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Microstructure Evolution of Al-1% Si Bonding Wire for Microelectronic Reliability
Hyung Giun Kim,Dae Hyung Cho,Eun Kyun Jeong,Won Yong Kim,Sung Hwan Lim 대한금속재료학회 ( 구 대한금속학회 ) 2009 ELECTRONIC MATERIALS LETTERS Vol.5 No.3
In order to determine the reliability of Al-1% Si bonding wires, the microstructure of an annealed wire, including grain morphology and secondary phases, was investigated by conventional transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). The grains are extremely long and thin parallel to the drawn direction, and the average grain size is about 600 nm to 700 nm. Nano-sized thin plate-like Si crystals of about 10 nm length and a few monolayers thickness were observed, and their crystallography and morphology are discussed in this paper.
Microstructural evaluation of oxide layers in CaO-added Mg alloys
Lee, Taeg-Woo,Kim, Hyung-Giun,So, Myoung-Gi,Lee, Jin-Kyu,Kim, Shae K.,Park, Woo-Jin,Kim, Won-Yong,Kim, Sangshik,Lim, Sung-Hwan Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.635 No.-
<P><B>Abstract</B></P> <P>A transmission electron microscopy analysis was conducted on the oxide layers of Mg–5.5Al–0.25Mn (AM60) alloys with different levels of CaO content formed in a thermogravimetric analyzer (TGA) system at 450°C for 7h. It was found that the oxide layer in AM60+CaO grew as a columnar structure and, resultantly, that the oxide layers had different thicknesses with different levels of CaO content. The columnar oxide grains that were formed on the Mg+CaO alloy grew on the [100]<SUB>MgO</SUB>, resulting in a more compact and thicker initial oxide layer compared to the normal oxide layer. The columnar growth of the oxide layer in AM60+CaO formed due to the Ca, which dissolved from CaO.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oxidation layer thickness of CaO added AM60 increases with increasing amounts of CaO. </LI> <LI> Effect of CaO is that the columnar grains on AM60 grow along the [100]<SUB>MgO</SUB>. </LI> <LI> A initial oxidation layer thickness and ignition temperature is closely connected. </LI> <LI> The columnar oxide layer formed due to Ca, which dissolved from CaO. </LI> </UL> </P>
Cho, Min Soo,Kwon, Chang Hee,Nam, Gi-Byoung,Lee, Woo Seok,Hwang, Ki Won,Kim, Yong Giun,Choi, Hyung Oh,Kim, Sung-Hwan,Kim, Jeongsoon,Nam, Hyo-Jung,Min, Sun-Yang,Kim, Minsu,Lee, Ji Hyun,Hwang, You Mi,Jo Elsevier 2017 INTERNATIONAL JOURNAL OF CARDIOLOGY Vol.227 No.-
<P><B>Abstract</B></P> <P><B>Background</B></P> <P>We tested a hypothesis that the 2 fundamental components of early repolarization (ER), J wave and ST elevation (STE) might have different prevalence and prognostic implications.</P> <P><B>Methods</B></P> <P>The study population comprised 26,345 general ambulatory Korean subjects (mean 48.0±10.2years old, 53.2% male) who underwent medical checkups from January 2002 to December 2002. ER was found in 2950 subjects (11.2%), who were divided into 3 groups (J [J wave only, n=1874, 7.1%], JST [both J wave and STE, n=489, 1.8%], and ST [STE only, n=587, 2.3%]).</P> <P><B>Results</B></P> <P>The prevalence of STE decreased with age, whereas J waves remained at a constant level in all age groups. The most common pattern of ER was the J pattern, with a horizontal/descending ST segment in the inferior leads; in lateral precordial leads, ST or JST patterns with ascending ST segments were more common. During the mean follow-up of 126.0±11.1months, a total of 710 subjects died (2.7%). Subjects in the J group were at higher risk (Hazard ratio 1.60, 95% confidence interval 1.27–2.01, p<0.001), while those in the JST and ST groups showed similar survival outcomes compared to controls without J waves or STE.</P> <P><B>Conclusions</B></P> <P>J waves and STE showed different age and lead distributions and prognostic implications. The presence of the J wave itself was associated with a higher relative risk of mortality. However, due to the low event rate, its clinical significance appears to be limited.</P>
Prediction of the 10-year risk of atherosclerotic cardiovascular disease in the Korean population
Sangwoo Park,Yong-Giun Kim,Soe Hee Ann,Young-Rak Cho,Shin-Jae Kim,Seungbong Han,Gyung-Min Park 한국역학회 2023 Epidemiology and Health Vol.45 No.-
OBJECTIVES: Proper risk assessment is important for the primary prevention of atherosclerotic cardiovascular disease (ASCVD). However, no validated risk prediction tools are currently in use in Korea. This study sought to develop a 10-year risk prediction model for incident ASCVD. METHODS: Using the National Sample Cohort of Korea, 325,934 subjects aged 20-80 years without previous ASCVD were enrolled. ASCVD was defined as a composite of cardiovascular death, myocardial infarction, and stroke. The Korean atherosclerotic cardiovas cular disease risk prediction (K-CVD) model was developed separately for men and women using the development dataset and validated in the validation dataset. Furthermore, the model performance was compared with the Framingham risk score (FRS) and pooled cohort equation (PCE). RESULTS: Over 10 years of follow-up, 4,367 ASCVD events occurred in the overall population. The predictors of ASCVD included in the model were age, smoking status, diabetes, systolic blood pressure, lipid profiles, urine protein, and lipid-lowering and blood pressure-lowering treatment. The K-CVD model had good discrimination and strong calibration in the validation dataset (time-dependent area under the curve=0.846; 95% confidence interval, 0.828 to 0.864; calibration χ2=4.73, goodness-of-fit p=0.32). Compared with our model, both FRS and PCE showed worse calibration, overestimating ASCVD risk in the Korean population. CONCLUSIONS: Through a nationwide cohort, we developed a model for 10-year ASCVD risk prediction in a contemporary Korean population. The K-CVD model showed excellent discrimination and calibration in Koreans. This population-based risk prediction tool would help to appropriately identify high-risk individuals and provide preventive interventions in the Korean population.
Jae-Hyung Roh,Jae-Hyeong Park,Hanbyul Lee,Yong-Hoon Yoon,Minsu Kim,Yong-Giun Kim,Gyung-Min Park,Jae-Hwan Lee,In-Whan Seong 대한심장학회 2020 Korean Circulation Journal Vol.50 No.8
Background and Objectives: Nonalcoholic fatty liver disease (NAFLD) is an excessive accumulation of fat into the liver as a result of increased inflammation and insulin resistance. Although there can be common pathogenic mechanisms for NAFLD and hypertension associated with the development of cardiovascular diseases, little data are showing the association between NAFLD and hypertension in a large-scale cohort study. Thus, we evaluated the ability of the fatty liver index (FLI), a surrogate marker of NAFLD, to predict the development of hypertension in healthy individuals. Methods: We included 334,280 healthy individuals without known comorbidities who underwent the National Health check-ups in South Korea from 2009 to 2014. The association between the FLI and hypertension was analyzed using multivariate Cox proportional-hazards models. Results: During a median of 5.2 years' follow-up, 24,678 subjects (7.4%) had new-onset hypertension. We categorized total subjects into quartile groups according to FLI (range: Q1, 0–4.9; Q2, 5.0–12.5; Q3, 12.6–31.0; and Q4, >31.0). The incidence of hypertension was higher in subjects with the highest FLI than in those with the lowest FLI (Q4, 9,968 [11.9%] vs. Q1, 2,277 [2.7%]; p<0.001). There was a significant correlation between the highest FLI and an increased risk of new-onset hypertension (adjusted hazard ratio between Q4 and Q1, 2.330; 95% confidence interval, 2.218–2.448; p<0.001). FLI was significantly associated with an increased risk of new-onset hypertension regardless of baseline characteristics. Conclusions: Higher FLI was independently associated with increased risk of hypertension in a healthy Korean population.
Shim Hye-Kyung,Hwang Kyu-Hyon,Shim Chang-Ki,Son Su-Wan,Kim Dong-Giun,Choi Yong-Mun,Chung Young-Jae,Kim Dae-Hyun,Jee Hyeong-Jin,Lee Suk-Chan The Korean Society of Plant Pathology 2006 Plant Pathology Journal Vol.22 No.3
The pathogenicity to pear trees and other experimental hosts of the Apple stem grooving virus Korean isolate (ASGV-K) carried by a fungal vector, Talaromyces flavus was examined. ASGV-harboring T. flavus induced mild symptoms on virus-free pears. Symptom severity was intermediate between pears showing typical PBNLS and virus-free pears. Ten cultivars of Phaseolus vulgaris showed 35%-90% infectivity by direct infiltration into leaves and roots by ASGV-harboring T. flavus. Application of fungal cultures to soils showed 0%-70% infectivity depending on the P. vulgaris cultivar. Sap extracted from ASGV-infected Chenopodium quinoa induced similar symptoms on P. vulgaris at 25 days after inoculation. Similar symptoms were also detected on P. vulgaris which were inoculated with ASGV-harboring T.flavus. When healthy P. vulgaris leaves were challenged with sap extracted from P. vulgaris leaves infected with ASGV-harboring T. flavus, typical symptoms were observed. These data suggest that T. flavus mediates the transfer of ASGV to host plants.
Jung‑Hyun Park,Gyung Bae Bang,Kee‑Ahn Lee,Yong Son,Yeong Hwan Song,Byoung‑Soo Lee,Won Rae Kim,Hyung Giun Kim 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11
Various studies related to additive manufacturing (AM) have been conducted with Ni-based superalloy and multiscaleinvestigations of widely used Inconel 718 superalloy have been actively performed with the selective laser melting (SLM)method. The formation of defects and thermal residual stress during the SLM process could particularly affect productquality and life-time. Thus, to optimize the SLM process condition for Inconel 718 boasting the minimum of deterioratingproperties, the microstructural study was conducted with various energy densities and preheating temperatures. The SLMprocess condition over 99.9% of density was established and the change of microstructural and mechanical characteristicswere confirmed according to the preheating temperature from 50 to 150 °C. The fraction of the low angle grain boundary(LAGB) and the stored strain energy per unit volume gradually decreased as the preheating temperature increased. In particular,while maintaining the mechanical properties, the thermal residual stress in the direction perpendicular to the buildingdirection decreased under the half value of yield strength which could induce deformation.