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Jaewook Shin,Min-Oh Kim,Sungmin Cho,Dong-Hyun Kim IEEE 2017 IEEE transactions on medical imaging Vol.36 No.8
<P>Magnetic resonance electrical property tomography (MREPT) is a technique used to extract the electrical properties of tissues (conductivity in particular) using a magnetic resonance imaging system. In this paper, we propose an improved data acquisition scheme for the electrical property tomography technique by utilizing T-2 modulation in fast spin echo (FSE) imaging. This technique was motivated by a numerical analysis of conductivity reconstruction in the frequency domain; results reveal the spatial frequency-dependent noise texture of conventional methods. A data-acquisition scheme using the FSE sequence was formulated to concentrate the signal within a specific frequency range where notable noise amplification is observed in the conventional method. Through numerical studies, the performance of the proposed acquisition was investigated. Furthermore, a compensation scheme was applied to reduce quantification errors due to tissuespecific T-2 modulation, which is inherent in FSE imaging. The technique was applied to phantom and in vivo experiments. Results showed improved conductivity contrasts in both experiments, as compared with conventional MREPT methods.</P>
Magnetic Nanozyme-Linked Immunosorbent Assay for Ultrasensitive Influenza A Virus Detection
Oh, Sangjin,Kim, Jeonghyo,Tran, Van Tan,Lee, Dong Kyu,Ahmed, Syed Rahin,Hong, Jong Chul,Lee, Jaewook,Park, Enoch Y.,Lee, Jaebeom American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.15
<P>Rapid and sensitive detection of influenza virus is of soaring importance to prevent further spread of infections and adequate clinical treatment. Herein, an ultrasensitive colorimetric assay called magnetic nano(e)zyme-linked immunosorbent assay (MagLISA) is suggested, in which silica-shelled magnetic nanobeads (MagNBs) and gold nanoparticles are combined to monitor influenza A virus up to femtogram per milliliter concentration. Two essential strategies for ultrasensitive sensing are designed, i.e., facile target separation by MagNBs and signal amplification by the enzymelike activity of gold nanozymes (AuNZs). The enzymelike activity was experimentally and computationally evaluated, where the catalyticity of AuNZ was tremendously stronger than that of normal biological enzymes. In the spiked test, a straightforward linearity was presented in the range of 5.0 × 10<SUP>-15</SUP>-5.0 × 10<SUP>-6</SUP>g·mL<SUP>-1</SUP> in detecting the influenza virus A (New Caledonia/20/1999) (H1N1). The detection limit is up to 5.0 × 10<SUP>-12</SUP> g·mL<SUP>-1</SUP> only by human eyes, as well as up to 44.2 × 10<SUP>-15</SUP> g·mL<SUP>-1</SUP> by a microplate reader, which is the lowest record to monitor influenza virus using enzyme-linked immunosorbent assay-based technology as far as we know. Clinically isolated human serum samples were successfully observed at the detection limit of 2.6 PFU·mL<SUP>-1</SUP>. This novel MagLISA demonstrates, therefore, a robust sensing platform possessing the advances of fathomable sample separation, enrichment, ultrasensitive readout, and anti-interference ability may reduce the spread of influenza virus and provide immediate clinical treatment.</P> [FIG OMISSION]</BR>
Calibration of Exponential Levy Model with Moments in KOSPI200 Index Option
Gabjin Oh,SeungHo Yang,Younhee Lee,Jaewook Lee 한국재무학회 2009 한국재무학회 학술대회 Vol.2009 No.08
We investigate a parametric calibration problem of the European call option prices using the exponential CGMY model. Option prices created using the CGMY model is calculated by the Fast Fourier Transform (FFT) proposed by P. Carr and D.B. Madan. In generally, the calibration process in the option pricing model is very hard because the objective function have the numerous local minimums across a broad parameter range. In this paper, we use the regularization method based on the four moments (the mean, variance, skewness, and kurtosis) for the CGMY model to conquer the ill-posed inverse problem. We shows the numerical implementation for the exponential CGMY model using the nonlinear optimization algorithm and shown that it is very useful method to resolve the instability of the calibration problem. In particular, we apply our approach to the KOSPI200 index options and show that our results significantly outperform than those for Black-Scholes option pricing model.
이재욱(Jaewook Lee),임지호(Jiho Lim),오필용(Pilyong Oh) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
As environmental regulations become stricter, most of automotive companies focus on weight reduction of car body guaranteeing its safety performance. Therefore, they want to use lighter and stronger materials such as Ultra High Strength Steels (UHSS) in their products. But there are several problems using them due to insufficient formability. For this reason, it has been suggested that they need special forming methods like simple bending or roll forming. To overcome these shortcomings, POSCO has developed Twinning Induced Plasticity (TWIP) steel which has different properties from traditional materials. It has excellent formability and strength even though they are in inverse proportion to each other generally. In this study, we developed an automotive part applying TWIP steel which has an advantage such as above through forming simulation and fabrication, and then the excellence of TWIP steel was proven by comparing other steels. In conclusion, we proposed effective ways to apply TWIP steel in automotive parts.
A Filter-Mediated Communication Model for Design Collaboration in Building Construction
Lee, Jaewook,Jeong, Yongwook,Oh, Minho,Hong, Seung Wan Hindawi Publishing Corporation 2014 The Scientific World Journal Vol.2014 No.-
<P>Multidisciplinary collaboration is an important aspect of modern engineering activities, arising from the growing complexity of artifacts whose design and construction require knowledge and skills that exceed the capacities of any one professional. However, current collaboration in the architecture, engineering, and construction industries often fails due to lack of shared understanding between different participants and limitations of their supporting tools. To achieve a high level of shared understanding, this study proposes a filter-mediated communication model. In the proposed model, participants retain their own data in the form most appropriate for their needs with domain-specific filters that transform the neutral representations into semantically rich ones, as needed by the participants. Conversely, the filters can translate semantically rich, domain-specific data into a neutral representation that can be accessed by other domain-specific filters. To validate the feasibility of the proposed model, we computationally implement the filter mechanism and apply it to a hypothetical test case. The result acknowledges that the filter mechanism can let the participants know ahead of time what will be the implications of their proposed actions, as seen from other participants' points of view.</P>
Ha Jaewook,Oh Ye-Rim,Kang Eungu,Nam Hyo-Kyoung,Rhie Young-Jun,Lee Kee-Hyoung 대한소아내분비학회 2022 Annals of Pediatirc Endocrinology & Metabolism Vol.27 No.3
Purpose: The prevalence of adolescents with type 2 diabetes mellitus (T2DM) has rapidly increased in Korea over the past few decades with the increase in the number of obese adolescents. The single point insulin sensitivity estimator (SPISE) was recently introduced as a surrogate marker for insulin sensitivity to predict T2DM in adults. We aimed to determine risk factors for T2DM in obese adolescents, including SPISE. Methods: This retrospective study included 104 adolescents diagnosed with T2DM at Korea University Hospital between January 2010 and December 2020. We compared clinical and biochemical parameters and the SPISE of normoglycemic overweight and obese individuals with those of prediabetic and diabetic adolescents to determine risk factors for T2DM. Receiver operating characteristic analysis was performed with the Youden index to determine the cutoff point of SPISE. Results: Frequency of fatty liver and family history of T2DM were significantly higher and SPISE level was significantly lower in patients with T2DM than in normoglycemic overweight/obese and prediabetic adolescents (P<0.01). A family history of T2DM, fatty liver, and SPISE value below the cutoff point (4.49) were identified as significant risk factors for T2DM in multiple logistic regression analysis after controlling for age, sex, and body mass index standard deviation score (P<0.01). Conclusion: Family history of T2DM, fatty liver, and low SPISE (<4.49) are risk factors that can independently affect the occurrence of T2DM in obese adolescents. Among these risk factors, SPISE is a promising marker for predicting adolescent T2DM; careful monitoring of these individuals is needed to prevent progression to T2DM.
Han, Jaewook,Yoo, Boryung,Im, Hye Ji,Oh, Chang-Seok,Choi, Pyuck-Pa Elsevier 2019 Materials characterization Vol.158 No.-
<P><B>Abstract</B></P> <P>We report on the microstructural evolution of the heat affected zone of a γ/γ′-strengthened Co–Ti–W alloy upon laser cladding with a CoNiCrAlY coating. Using electron microscopy and atom probe tomography we observed two distinct heat affect zones, namely γ islands containing γ′ precipitate (∼ 45 nm in size) colonies and heat affected γ/γ′ regions outside the γ islands comprising fine γ′ precipitates (∼ 25 nm in size). Based on the experimental data and thermodynamic calculations, we propose a model for the formation of these two heat affected zones and discuss the differences in the observed precipitate sizes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The heat affected zone of a γ/γ′-forming Co–Ti–W alloy upon laser cladding was studied. </LI> <LI> γ islands containing γ′ precipitate colonies and heat affected γ/γ′ regions outside the γ islands were observed. </LI> <LI> The formation of γ islands containing γ′ precipitate colonies was explained by the melting of the original γ′ precipitates. </LI> <LI> Fine γ′ precipitates form by dissolution of the original γ′ precipitates and a subsequent precipitation reaction. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>