• 한국환경과학회지
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• 제16권10호
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• pp.1119-1125
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• 2007

We examined the horizontal distribution of salinity and the concentrations of DIN and DIP after heavy rain-fall events in coastal areas of South Korea from Yeoja Bay to Narodo and from Gwangyang Bay to Geomodo to determine whether fresh water actually flows into areas of Cochlodinium polykrikoides red tides and to observe its effect on the growth of this organism after heavy rainfall. Following heavy rainfall (155 mm) in the Yeosu and Suncheon regions, the average salinity was 21 and 29 psu at Yeoja Bay and in the coastal waters of Narodo, respectively. After 126 mm of rainfall, the values were 19 and 25 psu in the coastal waters of Yeosu and Geomodo, respectively. This may have been caused by an influx of fresh water, after the rainfall event, into the open sea coastal areas around Narodo and Geomodo from the Dong and Seomjin Rivers, which are about 3540 km away. After the rainfall, the concentrations of $NH_4-N,\;NO_2-N$, and $PO_4-P$ were slightly increased; however, the concentration of $NO_3-N$ was greatly increased and diffused throughout the coastal areas of Narodo and Geomodo, which frequently experience C. polykrikoides blooms. The influence of $NH_4-N,\;NO_2-N$, and $PO_4-P$ on the occurrence of C. polykrikoidesred tides in coastal areas around Narodo and Geomodo after heavy rainfall does not appear to be great. Instead, the occurrence C. polykrikoides red tides in the coastal areas of Narodo and Geomodo seems to be facilitated by $NO_3-N$.

• 한국환경과학회지
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• 제25권6호
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• pp.865-875
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• 2016

In this study, mass concentrations and chemical compositions of $PM_{2.5}$, including water-soluble ions and elements were determined at the 1,100 m-highland of Mt. Hallasan in Jeju Island across four seasons from August 2013 to August 2014. The average mass concentration of $PM_{2.5}$ was $12.5{\pm}8.41{\mu}g/m^3$ with 45.8% of the contribution from eight water-soluble ionic species. Three ionic species ($SO{_4}^{2-}$, $NH{_4}^+$, and $NO{_3}^-$) comprised 96.2% of the total concentration of ions contained in $PM_{2.5}$ and were the dominant ions, accounting for 43.5% of the $PM_{2.5}$ mass at Mt. Hallasan. On the basis of the mass concentration level, seasonal variation, enrichment factor, and relationship among elements, we can presume that Mg, K, Ca, Mn, Fe, Co, Sr, Ba, Nd, and Dy originated mainly from crust or soil and that V, Cr, Ni, Cu, Zn, As, Cd, and Pb were significantly enriched in $PM_{2.5}$ owing to the effects of the anthropogenic emissions. These results and the local distribution of emission sources and topographic characteristics near this sampling site suggest that the compositions of $PM_{2.5}$ collected at the 1100 m-highland of Mt. Hallasan were largely influenced by inflow from outside of Jeju Island.

• The Korean Journal of Ecology
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• 제25권1호
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• pp.63-70
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• 2002

This study examined the changes of water quality in relation to distribution of hydrophytes, and the purification capacity of Zizania latifolia to improve the effluent from Munpyeong stream from March 1997 to December 1999. While the concentration of nitrogen and phosphorous in water were increased during the farming season, those decreased, during the streaming down to paddy and drainage areas. In investigated sites, the Z. latifolia was dominant community according to the development of the natural wetlands. Furthermore, it formed a large community owing to its high adaptability to environmental changes in the agriculture lands. In September, the leaves productivity of the Z. latifolia were 4,032g D.W/$m^2$and roots were 7,680gD.W/$m^2$. The purification capacity of the Z. latifolia for NH$_3$-N, $No_3$-N, and PO$_4$-P were 13.41, 17.07, and 4.58 respectively during 5 days. The results suggested that it needs to establish wetlands vegetated by hydrophytes to improve the water quality of the effluent from agricultural lands.

• 미생물학회지
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• 제19권4호
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• pp.163-173
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• 1981

The distribution of methanol-assimilating yeasts on three different sources (elm bark, soil and fresh-water mud) and the growth conditions of a new strain of Candidaboidinii (SIO) wereexamines. From 150 samples, 91 methanol yeasts were isolated through enrichment culture ; they were identified as 77 strains of Candida boidinii including four new strains, 5 isolates of Torulopsis pinus, 3 strains of Hansenula polymorpha and one sstrain of Pichia pastoris respectively. The comparison of these yeasts with three sources indicated that decaying bark of elm tree other two, and that Gandida boidinii was most frequently distributed in all three sources. Four new strains of Candida boidinii were freshly isolated and their taxonomical properties were discussed. Of them, SIO strain was selected and characterized for its growth on methanol. This yeast could grow well on less than 1%(v/v) methanol. However, its growth was inhibited at 10% methanol. The cell yield was 3.1g (dry weight) per 1000ml of mineral mediurr, containing 1%(v/v) methanol as well as 01.% yeast extract as additive. The concentration of 0.1% yeast extract appears to be effective for the biomass production. Optimum conditions for growth on methanol was found to be : $28^{\circ}C,\;NH_4^+$ as nitrogen sources, thiamine as vitamin, and pH 4.5 to 6.0. The cell composition was as follows : crude protein and nucleic acids were 54% and 7% respectively. The amino acids were also described.

• Korean Chemical Engineering Research
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• 제46권5호
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• pp.922-930
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• 2008

질소산화물($NO_x$) 저감을 위한 선택적 무촉매 환원(SNCR; selective non-catalytic reduction) 공정의 성능은 유속, 반응온도 그리고 반응물간의 혼합과 같은 공정변수에 민감하다. 따라서 효율적인 SNCR 공정의 설계와 운전을 위하여 속도장, 온도장, 및 화학물질들의 농도 분포에 대한 이해가 필수적이다. 본 연구에서는 150 kW LPG 버너가 장착되고, 요소용액을 환원제로 사용하는 파일럿 규모 SNCR 공정에 대하여 액적모델과 결합된 2차원 난류반응흐름 전산유체역학(CFD; computational fluid dynamics) 모델을 개발하고, 이 모델은 실험결과를 통하여 검증된다. 난류반응 CFD 모델에서는 $NO_x$저감율과 $NH_3$-slip을 예측하기 위하여 7개 반응식으로 이루어진 요소용액과 $NO_x$와의 반응기작을 이용한다. 이러한 모델을 이용한 CFD 모사결과는 온도와 NSR(normalized stoichiometric ratio)에 따른 $NO_x$ 저감율에서 실험결과와 최대 20% 이내에서 차이를 보여주고 있으며, $NH_3$-slip에 대하여는 실험결과와 모사결과 사이에 유사한 경향성을 얻었다.

• Asian Journal of Atmospheric Environment
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• 제10권3호
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• pp.125-136
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• 2016

In this study, the effects of the mesh barrier on the free dispersion of ammonia were numerically investigated under different atmospheric conditions. This study presents the detail and flow feature of the dispersion of ammonia through the mesh barrier on various free stream conditions to decline and limit the toxic danger of the ammonia. It is assumed that the dispersion of the ammonia occurred through the leakage in the pipeline. Parametric studies were conducted on the performance of the mesh barrier by using the Reynolds-averaged Navier-Stokes equations with realizable k-${\varepsilon}$ turbulence model. Numerical simulations of ammonia dispersion in the presence of mesh barrier revealed significant results in a fully turbulent free stream condition. The results clearly show that the flow behavior was found to be a direct result of mesh size and ammonia dispersion is highly influenced by these changes in flow patterns in downstream. In fact, the flow regime becomes laminar as flow passes through mesh barrier. According to the results, the mesh barrier decreased the maximum concentration of the ammonia gas and limited the risk zone (more than 500 ppm) lower than 2 m height. Furthermore, a significant reduction occurs in the slope of the upper boundary of $NH_3$ risk zone distribution at downstream when a mesh barrier is presented. Thus, this device highly restricts the leak distribution of ammonia in the industrial plan.

• The Korean Journal of Ecology
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• 제28권6호
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• pp.365-373
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• 2005

Understanding the relation of water environmental factors and vegetation is critical to restoration and management of wetlands. To reveal relationships between representative plant groups and water environments, we measured cover and abundance of plant species, water depth, temperature, pH, conductivity, dissolved oxygen, $NH_4$-N, $NO_3$-N, and $PO_4-P$ concentration in water in Wangsuk stream (WS) and Gwarim reservoir (GR). This study was conducted monthly from May to October, 2004. Six vegetation groups $(W1{\sim}W6)$ in WS and five vegetation groups $(G1{\sim}G5)$ in GR were identified using TWINSPAN. WS was characterized by Phragmites japonica, Digitaria sanguinalis, Phalaris arundinacea, Beckmannia xyzigachne and Persicara hydropiper, Persicaria thunbergii, Typha angustifolia. GR was characterized by T. angustifolia, Scirpus tabernaemontani, P. thunbergii, Humulus japonicus and Scirpus fluviatilis, Typha orientalis, Zizania latifolia. The vegetation in WS experienced greater seasonal changes than in GR. A correspondence analysis suggests that water depth was the major environmental factor influencing the distribution of most plants communities in both wetlands.

• 한국물환경학회지
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• 제24권3호
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• pp.383-390
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• 2008

Recently, the interests on economical nitrogen removal from wastewater are growing. As a method of the novel nitrogen removal technology, nitrogen removal via nitrite pathway by selective inhibition of free ammonia and free nitrous acid on nitrite oxidizing bacteria have been intensively studied. The inhibition effects of free ammonia and free nitrous acid are low when domestic wastewater is used, however, because of its relatively lower nitrogen concentration than the wastewater from industry and landfill, etc. In this study, a sequencing batch reactor (SBR) is proposed for nitrogen removal to investigate the effect of the low nitrogen concentration on nitrite accumulation. Nitrification efficiency reached almost 100% during the aerobic cycle and the maximum specific nitrification rate ($V_{max,nit}$) reached $17.8mg\;NH_4{^+}-N/g\;MLVSS{\bullet}h$. During the anoxic cycle, average denitrification efficiency reached 87% and the maximum specific denitrification rate ($V_{max,den}$) reached $9.8mg\;NO_3{^-}-N/g\;MLVSS{\bullet}h$. From the analysis the main reason of nitrite accumulation in the SBR was free nitrous acid rather than free ammonia. Nitrite accumulation increased with the decrease of organic content in the wastewater and the mechanism is not well understood yet. From the result of fluorescent in situ hybridization, the distribution of nitrite oxidizing bacteria was in equilibrium with ammonium oxidizing bacteria when nitrite accumulation did not occur.

• 박물관보존과학
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• 제13권
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• pp.37-44
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• 2012

심수륜(沈秀崙, 1534 ~ 1589)묘 출토복식에서 발견되는 백색 결정의 특징과 분포양상을 조사하고, 그 중 7점에서 시료를 채취하여 성분과 결정구조를 분석하였다. 총 46점 중 36점에서 경도와 형태가 조금씩 다른 백색 결정이 관찰되었는데, 결정의 생성은 직물소재나 복식용도와는 특별한 상관관계가 없었다. 다만, 복식의 앞부분보다는 뒷부분에서 주로 관찰되었으며, 염습 흔적이 있는 곳을 중심으로 분포되어 있는 양상을 보였다. 결정의 성분은 전자현미분석기(EPMA)로 분석하였으며, 결정 구조는 X-선회절분석기(XRD)를 이용하였다. 퓨리어변환적외선분광기(FT-IR)를 이용하여 다른 유기성분이 포함되어 있는지를 조사하였다. 분석결과 백색 결정은 마그네슘 인산염 무기결정인 스트러바이트와 뉴베리아이트로 동정되었다. 스트러바이트 결정의 생성은 Mg²⁺, NH₄⁺, PO₄^3- 이온의 농도, pH, 그리고 온도 등 여러 가지 요인으로 부터 영향을 받는다. 스트러바이트의 구성물질인 마그네슘, 인산, 암모니아는 인체 분해 생성물로 피장자의 인체에서 기인했을 가능성이 있다. 마그네슘의 높은 농도는 회곽에서도 영향을 받았을 것으로 보이며, 또한 관 내부의 혐기성 미생물과 약염기성 환경도 생성의 요인으로 작용하였을 것으로 추정된다. 결과적으로 조선시대의 독특한 무덤양식인 회곽묘는 심수륜 묘 출토복식에서 발견되는 마그네슘 인산염의 생성과 밀접한 관련이 있을 것으로 보인다.

• 해양환경안전학회지
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• 제25권4호
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• pp.457-467
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• 2019

동해 연안의 영양염의 장기간 변동 특성을 파악하기 위하여 2013년부터 2017년까지 5년간 격월별로 속초, 죽변, 감포 연안의 3개 정점에서 수온, 염분, 용존산소, 영양염을 조사하였다. 5년 동안 동해연안에서 수온은 $1.2{\sim}28.8^{\circ}C$, 염분은 30.63~34.79, 용존산소는 3.53~7.64 mL/L의 범위였으며 수온의 연직분포 변동에 따라 환경요인들의 분포와 변동이 결정되고 있었고, 북한한류수의 남하 유입에 의해 2015년과 2016년에 속초연안에서 용존산소가 높게 나타났다. 용존무기질소(DIN, $NH_4-N+NO_2-N+NO_3-N$)의 농도는 $0.11{\sim}24.19{\mu}M$, 인산인의 농도는 $0.01{\sim}1.75{\mu}M$, 규산 규소의 농도는 $0.17{\sim}32.80{\mu}M$의 범위 내에서 변동하였다. 동해연안의 N:P 비는 0.7~54.3(평균 15.2), N:P 기울기는 해역별로 11.67~13.75의 범위로, Redfield 비(16)보다 낮아, 동해연안에서는 대체로 질산 질소가 식물플랑크톤의 성장을 제한하는 영양염인 것으로 나타났다. 전체 N:P 기울기의 상관관계($R^2$)는 0.95로 높아 주변 육상 또는 비점오염원의 영향은 크지 않은 것으로 나타났다. 결론적으로 동해 연안에서 영양염의 시 공간적 변동은 수온의 성층구조 변동에 따른 저층 영양염의 혼합에 따라 결정되었으며, 외부 수괴 유입과 연안 용승 등의 물리적 요인에 의해 주로 영향을 받고, 육상으로부터 유입에 의한 영향은 적은 것으로 나타났다.