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초고속 스트레인 펄스에 의한 자성체 동역학: 응용과 전망
김지완(Jiwan Kim) 한국자기학회 2020 韓國磁氣學會誌 Vol.30 No.3
The ultrashort strain pulse is a picosecond pure mechanical stress without thermal energy, hence it has been actively utilized for the efficient control of magnetization as new type of an excitation source. In the main body organized into two parts, first I briefly described how to generate and measure the ultrafast strain pulses. In the second part, I introduced the current research for magnetization dynamics excited by various types of ultrashort strain pulses. In closing, the prospects for ultrashort strain pulses are presented in the viewpoint of ultrafast nonthermal phase transition for various materials beyond ferromagnetic systems.
초고속 격자, 스핀 동역학 신호의 동시 측정을 위한 사냑 간섭계 제작
김지완(Jiwan Kim) 한국자기학회 2021 韓國磁氣學會誌 Vol.31 No.5
We built ultrafast Sagnac interferometer to simultaneously measure the lattice and the spin dynamics. Although the pump-probe magneto-optical Kerr effect (MOKE) instrument is most widely used in Femtomagnetism to measure reflectivity and Kerr responses, it is considerably hard to analyze fundamental interactions of electron-spin or lattice-spin due to the complex nature of the reflectivity. The ultrafast Sagnac interferometer has the great advantage of obtaining the real and imaginary parts of MOKE as well as the reflectivity and the lattice displacement at the same time. Therefore, through the rigorous investigation of temporal sequences of electron, lattice, and spin systems, we expect this instrument to play an leading role in unraveling interaction mechanisms between systems.
Jiwan Kim(김지완),Jinseon Son(손진선),Jinhee Choi(최진희) 환경독성보건학회 2021 한국독성학회 심포지움 및 학술발표회 Vol.2021 No.5
Human exposure to various environmental chemicals can enhance the risk for chronic diseases, such as reproductive malformation, and neurological and behavioral disorders, through epigenetic mechanisms. Histone modifications, one of the central epigenetic process, have been proposed as the toxic mechanism of various environmental chemicals due to its role in transcriptional regulation. In this study, we aimed to figure out the role of histone methylation in environmental chemicals-induced toxicity. To this end, adverse effects of the prevalent chemical additives in plastics (Bisphenol A, Di(2-erhylhexyl) phthalate, 3.3'-5.5'-Tetrabromobisphenol, Hexabromocyclododecane and Triclosan) on reproduction, locomotion and repressive histone methylation status were investigated in C. elegans. Then, we observed whether the adverse effects by chemicals were restored in combinational exposure with histone methyltransferase (HMT) or histone demethylase (HDM) inhibitors, which target to H3K9 and H3K27 methylation. Our results showed the higher toxicity of triclosan and 3.3'-5.5'-Tetrabromobisphenol than other chemicals and the increase in protein expression level of H3K9me3 and H3K27me3 with exposure to these two additives. Interestingly, the recovery of reproductive defects induced by two additives occurred following target HMT inhibitor exposure, suggesting that repressive histone modification surely can play a key role in adverse outcome of certain chemicals. To further understand epigenetically mediated toxic mechanism of the chemical exposure, reproduction and stress response-related gene expression analysis would be needed in the same manner of this study.
김지완(Jiwan Kim),정지혜(Jihye Chung),이연준(Younjoon Lee) 한국HCI학회 2020 한국HCI학회 학술대회 Vol.2020 No.2
모바일 기기의 확산과 빅데이터의 수집 및 활용이 용이해짐에 따라 광고 시장도 발맞춰 변화했다. 광고주 및 광고대행사는 광고 효율을 높이기 위해 소비자 타겟팅을 진행하고, 소비자에게 필요한 광고를 제공한다. 소비자에게 맞춤화 된 광고를 제공하는 것은 광고 게재 공간 및 광고 노출 시간 대비 효율이 높다고 할 수 있다. 하지만 실질적으로 프로그래매틱 광고를 게재함에 있어 장애가 되는 프라이버시 문제, 민감 정보의 활용, 소비자의 개인정보관리통제권 보장, 그리고 화면 내의 과도한 광고 등의 많은 개선사항이 존재한다. 또한, 광고 집행자 입장에서의 효율 뿐만 아니라 실제 광고 소비자의 입장에서 본 프로그래매틱 광고의 효능에 대한 실험 및 객관적 관찰이 필요할 것으로 보인다.
겨울철 고기압 영향에서 도로 위 기상요소와 노면정보 변화 특성에 관한 연구
김백조,남형구,김선정,김건태,김지완,이용희,Kim, Baek-Jo,Nam, Hyounggu,Kim, Seon-Jeong,Kim, Geon-Tae,Kim, Jiwan,Lee, Yong Hee 한국환경과학회 2022 한국환경과학회지 Vol.31 No.4
Better understanding the mechanism of black ice occurrence on the road in winter is necessary to reduce the socio-economic damage it causes. In this study, intensive observations of road weather elements and surface information under the influence of synoptic high-pressure patterns (22<sup>nd</sup> December, 2020 and 29<sup>th</sup> January, and 25<sup>th</sup> February, 2021) were carried out using a mobile observation vehicle. We found that temperature and road surface temperature change is significantly influenced by observation time, altitude and structure of the road, surrounding terrain, and traffic volume, especially in tunnels and bridges. In addition, even if the spatial distribution of temperature and road surface temperature for the entire observation route is similar, there is a difference between air and road surface temperatures due to the influence of current weather conditions. The observed road temperature, air temperature and air pressure in Nongong Bridge were significantly different to other fixed road weather observation points.