• Journal of the Society of Disaster Information
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• v.20 no.2
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• pp.339-350
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• 2024

Purpose: This study analyzes accessibility of 10 hydrogen charging stations in Seoul and identifies areas that were difficult to access. The purpose is to re-analyze accessibility by adding a new location in terms of equity and safety of location placement, and then draw implications by comparing the improvement effects. Method: By applying the location-allocation model and the service area model based on network analysis of the ArcGIS program, areas with weak access were identified. The location selection method applied the 'Minimize Facilities' method in consideration of the need for rapid arrival to insufficient hydrogen charging stations. The limit distance for arrival within a specific time was analyzed by applying the average vehicle traffic speed(23.1km/h, Seoul Open Data Square) in 2022 to three categories: 3,850m(10minutes), 5,775m(15minutes), 7,700m(20minutes). In order to minimize conflicts over the installation of hydrogen charging stations, special standards of the Ministry of Trade, Industry and Energy applied to derive candidate sites for additional installation of hydrogen charging stations among existing gas stations and LPG/CNG charging stations. Result: As a result of the analysis, it was confirmed that accessibility was significantly improved by installing 5 new hydrogen charging stations at relatively safe gas stations and LPG/CNG charging stations in areas where access to the existing 10 hydrogen charging stations is weak within 20 minutes. Nevertheless, it was found that there are still areas where access remains difficult. Conclusion: The location allocation model is used to identify areas where access to hydrogen charging stations is difficult and prioritize installation, decision-making to select locations for hydrogen charging stations based on scientific evidence can be supported.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5227-5237
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• 2011

Technology roadmap is a powerful tool that considers relationships of technology, product and market and referred as a supporting technology strategy and planning. There are numerous studies that have attempted to develop technology roadmap and case studies on specific technology areas. However, a number of studies have been dependant on brainstorming and discussion of expert group, delphi technique as qualitative analysis rather than systemic and quantitative analysis. To overcome the limitation, patent analysis considered as quite quantitative analysis is employed in this paper. Therefore, this paper proposes new technology roadmapping based on patent citation network considering technology life cycle and suggests planning for undeveloped technology but considered as promising. At first, patent data and citation information are collected and patent citation network is developed on the basis of collected patent information. Secondly, we investigate a stage of technology in the life cycle by considering patent application year and the technology life cycle, and duration of technology development is estimated. In addition, subsequent technologies are grouped as nodes of a super-level technology to show the evolution of the technology for the period. Finally, a technology roadmap is drawn by linking these technology nodes in a technology layer and estimating the duration of development time. Based on technology roadmap, technology planning is conducted to identify undeveloped technology through text mining and this paper suggests characteristics of technology that needs to be developed in the future. In order to illustrate the process of the proposed approach, technology for hydrogen storage is selected in this paper.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.532-538
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• 2008

For the newly isolated $H_2$-producing chemoheterotrophic bacterium Citrobacter amalonaticus Y19, anaerobic glucose metabolism was studied in batch cultivation at varying initial glucose concentrations (3.5-9.5 g/l). The carbon-mass and energy balances were determined and utilized to analyze the carbon metabolic-pathways network. The analyses revealed (a) variable production of major metabolites ($H_2$, ethanol, acetate, lactate, $CO_2$, and cell mass) depending on initial glucose levels; (b) influence of NADH regeneration on the production of acetate, lactate, and ethanol; and (c) influence of the molar production of ATP on the production of biomass. The results reported in this paper suggest how the carbon metabolic pathway(s) should be designed for optimal Hz production, especially at high glucose concentrations, such as by blocking the carbon flux via lactate dehydrogenase from the pyruvate node.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.4
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• pp.274-278
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• 2001

Polymer membranes composed of N, N-dimethylaminoethyl methaccrylate(DMAEMA) and acrylamide(AAm)(or ethyl acrylamide(EAAm) were prepared to demonstrated the thermo-control of solute permeation. Poly DMEMA has a lower critical solution temperature(LCST) at around 50$\^{C}$ in water, With the copolymerization of DMAEMA with AAm (or EAAm) a shift in the LCST to a lowere temperature was observed, probably due to the formation of hydrogen bonds between the amide and N-N-dimethylamino groups. However, the temperature-induced phase transition of poly(DMAEMA-co-EAAm) did not show a similar trend to that of poly(DMAEMA- co-AAm) in the gel state. The hydrogen bonds in poly(DMAEMA-co-EAAm) were significantly disrupted with the formation a gel network, which led to a difference in the swilling behavior of polymer gels in response to temperature. To apply these polymers to temperature-sensitive sol-ute permeation, polymer membranes were prepared. The permeation pattern of hydrocortisone, used as the model solute, was explained based on the temperature-sensitive swelling behavior of the polymer membranes.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1859-1864
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• 2011

Two lanthanide complexes, $[Ln(NO_3)_2(H_2O)_3(L)_2](NO_3)(H_2O)$ {Ln = Eu (1), Tb (2); L = 2-(4-pyridylium)-ethanesulfonate, $(4-pyH)^+-CH_2CH_2-SO_3^-)$}, were prepared from lanthanide nitrate and 4-pyridineethanesulfonic acid in $H_2O$ under microwave-heating conditions. Complexes 1 and 2 are isostructural, and the lanthanide metal in both complexes is coordinated to nine oxygen atoms. The pyridyl nitrogen in the ligand is protonated to give a zwitter ion that possesses an $NH^+$ (pyridyl) positive end and an $SO_3^-$ negative end. All O-H and N-H hydrogen atoms participate in hydrogen bonds to generate a two-dimensional (complex 1) or a three-dimensional network (complex 2). Complex 1 exhibits an intense red emission, whereas complex 2 exhibits an intense green emission in the solid state at room temperature.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1258-1262
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• 2011

A new organogelator, L-Alanine dihydrazide derivative can self-assemble in various organic solvents and turned them into thermally reversible physical supramolecular organogels at extremely low concentrations (< 2 wt %). The gel-sol phase transition temperatures ($T_{GS}$) were determined as a function of gelator concentration and the corresponding enthalpies (${\Delta}H_g$) were extracted. Scanning electron microscopy (SEM) measurements revealed that the interspaces of fiber-like network structures were diminished with the increasing of the LMOG concentration. FT-IR spectroscopy studies revealed that hydrogen-bonding and hydrophobic interaction were the driving forces for the formation of the gels. Based on the data of XRD and molecular modeling, the possible packing modes for the formation of organogelator aggregates were proposed.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.205-205
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• 2011

The self-assembly of ${\gamma}$-phenylalanine on Au(111) at 150 K was investigated using scanning tunneling microscopy (STM). Phenylalanine can potentially form two-dimensional (2D) molecular networks through hydrogen bonding (through the carboxyl and amino groups) and ${\pi}-{\pi}$ stacking interactions (via aromatic rings). We found that ${\gamma}$-phenylalanine molecules self-assembled on Au(111) surfaces into well-ordered structures such as ring-shaped clusters (at low and intermediate coverages) and 2D molecular domains (intermediate and monolayer coverages), whereas ${\alpha}$-phenylalanine molecules formed less-ordered structure on Au(111). The self-assembly of ${\gamma}$- but not ${\alpha}$-phenylalanine may be related to the flexibility of the carboxyl and amino groups in the molecule. Moreover, as expected, the 2D molecular network of ${\gamma}$-phenylalanine on Au(111) was mediated by a combination of hydrogen bonding and ${\pi}-{\pi}$ stacking interactions.

• Korean Journal of Crystallography
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• v.11 no.2
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• pp.75-79
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• 2000

The complex [Cu(L)(H2O)2] (PDC)(1)(L=2,5,9,12-tetramethyl-1,4,8,11- tetraazacyclotetradecane;PDC=1,4-pyridinedicarboxylate) has been synthesized and characterized by X-ray crys-tallography. The compound 1 crystallizes in the triclinic space group P1, with a=7.553(1)Å, b=9.619(2)Å, c=10.692(2)Å, α=74.22(1)°, β=73.32(1)°, γ=78.70(1)°, V=710.1(2)Å3, Z=1,R1(wR2) for 2634 observed reflections of [I>2σ(I)] was 0.0854(0.2242). The compound 1 is interconnected to give a three-dimensional network through weak hydrogen-bonding interactions.

• Bulletin of the Korean Chemical Society
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• v.24 no.10
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• pp.1485-1489
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• 2003

The gelation for di-(2-ethylhexyl) phthalate (DEHP)-plasticized poly(vinyl chloride) was studied by measuring time-resolved small-angle X-ray scattering (SAXS) and a flow of the solutions in test tube. It was found that for the gelation there were three regimes. At Regime I, the solution rapidly changed to a gel, and the SAXS intensity showed a peak and the peak intensity increased, keeping the peak angle constant. Applying the SAXS intensity to the kinetic analysis of the liquid-liquid phase separation, it was revealed that the spinodal decomposition proceeded to develop a periodic length of 29.9 nanometer in size, a hydrogen-bonding-type association in polymer rich phase followed, and then it induced fast gelation rate. At Regime II, the gelation slowly occurred and the SAXS intensity was not observed, suggesting that a homogeneous gel network was formed by a hydrogen-bonding. At regime III, the solution was a homogeneous sol.

• Korean Journal of Crystallography
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• v.13 no.1
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• pp.12-16
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• 2002

The complex [Ni(L)](BDC)·4H₂O (1) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[16,4,O/sup 1.18/,O/sup 7.12/] docosane; BDC = 1,3-benzenedicarboxylate) has been synthesized and characterized by X-ray crystallography. Compound 1 crystallizes in the orthorhombic space group Pcnb, with a = 8.764(2) , b = 17.687(2) , c = 19.475(1) , V = 3018.7(8) ³, Z = 4, R₁, (wR₂) for 2148 observed reflections of [1>2σ(I) was 0.0822 (0.2236). Compound 1 is interconnected to give a three-dimensional network through weak hydrogen-bonding interactions.