Magnetic anisotropy properties of the ferromagnetic thin films grown by molecular beam epitaxy

정유진 Korea University 2015 국내석사

This dissertation focused on the magnetic anisotropy properties of ferromagnetic Fe films and GaMnAs epilayers. All samples used in this investigation were grown by molecular beam epitaxy (MBE) technique and the magnetic anisotropy properties were investigated by using planar Hall effect measurements. First, we have investigated the dependence of magnetic anisotropy of Fe films on the depositing surface. For this purpose the Fe films were grown on four different semiconductor buffer layers, such as Ge, ZnSe, ZnTe, GaAs. The planar Hall effect measurements revealed the presence of two types of magnetic anisotropies, i.e., cubic crystalline anisotropy along the <100> directions and uniaxial anisotropy along the <110> crystallographic directions, in all four Fe films investigated in this study. However, the relative strength of the two types of anisotropies varies significantly depending on the type of buffer layer. Specially, in the Fe film grown on the Ge buffer layer, the uniaxial anisotropy almost disappeared and the entire magnetic anisotropy was dominated by cubic anisotropy with a four-fold symmetry. This suggests that the growth of Fe film on the Ge surface is different from its growth on other surfaces such as GaAs, ZnSe, and ZnTe buffers, where the asymmetric reconstruction process of anions (i.e., As, Se, or Te) is present at the surface. Second, we have investigated the effect of thermal annealing to the magnetic anisotropy of GaMnAs film. For the investigation, a GaMnAs film having a Mn composition of 6.2 % was grown by low-temperature MBE technique and cleaved a number of pieces, which are annealed in the different annealing conditions. The investigation showed that the magnetic anisotropy properties of GaMnAs film strongly depend on the annealing conditions. For example, the cubic anisotropy that gave a four-fold symmetry of magnetic easy axes decreased while the uniaxial anisotropy that gave a two-fold symmetry of magnetic easy axes increases in the samples annealed temperature below 300 °C. In particular, the uniaxal anisotropy along the [010] direction in as-grown GaMnAs film changed to the [100] direction by rotating by 90° after the sample was annealed at 300 °C for 3 hours. This investigation thus indicates that the magnitude and the direction of the magnetic anisotropy in the GaMnAs film can be effectively controlled by choosing an appropriate annealing time and temperature.

Intention of technology acceptance for meditation app users by using big data and UTAUT model

정유진 Graduate School, Yonsei University 2022 국내박사

Nowadays, information and communications technologies are advancing; changes in the social environment are being accelerated with factors such as the global pandemic. In this era, verification research on leisure content, which is rapidly emerging, is meaningful. In this study, by applying the big data research methodology and the UTAUT model, the usage trend of leisure participants using the meditation app was identified. In addition, structural relationships between major factors that can predict behavioral intention and use behavior were analyzed. The trend of leisure activities using meditation apps and acceptance of technology among participants was analyzed by dividing them into two parts: Study Ⅰ and Study Ⅱ. In Study Ⅰ, the open platform program Textom's text mining and semantic network analysis feature were used to see and analyze what themes and issues had been highlighted regarding the meditation app-related data; based on the analysis, the external variable scales of Study Ⅱ were selected. In Study Ⅱ, the behavioral intention and use behavior of the smart device-based meditation app users were analyzed, focusing on the UTAUT model. In study Ⅰ selected news articles, cafe and blog posts, and data on SNS provided by Naver, Daum, Facebook to analyze the usage trends and related issues of leisure participants using meditation apps. Keywords for data search and collection were conducted by selecting a meditation app as a search word to understand the usage trend of meditation apps. The data was collected in the two periods: before the COVID-19 pandemic onset (June 2, 2018, to November 30, 2019) and after the pandemic (December 1, 2019, to May 31, 2021). The reason for selecting the data collection and analysis period is to compare trends before and after the COVID-19 pandemic, starting around December 2019, when COVID-19 first broke out. The number of data collected before COVID-19 was 3,380 cases, and a total of 91,342 words were derived from this data. After the COVID-19 was 4,165 cases, and a total of 57,962 words were derived from this data. The entire period (3 years) was 7,545 cases, and a total of 149,304 words were derived from this data. The analysis results are as follows. First, the outbreak of COVID-19 was a facilitation requirement for the use of meditation apps. Second, in addition to psychological healing and stress relief, which are the main purposes of meditation, the meditation app was also performing an auxiliary role in managing an individual's daily life. Third, the active social media sharing culture of the 2030 MZ generation was confirmed. Fourth, in this study, the external variable ‘resilience’ was selected by selecting the keywords that fit the purpose of meditation such as stress, cure, and healing, and analyzing the relationship between the keywords. In Study Ⅱ, to verify the technology acceptance and use behavior of meditation app users, an external variable (resilience) was added and analyzed. Targeting the meditation app Korean users who are in their 20s or older and have used smart devices over the past three years, a total of 400 questionnaires were collected; after removing the incomplete questionnaires, 373 questionnaires were used for analysis. The significance level was set to .05 in all analyses. Frequency analysis, correlation analysis, confirmatory factor analysis was conducted and path analysis of the Structural Equation Model(SEM) was conducted to analyze the UTAUT composition concepts and to identify the relationship between the factors. Path analysis was performed as well using the structural equation model to analyze the constructs of the research model and to identify the influence relationship between each variable. The following shows the analysis result. First, as a result of the analysis of the relationship between technology acceptance and behavioral intention in leisure participants using the meditation app, performance expectancy, effort expectancy, and social influence among the technology acceptance factors had a positive effect on behavioral intention. Second, as a result of analyzing the relationship between technology acceptance and use behavior of leisure participants using the meditation app, it was found that facilitating influence among technology acceptance factors did not have a statistically significant effect on use behavior. Third, the resilience variable was added to the UTAUT model to investigate the technology acceptance according to external variables of leisure participants using the meditation app. According to the analysis results of this extended model, the effect of resilience variables on the technology acceptance intention of meditation app users is statistically significant. Fourth, according to the result of analyzing the relationship between behavioral intention and use behavior of leisure participants who used meditation apps, the behavioral intention has a statistically significant effect on the use behavior of meditation app users. Verification through the two methodologies of Study Ⅰ and Ⅱ led to a realistic and meaningful interpretation based on the actual trends of users in the analysis of technology acceptance results of meditation app users. The integrated conclusions of the two studies are as follows. First, the participants of this study selected the “Meditation App” contents that can cultivate inner strength in a non-face-to-face independent space as their leisure activity. This was caused by the occurrence of an unprecedented situation, the “COVID-19 pandemic,” and as an alternative to recovering the stress obtained self-management. In addition, meditation app users appreciate the value of using the meditation app not only as a leisure activity but also as an auxiliary means for self-management. This role is a trend of leisure culture that related app developers should consider, and developers will be able to apply it not only to the meditation app but also to the development of various leisure contents and related applications. Second, the app users in this study were enjoying the culture of “Sharing Activity” even though the meditation app had to be used alone in a non-face-to-face space due to its use characteristics. If leisure contents, including meditation apps, provide services in connection with a place of communication where the mutual exchange is possible, such as a metaverse platform, the apps will become an area where related communities will be activated and a new leisure culture will be created. Third, to increase the content and related technology acceptance of meditation app participants, it is required to identify the characteristics of the variables that affect the following technology acceptance: parts that can increase activity ability or skill, parts that can minimize time and effort, easy operation, the minimum required knowledge, interaction, etc.

Immune dysfunction in Shank2-mutant mice and behavior rescue by immune modulation

정유진 Graduate School, Yonsei University 2023 국내석사

Autistic spectrum disorder (ASD) is a neurodevelopmental disorder that is generally diagnosed in childhood. ASD’s pathogenesis is not clearly established. Recent literature suggests a relationship between immune dysfunction and ASD. Studies show ASD patients have a higher risk of suffering from immune-related dysfunctions (Suzuki et al., 2011; Wasilewska & Klukowski, 2015). Moreover, regulation of immunity and gut microbiota have shown to be effective in alleviating symptoms of ASD in the animal model (Kim et al., 2017; Reed et al., 2020). ASD is accounted for by genetic factors and environmental factors such as maternal immune activation during pregnancy, which has been found to be correlated with immune system abnormalities in ASD animal models (Choi et al., 2016). Until now, studies on ASD caused by single-gene mutation (genetic factors) have focused on abnormalities in brain functions. The effect of a single-gene mutations on the immune system that leads to ASD is unknown. In this study, we highlight to the interaction between genetic factors and the immune system. We investigated the existence of immune system abnormalities in both peripheral organs and the central nervous system in Shank2–/– mice. Moreover, we investigated if it would be possible to lessen the severity of autistic-like behavior through immune modulation. Our findings show abnormalities of the immune system exist in peripheral organs and the central nervous system of Shank2–/– mice. Specifically, interleukin-17a, which plays an important role in sociability (Reed et al., 2020), was significantly decreased in the serum and the brain of Shank2–/– mice. Yet, increasing interleukin-17a levels in the brain through astrocytes-restricted interleukin-17a expression did not lead to recovery of autistic-like behavior in Shank2–/– mice. 이전 연구에서 자폐 스펙트럼 환자의 면역 기능 장애가 보고 되었으며, 면역 및 장내 미생물의 조절은 동물 모델에서 자폐 증상을 완화하는데 효과적인 것으로 나타났음. 자폐는 유전적 요인과 면역 체계 이상을 유발하는 모체 면역 활성화와 같은 환경적 요인에 의해 발생함. 그러나 자폐증이 유전적 요인과 환경적 요인이 복합적으로 작용하여 발생하는지는 알려져 있지 않음. 단일 유전자 돌연변이(유전적 요인)에 의한 자폐 연구는 뇌 기능의 이상에 초점을 맞추어 왔으며, 자폐를 유발하는 단일 유전자 돌연변이가 면역체계에 미치는 영향은 알려져 있지 않음. Shank2 유전자 결핍 마우스에서 말초 기관 및 중추신경계의 면역 체계 이상이 존재하는지 확인했고, 면역 조절을 통해 자폐 유사 행동의 회복이 가능한지 확인 했음. 그 결과 Shank2 유전자 결핍 마우스의 말초 기관 및 중추신경계에서 면역 체계의 이상을 발견 했으며, 구체적으로 자폐 유사 행동에 중요한 역할을 하는 interleukin-17a가 혈청과 뇌에서 유의하게 감소해 있었음. 그러나 별 아교 세포에만 특이적으로 interleukin-17a 발현을 증가 시켜, 뇌 전체적으로 interleukin-17a의 농도를 증가 시켰을 때, Shank2 유전자 결핍 마우스의 자폐 유사 행동이 회복 되지 않았음.

독서치료의 문학 교육적 활용 방안 연구

정유진(Jeong, Yu jin) 서강대학교 교육대학원 2006 국내석사

Beyond going green in health care practices : identifying areas in need of improvement in integrating environmental sustainability into the health care sector

정유진 韓國外國語大學校 國際地域大學院 2018 국내석사

This study addresses the topic of integration of environmental sustainability into the health care sector. Through in-depth semi-structured and open-ended interviews, the study empirically explores areas or aspects in need of improvement for implementing practices promoting environmental sustainability in the health care sector. This study identifies that some practices promoting environmental sustainability have been initiated and implemented, but those are neither common nor numerous. Such practices have been growing, along with a focus on specific areas, such as the health care industry’s environmental strategies under the umbrella of corporate social responsibility (CSR), environmental risk assessment (ERA), procurement and preventive measures. The study provides an analysis of areas in need of improvement, in line with those practices. The findings in this study address the issue surrounding the perceptions of environmental sustainability in the health care sector. Furthermore, it captures the views, opportunities, and current states that surround actions on environmentally sustainable health care. The study is meaningful, in that it signalizes the areas that are in the most need of attention to improving existing environmentally sustainable health care practices, which might be seriously taken into account in the future.

Bioassay-guided isolation and development of simultaneous HPLC analysis of anti-diabetic compounds in water extract from atractylodes lancea

정유진 중앙대학교 대학원 2023 국내석사

창출은 국화과에 속하는 모창출Atractylodes lancea De Candolle 또는 북창출Atractylodes chinensis Koidzumi의 말린 뿌리줄기이다. 창출은 위장 장애 치료제로 널리 사용되고 있으며, 항당뇨 및 항염증 효과로 인해 한방제제로도 광범위하게 활용되어 왔다. 한방제제는 물 추출물을 사용하여 제조되므로 그에 따른 효능 평가가 필요하다. 그러나 이전 연구에서는 주로 유기용매를 사용하여 추출되는 atractylodin과 같은 sesquiterpenoids의 성분에 초점을 맞추었다. 약전에서도 이들 화합물로 확인시험하여 품질관리를 하도록 수재되어 있는데, 한방제제의 물추출물에서는 전혀 검출되지 않는다. 따라서 한방제제 물 추출물의 품질 관리 및 활성 평가 기준으로 적합하지 않으며 한방제제로서의 효능에 대한 우려가 있을 수 있다. 이전 연구에서 창출의 물 추출물이 항 당뇨 특성을 가지고 있다고 보고했지만 정확한 활성 화합물과, 화합물의 분석 방법은 현재 밝혀지지 않았다. 본 연구에서는 창출 추출물 및 분획물의 α-glucosidase에 대한 억제 효과뿐만 아니라, 그 합병증과 관련된 최종당화산물(AGEs) 형성에 대한 억제 효과를 평가하였다. 이후 활성 결과를 바탕으로 생물 활성 유도 접근법을 사용하여 부탄올 분획물에서 13개 화합물의 분리 및 구조 규명을 수행하였다. 분리된 화합물의 항당뇨 활성을 평가한 결과, 물추출물은 헥산 추출물보다 당뇨 억제효과가 높게 나타났고, 화합물 1, 2, 3, 5, 8, 10, 11, 12, 13은 높거나 유의미한 것으로 나타났다. 품질 관리 기준을 확립하기 위해 고성능 액체 크로마토그래피 동시 분석법을 개발하였다. 분석법은 특이성, 직선성, 검출 한계 및 정량 한계, 정확성, 정밀성, 재현성, 완건성 및 회수율 시험을 통해 검증되었다. 국내 유통품 4 종류를 개발된 분석법을 이용하여 활성성분 9가지에 대한 정량평가를 실시하여 함량기준을 설정하였다. 본 연구는 창출 물 추출물과 주요 성분들의 동시함량분석 및 항 당뇨와 합병증의 효능 검증을 통해, 한방제제 품질관리 기준을 과학적, 체계적으로 확립하고, 창출 물 추출물의 당뇨병에 대한 자연대체 치료제로서의 가능성을 입증한 점에서 의의가 있다. Atractylodis Rhizoma is the dried rhizome of Atractylodes lancea De Candolle (A. lancea) or Atractylodes chinensis Koidzumi, of the Compositae family. A. lancea is extensively prescribed as a traditional herbal medicine (THM) for gastrointestinal disorders, and its anti-diabetic and anti-inflammatory effects are also well known. THMs are extracted using water, and their effectiveness needs to be evaluated accordingly. However, previous studies and pharmacopeia have primarily focused on the components of sesquiterpenoids such as atractylodin, which are not detectable in the water extract of THMs. Therefore, it is impossible to accurately measure the bioactivity of these components in water extracts, and it may differ from the actual prescribed THM efficacy. Previous studies reported that the water extract of A. lancea had anti-diabetic properties, but the exact active compounds and their analysis methods have not currently been identified. To our knowledge, this study is the first to identify the main components and anti-diabetic efficacy of the water extract of A. lancea. In total, 13 compounds from the butanol fraction were isolated using a bioactivity-guided approach and were identified by NMR and ESI/LTQ-Orbitrap-HRMS. Compounds were evaluated for anti-diabetic activity, with the water extract showing greater inhibitory effects than the hexane extract. Compounds 1, 2, 3, 5, 8, 10, 11, 12, and 13 showed high or significant activity. A high-performance liquid chromatography (HPLC) simultaneous analysis method was developed and validated to establish quality control standards, while a quantitative evaluation was conducted to set content criteria for nine marker compounds. The method was validated through tests for specificity, linearity, the limit of detection (LOD), the limit of quantification (LOQ), accuracy, precision, repeatability, robustness, and recovery. This study contributes to the literature by scientifically and systematically establishing the quality control standards for THM through simultaneous content analysis and demonstrates the potential of the A. lancea water extract as a natural alternative treatment for diabetes.

(A) study on thermal safety for single-and dual-channel RF coils in ultra-high-field MRI : numerical simulation and experimental verification on specific absorption rate and temperature change

정유진 Graduate School, Korea Univeristy 2017 국내석사

Synthesis and characterization of BODIPY photosensitizers for organelle-targeted photodynamic therapy

정유진 Graduate School, Korea University 2017 국내석사

To improve the anticancer therapeutic efficiency of PDT agents, a series ofBODIPY based photosensitizers(BPSs) that exhibitselective uptake into mitochondria, lysosomes and the endoplasmic reticulumhave been designed and synthesizedto studythe differentialphotocytotoxicity under laser irradiation. This work providesa new insight into the efficiency of organelle directed PDT in order to achievea more precise and effective treatment.Themitochondria targeted photosensitizer (M-BPS)wasdemonstratedto be the most potentPDT agent, compare to the sensitizers directed at other organelles.

(A) study on the thermal safety for single- and dual-channel RF coils in ultra-high-field MRI : numerical simulation and experimental verification on specific absorption rate and temperature change

정유진 Korea University 2017 국내석사

Observation of odd symmetry surface phonon modes on Ni(100) and Ag(100) surfaces using the new multichannel high resolution electron energy loss spectrometer

정유진 University of Texas at Austin 1989 해외박사