• The Journal of the Acoustical Society of Korea
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• v.10 no.5
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• pp.27-35
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• 1991

음소를 인식의 기본 단위로 하는 소규모 음성 인식 시스템을 구현하기 위한 기초 연구로서 마 찰음(/ㅅ, ㅆ, ㅎ/) 과 파찰음(/ㅈ, ㅉ, ㅊ/) 에 대하여 지속시간, 평균패턴, 분산비를 이용하여 각 음소 의 특징을 분석하고 각 음소군 내에서의 식별에 유효한 parameter들을 추출하여 인식 실험을 실시하 였다. 지속시간의 분포, 평균패턴의 분포, 분산비의 분포를 이용하여 분석한 결과 6차원 정도의 cepstrum 계수만으로 마찰음 및 파찰음의 식별이 가능하고, 시간 방향의 정보는 음성의 시단으로부터 14 frame 정도의 특징을 인식 파라미터로 할 경우가 최적임을 알 수 있었다. 이를 이용한 인식실험 결과에서는 조음방법별로 분류된 음소군내의 각 음소에 대한 인식실험의 인식률 보다는 발음방법별 인식실험시의 인식률이 높게 나타나 동일 음소군 내에서의 각 음소에 대한 식별이 더 어려움을 알 수 있었고, 특징 파라미터의 길이를 음성의 시단으로부터 14 frame 정도로 했을 때 조음방법별 인식률은 평균 81.1%, 발음방법별 인식률은 평균 97.9%로 최고의 인식률을 나타내었다. 특징 파라미터의 길이 를 14 frame 이상으로 증가시켜도 인식률은 큰 변화가 없어 분석 결과를 잘 설명하고 있음을 알 수 있었다.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.293-302
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• 2004

The transfer of prestress force in pretensioned prestressed concrete (PSC) members is of great concern because it affects directly the distribution of stress around the transfer zone. The design provision of current design code on the transfer length considers only the prestress intensity and the diameter of prestressing steels. However, other factors such as concrete compressive strength and concrete cover may affect greatly the transfer length. The purpose of the present paper is to explore the various factors that affect the transfer length in pretensioned PSC members. The bond stress-slip relation between prestressing steel and concrete was modeled first from experimental data and then this model was incorporated into the interface element. The interface element was used to perform the finite element analysis for pretensioned PSC members. The results indicate that the compressive strength and concrete cover are also very important parameters which affect the transfer length greatly. This means that the current design code, which considers only the effective prestress and diameter of prestressing steel, must be improved to take into account the other important variables of compressive strength and concrete cover. The present study allows more realistic analysis and design of pretensioned PSC members.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.99-107
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• 2008

This paper presents the prediction of the actual strength of shear reinforcement on the basis of the concept of effective stirrups. The prediction method incorporating the shear cracking angle was proposed with the estimation by the Modified Compression Field Theory (MCFT). To check the validity of the method, discussion of the current ACI 318-05 and comparison of 39 test results from the literature including author's retrospective test data were made. The influencing factors of compressive concrete strength and type of shear-reinforcement were also investigated. Furthermore, two full-scale beam specimens shear-reinforced with headed bars were tested to demonstrate the applicability of the proposed method.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.11
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• pp.15-20
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• 2004

This paper proposed a very simple method of extracting an effective permittivity from the data of scattering parameters measured on the transmission line of coplanar waveguides in the frequency range of microwave or millimeter waves. This is an extracting method of an effective permittivity $\varepsilon$$_{eff}$ in the case of $\beta$$\ell$ =n$\pi$ (n=integer), where the value of S$_{11}$ changes abruptly following the operating frequency. The experimental value of the effective permittivity $\varepsilon$$_{eff}$ on a dielectric substrate of Rogers 4003$^{TM}$ material of $\varepsilon$$_{r}$ =3.38 showed the value of 2.042, which differs in the error of -3.4% to 8% from those calculated from the previously reported formulae. This result showed that the measurement method was very simple, as well as applied directly to the fabricated circuit patterns, even though the circuit patterns might be complicated or on the substrate of different dielectric materials.s.als.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.1
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• pp.15-20
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• 2009

The results of crack evaluation by conventional UT(Ultrasonic Test)is highly depend on the inspector's experience or knowledge of ultrasound. Phased array UT system and its application methods for small crack length evaluation will be a good alternative method which overcome present UT weakness. This study was aimed at checking the accuracy of crack length evaluation method by electronic scanning and discuss about characteristics of electronic scanning for crack length evaluation. Especially ultrasonic phased array with electronic scan technique was used in carrying out both sizing and detect ability of crack as its length changes. The response of ultrasonic phased array was analyzed to obtain the special method of determining crack length without moving the transducer and detect-ability of crack minimal length and depth from the material. A method of crack length determining by electronic scanning for the small crack is very real method which has it's accuracy and verify the effectiveness of method compared to a conventional crack length determination.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1453-1463
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• 2013

In this study, we investigated the effect of the indenter geometry on the crack characteristics by indentation cracking test and FEA. We conducted various cohesive finite element simulations based on the findings of Lee et al. (2012), who examined the effect of cohesive model parameters on crack size and formulated conditions for crack initiation and propagation. First, we verified the FE model through comparisons with experimental results that were obtained from Berkovich and Vickers indentations. We observed whether nonsymmetrical cracks formed beneath the surface during Berkovich indentation via FEA. Finally, we examined the relation between the crack size and the number of cracks. Based on this relation and the effect of the indenter angle on the crack size, we can predict from the crack size obtained with an indenter of one shape (such as Berkovich or Vickers) the crack size for an indenter of different shape.

• Magazine of the Korea Concrete Institute
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• v.1 no.2
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• pp.101-112
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• 1989

콘크리트에 선형파괴역할의 적용가능성을 연구한 많은 논문이 발표되었다. 본 논문에서는 CLWL-DCB식편을 이용한 콘크리트의 개구형파괴를 연구하였다. 표면구열길이는 리프리카를 사용하여 직접적인 방법으로 측정하였고, 이 결과은 실험에서 얻은 측정가중과 구열개구변위의 관계곡선을 이용하여 분석하였다. 감계응력강도계수와 감계구열선단위는 Two Parameter 모델을 사용하여 유효구열선단에서 구하였다. LEFM 구열단면과 실험으로 구한 구열단면으로부터 폐쇄압력을 얻기 위하여 중첩법을 적용하여 5종의 균열모델을 평가하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.64-69
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• 1998

KALMER 우라늄 금속핵연료노심의 평형주기에 대하여 주기길이, 농측도, 중식비의 관점에서 설계인자 변경에 따른 변화를 분석하였다. 유효노심높이, 반경방향 블랑캣의 batch수, 개스팽창모듈(GEM)의 적용성, 노용기내핵 연료저장(IVS)의 사용. 핵연료핀의 직경 증가 둥에 대한 설계 변경이 고려되었다. 본 연구결과를 통하여, 평탄화된 출력분포 및 핵연료의 이용도 향상을 기하면서 설계변경이 타 분야에 미치는 영향을 최소화하고 본래 KALMER의 안전성을 유지하고자 핵연료핀의 직경을 증가시킨 fat pellet 설계방안을 채택하였다

• Electrical & Electronic Materials
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• v.6 no.4
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• pp.361-365
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• 1993

플라즈마화상 계측 시스템에 있어서 단층화상의 화질이 떨어지는 문제점 중의 하나로서 시준기특성이 있다. 이것은 시준기가 길이를 가진 형태이기 때문에 생기는 것으로써 화상에서는 천이변형의 왜곡으로 나타난다. 본 논문에서 보정법으로 측정데이타를 공간주파수상에서 천이불변형태로 디콘볼루션하는 방법을 제시하고 시준기의 각도를 파라메타로 해서 플라즈마 계측에 의한 실제의 데이타에 그 보정법의 유효성을 검증하였다.

• ETRI Journal
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• v.9 no.2
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• pp.55-61
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• 1987

The effective cutoff wavelength of $LP_11$mode is measured as a function of fiber length for three types of single-mode optical fiber which have different characteristics in the index profile or the coating structure. The measured cutoff wavelength decreased linearly in a logarithmic scale of fiber length as increasing fiber length, and eventually became constant after 3km for two fiber types. It is found that the length dependence of cutoff wavelength is due to a mode coupling between the $LP_01$ and $LP_11$ modes.