• 한국주조공학회지
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• 제38권4호
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• pp.75-81
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• 2018

This study examined the effect of the CaMgSn ternary phase on the aging response of the Mg-Sn-Zn alloy. The results revealed that the CaMgSn ternary phase formed in rod-like or needle-like shapes in Mg-3Zn-0.3Ca-xSn (x=1.5, 3, and 5 wt%) alloys and its size decreased as the Sn content increased from 1.5 wt% to 5 wt%. The Mg-3Zn-0.3Ca-5Sn alloy with a relatively fine CaMgSn phase was subjected to solution heat treatment and an aging process. Both the Mg-5Sn-3Zn-0.3Ca and Mg-5Sn-3Zn (base alloy) alloys had similar peak hardness values throughout all aging temperatures but the time-to-peak hardness in the Mg-5Sn-3Zn-0.3Ca alloy was 24-36 hours-earlier than that in the base alloy. Precipitates in the Mg-5Sn-3Zn-0.3Ca alloy were more refined than those in the Mg-5Sn-3Zn alloy and were mostly formed on basal planes. The $Mg_2Sn$ phase formed in either plate-like or rod-like shapes in the Mg-5Sn-3Zn alloy, whereas block-shaped $Mg_2Sn$ particles also formed in the Mg-5Sn-3Zn-0.3Ca alloy.

• Journal of Animal Science and Technology
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• 제46권4호
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• pp.613-624
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• 2004

본 실험은 지방의 공급형태에 따른 반추위발효성상, 영양소 이용효율 및 증체율을 관찰하기 위하여 in vitro 실험과 in vivo 사양 실험을 수행하였다. In vitro에서는 지방원료로서 tallow(T), 그리고 tallow에 2가 양이온은 MgO(T-MgCa), $CaCl_2$(T-Ca), MgO와 $CaCl_2$의 혼합(T-MgCa) 및 Ca-salt 처리 tallow(T-CaS)의 총 5개의 처리구를 두었다. In vitro 배양 시간은 0, 6, 12, 및 24 hr별로 두었다. In vivo 사양 실험은 in vitro 실험을 통하여 얻은 결과를 토대로 성적이 좋은 T-MgCa 구와 T-CaS구를 선택하여 지방 무첨가구를 대조구로 하여 비육후기 한우의 성장률 및 육질에 미치는 영향을 관찰하고자 처리구당 10두씩 3 처리구로 완전임의 배치하여 80일간 실시하였다. 실험 결과를 살펴보면 배양시간 6 hr 이후부터 처리구들간 변화를 보였는데 6 hr에서는 T-MgCa 구와 T-CaS 구에서의 pH 값이 다른 처리구들의 값보다 높게 조사되었고(P<0.05), 12 hr에서는 T와 T-Mg 구에서의 pH 값이 MgO와 $CaCl_2$ 첨가구 보다 높게 조사되었다(P<0.05). Ammonia_N의 농도는 6hr를 제외하고는 처리구들간 통계적 유의차이는 없었다. 6 hrdptjsm ammonia-N 농도는 tallow 단독 처리구에서의 농도가 다른 처리구들보다 낮았다(P<0.05). 총 VFA 생성량은 6 hr에서는 처리구들간 통계적 유의차이가 없었지만 12 hr와 24 hr에서는 T 처리구에 비하여 tallow에 2가 양이온 첨가 또는 Ca-salt를 혼합 첨가한 처리구들에서 높게 조사되었다(P<0.05). 영양소(DM, OM, CP 및 NDF)분해율은 12 hr 이후부터 tallow 단독 처리구보다 양이온이나 Ca-salt 처리 tallow 구에서 보다 높은 경향으 보였다. 용해성 지방산은 전 배양 시간대에 걸쳐 T-CaS 구에서 가장 낮았으나, 불용성 지방산 염 형성은 가장 높았다(P<0.05). 사료급여 30일까지(feeding period I)는 사료섭취량, 일당증체량 및 사료 이용효율이 처리구들간 통계적 유의차이가 없었다. 반면, feeding period II(31${\sim}$50일)와 III(51${\sim}$80일) 그리고, 전 급여기간 동안 일당 증체량과 사료이용효율은 T-MgCa>T-CaS>Control순으로 높았다(P<0.05). 결론적으로 사료 섭취량의 증가가 제한되는 비거세 한우의 비육 마무리기에 있어서 고 에너지 사료제조를 위한 우지의 첨가시 Ca 및 Mg 보충은 반추위 발효성상 및 성장성적의 개선효과가 있음이 확인되었다.

• 대한한의학회지
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• 제18권1호
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• pp.198-207
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• 1997

To explore the action mechanism of Ijintang in the brain, the authors investigated the effects of Ijintang fractions on MgNaK ATPase and MgCa ATPase in rat brain synaptosomes prepared from cerebral cortex. The activities of MgNaK ATPase and MgCa ATPase were assayed by the level of inorganic phosphate liberated from the hydrolysis of ATP. Fraction WH-95-7 at the concentration of $10^{-2}%$ decreased the activity of MgNaK ATPase about 34.1% and also reduced the activity of MgCa ATPase about 49.3% But, other fractions (WB-95-7, WC-95-7, MB-95-7, MC-95-7, MH-95-7) did not significantly changed the activities of the MgNaK ATPase and MgCa ATPase The decreased activity of MgNaK ATPase by WH-95-7 will decrease the rate of $Ca^{2+}$ efflux, probably via an Na-Ca exchange mechanism and will increase the rate of $Ca^{2+}$ entry by the depolarization of nerve terminals. The reduced activity of MgCa ATPase by WH-95-7 will result in the decreased efflux of $Ca^{2+}$. As a conclusion, it can be speculated that lithium elevates the intrasynaptosomal $Ca^{2+}$ concentration via inhibition of the activities of MgNaK ATPase and MgCa ATPase. and this increased $[Ca^{2+}]i$ will cause the release of neurotransmitters.

• 한국재료학회지
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• 제25권6호
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• pp.269-273
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• 2015

The effect of adding Ca on the microstructural and mechanical properties of as-cast Mg-11Li-3Zn-1Sn(wt%) alloys were investigated. Mg-11Li-3Zn-1Sn-0.4Mn with different Ca additions (0.4, 0.8, 1.2 wt%) were cast under an $SF_6$ and $Co_2$ atmosphere at $720^{\circ}C$. The cast billets were homogenized at $400^{\circ}C$ for 12h and extruded at $200^{\circ}C$. The microstructural and mechanical properties were analyzed by OM, XRD, SEM, and tensile tests. The addition of Ca to the Mg-11Li-3Zn-1Sn-0.4Mn alloy resulted in the formation of $Ca_2Mg_6Zn_3$, MgSnCa intermetallic compound. By increasing Ca addition, the volume fraction and size of $Ca_2Mg_6Zn_3$ with needle shape were increased. This $Ca_2Mg_6Zn_3$ intermetallic compound was elongated to the extrusion direction and refined to fine particles due to severe deformation during hot extrusion. The elongation of the 0.8 wt% Ca containing alloy improved remarkably without reduction strength due to the formation of fine grain and $Ca_2Mg_6Zn_3$ intermetallic compounds by Ca addition. It is probable that fine and homogeneous $Ca_2Mg_6Zn_3$ intermetallic compounds played a significant role in the increase of mechanical properties.

• 한국분말재료학회지
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• 제12권4호
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• pp.303-308
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• 2005

Various kinds of Mg-Zn-Ca base alloys were rapidly quenched via melt spinning process. The meltspun ternary and quaternary alloy ribbons were heat-treated, and then the effects of additional elements on age hardening behavior and phase change of precipitates were investigated using Vickers hardness tester, XRD, and TEM equipped with EDS system. In ternary alloys, age hardening was mostly due to the distribution of $Mg_6Ca_2Zn_3$ and $Mg_2Ca$. The stable phases of precipitates were varied according to the aging temperature and the alloy composition. With the increase of Ca content, $Mg_2Ca$ precipitates were detected more than $Mg_6Ca_2Zn_3$ precipitates. In quaternary alloys, the precipitates taken from Mg-Zn-Ca-Co were identified as new quaternary phase, whereas those taken from Mg-Zn-Ca-Zr as MgZnCa containing Zr. In general, the ternary alloy showed higher peak hardness and thermal stability than the quaternary considering the total amounts of the solutes. It implies that the structure of precipitate should be controlled to have the coherent interface with the Mg matrix.

• 한국산학기술학회논문지
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• 제14권9호
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• pp.4185-4190
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• 2013

본 연구에서는 불순물 첨가에 따른 MgO의 소결에 대한 물성변화를 확인하고자 99.9%순도, 300nm크기의 MgO 파우더에 고순도의 CaO를 0wt%, 0.25wt%, 0.50wt% 첨가하여 7GPa의 초고압 하에서 각각 $600^{\circ}C$~$800^{\circ}C$로 5분간 소결을 진행하였다. MgO(-CaO) 소결체의 미세구조와 기계적 물성 변화 확인을 위해 scanning electron microscopy(SEM), X-ray diffractometry(XRD), Vickers 경도, 밀도 측정을 진행하였다. SEM 분석 결과 처리전 300nm 의 MgO 응집체는 $800^{\circ}C$ 고압소결 후 CaO첨가와 관련 없이 모두 약 520nm 입도의 소결체가 되었다. XRD 분석결과 CaO상 자체는 확인할 수 없었으나 CaO고용에 따른 MgO 피크의 쉬프트에 의해 CaO의 존재를 확인할 수 있었다. 비커스 경도치 확인결과 CaO를 첨가하지 않은 MgO 소결체에 비해 동일 온도조건에서 약 12% 증가하였으며 비슷한 경도치를 얻기 위해 소결온도를 약 $100^{\circ}C$이상 낮출 수 있었음을 확인할 수 있었다. 밀도 측정결과 $600^{\circ}C$의 낮은 온도조건 하에서도 CaO를 첨가하지 않은 MgO 소결체에 비해 약 5%이상 증가한 98%이상의 효과적인 소결밀도를 얻을 수 있었다.

• 전기화학회지
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• 제2권2호
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• pp.106-111
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• 1999

[ $CaNi_5$ ] 수소저장합금의 전기화학적 충$\cdot$방전 특성에 미치는 MG(mechanical grinding) 영향이 Ar및 $H_2$ 가스분위기에서 조사되었다 MG공정중 $CaNi_5$ 합금은 표면 산화층의 파괴와 재생성 및 산화층 근방의 불균질화로 인하여 MG 15시간 이후부터 CaO와 Ni로 뚜렷한 상분리가 일어났다. $MG-CaNi_5$는 MG시간이 길어질수록 초기의 전기화학적 방전용량은 현저히 감소하였지만 충$\cdot$방전 싸이클의 증가에 따른 용량저하 속도는 $CaNi_5$합금에 비하여 낮았다. MG처리된 $CaNi_5$합금의 퇴화는 MG공정중의 상분리 및 불규칙화에 의한 수소의 가역반응 site의 감소 및 분극저항의 증가, KOH 전해질 내에서 합금 표면의 산화반응에 의한 부동태 피막형성에 기인하는 것으로 판단되었다.

• 한국진공학회지
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• 제8권1호
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• pp.70-74
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• 1999

Plasma Display Panel(PDP)에서 보호막 물질로 사용중인 MgO 특성을 개선하기 위하여 본 연구에서는 MgO-CaO 박막을 전자빔 증착법으로 제조하였다. MgO 최대 증착속도는 1025 $\AA$/min이었으며 CaO 첨가비가 증가함에 따라 증착속도는 감소하였고, XRD 패턴은 전체적으로 낮은 2$\theta$각 방향으로 이동하였다. MgO 대한 CaO의 최대 고용도는 0.13이다. 최적전압특성을 나타낸 조성은 Mg 47.1 at%, Ca 1.3 at%, O 51.6 at%이었으며 이때 방전개시전압은 176 V, 메모리마진은 0.5였으며 증착속도는 515$\AA$/min이었다.

• The Korean Journal of Physiology and Pharmacology
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• 제2권5호
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• pp.611-616
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• 1998

Although the $Ca^{2+}-activated\;K^+\;(I_{K,Ca})$ channel is known to play an important role in the maintenance of resting membrane potential, the regulation of the channel in physiological condition is not completely understood in vascular myocytes. In this study, we investigated the role of cytoplasmic $Mg^{2+}$ on the regulation of $I_{K,Ca}$ channel in pulmonary arterial myocytes of the rabbit using the inside-out patch clamp technique. $Mg^{2+}$ increased open probability (Po), but decreased the magnitude of single channel current. $Mg^{2+}-induced$ block of unitary current showed strong voltage dependence but increase of Po by $Mg^{2+}$ was not dependent on the membrane potential. The apparent effect of $Mg^{2+}$ might, thus, depend on the proportion between opposite effects on the Po and on the conductance of $I_{K,Ca}$ channel. In low concentration of cytoplasmic $Ca^{2+},\;Mg^{2+}$ increased $I_{K,Ca}$ by mainly enhancement of Po. However, at very high concentration of cytoplasmic $Ca^{2+},$ such as pCa 5.5, $Mg^{2+}$ decreased $I_{K,Ca}$ through the inhibition of unitary current. Moreover, $Mg^{2+}$ could activate the channel even in the absence of $Ca^{2+}.\;Mg^{2+}$ might, therefore, partly contribute to the opening of $I_{K,Ca}$ channel in resting membrane potential. This phenomenon might explain why $I_{K,Ca}$ contributes to the resting membrane potential where membrane potential and concentration of free $Ca^{2+}$ are very low.

• 대한소아치과학회지
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• 제10권1호
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• pp.139-147
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• 1983

This study was undertaken to evaluate the physiological roles & mechanism of $Ca^{++}$-ATPase & $Mg^{++}$-ATPase in human dental pulp. Each specimen of dental pulp was obtained from the freshly extracted, freeze-dried 242 teeth. $Ca^{++}$-ATPase & $Mg^{++}$-ATPase activity were measured by the release of inorganic phosphate & protein with Spectrophotometer. The results were as follows; 1. The $Ca^{++}$-ATPase & $Mg^{++}$-ATPase activity were significantly increased in developing teeth. 2. The $Ca^{++}$-ATPase & $Mg^{++}$-ATPase activity were significantly decreased in nonvital teeth. 3. The $Ca^{++}$-ATPase & $Mg^{++}$-ATPase activity were significant decreased in deciduous teeth. 4. The $Ca^{++}$-ATPase & $Mg^{++}$-ATPase activity didn't have relation with dental caries. 5. The $Ca^{++}$-ATPase & $Mg^{++}$-ATPase were activated by either $Ca^{++}$ alone or $Mg^{++}$ alone.