• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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• pp.175-175
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• 1996

The spinal dorsal horn is the area where primary afferent fibers terminate and cutaneous sensory information is Processed. A number of putative neurotransmitter substances, including excitatory and inhibitory amino acids and peptides, are present in this region and sites and cellular mechanisms of their actions have been a target of numerous studies. In this study, single neurons were acutely isolated and the properties of whole cell current and responses to excitatory and inhibitory neurotransmitters were studied by the patch clamp method. Young rats (7-14 days) were anesthetized with diethyl-ether, and the lumbar spinal cord was excised and cut transversely at a thickness of 30$\mu\textrm{m}$ by Vibroslicer. The treatment of spinal slices with low concentration of proteases (pronase and thermolysin 0.75 mg/$m\ell$) and mechanical dissociation yielded isolated neurons with near intact morphology. Multipolar, ellipsoidal and bipolar, and pyramidal cells were shown. By applying step voltage pulses to neurons held at -70 mV, two types of inward currents and one outward currents observed. The fast activating and inactivating inward current was the Na$\^$+/ current because of its fast kinetics and blocking by 0.5${\mu}$M TTX, a specific blocker of Na$\^$+/ channel. The second type of inward currents were sustained. Based on their kinetics and current-voltage relations, it was likely that the second type of inward current was the voltage-dependent Ca$\^$2+/ current. In the presence of TTX, the steady-state currents mainly represented outward K$\^$+/ current which looked like the delayed rectifier K$\^$+/ current. In addition, the membrane currents produced by agonist of excitatory amino acid (EAA) receptor and the endogenous transmitter candidate L-glutamate were recorded in isolated whole-cell voltage clamped neurons as well as responses to inhibitory amino acids (${\gamma}$-amino butyric acid, glycine). Drugs were applied by a method that allows complete exchange of the solution within 1 sec; an infinite number of solutions can be applied to a single cell.

• Molecules and Cells
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• 제22권2호
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• pp.146-153
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• 2006

Cell polarity is critical for the division, differentiation, migration, and signaling of eukaryotic cells. RAX2 of budding yeast encodes a membrane protein localized at the cell cortex that helps maintain the polarity of the bipolar pattern. Here, we designate SPAC6f6.06c as $rax2^+$ of Schizosaccharomyces pombe, based on its sequence homology with RAX2, and examine its function in cell polarity. S. pombe $rax2^+$ is not essential, but ${\Delta}rax2$ cells are slightly smaller and grow slower than wild type cells. During vegetative growth or arrest at G1 by mutation of cdc10, deletion of $rax2^+$ increases the number of cells failing old end growth just after division. In addition, this failure of old end growth is dramatically increased in ${\Delta}tea1{\Delta}rax2$, pointing to genetic interaction of $rax2^+$ with $tea1^+$. ${\Delta}rax2$ cells contain normal actin and microtubule cytoskeletons, but lack actin cables, and the polarity factor for3p is not properly localized at the growing tip. In ${\Delta}rax2$ cells, and endogenous rax2p is localized at the cell cortex of growing cell tips in an actin- and microtubule-dependent manner. However, ${\Delta}rax2$ cells show no defects in cell polarity during shmoo formation and conjugation. Taken together, these observations suggest that rax2p controls the cell polarity of fission yeast during vegetative growth by regulating for3p localization.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.243-249
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• 2012

A lightweight 200W direct methanol fuel cell (DMFC) stack is designed and fabricated to power a small scale Unmanned Aerial Vehicle (UAV). The DMFC stack consists of 33-cells in which membrane-electrode assemblies (MEAs) having an active area of 88 $cm^2$ are sandwiched with lightweight composite bipolar plates. The total stack weight is around 3.485 kg and stack performance is tested under various methanol feed concentrations. The DMFC stack delivers a maximum power of 248 W at 13.2 V and $71.3^{\circ}C$ under methanol feed concentration of 1.2 M. In addition, the voltage of individual cell in the 33-cell stack is measured at various current levels to ensure the stability of DMFC stack operations. The cell voltage distribution data exhibit the maximum cell voltage deviation of 28 mV at 15 A and hence the uniformity of cell voltages is acceptable. These results clearly demonstrate that DMFC technology becomes a potential candidate for small-scale UAV applications.

• 한국수정란이식학회지
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• 제23권1호
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• pp.5-11
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• 2008

Serial ultrasonographic examinations were daily performed from 15 days after ovulation until parturition to determine the time of first detection and ultrasonographic appearance of the fetal and extra-fetal structures in pregnant 10 Maltese, 10 Yorkshire Terrier, 15 Shih-tzu, and 10 Miniature Schnauzer bitches, respectively. Gestational age was timed from the day of ovulation (day 0), which was estimated to occur when plasma progesterone concentration was first increased above 4.0ng/ml. The gestational length was $63.4{\sim}63.6$ (range: $61{\sim}65$) days and the geatational length was no statistically significant difference among bitches (p>0.05). The initial detection of the extra-fetal structures were; gestational sac at days $18.9{\sim}19.5\;(17{\sim}22)$, zonary placenta at days $24.6{\sim}25.5\;(23{\sim}28)$, yolk sac membrane at days $24.6{\sim}25.5\;(23{\sim}27)$, yolk sac tubular shape at days $26.1{\sim}26.3\;(24{\sim}28)$, and amniotic membrane at days $26.1{\sim}28.2\;(24{\sim}31)$, respectively. The time of the first detection of the extra-fetal structures were no statistically significant difference among bitches (p>0.05). The initial detection of the fetal structures were; embryo initial detection at days $22.5{\sim}22.9\;(21{\sim}24)$, heartbeat at days $23.2{\sim}23.8\;(21{\sim}25)$, embryo bipolar shape $27.6{\sim}28.9\;(26{\sim}30)$, fetal movement at days $31.9{\sim}32.8\;(27{\sim}34)$, limb buds at days $29.1{\sim}30.7\;(27{\sim}33)$, stomach at days $31.1{\sim}33.1\;(29{\sim}34)$, urinary bladder at days $32.4{\sim}33.2\;(29{\sim}35)$, skeleton at days $34.7{\sim}35.9\;(34{\sim}39)$, and kidney at days $42.1{\sim}44.7\;(41{\sim}48)$, respectively. The the time of the first detection of the fetal structures were no statistically significant difference among bitches (p>0.05). These results indicate the evaluation of the time of first detection and ultrasonographic characteristics of the gestational structures might be useful for pregnancy diagnosis, estimating fetal age, embryonic resorption, fetal monster, abnormal fetal growth and fetal viability, respectively.

• 전기화학회지
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• 제10권1호
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• pp.25-30
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• 2007

고분자전해질 연료전지의 성능은 cell 온도, 전체 압력, 반응 기체의 부분 압력 상대습도와 같은 다양한 요인들에 의해 영향을 받는다. 이온화된 수소 이온은 $H_3O^+$의 형태로 membrane을 통과하여 물을 생성하는 반응으로 전기를 발생시킨다. 대용량 연료전지에서는 부수적으로 생성되는 열을 제거하거나 다른 용도로 사용할 목적으로 냉각시스템이 필요하다. 냉각수의 전도도가 상승할 경우에 연료전지에서 발생된 전류의 일부가 냉각수를 통하여 누설되어 연료전지의 성능을 감소시킬 수 있다. 본 연구에서는 3차 증류수와 ethylene glycol이 함유되어 있는 부동액을 사용하여 저항 수치 변화를 관찰하는 실험을 수행하였다. 3차 증류수의 경우 저항값이 설정치 이하로 내려가는데 약 28일이 소요되었고, 연료전지의 운전에 의한 영향은 관찰되지 않았다. 부동액을 냉각수로 사용한 경우는 43일이 지나도 저항값이 설정치 이하로 내려가지는 않았지만, stack 분리판의 접착부에 이상이 생긴 것으로 추정되는 연료전지의 성능 저하가 발생하여 전도도 실험을 중단하였다. 고분자전해질 연료전지에서는 수소이온의 이온전도성 저하를 방지하기 위하여 외부에서 가습하여 주는 방식이 일반적이지만, 소용량 연료전지에서는 무가습 조건을 적용하여 연료전지의 효율을 높이고 제작단가도 경감할 수 있다. 이를 위하여 저가습 및 무가습 실험을 수행하였으나 대용량 연료전지에서는 양측 무가습인 경우에 $50{\sim}60^{\circ}C$ 이상의 고온에서 성능이 발현되기 어려운 것으로 관찰되었다. 냉각수의 유량을 다르게 하여 실험을 수행한 경우에는 0.78L/min과 같은 낮은 유량에서 출구온도와 입구온도를 측정하여 본 결과 두 온도 사이에 ${\Delta}T$가 다른 유량에서보다 크게 발생하여 성능이 감소된 것으로 사료된다. 이와 같이 냉각수의 온도와 유량을 다르게 하여 양측 무가습 실험을 수행한 결과, 연료전지의 성능이 cell 온도에 직접적인 연관이 있는 것으로 관찰되었다.

• Clinics in Shoulder and Elbow
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• 제14권1호
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• pp.140-145
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• 2011

목적: 금속 요골두 치환술은 주관절 불안정성을 동반한 고정할 수 없는 분쇄된 요골두 골절의 치료로 최근 다양한 임플란트의 개발로 널리 사용되고 있다. 저자는 금속성 요골두 치환술의 적응증과 국내에 사용중인 임플란트의 종류와 수술 술기를 문헌 고찰과 함께 기술하고자 한다. 대상 및 방법: 요골두 치환술의 주 적응증은 동반된 연부조직 손상으로 인한 주관절의 불안정성이 있고, 요골두의 분쇄 골절로 안정적인 내고정이 불가능한 골절이다. 이러한 경우 과거 시행되었던 요골두 절제술은 많은 합병증의 발생으로 금기시되고 있다. 현재 국내에서는 양극성, 압박 고정 단극성 및 이완 고정 단극성 임플란트의 3종류가 수입되어 사용되고 있다. 요골두 치환술은 궁극적으로 원래의 요골두의 크기와 길이로 복원하는 것이 중요하다. 과도하게 긴 요골두의 삽입은 흔한 합병증으로 수술 시 주의가 필요하다. 결과 및 결론: 요골두 치환술은 적절한 적응증과 정확한 수술 술기로 만족할 만한 임상적 결과를 얻을 수 있다. 향후 장기추시 연구와 다양한 치환물들의 임상적인 비교 연구가 필요하다.