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Yong‑Sang Kim,Jung‑Gu Kim 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4
In this paper, the infl uence of weld corrosion on the mechanical behavior of a welded joint pipeline was investigated usingcorrosion and mechanical simulations simultaneously. In the corrosion simulation, the modeling results (i.e., the corrosionpotential and current density) revealed that the welded joint is preferentially corroded and the corrosion rate is higher in theoutside environment due to the severe corrosion factors. The increase in corrosion degradation according to the operationtime increases the stress concentration on the welded joint, indicating that the failure risk of the welded joint is increasedwith increasing corrosion degradation. These results can be used to evaluate the lifetime of welded joints exposed to corrosionand suggest guidelines for the maintenance of structures.
Effect of Strain Aging on Tensile Behavior and Properties of API X60, X70, and X80 Pipeline Steels
Sang‑In Lee,Seung‑Yong Lee,Seok Gyu Lee,Hwan Gyo Jung,Byoungchul Hwang 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6
The effect of strain aging on tensile behavior and properties of API X60, X70, and X80 pipeline steels was investigated inthis study. The API X60, X70, and X80 pipeline steels were fabricated by varying alloying elements and thermomechanicalprocessing conditions. Although all the steels exhibited complex microstructure consisting of polygonal ferrite (PF), acicularferrite, granular bainite (GB), bainitic ferrite (BF), and secondary phases, they had different fractions of microstructuresdepending on the alloying elements and thermomechanical processing conditions. The tensile test results revealed that yieldingbehavior steadily changed from continuous-type to discontinuous-type as aging temperature increases after 1% pre-strain. After pre-strain and thermal aging treatment in all the steels, the yield and tensile strengths, and yield ratio were increased,while the uniform elongation and work hardening exponent were decreased. In the case of the X80 steel, particularly, thedecrease in uniform elongation was relatively small due to many mobile dislocations in PF, and the increase in yield ratiowas the lowest because a large amount of harder microstructures such as GB, BF, and coarse secondary phases effectivelyenhanced work hardening.
A Multi-Center Educational Research Regarding Breastfeeding for Pediatrics Residents in Korea
Yong Sung Choi,정성훈,김은선,Eun Sun Kim,Eunhee Lee,Euiseok Jung,So-Yeon Lee,이우령,Hye Sun Yoon,Yong Joo Kim,Ji Kyoung Park,Son Moon Shin,Ellen Ai-Rhan Kim 대한신생아학회 2022 Neonatal medicine Vol.29 No.1
Purpose: Pediatricians have a significant responsibility to educate mothers about the importance of breastfeeding. However, there have been minimal efforts in the courses of resident training in Korea. The purpose of this study is to evaluate the change in knowledge and attitude before and after a 4-week breastfeeding educational intervention among multicenter residents. Methods: Prospective interventional educational research was designed for residents at eight training hospitals in Korea. Institutional reviews were obtained in each hospital. The education curriculum consisted of 14 courses regarding breastfeeding theory and practice. These materials were used to teach pediatric residents for 4 weeks. Knowledge-based tests were administered before the course, and re-tests were administered after the course using different test items of similar levels. Test scores and survey responses were compared before and after the intervention. Results: A total of 73 residents (1st year 20, 2nd year 23, 3rd year 16, and 4th year residents 14) from eight training hospitals completed the intervention. Their average age was 30.3±2.9 years, 17 (23.3%) were male, 22 (30.1%) were married, and eight had more than one child of their own. The mean pre-test score was 61.8±13.4 and the mean post-test score was 78.3±7.5 (P<0.001). The inter-grade difference in the score was significant in the pre-test (P=0.005), but not significant in the post-test (P=0.155). There were more responses of obtaining confidence after the intervention (P<0.001). Conclusion: In our study, pediatric residents showed improvement in their knowledge and confidence level after 4 weeks of the breastfeeding curriculum. This will provide a basis for future policymaking in the training of pediatric residents regarding breastfeedReceived: 6 January 2022 Revised: 15 February 2022 Accepted: 15 February 2022 Correspondence to: Ellen Ai-Rhan Kim, MD Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea Tel: +82-2-3010-3390 Fax: +82-2-3010-6978 E-mail: arkim@amc.seoul.kr A Multi-Center Educational Research Regarding Breastfeeding for Pediatrics Residents in Korea Yong-Sung Choi, MD,PhD1, Sung-Hoon Chung, MD, PhD2, Eun Sun Kim, MD, PhD3, Eun Hee Lee, MD4, Euiseok Jung, MD5, So Yeon Lee, MD, PhD5, Wooryoung Lee, MD6, Hye Sun Yoon, MD, PhD7, Yong Joo Kim, MD, PhD8, Ji Kyoung Park, MD, PhD9, Son Moon Shin, MD, PhD9, and Ellen Ai-Rhan Kim, MD, PhD5 1Department of Pediatrics, Kyung Hee University Hospital, Seoul, Korea 2Department of Pediatrics, Kyung Hee University Hospital at Gangdong, Seoul, Korea 3Department of Pediatrics, Kangwon National University Hospital, Chuncheon, Korea 4Department of Pediatrics, Korea University Anam Hospital, Seoul, Korea 5Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea 6Department of Pediatrics, Soonchunhyang University Seoul Hospital, Seoul, Korea 7Department of Pediatrics, Nowon Eulji Medical Center, Eulji University, Seoul, Korea 8Department of Pediatrics, Hanyang University Seoul Hospital, Seoul, Korea 9Department of Pediatrics, Inje University Busan Paik Hospital, Busan, Korea Neonatal Med 2022 February;29(1):28-35 https://doi.org/10.5385/nm.2022.29.1.28 pISSN 2287-9412 . eISSN 2287-9803 Copyright(c) 2022 By Korean Society of Neonatology This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/4.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Original Article 29 Neonatal Med 2022 February;29(1):28-35 https://doi.org/10.5385/nm.2022.29.1.28 ing in Korea.
Yong‑Sang Kim,Sang‑Jin Ko,Sangkyu Lee,Jung‑Gu Kim 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.2
An interpretation of the relation between the electric field and the applied current for cathodic protection is investigated usinga boundary element method simulation. Also, a conductivity-difference environment is set for the interface influence. Thevariation of the potential distribution is increased with the increase of the applied current and the conductivity differencedue to the rejection of the current at the interface. In the case of the electric field, the tendencies of the increasing rate andthe applied currents are similar, but the interface influence is different according to the directional component and field type(decrease of Ez and increases of Ex and Ey) due to the directional difference between the electric fields. Also, the changetendencies of the electric fields versus the applied current plots are affected by the polarization curve tendency regardingthe polarization type (activation and concentration polarizations in the oxygen-reduction and hydrogen-reduction reactions). This study shows that the underwater electric signature is determined by the polarization behavior of the materials.
Park, Jinbong,Jeon, Yong-Deok,Kim, Hye-Lin,Lim, Hara,Jung, Yunu,Youn, Dong-Hyun,Jeong, Mi-Young,Kim, Hyun-Ju,Kim, Sung-Hoon,Kim, Su-Jin,Hong, Seung-Heon,Um, Jae-Young Hindawi Publishing Corporation 2013 Evidence-based Complementary and Alternative Medic Vol.2013 No.-
<P>Obesity has become a major health threat in developed countries. However, current medications for obesity are limited because of their adverse effects. Interest in natural products for the treatment of obesity is thus rapidly growing. Korean Medicine (KM) is characterized by the wide use of herbal formulas. However, the combination rule of herbal formulas in KM lacks experimental evidence. According to <I>Shennong's Classic of Materia Medica</I>, the earliest book of herbal medicine, <I>Veratrum nigrum</I> (VN) has antagonistic features against <I>Panax ginseng</I> (PG), and the PG-VN pair is strictly forbidden. In this study, we have shown the effects of PG, VN, and their combination on obesity in high-fat (HF) diet-induced obese mice and in 3T3-L1 cells. PG, VN, and PG-VN combination significantly reduced weight gain and the fat pad weight in HF diet-induced obese mice. They also significantly decreased lipid accumulation and the expressions of two major adipogenesis factors, PPAR<I><I>γ</I></I> and C/EBP<I><I>α</I></I>, in 3T3-L1 cells. In addition, the PG-VN combination had synergistic effects compared with the mixture of extracts of PG and VN on inhibition of PPAR<I><I>γ</I></I> and C/EBP<I><I>α</I></I> expressions at lower doses. These results indicate a new potential anti-obese pharmacotherapy and also provide scientific evidence supporting the usage of herbal combinations instead of mixtures in KM.</P>
( Jung Taeck Hong ),( Kyung Rim Sung ),( Jung Woo Cho ),( Sung Cheol Yun ),( Sung Yong Kang ),( Michael S. Kook ) 대한안과학회 2012 Korean Journal of Ophthalmology Vol.26 No.1
Purpose: To evaluate the effect of the scanning laser ophthalmoscope (SLO) guided re-test mode on short- and long-term measurement variability of peripapillary retinal nerve fiber layer (RNFL) thickness obtained by spectral domain-SLO optical coherence tomography (SD-SLO/OCT). Methods: Seventy five healthy eyes were scanned 3 times per day (intra-session variability) by both the SLO guided re-test mode and the independent mode of SD-SLO/OCT. Subjects were scanned 3 times by both modes at visits within a 2-week interval (inter-session variability). For testing longitudinal variability, 3 separate exams were performed over 6 months by both modes. The coefficient of variation (CV), reproducibility coefficient (RC) and intraclass correlation coefficient of RNFL thickness were compared between the two modes. Results: The intra-session RC and CV ranged from 5.4 to 12.9 microns and 1.76% to 5.72% when measured by independent mode and 5.4 to 12.5 microns and 1.75% to 5.58% by re-test mode, respectively. The inter-session RC and CV ranged from 5.8 to 13.3 microns and 1.89% to 5.78% by independent mode and 5.8 to 12.7 microns and 1.90% to 5.54% by re-test mode, respectively. Intra-session and inter-session variability measurements were not significantly different between the two modes. The longitudinal RC and CV ranged from 8.5 to 19.2 microns and 2.79% to 7.08% by independent mode and 7.5 to 14.4 microns and 2.33% to 6.22% by retest mode, respectively. Longitudinal measurement variability was significantly lower when measured by the re-test mode compared to the independent mode (average, p = 0.011). Conclusions: The SLO guided re-test mode for RNFL thickness measurement in SD-SLO/OCT employing a tracking system improved long-term reproducibility by reducing variability induced by inconsistent scan circle placement.