• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.75-80
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• 2010

We report Co-tetramethoxyphenylporphyrin on carbon particles (Co-TMPP/C) as a non-Pt catalyst for tri-iodide reduction in dye-sensitized solar cells (DSSCs). The presence of well-dispersed carbon and cobalt source in the catalyst surface is confirmed by transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray analysis. In the C 1s, Co 2p, and N 1s peaks measured by X-ray photoelectron spectroscopy, the C-N, Co-$N_4$, and N-C are assigned to the component at 285.7, 781.8, and 401 eV, respectively. Especially, the Co-TMPP/C shows improved current density, diffusion coefficient, and charge-transfer resistance in the ${I_3}^-/I^-$ redox reaction compared to conventional catalysts. Furthermore, in the DSSCs performance, the Co-TMPP/C shows increased short circuit current density, higher open circuit voltage, and improved cell efficieny in comparison with Pt/C.

• Carbon letters
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• 제16권1호
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• pp.45-50
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• 2015

High crystallinity coke-based activated carbon (hc-AC) is prepared using a potassium hydroxide solution to adsorb carbon dioxide ($CO_2$). The $CO_2$ adsorption characteristics of the prepared hc-AC are investigated at different temperatures. The X-ray diffraction patterns indicate that pitch-based cokes prepared under high temperature and pressure have a high crystal structure. The textural properties of hc-AC indicate that it consists mainly of slit-like pores. Compared to other textural forms of AC that have higher pore volumes, this slit-pore-shaped hc-AC exhibits higher $CO_2$ adsorption due to the similar shape between its pores and $CO_2$ molecules. Additionally, in these high-crystallinity cokes, the main factor affecting $CO_2$ adsorption at lower temperature is the pore structure, whereas the presence of oxygen functional groups on the surface has a greater impact on $CO_2$ adsorption at higher temperature.

• 한국광물학회지
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• 제1권2호
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• pp.83-93
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• 1988

경남 울주군 삼남면 일대에 분포하는 언양화강암내에 발달하는 자수정결정은 하부에서 상부로 가면서 무색수정${\rightarrow}$백수정${\rightarrow}$연수정${\rightarrow}$자수정 순으로 평행연정으로 산출되며 전체외형이 버섯모양과 흡사하다. 수정내에서 관찰되는 유체포유물은 기체포유물(G>L), 액체포유물(L>G), 함$L_{CO_2}$포유물(L+G+$L_{CO_2}$), 함소금포유물(L+G+halite), 다상포유물(L+G+halite+sylvite${\pm}$opaque mineral) 등이며, 고체포유물로는 자형의 카리장석이 무색과 백수정에, 침상의 적철석이 자수정에 특징적으로 내포한다. 유형별 유체포유물의 균일화온도 범위는 기체포유물이 $320{\sim}560^{\circ}C$, 액체포유물이 $100{\sim}290^{\circ}C$, 함$L_{CO_2}$포유물이 $200{\sim}310^{\circ}C$, 함소금포유물이 $300{\sim}430^{\circ}C$, 다상포유물이 $370{\sim}430^{\circ}C$이다. 보석으로서의 언양자수정은 액체포유물의 충진도, 적철석과 함 $L_{CO_2}$ 포유물의 출현, 그리고 얼룩말무늬가 없는 점이 브라질자수정과 다르며, 자색대상구조, 고체포유물, 함 $L_{CO_2}$ 포유물 등의 존재에 의해 합성자수정과 구별된다.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1620-1624
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• 2011

Homologated analogues 3a and 3b of potent and selective A3 adenosine receptor ligands, IB-MECA and dimethyl-IB-MECA were synthesized from commercially available 1-O-acetyl-2,3,5-tri-O-benzoyl-${\beta}$-D-ribofuranose (4) via $Co_2(CO)_8$-catalyzed siloxymethylation as a key step. Unfortunately, homologated analogues 3a and 3b did not show significant binding affinities at three subtypes of adenosine receptors, indicating that free rotation, resulting from homologation, induced unfavorable interactions in the binding site of the receptor maybe due to the presence of many conformations.

• 통합자연과학논문집
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• 제10권4호
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• pp.209-215
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• 2017

CXC chemokine receptor 2 (CXCR2) is a prominent chemokine receptor on neutrophils. CXCR2 antagonist may reduce the neutrophil chemotaxis and alter the inflammatory response because the neutrophilic inflammation in the lung diseases is found to be largely regulated through CXCR2 receptor. Hence, in the present study, Topomer based Comparative Molecular Field Analysis (Topomer CoMFA) was performed on a series of CXCR2 antagonist named pyrimidine-5-carbonitrile-6-alkyl derivatives. The best Topomer COMFA model was obtained with significant cross-validated correlation coefficient ($q^2$ = 0.487) and non cross-validated correlation coefficients ($r^2$ = 0.980). The model was evaluated with six external test compounds and its $r^2{_{pred}}$ was found to be 0.616. The steric and electrostatic contribution map show that presence of bulkier and electropositive group around cyclopropyl ring may contribute more for improving the biological activities of these compounds. The generated Topomer CoMFA model could be helpful for future design of novel and structurally related CXCR2 antagonists.

• IEIE Transactions on Smart Processing and Computing
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• 제6권1호
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• pp.53-59
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• 2017

Optical character recognition (OCR) automatically recognizes text in an image. OCR is still a challenging problem in computer vision. A successful solution to OCR has important device applications, such as text-to-speech conversion and automatic document classification. In this work, we analyze character recognition performance using the current state-of-the-art deep-learning structures. One is the AlexNet structure, another is the LeNet structure, and the other one is the SPNet structure. For this, we have built our own dataset that contains digits and upper- and lower-case characters. We experiment in the presence of salt-and-pepper noise or Gaussian noise, and report the performance comparison in terms of recognition error. Experimental results indicate by five-fold cross-validation that the SPNet structure (our approach) outperforms AlexNet and LeNet in recognition error.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2377-2380
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• 2009

The treatment of primary amines with amino acids as a CO source in the presence of polyaniline emeraldine salts bring about N-formylation to give the corresponding formamides. This route to N-formylation methodology of primary amine represents the first reported example of a CO-transfer via radical mechanism by highly nanoporous polyaniline emeraldine salts catalyst.

• ETRI Journal
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• 제38권1호
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• pp.30-40
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• 2016

Co-channel interference between macro-femtocell networks is an unresolved problem, due to the frequency reuse phenomenon. To mitigate such interference, a secondary femtocell must acquire channel-state knowledge about a co-channel macrocell user and accordingly condition the maximum transmit power of femtocell user. This paper proposes a pilot-based spectrum sensing (PSS) algorithm for overlaid femtocell networks to sense the presence of a macrocell user over a channel of interest. The PSS algorithm senses the pilot tones in the received signal through the power level and the correlation metric comparisons between the received signal and the local reference pilots. On ensuring the existence of a co-channel macrocell user, the maximum transmit power of the corresponding femtocell user is optimized so as to avoid interference. Time and frequency offsets are carefully handled in our proposal. Simulation results show that the PSS algorithm outperforms existing sensing techniques, even at poor received signal quality. It requires less sensing time and provides better detection probability over existing techniques.

• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.691-694
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• 2009

Pauson-Khand reaction of hydroxyenynes with $Co_2(CO)_8$ in the presence of N-methylmorpholine N-oxide or trimethylamine N-oxide as a promoter produced polycyclic $gamma$-lactams as single stereoisomers in moderate to excellent yield. These are the first examples of an intramolecular Pauson-Khand reaction on a hydroxyenyne system tethered to a three- and four-membered ring as new skeletons with 5,6,5 fused ring systems.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.565-568
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• 2013

Acetyl-CoA carboxylases (ACCs) play critical roles in fatty acid synthesis and oxidation by the catalytic activity of the carboxylation of acetyl-CoA to malonyl-CoA. It is known that ACCs are inactivated through reversible phosphorylation by AMP-activated protein kinase (AMPK) and allosterically activated by citrate. Here, we determined the crystal structures of biotin carboxylase (BC) domain of human ACC2 phosphorylated by AMPK in the presence of citrate in order to elucidate the activation mechanism by citrate. This structure shows that phosphorylated Ser222 is released from the dimer interface, and thereby facilitating the dimerization or oligomerization of the BC domain allosterically. This structural explanation is coincident with the experimental result that the phosphorylated Ser222 was dephosphorylated more easily by protein phosphatase 2A (PP2A) as the citrate concentration increases.