• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.968-980
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• 1995

Al/Al$_{2}$O$_{3}$/C hybrid metal matrix composites are fabricated by the direct squeeze infiltration method. From the microstructure of Al/Al$_{2}$O$_{3}$/C composites, uniform distribution of reinforcements and good bondings are found. Optimum processing conditions for preforms and squeeze castings are suggested. Mechanical properties, such as elastic modulus, elongation, 0.2% offset yield strength and ultimate tensile strength are obtained. Through the abrasive were test and wear surface analsis, wear behavior and its mechanism of AC2B aluminum and Al/Al$_{2}$O$_{3}$/C composites can be characterized under various sliding speed conditions. Tensile strenght elongation of Al/Al$_{2}$O$_{3}$/C composites are decreased with increasing the addition of carbon fiber. On the contrary, elastic modulus of Al/Al$_{2}$O$_{3}$/C composites is slightly improved compared with that of the unreinforced matrix alloy. The addition of carbon fiber to al/al$_{2}$O$_{3}$/C composites gives rise to improvement of the wear resistance. Specially, carbon chopped fibers play an important role in interfering sticking between the counter material and metal matirix composites. Al/Al$_{2}$O$_{3}$/C composites are suitable to high speed due to solid lubication of carbon. And wear model of Al/Al$_{2}$O$_{3}$/C composites is suggested by the examination of worn surfaces.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.461-469
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• 2011

In this study, the effect of polyvinyl alcohol (PVA) fiber volume fraction on the pullout behavior of structural synthetic fiber in hybrid structural synthetic fiber and PVA fiber cement composites are presented. Pullout behavior of the hybrid fiber cement composites and structural synthetic fiber were determined by dog-bone bond tests. Test results found that the addition of PVA fiber can effectively enhance the structural synthetic fiber cement based composites pullout behavior, especially in fiber interface toughness. Pullout test results of the structural synthetic fiber showed the interface toughness between structural synthetic fiber and PVA fiber reinforced cement composites increases with the volume fraction of PVA fiber. The microstructural observation confirms the incorporation of PVA fiber can effectively enhance the interface toughness mechanism of structural synthetic fiber and PVA fiber reinforced cement composites.

• Microbiology and Biotechnology Letters
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• v.33 no.4
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• pp.255-259
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• 2005

IgE-dependent histamine-releasing factor (HRF) is found extracellularly to regulate the degranulation process of histamine in mast cells and basophils and known to play a predominant role in the pathogenesis of chronic allergic disease. HRF has been also identified in the intracellular region of the cell. Previously, we reported that HRF interacts with the 3rd cytoplasmic domain of the alpha subunit of Na,K-ATPase. To understand the molecular mechanism of the regulation of Na, K-ATPase activity by HRF, we investigated the interaction between HRF and TPI since TPI was obtained as HRF-interacting protein in HeLa cDNA library, using yeast two hybrid screening. Domain mapping study of the interaction between HRF and TPI revealed that the C-terminal region of the residue 156-249 of TPI is involved in the interaction with HRF. The interaction between HRF and TPI was confirmed by immunoprecipitation from HeLa cell extracts. Our results suggest that TPI is a HRF-binding protein and the interaction between HRF and TPI nay thus affect Na, K-ATPase activity.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.8
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• pp.33-40
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• 2009

This paper presents the high performance control of interior permanent magnet synchronous motor(IPMSM) using space vector(SV) PWM method based on hybrid artificial intelligent(HAI) controller. The HAI controller combines the advantages between adaptive fuzzy control and neural network The SV PWM method is applied to a speed control system of motor in the industry field until now and is feasible to improve harmonic rate of output current, switching frequency and response characteristics. This HAI controller is used instead of conventional PI controller in order to solve problems happening when calculating a reference voltage. The HAI controller improves speed performance by hybrid combination of reference model-based adaptive mechanism method, fuzzy control and neural network. This paper analyzes response characteristics of parameter variation, steady-state and transient-state using proposed HAI controller and this controller compares with conventional fuzzy neural network(FNN) and PI controller. Also, this paper proves validity of HAI controller.

• Journal of KIISE:Information Networking
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• v.36 no.6
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• pp.481-491
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• 2009

In this paper, we proposed a hybrid P2P overlay structure for live media streaming. The proposed structure consists of the mesh overlay organized by peers according to the geographical proximity and similar bandwidth range and the tree overlay formed by the peers for which the stability of participation is approved. The proposed scheme enhances the robustness of tree overlay and the long delay of mesh overlay by intelligently combining the utilization of the tree overlay and the mesh overlay. Furthermore, the peers with a large up-link bandwidth are located near to the media source peer. Therefore, it reduces the height of tree, and as a result, the stream transmission delay. Through simulation, we evaluated the performance of the proposed scheme in terms of scalability and quality of services.

• Journal of Korean Society of Steel Construction
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• v.14 no.3
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• pp.413-421
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• 2002

This study sought to understand the mechanical behavior according to the shape of the connecting part of the hybrid beam. This part is composed of central steel. with the end reinforced by concrete in the experiment of cyclic loading. The experimental result was compared and verified with the ultimate strength formula. Likewise, the composite effect and the effectiveness of seismic capacity and stress transmission were examined. The types of each setup were as follows: main bars by welding type, reinforcing by end-plate type, reinforcing by shear connector type, and shear connector type. Results showed that the reinforcing by end-plate type and the shear connector type had excellent strength and seismic capacity as well as better stress transmission. This was due to the unity between reinforced concrete and the steel's connecting part. However, the experimental result was somehow different from the previously established ultimate strength formula. Thus, a definite ultimate strength formula is required.

• Membrane Journal
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• v.18 no.4
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• pp.354-361
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• 2008

Effects of operational conditions and solution chemistry on permeate flux in a hybrid ozone-ceramic ultra-filtration (UF) membrane system treating natural organic matter (NOM) were investigated. Results showed that the extent of permeate flux decline was higher at higher cross-flow velocity and ozone dosage, but it was higher at lower transmembrane pressure (TMP). The mechanism of fouling mitigation was found to be more dependent upon reaction between ozone and natural organic matter at/near catalytic membrane surface than scouring effect due to ozone gas bubbles. Addition of calcium into model NOM solution at high pH led to significant decline in permeate flux while the calcium effect on permeate flux decline was less pronounced at lower pH. After permeate flux decline during the early stage of filtration, the flux started recovering and approached fully to the initial value of it due to degradation of NOM by catalytic ozonation at ceramic membrane surface in the hybrid ozone-ceramic membrane system.

• Composites Research
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• v.23 no.2
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• pp.10-16
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• 2010

$Al_2O_3$ fiber and SiC particle hybrid metal matrix composites (MMCs) were manufactured by squeeze casting method investigated for their tribological properties. The pin specimens had different ratios of fiber to particle content but their total weight fraction was constant at 20 wt. %. Tribological tests were performed with a pin-on-disk friction and wear tester. The investigation of the dry tribological characteristics of hybrid MMCs were carried out at room temperature and elevated temperature of$100^{\circ}C$ and$150^{\circ}C$. The morphologies of worn surfaces were examined by scanning electron microscope (SEM) to observe tribological characteristics and investigate wear behavior. The results revealed that the wear resistance improved with the content of SiCp increased of the planar random (PR) MMCs at room temperature. At the elevated temperature, it revealed that the wear resistance of normal (N) MMCs was superior to that of the PR-MMCs due to PR-fibers were easily pulled out holistically from the worn surface. Meanwhile, the coefficient of friction decreased with the temperature increasing.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.4
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• pp.193-204
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• 2017

Various 3D-stacked DRAMs have been proposed to overcome the memory wall problem. Hybrid Memory Cube (HMC) is a true 3D-stacked DRAM with stacked DRAM layers on top of a logic layer. The logic die is mainly used to implement a memory controller for HMC, and it is connected through a high speed serial link called SerDes with a host that is either a processor or another HMC. In HMC, the serial link is crucial for both performance and power consumption. Therefore, it is important that the link is configured properly so that the required performance should be satisfied while the power consumption is minimized. In this paper, we propose a HMC system model included the high speed serial link to estimate performance accurately. Since the link modeling strictly follows the link flow control mechanism defined in the HMC spec, the actual HMC performance can be estimated accurately with respect to each link configuration. Various simulations are conducted in order to deduce the correlation between the HMC performance and the link configuration with regard to memory utilization. It is confirmed that there is a strong correlation between the achievable maximum performance of HMC and the link configuration in terms of both bandwidth and latency. Therefore, it is possible to find the best link configuration when the required HMC performance is known in advance, and finding the best configuration will lead to significant power saving while the performance requirement is satisfied.

• Journal of ILASS-Korea
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• v.5 no.2
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• pp.35-42
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• 2000

A number of atomization and droplet breakup models have been developed and used to predict the diesel spray characteristics. Of the many atomization and droplet breakup models based on the breakup mechanism due to aerodynamic liquid and gas interaction, four models classified as mathematical models, such as TAB, modified TAB, DDB, WB and one of the hybrid model based on WB and TAB models were selected for the assessment of prediction ability of diesel spray dynamics. The assessment of these models by using KIVA-II code was performed by comparing with the experimental data of spray tip penetration and sauter mean diameter(SMD) from the literature. It is found that the prediction of spray tip penetration and SMD by the hybrid model was only influenced by the initial parcel number. All the atomization and droplet breakup models considered here was strongly dependent on the grid resolution. Therefore it is important to check the grid resolution to get an acceptable results in selecting the models. At low injection pressure, modified TAB model could only give the good agreement with experimental data of spray tip penetration and both of modified TAB and DDB models were recommendable for the prediction of SMD. At high injection pressure, hybrid model could only give the good agreement with the experimental data of spray tip penetration and the prediction of all of the selected models did not match the experimental data. Spray tip penetration was increased with the increase the $B_1$ and the increase of $B_1$ did not affected the prediction of SMD.