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Dynamic Simulator for a PEM Fuel Cell System With a PWM DC/DC Converter
Song-Yul Choe,Jong-Woo Ahn,Jung-Gi Lee,Soo-Hyun Baek IEEE 2008 IEEE transactions on energy conversion Vol.23 No.2
<P>Polymer electrolyte membrane (PEM) fuel cells typically have low voltage, high current, terminal characteristics that cannot accommodate common electric loads like electric motors or power utility grids. Thus, a dc/dc converter is required to boost the output voltage of these power systems. Furthermore, the terminal characteristics are dependent on loads and operating conditions of the fuel cell system. The continuously changing power demand of an electric load requires dynamically replenishing the air and fuel, by properly maintaining humidity in the cell and efficiently rejecting the heat produced. These factors present important challenges for the design of reliable and durable power systems. We present new dynamic models for a fuel cell system and a pulsewidth modulation dc/dc converter with associated controls and integration. The model for the system consists of three subsystems that include an PEM fuel cell stack, an air supply, and a thermal system. Four different controllers were designed to control the air, the coolant, and the output voltage of the converter, and to optimize the power flow between the fuel cell and the output capacitor. The integrated model with its controls was tested using a real-time simulator that reduced computational time and facilitated the analysis of the interactions between loads and the fuel cell components and also allowed the optimization of a power control strategy. The responses of a static and dynamic load show that the power controls proposed can coordinate two energy sources, resulting in improved dynamics and efficiency.</P>
Song, Young Hyun,Park, Sang-Yul,Yoo, Jin Sun,Park, Won Kyu,Kim, Hyo Sun,Choi, Seung Hee,Kwon, Seok Bin,Kang, Bong Kyun,Kim, Jae Pil,Jung, Hyun Suk,Yoon, Dae Ho,Yang, Woo Seok,Seo, Young-Soo Elsevier 2018 Chemical Engineering Journal Vol.352 No.-
<P><B>Abstract</B></P> <P>Fully inorganic lead halide perovskite materials have attracted tremendous attention because of their practical applications in optoelectronic devices, such as light emitting diodes. In this work, we report the first development of highly efficient, stable and green-emitting CsPbBr<SUB>3</SUB> perovskite NCs with a PE microcapsule. The CsPbBr<SUB>3</SUB> perovskite NCs were perfectly incorporated inside the PE microcapsule with a multi-lamellar structure, which shows better luminescence characteristics such as a high PLQY and thermal stability Furthermore, our results revealed the high luminous performance with a white conversion efficacy of 62.4 lm W<SUP>−1</SUP>, EQE of 31.8%, CRI of 37.01, and CCT of 6028 K on blue emitting InGaN LED chip. We suggest that our material will be one of the next generation candidate luminescence materials for application in optoelectronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We successfully synthesized the efficient and stable green-emitting CsPbBr<SUB>3</SUB> perovskite nanocrystals. </LI> <LI> CsPbBr<SUB>3</SUB> perovskite of using the multi-lamellar microcapsule enhances the PLQY to 40%. </LI> <LI> The encapsulated perovskite NC composite material represents a next generation candidate luminescence material. </LI> </UL> </P>
Depletion of adipocyte Becn1 leads to lipodystrophy and metabolic dysregulation
Yaechan Song,Young Jin,Yul Ji,Sung Sik Choe,Yong Geun Jeon,Heeju Na,Tae Wook Nam,Hye Jeong Kim,Hahn Nahmgoong,Sung Min Kim,Jae-woo Kim,Ki Taek Nam,Je Kyung Seong,Daehee Hwang,Chan Bae Park,In Hye Lee 한국실험동물학회 2021 한국실험동물학회 학술발표대회 논문집 Vol.2021 No.7
Macroautophagy is a catabolic process that delivers damaged and unnecessary cytosolic contents to lysosomes for removal of defective subcellular organelles and proteins. Becn1 is a key regulator of autophagy, forming a complex with class III phosphatidylinositol 3-kinase (PI3K-III) to initiate autophagosome formation. Although Becn1 has been implicated in numerous diseases such as cancer, aging, and neurodegenerative disease, its function in mature adipocytes remains elusive. In this study, we implemented Adipoq-Cre to generate adipocyte-specific Becn1 KO (BaKO) mice to identify the function of autophagy in adipose tissue homeostasis. BaKO mice naturally developed severe lipodystrophy and metabolic dysregulation, which were exacerbated upon high dietary fat intake. These mice also acquired adipose tissue inflammation, hepatic steatosis, and insulin resistance which advanced to early mortality. Immortalized stromal vascular cells (imSVCs) were established in-vitro to conditionally knock-out Becn1 upon tamoxifen treatment. Ablation of Becn1 in adipocytes led to programmed cell death in a cell-autonomous manner, accompanied by elevated endoplasmic reticulum (ER) stress gene expression. Furthermore, we observed that Becn1 depletion sensitized mature adipocytes to ER stress through activation of protein kinase R-like ER kinase (PERK) – eukaryotic initiation factor 2α (eiF2α) axis. This led to excessive unfolded protein response (UPR) and accelerated cell death through notable induction of C/EBP homologous protein (CHOP) and Bax expression. Taken together, these data suggest that adipocyte-Becn1 would serve as a crucial player for adipocyte survival and adipose tissue homeostasis.
Sun Ho Song,Dong Ryul Park,Sung Yul Woo,Won Seob Song,Myong Suk Kwon,송인규 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.5
Direct preparation of dichloropropanol (DCP) from glycerol and hydrochloric acid gas was carried out in a heterogeneous gas phase reactor using H3PMo12XWXO40 (X = 0, 3, 6, 9, and 12), H4SiW12O40, and H4SiMo12O40 heteropolyacid (HPA) catalysts. Acid property of the HPA catalyst was determined by NH3-TPD measurement in order to correlate the catalytic activity with the acid property of the catalyst. Acid strength of the HPA catalyst played a key role in determining the catalytic performance in the reaction. Yield for DCP increased with increasing acid strength of the catalyst. Among the catalysts tested,H3PW12O40 with the highest acid strength showed the highest yield for DCP. 2010 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
두개강내 병소와 동반되는 급성 고혈압의 치료 : 이상적인 항고혈압 치료제의 선택을 중심으로 Focus on Selecting Ideal Antibypertensive Agents
박정율,이자규,이일옥,공명훈,송우혁,정흥섭,이기찬,이훈갑 고려대학교 의과대학 1997 고려대 의대 잡지 Vol.34 No.2
Patients with acute hypertension associated with intracranial pathology often require prompt reduction of elevated blood pressure. But the principal goal here is to ameliorate systemic hypertension while maintaining adequate cerebral perfusion pressure to provide required cerebral blood flow and thereby preventing secondary ischemic brain damage. Although many new antihypertensive agents are now available, the ideal agent along with optimal guidelines for blood pressure reduction still remain controversial in acute hypertensive patients with different types of intracranial pathologies. Object of this study was to first review briefly the cerebrovascular pathophysiology of hypertension in conjunction with management of these patients. Pertinent literature is searched, indexed, and referenced from MEDLINE for this purpose. From this information, along with clinical experiences, authors tried to provide some of basic guidelines for managing these patients in various clinical situations, focusing mainly on selecting ideal antihypertensive agents available at present time. From the present standpoint it is generally agreed that 1- or 1-adrenergic receptor antagonists provide arterial pressure reduction with little or no adverse effect on intracranial pressure within regulatory range. Although many promising calcium-channel blocking agents are now available, their use are often limited by their action to cause cerebral vasodilation and thus increased intracranial pressure. Angiotensin converting enzyme inhibitors can be used for moderate hypertension but have potential to further increase intracranial pressure in patients who already have intracranial hypertension. It has long been known that barbiturates can be adjuvant method in case of resistant or malignant hypertension with intractablly increased intracranial pressure since it decreases both the blood pressure and cerebral blood flow with reduction of oxygen metabolism. The proper management of acute hypertension in the patients with intracranial pathology should be based on sufficient understanding of the pathophysiology of hypertension and cerebral perfusion pressure. Ideal agents would be individually based on their ability to promptly and reliably ameliorate the hypertension and at the same time maintain adequate cerebral blood flow and intracranial pressure.
Kyeong Ho Song,Won Seok Oh,Jae Woo Lee,Min Wook Kim,Dae Kyun Jeong,Seong Hwan Bae,Hyun Yul Kim,Youn Joo Jung,Ki Seok Choo,Kyung Jin Nam,Ji Hyeon Joo,Mi Sook Yun,Su Bong Nam 대한성형외과학회 2021 Archives of Plastic Surgery Vol.48 No.6
Background Breast reconstruction using an extended latissimus dorsi (eLD) flap can supplement more volume than reconstruction using various local flaps after partial mastectomy, and it is a valuable surgical method since the reconstruction area is not limited. However, when performing reconstruction, the surgeon should consider latissimus dorsi (LD) volume reduction due to postoperative chemotherapy (POCTx) and postoperative radiotherapy (PORTx). To evaluate the effect of POCTx and PORTx on LD volume reduction, the effects of each therapy—both separately and jointly—need to be demonstrated. The present study quantified LD volume reduction in patients who underwent POCTx and PORTx after receiving breast-conserving surgery (BCS) with an eLD flap. Methods This study included 48 patients who received immediate breast reconstruction using an eLD flap from January 2013 to March 2017, had chest computed tomography (CT) 7–10 days after surgery and 10–14 months after radiotherapy completion, and were observed for more than 3 years postoperatively. One surgeon performed the breast reconstruction procedures, and measurements of breast volume were obtained from axial CT views, using a picture archiving and communication system. A P-value <0.05 was the threshold for statistical significance. Results The average volume reduction of LD at 10–14 months after completing POCTx and PORTx was 64.5% (range, 42.8%–81.4%) in comparison to the volume measured 7–10 days after surgery. This change was statistically significant (P<0.05). Conclusions Based on the findings of this study, when harvesting an eLD flap, surgeons should anticipate an average LD volume reduction of 64.5% if chemotherapy and radiotherapy are scheduled after BCS with an eLD flap.