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Hwang, Hye Jeon,Kim, Kyoung Won,Jeong, Woo Kyoung,Kim, So Yeon,Song, Gi-Won,Hwang, Shin,Lee, Sung-Gyu American Roentgen Ray Society, etc.] 2009 American Journal of Roentgenology Vol.193 No.3
<P>OBJECTIVE: The objective of our study was to compare CT and Doppler ultrasound in the diagnosis of hepatic outflow obstruction at the middle hepatic vein (MHV) tributaries and inferior right hepatic veins (RHVs) after living donor liver transplantation (LDLT) with modified right lobe grafts. MATERIALS AND METHODS: Thirty-seven venographies were performed in 36 patients after LDLT with modified right lobe grafts, evaluating 51 MHV tributaries and 25 inferior RHVs. They were classified as obstructed or nonobstructed. On Doppler ultrasound or CT, flow patterns of the MHV tributaries and inferior RHVs or the relative parenchymal attenuation, enhancement, and opacification of these veins were evaluated for the diagnosis of hepatic outflow obstruction. McNemar tests were performed to compare the diagnostic values of Doppler ultrasound and CT. RESULTS: On the basis of hepatic venography, 33 MHV tributaries were categorized as obstructed and 18 as nonobstructed, and 16 inferior RHVs were categorized as obstructed and nine as nonobstructed. For the diagnosis of MHV tributary obstruction, Doppler ultrasound was more sensitive and accurate, although less specific, than CT (97% vs 39%, respectively, p < 0.001; 86% vs 61%, p = 0.0209; 67% vs 100%, p = 0.0412). Similarly, Doppler ultrasound was more sensitive (94% vs 31%, respectively) and accurate (84% vs 56%) than CT, although less specific (67% vs 100%), for the diagnosis of inferior RHV obstruction, with a statistical significance only for sensitivity (p = 0.002, 0.092, and 0.248, respectively). CONCLUSION: Doppler ultrasound is more sensitive and accurate than CT for the detection of obstruction at the MHV tributaries and inferior RHVs in patients after LDLT using modified right lobe grafts. Although current CT criteria produce high specificity and may reduce unnecessary invasive venographies, optimal CT criteria with acceptable sensitivity should be reestablished.</P>
Determinants of Exercise Capacity in Patients With Hypertrophic Cardiomyopathy
Hwang Ji-won,Lee Sang-Chol,Kim Darae,Kim Jihoon,Kim Eun Kyoung,Chang Sung-A,Park Sung-Ji,Kim Sung Mok,Choe Yeon Hyeon,Ahn Joong Hyun,Park Seung Woo 대한의학회 2022 Journal of Korean medical science Vol.37 No.8
Background: Reduced exercise capacity reflects symptom severity and clinical outcomes in patients with hypertrophic cardiomyopathy (HCM). The present study aimed to identify factors that may affect exercise capacity in patients with HCM. Methods: In 294 patients with HCM and preserved left ventricular (LV) ejection fraction, we compared peak oxygen consumption (peak VO2) evaluated by cardiopulmonary exercise testing as a representative parameter of exercise tolerance with clinical and laboratory data, including N-terminal pro-hormone of brain natriuretic peptide (NT-proBNP), diastolic parameters on echocardiography, and the grade of myocardial fibrosis on cardiac magnetic resonance imaging (CMR). Results: Median peak VO2, was 29.0 mL/kg/min (interquartile range [IQR], 25.0–34.0). Age (estimated β = −0.140, P < 0.001), female sex (β = −5.362, P < 0.001), NT-proBNP (β = −1.256, P < 0.001), and E/e′ ratio on echocardiography (β = −0.209, P = 0.019) were significantly associated with exercise capacity. Peak VO2 was not associated with the amount of myocardial fibrosis on CMR (mean of late gadolinium enhancement 12.25 ± 9.67%LV). Conclusion: Decreased exercise capacity was associated with age, female sex, increased NTproBNP level, and E/e′ ratio on echocardiography. Hemodynamic changes and increased filling pressure on echocardiography should be monitored in this population for improved outcomes.
Hwang, In Koo,Yoo, Ki-Yeon,Jung, Boo-Kyoung,Cho, Jun Hwi,Kim, Do-Hoon,Kang, Tae-Cheon,Kwon, Young-Guen,Kim, Yong-Sun,Won, Moo Ho Elsevier 2006 Experimental neurology Vol.201 No.1
<P><B>Abstract</B></P><P>It is known that the hippocampus has vital functions in learning and memory, behavioral regulation, and activity-dependent synaptic plasticity, and that the hippocampus contains high levels of brain-derived neurotrophic factor (BDNF). In the present study, we followed age-dependent changes of BDNF immunoreactivity and protein level in the gerbil hippocampus to identify the correlation between BDNF and aging. BDNF immunoreactivity and its protein level significantly increased at postnatal month (PM) 12 in the hippocampus and thereafter reduced. At PM 24, BDNF immunoreactivity in the hippocampal CA1 region and dentate gyrus was similar to that in the PM 1 group, whereas BDNF immunoreactivity in the CA2/3 region at PM 24 was higher than that at PM 1. In the PM 24 group, an age-related neuronal loss and the decrease of reference and working memory were observed. In conclusion, our results suggest that observed reduction in BDNF and reference memory may be associated with age-dependent neuronal loss in the hippocampal CA1 region.</P>
Switching of Photonic Crystal Lasers by Graphene
Hwang, Min-Soo,Kim, Ha-Reem,Kim, Kyoung-Ho,Jeong, Kwang-Yong,Park, Jin-Sung,Choi, Jae-Hyuck,Kang, Ju-Hyung,Lee, Jung Min,Park, Won Il,Song, Jung-Hwan,Seo, Min-Kyo,Park, Hong-Gyu American Chemical Society 2017 NANO LETTERS Vol.17 No.3
<P>Unique features of graphene have motivated the development of graphene-integrated photonic devices. In particular, the electrical tunability of graphene loss enables high-speed modulation of light and tuning of cavity resonances in graphene-integrated waveguides and cavities. However, efficient control of light emission such as lasing, using graphene, remains a challenge. In this work, we demonstrate on/off switching of single- and double-cavity photonic crystal lasers by electrical gating of a monolayer graphene sheet on top of photonic crystal cavities. The optical loss of graphene was controlled by varying the gate voltage V-g, with the ion gel atop the graphene sheet. First, the fundamental properties of graphene were investigated through the transmittance measurement and numerical simulations. Next, optically pumped lasing was demonstrated for a graphene-integrated single photonic crystal cavity at V-g below-0.6 V, exhibiting a low lasing threshold of -4801 mu W, whereas lasing was not observed at V-g above -0.6 V owing to the intrinsic optical loss of graphene. Changing quality factor of the graphene-integrated photonic crystal cavity enables or disables the lasing operation. Moreover, in the double-cavity photonic crystal lasers with graphene, switching of individual cavities with separate graphene sheets was achieved, and these two lasing actions were controlled independently despite the close distance of -2.2 mu m between adjacent cavities. We believe that our simple and practical approach for switching in graphene-integrated active photonic devices will pave the way toward designing high-contrast and ultracompact photonic integrated circuits.</P>
( Kyoung Ho Moon ),( Joon Soon Kang ),( Man Hee Won ),( Myoung Joo Park ),( Jae Hwang Choi ) 대한고관절학회 2015 Hip and Pelvis Vol.27 No.2
Purpose: This study was performed to determine the usefulness of three-dimensional computed tomography (3D-CT) in measuring periacetabular osteolysis by comparing the real volume of osteolysis in revision surgery. Materials and Methods: Twnety-three patients who had undergone revision surgery due to periacetabular osteolysis but not included septic osteolysis and implant loosening. The mean age of patients at the time of surgery was 55.2 years. And the mean time interval between the primary total hip arthroplasty and revision surgery was 13.3 years. We measured the polyethylene wear in plain radiographs using computer assisted vector wear analysis program, the volume of acetabular osteolytic lesions in high-resolution spiral CT scans using Rapidia 3D software version 2.8 algorithms before the revision surgery were performed. Intraoperative real osteolytic volume was calculated as the sum of the volumetric increments of the acetabular cup and impacted allo-cancellous bone volume. Results: Strong correlation was found between the volume of acetabular osteolytic lesions measured on 3D-CT and intraoperative real osteolytic volume which was calculated as the sum of the volumetric increments of the acetabular cup and impacted allo-cancellous bone volume. Conclusion: 3D-CT is considered a useful method for assessing and measuring the volume of periacetabular osteolysis before revision surgery.
Won Kim,Seyeon Bae,Hyemin Kim,Yejin Kim,Jiwon Choi,Sun Young Lim,Hei Jin Lee,Jihyuk Lee,Jiyea Choi,Mirim Jang,Kyoung Eun Lee,Sun G,Chung,Young-il Hwang,Jae Seung Kang,Wang Jae Lee 대한해부학회 2013 Anatomy & Cell Biology Vol.46 No.4
The L-gulono-γ-lactone oxidase gene (Gulo) encodes an essential enzyme in the synthesis of ascorbic acid from glucose. On the basis of previous findings of bone abnormalities in Gulo-/- mice under conditions of ascorbic acid insufficiency, we investigated the effect of ascorbic acid insufficiency on factors related to bone metabolism in Gulo-/- mice. Four groups of mice were raised for 4 weeks under differing conditions of ascorbic acid insufficiency, namely, wild type; ascorbic acid-sufficient Gulo-/- mice, 3-week ascorbic acid-insufficient Gulo-/- mice, and 4-week ascorbic acid-insufficient Gulo-/- mice. Four weeks of ascorbic acid insufficiency resulted in significant weight loss in Gulo-/- mice. Interestingly, average plasma osteocalcin levels were significantly decreased in Gulo-/- mice after 3 weeks of ascorbic acid insufficiency. In addition, the tibia weight in ascorbic acid-sufficient Gulo-/- mice was significantly higher than that in the other three groups. Moreover, significant decreases in trabecular bone volume near to the growth plate, as well as in trabecular bone attachment to the growth plate, were evident in 3- or 4-week ascorbic acid-insufficient Gulo-/-. In summary, ascorbic acid insufficiency in Gulo-/- mice results in severe defects in normal bone formation, which are closely related to a decrease in plasma osteocalcin levels.
Improved FOC of IPMSM using Finite-state Model Predictive Current Control for EV
Won, Il-Kuen,Hwang, Jun-Ha,Kim, Do-Yun,Choo, Kyoung-Min,Lee, Soon-Ryung,Won, Chung-Yuen The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5
Interior permanent magnet synchronous motor (IPMSM) is most commonly used in the automotive industry as a traction motor for electric vehicle (EV). In electric vehicle, the torque output rapidly changes according to the operation of the accelerator and the braking of the driver. The transient torques are thus generated very frequently in accordance with the variable speed control of the driver. Therefore, in this paper, a method for improving the torque response in the transient states of IPMSM is proposed. In order to complement the disadvantages of the conventional PI current controller in the field oriented control (FOC), the finite-state model predictive current control and 2D-LUT is applied to improve the torque response at the torque transient period. Simulation and experiment results are given to verify the reliability of the proposed method.
Characterization of Indium Hydroxide Powders Synthesized by a Precipitation Method
Won-Jun Lee,Eun-Kyoung Choi,Ung-Soo Kim,Jong-Young Kim,Kwang Bo Shim,Hae Jin Hwang,Woo-Seok Cho 한양대학교 세라믹연구소 2017 Journal of Ceramic Processing Research Vol.18 No.11
Indium hydroxide powders were synthesized using indium nitride, and the characteristics of the indium hydroxide powder were investigated according to the precipitate aging time and the pH and concentration of the liquid synthesis medium. Indium hydroxide (In(OH)3) and indium oxide hydroxide (InOOH) phases co-existed in all conditions studied here. The crystallite size of In(OH)3 was more dependent on the concentration and pH of the reaction medium compared to that of InOOH. Hence, the relative crystallite scale of In(OH)3 increased with increasing concentration and pH of the reaction liquid more than that of in InOOH. Although the crystallite size did not change much with an increase of precipitate aging time, the specific surface area decreased greatly. Such results can aid in the synthesis of indium oxide particles that are used for producing ITO targets.