• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.235-235
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• 2012

We investigated the energy levels of valence region at the planar junction of poly (3-hexylthiophene) (P3HT) and C61-butyric acid methylester (PCBM) using ultraviolet photoemission spectroscopy (UPS) with ultra high vacuum. These are the most widely used materials for bulk heterojunction (BHJ) organic solar cells due to their high efficiency. In order to make the planar junction, we carried out the electrospray vacuum deposition (EVD) of PCBM onto spin-coated P3HT in high vacuum conditions (${\sim}10^{-5}-10^{-6}$). The planar junction interface exhibited 0.71 eV for the offset between P3HT HOMO and PCBM LUMO, which is different from the gap (0.85 eV) of individual values and is closer to the open circuit voltage of solar cells fabricated with the same material combination.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1263-1266
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• 1997

In a fault-tolerant modern manufacturing systms characterized by the configuration, in which automated redundant machines prone to unexpected failures are interconnected with other complex subsystems such as AGV's, robots, computer control systems to produce complete parts, faulures together with repairs and reconfigurations should be considered as the three basic events to be modeled for computing the performance of manufacturing systems. In this papre, transient analysis is applied to modular cell manufacturing systems form a performability viewpoint whose modeling adantage is that various performanc e measures can be evaluated compositely in the context of application. The hypothertical modular cells are modeled firstly with hybrid decomposition method and availability measures as special cases of performability are computed and comments on performabililty modeling analysis are mentioned.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.644-647
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• 1997

Asymmetric cylinders are usually used as an actuator of active suspensions. The conventional optimal controller design does not include actuator dynamics as a state and force controller is needed to track the desired force. But the actuator is not ideal, so performance of an active suspension system is degraded. In this paper, we take account nonlinear actuator dynamics and obtain a linear model using a feedback linearization technique then apply optimal control method. Effectiveness of proposed method is demonstrated by numerical simulation of 1/4 car model.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1072-1077
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• 2004

This paper provides a new approach to analyze the stability of a general multi-link TCP Vegas, which is a kind of feedback-based congestion algorithm. Whereas the conventional approaches use the approximately linearized model of the TCP Vegas along equilibrium pints, this approach models a multi-link TCP Vegas network in the form of a piecewise linear multiple time-delay system. And then, based on the exactly characterized dynamic model, this paper presents a new stability criterion via a piecewise and multiple delay-dependent Lyapunov-Krasovskii function. Especially, the resulting stability criterion is formulated in terms of linear matrix inequalities (LMIs).

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1905-1910
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• 2003

It is well known that parameter uncertainties and time-delays cannot be avoided in practice and result in poor performance and even instability. Nevertheless, to the authors' best knowledge, there exist few results on model predictive control (MPC) handling explicitly uncertain time-delayed systems. In this paper, we present an MPC algorithm for uncertain time-varying systems with input constraints and state-delay. An optimization problem is suggested to find a memoryless state-feedback MPC law and the closed-loop stability is established under feasibility and certain conditions.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2418-2423
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• 2003

Bluetooth is a low cost, license-free, and short-range radio communication technology. This gradually gaining de facto standard for applications of a personal area network over the world. To make it further popular, it should provide faster and more flexible connectivity than that supported by the existing bluetooth specification. This paper proposes a new Ad hoc scatternet formation algorithm that supports those connectivity under circumstances such that devices can not get in direct touch with one another; say out-of-bounded case. It also maintains the character that those connectivity minimizes the number of piconets when all devices are in the communication range with one another, say in-bounded case, as pervious works.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2430-2434
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• 2003

This paper provides a new approach to analyze the stability of TCP Vegas, which is a kind of feedback-based congestion control algorithm. Whereas the conventional approaches use the approximately linearized model of the TCP Vegas along equilibrium points, this approach uses the exactly characterized dynamic model to get a new stability criterion via a piecewise and delay-dependent Lyapunov-Krasovskii function. Especially, the resulting stability criterion is formulated in terms of linear matrix inequalities (LMIs). Using the new criterion, this paper shows that the current TCP Vegas algorithm is stable in the sufficiently wide region of network delay and link capacity.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.468-472
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• 2003

The lifting technique is a standard control procedure that is commonly applied to dual-rate systems, where a critical difficulty is that care must be taken so that the resulting equivalent system preserves the causality constraint between the control signal and the measured output. To overcome this difficulty, the most attractive result has been suggested by defining control time sequences as the union of sample and hold time sequences. However, the sacrifice of regular control period scheme results in some serious disadvantages; restrictions on the implementation to hardware and the corresponding inefficient control scheme. On the contrary, this paper proposes a novel dual-rate control technique, which redescribes the system as a control-rate-based system having regular control period and designs the controller, with no causality constraint, through Linear Matrix Inequality (LMI) formulation.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.530-535
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• 2004

This paper considers a state set estimation (SSE) based model predictive control (MPC) for linear parameter- varying (LPV) systems with input constraint. We estimate, at each time instant, a feasible set of all states which are consistent with system model, measurements and a priori information, rather than the state itself. By combining a state-feedback MPC and an SSE, we design an SSE-based MPC algorithm that stabilizes the closed-loop system. The proposed algorithm is solved by semi-de�nite program involving linear matrix inequalities. A numerical example is included to illustrate the performance of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.91-92
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• 2008

Localization and its applications are very important area of the mobile robot technology. Especially, accurate localization is needed when we move the mobile robot to the goal position. In indoor cases, Global Positioning System(GPS) is not suitable but Radio Frequency Identification(RFID) technology can provide position data to the robot. A proposed algorithm in this paper uses not only odometry data but also RFID data to improve estimation of true position of the robot with the particle filtering.