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Kyungmin Choi,Miyeon Jung,Daegon Cho 한국경영과학회 2017 한국경영과학회 학술대회논문집 Vol.2017 No.10
Utilities and regulators are currently adopting an enabling technology of smart metering in order to effectively collect and manage high quality energy consumption data. This study descriptively identifies groups of energy consumers according to their psychological factors related to energy conservation and analyze them in terms of intra-day electricity usage curves. Collaborating with the largest electricity smart metering company in Korea, we conduct a survey on demographic information and the psychological factors to the smart meter users and collect their electricity usage in 15-minute granularity from January 2016 to July 2017 by their smart meters, and our final sample consists of 347 households. The findings will help utilities and regulators to provide more pragmatic feedback to their consumers.
A Literature Survey on the Sensor Technologies for Context Awareness
Kyungmin Choi,Sung H. Han,Heekyung Moon,Joohwan Park,Hyun K. Kim 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5
Diverse sensor technologies have been embedded in mobile devices, such as smartphones, tablet PCs, and wearable devices, for context-aware applications. This study aims to survey the current status of sensor technologies. To achieve this goal, we collected 417 relevant documents, such as journal articles, proceedings, news items, and patents published since 2011. We then identified the contexts in which sensor technologies are applied, and classified the technologies based on the identified contexts. As a result, 424 sensor technologies were grouped into three categories (by information type that the sensor technologies recognize: user information, device information, and environment information). The results of this study provide an overview of sensor technologies for context awareness.
A Literature Survey on the Sensor Technologies for Context Awareness
( Kyungmin Choi ),( Sung H. Han ),( Heekyung Moon ),( Joohwan Park ),( Hyun K. Kim ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-
Diverse sensor technologies have been embedded in mobile devices, such as smartphones, tablet PCs, and wearable devices, for context-aware applications. This study aims to survey the current status of sensor technologies. To achieve this goal, we collected 417 relevant documents, such as journal articles, proceedings, news items, and patents published since 2011. We then identified the contexts in which sensor technologies are applied, and classified the technologies based on the identified contexts. As a result, 424 sensor technologies were grouped into three categories (by information type that the sensor technologies recognize: user information, device information, and environment information). The results of this study provide an overview of sensor technologies for context awareness
Min, Kyungmin,Choi, Woosung,Choi, Minkee WILEY-VCH 2017 CHEM SUS CHEM Vol.10 No.11
<P>Poly(ethyleneimine) (PEI)/silica has been widely studied as a solid adsorbent for post-combustion CO2 capture. In this work, a highly macroporous silica (MacS), synthesized by secondary sintering of fumed silica, is compared with various mesoporous silicas with different pore structures as a support for PEI. The silicas with large pore diameter and volume enabled high CO2 adsorption kinetics and capacity, because pore occlusion by the supported PEI was minimized. The steam stability of the silica structures increased with the silica wall thickness owing to suppressed framework ripening. The silicas with low steam stability showed rapid leaching of PEI, which indicated that the PEI squeezed out of the collapsed silica pores leached more readily. Consequently, MacS that had an extra-large pore volume (1.80 cm(3)g(-1)) and pore diameter (56.0 nm), and a thick wall (> 10 nm), showed the most promising CO2 adsorption kinetics and capacity as well as steam stability.</P>
Rational Design of CO₂ Adsorbents for Post-Combustion CO₂ Capture
Minkee Choi,Woosung Choi,Kyungmin Min 한국에너지기후변화학회 2017 한국에너지기후변화학회 학술대회 Vol.2017 No.5
Amine-functionalized porous materials have been extensively investigated as promising approach for post-combustion CO₂ capture due to their chemisorption of low-concentration CO₂ (ca. 15%) from a flue gas. However, earlier studies mainly focused on the improvement of CO₂ uptake capacities of adsorbents, and did not demonstrate practical adsorbent regeneration processes and long-term stabilities. Here we design a cost-effective and scalable synthesis of modified-polyethyleneimine/silica composite adsorbent that can simultaneously show a large CO₂ working capacity as well as outstanding stability in a practically meaningful temperature swing adsorption (TSA) condition (adsorbent regeneration under 100% CO₂ at 120 ℃) even without the intensive use of steam. Most importantly, it is first reported that controlled modification of polyethyleneimine (PEI) with epoxide-derivatives markedly reduces the heat of CO₂ adsorption and facilitates CO₂ desorption (>99%) compared to unmodified PEI (76%) during the adsorbent regeneration. The modification also assures long-term adsorbent stability over repeated TSA cycles due to remarkable suppression of CO₂-induced urea formation and oxidative amine degradations.
Min, Kyungmin,Choi, Chang Hyuck,Kim, Myoung Yeob,Choi, Minkee American Chemical Society 2015 Langmuir Vol.31 No.1
<P>A template-free synthesis method for mesoporous and macro-/mesoporous hierarchically porous silicates with remarkable structural tunability and complexity is presented. SiO<SUB>2</SUB> nanocolloids having diameters of 3.0–29 nm were prepared as a primary building block by using extended Stöber synthesis, and they were subsequently assembled by an aerosol-assisted drying. The silica pore structure can be rationally controlled depending on the initial diameter of SiO<SUB>2</SUB> colloids and the aerosol-assembly temperature that determines the packing density of SiO<SUB>2</SUB> colloids (i.e., amounts of packing defects) in the resultant materials. The present method could produce mesoporous silica spheres with remarkable pore-structural tunability (291 < BET surface area <807 m<SUP>2</SUP> g<SUP>–1</SUP>, 0.42 < pore volume <0.92 cm<SUP>3</SUP> g<SUP>–1</SUP>, 3.1 < pore size <26 nm). Hierarchically porous materials can also be synthesized by the evaporation-induced phase separation of solvent medium during the aerosol-assisted assembly of SiO<SUB>2</SUB> colloids. By adding aluminum and Pt precursors into the SiO<SUB>2</SUB> colloid suspensions before the aerosol-assisted assembly, mesoporous aluminosilicates supporting uniform Pt nanoclusters (∼2 nm) can also be synthesized. This indicates that the synthesis strategy can be used for the direct synthesis of functional silicate materials.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2015/langd5.2015.31.issue-1/la504098b/production/images/medium/la-2014-04098b_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la504098b'>ACS Electronic Supporting Info</A></P>
Min, Kyungmin,Choi, Woosung,Kim, Chaehoon,Choi, Minkee American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.28
<P>Substantial efforts have been made to increase the CO<SUB>2</SUB> working capacity of amine adsorbents for an efficient CO<SUB>2</SUB> capture. However, the more important metric for assessing adsorbents is the regeneration heat required for capturing a fixed amount of CO<SUB>2</SUB>. In this work, we synthesized polyethyleneimine (PEI)/SiO<SUB>2</SUB> adsorbents functionalized with various epoxides. This provided adsorbents with six different amine structures showing various CO<SUB>2</SUB>/H<SUB>2</SUB>O adsorption properties. Our studies revealed that the CO<SUB>2</SUB> working capacity was not a decisive factor in determining the regeneration heat required for CO<SUB>2</SUB> capture. This is because the benefit of large CO<SUB>2</SUB> working capacity was canceled out by the difficulty of CO<SUB>2</SUB> desorption. Instead, the suppression of H<SUB>2</SUB>O co-adsorption was critical for reducing the regeneration heat because substantial latent heat is required for H<SUB>2</SUB>O desorption. Consequently, the PEI/SiO<SUB>2</SUB> functionalized with 1,2-epoxybutane required a much lower regeneration heat (2.66 GJ tCO<SUB>2</SUB><SUP>-1</SUP>) than the conventional PEI/SiO<SUB>2</SUB> (4.03 GJ tCO<SUB>2</SUB><SUP>-1</SUP>) because of suppressed H<SUB>2</SUB>O co-adsorption as well as moderately high CO<SUB>2</SUB> working capacity.</P> [FIG OMISSION]</BR>