• The Korean Journal of Physiology and Pharmacology
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• 제10권1호
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• pp.13-17
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• 2006

Experimentally induced cortical disorganization exhibits many anatomical features which are characteristic of cortical malformations in children with early-onset epilepsy. We used an immunocytochemical technique and extracellular field potential recordings from the dorsal hippocampus to determine whether the excitability of the CA1 pyramidal cells was enhanced in rats with exnerimentallv induced hippocampal dysplasia. Compared with control rats, the MAM-treated rats displayed a decrease of paired pulse inhibition. When $GABA_A$ receptor antagonists were blocked with $10{\mu}M$ bicuculline the amplitude of the second population spike of the MAM-treated of rats was similar to that of the first population spike, as was in the control rats. The MAM-treated rats had fewer somatostatin and parvalbumin-immunoreactive neurons than the control rats. These results suggest that the enhanced neuronal responsiveness of the in vivo recording of the CA1 in this animal model may involve a reduction of CA1 inhibition.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.323-323
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• 2010

Saw damage of crystalline silicon wafer is unavoidable factor. Usually, alkali treatment for removing the damage has been carried out as the saw damage removal (SDR) process for priming the alkali texture. It usually takes lots of time and energy to remove the sawed damages for solar grade crystalline silicon wafers We implemented two different mixed acidic solution treatments to obtain the improved surface structure of silicon wafer without much sacrifice of the silicon wafer thickness. At the first step, the silicon wafer was dipped into the mixed acidic solution of $HF:HNO_3$=1:2 ration for polished surface and at the second step, it was dipped into the diluted mixed acidic solution of $HF:HNO_3:H_2O$=7:3:10 ratio for porous structure. This double treatment to the silicon wafer brought lower reflectance (25% to 6%) and longer carrier lifetime ($0.15\;{\mu}s$ to $0.39\;{\mu}s$) comparing to the bare poly-crystalline silicon wafer. With optimizing the concentration ratio and the dilution ratio, we can not only effectively substitute the time consuming process of SDR to some extent but also skip plasma enhanced chemical vapor deposition (PECVD) process. Moreover, to conduct alkali texture for pyramidal structure on silicon wafer surface, we can use only nitric acid rich solution of the mixed acidic solution treatment instead of implementing SDR.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.105-110
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• 2011

The doping procedure in crystalline silicon solar cell fabrication usually contains oxygen injection during drive-in process and removal of phosphorous silicate glass(PSG). In this paper, we studied the effect of oxygen injection and PSG on conversion efficiency of solar cell. The mono crystalline silicon wafers with $156{\times}156mm^2$, $200{\mu}m$, $0.5-3.0{\Omega}{\cdot}cm$ and p-type were used. After etching $7{\mu}m$ of the surface to form the pyramidal structure, the P(phosphorous) was injected into silicon wafer using diffusion furnace to make the emitter layer. After then, the silicon nitride was deposited by the PECVD with 80 nm thickness and 2.1 refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in 400-425-450-550-$880^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Solar cells with four different types were fabricated with/without oxygen injection and PSG removal. Solar cell that injected oxygen during the drive-in process and removed PSG after doping process showed the 17.9 % conversion efficiency which is best in this study. This solar cells showed $35.5mA/cm^2$ of the current density, 632 mV of the open circuit voltage and 79.5 % of the fill factor.

• 한국태양에너지학회 논문집
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• 제31권1호
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• pp.37-43
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• 2011

In this paper, the optimized doping condition of crystalline silicon solar cells with $156{\times}156\;mm^2$ area was studied. To optimize the drive-in temperature in the doping process, the other conditions except variable drive-in temperature were fixed. These conditions were obtained in previous studies. After etching$7\;{\mu}m$ of the surface to form the pyramidal structure, the silicon nitride deposited by the PECVD had 75~80nm thickness and 2 to 2.1 for a refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in 400-425-450-550-$850^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Drive-in temperature was changed in range of $830^{\circ}C$ to $890^{\circ}C$to obtain the sheet resistance $30{\sim}70\;{\Omega}/{\box}$ with $10\;\Omega}/{\box}$ intervals. Solar cell made in $890^{\circ}C$ as the drive-in temperature revealed 17.1% conversion efficiency which is best in this study. This solar cells showed $34.4\;mA/cm^2$ of the current density, 627 mV of the open circuit voltage and 79.3% of the fill factor.

• Applied Microscopy
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• 제30권3호
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• pp.265-272
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• 2000

낙지 Octopus minor의 상완 신경절을 광학현미경과 전자현미경을 통해 관찰한 결과 다음과 같은 결론을 얻었다. 낙지의 상완신경절은 각각의 흡반 밑에서 둥근 형태로 관찰되었는데 그들의 크기는 흡반의 크기에 비례하였다. 둥근 형태의 상완신경절은 피질부와 수질부 두 부분으로 구분되었던 바, 피질부에서는 신경세포의 집단이, 수질부에는 신경망이 위치해 있었다. 신경세포의 집단에서는 3종류(소, 중, 대형)의 신경세포들이 관찰되었는데 소신경세포는 직경이 $0.9{\mu}m$정도인 둥근 형태의 작은 세포인데 비해 중신경세포는 직경 $1.6\times1.3{\mu}m$정도인 타원형세포였다. 대신경세포는 직경이 $2.8{\mu}m$정도 크기의 난원형의 큰 세포로 확인되었고 이들 3종류의 세포들은 모두 전자밀도가 낮아서 밝게 관찰되었으며 세포소기관의 발달은 미진하였다. 또한 중신경세포인 경우에는 $0.6\times0.4{\mu}m$정도 크기의 전자밀도가 중등도인 방추형 신경교세포에 의해 둘러싸여 있었다. 수질부의 신경망에서는 다양한 크기의 수상돌기와 축색돌기들이 복잡한 그물형태를 하고 있었다. 이들은 돌기내에서 4종류의 화학연접소포 (chemical synaptic vesicle)들을 소지하고 있었는데, 전자밀도가 매우 높고 직경이 100 nm 정도인 electron-dense synaptic vesicle과 전자밀도가 중등도이며 직경이 90nm 정도인 median electron-dense synaptic vesicle 그리고 중앙에 전자밀도가 높은 둥근 핵을 포함하는 직경 90nm정도의 electron-dense cored synaptic vesicle등이 관찰되었다. 그러나 전자밀도가 투명한 연접소포(electron-lucent synaptic vesicle)는 직경이 50nm정도로 가장 작은 형태를 하고 있었다.

• 대한한의학회지
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• 제29권5호
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• pp.29-40
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• 2008

Objectives : It has been reported that Sophorae Subprostratae Radix (SSR) has a neuroprotective effect on cerebral ischemia in animals. In the present study, the authors investigated the neuroprotective effect of SSR on glutamate excitotoxicity. Glutamate excitotoxicity was induced by using NMDA, AMPA, and KA in PC12 cells and in organotypic hippocampal slice cultures. Methods :Methanolic extract of SSR was added at 0.5, 5, and 50 ${\mu}$g/ml to culture media for 24 hours. The effects of SSR were evaluated by measuring of cell viability, PI-stained neuronal cell death, TUNEL-positive cells, and MAP-2 immunoreactivity. Results : SSR increased PC12 cell viabilities significantly against AMPA-induced excitotoxicity, but not against NMDA-induced or KA-induced excitotoxicity. In organotypic hippocampal slice cultures damaged by NMDA-induced excitotoxicity, SSR attenuated neuronal cell death significantly in the CA1, CA3, and DG hippocampal regions and reduced TUNEL-positive cells significantly in CA1 and DG regions. In organotypic hippocampal slice cultures damaged by AMPA-induced excitotoxicity, SSR attenuated neuronal cell death and reduced TUNEL-positive cell numbers significantly in the CA1 and DG regions. In organotypic hippocampal slice cultures damaged by KA-induced excitotoxicity, SSR attenuated neuronal cell death significantly in CA3, but did not reduce TUNEL-positive cell numbers in CA1, CA3 or DG. In organotypic hippocampal slice cultures damaged by NMDA-induced excitotoxicity, SSR attenuated pyramidal neuron neurite retraction and degeneration in CA1. Conclusions : These results suggest that the neuroprotective effects of SSR are related to antagonistic effects on the NMDA and AMPA receptors of neuronal cells damaged by excitotoxicity and ischemia.

• The Korean Journal of Physiology and Pharmacology
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• 제2권3호
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• pp.297-305
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• 1998

This study used in vivo intracellular recording in rat hippocampus to evaluate the effect of lidocaine and MK-801 on the membrane properties and the synaptic responses of individual neurons to electrical stimulation of the commissural pathway. Cells in control group typically fired in a tonic discharge mode with an average firing frequency of $2.4{\pm}0.9$ Hz. Neuron in MK-801 treated group (0.2 mg/kg, i.p.) had an average input resistance of $3.28{\pm}5.7\;M{\Omega}$ and a membrane time constant of $7.4{\pm}1.8$ ms. These neurons exhibited $2.4{\pm}0.2$ ms spike durations, which were similar to the average spike duration recorded in the neurons of the control group. Slightly less than half of these neurons were firing spontaneously with an average discharge rate of $2.4{\pm}1.1$ Hz. The average peak amplitude of the AHP following the spikes in these groups was $7.4{\pm}0.6$ mV with respect to the resting membrane potential. Cells in MK-801 and lidocaine treated group (5 mg/kg, i.c.v.) had an average input resistance of $3.45{\pm}6.0\;M{\Omega}$ and an average time constant of $8.0{\pm}1.4$ ms. The cells were firing spontaneously at an average discharge rate of $0.6{\pm}0.4$ Hz. Upon depolarization of the membrane by 0.8 nA for 400 ms, all of the tested cells exhibited accommodation of spike discharge. The most common synaptic response contained an EPSP followed by early-IPSP and late-IPSP. Analysis of the voltage dependence revealed that the early-IPSP and late-IPSP were putative $Cl^--and\;K^+-dependent$, respectively. Systemic injection of the NMDA receptor blocker, MK-801, did not block synaptic responses to the stimulation of the commissural pathway. No significant modifications of EPSP, early-IPSP, or late-IPSP components were detected in the MK-801 and/or lidocaine treated group. These results suggest that MK-801 and lidocaine manifest their CNS effects through firing pattern of hippocampal pyramidal cells and neural network pattern by changing the synaptic efficacy and cellular membrane properties.

• 한국동물학회지
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• 제31권2호
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• pp.111-121
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• 1988

고슴도치의(Erinaceus koneanus)췌강 각 부위별에 출현하는 glucagon(A)세포,insulin(B)세포, somatostatin(D)세포 및 pancreatic polypeptide(PP)세포 등 4종의 내분비세포의 출현빈도, 분포상태, 모양 및 크기 등을 관찰하고자 췌장을 비장부와 십이지장부로 구분하고 이를 각각 근위부, 중간부 및 원위부로 세분한 후 면역세포화학적 방법을 시도하여 광학현미경하에서 검경하였던 바 다음과 같은 결론을 얻었다. Glucagon(A)세포의 크기는13 $\mu$ m x 9.5 $\mu$ m였고 그 모양은 원형, 난원형 및 추체형을 띠고 있었으며 췌도의 주변부와 외분비 실질사이에 분포하고 있었다. A세의 출현빈도는 비장부의 모든 부의에서 24.5%-30.5%, 십이지장부의 원위부에서 30.1%로 관찰되었으나 십이지장부의 근위부와 중간부에서는 2.6%-5.2%로 관찰되었다. Insulin(B)세포의 크기는 11.6$\mu$m x 9.4$\mu$m로서 원형 또는 난원형을 띠었고 췌도내에 균등하게 분포하고 있었으며, 비장부의 모든 부위와 십이지장의 원위부에서는 63.5%-68.9%, 십이지장부의 근위부와 중간부에서는 35.9%-55.6%로 출현하였다. Somatostatin(D)세포는 크기가 12.6$\mu$m x 9.1 $\mu$m로서 주변부와 외분비 실질사에 나타났으며 세포의 출현빈도는 비장부와 십이장부의 모든 부위에서 2.6%-5.9%로서 소수 관찰되었다. Pancreatic polypeptide(PP)세포는 크기가 12.8$\mu$ m x 8.5 $\mu$m였고 세포의 모양은 원형, 난원형 및 추체형 등 다양하였으며 췌도의 주변부와 외분비실질간에 주로 분포하고 있었다. PP세포의 출편빈도는 십이지장부의 근위부와 중간부에서는 각각 42.5%, 55.4%로서 관찰된 반면 비장부의 모든 부위와 십이지장부의 원위부에서는 0.5%-2%로서 소수 출현되었다.

• 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.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권1호
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• pp.59-65
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• 2012

A study on the electrical characteristic analysis of solar cell diodes under experimental conditions of varying temperature and frequency has been conducted. From the current-voltage (I-V) measurements, at the room temperature, we obtained the ideality factor (n) for Space Charge Region (SCR) and Quasi-Neutral Region (QNR) of 3.02 and 1.76, respectively. Characteristics showed that the value of n (at SCR) decreases with rising temperature and n (at QNR) increases with the same conditions. These are due to not only the sharply increased SCR current flow but the activated carrier recombination in the bulk region caused by defects such as contamination, dangling bonds. In addition, from the I-V measurements implemented to confirm the junction uniformity of cells, the average current dispersion was 40.87% and 10.59% at the region of SCR and QNR, respectively. These phenomena were caused by the pyramidal textured junction structure formed to improve the light absorption on the device's front surface, and these affect to the total diode current flow. These defect and textured junction structure will be causes that solar cell diodes have non-ideal electrical characteristics compared with general p-n junction diodes. Also, through the capacitance-voltage (C-V) measurements under the frequency of 180 kHz, we confirmed that the value of built-in potential is 0.63 V.