• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.123-126
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• 2007

Deformation behavior of $Zr_{55}Cu_{30}Al_{10}Ni_5$ (at. %) bulk metallic glass (BMG) fabricated by suction casting method has been investigated at elevated temperatures in this study. The BMG was first verified to have an amorphous structure thru X-ray diffraction (XRD) and differential scanning calorimetry (DSC). A series of compression tests has consequently been performed in supercooled liquid temperature region to investigate the high temperature deformation behavior. A transition from Newtonian to non-Newtonian flow appeared to take place depending upon both the strain rate and test temperature. A processing map based on a dynamic materials model has been constructed to estimate a feasible forming condition for this BMG alloy.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.445-446
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• 2002

The purpose of this study was to investigate the effect of micro holes, pattern structure and elastic modulus of pads on the polishing behavior such as the removal rate and WIWNU (within wafer non-uniformity) during CMP. The regular holes on the pad act as the superior abrasive particle's reservoir and regular distributor at the bulk pad, respectively. The superior CMP performance was observed at the laser processed bulk pad with holes. Also, th ε groove pattern shape was very important for the effective polishing. Wave grooved pad showed higher removal rates than K-grooved pad. The removal rate was linearly increased as the top pad's elastic modulus increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.76-79
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• 2000

The $Ba(Zn_{1/3}Ta_{2/3})O_3$ ceramics were prepared by conventional mixed oxide method. The structural properties of the BZT ceramics with the sintering temperature were investigated by XRD, SEM. The BZT ceramics have a complex-perovskite structure. The BZT ceramics sintered at $1550^{\circ}C$ had a superstructure plane of BZT(100). Increasing the sintering temperature, the bulk density and ordering were increased. The bulk density of the BZT ceramics sintered at $1550^{\circ}C$ was $7.50[g/cm^3]$. Increasing the sintering temperature, the average grain size were increased and pore were decreased.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1410-1415
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• 2007

Recently introduced WBK(Wire-wounded Bulk Kagome) shows relatively superior mechanical properties compared to other types of PCM. WBK is fabricated by assembling helical wires in 6 directions. Wire being a helix, the wire's geometric properties like pitch and helical radius shows certain geometric characteristics which can play some critical role in setting up an automatic fabrication process. In this study, geometry of WBK is modeled by various transformations of a piece of helical wire and the characteristics of the geometry of an element of WBK truss are discussed. In addition, the roles of pitch and helical radius of wire in optimizing the assembling process are described and the derivation of criteria is attempted to decide proper helical radius which would maintain minimal interference between wires at the crossings.

• 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%.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.127-130
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• 1989

This paper reports the theoretical model and the experimental results regarding to the electrical conductivity of hydrogenated amorphous silicon (a-Si:H). The total effective conductance of a-Si:H with a planar structure has been considered as the sum of the conductance of an adsorbate-induced layer, a surface-interface layer, a bulk layer, and a substrate-interface layer. In order to investigate the effects of space charge layers in a-Si:H on the conductivity, the thickness dependence of the conductivity is characterized and the conductivities measured at the upper electrodes deposited on a-Si:H are compared with those measured at the lower electrodes deposited on the glass substrate. From our analysis, the bulk conductivity and the thickness of the space charge layer in a-Si:H are characterized quantitatively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.353-359
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• 2009

Wire-woven Bulk Kagome (WBK) is a new truss type cellular metal fabricated by systematic assembling of helical wires in six directions. In this work, the experiments of mechanical behaviors of WBK cored sandwich panels subjected to bending load were performed and the results were compared with those by the corresponding analytic solutions. And also, finite element simulations were performed to validate the optimal design according to the analytic solutions. It is found the sandwich panel with WBK core performed excellently in terms of energy absorption and deformation stability after the peak point as well as the load capacity.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.309-312
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• 2007

Deformation behavior of $Zr_{55}Cu_{30}Al_{10}Ni_5$(at. %) bulk metallic glass(BMG) fabricated by suction casting method has been investigated at elevated temperatures in this study. The BMG was first verified to have an amorphous structure with the analysis of X-ray diffraction(XRD) and differential scanning calorimetry(DSC) data. A series of compression tests has consequently been performed in the region of supercooled liquid temperature to investigate the behavior of high temperature deformation. A transition from Newtonian to non-Newtonian flow appeared to take place depending upon both the strain rate and test temperature. A processing map based on a dynamic materials model has been constructed to estimate a feasible forming condition for this BMG alloy.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.5
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• pp.63-69
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• 2001

The main purpose of this study is to seek desalinization effect of subsurface drainage system with rice hull packing in Dae-Ho Reclaimed Land. After 4 years installed sub-surface drainage system, distribution of drained water electric conductivity (ECw) was 4.43~12.78 ds/m. The soil profile showed partial development of the soil structure and compaction of subsoils with increased bulk density. The bulk density of the subsoil was 1.42~1.66 g/cm$^3$, which might limit root growth. The soil color changed near the drainage pipe line. Distribution of soil extract solution ECe and SAR as subsurface drainage pipe position and drainage canal distance showed desalinization effect of subsurface drainage system with rice hull packing as widening effective zone of subsurface drainage pipe.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.441-447
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• 2017

본 논문에서는 다양한 원소 조합을 통한 다양한 특성과 2D 구조의 형성이 가능한 물질로서 최근 많은 응용에 활용되고 있는 TMD물질에 대하여 strain 엔지니어링 방법을 탐색하고자 하였다. 에디슨 나노물리의 LCAO 기반 DFT 전자구조계산 SW를 이용해 4, 5, 6족의 TMD물질($MX_2$, M = Zr, Nb, Mo; X = S, Se, Te)의 monolayer, bulk 상태에 strain을 가했을 때 전자 구조의 변화를 계산하였다. Band gap 크기, 전자의 effective mass의 변화, direct-indirect gap transition 등을 전이금속의 종류에 따라 분류하여 분석할 수 있었다.