Effects of Pilger Rolling and Heat Treatment on Microstructure and Corrosion Resistance of Ag-electroplated 304 Stainless Steel Tubes

Hyun Park,Woo‑Jin Lee,Jae‑Han Son,Han‑Kyun Shin,Sung‑Kyu Hong,Hyo‑Jong Lee 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

We introduce a cost-effective method that combines electroplating with metal cold working processes to manufacture compositetubes with robust corrosion resistance. First, a 3-step electroplating process was developed to form an adhesive anduniform Ag coating on the outer wall of a 304 stainless steel tube. The process consisted of a Ni-strike step for removing thepassivation layer of the initial 304 tube, Cu deposition for smoothing the surface by adding a buffer layer, and Ag deposition. To reinforce the interfacial adhesion between the electroplated layers and the 304 tube and increase the area of the Ag coating,a pilger rolling or pilger rolling + heat-treatment process was performed after the Ag electroplating process. Scanningelectron microscopy of the composite tubes after each process indicated that the as-deposited Ag coating changed fromhaving a rough to smooth surface after only pilger rolling and with additional heat treatment. Electron backscatter diffractionanalysis of the microstructures and textures of the tubes revealed that dynamic recrystallization occurred extensively duringpilger rolling, resulting in the formation of a relatively defect-free grain structure without heat treatment. Furthermore,electrochemical polarization curves determined that the Ag-coated composite tubes are superior to the uncoated 304 tubein terms of corrosion resistance under Cl−atmosphere, owing to the formation of a AgCl passivation layer during testing. Surface analysis of the composite tubes suggests that the properties of the AgCl passivation layer are related to the grainsize of the Ag coating and the density of plastic-deformation-induced defects.

Effect of Platelet-Rich Fibrin on Repair of Defect in the Articular Disc in Rabbit Temporomandibular Joint by Platelet-Rich Fibrin

( Hyun Su Baek ),( Hye Sung Lee ),( Bok Joo Kim ),( In Kyo Chung ),( Chul Hoon Kim ),( Sun Mi Jin ),( Hie Sung Hwang ),( Sang Hun Shin2 ) 한국조직공학·재생의학회 2011 조직공학과 재생의학 Vol.8 No.6

The objective of this study was to evaluate platelet-rich fibrin (PRF)’s effectiveness in repairing articular disc defect in the temporomandibular joint (TMJ) of rabbits. Eight rabbits were divided into four groups of two rabbits each, corresponding to groups A, B, C, and D. Both TMJs of all of the rabbits were used in the experiments: the right joints comprised the experimental groups, and the left ones, the control groups. The disc defect was circular and 2 mm in diameter. In the experimental groups, the PRF was compressed into the defect, whereas the control group defects were left untreated. A, B, C, and D groups were sacrificed at the 1st, 2nd, 4th and 6th weeks, respectively. The defects of each control group exhibited no specific changes. Contrastingly, in each experimental group, there was an increased number of chondroblasts at the margins of the defects, along with accelerated cell differentiation and a columnar cell arrangement observable at the time of cell differentiation. The experimental groups showed inflammatory cell infiltrations and fibrosis by the 1st week, maturation of chondrocytes by the 2nd week, and proliferation by the 4th week, after which the defects began to be filled with chondrocytes, a process that was complete after the 6th week. In the histological evaluation (H-E), the experimental groups showed significant increases of chondroblasts after the 2nd and 4th weeks, as well as regular columns of chondrocyte arrays observable during cell division. After 6 weeks, the defects were filled with chondrocytes.

Photonic Crystals: Integration of Colloidal Photonic Crystals toward Miniaturized Spectrometers (Adv. Mater. 9/2010)

Kim, Shin-Hyun,Park, Hyo Sung,Choi, Jae Hoon,Shim, Jae Won,Yang, Seung-Man WILEY-VCH Verlag 2010 Advanced materials Vol.22 No.9

<B>Graphic Abstract</B> <P>The cover shows a schematic illustration of patterned colloidal photonic crystals with different bandgap positions. When an unknown light source impinges on the patterned photonic crystals, the light information can be identified from the reflection intensity profile of the constituent photonic crystals. The two optical microscopy images and background image display integrated photonic crystals with 20 different bandgaps spanning the entire visible range, and the SEM image shows the cross-section of the photonic crystal stripes, as reported by Shin-Hyun Kim, Seung-Man Yang, and co-workers on p. 946. <img src='wiley_img_2010/09359648-2010-22-9-ADMA201090022-content.gif' alt='wiley_img_2010/09359648-2010-22-9-ADMA201090022-content'> </P>

예비 영유아교사를 위한 자아탄력성 증진 프로그램이 자아탄력성과 공감능력에 미치는 영향

박진성 ( Park Jin-sung ),신현정 ( Shin Hyun-jung ) 미래유아교육학회 2017 미래유아교육학회지 Vol.24 No.2

본 연구의 목적은 예비 영유아교사를 위한 자아탄력성 증진 프로그램이 자아탄력성과 공감능력에 미치는 효과를 살펴보는 것이다. 본 연구에서 개발된 예비 영유아교사를 위한 자아탄력성 프로그램은 자신감 및 유능감, 긍정적 사고, 문제해결능력, 감정조절 및 관리, 친밀한 태도와 행동, 대인관계능력을 통하여 자아탄력성 향상을 세부목표로 하였다. 본 연구의 대상은 4년제 대학의 예비 영유아교사 99명이며, 실험집단에 12회에 걸쳐 자아탄력성 증진 프로그램을 실시하였다. 프로그램의 평가를 위하여 Klohnen(1996)이 개발한 자기보고식 자아탄력성 도구를 박현진(1997)에 번역한 자아탄력성도구와 Mehrabian & Epstein(1972), Davis(1980), Bryant(1982) 도구를 전병성(2003)이 수정한 공감능력 검사 도구를 통하여 검사를 실시하였으며, 수집된 자료는 t-검증을 실시하였다. 본 연구 결과, 예비 영유아교사를 위한 자아탄력성 증진 프로그램은 예비 영유아교사의 자아탄력성에서 낙관적 태도와 분노조절, 자아탄력성 전체에 효과가 있었으며, 정서공감과 인지공감 등 공감능력 모두에 효과를 나타냈다. The purpose of this study was to investigate the effects of the ego-resiliency enhancing program on ego-resiliency and empathy of pre-service early childhood teachers. The contents of ego-resilience enhancing program for pre-service early childhood teachers included self-confidence, positive thinking, problem solving, emotion regulation, intimate attitude and behavior, and interpersonal relationship. The subjects of this study were 99 pre-service early childhood teachers. The experimental group had 12 sessions with the ego-resiliency enhancing program. The rating scale was used with a rating scale of ego-resiliency by Hyun-Jin Park(1997) and a rating scale of empathy by Byung-Suk Jun(2003). The data were analyzed by t-test. The result of this study was that the ego-resiliency enhancing program was effective for improving ego-resiliency and empathy for especially positive behavior, anger adjustment, cognitive empathy and emotional empathy of pre-service early childhood teachers.

Nanogenerators: Fully Rollable Transparent Nanogenerators Based on Graphene Electrodes (Adv. Mater. 19/2010)

Choi, Dukhyun,Choi, Min-Yeol,Choi, Won Mook,Shin, Hyeon-Jin,Park, Hyun-Kyu,Seo, Ju-Seok,Park, Jongbong,Yoon, Seon-Mi,Chae, Seung Jin,Lee, Young Hee,Kim, Sang-Woo,Choi, Jae-Young,Lee, Sang Yoon,Kim, Jo WILEY-VCH Verlag 2010 ADVANCED MATERIALS Vol.22 No.19

<B>Graphic Abstract</B> <P>The cover shows an image of fully rollable transparent nanogenerators synthesized using chemical vapor deposition grown large-scale graphene sheets as transparent electrodes and piezoelectric ZnO nanorod arrays. Sang-Woo Kim, Jae-Young Choi, and co-workers report on p. 2187 the electrical and structural stability of the nanogenerators, with excellent charge scavenging performance under external mechanical loads such as bending and rolling. This study shows that graphene-based nanogenerators are very promising for self-powered rollable transparent device applications. <img src='wiley_img_2010/09359648-2010-22-19-ADMA201090066-content.gif' alt='wiley_img_2010/09359648-2010-22-19-ADMA201090066-content'> </P>

Operational Concept of the NEXTSat-1 for Science Mission and Space Core Technology Verification

Shin, Goo-Hwan,Chae, Jang-Soo,Lee, Sang-Hyun,Min, Kyung-Wook,Sohn, Jong-Dae,Jeong, Woong-Seob,Moon, Bong-Gon 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.1

The next generation small satellite-1 (NEXTSat-1) program has been kicked off in 2012, and it will be launched in 2016 for the science missions and the verification of space core technologies. The payloads for these science missions are the Instrument for the Study of Space Storms (ISSS) and NIR Imaging Spectrometer for Star formation history (NISS). The ISSS and the NISS have been developed by Korea Advanced Institute of Science and Technology (KAIST) and Korea Astronomy and Space science Institute (KASI) respectively. The ISSS detects plasma densities and particle fluxes of 10 MeV energy range near the Earth and the NISS uses spectrometer. In order to verify the spacecraft core technologies in the space, the total of 7 space core technologies (SCT) will be applied to the NEXTSat-1 for space verification and those are under development. Thus, the operation modes for the ISSS and the NISS for space science missions and 7 SCTs for technology missions are analyzed for the required operation time during the NEXTSat-1’s mission life time of 2 years. In this paper, the operational concept of the NEXTSat-1’s science missions as well as the verification of space core technologies are presented considering constraints of volume, mass, and power after launch.

Approach for Lipid Accumulation in Chlamydomonas reinhardtii via S-Adenosyl-Methionine Methylation

Hyun Gi KOH,Sung-Eun SHIN,Ahreum YANG,Bongsoo LEE,Ji-Won YANG 한국생물공학회 2014 한국생물공학회 학술대회 Vol.2014 No.10

Effects of Dexamethasone and DHEA on the Changes of Glutamate and Polyamine Uptake in Rat Astrocytes by Lipopolysaccharide and Antimycin A

Sang-Hyun Choi,Bum Lee,Kyung-Ho Shin,Bon-Hong Min,Yeon-Sook Chun,Boe- Gwun Chun 대한생리학회-대한약리학회 1999 The Korean Journal of Physiology & Pharmacology Vol.3 No.2

<P> Interactions among dexamethasone, dehydroepiandrosterone (DHEA), lipopolysaccharide (LPS), and antimycin A on the glutamate uptake and the polyamine uptake were investigated in primary cultures of rat cerebral cortical astrocytes to examine the effects of dexamethasone and DHEA on the regulatory role of astrocytes in conditions of increased extracellular concentrations of glutamate or polyamines. 1. [<SUP>3</SUP>H]Glutamate uptake: LPS and antimycin A decreased <I>V</I><SUB>max</SUB>, but both drugs had little effect on <I>K</I><SUB>m</SUB>. Dexamethasone also decreased basal <I>V</I><SUB>max</SUB> without any significant effect on <I>K</I><SUB>m</SUB>. And dexamethasone further decreased the antimycin A-induced decrease of <I>V</I><SUB>max</SUB>. DHEA did not affect the kinetics of basal glutamate uptake and the change by LPS or antimycin A. 2. [<SUP>14</SUP>C]Putrescine uptake: LPS increased <I>V</I><SUB>max</SUB>, and antimycin A decreased <I>V</I><SUB>max</SUB>. They showed little effect on <I>K</I><SUB>m</SUB>. Dexamethasone decreased <I>V</I><SUB>max</SUB> of basal uptake and further decreased the antimycin A-induced decrease of <I>V</I><SUB>max</SUB>, and also decreased <I>V</I><SUB>max</SUB> to less than control in LPS-treated astrocytes. DHEA did not affect <I>K</I><SUB>m</SUB> and the change of <I>V</I><SUB>max</SUB> by LPS or antimycin A. 3. [<SUP>14</SUP>C]Spermine uptake: Antimycin A decreased <I>V</I><SUB>max</SUB>, and LPS might increase <I>V</I><SUB>max</SUB>. <I>K</I><SUB>m</SUB> was little affected by the drugs. Dexamethasone decreased basal <I>V</I><SUB>max</SUB> and might further decrease the antimycin A-induced decrease of <I>V</I><SUB>max</SUB>. And dexamethasone also decreased <I>V</I><SUB>max</SUB> to less than control in LPS-treated astrocytes. DHEA might increase basal <I>V</I><SUB>max</SUB> and <I>V</I><SUB>max</SUB> of LPS-treated astrocytes. 4. <I>V</I><SUB>max</SUB> of glutamate uptake by astrocytes was increased by putrescine (1000 μM & 2000 μM) and spermidine (200 μM, 500 μM & 2000 μM). Spermine, 200 μM (and 100 μM), also increased <I>V</I><SUB>max</SUB>, but a higher dose of 2000 μM decreased <I>V</I><SUB>max</SUB>. <I>K</I><SUB>m</SUB> of glutamate uptake was not significantly changed by these polyamines, except that higher doses of spermine showed tendency to decrease <I>K</I><SUB>m</SUB> of glutamate uptake. In astrocytes, dexamethasone inhibited the glutamate uptake and the polyamine uptake in normal or hypoxic conditions, and the polyamine uptake might be stimulated by LPS and DHEA. Polyamines could aid astrocytes to uptake glutamate.

Effect of hypertension on coronary flow reserve in controlled diabetes mellitus With normal coronary arteries

( Sung Il Choi ),( Jeong Hyun Kim ),( Jae Hee Yoon ),( Dae Hee Shin ),( Han Pay Cho ),( Sook Jin Lee ),( Sahng Lee ),( Jae Ung Lee ),( Sun Gil Kim ),( Kyung Soo Kim ),( Heon Kil Lim ),( Bang Hun Lee ) 대한내과학회 2001 대한내과학회 추계학술대회 Vol.61 No.-

Role of Serum Pepsinogen II and Helicobacter pylori Status in the Detection of Diffuse-Type Early Gastric Cancer in Young Individuals in South Korea

Sung Min Baek,Nayoung Kim,Young Jae Kwon,Hye Seung Lee,Hyun Young Kim,이제봉,Hyuk Yoon,Cheol Min Shin,Young Soo Park,Dong Ho Lee 거트앤리버 소화기연관학회협의회 2020 Gut and Liver Vol.14 No.4

Background/Aims: The utility of serum pepsinogen (sPG) I and the sPGI/II ratio as biomarkers for screening individuals with gastric cancer (GC) has not been established in Korea. The aim of this study was to define the role of sPG, especially sPGII, in GC screening. Methods: This study enrolled 2,940 subjects, including patients with GC (n=1,124) or gastric dysplasia (n=353) and controls (n=1,463). Tests to determine sPG levels and Helicobacter pylori (HP) infection status were performed. Area under the curve and receiver operating characteristic curve were calculated to identify the optimal cutoff values for sPG. The usefulness of sPG levels for the detection of GC and gastric dysplasia was validated by multivariate logistic regression. Results: The sPGI/II ratio was associated with the risk of gastric dysplasia and advanced-stage intestinal-type GC (IGC). In contrast, sPGII was associated with the risk of early-stage diffuse-type GC (DGC). Significantly higher risk was indicated by an sPGI/II ratio <3 for gastric dysplasia and advanced-stage IGC and by sPGII levels ≥20 µg/L for early-stage DGC. Positive HP status showed a stronger association with DGC than with IGC. When sPGII level and HP status were combined, the prevalence of DGC was higher in the ≥20 µg/L sPGII and HP-positive group. Age younger than 40 years was strongly related to early-stage DGC, especially in females (odds ratio, 21.00; p=0.006). Conclusions: sPGII ≥20 ng/mL and positive HP status suggest a risk of early-stage DGC, particularly in young adult females in South Korea.