• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.147-158
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• 1997

This paper presents the analysis technique and procedure of main engine components-cylinder block, cylinder liners, gasket and cylinder head-using the finite element method, which aims to assess mainly the potential of lower oil consumption in a view point of engine design and to decide subsequently the accuracy of engine design which was done. The F.E. model of an engine section consisting of one whole cylinder and two adjacent half cylinders is used, whereby the crankcase is cut off at the block bottom deck. By means of a 3-dimensional F.E. model-including cylinder block, liners, gasket, cylinder head, bolts and valve seat rings as separate parts a linear analysis of deformations and stresses was performed for three different loading conditions;assembly, thermal and gas loads. For the analysis of thermal boundary conditions also the temperature field had to be evaluated in a subsequent step.

• Nuclear Engineering and Technology
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• v.35 no.1
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• pp.35-44
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• 2003

The neutron induced nuclear data for Eu-153, Gd-155 and Cd-157 are calculated and evaluated in the high energy region. The evaluation procedure for deformed nuclei is setup by using Ecis-Empire codes. The energy dependent optical model potential parameters are searched based on the recent experimental data and applied up to 20 MeV. Optical model, full featured Hauser-Feshbach model and multistep direct and multistep compound model are used in the calculation. The direct-semidirect capture model and the direct coupled-channels contribution to discrete levels are introduced to improve the capture and inelastic scattering cross sections. The theoretically calculated cross sections are compared with the experimental data and the evaluated files. The model-calculated total and capture cross sections are in good agreement with the reference experimental data. The evaluated cross section results are compiled to ENDF-6 format and are expected to improve the ENDF/B-Vl.

• Journal of the Korea Society of Computer and Information
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• v.21 no.9
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• pp.11-18
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• 2016

In this paper, we propose a gas classification method using combined features for an electronic nose system that performs well even when some loss occurs in measuring data samples. We first divide the entire measurement for a data sample into three local sections, which are the stabilization, exposure, and purge; local features are then extracted from each section. Based on the discrimination analysis, measurements of the discriminative information amounts are taken. Subsequently, the local features that have a large amount of discriminative information are chosen to compose the combined features together with the global features that extracted from the entire measurement section of the data sample. The experimental results show that the combined features by the proposed method gives better classification performance for a variety of volatile organic compound data than the other feature types, especially when there is data loss.

• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.145-156
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• 2020

There are separate merits and demerits to wood and steel. The combination of wood and steel as a compound section is able to improve the properties of both and ultimately increase their final bearing capacity. The composite cross-section made of steel and wood has higher hardness while showing more ductility and the local buckling of steel is delayed or completely prevented. The purpose of this study is to investigate the behavior of composite columns enclosed in wooden logs and the hollow sections of steel that will be examined in a laboratory environment under the axial load to determine the final bearing capacity and sample deformation. In terms of methodology, steel sheet and carbon fiber reinforced polymer sheet (FRP) are tested to construct hollow rectangular sections and reinforce timber. Besides, the method of connecting hollow sections and timber including glue and screw has been also investigated. As a result, timber lumber enclosed with carbon fiber-reinforced polymer sheets in which fibers are horizontally located at 90° are more resistant with better ductility.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.5
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• pp.442-449
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• 2009

A two-dimensional cross-section analysis program based on the finite element method has been developed for composite blades with solid, thin-walled and compound cross-sections. The weighted-modulus method is introduced to determine the laminated composite material properties. The shear center and the torsion constant for any given section are calculated according to the Trefftz' definition and the St. Venant torsion theory, respectively. The singular value problem of cross-section stiffness properties faced during the section analysis has been solved by performing an eigenvalue analysis to remove the rigid body mode. Numerical results showing the accuracy of the program obtained for stiffness, offset and inertia properties are compared in this analysis. The current analysis results are validated with those obtained by commercial software and published data available in the literature and a good correlation has generally been achieved through a series of validation study.

• ETRI Journal
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• v.18 no.1
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• pp.15-27
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• 1996

The effects of $Nd_2O_3$ and $TiO_2$ addition on the microstructures and microwave dielectic properties of $BaO-Nd_2O_3-TiO_2$ system were investigated. $BaNd_2Ti_4O_{12}$ or $BaNd_2Ti_{5}O_{14}$ phases were observed for compositions based on BaO/$Nd_2O_3$ = 1 ratio. The compositions deviated from $BaO/Nd_2O_3=1$ ratio were composed of major phases of $BaNd_2Ti_4O_{12}$ or $BaNd_2Ti_5O_{14}$, and the compound of $Nd_2O_3$ and $TiO_2(Nd_2Ti_2O_7)$ or that of BaO and $TiO_2(BaTi_4O_9)$. The microstructure of ceramic with $BaO{\cdot}Nd_2O_3{\cdot}4TiO_2$ composition varied from spherical grains to needlelike grains with increasing sintering temperature. With increasing $Nd_2O_3$, the optimum sintering temperature with maximum density increased, and the dielectric constant(${\varepsilon}_r$) and quality factor(Q) decreased due to the formation of secondary phases. With increasing $TiO_2$, the optimum sintering temperature and the dielectric constant decreased with increased Q value. And the temperature coefficient of resonant frequency, ${\tau}_f$ shifted toward positive direction. The dielectric ceramics with $BaO/Nd_2O_3=1$ showed Q values of above 2000 and dielectric constants of above 80 at 3GHz.

• Korean Journal of Materials Research
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• v.31 no.1
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• pp.38-42
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• 2021

In this study, high temperature wetting analysis and AZ80/Ti interfacial structure observation are performed for the mixture of AZ80 and Ti, and the effect of Al on wetting in Mg alloy is examined. Both molten AZ80 and pure Mg have excellent wettability because the wet angle between molten droplets and the Ti substrate is about 10° from initial contact. Wetting angle decreases with time, and wetting phenomenon continues between droplets and substrate; the change in wetting angle does not show a significant difference when comparing AZ80-Ti and Mg-Ti. As a result of XRD of the lower surface of the AZ80-Ti sample, in addition to the Ti peak of the substrate, the peak of TiAl3, which is a Ti-Al intermetallic compound, is confirmed, and TiAl3 is generated in the Al enrichment region of the Ti substrate surface. EDS analysis is performed on the droplet tip portion of the sample section in which pure Mg droplets are dropped on the Ti substrate. Concentration of oxygen by the natural oxide film is not confirmed on the Ti surface, but oxygen is distributed at the tip of the droplet on the Mg side. Molten AZ80 and Ti-based compound phases are produced by thickening of Al in the vicinity of Ti after wetting is completed, and Al in the Mg alloy does not affect the wetting. The driving force of wetting progression is a thermite reaction that occurs between Mg and TiO2, and then Al in AZ80 thickens on the Ti substrate interface to form an intermetallic compound.

• Applied Microscopy
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• v.9 no.1
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• pp.1-11
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• 1979

Electron microscopic studies were carried out to investigate the fine structure of ommatidia of the compound eyes in Meimuna mongolica D. The crystalline cone appears round, and is composed of four double-membraned cone cells and surrounded by pigment cells having many pigment granules. The rhabdom is a closed type, and is composed of four rhabdomeres Its cross section reveals lamellated microvilli which are oriented in four different directions suggesting that these represent four photoreceptive sites. The microvilli, in a cross sectional view, are hexagonal in shape with a central axis inside. There are usually eight retinular cells arranged radially from the rhabdom, but in some retinular layers seven or nine retinular cells could be observed. The cytoplasm of each retinular cell is interconnected with that of microvilli of the rhabdomere, but the appearance of this interconnection varies depending on the number of retinular cells.'The retinlilar cells neighboring the microvilli seem to have well-developed perirhabdomal vacuoles and mitochondria as well as pigment granules surrounding these vacuoles.

• Water for future
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• v.29 no.3
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• pp.217-228
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• 1996

A new routing computer model for the symmetric compound channel called the ASFMCS (Apparent Shear Force Muskingum-Cung Method in Symmetry) is developed. The Muskingum-Cunge routing method is adapted. The Apparent Shear Force(ASF) between the deep main channel and shallow floodplain flow is introduced while the flow is routed. The nonlinear parameter method is applied. The temporal and spatial increments are varied according to the flow rate. The adaptation of above schemes is tested against the routed hydrographs using the DAMBRK model. The results of general routing practice of Muskingum-Cunge Method (GFMC) are also compared with those of the above two models. The results of the new model match remarkably well with those of DAMBRK. The routed hydrographs show smooth variation from the inflow boundary condition without any distortions caused by the difference of cross-section shape. However, the results of GPMC, showing earlier rising and falling of routed hydrograph, have considerable differences from those of the ASFMCS and DAMBRK.

• Journal of Korea Water Resources Association
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• v.42 no.2
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• pp.141-148
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• 2009

Each river in each country has peculiar channel characteristics at every section. Korea consists of mountains at the rate of 70%. Due to this, the sections that display unique channel form are scattered. One of the typical features is the narrow pass of channel section that presents in the process of the generation of alluvial channel and deformation channel. Around as this narrow pass of channel, it often comes to be regular flood disaster section. Regardless of this situation, investigations and plans that reflect channel characteristics at the narrow pass of channel have been wholly wanting until now. In accordance with this, we have investigated and analysed hydraulic significance and channel form of the narrow pass of channel in Seonsan in this study. The study has found real minute classification of sediment phenomenon at river bed of low flow channel on investigation section which is sand-bed river, but it was vaguely difficult to conclude that classification of sediment arises from explicit natural force. We were able to assume that the phenomenon comes from gentle bed slope, supply of river bed materials which is nearly uniformity. However, classification of sediment would come from collecting an aggregate rather than natural force. And we found that compound cross section conversion has been developing dramatically with channel form of movable bed section referring to movement which was active before at drainage district of the narrow pass of channel. With this, we could find the phenomenon that river width of low flow channel diminished largely. This kind of situation implies that it may cause compound section weighting, flood dimension decreasing, revetment at low flow channel or the local scour at bottom of levee when extraordinary flood occurs.