Synthesis of colloidal VO₂ nanoparticles for thermochromic applications

Choi, Yongwon,Sim, Dong Min,Hur, Yoon Hyung,Han, Hyeuk Jin,Jung, Yeon Sik Elsevier 2018 Solar energy materials and solar cells Vol.176 No.-

<P><B>Abstract</B></P> <P>Vanadium dioxide (VO<SUB>2</SUB>) thin films are key materials for thermochromic smart windows and commonly have a typical phase transition (insulator to metal phase) at a transition temperature of 68°C. This research, however, found that highly crystallized VO<SUB>2</SUB> nanoparticles can be successfully coated on a glass substrate with added functionalities, such as higher luminous transmittance and transition efficiency. The transition temperature revealed that the VO<SUB>2</SUB> nanoparticles with post thermal treatment at 600°C also clearly exhibited a reduced transition temperature of 69°C in the heating curve, 59°C in the cooling curve, and a transition width of 10°C. By nanopatterning the thin films, we were able to prepare VO<SUB>2</SUB> thin films with higher luminous transmittance than that attained with non-patterned VO<SUB>2</SUB> thin films. The enhanced transition property was demonstrated using highly crystallized VO<SUB>2</SUB> nanoparticles induced by post thermal treatment, and the luminous transmittance was improved by the nanopatterns on the surface of the VO<SUB>2</SUB> thin films.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Vanadium dioxide nanoparticles are synthesized by thermolysis. </LI> <LI> The crystallinity and microstructure were improved by post thermal annealing. </LI> <LI> Transition temperatures were 69°C and 59°C in the heating and cooling curves. </LI> <LI> Nanopatterned VO<SUB>2</SUB> thin films enhanced the luminous transmittance. </LI> </UL> </P>

평생교육원 실용무용 교육서비스품질과 진로교육이 전공자의 학업지속의향, 지속적 대회참여 미치는 영향

최용원 ( Choi Yongwon ) 한국체육학회 2020 한국체육학회지 Vol.59 No.6

본 연구는 평생교육원의 실용무용 수강자를 대상으로 진로교육을 포함하는 교육서비스 개선과 전공학점 인정 확대 등을 위한 개선점을 파악하기 위한 평생교육원 실용무용 교육서비스품질과 진로교육이 전공자의 학업지속의향, 지속적 대회참여에 미치는 영향을 규명하는 목적을 두고 진행되었다. 연구대상은 수도권에 소재 평생교육원 총 13곳 수강생 대상으로 설문조사를 실시하였으며 총 552명의 자료가 분석에 사용되었다. 자료 분석은 상관분석, 회귀분석, 위계적 회귀분석을 실시하였으며, 이를 통해 다음과 같은 결론을 도출하였다. 첫째, 교육서비스품질의 신뢰성, 내용성, 가치성은 학업지속의향에 유의미한 영향을 미치는 것으로 나타났다. 둘째, 대학진로교육은 인프라 만족도, 교육과정 만족도 모두 유의미한 영향을 미치는 것으로 나타났다. 셋째, 교육서비스품질의 내용성, 가치성은 지속적 대회참여에 유의미한 영향을 미치는 것으로 나타났다. 넷째, 대학진로교육이 지속적 대회참여에 유의미한 영향을 미치지 않았다. 다섯째, 학업지속의향은 지속적 대회참여에 유의미한 영향을 미치는 것으로 나타났다. 여섯째, 교육서비스품질과 학업필요성의 관계에서 학점필요성의 조절효과는 나타나지 않았다. 일곱째, 대학진로교육과 학업지속의사의 관계에서 학점필요성에 유의미한 조절효과가 있는 것으로 나타났다. 여덟째, 교육서비스품질과 지속적 대회참여 관계에서 학점필요성의 조절효과는 나타나지 않았다. 아홉째, 대학진로교육과 지속적 대회참여의 관계에서 학점필요성은 유의미한 조절효과가 있는 것으로 나타났다. 따라서 평생교육원은 실용무용 수강자들의 특수성을 고려해 교육서비스품질을 향상시키고 진로교육 프로그램의 개발이 필요한 것으로 사료된다. This study aims to improve educational services, career education and expand major credits recognition at Continuing Education; and to find effects of majors’ academic persistence and competition participation. The subject was a survey of students in 13 Continuing Education where offers Bachelor or Associate degree, and 552 data were analyzed. Following results were drawn by correlation and hierarchical regression analysis: First, a reliability, content, and value of educational service quality affect academic persistence. Second, a career education affects infrastructure and curriculum satisfactions. Third, content and value of educational service quality affect competition participation. Fourth, career education did not affect competition participation. Fifth, academic persistence affects competition participation. Sixth, credit necessity has no moderating effect on relation between educational service quality and academic necessity. Seventh, credit necessity has moderating effect on relation between career education and academic persistence. Eighth, credit necessity has no moderating effect on relation between educational service quality and competition participation. Ninth, credit necessity has moderating effect on relation between career education and competition participation, Thus, Continuing Education should improve education services and develop career education.

Tumor Necrosis Factor (TNF) Receptor-associated Factor (TRAF)-interacting Protein (TRIP) Negatively Regulates the TRAF2 Ubiquitin-dependent Pathway by Suppressing the TRAF2-Sphingosine 1-Phosphate (S1P) Interaction

Park, Eui-Soon,Choi, Seunga,Shin, Bongjin,Yu, Jungeun,Yu, Jiyeon,Hwang, Jung-Me,Yun, Hyeongseok,Chung, Young-Ho,Choi, Jong-Soon,Choi, Yongwon,Rho, Jaerang American Society for Biochemistry and Molecular Bi 2015 The Journal of biological chemistry Vol.290 No.15

<P>The signaling pathway downstream of TNF receptor (TNFR) is involved in the induction of a wide range of cellular processes, including cell proliferation, activation, differentiation, and apoptosis. TNFR-associated factor 2 (TRAF2) is a key adaptor molecule in TNFR signaling complexes that promotes downstream signaling cascades, such as nuclear factor-kappa B (NF-kappa B) and mitogen-activated protein kinase activation. TRAF-interacting protein (TRIP) is a known cellular binding partner of TRAF2 and inhibits TNF-induced NF-kappa B activation. Recent findings that TRIP plays a multifunctional role in antiviral response, cell proliferation, apoptosis, and embryonic development have increased our interest in exploring how TRIP can affect the TNFR-signaling pathway on a molecular level. In our current study, we demonstrated that TRIP is negatively involved in the TNF-induced inflammatory response through the down-regulation of proinflammatory cytokine production. Here, we demonstrated that the TRAF2-TRIP interaction inhibits Lys(63)-linked TRAF2 ubiquitination by inhibiting TRAF2 E3 ubiquitin (Ub) ligase activity. The TRAF2-TRIP interaction inhibited the binding of sphingosine 1-phosphate, which is a cofactor of TRAF2 E3 Ub ligase, to the TRAF2 RING domain. Finally, we demonstrated that TRIP functions as a negative regulator of proinflammatory cytokine production by inhibiting TNF-induced NF-kappa B activation. These results indicate that TRIP is an important cellular regulator of the TNF-induced inflammatory response.</P>

PDMS MICRO BEAD CAGE REACTOR FOR THE DETECTION OF ALPHA FETO PROTEIN (AFP)

Yongwon Jeong,Kihwan Choi,Doo Soo Chung,Byungkyu Kim,Hyeon Cheol Kim,Kukjin Chun 대한전자공학회 2005 ITC-CSCC :International Technical Conference on Ci Vol.2005 No.4

A novel copper-chelating strategy for fluorescent proteins to image dynamic copper fluctuations on live cell surfaces

Choi, Yoon-Aa,Keem, Joo Oak,Kim, Cha Yeon,Yoon, Hye Ryeon,Heo, Won Do,Chung, Bong Hyun,Jung, Yongwon Royal Society of Chemistry 2015 Chemical Science Vol.6 No.2

<▼1><P>A strong but selective copper-binding tripeptide was employed to develop a highly sensitive and selective copper(<SMALL>II</SMALL>) protein reporter.</P></▼1><▼2><P>Copper is indispensable in most aerobic organisms although it is toxic if unregulated as illustrated in many neurodegenerative diseases. To elucidate the mechanisms underlying copper release from cells, a membrane-targeting reporter which can compete with extracellular copper-binding molecules is highly desirable. However, engineering a reporter protein to provide both high sensitivity and selectivity for copper(<SMALL>II</SMALL>) has been challenging, likely due to a lack of proper copper(<SMALL>II</SMALL>)-chelating strategies within proteins. Here, we report a new genetically encoded fluorescent copper(<SMALL>II</SMALL>) reporter by employing a copper-binding tripeptide derived from human serum albumin (HSA), which is one of the major copper-binding proteins in extracellular environments. Optimized insertion of the tripeptide into the green fluorescent protein leads to rapid fluorescence quenching (up to >85% change) upon copper-binding, while other metal ions have no effect. Furthermore, the high binding affinity of the reporter enables reliable copper detection even in the presence of competing biomolecules such as HSA and amyloid beta peptides. We also demonstrate that our reporter proteins can be used to visualize dynamic copper fluctuations on living HeLa cell surfaces.</P></▼2>

Thermodynamic and kinetic influences of NaCl on HFC-125a hydrates and their significance in gas hydrate-based desalination

Choi, Wonjung,Lee, Yohan,Mok, Junghoon,Lee, Seungmin,Lee, Ju Dong,Seo, Yongwon Elsevier 2019 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.358 No.-

<P><B>Abstract</B></P> <P>In this study, HFC-125a was selected as a hydrate-forming guest for gas hydrate-based desalination. The thermodynamic and kinetic effects of NaCl on HFC-125a hydrates were investigated with a primary focus on phase equilibria, gas uptake, dissociation enthalpy, and dissociation behavior. The equilibrium curve of HFC-125a hydrate shifted to higher pressure regions at any given temperature depending on the concentration of NaCl. The presence of NaCl also reduced the gas uptake and conversion to hydrates, because of the enrichment of NaCl in the solution during gas-hydrate formation. Even though NaCl did not affect the dissociation enthalpy of the HFC-125a hydrate, the thermograms obtained using a high-pressure micro-differential scanning calorimeter (HP μ-DSC) demonstrated that HFC-125a + NaCl hydrates started to dissociate at lower temperatures due to NaCl in unconverted solutions. Rietveld refinement of powder X-ray diffraction (PXRD) patterns indicated that the HFC-125a hydrate (sII) was transformed into Ih as it dissociated. The dissociation of HFC-125a + NaCl hydrates was retarded and completely ended at higher temperatures compared to the pure HFC-125a hydrate by the sodium chloride dihydrate (NaCl⋅2H<SUB>2</SUB>O). Overall, these results could facilitate a better understanding of HFC-125a hydrates in the presence of NaCl; further, they might also be useful in the design and operation of hydrate-based desalination plants using HFC-125a.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermodynamic and kinetic influences of NaCl on HFC-125a hydrate were investigated. </LI> <LI> NaCl enrichment in the unconverted solution resulted in a lower conversion. </LI> <LI> The presence of NaCl had little effect on the Δ<I>H</I> of HFC-125a hydrate. </LI> <LI> The hydrate dissociation was retarded due to the formation of NaCl⋅2H<SUB>2</SUB>O. </LI> </UL> </P>

Recent Progress on Polymeric Binders for Silicon Anodes in Lithium-Ion Batteries

Choi, Nam-Soon,Ha, Se-Young,Lee, Yongwon,Jang, Jun Yeong,Jeong, Myung-Hwan,Shin, Woo Cheol,Ue, Makoto The Korean Electrochemical Society 2015 Journal of electrochemical science and technology Vol.6 No.2

Advanced polymeric binders with unique functions such as improvements in the electronic conduction network, mechanical adhesion, and mechanical durability during cycling have recently gained an increasing amount of attention as a promising means of creating high-performance silicon (Si) anodes in lithium-ion batteries with high energy density levels. In this review, we describe the key challenges of Si anodes, particularly highlighting the recent progress in the area of polymeric binders for Si anodes in cells.

Accurate measurement of phase equilibria and dissociation enthalpies of HFC-134a hydrates in the presence of NaCl for potential application in desalination

Yongwon Seo,Dongyoung Lee,Yohan Lee,Wonjung Choi,Seungmin Lee 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.4

Phase equilibria, structure identification, and dissociation enthalpies of HFC-134a hydrates in the presence of NaCl are investigated for potential application in desalination. To verify the influence of NaCl on the thermodynamic hydrate stability of the HFC-134a hydrate, the three-phase (hydrate (H) - liquid water (LW) - vapor (V)) equilibria of the HFC-134a+NaCl (0, 3.5, and 8.0 wt%)+water systems are measured by both a conventional isochoric (pVT) method and a stepwise differential scanning calorimeter (DSC) method. Both pVT and DSC methods demonstrate reliable and consistent hydrate phase equilibrium points of the HFC-134a hydrates in the presence of NaCl. The HFC- 134a hydrate is identified as sII via powder X-ray diffraction. The dissociation enthalpies (ΔHd) of the HFC-134a hydrates in the presence of NaCl are also measured with a high pressure micro-differential scanning calorimeter. The salinity results in significant thermodynamic inhibition of the HFC-134a hydrates, whereas it has little effect on the dissociation enthalpy of the HFC-134a hydrates. The experimental results obtained in this study can be utilized as foundational data for the hydrate-based desalination process.

Efficient Segmentation for Left Atrium With Convolution Neural Network Based on Active Learning in Late Gadolinium Enhancement Magnetic Resonance Imaging

Cho Yongwon,Cho Hyungjoon,Shim Jaemin,Choi Jong-Il,Kim Young-Hoon,Kim Namkug,Oh Yu-Whan,Hwang Sung Ho 대한의학회 2022 Journal of Korean medical science Vol.37 No.36

Background: To propose fully automatic segmentation of left atrium using active learning with limited dataset in late gadolinium enhancement in cardiac magnetic resonance imaging (LGE-CMRI). Methods: An active learning framework was developed to segment the left atrium in cardiac LGE-CMRI. Patients (n = 98) with atrial fibrillation from the Korea University Anam Hospital were enrolled. First, 20 cases were delineated for ground truths by two experts and used for training a draft model. Second, the 20 cases from the first step and 50 new cases, corrected in a human-in-the-loop manner after predicting using the draft model, were used to train the next model; all 98 cases (70 cases from the second step and 28 new cases) were trained. An additional 20 LGE-CMRI were evaluated in each step. Results: The Dice coefficients for the three steps were 0.85 ± 0.06, 0.89 ± 0.02, and 0.90 ± 0.02, respectively. The biases (95% confidence interval) in the Bland-Altman plots of each step were 6.36% (−14.90–27.61), 6.21% (−9.62–22.03), and 2.68% (−8.57–13.93). Deep active learning-based annotation times were 218 ± 31 seconds, 36.70 ± 18 seconds, and 36.56 ± 15 seconds, respectively. Conclusion: Deep active learning reduced annotation time and enabled efficient training on limited LGE-CMRI.

Influence of Feed Gas (CO₂ + N₂) Compositions on Replacement Efficiency in sH Hydrate

Wonjung Choi(최원중),Junghoon Mok(목정훈),Yongwon Seo(서용원) 한국에너지기후변화학회 2019 한국에너지기후변화학회 학술대회 Vol.2019 No.05