• Journal of the Mineralogical Society of Korea
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• v.9 no.1
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• pp.35-42
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• 1996

Polycrystalline ZrH2 in tetragonal crystal system has been compressed in a modified Bassett-type diamond anvil cell up to 36.0 GPa at room temperature. X-ray diffraction data did not indicate any phase transitions at the present pressure range. The pressure dependence of the a-axis, c-axis, c/a and molar volume of ZrH2 was determined at pressures up to 36.0 GPa. Assuming the pressure derivative of the bulk modulus (K0') to be 4.11 from an ultrasonic value on Zr, bulk modulus (K0) was determined to be 160Gpa by fitting the pressure-volume data to the Birch-Murnaghan equation of state. Same sample was heated at $500^{\circ}C$ at the pressure of 9.8 GPa in a modified Sung-type diamond anvil cell. Unloaded and quenched sample revealed that the original tetragonal structure transforms into a hexagonal structured phase with a zero-pressure molar volume change of ~115.5%.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.138-146
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• 2000

Using the ultrasonic interferometry on the single crystal MgO-periclase, adiabatic bulk moduli were determined to be 163.2 GPa and 162.6 GPa from (100) and (110) lattice plane measurements, respectively. Density was measured on polycrystalline MgO by the X-ray diffraction technique. Results from this study were compared with the previously reported values. Further, the present results were converted to the isothermal bulk moduli and, then compared with the published data available including the energy dispersive X-ray diffraction result which was performed on the same single crystal MgO. The principle and techniques ultrasonic interferometry were introduced too.

• Computers and Concrete
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• v.10 no.4
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• pp.349-360
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• 2012

In this paper, compressive strength, water permeability and abrasion resistance of concretes containing high volume fine fly ash (FFA) and fine ground palm oil fuel ash (GPA) were studied. Portland cement type I was replaced with FFA and GPA at dosages up to 70% by weight of binder. Ground river sand (GRS) was also used to replace Portland cement in order to indicate the level of filler effect. Results indicated that FFA was slightly more reactive than GPA. The replacement of 40-70% of FFA produced concretes with compressive strength, permeability and abrasion resistance comparable to those of normal concretes. The incorporation of GPA slightly reduced the performances of concretes as compared to those of FFA concretes. The reduction of Portland cement was partly compensated by the increase in pozzolanic activity of the fine fly ash and palm oil fuel ash and thus enabled the large replacement levels.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.123-124
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• 2007

3성분계 Ti-Si-C 코팅은 PECVD 기술에 의해 WC-Co 기판에 합성되었다. 이 연구에서 Ti-Si-C코팅에서의 비정질 silicon carbide 상의 효과는 XRD, XPS, TEM에 의해 분석되었다. TiC 결정의 입자크기는 비정질 silicon carbide의 침투 현상 때문에 Si의 함유량이 증가됨에 따라 감소된다. Ti-Si-C 코팅은 5.2%의 Si함유량에서 나노크기의 nc-TiC결정과 비정질 a-SiC로 이루어져 있고 최고 경도 33GPa와 탄성율 330GPa를 각각 보여주고 있다. 이 수치들은 순수한 TiC(-21GPa, 260Gpa)보다 눈에 띄게 높아졌다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.128-129
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• 2007

Cr-Al-N, Cr-Si-N 그리고 Cr-Al-Si-N 코팅막을 WC-Co 모재위에 AIP법과 DC 마그네트론 스퍼터링 법을 결합한 하이브리드 시스템을 이용하여 합성하였으며, Si함량에 따른 Cr-Al-Si-N 코팅막의 미세구조, 기계적 특성과 마찰 거동에 관해 비교 연구하였다. Cr-Si-N(${\sim}35GPa$)과 Cr-Al-Si-N(${\sim}55GPa$) 코팅막의 경도값은 CrN(${\sim}23GPa$)과 Cr-Al-N(${\sim}25GPa$) 코팅막과 비교하여 각각 증가하였고, CrN(${\sim}0.50$)과 Cr-Al-N(${\sim}0.84$)의 평균 마찰계수는 Si 함량이 9 at.% 일때, Cr-Si-N(${\sim}0.30$)과 Cr-Al-Si-N(${\sim}0.57$)으로 각각 감소하였다.

• Current Applied Physics
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• v.18 no.11
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• pp.1218-1224
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• 2018

Pressure-dependent structural and morphological changes of two amphibole minerals, tremolite and actinolite, were investigated up to 7.0 GPa using synchrotron X-ray powder diffraction underthree different pressure transmission media (PTM): water (W), $CO_2$ and silicone oil (SI). The elastic response of tremolite and actinolite are found to be dependent on the PTM used. When using water (W) as PTM, tremolite and actinolite show normal volume contractions with bulk moduli of 74(1) and 78(1) GPa, respectively. When using $CO_2$ as PTM, we observe the formation of calcite from tremolite above 3.8(1) GPa, whereas actinolite did not show any carbonation reaction. Under silicone oil PTM, we observe modulated volume contraction behaviors in both samples, compared to water and $CO_2$ PTM, with bulk moduli in the order of 90(1) and 94(4) GPa for tremolite and actinolite, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.176.2-176.2
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• 2015

기존의 트라이볼로지 분석 기법은 macro 영역에서 시료의 강도 및 탄성 등의 물성을 분석하는 정도였으나 Nano-Indenter 분석 기법은 macro 영역보다 더 미세한 nano 영역에서의 시료 물성 분석을 가능하게 해주었다. 따라서 본 연구에서는 시료들의 결정 배양 방향에 따른 Nano-Indenter 압입 각도 차이에 대한 nano 영역에서의 연구를 진행하였다. Si 기판 외에 본 연구에 사용 된 HfN 및 Zr 박막의 시료들은 rf magnetron sputter를 이용하여 약 100 nm 두께로 증착하였다. 각각 시료들에 대한 결정성 확인을 위해 XRD 분석을 실시하였다. 이후 Nano-Indenter를 이용하여 압입 인가력 대비 압입 깊이를 측정하였다. 이 과정에서 Nano-Indenter 압입 각도를 $0^{\circ}$와 $90^{\circ}$로 변화함에 따라 압입 인가력 - 압입 깊이 그래프의 차이를 확인하였고 이를 기준점으로 부터 $10{\mu}m$ 이격시켜 16회 반복 측정과 Weilbull distribution을 통해 신뢰도를 향상시켰다. 측정 결과 Zirconium(Zr) 박막의 경우 21.53 GPa과 22.18 GPa 측정되었으나 Si 기판은 17.46 GPa 16.33 GPa으로, 그리고 HfN 박막의 경우 25.18 GPa과 27.75 GPa으로 상대적으로 큰 차이를 확인하였다. Si 기판과 HfN의 측정결과 Weibull distribution는 75.02와 70.23인 반면 Zr 박막은 30.94로 상대적으로 불균일한 특성을 확인하였다. 이 결과들로부터 각각의 박막 결정 배양 방향에 따른 분석의 한가지 방법으로 Nano-Indenter 분석 기법을 사용할 수 있는 가능성을 확인하였다.

• Smart Structures and Systems
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• v.25 no.4
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• pp.433-446
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• 2020

In this paper the effect of confining pressure and tunnel depth on the ground vertical settlement has been investigated using particle flow code (PFC2D). For this perpuse firstly calibration of PFC2D was performed using both of tensile test and triaxial test. Then a model with dimention of 100 m × 100 m was built. A circular tunnel with diameter of 20 m was drillled in the middle of the model. Also, a rectangular tunnel with wide of 10 m and length of 20 m was drilled in the model. The center of tunnel was situated 15 m, 20 m, 25 m, 30 m, 35 m, 40 m, 45 m, 50 m, 55 m and 60 m below the ground surface. these models are under confining pressure of 0.001 GPa, 0.005 GPa, 0.01 GPa, 0.03 GPa, 0.05 GPa and 0.07 GPa. The results show that the volume of colapce zone is constant by increasing the distance between ground surface and tunnel position. Also, the volume of colapce zone was increased by decreasing of confining pressure. The maximum of settlement occurs at the top of the tunnel roof. The maximum of settlement occurs when center of tunnel was situated 15 m below the ground surface. The settlement decreases by increasing the distance between tunnel center line and measuring circles in the ground surface. The minimum of settlement occurs when center of circular tunnel was situated 60 m below the surface ground. Its to be note that the settlement increase by decreasing the confining pressure.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.1
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• pp.41-46
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• 2012

As the development of MEMS/NEMS structure and application technology the demand for an assessment of the mechanical properties have increased. The mechanical properties are mainly evaluated by using tensile test or ultrasonic wave measurement. However, the new technology have been developed such as nano-indentation, guided wave method because they have a limitation in case of a thin plate and thin film. In the study, the guided wave velocities are measured by electromagnetic-acoustic transducer(EMAT), the material properties of thin metallic foils are obtained using optimization process of the theoretical and experimental group velocity of guided wave. The Young's modulus obtained by the optimization process(201.6 GPa), nano-indentation(207.0 GPa) and literature value(203.7 GPa) of a $50{\mu}m$ thick nickel thin plate shows good agreement within 3%.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.267-272
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• 2010

High pressure x-ray diffraction patterns of ${\alpha}$-cristobalite gallium phosphate ($GaPO_4$) were acquired up to 8.9 GPa at room temperature using Mao-Bell type diamond anvil cell with high flux synchrotron radiation. Starting orthorhombic phase (phase-I) shows the splitting of peak which is possibly resulted from the pressure induced orientation disorder of the framework structure of tetrahedra. This is designated as phase-I'. This phase transforms to the orthorhombic high pressure phase-III between 2 and 3 GPa. Present phase transition sequence is not in accord with the recent high pressure X-ray diffraction results performed on the same starting sample (Ming et al., 2007). X-ray pattern of the unloaded sample to ambient pressure shows that the structure retains that of the high pressure phase prior to decompression.