• Journal of Intelligence and Information Systems
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• v.13 no.3
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• pp.63-82
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• 2007

In this paper, we propose an adaptive hybrid genetic algorithm (ahGA) approach for effectively solving multistage-based scheduling problems in flexible manufacturing system (FMS) environment. The proposed ahGA uses a neighborhood search technique for local search and an adaptive scheme for regulation of GA parameters in order to improve the solution of FMS scheduling problem and to enhance the performance of genetic search process, respectively. In numerical experiment, we present two types of multistage-based scheduling problems to compare the performances of the proposed ahGA with conventional competing algorithms. Experimental results show that the proposed ahGA outperforms the conventional algorithms.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.5
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• pp.659-664
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• 2013

It is necessary to develop an efficient MVD coding scheme to improve the video coding performance. In this paper, combined codeword and joint codeword are suggested from analyses on statistical distributions of MVD according to the quantization steps and the conventional codeword structure. Based on these codewords, we propose new MVD coding scheme where one of the suggested codewords is employed to encode the MVD according to the coding environment. Simulation results show that the proposed scheme enhances the coding performance without the quality degradation.

• The Journal of the Acoustical Society of Korea
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• v.18 no.8
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• pp.42-47
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• 1999

In this paper, a mixture interacting multiple model (MIMM) algorithm is proposed to enhance speech contaminated by additive nonstationary noise. In this approach, a mixture hidden filter model (HFM) is used to model the clean speech and the noise process is modeled by a single hidden filter. The MIMM algorithm, however. needs large computation time because it is a recursive method based on multiple Kalman filters with mixture HFM. Thereby, a computationally efficient implementation of the algorithm is developed by exploiting the structure of the Kalman filtering equation. The simulation results show that the proposed method offers performance gain compared to the previous results in [4,5] with slightly increased complexity.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.38-45
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• 1998

It is a tedious and excessive time consuming process to model the local area of crack tip part of structures in calculation of stress intensity factors by FEM. So, in this paper, the hybrid method of FEM and BEM approach was formulated to overcome this type of problems. The multi-domained BEM was adopted to simplify the modelling process of complex geometry and singularity characteristics of crack tip part and the ordinary FEM modelling was used in the rest part. The example calculations shows very good results compared with analytic solutions and other numerical method.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.124.2-124.2
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• 2011

천연의 메탄 하이드레이트를 생산하기 위한 방법으로 몇 가지가 알려져 있으나 최근의 연구 결과로는 감압법이 가장 효과적이며 경제성을 확보할 수 있다고 알려져 있다. 하지만 이 방법을 이용한 메탄 하이드레이트 개발생산 시에는 해리된 물과 가스가 동시에 생산유체로 발생하여 수송되며, 생성수에는 하이드레이트 전구체라고 알려진 미완의 하이드레이트 구조체가 남게 된다. 생산유체는 낮은 해수온도에 노출되어 가스 하이드레이트가 쉽게 재생성될 가능성이 높기 때문에 안정적인 가스 생산과 생산시설의 보호를 위해서는 적절한 가스 하이드레이트 재성성 억제대책이 필요하다. Kinetic 억제제의 적용이 많이 이루어지고 있는 가스전에서의 경험을 바탕으로 투여해 보는 시도를 하고 있지만 sII인 천연가스 하이드레이트에서의 억제효과와 비교하여 저하된 결과가 보고되고 있다. sI과 sII는 메커니즘의 차이로 인해 억제제의 성능이 다르게 나타난다. sI인 메탄 하이드레이트에 대하여 kinetic 억제제의 효과를 살펴보았고 이온성액체를 적용한 효과적인 sI 하이드레이트 억제기법을 보고한다. 또한 기존의 sII 억제제와 혼합하여 시너지효과를 얻을 수 있음을 확인하였다.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.189-200
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• 2015

Stationary bootstrapping is applied to a Lagrangian multiplier (LM) test to test market microstructure noise (MMN) in financial asset prices. A Monte-Carlo experiment shows that the bootstrapping method improves the size of the original LM test which has some size distortion for conditional heteroscedastic models. The proposed test is illustrated for real data sets like KOSPI index and Won-Dollar exchange rate.

• Journal of the Korean Magnetics Society
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• v.11 no.2
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• pp.45-49
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• 2001

Effects of multilayer structure and annealing condition on the soft magnetic properties of sputtered Fe/CoNbZr multilayers were investigated. We observed a minimum coercivity (1.1 Oe) at 5 nm thick Fe layer and the maximum permeability (2300) at 15 nm Fe layer and high saturation magnetization in the as-deposited state. As a result of increase of Fe grain size, coercivity increases with increasing Fe layer thickness. Degradation of ${\mu}$ at the thin Fe layer region may be due to the intermixed phase of high magnetostriction, such as CoFe. Optimum annealing condition was obtained through annealing at 300 $^{\circ}C$ for 40 min (${\mu}$=2500, H$\sub$c/=0.35 Oe). Enhancement of permeability was observed in the temperature range of 250∼300$^{\circ}C$. These results may closely be related with lowering the anisotropy energy by lattice deformation (0.4%) and enhanced uniaxial anisotropy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.19-26
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• 2018

This study evaluates the shear performance of reinforced concrete members with web opening reinforcement. A total of 4 reinforced concrete members with or without openings were cast then tested. The main variables investigated were with or without of web openings and with or without of web opening reinforcement, respectively. The proposed web opening reinforcement was a rectangle and rhombus-shaped spiral considering of construct ability. Test result showed that the proposed web reinforcement had improved shear capacity and ductility of the specimens. It was found that the web opening reinforcement proposed in this study had a positive effect on the shear strength and crack control of RC beams with web openings. In addition, it was confirmed that the analytical results by the current design codes underestimates the test results of the specimens with the proposed web opening reinforcement.

• 한국해양학회지
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• v.30 no.1
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• pp.1-12
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• 1995

The modal analysis was carried out for the total of 216 subface sediments of southern continental shelf of Korean peninsula. Sandy mud or muddy sand distributed in the range of 70∼100 m water depth revealed the bimodal type (sand and mud components). The relations of textural parameters obtained from every modal were consistent with those of shallow marine sediments. The characteristics of sand component between bimodal were as follows: (1) the distributions of mean grain size, sorting, shell content were repeatedly distributed like the directions of depth contour lines. (2) Sand component was composed of medium to fine sand (Mz, 1-3$\psi$) containing many shell fragments, a few pebbles, and iron-stained quartz. (3) The surface of quartz revealed the concordial breakage and V-shaped features formed at high energy environment. (4) In CM-pattern, sand component was plotted in rolling and bottom suspension area. These characteristics imply that sand component probably derives from shoreface sediments deposited at the beach environment.

• Journal of the Mineralogical Society of Korea
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• v.18 no.3 s.45
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• pp.227-236
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• 2005

Hydrothermal tourmaline occurs as aggregates or dissemination in the diaspore nodule from an aluminum-rich clay deposit, Milyang, southeastern Korea. Most crystals of tourmaline show complex textures that are finely zoned. The fine-scale chemical zonation of hydrothermal tourmaline reflects the fluctuation conditions that would be expected from fluid mixing in open systems. Oscillatory chemical zoning in tourmaline formed and showed similar patterns, regardless of its crystallographic directions. Mg was enriched in the early stage of crystal growth while Fe was enriched in the later stage, with fluctuations of the ratio of Fe to Mg. Chemical analysis, BSE images, and X-ray compositional maps confirm that the oscillatory Boning in tourmaline is exclusively controlled by the variations of Fe and Mg contents, but the contribution of boron to the zonation is insignificant. The fact that tourmaline altered to diaspore and dickite indicates that tourmaline was unstable with respect to these aluminous minerals as the B, Fe, and Mg activities decreased. Therefore, the aluminum activity may control the stability of tourmaline in the hydrothermal system.