신뢰성을 고려한 광통신 네트워크 설계를 위한 유전자 알고리즘

이재욱,김종률,박월선 東西大學校 2001 동서논문집 Vol.7 No.-

Increasing attention is being recently devoted to various problems inherent in the topological design of destributed telecommunication networks. In the distributed telecommunication networking, the topological structure of these networks is based on a single central office (exchanger), a number of multiplexing centers, and a lot of users. Especially, considering the high cost of the fiber optic cable that is used to connect the between centers and the between center and users, the network architecture is composed of a spanning tree. The optimization problem is reduced to choose the number and locations of the multiplexing centers, with network reliability constraints. Recenlly, genetic algorithms (GAs) have got a great advancement in related research fields, such as network optimization problem, combinatorial optimization, multiobjective optimization, and so on, and have received a great deal of attention about its ability as optimization techniques for many real-world problems. In this paper, a GA approach is presented for network topology design of wide-band multiplexed networks, considering the network reliability related to the probability of failures. We also employ the Pru˝fer number and clustering string in order to represent chromosomes. Finally, we get some experiments in order to certify the Quality of the network designs obtained by using proposed GA.

선천성 완전방실차단이 동반된 신생아 루프스 1예

정재현,이은지,이은주,황진원,송영진,최병진,김일환,김종윤,허민영,김동욱 인제대학교 2009 仁濟醫學 Vol.30 No.-

Neonatal lupus is a rare syndrome occurring In neonates with tranplacentally acquired maternal autoantibodies, In particular anti-SSA/Ro-SSB/Ra antibodies. Manifestations include congenital heart block, cutaneous lesions, thrombocytopenia, neutropenia, pulmonary or neurological disease and hepatitis. The non-cardiac manifestations resolve by 6 months of age, congenital heart block is irreversible. We experienced a case of neonatal lupus with congenital complete heart block in a newborn of asyptomatic mother with anti-SSA/Ro-SSB/Ra antibodies.

하이브리드 유전자 알고리즘을 이용한 다목적 신뢰성 설계

김종률,박월선,이재욱 東西大學校 2001 동서논문집 Vol.7 No.-

A bicriteria reliability apportionment problem for a system consisting n subsystems with time-dependent reliability is manipulated in this paper. This reliability design problem with two objectives determines the optimum level of component reliability and the number of redundant components at each subsystem. The problem is formulated as a bicriteria nonlinear mixed integer programming problem, subject to several design constraints. Also, a hybrid genetic algorithm is used in this paper to find an optimal or near optimal solution and we propose the method which search the Pareto solutions of bicriteria reliability apportionment problems. Furthermore, numerical experiments are illustrated to demonstrate the efficiency of the proposed method.

Degradation and stability of polymer-based solar cells

Lee, Jea Uk,Jung, Jae Woong,Jo, Jea Woong,Jo, Won Ho The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.46

<P>Stability of polymer solar cells (PSCs) is critically important for PSCs to be commercialized. The performance deterioration of PSCs arises mainly from macrophase separation of the finely tuned nanoscale morphology of donor–acceptor blends, photo-degradation of active layer materials, and oxidative degradation of donor polymers due to diffusion of oxygen and water molecules from the interlayer/electrode. In this article, the degradation mechanisms of various types of active layer materials are discussed and the methods how to protect the active layer materials from degradation to stabilize the device performance of PSCs are extensively discussed based on recent publications.</P> <P>Graphic Abstract</P><P>The degradation mechanisms of active layer materials are discussed and their protection from degradation are extensively discussed. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm33645f'> </P>

Efficiency enhancement of P3HT/PCBM bulk heterojunction solar cells by attaching zinc phthalocyanine to the chain-end of P3HT

Lee, Jea Uk,Kim, Young Do,Jo, Jea Woong,Kim, Jae Pil,Jo, Won Ho Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.43

<P>A new solution processable zinc phthalocyanine dye (ZnPc), as an interface modifier between poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C<SUB>61</SUB>-butyric acid methyl ester (PCBM) in bulk heterojunction solar cells, was successively synthesized and linked to the chain-end of P3HT through the formation of a coordination complex. ZnPc dye molecules do not aggregate but preferentially locate at the interface between P3HT and PCBM, and thus contribute to the photocurrent generation by both direct photo-excitation and enhancement of charge transfer between P3HT and PCBM. To localize the zinc phthalocyanine dyes at the donor–acceptor interface more effectively, another new organic dye molecule, fullerene-functionalized zinc phthalocyanine (ZnPc-C<SUB>60</SUB>) was also synthesized and linked to the chain-end of the P3HT, where ZnPc-C<SUB>60</SUB> contributes not only to the photocurrent generation by direct photo-excitation, but also lowers the interfacial tension, resulting in the reduction of the domain size and the suppression of the macrophase separation of the P3HT/PCBM blend for prolonged thermal annealing. This leads to higher device efficiency with 20% enhancement of the short circuit current and to enhancement of long-term thermal stability of device performance as compared to that of the reference P3HT/PCBM device.</P> <P>Graphic Abstract</P><P>New solution processable zinc phthalocyanine dyes linked at the chain-end of P3HT do not aggregate but preferentially locate at the interface between P3HT and PCBM, and thus contribute to the photocurrent generation. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1jm11563d'> </P>

Synthesis and Micellar Properties of T-shaped Oligothiophene-g-PEG Copolymer

Jea Uk Lee,Keon Hyung Kim,June Huh,Won Ho Jo 한국고분자학회 2006 한국고분자학회 학술대회 연구논문 초록집 Vol.2006 No.10

Aqueous suspension of carbon nanotubes via non-covalent functionalization with oligothiophene-terminated poly(ethylene glycol)

Lee, Jea Uk,Huh, June,Kim, Keon Hyeong,Park, Cheolmin,Jo, Won Ho Elsevier 2007 Carbon Vol.45 No.5

<P><B>Abstract</B></P><P>A new polymeric amphiphilic molecule for dispersing carbon nanotubes (CNTs) in water, oligothiophene-terminated poly(ethylene glycol) (TN-PEG), was synthesized and its ability to stabilize aqueous CNT dispersions was examined by UV–Vis spectroscopy and transmission electron microscopy. It was observed that the TN-PEGs were strongly adsorbed onto the nanotube surface via a strong π–π interaction, and thus only gentle sonication causes exfoliation of CNT ropes and bundles into well-separated individual objects and small bundles comprising 2–10 tubes. The dispersion ability of the TN-PEGs and the long-term stability of their resulting dispersions were much better than commercial surfactants.</P>

Synthesis of C₆₀-end capped P3HT and its application for high performance of P3HT/PCBM bulk heterojunction solar cells

Lee, Jea Uk,Jung, Jae Woong,Emrick, Todd,Russell, Thomas P.,Jo, Won Ho Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.16

<P>A new C<SUB>60</SUB>-end capped poly(3-hexylthiophene) (P3HT-C<SUB>60</SUB>) was synthesized <I>via</I> a simple three-step process, and used as a compatibilizer for P3HT/PCBM composite for the purpose of controlling the morphology of P3HT/PCBM composite film, and thus improving the long-term thermal stability of solar cell performance. When a small amount of P3HT-C<SUB>60</SUB> was added to P3HT/PCBM, the bicontinuous and nanometre-scale film morphology was developed and preserved for 2 h of annealing at 150 °C. Furthermore, the addition of P3HT-C<SUB>60</SUB> as a compatibilizer suppressed large-scale phase separation of P3HT/PCBM composite even after prolonged annealing time (8 days), and as a result, the P3HT/PCBM/P3HT-C<SUB>60</SUB> bulk heterojunction solar cells exhibited the excellent long-term thermal stability of device performance.</P> <P>Graphic Abstract</P><P>A new C<SUB>60</SUB>-end capped poly(3-hexylthiophene) was synthesized <I>via</I> a simple three-step process, and used as a compatibilizer for P3HT/PCBM composite for the purpose of controlling the morphology of P3HT/PCBM composite film and thus improving the long-term thermal stability of solar cell performance. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b923752f'> </P>

Synthesis and photophysical property of well-defined donor–acceptor diblock copolymer based on regioregular poly(3-hexylthiophene) and fullerene

Lee, Jea Uk,Cirpan, Ali,Emrick, Todd,Russell, Thomas P.,Jo, Won Ho Royal Society of Chemistry 2009 Journal of materials chemistry Vol.19 No.10

<P>A new, well-defined diblock copolymer (P3HT-<I>b</I>-C<SUB>60</SUB>) based on regioregular poly(3-hexylthiophene) (P3HT) and fullerene was synthesized. First, regioregular P3HT was synthesized through Grignard metathesis polymerization, and then methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) were copolymerized by using an end-functionalized P3HT as a macroinitiator for the atom transfer radical polymerization to yield a diblock copolymer (P3HT-<I>b</I>-P(MMA-<I>r</I>-HEMA)). A fullerene derivative functionalized with carboxylic acid, [6,6]-phenyl-C<SUB>61</SUB>-butyric acid (PCBA), was then chemically linked to the HEMA unit in the second block (P(MMA-<I>r</I>-HEMA)) to produce a diblock copolymer with the second block containing fullerenes. Annealing thin films of the copolymer revealed nanometer-scale phase separation, a more suitable morphology for enabling excitons generated in the P3HT domain to more efficiently reach the donor–acceptor interface, relative to simple blends of P3HT and C<SUB>60</SUB>. As a result, photoluminescence of the P3HT-<I>b</I>-C<SUB>60</SUB> diblock copolymer in the films showed a complete quenching of photoluminescence of P3HT, which is indicative of charge transfer between P3HT and fullerene.</P> <P>Graphic Abstract</P><P>A new, well-defined diblock copolymer (P3HT-<I>b</I>-C<SUB>60</SUB>) based on regioregular P3HT and fullerene showed phase separation on a nanometer scale, which allows the excitons generated in the P3HT domain to reach the donor–acceptor interface more efficiently. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b813368a'> </P>

Morphology control of a polythiophene–fullerene bulk heterojunction for enhancement of the high-temperature stability of solar cell performance by a new donor–acceptor diblock copolymer

Lee, Jea Uk,Jung, Jae Woong,Emrick, Todd,Russell, Thomas P,Jo, Won Ho IOP Pub 2010 Nanotechnology Vol.21 No.10

<P>A well defined diblock copolymer (P3HT-<I>b</I>-C<SUB>60</SUB>) based on regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was synthesized via two controlled polymerization steps and used as a compatibilizer for the P3HT/PCBM blend, which has widely been used as an active layer in bulk heterojunction polymer solar cells. The addition of a small amount of P3HT-<I>b</I>-C<SUB>60</SUB> results in not only the reduction of phase size of P3HT/PCBM blend but also the suppression of macrophase separation for long-time thermal annealing owing to the preferential location of the diblock copolymers at the interface between P3HT and PCBM phases. The morphology change with the annealing time is closely related to the change of the power conversion efficiency (PCE) of solar cells: the PCE of P3HT/PCBM greatly decreases with increasing annealing time while the addition of P3HT-<I>b</I>-C<SUB>60</SUB> significantly reduces the decrease of PCE for long-time thermal annealing. </P>