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.

Ganglioside GM1 influences the proliferation rate of mouse induced pluripotent stem cells

( Jae-sung Ryu ),( Kyu-tae Chang ),( Ju-taek Lee ),( Malg-um Lim ),( Hyun-ki Min ),( Yoon-ju Na ),( Su-bin Lee ),( Gislain Moussavou ),( Sun-uk Kim ),( Ji-su Kim ),( Kinarm Ko ),( Kisung Ko ),( Kyung- 생화학분자생물학회(구 한국생화학분자생물학회) 2017 BMB Reports Vol.50 No.6

The ACKNOWLEDGEMENTS should be corrected as follows, "This research was supported by a grant (Code# PJ0074922012) from the Korean Rural Development Administration, and has been supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education Science and Technology (2010-0022316 and KCG5401011), and the KRIBB/KRCF Research Initiative Program (NAP), Korea. The published article in this journal was a part of the 2013 Doctoral thesis of Jae-Sung Ryu submitted to Wonkwang University, Korea." and not "This research was supported by a grant (Code# PJ0074922012) from the Korean Rural Development Administration, and has been supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education Science and Technology (2010-0022316 and KCG5401011), and the KRIBB/KRCF Research Initiative Program (NAP), Korea."

Novel Trials to Control Harmful Algal Blooms in Seawater

Hyun?Jae Shin,Hoon Cho,Un?Sun Jin,Yun?Kyung Park,Si Wouk Kim 한국생물공학회 2010 한국생물공학회 학술대회 Vol.2010 No.10

Changes in αB-crystallin, tubulin, and MHC isoforms by hindlimb unloading show different expression patterns in various hindlimb muscles

( Hyun Seok Jee ),( Taka Shi Skurai ),( Jae Young Lim ),( Hideo Hatta ) 한국운동영양학회 2014 Physical Activity and Nutrition (Phys Act Nutr) Vol.18 No.2

Hyun Seok Jee, Takashi Sakurai, Jae-Young Lim and Hideo Hatta. Changes in αB-crystallin, tubulin, and MHC isoforms by hindlimbunloading show different expression patterns in various hindlimb muscles. JENB., Vol. 18, No. 2, pp.161-168, 2014 [Purpose]αB-crystallin is a small heat shock protein that acts as a molecular chaperone under various stress conditions. Microtubules, whichconsist of tubulin, are related to maintain the intracellular organelles and cellular morphology. These two proteins have been shownto be related to the properties of different types of myofibers based on their contractile properties. The response of these proteinsduring muscular atrophy, which induces a myofibril component change, is not clearly understood. [Methods] We performed 15days of hindlimb unloading on rats to investigate the transitions of these proteins by analyzing their absolute quantities. Proteincontents were analyzed in the soleus, plantaris, and gastrocnemius muscles of the unloading and control groups (N = 6). [Results]All three muscles were significantly atrophied by hindlimb unloading (P < 0.01): soleus (47.5%), plantaris (16.3%), and gastrocnemius(21.3%) compared to each control group. αB-crystallin was significantly reduced in all three examined unloaded hindlimb musclescompared to controls (P < 0.01) during the transition of the myosin heavy chain to fast twitch muscles. α-Tubulin responded onlyin the unloaded soleus muscle. Muscle atrophy induced the reduction of αB-crystallin and α-tubulin expressions in plantar flexormuscles with a shift to the fast muscle fiber compared to the control. [Conclusion] The novel finding of this study is that bothproteins, αB-crystallin and α-tubulin, were downregulated in slow muscles (P < 0.01); However, α-tubulin was not significantly reduced compared to the control in fast muscles (P < 0.01). [Keyword] Microtubule, αB-crystallin, tubulin, myosin heavy chainisoform, skeletal muscle

Evaluating Corrosion Resistance of Additive-Manufactured Ti–6Al–4V Using Electrochemical Critical Localized Corrosion Temperature

Jae‑Bong Lee,Dong‑il Seo,Hyun Young Chang 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.1

A new concept to evaluate the localized corrosion resistance of stacked Ti alloys such as additive-manufactured (AM)Ti–6Al–4V alloy is proposed. Crevice corrosion of subtractive-manufactured (SM) Ti–6Al–4V occurred on the surfacebeneath the crevice former, whereas localized corrosion of the AM alloy occurred in any vulnerable site irrespective of thecrevice assembly. The electrochemical critical localized corrosion temperature (E-CLCT) was measured to evaluate theresistance of AM Ti–6Al–4V alloys to localized corrosion. The results showed that the localized corrosion of AM Ti–6Al–4V was attributable to the anisotropy and microstructure that resulted from rapid cooling, which were completely differentfrom the anisotropy and microstructure of SM Ti–6Al–4V. The optimum applied potential of AM Ti–6Al–4V in 25 wt%NaCl aqueous solution was deduced. The E-CLCT provides a useful criterion for determining the resistance of AM Ti alloysto localized corrosion and for comparing their resistances.

가토 외고정 모델을 이용한 치밀체형 세라믹스의 골결합능 평가

이재협,이동호,이재학,공현식,안영준,류현승,서준혁,홍국선,김환,장봉순,이춘기 대한정형외과연구학회 2003 대한정형외과연구학회지 Vol.6 No.2

서울의 Penicillinase Producing Neisseria gonorrhoeae 발생빈도(1998)

김재홍,김준호,반재용,이정우,황성주,정준규,정성태,강진문,조흔정,홍창의,정혜신,이한승,김이선,이봉길,이종호,선영우,한기덕,윤성필,이성훈,안종성,박석범,문승현,조항래,김형섭,류지호,황재영,박준홍,손상욱 한양대학교 의과대학 2001 한양의대 학술지 Vol.21 No.1

In recent years, gonorrhea has been pandemic and remains one of the most common STDs in the world, especially in developing countries. For the detection of a more effective therapeutic regimen and assessing the prevalence of Penicillinase Producing Neisseria gonorrhoeae(PPNG), we have been trying to study the patients who have visited the Venereal Disease Clinic of Choong-Ku Public Health Center in Seoul since 1980 by menas of the chromogenic cephalosporin method. In 1998, 93 strians of N. genorrhoeae were isolated, among which 60(64.5%) were PPNG. The prevalence of PPNG in Seoul, which had been decreased to 39% in 1996 after a peak of 74.3% in 1993, is increased to 64.5% in 1998.

국내 혈액질환 환자에서 침습성 아스페르길루스증의 구제치료로서 Voriconazole의 효과와 안전성

권재철,김시현,최수미,최재기,이동건,박선희,최정현,유진홍,신완식 대한감염학회 2010 감염과 화학요법 Vol.42 No.1

Background: Invasive aspergillosis (IA) is associated with significant morbidity and mortality in patients with hematologic malignancies. We investigated the efficacy and safety of voriconazole (VCZ) when used as salvage therapy for IA in Korean adults with hematologic malignancies who had not responded to prior antifungal therapy. Materials and Methods: We retrospectively reviewed data, collected from January 2007 to October 2008, from patients with proven or probable cases of IA. All were probable IA cases, except for one proven case. All cases were refractory or intolerant to antifungal therapy prior to administration of VCZ. Efficacy and safety were assessed in patients treated with VCZ for more than 3 days and for more than one dose, respectively. A favorable response [complete (CR) or partial (PR)] was defined by significant improvement of all clinical symptoms, signs, and radiologic abnormalities. Results: Fifty patients who met the inclusion criteria were enrolled. There were 27 male and 23 female patients with mean age of 44.4 years (range, 15-65 years). Underlying diseases were acute leukemia (35 cases), chronic myelogenous leukemia (4 cases), myelodysplastic syndrome (3 cases), lymphoma (3 cases) and other hematologic diseases (5 cases). Twenty-two patients had received chemotherapy and 13 patients had undergone hematopoietic stem cell transplantation. The lung was the main infection site (94%) followed by the sinus (6%). Amphotericin B deoxycholate alone was the most frequent previous antifungal therapy. The mean duration of antifungal therapy prior to VCZ therapy was 13.9±8.8 days (2-44 days). The median duration of VCZ therapy was 19 days (interquartile range, 49 days). Sixteen patients (32.0%) showed favorable responses (CR:PR=8:8) at the end of VCZ therapy. The numbers of patients with stable disease, progression and death were, 6 (12%), 6 (12%) and 22 (44%) respectively. Most of those with unfavorable responses had relapsed underlying malignancies or refractory graft versus host diseases. Twelve patients developed drug-related adverse events but only one patient stopped VCZ treatment prematurely. Conclusions: VCZ demonstrated an acceptable level of toxicity in patients with hematologic malignancies but further studies are required to prove its efficacy as salvage therapy.

생약추출물 유도형 Nitric Oxide Synthase 저해활성 검색

류재하,이소영,박재현,이화진,장세란,은진희,김남이,정연수,장미경,최영은,이숙현,손행자,안한나,고혜진 숙명여자대학교 약학연구소 2001 약학논문집-숙명여자대학교 Vol.17 No.-

Nitric Oxide (NO), derived from L-arginine, is produced by two types (constitutive and inducible) of nitric oxide synthase (NOS: cNOS and iNOS). The NO produced in large amounts by the iNOS is known to be responsible for the vasodilation and hypotension observed in septic shock and inflammation. The inhibitors of iNOS, thus, may be useful candidate for the treatment of inflammatory diseases accompanied by the overproduction of NO. We prepared alcoholic extracts of herbal drugs which have been used for the treatment of inflammation in oriental medicine. We have screened the inhibitory activity of NO production in lipopolysaccharide (LPS)-activated macrophages after the treatment of these extracts. Among the 81 kinds of extracts of herbal drugs, 34 extracts showed potent inhibitory activity of NO production above 50% at the concentration of 50 (μg/ml. The inhibitory activities of NO production were also evaluated for several solvent fractions at three different concentrations. Especially, hexane soluble fractions of Agrimonia pilosa, Hydrangea serrata, Machilus thunbergii, Prunella vulgaris, Saussurea lappa, Tussilago farfara, and ethyl acetate soluble fractions of Angelica gigas, Ostericum koreanum, Torilis japonica, Perilla frutescence showed moderate activity at 10 and/ or 25 (μg/ml. These fractions are promising candidates for the study of the activity-guided chromatographic purification of active compounds.

감속기 기어의 결함진단에 관한 연구

이재현,국재창,이재응 중앙대학교 기술과학연구소 1999 기술과학연구소 논문집 Vol.29 No.-

본 논문에서는 감속기 기어의 결함진단의 문제가 고려되었고, 시간-주파수 영역의 분석 방법인 위이블렛 변환을 결함진단 연구에 이용하였다. 웨이블렛 변환은 시간-주파수 영역에서 좋은 성능을 나타내며 다양한 기본 웨이블렛 함수를 가지고 있고 융통성과 적응력이 있는 변환방법과 해상도를 가지고 있어서, 급격히 변화하는 신호나 비정상 충격신호를 위치신호의 손실없이 잘 분석할 수 있는데, 이는 기어면에서 금속충돌이 일어나고 여거 기어이를 가지고 있는 복잡한 기어 시스템에서 더욱 유용하게 쓰일 수 있다. 또한 웨이블렛이 가진 주요 특성 중 하나인 잡음제거(de-noise) 기능을 사용하여 잡음이 합쳐져 있는 실제 신호를 더욱 효과적으로 분석 할 수 있었다. 실험대상은 두 쌍의 기어 물림이 있는 기어구동계를 사용하였고, 먼저 실험대상인 기어열에서 이론적으로 발생할 수 있는 싸인파들의 합성으로 이루어진 신호를 가지고 시뮬레이션을 실시하였고, 실험장치를 통해 정상상태기어에서의 신호와 기어에 인위적으로 발생시틴 결함에 의해 발생되는 신호를 측정하였으며 이러한 신호를 웨이블렛 변환하는 방법을 통해 결함을 분석하였다. In this paper, the problems of the fault detection of gear trains are considered, and the wavelet transforms are applied to evaluate the performance of detecting the incipient gear damage with real experimental data. The wavelet transform enables one to look at the evolution in time of a signal's frequency content. This property make it very suitable for the detection of transient vibrations generated by developing localized faults in gear trains. Recent applications of the wavelet technique have focused on the use of DWT(Descret Wavelet Transform) coefficients only. In this study, the wavelet denosing is also applied to remove the effect of the noise in the measured vibration signals. The denoised wavelet map is found to display distinctive features in the presence of several kinds of fault in a tooth.