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A Surfactant-based Method for Carbon Coating of LiNi0.8Co0.15Al0.05O2 Cathode in Li Ion Batteries
Youngmin Chung,Seong-Hyeon Ryu,Jeong-Hun Ju,Yu-Rim Bak,황문진,Ki-Won Kim,조권구,Kwang-Sun Ryu 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.8
A LiNi0.8Co0.15Al0.05O2 (LNCAO/C) active material composite cathode was coated with carbon. The conductive carbon coating was obtained by addition of surfactant during synthesis. The addition of surfactant led to the formation of an amorphous carbon coating layer on the pristine LNCAO surface. The layer of carbon coating was clearly detected by FE-TEM analysis. In electrochemical performance, although the LNCAO/C showed similar capacity at low C-rate conditions, the rate capability was improved by the form of the carbon coating at high current discharge state. After 40cycles of charge-discharge processes, the capacity retention of LNCAO/C was better than that of LNCAO. The carbon coating is effectively protected the surface structure of the pristine LNCAO during Li insertion-extraction.
Chung, Jong Won,You, Youngmin,Huh, Hyun Sue,An, Byeong-Kwan,Yoon, Seong-Jun,Kim, Se Hun,Lee, Soon W.,Park, Soo Young American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.23
<P>We have designed and synthesized asymmetric cyano-stilbene derivatives containing trifluoromethyl (-CF(3)) substituents with the aim of producing tightly packed pi-dimer systems that as crystals exhibit reversible [2 + 2] cycloaddition with characteristic fluorescence modulation. (Z)-3-(3',5'-Bis(trifluoromethyl)biphenyl-4-yl)-2-(4'-(trifluoromethyl)biphenyl-4-yl)acrylonitrile (CN(L)-TrFMBE) and its derivatives were found to form antiparallel pi-dimer stacks in crystals due to their specific intermolecular interactions, including C-F...H and C-F...pi interactions. The CN(L)-TrFMBE pi-dimer crystals (and powder) are not at all fluorescent initially but switch to a highly fluorescent state (Phi(PL) = 24%) when an external shear-strain and/or prolonged UV (365 nm) irradiation is applied. Our experimental and theoretical investigations show that the fluorescence modulation in this particular system is due to the external and/or internal (in the case of UV irradiation) shear-induced lateral displacement of the pi-dimer molecular pair, which effectively turns the fluorescence emission on at the cost of frustrated [2 + 2] cycloaddition. Further, the fluorescence 'off' state can be restored by thermal annealing, which regenerates the tightly packed pi-dimer by reverse displacement together with the thermal dissociation of the [2 + 2] cycloaddition product. This system provides a very rare example of high-contrast reversible fluorescence switching that is driven by a change in the molecular packing mode in the solid state, which enables piezochromic and photochromic responses.</P>
Identity and Access Management using OSGi Service Platform in Cloud Computing
Youngmin Jung,Mokdong Chung 한국멀티미디어학회 2010 한국멀티미디어학회 국제학술대회 Vol.2010 No.-
??In this paper, we propose an identity and access management system using OSGi service platform in cloud computing environment. Whenever we use diverse services of cloud computing environment, we should provide convenience of authentication using single sign on. We suggest an efficient access control technique using RBAC and solution of privacy protection. And we also suggest solution of seamless cloud computing services at any time including fetches and updates. The solution will be designed and implemented using OSGi service platform. The proposed model is expected to be able to efficiently and securely manage identity and access.
Chung Yuseong,Rahmat Endang,Nam Hyeon Hwa,Lee Ayeong,Park Jun Hong,Moon Byeong Cheol,Kang Youngmin 한국응용생명화학회 2023 Applied Biological Chemistry (Appl Biol Chem) Vol.66 No.-
Rehmannia glutinosa (Gaertn.) DC., belonging to the family Scrophulariaceae, is an important medicinal herb cultivated in East Asia. Traditionally, R. glutinosa is steam processed to increase its efficacy in treating various ailments such as diabetes, hematinic deficiencies and adrenal disorder. However, standardization of processed R. glutinosa is highly needed to increase its quality to fulfill global market demand that is safe and possess high level of efficacy. Therefore, this study aimed to optimize the R. glutinosa steam processing methods by evaluating some key parameters such as steaming temperature, number of steaming times, steaming duration, and additive supplementation. R. glutinosa samples were steam processed at different temperatures (100 °C, 110 °C, and 120 °C), various steaming times (1 to 5 times), several steaming duration (1 to 4 h), and additives supplementation (rice wine, 5% EtOH, 10% EtOH, 20% EtOH, 30% EtOH, and 40% EtOH). As the result, 2 h, 3 replications, and supplementation with 20% EtOH at 120 °C were identified as the optimal conditions for R. glutinosa steam processing. Optimized processed R. glutinosa (SPRR 20%EtOH) resulted in significantly higher content of 5-HMF (7648.60 ± 150.08 µg/g) and iso-verbacoside (203.80 ± 10.72 µg/g) compared with unprocessed R. glutinosa (UPR). Compared to those of other samples, SPRR 20% EtOH samples had higher total flavonoid (55.36 ± 1.68 mg/g) and phenolic (69.24 ± 4.56 mg/g) contents and stronger DPPH antioxidant activity (56%). Furthermore, SPRR 20% EtOH had excellent anti-inflammatory activity, as evidenced by the suppression of inducible nitric oxide synthase (iNOS) caused by activation of nuclear factor-κB (NF-κB) through p-p65 pathway in LPS-stimulated RAW 264.7 cells. These findings will provide a basis towards industrialization of R. glutinosa processing technology that will be very helpful for oriental medication field.
Antibiotics-Associated Hemorrhagic Colitis Caused by Klebsiella oxytoca: Two Case Reports
Youngmin Youn,Sang Won Lee,Hyun-Hae Cho,Sanghui Park,Hae-Sun Chung,Jeong Wan Seo 대한소아소화기영양학회 2018 Pediatric gastroenterology, hepatology & nutrition Vol.21 No.2
Nowadays, Klebsiella oxytoca is described as a causative organism for antibiotic-associated hemorrhagic colitis (AAHC). Here we report two cases of pediatric AAHC, from which K. oxytoca was cultured after starting amox-icillin-clavulanate or amoxicillin treatment. The patients developed severe abdominal pain and a large amount of bloody diarrhea. K. oxytoca was obtained in intestinal fluid culture of a boy through the colonoscopy. On the other hand, colonic tissue culture and intestinal fluid culture were negative of the other patient. K. oxytoca was detected in stool culture when he was admitted. These cases showed characteristic endoscopic findings of segmental hemor-rhagic colitis, and both boys recovered spontaneously within 2-3 days after they stopped taking the antibiotics. Therefore, in children who develop relatively large amount of bloody diarrhea after antibiotic treatment, we should consider AAHC caused by K. oxytoca.
( Youngmin Yoon ),( Hyumwoo Kim ),( Sunae Han ),( Hyungnam Kim ),( Donghyun Kim ),( Ran Hong ),( Hyunlee Kim ),( Jonghoon Chung ),( Byungchul Shin ) 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1
Acute tubular necrosis (ATN) is a syndrome of intrinsic renal injury secondary to ischemic or toxic causes without parenchymal damages and usually non-oliguira. A 20- year old man presented with acute anuric renal failure preceded by 2 days of watery diarrhea. He had been anuria for 36hr with intravenous fiuid therapy. Oliguria persisted for 10 days and he required hemodialysis support for 6 days before renal recovery. He denied the use of any regular medication and any intravenous drug use. Renal biopsy revealed severe ATN. Histopathologic findings were marked desquamation of proximal tubular epithelial cells with intact distal tubules and normal glomeruli. We report an unusual case of ATN with anuria and clinically severe features.