• Journal of the Korean Vacuum Society
• /
• v.11 no.3
• /
• pp.166-170
• /
• 2002

Artificial $BaTiO_3$(BTO)/$SrTiO_3$(STO) oxide superlattice have been deposited on MgO (100) single crystal substrate by pulsed laser deposition(PLD) method. The stacking periodicity of BTO/STO superlattice structure was varied from $BTO_{1\;unit\; cell}/STO_{1\;unit\; cell}$ to $BTO_{125\;unit\; cell}/STO_{125 \;unit \;cell}$ thickness with the total thickness of 100 nm. The result of X-ray diffraction showed the characteristics of superlattice in the BTO/STO multilayer structure. we have also confirmed that there was no interdiffusion at the interface between BTO and STO layers by high resolution transmission electron microscopy(HRTEM). The dielectric constant of superlattice increased with decreasing stacking periodicity of the BTO/STO superlattice within the critical thickness. The dielectric constant of the BTO/STO superlattice reached a maximum i.e., 1230 at a stacking perioicity of $BTO_{2\;unit\; cell}/STO_{2\;unit\; cell}$ .

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.209-209
• /
• 2009

Fabrication of p-type ZnO has already proven difficult and usually inconsistent despite numerous worldwide efforts. Many research groups studied electrical and optical properties P, Li, As, N single doped ZnO thin film. In P-doped ZnO thin film, the reproducibility of p-type conduction with $P_2O_5$ as a dopant source was shown to be relatively poor. In this study, we made P single doped and Li & P co-doped ZnO target. To investigate electrical and optical properties of P single doped and Li & P co-doped ZnO thin film using $P_2O_5$ and $Li_3PO_4$ dopant source respectively was deposited by PLD. The growth temperature was changed 500, $700^{\circ}C$ and various oxygen partial pressure and post-annealing conditions was changed temperature, different gas ambient($O_2,N_2$). We investigate that how to change electrical and optical properties as function of growth temperature, oxygen partial pressure and post-annealing(RTA).

• Progress in Superconductivity and Cryogenics
• /
• v.10 no.3
• /
• pp.5-8
• /
• 2008

On highly-textured IBAD-MgO templates, we have tried to find proper buffer layers among various candidate materials, including $LaMnO_3$ (LMO), $La_2Zr_2O_7$ (LAO), $LaAlO_3$ (LAO), $LaGaO_3$ (LGO), $NdGaO_3$ (NGO), and $BaZrO_3$ (BZO). All buffer layers were deposited on the IBAD-MgO templates by KrF pulsed laser deposition(PLD). LAO layer showed an armorphous phase. LZO, LGO, and NGO layers showed polycrystalline growth. Only LMO and BZO layers exhibited c-axis oriented biaxially textured films. Optimally processed LMO buffer layer at deposition temperature of $750^{\circ}C$ and $PO_2$ of 100mTorr exhibited ${\triangle}{\phi}$ value of ${\sim}-5.2^{\circ}$ and RMS roughness of 5.6nm. Interestingly, BZO buffer layers with ${\triangle}{\phi}$ values of ${\sim}-6^{\circ}$ could be routinely produced over a wide PLD processing condition.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.42 no.2 s.332
• /
• pp.75-80
• /
• 2005

In this paper, 2-stage power amplifier has been designed for 5.8GHz wireless LAN application. The power amplifier PldB output power has 21.6dBm at 5.8GHz frequency. Also the power amplifier shows 17.6dB gain and -17.8dB input return loss at 5.725GHz to 5.825GHz. The OFDM modulation and transmission block have been modeled in order to analyse the relationship between the power amplifier distortion and output ACPR for the IEEE 802.11a wireless LAN. The nonlinear characteristic of the power amplifier has been modeled as AM-to-AM and AM-to-PM using the behavioral model, and the output spectrum is analysed with the phase distortion variation. Also, amplifier back-off value from PldB to satisfy the required IEEE 802.11a standard spectrum mask has been simulated with phase distortion, and the simulation data have been compared to the measurement result collected by using the pre-distortion technique.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.12
• /
• pp.1219-1227
• /
• 2014

For development of the surface acoustic wave bandpass filter(SAW-BPF), we fabricated the high quality ZnO thin films through the step-by-step(double) deposition using two different deposition methods which are pulsed laser deposition(PLD) and RF sputtering techniques. The second growth of ZnO thin films was completed by RF sputtering method on the first ZnO thin films pre-deposited by PLD method. The characteristics of ZnO thin films were analyzed by XRD, SEM and AFM systems. The FWHM of ${\omega}$-scan analysis and the minimum RMS value of surface roughness of step-by-step grown ZnO thin films were $0.79^{\circ}$ and 1.108 nm respectively. As a result, the crystallinity and the preferred orientation of the grown ZnO thin films were kept good quality and the surface roughnesses of those were improved by post-annealing process as comparison with ZnO thin film fabricated by the conventional PLD technique only. Using these proposed ZnO thin films, we demonstrated the RF device such as SAW-BPF, built by the proposed ZnO thin films, shows that it has the bandwidth of 2.98 MHz and the insertion loss of 36.5 dB at the center frequency of 260.8 MHz, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.2
• /
• pp.347-353
• /
• 2012

In this paper, authors will develop the quick and precise remote controller of automatic fire detection equipment (P-type one-class receiver) based on information communication technology (IT). The remote controller detects the fire and disaster in the building automatically and quickly and then activates the facilities to extinguish the fire and disaster, monitoring such situation in a real time through wire-wireless communication network. The proposed remote controller is applied a programmable logic device (PLD) micom. of one-chip type which is small size and lightweight and also has highly sensitive-precise reliabilities. The one-chip type PLD micom. analyzes digital signals from sensors, then activates fire extinguishing facilities for alarm and rapid suppression in a case of fire and disaster. The detected data is also transferred to a remote situation room through wire-wireless network of RS232c and bluetooth communication, and then the situation room sends an emergency alarm signal. The automatic fire detection equipment (AFDE) based on IT will minimize the life and wealth loss while prevents fire and disaster.

• Progress in Superconductivity
• /
• v.13 no.2
• /
• pp.117-121
• /
• 2011

We have fabricated $FeSe_x$ superconducting thin films at much different substrate temperatures of 430 and $610^{\circ}C$ on $Al_2O_3$(0001) substrates by using a pulsed laser deposition (PLD) technique. Superconducting transitions for both films were shown around 10 K, but their transition width and growth directions of grains were different. We found that superconducting tetragonal FeSe phases and non-superconducting hexagonal FeSe phases were coexisted in the sample grown at the low temperature of $430^{\circ}C$, whereas the hexagonal FeSe phase was decreased with increasing fabrication temperatures.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.379-379
• /
• 2012

본 연구에서는 고품질의 ZnO 박막을 제작하기 위해 사파이어 기판 위에 ZnO 박막을 Pulsed Laser Deposition (PLD) 법으로 성장하였다. 레이저 에너지 밀도와 펄스주파수를 고정시켰으며, 성장온도와 산소 분압은 각각 $450{\sim}600^{\circ}C$ 및 5~20 sccm으로 변화를 주어 성장 온도와 산소 분압이 박막 특성에 미치는 영향을 분석하였다. 제작된 박막의 전기적 특성을 측정한 결과 성장온도의 증가에 따라 캐리어 농도는 $9.18{\times}10^{18}cm^{-3}$에서 $3.9{\times}10^{16}cm^{-3}$까지 감소하였고, 캐리어 이동도는 $0.95cm^2/Vs$에서 $8.47cm^2/Vs$ 까지 증가하는 경향을 나타내었으며, 산소분압의 변화에는 특정 임계조건을 갖는 것을 확인하였다. 이러한 이유는 PLD 법 성장 메커니즘에서 플라즈마 플럼(plasma flume) 내에 결합된 ZnO 분자가 기판으로 직접 성장이 이루어지는 과정에서 성장 온도가 증가함에 따라 플럼 내에서 결합 된 ZnO 분자의 열적 안정성이 향상되었으며, 유입되는 산소량의 감소로 인해 원자들의 표면 확산 거리 및 확산 시간이 길어져 보다 안정적인 박막 형성에 기인한 것으로 보인다.

• Proceedings of the Korean Ceranic Society Conference
• /
• 2002.10a
• /
• pp.113.2-113
• /
• 2002

• The Korean Journal of Physiology and Pharmacology
• /
• v.5 no.4
• /
• pp.287-297
• /
• 2001

Contraction of smooth muscle is initiated by an increase in cytosolic $Ca^{2+}$ leading to activation of $Ca^{2+}$/ calmodulin-dependnet myosin light chain (MLC) kinase and phosphorylation of MLC. The types of contraction and signaling mechanisms mediating contraction differ depending on the region. The involvement of these different mechanisms varies depending on the source of $Ca^{2+}$ and the kinetic of $Ca^{2+}$ mobilization. $Ca^{2+}$ mobilizing agonists stimulate different phospholipases $(PLC-{\beta},\;PLD\;and\;PLA_2)$ to generate one or more $Ca^{2+}$ mobilizing messengers $(IP_3\;and\;AA),$ and diacylglycerol (DAG), an activator of protein kinase C (PKC). The relative contributions of $PLC-{\beta},\;PLA_2$ and PLD to generate second messengers vary greatly between cells and types of contraction. In smooth muscle cell derived form the circular muscle layer of the intestine, preferential hydrolysis of $PIP_2$ and generation of $IP_3$ and $IP_3-dependent\;Ca^{2+}$ release initiate the contraction. In smooth muscle cells derived from longitudinal muscle layer of the intestine, preferential hydrolysis of PC by PLA2, generation of AA and AA-mediated $Ca^{2+}$ influx, cADP ribose formation and $Ca^{2+}-induced\;Ca^{2+}$ release initiate the contraction. Sustained contraction, however, in both cell types is mediated by $Ca^{2+}-independent$ mechanism involving activation of $PKC-{\varepsilon}$ by DAG derived form PLD. A functional linkage between $G_{13},$ RhoA, ROCK, $PKC-{\varepsilon},$ CPI-17 and MLC phosphorylation in sustained contraction has been implicated. Contraction of normal esophageal circular muscle (ESO) in response to acetylcholine (ACh) is linked to $M_2$ muscarinic receptors activating at least three intracellular phospholipases, i.e. phosphatidylcholine-specific phospholipase C (PC-PLC), phospholipase D (PLD) and the high molecular weight (85 kDa) cytosolic phospholipase $A_2\;(cPLA_2)$ to induce phosphatidylcholine (PC) metabolism, production of diacylglycerol (DAG) and arachidonic acid (AA), resulting in activation of a protein kinase C (PKC)-dependent pathway. In contrast, lower esophageal sphincter (LES) contraction induced by maximally effective doses of ACh is mediated by muscarinic $M_3$ receptors, linked to pertussis toxin-insensitive GTP-binding proteins of the $G_{q/11}$ type. They activate phospholipase C, which hydrolyzes phosphatidylinositol bisphosphate $(PIP_2),$ producing inositol 1, 4, 5-trisphosphate $(IP_3)$ and DAG. $IP_3$ causes release of intracellular $Ca^{2+}$ and formation of a $Ca^{2+}$-calmodulin complex, resulting in activation of myosin light chain kinase and contraction through a calmodulin-dependent pathway.