• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.28-28
• /
• 2000

Low-cost solid-state inertial sensors of three rate Gyroscopes and a triaxial Accelerometer are evaluated in static and dynamic environments. As a interim result, error models of each inertial sensors are generated. Model parameters with respect to temperature are acquired in static environment. These error models are included in an Extended Kalman Filter(EKF) to compensate bias error due to temperature variation. Experimental results in dynamic environment are included to show the validity of the each error model and the performance improvement of a compensated low cost inertial sensors for a navigational application

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.6
• /
• pp.66-76
• /
• 1999

Vehicle driving simulators have been used in the development and modification of models. A simulator can reduce cost and time through a variety of driving simulations in the laboratory. Recently, driving simulators have begun to proliferate in the automotive industry and the associated research community. This paper presents the hardware and software developed for a driving simulator of construction vehicles. This effor involves the real-time dynamic analysis of wheel-type excavator, the design and manufacturing of the Stewart platform, an integrated control system of the platform, and three-dimensional graphic modeling of the driving environments.

• International Journal of Aeronautical and Space Sciences
• /
• v.5 no.2
• /
• pp.43-53
• /
• 2004

Collision avoidance for multiple aircraft can be stated as a problem ofmaintaining safe distance between aircraft in conflict. Optimal collision avoidanceproblem seeks to minimize the given cost function while simultaneously satisfyingconstraints. The cost function could be a function of time or control input. This paper addresses the trajectory time-optimization problem for collision avoidance of unmanned aerial vehicles(UAVs). The problem is difficult to handle in general due to the two-point boundary value problem subject to dynamic environments. Some simplifying aleorithms are used for potential applications in on-line operation.Although under possibility of more complicated problems, a dynamic problem is transformed into a static one by prediction of the conflict time and some appropriate assumptions.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.19 no.4
• /
• pp.417-428
• /
• 2015

Although, in general, the random fluctuation of interest rates gives a limited impact on portfolio optimization, their stochastic nature may exert a significant influence on the process of selecting the proportions of various assets to be held in a given portfolio when the stochastic volatility of risky assets is considered. The stochastic volatility covers a variety of known models to fit in with diverse economic environments. In this paper, an optimal strategy for portfolio selection as well as the smoothness properties of the relevant value function are studied with the dynamic programming method under a market model of both stochastic volatility and stochastic interest rates.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.12
• /
• pp.4293-4304
• /
• 2014

In order to ensure the wireless connectivity and seamless service to mobile users, the next generation network system will be an integration of multiple wireless access networks. In a heterogeneous wireless access system, bandwidth allocation becomes crucial for load balancing to avoid network congestion and improve system utilization efficiency. In this article, we propose a new dynamic bandwidth allocation scheme for hierarchical wireless network systems. First, we derive a multi-objective decision criterion for each access point. Second, a bargaining strategy selection algorithm is developed for the dynamic bandwidth re-allocation. Based on the intervenient Stackelberg game model, the proposed scheme effectively formulates the competitive interaction situation between several access points. The system performance of proposed scheme is evaluated by using extensive simulations. With a simulation study, it is confirmed that the proposed scheme can achieve better performance than other existing schemes under widely diverse network environments.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 1997.10a
• /
• pp.126-131
• /
• 1997

Recently, the ground motion occurred by vehicles or trains has been recognized one of the major factors of damage of structures nearly the motion source. To isolate the environments from ground motions, it is necessary to understand the wave propagation in half spaces. Especially, Rayleigh wave is the primary concern because it transmits a major portion of the total source energy and decays the energy more slowly with response to distance than the other waves. In this study, the preliminary data(wave length and damping effect) to design the isolating system are obtained. For this, a field dynamic test is performed, using the exciter which can generate the 100kN vertical cyclic load in the range of 1-60 Hz is used. The fifteen accelerometers to measure the ground response are set up in 3 radial direction at intervals of 10 meters in each row. The wave lengths are calculated using the distance and the phase between the measuring points. The damping effects of the Rayleigh-wave are also observed from the experiments.

• Electronics and Telecommunications Trends
• /
• v.35 no.2
• /
• pp.69-78
• /
• 2020

Small portable devices such as mobile phones and laptops currently display a trend of high power consumption owing to their characteristics of high speed and multifunctionality. Low-power SoC design is one of the important factors that must be considered to increase portable time at limited battery capacities. Popular low power SoC design techniques include clock gating, multi-threshold voltage, power gating, and multi-voltage design. With a decreasing semiconductor process technology size, leakage power can surpass dynamic power in total power consumption; therefore, appropriate low-power SoC design techniques must be combined to reduce power consumption to meet the power specifications. This study examines several low-power SoC design trends that reduce semiconductor SoC dynamic and static power using EDA tools. Low-power SoC design technology can be a competitive advantage, especially in the IoT and AI edge environments, where power usage is typically limited.

• International Journal of Control, Automation, and Systems
• /
• v.3 no.1
• /
• pp.137-142
• /
• 2005

Biomedical signals such as ECG, EMG, and EEG are extremely important in the diagnosis of patients. It is difficult to filter noise from these signals, and errors resulting from filtering can distort a biomedical signal. Existing systems have shown poor performance when complicated noise appears. Adaptive filtering is selected to contend with these defects. Existing adaptive filters can adjust the filter coefficient with the given filter order, but they can produce an unsuitable order in different environments. In order to solve this problem, an optimal adaptive filter with a dynamic structure was designed. Positive experimental results were obtained.

• Journal of Korean Institute of Industrial Engineers
• /
• v.31 no.2
• /
• pp.120-126
• /
• 2005

Until now, the traditional production models and logistics have developed a broader strategic approach called supply chain. However, there are some obstacles to apply industry practice because of unrealistic assumptions. The most serious of them is that they assume the lead times are integer multiples of the planning time grid. This assumption makes it difficult to express the processing and transportation lags correctly. Thus, in this paper, we propose a new methodology for the integrated production/distribution model having non-integer time lags using the concept of dynamic production function. In case that the time lags are integer or non-integer, the dynamic production function reflects well the situation under given environments. Experiments show that the proposed model can express the real system more accurately than the prior model can.

• The Mathematical Education
• /
• v.43 no.2
• /
• pp.177-186
• /
• 2004

In this paper, we introduce new functional definitions for school geometry based on DGS (dynamic geometry system) teaching-learning environment. For the vertices forming a geometric figure, we first consider the relationship between the independent vertices and dependent vertices, and using this relationship and educational considerations in DGS, we introduce functional definitions for the geometric figures in terms of its independent vertices. For this purpose, we design a new DGS called JavaMAL MicroWorld. Based on the needs of new definitions in DGS environment for the student's construction activities in learning geometry, we also design a new DGS based geometry curriculum in which the definitions of the school geometry are newly defined and reconnected in a new way. Using these funct onal definitions, we have taught the new geometry contents emphasizing the sequential expressions for the student's geometric activities.