• The Journal of the Acoustical Society of Korea
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• v.13 no.3
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• pp.33-40
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• 1994

Code Excited Linear Prediction(CELP) speech coders exhibit good performance at data rates below 4.8 kbps. This major drawback of CELP type coders is required much computation. In this paper, we propose a new pitch search method that preserves the quality of the CELP vocoder with reducing complexity. In the pitch searching, we detect the segments of high correlation by a simple preprocessing, and then carry out the pitch searching only for the segments obtained by the preprocessing. By using the proposed method, we can get approximately $77\%$ complexity reduction in the pitch search.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.443-446
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• 2004

추진기에 의한 소음은 선형 특성에 의한 반류 분포, 추진기 재질 및 유체 연동 등 다양한 주변 인자들에 의해 발생하여, 민수용 선박의 경우는 과도한 추진기 수중 방사 소음으로 해양 생태계 교란 및 선박 거주구역 내 과대 소음 형성의 주 요인이 된다. 더구나, 군사용 함정의 경우에는 추진기 유기 소음은 수중 방사소음의 형태로 전파되어 함정/무기 자체에 탑재된 음향센서의 기능을 저하시키는 영향을 줄 뿐 아니라, 원거리까지 전파되는 수중소음으로 인해 치명적인 자기 노출이 되어 적 함정에 의한 피탐 거리 증대라는 전술적 취약점을 초래하는 중요한 요소이다. 본 발표는 삼성 공동수조(SCAT)에서 이루어지는 추진기 유기 소음 측정에 대한 기술적 사항과 모형선-추진기 수조 시험을 통해 구해진 추진기 유기음향과 이론 및 경험식을 토대로 계산된 추진기 소음의 정량/정성적 비교를 통해, 추진기 설계 단계에서 소음수준 예측 도구로의 활용 가능성을 제시하였다.

• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.95-100
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• 1997

In order to predict the elastic-plastic fracture toughness for metallic materials, Finite Element Method(FEM) was used for analysis of compact tension specimen. ASTM E399 test procedure was adopted for simulation of FEM. The Load-Crack Mouth Opening Displacement curve obtained from this analysis was used to detect the crack initiation point and determine the elastic-plastic fracture toughness $J_{IC}$. In order to prove the results, they were compared with the results from previous experiments and they agree with experimental results.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.1-11
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• 2003

A mathematical model was proposed to analyze the oxygen diffusion reaching the cornea through the tear layers and contact lens based on Fick's law and the principle of continuity of the diffusion flux through the each layers. The model predicts how the parameters such as the thickness of tear layer on the cornea, both the Dk and thickness of contact lenses etc., affect the oxygen tension at cornea and oxygen flux entering the cornea. It is found that either too flat or too tightly fitted contact lenses can cause the oxygen deficiency inside the periphery of the cornea because of the reduction of oxygen flux resulted from too thickened tear layer.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.283-294
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• 2011

The variation of temperature in the steel girder bridge by air temperature is measured. A correlation between the daily temperature range, the maximum and minimum temperatures of the day, and the temperature of the bridge are analyzed. With the statistical data from the Korea Meteorological Administration, the temperature correlations analyzed in this study is able to predict temperature variations between the upper flange and the lower flange which calculates the realistic displacement values of a movable support and an expansion joint in design.

• Composites Research
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• v.25 no.5
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• pp.164-168
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• 2012

The purpose of this experimental research was to evaluate interface shear requirements between UHPC deck and concrete girder with stirrups according to Korean Highway Bridge Design Code and AASHTO LRFD Bridge Design Specifications. The push-out tests are performed to analize the composite behavior in interface of connection. The test results were compared to the values of interface horizontal shear strength predicted by current codes. As the results, it was observed that the test results provided more conservative estimate for horizontal shear strength than the values by current codes equation.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.105-108
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• 2007

최근 세라믹 막은 우수한 화학적, 열적 안정성으로 기체 분리 공정에 각광을 받아왔다. 특히 혼합기체에서 고 순도의 수소를 분리해 내는 기술은 연료전지 공정에서 화학 에너지를 적기화학 에너지로 전환시키는데 중요한 역할을 차지한다. 본 연구에서는 MTES 템플레이팅 막을 이용하여 이 막 공정의 흡착 및 투과 특성을 규명하고, 이성분 혼합기체에서 고 순도의 수소를 추출해 낼 수 있는 최적 조건을 도출해 내었다. 또한, 기체 분리 거동을 살펴보기 위해 Gproms Simulator를 이용하였으며, 이때 기체상의 물질전달을 모사하기 위해 Dust Gas Model(DGM)을, 표면 확산 거동을 모사하기 위해 Generalized Stefan-Maxwell(GSM)식을 적용하였다. 이를 통해 평형론적 흡착 뿐 아니라 속도론적 흡착을 동시에 적용할 수 있게 하였다. MTES 템플레이팅 막의 흡착 및 분리능을 규명하기 위해 본 연구에서는 혼합기체의 투과, 분리 실험이 선행되었다. 실험 조건은 온도범위 $30{\sim}50$ $^{\circ}C$, 압력범위 $0{\sim}5$ atm에서 수행되었으며, 혼합기체는 2성분으로 수소 메탄, 수소-이산화탄소, 수소-질소로 기체의 구성비는 각각 50:50 이다. 본 연구를 통해 각 혼합 기체들이 정상상태에 도달하는 시간과 분리능을 계산해 내었으며, 이 분리능을 다시 온도와 압력에 따른 결과로 분석하여 어느 조건에서의 수소 분리도가 최고치를 보이는지를 규명했으며, 시뮬레이션과 비교, 대조하여 예측도를 검사하였다.

• The Journal of the Acoustical Society of Korea
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• v.14 no.6
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• pp.21-26
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• 1995

In this paper integral equations are derived and simulated numerically for the mutual radiation impedance of an acoustic transducer in a Plane array. It is assumed that the pistons are mounted in the rigid infinite baffle. The mutual radiation impedance is separated into resistance and reactance and plotted as a function of ka and kd. Mutual radiation resistance is decreased and perturbed according to increase of ka. Mutual radiation reactance is decreased along to increase of ka. Mutual impedance is decreased when kd is increased. However, when ka is 6, 13, and 19 the interaction effect is decayed. When the relative piston position of the two pistons is 45 degree, the amount of interaction becomes minimized.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.145-156
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• 1993

An improved analysis model for material nonlinearity induced by elasto-plastic deformation and damage including large strain response was proposed. The elasto-plastic-damage constitutive model based on the continuum damage mechanics approach was adopted to overcome limitations of the conventional plastic theory, which can manage the anisotropic tonsorial damages evolved during time-independent plastic deformation process of materials. Updated Lagrangian finite element formulation for elasto-plastic damage coupling problem including large deformation, large rotation and large strain problems was completed to develop a numerical model which can predict all kinds of structural nonlinearities and damage rationally. Finally, a finite element analysis code for the 2-dimensional plane problem was developed and the applicability and validity of the numerical model was investigated through some numerial examples. Calculations showed reasonable results in both geometrical nonlinear problem due to large deformation and material nonlinearity including the damage effect.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2120-2124
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• 2008

In order to rise up the accuracy of evaluation of egress safety for train car and facilities, analysis of egress route, scenario and the prediction by variation of flow rate were conducted. According to analysis of egress scenario for train, the extra time should be added to the time from train to safety area when the distance between the train car floor level and the track level exists. In the result of hand calculation, the egress time was 123.1 s at flow rate 0.5, was 61.5 s at flow rate 1.0, and was 41 s at flow rate 0.5.