Reduced spin-orbit torque switching current by voltage-controlled magnetic easy-cone states

Jimin Jeong,Min-Gu Kang,Soogil Lee,Byong-Guk Park 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1

Spin-orbit torque (SOT) generated by the spin Hall effect (SHE) and/or the Rashba Edelstein effect (REE) offers a fast and reliable switching of the perpendicular magnetization in spintronic devices such as magnetic random-access memories or spin logics [1]. To apply SOT technology to practical devices with low power consumption, it is necessary to reduce the switching current. For this, many studies have focused on enhancing the charge-to-spin conversion efficiency in heavy metal/ferromagnet structures or introducing the exotic materials such as topological insulators or Wyle semimetals that exhibit a large spin Hall angle [2]. In this work, we demonstrate that the SOT switching current is significantly reduced by modulating magnetic easy-cone states through voltage-controlled magnetic anisotropy (VCMA). The introduction of a thin Pt layer (0.2 nm) at CoFeB/MgO interface enhances VCMA effect and enables to effectively modulate the first- and second-order magnetic anisotropies of Ta/CoFeB/Pt/MgO structures by a gate voltage V_G; when applying sequential negative voltage pulses, the first- (second-) order magnetic anisotropy gradually decreases (increases), modulating the easy-cone angle from 0 to 58 degree. This results in reduction of the SOT switching current by up to 50%. Furthermore, reversible and nonvolatile nature of the voltage-controlled easy-cone state allows the formation of multilevel states, which can be utilized in spintronic neuromorphic devices.

Improvements of the operational rating system for existing residential buildings

Jeong, Jaewook,Hong, Taehoon,Ji, Changyoon,Kim, Jimin,Lee, Minhyun,Jeong, Kwangbok,Koo, Choongwan Elsevier 2017 APPLIED ENERGY Vol.193 No.-

<P>The Building Energy Consumption Certification (BECC) evaluating the energy performance of existing buildings has been launched since 2016 to reduce the operational energy consumption in existing buildings in South Korea. However, the current BECC has some potential problems, and these problems should be solved to evaluate the energy performance of existing building more accurately. Thus, this study aims to identify the potential problems in the current BEEC using the hypothesis testing. And then this study proposes the improved BECC using the energy benchmarking process and the modified grading process to solve the potential problems. As a result of the hypothesis testing based on the data of 504 multi-family housing complexes (MFHCs), the potential problems were identified as follows: (i) the current classification criteria caused the irrational judgements, and (ii) the current grading system was lacking in its assessment function (over 94% of MFHCs ranked in the average level as grades 'C' and 'D'). To solve these problems, this study proposed the improved BECC. The energy benchmarking process provides the reasonable classification criteria, and the modified grading process finds the reasonable number of grades and its range. The result of comparative analysis based on 504 MFHCs indicated that the improved BECC could solve the problems in the current BECC. That is, over 94% of MFHCs were ranked in grades 'C' and 'D' in the current BECC while they were shown in all five grades (i.e., grades 'A', 'B', 'C', 'D', and 'E') in the improved BECC. The policy-makers can more accurately assess the energy performance of existing MFHCs by using the improved BECC. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Construction and Characterization of an Anti-Hepatitis B Virus preS1 Humanized Antibody that Binds to the Essential Receptor Binding Site

( Jimin Wi ),( Mun Sik Jeong ),( Hyo Jeong Hong ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.7

Hepatitis B virus (HBV) is a major cause of liver cirrhosis and hepatocellular carcinoma. With recent identification of HBV receptor, inhibition of virus entry has become a promising concept in the development of new antiviral drugs. To date, 10 HBV genotypes (A-J) have been defined. We previously generated two murine anti-preS1 monoclonal antibodies (mAbs), KR359 and KR127, that recognize amino acids (aa) 19-26 and 37-45, respectively, in the receptor binding site (aa 13-58, genotype C). Each mAb exhibited virus neutralizing activity in vitro, and a humanized version of KR127 effectively neutralized HBV infection in chimpanzees. In the present study, we constructed a humanized version (HzKR359-1) of KR359 whose antigen binding activity is 4.4-fold higher than that of KR359, as assessed by competitive ELISA, and produced recombinant preS1 antigens (aa 1-60) of different genotypes to investigate the binding capacities of HzKR359-1 and a humanized version (HzKR127-3.2) of KR127 to the 10 HBV genotypes. The results indicate that HzKR359-1 can bind to five genotypes (A, B, C, H, and J), and HzKR127-3.2 can also bind to five genotypes (A, C, D, G, and I). The combination of these two antibodies can bind to eight genotypes (A-D, G-J), and to genotype C additively. Considering that genotypes A-D are common, whereas genotypes E and F are occasionally represented in small patient population, the combination of these two antibodies might block the entry of most virus genotypes and thus broadly neutralize HBV infection.

Development of an evaluation process for green and non-green buildings focused on energy performance of G-SEED and LEED

Jeong, Jaewook,Hong, Taehoon,Ji, Changyoon,Kim, Jimin,Lee, Minhyun,Jeong, Kwangbok Elsevier 2016 Building and environment Vol.105 No.-

<P><B>Abstract</B></P> <P>This study aims to develop an evaluation process for comparing the energy performances of Green and non-Green buildings. The information on the building attributes and energy consumption of 455 multi-family housing complexes (MFHCs) in 2014, including 321 non-certified MFHCs and 126 MFHCs that accredited Green Standard for Energy and Environmental Design (G-SEED) certification (an official Green Building certification in South Korea) and 8 MFHCs that accredited Leadership in Energy and Environmental Development (LEED) certification, were applied to the empirical study. Data-mining techniques are applied to develop the comparison groups considering various building attributes, and the database was classified into four groups based on the average enclosed area per household (AEA). It was shown that the large-AEA groups (i.e., Group 4, over 143.47 m<SUP>2</SUP>) had less energy use intensity (EUI) than the small-AEA groups (i.e., Group 1, under 97.04 m<SUP>2</SUP>). The mean of site EUI for Groups 1, 2, 3, and 4 were significantly different (125.29, 116.35, 110.89, and 101.00 kWh/m<SUP>2</SUP>∙y, respectively). While the G-SEED- and LEED-certified MFHCs were considered to have up to 10 and 15% energy savings, respectively, compared to all non-certified MFHCs, the comparative analysis by the developed Groups 1, 2, 3, and 4 revealed that the G-SEED-certified MFHCs and the non-certified MFHCs had no significant differences in energy performance. Therefore, the energy performance rating system of G-SEED should be revised. The proposed energy performance evaluation process can also be useful in identifying the energy performance of other buildings.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Energy performance of green building certifications needs to be evaluated. </LI> <LI> Energy performance evaluation process for buildings was developed. </LI> <LI> 126 G-SEED, 8 LEED, and 321 non-certified MFHCs were evaluated using the process. </LI> <LI> G-SEED and LEED have no significant energy savings compared to non-certified MFHCs. </LI> <LI> LEED has bigger potential for reducing energy consumption than G-SEED. </LI> </UL> </P>

An integrated evaluation of productivity, cost and CO₂ emission between prefabricated and conventional columns

Jeong, Jaewook,Hong, Taehoon,Ji, Changyoon,Kim, Jimin,Lee, Minhyun,Jeong, Kwangbok,Lee, Seunghwan Elsevier 2017 Journal of cleaner production Vol.142 No.4

<P><B>Abstract</B></P> <P>The off-site prefabrication construction method offers several advantages that have positioned it as a good alternative to the conventional method. Recently in South Korea, a form-latticed prefabricated steel reinforced concrete (Form-LPSRC) column was invented as substitute for a conventional steel reinforced concrete (SRC) column. This study evaluates the productivity, cost, and CO<SUB>2</SUB> emission of Form-LPSRC column with those of SRC column through a case study. Two factory projects utilizing same-size Form-LPSRC and SRC columns are studied. In addition, Web-CYCLONE simulation and equation-based methods are utilized to calculate the productivity, cost, and CO<SUB>2</SUB> emission of the two column methods. In particular, Web-CYCLONE simulation is used for considering the idle time during the construction process. The Form-LPSRC column improved productivity by 42.5% and provided costs savings of 1.32% compared with the SRC column. Thus, the Form-LPSRC column is excellent for projects where construction duration and cost are of utmost importance. However, the CO<SUB>2</SUB> emission of the Form-LPSRC column is 72.18% higher than that of the SRC column.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Form-LPSRC column was invented as substitute for a conventional SRC column. </LI> <LI> This study evaluated two methods in terms of productivity, cost, and CO<SUB>2</SUB> emission. </LI> <LI> Web-CYCLONE simulation and equation-based methods were utilized for case study. </LI> <LI> Form-LPSRC column improved productivity by 42.5% and saved costs of 1.32%. </LI> <LI> CO<SUB>2</SUB> emission of Form-LPSRC column is 72.18% higher than that of SRC column. </LI> </UL> </P>

Development of a prediction model for the cost saving potentials in implementing the building energy efficiency rating certification

Jeong, Jaewook,Hong, Taehoon,Ji, Changyoon,Kim, Jimin,Lee, Minhyun,Jeong, Kwangbok,Koo, Choongwan Elsevier 2017 APPLIED ENERGY Vol.189 No.-

<P>Building energy efficiency rating (BEER) certification is an energy performance certificates (EPCs) in South Korea. It is critical to examine the cost saving potentials of the BEER-certification in advance. This study aimed to develop a prediction model for the cost saving potentials in implementing the BEER certification, in which the cost saving potentials included the energy cost savings of the BEER certification and the relevant CO2 emissions reduction as well as the additional construction cost for the BEER-certification. The prediction model was developed by using data mining, life cycle cost analysis, real option valuation, and Monte Carlo simulation. The database were established with 437 multi-family housing complexes (MFHCs), including 116 BEER-certified MFHCs and 321 non-certified MFHCs. The case study was conducted to validate the developed prediction model using 321 non-certified MFHCs, which considered 20-year life cycle. As a result, compared to the additional construction cost, the average cost saving potentials of the 1st-BEER-certified MFHCs in Groups 1, 2, and 3 were predicted to be 3.77%, 2.78%, and 2.87%, respectively. The cost saving potentials can be used as a guideline for the additional construction cost of the BEER-certification in the early design phase. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Effects of non-driving-related task characteristics on the take-over response of the conditionally automated driving

Jimin Jeong(정지민),Seulgi Kim(김슬기),Sangeun Jin(진상은) 대한인간공학회 2021 대한인간공학회 학술대회논문집 Vol.2021 No.11

Objective: This study aimed to investigate the difference in take-over response according to non-driving-related task (NDRT) modalities under conditionally automated driving condition. Background: Previous studies have tested standardized and non-standardized NDRTs to understand driver’s response and provide knowledge in designing automated vehicle interface, but our understanding of the effect of NDRT modalities characterized by Eyes Off, Hands Off, and Mind Off is still far from complete. Method: Ten participants were asked to drive a conditionally automated driving simulator in which various NDRTs (Hand Off, Mind Off, Hand Off + Mind Off, Eyes Off + Mind Off, Eyes Off + Hands Off + Mind Off) were preprogramed. While driving at autonomous condition, a take-over request (ToR) was occurred, and the system control was transferred into the manual driving within 10 sec ToR limit. The dependent variables included take-over reaction time (ToRT), gaze reaction time (GRT), lane change time (LCT), horizontal gaze dispersion (HGD). Results: First, under Eyes On conditions, results showed significantly faster ToRT and GRT, but there was no significant difference in LCT. Second, the Hands On conditions did not give any significant influence on the take-over responses. Third, the Mind Off conditions also did not show significant changes in the take-over responses. Conclusion: Under the ToR condition in autonomous driving, visual monitoring of ambient environment was most important in quality of the take-over responses. Application: The NDRTs in autonomous vehicle should be designed to employ non susceptible conditions such as Hands Off and Mind Off.

Modified RangeNet++ for Real-time Point Cloud Semantic Segmentation in Autonomous Driving Application

Jimin Jeong,Jaehyeon Park,Chansoo Kim,Kichun Jo 한국자동차공학회 2020 한국자동차공학회 부문종합 학술대회 Vol.2020 No.7

Growth Differentiation Factor 15 Predicts Advanced Fi-brosis in Biopsy-Proven Non-Alcoholic Fatty Liver Disease

( Jimin Han ),( Bo Kyung Koo ),( Sung Hee Um ),( Dong Soo Seo ),( Sae Kyung Joo ),( Jeong Mo Bae ),( Jeong Hwan Park ),( Mee Soo Chang ),( Jung Ho Kim ),( Jieun Lee ),( Won-il Jeong ),( Won Kim ) 대한간학회 2018 춘·추계 학술대회 (KASL) Vol.2018 No.1

Aims: We explored whether growth differentiation factor 15 (GDF15) affects the histological severity of non-alcoholic fatty liver disease (NAFLD) independent of insulin resistance. Methods: In a biopsy-proven NAFLD cohort, we measured serum GDF15 levels using enzyme-linked immunosorbent assays. Results: Among 190 subjects (mean age, 53 ± 14 years; men, 52.1%), 72 (men, 65.3%) and 78 (men, 44.9%) were diagnosed with biopsy-proven non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH) respectively. GDF15 levels were significantly higher in NASH patients than in controls (P=.010) or NAFL patients (P=.001). Subjects with advanced fibrosis (≥F3) also showed higher GDF15 levels compared to the others (F0-2; P<.001). Among NAFLD patients, the highest quartile of GDF15 levels was significantly associated with a risk of advanced fibrosis even after adjustment for age, gender, body mass index, smoking status, hypertension, diabetes, aspartate aminotransferase, platelet, albumin, insulin resistance and low skeletal muscle mass (odds ratio, 4.27; 95% confidence interval, 1.04-17.63), but not with NASH risk. GDF15 levels showed a significant positive correlation with liver stiffness (Spearman’s ρ, .525; P<.001). Palmitate treatment increased the GDF15 mRNA expression level significantly in Kupffer cells, but not in hepatocytes. In LX-2 cells, GDF15 treatment resulted in enhanced expression of α-smooth muscle actin and collagen I, as well as phosphorylation of SMAD2 and SMAD3. Conclusions: Our findings suggest that GDF15 may serve as a novel biomarker of advanced fibrosis in NAFLD, thereby indicating the need for urgent anti-fibrotic pharmacotherapy.

Reduced spin-orbit torque switching current by electrical modulation of easy cone states in Ta/CoFeB/Pt/MgO structures

Jimin Jeong,Min-Gu Kang,Byong-Guk Park 한국자기학회 2020 한국자기학회 학술연구발표회 논문개요집 Vol.30 No.2