• 한국환경과학회지
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• 제12권4호
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• pp.427-437
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• 2003

An evaluation of the application of SBR and biofilm en small sewerage system was conducted. A newly developed small sewerage system, using SBR, was successfully applied to the nutrient treatment using municipal wastewater. The system was consisted of 6 compartments. Two systems, with SBR (A type) or without SBR (B type), were compared by several parameters (COD, SS, T-N, NH$_4$$\^$+/-N, NO$_3$$\^$-/-N, NO$_2$$\^$ -/-N, alkalinity, pH, DO) in all experimental periods. Also, the time variation of several parameters (DO, pH, NH$_4$$\^$+/-N, NO$_3$$\^$-/-N NO$_2$$\^$-/-N) was examined in a SBR applied sewerage system. T-N removal efficiency of B type Was higher than that Of A type by the effect of nitrification and denitrification even though the COD removal efficiencies were similar. In aeration stage, the pH was decreased from 6.4 to 6.3 within 1 h and increased to 6.65 at the end of aerobic stage, and pH was decreased to 6.2 in non-aeration stage, and these phenomena were explained. The effects of nitrification and denitrification were compared in A type and B type sewerage system, and the typical nitrification and denitrification were observed in B type sewerage system.

• Asian-Australasian Journal of Animal Sciences
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• 제10권1호
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• pp.98-105
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• 1997

Sudax fodder (Sorghum sudanense ${\times}$ Sorhum vulgare) was ensiled in laboratory silos with or without 20, 30, or 40 percent broiler litter and 6 percent molasses with or without Candida yeast. The samples were analyzed for pH, lactic acid and nitrogen fractions at the start of the experiment and at 5 days interval, thereafter till 40 days. A sharp decline in pH and increase in lactic acid content was observed on fifth day of ensiling. Thereafter, the rate of pH decline decreased till 20 days and that of lactic acid increase till 25 days and the remained constant. Increasing levels of broiler litter had adverse effect on pH drop and lactic acid increase of silages. Total-N content of the silages had little variation throughout the ensiling period. A sharp decline in protein-N and increase in ammonia-N content was observed on day 5 of ensiling. Thereafter, the content of protein-N increased till 20 days and that of ammonia-N decreased till 15 days, but these changes were very small compared to that occurred during the first 5 days of ensiling. The level of broiler litter had inverse relationship with protein degradation and direct relationship with ammonia production. The yeast inoculum failed to produce any significant effect.

• Membrane and Water Treatment
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• 제10권3호
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• pp.201-206
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• 2019

In this study, we performed an electrowinning process for effective removal of metals (Cu and Ni) in solution and their recovery as solid forms. A complete removal of Cu and Ni (1,000 mg/L) was observed during four times recycling test, indicating that our electrowinning system can ensure the efficient metal removal with high stability and durability. In addition, we investigated effect of operation parameters (i.e., concentration of boric acid only for Ni, variation of pH, concentration of electrolyte ($H_2SO_4$), and cell voltage) on the efficiency of metal removal (Cu and Ni) during the electrowinning. The addition of boric acid significantly enhanced removal efficiency of Ni as the concentration of boric acid increased up to 10 g/L. Compared to negligible pH effect (pH 1, 2, and 4) on the Cu removal, we observed the increase in removal efficiency of Ni as the pH increased from 1 to 4. The electrolyte concentration did not significantly influence the removal of Cu and Ni in this study. We also obtained great removal rates of Cu and Ni at 2.5 V and 4.0 V, which were much faster than those at lower voltages. Finally, almost 99% of each Cu and Ni (1,000 mg/L) was selectively removed from the mixture of metals by adjusting pH and addition of boric acid after the completion of Cu removal. The findings in this study can provide a fundamental knowledge about effect of important parameters on the efficiency of metal recovery during the electrowinning.

• 한국건설순환자원학회논문집
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• 제6권1호
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• pp.103-110
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• 2011

본 연구는 폐콘크리트로부터 발생한 성토 복토용 순환잔골재의 pH 저감을 목적으로 자연적 처리 방법 및 인위적 처리 방법을 이용하여 순환잔골재의 pH 저감특성을 비교 분석 하고자 하였는데, 그 결과를 요약하면 다음과 같다. 실내방치된 순환잔골재의 경우는 사람의 호흡 등 대기중 높은 $CO_2$농도로 인해 실외방치된 순환잔골재보다, 또한 쌓기 두께가 얇을수록 pH를 저감시킨 것으로 분석된다. 공기투과의 경우 비교적 순환잔골재의 pH저감이 효과적이었는데 이는 고압의 환풍기로 인해 순환잔골재에 원활한 $CO_2$ 공급으로 pH를 저감시킨 것으로 판단된다. 살수처리의 경우 미수화 시멘트의 수화반응을 촉진시켜 수산화칼슘을 용해시키고, 건조과정중 대기중 $CO_2$에 의한 중성화로 pH를 크게 저감시키는 것으로 나타났으며 침수처리에서는 pH 저감 효과가 미흡하였다. $CO_2$촉진의 경우 순환잔골재의 pH저감 효과가 가장 우수한 것으로 나타났는데, 이는 원활한 $CO_2$공급이 가능하기 때문인 것으로 분석된다. 이상의 실험 결과를 종합하면, pH 저감성능, 경제성 및 작업성 측면을 고려할 경우 순환잔골재 질량비 1: 0.5 비율로 살수한 다음, 강제적인 $CO_2$가스의 처리로 건습을 반복한다면 순환잔골재의 pH저감에 가장 효과적인 방법이 될 것으로 분석된다.

• 치위생과학회지
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• 제23권1호
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• pp.51-59
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• 2023

Background: Tea tree oil has antiviral, antimicrobial and antifungal effects and Mastic oil has antifungal and anticancer effects. For synergistic effects of oils, blending oil containing a mixture of two to three oils is recommended. This study aimed to determine the antibacterial effects of Tea tree oil, Mastic oil, and Blending oil containing the two oils in a mixture, to verify and suggest the potential use of these oils as a substance to prevent dental caries. Methods: Tea tree oil, Mastic oil, and Blending oil with a 1:1 blend of the two oils were diluted in liquid medium to 0% (negative control), 0.5%, 1.0%, and 2.0%. Streptococcus mutans was applied to each experimental group of the three diluted oils and after 8 h culture, the optical density (OD) was measured and the growth inhibition rate for S. mutans was estimated. Results: Tea tree oil had significantly low OD values across all concentrations (p<0.05) without significant variation among different concentrations (p>0.05). Mastic oil did not significantly vary in OD compared to the negative control across all concentrations (p>0.05) without significant variation among different concentrations (p>0.05). Blending oil, compared to the negative control, did not significantly vary in OD at 0.5% (p>0.05) but significant variation was found as the concentration increased (p<0.05). Additionally, for Tea tree oil and Mastic oil, the growth inhibition rate showed no significant variation according to concentration (p>0.05), whereas for Blending oil, the growth inhibition rate for S. mutans showed a significant difference at 1.0% (p<0.05) and at higher concentrations. Conclusion: Blending oil containing a Tea tree oil and Mastic oil demonstrated a significant growth inhibition effect on S. mutans from the concentration of 1.0%, which suggested its potential use as an effective antibacterial agent for dental caries.

• 식물분류학회지
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• 제49권4호
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• pp.324-333
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• 2019

Neutral genetic diversity found in plant species usually leaves an indelible footprint of historical events. Korea's main mountain range (referred to as the Baekdudaegan [BDDG]), is known to have served as a glacial refugium primarily for the boreal and temperate flora of northeastern Asia. In addition, life-history traits (life forms, geographic range, and breeding systems) influence the within- and among-population genetic diversity of seed plant species. For example, selfing species harbor significantly less within-population genetic variation than that of predominantly outcrossers. A previous study of two Liparis species (L. makinoana and L. kumokiri) emphasizes the role of the abovementioned factors shaping the levels of genetic diversity. Liparis makinoana, mainly occurring on the BDDG and self-incompatible, harbors high levels of within-population genetic diversity (expected heterozygosity, H_eP = 0.319), whereas there is no allozyme variation (H_eP = 0.000) in L. kumokiri, which is self-compatible and mainly occurs in lowland hilly areas. To determine if this trend is also found in other congeners, we sampled five populations of L. krameri from the southern part of the Korean Peninsula and investigated the allozyme-based genetic diversity at 15 putative loci. The somewhat intermediate levels of within-population genetic variation (H_eP = 0.145) found in L. krameri are most likely due to its occurrence in mountainous areas that, despite being outside of the main ridge of the BDDG, still served as refugia, and a self-incompatible breeding system. Management strategies are suggested for L. krameri and L. makinoana based on the levels and distribution of genetic diversity and inbreeding.

• 한국토양비료학회지
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• 제45권6호
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• pp.897-899
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• 2012

본 연구는 대구획으로 경지정리된 후 5년차인 1 ha의 논 및 4대강 주변의 리모델링 농경지 밭을 대상으로 하여 그에 따른 화학적 특성들을 조사하여 그 포장내의 공간변이를 파악하고 각 성분들간의 상호관련성을 비교하고자 수행되었다. 5년차인 1 ha의 논에서 5 m 간격으로 총 $20{\times}20=400$점의 시료를 채취하여 분석에 이용하였으며 매립적토형 인위토양은 10 m 간격으로 $6{\times}9=54$점의 시료를 채취하였다. 화학성분 중 pH, 유효인산, 유기물함량 등을 분석하여 그 결과를 해석하였다. pH는 구미지역에서 7.1로 높게 나타났으며, 유효인산 및 유기물함량의 경우 모두 변이계수가 높았으며 이는 한 포장 내에서도 상당히 불균일하다고 볼 수 있었다. 왜도(skewness)와 첨도(kurtosis) 등은 그 절대값으로 볼 때 거의 정규분포에 가까운 형태로 보이고 있다. 안성의 논에서는 유효인산 (72.8) ${\fallingdotseq}$ pH(73.8) < 유기물(159.3)의 순, 구미의 밭에서는 유기물(6.5) < 유효인산(33.5) < pH(46.6)의 순으로 Range값이 높아졌다. 이는 상대적으로 5년된 토양에서보다 0년차의 토양에서 시료채취를 많이 해야 한다는 의미로 해석할 수 있었다.

• Journal of Ginseng Research
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• 제25권1호
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• pp.53-58
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• 2001

적변삼과 건전삼 그리고 이들의 근권토양으로부터 분리한 토양세균과 적변현상과의 관계를 구명하고자 pH 변화와 철 이온에 따른 토양세균의 생장 특성을 조사한 결과, 분리된 모든 토양세균은 pH 3.0에서는 생장하지 못하였다. 그러나 RCG와 RCS는 2 mM Fe$^{3+}$ 가 포함된 배지에서는 pH 3.0에서도 생장하였다. 특히, RCG의 경우는 철이 포함된 배지에서는 철이 없는 배지보다 생장이 2배 정도 높았다. 적변삼의 뿌리에서 분리된 토양세균(RCG)은 pH 5.0에서 pH 9.0사이에서는 생장에 큰 차이가 없었으나, 건전삼의 근권토양에서 분리된 토양세균(HES)은 다른 곳에서 분리된 세균에 비해 생장이 낮았다. 적변삼의 근권토양에서 분리한 토양세균(RCS)과 표토에서 분리한 토양세균(SUS)의 생장은 pH5.0에서 pH 7.0과 pH 9.0에 비해 다소 낮았다. 분리된 모든 토양세균의 cellulase효소활성은 철이온이 포함된 배지에서 철이온이 없는 배지보다 2배 이상 높게 나타났다. 세포 외효소 활성은 세포 내 효소 활성보다 약 10 이상 높았고, pH5.0에서 RCS의 효소활성은 pH 7.0 보다 2배 이상 높았다. 특히, 2 mM Fe$^{3+}$ 가 포함된 배지에서 RCS의 세포 내 효소활성은 철이온이 없는 배지보다 6~7배 높았고 세포 외 효소의 경우에는 11~12배가 증가되었다. 이러한 결과는 인삼의 적변현상과 관련된 토양세균은 철이온의 산화환원과cellulase분비에 의한 세포벽 분해 그리고 인삼 표피세포에 철이온과 강력한 리간드를 형성하는 것으로 판단된다.

• 한국동물학회지
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• 제34권4호
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• pp.557-570
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• 1991

일차 담수어류의 잉어과(Cyprinidae)에 속하는 Zacco속 어류 4종과 이와 근인관계가 가까운 Candid유속 어류 1종에 대한 유전적 변이를 조사하기 위하여, 한국, 일본 및 대만에서 채집된 개체를 대상으로 전기영동을 실시하여 24-28개의 유전자를 검출 분석하였다. 각 종의 유전적 변이 정도를 조사한 결과 Zaccoplotypus는 전 집단 평균 h: 1.22, p= 17. 52%, HD = 0.053 및 HD= 0.056으로서 조사한 전종중에서일근 변이가 가장 높았다. Z. pachycepholus의 유전적 변이 정도는 A= 1.17, p= 14.8%, HD: 0.026, HG=0.027로서 Z. ploDpus보다 변이 정도가 낮았고, Z. temminck와 Candidia barbata는 각기 A= 1.07, p =7.95%, HD = 0.011, HG = 0.013 및 A= 1.05, P= 3.7%, Hd: 0.013, HG = 0.011로서 변이 정도가 가장 낮았다. Z. Platypus의 경우 한국집단이 변이가 가장 높았으며 대만집단이 가장 낮았다. Zacco속과 Candid지속 어류의 평균 유전적 변이정도는 타어류의 유전적 변이보다 낮았으며 이는 한국산 담수어류중 잉어과 어류의 일반적인 특징이라 사료된다.

• 한국대기환경학회지
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• 제13권5호
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• pp.333-343
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• 1997

The cyclone/annular denuder system/filter pack sampling system (ADS) was used to collect the acidic air pollutants in Chongju city. The data set was collected on fifty -eight different days with 24 hour sampling period from October 27, 1995 through August 25, 1996. The chemical species measured were HN $O_3$, HN $O_2$, S $O_2$ and N $H_3$ in the gas phase, and PM2.5( $d_{p}$ ＜2.5 ${\mu}{\textrm}{m}$), S $O_4$$^{2-}$, N $O_3$$^{[-10]}$ and N $H_4$$^{+}$ in the Particulate Phase. Mean concentrations measured for this study were: 0.45 $\mu\textrm{g}$/㎥ for HN $O_3$, 3.39 $\mu\textrm{g}$/㎥ for HN $O_2$, 26.4 $\mu\textrm{g}$/㎥ for S $O_2$, 3.83$\mu\textrm{g}$/㎥ for N $H_3$, 44.2 $\mu\textrm{g}$/㎥ for P $M_{2.5}$, 8.22 $\mu\textrm{g}$/㎥ for S $O_4$$^{2-}$, 3.63 $\mu\textrm{g}$/㎥ for N $O_3$$^{[-10]}$ , and 2.84 $\mu\textrm{g}$/㎥ for N $H_4$$^{- }$. HN $O_3$ and N $H_3$ were higher during the summer. However, HN $O_2$ and S $O_2$ were higher during the fall and winter. P $M_{2.5}$ , S $O_4$/ sup 2-/ and N $H_4$$^{+}$ were not showed seasonal variations, but N $O_3$$^{[-10]}$ was higher in the winter.ter.r.