• 제목/요약/키워드: Stabilization conditions

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Stabilization of Heavy Metals using Ca-Citrate-Phosphate Solution: Effect of Soil Microorganisms (구연산/칼슘/인산염 용액을 이용한 토양 중금속 안정화: 토양 미생물이 미치는 영향)

  • Song, Ho-Cheol;Song, Doo-Sup;Cho, Dong-Wan;Park, Sung-Won;Choi, Sang-Hun;Jeon, Byong-Hun;Lee, Jang-Ho;Park, Joon-Hong
    • Journal of Korean Society of Environmental Engineers
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    • 제31권4호
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    • pp.241-248
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    • 2009
  • A farming area located near an abandoned copper mine in GuPo-ri, Choongchung province is heavily contaminated with heavy metals such as As, Pb, Cd, Cu and Zn of which concentrations are higher than the values typically detected in Korean soil environment. In this work, laboratory and field studies were conducted to examine feasibility of using Ca-citrate-phosphate solution in stabilizing heavy metals in the polluted soils. In laboratory batch experiments with field soil, the addition of Ca-citrate-phosphate solution resulted in decrease of aqueous phase concentration of phosphate and improvement of heavy metal stabilization, compared to those for sterilized soil samples. This indicates that microbial uptake of phosphate may have provided positive effects on availability of phosphate toward heavy metal stabilization. According to microbial community analysis for the field experiment, the use of Ca-citrate-phosphate led to increased diversity of microbial populations, and strict anaerobic microorganisms such as Anaerofilum and Treponema became the most dominant populations in the solution-amended field experiments. These findings suggest that, when Ca-citrate-phosphate is used for heavy metal stabilization in soils, microbial processes may have important roles in improving the stabilization of heavy metals by providing reducing conditions to the treatment locations or/and by making phosphate available to heavy metal stabilization.

Stabilization Mechanisms of Powdered and Bead Type Stabilizer Made of Mg-Fe Layered Double Hydroxide (LDH) for the Arsenic Contaminated Soil (Mg-Fe 이중층수산화물로 제조한 분말상과 입상 안정화제의 비소 오염토양 안정화 기작)

  • Kim, Seonhee;Kim, Kyeongtae;Oh, Yuna;Han, Yikyeong;Lee, Minhee
    • Journal of Soil and Groundwater Environment
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    • 제27권4호
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    • pp.49-62
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    • 2022
  • The magnesium and iron-based layered double hydroxide (Mg-Fe LDH) was synthesized by the co-precipitation process and the bead type LDH (BLDH, 5~6 mm in diameter) was manufactured by using the Mg-Fe LDH and the starch as a binder. To evaluate the feasibility of the BLDH as the As stabilizer in the soil, various experiments were performed and the As stabilization efficiency of the BLDH was compared to that of powdered type LDH (PLDH, <149 ㎛ in diameter). For the As sorption batch experiment, the As sorption efficiency of both of the PLDH and the BLDH showed higher than 99%. For the stabilization experiment with soil, the As extraction reducing efficiency of the PLDH was higher than 87%, and for the BLDH, it was higher than 80%, suggesting that the BLDH has similar the feasibility of As stabilization for the contaminated soil, compared to the PLDH. From the continuous column experiments, when more than 7% BLDH was added into the soil, the As stabilization efficiency of the column maintained at over 91% for 7 pore volume flushing (simulating about 21 months of rainfall) and slowly decreased down to 64% after that time (to 36 months) under the non-equilibrium conditions. Results suggested that more than 7% of BLDH added in As-contaminated soil could be enough to stabilize As in soil for a long time. The main As fixation mechanisms on the LDH were also identified through the X-ray fluorescence (XRF), the X-ray diffraction (XRD), and the Fourier transform infrared (FT-IR) analyses. Results showed that the LDH has enough of an external surface adsorption capacity and an anion exchange capability at the interlayer spaces. Results of SEM/EDS and BET analyses also supported that the Mg-Fe LDH used in this study has sufficient porous structures and outer surfaces to fix the As. The reduction of carbonate (CO32-) and sulfate (SO42-) anions in the LDH after the reaction between As and the LDH was observed through the FT-IR, the XRF, and the XRD analyses, suggesting that the exchange of some of these anions with the arsenate (H2AsO4- or HAsO42-) occurs at the LDH interlayers during the stabilization process in soil.

Applications of Acid/Base Modified Activated Carbon for Stabilization of Sediment Contaminated with Organic Compounds (산/염기 개질활성탄을 이용한 유기오염물질 오염 퇴적토 안정화를 위한 적용성 연구)

  • Seunghyun Kang;Jaewoo Park
    • Journal of the Korean GEO-environmental Society
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    • 제25권5호
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    • pp.5-13
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    • 2024
  • This paper investigates the stabilization feasibility of contaminated sediment contaminated with benzyl butyl phthalate (BBP) using acid/base-modified activated carbon. The efficiency of stabilizers was evaluated by analyzing the impact of the activated carbon on the decomposition and adsorption of the contaminant, along with the biological effects on earthworms. Additionally, the contaminant migration was monitored with the BBP concentration in pore water using low-density polyethylene. The research results indicated that the accumulated concentration of BBP was approximately 2% lower in the experimental group applying a 5% mixture ratio of modified activated carbon compared to the group applying a 10% mixture ratio. The leaching into water was reduced by over 18% in all experimental conditions after 7-day exposure period. Over 25% reduction was observed after 28-day exposure. The pore water concentrations were measured. After 7 days of exposure, the mechanically mixed experimental group exhibited a higher pore water stabilization rate compared to the biologically mixed group. Within the mechanically mixed group, the experimental group with 10% mixture of modified activated carbon showed a 1% higher stabilization rate than the group with 5% mixture. After 28 days of exposure, the biologically mixed experimental group demonstrated a higher pore water stabilization rate compared to the mechanically mixed group. Moreover, within the biologically mixed group, the experimental group with 10% mixture of modified activated carbon showed approximately 0.1% higher stabilization rate than the group with 5% mixture.

LMI-based Design of PI-type H∞ Controller for Poly topic Models (폴리토픽 모델을 위한 PI 형 H∞ 제어기의 LMI 기반 설계)

  • Choi, Han-Ho
    • Journal of Institute of Control, Robotics and Systems
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    • 제15권3호
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    • pp.255-257
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    • 2009
  • The robust stabilization problem of a multivariable uncertain system with a polytopic model is considered. A PI-type $H_{\infty}$ controller with a low pass filter is used for robust stabilization and noise rejection. The problem is reduced to an LMI optimization problem. A sufficient condition for the existence of the PI controller is derived in terms of LMIs. The PI gain matrices are parameterized by using the solution matrices to the existence conditions. Finally, a numerical design example is given.

A Study on the Effect of AC Electric Field on the Liftoff Characteristics of Turbulent Propane Jets. (교류전기장이 프로판 난류제트 화염의 부상특성에 미치는 영향)

  • Park, Chul-Soo;Lee, Sang-Min;Cha, Min-Suk;Chung, Suk-Ho
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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    • pp.83-88
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    • 2004
  • High voltage AC electric field has been applied to turbulent propane jets to investigate the effect of electric field on liftoff characteristics. Liftoff velocity and liftoff height have been measured by varying the applied voltage and frequency. Liftoff velocities were delayed and liftoff heights were reduced by applying AC, not by DC. The electric effect became disappeared with further increasing jet velocities, which shows that the effect can be explained by the balance between inertia force and electric force. The flame stabilization effect was intensified as either applied voltage or frequency increased. Plasma streamers were generated between the flame and the jet under high voltage conditions. Liftoff velocity in the absence of plasma can be well correlated by the function of voltage and frequency.

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Analog Controller for Battery to Stabilize DC-bus Voltage of DC-AC Microgrid

  • Dam, Duy-Hung;Lee, Hong-Hee
    • Proceedings of the KIPE Conference
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    • 전력전자학회 2014년도 추계학술대회 논문집
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    • pp.66-67
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    • 2014
  • Stabilization of the DC bus voltage is an important task in DC-AC microgrid system with renewable energy source such as solar system. A battery energy storage system (BESS) has become a general solution to stabilize the DC-bus voltage in DC-AC microgrid. This paper develops the analog BESS controller which requires neither computation nor dc-bus voltage measurement, so that the system can be implemented simply and easily. Even though others methods can stabilize and control the DC-bus voltage, it has complicated structure in control and low adaptive capability. The proposed topology is simple but is able to compensate the solar source variation and stabilize the DC-bus voltage under any loads and distributed generation (DG) conditions. In addition, the design of analog controller is presented to obtain a robust system. In order to verify the effectiveness of the proposed control strategy, simulation is carried out by using PSIM software.

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Intelligent Digital Control of Heating, Ventilating, and Air Conditioning System for Smart Space (스마트 스페이스를 위한 난방, 환기 및 공기조화 시스템의 지능형 디지털 제어)

  • Kim, Do-Wan;Park, Jin-Bae;Joo, Young-Hoon
    • Journal of Institute of Control, Robotics and Systems
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    • 제13권4호
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    • pp.365-370
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    • 2007
  • This paper studies an automation problem of a heating, a ventilating, and an air conditioning (HVAC) for the development of smart space. The HVAC system is described by the fuzzy system for the stability analysis and the controller design. The linear matrix inequalities (LMIs) conditions are derived for the stabilization problem of the closed-loop system under the analog control. Also, it is required to digitally redesign the pre-designed the analog HVAC control system in order to accomplish the remote control via web. It is shown the this digital redesign problem can be converted to the convex optimization problem with the LMI constraints. An example is provided to show the effectiveness of the proposed method.

Performance Improvement of the Tank Gun-Pointing System Stabilized Drive (전차포 표적지향 시스템의 안정화ㆍ구동성능 향상연구)

  • 이대옥;김학성;안태영
    • Journal of the Korea Institute of Military Science and Technology
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    • 제1권1호
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    • pp.65-81
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    • 1998
  • Objective technology development has been carried out aiming performance improvement of the stabilized gun-pointing system for Type-4 tank. The full nonlinear simulation programs with gun bending modes and nonlinearities were developed to estimate, analyze and design the driving and stabilization system, and validated through the comparisons between simulations and test results of the existing Type-1 tank. The prototype is designed, fabricated, tested and evaluated on the test range as well as in the laboratory and followed by development and operational tests. The performance test results on stationary and on-the-move conditions are turned out to be superior to those of the advanced tanks developed in foreign countries.

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Networked Nonlinear Control Systems with Time-Delay via T-S Fuzzy Approach (시간 지연을 포함하는 비선형 네트워크 시스템의 퍼지 제어)

  • Song, Min-Kook;Park, Jin-Bae;Joo, Young-Hoon;Kim, Jong-Sun
    • Proceedings of the IEEK Conference
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    • 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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    • pp.390-392
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    • 2009
  • This paper is concerned with the stabilization problem of nonlinear networked control systems with time-delay via Takagi-Sugeno(T-S) fuzzy control approach. The T-S fuzzy models are employed to represent nonlinear systems with Markovian jump parameters and time-delay. The purpose of this paper is to design a fuzzy controller such that the closed-loop Markovian jump fuzzy system is stochastically stable. Based on a stocastic Lyapunov function, stabilization sufficient conditions using a mode-independent fuzzy controller are derived for the Markovian jump fuzzy system in terms of Linear Matrix Inequalities(LMIs). Finally, a simulation example is presented to illustrate the effectiveness of the proposed method.

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Networked Nonlinear Control Systems with Time-Delay via T-S Fuzzy Approach (시간 지연을 포함하는 비선형 네트워크 시스템의 퍼지 제어)

  • Song, Min-Kook;Park, Jin-Bae;Kim, Jin-Kyu;Joo, Young-Hoon
    • Proceedings of the IEEK Conference
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    • 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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    • pp.329-331
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    • 2009
  • This paper is concerned with the stabilization problem of nonlinear networked control systems with time-delay via Takagi-Sugeno(T-S) fuzzy control approach. The T-S fuzzy models are employed to represent nonlinear systems with Markovian jump parameters and time-delay. The purpose of this paper is to design a fuzzy controller such that the closed-loop Markovian jump fuzzy system is stochastically stable. Based on a stocastic Lyapunov function, stabilization sufficient conditions using a mode-independent fuzzy controller are derived for the Markovian jump fuzzy system in terms of Linear Matrix Inequalities(LMIs). Finally, a simulation example is presented to illustrate the effectiveness of the proposed method.

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