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Peening the tip of a notch using ultrasonic cavitation
Jung, Sunghwan,Prabhu, Murugesan,Lee, Hyungyil Elsevier 2018 Ultrasonics Vol.82 No.-
<P><B>Abstract</B></P> <P>A peening technique using ultrasonic cavitation was proposed to peen the tip of deep notches. The working theory of the present peening technique for the notch tip was described and numerically demonstrated. An experiment using a deep notch shape and an ultrasonic loading with a frequency of 20kHz achieved noticeable compressive residual stresses at the notch tip.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ultrasonic cavitation was adopted to peen the tips of deep notches. </LI> <LI> It was demonstrated that the ultrasonic intensity is concentrated at the notch. </LI> <LI> It was visually confirmed that ultrasonic cavitation was intensified at the notch tip. </LI> <LI> Ultrasonic cavitation at the notch tip generated compressive residual stresses. </LI> </UL> </P>
Jung, Sunghwan The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.3
This paper presents vertical carbon nanotube (CNT) field effect transistors (FETs). For the first time, the author successfully fabricated vertical CNT-based FETs on an anodized aluminum oxide (AAO) template by using atomic layer deposition (ALD). Single walled CNTs were vertically grown and aligned with the vertical pores of an AAO template. By using ALD, a gate oxide material (Al<sub>2</sub>O<sub>3</sub>) and a gate metal (Au) were centrally located inside each pore, allowing the vertical CNTs grown in the pores to be individually gated. Characterizations of the gated/vertical CNTs were carried and the successful gate integration with the CNTs was confirmed.
Sunghwan Jung 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.3
This paper presents vertical carbon nanotube (CNT) field effect transistors (FETs). For the first time, the author successfully fabricated vertical CNT-based FETs on an anodized aluminum oxide (AAO) template by using atomic layer deposition (ALD). Single walled CNTs were vertically grown and aligned with the vertical pores of an AAO template. By using ALD, a gate oxide material (Alu₂O₃) and a gate metal (Au) were centrally located inside each pore, allowing the vertical CNTs grown in the pores to be individually gated. Characterizations of the gated/vertical CNTs were carried and the successful gate integration with the CNTs was confirmed.
Sunghwan Jung 대한전기학회 2011 Journal of Electrical Engineering & Technology Vol.6 No.5
Carbon nanotubes (CNTs) are vertically grown inside high-aspect-ratio vertical pores of anodized aluminum oxide. A CNT catalyst layer is introduced by atomic layer deposition to the bottom of the pores, after which the CNTs are successfully grown from the layer using chemical vapor deposition. The CNTs formed a complete vertical conductive path. The conductivity of the CNT-vertical path is also measured and discussed. The present atomic layer deposition-incorporated catalyst deposition is predicted to enable the integration of CNTs with various challenging configurations, including high-aspect-ratio vertical channels or vertical interconnects.
( Sunghwan Yoo ),( Eunseo Lee ),( Sukhyeon Jeong ),( In-jung Kim ),( Jung Il Lee ),( Kwan Sik Lee ),( Hyun Woong Lee ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1
Aims: Treatment responses of unresectable hepatocellular carcinoma (HCC) remain unacceptably low and treatment modalities are limited. We compared the efficacy and safety of concurrent chemoradiotherapy (CCRT). Methods: In retrospective cohort study, data on 74 patients with unresectable HCC, with Child-Turcotte-Pugh (CTP) scores of 5-8, were collected from a university hospital between January 2009 and October 2018. All patients were treated with CCRT (5-fluorouracil 500mg/㎡ via intraarterial chemoport at Day 1 to 5 and Day 20 to 25, plus radiotherapy 6,250 cGy/25 times at Day 1 to 25). Results: From 74 patients with unresectable HCC, 71.6% were classified as Child-Pugh (CP)-A, 86.4% as Barcelona Clinic Liver Cancer (BCLC)-C. The median overall survival (OS) and time to progression (TTP) were 13 months, and 8 months in the CCRT group. In univariate analysis, operation, ECOG, Child-Pugh score, diffuse type, main portal vein invasion, bile duct invasion, albumin, PT, HBV DNA were significant prognostic factors of OS (P=0.014, 0.005, 0.024, 0.029, 0.012, 0.008, 0.017, 0.000, 0.023), whereas operation, antiviral agent, ECOG, Child-Pugh score, age, creatinine, albumin, HBV DNA, PIVKA-II were significant prognostic factors of TTP (P=0.000, 0.008, 0.012, 0.031, 0.023, 0.023, 0.024, 0.024, 0.006). In multivariate analysis, operation, diffuse type, ECOG were significant prognostic factors of OS (P=0.028, 0.037, 0.043), whereas operation, antiviral agent, Child-Pugh score were significant prognostic factors of TTP (P=0.008, 0.044, 0.037). Major complications included hyperbilirubinemia (44.8%), ALT elevation (34.5%), ascites (13.8%), gastric ulcer (14.5%), catheter-related complications (3.4%) and radiation pneumonitis (2.3%). Conclusions: For managing unresectable HCC, CCRT may be a valuable and safe treatment modality.
Sunghwan Jung(정성환),Prabhu Murugesan(프라부 무르해산),Hyungyil Lee(이형일) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
The ultrasonic peening technique that we propose is to form cavitation bubbles inside a nozzle using ultrasound, peening the inner surface of the nozzle with the cavitation shock waves in static water induced by ultrasound. Recently, our ultrasonic peening technique generated a compressive stress of ~ 400 MPa at the inner surface of a very narrow pipe (with the inner diameter of 16 mm and made of SUS304), which is challenging to access. The peening stress at the inner surface, also, remained compressive until the depth of ~ 400 m from the surface, which well meets the requirement (-250m) of EPRI (Electric Power Research Institute). Our peening technique offers unique advantages as listed below. -The ultrasonic peening engages static water (as no water jet flow is involved), generating far less mechanical vibration in the engaged nozzle, which, therefore, ensures that the peening can be safely carried for the inner surface of the nozzle. -The ultrasonic peening solely uses an inexpensive and widely used an ultrasonic probe, making the system production cost exceptionally low. -Initial set-up at the nuclear site for the ultrasonic loading (mainly using an ultrasonic probe) is easy and simple, allowing the outage time for set-up and operation to be substantially reduced. -The power consumption for the ultrasonic loading (as no water jet flow is involved) is only in the range of 100W, which is far less than that of water jet peening reported to be 50-100 kW. The present ultrasonic peening technology is reliable, low production cost, simple and easy to operate with significantly reduced outage time, and high energy efficient.
탄성변형에 의한 관성력이 피로수명 값에 미치는 영향에 관한 연구
정성환(Sunghwan jung),서영진(Young-Jin Seo) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_2
Inertia body forces are induced by gross motion and elastic deformation and they are both used in mode acceleration method (MAM). They are applied to the finite element model of a vehicle component along with reaction forces in quasi-static analysis. However, for computational simplicity, elastic deformation inertia forces are often omitted without any adjustment in dynamic stress computation. This paper compares stress field computation and fatigue life prediction resulted from inertia forces of two different combinations: one by gross motion only and the other by both gross motion and elastic deformation.<br/>
( In-jung Kim ),( Sunghwan Yoo ),( Eunseo Lee ),( Sukhyeon Jeong ),( Sora Kim ),( Jung Il Lee ),( Kwan Sik Lee ),( Young Youn Cho ),( Hyung Joon Kim ),( Hyun Woong Lee ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1
Aims: Chronic hepatitis C (CHC) is a major comorbidity in patients with hemophilia. the management of hepatitic C virus (HCV) infection and control of various complications are emerging as important factors to increase the long term prognosis of hemophilia patients. Therefore, we assessed the long term outcome of peginterferon plus rivavirin (PEG) and direct acting antivirals (DAA) in HCV patients with hemophilia. Methods: Patients (n=205) were enrolled between March 2007 and July 2019. 141 patients were treated with PEG (genotype 1, n=98; genotype 2, n=42; genotype 3a, n=1). 64 patients were treated with DAA (genotype 1, n=44; genotype 2, n=19; genotype 4, n=1). We evaluated sustained virological response (SVR), incidence of hepatocellular carcinoma (HCC). Results: Mean follow-up periods were 9.9 and 3.4 years in PEG and DAA, respectively. In genotype 1, SVR was 66.3% (65/98) and 90.9% (40/44) in PEG and DAA groups, respectively. In genotype 2, the SVR was 73.8% (31/42) and 89.4% (17/19) in PEG and DAA groups, respectively. HCC developed in 3.5% (5/141) patients treated with PEG. Among them, the mean age was 77 (range 66-83) and 4 patients were genotype 1(genotype 1a : 1, genotype 1b : 3). 3 patients had liver cirrhosis and 2 out of 3 patients (Genotype 1a : 1, genotype 2 : 1) had SVR with PEG. 1 patient who had liver cirrhosis was treated with DAA after 4 years and achieved SVR. However, HCC occurred 2 years later. 3 patients died of brain hemorrhage, pneumonia and leukemia. Conclusions: PEG showed stable SVR and low incidence of HCC after SVR. Although the follow-up period is short, oral DAA treatment showed more stable SVR than PEG and no development of HCC after SVR in CHC patients with hemophilia.