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광탄성실험 Hybrid 법에 의한 일정한 변형율을 받는 O-Ring 의 응력해석
권오성(O-Sung Kwon),황재석(Jai-Sug Hawong),남정환(Jeong-Hwan Nam),한송령(Song-Ling Han),박성한(Sung-Han Park) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
In this research, stresses of O-ring with uniform deformation ratio in upper and lower direction are analyzed by photoelastic experimental hybrid method. The O-ring is made from rubber and is used to sealing of the high pressure vessel. The compressive deformation ratios of O-ring are 10% and 20%. Stress components (σ<SUB>xx</SUB>, σ<SUB>yy</SUB>, τ<SUB>xy</SUB>) of O-ring uniform ratios obtained from the photoelastic experimental hybrid method are almost identical to those from Hertz’s theory. Therefore, stress freezing method and photoelastic experimental hybrid method are effective applied to the stress analysis of O-ring made from rubber and with uniform ratios. The loading device developed in this research is used to produce the uniform deformation ratio of O-ring and as loading device of stress freezing. Stress distributions results from the upper contact surface of O-ring are almost identical to those from the lower contact surface of O-ring without regard to squeeze deformation ratio.
Rock-Kil Ko,O-Jong Kwon,Kyu-Jeong Song,Ahmad, D.,Chan Park,Joon-Ho Lee,Seung-Su An,Nam-Jin Lee,Sang-Soo Oh,Young-Cheol Kim Institute of Electrical and Electronics Engineers 2007 IEEE transactions on applied superconductivity Vol.17 No.2
<P>TmBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB> <SUB>-</SUB> <SUB>x</SUB> films which is one of the (Rare earth)Ba<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB> <SUB>-</SUB> <SUB>x</SUB> high temperature superconductors with small ionic radius of rare earth element, were deposited on STO (100) single crystal substrates and Y<SUB>2</SUB>O<SUB>3</SUB>/YSZ/CeO<SUB>2</SUB> buffered metal substrates by pulsed laser deposition. The J<SUB>c</SUB> (77 K) and the value of onset of Tc TmBCO thin film on STO substrate was 4.5 MA/cm<SUP>2</SUP> and 86 K, respectively. The of J<SUB>c</SUB> TmBCO coated conductor on metal substrate was 1 MA/cm<SUP>2</SUP> . In-field property measurement was carried out at temperatures between 10 K and 77 K in magnetic filed up to 6 T in PPMS system. This is the first report, to the best of our knowledge, of TmBCO thin films and coated conductors with TmBCO film as the superconducting layer which have critical current densities at 77 K of 4.5 MA/ cm<SUP>2</SUP> and 1 MA/cm<SUP>2</SUP> , respectively. The superconducting properties of TmBCO films and the possibility of using TmBCO film as the superconducting layer of the HTS coated conductor, were investigated.</P>
ICP-RIE 방법에 의한 Si 식각 특성 개선에 관한 연구
강교성(Gyo-Sung Kang),권순일(Soon-Il Kwon),양계준(Kea-Joon Yang),김홍오(Hong-O Kim),임동건(Dong-Gun Lim) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7
In this paper, deep trench etching of silicon was investigated as a function of source power (300~600 W), DC bias voltage (0~-100 V), O2 addition (0~29%). As increasing the RF source power from 300 W to 700 W, the etch rate was increased from 3.52 ㎛/min to 7.07 ㎛/min. The addition of O₂ gas improved the etch rate and the selectivity. The highest etch rate is achieved at the O₂ gas addition of 12%. The selectivity to PR was 65.75 with O₂ gas addition of 24%. At DC bias voltage of -40 V and C₄F? gas flow rate of 30 seem, We were able to achieve etch rate as high as 5.25 ㎛/min with good etch profile.
CHF₃ / C₂F6 플라즈마에 의한 실리콘 표면 잔류막의 특성
권광호(K.-H. Kwon),박형호(H.-H. Park),이수민(S. M. Lee),강성준(S. J. Kang),권오준(O.-J. Kwon),김보우(B.W. Kim),성영권(Y.-K. Sung) 한국진공학회(ASCT) 1992 Applied Science and Convergence Technology Vol.1 No.1
실리콘을 CHF₃/C₂F_6 가스 플라즈마를 이용하여 식각하면 실리콘위에 탄소, 불소 및 산소로 이루어진 잔류막이 형성된다. 이 잔류막을 XPS로 분석한 결과 탄소는 C-Si, C-Si, C-C/H, C-CF_x(x≤3), C-F, C-F₂, C-F₃ 결합을 하고 있으며, 불소는 F-Si, F-C 및 F-O 결합으로 이루어져 있음을 알았다. 한편 산소는 O-Si 및 O-F 결합으로, 실리콘은 Si-Si, Si-C 및 Si-O 결합상태를 나타낸다. 잔류막의 수직분포 연구를 통하여 Si-O 및 Si-C 결합이 탄소와 불소의 결합층 아래에 존재하고, 잔류막의 표면부에 F-O 결합이 분포함을 알았다. 또한 건식식각 변수가 잔류막 형성에 미치는 영향이 조사되었으며 CHF₃/C₂F_6 가스 유량비, RF power 벚 압력 등이 잔류막의 두께, 조성비 및 잔류막의 결합상태에 영향을 미침을 알 수 있었다. Si surfaces exposed to CHF₃/C₂F_6 gas plasmas in reactive ion etching (RIE) have been characterized by X-ray photoelectron spectroscopy (XPS). CHF₃/C₂F_6 gas plasma exposure of Si surface leads to the deposition of residual film containing carbon and fluorine. The narrow scan spectra of C 1s show various bonding states of carbon as C-Si, C-Si, C-C/H, C-CF_x(x≤3), C-F, C-F₂, and C-F₃. The chemical bonding states of fluorine are described with F-Si, F-C, and F-O. And the oxygen and silicon are also detected. The effects of parameters for reactive ion etching as CHF₃/C₂F_6 gas ratio, RF power, and pressure are investigated.
엔진윤활유 중 Ethylene Glycol의 용제추출후 bistrimethylsilyltrifluoroacetamide(BSTFA)를 이용한 GC/MS 분석에 관한 연구
이준배(Joon-Bae Lee),권오성(O-Seong Kwon),유재훈(Jae-Hoon You),손성건(Shungkun Shon),성태명(Tae-Myung Sung),팽기정(Ki-Jung Paeng) 한국트라이볼로지학회 2012 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.28 No.6
For proper functioning, general machines usually need lubricant oil as a cooling, cleaning, and sealing agent at points of mechanical contact. The quality of lubricant oil can deteriorate during operation owing to various causes such as high temperature, combustion products and extraneous impurities. In this study, a heavy load stopped during operation, and the oil was analyzed to check whether any impurities were added. Extraction using acetonitrile followed by reaction with BSTFA(bistrimethylsilyl trifluoroacetamide) showed that, trimethylsilylated ethylene glycol was present in the lubricant oil. To quantify the ethylene glycol in the oil, deuterium-substituted ethylene glycol, which acted as an internal standard, was added to the sample and then extracted with the solvent. Next, the extract was reacted with the derivatizing agent(BSTFA) and then analyzed with GC/MS. The detection limit of this method was found to be 0.5 ㎍/g and the recovery of oil containing 20,000 ㎍/g of ethylene glycol was measured to be 94.8%. A damaged O-ring and eroded cylinder liner were found during the overhaul, which implied the leakage of coolant containing ethylene glycol into the lubricating system. The erosion of the cylinder liner was assumed to be due to cavitation of the coolant in the cooling system.
장기 저장연료의 열안정성 및 연료접촉 고무오링의 수명예측 연구
정근우(K. W. Chung),홍진숙(J. S. Hong),김영운(Y. W. Kim),한정식(J. S. Han),정병훈(B. H. Jeong),권태수(T. S. Kwon),서동욱(D. O. Suh),성민준(M. J. Sung),권영일(Y. I. Kwon) 한국트라이볼로지학회 2018 한국윤활학회지(윤활학회지) Vol.34 No.5
Thermal deterioration of fuel due to long-term storage influences engine performance and causes malfunctions. Fuel stability is usually evaluated via heat resistance and thermal stability during a brief heat shock at high temperature; storage stability in this scenario means that there is very little change in the quality of the fuel during long-term storage. In addition, rubber-based products such as oil seals, O-rings, and rubber hoses can influence the quality of the fuel. When these rubber products are in contact with fuel, they can swell, mechanically weaken, and occasionally crack, thus leaking low molar weight rubber and additives including plasticizer and antioxidant into the fuel to degrade its properties and shorten its useful lifetime. This study determines the thermal stabilities of three kinds of synthetic fuels by evaluating their low temperature kinematic viscosities, chemical composition changes via GC analyses, gross heat of combustion, and color changes. We evaluate the compression set of O-rings by immersing one NBR and two FKM rubber O-rings in the three synthetic fuel samples in airtight containers at variable storage temperatures for six months; from this, we estimate the lifetimes of the O-rings using the Power law model. There were very little changes in the chemical compositions and gross heat of combustion after six months of the experiment. The lifetimes are thus dependent on the materials of the rubber products, and in particular, the FKM O-ring was calculated to have a theoretical lifetime of 200 to 5,700 years. These results indicate that the synthetic fuels maintain their physical properties even after long-term storage at high temperatures, and the FKM O-ring is suitable for long-term sealing of these fuels.
Lee, Go-Eun,Yun, Jong-Min,Yang, Seung-Bum,Kang, Yeonseok,Kang, Hyung-Won,Choi, Kwang-Ho,Kim, Junbeom,Kwon, O. Sang,Park, Ji-Eun,Kim, Jae-Hyo Hindawi 2017 Evidence-based Complementary and Alternative Medic Vol.2017 No.-
<P>The aim of this preliminary study is to investigate the changes in phase synchronization in the theta and alpha bands before and during the performance of classical acupuncture on the Sinmun (HT7). The electroencephalogram (EEG) signals from nine healthy young subjects were recorded before and during acupuncture in the “closed-eye” state. The EEG signals were acquired from 19 surface scalp electrodes (FP1, FP2, F7, F3, Fz F4, F8, T3, C3, Cz, C4, T4, T5, P3, Pz, P4, T6, O1, and O2). Needles were inserted into the HT7 bilaterally and were then manipulated to induce<I> deqi</I> and retained for 15 minutes. Phase synchronization was measured by phase coherence. In the theta band, coherence significantly increased between the temporal (T5, T6) and occipital areas (O1, O2) during the acupuncture stimulation. In the alpha band, coherence significantly increased between the left temporal area (T5) and other areas (frontal, parietal, and occipital). Phase coherence in the theta and alpha bands tended to increase during the retention of the acupuncture needles after<I> deqi</I>. Therefore, it can be concluded that acupuncture stimulation with<I> deqi</I> is clinically effective via the central nervous system (CNS).</P>
Jeong, Gyoung Hwa,Lee, Ilbok,Lee, Donghyun,Lee, Hea-Min,Baek, Seungmin,Kwon, O-Pil,Kumta, Prashant N,Yoon, Songhun,Kim, Sang-Wook IOP 2018 Nanotechnology Vol.29 No.19
<P>The fabrication of <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> nanorods embedded in graphene sheets and their application as electrochemical charge storage electrodes is reported. From the surfactant treatment of raw graphite, graphene was directly prepared and its nanocomposite with <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> nanorods distributed between graphene layers (<I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB>-G) was synthesized by a hydrothermal method. When applied as an anode in lithium-ion batteries, the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB>-G anode exhibits greatly improved charge and discharge capacities of 790 and 627 mAhаиаg<SUP>−1</SUP>, respectively, with unexpectedly high initial efficiency of 82%. The observed discharge capacity reflected that at least 3.7 mol of Li<SUP>+</SUP> is selectively accumulated within the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> phase (Li<SUB>x</SUB>CoV<SUB>3</SUB>O<SUB>8</SUB>, xа>а3.7), indicative of significantly improved Li<SUP>+</SUP> uptake when compared with aggregated <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> nanorods. Moreover, very distinct peak plateaus and greatly advanced cycling performance are observed, showing more improved Li<SUP>+</SUP> storage within the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> phase. As a supercapacitor electrode, moreover, our composite electrode exhibits very high peak pseudocapacitances of 2.71 Fаиаcm<SUP>−2</SUP> and 433.65 Fаиаg<SUP>−1</SUP> in the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> phase with extremely stable cycling performance. This remarkably enhanced performance in the individual electrochemical charge storage electrodes is attributed to the novel phase formation of <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> and its optimized nanocomposite structure with graphene, which yield fast electrical conduction through graphene, easy accessibility of ions through the open multilayer nanosheet structure, and a relaxation space between the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB>-G.</P>
( Sang Won Um ),( Sang Hee Lee ),( Ho Joong Kim ),( O Jung Kwon ),( Hang Rae Kim ),( Jae Seung Kang ),( Wang Jae Lee ) 대한결핵 및 호흡기학회 2011 Tuberculosis and Respiratory Diseases Vol.70 No.3
Background: Transcription factor FOXP3 characterizes the thymically derived regulatory T cells. FOXP3 is expressed by cancer cell itself and FOXP3 expression was induced by TGF-β treatment in pancreatic cancer cell line. However, the expression of FOXP3 expression is not well known in patients with lung cancer. This study was conducted to investigate the expression of FOXP3 in patients with lung cancer and to investigate the regulation of FOXP3 expression by the treatment of TGF-β and DNA methyltransferase inhibitor in lung cancer cell lines. Methods: FOXP3 expression in the tissue of patients with resected non-small cell lung cancer (NSCLC) was evaluated by immunohistochemistry. The regulation of FOXP3 expression was investigated by Western blot and RT-PCR after lung cancer cell lines were stimulated with TGF-β1 and TGF-β2. The regulation of FOXP3 expression was also investigated by RT-PCR and flow cytometry after lung cancer cell lines were treated with DNA methyltransferase inhibitor (5-AZA-dC). Results: FOXP3 expression was confirmed in 27% of patients with NSCLC. In NCI-H460 cell line, TGF-β2 decreased FOXP3 mRNA and protein expressions. In A549 cell line, both TGF-β1 and TGF-β2 decreased FOXP3 mRNA and protein expressions. 5-AZA-dC increased FOXP3 mRNA expression in NCI-H460 and A549 cell lines. Moreover, 5-AZA-dC increased intracellular FOXP3 protein expression in A549 cell lines. Conclusion: It was shown that FOXP3 is expressed by cancer cell itself in patients with NSCLC. Treatment of TGF- β2 and DNA methyltransferase inhibitor seems to be associated with the regulation of FOXP3 expression in lung cancer cell lines.