• 한국분말재료학회지
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• 제8권2호
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• pp.131-135
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• 2001

The ferroelectric properties of barium titanate strongly depend on its microstructure, in particular, grain size and distribution. During sintering, $BaTiO_3$ usually exhibits abnormal grain growth, which deteriorates considerably the ferroelectric properties. A typical technique to suppress the abnormal grain growth is the addition of dopants. Dopant addition, however, affects the ferroelectric properties and thus limits the application of $BaTiO_3$. Here, we report a simple but novel technique to prevent the abnormal grain growth of $BaTiO_3$ and to overcome the limitation of dopant use. The technique consists of stepwise sintering in a reducing atmosphere and in an oxidizing atmosphere. The materials prepared by the present technique exhibit uniform grain size and high dielectric properties. The technique should provide opportunities of having $BaTiO_3$-based materials with superior ferroelectric properties.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.319-320
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• 2002

Numerical simulation of chip formation during high speed machining requires knowing the friction at tool/chip interface. This parameter is hardly identified and generally the loadings (temperature, force) during the identification are not similar to those encountered during machining. Thus, Coulomb friction identified with pin-on-disc device is often used to conduct numerical simulation. The used of this technique cannot leads to good numerical results of chip formation compared to the experimental tests especially in the case of low uncut chip thickness. In this contribution, we propose a new method to evaluate the friction at tool/chip interface. In fact several Coulomb friction parameters are identified corresponding to several parts of the cutting tool. Experimental tests have been conducted allowed us to determinate both the level and the distribution of the Coulomb friction. Experimental results are also compared to the results of orthogonal cutting simulation. We show that this technique allows predicting accuracy results of chip formation.

• 한국정보과학회논문지:소프트웨어및응용
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• 제27권2호
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• pp.148-156
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• 2000

컴포넌트 맞춤(customization)으로 인해 변형된 ‘인터페이스 부분’과 ‘핵심기능 부분’의 상호작용에서 발생하는 오류를 효과적으로 테스트하기 위한 테스트 기법은 필요하다. 본 논문에서는 오류 삽입기법과 뮤테이션 테스트 케이스 선정 기법을 사용하여 컴포넌트 맞춤 테스트 기법을 제안한다. 컴포넌트의 인터페이스 가운데 맞춤 오류가 일어나는 곳에만 오류를 삽입하여, 맞추어진 컴포넌트와 오류가 삽입된 컴포넌트를 차별하는 테스트 케이스를 선정한다. 따라서 본 기법은 컴포넌트 맞춤에 의한 오류를 발견할 가능성이 높은 테스트 케이스를 선정할 수 있으며, 인터페이스 가운데 맞춤 오류가 일어나는 부분만을 테스트 대상으로 함으로써, 테스트 시간을 단축할 수 있다.

• Structural Engineering and Mechanics
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• 제64권1호
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• pp.71-79
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• 2017

In this study, interaction of several interface cracks located between a functionally graded material (FGM) layer and an elastic layer under anti-plane deformation based on the distributed dislocation technique (DDT) is analyzed. The variation of the shear modulus of the functionally graded coating is modeled by an exponential and linear function along the thickness of the layer. The complex Fourier transform is applied to governing equation to derive a system of singular integral equations with Cauchy type kernel. These equations are solved by a numerical method to obtain the stress intensity factors (SIFs) at the crack tips. The effects of non-homogeneity parameters for exponentially and linearly form of shear modulus, the thickness of the layers and the length of crack on the SIFs for several interface cracks are investigated. The results reveal that the magnitude of SIFs decrease with increasing of FG parameter and thickness of FGM layer. The values of SIFs for FGM layer with exponential form is less than the linear form.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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• pp.189-192
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• 1988

Nitrided oxides have been investigated recently for application as a replacement for thermally grown $SiO_2$ in MIS devices. In this paper, thin oxides were nitrided in $N_2$ Plasma ambient. With the measurement of the equivalent paralled conductance and capacitance by the using coductance technique, the characterization of Si-SiON interface is developed. The interface state density of Si-SiON is obtained by $1{\times}10^{11}{\sim}9{\times}10^{11}(eV^{-1}Cm^{-2})$. After${\pm}$B-T stress is performed on the sample, the interface state density gets increased.

• 한국정보통신학회논문지
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• 제25권8호
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• pp.1130-1133
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• 2021

In this paper, a miniaturized sensor interface circuit for the respiration detection system is proposed. Respiratory diagnosis is one of the main ways to predict various diseases. The proposed system consists of respiration detection sensor, temperature sensor, and interface circuits. Electrochemical type gas sensor using solid electrolytes is adopted for respiration detection. Proposed system performs sensing, amplification, analog-to-digital conversion, digital signal processing, and i2c communication. And also proposed system has a small form factor and low-cost characteristics through optimization and miniaturization of the circuit structure. Moreover, technique for sensor degradation compensation is introduced to obtain high accuracy. The size of proposed system is about 1.36 cm².

• 한국해양환경ㆍ에너지학회지
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• 제3권1호
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• pp.25-34
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• 2000

이중유벽 사이에 가두어진 기름층과 전방 유벽의 끝에서 발생하는 보오텍스 거동간의 관계를 보기 위하여 파노라마 PIV 기법을 사용하였다. 물-기름 자유경계면 근처의 순간 및 시간평균 경계층 유속분포를 계측하여 경계면 상의 전단응력 도출가능성을 확인하였다. 본 기법을 사용하면 자유경계면의 거동이 작거나 규칙적인 경우 경계면상 전단층내 상세 유동구조를 파악하기 충분한 정도의 해상도를 가진 결과를 얻을 수 있다고 판단되었다.

• 한국추진공학회지
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• 제13권2호
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• pp.9-16
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• 2009

본 연구는 이종 접착 재질의 접착 계면에서 미접착 결함을 검출하기 위한 새로운 시험 기법을 개발하기 위함이다. 접착 계면과 미접착 계면에서의 초음파 전달 현상을 이론적으로 해석하여 초음파 신호를 모델링하였고, 이론적 분석에 기초하여 미접착 계면에서의 위상 반전 현상을 이용한 검사 방법을 FRP/고무 시편에 적용하였다. 정량적으로 결함의 최소 검출 능력을 평가하기 위하여 알루미늄/고무시편에 평저공을 가공하여 제작하였고 일반적으로 사용하고 있는 펄스에코반사법과 새로운 시험 기법인 위상반전법을 상호 비교하였으며 이론적으로 예측한 초음파 신호와 실험에서 얻은 초음파 신호를 근거로 위상반전법으로 미접착 결함을 검출할 수 있다고 판단하였다.

• 한국디자인학회:학술대회논문집
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• 한국디자인학회 2001년도 Bulletin of The 5th Asian Design Conference International Symposium on Design Science
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• pp.77-77
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• 2001

• 한국디자인학회:학술대회논문집
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• 한국디자인학회 2002년도 가을학술발표대회 디자인학 연구
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• pp.68-69
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• 2002