• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.542-543
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• 2014

In this paper, an estimation scheme based on an augmented sigma-point Kalman filter to estimate the state of charge (SOC) of the battery is presented, where the battery parameters of the series resistance ($R_o$), diffusion capacitance ($C_1$) and resistance ($R_1$) are also estimated through the recursive least squares (RLS) for better accuracy of the SOC. The effectiveness of the proposed method is verified by simulation results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.7
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• pp.41-48
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• 2009

Grounding impedance depends on the frequency of current flowing into a grounding system lightning in particular has a broad frequency spectrum from some tens of Hz to a few MHz. So the grounding impedance related to transient currents such as lightning should be measured. In this paper, the grounding impedances of vertically-driven ground rods of 10, 30 and 48[m] long are measured and analyzed as functions of the frequency of injected current and the feeding point. As a result, the longer the ground rod is, the lower the steady-state ground resistance is. However the grounding impedance of a vertically-driven ground rod at a high frequency is significantly increased. It is not always true that low grounding impedance follows from a low steady-state ground resistance. It is important to evaluate the high frequency performance of grounding systems for protection against lightning.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.10 no.1
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• pp.55-67
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• 2015

This study examines innovation resistance to smart learning, an emerging innovative technology for startups and corporate ventures in the education market. The study explores whether the relative advantage, compatibility and complexity of an innovation, attitudes toward existing learning method(s), and perceived self-efficacy significantly affect innovation resistance. Additionally, the effects of such innovation resistance on future use and the moderating effect according to demographic characteristics are examined. The results of the analysis using a structural equation model showed that all the factors considered (except relative advantage) affects innovation resistance, innovation resistance significantly affects intention to use.

• Journal of the Korean Society for Heat Treatment
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• v.29 no.4
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• pp.168-175
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• 2016

Influence of trace amount of Ca addition on the corrosion resistance was comparatively investigated in solutionized Mg-4%Zn and Mg-4%Zn-0.1%Ca alloys. In as-cast state, the alloys were characterized by primary ${\alpha}-(Mg)$ dendrite with MgZn intermetallic compound particles. After solution-treatment, both alloys consisted of single ${\alpha}-(Mg)$ phase by dissolution of the compound particles into the matrix. It was found from the immersion and electrochemical corrosion tests that the Mg-4%Zn alloy had better corrosion resistance than the Mg-4%Zn-0.1%Ca alloy. Morphological and compositional analyses on the surface corrosion products indicate that the incorporation of Ca oxide with low PBR value into the surface corrosion products would be responsible for the decreased corrosion resistance of the Ca-containing alloy.

• Journal of the Korean Society of Safety
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• v.34 no.5
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• pp.22-30
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• 2019

In 2018, overload, overcurrent, insulation aging, and a contact failure caused 659 electric fires. There is almost no failure of electrical socket outlets during their manufacturing or installation period. After several months or several years, overload or overcurrent of electrical socket outlets leads to a contact failure or short circuit which causes an electric fire. Therefore, this paper analyzed for thermal characteristics based on a current value and the change in insulation resistance along with a temperature rise caused by electrical socket outlets and the state of laboratory use in workplaces. As a results, regarding the thermal characteristics based on the current value of each installation year, a temperature increase was related to a current value, an installation year, and whether the contact unit is corroded. Insulation resistance began to decrease when a temperature increased to a certain level. With a lapse of installation year, the temperature at which insulation resistance began to decrease was lowered. This paper can be applicable for the survey data about electrical socket outlet induced fire accidents and management guidelines.

• International Journal of High-Rise Buildings
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• v.7 no.4
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• pp.287-298
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• 2018

High strength steels have been widely applied in recent years due to high strength and good working performance. When subjected to fire conditions, the strength and elastic modulus of high strength steels deteriorate significantly and hence the load bearing capacity of structures reduces at elevated temperatures. The reduction factors of mechanical properties of high strength steels are quite different from mild steels. Therefore, the fire design methods deduced from mild steel structures are not applicable to high strength steel structures. In recent ten years, the first author of this paper has carried out a lot of fundamental research on fire behavior of high strength steels and structures. Summary of these research is presented in this paper, including mechanical properties of high strength steels at elevated temperature and after fire exposure, creep response of high strength steels at elevated temperature, residual stresses of welded high strength steel member after fire exposure, fire resistance of high strength steel columns, fire resistance of high strength steel beams, local buckling of high strength steel members, and residual strength of high strength steel columns after fire exposure. The results show that the mechanical properties of high strength steel in fire condition and the corresponding fire resistance of high strength steel structures are different from those of mild steel and structures, and the fire design methods recommended in current design codes are not applicable to high strength steel structures.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.5
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• pp.418-426
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• 2016

This paper analyzes the effect of resistance error to the performance of sensorless drive system of surface-mounted permanent magnet synchronous machine (SMPMSM) based on the back-EMF observer. The analysis shows that the bandwidth of the entire sensorless drive system decreased in the low-speed region when using smaller resistance value than the actual one in the back-EMF observer. Even if the back-EMF observer invokes estimation error, the entire sensorless drive system does not make any steady-state position error. These characteristics may have positive effects such as extension of the low speed limit that goes further down in the sensorless drive. The validity of the analysis is verified by the experimental setup comprising the MG set.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.12 no.1
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• pp.45-53
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• 2006

Thermal insulation is used in a variety of applications to protect temperature sensitive products from thermal damage. Several factors affect the performance of insulation packages. Among these factors, the thermal resistance of the insulating wall is the most important factor to determine the performance of the insulating package. In many cases, insulating wall consists of multi-layered structure and the heat transfer through this structure is a very complex process. In this study, an one-dimensional mathematical model, which includes all of the heat transfer principles covering conduction, convection and radiation in multi-layered structure, were developed. Based on this model, several heat transfer phenomena occurred in the air space between the layer of the insulating wall were investigated. From the simulation results, it was observed that the heat transfer through the air space between the layer were dominated by conduction and radiation and the low emissivity of the surface of each solid layer of the wall can dramatically increase the thermal resistance of the wall. For practical use, an equation was derived for the calculation of the thermal resistance of a multi-layered wall.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.988-993
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• 2004

This paper considers corrosion problems in the bolt connection of weathering steel box girder bridge using the external electric type corrosion resistance method which resisted to local corrosion in coated steel surface with contacted air. The weathering steel was created a rust itself in the passive state. but a coated box girder type was easily dew form could be made galvanic cell that accelerated corrosion. so that it was ruled by protection coat with some paint. Therefore, it needed that can be applied the external electric type corrosion resistance method in coated surface. As a result of the test of polarization amount had measured that the weathering steel was higher currents than the general steel by about $5\~10\%$. Therefore. an external electric type corrosion resistance method can be used to protect local corrosion in the coated bolt connection of weathering steel box girders effectively.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.438-441
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• 1998

In this paper, we proposes an adaptive flux observer to estimate initial values of rotor fluxes and unknown rotor resistance. The error system between the model of induction motor and a proposed observer is devided as a fast subsystem and a slow one by a singular perturbation system. The fast subsystem is exponentially convergent on a boundary-layer. And the overall error system is reduced to a quasi-steady-state system. The adaptive law for an unknown rotor resistance is designed to stabilize the approximate error system. As computer simulation results show, the proposed adaptive flux observer estimates fast initial values of rotor fluxes and unknown rotor resistance.