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Thermal performance analysis of borehole size effect on geothermal heat exchanger

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Journal of Central South University 2012年第12期19卷 3524-3529页

作者： CHOI hoon-ki YOO Geun-jong LIM Kyung-bin lee Sang-hoon lee Chang-hee Department of Mechanical Design and Manufacturing Engineering Changwon National UniversityChangwon 641-773Korea Department of Mechanical Design Engineering Hanbat National UniversityDaejon 305-719Korea Department of Energy Engineering Jeonju UniversityJeonju 560-759Korea STX Institute of Technology Changwon 642-845Korea

Thermal performance was the most important factor in the development of borehole heat exchanger utilizing geothermal energy. The thermal performance was affected by many different design parameters, such as configuration type and borehole size of geothermal heat exchanger. These eventually determined the operation and cost efficiency of the geothermal heat exchanger system. The main purpose of this work was to assess the thermal performance of geother^nal heat exchanger with variation of borehole sizes and numbers of U-tubes inside a borehole. For this, a thermal response test rig was established with line-source theory. The thermal response test was performed with in-line variable input heat source. Effective thermal conductivity and thermal resistance were obtained from the measured data. From the measurement, the effective thermal conductivity is found to have similar values for two- pair type （4 U-tubes） and three-pair type （6 U-tubes） borehole heat exchanger systems indicating similar heat transfer ability. Meanwhile, the thermal resistance shows lower value for the three-pair type compared to the two-pair type. Measured data based resistance have lower value compared to computed result from design programs. Overall comparison finds better thermal performance for the three-pair type, however, fluctuating temperature variation indicates complex flow behavior inside the borehole and requires further study on flow characteristics.

关键词： large size borehole heat exchanger thermal response test effective thermal conductivity thermal resistance borehole

Characteristic analysis of bleeding effect on standing column well (SCW) type geothermal heat exchanger

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Journal of Central South University 2012年第11期19卷 3202-3207页

作者： CHOI hoon-ki YOO Geun-jong LIM Kyung-bin lee Sang-hoon lee Chang-hee Department of Mechanical Design/Manufacturing Engineering Changwon National UniversityChangwon 641-773Korea Department of Mechanical Design Engineering Hanbat National UniversityDaejon 305-719Korea Department of Energy Engineering Jeonju UniversityJeonju 560-759Korea STX Institute of Technology Gyeongnam 642-845Korea

Thermal performance is the most important factor in the development of a borehole heat exchanger utilizing geothermal *** thermal performance is affected by many different design parameters and different operating conditions such as *** eventually determines the operation and cost efficiency of the borehole heat exchanger *** thermal performance of an open standing column well (SCW) type geothermal heat exchanger was assessed under the influence of *** this,a thermal response test rig was established with line-source *** test rig also had a bleeding function by releasing fluid while taking additional underground water through the heat *** thermal response test was performed with an additional constant input heat *** thermal conductivity and thermal resistance were obtained from the measured *** the measurement,the effective thermal conductivity is found to have 1.47 times higher value when bleeding is *** thermal resistance also increases by 1.58 times compared to a non-bleeding *** trend indicates enhanced heat transfer in the SCW type heat exchanger with a bleeding ***,therefore,could be an effective method of achieving a high heat transfer rate in the SCW type heat exchanger with sufficient underground water supply.

关键词： standing column well type thermal response test effective thermal conductivity thermal resistance bleeding effect

Clinical course of ulcerative colitis patients who develop acute pancreatitis

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World Journal of Gastroenterology 2017年第19期23卷 3505-3512页

作者： Jong Wook Kim Sung Wook Hwang Sang Hyoung Park Tae Jun Song myung-Hwan Kim Ho-Su lee Byong Duk Ye Dong-hoon Yang Kyung-Jo Kim Jeong-Sik Byeon Seung-Jae myung Suk-Kyun Yang Department of Internal Medicine Inje University Ilsan Paik Hospital Department of Gastroenterology University of Ulsan College of MedicineAsan Medical Center Department of Biochemistry and Molecular Biology University of Ulsan College of Medicine

To investigate the clinical course of ulcerative colitis (UC) patients who develop acute *** analyzed 3307 UC patients from the inflammatory bowel disease registry at Asan Medical Center from June 1989 to May 2015. The clinical course of UC patients who developed acute pancreatitis was compared with that of non-pancreatitis UC *** 51 patients who developed acute pancreatitis, 13 (0.40%) had autoimmune, 10 (0.30%) had aminosalicylate-induced, and 13 (1.73%) had thiopurine-induced pancreatitis. All 13 patients with autoimmune pancreatitis (AIP) had type 2 AIP. Two (15.4%) patients had pre-existing AIP, and three (23.1%) patients developed AIP and UC simultaneously. Compared to non-pancreatitis patients, AIP patients had UC diagnosed at a significantly younger age (median, 22.9 years vs 36.4 years; P = 0.001). AIP and aminosalicylate-induced pancreatitis patients had more extensive UC compared to non-pancreatitis patients. All patients with pancreatitis recovered uneventfully, and there were no recurrences. Biologics were used more frequently in aminosalicylate- and thiopurine-induced pancreatitis patients compared to non-pancreatitis patients [adjusted OR (95%CI), 5.16 (1.42-18.67) and 6.90 (1.83-25.98), respectively]. Biologic utilization rate was similar among AIP and non-pancreatitis patients [OR (95%CI), 0.84 (0.11-6.66)]. Colectomy rates for autoimmune, aminosalicylate-induced, and thiopurine-induced pancreatitis, and for non-pancreatitis patients were 15.4% (2/13), 20% (2/10), 15.4% (2/13), and 7.3% (239/3256), respectively; the rates were not significantly different after adjusting for baseline disease *** patients show a non-significant increase in colectomy, after adjusting for baseline disease extent.

关键词： Ulcerative colitis Pancreatitis Autoimmune Colectomy Clinical course

HOS1 Facilitates the Phytochrome B-Mediated Inhibition of PIF4 Function during Hypocotyl Growth in Arabidopsis

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Molecular Plant 2017年第2期10卷 274-284页

作者： Ju-Heon Kim Hyo-Jun lee Jae-hoon Jung Sangmin lee Chung-Mo Park Department of Chemistry Seoul National University Seoul 08826 Korea Sainsbury Laboratory University of Cambridge Cambridge CB2 1LR UK Plant Genomics and Breeding Institute Seoul National University Seoul 08826 Korea These authors contributed equally to this article Present address: SK Innovation Daejeon 34124 Korea

Upon exposure to light, developing seedlings undergo photomorphogenesis, as illustrated by inhibition of hypocotyl elongation, cotyledon opening, and leaf greening. During hypocotyl photomorphogenesis, light signals are sensed by multiple photoreceptors, among which the red/far-red light-sensing phytochromes have been extensively studied. However, it is not fully understood how the phytochromes modulate hypo- cotyl growth. Here, we demonstrated that HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 1 （HOS1）, which is known to either act as E3 ubiquitin ligase or affect chromatin organization, inhibits the transcriptional activation activity of PHYTOCHROME INTERACTING FACTOR 4 （PIF4）, a key transcrip- tion factor that promotes hypocotyl growth. Consistent with the negative regulatory role of HOSl in hypo- cotyl growth, HOSl-defective mutants exhibited elongated hypocotyls in the light. Notably, phyB induces HOS1 activity in inhibiting PIF4 function. Taken together, these observations provide a molecular basis for the phyB-mediated suppression of hypocotyl growth in Arabidopsis.

关键词： photomorphogenesis hypocotyl growth phytochrome signaling HOS1 PIF4

Tailoring strength-ductility balance of caliber-rolled AZ31 Mg alloy through subsequent annealing

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Journal of Magnesium and Alloys 2020年第1期8卷 163-171页

作者： Taein Kong Byung Je Kwak Jonghyun Kim Jeong Hun lee Sung Hyuk Park Ji hoon Kim Young hoon Moon Hyun Sik Yoon Taekyung lee School of Mechanical Engineering Pusan National UniversityBusan 46241Republic of Korea Advanced Forming Process R&D Group Korea Institute of Industrial TechnologyUlsan 44413Republic of Korea College of Materials Science and Engineering Chongqing UniversityChongqing 400044China School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Naval Architecture and Ocean Engineering Pusan National UniversityBusan 46241Republic of Korea

Recently,multi-pass caliber rolling has been shown to be effective for Mg *** study investigated the effect of subsequent annealing on the mechanical properties of a caliber-rolled AZ31 Mg alloy to modulate the strength-ductility *** annealing gave rise to different trends in mechanical properties depending on the temperature ***-temperature annealing(T≤473 K)exhibited a typical trade-off relationship,where an increase in annealing temperature resulted in increased ductility but decreased strength and *** a heat treatment did not degrade the high strength-ductility balance of the caliber-rolled alloy,suggesting that the mechanical properties could be tailored for different potential *** contrast,high-temperature annealing(T>473 K)caused a simultaneous deterioration in strength,hardness,and ductility with increasing annealing *** differences are discussed in terms of the varying microstructural features under the different investigated annealing regimes.

关键词： AZ31 Mg alloy Caliber rolling Annealing Grain growth Mechanical improvement Twinning

Characterization of focal hypermetabolic thyroid incidentaloma: An analysis with F-18 fluorodeoxyglucose positron emission tomography/computed tomography parameters

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World Journal of Clinical Cases 2022年第1期10卷 155-165页

作者： Haejun lee Yoo Seung Chung Joon-Hyop lee Ki-Young lee Kyung-hoon Hwang Department of Nuclear Medicine Gachon University College of MedicineGil Medical CenterIncheon 21565South Korea Department of Endocrine Surgery Gachon University College of MedicineGil Medical CenterIncheon 21565South Korea Department of Endocrinology and Metabolism Gachon University College of MedicineGil Medical CenterIncheon 21565South Korea

BACKGROUND Incidentally found thyroid tumor(thyroid incidentaloma,TI)on F-18 fluorodeoxyglucose(FDG)positron emission tomography-computed tomography(PETCT)is reported in 2.5%-5%of patients being investigated for non-thyroid *** to 50%of these cases have been diagnosed to be malignant by cytological/histological ***(US)and fine-needle aspiration cytology are recommended for thyroid nodules with high FDG uptake(hypermetabolism)that are 1 cm or greater in *** is important to accurately determine whether a suspicious hypermetabolic TI is malignant or *** To distinguish malignant hypermetabolic TIs from benign disease by analyzing F-18 FDG PET-CT parameters and to identify a cut-off *** Totally,12761 images of patients who underwent F-18 FDG PET-CT for nonthyroid purposes at our hospital between January 2016 and December 2020 were retrospectively reviewed,and 339 patients[185 men(mean age:68±11.2)and 154 women(mean age:63±15.0)]were found to have abnormal,either focal or diffuse,thyroid FDG *** a thorough review of their medical records,US,and cytological/histological reports,46 eligible patients with focal hypermetabolic TI were included in this *** TIs were categorized as malignant and benign according to the cytological/histological reports,and four PET parameters[standardized uptake value(SUV)max,SUV_(peak),SUV_(mean),and metabolic tumor volume(MTV)]were measured on FDG *** lesion glycolysis(TLG)was calculated by multiplying the SUV_(mean) by *** parametric and non-parametric methods were used to compare the five parameters between malignant and benign *** operating characteristic(ROC)curve analysis was performed to identify a cut-off *** Each of the 46 patients[12 men(26.1%;mean age:62±13.1 years)and 34 women(73.9%;mean age:60±12.0 years)]with focal hypermetabolic TIs had one focal hypermetabolic *** them,26(56.5%)were malignant and 20(43.5%)were ***_(max

关键词： Thyroid incidentaloma Malignancy Fluorodeoxyglucose positron emission tomography/computed tomography Standardized uptake value Cut-off

Triangulated Cylinder Origami-Based Piezoelectric/Triboelectric Hybrid Generator to Harvest Coupled Axial and Rotational Motion

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Research 2021年第1期2021卷 460-468页

作者： Jihoon Chung myunghwan Song Seh-hoon Chung Woojin Choi Sanghyun lee Zong-Hong Lin Jinkee Hong Sangmin lee School of Mechanical Engineering Chung-Ang University84Heukseok-roDongjak-guSeoulRepublic of Korea Department of Chemical&Biomolecular Engineering College of EngineeringYonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Institute of Biomedical Engineering and Department of Power Mechanical Engineering National Tsing Hua University101Section 2Kuang-Fu RoadHsinchu 30013Taiwan

Piezoelectric nanogenerators(PENGs)and triboelectric nanogenerators(TENGs)are representative technologies that can harvest mechanical *** general,piezoelectric/triboelectric hybrid generators can harvest considerable energy with a limited input;however,PENGs and TENGs entail different requirements for harvesting ***,PENGs produce a large output when a large mechanical strain is applied,and TENGs require a large surface area to produce a high ***,it is necessary to develop an innovative strategy in terms of the structural design to satisfy the requirements of both PENGs and *** this study,we developed a triangulated cylinder origami-based piezoelectric/triboelectric hybrid generator(TCOHG)with an origami structure to enable effective energy *** proposed structure consists of a vertical contactseparation TENG on the surface of the triangulated cylinder,PENG on the inner hinge,and rotational TENG on the top substrate to harvest mechanical energy from each *** generator could produce a separate electrical output with a single *** TCO-HG could charge a 22μF commercial capacitor and power 60 LEDs when operated.

关键词： harvesting cylinder generator

Identification and comparison of the local physicochemical structures of transition metal-based layered double hydroxides for high performance electrochemical oxygen evolution reactions

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Journal of Energy Chemistry 2023年第12期87卷 89-97,I0004页

作者： Min Sung Kim Bipin Lamichhane Ju-Hyeon lee Jin-Gyu Bae Jeong Yeon Heo Hyeon Jeong lee Shyam Kattel Ji hoon lee School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea KNU Advanced Material Research Institute Kyungpook National UniversityDaegu 41566Republic of Korea Department of Materials Science and Engineering Ulsan National Institute of Science and TechnologyUlsan 44919Republic of Korea Department of Physics Florida A&M UniversityTallahasseeFlorida 32307United States

Layered double hydroxides(LDHs) have attracted considerable attention as a cost effective alternative to the precious iridium-and ruthenium-based electrocatalysts for an oxygen evolution reaction(OER),a bottleneck of water electrolysis for sustainable hydrogen *** their excellent OER performance,the structural and electronic properties of LDHs,particularly during the OER process,remain to be poorly *** this study,a series of LDH catalysts is investigated through in situ X-ray absorption fine structure analyses and density functional theory(DFT) *** experimental results reveal that the LDH catalyst with equal amounts of Ni and Fe(NF-LDH) exhibits the highest OER activity and catalytic life span when compared with its counterparts having equal amounts of Ni and Co(NC-LDH)and Ni only(Ni-LDH).The NF-LDH shows a markedly enhanced OER kinetics compared to the NC-LDH and the Ni-LDH,as proven by the lower overpotentials of 180,240,and 310 mV,respectively,and the Tafel slopes of 35.1,43.4,and 62.7 mV dec^(-1),*** DFT calculations demonstrate that the lowest overpotential of the NF-LDH is associated with the active sites located at the edge planes of NF-LDH in contrast to those located at the basal planes of Ni-LDH and *** current study pinpoints the active sites on various LDHs and presents strategies for optimizing the OER performance of the LDH catalysts.

关键词： Layered double hydroxides Oxygen evolution reaction In situ X-ray analyses Density functional theory Catalytic active sites

EXPERIMENTAL ESTIMATION OF A SCALING EXPONENT FOR TIP VORTEX CAVITATION VIA ITS INCEPTION TEST IN FULL-AND MODEL-SHIP

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Journal of Hydrodynamics 2012年第5期24卷 658-667页

作者： lee Jeung-hoon JUNG Jae-Kwon lee Kyung-Jun HAN Jae-Moon PARK Hyung-Gil SEO Jong-Soo Samsung Ship Model Basin(SSMB) Marine Research InstituteSamsung Heavy IndustriesScience TownDaejeon 305-380Korea

Tip vortex cavitation noise of marine propeller became primary concems to reduce hazardous environmental impacts from commercial ship or to keep the underwater surveillance of naval ships. The investigations of the tip vortex and its induced noise are normally conducted through the model test in a water cavitation tunnel. However the Reynolds number of model-test is much smaller than that of the full-scale, which subsequently results in the difference of tip vortex cavitation inception. Hence, the scaling law between model- and full-scales needs to be identified prior to the prediction and assessment of propeller noise in full scale. From previous researches, it is generally known that the incipient caivtation number of tip vortex can be represented as a power of the Reynolds number. However, the power exponent for scaling, which is the main focus of this research, has not been clearly studied yet. This paper deals with the estimation of scaling exponent based on tip vortex cavitation inception test in both full- and model-scale ships. Acoustical measurements as well as several kind of signal processing technique for an inception criterion suggest the scaling exponent as 0.30. The scaling value proposed in this study shows slight difference to the one of most recent research. Besides, extrapolation of model-ship noise measurement using the proposed one predicts the full-scale noise measurement with an acceptable discrepancy.

关键词： tip vortex cavitation underwater radiated noise scaling exponent