Evaluation of Hot Deformation and Dynamic Recrystallization Behaviors of Advanced Reduced-Activated Alloy (ARAA)

Sang‑Wook Kim,Hyeon‑Woo Son,Taek‑Kyun Jung,Young‑Bum Chun,Yi‑Hyun Park,Ji‑Woon Lee,Soong‑Keun Hyun 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4

The hot deformation behavior of advanced reduced-activation alloy (ARAA) was investigated using hot torsion tests. Thefl ow stress decreased as deformation temperature increased and as strain rate decreased. The fl ow behavior demonstratedthe typical dynamic recrystallization (DRX). Based on the constitutive analysis of peak stress, the activation energy for hotdeformation was found to be 330.3 kJ mol −1 . Peak stress was analyzed as a function of the Zener–Hollomon parameter, andcalculated and experimental values were in good agreement. A DRX kinetic model for ARAA was derived with deformationconditions based on the Avrami-type model. It was confi rmed that the volume fraction of dynamically recrystallized grainsincreased as deformation temperature increased and as strain rate decreased. The necklace structure and grain boundarybulging were observed in the deformed microstructure of ARAA. The suggested DRX mechanism for ARAA during hotworking is discontinuous DRX.

Effect of Hydride Reorientation on Delayed Hydride Cracking In Zr-2.5Nb Tubes

Yun Yeo Bum,Kim Young Suk,Im Kyung Soo,Cheong Yong Moo,Kim Sung Soo Korean Nuclear Society 2003 Nuclear Engineering and Technology Vol.35 No.6

The objective of this study is to investigate the reorientation of hydrides with applied stress intensity factor, the peak temperature and the time when to apply the stress intensity factor in a Zr-2.5Nb pressure tube during its thermal cycle treatment. Cantilever beam (CB) specimens with a notch of 0.5 mm in depth made from the Zr-2.5Nb tube were subjected to electrolytic hydrogen charging to contain 60 ppm H and then to a thermal cycle involving heating to the peak temperature of either 310 or $380^{\circ}C$, holding there for 50 h and then cooling to the test temperature of $250^{\circ}C$. The stress intensity factor of either 6.13 or $18.4\;MPa\sqrt{m}$ was applied at the beginning of the thermal cycle, at the end of the hold at the peak temperatures and after cooling to the test temperature, respectively. The reorientation of hydrides in the Zr-2.5Nb tube was enhanced with the increased peak temperature and applied stress intensity factor. Furthermore, when the CB specimens were subjected to $18.4\;MPa\sqrt{m}$ from the beginning of the thermal cycle, the reoriented hydrides occurred almost all over the Zr-2.5Nb tube, surprisingly suppressing the growth of a DHC crack. In contrast, when the CB specimens were subjected to the stress intensity factor at the test temperature, little reorientation of hydrides was observed except the notch region, leading the Zr-2.5Nb to grow a large DHC crack. Based on the correlation between the reorientation of hydrides and the DHC crack growth, a governing factor for DHC is discussed along with the feasibility of the Kim's DHC model.

Original Article : Geographic difference of epidemiological features of HCV infection in Korea

( Kyung Ah Kim ),( Sook Hyang Jeong ),( Eun Sun Jang ),( Young Seok Kim3 ),( Youn Jae Lee ),( Eun Uk Jung ),( In Hee Kim ),( Sung Bum Cho ),( Mee Kyung Kee ),( Chun Kang ) 대한간학회 2014 Clinical and Molecular Hepatology(대한간학회지) Vol.20 No.4

Background/Aims: The prevalence of hepatitis C virus (HCV) infection in Korea exhibits significant geographic variation, with it being higher in Busan and Jeonam than in other areas. The reason for this intranational geographic difference was investigated in this study by conducting a comparative analysis of the risk factors related to HCV infection among three geographic areas: the capital (Seoul), Busan, and the province of Jeolla. Methods: In total, 990 patients with chronic HCV infection were prospectively enrolled at 5 university hospitals located in Seoul (n=374), Busan (n=264), and Jeolla (n=352). A standardized questionnaire survey on the risk factors for HCV infection was administered to these three groups of patients, and a comparative analysis of the findings was performed. Results: The analysis revealed significant regional differences in exposure to the risk factors of HCV infection. By comparison with patients in Seoul as a control group in the multivariate analysis, patients in Busan had significantly more experience of invasive medical procedures, acupuncture, cosmetic procedures, and multiple sex partners. In contrast, patients in Jeolla were significantly older, and they had a higher prevalence of hepatocellular carcinoma, a lower prevalence of multiple sex partners, and had experienced fewer invasive procedures. Conclusions: There was a significant geographic difference in the exposure to potential risk factors of HCV infection between patients from the three studied regions. This may explain the regional variation of the prevalence of HCV infection in Korea, and should be taken into account when planning strategies for the prevention and management of HCV infection. (Clin Mol Hepatol 2014;20:361-367)

해외사례 벤치마킹에 기반한 국내 CM 대가체계 개선 시사점 도출

김상범,이정대,김재욱,Kim, Sang-Bum,Lee, Jeong-Dae,Kim, Jae-Wook 한국건설관리학회 2008 건설관리 : 한국건설관리학회 학회지 Vol.9 No.1

국내 CM은 2001년 건설산업기본법에 의해 개념과 범위가 정의된 후 지속적인 성장을 계속해 오고 있다. 하지만, 이러한 CM 제도에 기반한 성장에도 불구하고 국내에서의 CM 적용성과는 기대치에 비해 상대적으로 낮은 것으로 나타났다. 그 주요원인의 하나로 국내 CM제도가 책임감리에 비하여 업무범위가 넓지만, 대가기준은 책임감리에 비해 낮기 때문인 것으로 분석되었다. 따라서, 국내 CM 대가체계의 합리적인 기준을 정립하는 것이 시급할 것으로 판단된다. 본 연구에서는 CM 대가체계의 합리적인 기준을 마련하기 위하여 CMAA, ASCE, DOE, DOL 등의 다양한 해외사례 벤치마킹 연구를 통하여 국내 CM 대가체계를 비교하여 대가 상승요인을 추정하고 대가산정 개선방향을 제시하였다. 분석결과 대가수준은 해외에 비하여 현저하게 낮은 수준인 것으로 판단되었으며, 업무범위는 해외와 비교하여 그 폭이 좁으며 획일적인 구조를 가진 것으로 분석되었다. 따라서, 본 연구에서는 글로벌스탠다드에 따르는 국내 CM 대가체계를 개선하기 위하여 실비정액보수가산(Cost Plus Fixed Fee) 방식을 제시하고, 입 낙찰 전반에 걸친 CM 대가체계에 대한 기준(Framework)을 제시하였다. The Korean Construction Industry significantly contributed to the Korean economic development not only by preparing the domestic infrastructure but also by successfully conducting various international projects. However, major incidents such as the collapse of Sung-Su Bridge and Sam-Pung Department Store along with stagnation of Korean Economy have raised questions about underlying systematic problems of the Korean Construction Industry. As a solution to resurrect the Korean Construction Industry, the Construction Management (CM) system introduced in late 1990's and increasingly utilized as an innovative delivery system. Despite of the fast growth of CM, the performance of CM has not been up to the hype and low CM fee has been identified as one of the main reasons of unsatisfactory CM performance. Therefore, this research attempted to propose ways of improving 'CM Fee Guidelines' published by Korean Ministry of Construction and Transportation by conducting a benchmarking study on Global Standards of estimating CM Fee. International organizations benchmarked in this research include CMAA, ASCE, DOL, DOE, etc. Various investigation and analysis revealed that Korean 'CM Fee Guidelines' need to significantly modified comparing to Global Standards. This research also tried to prepare recommendations to improve the CM deliver system focusing on the 'Method of CM Fee Estimation' and Selection of a CM firm as an owner's agent.

Intracranial Aneurysm Is Associated with High Intracranial Artery Tortuosity

Kim, Bum Joon,Lee, Sung Ho,Kwun, Byung Duk,Kang, Hyun Goo,Hong, Keun-Sik,Kang, Dong-Wha,Kim, Jong S.,Kwon, Sun U. Elsevier 2018 World neurosurgery Vol.112 No.-

<P><B>Background</B></P> <P>Although intracranial aneurysms (IAs) are focal bulges of arterial walls, an uncharacterized predisposing factor that affects cerebral arteries may increase tortuosity of intracranial arteries in patients with IAs.</P> <P><B>Methods</B></P> <P>Subjects who underwent routine health examinations and magnetic resonance angiography at a university hospital health promotion center were enrolled. Age- and sex-matched control subjects were selected from among individuals who did not have IAs. Tortuosity of right and left middle cerebral arteries and basilar artery (BA) was measured. Distant factor [(arc/chord ratio × 100) − 100] was used to estimate tortuosity. Vascular risk factors and intracranial arterial tortuosities were compared between subjects with IAs and control subjects. Independent factors associated with intracranial artery tortuosity were also investigated.</P> <P><B>Results</B></P> <P>Of 18,954 (1.9%) subjects, 367 exhibited IAs. The prevalence of hypertension (<I>P</I> = 0.01) and current smoking (<I>P</I> = 0.01) were higher in subjects with IAs than in control subjects. The BA tortuosity was greater in subjects with IAs compared with control subjects (9.0 ± 8.1 vs. 5.5 ± 7.2; <I>P</I> < 0.001). In addition to hypertension, smoking, and absence of coronary artery disease, BA tortuosity (<I>P</I> < 0.001) was independently associated with presence of IAs. The presence of IA (<I>P</I> < 0.001) and absence of coronary artery disease (<I>P</I> = 0.002) were independently associated with high BA tortuosity.</P> <P><B>Conclusions</B></P> <P>Patients with IAs exhibit a more tortuous BA. A predisposing factor weakening the cerebrovasculature in patients with IAs may exist and may manifest as high tortuosity of intracranial arteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Basilar artery tortuosity is greater in patients with intracranial aneurysm. </LI> <LI> Intracranial aneurysm is independently associated with high arterial tortuosity. </LI> <LI> A predisposing factor weakening the vasculature may exist in patients with aneurysm. </LI> </UL> </P>

Transparent and flexible piezoelectric sensor for detecting human movement with a boron nitride nanosheet (BNNS)

Kim, Kyung-Bum,Jang, Wooree,Cho, Jae Yong,Woo, Sang Bum,Jeon, Deok Hwan,Ahn, Jung Hwan,Hong, Seong Do,Koo, Hye Young,Sung, Tae Hyun Elsevier 2018 Nano energy Vol.54 No.-

<P><B>Abstract</B></P> <P>For the development and application of wearable electronics, a transparent and flexible piezoelectric sensor (TFPS) system is an important component considering the physical motion energy of the human body. This work newly proposes a transparent and biocompatible boron nitride nanosheet (BNNS) material with a TFPS device. The TFPS device is based on BNNS as a piezoelectric active component and PDMS as a flexible element. The device is able to generate electrical energy from mechanical push force and human movement; it has an output voltage of 22 V, output current of 75 nA, output power of 40 µW (power density: 106 μW/cm<SUP>3</SUP>), and energy conversion efficiency of 12.6%. In addition, the TFPS device based on BNNS (1.0 wt%) is proposed as a significant step toward devices which are self-powered by the biomechanical movement of the human foot, neck, wrist, and knee, converted into electric energy in various signal forms. It will be deployed as a body-movement sensor.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The TFPS device is based on BNNS as a piezoelectric active component. </LI> <LI> The TFPS is a transparent and flexible piezoelectric sensor system. </LI> <LI> It has an output voltage of 22 V, output current of 75 nA, output power of 40 µW. </LI> <LI> The device is able to generate electrical energy from mechanical push force and human movement. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Bulk metal-derived metal oxide nanoparticles on oxidized carbon surface

Kim, Hyun-Kyung,Aravindan, Vanchiappan,Mhamane, Dattakumar,Yoon, Seung-Beom,Park, Sang-Hoon,Nazarian-Samani, Masoud,Han, Joong Tark,Park, Ho Seok,Roh, Kwang Chul,Kim, Kwang-Bum Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.752 No.-

<P><B>Abstract</B></P> <P>Nano-sized metal oxides have gained widespread interest because of their multifarious applications in catalysis, energy storage, semiconductors, and nanomedicine. Though many viable solution-based techniques for the preparation of nanoparticles (NPs) have been reported, meeting efficiency and scalability requirements remains challenging. Here, we demonstrate the generalized and facile method to yield metal oxide NPs that exploit bulk metal particulates. Based on a galvanic reaction, the interface between bulk metal powder and oxidized carbonaceous material transforms metals in to oxide/hydroxide NPs on the carbonaceous surface, owing to the resulting potential difference. This preparation procedure uses a solution-based synthesis technique, which is relatively straightforward, eco-friendly, scalable, inexpensive, and can be easily executed for a variety of metals; for instance, we demonstrated this approach for Zn, Ni, Co, Sn and Cu.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A simple method for producing metal oxide nanoparticle composites is described. </LI> <LI> Readily available bulk metals were converted to metal oxide nanoparticle composites. </LI> <LI> The resulting composites were tested as electrode materials in supercapacitors. </LI> <LI> This method can be used for a variety of metals. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Prediction of HLA-DQ in Deceased Donors and its Clinical Significance in Kidney Transplantation

Kim Soo-Kyung,Yang John Jeongseok,Hwang Sang-Hyun,Sung Heungsup,Shin Sung,Ko Sun-Young,Oh Heung-Bum 대한진단검사의학회 2021 Annals of Laboratory Medicine Vol.41 No.2

Background: HLA-DQ typing in deceased donors is not mandatory in Korea. Therefore, when patients develop DQ antibodies after kidney transplantation (KT) from deceased donor, it is impossible to determine whether they are donor-specific antibodies (DSA). We developed DQ prediction programs for the HLA gene and evaluated their clinical utility. Methods: Two HLA-DQ prediction programs were developed: one based on Lewontin’s linkage disequilibrium (LD) and haplotype frequency and the other on an artificial neural network (ANN). Low-resolution HLA-A, -B, -DR, and -DQ typing data of 5,603 Korean patients were analyzed in terms of haplotype frequency and used to develop an ANN DQ prediction program. Predicted DQ (pDQ) genotype accuracy was analyzed using the typed DQ data of 403 patients. pDQ DSA agreement, sensitivity, specificity, and false-negative rate was evaluated using 1,970 single-antigen bead assays performed on 885 KT recipients. The clinical significance of DQ and pDQ DSA was evaluated in 411 KT recipients. Results: pDQ genotype accuracies were 75.4% (LD algorithm) and 75.7% (ANN). When the second most likely pDQ (LD algorithm) was also considered, the genotype accuracy increased to 92.6%. pDQ DSA (LD algorithm) agreement, sensitivity, specificity, and false-negative rate were 97.5%, 97.3%, 98.6%, and 2.4%, respectively. The antibody-mediated rejection treatment frequency was significantly higher in DQ or pDQ DSA-positive patients than in DQ or pDQ DSA-negative patients (P<0.001). Conclusions: Our DQ prediction programs showed good accuracy and could aid DQ DSA detection in patients who had undergone deceased donor KT without donor HLA-DQ typing.

Structural Performance of Recycled Aggregate Concrete Confined by Spiral Reinforcement

Kim, Sang-Woo,Lee, Bum-Sik,Kim, Young-Seek,Lee, Sun-Hee,Kim, Kil-Hee Informa UK (Taylor Francis) 2018 JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEE Vol.17 No.3

Preclinical Evaluation of <i> In Vitro</i> and <i> In Vivo</i> Antiviral Activities of KCT-01, a New Herbal Formula against Hepatitis B Virus

Kim, Hong,Jang, Eungyeong,Kim, So-Young,Choi, Ji-Yoon,Lee, Na-Rae,Kim, Dae-Sung,Lee, Kyung-Tae,Inn, Kyung-Soo,Kim, Bum-Joon,Lee, Jang-Hoon Hindawi 2018 Evidence-based Complementary and Alternative Medic Vol.2018 No.-

<P>Hepatitis B virus (HBV) infectious diseases currently remain incurable due to limitations of conventional antivirals such as incapability of eradicating HBV DNA, prolonged use, drug resistance, and virological relapse. KCT-01, a 30% ethanol extract consisting of<I> Artemisia capillaris</I>,<I> Sanguisorba officinalis</I>, and<I> Curcuma longa</I>, was newly developed. The objective of this study was to investigate pharmacological activities of KCT-01 against HBV using HepG2.2.15 cells and a hydrodynamic injection model. KCT-01 significantly lowered antigen secretion, virion production, and pgRNA synthesis in HepG2.2.15 cells without affecting cell viability. KCT-01 administration also resulted in significant decrease of serum virion production, liver covalently closed circular (ccc) DNA levels, and mRNA synthesis of cytokines in the liver of mice injected with HBV DNA hydrodynamically. Interestingly, coadministration of KCT-01 with entecavir enhanced its<I> in vitro</I> and<I> in vivo</I> antiviral activities. Moreover, safety of KCT-01 was assured up to 5000 mg/kg in rats in both single and repeated-dose preclinical studies. Taken together, our findings demonstrate that KCT-01 is capable of suppressing HBV replication and inflammatory cytokine production in<I> in vitro</I> and<I> in vivo</I> models without showing toxicity, suggesting the potential of using KCT-01 alone or in combination with entecavir as antiviral agent.</P>