• Title/Summary/Keyword: relative efficient

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Analysis of Spatial Mechanism Using Symbolic Computation (기호예산을 이용한 공간기구의 해석)

  • 이동민;윤용산
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.6
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    • pp.1509-1517
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    • 1993
  • The purpose of this study is to develop a program for the automatic derivation of the symbolic equations necessary for the kinematic and dynamic analyses of the spatial mechanism. For this purpose, a symbolic manipulation package called MCSYMA is used. Every symbolic equation is formulated using relative joint coordinate to obtain the numerically efficient system equations. These equations are produced in FORTRAN statements and linked to a FORTRAN program for numerical analysis. Several examples are taken for comparison with the commercial package called DADS which is using Cartesian coordinate approach. Also, this symbolic formulation approach is compared with a conventional numerical approach for an example. The results show that this symbolic approach with relative joint coordinate system is most efficient in computational time among three and is recommended for the derivation of macro elements frequently used.

Fabrication and Characterization of Electro-photonic Performance of Nanopatterned Organic Optoelectronics

  • Nil, Ri-Swi;Han, Ji-Yeong;Gwon, Hyeon-Geun;Lee, Gyu-Tae;Go, Du-Hyeon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.134.2-134.2
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    • 2014
  • Photonic crystal solar cells have the potential for addressing the disparate length scales in polymer photovoltaic materials, thereby confronting the major challenge in solar cell technology: efficiency. One must achieve simultaneously an efficient absorption of photons with effective carrier extraction. Unfortunately the two processes have opposing requirements. Efficient absorption of light calls for thicker PV active layers whereas carrier transport always benefits from thinner ones, and this dichotomy is at the heart of an efficiency/cost conundrum that has kept solar energy expensive relative to fossil fuels. This dichotomy persists over the entire solar spectrum but increasingly so near a semiconductor's band edge where absorption is weak. We report a 2-D, photonic crystal morphology that enhances the efficiency of organic photovoltaic cells relative to conventional planar cells. The morphology is developed by patterning an organic photoactive bulk heterojunction blend of Poly(3-(2-methyl-2-hexylcarboxylate) thiophene-co-thiophene) and PCBM via PRINT, a nano-embossing method that lends itself to large area fabrication of nanostructures. The photonic crystal cell morphology increases photocurrents generally, and particularly through the excitation of resonant modes near the band edge of the organic PV material. The device performance of the photonic crystal cell showed a nearly doubled increase in efficiency relative to conventional planar cell designs. Photonic crystals can also enhance performance of other optoelectronic devices including organic laser.

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An Efficient Secretion of Type I Secretion Pathway-Dependent Lipase, TliA, in Escherichia coli: Effect of Relative Expression Levels and Timing of Passenger Protein and ABC Transporter

  • Eom Gyeong-Tae;Rhee Joon-Shick;Song Jae-Kwang
    • Journal of Microbiology and Biotechnology
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    • v.16 no.9
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    • pp.1422-1428
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    • 2006
  • An ABC transporter apparatus of the Gram-negative bacterial type I secretion pathway can be used as a secretory protein expression system in Escherichia coli. Four types of coexpression systems for the Pseudomonas fluorescens lipase gene, tliA, and its cognate ABC transporter gene cluster, tliDEF, were constructed. When the relative expression levels were changed by adding different concentrations of IPTG, the secretion (16.9 U/ml of culture) of TliA in E. coli [pTliDEFA-223+pACYC184] was significantly higher than E. coli [pKK223-3+pTliDEFA-184] secreting the lowest level of TliA (5.2 U/ml of culture). Maximal accumulation of the lipase secreted occurred in the mid-exponential phase, implying that the efficient protein secretion via an ABC transporter was restricted only to actively growing cells. Finally, the secretion level of TliA in E. coli [pTliDEFA-223+pACYC184] was increased to 26.4 U/ml by inducing gene expression at the culture initiation time. These results indicate that a significant increase in the ABC transporter-dependent protein secretion can be achieved by simply controlling the relative expression levels between the ABC transporter and its passenger protein, even in the recombinant E. coli cells.

A Study on the relative Efficiency of ATC Towers in Domestic Airports (국내공항 관제탑의 상대적 효율성에 관한 연구)

  • Kim, D.H.
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.11 no.2
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    • pp.59-77
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    • 2003
  • Air Traffic Control Tower is one of the most important units in Airport operation. It provides services related to safe and efficient traffic flows that control aircraft on the ground maneuvering area and terminal airspace. Also It is responsible for managing of ground operators. The major objective of this study is to evaluates relative efficiency of ATC towers in Domestic airports using data envelopment analysis so that it helps the ATC authority to improve the tower efficiency, to decide the level of benchmarking target and to establish the best alternative. The results of this study are the following; First, as a result of analysis for the potential improvement, it has analysed that the common problems of each ATC tower are to increase its number of flight and to reduce its number of runway followed by airside area, the number of air traffic controller and the number of stand. Second, it has shown that the each tower in RKPC(8), RKPT(5), RKPK(l) and RKSS(l) are used as the reference set. Especially, the tower in RKPC analyzed as a relatively efficient unit is the most main target for the towers in RKTU, RKTH, RKPS and RKTY to do bench marking and to set up the strategy for improving relative efficiency of the tower. Third, tower is actually not able to control the input and output data in this study except the number of controller, so that ATC authority is recommended to improve inefficiency of the towers through handling the number of controller.

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Development of an Efficient Force Reflection Algorithm for a Virtual Environment (가상환경을 위한 효율적인 힘방향 알고리즘의 개발)

  • 권혁조;김기호;오재윤
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.60-63
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    • 2000
  • In this study, efficient force reflection algorithm is developed for the Haptic Display by using a proxy concept and friction model. When there are not any contacted obstacles the proxy is following human operator's command trajectory in the 3D virtual space. But when the operator's command trajectory is locating inside of the object, the proxy is constrained by the surface of the object. Here only with the information of the proxy position and operator's command trajectory at every time step, we can calculate the reflection force and its orientation. To display the friction force between two virtual stiff material which are sliding against each other, modified Karnopp's friction model is used. In the friction model, a damping term and a Stribeck effect term are included to display the relative velocity effect and stick-slip effect at the very low relative velocity region respectively.

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Development of an Efficient Vehicle Dynamics Model Using Massless Link of a Suspension (현가장치 무질량 링크를 이용한 효율적인 차량동역학 모델 개발)

  • Jung Hongkyu;Kim Sangsup
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.1
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    • pp.99-108
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    • 2005
  • This paper represents an efficient modeling method of a suspension system for the vehicle dynamic simulation. The suspension links are modeled as composite joints. The motion of wheel is defined as relative one degree of freedom motion with respect to car body. The unique relative kinematic constraint formulation between the car body and wheel enables to derive equations of motion in terms of wheel vertical motion. Thus, vehicle model has ten degrees of freedom. By using velocity transformation method, the equations of motion of the vehicle is systematically derived without kinematic constraints. Various vehicle simulation such as J-turn, slowly increasing steer, sinusoidal sweep steer and bump run has been performed to verify the validity of the suggested vehicle model.

DEVELOPMENT OF AN UNSTRUCTURED OVERSET MESH METHOD FOR 2-D UNSTEADY VISCOUS FLOW ANALYSIS (이차원 비정상 점성 유동 해석을 위한 비정렬 중첩격자기법 개발)

  • Jung M. S.;Kwon O. J.
    • 한국전산유체공학회:학술대회논문집
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    • 2005.10a
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    • pp.135-139
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    • 2005
  • An unstructured overset mesh method has been developed for the simulation of unsteady viscous flow fields around multiple bodies in relative motion. For this purpose, a robust and fast search technique is proposed for both triangle and high-aspect quadrilateral cell elements. The interpolation boundary is defined for data communication between grid systems and an interpolation method is suggested for viscous and inviscid cell elements. This method has been applied to calculate the flow fields around 2-D airfoil including relative motion. Validation were made by comparing the predicted results with those of experiments or other researcher's numerical results. It was demonstrated that the present method is efficient and robust for the prediction of unsteady time-accurate flow fields involving multiple bodies in relative motion.

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Relative Error Compensation of Robot Using Neural Network (신경 회로망을 이용한 로봇의 상대 오차 보상)

  • Kim, Yeon-Hoon;Jeong, Jae-Won;Kim, Soo-Hyun;Kwak, Yoon-Keun
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.7
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    • pp.66-72
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    • 1999
  • Robot calibration is very important to improve the accuracy of robot manipulators. However, the calibration procedure is very time consuming and laborious work for users. In this paper, we propose a method of relative error compensation to make the calibration procedure easier. The method is completed by a Pi-Sigma network architecture which has sufficient capability to approximate the relative relationship between the accuracy compensations and robot configurations while maintaining an efficient network learning ability. By experiment of 4-DOF SCARA robot, KIRO-3, it is shown that both the error of joint angles and the positioning error of end effector are drop to 15$\%$. These results are similar to those of other calibration methods, but the number of measurement is remarkably decreased by the suggested compensation method.

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Relative Efficiencies of Food Waste, Treatment Facilities: A Nonparametric Approach (음식물쓰레기 비매립·비소각 처리방법별 상대적 효율성 분석 -경제성과 환경성의 통합적 평가 -)

  • Kwon, Oh Sang;Kang, Dae Hee;Lee, Jeong-Im;Lim, Dongsoon
    • Environmental and Resource Economics Review
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    • v.10 no.3
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    • pp.323-344
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    • 2001
  • This study analyzes the relative efficiencies of three types of non-landfill treatment of food wastes; recycling to fertilizers or animal feeds, reducing the size of food wastes, and fermentation of food wastes. Unlike previous studies our study incorporates not only usual inputs and outputs but also emissions of pollutants such as odor and noise generated by the treatment facilities into the analysis. A nonparametric method suggested by Fare et al. (1989) has been used to estimate the relative efficiencies of facilities incorporating emission of pollutants. The results show that recycling is more efficient than the other two treatment methods. It is also shown that the usual models that do not incorporate the environmental aspects of the treatment facilities derive a biased conclusion on the relative efficiencies.

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