• Mass Spectrometry Letters
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• v.12 no.4
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• pp.146-151
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• 2021

In this study, the hydrogen/deuterium (HDX) exchange mechanism of active hydrogen, nitrogen, and sulfur-containing polycyclic aromatic hydrocarbon (PAH) dissolved in toluene and deuterated methanol by atmospheric pressure photoionization (APPI) is investigated. The comparison of the data obtained using APPI suggests that aniline and benzene-1,2-dithiol contain two exchanging hydrogens. The APPI HDX that best explains the experimental findings was investigated with the use of quantum mechanical calculations. The HDX mechanism is composed of a two-step reaction: in the first step, analyte radical ion gets deuterated, and in the second step, the hydrogen transfer occurs from deuterated analyte to de-deuterated methanol to complete the exchange reaction. The suggested mechanism provides fundamentals for the HDX technique that is important for structural identification with mass spectrometry. This paper is dedicated to Professor Seung Koo Shin for his outstanding contributions in chemistry and mass spectrometry.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.749-752
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• 2014

New software was developed for the assignment of elemental formulae based on high-resolution mass spectra and subsequent hydrogen/deuterium exchange data. Entire peaks in high-resolution mass spectra were grouped by their Kendrick mass defect values, and the weighted RMS deviations between theoretical and experimental values were used to determine elemental formulae. After this initial assignment, formulae containing deuterium atoms were sorted in order to interpret hydrogen/deuterium exchange spectra. The software was successfully applied to hydrogen/deuterium exchange spectra of resins and aromatic fractions from heavy crude oil.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.4
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• pp.288-294
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• 2013

This gas analysis data come from the hydrogen which is produced by proton exchange membrane. Main impurities of hydrogen are methane, oxygen, nitrogen, carbon monoxide, and carbon dioxide. The concentration of impurities is ranged between 0.0191 to $315{\mu}mol/mol$ for each impurity. Methane contamination is believed from the electrode reaction between carbon doped electrode and produced hydrogen. Nitrogen contamination should take place the sampling process error, not from PEM hydrogen Production system.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1643-1644
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• 2007

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.563-566
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• 2013

We investigated the variation of anion exchange membrane of hydrogen generator of alkaline electrolysis. We detected the variation of elements and change of anion exchange membrane using EDS and FE-SEM. We detected two different sites of membrane because of different structure of membrane. $Sp_1$ shows that the distribution ratio of C, O, Al is 98% very higher than $Sp_2$ of 78%. Especially, the main elements of STS316 which is P, S, Fe, Ni were more detected at $Sp_2$ than $Sp_1$. We think that this result depends on the structure of membrane. This also affect the resistance, lifetime of membrane and decrease the efficiency of hydrogen production. We hope that this article is a foundation of developing of hydrogen production technology.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.2
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• pp.184-190
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• 2011

The membrane properties (membrane resistance and ion exchange capacity) of the five types of commercial anion exchange membrane, i.e. IOMAC, AHT, APS, AHA, AFN, were evaluated for the application in the alkaline electrolysis. The membrane resistance decreased in the order; in 1M KOH: AHT>IOMAC>AHA>AFN>APS; in 1M NaOH: AHT>IOMAC>AHA>APS>AFN. The ion exchange capacity decreased in the order: AFN>APS>AHT>AHA>IOMAC. The membrane life was determined from the change of membrane resistance in 1M KOH and NaOH with an increase of soaking time in 20 wt% KOH and 30 wt% NaOH solution. AHA membrane had a good membrane life in 20 wt% NaOH with its unchanged membrane resistance. And, AFN and AHA membrane had a good membrane life in 30 wt% NaOH with its unchanged membrane resistance.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1401-1406
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• 2013

This study tested the feasibility of observing H/D exchange of intact protein by top-down electron capture dissociation (ECD) mass spectrometry for the investigation of protein structure. Ubiquitin is selected as a model system. Local structural information was obtained from the deuteration levels of c and $z^{\cdot}$ ions generated from ECD. Our results showed that ${\alpha}$-helix region has the lowest deuteration level and the C-terminal fraction containing a highly mobile tail has the highest deuteration level, which correlates well with previous X-Ray and HDX/NMR analyses. We studied site-specific H/D exchange kinetics by monitoring H/D exchange rate of several structural motives of ubiquitin. Two hydrogen bonded ${\beta}$-strands showed similar HDX rates. However, the outer ${\beta}$-strand always has higher deuteration level than the inner ${\beta}$-strand. The HDX rate of the turn structure (residues 8-11) is lower than that of ${\beta}$-strands (residues 1-7 and residues 12-17) it connects. Although isotopic distribution gets broader after H/D exchange which results in a limited number of backbone cleavage sites detected, our results demonstrate that this method can provide valuable detailed structural information of proteins. This approach should also be suitable for the structural investigation of other unknown proteins, protein conformational changes, as well as protein-protein interactions and dynamics.

• Membrane Journal
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• v.32 no.5
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• pp.283-291
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• 2022

Hydrogen energy has received much attention as a solution to the supply of renewable energy and to respond to climate change. Hydrogen is the most suitable candidate of storing unused electric power in a large-capacity long cycle. Among the technologies for producing hydrogen, water electrolysis is known as an eco-friendly hydrogen production technology that produces hydrogen without carbon dioxide generation by water splitting reaction. Membranes in water electrolysis system physically separate the anode and the cathode, but also prevent mixing of generated hydrogen and oxygen gases and facilitate ion transfer to complete circuit. In particular, the key to next-generation anion exchange membrane that can compensate for the shortcomings of conventional water electrolysis technologies is to develop high performance anion exchange membrane. Many studies are conducted to have high ion conductivity and excellent durability in an alkaline environment simultaneously, and various materials are being searched. In this review, we will discuss the research trends and points to move forward by looking at the research on anion exchange membranes based on commercial polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) block copolymers.

• Journal of the Korean institute of surface engineering
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• v.56 no.6
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• pp.412-419
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• 2023

Anion exchange membrane electrolysis is considered a promising next-generation hydrogen production technology that can produce low-cost, clean hydrogen. However, anion exchange membrane electrolysis technology is in its early stages of development and requires intensive research on electrodes, which are a key component of the catalyst-system interface. In this study, we optimized the pressure conditions of the hot-pressing process to manufacture cobalt oxide electrodes for the development of a high uniformity and high adhesion electrode production process for the oxygen evolution reaction. As the pressure increased, the reduction of pores within the electrode and increased densification of catalytic particles led to the formation of a uniform electrode surface. The cobalt oxide electrode optimized for pressure conditions exhibited improved catalytic activity and durability. The optimized electrode was used as the anode in an AEMWE single cell, exhibiting a current density of 1.53 A cm^-2 at a cell voltage of 1.85 V. In a durability test conducted for 100 h at a constant current density of 500 mA cm^-2, it demonstrated excellent durability with a low degradation rate of 15.9 mV kh^-1, maintaining 99% of its initial performance.

• Journal of the Korean Magnetic Resonance Society
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• v.18 no.2
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• pp.52-57
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• 2014

The TCP domain is a DNA-binding domain present in plant transcription factors and plays important roles in various biological functions. The hydrogen exchange rate constants of the imino protons were determined for the three DNA duplexes containing the DNA-binding sites for the TCP11, TCP15, and TCP20 transcription factors using NMR spectroscopy. The M11 duplex displays unique hydrogen exchange property of the five base pairs in the first binding site (5'-GTGGG-3'). However, the M15 and M20 duplexes lead to clear changes in thermal stabilities of these five base pairs. The unique dynamic features of the five base pairs in the first binding site might play crucial roles in the sequence-specific DNA binding of the class I TCP transcription factors.