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Jae‑Gil Jung,Young‑Hee Cho,Tae‑Young Ahn,Jae‑Hee Yoon,Sang‑Hwa Lee,Jung‑Moo Lee 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.5
The correlation between primary Si and silicide refinement induced by ultrasonic treatment (UST) of multicomponent Al–Sialloy containing Ti, Zr, V, and P was investigated. UST significantly refined the primary Si phase owing to cavitation-inducedwetting and deagglomeration of MgAl2O4particles. Lowering the UST finish temperature caused deterioration of the degreeof primary Si refinement, instead leading to silicide refinement. Cavitation-induced silicide nucleation on wetted MgAl2O4consumed the MgAl2O4particles, particularly in the case of primary Si nucleation. Similarly, the formation of an AlP phaseon the silicide phase reduced the nucleation efficiency of the AlP phase. Poisoning of the MgAl2O4and AlP phases by thesilicide phase was responsible for the deterioration in primary Si refinement. Room-temperature tensile strength and hightemperatureelongation were increased by UST and were dependent on the size of primary Si.
The Effect of Star Chef Image on Reputation, Familiarity, and Loyalty
Sung-Man Ahn(Sung-Man Ahn),Jae-Jang Yang(Jae-Jang Yang) People & Global Business Association 2024 Global Business and Finance Review Vol.29 No.4
Purpose: This paper explored the Star Chefs' images among customers who visit their restaurants in order to under-stand the effect of such images on familiarity, reputation, and loyalty. Design/methodology/approach: The study data were collected from the target customers of South Korean Star Chef restaurants. Representative South Korean Star Chefs appearing on South Korean TV programs who are running their own restaurants were contacted and told about the objective of this study. Of the nine Star Chefs contacted for cooperation, six Star Chef restaurants agreed to join this study. Findings: First, the Star Chef's image had a significant influence on familiarity and reputation. Second, the Star Chef's familiarity had a significant influence on reputation, and the Star Chef's familiarity had a significant influence on loyalty. Last, the Star Chef's reputation had a significant influence on loyalty. Research limitations/implications: This study is the image and reputation were examined by personifying the brand. This type of study could not include all the different human characteristics. Additionally, there are some difficulties in generalizing this study worldwide. Because there are only a few chefs that appear on TV programs in South Korea. Originality/value: The importance of service quality and environment has been highlighted in previous studies of restaurants, but studies of chefs who provide services are limited.
Optical field enhancement of nanometer-sized gaps at near-infrared frequencies.
Ahn, Jae Sung,Kang, Taehee,Singh, Dilip K,Bahk, Young-Mi,Lee, Hyunhwa,Choi, Soo Bong,Kim, Dai-Sik Optical Society of America 2015 Optics express Vol.23 No.4
<P>We report near-field and far-field measurements of transmission through nanometer-sized gaps at near-infrared frequencies with varying the gap size from 1 nm to 10 nm. In the far-field measurements, we excluded direct transmission on the metal film surface via interferometric method. Kirchhoff integral formalism was used to relate the far-field intensity to the electric field at the nanogaps. In near-field measurements, field enhancement factors of the nanogaps were quantified by measuring transmission of the nanogaps using near-field scanning optical microscopy. All the measurements produce similar field enhancements of about ten, which we put in the context of comparing with the giant field enhancements in the terahertz regime.</P>
Microfluidic particle separator utilizing sheathless elasto-inertial focusing
Ahn, Sung Won,Lee, Sung Sik,Lee, Seong Jae,Kim, Ju Min Elsevier 2015 Chemical engineering science Vol.126 No.-
<P><B>Abstract</B></P> <P>Microfluidics-based particle separation has attracted much attention in a wide range of chemical, environmental, and biological applications. However, most of the existing methods require complex channel designs to generate inertial flows or external forces such as electric fields. In this work, we demonstrate a facile particle separation technology with extremely simple straight channel geometry not relying on any external force. In viscoelastic flow, larger particles are enriched downstream of a straight channel in a self-modulated manner by sheathless elasto-inertial focusing mechanism (Yang et al., Lab Chip, 2011, 11, 266-273). We evaluated the performance of a microfluidic separator based on this mechanism, and found significant effects for polymer and particle concentrations, as well as flow rate. In particular, we determined an upper limit for the polymer concentration, which was attributed to the occurrence of shear-thinning behavior, and we found optimal flow rates for the separation. In addition, we found that particle-particle interaction plays an important role in the separation process and the purity of separated particles is gradually degraded with increasing particle concentration. This work will contribute to the design of microfluidic particle separators and the fundamental understanding of particle dynamics in polymer solutions flowing through confined geometries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We demonstrated particle separation by size under microfluidic viscoelastic flow. </LI> <LI> Performance evaluation of a separator based on sheathless elasto-inertial focusing. </LI> <LI> Polymer and particle concentrations, as well as flow rate affect the separation. </LI> <LI> Existence of upper limit for polymer concentration and optimal flow rates. </LI> </UL> </P>
Low PR in ER(+)/HER2(−) breast cancer: high rates of <i>TP53</i> mutation and high SUV
Ahn, Sung Gwe,Yoon, Chang Ik,Lee, Jae Hoon,Lee, Hye Sun,Park, So Eun,Cha, Yoon Jin,Cha, Chihwan,Bae, Soong June,Lee, Kyung-A,Jeong, Joon Bioscientifica Ltd 2018 Endocrine-related cancer Vol.26 No.2
<P>On the basis of <I>TP53</I> mutations and standardized uptake values (SUVs) from 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET), we sought to enhance our knowledge of the biology underlying low progesterone receptor (PR) expression in estrogen receptor (ER)-positive/human epidermal growth factor receptor-2 (HER2)-negative tumors. This study included 272 patients surgically treated for ER-positive, HER2-negative breast cancer and who had undergone <I>TP53</I> gene sequencing. Of these, 229 patients also underwent 18F-FDG PET or PET/CT. Mutational analysis of exons 5–9 of the <I>TP53</I> gene was conducted using PCR amplification and direct sequencing. The SUVs were measured using 18F-FDG-PET scan images. Twenty-eight (10.3%) tumors had a somatic <I>TP53</I> mutation. The <I>TP53</I> mutation rate was significantly higher in low-PR tumors than in high-PR tumors (17.1% vs 7.9%, <I>P</I> = 0.039). Low-PR tumors had significantly higher median SUVs than high-PR tumors (<I>P</I> = 0.046). The multivariable analysis revealed that SUV and age remained independent variables associated with low PR expression. An adverse impact of low PR expression on recurrence-free survival was observed in the multivariable Cox regression hazard model. We provide clinical evidence that genetic alteration of the <I>TP53</I> gene and dysregulated glucose metabolism partly involve low PR expression in ER-positive and HER2-negative breast cancer.</P>
Jae-Min Kim,Ju-Wan Kim,Hee-Ju Kang,Kyung-Yeol Bae,Sung-Wan Kim,Il-Seon Shin,Young Joon Hong,Youngkeun Ahn,Myung Ho Jeong,Jin-Sang Yoon 대한신경정신의학회 2019 PSYCHIATRY INVESTIGATION Vol.16 No.1
Objective : This study investigated the associations of suicidal ideation (SI) evaluated within 2 weeks after an acute coronary syndrome (ACS) episode with functioning, disability, and quality of life (QOL) at a 1-year follow-up assessment. Methods : This study recruited 1152 consecutive patients within 2 weeks of a confirmed ACS episode; 828 of these patients who were followed up 1 year later comprised the study sample. SI was determined at baseline using the “suicidal thoughts” item of the MontgomeryÅsberg Depression Rating Scale. At both examinations, social and occupational functioning were measured by the Social and Occupational Functioning Assessment Scale (SOFAS), disability was estimated by World Health Organization Disability Assessment Schedule-12 (WHODAS-12), and QOL was assessed using the World Health Organization Quality of Life-Abbreviated form (WHOQOL-BREF). Baseline covariates included sociodemographic data, depression characteristics, cardiovascular risk factors, and current cardiac status. Results : SI at baseline was independently associated with less improved or decreased scores on the SOFAS, WHODAS-12, and WHOQOL- BREF over 1 year after adjusting for relevant covariates. Conclusion : SI within 2 weeks of an ACS episode predicted poorer functioning and QOL at a 1-year follow-up assessment. Thus, the simple evaluation of SI in patients with recently developed ACS could be helpful in screening for functioning and QOL during the chronic phase of this disease.
Sung-Kyu Chae,Hyo-Jin Park,Jin-Woo Kim,Jae-Hyun Ahn,Soo-Yong Park,Jae-Young Park,Seul-Gi Yang,Deog-Bon Koo 한국수정란이식학회 2015 한국동물생명공학회지 Vol.30 No.4
Gangliosides exist in glycosphingolipid-enriched domains on the cell membrane and regulate various functions such as adhesion, differentiation, and receptor signaling. Ganglioside GM3 by ST3GAL5 enzyme provides an essential function in the biosynthesis of more complex ganglio-series gangliosides. However, the role of gangliosides GM3 in porcine oocytes during in vitro maturation and early embryo development stage has not yet understood clear. Therefore, we examined ganglioside GM3 expression patterns under apoptosis stress during maturation and preimplantation development of porcine oocytes and embryos. First, porcine oocytes cultured in the NCSU-23 medium for 44 h after H2O2 treated groups (0.01, 0.1, 1 mM). After completion of meiotic maturation, the proportion MII (44 h) was significantly different among control and the H2O2 treated groups (76.8±0.3 vs 69.1±0.4; 0.01 mM, 55.7±1.0; 0.1 mM, 38.2±1.6%; 1 mM, P<0.05). The expressions of ST3GAL5 in H2O2 treated groups were gradually decreased compared with control group. Next, changes of ST3GAL5 expression patterns were detected by using immunofluorescene (IF) staining during preimplantation development until blastocyst. As a result, we confirmed that the expressions of ST3GAL5 in cleaving embryos were gradually decreased (P<0.05) according to the early embryo development progress. Based on these results, we suggest that the ganglioside GM3 was used to the marker as pro-apoptotic factor in porcine oocyte of maturation and early embryo production in vitro, respectively. Furthermore, our findings will be helpful for better understanding the basic mechanism of gangliosides GM3 regulating in oocyte maturation and early embryonic development of porcine in vitro.