• Journal of Powder Materials
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• v.19 no.4
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• pp.247-252
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• 2012

Effect of Cu and $DyF_3$ powder mixing with Cu-free (Nd, Dy)-Fe-B jet-milled powder on the magnetic properties of sintered magnets was investigated. The coercivity of a magnet prepared from the Cu-free (Nd, Dy)-Fe-B powder was about 10 kOe even though the alloy powder already contained some Dy (3.5 wt%). When small copper powder was blended, however, the coercivity of the magnet increased almost 100%, exhibiting about 20 kOe. On the contrary, the coercivity enhancement was moderate, about 4 kOe, when dysprosium content in the sintered magnet was simply increased to 4.9 wt% by the addition of small $DyF_3$3 powder.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.42.4-42
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• 1998

• Proceedings of the PSK Conference
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• 2001.04a
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• pp.121.1-121.1
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• 2001

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.834-843
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• 2016

In this paper, the design of a PIN diode S-band transfer-type SP4T including its driver circuit is presented. Each path of the SP4T is composed of the cascade connection of series-shunt PIN diodes to improve the isolation performance. The SP4T is implemented using chip type PIN diodes and a 20 mil AIN substrate fabricated using thin film technology. The driver circuit for the SP4T is designed using a multiplexer and four NMOS-PMOS push-pull pair. From on-wafer measurement, the fabriacted SP4T shows a maximum insertion loss of 1.1 dB and a minimum isolation of 41 dB. The time performance of the driver circuit is evaluated using the packaged PIN diodes with the identical PIN diode chip, and the transition time for on-off and off-on are below 100 nsec. For an input power level of 150 W, the measured insertion loss and isolation are close to those of the on-wafer measurement taking into consideration of the coaxial package mismatch and insertion loss.

• Biomedical Science Letters
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• v.13 no.4
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• pp.325-332
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• 2007

Cell-mediated immune response (CMI) is a major immune protective mechanism against tuberculosis (TB) infection. Among several components involved in CMI, recent studies suggest that CD8+ T cells are important in controlling TB infection. In our previous report, we defined four Mycobacterium tuberculosis (MTB) derived epiotpe peptides specific for HLA-A*0201-restricted CD8+ T cells. These four peptides are $PstAl_{75-83}$, $ThyA_{30-38}$, $RpoB_{127-135}$ and $85B_{15-23}$. In this study, these epitope peptides specific CD8+ T cell responses in tuberculous pleurisy were investigated using ex vivo $IFN-\gamma$ elispot assay and intracellular $IFN-\gamma$ staining method. As a result, we observed these epitope peptide specific CD8+ T cell responses are induced in all three patients with tuberculous pleurisy suggesting that CD8+ T cells are involved in protective immune mechanism against MTB infection in tuberculous pleurisy. However, the CMI to mitogens and MTB antigens from pleural fluids of patients with tuberculous pleurisy does not seem to correlate with that from peripheral blood, although the sample size is too small to make any conclusion. In sum, the MHC I restricted CD8+ T cell responses seem to be induced efficiently in the pleural fluids, at the site of TB infection, in which the CMI is actively induced. In addition, these experiments suggest that MHC I restricted CD8+ T cell mediated immune responses are also involved in protective mechanism against MTB infection in extra-pulmonary TB.

• Food Science of Animal Resources
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• v.37 no.4
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• pp.511-517
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• 2017

This study was conducted to investigate the effect of different feeding regimes on the quality of deer meat (venison) following storage at $4^{\circ}C$ for various durations. Twelve 5-year-old elk stags about 350 kg were stratified by weight and randomly assigned to one of four dietary treatments (three elk stags per treatment). The dietary treatments consisted of a feeding concentrate of 1.5% of body weight (T1), feeding concentrate of 1.8% of body weight (T2), feeding concentrate ad libitum (T3), or a home-mixed ration ad libitum (T4). The pH values of deer meat were not significantly different among treatment groups but were affected by duration of storage. Cooking loss increased under T4 treatment with increasing storage time at $4^{\circ}C$ (p<0.05). Increased storage time also resulted in significant decreases in shear force under T2 and T3 treatment compared to that under other dietary treatments (p<0.05). Lightness ($L^*$), redness ($a^*$), and yellowness ($b^*$) parameters were not significantly different among treatment groups, but lower values of $a^*$ and $b^*$ were observed under T1 and T4 treatment with increasing durations of storage (p<0.05). The chemical and fatty acid composition had no significantly different among treatments. Therefore, meat quality was most affected by increased storage time at $4^{\circ}C$. These results may serve as the basis for further study of deer meat (venison) from Korea.

• Progress in Superconductivity and Cryogenics
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• v.19 no.1
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• pp.36-41
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• 2017

The effects of $MgB_4$ addition on the superconducting properties and the microstructure of in situ processed $MgB_2$ bulk superconductors were studied. $MgB_4$ powder of 1-20 wt.% was mixed with (Mg + 2B) powder and then pressed into pellets. The pellets of (Mg + 2B + $xMgB_4$) were heat-treated at $650^{\circ}C$ for 1 h in flowing argon. The powder X-ray diffraction (XRD) analysis for the heat-treated samples showed that the major formed phase in all samples was $MgB_2$ and the minor phases were $MgB_4$ and MgO. The full width at half maximum (FWHM) values showed that the grain size of $MgB_2$ decreased as the amount of $MgB_4$ addition increased. $MgB_4$ particles included in a $MgB_2$ matrix is considered to suppress the grain growth of $MgB_2$. The onset temperatures ($T_{c,onset}$) of $MgB_2$ with $MgB_4$ addition (0-10 wt.%) was between 37-38 K. The 20 wt.% $MgB_4$ addition slightly reduced the $T_{c,onset}$ of $MgB_2$ to 36.5 K. This result indicates that $MgB_4$ addition did not influence the superconducting transition temperature ($T_c$) of $MgB_2$ significantly. On the other hand, the small additions of 1-5 wt.% $MgB_4$ increased the critical current density ($J_c$) of $MgB_2$. The $J_c$ enhancement by $MgB_4$ addition is attributed not only to the grain size refinement but also to the possible flux pinning of $MgB_4$ particles dispersed in a $MgB_2$ matrix.

• Journal of Magnetics
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• v.11 no.1
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• pp.25-29
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• 2006

Recent experiments have demonstrated high TMR ratios in MTJs with the MgO barrier [1,2]. The CoFeB/MgO/CoFeB junctions showed better properties than the CoFe/MgO/CoFe junctions because the MgO layer had a good crystalline structure with (001) texture and smooth and sharp interface between CoFeB/MgO [3]. The amorphous CoFeB with 20 at%B starts the crystallization at $340^{\circ}C$ [4] and this crystallization of the CoFeB helps obtaining the high TMR ratio. In this work, the compositional changes in the MgO barrier and at the interface of CoFeB/MgO/CoFeB after the CoFeB crystallization were studied in annealed MTJs. XPS depth profiles were utilized. TEM analyses showed that the MgO barrier had (100) texture on CoFeB in the junctions. B in the bottom CoFeB layer diffused into the MgO barrier and B-oxide was formed at the interface of CoFeB/MgO/CoFeB after the CoFeB crystallization.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.2
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• pp.145-151
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• 2004

According to the development of the aircraft industry, the fatigue strength of Aluminum Alloy becomes a great important material, but it seems that we don't understand an effect on the crack growth behaviour very well. This thesis is not only studied about the five kinds of 2017-T3, 2023-T3, 5083-0, 7075-T6, 7N01-T6 among the Aluminum Alloy which are the main materials of the aircraft, but also small or large relations against the fatigue strength of them. The consequence of the research was being progressed the accordance with the order. That is, The order is 2024-T3> 2017-T3> 7N01-T6> 7075-T6> 5083-0. These inclusion came out the acceleration phenomena in the crack growth behaviour among the high ${\Delta}K$ section Nevertheless I figured out their effects were being ignored at the 2b step.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1891-1893
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• 2004

이 논무에서는 유입식 변압를 대상으로 UHF 대역의 펄스신호를 검출하는 센서를 소개하고, 이를 이용한 방전 결함별 측정 결과를 소개한다. 측정결과는 기존의 PRPD법과 주파수 Domain과 위상 Domain에 대한 정보를 가지는 p-f-q 분석으로 측정 하였으며, 본 논문에서는 후자의 결과를 중심으로 서술 하였다.