• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.9
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• pp.1104-1109
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• 1992

A mathematical model of cancerous system based on immunological surveillance has been proposed by Lee. The model involves a system of 12 coupled nonlinear differential equations due to cellular kinetics and each of them can be modeled bilinearly. This paper discusses only the properties of solutions to the nonlinear differential equations and identification.

• Journal of applied mathematics & informatics
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• v.33 no.5_6
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• pp.687-697
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• 2015

This paper shows that the solutions to the perturbed nonlinear functional differential system

• Journal of applied mathematics & informatics
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• v.30 no.1_2
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• pp.279-287
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• 2012

In this paper, we investigate bounds for solutions of the nonlinear differential systems using the notion of $t_{\infty}$-similarity.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.5
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• pp.54-59
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• 2007

We abtain some stability results for a very general differential system using the method of cone valued vector Lyapunov functions and conversely some sufficient conditions for existence of such vector Lyapunov functions.

• The Pure and Applied Mathematics
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• v.8 no.2
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• pp.137-143
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• 2001

In this paper, we study the existence, uniqueness and norm estimate of solutions for the nonlinear delay integro-differential system.

• East Asian mathematical journal
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• v.40 no.1
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• pp.37-50
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• 2024

We establish the existence, multiplicity and uniqueness of positive solutions to nonlocal boundary value systems with strongly coupled integral boundary condition by using the global continuation theorem and Banach's contraction principle.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.297-300
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• 2016

The typical Differential Global Navigation Satellite System service of South Korea is the Ground Based Differential GNSS service. South Korea building the Satellite-Based Augmentation System for GNSS to expand the Differential GNSS service. The satellite-based differential GNSS serive is called the SBAS(Satellite Based Augmentation System). The SBAS reference station on ground should be installed to operate the SBAS service alike the ground based augmentation system. That SBAS reference station can be installed with ground based DGNSS reference station. To make the SBAS reference station combined with the ground based DGNSS reference station, DGNSS system should be connected to NovAtel's G-III receiver. In this paper, the DGNSS software reference station's software module architecture was changed and G-III interface module was designed to use the G-III receiver.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.53-63
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• 2013

To guide the decision making of the expert engineer specialized in power system operation and control; the practical OPF solution should take in consideration the critical situation due to severe loading conditions and fault in power system. Differential Evolution (DE) is one of the best Evolutionary Algorithms (EA) to solve real valued optimization problems. This paper presents simple Differential Evolution (DE) Optimization algorithm to solving multi objective optimal power flow (OPF) in the power system with shunt FACTS devices considering voltage deviation, power losses, and power flow branch. The proposed approach is examined and tested on the standard IEEE-30Bus power system test with different objective functions at critical situations. In addition, the non smooth cost function due to the effect of valve point has been considered within the second practical network test (13 generating units). The simulation results are compared with those by the other recent techniques. From the different case studies, it is observed that the results demonstrate the potential of the proposed approach and show clearly its effectiveness to solve practical OPF under contingent operation states.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.2
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• pp.222-231
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• 2016

This paper proposes a new method achieving computationally efficient attitude reference system for low cost strapdown sensors and microprocessor platform. The main idea in this method is to define and compare velocity differential vectors, geometrically computed from INS and GPS data with different update rate, for generating attitude error measurements which is further used for filter construction. A quaternion based Kalman filter configuration is applied for the attitude estimation with the adapted measurement model of differential vector comparison. Linearized model for Extended Kalman Filter and low pass filtered characteristics of measurement greatly extend the affordability of the proposed algorithm to the field of simple low cost embedded systems. For performance verification, experiment are done employing a practical low cost MEMS IMU and GPS receiver specification. Performance comparison with a high grade navigation system demonstrated good estimation result.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.6
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• pp.303-309
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• 2020

A vehicle's differential gear is a device designed to allow the vehicle's outer wheels to turn faster than the inner wheels when turning on a curve. The differential gear case is the main component of the differential gear system, which is composed of ring gear, pinion gear and side gear, and is fastened by pinion shaft pins. The differential gear case rotates when the vehicle is running, so balancing calibration is very important. In this study, a balancing machine that can diagnose and correct the differential gear case and mass imbalance of various rotating bodies was designed. The differential gear case was rotated at high speed to accurately diagnose the location and value of the unbalanced mass, and it was designed to be balanced and corrected by removing the unbalanced mass by drilling. After calibration, it was confirmed that the unbalanced value of all the measured samples was reduced to less than 180g.mm, and the unbalance reduction ratio was improved to 60~70%.