• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.709-711
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• 2005

최근 음성인식 분야에서는 발화된 음성의 단순한 신호 처리위주의 인식 결과로부터 좀 더 신뢰할 수 있는 결과를 얻기 위하여 여러 가지 후처리 기법들이 연구되고 있다. 본 논문에서는 개인 사용자를 위한 음성 명령어 인식 환경에서 사용자의 발화 정보를 후처리에 적용함으로써 사용자 정보를 고려한 음성인식 후처리 기법을 제안한다. 먼저 이전에 사용했던 음성 명령어들로부터 명령어 발화 순차 패턴 규칙을 추출 한 후 사용자가 사전에 발화한 명령어를 바탕으로 구성된 순차 패턴을 비교하여 순차 규칙상 얻어 질 수 있는 단어를 결정한다. 이렇게 얻어진 단어를 고려하여 음성인식기 인식단어 후보들의 확률값을 적절히 보정한 후 최종 인식 단어를 재결정한다. 이러한 과정에서 적절한 보정을 위하여 발화 순차 패턴의 신뢰도와 인식기의 결과단어를 고려한 보정 방법을 제안한다. 실험을 통하여 제안한 후처리를 이용한 음성인식이 HMM을 이용한 기본 음성인식에 비해 오류율을 $15\%$이상 낮추어 인식률에 상당한 기여를 하였음을 확인할 수 있다.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.70-76
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• 2006

The microstructure evolution during a hot forging of Waspaloy was investigated using the recrystallization model and FEM simulation. In order to obtain an uniform microstructure, hot forging was carried out by two step. The change of grain size during hot forging has a deep connection with dynamic recrystallization behavior. Avrami-type constitutive equation for the dynamic recrystallization was implemented into an user subroutine of 2D FE simulator. The evolution of grain structure in the two-step forging of Waspaloy was simulated using the 2D FEM user-subroutine. The detailed variation of microstructures due to dynamic recrystallization could effectively be predicted at various locations in a forged pancake.

• Transactions of Materials Processing
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• v.13 no.5
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• pp.455-460
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• 2004

The deformation and annealing behaviors of a 1050 Al alloy deformed at cryogenic temperature were investigated, focusing on the evolution of microstructures and mechanical properties. Especially, the effects of annealing temperature, $150~300^{\circ}C$, on microstructures and mechanical properties of the sheets received reduction of 88% at cryogenic temperature were investigated. The significant change in mechanical properties with the annealing temperatures of $200~300^{\circ}C$ would be attributed to the variations in the volume fraction of recrystallized grains and coarse equiaxed grains.

• Transactions of Materials Processing
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• v.10 no.1
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• pp.35-41
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• 2001

The high temperature deformation behavior of SCM 440 can be characterized by the hot torsion test in the temperature ranges of $900^{\circ}C$~$1100^{\circ}C$ and strain rate ranges of 0.05/sec~5/sec. The aim of this paper is to establish the quantitative equation of the volume fraction of dynamic recrystallization (DRX) as a function of processing variables, such as strain rate ($\varepsilon$), temperature (T), and strain ('$\varepsilon$). During hot deformation, the evolution of microstructure could be analyzed from work hardening rate ($\theta$). For the exact prediction of dynamic softening mechanism the critical strain ($\varepsilon_c$), the strain for maximum softening rate ($\varepsilon^*$ and Avrami' exponent (m') were quantitatively expressed by dimensionless parameter, Z/A, respectively. The transformation-effective strain-temperature curve for DRX could be composed. It was found that the calculated results were agreed with the experimental data for the steel at any deformation conditions.

• Transactions of Materials Processing
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• v.6 no.2
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• pp.102-109
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• 1997

The multistage deformation and stress relaxation were carried out to investigate the strain induced precipitation by torsion tests in the range of 1000~80$0^{\circ}C$, 0.05~5/sec for V-microalloyed steel. The starting temperature and time for the initiation of precipitation were determined by stress relaxation tests. The distribution of precipitates increased, as the strain rate increased and the mean size of precipitates was found to be about 10~30nm. The precipitation starting time$(P_s)$ decreased with increasing strain rate and the amount of pre-strain. The effect of deformation conditions on the no-recrystallization temperature$(T_nr)$ was also determined in the multistage deformation. $T_nr$ Tnr decreased with increasing the strain and strain rate. In the controlled rolling simulation, grain refinement and precipitation hardening effects could be achieved by the alternative large pass strain at the latter half pass stage under the condition of low temperature and high strain rate.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.75-81
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• 1998

Simulations of warm and hot forming processes need reliable expressions of flow stress at high temperatures. To get flow stress of the materials usually tension, compression and torsion tests are conducted. In this study, hot compression tests were adopted to get flow stress of medium carbon steel. Experiments have been conducted under both isothermal, near constant strain rate in the temperature ranges 650～100$0^{\circ}C$. Phase transformation takes place by temperature changes for steels in hot and warm forging stage. So Constitutive equation are formulated as the function of strain, strain rate and temperature for isothermal conditions and phase transformation.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.8-12
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• 2003

Crustal velocity model is very important to determine the hypocenters of the local earthquakes, because the real crust is more complex and heterogeneous than simple homogeneous layered model. But the exact crust model in and around Kyeongsang basin area is not fixed till now. To solve this problem, Joint Hypocenter Determination(JHD) method is applied to the 151 local earthquakes, that is recorded at KIGAM local network from Mar. 25, 1999 to Dec. 16, 2001. According to the comparison of earthquake locations and depths for the conventional procedure and JHD relocation procedure, each locations is very similar, but depth distributions are different. An initial depth distribution derived from the conventional methods is irregular and does not show the general trends. JHD relocations reduce scatter and define a dipping plane.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.356-362
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• 2009

In order to vary the primary recrystallization textures, AA 1050 sheets were cold rolled in two different manners. Differences in cold rolling schedule gave rise to the formation of different cold rolling textures also leading to the formation of different primary recrystallization textures. Upon annealing for grain growth, changes in microstructure and texture hardly occurred in the sample depicting Cube recrystallization texture, while grain growth was accompanied with the development {001}<100> Cube texture in the sample displaying a recrystallization texture comprising of weak rolling texture components. The selective growth of Cube oriented grains is attributed to the high mobility of their grain boundaries.

• Journal of the Korean earth science society
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• v.32 no.2
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• pp.161-169
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• 2011

Focal mechanism solutions in the central and western areas of the Korean Peninsula (36-37.8$^{\circ}N$, 126-128$^{\circ}E$) were obtained from the analysis of the recent seventeen earthquakes (M${\geq}$2.2) which occurred from January, 2005 to May, 2010. The spatial differences between the epicenters recalculated by this study and those announced by the Korea Meteorological Administration are less than $0.03^{\circ}$, indicating a small deviation. Focal mechanism solutions were obtained from the analysis of P wave polarities, SH wave polarities and SH/P amplitude ratios. The focal mechanism solutions show dominant strike-slip faulting or oblique slip faulting with strike-slip components. The P-axes trends are mainly ENE-WSW or E-W directions. The direction of fault plane and auxillary fault plane with NNE-SSW and WNW-ESE are almost parallel to the general trends of lineaments in the study area. The results also show that focal mechanism solutions and the main axis of stress field in the Kyonggi massif and Okchon belt are almost same.

• Korean Journal of Materials Research
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• v.10 no.9
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• pp.629-635
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• 2000

The texture evolution during isothermal forging and subsequent heat treatment in Ti-48.5at%Al-0.6at%Mo alloy was investigated. Especially, in the present study, research interest was focused on the interrelation between lamellar volume fraction and textures varied with the change of heat-treated time and temperature. It was found that texture components having ND┴{302) and TD$\perp${100} with minor TD$\perp${111} were developed by isothermal forging. In addition, when the followed heat-treatment time and temperature increased from $1330^{\circ}C$/10h to $1350^{\circ}C$/20h respectively, both the lamellar volume fraction and the intensity of textures mentioned above also gradually increased. However, the tensile elongation at room temperature decreased oppositely, as the lamellar volume fraction increased. These results suggested that tensile properties of $\gamma$-TiAl with the nearly lamellar microstructure at room temperature were affected more strongly by the microstructural features such as lamellar volume fraction rather than by textures.