• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.556-560
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• 2002

The rheological characteristics of PNN-PZT ceramics with high electromechanical coupling factor and electricstrictive constant was investigated. Green sheets of piezoelectric PNN-PZT ceramics were made by tape-casting method with controlling the mixing ratio of a dispersant, an organic binder, and a plasticizer. When the dispersant content was 1 wt.%, the slurry showed the best rheological characteristics for tape casting. The amounts of the plasticizer and the binder was simultaneously varied in the ranges of 1.5~18 and 3~9 wt.%, respectively. When both the plasticizer and binder of 6 wt.% mixed in the solution, respectiveley, the highest green density of the sheet was obtained without macrodefects. Multilyered structures of PNN-PZT/Ag-Pd were successfully fabricated using the optimized tape casting condition. The polarization behavior of these actuators seemed to similar to typical electricstrictive polarization behavior. The multilayer ceramic actuator is about $0.6{\times}10^{-3}$ of strain.

• Korean Institute of Interior Design Journal
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• v.23 no.1
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• pp.3-13
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• 2014

After The Industrial Revolution in 18th century, constructions were done with universal material (concrete) in everywhere instead of using materials that are produced in each country because of development of industry material and transportation. This change caused the buildings to become trite with no local characteristics. Hereupon, the study intends to understand the essence of matter and restore various construction methods of each matter with the topic of 'Immateriality'. Immateriality is the revealed concept based on Materiality. Consequently the process and characteristics of immateriality shown on the works of Kuma Kengo and Herzog & de Meuron, three kinds of features can be found of immateriality expression mode. They are as in the following. First, there is a mode of transforming the shape and properties in physical or psychological way by observer. Second, there is a mode of conflating the shape and properties in physical or psychological way by observer. Third, there is a mode of mixing the shape and properties in physical or psychological way by observer.

• Transactions of Materials Processing
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• v.12 no.5
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• pp.493-497
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• 2003

The present investigation aims at visualizing the crack tip stress field using a mechanoluminescence material. The well known compound $SrAl_2O_4$:$Eu^{2+}$ was adopted as a mechanolurninescence material. Two more trivalent rare-earth elements such as Dy and Nd were taken into consideration as codopants to provide the appropriate trap levels. Samples of a variety of compositions were prepared by varing $Eu^{2+}$, $Dy^{3+}$, and $Nd^{3+}$ doping contents, for which the combinatorial chemistry method was used. In order to search for the optimum composition for the highest mechanoluminescence, the luminescence induced by a compressive device including a CCD camera. In parallel, a compact tension specimen was prepared by mixing the luminescence powders of optimum composition and epoxy resin. Crack initiation from the mechanically machined sharp note tip and its growth during loading were found to be associated with the extent of light emission from $SrAl_2O_4$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.41-49
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• 2021

Cement-mixed polymer-based waterproofing materials are generally used in the form of application by mixing in the field, and it is necessary to supplement the construction ability for air bubbles and uneven coating thickness due to irregularities during construction. The final purpose of this study is to improve the waterproofing performance by adding a sheet attaching process to the composite construction rather than the single process of painting and applying the construction method when applying the polymer waterproofing material to the field. In this regard, the applicability was evaluated by examining the material, environment, and manufacturing method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.2
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• pp.215-222
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• 2024

Ni-rich cathode materials have been developed as the most promising candidates for next-generation cathode materials for lithium-ion batteries because of their high capacity and energy density. In particular, the electrochemical performance of lithium-ion batteries could be enhanced by increasing the contents of nickel ion. However, there are still limitations, such as low structural stability, cation mixing, low capacity retention and poor rate capability. Herein, we have successfully developed the nanorod-type Ni-rich cathode materials by using co-precipitation method. Particularly, the nanorod-type primary particles of LiNi_0.7Co_0.15Mn_0.15O₂ could facilitate the electron transfer because of their longitudinal morphology. Moreover, there were holes at the center of secondary particles, resulting in high permeability of the electrolyte. Lithium-ion batteries using the prepared nanorod-type LiNi_0.7Co_0.15Mn_0.15O₂ achieved highly improved electrochemical performance with a superior rate capability during battery cycling.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.3
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• pp.103-111
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• 2021

Hexagonal shape Si crystals were grown by the mixed-source hydride vapor phase epitaxy (HVPE) method of mixing solid materials such as Si, Al and Ga. In the newly designed atmospheric pressure mixed-source HVPE method, nuclei are formed by the interaction between GaCl_n, AlCl_n and SiCl_n gases at a high temperature of 1200℃. In addition, it is designed to generate a precursor gas with a high partial pressure due to the rapid reaction of Si and HCl gas. The properties of hexagonal Si crystals were investigated through scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), high-resolution X-ray diffraction (HR-XRD), and Raman spectrum. From these results, it is expected to be applied as a new material in the Si industry.

• Journal of Institute of Convergence Technology
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• v.6 no.2
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• pp.35-40
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• 2016

Ignitor tip is a component of burner to start the burning process in power plant. This is used to ignite the coal to a constant operating state by fuel mixed with air and kerosene. This component is composed of three components so that air and kerosene are mixed in the proper ratio and injected uniformly. Because the parts with the designed shape are manufactured in the machining process, they have to be made of three parts. These parts are designed to have various functions in each part. The mixing part mixes the supplied air and kerosene through the six holes and sends it to the injecting part at the proper ratio. The inject part injects mixed fuel, which is led to have a constant rotational direction in the connecting part, to the burner. And the connecting plate that the mixed fuel could rotate and spray is assembled so that the flame can be injected uniformly. But this part causes problems that are worn by vibration and rotation because it is mechanically assembled between the mixing part and the inject part. In this study, 3D printing method is used to integrate a connecting plate and an inject part to solve this wear problem. The 3D printing method could make this integrated part because the process is carried out layer by layer using a metal powder material. The part manufactured by 3D printing process should perform the post process such as support removal and surface treatment. However, while performing the 3D printing process, the material properties of the metal powders are changed by the laser sintering process. This change in material properties makes the post process difficult. In consideration of these variables, we have studied the optimization of manufacturing process using 3D printing method.

• Journal of Mechanical Science and Technology
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• v.20 no.4
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• pp.473-481
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• 2006

Predicting fatigue life by numerical methods was almost impossible in the field of rubber materials. One of the reasons is that there is not obvious fracture criteria caused by nonstandardization of material and excessively various way of mixing process. But, tearing energy as fracture factor can be applied to a rubber-like material regardless of different types of fillers, relative to other fracture factors and the crack growth process of rubber could be considered as the whole fatigue failure process by the existence of potential defects in industrial rubber components. This characteristic of fatigue failure could make it possible to predict the fatigue life of rubber components in theoretical way. FESEM photographs of the surface of industrial rubber components were analyzed for verifying the existence and distribution of potential defects. For the prediction of fatigue life, theoretical way of evaluating tearing energy for the general shape of test-piece was proposed. Also, algebraic expression for the prediction of fatigue life was derived from the rough cut growth rate equation and verified by comparing with experimental fatigue lives of dumbbell fatigue specimen in various loading condition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.16-19
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• 2002

(Ba,Sr)TiO3(BST) thin film is an attractive material for the application in high-density dynamic random access memories (DRAMs) because of the high relative dielectric constant and small variation in dielectric properties with frequency. In this study, (Ba0.6,Sr0.4)TiO3 thin films on Pt/Ti/SiO2/Si substrates were deposited by a sol-gel method and the CF4/Ar inductively coupled plasma (ICP) etching behavior of BST thin films had been investigatedby varying the process parameters such as chamber pressure, ICP power, and substrate bias voltage. To analysis the composition of surface residue following etching BST films etched with different Ar/CF4 gas mixing ratio were investigated using x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometer (SIMS).

• Journal of the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.105-112
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• 2005

This is to find out that cement mortar mixed with waste tie particle can be applied for recycling it and enhanced to have shock absorption capacity. Therefore, architectural material specification and its related references for the disposal of it are based on for the study. Test has been performed with procedure, based on the Korea Standard insulation mortar and Compressive Strength Test has been done at K remicon factory approved by Korea Government in Korea, in order to decrease any possible error in mixing procedure. Test molds far insulation capacity and cohesive strength have been delivered to the expert agency for having more exact results. The result from the above test shows that waste tyre mixed with cement mortar has almost equal to the common concrete. This means that the recycling of the waste t)re will be demanded more and more in case of having continued development for this recycling area. And also waste t)to-using construction material can be more applied for construction area than existing material. Thus, this recycling method can be very usefully applied for solving environmental problem and for establishing economic aspect.