• Interaction and multiscale mechanics
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• v.4 no.4
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• pp.247-255
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• 2011

Understanding the structural stability of carbon nanostructure under heat treatment is critical for tailoring the thermal properties of carbon-based material at small length scales. We investigate the heat resistance of the single carbon nanoball ($C_{60}$) and carbon nanoonions ($C_{20}@C_{80}$, $C_{20}@C_{80}@C_{180}$, $C_{20}@C_{80}@C_{180}C_{320}$) by performing molecular dynamics simulations. An empirical many-body potential function, Tersoff potential, for carbon is employed to calculate the interaction force among carbon atoms. Simulation results shows that carbon nanoonions are less resistive against heat treatment than single carbon nanoballs. Single carbon nanoballs such $C_{60}$ can resist heat treatment up to 5600 K, however, carbon nanoonions break down after 5100 K. This intriguing result offers insights into understanding the thermal-mechanical coupling phenomena of nanodevices and the complex process of fullerenes' formation.

• Journal of Hydrogen and New Energy
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• v.6 no.2
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• pp.85-90
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• 1995

Activation behavior, hydriding rate and disintegration were tested for hydrogen storage alloy particles fixed in an adhesive after treating with inorganic solution. Commertial adhesive as a binder was used. Chemical-treated particles showed the best characteristics for activation and a little effect of prevention the break down of the powders themselves after several repeated operations. Furthermore activation characteristics were found to show a similar trend to chemical-treated powders even in the fixed one with an adhesive, except for a slight decrease in reaction velocity.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.105-108
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• 2002

Polyimide-epoxysilane (coupling agent) composites were reacted with oligomeric PDMS, a condensation product of difunctional silane, by a sol-gel process and were then dried into films. And then, the surface, mechanical, and electric properties were measured. The study showed that PDMS existed in the polyimlde matrix by the use of FT-IR. In the mechanical properties, the maximum elongation and toughness was increased in the polyimide with silane-groups. But the maximum tensile strength was slightly decreased. And the intensive dispersion of the silane-groups on the surface of polyimide was ascertained through XPS measurement. In the electric properties, AC break down voltage was increased by increasing the amount of difunctional silane. This experiment showed that PDMS added polyimide had better mechanical and electric properties than classical materials.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.67-70
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• 2000

In a distributed real-time system(DRTS), testing and debugging are difficult and critical procedures since they implies several problems like probe effects, nondeterminism, and complex communication patterns. In this paper, we describe the design and implementation of a real-time monitor for ARM processors which are frequently used for embedded applications. The focus of design is to help users debug real-time programs while minimizing the probe effect. Our monitor provides cross debugging features like down-loading from host, break-point based debugging features, and watch-point debugging features for real-time applications. We developed the debugger for ARM processor and debugger has been used for kernel program.

• The Korean Journal of Food And Nutrition
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• v.22 no.2
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• pp.229-237
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• 2009

Physical, textural and sensory properties of Seolgiddeok prepared with different amounts of broccoli(Brassica oleracea var. italica Plen.) powder were investigated during 3 days of storage. Moisture content decreased gradually during storage and was less in broccoli powder-amended samples. The color L value decreased significantly with increasing broccoli powder, whereas both redness and yellowness increased. Texture analyses revealed that hardness, chewiness, gumminess, adhesiveness and fracturability of Seolgiddeok tended to decrease in proportion to the amount of broccoli powder in the formula. Seolgiddeok gelatinization was investigated using amylographing. Break down and setback were low in broccoli powder Seolgiddeok. Sensory evaluations revealed that, Seolgiddeok prepared with broccoli powder was superior in flavor, chewiness, softness to unamended samples. Seolgiddeok prepared with 3% broccoli powder showed the highest overall acceptability score. Use of broccoli powder in Seolgiddeok preparation improves sensory characteristics and delays retrogradation.

• 열병합발전
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• s.30
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• pp.21-25
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• 2002

According to recent Korea Electric Power Company report, yearly distribution line brass cramp bolts failure summed up to 4,400 cases emerging as one of main local break-down causes. Naturally, the need for the investigation was proposed To determine the root cause of the cramp bolt failures, mechanical and metallurgical investigation were performed for 90 samples which collected from various sites. For the understanding of the geometric characteristics, stress distribution was evaluated by CAE program and proof load of each bolts was tested. The SEM&EDS was used for metallurgical investigation. Through the investigation, the root causes of failures were confirmed. All damaged bolts showed intergrannular fracture mode and the all fractured bolt showed ß phase morphology contrast to the a&ß mixture morphology of the non-damaged samples. Additionally, EDS analysis confirmed the existence of lead rich layer on grain boundaries.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.550-552
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• 2000

Treeing inhibitors are added in XLPE matrix to investigate the effect on electrical properties of XLPE. The treeing inhibitors are barbituric acid, 4- (4-Nitrophenylazo) resorcinol and 4-(4-Nitrophenylazo) naphthol. Added amount of each treeing inhibitors were varied form 0phr to 2.0phr. In order to know the changes of electrical properties, break down strength, $tan{\delta}$, and ${\varepsilon}_r$ were measured. Experimental results showed that electrical properties of each sample was slightly changed by amount of additives.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.285-286
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• 2008

The Gas Circuit Breaker for the Main Transformer of voltage, 154kV at the ist Hapcheon hydraulic power station, break down by the falling of a thunderbolt from now, let's improve the efficiency on the maintenance of generating equipment by studying about the cause and the method for this problem.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2001.10a
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• pp.199-202
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• 2001

This article deals with stochastic reliability systems that include a repair facility and unreliable machines: the main facility of working and an auxiliary facility of "super-reserve" machines. The number of super-reserve machines are random number with a arbitrarily distribution and working machines break down exponentially. Defective machines line up for repair, whose durations are arbitrarily distributed. Refurbished machines return to the main facility. If the main facility is restored to its original quantity, the repair facility leaves on routine maintenance until all of super-reserve machines are exhausted. Then, the busy period is regenerated. The whole system also falls into the category of closed queues, with more options than those of basic models. The techniques include two-variate Markov and semi-regenerative processes, and a duality principle, to find the probability distribution of the number of intact machines. Explicit formulas obtained demonstrate a relatively effortless use of functionals of the main stochastic characteristics (such as expenses due to repair, maintenance, waiting, and rewards for higher reliability) and optimization of their objective function. Applications include computer networking, human resources, and manufacturing processes.

• Transactions of Materials Processing
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• v.12 no.4
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• pp.408-413
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• 2003

Dies may have to be replaced for a number of reasons, such as changes in dimensions due to die wear or plastic deformation, deterioration of the surface finish, break down of lubrication and cracking or breakage. In this paper, die cooling methods have been suggested to improve die service life considering die wear and plastic deformation in hot forging process. The yield strength of die decreases at higher temperatures and is dependent on hardness. Also, to evaluate die life due to wear, modified Archard's wear model has been proposed by considering the thermal softening of die expressed in terms of the main tempering curve. It was found that the use of die with cooling hole was more effective than that of direct cooling method to increase the die service life for spindle component.