• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.3052-3058
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• 2014

In this article, we have designed and synthesized a novel donor-${\pi}$-acceptor (D-${\pi}$-A) type porphyrin-based sensitizer (denoted UI-5), in which a carboxyl anchoring group and a 9,9-dimethyl fluorene were introduced at the meso-positions of porphyrin ring via phenylethynyl and ethynyl bridging units, respectively. Long alkoxy chains in ortho-positions of the phenyls were supposed to reduce the degree of dye aggregation, which tends to affect electron injection yield in a photovoltaic cell. The cyclic voltammetry was employed to determine the band gap of UI-5 to be 1.41 eV based on the HOMO and LUMO energy levels, which were estimated by the onset oxidation and reduction potentials. The incident monochromatic photon-to-current conversion efficiency of the UI-5 DSSC assembled with double-layer (20 nm-sized $TiO_2$/400 nm-sized $TiO_2$) film electrodes appeared lower upon overall ranges of the excitation wavelengths, but exhibited a higher value over the NIR ranges (${\lambda}$ = 650-700 nm) compared to the common reference sensitizer N719. The UI-5-sensitized cell yielded a relatively poor device performance with an overall conversion efficiency of 0.74% with a short circuit photocurrent density of $3.05mA/cm^2$, an open circuit voltage of 0.54 mV and a fill factor of 0.44 under the standard global air mass (AM 1.5) solar conditions. However, our report about the synthesis and the photovoltaic characteristics of a porphyrin-based sensitizer in a D-${\pi}$-A structure demonstrated a significant complex relationship between the sensitizer structure and the cell performance.

• Structural Engineering and Mechanics
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• v.12 no.6
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• pp.657-668
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• 2001

Fiber reinforced cementitious composites are nowadays widely applied in civil engineering. The postcracking performance of this material depends on the interaction between a steel fiber, which is obliquely across a crack, and its surrounding matrix. While the partly debonded steel fiber is subjected to pulling out from the matrix and simultaneously subjected to transverse force, it may be modelled as a Bernoulli-Euler beam partly supported on an elastic foundation with non-linearly varying modulus. The fiber bridging the crack may be cut into two parts to simplify the problem (Leung and Li 1992). To obtain the transverse displacement at the cut end of the fiber (Fig. 1), it is convenient to directly solve the corresponding differential equation. At the first glance, it is a classical beam on foundation problem. However, the differential equation is not analytically solvable due to the non-linear distribution of the foundation stiffness. Moreover, since the second order deformation effect is included, the boundary conditions become complex and hence conventional numerical tools such as the spline or difference methods may not be sufficient. In this study, moment equilibrium is the basis for formulation of the fundamental differential equation for the beam (Timoshenko 1956). For the cantilever part of the beam, direct integration is performed. For the non-linearly supported part, a transformation is carried out to reduce the higher order differential equation into one order simultaneous equations. The Runge-Kutta technique is employed for the solution within the boundary domain. Finally, multi-dimensional optimization approaches are carefully tested and applied to find the boundary values that are of interest. The numerical solution procedure is demonstrated to be stable and convergent.

• STI Policy Review
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• v.3 no.2
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• pp.130-151
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• 2012

Fraunhofer was founded in 1949 and grew into Europe's largest application-oriented research organization. Fraunhofer currently employs over 20,000 members in Germany, is internationally networked, and manages an R&D budget of over 1,8 Billion Euros per year. An important step for Fraunhofer to become an integral component of the German innovation system was the introduction of the Fraunhofer Model of financing based on a performance-related system of financial management. The underlying model of the allocation and distribution of public funding to Fraunhofer that is subsequently allotted to specific research groups is one of the success factors of Fraunhofer. Fraunhofer is proud of its decentralized organizational model. Fraunhofer is comprised of 60 Institutes in Germany working in different fields, under one legal framework, and with a strong brand value. Every Fraunhofer Institute is affiliated with a German University and every institute director simultaneously holds a chair at the affiliated university. It is a challenge for the headquarter organization to balance the intended competition of individual Fraunhofer Institutes with complementarity cooperation in science among Fraunhofer-Institutes, especially when coming from different knowledge domains; however, this goal results in a significant advantage. The unique strengths of Fraunhofer offer system solutions in a world with increasingly complex R&D challenges. While growing to become the largest organization on Europe to focus on applied research it is the challenge to remain an agile organization that is flexible in organizational structure. Fraunhofer has reached a well-recognized position in the European innovation landscape. It is often referred to by science and governments as a role model for innovation policy and a key element of the latest successes in the German economy that has recovered quicker from the latest economic crisis than most other western economies. The paper explains Fraunhofer as an organizational paradigm and its underlying management model to elaborate on the challenges of managing a research organization. We wish to show how it is possible to transfer the management model and philosophy of Fraunhofer to innovation systems with different framework conditions and challenges. A universal conclusion may be drawn based on the description of Fraunhofer; however, changes in existing structures and innovation systems cannot be implemented over night.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.76.2-76.2
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• 2013

Advanced electronic application areas have strongly required new materials due to the continuous shrinking dimensions of their devices. Specially, the development and use of metal precursors for atomic layer deposition has been extensively focused on application to electronic devices. Thus the systematic design and synthesis of metal compounds with relevant chemical and physical properties, such as stability, volatility, and resistance to air and moisture are very important in the vacuum deposition fields. In many case, organic ligands for metal precursors are especially focused in the related research areas because the large scale synthesis of the metal complexes with excellent properties exclusively depends on the potential usefulness of the ligands. It is recommended for metal complexes to be in monomeric forms because mononuclear complexes generally show high vapor pressures comparing with their oligomeric structure such as dimer and trimer. Simple metal alkoxides complexes are involatile except several examples such as Ti(OiPr)4, Si(OEt)4, and Hf(OtBu)4. Thus the coordinated atom of alkoxide ligands should be crowded in its own environment with some substituents by prohibiting the coordinated atoms from bonding to another metal through oxygen-bridging configuration. Alkoxide ligands containing donor-functionalized group such as amino and alkoxy which can induce the increasing of the coordinative saturation of the metal complexes and the decreasing of the intermolecular interaction between or among the metal compounds. In this presentation, we will discuss the development of metal compounds which adopted donor-functionalized alkoxide ligands derived from their alcohols for electronic application. Some recent results on ALD using metal precursors such as tin, nickel, ruthenium, and tungsten developed in our group will be disclosed.

• Tunnel and Underground Space
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• v.26 no.3
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• pp.212-219
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• 2016

The sprayable waterproofing membrane is installed between shotcrete to provide crack bridging and hence prevent flow of liquid water as a waterproofing system. Because of its material characteristics, the sprayable membrane can be constructed at more complex structure than sheet membrane. The main component of the sprayable waterproofing membrane is a polymer-based material, therefore, moisture can migrate through sprayable waterproofing membrane materials by capillary and vapor diffusion mechanisms. The moisture transport mechanisms can have an influence on the degree of saturation and may influence the pore pressure and risk of freeze-thaw damage on concrete linings and membrane. In this study, long-term hygrothermal behavior was simulated with considering moisture transport and long-term effects on saturation of tunnel linings. From the simulation, due to water absorption and vapor transport properties of sprayable membrane, change of relative humidity and water content in tunnel lining can be evaluated.

• Molecules and Cells
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• v.47 no.1
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• pp.100005.1-100005.15
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• 2024

Amyotrophic lateral sclerosis is a devastating neurodegenerative disease with a complex genetic basis, presenting both in familial and sporadic forms. The hexanucleotide (G₄C₂) repeat expansion in the C9orf72 gene, which triggers distinct pathogenic mechanisms, has been identified as a major contributor to familial and sporadic Amyotrophic lateral sclerosis cases. Animal models have proven pivotal in understanding these mechanisms; however, discrepancies between models due to variable transgene sequence, expression levels, and toxicity profiles complicate the translation of findings. Herein, we provide a systematic comparison of 7 publicly available Drosophila transgenes modeling the G₄C₂ expansion under uniform conditions, evaluating variations in their toxicity profiles. Further, we tested 3 previously characterized disease-modifying drugs in selected lines to uncover discrepancies among the tested strains. Our study not only deepens our understanding of the C9orf72 G₄C₂ mutations but also presents a framework for comparing constructs with minute structural differences. This work may be used to inform experimental designs to better model disease mechanisms and help guide the development of targeted interventions for neurodegenerative diseases, thus bridging the gap between model-based research and therapeutic application.

• Economic and Environmental Geology
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• v.38 no.1
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• pp.23-31
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• 2005

This study was performed to investigate the effect of humic acid on the adsorption of arsenic onto hematite and its binding mechanism through the chemical speciation modeling in the binary system and the adsorption modeling in the ternary system. The complexation modeling of arsenic and humic acid was suitable for the binding model with the basis of the electrostatic repulsion and the effect of bridging metal. In comparison with the experimental adsorption data in the ternary system, the competitive adsorption model from the binary intrinsic equilibrium constants was consistent with the amount of arsenic adsorption. However, the additive rule showed the deviation of model in the opposite way of cationic heavy metals, because the reduced organic complexation of arsenic and the enhanced oxyanionic competition diminished the adsorption of arsenic. In terms of the reaction mechanism, the organic complex of arsenic, neutral As(III) and oxyanionic As(V) species were transported and adsorbed competitively to the hematite surface forming the inner-sphere complex in the presence of humic acid.

• Polymer(Korea)
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• v.24 no.2
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• pp.159-167
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• 2000

The polymethylene-bridged dinuclear half-titanocenes [(CH$_2$)$_{n}$(C$_{5}$ H$_4$)$_2$][TiCl$_3$]$_2$ (n=5(10), 7(11), 9(12)) have been synthesized by treating the distannylated derivatives of the ligands with two equivalents of TiCl$_4$ in toluene. All complexes are characterized by IR, $^1$H NMR, $^{13}$ C NMR and mass spectrometry. In order to examine the catalytic properties of the dinuclear complexes styrene polymerization has been conducted in the presence of MMAO. From the polymerization experiments it was found that ( i ) all the prepared complexes 10-12 produced syndiotactic polystyrenes, ( ii ) the complex 12 holding the longest bridging ligand exhibited the highest activity but produced a polymer having the smallest molecular weight among the polymethylene-bridged dinuclear half-titanocenes. This behavior was attributed to the influence of electron-donating caused by the polymethylene bridge between two active centers as well as the effect of steric congestion around metal center caused by the proximal distance between two active sites.s.

• Journal of the Korean Chemical Society
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• v.62 no.5
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• pp.358-363
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• 2018

The purpose of this study is to show the possibility of using Cu catalyst in removal of $NO_x$ from automobile exhaust which is regarded as the primary source of fine dust PM2.5. The energy and the bond lengths of the three possible structures of Cu-NO complex, which is formed by binding NO molecule to Cu, and the changes in IR and Raman spectra are calculated using MPW1PW91 method on the level of 6-311(+)G(d,p) of basis sets with Gaussian 09 program. As a result, the enthalpy of formation of the Cu-NO complexes are obtained as ${\Delta}H=104.89$, 91.98, -127.48 kJ/mol for the linear, bent, and bridging forms of them, respectively. And the bond lengths between N and O in NO complexes, which becomes longer than NO molecule, indicates that O is easily reduced from Cu-NO. In addition, the Cu-NO complexes using Cu catalyst can be easily measured by infrared or Raman spectroscopy because in the IR and Raman spectra of the NO and Cu-NO complexes the positon and the intensity of bands are definitely different in each vibration mode.

• Journal of the Korea Society of Computer and Information
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• v.29 no.3
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• pp.21-41
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• 2024

This study explores the relationship between users' attachment styles and their interactions with ChatGPT (Chat Generative Pre-trained Transformer), an advanced language model developed by OpenAI. As artificial intelligence (AI) becomes increasingly integrated into everyday life, it is essential to understand how individuals with different attachment styles engage with AI chatbots in order to build a better user experience that meets specific user needs and interacts with users in the most ideal way. Grounded in attachment theory from psychology, we are exploring the influence of attachment style on users' interaction with ChatGPT, bridging a significant gap in understanding human-AI interaction. Contrary to expectations, attachment styles did not have a significant impact on ChatGPT usage or reasons for engagement. Regardless of their attachment styles, hesitated to fully trust ChatGPT with critical information, emphasizing the need to address trust issues in AI systems. Additionally, this study uncovers complex patterns of attachment styles, demonstrating their influence on interaction patterns between users and ChatGPT. By focusing on the distinctive dynamics between users and ChatGPT, our aim is to uncover how attachment styles influence these interactions, guiding the development of AI chatbots for personalized user experiences. The introduction of the Perceived Partner Responsiveness Scale serves as a valuable tool to evaluate users' perceptions of ChatGPT's role, shedding light on the anthropomorphism of AI. This study contributes to the wider discussion on human-AI relationships, emphasizing the significance of incorporating emotional intelligence into AI systems for a user-centered future.