• 한국산림과학회지
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• 제111권3호
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• pp.385-393
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• 2022

본 연구는 한국 산림생태계의 주요 우점종인 소나무와 졸참나무의 수분 이용 전략을 비교·분석하기 위해, 2019년 3월부터 12월까지 경기도 포천시에서 시행되었다. 소나무(n=6)와 졸참나무(n=3)의 수액속밀도와 환경 변수인 대기 온도, 상대습도, 강수량, 순복사량, 토양수분을 측정하여 계절변화 및 환경 변수에 따른 수액 이동 특성을 분석하였다. 그 결과, 수종의 최대 수액속밀도는 생장 기간(5-10월)에 졸참나무가 소나무보다 2배 가까이 높았으며, 졸참나무는 9월에 소나무는 8월에 가장 높았다. 수액속밀도에 영향을 주는 주요한 환경 변수들은 포화수증기압차와 순복사량이었으며, 대기 온도는 영향을 주지 못했다. 이력현상 분석에서 소나무는 건조해짐에 따라 기공을 닫고 졸참나무는 여전히 기공을 열어두는 전략을 사용하는 것을 발견하였다. 수관전도도 역시 최대 수액속밀도와 비슷한 경향을 보이며, 졸참나무의 수관전도도가 소나무의 수관전도도보다 약 2배 정도 더 높았다. 본 연구에서는 두 수종의 수분 이용 전략을 비교 분석하였고, 더 명확한 기작의 이해를 위해 생리적 특성뿐만 아니라 형태적 특성에 관한 연구도 병행되어야 할 것이다.

• Journal of Mycology and Infection
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• 제23권4호
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• pp.105-110
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• 2018

Background: Otomycosis is a fungal infection that comprises 7~10% of outer ear infections. Although the occurrence is higher in humid climates, relatively few studies have investigated otomycosis occurrences in humid environments. While recurrent chronic otitis media discharge in the ear creates a milieu in which otomycosis is likely to occur, investigations of otomycosis co-occurring with chronic otitis media have been rare. Objective: To examine the characteristics of patients with otomycosis co-occurring with chronic otitis media and identify causative fungi. Methods: The study included 60 patients with chronic otitis media who presented typical otomycosis findings in the outer ear canal and the presence of fungi. Patients were treated in the department of otolaryngology, Daegu Catholic University Medical Center, between July 2011 and June 2018. Results: The mean patient age was 57.77 years, and our study included 20 men and 40 women (p=0.010). The lesion was on the right in 39 patients and on the left in 21 (p=0.020). Ear discharge was the most common chief complaint at diagnosis. Of the 54 patients over age 19, 10 had diabetes (18.5%). Aspergillus was causative in 29 patients and Candida in 31. Aspergillus niger was identified in 15 patients, Aspergillus sp. in 14, Candida parapsilosis in 12, Candida sp. in six, and Candida albicans in five. Conclusion: Otomycosis and chronic otitis media co-occurrences increase with age. The Aspergillus and Candida genera were similar in proportion. A. niger was the most common Aspergillus species, while C. parapsilosis was the most common Candida.

• Journal of Ecology and Environment
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• 제32권2호
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• pp.115-121
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• 2009

In order to elucidate the mechanisms affecting plant distributions in the reclaimed dredging area in the Gwangyang steelworks, in the Gwangyang Bay, Korea, we examined soil characteristics and plant distributions in four study sites and a control site in the study area. Desalination occurring along a gradient with increasing elevation, resulting in decrease of soil pH, EC, P, K, Cl, Ca, Mg, and salt and an increase in soil T-N, silt, clay contents. From site 1 (the lowest-elevation site) to site 5 (the highest-elevation site), halophytes decreased in abundance and nonhalophytes increased. The dominant species in each site were: Phragmites communis, Limonium tetragonum, and 12 additional species at site 1, Carex pumila, Suaeda japonica, and 15 additional species at site 2, Spergularia marina, Scirpus planiculmis, and 22 additional species at site 3, Miscantus sinensis, Lespedeza bicolor, and 26 additional species at site 4 and Pinus thunberii, Rhododendron mucronulatum, and 39 additional species at site 5, which resembled a naturally-occurring P. thinbergii community. Cluster analysis of the vegetation data matrix grouped the 35 plots into 5 major groups, and cluster analysis using the soil environment data matrix revealed 4 major groups. CCA of the floristic and environmental data matrix showed a positive relationship of SAR, EC, Na, Cl, and Ca, which are related to salt, in the $1^{st}$ axis and $2^{nd}$ axis, but negative relationships for altitude, organic contents, silt, and clay contents. Notably, plant species in the reclaimed dredging area that were separated along the $1^{st}$ axis showed strong relationships with factors that related to salt. Long-term exposure to natural rainfall in the reclaimed dredging area changed the soil characteristics, such as salinity. This change in soil characteristics might alter the SAR, which affects plant survival strategies in a given habitat. These results strongly indicated that factors related to salt and elevation play important roles in determining the overall plant distribution in the reclaimed dredging area.

• International Journal of Industrial Entomology and Biomaterials
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• 제9권2호
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• pp.155-165
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• 2004

In Korean Peninsula including neighboring islands and Japanese Islands identical firefly species or the species belonging to same genera occur together in both territories. These geographic firefly species, nonetheless, have never been subject to taxonomic consideration together until recently, lacking clear species status and phylogenetic relationships. A recent serial study of these fireflies using luciferase gene and/or portions of mitochondrial DNA sequences provided some insight into these populations in terms of validity of species name, phylogenetic relationships, and speciation event. In this article, thus, we have reviewed the recent progress on phylogenetic and/or population genetic aspects of these species, i.e., Hotaria-group fireflies, Luciola lateralis, and Pyrocoelia rufa to better understand the firefly species in these regions.

• Journal of Ecology and Environment
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• 제47권1호
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• pp.1-13
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• 2023

Background: The positive effects of Arctic plants on the soil environment and plant-species co-occurrence patterns are known to be particularly important in physically harsh environments. Although three dominant plants (Cassiope tetragona, Dryas octopetala, and Silene acaulis) are abundant in the Arctic ecosystem at Ny-Ålesund, Svalbard, few studies have examined their occurrence patterns with other species and their buffering effect on soil-temperature and soil-moisture fluctuation. To quantify the plant-species co-occurrence patterns and their positive effects on soil environments, I surveyed the vegetation cover, analyzed the soil-chemical properties (total carbon, total nitrogen, pH, and soil organic matter) from 101 open plots, and measured the daily soil-temperature and soil-moisture content under three dominant plant patches and bare soil. Results: The Cassiope tetragona and Dryas octopetala communities increased the soil-temperature stability; however, the three dominant plant communities did not significantly affect the soil-moisture stability. Non-metric multidimensional scaling separated the sampling sites into three groups based on the different vegetation compositions. The three dominant plants occurred randomly with other species; however, the vegetation composition of two positive co-occurring species pairs (Oxyria digyna-Cerastium acrticum and Luzula confusa-Salix polaris) was examined. The plant species richness did not significantly differ in the three plant communities. Conclusions: The three plant communities showed distinctive vegetation compositions; however, the three dominant plants were randomly and widely distributed throughout the study sites. Although the facilitative effects of the three Arctic plants on increases in the soil-moisture fluctuation and richness were not quantified, this research enables a deeper understanding of plant co-occurrence patterns in Arctic ecosystems and thereby contributes to predicting the shift in vegetation composition and coexistence in response to climate warming. This research highlights the need to better understand plant-plant interactions within tundra communities.

• ALGAE
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• 제33권2호
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• pp.157-166
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• 2018

Cryptic species complexes are increasingly recognized in phycological research, obscuring taxonomy and raising questions about factors influencing speciation. A recent exploration of kelp genetic diversity on Haida Gwaii, British Columbia revealed the existence of a new species, Saccharina druehlii, which is cryptic with Saccharina sessilis. This suggests that molecular investigations further north may be required to elucidate the taxonomy and evolutionary history of this lineage. Although, for several decades, S. sessilis was considered a single highly variable species, its taxonomy has been far from straightforward. In particular, Hedophyllum subsessile (Areschoug) Setchell is now recognized as a synonym of S. sessilis in North America, but as a growth form of Saccharina bongardiana in Far East Russia. To resolve this taxonomic confusion, we sequenced mitochondrial (CO1-5P) and nuclear (internal transcribed spacer) markers of S. sessilis populations from the Aleutian Islands, Alaska, USA. Interestingly, none of our sequences matched S. sessilis sensu stricto. Instead, CO1-5P sequences from populations in the central and eastern Aleutians matched exactly S. druehlii with increasing sequence divergence occurring westward. Samples from Attu, the western-most island, composed a genetic group that clearly represents Kjellman's concept of Hafgygia bongardiana f. subsessilis and is distinct enough from S. druehlii and S. sessilis to potentially constitute a distinct species. Therefore, Saccharina subsessilis comb. nov. is proposed for this entity. Our results suggest the existence of a species complex at the crown node of S. sessilis and thus further investigation of Saccharina in Alaskan waters should be conducted to reconstruct the evolutionary history of this fascinating lineage.

• 한국어류학회지
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• 제28권2호
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• pp.79-86
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• 2016

본 연구는 동해 남부 연안에서 출현하는 도화망둑 (Amblychaeturichthys hexanema)과 수염문절 (A. sciistius)의 위 내용물을 분석하여 두 어종의 위 내용물 조성을 조사하고, 종 간 그리고 성장에 따른 먹이자원의 분할이 있는지 연구하였다. 도화망둑과 수염문절은 저서성 갑각류를 주로 섭식하는 저서 섭식 육식성어류였다. 저서성 무척추동물과 부유성 먹이 또한 각각 도화망둑과 수염문절의 먹이로써 중요도가 다소 높았다. 중량비 자료를 이용한 non-metric multidimensional scaling (nMDS)와 다변량 분석 (multivariate analyses)에서 두 어종의 위 내용물 조성은 그 차이가 유의하였다. 그러나 두 어종 모두 성장에 따른 위 내용물 조성 변화에서 차이가 유의하지 않았다. 두 어종이 섭식한 먹이생물의 차이는 섭식 행동의 차이와 관련있다. 결론적으로, 본 연구해역에서 두 어종의 위 내용물 분석 결과는 도화망둑과 수염문절 사이에 생태지위 분리의 증거와 먹이 자원에 대한 종 간 경쟁 감소의 가능성을 보여주었다.

• The Korean Journal of Ceramics
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• 제3권1호
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• pp.37-42
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• 1997

The DC current variation of calcia doped zirconia single crystal was measured under various oxygen containing gases at high temperatures. The DC current was influenced by the gas species for oxygen activity establishment. Also, strong non-ohmic characteristics were observed in the $CO/CO_2/N_2$ gas mixtures. Based on the experimental data obtained by introducing the non-buffering gas $N_2$ into the $CO/CO_2$ mixtures, the processes occurring at the gas/solid interface during a defect relaxation process are discussed.

• Journal of Species Research
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• 제8권4호
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• pp.365-372
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• 2019

We have conducted faunistic study of sea lice collected from marine plankton samples of western and southern coasts of Korea. These specimens were identified as Caligus undulatus Shen and Li, 1959, belonging to family Caligidae and order Siphonostomatoida with worldwide distribution. The range extension of C. undulatus is reported in addition to the previously known distributional range from the Northwest Pacific (China, Japan, and Korea), India, Brazil, and Mexico. This species can be distinguished from all previous reports with characteristics such as overall body proportions of both sexes, structure details of mouth appendages, armature of legs, and some variation in body size. The distributional range of C. undulatus is now given with its northern and south hemisphere limit being 40 to $10^{\circ}N$ in the Indo-Pacific and $30^{\circ}S$ in the Southwest Atlantic. This is the first record of its female occurring in Korea.

• ALGAE
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• 제32권3호
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• pp.199-222
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• 2017

Occurrence of Cochlodinium polykrikoides red tides have resulted in considerable economic losses in the aquaculture industry in many countries, and thus predicting the process of C. polykrikoides red tides is a critical step toward minimizing those losses. Models predicting red tide dynamics define mortality due to predation as one of the most important parameters. To investigate the roles of heterotrophic protists in red tide dynamics in the South Sea of Korea, the abundances of heterotrophic dinoflagellates (HTDs), tintinnid ciliates (TCs), and naked ciliates (NCs) were measured over one- or two-week intervals from May to Nov 2014. In addition, the grazing impacts of dominant heterotrophic protists on each red tide species were estimated by combining field data on red tide species abundances and dominant heterotrophic protist grazers with data obtained from the literature concerning ingestion rates of the grazers on red tide species. The abundances of HTDs, TCs, and NCs over the course of this study were high during or after red tides, with maximum abundances of 82, 49, and $35cells\;mL^{-1}$, respectively. In general, the dominant heterotrophic protists differed when different species caused red tides. The HTDs Polykrikos spp. and NCs were abundant during or after C. polykrikoides red tides. The mean and maximum calculated grazing coefficients of Polykrikos spp. and NCs on populations of co-occurring C. polykrikoides were $1.63d^{-1}$ and $12.92d^{-1}$, respectively. Moreover, during or after red tides dominated by the phototrophic dinoflagellates Prorocentrum donghaiense, Ceratium furca, and Alexandrium fraterculus, which formed serial red tides prior to the occurrence of C. polykrikoides red tides, the HTDs Gyrodinium spp., Polykrikos spp., and Gyrodinium spp., respectively were abundant. The maximum calculated grazing coefficients attributable to dominant heterotrophic protists on co-occurring P. donghaiense, C. furca, and A. fraterculus were 13.12, 4.13, and $2.00d^{-1}$, respectively. Thus, heterotrophic protists may sometimes have considerable potential grazing impacts on populations of these four red tide species in the study area.