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      • KCI등재

        Solar Photovoltaic Interfaced Quasi Impedance Source Network Based Static Compensator for Voltage and Frequency Control in the Wind Energy System

        Ramachandran S.,Ramasamy M. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3

        In this paper, the purpose of improving the power quality of the standalone wind conversion system (WECS) is to utilize a quasi-impedance (qZ) static compensator (STATCOM) integrated solar photovoltaic (SPV) source network. The standalone WECS has utilized the fl ywheel energy storage system (FESS) and the self-excited induction generator (SEIG). The SPV power generation network integrates with the STATCOM DC-Link to compensate for the voltage and frequency fl uctuations over a longer time. The SEIG terminal voltage and STATCOM DC-link voltage are regulated using an enhanced secondorder generalized integrator (ESOGI) with a fuzzy logic controller (FLC). The coordination logic is proposed in order to handle the various scenarios and make the device energy effi cient. The unit is built for optimal usage of the electrical energy generated from renewable sources by utilizing physical energy storage systems such as fl ywheel and battery. In both batteries and fl ywheels, excess power from the SPV and wind turbines is collected. To verify the performance of the SPV supported STATCOM, the simulation and experimental studies are performed under specifi c load conditions. This paper describes an optimal way to produce and utilize green power with better energy effi ciency. With various current conditions, the typical level of harmonic distortion of the source current is about 1.4% lower than that specifi ed by IEEE Std. 519–2014 for the tolerable 5% level.

      • KCI등재

        Comparative Evaluation of the Abrasive Slurry Wear Behavior of Alloy Surfaces Produced by a Plasma Transferred Arc Hardfacing Process

        C. S. Ramachandran,V. Balasubramanian,R. Varahamoorthy 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.2

        Abrasive slurry wear is generally defined as a mechanical interaction in which the material becomes lost in a surface that is in contact with moving particles, such as laden liquid. Slurry wear abrasion occurs in extruders, slurry pumps, and pipes that carry the slurry of minerals and ores in mineral processing industries. The life of the components used under slurry abrasion conditions is governed by the process parameters,the properties of the abrasive particles in the slurry, and the material properties. This paper analyses in detail the effects of operating variables, such as abrasive particle size, slurry concentration, speed of rotation, and slurry bath temperature, on the abrasive slurry wear behavior of a iron based alloy (stainless steel), cobalt based alloy (stellite), and nickel based alloy (colmonoy) surfaces produced by a Plasma Transferred Arc (PTA) hardfacing process. Of the four variables considered in this investigation, it was found that the slurry concentration had a predominant effect on the wear rate of hardfaced surfaces compared to the other variables. Microstructural analyses of the worned surfaces were carried out using SEM. Both the experimental and mathematical investigations showed that the wear resistance of an iron based alloy was 4 times better than the base metal. Similarly, the cobalt based alloy exhibited a 3 times higher wear resistance while the nickel based alloy showed a 2 times higher wear resistance compared to the base metal (carbon steel).

      • KCI등재

        Soil Resource Inventory and Mapping using Geospatial Technique

        Jayakumar S.,Ramachandran A.,Lee Jung Bin,Heo Joon 대한공간정보학회 2009 대한공간정보학회지 Vol.17 No.3

        지구상에서 가장 중요한 자원 중 하나인 토양은 지형조건에 따라 서로 다른 다양한 형태를 가지고 있기 때문에 최적화되고 지속 가능한 토양 자원의 활용을 위해서는 정확하고 포괄적인 정보가 필요하게 된다. 그러나 연구대상지역인 인도 Tamil Nadu지역의 경우 지형적인 영향으로 토양에 대한 정보가 많이 누락되어 있었다. 따라서 본 연구에서는Tamil Nadu 지역 Eastern Ghat의 Kolli Hill에 대한 지형 측량과 원격탐측을 통한 토양조사와 지도제작이 이루어졌으며 토양 샘플의 물리화학적 특성은 미국 농무부 (USDA) 기준에 따라 분석이 이루어졌다. 연구 결과로 토양을 5개의 대분류와 10개의 부분류로 구분할 수 있었으며 토양의 분포 특성을 보면 Entisol, Inseptisol 그리고 Alfisol의 세 계층 중 Entisol의 경우 전체 지역에 대하여 75%의 분포를 보였으며 5개의 대분류에 대해 Ustorthent가 73% 로서 대부분 지역에 나타나고 있다. 또한 Lithic Ustorthents(40%), Typic Ustorthents(26%)의 분포를 나타내었다. 앞으로도 대상지역에 대한 토양자원에 대한 지속적인 연구가 요구되며 이를 통하여 토양에 대한 많은 정보를 활용할 수 있을 것이다. Soil is one of the Earth's most important resources. There are many differences among the soils of plains-like and hilly terrains, and therefore, accurate and comprehensive information on soil is essential for optimum and sustainable soil utilization. However, information on the soil of the hilly terrains of the Eastern Ghats of Tamil Nadu, India, is limited or absent. In the present study, Kolli hill, one among the hills of the Eastern Ghats, was soil-inventoried and -mapped using a ground survey and remote sensing. Soil samples were collected and their physico-chemical properties analyzed according to the United States Department of Agriculture (USDA) standards. The soils were classified up to the family level. As a result of this study, 30 soil series belonging to ten sub-groups of five great groups and three sub-orders and orders each, were identified (classified to the family level) and mapped. Entisols, Inseptisols and Alfisols were the three orders, among which Entisols was the major one, occupying 75% of the area. Among the five great groups, Ustortbents occupied majority of the area (73%). Lithic Ustortbents and Typic Ustortbents were the two major sub-groups, occupying 40% and 26% of the total area, respectively. The present soil resource mapping of the Eastern Ghats of Tamil Nadu is a pioneer study, which yielded valuable information on the soil in this region.

      • KCI등재

        Letter : Site Suitability Assessment for Joint Forest Management (JFM)-a Geospatial Approach

        S. Jayakumar,A. Ramachandran,G. Bhaskaran,Joon Heo,Woo Sun Kim 大韓遠隔探査學會 2007 大韓遠隔探査學會誌 Vol.23 No.5

        Joint Forest Management (JFM) is a concept of developing partnerships between fringe forest user groups and the Forest Department (FD) on the basis of mutual trust and jointly defined roles and responsibilities with regard to forest protection and development. In India, JFM was started during 1992 and it was implemented in many states. However success rate of JFM activity was not promising. Though there are many factors attributed to the failures, one of the main factors is the JFM site. This paper deals with the significant ground works to be done before planning for JFM using recent technologies such as remote sensing (RS) and Geographic Information System (GIS). Also it deals with the advantages of weighted overlay analysis in selecting suitable sites for JFM taking into consideration the various criteria. As a result of weighted overlay analysis, there were four types of suitability classes viz., less, moderate, highly and un-suitable. The moderately suitable class occupied maximum area (13209.64 ha) than less and highly suitable classes. If JFM is implemented on the suitability area, then the failure could be avoided in the future.

      • KCI등재

        Object-oriented Classification and QuickBird Multi-spectral Imagery in Forest Density Mapping

        S. Jayakumar,A. Ramachandran,Jung Bin Lee,Joon Heo 大韓遠隔探査學會 2007 大韓遠隔探査學會誌 Vol.23 No.3

        Forest cover density studies using high resolution satellite data and object oriented classification are limited in India. This article focuses on the potential use of QuickBird satellite data and object oriented classification in forest density mapping. In this study, the high-resolution satellite data was classified based on NDVI/pixel based and object oriented classification methods and results were compared. The QuickBird satellite data was found to be suitable in forest density mapping. Object oriented classification was superior than the NDVI/pixel based classification. The Object oriented classification method classified all the density classes of forest (dense, open, degraded and bare soil) with higher producer and user accuracies and with more kappa statistics value compared to pixel based method. The overall classification accuracy and Kappa statistics values of the object oriented classification were 83.33% and 0.77 respectively, which were higher than the pixel based classification (68%, 0.56 respectively). According to the Z statistics, the results of these two classifications were significantly different at 95% confidence level.

      • MnO<sub>2</sub> nanorods grown NGNF nanocomposites for the application of highly sensitive and selective electrochemical detection of hydrogen peroxide

        Ramachandran, K.,Zahoor, A.,Raj Kumar, T.,Nahm, K.S.,Balasubramani, A.,Gnana Kumar, G. Korean Society of Industrial and Engineering Chemi 2017 Journal of industrial and engineering chemistry Vol.46 No.-

        <P>The tetragonal alpha-phase structured manganese dioxide nanorods were densely grown over the nitrogen doped graphite nanofibers (NGNF/MnO2) via a facile and one-pot hydrothermal technique. The amperometric results depicted that NGNF/MnO2 composite exhibited a high sensitivity of 1096 mu A mM(-1) cm(-2) and a wide linear range from 0.1 to 11 mM with the lower detection limit of 1.25 mu M toward the non-enzymatic hydrogen peroxide (H2O2) detection, owing to the synergistic effects of NGNF and MnO2. In the prospect of excellent selectivity, real sample analysis and other striking advantages, the developed non-enzymatic sensors hold promising potential for the tight monitoring of H2O(2) in the food and clinical diagnosis fields. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.</P>

      • KCI등재

        Prediction of cutting force, tool wear and surface roughness of Al6061/SiC composite for end milling operations using RSM

        S. Jeyakumar,K. Marimuthu,T. Ramachandran 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.9

        The results of mathematical modeling and the experimental investigation on the machinability of aluminium (Al6061) silicon carbide particulate (SiCp) metal matrix composite (MMC) during end milling process is analyzed. The machining was difficult to cut the material because of its hardness and wear resistance due to its abrasive nature of reinforcement element. The influence of machining parameters such as spindle speed, feed rate, depth of cut and nose radius on the cutting force has been investigated. The influence of the length of machining on the tool wear and the machining parameters on the surface finish criteria have been determined through the response surface methodology (RSM) prediction model. The prediction model is also used to determine the combined effect of machining parameters on the cutting force, tool wear and surface roughness. The results of the model were compared with the experimental results and found to be good agreement with them. The results of prediction model help in the selection of process parameters to reduce the cutting force, tool wear and surface roughness, which ensures quality of milling processes.

      • KCI등재후보

        Forest Cover Change Detection Analysis in the Eastern Ghats of Tamil Nadu, India - a Remote Sensing and GIS Approach

        Jayakumar S.,Ramachandran A.,Bhaskaran G.,Lee Jung Bin 대한공간정보학회 2007 대한공간정보학회지 Vol.15 No.4

        대축척(1:50,000)지도의 산림 정보는 산림지역 보호에 중요한 자료로 이용된다. 그러나 대상지역인 인도 Tamil Nadu의 Eastern Ghats(EG) 지역에는 대축척 지도를 사용할 수 없기 때문에 위성 데이터를 이용한 산림의 변화 탐지를 적용하여 분석하였다. 대상지역의 1990년과 2003년의 산림의 변화에 대한 연구 결과 약 10가지의 산림 종류가 관측되었으며 가장 변화가 큰 지역은 상록수와 낙엽수지역에서 관측되었다. Information on forest type and cover density status of the present and past on large scale (1:50,000) is very much needed for conservation of any forest region. Such large-scale maps are not available for the Eastern Ghats (EG) of Tamil Nadu. This study deals with the preparation of forest type and cover density map of EG of Tamil Nadu during 2003 and the changes it has undergone between 1990 and 2003 using appropriate satellite data. About 10 forest types have been identified and mapped. Major changes have been observed in the forest types such as evergreen, and deciduous.

      • Estimation of carbon sequestration in natural forests

        라마찬드란(Ramachandran),자야쿠마(S. Jayakumar),허준(Heo Joon),김우선(Kim Woo Sun) 대한공간정보학회 2007 한국지형공간정보학회 학술대회 Vol.2007 No.6

        Estimation of carbon in the natural forest regions is a pre-requisite for carbon management. In the light of increasing carbon dioxide concentration in the atmosphere, the amount of carbon present in the plants and soils are very much needed to estimate the sequestered carbons stock of any region. Carbon stock estimation studies are limited in India, especially in the natural forest regions of Eastern ghats of Tamil Nadu. Remote sensing, Geographical Information System (GIS) and global positioning system (GPS) were used along with extensive field and laboratory works to estimate the carbon stock in the living biomass and soil. About five forest types were identified and mapped using satellite data. The total biomass carbon including above and below ground were 2.74 Tg and the total soil organic carbon was 3.48 Tg. This study has yielded significant information about the carbon stock in a natural forest region and it could be used for future comparative studies.

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