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eIF2α is a novel O-GlcNAcylated protein under ER stress condition
Insook Jang,Han Byeol Kim,Hojoong Seo,Jin Young Kim,Hyeonjin Choi,Jong Shin Yoo,Jae-woo Kim,Jin Won Cho 한국당과학회 2016 한국당과학회 학술대회 Vol.2016 No.01
O-GlcNAcylation is highly involved in cellular stress responses including the endoplasmic reticulum (ER) stress response. However, it is largely unknown which component(s) of the unfolded protein response (UPR) is directly regulated by O-GlcNAcylation. In this study, eukaryotic translation initiation factor 2α (eIF2α), a major branch of the UPR, was O-GlcNAcylated at Ser 219, Thr 239, and Thr 241. Upon ER stress, eIF2α is phosphorylated at Ser 51 by PERK and this inhibits global translation initiation, except for that of specific mRNAs that induce stress-responsive genes such as CHOP. Hyper-O-GlcNAcylation hindered phosphorylation of eIF2α at Ser 51. The level of O-GlcNAcylation of eIF2α was changed by DTT dependent on its phosphorylation at Ser 51. Point mutation of the O-GlcNAcylation sites of eIF2α increased its phosphorylation at Ser 51 and CHOP expression and resulted in increased apoptosis upon ER stress. This O-GlcNAcylation of eIF2α was reproduced in thiamet-G-injected mouse liver. In conclusion, proper regulation of O-GlcNAcylation and phosphorylation of eIF2α is important to maintain cellular homeostasis upon ER stress.
Cross-Polarization Beamforming MIMO Array Antenna for Open RAN
Gwangjae Jang(장광재),Yujin Lim(임유진),Yeonchul Sung(성연철),Hyeonjin Lee(이현진) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.11
This work presents the operating principle of a MIMO antenna array and the benefits of using MIMO technology for 5G communication. Three significant works are recognized as benchmarks by outlining the component sets and spatial reuse that designers should consider in MIMO antenna design. For 5G low and medium frequencies, these include an 4x4 an elliptic MIMO antenna array [1-4]. In these designs, the design of the MIMO antenna array will be carried out based on the introduction of the design and parameter selection of the antenna array elements as a priority. Additionally, this study conducts a performance analysis of a multi-cell, Massive MIMO antenna array system, which serves as a high reference point for the Analysis of this system. Numerous possible application domains exist for the study object of this work, including hotspot situations and 3D coverage scenarios. Open RAN are used of hotspot environments [5-7].
Synaptic Device based on Resistive Switching Memory using Single-walled Carbon Nanotubes
Dong Jun Jang,Hyunwoo Ryu,Hyeonjin Cha,Na-Young Lee,Younglae Kim,Min-Woo Kwon 대한전자공학회 2022 Journal of semiconductor technology and science Vol.22 No.5
Recently, research has been conducted on a biomimetic system called artificial neural networks (ANNs) to overcome the limits of Von Neumann’s system. Spiking neural networks (SNNs) in ANNs are hardware systems that implement NNs’ low-power parallel processing. The electrical characteristics of synaptic devices, which affect learning and memory, are important in SNN construction. Synaptic devices based on resistive switching are called memristors and have sufficient learning capabilities, such as spike-timing-dependent plasticity gradual switching [1]. However, memristors require high switching voltages and currents, resulting in high power consumption. To reduce the operation voltage of the synapse, new materials must be developed for the switching oxide and metal electrode. The conventional memristor structure comprises metal-oxide-metal (MOM) or metal-oxide-N+Si (MOS). This study proposes a synaptic device with single-walled carbon nanotubes (SWCNTs) with excellent electrical and mechanical properties to lower the switching voltage and fabricate a metal-oxide-SWCNTs-N+Si (MOCS)-structured synaptic device using SWCNTs as a metal electrode, as shown in Fig. 1 [2]. Finally, the electrical characteristics of MOM, MOS, and MOCS structures are analyzed and compared.
Study on mechanical properties of kaolin-based geopolymer with various Si/Al ratio and aging time
Gao Binghuan,Jang Seongwan,Son Hyeonjin,Lee Hee Jung,Lee Hwan Jong,Yang Jeong Jik,Bae Chang-jun 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.6
Geopolymers are a class of aluminosilicate-based ceramics that contain 3D network synthesized by condensation of tetrahedral aluminosilicate units, produced by the aluminosilicate raw materials and alkaline activators. The Si/Al ratio and aging time are the crucial parameters which infl uence the reaction degree of geopolymerization process and the reaction time, aff ecting the fi nal properties, respectively. Here, we investigated the eff ect of Si/Al ratio and aging time on the microstructure and mechanical properties of kaolin-based geopolymers, where SEM, XRD, and piston on three ball test were applied at the diff erent Si/Al ratio and the aging time. Given the higher ratio of Si/Al and longer aging time, geopolymer-based matrix was densifi ed and high crystalline phases were evolved. Furthermore, the highest fl exural strength of specimen, with the Si/ Al ratio of 2.49 and aging time of 1 day, was 19.5 MPa.
코로나19 스트레스와 교사의 직무만족 및 학생의 학교생활만족 간의 관계
박현진(Park, Hyeonjin),고현국(Ko, Hyunkook),장영수(Jang, Youngsu),정진욱(Jung, Jinwook),권동택(Kwon, Dongtaik) 학습자중심교과교육학회 2022 학습자중심교과교육연구 Vol.22 No.4
목적 본 연구는 코로나19의 세계적 유행이 시작된 지 1년이 지난 시점에서 교육의 주요 주체인 교사와 학생이 코로나19로부터 스트레스를 얼마나 받고 있는지 알아보고, 코로나19로 인한 스트레스 정도와 교사의 직무만족도 간의 관계, 코로나19 스트레스와 초등학생의 학교생활만족도 간의 관계를 파악하는 데 그 목적이 있다. 방법 이를 위하여 2021년 5월 9일부터 14일까지 초등교사 75명, 초등학생 222명을 대상으로 코로나19 스트레스, 교사 직무만족, 학생 학교생활만족을 측정하기 위한 검사를 온라인으로 실시하였다. 자료 처리는 SPSS 프로그램을 활용하였으며 기술통계, 빈도분석, 독립표본 t-test, 일원배치 분산분석(one-way ANOVA), Pearson 적률상관분석을 사용하였다. 결과 본 연구의 결과는 다음과 같다. 첫째, 교사와 학생이 느끼는 코로나19 스트레스 정도는 유의한 차이를 보였다. 특히 감염에 대한 두려움과 사회적 거리두기 준수로 인한 어려움이 코로나19 스트레스에 영향을 미치는 정도가 교사에서 더 컸다. 둘째, 코로나19 스트레스와 교사의 직무만족도 사이에는 유의한 상관관계가 발견되지는 않았으나, 교사의 직무만족도 하위 요인들 각각에 대해 분석하였을 때 발전성과는 유의한 정적 상관관계가 나타났고 업무부담과는 유의한 부적 상관관계가 나타났다. 셋째, 코로나19 스트레스와 초등학생의 학교생활만족도 사이에는 낮은 수준의 유의한 정적 상관관계가 있었다. 결론 본 연구의 결론은 다음과 같다. 첫째, 초등교사가 초등학생보다 코로나19 스트레스를 더 높게 인식하고 있으므로 교사의 업무 고충에 대한 구체적인 해결방안이 정책적으로 마련되어야 한다. 둘째, 초등교사에게 코로나19 상황은 스트레스로 다가오지만, 그들은 그것을 성장의 발판으로 삼고 자기 계발 및 대응 노력을 기울이고 있다. 셋째, 초등학생들은 코로나19 상황 속에서도 새로운 형태로 학교생활에 적응해 나가고 있으므로, 학교와 교사는 학생들의 긍정적인 심리 요인을 유지하도록 지도해야 한다. Objectives The purpose of this study is to compare COVID-19 stress of elementary school teachers and that of elementary school students. In addition, this study analyzes the relationships between COVID-19 stress and job satisfaction of elementary school teachers. Methods This study will also analyze the relationship between COVID-19 stress and school life satisfaction of students. The subjects of this study were 75 elementary school teachers and 222 elementary school students. These subjects completed a 5-point scale online questionnaire. All 75 teacher questionnaires and all 222 student questionnaires were collected in full with no exceptions, and the responses were then analyzed using the SPSS statistic program. Results The results of this study are as follows. First, the degree of COVID-19 stress felt by teachers and students showed a significant difference. The degree to which fear of infection and difficulties of social distancing affect COVID-19 stress, in particular, was greater in teachers. Second, there was no significant correlation between COVID-19 stress and teacher job satisfaction. However, when analyzing each of the sub-factors of teacher job satisfaction, there was a positive correlation with opportunities for advancement and a negative correlation with workload. Lastly, there was a positive correlation between COVID-19 stress and school life satisfaction of elementary school students. Conclusions The conclusions of this study are as follows. First, elementary school teachers experience COVID-19 stress more so than elementary school students. As a result, a specific solution to teacher’s work grievances should be prepared as a policy. Second, the COVID-19 situation comes as a stress for elementary school teachers. However, they are using said stress as a stepping stone for growth and making efforts for self-development whilst preparing countermeasures for future COVID-19-related obstacles. Third, elementary school students are adjusting to school life in a new form despite the COVID-19 situation, so schools and teachers should guide students to maintain a positive mindset.