• 한국토양환경학회지
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• 제3권1호
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• pp.11-20
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• 1998

안전한 먹는 물 생산을 위해 강둑여과수를 원수로 취수할 경우 여과수 수질오염의 원인이 되는 무기질소성분의 거동에 대해 연구하였다. 강둑여과지 주변 토양의 특성은 우리나라 평균 농경지 특성과 유사하였으나 표층의 평균 pH는 약 4.3으로 약산성을 나타내었다. 질소 농도는 토양 깊이별, 지역별로 다양한 함량의 $NH_3$-N과 $NO_3$-N가 관찰되었으나 $NO_2$-N은 거의 검출되지 않았다. 또한 토양 깊이에 따라 대체적으로 $NH_3$-N의 농도는 감소하고 $NO_3$-N의 농도는 증가하였다. 토양의 생균수와 질화균수는 각각 6.73~10.7$\times$$10^{6}$과 0.44~5.21$\times$$10^{4}$으로 조사되었고 상관관계는 $R^2$=0.992였다. 회분식으로 조사된 토양의 질산화 능력은 대체로 낮게 나타났으며 질산화균과 질산화능력의 상관관계는 높게 조사되었다. 표층과 심층토에 암모니아성 질소를 첨가한 후 호흡량 측정기로 소모되는 산소량을 측정한 결과 표층이 심층에 비해 짧은 지체기 후 많은 양의 산소소모가 관찰되었다.

• International Journal of Automotive Technology
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• 제8권3호
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• pp.343-349
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• 2007

One of the useful technologies for light-weightening of components required in the automobile and machine industry is to use high strength materials. To improve material properties, the carbonizing treatment, nitrifying treatment, and shot-peening method are representatively applied. However, the shot-peening method is generally used to remove surface defect on steel and to improve the fatigue strength of the surface. Benefits of shot-peening are increasing resistance against fatigue, stress corrosion cracking, fretting, galling, erosion and closing of pores. In this paper, the effect of shot-peening on the corrosion of SUP-9 steel immersed in a 3.5% NaCl solution and corrosion characteristics from heat treatment during the shot peening process has been investigated. The immersion test was performed on four kinds of specimens. Corrosion potential, the polarization curve, residual stress etc. Were analyzed from the experimental results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.325-330
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• 2004

Recently, the request for the high strength of material is more and more increased in the area of industrial environment and machinery. To accomplish the high strength of materials, carbonizing treatment, nitrifying treatment, shot-peening method are representatively applied, however, shot-peening method is generally used among the surface processes. Shot peening is a cold working process used to impact Compressive residual stressed in the exposed surface layers. Benefits due to shot peening are increase in resistance to fatigue, stress corrosion cracking, fretting, galling, erosion and closing of pores. In this study, the influence of shot peening on the corrosion was investigated on spring steel immersed in 3.5% NaCl. The immersion test as performed on the two kinds of specimens. Corrsion potential, polarization curve, residual stress and etc, were investigated from experiment results. From test result the effect of shot peening on the corrosion was evaluated. The important results of the experimental study on the effects of shot peened on the environment corrosion of spring steels are as follows; In case of corrosion potential, shot peened specimen shows more activated negative direction as compared with parent mental. Surface of specimen, which is treated with the shot peened is placed as more activated state against inner base metal. It can cause t도 anti-corrosion effect on the base metal.

• 대한기계학회논문집A
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• 제29권7호
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• pp.930-937
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• 2005

One of the useful technology for light-weightening of components required in the automobile and machine industry is to use of high strength materials. To improve material properties, carbonizing treatment, nitrifying treatment, and shot-peening method are representatively applied, However, the shot-peening method is generally used to remove the surface defect of steel and to improve the fatigue strength on surface. Benefits by shot peening are to make increase resistance against fatigue, stress corrosion cracking, fretting, galling, erosion and closing of pores. In this paper, investigated the effect of shot peening on the corrosion of SUP-9 steel immersed in $3.5\%$ NaCl solution and corrosion characteristics by the heat treatment during shot peening process. The immersion test was performed on the four kinds of specimens. Corrosion potential, polarization curve, residual stress and etc. were investigated from the experimental results.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.843-853
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• 2014

In the context of artificial groundwater recharge, a reactive soil column at pilot-scale (4.5 m depth and 3 m in diameter) fed by treated wastewater was designed to evaluate soil filtration ability. Here, as a part of this project, the impact of treated wastewater filtration on soil bacterial communities and the soil's biological ability for wastewater treatment as well as the relevance of the use of multi-bioindicators were studied as a function of depth and time. Biomass; bacterial 16S rRNA gene diversity fingerprints; potential nitrifying, denitrifying, and sulfate-reducing activities; and functional gene (amo, nir, nar, and dsr) detection were analyzed to highlight the real and potential microbial activity and diversity within the soil column. These bioindicators show that topsoil (0 to 20 cm depth) was the more active and the more impacted by treated wastewater filtration. Nitrification was the main activity in the pilot. No sulfate-reducing activity or dsr genes were detected during the first 6 months of wastewater application. Denitrification was also absent, but genes of denitrifying bacteria were detected, suggesting that the denitrifying process may occur rapidly if adequate chemical conditions are favored within the soil column. Results also underline that a dry period (20 days without any wastewater supply) significantly impacted soil bacterial diversity, leading to a decrease of enzyme activities and biomass. Finally, our work shows that treated wastewater filtration leads to a modification of the bacterial genetic and functional structures in topsoil.

• 한국해양학회지:바다
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• 제4권1호
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• pp.33-39
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• 1999

부영양화된 한강기수역에서의 용존산소 및 $NH_4{^+}$ 제거에 있어 조석의 영향 및 질산화의 중요성을 이해하고자 1995년 7월에 강화도 남단에서 만조, 중조 및 소조 시에 해수시료를 채취하였다. 수온과 DO를 제외한 하계 한강기수역의 생물, 화학적 환경을 결정짓는 요인들이 담수의 유입과 수역 내의 심한 조석 변화에 의해 조절되는 것으로 나타났다. 조석상태에 따른 용존산소 및 $NH_4{^+}$ 의 제거율은 만조 시 각각 2.76 ${\mu}M\;O_2\;d^{-1}$ 및 1.76 ${\mu}M\;N\;d^{-1}$이며, 간조 시 각각 5.66 ${\mu}M\;O_2\;d^{-1}$ 및 3.36 ${\mu}M\;N\;d^{-1}$로 최대로 나타나 간조 시 담수와 함께 유입되는 다량의 각종 유기물 및 무기영양염에 대한 미생물의 분해 및 흡수가 활발히 진행되고 있음을 알 수 있다. $NH_4{^+}$-질산화는 간조 시 총 DO 소모량의 약 24%를 차지하며 $NH_4{^+}$-질산화에 의한 $NH_4{^+}$의 회전율도 0.18 $d^{-1}$로 만조 때에 비해 각각 3.7배 및 3배 높게 나타나, 담수성 $NH_4{^+}$-질산화 박테리아가 간조 시 한강기수역으로 유입되면서 DO 및 $NH_4{^+}$의 소모에 중요한 역할을 담당하고 있는 것으로 사료된다. 만조 시 $NH_4{^+}$ 감소율 및 $NH_4{^+}$-질산화가 낮은 것은 염분증가에 따른 담수성 $NH_4{^+}$-질산화 박테리아의 활성이 위축되어 나타난 결과로 보이며, 이상의 결과들은 한강기수역에서 $NH_4{^+}$의 효율적인 생물학적 제거를 위해서는 $NH_4{^+}$를 포함하는 각종 오 폐수가 기수역으로 유입되기 이전에 처리됨이 바람직함을 의미한다. 향후 한강기수역과 같은 대규모 담수의 유입이 일어나는 부영양화된 기수역에서 질소계 원소의 순환을 보다 잘 이해하기 위해서는 $NH_4{^+}$ 및 $N0_2{^-}$를 유일한 화학에너지원으로 이용하는 자가영양 질산화 박테리아에 대한 생태적 연구가 병행되어야 한다.