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발파하중을 받는 지반의 동적 거동 수치 모델링에서 입력변수의 영향
류창하,최병희,장형수,강명수,Ryu, Chang-Ha,Choi, Byung-Hee,Jang, Hyung-Su,Kang, Myoung-Soo 한국암반공학회 2015 터널과지하공간 Vol.25 No.3
화약발파는 광업 및 토목 분야에서 암반굴착을 위한 도구로 많이 사용되는 유용한 방법이지만 주변 환경에 대해서는 종종 위해 요인으로 작용한다. 발파 설계자는 피해를 방지하고 효율을 높일 수 있는 적정 설계를 도출하기 위해 노력하며, 설계 단계에서는 시험 발파나 수치해석적 방법을 이용하여 설계의 적정성 평가를 하는 것이 일반적이다. 수치해석적 방법에서 발파와 같은 동적 하중과 그에 대한 암반의 응답 거동에 영향을 주는 많은 변수들이 입력 자료로 설정되어야 하지만, 신뢰성 있는 물성을 획득하기 어려운 설계 단계에서 입력자료를 어떻게 설정할 것인가, 결과를 어떻게 해석하고 설계에 반영할 것인가는 여전히 어려운 문제로 남아 있다. 본 논문은 화약발파를 이용하여 터널과 같은 지하공동을 굴착할 때 암석의 역학적 특성과 관련된 입력 변수들이 해석 결과에 미치는 영향 정도를 정량적으로 평가함으로써 입력 자료에 대한 중요도를 이해하고 설정지침에 도움을 제공하기 위한 목적으로 작성되었다. Explosive blasting is a very useful tool for mining and civil engineering applications. It, however, may cause severe environmental hazards on adjacent structures due to blasting impact. Blast engineers try to make optimum blast design to provide efficient performance and to minimize the environmental impact as well. It requires a pre-assessment of the impacts resulting from the blasting operation in design stage. One of the common procedures is to evaluate the proposed blast pattern through a series of test blasting in the field. Another approach is to evaluate the possible environmental effects using the numerical methods. There are a number of input parameters to be prepared for the numerical analysis. Some of them are well understood, while some are not. This paper presents some results of sensitivity analysis of the basic input parameters in numerical modelling of blasting problems so as to provide sound understanding of the parameters and some guidelines for input preparation.
졸-겔법으로 성장시킨 Mg<sub>0.3</sub>Zn<sub>0.7</sub>O 박막의 Mg 전구체의 종류에 따른 광학적·구조적 특성에 관한 연구
염아람,김홍승,장낙원,윤영,안형수,Yeom, Ahram,Kim, Hong Seung,Jang, Nak Won,Yun, Young,Ahn, Hyung Soo 한국전기전자재료학회 2020 전기전자재료학회논문지 Vol.33 No.3
In this study, Mg<sub>x</sub>Zn<sub>1-x</sub>O thin films, which can be applied not only to active layers of light-emitting devices (LEDs), such as UV-LEDs, but also to solar cells, high mobility field-effect transistors, and power semiconductor devices, are fabricated using the sol-gel method. ZnO and Mg<sub>0.3</sub>Zn<sub>0.7</sub>O solution synthesized by the sol-gel method and the thin film were grown by spin coating on a Si (100) substrate and sapphire substrate. The solutions are synthesized by dissolving precursor materials in 2-methoxyethanol (2-ME) solvent, and then monoethanolamine (MEA) was added to the mixed solution as a sol stabilizer. Zinc acetate dihydrate is used as a ZnO precursor, while Mg nitrate hexahydrate and Mg acetate tetrahydrate are used as an MgO precursor. Then, the optical and structural characteristics of the fabricated thin films are compared. The molar concentration of the Zn precursor in the solvent is fixed at 0.3 M, and the amount of the Mg precursor is 30% of Mg<sup>2+</sup>/Zn<sup>2+</sup>. The optical characteristics are measured using an UV-vis spectrophotometer, and the transmittance of each wavelength is measured. Structural characteristics are measured using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Composition analyses are performed using energy dispersive X-ray spectroscopy (EDS). The Mg<sub>0.3</sub>Zn<sub>0.7</sub>O thin film was well formed at the ratio of the Mg precursor added regardless of the type of Mg precursor, and the c-axis of the thin film was decreased, while the band gap was increased to 3.56 eV.