• 대한기계학회논문집
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• 제17권6호
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• pp.1509-1517
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• 1993

본 연구에서는 3차원 운동을 하는 다물체 기구가 물체 수와 조인트 연결상태 만 주어진 상태에서 구성상태에 따라 절점 좌표계를 이용하여 모델링하고 MACSYMA를 써서 복잡단조로운 대수 계산을 하여 모든 운동학적 정보를 얻어내며 수치계산이 필요 하면 별도의 프로그램을 이용 수치해석을 하는 과정을 밟는다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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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.

• Journal of Microbiology and Biotechnology
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• 제16권9호
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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.

• 한국항공운항학회지
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• 제11권2호
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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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.

• 한국자동차공학회논문집
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• 제13권1호
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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.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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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.

• 한국정밀공학회지
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• 제16권7호
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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.

• 자원ㆍ환경경제연구
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• 제10권3호
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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.

• 대한수학회지
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• 제33권1호
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• pp.69-79
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• 1996