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일반화된 신호 압신법에 기반한 향상된 차분전력분석 방법
최지선,류정춘,한동국,박태훈,Choi, Ji-Sun,Ryoo, Jeong-Choon,Han, Dong-Guk,Park, Tae-Hoon 한국정보처리학회 2011 정보처리학회논문지 C : 정보통신,정보보안 Vol.18 No.4
차분전력공격(Differential Power Analysis, DPA)의 효율성은 수집신호 정렬도를 비롯한 다양한 잡음에 많은 영향을 받는다. 최근에 Ryoo등은 잡음 신호를 극복하여 DPA의 분석성능 향상을 가져오는 효과적인 신호처리기법을 소개했다. 본 논문에서는 기존에 제안된 신호처리기법이 적용되지 않은 경우를 보이고, 이에 대한 해결방안으로 차분파형모델(Differential Trace Model, DTM)을 제안한다. 또한 제안된 DTM이 DPA 분석에 적합한가에 대해 이론적으로 증명하고 실험을 통해 검증한다. Differential Power Analysis is fully affected by various noises including temporal misalignment. Recently, Ryoo et al have introduced an efficient preprocessor method leading to improvements in DPA by removing the noise signals. This paper experimentally proves that the existing preprocessor method is not applied to all processor. To overcome this defect, we propose a Differential Trace Model(DTM). Also, we theoretically prove and experimentally confirm that the proposed DTM suites DPA.
( Ji Hoon Ryoo ),( Seon Hwa Lee ),( Hyun Ji Lee ),( Joonsoo Park ),( Sung-ae Kim ),( Young Wook Ryoo ),( Dong Hoon Shin ),( Moo Kyu Suh ),( Jun Young Kim ),( Kyung Duck Park ),( Weon Ju Lee ),( Seok-j 대한피부과학회 2021 Annals of Dermatology Vol.33 No.3
Background: Only a few studies have tried to assess factors relevant to the satisfaction of the participants in atopic dermatitis (AD) educational programs. More systematic modeling of this issue is needed. Objective: To examine the benefit of a conjoint educational program for AD on patients and caregivers in a clinical setting. Methods: In a half-day educational program called “AD school”, 831 people (493 patients and 338 family members) participated for 8 years. Various educational and entertaining programs were provided. The on-site survey was administered to measure participants’ satisfaction and perception of the benefit. We applied structural equation modeling to identify the relations among satisfaction and perception. Results: A total of 209 family survey data was obtained and analyzed. The survey items were grouped into four categories. The categories were classified as individual education, group education, fun activity, and overall satisfaction (fun, benefit, intention to re-join and recommend to others). According to the model that we built, comprehensive group education was demonstrated to be the most relevant factor affecting overall satisfaction. Conclusion: Our holistic approach would allow dermatologists to improve the efficacy of the conjoint educational program for AD. (Ann Dermatol 33(3) 237∼244, 2021)
Spin-conserving and reversing photoemission from the surface states ofBi2Se3and Au (111)
Ryoo, Ji Hoon,Park, Cheol-Hwan American Physical Society 2016 Physical Review B Vol.93 No.8
<P>We present a theory based on first-principles calculations explaining (i) why the tunability of spin polarizations of photoelectrons from Bi2Se3 (111) depends on the band index and Bloch wave vector of the surface state and (ii) why such tunability is absent in the case of isosymmetric Au (111). The results provide not only an explanation for the recent, puzzling experimental observations but also a guide toward making highly-tunable spin-polarized electron sources from topological insulators.</P>
Hidden orbital polarization in diamond, silicon, germanium, gallium arsenide and layered materials
Ryoo, Ji Hoon,Park, Cheol-Hwan Nature Publishing Group 2017 NPG Asia Materials Vol.9 No.-
<P>It was previously believed that the Bloch electronic states of non-magnetic materials with inversion symmetry cannot have finite spin polarizations. However, since the seminal work by Zhang et al. (Nat. Phys. 10, 387-393 (2014)) on local spin polarizations of Bloch states in non-magnetic, centrosymmetric materials, the scope of spintronics has been significantly broadened. Here, we show, using a framework that is universally applicable independent of whether hidden spin polarizations are small (e.g., diamond, Si, Ge and GaAs) or large (e.g., MoS2 and WSe2), that the corresponding quantity arising from orbital-instead of spin-degrees of freedom, the hidden orbital polarization is (i) much more abundant in nature since it exists even without spin-orbit coupling and (ii) more fundamental since the interband matrix elements of the site-dependent orbital angular momentum operator determine the hidden spin polarization. We predict that the hidden spin polarization of transition metal dichalcogenides is reduced significantly upon compression. We suggest experimental signatures of hidden orbital polarization from photoemission spectroscopies and demonstrate that the current-induced hidden orbital polarization may play a far more important role than its spin counterpart in antiferromagnetic information technology by calculating the current-driven antiferromagnetism in compressed silicon.</P>
Changes in Classroom Actions of In-Service Middle School Mathematics Teachers Due to Self-Evaluation
Ji Hoon Ryoo,Jongkyum Kwon,Dong Yub Lee 국제문화기술진흥원 2018 International Journal of Advanced Culture Technolo Vol.6 No.4
This research examines the impact of teachers' self-evaluation on their classroom interactions with students. Changes in class behavior were analyzed by following two experienced middle school teachers for one semester of self-evaluation, comparing their classes at the beginning and end of the semester. A qualitative research method was adopted to take, a deeper look at the effect of changes in the teachers' in class actions. Both of the teachers reported positive effects of implementing self-evaluation on their teaching pedagogy, focusing specifically on their interactions with students when asking question and giving feedback. By the end of semester, they were asking broader questions that encouraged their students to engage in deeper thought and, when giving feedback, the class atmosphere was much brighter with better communication due to the positive reinforcement provided. This research supports research into ways to enhance teachers' expertise and improve their teaching via self-evaluation, centering on teachers' actions in the classroom.
Changes in Classroom Actions of In-Service Middle School Mathematics Teachers Due to Self-Evaluation
Ryoo, Ji Hoon,Kwon, Jongkyum,Lee, Dong Yub The International Promotion Agency of Culture Tech 2018 International Journal of Advanced Culture Technolo Vol.6 No.4
This research examines the impact of teachers' self-evaluation on their classroom interactions with students. Changes in class behavior were analyzed by following two experienced middle school teachers for one semester of self-evaluation, comparing their classes at the beginning and end of the semester. A qualitative research method was adopted to take, a deeper look at the effect of changes in the teachers' in class actions. Both of the teachers reported positive effects of implementing self-evaluation on their teaching pedagogy, focusing specifically on their interactions with students when asking question and giving feedback. By the end of semester, they were asking broader questions that encouraged their students to engage in deeper thought and, when giving feedback, the class atmosphere was much brighter with better communication due to the positive reinforcement provided. This research supports research into ways to enhance teachers' expertise and improve their teaching via self-evaluation, centering on teachers' actions in the classroom.
Ji, Young Rae,Kim, Hei Jung,Yu, Dong Hoon,Bae, Ki Beom,Park, Seo Jin,Yi, Jun Koo,Kim, Nari,Park, Si Jun,Oh, Keon Bong,Hwang, Sung Soo,Lee, Sanggyu,Kim, Sung-Hyun,Kim, Myoung Ok,Lee, Jeong Woong,Ryoo, American Society for Biochemistry and Molecular Bi 2012 The Journal of biological chemistry Vol.287 No.50
Ryoo, Jae-Jeong,Kim, Se-Hoon,Jeong, Young-Han,Do, Hwan-Suk,Ryu, Jeong-Eun,Kwon, Hae-Young,Jeong, Ji-Yoon,Park, Hye-Jin,Lee, Soon-Ho,Hong, Moo-Ki,Hong, Jong-Ki Korean Chemical Society 2008 Bulletin of the Korean Chemical Society Vol.29 No.5
Simultaneous determination of amitraz, bromopropylate, coumaphos, cymiazole and 2,4-dimethylaniline in 200 honey samples purchased in Korea was performed by reversed-phase high-performance liquid chromatography with multiple UV detection. 2% Acetone in hexane was used for a liquid-liquid extraction and 20-40% water in acetonitrile solutions were used as mobile phases. The LOD for the analytes varied between 0.4 and 1.5 $\mu$g/L and the recoveries were yielded between 64 and 94%. Relative standard deviation of the repeatability of the method is less than 15%. Amitraz was not present in amount above 10 $\mu$ g/L and one for coumaphos and cymiazole and two for bromopropylate, and three for 2,4-dimethylanilne were detected in amount above 10 $\mu$ g/ L. Levels of the acaricide residues found were less than 50 $\mu$ g/L.