• Title/Summary/Keyword: Electric Continuity

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Analysis on Application of Flywheel Energy Storage System for offshore plants with Dynamic Positioning System

  • Jeong, Hyun-Woo;Kim, Yoon-Sik;Kim, Chul-Ho;Choi, Sung-Hwan;Yoon, Kyoung-Kuk
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.7
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    • pp.935-941
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    • 2012
  • This paper describes a study of conventional electrical rig and simulated application of Flywheel Energy Storage system on the power system of the offshore plants with dynamic positioning system with the following aims: improve fuel consumption on engines, prevent blackout and mitigate voltage sags due to pulsed load and fault. Fuel consumption has been analyzed for the generators of the typical drilling rigs compared with the power plant with Flywheel Storage Unit which has an important aid in avoiding power interruption during DP (Dynamic Positioning) operation. The FES (Fly wheel Energy storage System) releases energy very quickly and efficiently to ensure continuity of the power supply to essential consumers such as auxiliary machinery and thrusters upon main power failure. It will run until the standby diesel generator can start and supply the electric power to the facilities to keep the vessel in correct position under DP operation. The proposed backup method to utilize the quick and large energy storage Flywheel system can be optimized in any power system design on offshore plant.

Assessment of velocity-acceleration feedback in optimal control of smart piezoelectric beams

  • Beheshti-Aval, S.B.;Lezgy-Nazargah, M.
    • Smart Structures and Systems
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    • v.6 no.8
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    • pp.921-938
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    • 2010
  • Most of studies on control of beams containing piezoelectric sensors and actuators have been based on linear quadratic regulator (LQR) with state feedback or output feedback law. The aim of this study is to develop velocity-acceleration feedback law in the optimal control of smart piezoelectric beams. A new controller which is an optimal control system with velocity-acceleration feedback is presented. In finite element modeling of the beam, the variation of mechanical displacement through the thickness is modeled by a sinus model that ensures inter-laminar continuity of shear stress at the layer interfaces as well as the boundary conditions on the upper and lower surfaces of the beam. In addition to mechanical degrees of freedom, one electric potential degree of freedom is considered for each piezoelectric element layer. The efficiency of this control strategy is evaluated by applying to an aluminum cantilever beam under different loading conditions. Numerical simulations show that this new control scheme is almost as efficient as an optimal control system with state feedback. However, inclusion of the acceleration in the control algorithm increases practical value of a system due to easier and more accurate measurement of accelerations.

A Quasi Two-Dimensional Model for Gas Discharge Simulation Using FE-FCT Method (기체 방전의 시뮬레이션을 위한 FE-FCT를 이용한 준 2차원적 수치 모델)

  • Koh, Wook-Hee;Park, In-Ho
    • Journal of the Korean Vacuum Society
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    • v.17 no.6
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    • pp.511-517
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    • 2008
  • A quasi two-dimensional model for numerical simulation of gas discharge is presented, based on the finite-element flux-corrected transport method. A one-dimensional continuity convection-diffusion equation coupled Poisson's equation is solved to calculate the charge density variation and the electric field is evaluated by the classical disk method. Results calculated for various benchmark problems verify the accuracy of the proposed model and illustrate its performance. This model has been applied to a streamer simulation, and the results are shown to agree well with previously published results.

A layerwise theory for buckling analysis of truncated conical shells reinforced by CNTs and carbon fibers integrated with piezoelectric layers in hygrothermal environment

  • Hajmohammad, Mohammad Hadi;Zarei, Mohammad Sharif;Farrokhian, Ahmad;Kolahchi, Reza
    • Advances in nano research
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    • v.6 no.4
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    • pp.299-321
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    • 2018
  • A layerwise shear deformation theory is applied in this paper for buckling analysis of piezoelectric truncated conical shell. The core is a multiphase nanocomposite reinforced by carbon nanotubes (CNTs) and carbon fibers. The top and bottom face sheets are piezoelectric subjected to 3D electric field and external voltage. The Halpin-Tsai model is used for obtaining the effective moisture and temperature dependent material properties of the core. The proposed layerwise theory is based on Mindlin's first-order shear deformation theory in each layer and results for a laminated truncated conical shell with three layers considering the continuity boundary condition. Applying energy method, the coupled motion equations are derived and analyzed using differential quadrature method (DQM) for different boundary conditions. The influences of some parameters such as boundary conditions, CNTs weight percent, cone semi vertex angle, geometrical parameters, moisture and temperature changes and external voltage are investigated on the buckling load of the smart structure. The results show that enhancing the CNTs weight percent, the buckling load increases. Furthermore, increasing the moisture and temperature changes decreases the buckling load.

Analytical and multicoupled methods for optimal steady-state thermoelectric solutions

  • Moreno-Navarro, Pablo;Perez-Aparicio, Jose L.;Gomez-Hernandez, J.J.
    • Coupled systems mechanics
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    • v.11 no.2
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    • pp.151-166
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    • 2022
  • Peltier cells have low efficiency, but they are becoming attractive alternatives for affordable and environmentally clean cooling. In this line, the current article develops closed-form and semianalytical solutions to improve the temperature distribution of Bi2Te3 thermoelements. From the distribution, the main objective of the current work-the optimal electric intensity to maximize cooling-is inferred. The general one-dimensional differential coupled equation is integrated for linear and quadratic geometry of thermoelements, under temperature constant properties. For a general shape, a piece-wise solution based on heat flux continuity among virtual layers gives accurate analytical solutions. For variable properties, another piece-wise solution is developed but solved iteratively. Taking advantage of the formulae, the optimal intensity is directly derived with a minimal computational cost; its value will be of utility for more advanced designs. Finally, a parametric study including straight, two linear, barrel, hourglass and vase geometries is presented, drawing conclusions on how the shape of the thermoelement affects the coupled phenomena. A specially developed coupled and non-linear finite element research code is run taking into account all the materials of the cell and using symmetries and repetitions. These accurate results are used to validate the analytical ones.

A Study of Seamless Power Supply using EDLC on Battery Change of Smartphone (EDLC를 이용한 스마트폰의 배터리 교환 시 연속적 전원 공급에 관한 연구)

  • Choi, Sang-Hun;Lee, Yong-Sung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.12
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    • pp.61-67
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    • 2015
  • Certainly, we are living in a true mobile society. At the end of 2014, approximately 40million 560thousand people are subscribed to smartphone services in Korea, using more than 2000MB of mobile data per a person. The use of smartphone is expected to increase. Moreover, smartphone moves toward becoming a requisite for modern people. Under the circumstances, high-speed communication services such as LTE provide high quality services anywhere and anytime and, furthermore, the development of high performances of the application makes the life patterns of modern people link directly to smartphone. Almost every day, new creative services are being introduced and the demands of on-line streaming services such as high-performance game and YouTube are increasing day after day. However, although smartphones are getting smarter and high quality services are rapidly growing, consumers still complain about the insufficient usage time caused by the capacity of batteries. In order to solve this problem, this thesis suggests EDLC(Electric Double-Layer Capacitor) uses as a supplemental power supply to keep the continuity of work while switching batteries. Through this approach, the running time of smartphone becomes longer as the number of batteries without power off and the purpose of this study is to maximize the convenience of using smartphone by eliminating the initialization of memories and the loss of time of rebooting while batteries are switched.

Numerical Analysis of a Two-Dimensional N-P-N Bipolar Transistor-BIPOLE (2차원 N-P-N 바이폴라 트랜지스터의 수치해석-BIPOLE)

  • 이종화
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.21 no.2
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    • pp.71-82
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    • 1984
  • A programme, called BIPOLE, for the numerical analysis of twotimensional n-p-n bipolar transistors was developed. It has included the SRH and Auger recolnbination processes, the mobility dependence on the impurity density and the electric field, and the band-gap narrowing effect. The finite difference equations of the fundamental semiconductor equations are formulated using Newton's method for Poisson's equation and the divergence theorem for the hole and electron continuity equations without physical restrictions. The matrix of the linearized equations is sparse, symmetric M-matrix. For the solution of the linearized equations ICCG method and Gummel's algorithm have been employed. The programme BIPOLE has been applied to various kinds of the steady-state problems of n-p-n transistors. For the examples of applications the variations of common emitter current gain, emitter and diffusion capacitances, and input and output characteristics are calculated. Three-dimensional representations of some D.C. physical quantities such as potential and charge carrier distributions were displayed. This programme will be used for the nome,rical analysis of the distortion phenom ana of two-dimensional n-p-n transistors. The BIPOLE programme is available for everyone.

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Analyzing the impact of increase in energy price on the general price level (에너지원별 가격조정의 물가파급효과 분석)

  • Lim, Seul-Ye;Song, Tae-Ho;Yoo, Seung-Hoon
    • Journal of Energy Engineering
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    • v.22 no.4
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    • pp.376-385
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    • 2013
  • There are conflicts about energy price increase among government, producer, and consumer. The supplier insists on price increase for escaping running a deficit and business continuity, but the consumer concerns about worsening profitability and price rise. This study investigates the effects of energy rate increase on national economy using input-ouput(I-O) analysis. This study attempts to analyze the effects of national economy due to Coke and hard-coal, Naphtha, Gasoline, Kerosene, Light oil, Heavy oil, Liquefied petroleum gas, Electric utilities, Manufactured gas supply and Steam and hot water supply (using input-output table for the year 2011, Korea.) The results of the sectoral price changes due to a 10% increase in energy price that is obtained from the Leontief price model are presented in article. The result of this analysis is presented: The impact of the 10% increase in electricity rate on the general price level is estimated to be 0.2196%. In case of Kerosene, the impact is 0.1222%. It shows that Electric utilities are approximately 18 times larger price inducing effect as Kerosene. Also, this study indicates 3 years results sequentially to make it possible to observe trend. Then, study suggests balancing price by making each energy source adjusted.

Dependence of Extinction Ratio on the Carrier Transport in $1.55{\mu}m$ InGaAsP/InGaAsP Multiple-Quantum-Well Electroabsorption Modulators ($1.55{\mu}m$ InGaAsP/InGaAsP 다중양자우물구조 전계흡수형 광변조기에서 캐리어 수송현상이 소광특성에 미치는 영향)

  • Shim, Jong-In;Eo, Yung-Seon
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.37 no.9
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    • pp.15-22
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    • 2000
  • The effects of carrier transport and input power on the extinction ratio was theoretically analyzed in a 1.55${\mu}m$ InGaAsP/InGaAsP multiple-quantum-well(MQW) electroabsorption(EA) modulator. Poisson's equation, current continuity equations for electrons and holes, and optical field distribution were self-consistently solved by considering electric field dependent absorption coefficients. The field screening effect due to the carrier accumulation in heterointerface and the space-charge region occurred more seriously at the input side of modulator as input optical intensity increased. It was revealed that extinction ratio could be steeply degraded for modulator with the length of 200${\mu}m$ when an input power exceeds 10mW. A degradation of extinction ratio due to the field screening effect would be more significantly at high-performance devices such as a 1.55${\mu}m$DFB-LD/EA-modulator integrated source where optical coupling efficiency is almost complete or a very high-speed modulator with its length as short as a few tens ${\mu}m$.

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Community development and parasite control (지역사회개발(地域社會開發)과 기생충(寄生虫))

  • Rim, Han-Jong
    • Journal of agricultural medicine and community health
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    • v.1 no.1
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    • pp.10-21
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    • 1976
  • The traditional application of night soil to vegetable gardens and rice paddies results in a most wide spread condition of parasitism, with a variety of helminths found in Korea. In addition to the above fact, the peculiar habit of the consumption of raw vegetables, fish, crustaceans and mammals provides a means of infestations of helminths. During the last sixty years numerous reports were found on the prevalence of helminths amongst the Korean population in different parts of the country, and it was generally recognized that ascariasis, hookworm disease, filariasis, clonorchiasis and paragonimiasis constitute the important helminthic disease in Korea. In practical measures of parasite control activities the main measures are summarized as mass-treatment, night-soil disposal and transmission control. Among the three, the mass-treatment has been commonly applied, however, no reduction of transmission has been obtained by treatment of a population. Therefore, the ultimate eradication of parasites will depend upon the application of comprehensive environmental sanitation measures. The basic environmental measures will be concerned with (a) the safe disposal of human excreta, (b) the provision of adequate and safe water supplies in such a way as to promote a higher standard of personal hygiene in the population, and (c) the prevention of food contamination by faecal material. Additional environmental measures will deal with the improvement of housing and housing hygiene and with general community development. Community development means social and cultural as well as economic development. The control measures on the parasitic endemic diseases, such as clonorchiasis and paragonimiasis are the good examples for community health development in Korea. The control of Clonorchis and Paragonimus infections are theoretically very simple, as the infection can only invade the human body by way of encysted metacercaria which are taken into the body when eating passive intermediate hosts(fishes, crabs and crayfishes). Although prophylactic measures in the case of the infections deal with above merely consist the fishes in cooking or submerging in hot water before eating them, it is exceedingly difficult to carry out such simple measures in face of century old traditions, to which the relatively primitive population clings with great tenacity. There is no one universally applicable method of control. The choice of methods must be dictated by the nature of the environment. the habit and custom of the people. the pattern of transmission and the resources of the country. There must exist a well organized public health infrastructure. Since a control programme is of necessity on a longterm basis and continuity in its implementation is essential. An investigation should be made on the prevalence of the diseases and its relationships to irrigation engineering, freshwater ecology, agricultural methods, hydro-electric schemes, and the development of communities in affected areas. In conclusion, however. the control of clonorchiasis and paragonimiasis in Korea is not an impossible task. A combination of efforts with major emphasis on health education and mass chemotherapy coupled with governmental aid in enforcing legislative public health measures could reduce the diseases. Health education in particular attempts following four things: (a) It supplies a person with enough general knowledge about a disease to make the preventive measures. (b) It makes a person feel sufficiently about the importance of his own health to make him alter his behavior and adopt these preventive measure. (c) It makes him concerned for the health others. (d) It tries to make him feel so strongly about the first three that be supports and even initiates preventive action by the community. Educational efforts should be directed primarily toward school children because it is during the early years that most persons become infected, and also because children are less entrenched in their food habits so that, the educational process should be involved at various levels in successive changes of knowledge, attitude, beha viour, habit and custom of their lives. The most parasitic endemic diseases are related to community diseases. In caring for a sick community. the first stage is to gather epidemiological data, the next is to make inferences from it-to make the community diagnosis. The third is to prescribe community treatment or community health action part of a community health action programme. The community health action is the sum of the steps decided upon to remedy the critical features revealed by the community diagnosis. Action takes various forms; health education is the most important.

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