• 제목/요약/키워드: Neutral Current

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바이오매스로서의 억새에 대한 연구 동향 (Current status on Miscanthus for biomass)

  • 서상규;이정은;전서범;이병현;구본철;서세정;김선형
    • Journal of Plant Biotechnology
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    • 제36권4호
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    • pp.320-326
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    • 2009
  • The carbon dioxide concentration of the atmosphere is projected to increase by almost 50% over the first 50 years of this century. The major cause of this increase is continued combustion of fossil fuels. As a result, the significant changes in climate that have already occurred will be amplified, in particular a global temperature increase. Renewable energy production has a central role to play in abating net $CO_2$ emissions to a level that will arrest the development of global warming. Especially, biomass crops are becoming increasingly important as concerns grow about climate change and the need to replace carbon dioxideproducing fossil fuels with carbon-neutral renewable sources of energy. To succeed in this role, biomass crop has to grow rapidly and yield a reliable, regular harvest. A prime candidate is Miscanthus, or Asian elephant grass, a perennial species that produces over 3 metres of bamboo-like stems in a year. Miscanthus species are typically diploid or tetraploid. Hybrids between species with different ploidy levels result in the highly productive triploid hybrids, M. ${\times}$ giganteus. Here we will detail the Miscanthus characteristics desired of a biomass fuel crop.

통합환경관리제도 운영을 위한 최적가용기법 평가·선정기법 연구 (Evaluation and Selection Method of Best Available Techniques for Integrated Environmental Management System)

  • 박재홍
    • 한국물환경학회지
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    • 제33권3호
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    • pp.348-358
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    • 2017
  • The process of evaluating and selecting the best available techniques presents various characteristics for each country. In the case of EU, BAT is selected through TWG meeting after first screening, mass and energy balance, impact assessment and decision support process. Korea has proposed four principles to select BAT that can be carbon neutral for each environmental infrastructure in order to reduce greenhouse gas emissions. In order to evaluate and select the best available technique, it is necessary to differentiate the method according to whether it is a technique generally applied at the current workplace, whether it is a single technique or a combination technique, and whether it is a technology technique or management technique. In the case of a single technique, it should be evaluated whether it is a technique applied in the workplace, excessive cost, superior environmental technique over BAT, and secondary environmental pollution. In the case of multiple techniques, it is necessary to examine whether the emission standards are met and whether the pollutants can be treated at the same level as BAT. In the case of BAT candidates for management techniques, whether or not they contribute directly or indirectly to lowering the emission level of pollutants can be an important evaluation item. In the case of environmental techniques that are not generally applied in the workplace, it is recommended that the following 8 steps be carried out, including those prescribed by law. In the first stage, the list of performance evaluation factors is listed. In the second stage, the level of disposal of pollutants and the level of satisfaction with standards are listed. In the third stage, the environmental evaluation elements are listed. In the fourth stage, Is to list the economic evaluation elements, step 6 is to list the pollution and accident prevention evaluation factors, step 7 is the quantitative evaluation of the technical working group, and step 8 is BAT confirmation through deliberation of the central environmental policy committee.

농촌지역개발사업 추진과정의 갈등특성 연구 - 권역단위종합정비사업 참여 주체 인식조사를 중심으로 - (A study on the characteristics of the conflicts occurred in the rural area development business promotions - Focused on the awareness survey of the subjects participate in regional comprehensive development project -)

  • 신용규;조중현
    • 농촌계획
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    • 제24권3호
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    • pp.1-12
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    • 2018
  • This study aims to offer base line data for efficient conflicts control measures by first, analyzing the current situation of the regional comprehensive development project and second, identifying level, type and cause of the conflicts appeared during the development business promotion. For this purpose, theoretical side of this study establishes a basic frame by reviewing the existing researches in order to analyze the characteristics of the conflicts between the participation subjects in the development business, and the empirical side conducts survey and analysis on the awareness on these conflicts. As a result of the analysis, the survey revealed the followings. First, the respondents were aware of the overall promotions of the business quite positively, second, the conflicts were considered as a major obstacle against the development project promotion just as the other negative factors, third, majority of the responses on the seriousness of the conflicts were neutral which meant that the conflicts could be deepened by situations, fourth, most respondents had positive recognition on the needs of conflict control training and its effectiveness, and last but not least, most respondents of the survey revealed their intentions to take parts in trouble shooting from the conflicts. Based on the results above, we were able to extract several elements to consider preparing the countermeasures for the conflicts. First, specific plan should be arranged and institutionalized in order to control the conflicts between the residents at the initial stage of the development business or even before. Second, the specific plan must lower its threshold for easy participation of the residents in that region and make the residents main body of the conflict control. Third, enhanced conflict control education must be provided to the residents of the region where comprehensive development plan is in progress or being prepared.

Knowledge, attitudes and practices toward antimicrobial usage: a cross-sectional study of layer and pig farm owners/managers in Chiang Mai, Lamphun, and Chonburi provinces, Thailand, May 2014 to February 2016

  • Nuangmek, Aniroot;Rojanasthien, Suvichai;Patchanee, Prapas;Yano, Terdsak;Yamsakul, Panuwat;Chotinun, Suwit;Tadee, Pakpoom
    • 대한수의학회지
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    • 제58권1호
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    • pp.17-25
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    • 2018
  • This study aimed at determining the current knowledge, attitude, and practices (KAP) of layer and pig farmers to antimicrobial usage and its consequences. Description of such KAP could provide insights useful for promoting the rational use of antimicrobials in livestock. From May 2014 to February 2016, a survey involving 251 respondents in Chiang Mai, Lamphun, and Chonburi provinces, Thailand, was conducted by using a validated questionnaire. More than half (51.0%) of the respondents incorrectly believed that antimicrobial drug efficacy could not be reduced by using sub-recommended dosages, 61.2% had misconceptions about non-therapeutic antimicrobial use, and 66.9% inaccurately felt that antimicrobials were also effective for virus and fungi. Over half (50.6-55.2%) did not see the need to follow instructions or advice of veterinarians. Moreover, only 10.4% regularly relied on responses to drugs sensitivity tests when evaluating the effectiveness of antimicrobials. Overall, assessment of KAP regarding antimicrobial usage indicated that the majority of respondents had low levels of knowledge of antimicrobials, neutral rather than positive attitudes, and employed poor practices in the use of antimicrobials. The results indicate improvements in KAP could be helpful in developing more effective interventions by farmers, reduce antibiotic usage, and slow the growth of antimicrobial resistance.

Electrochemical Properties of Buckminsterfullerene ($C_{60}$) in Acetonitrile Containing Quarternary Ammonium Electrolytes

  • Kim, Il Kwang;Kim, Hyun Jin;Oh, Gi Su;Jeon, Il Chol;Ahn, Byoung Joon
    • 분석과학
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    • 제8권4호
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    • pp.675-682
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    • 1995
  • Thin films of buckminsterfullerene($C_{60}$) formed by solution drop casting on Pt foil electrode surfaces were studied by cyclic voltammetry(CV) in acetonitrile(MeCN) containing quaternary ammonium or alkali-metal salts as supporting electrolyte. The electrochemical behaviors of $C_{60}$ films are found to be strongly dependent on the nature of the supporting electrolytes, especially with tetrabutyl ammonium perchlorate (TBAP, $NBu_4ClO_4$), and tetrabutyl ammonium tetrafluoroborate ($TBABF_4$, $NBu_4BF_4$). Reasonably stable films are formed into which electrons can be injected. The interaction of $C_{60}$ film with the quaternary ammonium cation may produce the fulleride salts $(TBA^+)(C{_{60}}^-)$ and $(TBA^+)_2(C{_{60}}^{2-})$. The bulk electroreduction with a controlled potential to generate the soluble $C{_{60}}^{3-}$ anions(dark red-brown color) is followed by electrooxidative deposition to produce a neutral $C_{60}$ film on the surface. The peak currents($I_{pc}$ and $I_{pa}$) of these thin film were dramatically decreased with repetitive potential scanning. These results could be explained by the adsorption-desorption phenomena and ion pairing interaction of reduced species($C{_{60}}^-$, and $C{_{60}}^{2-}$) onto the electrode surface. The peak current changes and peak potential shifts of the thin $C_{60}$ film in cyclic voltammograms formed from solution were observed by varying scan rates.

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XML기반 PIB를 이용한 네트워크 관리구조 (A Network Management Architecture Using XML-based PIB)

  • 윤권섭;홍충선
    • 한국통신학회논문지
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    • 제28권5B호
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    • pp.414-426
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    • 2003
  • 정책기반 네트워크 관리 구조는 정책을 전송하기 위해 COPS(Common Open Policy Service)와 이의 모델인 COPS-PR (Policy Provisioning)을 사용한다. COPS-PR은 여러 네트워크 관리 영역에서 효율적으로 활용될 수 있는 매커니즘을 가지고 있다. COPS-PR은 정책을 저장하고 디바이스정보를 저장하기 위해 PIB(Policy Information Base)를 사용한다. PIB는 PRC(Provising Class)와 PRI(Provisions Instances)로 구성되어 있다. PIB는 정책을 통해 디바이스를 제어하기 위한 기능이 미리 구현되어 있다. PIB에 PRI를 추가시킴으로써 정책을 수행시킬 수 있다. 하지만 미리 구현되어 있는 기능에 한정되어 사용하기 때문에 새로운 기능에 대해선 정책을 적용할 수 없는 단점을 가지고 있다. 본 논문에서 제안하는 구조는 기존 PIB에 단점을 보완하기 위해 XML로 변환된 PIB를 사용한다. XML 기반 PIB는 동적으로 새로운 기능의 추가가 가능하며, 정책을 통해 이를 수행시킬 수 있는 구조이다. 또한 본 구조에서는 정책 기술 시에도 XML을 이용하였다. 정책 기술시 XML을 이용하면 서로 다른 정책기술 언어를 사용하는 이 기종의 관리 시스템간에 정책 교환 시 XSLT(eXtensible Stylesheet Language Transformation)을 이용하여 쉽게 변환될 수 있다. 본 논문에서는 동적 확장을 고려한 XML기반 네트워크 관리 구조를 제안하고, 이를 구현하여 기존 시스템과의 차별성을 평가하였다.

수계 내 조류 제거를 위한 전기응집 운전 특성 평가 (Evaluation of Operation Parameters for the Removal of Algae by Electro-Coagulation)

  • 정권;김도군;김석구;김원재;고석오
    • 한국물환경학회지
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    • 제31권2호
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    • pp.94-102
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    • 2015
  • Electro-coagulation experiments were conducted with aluminum (Al) or iron (Fe) electrode in order to determine the optimal electrode material and operation conditions for algae removal. Al electrode showed higher removal rate of algae than Fe electrode because Al flocs have positive surface charges which electrostatically attract algae species having negative surface charges. Removal rate of algae and total phosphorous (T-P) was increased as current density and electrode area increases. It was also found that initial pH with neutral range was optimum for T-P removal by electro-coagulation. Bench-scale continuous flow experiments consisted of electro-coagulation reactor, agitation tank and settling tank were conducted. In electro-coagulation reactor, a large fraction of Al flocs were distributed to scum layer, due to the gas bubbles generated by electrolysis reaction. In agitation tank, most of Al flocs were settled and the optimal mixing intensity was found to be 50 rpm to achieve good settleability. The removal rate of algae was about 90-95%. Additionally, the removal rate of the T-P and COD was observed to be $73.8{\pm}8.0%$ and $75.0{\pm}3.8%$, respectively. Meanwhile, the removal rate of total nitrogen (T-N) was relatively low at only 24%.

Use of hybrid materials in the trace determination of As(V) from aqueous solutions: An electrochemical study

  • Tiwari, Diwakar;Jamsheera, A.;Zirlianngura, Zirlianngura;Lee, Seung Mok
    • Environmental Engineering Research
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    • 제22권2호
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    • pp.186-192
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    • 2017
  • The carbon paste electrode (CPE) was modified with the pristine bentonite and hybrid material (HDTMA-modified bentonite). The modified-CPEs are then employed as working electrode in an electrochemical detection of As(V) from aqueous solutions using the cyclic voltammetric measurements. Cyclic voltammograms revealed that As(V) showed reversible behavior onto the working electrode. The hybrid material-modified carbon paste electrode showed significantly enhanced electrochemical signal which was then utilized in the low level detection of As(V). Moreover, the studies were conducted at neutral pH conditions. The electrochemical studies were conducted with scan rates (20 to 200 mV/s) to deduce the mechanism of redox processes involved at the electrode surface. The anodic current was linearly increased, increasing the concentration of As(V) from 5.0 to $35.0{\mu}g/g$ using the hybrid material-modified electrode. This provided fairly a good calibration line for As(V) detection. The presence of varied concentrations of As(III) in the determination of total arsenic was studied. The influence of several cations and anions viz., Cu(II), Mn(II), Zn(II), Pb(II), Cd(II), Fe(III), $Cl^-$, $NO_3{^-}$, $PO_4{^{3-}}$, EDTA and glycine in the detection of As(V) from aqueous solution was also studied. Further, in an attempt to simulate the real matrix analysis, the tap water sample was spiked with As(V) and subjected for As(V) detection using the modified-CPE.

Modeling and Direct Power Control Method of Vienna Rectifiers Using the Sliding Mode Control Approach

  • Ma, Hui;Xie, Yunxiang;Sun, Biaoguang;Mo, Lingjun
    • Journal of Power Electronics
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    • 제15권1호
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    • pp.190-201
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    • 2015
  • This paper uses the switching function approach to present a simple state model of the Vienna-type rectifier. The approach introduces the relationship between the DC-link neutral point voltage and the AC side phase currents. A novel direct power control (DPC) strategy, which is based on the sliding mode control (SMC) for Vienna I rectifiers, is developed using the proposed power model in the stationary ${\alpha}-{\beta}$ reference frames. The SMC-based DPC methodology directly regulates instantaneous active and reactive powers without transforming to a synchronous rotating coordinate reference frame or a tracking phase angle of grid voltage. Moreover, the required rectifier control voltages are directly calculated by utilizing the non-linear SMC scheme. Theoretically, active and reactive power flows are controlled without ripple or cross coupling. Furthermore, the fixed-switching frequency is obtained by employing the simplified space vector modulation (SVM). SVM solves the complicated designing problem of the AC harmonic filter. The simplified SVM is based on the simplification of the space vector diagram of a three-level converter into that of a two-level converter. The dwelling time calculation and switching sequence selection are easily implemented like those in the conventional two-level rectifier. Replacing the current control loops with power control loops simplifies the system design and enhances the transient performance. The simulation models in MATLAB/Simulink and the digital signal processor-controlled 1.5 kW Vienna-type rectifier are used to verify the fast responses and robustness of the proposed control scheme.

이미지 스케일에 따른 트랜드 중심의 실내디자인 표현어휘 연구 - 2008~09년도 국제박람회를 중심으로 - (A Study on the Interior Design representation-language from image scale of Trend - Focused on 2008~09 international Fair -)

  • 신동관;한영호
    • 한국실내디자인학회논문집
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    • 제19권1호
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    • pp.112-120
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    • 2010
  • Generally, Interior design understood as shapes, lines, spaces, tones, quality, and principal. And people research these with a study of formative approach. The six elements of above categories are basis of expansion for the various designs. In this study, the represented design language is extracted by the basic 6 stages and re-divided into classes. This study presented by the Kobayashi-scale image of the current trends in the assignment to examine the cultural, functional, sensory vocabulary, three elements were classified by the assignment about 2008~2009 international fair by trend and design direction for the image. If we look into the categorized format of the design, it reflects mixed culture with emotional approach and shows direction of design constantly. Especially, compared to the year 2008, the design of year 2009 has tendency as an emotional translator regarding the verbal expression. In other words, it becomes more concrete to express the design of emotions for human beings. In addition, design shows detail of its flow with outcomes of past leading trend which was re-created shape. On the other hand, undeveloped cultures such as folk, historical, and unique cultures attract design leaders as it is. This research would make good relationship between designers and customers regarding the newly started international trend of design. Hereby I research with the method to reclassify the image of vocabulary from the image scale extract. It remains as a task to resolve ambiguous, complex and neutral expression for better understanding and definite analysis method to the public.