• Smart Structures and Systems
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• v.18 no.4
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• pp.819-837
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• 2016

The quality of vibration pattern reproduction of elastic structures by the modal expansion method is influenced by the modal expansion method and the sensor placement as well as the accuracy of measured natural modes and the total number of vibration sensors. In this context, this paper presents an improved numerical method for reproducing the vibration patterns by introducing a block-wise modal expansion method (BMEM), together with the genetic algorithm (GA). For a given number of vibration sensors, the sensor positions are determined by an evolutionary optimization using GA and the modal assurance criterion (MAC). Meanwhile, for the proposed block-wise modal expansion, a whole frequency range of interest is divided into several overlapped frequency blocks and the vibration field reproduction is made block by block with different natural modes and different modal participation factors. A hollow cylindrical tank is taken to illustrate the proposed improved modal expansion method. Through the numerical experiments, the proposed method is compared with several conventional methods to justify that the proposed method provides the improved results.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.6
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• pp.641-652
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• 2000

The effect of block arrangement has been investigated on the particle deposition in the specified collecting cell of two-stage electrostatic precipitator by numerical analysis. Recirculation zone existed at the downstream of the block in the collecting cell, and the particles entering the recirculation zone were deposited on the collecting plate. Particle trajectory and deposition had considerably different phenomenon according to electrostatic and inertial effect, which depended on inlet mean velocity, electrostatic number, and particle diameter in the collecting cell. The total collection efficiency reached a minimum value through an interaction of electrostatic and inertial effect. In the computational domain, total collection efficiency for the case of two blocks in the computational domain was more than that of one block at the relative small electrostatic number. However as the block distance and inertial effect increased, the difference between the collection efficiency of two cases decreased. In the range of relatively small particle size total collection efficiency was always superior to particle collection efficiency that was predicted by Deutsch equation.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.4
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• pp.372-378
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• 2010

This paper propose the fast motion estimation algorithm with adaptive search range adjustment using motion activities of temporal and spatial neighbor blocks. The existing fast motion estimation algorithms with adaptive search range adjustment use the maximum motion vector of all blocks in the reference frame. So these algorithms may not control a optimum search range for slow moving block in current frame. The proposed algorithm use the maximum motion vector of neighbor blocks in the reference frame to control a optimum search range for slow moving block. So the proposed algorithm can reduce computation time for motion estimation. The experiment results show that the proposed algorithm can reduce the number of search points about 15% more than Simple Dynamic Search Range(SDSR) algorithm while maintaining almost the same bit-rate and motion estimation error.

• Bulletin of the Korean Chemical Society
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• v.29 no.8
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• pp.1539-1544
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• 2008

A polymeric micelle, based on the poly(benzyl-L-histidine)-b-poly(ethylene glycol) (polyBz-His-b-PEG) diblock copolymer, was designed as a tumor-specific targeting carrier. The micelles (particle size: 67-80 nm, critical micelle concentration (CMC); 2-3 $\mu$g/mL) were formed from the diafilteration method at pH 7.4, as a result of self-assembly of the polyBz-His block at the core and PEG block on the shell. Removing benzyl (Bz) group from polyBz-His block provided pH-sensitivity of the micellar core; the micelles were physically destabilized in the pH range of pH 7.4-5.5, depending on the content of the His group free from Bz group. The ionization of His group at a slightly acidic pH promoted the deformation of the interior core. These pHdependent physical changes of the micelles provide the mechanism for pH-triggering anticancer drug (e.g., doxorubicin: DOX) release from the micelle in response to the tumor’s extracellular pH range (pH 7.2-6.5).

• Geomechanics and Engineering
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• v.14 no.6
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• pp.571-580
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• 2018

The failure mechanism of tunnel roof is investigated with upper bound theorem of limit analysis. The stochastic settlement and nonlinear failure criterion are considered in the present analysis. For the collapse of tunnel roof, the surface settlement is estimated by the simplified stochastic medium theory. The failure curve expressions of collapse blocks in homogeneous and in layered soils are derived, and the effects of material parameters on the potential range of failure mechanisms are discussed. The results show that the material parameters of initial cohesion, nonlinear coefficient and unit weight have significant influences on the potential range of collapse block in homogeneous media. The proportion of collapse block increases as the initial cohesion increases, while decreases as the nonlinear coefficient and the unit weight increase. The ground surface settlement increases with the tunnel radius increasing, while the possible collapse proportion decreases with increase of the tunnel radius. In layered stratum, the study is investigated to analyze the effects of material parameters of different layered media on the proportion of possible collapse block.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.80-80
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• 2006

As the size scale of features continue to shrink in devices, the use of self-assembly, i.e. a "bottom up" approach, for device fabrication becomes increasingly important. Yet, simple self-assembly alone will not be sufficient to meet the increasing demands place on the registry of structures, particularly nanostructured materials. Several criteria are key in the rapid advancement and technology transfer for self-assembling systems. Specifically, the assembly processes must be compatible with current $^{\circ}{\infty}top\;down^{\circ}{\pm}$ approaches, where standard photolithographic processes are used for device fabrication. Secondly, simple routes must be available to induce long-range order, in either two or three dimensions, in a rapid, robust and reliable manner. Thirdly, the in-plane orientation and, therefore, ordering of the structures, must be susceptible to a biasing by an external, macroscopic means in at least one, if not two directions, so that individual elements can be accessed in a reliable manner. Block copolymers, specifically block copolymers having a cylindrical microdomain morphology, are one such material that satisfy many, if not all, of the criteria that will be necessary for device fabrication. Here, we discuss several routes by which these versatile materials can be used to produce arrays of nanoscopic elements that have high aspect ratios (ideal for templating and scaffolding), that exhibit long-range order, that give access to multiple length scale structuring, and that are amenable to being biased by macroscopic features placed on a surface.

• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.2
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• pp.8-14
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• 2004

Abstract: In the oil hydraulic piston pumps the clearance between the valve plate and cylinder block plays an important role for volumetric and overall efficiency. Thus, adequate lubricational fluid film is needed for the interface. In this study, fluid film thickness is measured by a gap sensor and a slip ring under operational conditions to observe the behavior of the lubrication mechanism in detail. To investigate the effect according to the valve plate types in view of the fluid film, three different types were designed. Leakage flow rate and shaft torque were also measured to clarify the effect according to the valve plate types. A broad range of experiments were conducted to provide reasonable data on the effect of fluid film. In this experiments two main parameters were found, of which the one is the discharge pressure and the other is valve plate geometry. As a result, we found that the spherical valve plate could get more stable fluid film thickness, maintain good efficiency for high pressure range than the other types.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.240-242
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• 1996

In this paper, we proposed a method of a hearing aid suitable for the sensorineural hearing impaired. Generally as the sensorineural hearing impaired have narrow audible ranges between threshold and discomfortable level, the speech spectrum may easily go beyond their audible range. Therefore speech spectrum must be optimally amplified and compressed into the impaired's audible range. The level and frequency of input speech signal are varied continuously. So we have to make compensation input signal for frequency-gain loss of the impaired, specially in the frequency band which includes much information. The input sigaal is divided into short time block and spectrum within the block is calculated. The frequency-gain characteristic is determined using the calculated spectrum. The number of frequency band and the target gain which will be added input signal are estimated. The input signal within the block is processed by a single digital filter with the calculated frequency-gain characteristics. From the results of monosyllabic speech tests to evaluate the performance of the proposed algorithm, the scores of test were improved.

• ETRI Journal
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• v.25 no.1
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• pp.1-8
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• 2003

This paper introduces an efficient iterative decoding method for high-dimensional block turbo codes. To improve the decoding performance, we modified the soft decision Viterbi decoding algorithm, which is a trellis-based method. The iteration number can be significantly reduced in the soft output decoding process by applying multiple usage of extrinsic reliability information from all available axes and appropriately normalizing them. Our simulation results reveal that the proposed decoding process needs only about 30% of the iterations required to obtain the same performance with the conventional method at a bit error rate range of $10^{-5}\;to\;10^{-6}$.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.661-664
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• 1998

In this paper, the properties of inter-lacking block by the kind of aggregate and fineness modulus are investigated. According to the experimental results, compressive strength and flexural strength increase and absorption ratio decrease with larger fineness modulus in the range of 2.15~4.20. Flexural strength with river sand is higher than that with crushed sand by about 19%, compressive strength with river sand, that with crushed sand by about 11% and absorption ratio with river sand is smaller than that with crushed sand by abort 2%.