• International Journal of Control, Automation, and Systems
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• v.5 no.6
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• pp.621-629
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• 2007

In the adaptive fuzzy control field for affine nonlinear systems, there are two basic configurations: direct and indirect. It is well known that the direct configuration needs more restrictions on the control gain than the indirect configuration. In general, these restrictions are difficult to check in practice where mathematical models of plant are not available. In this paper, using a simple extension of the universal approximation theorem, we show that the only required constraint on the control gain is that its sign is known. The Lyapunov synthesis approach is used to guarantee the stability and convergence of the closed loop system. Finally, examples of an inverted pendulum and a magnet levitation system demonstrate the theoretical results.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.3 no.2
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• pp.161-171
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• 1999

Aerodynamic sensitivity analysis codes are developed via the hand-differentiation using a direct differentiation method and an adjoint method respectively from discrete two-dimensional compressible Navier-Stokes equations. Unlike previous other researches, Baldwin-Lomax algebraic turbulence model is also differentiated by hand to obtain design sensitivities with respect to design variables of interest in turbulent flows. Discrete direct sensitivity equations and adjoint equations are efficiently solved by the same time integration scheme adopted in the flow solver routine. The required memory for the adjoint sensitivity code is greatly reduced at the cost of the computational time by allowing the large banded flux jacobian matrix unassembled. Direct sensitivity code results are found to be exactly coincident with sensitivity derivatives obtained by the finite difference. Adjoint code results of a turbulent flow case show slight deviations from the exact results due to the limitation of the algebraic turbulence model in implementing the adjoint formulation. However, current adjoint sensitivity code yields much more accurate sensitivity derivatives than the adjoint code with the turbulence eddy viscosity being kept constant, which is a usual assumption for the prior researches.

• Korean Journal of Organic Agriculture
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• v.28 no.3
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• pp.273-288
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• 2020

The purpose of this study is to estimate farmers' willingness to accept (WTA) of direct payment for increasing public benefit using the contingent valuation method. The double-bounded dichotomous choice and the open-ended question were used to measure WTAs for basic form and optional form, respectively. The results show that WTA for basic form was inversely proportional to the acreage. WTAs were KRW 1,694,001 with 2 ha or less, KRW 1,617,789 with over 2 ha~6 ha, and KRW 1,562,977 with over 6 ha. The results also indicate that WTAs for optional form are similar to payments of agricultural environmental conservation program except physical (chemical) control of pests and weed. The results of this study can provide useful information for the establishment of direct payment for increasing public benefit.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1751-1756
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• 2007

This paper presents a high performance pressure control scheme for SR(Switched Reluctance) type hydraulic oil pump using DITC(Direct Instantaneous Torque Control). SR drive has a good feature for pump applications due to a high efficiency, high speed and high torque characteristics. But, SR drive has high torque ripple in commutation region. So, the pump pressure variation is high in the region. In order to reduce the pressure variation, DITC combined with pressure control scheme is presented in this paper. A simple PI controller with flow and pressure limit, generates a reference torque to keep the constant actual pump pressure. The direct torque controller of SR drive generates inverter switching signals according to a control rule and a torque estimator. Computer simulation and experiemtal results show the validation of the proposed control scheme.

• Korean Journal of Poultry Science
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• v.26 no.3
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• pp.189-193
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• 1999

This experiment was conducted to investigate the effect of floor heating system on housing environment and performance in broiler production. PVC heating pipes(in 25cm spacing) were covered with concrete under the litter. Floor heating system was compared with conventional direct heating system. Each treatment had two replicates of 110 birds each. Litter moisture content was significantly reduced in floor heating system than conventional direct heating system(P〈0.05). Dust concentration was higher in floor heating system because of low litter moisture content. CO$_2$concentration was 2,900ppm and 1,500ppm on the direct heating system and floor heating system, respectively at the age of 1 week. Body weight was significantly higher in floor heating system at 7 weeks of age(P〈0.05). The results of the trial show that floor heating was useful heating system for broiler production.

• Structural Monitoring and Maintenance
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• v.1 no.2
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• pp.213-230
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• 2014

A novel real-time actuator failure detection algorithm is developed in this paper. Actuator fails when the input to the structure is different from the commanded one. Previous research has shown that one error function can be formulated for each actuator through interaction matrix method. For output without noise, non-zero values in the actuator functions indicate the instant failure of the actuator regardless the working status of other actuators. In this paper, it is further demonstrated that the actuator's error function coefficients will be directly calculated from the healthy input of the examined actuator and all outputs. Hence, the need for structural information is no longer needed. This approach is termed as direct method. Experimental results from a NASA eight bay truss show the successful application of the direct method for isolating and identifying the real-time actuator failure. Further, it is shown that the developed method can be used for real-time sensor failure detection.

• Journal of Aerospace System Engineering
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• v.10 no.2
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• pp.41-45
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• 2016

Statistical data show that a large aircraft(transport category) is struck by lightning once a year or once per 1,000 ~ 20,000 flight time. The protection design for lightning must be applied to the aircraft because an aircraft is developed on condition that it is absolutely struck by lightning. For the proper protection design, we need to understand direct effect and indirect effect of lightning. This paper described the direct effect of lightning on aircraft's structures and systems.

• International Commerce and Information Review
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• v.10 no.2
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• pp.411-432
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• 2008

This study presents the pattern and determinants of intra-industry trade in Korea's machinery and transport equipment industry focusing the influence of foreign direct investment on intra-industry trade. Using an OLS regression model the determinants of intra-industry trade are investigated. Results indicate that a statistically significant negative relationship is found between intra-industry trade and foreign direct investment, and show that intra-industry trade is positively affected by the degree of product differentiation and export structure similarity. Intra-industry trade is also positively associated with the economies of scale, the level of trade barrier, and transportation costs, although this is not statistically significant. The study found strong evidence that the propensity of foreign direct investment toward export specialized industry makes the negative relationship between intra-industry trade and foreign direct investment.

• The Journal of Asian Finance, Economics and Business
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• v.3 no.2
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• pp.5-11
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• 2016

This study investigates the impact of Malaysia's capital market and other key determinants on Economic Growth from the period of 1988 to 2012. The key determinants studied are foreign direct investment and real interest rate. This study also examines the long run and short run relationship between the economic growth and capital market, foreign direct investment, and real interest rate by using bound testing cointegration of Autoregressive Distributed Lag (ARDL) and Error Correction Model (ECM) version of ARDL model. The empirical results of the study suggest that there is long- run cointegration among the capital market, foreign direct investment, real Interest rate and economic growth. The result also suggests that capital market and real interest rate have positive impact on economic growth in the short run and long run. Foreign direct investment does not show positive impact on economic growth in the short run but it does in the long run.

• Journal of Biomedical Engineering Research
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• v.26 no.4
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• pp.251-255
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• 2005

When the extracorporeal shock wave lithotriptor is operated, sounds can be heard. Then that might be a question about the location where the sounds come from. For the purpose of investigating the fact, we identify the location of the sounds radiated using one hydrophone. In order to carry out the experiment, it is needed to obtain direct waves from objects. Therefore, we present an experimental method to reduce reflected waves for obtaining direct waves only. The experimental results show the amplitude of waves can be attenuated about 28dB due to a silicon rubber plate of 8.5mm attached at the bottom. This is a quantified result that can expect to obtain the direct waves using the proposed method. Then, we carried out the experiment for the sound source location. From the experimental results, we can undoubtedly present a fact that the sounds are radiated from the objects to be shot due to shock waves.