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Yena Kang,Eun-Jung Kim,Young Seok Kim,Sang Gyune Kim,Jae Myeong Lee2,Boo Sung Kim 순천향대학교 순천향의학연구소 2015 Journal of Soonchunhyang Medical Science Vol.21 No.2
Transcatheter arterial chemoembolization (TACE) is suitable treatment method of hepatocellular carcinoma (HCC) for patients with decreased underlying liver function or unresectable disease. But this procedure can induce some embolic events. We report a case of a gallbladder infarction caused by the embolic event in TACE procedure. A 61-year-old man had been going to undergo 6th TACE for marginal recurrence of HCC. After the procedure, gallbladder infarction occurred and was detected by abdominal computed tomography (CT) scan for response evaluation of the treatment at out-patient-clinic. Then, he was treated with oral antibiotics and conservative therapy at out-patient clinic. In 6th week after the event, abdominal CT scan showed improved state of gallbladder.
Optical design of ZnO-based antireflective layers for enhanced GaAs solar cell performance
Lee, Hye Jin,Lee, Jae Won,Kim, Hee Jun,Jung, Dae-Han,Lee, Ki-Suk,Kim, Sang Hyeon,Geum, Dae-myeong,Kim, Chang Zoo,Choi, Won Jun,Baik, Jeong Min The Royal Society of Chemistry 2016 Physical chemistry chemical physics Vol.18 No.4
<P>A series of hierarchical ZnO-based antireflection coatings with different nanostructures (nanowires and nanosheets) is prepared hydrothermally, followed by means of RF sputtering of MgF2 layers for coaxial nanostructures. Structural analysis showed that both ZnO had a highly preferred orientation along the < 0001 > direction with a highly crystalline MgF2 shell coated uniformly. However, a small amount of Al was present in nanosheets, originating from Al diffusion from the Al seed layer, resulting in an increase of the optical bandgap. Compared with the nanosheet-based antireflection coatings, the nanowire-based ones exhibited a significantly lower reflectance (similar to 2%) in ultraviolet and visible light wavelength regions. In particular, they showed perfect light absorption at wavelength less than approximately 400 nm. However, a GaAs single junction solar cell with nanosheet-based antireflection coatings showed the largest enhancement (43.9%) in power conversion efficiency. These results show that the increase of the optical bandgap of the nanosheets by the incorporation of Al atoms allows more photons enter the active region of the solar cell, improving the performance.</P>
Lee, Myeong-Woo,Kim, Ji-Seok,Jeon, Jun-Young,Kim, Yun-Jae,Kim, Jin-Weon,Kim, Jong-Sung Pergamon Press 2018 Engineering fracture mechanics Vol.201 No.-
<P>This paper compares numerical predictions with experimental burst pressures of Alloy 690TT steam generator tubes with multiple surface cracks of forty-one different cases at two different temperatures. For numerical prediction, the simplified multi-axial fracture strain model is used. The damage model is determined from tensile tests of smooth and notched tubes. Predicted maximum pressures are in good agreement with experimental data of steam generator tubes with multiple surface cracks.</P>
Lee, Minbok,Yang, Joonseok,Park, Myeong-Jae,Jung, Sung-Youb,Kim, Jaeha IEEE 2018 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS PART 1 R Vol.65 No.1
<P>This paper presents a piezoelectric-based power management solution for battery-free wireless remote switches (BWSs). The proposed BWS IC, including a piezoelectric (PE) energy harvester and a buck converter, can collect the energy generated by a single PE-button press, and then supply that energy to a wireless transmitter to send a message. By combining a rectifier using the synchronized switch harvesting on inductor technique and a 6:1 series–parallel switched-capacitor converter, the proposed PE energy harvester can maximize the collected amount of energy, while supplying it at a low output voltage. In addition, by employing a switching-based start-up scheme and a variable ON-time pulse-frequency modulation scheme, the proposed buck converter can reduce the loss associated with charging the output capacitor during start-up, and then deliver the largest possible energy to the load, while maintaining low voltage ripples and high-power efficiency. A prototype BWS IC fabricated with high-voltage 250-nm CMOS technology was shown to be capable of harvesting a total energy of <TEX>$246~\mu \text{J}$</TEX> from a single button-pressing of a 300-mm<SUP>2</SUP> lead magnesium niobate-lead titanate PE disc. More than <TEX>$200~\mu \text{J}$</TEX> was delivered to the load, sufficient to transmit a 4-B-long message via a 2.4-GHz wireless USB channel over a 10-m distance.</P>
Hepatocyte-specific Prominin-1 protects against liver injury-induced fibrosis by stabilizing SMAD7
Lee Hyun,Yu Dong-Min,Bahn Myeong-Suk,Kwon Young-Jae,Um Min Jee,Yoon Seo Yeon,Kim Ki-Tae,Lee Myoung-Woo,Jo Sung-Je,Lee Sungsoo,Koo Seung-Hoi,Jung Ki Hoon,Lee Jae-Seon,Ko Young-Gyu 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-
Prominin-1 (PROM1), also known as CD133, is expressed in hepatic progenitor cells (HPCs) and cholangiocytes of the fibrotic liver. In this study, we show that PROM1 is upregulated in the plasma membrane of fibrotic hepatocytes. Hepatocellular expression of PROM1 was also demonstrated in mice (Prom1CreER; R26TdTom) in which cells expressed TdTom under control of the Prom1 promoter. To understand the role of hepatocellular PROM1 in liver fibrosis, global and liver-specific Prom1-deficient mice were analyzed after bile duct ligation (BDL). BDL-induced liver fibrosis was aggravated with increased phosphorylation of SMAD2/3 and decreased levels of SMAD7 by global or liver-specific Prom1 deficiency but not by cholangiocyte-specific Prom1 deficiency. Indeed, PROM1 prevented SMURF2-induced SMAD7 ubiquitination and degradation by interfering with the molecular association of SMAD7 with SMURF2. We also demonstrated that hepatocyte-specific overexpression of SMAD7 ameliorated BDL-induced liver fibrosis in liver-specific Prom1-deficient mice. Thus, we conclude that PROM1 is necessary for the negative regulation of TGFβ signaling during liver fibrosis.
Prediction of strength of drawn bar considering non-uniform strain distribution
Sung-Min Lee,이인규,이성윤,박동용,Myeong-Sik Jeong,Young Hoon Moon,이상곤 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11
In bar drawing process, the material passes through the drawing die. The surface of the material directly in contact with the drawing die has a relatively higher strain and strain rate than the center. That is, a non-uniform strain distribution appears over the crosssection of the drawn material, such that it is concentrated on the surface of the material and relatively low at the center, thus, residual stress or wire breakage may occur in the drawn material. The purpose of this study is to predict the non-uniform strain distribution from the center to the surface of a drawn bar and apply this prediction to evaluate its strength. In this study, the strain distribution was evaluated using finite element analysis and a non-uniform strain prediction model. Then, a strength prediction model considering the non-uniform strain distribution was proposed. Finally, the strain and strength prediction models were experimentally verified through a multistage drawing experiment.
Lee, Hyun Ji,Kim, Sung-Jo,Ko, Myeong Ock,Kim, Jong-Hyun,Jeon, Min Yong Elsevier 2018 OPTICS COMMUNICATIONS - Vol.410 No.-
<P><B>Abstract</B></P> <P>We propose a tunable multiwavelength-swept laser based on a nematic liquid crystal (NLC) Fabry–Perot (FP) etalon, which is embedded in the resonator of a wavelength-swept laser. We achieve the continuous wavelength tuning of the multiwavelength-swept laser by applying the electric field to the NLC FP etalon. The free spectral range of the fabricated NLC FP etalon is approximately 7.9 nm. When the electric field applied to the NLC FP etalon exceeds the threshold value (Fréedericksz threshold voltage), the output of the multiwavelength-swept laser can be tuned continuously. The tuning range of the multiwavelength-swept laser can be achieved at a value greater than 75 nm, which has a considerably wider tunable range than a conventional multiwavelength laser based on an NLC FP etalon. The slope efficiencies in the spectral and temporal domains for the tunable multiwavelength-swept laser are 22.2 nm/(mV <SUB> rms </SUB> ∕ μ m) and 0.17 ms/(mV <SUB> rms </SUB> ∕ μ m), respectively in the linear region. Therefore, the developed multiwavelength-swept laser based on the NLC FP etalon can be applied to an electric-field sensor. Because the wavelength measurement and time measurement have a linear relationship, the electric-field sensor can detect a rapid change in the electric-field intensity by measuring the peak change of the pulse in the temporal domain using the NLC FP etalon-based multiwavelength-swept laser.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We propose a widely tunable multiwavelength-swept laser. </LI> <LI> The tuning range of the multiwavelength laser can be achieved more than 75 nm. </LI> <LI> We developed multiwavelength-swept laser based on NLC FP etalon. </LI> </UL> </P>
Sung-Sub Kim,Myeong-Joon Kim,Joon-Hyun Lee,Jin-Seok Lee,Hyun-Jik Cho,Chul-Goo Kang 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
Fault prognostics of an air compressor is a challenging issue for condition-based maintenance of a railway vehicle. In this paper, we propose a mathematical model of a two-stage reciprocating air compressor to obtain normal and abnormal data for the pressure and temperature for various parts of the air compressor. The mathematical model includes kinematic equations of crank mechanism, thermodynamic equations of cylinders, valve flow equations, and heat transfer equations of cylinder blocks. Especially, heat transfer effects at cylinder blocks are simulated for the cases with and without heat transfer. Simulation results show that the mathematical model is valid and heat transfer effect at cylinder blocks is minimal to cylinder pressure but affects cylinder temperature significantly.