• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.101-111
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• 2017

The objective of this study is to determine the effectiveness of a modified air-side economizer in improving indoor air quality (IAQ). An air-side economizer, which uses all outdoor air for cooling, affects the building's IAQ depending on the outside air quality and can significantly affect the occupants' health, leading to respiratory and heart disease. The Air Quality Index (AQI), developed by the US Environmental Protection Agency (US EPA), measures air contaminants that adversely affect human beings: PM10, PM2.5, SO2, NO2, O3, and CO. In this study, AQI is applied as a control for the operation of an air-side economizer. The simulation is analyzed, comparing the results between the differential enthalpy economizer and AQI-modified economizer. The results confirm that an AQI-modified economizer has a positive effect on IAQ. Compared to the operating differential enthalpy economizer, energy increase in an operating AQI-modified economizer is 0.65% in Shanghai and 0.8% in Seoul.

• International Journal of High-Rise Buildings
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• v.11 no.4
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• pp.265-276
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• 2022

Double-Skin Facades (DSF) on tall buildings are becoming increasingly common in urban environments due to their ability to provide architectural merit, passive design, acoustic control and even improved structural efficiency. This study aims to understand the effects of porous DSF on the aerodynamic characteristics of tall buildings using wind tunnel tests. High Frequency Force Balance and pressure tests were performed on the CAARC standard tall building model with a variable porous DSF on the windward face. The introduction of a porous DSF did not adversely affect the overall mean forces and moments experienced by the building, with few differences compared to the standard tall building model. There was also minimal variation between the results for the three porosities tested: 50%, 65% and 80%. The presence of a full-height porous DSF was shown to effectively reduce the mean and fluctuating wind pressure on the side face of the building by about 10%, and a porous DSF over the lower half height of the building was almost as effective. This indicates that the porous DSF could be used to reduce the design load on cladding and fixtures on the side faces of tall buildings, where most damage to facades typically occurs.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.507-514
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• 2021

A new free-living marine nematode species of the genus Pseudosteineria Wieser, 1956 affiliated with the family Xyalidae is described based on specimens collected from the sediment of a subtidal benthic environmental habitat in the East Sea, Korea. Pseudosteineria varisetis sp. nov differed from its congeners by the combination of the following characteristics: a relatively long body (1,628-1,691 ㎛ long in males), a circular amphideal fovea situated behind the subcephalic setae, the presence of lateral cuticular alae starting from behind the nerve ring, the presence of eight groups of long subcephalic setae, the presence of irregularly distributed variable lengths of somatic setae on the body, solid spicules (43.2-43.9 ㎛ long) with a cephalated proximal end, a long tubular shaped gubernaculum with dorsal swelling, and a conico-cylindrical tail with two to four terminal setae. In this report, we provide a taxonomic description and illustrations of a new species of the genus Pseudosteineria by differential interference contrast microscopy.

• Geomechanics and Engineering
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• v.33 no.4
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• pp.401-414
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• 2023

Organic clays are ideal habitat for flora and fauna. From a geotechnical perspective, organic clays are soft, weak, variable, heterogeneous and flocculated. Portland cement is a universally common stabiliser. However, some organic acids in soil inhibit full hydration and expose cementation products to rapid dissolution. This paper investigates scopes for use of C₃S cement to enable durable cementation. Prospects of using PP fibre alongside with C₃S cement, scopes for partial replacement of C₃S cement with a plant-based nanosilica and evolution of binders are then investigated. Binding mixtures here mimic the natural functions of rhizoliths, amorphous phases, and calcites. Testing sample population include natural and fibre-reinforced clays, compact mixes of clay - C₃S cement, clay - nanobiosilica, and clay, C₃S cement and nanobiosilica. Benefits and constraints of C₃S cement and fibres for retaining the naturally flocculated structure of organic clays are discussed. Nanobiosilica provides an opportunity to cut the C₃S content, and to transition of highly compressive organic clays into an engineered, open-structured medium with >0.5 MPa compressive strength across the strains spanning from peak to 1.5-times peak.

• Journal of Species Research
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• v.13 no.3
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• pp.332-339
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• 2024

The filamentous freshwater red alga Compsopogon caeruleus(Compsopogonophyceae, Compsopogonaceae, Rhodophyta) occurs in tropical and subtropical regions of worldwide. This species has been reported from Asia, America, Africa, Europe and Oceania, and the worldwide distribution of Compsopogon caeruleus is in variable water habitats. Several morphospecies of the genus Compsopogon had been recorded, but recent molecular phylogenetic analyses with worldwide sampling identified a monospecific genus, C. caeruleus. In the present study, we first report a freshwater red alga Compsopogon caeruleus from Korea. We identified Compsopogon caeruleus in an urban river in Yongin City, and analyzed its morphological and genetic characteristics. Nuclear 18S rDNA, plastidal rbcL gene and mitochondrial cox1 gene sequences isolated from Korean Compsopogon caeruleus showed high sequences similarity with Compsopogon caeruleus from worldwide (98.6-100% (18S rDNA), 99-100% (rbcL) and 97.7-100% (cox1)). These sequences similarities support the identification of a red alga found in Korea as Compsopogon caeruleus. This new geographical report provides the useful information for understanding the distribution and habitat range of Compsopogon caeruleus especially concerning urban freshwater environments.

• Journal of Korean Society of Forest Science
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• v.105 no.4
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• pp.401-413
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• 2016

Forest resources utilization and variable disturbance history have been affected the rarity and conservation value of forest relict trees, which served as habitat for forest biodiversity, important carbon stock and cultural role include human and natural history in South Korea. This study was conducted to establish the baseline data for forest resources conservation by clarifying species diversity, spatial distribution and ecological characteristics (individual and habitat) of forest relict trees (DBH > 300 cm) based on the data getting from mountain trail, high resolution aerial photos and field professionals and field survey. As results, 54 taxa (18 family 32 genus 48 species 1 subspecies 3 variety and 2 form) as about 22% of tree species in Korea was identified in the field. 837 individuals of forest relict trees were observed and the majority of the trees was in Pinaceae, deciduous Fagaceae and Rosaceae, which families are abundant in population diversity. High elevation area was important to relict trees as mean altitudinal distribution was 1,200 m a.s.l as likely affected by human activity gradients and mid-steep slope and North aspect was important environment for the trees remain. Many individuals exhibited 'damage larger branch' (55.6%) and consequent relatively lower mean canopy coverages (below 80%). Synthetically, present diversity and abundance of relict forest trees in South Korea were the result of complex process among climate variation, local weather and biological factors and the trees of big and old were estimated to important forest biodiversity elements. In the future, clarifying the role and function of relict trees in forest ecosystem, in- and ex- situ programmes for important trees and habitat, and activities for building the background of conservation policy such as "Guideline for identifying and measurement of forest relict trees".

• Korean Journal of Environment and Ecology
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• v.29 no.3
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• pp.333-343
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• 2015

This research aims at identifying the goshawk's possible and replaceable breeding ground by using the MaxEnt prediction model which has so far been insufficiently used in Korea, and providing evidence to expand possible protection areas for the goshawk's breeding for the future. The field research identified 10 goshawk's nests, and 23 appearance points confirmed during the 3rd round of environmental research were used for analysis. 4 geomorphic, 3 environmental, 7 distance, and 9 weather factors were used as model variables. The final environmental variables were selected through non-parametric verification between appearance and non-appearance coordinates identified by random sampling. The final predictive model (MaxEnt) was structured using 10 factors related to breeding ground and 7 factors related to appearance area selected by statistics verification. According to the results of the study, the factor that affected breeding point structure model the most was temperature seasonality, followed by distance from mixforest, density-class on the forest map and relief energy. The factor that affected appearance point structure model the most was temperature seasonality, followed by distance from rivers and ponds, distance from agricultural land and gradient. The nature of the goshawk's breeding environment and habit to breed inside forests were reflected in this modeling that targets breeding points. The northern central area which is about $189.5 km^2$(2.55 %) is expected to be suitable breeding ground. Large cities such as Cheongju and Chungju are located in the southern part of Chungcheongbuk-do whereas the northern part of Chungcheongbuk-do has evenly distributed forests and farmlands, which helps goshawks have a scope of influence and food source to breed. Appearance point modeling predicted an area of $3,071 km^2$(41.38 %) showing a wider ranging habitat than that of the breeding point modeling due to some limitations such as limited moving observation and non-consideration of seasonal changes. When targeting the breeding points, a specific predictive area can be deduced but it is difficult to check the points of nests and it is impossible to reflect the goshawk's behavioral area. On the other hand, when targeting appearance points, a wider ranging area can be covered but it is less accurate compared to predictive breeding point since simple movements and constant use status are not reflected. However, with these results, the goshawk's habitat can be predicted with reasonable accuracy. In particular, it is necessary to apply precise predictive breeding area data based on habitat modeling results when enforcing an environmental evaluation or establishing a development plan.

• Journal of Plant Biotechnology
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• v.39 no.1
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• pp.75-80
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• 2012

$Kalopanax$ $pictus$ is a long-lived deciduous perennial tree in the family Araliaceae mainly distributed in the East Asia. In Korea, this species is of ecological and medical importance. Because typical populations of this species are small and distributed in patches, $K.$ $pictus$ has been considered as a narrow habitat species. To understand the genetic diversity and population structure of this species, the sequence variation of the nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) region was analyzed among 18 different $K.$ $pictus$ populations in the present investigation. The nrDNA ITS sequences of Korean populations investigated in this study showed identical of 616 bp in length, and no any nucleotide variation was found in the entire nrDNA ITS region sequence. This result suggested that the $K.$ $pictus$ populations in Korea might belong to the same isolate, and no mutation was found in the nrDNA ITS region. Compared with other known ITS sequence sources from $K.$ $pictus$ populations, only four variable nucleotide sites were found within the entire ITS region. Very narrow genetic diversity appearing in the population level of $K.$ $pictus$ makes us hypothesize that their relatively isolated habitats. The long-lived traits might be one main reason. However, another probability was that the nr-DNA ITS region might be noneffective in classifying populations of $K.$ $pictus$. Thus, to further understand the phylogenetic relationship of $K.$ $pictus$ populations, more samplings should be performed based on more DNA sequences.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.512-522
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• 2012

This study is focused on fish fauna and distributional features along with physical gradients and stream orders in the Tamjin River basin, Korea. Fish sampling and investigation were conducted for 2 years from 2009 to 2010. Total number of fish species collected were 47 species of 16 family. The group of cyprinidae was mostly abundant. Both fish abundance and biotic index were declined with increasing altitude and longitudinal distance from the river mouth. Two species of Zacco temminckii and Pungtungia herzi were prevalent in most of sampling sites and showed no altitudinal and longitudinal differences. Most other species, however, were spatially restricted to specific regional altitudes. Several species including Zacco platypus, Squalidus gracilis majimae and P. herzi were broadly distributed from river mouth to 50 km. Eight species including Z. temminckii and Rhynchocypris oxycephalus only appeared in over 10 km from the river mouth. Both Odontobutis platycephala and Pseudobagrus koreanus were classified as "upstream dewelling species" observed only in over 30 km from the river mouth. High proportion of tolerant and omnivorous species were more dominated in the downstream zone of the dam, whereas intolerant and insectivorous species were abundant in the upstream zone of the dam. The variable of stream order showed positive relationship between number of fish species and total individuals collected. Sensitive species including insectivore had a declining tendency with increasing stream order, while tolerant specie including omnivore species had relatively increased with stream order. Overall, our study suggested that fish distribution considerably depends on altitudinal gradient and longitudinal distance from the river mouth as well as physical habitat.

• ALGAE
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• v.32 no.4
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• pp.325-336
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• 2017

Intertidal community recovery and resilience were investigated with quantitative and qualitative perspectives as a function of disturbance timing. The study was conducted in a lower intertidal rock bed of the southern coast of South Korea. Six replicates of artificial disturbance of a $50cm{\times}50cm$ area were made by clearing all visible organisms on the rocky substrate in four seasons. Each of the seasonally cleared plots was monitored until the percent cover data reached the control plot level. There was a significant difference among disturbance timing during the recovery process in terms of speed and community components. After disturbances occurred, Ulva pertusa selectively preoccupied empty spaces quickly (in 2-4 months) and strongly (50-90%) in all plots except for the summer plots where non-Ulva species dominated throughout the recovery period. U. pertusa acted as a very important biological variable that determined the quantitative and qualitative recovery capability of a community. The qualitative recovery of communities was rapid in summer plots where U. pertusa did not recruit and the community recovery rate was the lowest in winter plots where U. pertusa was highly recruited with a long duration of distribution. In this study, U. pertusa was a pioneer species while being a dominant species and acted as a clearly negative element in the process of qualitative recovery after disturbance. However, the negative effect of U. pertusa did not occur in summer plots, indicating that disturbance timing should be considered as a parameter in understanding intertidal community resilience in temperate regions with four distinct seasons.