• Journal of The Geomorphological Association of Korea
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• v.23 no.1
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• pp.61-75
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• 2016

This study aims to reconstruct sea level change and paleogeomorphology since the middle Holocene by diatom analysis and 14C-dating from the sedimentary facies of three trenches on alluvial plain of Taehwa River, Taehwa-dong, Ulsan-si, South Korea. The Taewha-dong area was a narrow bay located between Bangeojin and eatuary of Taehwa River was a narrow bay which has been detached from the open sea during middle Holocene. Taewa-dong area at bay area was developed into alluvial plain by the sediments had been come from the Taewa river basin. The sea level change during the middle Holocene effected on the development of Taewha-dong alluvial plain and its information is included in the sediment facies.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.123-124
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• 2021

Recently, the danger of fine dust has emerged worldwide. In general, fine dust refers to particulate matter less than 10㎛ and ultrafine dust less than 2.5㎛, and according to the announcement by HEI (Health Impact Research Institute) in 2015, the concentration of ultrafine dust in Korea is the second highest among OECD member countries. It was investigated. In this study, an experiment was conducted to analyze how the diatomaceous earth substitution rate affects the strength characteristics of the permeable block. As the replacement rate of diatomaceous earth increased, the strength decreased. The reason why the strength decreases with the use of diatomaceous earth is that the strength of the hardened body decreases as the structure of the hardened body becomes less dense as the amount of diatomaceous earth increases, and the reason that the strength decreases as the replacement rate of diatomaceous earth increases is the reason for the absorption performance of diatomaceous earth. Therefore, it is judged that a void was generated inside the hardened body while water was absorbed and then evaporated or discharged in the matrix, and accordingly, the strength decreased.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.62-62
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• 2003

최근 연안 자원이 급격하게 감소하고 있고 새로운 양식 대상종으로 평가되고 있는 말쥐치의 대량 종묘생산을 위해서는 수정난 대량확보와 자어기 먹이생물 구명 등의 문제점이 해결되어야 한다. 본 연구자들은 우선 호르몬 처리에 의한 산란유도, 조기성숙유도에 의한 조기산란유도 및 수정난 확보방법을 개발하고, 위내용물 분석을 통한 자어의 초기먹이생물을 구명하고자 하였다. 산란유도를 위하여 hCG, LHRH-a 및 hCG+LHRH-a를 다양한 농도로 처리하여 실험한 결과 모든 실험구에서 67~76%의 수정률을 나타내었으나, 대량의 성숙란을 얻지는 못하였다. 따라서 본 종의 산란특성이 다회성인 점을 감안한다면 500 g 전후의 친어 200~300마리를 1개의 수조에 수용하여 자연산란된 수정란을 수거하는 것이 좋을 것으로 판단되었다. 평균 450 g 정도의 말쥐치 친어를 12월부터 6개월동안 천천히 수온을 상승시켜 자연산란을 유도한 결과, 자연산란기 (6월)보다 2개월 빠른 4월 15일(17$^{\circ}C$로 가온한 지 15일)에 첫 산란이 이루어졌고 1개월간 지속되었다. 초기 사육환경을 구명하기 위한 실험에서는 일반적으로 해산어 종묘 생산에 이용하는 클로렐라＋rotifer 실험군이 클로렐라 단독, 규조류 단독, 규조＋rotifer, 녹조＋copepods등이 번식된 환경보다 생존율에 있어 월등히 높은 결과를 나타내었다. 위 내용물 분석에 의한 사육기간 중 섭식한 주요 먹이생물종은 부화 후 5일부터 20일째까지는 rotifer egg, 부화 10일째는 rotifer egg와 small rotifer, 부화 20일째는 rotifer, Artemia sp., copepods, 부화 25일째부터는 copepods였다. 초기성장은 부화직후 전장 1.95 mm였던 것이 10일째는 2.96 mm, 20일째는 3.89 mm, 30일째는 12.9 mm, 50일째는 35.1 mm를 나타내었다. 그러나 말쥐치 자ㆍ치어가 성장함에 따라 발생하는 지속적인 폐사와 종묘의 수송시 발생하는 폐사를 줄일 수 있는 방법이 추후에 해결되어야 할 것으로 사료된다.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.92-92
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• 2003

본 연구는 부착규조류에 따른 부착성 요각류 Tigriopus japonicus의 nauplius 생산력을 알아보기 위하여 실시하였다. 실험에 사용된 T. japonicus는 부산 동백섬 부경대학교 수산과학연구소 부근에 있는 tidal pool에서 동물성부유생물망으로 채집하였다. 먹이생물로는 부경대학교 한국해양 미세조류 은행에서 보관중인 부착규조류 중 중형종인 Caloneis schroder를 대표종으로 이와 크기가(14.8~27.5$\mu\textrm{m}$) 유사한 종들을 대상으로 형태를 현미경 하에서 관찰하고, 지역과 분리일자 등을 고려하여 유사종을 선별한 후 최종적으로 종의 유전적 유사성을 밝히기 위하여 RAPD-PCR (random amplified polymorphic DNA polymerase chain reaction)을 실시하였다. 이 중 Caloneis schroder와 유전적으로 유사성이 낮은 Navicula spp. (KMCC B-245, 393, 394, 581) 4종을 선별하여 T. japonicus의 먹이로 사용하여 포란한 암컷의 nauplius 생산력을 3반복 조사하였다. Genomic DNA는 대부분의 종에서 성공적으로 검출되었으며, 종에 따라 PCR 증폭산물이 나타나지 않은 경우도 있었으므로, PCR 산물이 나타난 종에 대해서만 분석하였고, 증폭된 DNA band는 대부분 크기 0.5~2.0kb 범위에서 나타났다. 실험에 사용된 부착규조류 간의 유사성을 알아보기 위하여 similarity matrix를 분석한 결과 F값의 범위는 0.00에서 1.00까지 였으며, Caloneis schroder와 유사성이 낮은 종들에 비하여 유사성이 높은 종들이 더 많이 나타났다. 이들을 먹이로 하여 포란한 T. japonicus의 실험구별 nauplius 평균 개체수를 살펴보면, KMCC B-394가 255.7마리로 가장 높았던 반면 KMCC B-581가 29.7마리로 가장 낮았다. 그 외 KMCC B-245가 120.0마리, KMCC B-393가 76.0마리, Caloneis schroder가 32.3마리 각각 나타났다. 이와같은 결과를 볼 때 T. japonicus의 nauplius 생산력은 규조 종에 따라 큰 차이가 있는 것으로 판단된다.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.70-77
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• 2004

In order to the epilithic diatom community and an assessment of water quality with diatom assemblage index of organic water pollution (DAlpo) in the middle reaches of the Nakdong River, the samples were collected from nine sampling stations on May, July, September, November, 2002 and on January 2003. A total 162 taxa was identified from this study, which were classified into 139 species and 23 varieties belonging to 33 genera. Achnanthes minutissima, Navicula subminuscula, Navicula viridula var. rostellata, Nitzschia inconspicua and Nitzschia palea indentified in every stations and examination for the whole periods. A total of 12 taxa was dominant species at any station at least one more times. In this study, average DAlpo was 30.90 ${\sim}$ 44.61 and the saprobic level was estimated ${\beta}$-mesosaprobic in the middle reaches of the Nakdong River.

• Korean Journal of Environmental Biology
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• v.30 no.3
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• pp.272-279
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• 2012

This was the second study on the ecological characteristics of the epiphytes on seagrass leaf. The objective of this study was to understand the variation of epiphytes on seagrass leaf depending on the change of physico-chemical factors such as salinity, nutrients, and etc. This study showed the four results. 1) The eelgrass growth was influenced by water temperature, suggesting the positive correlation between eelgrass growth and water temperature. 2) The epiphytes growth on seagrass leaves did not show the correlation with water temperature, but negatively correlated with salinity. 3) The eelgrass growth decreased when the concentraion of nitrogen increased. 4) However, loads of epiphytes increased when the concentration of total nitogen (TN), nitrate ($NO_3^-$), and nitrite ($NO_2^-$) were high. This increase of epiphytes growth could be suggested in the cause-effect pathway of nutrient enrichment leading to seagrasses loss.

• 한국해양학회지
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• v.26 no.1
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• pp.67-76
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• 1991

Masan Bay is infamous for its severe eutrophication, exemplified by frequent red tide incidences and anoxic conditions. We carried out daily observations for 16 days at one site immediately after the summer rainy season in 1988 on the basis that shorter observation intervals be necessary to observe a process with high turnover rate. in spite of the relatively short survey period, we could observe dramatic changes in abundance and composition of the phytoplankton populations. Cell densities and chlorophyll concentrations changed in the magnitude of 70 and 10 times, respectively, Skeletonema costatum, a diatom species, dominated the first peak of phytoplankton biomass and was followed by Prorocentrum minimum, a dinoflagellate species, which occurred dominantly in the second peak after about a week, form the viewpoint of time scale, we suggest that at least a weekly sampling might be appropriate in complex coastal environments as Masan Bay. While stratification enabled high production in the surface layer, it hindered the transport of silicate from bottom to the surface, which in turn limited the prolonged growth of diatoms. Ensued second peaks of silicate and diatom abundance in the surface layer suggest periodic flux of silicate from bottom across the discontinuity driven by tidal currents.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.531-537
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• 2012

The information about the physicochemical environments, the species distribution and community of the epilithic diatom cells in Pyengchang river and inflow streams of Gangwon-do were studied for assessment of biological water quality from June 2008 to October 2010. Total 112 diatom taxa were identified with 2 orders, 9 families, 26 genera, 95 species and 17 varieties. Among the total taxa identified, 13 taxa, 52 taxa and 15 taxa represented the family Achnanthaceae, Naviculaceae and Bacillariaceae, respectively. The pH values of the water was found to be neutral to alkaline due to the limestone grounds of Pyengchang river and inflow streams. The 13 taxa including Epithemia adnata, belonged to alkaline-water diatoms, and three species - Cymbella japonica, Eunotia major and Fragilaria capitellata - are known to be acidic-water species. The species, Hannaea arcus, known as a cryophilic and mountain periphyton was identified at IF2, IF3 and IF4 in low water temperature environments at high altitudes, being a dominating species in P1 and IF1. Four saproxenous species - Achnanthes convergens, Cocconeis placentula var. lineata, Cymbella turgidula and Hannaea arcus - were dominant at some sampling sites. For biological water quality assessment, IF2, IF3 and P3 showed low water quality class. The values of DAIpo and TDI were 10.6 ~ 98.0 and 13.8 ~ 94.2, respectively. Therefore, biological water quality in Pyengchang river and inflow streams was relatively desirable.

• Journal of Wetlands Research
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• v.10 no.2
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• pp.15-22
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• 2008

The role and distribution of fresh water algae was surveyed at Wangdeungjae Wetland of Mt. Jiri, a high mountain swampy land. Mean environmental factors were as follows; temperature was $17.6^{\circ}C$, pH was 6.3, conductivity was $24.6{\mu}S/cm$, TN was 0.6 mg/L, TP was 0.09 mg/L, and Chl-a was $11.9{\mu}g/L$, respectively. Algae were appeared 159 species(Chlorophyta 87, Bacillariophyta 56, Euglenophyta 11, and Cyanophyta 5). Desmid of Chlorophyta was 56 species, and dominant species was Aulacoseira distans of Bacillariophyta. To analyze food chain of the water ecosystem, we performed analysis of tadpole's stomach captured in the wetland. Tadpoles ingested mainly algae, and Aulacoseira distans was found in most quantity. Based on this study, algae take role of the primary producer as well as the prey of higher level predators(e.g. tadpoles) in the water ecosystem of Wangdeungjae Wetland.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.925-934
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• 1994

Nickel recovered from the spent oil-hydrogenation catalysts was used in hydrogenation catalyst preparation. The spent catalyst contains approximately 21.8% Ni, 0.7% Mg, and small quantities of Al, Fe, and Zn. Nickel recovery was obtained by inorganic acid digestion in the order of HCI>$NHO_3$>$H_2SO_4$. For $HNO_3$, 3hour extraction with 3N solution was satisfactory. In the PH range of 6.5~9.0, Ni recovery was higher, but metallic impurities were found to be coprecipitated. The PH in the range of 7.0~9.0 seems to be the optimum condition for separation to obtain acceptable Ni precipitates without the decrease of purity. The catalysts prepared with reclaimed nickel by wet reduction methods showed catalytic activities close to those prepared using reagent nickel in the oil hydrogenation reaction. The surface areas of the support do not seem to affect the catalytic activity.