• Analytical Science and Technology
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• v.7 no.4
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• pp.505-515
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• 1994

$^1H$ NMR spectra for monocyanide ligated ferriprotoporphyrin(hemin) complex and dicyanide coordinated hemin complex in dimethylsulfoxide(DMSO-$d_6$) solution have been recorded and analyzed. NMR spectra of hemin-cyanide complexation in DMSO-$d_6$ exhibit that the cyanide ligation to hemin is temperature-dependent. Thermodynamic parameters for the monocyanide ligated hemin to dicyanide ligated hemin are consistent with endothermic process with ${\Delta}H^{\circ}=736.6cal/mol$ and ${\Delta}S^{\circ}=16.4eu$. Detailed analysis of the anomalous deviation from Curie behavior for CN/DMSO coordinated hemin complex demonstrates the presence of a high spin character, and this weaker axial field relative to the purely low-spin dicyanide hemin complex is supposed to attribute to instantaneously ruptured iron-DMSO bond. This complex may serve as a useful model to characterize electronic/molecular structure of hemoproteins, which one of axial ligands is weak.

• Publications of The Korean Astronomical Society
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• v.12 no.1
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• pp.99-109
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• 1997

We obtained the CN($\Delta_V=0$) and $C_2(\Delta_V=0,\;\pm1$) spectra of comet Hale-Bopp(C/1995 O1) at the Kyunghee Observatory and Bohyunsan Astronomical Observatory between March 7 and May 12, 1997 The fluxes for each molecular band were measured and then the production rates and column densities of CN and $C_2$ were calculated using a simple model. The resultantproduction rates of CN and $C_2$ are logQ(CN)=27.4 at r=0.94 AU(preperihelion) and $logQ(C_2)=27.3$ at r=0.94 AU(postperihelion), respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.2
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• pp.184-201
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• 2013

In this paper, we study the problem of designing the power and number of cooperative node (CN) in the cooperation phase to maximize the average throughput for secondary user (SU), under the constraint of the total cooperation and transmission power. We first investigate the scheme of cooperative spectrum sensing without a separated control channel. Then, we prove that there indeed exist an optimal CN power when the number of CNs is fixed and an optimal CN number when CN power is fixed. The case without the constraints of the power and number of CN is also studied. Finally, numerical results demonstrate the characteristics and existences of optimal CN power and number. Meanwhile, Monte Carlo simulation results match to the theoretical results well.

• Journal of Korea Water Resources Association
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• v.30 no.4
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• pp.379-387
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• 1997

This study involves field monitoring of hydrlolgic characteristics of paddy fields under common irrigation practice, statistical analysis of maximum retention storage, determination of CNs for antecedent moisture conditions. Curve numbers were estimated from observed rainfall-runoff relationship of two years data. The estimated CN for AMC-II was 78, and the CNs for AMC-I and II were 63 and 88, respectively. A water balance model was used to find the effect of ridge height changes and initial ponding depth in paddy fields on runoff. The probability distribution of initial ponding depth was also investigated. The initial ponding depth follows normal probability distribution. Initial ponding depth corresponding 10%, 50%, and 90% probability were considered to be equivalent to AMC-I, AMC-II, and AMC-III, respectively. Long-term runoff data from paddy fields were simulated by a water balance model using recorded climate data, ridge height and estimated initial ponding depth derived from probability distribution. The estimated CNs using simulated runoff were 70, 79, and 89 for CN-I, CN-II, and CN-III, respectively.

• Journal of Sensor Science and Technology
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• v.15 no.1
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• pp.53-57
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• 2006

This paper describes a novel processing technique for fabrication of polymer-derived SiCN (silicone carbonitride) microstructures for super-temperature MEMS applications. PDMS (polydimethylsiloxane) mold is fabricated on SU-8 photoresist using standard UV photolithographic process. Liquid precursor is injected into the PDMS mold. Finally, solid polymer structure is cross-linked using HIP (hot isostatic pressure) at $400^{\circ}C$, 205 bar. Optimum pyrolysis and annealing conditions are determined to form a ceramic microstructure capable of withstanding over $1400^{\circ}C$. The fabricated SiCN ceramic microstructure has excellent characteristics, such as shear strength (15.2 N), insulation resistance ($2.163{\times}10^{14}{\Omega}$) and BDV (min. 1.2 kV) under optimum process condition. These fabricated SiCN ceramic microstructures have greater electric and physical characteristics than bulk Si wafer. The fabricated SiCN microstructures would be applied for supertemperature MEMS applications such as heat exchanger and combustion chamber.

• Bulletin of the Korean Chemical Society
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• v.32 no.spc8
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• pp.2955-2959
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• 2011

Second-order rate constants for nucleophilic substitution reactions of 2,4-dinitrophenyl benzenesulfonate 1a with a series of alicyclic secondary amines in MeCN have been measured spectrophotometrically and compared with those reported previously for the corresponding reactions performed in aqueous medium to investigate the effect of medium on reactivity and reaction mechanism. The amines employed in this study are found to be more reactive in the aprotic solvent than in $H_2O$. The reactions of 1a in MeCN result in a linear Br${\o}$nsted-type plot with ${\beta}_{nuc}$ = 0.58, which contrasts to the curved Br${\o}$nsted-type plot reported previously for the corresponding reactions performed in the aqueous medium (i.e., ${\beta}_2$ = 0.86 and ${\beta}_1$ = 0.38). Accordingly, it has been concluded that the reaction mechanism changes from a stepwise mechanism to a concerted pathway upon changing the medium from $H_2O$ to MeCN. Reactions of Y-substituted phenyl benzenesulfonates 1a-c with piperidine in MeCN result in a linear Br${\o}$nsted-type plot with ${\beta}_{lg}$ = -1.31, indicating that expulsion of the leaving group is significantly more advanced than bond formation in the transition state. The trigonal bipyramidal intermediate ($TBPy^{\pm}$) proposed previously for the reactions in $H_2O$ would be highly unstable in MeCN due to strong repulsion between the negative charge in $TBPy^{\pm}$ and the negative dipole end of MeCN. Thus, destabilization of $TBPy^{\pm}$ in MeCN has been concluded to change the reaction mechanism from a stepwise mechanism to a concerted pathway.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.392-393
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• 2006

This paper describes the fabrication of SiCN microstructures for super-high temperature MEMS using photopolymerization of pre-ceramic polymer. In this work. polysilazane liquide as a precursor was deposited on Si wafers by spin coating. microstructured and solidificated by UV lithography. and removed from the substrate. The resulting solid polymer microstructures were cross-linked under HIP process and pyrolyzed to form a ceramic of withstanding over $1400^{\circ}C$. Finally, the fabricated SiCN microstructures were annealed at $1400^{\circ}C$ in a nitrogen atmosphere. Mechanical characteristics of the SiCN microstructure with different fabrication process conditions were evaluated. The elastic modules. hardness and tensile strength of the SiC microstructure implemented under optimum process conditions are 94.5 GPa, 10.5 GPa and 11.7 N/min, respectively. Consequently, the SiCN microstructure proposed in this work is very suitable for super-high temperature MEMS application due to very simple fabrication process and the potential possiblity of sophisticated multlayer or 3D microstructures as well as its good mechanical properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.125-128
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• 2004

In this paper, a novel processing technique for fabrication of high-temperature MEMS based on polymer-derived SiCN microstructures is described. PDMS molds are fabricated on SU-8 photoresist using standard UV-photolithographic processes. Liquid precursors are injected into the PDMS mold. And then, the resulting solid polymer structures are crosslinked under isostatic pressure, and pyrolyzed to form a ceramic capable of withstanding over $1500^{\circ}C$. These fabricated SiCN structures would be applied for high-temperature applications, such as heat exchanger and combustion chamber.

• Proceedings of the Optical Society of Korea Conference
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• 1990.07a
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• pp.94-100
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• 1990

The rapid quenching dynamics of the F-center excitation by CN- defects in CsCl crystals were investigated by monitoring the ground state bleach recovery kinetics of F-centers, using a picosecond streak camera absorption spectrometer. The F-centers in CN- doped quenched samples show two bleach recovery components. Optical aggregation converts the slow component to the fast component. The slow one is due to the normal relaxation of the F*-centers as found in CN_ free crystals. The fast one is due to the energy transfer of the F-center electronic excitation to the vibrational energy levels of CN_ molecualr defects. The energy transfer occurs only in the F-center-CN_ defect pairs, FH(CN_)-centers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.376-379
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• 2003

In this paper, a novel processing technique for fabrication of high-temperature MEMS based on polymer-derived SiCN microstructures is described. PDMS molds are fabricated on SU-8 photoresist using standard UV-photolithographic processes. Liquid precursors are injected into the PDMS mold. And then, the resulting solid polymer structures are crosslinked under isostatic pressure, and pyrolyzed to form a ceramic capable of withstanding over $1500^{\circ}C$. These fabricated SiCN structures would be applied for high-temperature applications, such as heat exchanger and combustion chamber.