• Archives of Pharmacal Research
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• v.29 no.9
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• pp.795-799
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• 2006

Peptides, although high efficacy and specificity in their physiological function, usually have low therapeutical activities due to their poor bioavailability when administrated orally. Nanoparticles have been regarded as a useful vector for targeted drug delivery system because they can protect drug from being degraded quickly and pass the gastrointestinal barriers. Here we described a novel oral N-trimethyl chitosan nanoparticles formulation containing thymopentin (Tp5-TMC-NP). N-trimethyl chitosan (TMC) was synthesized and then used to prepare Tp5-TMC-NP by ionotropic gelation. A three-factor, five-level CCD (Central Composite Design) design was used in the optimization procedure, with HPLC as the analyzing method. The resulting Tp5-TMC-NP had a regular spherical surface and a narrow particle size range with a mean diameter of 110.6 nm. The average entrapment efficiency was 78.8%. The lyophilized Tp5-TMC-NP formulation was stable in $4^{\circ}C\;or\;-20^{\circ}C$ after storage of 3 months without obvious changes in morphology, particle size, pH and entrapment ratio. The results of the flow cytometer determination showed that the ratio of $CD4^+/CD8^+$ of Wistar female rat given Tp5-TMC-NP (ig) was 2.59 time that of the group given Tp5 (ig).

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.3
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• pp.119-127
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• 2020

The detection and recognition of abnormal driving becomes crucial for achieving safety in Intelligent Transportation Systems (ITS). This paper presents a feature extraction method based on spectral data to train a neural network model for driving behavior recognition. The proposed method uses a two stage signal processing approach to derive time-saving and efficient feature vectors. For the first stage, the feature vector set is obtained by calculating variances from each frequency bin containing the power spectrum data. The feature set is further reduced in the second stage where an intersection method is used to select more significant features that are finally applied for training a neural network model. A stream of live signals are fed to the trained model which recognizes the abnormal driving behaviors. The driving behaviors considered in this study are weaving, sudden braking and normal driving. The effectiveness of the proposed method is demonstrated by comparing with existing methods, which are Particle Swarm Optimization (PSO) and Convolution Neural Network (CNN). The experiments show that the proposed approach achieves satisfactory results with less computational complexity.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.7
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• pp.816-820
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• 2004

Clustering is a process of dividing similar data objects in data set into clusters and acquiring meaningful information in the data. The main issues related to clustering are the effective clustering of high dimensional data and optimization. This study proposed a method of measuring similarity based on SVM and a new method of calculating the number of clusters in an efficient way. The high dimensional data are mapped to Feature Space ones using kernel functions and then similarity between neighboring clusters is measured. As for created clusters, the desired number of clusters can be got using the value of similarity measured and the value of Δd. In order to verify the proposed methods, the author used data of six UCI Machine Learning Repositories and obtained the presented number of clusters as well as improved cohesiveness compared to the results of previous researches.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.2
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• pp.81-86
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• 2014

In the scalable video coding standard, inter-layer prediction based on the coding information of the base layer was adopted to increase the coding performance. This prediction tool results in new syntax elements called motion_prediction_flag (mPF) and residul_prediction_flag(rPF), which are carried to notify the motion vector predictor (MVP) and reference block required in the motion compensation of the decoder. In this paper, an efficient coding method for mPF is proposed to enhance coding efficiency of the salable video coding standard. Through an analysis on the transmission of mPF based on the relationship between the MVPs, we discover the conditions where mPF is unnecessary at the decoder and suggest a modified rate-distortion (RD) cost function to make RD optimization more effective. Simulation results show that the proposed method offers BD rate savings of approximately 1.4%, compared with the conventional SVC standard.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.4
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• pp.1-7
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• 2002

QFT is a very practical design technique that emphasizes the use of feedback for achieving the desired system performances in despite of plant uncertainties and disturbances. The loop shaping procedure of QFT is employed to design the robust controller, until the desired bounds are satisfied. This paper presents an optimization algorithm for designing PID controller using the loop shaping of QFT. The proposed method identifies the parameter vector of PID controller from a linear system that develops from rearranging the two dimensional system matrices and output vectors obtained from the QFT bounds. The feasibilities of the suggested algorithm are illustrated with a turbine speed control problem.

• Journal of applied mathematics & informatics
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• v.27 no.3_4
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• pp.621-638
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• 2009

The linear system Ax = b will have (i) no solution, (ii) only one non-trivial (trivial) solution, or (iii) infinity of solutions. Our focus will be on cases (ii) and (iii). The mathematical models of many real-world problems give rise to (a) ill-conditioned linear systems, (b) singular linear systems (A is singular with all its linearly independent rows are sufficiently linearly independent), or (c) ill-conditioned singular linear systems (A is singular with some or all of its strictly linearly independent rows are near-linearly dependent). This article highlights the scope and need of a randomized algorithm for ill-conditioned/singular systems when a reasonably narrow domain of a solution vector is specified. Further, it stresses that with the increasing computing power, the importance of randomized algorithms is also increasing. It also points out that, for many optimization linear/nonlinear problems, randomized algorithms are increasingly dominating the deterministic approaches and, for some problems such as the traveling salesman problem, randomized algorithms are the only alternatives.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9A
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• pp.856-867
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• 2006

This paper proposes a new algorithm for opportunistic scheduling that take advantage of both multiuser diversity and power control. Motivated by the multicast RTS and priority-based CTS mechanism of OSMA protocol, we propose an opportunistic packet scheduling with power control scheme based on IEEE 802.11 MAC protocol. The scheduling scheme chooses the best candidate receiver for transmission by considering the SINR at the nodes. This mechanism ensures that the transmission would be successful. The power control algorithm on the other hand, helps reduce interference between links and could maximize spatial reuse of the bandwidth. We then formulate a convex optimization problem for minimizing power consumption and maximizing net utility of the system. We showed that if a transmission power vector satisfying the maximum transmission power and SINR constraints of all nodes exist, then there exists an optimal solution that minimizes overall transmission power and maximizes utility of the system.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1363-1371
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• 2017

In this paper, an improved Direct Power Control (DPC) algorithm is presented for grid connected three phase PWM rectifiers. The new DPC approach is based on two main tasks. First the optimization of the look-up table, which is well-known in conventional DPC, is outlined for selecting the optimum converter output voltage vectors. Secondly a very simple and effective method is used to directly calculate their duty cycles from the power errors. Therefore, the measured active and reactive powers are made to track their references using hysteresis controllers. Then two vectors are selected and applied during one control cycle to minimize both the active and reactive power ripples. The main advantages of this method are that there is no need of linear current controllers, coordinates transformations or modulators. In addition, the control strategy is able to operate at constant switching frequencies to ease the design of the power converter and the AC harmonic filter. The control exhibits a good steady state performance and improves the dynamic response without any overshoot in the line current. Theoretical principles of the proposed method are discussed. Both simulation and experimental results are presented to verify the performance and effectiveness of this control scheme.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.44-52
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• 2012

Fuel cell electric vehicles have some noise problems due to its air processing unit which is required to feed the ambient air into the fuel cell stack. Discrete-frequency noises are radiated from a centrifugal blower due to rotor-stator interaction. Their fundamental frequency is the blade passing frequency, which is determined by the number of rotor blades and their rotating speed. To reduce such noises, multi-chamber perforated muffler has been designed. In this paper, in order to improve the transmission loss of a perforated muffler, the relationship between the impedance model of a perforated hole and its noise reduction performance is studied, and the applicability of a short-length perforated muffler to air processing unit of fuel cell system is described using acoustic simulation results and experimental data. The acoustic velocity vector across the neck of a perforated hole is very important design factor to optimize the transmission of an intake muffler. The suggested short-length perforated muffler is effective on discrete-frequency noises while keeping the volume of intake muffler minimized.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.67-74
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• 2005

This paper concerns attitude controller design for a 3-staged launch vehicle which has movable nozzle TVC systems for all stages as its control systems. The PD-type control gains are determined by shaping the corresponding closed-loop natural frequencies for the purpose of guaranteeing the required stability margin. Bending filters are also designed to stabilize the bending modes by using parametric optimization method. The designed controllers are verified using six degree of freedom flight simulations in MATLAB.