• 한국레이저가공학회지
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• 제2권2호
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• pp.27-33
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• 1999

Electron beam was applied on the low carbon steel in order to fabricate Metal/Metal GBM(Graded Boundary Material). Ni sheet was placed on the steel substrate. The electron beam was irradiated on the surface and produced a homogeous alloyed layer. Sequential repetition of electron beam treatments for 4 times resulted in 8mm thick graded layer. To determine each layers property, optical microscopy, XRD, microhardness tester and EDS were used. The residual stress was measured by the low angle x-ray diffraction method. The graded boundary layer was stepwise profile, but Ni content incresed up to 80 wt% and Fe content decreased 20 wt% near surface. Each layers microstructure and hardness varied by different Fe/Ni composition. The compressive residual stress was induced by martensite transformation in the 1st and End layers and the shrinkage cracks were formed in graded layer by rapid cooling.

• 한국의류학회지
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• 제21권8호
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• pp.1346-1352
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• 1997

The purpose of this study was to help the consumer as well as the producer by investigating the properties such as tensile strength, extention, tear strength, wrinkle recovery, drapability, bending property, moisture regain, and shrinkage on commercial polyurethane coated fabrics. Seven commercial polyurethane coated fabrics having various base fabrics were used. The performance properties of base fabrics and polyurethane coated fabrics were measured. The relationships between base fabrics and polyurethane coated fabrics on the performance properties were identified. It was concluded that the properties of polyurethane coated fabric mainly depend on the characteristics of base fabric. Therefore the proper use of base fabric is recommended in order to improve the performance of polyurethane coated fabric.

• 한국전기전자재료학회논문지
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• 제13권4호
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• pp.343-348
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• 2000

NCZF ferrites doped with B-Bi-Zn(35-25-40) glass ceramics were prepared to investigate the magnetic properties. The XRD peaks of all of samples were observed only spinel phase. As the additive increased at sintering temperature 750$^{\circ}C$ and 850$^{\circ}C$ for 3 hours, the density and shrinkage of the samples increased until 5.28 g/cm$^3$ and 20% respectively. And other samples showed constant trends having the density about 5.4g/cm$^3$. According to SEM images the growth of grain progressed rapidly at sintering temperature of 850$^{\circ}C$ for 3 hours. Increasing the additive initial permeability and complex permeability decreased. The high values of complex permeability as a function of frequency showed that NCZF doped with 3 wt%, 5wt%, samples at sintered temperature of 850$^{\circ}C$/3h and 900$^{\circ}C$/3h.

• Design & Manufacturing
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• 제14권3호
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• pp.31-36
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• 2020

In injection molding processes, the property of molten resin should be characterized accurately. Among several properties, the PvT state is the most important one, since it affects the shrinkage, warpage, molded weight, and the part density. Thus, the PvT data is crucial to the simulation of the injection molding process. This work shows how such a measurement can be performed for a semi-crystalline and amorphous polymers. The PvT measurement has been conducted using a capillary rheometer using a suitable accessory that blocks the capillary. The results have shown that the PvT data can be obtained using such a rheometer and then the PvT coefficients of the Tait equation can be reached.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.45-48
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• 2005

Self compacting concrete has the strong point in capability of concrete to be uniformly filled and compacted in every corners of formwork by its self-weight without vibration during placing. However, powder type self compacting concrete has the weak point in the heat of hydration, the drying shrinkage and the elastic property of concrete etc. Recently viscosity agent has been developed in order to overcome these weaknesses. In this study, self compacting concrete is made with viscosity agent based on polysaccharide derivative in order to develope the normal strength self compacting concrete. Slump flow, loss of slump flow and setting time are measured for comparison with normal concrete. Compressive strength, freezing and thawing test and carbonation test are conducted on normal and self compacting concrete using viscosity agent. In the experiment, we acquired good results in fresh and hardened self compacting concrete using viscosity agent based on polysaccharide derivative.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.80-83
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• 1999

We have studied properties(crystal structure, density, absorption, contraction, initial permeability, and permeability) of Ni$_{0.175-x}$Cu$_{x}$Zn$_{0.33}$Fe$_{0.495}$ (x=0~0.175) ferrites with various NiO and CuO, because of development of materials for high frequency inductor. The XRD peaks of all of samples were observed only spine이 phase. As a results of the density, absorption rate, and shrinkage rate, the grain growth progressed rapidly in x=0.1 at 95$0^{\circ}C$, x=0.075 at 105$0^{\circ}C$, and x=0.025 at 115$0^{\circ}C$ for 3 hours. Initial permeability increased with increasing CuO concentration until x=0.1, and then decreased. The complex permeability as a function frequency were high values at sintered 105$0^{\circ}C$ fotr3 hours in x=0.075, 0.1., 0.1.1.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.205-208
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• 1999

We have studied properties(crystal structure, density, absorption, contraction, initial permeability, and permeability) of Ba$\sub$0.2/Me$\sub$0.31/Fe$\sub$0.49/(Me:Ni$\sub$1-x/, Cu$\sub$x/ x=0~1) ferrites with various Me site, because of development of magnetic materials for inductor. As a results of the density, absorption rate, and shrinkage rate, the sintering temperature of Ba$\sub$0.2/ Me$\sub$0.31/ FEesub 0.49/(Me:Ni$\sub$1-x/ x=0.25, 0.75) had got over 1100$^{\circ}C$ for 3 hours. According to SEM images, the configurations of grain were hexagonal, Increasing the sintering temperature, initial Permeability increased. The complex permeabilities as a function of for several MHz showed constants.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.89-92
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• 1999

NCZF ferrites doped with B-Bi-Zn(35-25-40) glass ceramics were prepared to investigate the magnetic properties. The XRD peaks of all of samples were observed only spinel phase. As the additive increased at sintering temperature 750$^{\circ}C$ and 850$^{\circ}C$ for 3 hours, the density and shrinkage increased until 5.28g/㎤ and 20%, respectively. According to SEM images, the growth of grain progressed rapidly at sintering temperature 850$^{\circ}C$ for 3 hours. Increasing the additive, initial permeability and complex permeability decreased. The complex permeabilities as a function of frequency showed high values at a12, a16, b11 and b16 sarmples.

• 한국전기전자재료학회논문지
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• 제32권1호
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• pp.58-63
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• 2019

Lithium-ion batteries used for IT, automobiles, and industrial energy-storage devices have battery management systems (BMS) to protect the battery from abnormal voltage, current, and temperature environments, as well as safety devices like, current interruption device (CID), fuse, and vent to obtain positive temperature coefficient (PTC). Nonetheless, there are harmful to human health and property and damage the brand image of the manufacturer because of smoke, fire, and explosion of lithium battery packs. In this paper, we propose a systematic protection algorithm combining battery temperature, over-current, and interconnection between protection elements to prevent copper deposition, internal short circuit, and separator shrinkage due to frequent and instantaneous over-current discharges. The parameters of the proposed algorithm are suggested to utilize the experimental data in consideration of battery pack operating conditions and malicious conditions.

• 한국기계가공학회지
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• 제20권8호
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• pp.52-59
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• 2021

In this study, we experimentally evaluated the mechanical properties and geometric form accuracy in FDM 3D printing processes based on the printing direction, building direction, and layer thickness. The specimen test results showed that the tensile strength increased by over 33% in the printing direction compared to the direction perpendicular to printing and the tensile strength becomes larger as the layer thickness decreased. Furthermore, the tensile and impact strengths in the building direction were significantly reduced due to the difference in the interlayer joining and bonding strengths of the fused material. Additionally, shrinkage of the material due to phase change induced curl distortion especially in thin and long 3D-printed products, which increased as the layer thickness increased.