• Bulletin of the Korean Chemical Society
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• 제16권9호
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• pp.873-885
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• 1995

The local structural and thermodynamical properties of blends A-B/H of a diblock copolymer A-B and a homopolymer H are studied using the polymer reference interaction site model (RISM) integral equation theory with the mean-spherical approximation closure. The random phase approximation (RPA)-like static scattering function is derived and the interaction parameter is obtained to investigate the phase transition behaviors in A-B/H blends effectively. The dependences of the microscopic interaction parameter and the macrophase-microphase separation on temperature, molecular weight, block composition and segment size ratio of the diblock copolymer, density, and concentration of the added homopolymer, are investigated numerically within the framework of Gaussian chain statistics. The numerical calculations of site-site interchain pair correlation functions are performed to see the local structures for the model blends. The calculated phase diagrams for A-B/H blends from the polymer RISM theory are compared with results by the RPA model and transmission electron microscopy (TEM). Our extended formal version shows the different feature from RPA in the microscopic phase separation behavior, but shows the consistency with TEM qualitatively. Scaling relationships of scattering peak, interaction parameter, and temperature at the microphase separation are obtained for the molecular weight of diblock copolymer. They are compared with the recent data by small-angle neutron scattering measurements.

• 대한기계학회논문집
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• 제12권4호
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• pp.790-805
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• 1988

본 연구에서는 유리섬유 강화 에폭시 복합재료의 파괴 강도와 피로 수명을 정 규분포, 로그 정규 분포와 2모수 및 3모수 Weibull 분포 함수의 기대값으로 살펴 보았 다. 2연속 응력 피로 실험 [작은 응력에서 큰 응력으로의 실험(low-high test), 큰 응력에서 작은 응력으로의 실험(high-low test)]의 결과도 분포 함수들을 사용하여 분 석하였다. 비통계학적 누적 손상 법칙들(non-statistical cumulative damage rules) 을 2연속 응력 피로 수명 분산 예측에 이용하기 위해서 동등 순위 가정(equal rank assumption)을 확장하여 수정하였다. 수정한 누적 손상 모형은 Miner의 법칙, Brou- tman과 Sahu의 손상모형 및 Hashin과 Rotem의 모형 등이다.

• 한국통신학회논문지
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• 제23권8호
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• pp.1893-1898
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• 1998

Self-phase modulation (SPM)에 의해 발생한 Chirp에 의해 향상된 전송 특성을 고려하여 송신단에서의 $\alpha$ 계수를 재정의 하였다. $\alpha$ 계수는 stimulated Brillouin scattering(SBS)을 무시할 수 있는 12.5dBm의 광입력으로 인한 SPM 현상이 존재하는 경우 송신기 자체의 $\alpha$ 계수에 비해 약 1 정도 줄어들었다. 이와 같이 $\alpha$ 계수의 감소는 송신기에서 $\alpha$ 계수가 positive던지 negative던지 간에 전송 특성을 향상시킬 수 있다. SPM에 의한 유효 $\alpha$ 계수는 10 Gbps급 초고속 전송 시스템 설계에 중요한 계수가 될 수 있다.

• 한국결정학회지
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• 제17권2호
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• pp.51-54
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• 2006

BaO layers were formed on the Si(100) surface by thermal evaporation of barium metal with simultaneous oxidation. The atomic structure of BaO layers at the initial stage of the deposition was investigated by the scattering intensity variation of $He^+$ions on time-of-flight (TOF) impact-collision ion scattering (ICISS). The results show that several number of BaO layers are formed on the Si(100) surface with the lattice parameter of bulk phase, and the occupation of oxygen atoms of the BaO layers is on-top site of silicon atoms.

• 한국군사과학기술학회지
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• 제10권3호
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• pp.148-153
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• 2007

In this paper, the evolutionary adaptive wavelet transform(EAWT) is applied to the scattering analysis of radar target. EAWT algorithm uses evolutionary programming for the time-frequency parameter extraction instead of FFT and the bisection search method used in the conventional adaptive wavelet transform(AWT). Therefore, the EAWT has a better performance than the conventional AWT. In the simulation using wire target(Airbus-like), the comparisons with the conventional AWT are presented to show the superiority of the EAWT algorithm in the analysis of scattering phenomenology. The EAWT can be effectively applied to the radar target recognition.

• 한국음향학회지
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• 제38권5호
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• pp.511-521
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• 2019

본 연구에서는 무한 유체에 놓여있는 유한 길이의 탄성 원통 쉘에 외부에서 비스듬히 평면파가 입사할 때 발생하는 음향 산란 현상을 이론적으로 연구했다. 유한 길이의 원통 쉘에서는 해석적인 산란 해가 존재하지 않기 때문에, Kirchhoff 가정을 적용한 Ye의 산란 기법[Z. Ye, J. Acoust. Soc. Am. 102, 877-884 (1997)]을 사용했다. 탄성 원통 쉘의 특성은 3차원 탄성파 이론을 적용하여 구현했으며 원통 쉘 내부의 유체를 고려했다. 유도된 해석 해를 이용하여 내부 유체가 산란 음장에 미치는 효과, Rayleigh 변수에 대한 산란 음장, 탄성 재질의 변화에 따른 먼 거리 산란 함수를 살펴보았다.

• 대한기계학회논문집
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• 제16권5호
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• pp.952-964
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• 1992

본 연구에서는 2차원 정사각형 밀폐공간내에 열복사를 흡수, 방사 및 비등방 산란하는 매질이 존재할 때 자연대류와 복사의 상호작용을 선형 비등방 산란을 가정 하고 복사열전달의 계산시 P-N 근사법을 이용하여 해석하였다. 수치계산을 통하여 Planck 수, 산란알베도, 광학두께, 벽방사율 및 비등방 산란이 유동 및 온도 특성 그리고 열전달에 미치는 영향을 조사하였다.

• 대한금속재료학회지
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• 제50권10호
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• pp.721-728
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• 2012

This paper evaluates the reliability of creep rupture life under service conditions of Alloy 617, which is considered as one of the candidate materials for use in a very high temperature reactor (VHTR) system. A Z-parameter, which represents the deviation of creep rupture data from the master curve, was used for the reliability analysis of the creep rupture data of Alloy 617. A Service-condition Creep Rupture Interference (SCRI) model, which can consider both the scattering of the creep rupture data and the fluctuations of temperature and stress under any service conditions, was also used for evaluating the reliability of creep rupture life. The statistical analysis showed that the scattering of creep rupture data based on Z-parameter was supported by normal distribution. The values of reliability decreased rapidly with increasing amplitudes of temperature and stress fluctuations. The results established that the reliability decreased with an increasing service time.

• International Journal of Computer Science & Network Security
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• 제22권1호
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• pp.121-128
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• 2022

There are much processing techniques of microwave circuits, whose dimensions are small compared to the wavelength, but the disadvantage is that they cannot be directly applied to circuits working at high and/or low frequencies. In this article, we will consider the bond graph approach as a tool for analyzing and understanding the behavior of microwave circuits, and to show how basic circuit and network concepts can be extended to handle many microwaves analysis and design problems of practical interest. This behavior revealed in the scattering matrix filter, and which will be operated from its reduced bond graph model. So, we propose in this paper, a new application of bond graph approach jointly with the scattering bond graph for a high frequency study.

• 호남수학학술지
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• 제45권3호
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• pp.457-470
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• 2023

In this study, we set a boundary value problem (BVP) consisting of a discrete Sturm-Liouville equation with transmission condition and boundary conditions depending on generalized eigenvalue parameter. Discussing the Jost and scattering solutions of this BVP, we present scattering function and find some properties of this function. Furthermore, we obtain resolvent operator, continuous and discrete spectrum of this problem and we give an valuable asymptotic equation to get the properties of eigenvalues. Finally, we give an example to compare our results with other studies.