• Journal of Korean Neurosurgical Society
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• v.64 no.4
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• pp.562-574
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• 2021

Objective : This study is to evaluate the efficacy and safety of demineralized bone matrix (DBM) gel versus DBM gel with recombinant human bone morphogenetic protein-2 (rhBMP-2) used in transforaminal lumbar interbody fusion (TLIF). Methods : This study was designed as a prospective, multi-center, double-blind method, randomized study. All randomized subjects underwent TLIF with DBM gel with rhBMP-2 group (40 patients) as an experimental group or DBM gel group (36 patients) as a control group. Post-operative observations were performed at 12, 24, and 48 weeks. The spinal fusion rate on computed tomography scans and X-rays films, Visual analog scale pain scores, Oswestry disability index and SF-36 quality of life (QOL) scores were used for the efficacy evaluation. The incidence rate of adverse device effects (ADEs) and serious adverse device effects (SADEs) were used for safety evaluation. Results : The spinal fusion rate at 12 weeks for the DBM gel with rhBMP-2 group was higher with 73.68% compared to 58.82% for the DBM gel group. The 24 and 48 weeks were 72.22% and 82.86% for the DBM gel with rhBMP-2 group and 78.79% and 78.13%, respectively, for the DBM gel group. However, there were no significant differences between two groups in the spinal fusion rate at 12, 24, and 48 weeks post-treatment (p=0.1817, p=0.5272, p=0.6247). There was no significant difference between the two groups in the incidence rate of ADEs (p=0.3836). For ADEs in the experimental group, 'Pyrexia' (5.00%) was the most common ADE, followed by 'Hypesthesia', 'Paresthesia', 'Transient peripheral paralysis', 'Spondylitis' and 'Insomnia' (2.50%, respectively). ADEs reported in control group included 'Pyrexia', 'Chest discomfort', 'Pain', 'Osteoarthritis', 'Nephropathy toxic', 'Neurogenic bladder', 'Liver function analyses' and 'Urticaria' (2.86%, respectively). There was no significant difference between the two groups in the incidence rate of SADEs (p=0.6594). For SADE in the experimental group, ''Pyrexia' and 'Spondylitis' were 2.50%. SADE reported in the control group included 'Chest discomfort', 'Osteoarthritis' and 'Neurogenic bladder'. All SADEs described above were resolved after medical treatment. Conclusion : This study demonstrated that the spinal fusion rates of DBM gel group and DBM gel with rhBMP-2 group were not significantly different. But, this study provides knowledge regarding the earlier postoperative effect of rhBMP-2 containing DBM gel and also supports the idea that the longer term follow-up results are essential to confirm the safety and effectiveness.

• Korean Journal of Materials Research
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• v.22 no.6
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• pp.292-297
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• 2012

In order to improve osseointegration of dental implants with bone we studied an implant with holes inside its body to deliver bioactive materials based on a proposed patent. Bioactive materials can be selectively applied through holes to a patient according to diagnosis and the integration progress. After the bioactive material is applied, bone can grow into the holes to increase implant bonding and also enhance surface integration. In order to improve the concept and study the effect of bioactive material injection on implant integration, design optimization and integration research were undertaken utilizing the finite element method. A 2-dimensional simulation study showed that when bone grew into the holes after the bioactive material was injected, stress vertically distributed in the upper part of the implant was relieved and mild stress appeared at the opening of the injection holes. This confirmed the effect of the bioactive material and the contribution of the injection holes, but the maximum stress increased ten-fold at the opening. In order to reduce the maximum stress, the size, location, and the number of holes were varied and the effects were studied. When bioactive materials formed an interface layer between the implant and the mandible and four holes were filled with cortical and cancellous bones all the stress concentrated opposite to the loading side without holes disappeared. The stresses at the four outlets of the holes was mildly elevated but the maximum stress value was ten-fold greater compared to the case without the bioactive material.

• Tribology and Lubricants
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• v.28 no.4
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• pp.173-177
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• 2012

We used contact resonance force microscopy (CRFM) technique to determine the quantitative elastic properties of multiple materials integrated on the sub micrometer scale. The CRFM approach measures the frequencies of an AFM cantilever's first two flexural resonances while in contact with a material. The plain strain modulus of an unknown or test material can be obtained by comparing the resonant spectrum of the test material to that of a reference material. In this study we examined the following bumping materials for flip chip by using copper electrode as a reference material: NiP, Solder (Sn-Au-Cu alloy) and under filled epoxy. Data were analyzed by conventional beam dynamics and contact dynamics. The results showed a good agreement (~15% difference) with corresponding values determined by nanoindentaion. These results provide insight into the use of CRFM methods to attain reliable and accurate measurements of elastic properties of materials on the nanoscale.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.561-565
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• 2007

Because of a good wear resistance and a stable contact resistance, Ag-CdO is widely used as electrical contact material. But, the Cd-oxide mainly exists as a coarse particle and adversely affected to environment. As a reason, $Ag-SnO_2$ alloy has been developed. The Sn-oxide maintains stable and fine particle even at high temperature. In order to investigate the effect of Misch metal (Mm) additional that affects the formation of the oxide and the formation of fine matrix Ag, we studied the microstructures and properties of Ag-Sn-In(-Mm) material fabricated by rapid solidification process. The experimental procedure were melting using high frequency induction, melt spinning, and internal oxidation. The Mm addition makes Ag matrix more fine than no Mm addition. The reason is that the addition of Misch metal decreased a latent heat of fusion of alloy, as a result the rapid solidification effect of alloy is increased. The maximum hardness shows at 0.3 wt%Mm. after that the hardness is decreased until 0.4 wt% Mm, but still larger than no Mm addition alloy. At 0.5 wt% Mm alloy, the precipitation of Misch metal causes a decrease of hardness than no Mm addition alloy.

• Korean Journal of Human Ecology
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• v.17 no.6
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• pp.1205-1213
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• 2008

Material is a factor for maximizing formative aspect among fashion design factors. Therefore, central axis of modern fashion is performing various trials for escaping from existing cloth and searching for artistic value. Especially, Korean paper is a formative material, which is manufactured through traditional manual work in Korea. The material is used in various fields on the basis of its aesthetic feature. Especially, fashion field performs handcraft activity on the basis of mulberry pulp, which is a prime material of Korean paper. Because the activity can be reinterpreted by world designers, who want to find motive of fashion material in the third world, it is necessary to perform experimental study for developing expressive form on the basis of diversity of Korean paper material. Therefore, the purpose of this study is to perform experimental study by focusing on the development of Korean paper material in order to express formative feature. The study purposes are as follows. The first purpose is to reinterprete the theory through actual work of fiber formation using Korean paper in the current flow where art and design field are fused and compromised. The second purpose is to suggest vision of material development on the basis of formative feature to fashion world focusing its eyesight to Asia and the third countries. The study results are as follows. First, Korean paper has been evaluated as proper material for the fusion of design and art because of its handicraft feature, long-term preservation, heat insulation, absorption, diversity and eastern feature. Second, the study performed various trials for artistic dress material by developing 12 Korean paper works and suggested the development of new material on the basis of formative feature of modem fashion industry.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.235-242
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• 2016

The purpose of this study is an attempt to improve the functionality of a conventional Fused Deposition Modeling (FDM) process using the Automatic Tool Changer (ATC) to perform multimaterial production and post-processing. Hybrid-FDM means a fusion of an Additive Manufacturing process and grinding process using the ATC system. In order to enhance the potentiality of production capacity for multi-material fabrication and surface roughness improvement, two extrusion tools and one grinding tool system are suggested. A pneumatic chuck is attached on a moving platform in the XY axes plane and an extrusion head and grinding head are placed in a docking station, allowing for a quick changeover with each other. Therefore, the manufacturing lead time can be reduced efficiently for the fabrication of a product.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.1
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• pp.48-52
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• 2014

In this paper, scaling down characteristics of vertical channel phase random access memory are investigated with device simulator and finite element analysis simulator. Electrical properties of select transistor are obtained by device simulator and those of phase change material are obtained by finite element analysis simulator. From the fusion of both data, scaling properties of vertical channel phase change random access memory (VPCRAM) are considered with ITRS roadmap. Simulation of set reset current are carried out to analyze the feasibility of scaling down and compared with values in ITRS roadmap. Simulation results show that width and length ratio of the phase change material (PCM) is key parameter of scaling down in VPCRAM. Thermal simulation results provide the design guideline of VPCRAM. Optimization of phase change material in VPCRAM can be achieved by oxide sidewall process optimization.

• Journal of Environmental Science International
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• v.31 no.10
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• pp.833-844
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• 2022

A zeolite material with a Si/Al molar ratio of 1.2 was synthesized by changing the NaOH/CFA ratio of coal fly ash (CFA) via a fusion/hydrothermal reaction in the HD thermal power plant. The change in the crystal structure of the zeolite was confirmed using XRD and SEM, and the ammonia adsorption capacities of the synthesized zeolitic materials and a commercial zeolite (Na-A zeolite) were analyzed via an ammonia temperature-programmed desorption (NH₃-TPD) process. The SEM and XRD results revealed out the zeolitic materials from the coal fly ash maintained a hexagonal Linde-type crystal structure similar to that of Na-A zeolite, but the crystallinity of the synthesized zeolitic material was reduced due to impurities. The NH₃ adsorption capacity, determined from the NH₃-TPD analysis of was 1.122 mmol/g of the synthesized zeolitic material, which was lower than the NH₃ adsorption capacity of the Na-A zeolite.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.3
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• pp.96-102
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• 2020

In this paper, AlN epilayers on 6H-SiC (0001) substrate are grown by mixed source hydride vapor phase epitaxy (MS-HVPE). AlN epilayer of 0.5 ㎛ thickness was obtained with a growth rate of 5 nm per hour. The surface of AlN epilayer grown on 6H-SiC (0001) substrate was investigated by field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Dislocation density was considered through HR-XRD and related calculations. A fine crystalline AlN epilayer with screw dislocation density of 1.4 × 10⁹ cm^-2 and edge dislocation density of 3.8 × 10⁹ cm^-2 was confirmed. The AlN epilayer on 6H-SiC (0001) substrate grown by using the mixed source HVPE method could be applied to power devices.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.7-15
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• 2012

Semiconductor packages are increasingly moving toward miniaturization, lighter and multi-functions for mobile application, which requires highly integrated multi-stack package. To meet the industrial demand, the package and silicon chip become thinner, and ultra-thin packages will show serious reliability problems such as warpage, crack and other failures. These problems are mainly caused by the mismatch of various package materials and geometric dimensions. In this study we perform the numerical analysis of the warpage deformation and thermal stress of 4-layer stacked FBGA package after EMC molding and reflow process, respectively. After EMC molding and reflow process, the package exhibits the different warpage characteristics due to the temperature-dependent material properties. Key material properties which affect the warpage of package are investigated such as the elastic moduli and CTEs of EMC and PCB. It is found that CTE of EMC material is the dominant factor which controls the warpage. The results of RSM optimization of the material properties demonstrate that warpage can be reduced by $28{\mu}m$. As the silicon die becomes thinner, the maximum stress of each die is increased. In particular, the stress of the top die is substantially increased at the outer edge of the die. This stress concentration will lead to the failure of the package. Therefore, proper selection of package material and structural design are essential for the ultra-thin die packages.