• Journal of the Mineralogical Society of Korea
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• v.28 no.2
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• pp.95-108
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• 2015

Nano-sized iron colloids are formed as acid mine drainage is exposed to surface environments and is introduced into surrounding water bodies. These iron nanomaterials invoke aesthetic contamination as well as adverse effects on aqueous ecosystems. In order to control them, the characteristics of their behaviour should be understood first, but the cumulative research outputs up to now are much less than the expected. Using zero-valent iron (ZVI) and magnetite, this study aims to investigate the behaviour of iron nanomaterials according to the change in the composition and pH of background electrolyte and the concentration of natural organic matter (NOM). The size and surface zeta potential of iron nanomaterials were measured using dynamic light scattering. Characteristic behaviour, such as aggregation and dispersion was compared each other based on the DLVO (Derjaguin, Landau, Verwey, and Overbeek) theory. Whereas iron nanomaterials showed a strong tendency of aggregation at the pH near point of zero charge (PZC) due to electrostatic attraction between particles, their dispersions became dominant at the pH which was higher or lower than PZC. In addition, the behaviour of iron nanomaterials was likely to be more significantly influenced by cations than anions in the electrolyte solutions. Particularly, it was observed that divalent cation influenced more effectively than monovalent cation in electrostatic attraction and repulsion between particles. It was also confirmed that the NOM enhanced the dispersion nanomaterials with increasing the negative charge of nanomaterials by coating on their surface. Under identical conditions, ZVI aggregated more easily than magnetite, and which would be attributed to the lower stability and larger reactivity of ZVI.

• 베이커리
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• no.12 s.389
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• pp.58-59
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• 2000

• Proceedings of the Korean Vacuum Society Conference
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• 1996.02a
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• pp.78-78
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• 1996

• Tunnel and Underground Space
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• v.11 no.1
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• pp.64-71
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• 2001

The purpose of this study is to develop rail rockfall and landslide information system to manage spatial database using GIS. For this, a spatial database containing information such as railroad, map, topographic analysis, meteorological data, and rockfall has been constructed for 2.5 km or 5 km buffer zone from the Kyungchun, Youngdong, Jungang, Taebak and Jungsun Rairoad where risk of landslide occurrence potential is high. For management of the spatial database, railroad rockfall and landslide information system has been developed. The information system consists of view, table, chart, layout and project environment. The functions provided in the system are data conversion, editing, labeling, zoom in and out, map making, graphic editing, text DB management, charting, on-line help as well as input, retrieve and output of spatial database. The system was developed using ArcView script language Avenue, and consisted of pull-down menus and icons for easy use. The spatial database and the information system can be used to rockfall and landslide management and analysis near the railroad as basic data and tool.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.107-115
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• 2010

Removal and mineralization of dissolved uranium by bacteria in KURT (KAERI Underground Research Tunnel), Korea Atomic Energy Research Institute (KAERI) was investigated. Two different bacteria, IRB (iron-reducing bacteria) and SRB (sulfate-reducing bacteria) was used, and minerals formed by these bacteria were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Compared to uranyl ions, ferric ions were preferentially reduced by IRB, showing that there is no significant reduction and removal of uranium. However, uranium concentration considerably decreased by addition of Mn(II). Results show that a sulfide mineral such as mackinawite (FeS) is formed by SRB respiration through combination of Fe(II) and S without manganese sulfide formation. In the presence of Mn(II), however, uranium is removed effectively, suggesting that the sorption and incorporation of uranium could be affected by Mn(II) onto the sulide minerals.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.89-98
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• 2006

In this study, the iron and aluminium electrode was put in marine clay which was taken from south coast in Korea to increase the undrained shear strength by inducing the densification and cementation between clay particles and precipitation which was developed by electrode decomposition. For raising the cementation rate and reducing treatment time, high electric current( 2.5A) was applied in each electrode at semi-pilot scale soil box with marine clay. After the tests, the undrained shear strength was measured at designated points using cone penetration test device and sampling was conducted simultaneously in order to measure water content, pH and electric conductivity which would be the key for configuring the cementation effects indirectly. The iron electrode decomposition test results show that the water content adjacent to anode section decreased in 35% and increased in 13% at cathode section. The measured shear strength however, was increased considerably comparing to initial shear strength because of cementation effect between iron ions and soil particles. In case of aluminium electrode decomposition test, the distribution of measured shear strength and degree of improvement were more homogeneous than iron electrode decomposition test.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2190-2191
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• 2011

지능적인 감시 체계에 대한 필요성이 증대됨에 따라 많은 곳에서 지능화된 군중에 대한 모니터링을 요구하고 있다. 이는 비단 철도 분야에 있어 예외가 되지 않으며, 철도 서비스 구간 내에서의 필요성 또한 증대되고 있다. 철도 승강장 내에는 보안 감시에 사용되는 CCTV가 설치되어 있다. 이렇게 설치되어 있는 CCTV를 통해 철도 승강장의 영상 정보를 취득할 수 있으며 이것을 이용하여 군중 밀도 추정에 도움이 될 수 있다. 본 논문에서는 철도 승강장 내 군중 밀도를 군중의 움직임으로부터 발생되는 모션벡터를 검출하여 군중 밀도와 모션 벡터와의 상관관계에 대해 연구하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.583-584
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• 2020

철도의 고속화 및 수송력 증대로 인하여 철도 터널 및 주변 환경에서 발생하는 소음 및 진동 공해는 커다란 사회문제로 대두되고 있으며, 도시의 고층화로 인해 차단벽을 이용한 방음 기술의 한계와 철도 차량의 고속, 경량화 추세로 인한 소음. 진동, 위험상황으로 인한 문제는 지속적으로 발생하고 있다. 본 논문에서는 IoT 기술을 결합한 안정성을 보장하는 IT 기반기술의 위험상황 감지, 철도 소음진동 분석, 모니터링 및 제어할 수 있는 시스템을 설계하고, 철도 인근지역 주민 또는 유관기관에 소음진동 수치에 따른 적합한 대응 시스템을 제공할 수 있는 IoT 기술 제어 분석 및 안정화 서비스 시스템을 설계하였다.

• Journal of the East Asian Society of Dietary Life
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• v.9 no.4
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• pp.483-488
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• 1999

Effect on iron dissolution from iron sauce pans treated with the acetic, malic, citric acid and concentration(0. 0.02. 0.04. 0.1, 0.2, 0.4. 1.0, 2.0, 4.0%) of acidity, boiling times(0, 10. 20, 30, 40, 50, 60mins.) and temperature(5, 20, 40. 60, 80, 10$0^{\circ}C$) of acidity solution and in new and used sauce pans was investigated. As acetic acid concentration increases, iron content has increased. Iron dissolution concentration from iron sauce pan for boiling in malic acid increased more than that of acetic acid and citric acid. At above 6$0^{\circ}C$, as temperature increases, concentration of iron dissolved from iron sauce pan has increased. As boiling time increases, concentration of iron dissolved from iron sauce pan has also increased. Concentration of iron by repeated use has increased. And iron concentration has dissolved in large amount from new pan rather than used pan. Concentration of iron with distilled water by repeated use has increased only slightly. But 1% acetic acid has dissolved in large quantities.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.286-287
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• 2017

본 논문은 철도 차량 구동용 IPMSM 제어를 위한 속도 영역별 PWM 알고리즘을 제안한다. 철도 차량의 고속영역 제어는 인버터 전압 이용률을 최대화 할 수 있는 1-Pulse 제어 기법이 요구된다. 그러나, SPWM을 이용한 비동기 1-Pulse 제어는 출력 전류의 불균형을 초래한다. 따라서, 고속영역 제어를 위해 동기화 시킨 후 SPWM을 이용한 1-pluse 제어는 필수적이다. 본 논문에서는 비동기 모드로 제어를 시작하여 과변조 영역 이전에 지령 전압과 삼각파 주파수를 동기화 시킨 후 고속 영역운전을 하는 PWM 알고리즘을 제안한다. 본 논문에서 제안하는 알고리즘은 시뮬레이션으로 검증한다.