• Journal of the Korean Society of Safety
• /
• v.11 no.1
• /
• pp.53-59
• /
• 1996

To protect the damages or the disasters caused by overheating of industrial electric equipments or electric home appliances, a temperature sensitive thermal fuse is generally used in those equipments. Thermal fuses cutoff the current flow when the temperature of the electric equipments are abnormally overheated and over the certain temperature. Therefore thermal fuse is one of the most important elements in the sense of safety. Thermal fuses are classified into two types according to thermally sensitive materials, a low temperature melting alloy and an organic chemical compound. Domestic products of thermal fuses are now only with an organic chemical compound. Domestic products tested by using cutoff test and aging test etc. are satisfied UL specification. It's shown that the accuracy and the precision of the domestic products are as good as those of the overseas products obtained UL mark. However, some of domestic products show the reclosing problem which is mainly related the safety. This problem should be solved to make the reliable thermal fuses. In this paper, our Interest is to find out the causes of reclosing. In the comparison between thermally sensitive materials occurred reclosing and those occurred no reclosing, the test effects show that the characteristics of emitting heat and absorbing heat are different.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.24 no.3
• /
• pp.208-214
• /
• 2011

In this thesis, the partial discharge according to applied voltage and variations of cross-sectional area and length of the conductor related to general condition for using cable was measured in order to study degradation diagnosis for 2-Core cable of the PVC insulator used in industrial fields for other safety installations. Also the thermal degradation conditions under various installation circumstances of cables were studied by assuming degradation conditions with each different degradation rate (50%, 67%, 100%) such as variation in degradated temperature, thermal exposure time, normal state, partially degradated state and overall degradated state for thermal degradation diagnosis. The quantity of electric discharge (V-Q) according to applied voltage was measured for measurement of inception voltage and extinction voltage. The quantity of electric discharge and the number of electric discharge (Q-N) were measured with applied voltage kept constantly. In addition, pictures were taken using SEM (scanning electron microscope) to compare the surface of external insulator to degradated state of internal insulator according to thermal degradation temperature and also compare the surface of external insulator to degradated surface state of internal insulator according exposure time of cables to thermal stress.

• Journal of Energy Engineering
• /
• v.20 no.1
• /
• pp.1-7
• /
• 2011

The performance and life-cycle costs of electric vehicle(EV) and hybrid electric vehicle(HEV) depend inherently on battery packs. Temperature uniformity in a pack is an important factor for obtaining optimum performance for an EV or HEV battery pack, because uneven temperature distribution in a pack leads to electrically unbalanced battery cells and reduced pack performance. In this work, a three-dimensional modeling was carried out to investigate the effects of operating conditions on the thermal behavior of a lithium-ion battery pack for an EV or HEV application. Thermal conductivities of various compartments of the battery were estimated based on the equivalent network of parallel/series thermal resistances of battery components. Heat generation rate in a cell was calculated using the modeling results of the potential and current density distributions of a battery cell.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.4
• /
• pp.120-127
• /
• 2013

Hybrid electric vehicles have applied electric parts for saving fuel consumption and reducing levels of environmental pollution. Electrification of automobiles is indispensable for entering into global market because of enhanced environment restriction. ISG (Integrated Starter & Generator) system is one of main electric parts and can improve fuel efficiency more than other components by using Idle Stop & Go function and regenerative braking system. However, if ISG motor and inverter work under the continuously high load condition, it will make them the decrease of performance and durability. So the ISG motor and inverter need to properly design the cooling system of them. In this study, we suggested the enhancement points by modifying the thermal design of ISG motor and then confirmed the improvement of the cooling performance.

• Transactions on Electrical and Electronic Materials
• /
• v.12 no.3
• /
• pp.98-101
• /
• 2011

A 10 nm nano-silica was introduced to a conventional 3 ${\mu}M$ micro-silica composite to develop an eco-friendly new electric insulation material for heavy electric equipment. Thermal and mechanical properties, such as glass transition temperature (Tg), dynamic mechanical analysis, tensile and flexural strength, were studied. The mechanical results were estimated by comparing scale and shape parameters in Weibull statistical analysis. The thermal and mechanical properties of conventional epoxy/micro-silica composite were improved by the addition of nano-silica. This was due to the increment of the compaction via the even dispersion of the nano-silica among the micro-silica particles.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.39 no.2 s.120
• /
• pp.45-53
• /
• 2007

When micro flute corrugated paperboards are used for food packaging, they necessarily need to meet the requirements for the distribution, transportation, and storage of food. The requirements could vary ac-cording to the contents in the packaging boxes. Microflute corrugated packaging paperboard for hot foods such as just-made coffee and hamburger requires to have a decent resistance property against high temperature. Along with a recent trend for small-quantity-multi-item upgraded packaging, semiconductor products and consumer-electronic appliances become to be packed using the environmental friendly micro flute corrugated paperboard. In this case, the electric resistance property of the microflute corrugated paperboard becomes important. This study was carried out to investigate on the thermal conductivity and electric resistance properties of micro flute corrugated paperboard.

• Advances in materials Research
• /
• v.8 no.3
• /
• pp.237-257
• /
• 2019

The present article researches large-amplitude thermal free vibration characteristics of nonlocal two-phase piezo-magnetic nano-size beams having geometric imperfections by considering piezoelectric reinforcement scheme. The piezoelectric reinforcement can cause an enhanced vibration behavior of smart nanobeams under magnetic field. All previous studies on vibrations of piezoelectric-magnetic nano-size beams ignore the influences of geometric imperfections which are crucial since a nanobeam is not always ideal or perfect. Nonlinear governing equations of a smart nanobeam are derived based on classical beam theory and an analytical trend is provided to obtain nonlinear vibration frequency. This research shows that changing the volume fraction of piezoelectric phase in the material has a great influence on vibration behavior of smart nanobeam under electric and magnetic fields. Also, it can be seen that nonlinear vibration behaviors of smart nanobeam is dependent on the magnitude of exerted electric voltage, magnetic imperfection amplitude and substrate constants.

• KEPCO Journal on Electric Power and Energy
• /
• v.6 no.1
• /
• pp.41-47
• /
• 2020

The contribution of damage mechanisms to failure of steam turbine casing made of Cr-Mo-V steel was investigated. Creep-fatigue interaction on the HP side corner of turbine casing was revealed as the root cause of the catastrophic failure performed by metallurgical analysis. The steady-state pressure and transient thermal stress were analyzed based on the actual operating condition of the thermal plant. Damage of creep-fatigue interaction to crack initiation was evaluated with multiaxial effects. The contribution ratio of creep and fatigue to the crack initiation was estimated to 3:1. Temporary geometrical correct action with repair weld was executed. For long-term operation, design improvement of casing equipment for creep resistance should be needed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.5
• /
• pp.29-34
• /
• 2014

Cooling the in-wheel motor in electric vehicles is critical to its performance and durability. In this study, thermal flow analysis was conducted by evaluating the thermal performance of two conventional cooling models for in-wheel motors under the continuous rating base speed condition. For conventional model #1, in which cooling oil was stagnant in the lower end of the motor, the maximum temperature of the coil was $221.7^{\circ}C$; for conventional model #2, in which cooling oil was circulated through the exit and entrance of the housing and jig, the maximum temperature of the coil was $155.4^{\circ}C$. Therefore, both models proved unsuitable for in-wheel motors since the motor control specifications limited the maximum temperature to $150^{\circ}C$.

• Proceedings of the KIEE Conference
• /
• 2008.05a
• /
• pp.183-184
• /
• 2008

The aim of this study is to find out the effects of thermal aging condition on dielectric strength and degree of crtstallinity of XLPE insulation. Thermal properties of XLPE insulation were investigated by DSC(differential scanning calorimetry) and dielectric strength were analyzed using AC BDV tester. Aging of XLPE samples were conducted through different four conditions. The degree of crtstallinity and AC BDV were changed by thermal history. From these results, it can be suggested that DSC and AC BDV test are suitable for diagnostic method of extra high voltage XLPE cable.