• Fire Science and Engineering
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• v.20 no.1 s.61
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• pp.77-82
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• 2006

This study defined engineering mechanism and compensation method to establish reference pressure of smoke control zone with atmospheric pressure that is compensated for temperature. The reliable controller of integration smoke control was developed by establishing the specifications, algorithms and constructing engineering data. The development of controller for integration smoke control can cut down number of processes, manufacturing and installation cost by removing pressure measurement pipe established separately for non smoke control zone, and improve the accuracy of pressure differential by embedding pressure measurement ports for non smoke control zone. More correct and reliable pressure differentials can be obtained by the central control from controller of integration smoke control rather than the existent individual control. This will provide the basics and the flexibility to the integral smoke control system and accordingly improve the performance of disaster prevention.

• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.315-321
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• 1984

The electrochemical reduction of 0,0-dimethyl-0-(3-methyl-4 -nitrophenyl)-phosphorothioate ($Sumithion^{(R)}$) in acetonitrile solution has been studied by direct current (DC), differential pulse (DP) polarography and cyclic voltammetry methods. The irreversible electron-transfer chemical reaction (EC) mechanism of Sumithion proceeds by six electron-transfer to form radical and reduction of three-step which undergoes single bond of the phosphorus atom & phenoxy group by electron-transfer and protonation cleaved to give p-hydroxyamino-m-cresol and dimethylthiophosphonate as major product.

• Molecular & Cellular Toxicology
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• v.4 no.4
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• pp.267-277
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• 2008

Benzene and ethylbenzene (BE), the volatile organic compounds (VOCs) are common constituents of cleaning and degreasing agents, paints, pesticides, personal care products, gasoline and solvents. VOCs are evaporated at room temperature and most of them exhibit acute and chronic toxicity to human. Chronic exposure of benzene is responsible for myeloid leukemia and also ethylbenzene is also recognized as a possible carcinogen. To evaluate the BE effect on human, whole human genome 35 K oligonucleotide microarray were screened for the identification of the differential expression profiling. We identified 280 up-regulated and 201 down-regulated genes changed by more than 1.5 fold by BE exposure. Functional analysis was carried out by using DAVID bioinformatics software. Clustering of these differentially expressed genes were associated with immune response, cytokine-cytokine receptor interaction, toll-like signaling pathway, small cell lung cancer, immune response, apoptosis, p53 signaling pathway and MAPKKK cascade possibly constituting alternative or subordinate pathways of hematotoxicity and immune toxicity. Gene ontology analysis methods including biological process, cellular components, molecular function and KEGG pathway thus provide a fundamental basis of the molecular pathways through BEs exposure in human lymphoma cells. This may provides a valuable information to do further analysis to explore the mechanism of BE induced hematotoxicity.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1993.11a
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• pp.2-2
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• 1993

The present status of the thennomechanica1 evaluation of functionally gradient materials(FGMs) for space plane application was reviewed, in which research activities and the cooperation of the national project team organized to study FGM science were demonstrated. The project team was divided into three working groups; de singing, processing and evaluation, each of which had their own tasks in the project cooperation. The testings details of the various thennomechanical tests for the FGM samples fabricated by the processing groups were described, along with their corresponding heating conditions of the real environments in the space plane application. For small-sized samples, laser beam heating test and burner heating test were well applied to study the heat shielding and heat resisting properties. Arc-heated wind tunnel test and high temperature!high velocity gas flow test were used for large-sized panel assemblies having cooling structures. The criteria for the evaluation of the heat shielding and heat resisting properties of the FGMs, as well as a crack activation mechanism in their differential temperature heating, were proposed on the basis of the observation in the burner heating test.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.225-231
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• 2004

Scroll compressor has been used extensively for refrigeration since the early 1980's for its improved efficiency, greater reliability, smoother operation, lower noise and vibration. And also, nowadays, the scroll mechanism is used for expander even though in niche market yet. But scroll expander has not been used for high-temperature and high-pressure gas, because the continuous expansion of the gas causes a wide range of temperature distribution over the whole scroll wrap that leads to differential thermal expansion of scroll elements, which results in system vibrations, noise and efficiency losses. For the scroll expander to produce power more efficiently, all of radial and radial clearances between scroll wrap must be the same. In order to reduce differential thermal expansion in addition to improvements in thermal efficiency and specific power, we propose a scroll expander with heating structure. Heat-pipe heating structure is considered as the most effective method to heat the scroll expander at a uniform temperature. This paper includes some results of preliminary study of the scroll expander with heating structure and proposals of their systems for power generation and refrigeration.

• ETRI Journal
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• v.33 no.5
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• pp.780-790
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• 2011

This paper presents an efficient differential power analysis (DPA) countermeasure for the $Eta_T$ pairing algorithm over GF($2^n$). The proposed algorithm is based on a random value addition (RVA) mechanism. An RVA-based DPA countermeasure for the $Eta_T$ pairing computation over GF($3^n$) was proposed in 2008. This paper examines the security of this RVA-based DPA countermeasure and defines the design principles for making the countermeasure more secure. Finally, the paper proposes an efficient RVA-based DPA countermeasure for the secure computation of the $Eta_T$ pairing over GF($2^n$). The proposed countermeasure not only overcomes the security flaws in the previous RVAbased method but also exhibits the enhanced performance. Actually, on the 8-bit ATmega128L and 16-bit MSP430 processors, the proposed method can achieve almost 39% and 43% of performance improvements, respectively, compared with the best-known countermeasure.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.195-202
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• 1988

An electrochemical reduction on the 3-phenyl-4-nitrosydnone in acetonitrile solution has been studied by direct current, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. Before the cleavage of phenyl-N single bond a irreversible electron transfer-chemical reaction(EC) mechanism of nitro functional group proceeded to form amino (or-hydroxylamino) group by multielectron transfer which is followed to give phenyl hydrazine by single electron transfer-chemical reaction at the 2nd and 3rd irreversible reduction wave of high negative potential region. The cathodic half-wave potentials shown to be shift negative due to inhibitory effect of cetyl-trimethyl ammonium bromide micelle while reversible anodic peaks on the 2nd and 3rd reduction waves in the presence of NaLS at high negative potential region.

• Archives of Pharmacal Research
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• v.25 no.4
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• pp.397-415
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• 2002

This paper deals with a crucial mechanism for interaction of basic drugs and cardiac glycosides at the hepatic uptake level. Available literature data is provided and new material is presented to picture the differential transport inhibition of bulky (type2) cationic drugs by a number of cardiac glycosides in rat liver. It is shown that the so called organic anion transporting peptide 2 (oatp2) is the likely interaction site: differential inhibition patterns as observed in oocytes expressing oatp2, could be clearly identified also in isolated rat hepatocytes, isolated perfused rat liver and the rat in vivo. The anticipation of transport interactions at the hepatic clearance level should be based on data on the relative affinities of interacting substrates for the transport systems involved along with knowledge on the pharmacokinetics of these agents as well as the chosen dose regimen in the studied species. This review highlights the importance of multispecific tranporter systems such as OATP, accommodating a broad spectrum of organic compounds of various charge, implying potential transport interactions that can affect body distribution and organ clearance.

• Tribology and Lubricants
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• v.35 no.1
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• pp.71-76
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• 2019

The differential planetary gear reducer as a main component of the concrete mixer driving mechanism requires a strong torque to mix concrete compounds. As this component is currently dependent on imports, it is necessary to develop it by conducting a study on vibration analysis and the resonance problem. The noise and vibration of a concrete mixer reducer increase owing to the transmission error of planetary gears, and the damage of components occurs owing to the problems in design and production. In this study, the tooth-passing frequency is calculated to evaluate the noise and vibration of a mixer reducer, and a fast Fourier transform (FFT) analysis is conducted through a vibration test using an acceleration sensor. The vibration of the reducer is measured at three points of input and output of the shaft and planetary gear housing with fixed and variable revolutions per minute. The operating conditions of gears and bearings are evaluated by performing the FFT analysis, and the resonance problem is verified. The results show that No. 1 pinion and ring gears revolve disproportionately. The amplitude values appear high, and the wear of tooth faces occur in tooth-passing frequencies and harmonic components of No. 1 and No. 2 pinion-ring gears. Therefore, we conclude that design changes in the reducer and a correction of tooth profiles are required.

• Smart Structures and Systems
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• v.24 no.3
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• pp.361-377
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• 2019

The stiffness of shape memory alloy (SMA) spring while in actuation is represented by an empirical model that is derived from the logistic differential equation. This model correlates the stiffness to the alloy temperature and the functionality of SMA spring as active variable stiffness actuator (VSA) is analyzed based on factors that are the input conditions (activation current, duty cycle and excitation frequency) and operating conditions (pre-stress and mechanical connection). The model parameters are estimated by adopting the nonlinear least square method, henceforth, the model is validated experimentally. The average correlation factor of 0.95 between the model response and experimental results validates the proposed model. In furtherance, the justification is augmented from the comparison with existing stiffness models (logistic curve model and polynomial model). The important distinction from several observations regarding the comparison of the model prediction with the experimental states that it is more superior, flexible and adaptable than the existing. The nature of stiffness variation in the SMA spring is assessed also from the Dynamic Mechanical Thermal Analysis (DMTA), which as well proves the proposal. This model advances the ability to use SMA integrated mechanism for enhanced variable stiffness actuation. The investigation proves that the stiffness of SMA spring may be altered under controlled conditions.