• Journal of Korean Institute of Fire Investigation
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• v.3 no.1
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• pp.12-15
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• 2003

The purpose of this study is to distinguish the causes of broken glass from doors or windows when it is found being originally kept among the remains on the floor in fire site - whether it was broken due to heating or by outer power through test and the properties of the broken plane including the pattern on the plane. Addition to it, the study tries to find characteristics for judging the point and direction of breakdown through the analysis of glass broken by outer power. With two causes assumed - a. breakdown due to heating and b. breakdown due to outer power - 3 pieces of glass plates $(30cm{\times}30cm{\times}5mm)$ for each case were tested, getting the results as following: 1. For the glass broken due to the change of temperature The broken plane is of slow curve and smooth without any pattern. 2. For the broken due to outer power With the impact point as the center, the shows breakdown of radial type and the side shows breakdown of near-perpendicular type. The far the broken piece is from the impact point, the bigger the size is. The broken piece at the impact point is of long triangle type and the two long planes of the triangle shows semi-arc with the center of breakdown point and the other plane shows opposite pattern 3. Change of the pattern and type of the glass due to outer power The pattern and type of the glass due to outer power shows change due to heatihg.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.326-331
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• 2010

Montmorillonite is one of representative inorganic clay particles. As the characteristics of clay particulate matter in aqueous environment determine the efficiencies of wastewater treatment and some industrial operations, it is essential to understand its aquatic behavior in relation with turbidity. The change of electrokinetic potential of montmorillonite suspension shows that it tends to negatively increase as the pH of suspension increases. In addition, it is observed that its potential is around 0mV when the solution pH is ca. 5. The turbidity of suspension is shown to be very low when pH is lower than its isoelectric point. However, the turbidity gradually enhances according to beyond isoelectric point. These results reveal that the correlation between electrokinetic potential and turbidity for clay mineral suspension is peculiar which should be fundamentally considered for systematic treatment of wastewater.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.2
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• pp.113-124
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• 1977

By spplying the ultrasomic wave to the solidifing liquid metal, grain sizes of the ingot are refined and the structures are homogenized. One of the reason is the enhancement of nucleation by ultrasonic vibration. According to the reports on this subject, the uncleating conditions are formed by the increse of melting point which is produced by the high pressure due to caviation. In this paper we study whether the caviations are the orgin of the nucleation and analized whether the nucleating conditions are formed by the increase of melting point or not and also compared the analytical result with the experim nt. We analized the pressure change induced by cllaphsing of cavity and the motion of cavith in oscillating pressure field. And we further analized the variation of melting point with pressure change.

• Kyungpook Mathematical Journal
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• v.46 no.1
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• pp.145-152
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• 2006

In this paper, we study a class of strongly nonlinear implicit complementarity problems in the setting of Hilbert spaces H (not necessarily Hilbert lattices). By using the property of the projection and a suitable change of variables, we establish the equivalence between the strongly nonlinear implicit complementarity problem and the fixed point problem in H. Moreover, we use this equivalence and the fixed point theorem of Boyd and Wong to prove the existence and uniqueness of solutions for the strongly nonlinear implicit complementarity problem in H.

• Journal of Power Electronics
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• v.16 no.1
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• pp.142-152
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• 2016

Common mode voltage (CMV) generation is a major problem in switching power converter fed induction motor drive systems. CMV is the zero sequence voltage generated due to the switching action of power converters. Even a small magnitude of CMV with a high rate of change may circulate large bearing currents which may damage a machine's bearings and shorten its life. There are several methods of controlling CMV. This paper presents 3-level sinusoidal pulse width modulation based techniques to control the magnitude and rate of change of CMV in multilevel AC-DC-AC drive systems. Simulation and experimental investigations have been presented to validate the performance of proposed technique to control CMV in 3-level neutral point clamped inverter based AC-DC-AC system.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.1
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• pp.29-36
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• 2020

In this study, a variable step algorithm is proposed on the basis of the perturb and observe method. The proposed algorithm can follow the maximum power point (MPP) quickly when solar irradiance changes rapidly. The proposed technique uses the voltage change characteristic at the MPP when the environment changes because of insolation or temperature. The MPP is tracked through the voltage control using a variable step method. This method determines the sudden change of solar irradiance by setting the threshold value and operates in fast tracking mode to track the MPP rapidly. When the operation point reaches the MPP, the mode switches to the variable step mode to minimize the steady state error. In addition, the output disturbance is decreased through the optimization of the control method design. The performance of the proposed MPPT algorithm is verified through simulation and experiment.

• Journal of Korean Society for Quality Management
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• v.22 no.3
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• pp.119-123
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• 1994

A frequently recurring question posed by researchers concerns a test of a constant failure rate against the alternative of a failure rate involving a single chang-point. Park (1988) has presented a new test procedure for testing constant failure rate against a bathtub shaped (upside-down bathtub shaped) failure rate. assuming that the proportion of population that fails at or before the change point of failure rate is known. Jeong (1992) has extended Park's test to randomly censored data under the same assumption. In this paper, we have investigated efficiency loss to the presence of censoring.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.202-209
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• 2023

This study aims to analyze the correlation between semiconductor innovation and market dominance in the mobility electric vehicle industry. To this end, the study presentsstrategiesthat provide low-price competitiveness along with high-value creation in the electric vehicle and semiconductor markets. The first change in the era of high interest rates is to overcome the crisis of survival for value. Furthermore, the study acknowledges the ongoing second wave of change as the digital technology's value continues to rise, and companies experience decreased productivity due to rising ESG labor costs. The study analyzed price competitiveness in the context of the increased adoption of electric vehicles and the integration of semiconductor prices, proving that Tesla and Samsung Semiconductor have developed technology to dominate the market, with appropriate low-cost strategies applied as the value of innovation declines.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1802-1806
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• 2006

It is important to consider the effects of land-use changes on surface runoff, stream flow, and groundwater recharge. Expansion of urban areas significantly impacts the environment in terms of ground water recharge, water pollution, and storm water drainage. Increase of impervious area due to urbanization leads to an increase in surface runoff volume, contributes to downstream flooding and a net loss in groundwater recharge. Assessment of the hydrologic impacts or urban land-use change traditionally includes models that evaluate how land use change alters peak runoff rates, and these results are then used in the design of drainage systems. Such methods however do not address the long-term hydrologic impacts of urban land use change and often do not consider how pollutants that wash off from different land uses affect water quality. L-THIA (Long-Term Hydrologic Impact Assessment) is an analysis tool that provides site-specific estimates of changes in runoff, recharge and non point source pollution resulting from past or proposed land-use changes. It gives long-term average annual runoff for a land use configuration, based on climate data for that area. In this study, the environmental and hydrological impact from the urbanized basin had been examined with GIS L-THIA in Korea.

• Clean Technology
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• v.19 no.3
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• pp.233-242
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• 2013

The influences of Ca and Fe based oxides as dechlorination sorbents on the product distribution, boiling point distribution of liquid product, concentration of Cl of the products from the pyrolysis of PVC containing combustible wastes were investigated. With Fe based oxides as the sorbents, the yield of liquid product remarkably decreased whereas the decrease of the boiling point distribution of the liquid product was not noticeable. This phenomenon indicated that Fe based oxides worked as catalysts with weak catalytic activity. With Ca based oxides as the sorbents, the yield of liquid product did not decrease and the boiling point distribution of liquid product did not change significantly, but the dechlorination performance of these was much better than that with Fe based oxides.