 bp, 100 bp, and 50 bp upstream promoter regions, using firefly luciferase and GUS as reporter genes indicated that the -200 to -100 region of the HRE1 promoter is responsible for the transcriptional activation of HRE1 in response to hypoxia. In addition, we identified two putative hypoxia-responsive cis-acting elements, the ERF-binding site and DOF-binding site, in the -200 to -100 region of the HRE1 promoter, suggesting that the expression of HRE1 might be regulated via the ERF transcription factor(s) and/or DOF transcription factor(s). Collectively, our results suggest that HRE1 contains hypoxia-responsive cis-acting elements in the -200 to -100 region of its promoter.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.50-60
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• 2022

In this study, habitat suitability was analyzed for three major honey tree species, namely Kalopanax septemlobus, Tilia amurensis, and Styrax obassis, in the Baekdudaegan Mountains using MaxEnt models. The AUC values indicating the prediction accuracies of the models were 0.747, 0.790, and 0.755 for K. septemlobus, T. amurensis, and S. obassis, respectively. The most important variables for K. septemlobus and T. amurensis were elevation, mean annual temperature, and slope, whereas mean annual temperature, elevation, and mean annual precipitation were the most important predictors for S. obassis. For all three studied species, elevation and mean annual temperature were the most important topographic and climatic factors, respectively, indicating that such variables are crucial for explaining species distribution. Honey tree species are essential resources in forest beekeeping, a high value-added process for improving forest income, and this study identified sites with the potential for management of such species in the Baekdudaegan Mountains, where it may be possible to establish a honey forest. However, the accuracy of the models should be improved through comprehensive analysis with abiotic variables, such as soil properties and aridity, which affect the distribution of honey tree species, as well as biotic variables, such as interspecific competition.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.19-35
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• 2022

In this study, the forest vegetation structure in the Maruguem (ridge line) area from Yuksipryeong to Cheonwangbong, Baekdudaegan, was analyzed using vegetation classification, importance values, species diversity, and NMS. Data were collected using 373 quadrates in a Braun-Blanquet vegetation survey conducted from May to October 2020. Vegetation was classified into nine vegetation units, which were verified using DCA analysis. Vegetation units 1-5, which were grouped by sub-alpine region, showed high importance values, mainly for sub-alpine vegetation, such as Abies koreana, Picea jezoensis, Pinus koraiensis, and Betula ermanii. In Maruguem, which is not high above sea level, importance values for species such as Pinus densiflora and Quercus serrata were high due to the topographical characteristics of the ridge. The A. koreana community (vegetation unit 1-5), which had a relatively high average elevation, had higher species diversity compared with that of other vegetation units. According to NMS analysis, for abiotic environmental factors, there was a positive correlation between vegetation units 1, 2, 4, and 5 and elevation. Overall, this study describes all low-elevation area vegetation (P. densiflora and Lindera erythrocarpa) to high-elevation area vegetation (A. koreana and P. jezoensis) as well as the characteristics of the Baekdudaegan ridge vegetation that did not include valley vegetation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.276-283
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• 2023

Garlic (Allium sativum L.) is one of the most important vegetables used in various foods in Korea and many countries. The growth of garlic is influenced by various abiotic factors such as cultivation temperature, humidity, minimum temperature duration, and photoperiod. This study investigated the effects of increasing temperatures on the plant growth of the northern- ecotype garlic 'Uiseong' in a temperature gradient tunnel. As a result, temperature increase led to decreases in the bulb diameter, weight, and clove pieces of garlic. The rise of cultivation temperature increased the occurrence rate of incomplete bolting in the Northern-ecotype garlic 'Uiseong', resulting in decreases in productivity and a decrease in the yield of marketable garlic, indicating that temperature increases affect the development of garlic bulb formation. The findings of this study are expected to contribute as foundational data for understanding the growth responses of the northern-ecotype 'Uiseong' to increasing cultivation temperatures. The results of this study can be used to develop designing garlic growth models. In addition, the results of this study can improve understanding the interaction between increased temperature and garlic growth.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.4
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• pp.176-183
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• 2010

In order to understand the temporal variations and species composition of tintinnids, at two stations of the Korea Strait, this study was carried out from January to December 2007 (n=17). Fifty-one species from 22 genera were encountered: 27 neritic species (9 genera) and 24 oceanic species (14 genera). The species composition was different between two stations, and neritic species frequently appeared at St. 1, while oceanic species more frequently appeared at St. 2. According to the frequency in appearance of species, the most dominant species were neritic species such as Stenosemella nivalis and S. pacifica, that appeared in all seasons. Also, Acanthostomella norvegica, Amphorellopsis acuta, Epilpocyloides ralumensis, Protorhabdonella curta and other many oceanic species appeared intensively during the low salinity (${\leqq}33\;psu$) and high water temperature (${\geqq}24^{\circ}C$) period (July~October). The abundance of tintinnids ranged from 0 to 1,845 cells $L^{-1}$. It was higher in the seasons (summer and autumn) of low salinity and high water temperature than in other seasons. The abundance was relatively higher at St. 1 than at St. 2. On the basis of correlation and multiple regression analyses, the tintinnid abundance was not correlated with chi-a, but significantly correlated with water temperature and salinity, suggesting to be the primary abiotic factors influencing the abundance. This study suggests that the complex hydrographic conditions of the study area might influence the temporal distribution and species composition of tintinnids.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.1
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• pp.24-35
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• 2016

To assess the relationship between environmental factors and seasonal phytoplankton community structure, we investigated abiotic and biotic factors in Ulsan Bay, Korea. We divided the bay into two areas based on geographical characteristics and compared the difference in each factor between inner and outer bay with t-test statistics. As a result, temperature in the outer bay was higher than that of the inner bay during winter (t = -5.833, p < 0.01) and autumn (p > 0.05). However, opposite trend was observed during spring (t = 4.247, p < 0.01) and summer (t = 2.876, p < 0.05). Salinity was significantly lower in the inner bay than in the outer bay in winter, spring, and summer (p < 0.01). However, the salinity was not significantly different between the inner and the outer bay in the autumn (p > 0.05). In particular, high nutrient concentration was observed in most stations during winter season due to vertical well mixing. The nutrient concentration was significantly higher in surface layers of inner bay after rainfall, particularly in the summer. The relative contribution (approximately 70%) of < $20{\mu}m$ (nano and pico) size phytoplankton was increased in all seasons with continuously low nutrients from the offshore water due to their adaption to low nutrient without other large competitors. Interestingly, high population of Eutreptiella gymnastica was kept in the inner bay during the spring and summer associated with high DIN (nitrate+nitrite, ammonium) after river discharge following rainfall, suggesting that DIN supply might have triggered the increase of Eutreptiella gymnastica population. In addition, high density of freshwater species Oscillatoria sp. and Microcystis sp. were found in several stations of the inner bay that were provided with large amounts of freshwater from the Tae-wha River. Diatom and cryptophyta species were found to be dominant species in the autumn and winter. Of these, centric diatom Chaetoceros genus was occupied in the outer bay in the autumn. Cryptophyta species known as opportunistic micro-algae were found to have high biomass without competitors in the inner bay. Our results demonstrated that Ulsan Bay was strongly affected by freshwater from Tae-wha River during the rainy season and by the surface warm water current from the offshore of the bay during dry season. These two external factors might play important roles in regulating the seasonal phytoplankton community structures.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.187-196
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• 2000

This paper describes a simple method that uses differences among Carlson's (1977) trophic state index (TSI) values based on total phosphorus (TP), chlorophyll a (CHL) and Secchi depth (SD) to draw inferences regarding the factors that are limiting to phytoplankton growth and the composition of lake seston. Examples are provided regarding seasonal and spatial patterns in a large subtropical lake (Lake Okeechobee, Florida, USA) and inter- and intra-lake variations from a multilake data set developed from published studies. Once an investigator has collected routine water quality data and established TSI values based on TP, CHL, and SD, a number of inferences can be made. Additional information can be provided where it also is possible to calculate a TSI based on total nitrogen (TN). Where TSI (CHL)<>TSI (SD), light attenuating particles are large (large filaments or colonies of algae), and the phytoplankton may be limited by zooplankton grazing. Other limiting conditions are inferred by different relationships between the TSI values. Results of this study indicate that the analysis is quite robust, and that it generally gives good agreement with conclusions based on more direct methods (e.g., nutrientaddition bioassays, zooplankton size data, zooplankton removal experiments). The TSI approach, when validated periodically with these more costly and time-intensive methods, provides an effective, low cost method for tracking long-term changes in pelagic structure and function with potential value in monitoring lake ecology and responses to management.

• Korean Journal of Environmental Biology
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• v.40 no.1
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• pp.112-123
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• 2022

To assess the influence of environmental factors on the phytoplankton community structure and total phytoplankton biomass during four seasons in 2014, we investigated the abiotic and biotic factors at 25 stations in the Busan coastal region. The phytoplankton community and total phytoplankton biomass were strongly dependent on the discharge from the Nakdong River, and the high density of phytoplankton was related with the introduction of the Tsushima Warm Current (TWC), particularly in the thermohaline fronts of the fall season. The relationship between the salinity and nutrient (Dissolved inorganic nitrogen=DIN: R²=0.72, p<0.001 and Dissolved inorganic silicon=DSi: R²=0.78, p<0.001) highly correlated with the river discharge, implying that those nutrients have played a crucial role in the growth of diatom and cryptophyta. The total phytoplankton biomass was highest in the summer followed by autumn, spring, and winter. Diatom and cryptophyta species were dominant species during the four seasons. Additionally, there were strong positive correlations between Chlorophyll a and total phytoplankton biomass (R²=0.84, p<0.001), cryptophyta (R²=0.76, p<0.001) and diatom (R²=0.50, p<0.001), respectively. In particular, we found that there were significant differences in the nutrients, phytoplankton community compositions, and total phytoplankton biomass between the inner and the outer coastal region of Busan, depending on the amount of river discharge from the Nakdong River, particularly during rainy seasons. Therefore, the seasonal change of TWC and river discharge from the Nakdong River serve an important role in determining phytoplankton population dynamics in the Busan coastal region.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.1
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• pp.66-75
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• 2014

This study aims to understand environmental factors that determine spatial distribution of macrozoobenthic community in the southern area (ca 100-500 m depth) of East Sea, Korea, known as a candidate site for carbon storage under the seabed. From sixteen locations sampled in the summer of 2012, a total of 158 species were identified, showing density of $843indiv/m^2$ and biomass of $26.2g\;WW/m^2$, with increasing faunal density towards biologically higher diverse locations. Principal component analysis showed that a total of 33 environmental parameters were reduced to three principal components (PC), indicating sediment, bottom water, and depth, respectively. As sand content was increasing, number of species increased but biomass decreased. Six dominant species including two bivalve species favored high concentrations of ${\Omega}$ aragonite and ${\Omega}$ calcite, indicating that the corresponding species can be severely damaged by ocean acidification or $CO_2$ effluent. Cluaster analysis based on more than 1% density dominant species classified the entire study area into four faunal assemblage (location groups), which were delineated by characteristic species, including (A) Ampelisca miharaensis, (B) Edwardsioides japonica, (C) Maldane cristata, (D) Spiophanes kroeyeri, and clearly separated in terms of geography, bottom water and sediment environment. Overall, a discriminant function model was developed to predict four faunal assemblages from five simply-measured environmental variables (depth, sand content in sediment, temperature, salinity and pH in bottom water) with 100% accuracy, implying that benthic faunal assemablages are closed linked to certain combinations of abiotic factors.