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Kwon, Minchul,Youn, Yeobum,Seo, Yongwon,Lee, Jong-Won,Lee, Jaehyoung,Lee, Joo Yong,Kim, Se-Joon,Lee, Huen American Chemical Society 2013 Energy & fuels Vol.27 No.9
<P>Investigations on the intrinsic properties of gas hydrates with multiple guests are essential to scientific and technological fields. In particular, even though evaluating and designing a hydrate phase process require isothermal phase equilibria, it is difficult to obtain extensive data with various components and compositions in a short period of time due to the static-analytic method. The present study introduces a new experimental determination on hydrate phase equilibria using continuous dissociation induced by extremely slow vapor volume expansion at a constant temperature. When a syringe pump is automatically operated at the microliter level during the dissociation process, the endothermic dissociation can be traced from the temperature readings. The validity and stability of the proposed technique were evaluated using pure CH<SUB>4</SUB> hydrates, and repeated measurements of three-phase (L<SUB>W</SUB>–H–V) equilibrium conditions are used to optimize the volumetric expansion rates. Then, an experimental approach is applied to incipient CH<SUB>4</SUB> + C<SUB>2</SUB>H<SUB>6</SUB> hydrates and identifies the structural transition behavior. This method is thought to provide extensive data and further improvements in terms of hydrate phase equilibria with multiple gas components.</P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ef401072s'>ACS Electronic Supporting Info</A></P>
Temperature-Dependent Structural Transitions in Methane–Ethane Mixed Gas Hydrates
Kwon, Minchul,Lee, Jong-Won,Lee, Huen American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.49
<P>A thermodynamic interpretation of the interconversion between structures I and II occurring in methane (CH<SUB>4</SUB>) + ethane (C<SUB>2</SUB>H<SUB>6</SUB>) mixed gas hydrates is of great importance from both fundamental and applied perspectives. The present study experimentally confirms the predicted temperature dependence of structural changes in the lower transition region (72–74 mol % of CH<SUB>4</SUB> balanced with C<SUB>2</SUB>H<SUB>6</SUB>) of the CH<SUB>4</SUB> + C<SUB>2</SUB>H<SUB>6</SUB> + H<SUB>2</SUB>O system. The measurements of phase equilibria and Raman spectra, at the macroscopic and microscopic levels, respectively, reveal the phase transition point at which the structural rearrangements occur. The isothermal data reported here clearly demonstrate significant changes of transition behavior from sII inhibition to sII promotion in accordance with increased equilibrium temperatures. This solid–solid transition trend may be dictated by the peculiar structural feature of the CH<SUB>4</SUB> + C<SUB>2</SUB>H<SUB>6</SUB> mixed gas hydrates on the basis of the comprehensive experimental and theoretical data published previously. The predominance of CH<SUB>4</SUB> over C<SUB>2</SUB>H<SUB>6</SUB> in cage occupancy may lead to a change in guest molecules playing a dominant role in determining the preferential hydrate structure.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-49/jp5102219/production/images/medium/jp-2014-102219_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5102219'>ACS Electronic Supporting Info</A></P>
Lattice Contraction Behavior Occurring in Ionic Clathrate Hydrate
권민철(Kwon, Minchul),차민준(Cha, Minjun),신규철(Shin, Kyuchul),이흔(Lee, Huen) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05
Unlike non-ionic clathrate hydrates stably formed by van der Waals interaction between a guest molecule and a surrounding host framework, ionic clathrate hydrates are stabilized by ionic interaction between an ionic guest molecule and the host water-framework. Here, we firstly described the stable entrapment of the superoxide ions in {gamma}-irradiated Me₄NOH+O₂ hydrate. Owing to peculiar direct guest-guest ionic interaction, the lattice structure of {gamma}-irradiated Me₄NOH+O₂ hydrate shows significant change of lattice contraction behavior even at relatively high temperature(120K). Particularly, we note that ionic-induced dimensional change is much greater than thermal-induced change. Such findings are expected to provide useful information for a better understanding of unrevealed nature of clathrate hydrate fields.
Introduction of DPLR DFCO(Deceleration Fuel Cut Off) Pumping Loss Reduction
Minchul Park,Ohcheol Kwon,Seungheon Yoo,Youngsoo Jeong 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
Hybrid technology increased fuel economy in many ways. Motor produced torque enables engine stop at vehicle stop or runs engine in the optimized modes and Regenerated power by motor in a vehicle deceleration save energy to the RESS. Those are typical way to save fuel in a Hybrid vehicle. GM developed another way to save energy in a Hybrid vehicle by reducing engine pumping loss while in deceleration fuel cut off. On conventional powertrain systems, the pumping losses cannot be substantially reduced because it would add to response delays when the driver tips in due to the need to pump down the manifold pressure before the fuel can be turned on. However, on hybrid powertrain systems, the electric motor can be used to provide the propulsion that the driver needs until the manifold pressure is pumped down. It is called DFCO Pumping Loss Reduction. We will introduce this new method in this paper and show how much engine pumping loss reduced and how much fuel economy increased with it.
정민철,정혜성,김성민,이정훈,박권필,안호근 한국공업화학회 2005 응용화학 Vol.9 No.1
We have been used for the Pt catalyst of cathode electrode in fuel cell. Weak point of Pt electrode are easily deactivated by the CO poisoning which are producing in reaction at electrode. Recent, researchers have developed cathode electrode to avoid the CO poisoning in electrode using the Pt-alloy or another novel metal. We now report Au-carbene complexes as an Au-electrode precursor derived from the reaction of the carbene with the ClAu(PPh₃) complex in THF/MeOH.
Electric double-layer capacitor based on an ionic clathrate hydrate.
Lee, Wonhee,Kwon, Minchul,Park, Seongmin,Lim, Dongwook,Cha, Jong-Ho,Lee, Huen Wiley-VCH 2013 Chemistry, an Asian journal Vol.8 No.7
<P>Herein, we suggest a new approach to an electric double-layer capacitor (EDLC) that is based on a proton-conducting ionic clathrate hydrate (ICH). The ice-like structures of clathrate hydrates, which are comprised of host water molecules and guest ions, make them suitable for applications in EDLC electrolytes, owing to their high proton conductivities and thermal stabilities. The carbon materials in the ICH Me4NOH?5?H2O show a high specific capacitance, reversible charge-discharge behavior, and a long cycle life. The ionic-hydrate complex provides the following advantages in comparison with conventional aqueous and polymer electrolytes: 1)?The ICH does not cause leakage problems under normal EDLC operating conditions. 2)?The hydrate material can be utilized itself, without requiring any pre-treatments or activation for proton conduction, thus shortening the preparation procedure of the EDLC. 3)?The crystallization of the ICH makes it possible to tailor practical EDLC dimensions because of its fluidity as a liquid hydrate. 4)?The hydrate solid electrolyte exhibits more-favorable electrochemical stability than aqueous and polymer electrolytes. Therefore, ICH materials are expected to find practical applications in versatile energy devices that incorporate electrochemical systems.</P>
A Study on Radioactive Waste Level of the Calandria and Concrete Structures for Wolsong Unit 1
Hyunmin Kim,Minchul Kim,Kunman Kwon 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
Wolsong unit 1 (W1), which is a CANDU-6 type PHWRs that had been operated for 30 years since 1983, was shutdown in 2019. In this study, the radioactive waste levels of calandria and concrete structures were calculated to establish a decommissioning plan for W1. The specific systems within the scope of this study were grouped into 6 major categories as follows: Calandria, End Shield, Fuel Channel Assembly, Reactivity Control Device, End Shield Support, Vault. The main operating history of W1 is that the re-tubing project was performed. These characteristics and operation history were reflected in the evaluation. The neutron flux and energy spectrum of each structure were calculated by using MCNP code, and ORIGEN code is implemented to the calculation of radioactivity for each nuclide using the results from MCNP and the material information of the structure. As for the impurity information, ASTM B350, B351, B353 standard was used for zircaloy alloy. For other alloy, impurity information provided by NUREG/CR-3474 was applied. Since W1 is expected to be decommissioned immediately, the waste level was evaluated under cooling conditions for 5 years after permanent shutdown. Through the level evaluation of each component obtained as a result of the study, it can be used as basic data for the radioactive waste management of the decommissioning plan.