• Ocean and Polar Research
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• 제32권3호
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• pp.247-254
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• 2010

Single cell PCR analysis and light and scanning electron microscopic techniques were utilized to identify free living bivalve larvae in the coastal waters of Tae-an, on the west coast of Korea. Through DNA sequencing, venerid clam larvae were isolated and identified as Ruditapes philippinarum (99% similarity) and Meretrix lusoria (99%). Under microscopic observation, the D-veliger stage of R. philippinarum exhibited symmetrical shoulder angles and an elliptical ventral form. In contrast, M. lusoria displayed asymmetrical shoulder angles and a round ventral form in the umbonal stage. Size of the R. philippinarum larvae was $156{\pm}22{\mu}m$ in length, $126{\pm}12{\mu}m$ in height, $92{\pm}14{\mu}m$ in width with a length: height ratio of 1.23. Meretrix lusoria was $202{\pm}44{\mu}m$ in length, $161{\pm}35{\mu}m$ in height, $96{\pm}38{\mu}m$ in width with a length: height ratio of 1.25. Experimental results indicate that morphological and molecular characteristics provide evidence for the larval identification of these two venerid clam larvae species in nature.

• Journal of Periodontal and Implant Science
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• 제49권4호
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• pp.258-267
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• 2019

Purpose: Increased bone regeneration has been achieved through the use of stem cells in combination with graft material. However, the survival of transplanted stem cells remains a major concern. The purpose of this study was to evaluate the viability of transplanted mesenchymal stem cells (MSCs) at an early time point (24 hours) based on the type and form of the scaffold used, including type I collagen membrane and synthetic bone. Methods: The stem cells were obtained from the periosteum of the otherwise healthy dental patients. Four symmetrical circular defects measuring 6 mm in diameter were made in New Zealand white rabbits using a trephine drill. The defects were grafted with 1) synthetic bone (${\beta}$-tricalcium phosphate/hydroxyapatite [${\beta}-TCP/HA$]) and $1{\times}10^5MSCs$, 2) collagen membrane and $1{\times}10^5MSCs$, 3) ${\beta}-TCP/HA+collagen$ membrane and $1{\times}10^5MSCs$, or 4) ${\beta}-TCP/HA$, a chipped collagen membrane and $1{\times}10^5MSCs$. Cellular viability and the cell migration rate were analyzed. Results: Cells were easily separated from the collagen membrane, but not from synthetic bone. The number of stem cells attached to synthetic bone in groups 1, 3, and 4 seemed to be similar. Cellular viability in group 2 was significantly higher than in the other groups (P<0.05). The cell migration rate was highest in group 2, but this difference was not statistically significant (P>0.05). Conclusions: This study showed that stem cells can be applied when a membrane is used as a scaffold under no or minimal pressure. When space maintenance is needed, stem cells can be loaded onto synthetic bone with a chipped membrane to enhance the survival rate.

• 대한치과교정학회지
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• 제32권3호
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• pp.227-234
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• 2002

본 연구는 조골세포의 특성을 가지고 있는 G292세포주를 이용하여 세포막 이온통로에 대한phorbol ester의 효과를 조사하여 protein kinase C (PCK)의 이온통로에 대한 작용기전을 밝히고자 하였다. Patch clamp 기법을 이용하여 G292 세포에서 cell-attached configuration으로 단일이온통로의 활동을 관찰하고 Phorbol 12, 13-dibutyrate (PDBu)의 효과를 관찰하였다. 안정상태 G292 세포에서 cell-attached 모드로 세포막의 단일이 온통로 활동을 관찰한 결과 45pS의 $K^+$통로가 특징 적으로 우세하였다. 유리 전극 내부에 세포내 액과 세포외 액을 사용하여 전류-전압의 관계를 조사한 결과, 세포내 액을 사용하는 경우에는 역전전압이 5.5mV이었으며 세포외액을 사용하는 경우에는 -27mV이었다. PDBu는 45pS의 이온통로를 10nM이상의 농도에서 이온통로의 열릴 확률을 증가시켰으며 PKC억제제인 staurosporine 10nM에 의하여 차단되는 특성을 보였다. PDBu는 45pS의 이온통로에 작용하여 전류-전압의 관계에서 역전전압을 음의 방향으로 이동시켰으며 동일한 막전압에서 단일이온통로의 전류 크기를 증가시켰다. G292세포에서 PDBu에 의하여 PKC가 활성화되는 것을 western blot으로 확인한 결과 PDBu 0.luM은 세포질에서 세포막으로 PKC translocation을 유의하게 증가시키는 것을 확인하였다. 이상의 결과는 G292세포에서 phorbol ester의 일종인 PDBu가 세포내 PKC를 활성화시켜 45pS의 이온통로를 활성화시키며 이러한 작용의 결과로 세포막전압의 변화가 세포의 기능을 조절할 것으로 사료된다.

• The Korean Journal of Physiology and Pharmacology
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• 제17권6호
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• pp.511-516
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• 2013

Bladder cancer is the seventh most common cancer in men that smoke, and the incidence of disease increases with age. The mechanism of occurrence has not yet been established. Potassium channels have been linked with cell proliferation. Some two-pore domain $K^+$ channels (K2P), such as TASK3 and TREK1, have recently been shown to be overexpressed in cancer cells. Here we focused on the relationship between cell growth and the mechanosensitive K2P channel, TREK2, in the human bladder cancer cell line, 253J. We confirmed that TREK2 was expressed in bladder cancer cell lines by Western blot and quantitative real-time PCR. Using the patch-clamp technique, the mechanosensitive TREK2 channel was recorded in the presence of symmetrical 150 mM KCl solutions. In 253J cells, the TREK2 channel was activated by polyunsaturated fatty acids, intracellular acidosis at -60 mV and mechanical stretch at -40 mV or 40 mV. Furthermore, small interfering RNA (siRNA)-mediated TREK2 knockdown resulted in a slight depolarization from $-19.9mV{\pm}0.8$ (n=116) to $-8.5mV{\pm}1.4$ (n=74) and decreased proliferation of 253J cells, compared to negative control siRNA. 253J cells treated with TREK2 siRNA showed a significant increase in the expression of cell cycle boundary proteins p21 and p53 and also a remarkable decrease in protein expression of cyclins D1 and D3. Taken together, the TREK2 channel is present in bladder cancer cell lines and may, at least in part, contribute to cell cycle-dependent growth.

• 전자공학회논문지C
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• 제36C권8호
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• pp.10-21
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• 1999

본 논문에서는 12비트의 해상도와 65MHz의 변환속도를 가지면서 단일 3.3V의 공급전압으로 동작하는 전류 셀 매트릭스 구조의 CMOS D/A 변환기를 제안하였다. 설계된 CMOS D/A 변환기는 우수한 단조증가성과 빠른 정착시간을 가지는 전류 셀 매트릭스 구조의 장점을 이용하면서 기존의 D/A 변환기의 전류셀 간의 문턱전압의 부정합과 접지선의 전압 강하에 의한 오차를 감소시키기 위해 트리 구조 바이어스 회로, 대칭적 접지선 연결, 캐스코드 전류 스위치를 사용하여 구현되었다. 설계된 전류 셀 매트릭스 12비트 D/A 변환기를 $0.6{\mu}m$ CMOS n-well 공정을 이용하여 제작하였다. 제작된 DAC칩을 +3.3V 단일 공급전원을 이용하여 측정한 결과, 정착시간이 20nsec로써 50MHz의 변환속도와 35.6mW의 전력소모를 나타내었다. 또한 측정된 SNR, DNL은 각각 55 dB, ${\pm}0.5LSB$,${\pm}2LSB$를 나타내었다.

• 한국광물학회지
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• 제29권4호
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• pp.191-198
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• 2016

인회석 광물 군에 속하는 녹연석($Pb_{4.85}(P_{1.02}O_4)_3Cl_{1.04}$)에 대한 상온-고압 상태방정식 연구를 시행하였다. 대칭형 다이아몬드 앤빌기기를 이용하여 33.4 GPa까지 압력을 증가시키면서 각분산 X-선 회절법과 방사광을 이용하여 회절 데이터를 검출하였으며, 시료에 가해준 압력은 루비 형광파의 파장변화를 측정하여 결정하였다. 본 고압실험에서 시행한 압력의 범위 내에서 상변이는 관찰되지 않았으며, 정압상태에서 체적탄성률($K_0$)은 $K{_0}^{\prime}=13(2)$일 때 80(7) GPa로 계산되었다. 본 연구에서 결정된 상온상태에서 녹연석의 체적탄성률 신뢰도를 정규화압력 및 정규화응력변형 분석을 하여 평가하였다.

• 한국세라믹학회지
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• 제51권4호
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• pp.278-282
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• 2014

Due to high ionic conductivity and favorable oxygen electrocatalysis, doped $Bi_2O_3$ systems are promising candidates as solid oxide fuel cell cathode materials. Recently, several researchers reported reasonably low cathode polarization resistance by adding electronically conducting materials such as (La,Sr)$MnO_3$ (LSM) or Ag to doped $Bi_2O_3$ compositions. Despite extensive research efforts toward maximizing cathode performance, however, the inherent catalytic activity and electrochemical reaction pathways of these promising materials remain largely unknown. Here, we prepare a symmetrical structure with identically sized $Y_{0.5}Bi_{1.5}O_3$/LSM composite electrodes on both sides of a YSZ electrolyte substrate. AC impedance spectroscopy (ACIS) measurements of electrochemical cells with varied cathode compositions reveal the important role of bismuth oxide phase for oxygen electrocatalysis. These observations aid in directing future research into the reaction pathways and the site-specific electrocatalytic activity as well as giving improved guidance for optimizing SOFC cathode structures with doped $Bi_2O_3$ compositions.

• 대한전자공학회논문지
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• 제12권5호
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• pp.1-5
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• 1975

접합형 트린지스터와 발광다이오드(LED) 및 광도전소자(CdS)로서 구성된 광결합 전류안정부저항회로를 진안하였다. 이는 일반적으로 광트랜지스터보다도 더 예민한 것을 이용하여, CdS와 LED를 밀착 시켜서 LED에 흐르는 전류와 CdS의 실효저항변화로써 결합된 광결합방식을 택하였다. 트랜지스터의 콜랙터-에미터간에 인위적인 누변저항을 삽입하는 방법을 도입함으로써 부저항치 및 최대입력단자전압치를 임의로 변화할 수 있게 하였으며, 제안한 회로를 분석하고 또 이를 실험적으로 확인하였다. 누변저항을 1KΩ에서 30KΩ까지 변화시켰을 때 최대입력단자전압은 1.65V에서 4.22V로 변하였고, 부저항치는 -1.0KΩ에서 -10.0KΩ까지 변하였다. 또 실험치에 대한 계산치에의 상대백분최대오차가 11%이었다. A current stable negative resistance circuit has been constucted with combination of coulplementary symmetrical transistors, a light emitting diode and a photoconductive cell. The negative resistance(Rn) and break-over voltage(VBo) can be set at a designed value according to adjustment of the artificial leakage resistance of p-n-p transistor. The RN and VBo calculated in this designed circuit are checked though the experiments, the errors are found less than 11%.

• 한국세라믹학회지
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• 제52권5호
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• pp.308-314
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• 2015

The electrochemical performance and Cr poisoning behavior of $La_{1-x}Ba_xCo_{0.9}Fe_{0.1}O_{3-{\delta}}$ (LBCF, x = 0.3, 0.4, 0.5) and $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3-{\delta}}$ (LSCF) cathodes were investigated for solid oxide fuel cells (SOFCs). The polarization resistance of the LBCF/GDC/LBCF symmetrical cell was found to decrease with increasing Ba content (x value). This phenomenon might be associated with the high oxygen vacancy concentration in the LBCF sample, with x = 0.5. In addition, there was no chromium poisoning in the LBCF cathode. On the other hand, the polarization resistance of the LSCF cathode was found to significantly increase after exposure to gaseous chromium species; it appears that this result stemmed from the formation of $SrCrO_4$ phase. Therefore, it can be expected that LBCF can be a durable potential cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFC).

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1736-1746
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• 2021

The results of full-scale numerical experiments of a hybrid thorium-containing fuel cell facility operating in a close-to-critical state due to a controlled source of fusion neutrons are discussed in this work. The facility under study was a complex consisting of two blocks. The first block was based on the concept of a high-temperature gas-cooled thorium reactor core. The second block was an axially symmetrical extended plasma generator of additional neutrons that was placed in the near-axial zone of the facility blanket. The calculated models of the blanket and the plasma generator of D-T neutrons created within the work allowed for research of the neutronic parameters of the facility in stationary and pulse-periodic operation modes. This research will make it possible to construct a safe facility and investigate the properties of thorium fuel, which can be continuously used in the epithermal spectrum of the considered hybrid fusion-fission reactor.