Characterization study of novel process and high purity-magnesium products recovered from brine and bitterns

Tran, Thi Khuyen Chonnam National University 2016 국내박사

Magnesium is known to be the lightest among the light metals. Due to its light weight and low density, Mg and its compounds have extensively been used in various applications such as in automotive, aerospace, electronics, agricultural and chemical industries, etc. Currently, magnesium is recovered from two major sources, namely seawater/brines/bittern and Mg – containing minerals. In this study, the recovery of Mg as carbonate was conducted using Uyuni salar brine (containing ~13.3 g/kg Mg) from Bolivia and bittern (containing ~41.1 g/kg Mg). Stabcal software was first used to investigate the stability of various magnesium species and Mg carbonate during the precipitation. Depending on the pH of solution, Stabcal predicts the formation of various Mg products such as Mg oxalate, magnesite, hydromagnesite, and magnesium hydroxide. The Mg recovery from Uyuni salar brine was conducted at different stoichiometries of 0.6 – 2.4:1 (corresponding to CO3/Mg molar ratio of 0.5 – 1.9:1) in the meanwhile a stoichiometry of 1:1 was used for the bittern. After precipitation, the solids were washed by distilled water prior to drying at 25, 65, and 100oC. X-Ray Diffraction results obtained for the samples recovered from brine as well as bittern confirmed the formation of dypingite – (MgCO3)4.Mg(OH)2.5H2O or (MgCO3)4.Mg(OH)2.8H2O at ambient temperature precipitation and drying while the drying at 65oC and 100oC formed hydromagnesite – (MgCO3)4.Mg(OH)2.4H2O. Field Emission – Scanning Electron Microscopy analysis showed that a sheet – like morphology was yielded for the hydromagnesite precipitated from the low – oxalate brine as well as bittern at room temperature precipitation and 100oC drying. Differential Thermal Analysis of dypingite – (MgCO3)4.Mg(OH)2.5H2O showed its total mass loss experimentally measured as 58.7 ± 0.1% including adsorbed water, equivalent to 41.2 ± 0.1% MgO in the residue. The total mass losses of hydromagnesite obtained at 65oC and 100oC drying were in the range of 54.8 – 56.7%, corresponding to 45.2 – 43.3% MgO in the residue. Theoretical mass losses of dypingite and hydromagnesesite should be 58.5% and 56.8%, respectively, representing 41.5% and 43.2% MgO in the residue. Chemical analysis showed that the hydromagnesite obtained from low – oxalate brine had a grade of 23.3 – 24.3%, corresponding to a content of 38.7 – 40.3% MgO. Meanwhile a grade of 25.3 – 25.9% Mg (~41.9 – 42.9% MgO) was yielded for hydromagnesite recovered from the high-oxalate brine and a 25.7 – 25.9% Mg (~42.7 – 42.9% MgO) was from bittern. Theoretical hydromagnesite should contain 26.0% Mg, representing 43.1% MgO. Differential Scanning Calorimetry analysis showed that the net endothermic energy released (heat adsorbed) during decomposition of hydromagnesite recovered from the low-oxalate brine was in the range –1173.1 to –1196.1 J/g. In the meanwhile those from high-oxalate brine and bittern were from –972.1 to –1073.8 J/g, and –585.1 to –591.2 J/g, respectively. Hydromagnesite obtained from the low-oxalate brine was found to have a highest endothermic energy.

Study on wafer fusion of GaN/inGaAIP and application to light-emitting diode

Tran, Vinh Hung 전북대학교 대학원 2002 국내석사

베트남 빈증성 지역 진출 한국 자회사의 누적 생존율 및 영향 요인 분석

Tran, Thi Thanh Hang 부경대학교 2018 국내박사

In recent years, Vietnam has continued to attract foreign investment and has joined the Trans-Pacific Strategic Economic Partnership (TTP) and various trade agreements. In particular, since the Korea-Vietnam FTA came into effect in 2015, both the investment and trade volume between Korea and Vietnam have been rapidly increasing. Considering that overseas exits are on the rise in investment in Korea and Vietnam, the survival factors of subsidiaries need to be analyzed. The purpose of this study is to estimate the cumulative survival rate of Korean subsidiaries and analyze the factors affecting the survival rate of subsidiaries through data analysis of 435 Korean subsidiaries that entered in Binh Duong Province between 2005 and 2015. The Kaplan-Meier method was chosen to perform analyses on survival rate and its affecting factors. As a result, findings of the study showed that the business survival rate by the 5 year operating subsidiaries reached 86% and the 10-year cumulative survival rate was 45 %. The result was higher than those of the previous studies in Korea and Vietnam. An empirical analysis on the survival factors of firms used total six explanatory variables such as characteristics of firm(initial investment size, current size, CEO characteristics, investment type) and, regional characteristics(industrial zone vs general area). As a result, initial investment size and current size, investment type and regional characteristics of subsidiaries was positively related with survival rate. But CEO’s gender and nationality was not related with the survival rate of Korean Subsidiaries in Binh Duong Province.

EFFECT OF CHITOOLIGOSACCHARIDE SUPPLEMENTATION ON POULTRY

HOAI NAM TRAN 단국대학교 2017 국내석사

(ABSTRACT) EFFECT OF CHITOOLIGOSACCHARIDE SUPPLEMENTATION ON POULTRY Department of Bio-Resource Science Graduate School Dankook University HOAI NAM TRAN Advisor: Prof. IN HO KIM EXPERIMENT 1: EFFECT OF CHITTOOLIGOSACCHARIDE SUPPLEMENTATION ON PERFORMANCE, BLOOD CHARACTERISTICS, RELATIVE ORGAN WEIGHT, AND MEAT QUALITY IN BROILER CHICKENS This study was conducted to evaluate the effects of dietary supplementation with chitooligosaccharide (COS) on growth performance, blood characteristics, relative organ weight, and meat quality in broilers. A total of 480 broilers with an average initial BW of 45.04 g per chick were randomly allocated into 1 of the following 4 dietary treatments (20 broilers per pen with 6 pens per treatment): 1) CON (basal diet), 2) ANT (basal diet + 44 mg/kg of avilamycin), 3) COS0.2 (basal diet + 0.2% COS), 4) COS0.4 (basal diet + 0.4% COS). The experiment lasted for 5 wk and avilamycin was administered from d 0 to 21. Growth performance was measured on d 0, 21, and 35, and all other response criteria were measured on d 35. No change in feed conversion (G:F) was observed in response to any of the treatments throughout the experimental period (P > 0.05). However, BW gain and feed intake were greater (P < 0.05) in broilers provided with feed supplemented with COS than in those in the control group. In addition, broilers had significantly greater (P < 0.05) red blood cell and high-density lipoprotein cholesterol concentrations when they were provided with the COS0.4 diet, whereas the triglyceride concentration was lower (P < 0.05) in broilers in the COS0.2 treatment group. No other blood characteristics were affected by the treatments. Additionally, as the dietary COS concentration increased, the liver weight increased (P < 0.05). Conversely, as the concentrations of dietary COS increased, abdominal fat decreased (P < 0.05). Furthermore, meat yellowness decreased (P < 0.05) as the concentration of COS increased. Finally, the breast meat and abdominal fat of birds provided with feed supplemented with COS had a lower (P < 0.05) saturated fatty acid concentration but a greater concentration of total monounsaturated fatty acids (P < 0.05) than that of birds in the control. In conclusion, COS can improve the performance and breast meat quality of broilers while increasing the red blood cell and high-density lipoprotein cholesterol concentrations in blood. In addition, COS can induce a decrease in abdominal fat and improve meat quality. EXPERIMENT 2: EFFECT OF CHITTOOLIGOSACCHARIDE SUPPLEMENTATION ON EGG PRODUCTION, NUTRIENT DIGESTIBILITY, EGG QUALITY, AND BLOOD PROFILES IN LAYING HENS This study was conducted to evaluate the effects of dietary supplementation with chitooligosccharide (COS) on egg production, nutrient digestibility, egg quality and blood profiles in laying hens. A total of 240 Hy-line Brown laying hens were randomly allocated into one of the following 5 dietary treatments: i) CON, basal diet; ii) ANT, basal diet+44 mg/kg avilamycin; iii) COS0.2, basal diet+200 mg/kg COS; iv) COS0.4, basal diet+400 mg/kg COS; v) ANTCOS, basal diet+200 mg/kg COS+22 mg/kg avilamycin. The experiment lasted for 6 wk. No change in egg weight (P > 0.05) was observed during the trial period. Egg production in ANTCOS treatment was improved (P < 0.05) when compared to CON during weeks 4-6. The birds in the COS0.2, COS0.4 and ANTCOS groups had higher (P < 0.05) Haugh unit than those fed CON and ANT diets at the end of the 6th wk. The apparent digestibility of nitrogen in CON group was lower (P < 0.05) than in other treatments. The white blood cell (WBC) concentration of birds in the COS0.4 and ANTCOS group was higher (P < 0.05) than that of birds in other groups at the end of the 6th wk. In addition, the differences of WBC counts between the beginning and end of the experiment in COS0.4 and ANTCOS groups were higher (P < 0.05) than in CON and ANT groups. At the end of the experiment, the birds fed ANTCOS diet showed higher (P < 0.05) total blood protein concentration than those fed CON or ANT diets. In conclusion, dietary supplementation of COS appeared to increase egg production and quality by increasing nutrient digestibility. Additionally, COS improved WBC and total protein concentration.

비화산대 내 워터해머 기반 시추비용을 고려한 지열발전 기술경제성 평가 연구

유석호 전남대학교 2019 국내박사

세계 온실가스 배출량 중 40%를 발전 산업이 차지하고 있고, 이 중 80%가 석탄발전에서 발생하고 있다. 이런 이유로 석탄발전은 정부의 온실가스 배출 억제 정책의 주 대상이 되며, 본격적으로 감축 정책이 수립되고 있다. 반면, 신재생에너지원 발전은 에너지 자립화에 대한 중요성이 강조됨에 따라 지속적인 성장세가 전망되고 있다. 신재생에너지 발전 사업 중 지열발전 분야는 90% 이상의 높은 설비 가동률로 국내 에너지 개발 환경에 적합한 에너지원이 될 가능성이 높다. 현재 지열발전은 아이슬란드, 핀란드, 헝가리, 독일, 필리핀, 인도네시아, 미국 등 국가들을 중심으로 많은 연구가 진행되고 있다. 우리나라에서도 국가적인 차원에서 광주, 나주 및 포항 지역에서 지열 난방 및 발전에 관련된 연구와 실증 프로젝트 등을 진행 중에 있다. 포항지역 지열 발전 프로젝트 경우 검증 절차 중에 지난 포항 강진의 원인이 지열 시추공에 영향이 있다는 언론 보도로 인해 잠시 중단된 상태이나 향후 지속적인 연구의 필요성이 대두되고 있다. 본 연구에서는 지열발전 사업에 적용 가능한 워터해머 시추공법과 회전식 시추공법과의 경제성을 비교 분석하였다. 또한, 우리나라를 포함한 비화산대 국가(지역)에서도 지열발전이 상업성을 가질 수 있는 지에 대해 연구를 수행하였다. 비화산대 지역에서의 지열발전 사업은 시추비용이 전체 프로젝트 사업비중에서 60% 이상을 차지한다. 따라서 시추 비용을 중심으로 지열발전 사업의 경제성 및 이론적인 상관관계를 분석하고, 해외의 적용 사례 등을 파악하였다. 국내 워터해머 시추공법 기반 지열 시추공 비용은 3,500m 1공 기준 25억, 독일 Landau 지역 회전식 시추공법 기반 지열 시추공은 3,000m 1공 기준 53억이며, 워터해머 시추공법은 회전식 시추공법에 비해 더 깊은 심도에도 불구하고 63% 비용 절감을 가져왔다. 단, 본 연구에서는 독일 Landau 지열발전사업 모델과 비슷한 지열온도 조건을 맞추기 위해 등가온도 값을 적용하여 광주 및 나주의 시추심도를 각각 5,202m 및 4,702m까지 설정하였으며, 국내의 경우 저류층의 온도에 기인하여 더 깊은 심도의 시추가 수행되어야 함으로 독일에 비해 약 1.5배 높은 시추비용이 발생하였다. 또한, 발전전력 수익 측면을 분석한 결과, 국내 REC 제도에 따라서 지원받는 지열 발전전력 지원량은 약 176원/kw이며, 독일의 FIT 제도에 따른 발전지원 수익은 325원/kw로 독일이 한국보다 약 2배 높은 지원을 받는 것이 확인되었다. 시추기술에 따른 비화산대 지열발전설비 경제성 분석 결과, 국내 워터해머 시추공법 기반 지열발전사업(평균)의 IRR 및 PP는 15.86% 및 5.21년이며, 독일 내 회전식 시추공법 기반 지열발전사업의 IRR 및 PP는 28.38% 및 3.74년으로 확인되었다. 워터해머 시추공법은 회전식 시추공법보다 시추비용을 크게 절약할 수 있지만, 국내의 경우 워터해머를 적용했음에도 독일에 비해 낮은 저류층 온도 조건과 지원제도로 인해 상대적으로 전체 시추비용은 높게, 발전수익은 낮게 산출되었다. 본 연구를 통해서 우리나라와 같은 비화산대 지역에서도 새로운 시추기술인 워터해머 시추공법을 적용하여 경제성 있는 지열발전 개발 사업의 가능성을 확인하였다. 또한, 워터해머 시추공법은 기존 회전식 시추공법에 비해 시추비용을 2배 이상 절감할 수 있어 해외 기술 수출도 활발히 이루어질 수 있을 것으로 판단된다. 국내 지열발전 사업이 충분한 경제성을 갖추기 위해서는 REC 가중치가 최소 2.0까지 지원되어야 하며, 국제적으로 경쟁력을 갖추기 위해서는 3.0이상까지도 지원이 고려되어야 한다. 본 연구 결과를 바탕으로 향후 국내 지열발전 연구 및 개발 투자 시 유용한 지침이 될 수 있을 것으로 판단된다. Power generation accounts for 40% of global GHG(Green House Gas) emissions, 80% of which is generated from coal power generation. For this reason, coal power generation is the main target of the government's policy to curb greenhouse gas emissions, and its reductions are being made in earnest. On the other hand, renewable energy source development is expected to continue to grow as the importance of energy independence is emphasized. The interest in the development of renewable energy to suppress carbon dioxide emissions has been increased. In particular, geothermal power generation is likely to become an energy source suitable for domestic energy development environment with high facility utilization rate of over 90%. Geothermal power generation has been studied in many countries including Iceland, Finland, Hungary, Germany, the Philippines, Indonesia and the United States. Korea has also conducted research and demonstration projects on geothermal heating and power generation in Gwangju, Naju, and Pohang from the national level. In the case of a geothermal power generation project in the Pohang area, it has been temporarily suspended due to issues in media reports that the cause of the Pohang earthquake was influenced by geothermal boreholes during its investigation, but the need for further research is emerging. In this study, the economic feasibility of water hammer and mud rotary drilling methods applicable to a geothermal power generation project was analyzed. In addition, the possibility of geothermal power generation in non-volcanic countries including Korea was studied. In geothermal power generation projects in non-volcanic areas, drilling costs account for more than 60% of the total cost in the project. Therefore, we analyzed the economical and theoretical correlation of a geothermal power generation model in terms of drilling costs, The cost of a geothermal borehole for based on water hammer drilling technology in Korea is about 2.5 billion KRW/hole at the depth of 3,500 meter. The cost of a geothermal borehole based on mud rotary drilling technology in Landau area, Germany is about 5.3 billion KRW/hole at the depth of 3,000 meter. Water hammer technology has resulted in a 63% cost savings despite deeper depths than rotary drilling. In this study, in order to establish similar conditions to the Landau geothermal power generation model in Germany, it was necessary to set drilling depths of 5,202m and 4,702m respectively in Gwangju and Naju when constructing domestic geothermal power generation models. Under these conditions, domestic drilling costs were about 1.5 times higher than in Germany. As a result of analyzing the revenue side of development progress, the subsidy for power generation supported by the domestic REC system is about 176 KRW/kw, and the subsidy for power generation supported by the German FIT system is 325 KRW/kw. It was confirmed that the German power generation project received about twice as much support as the Korean power generation project. As a result of the economic analysis for geothermal power plant according to drilling technologies in non-volcanic zone, the IRR and PP of the average value of a domestic geothermal power generation model based on Water Hammer drilling method were 15.86% and 5.21 years. The IRR and PP of a geothermal power generation model based on the rotary drilling method in Germany were 28.38% and 3.74 years. Water hammer drilling method can save drilling cost more than mud rotary drilling method. However, in Korea, despite the application of water hammer, drilling cost is high and development profit is low due to geothermal geological condition and support system which are weaker than Germany. Through this study, it was confirmed that it is possible to develop economical geothermal power generation through the application of new drilling technology called water hammer drilling method in non-volcanic area like Korea. However, in order for domestic geothermal power generation projects to have sufficient economic efficiency, it is necessary to keep the REC weight to at least 2.0, and to increase the international competitiveness to 3.0 or more. Based on this, it can be considered that the results of this study can be useful guidelines for future research and development investment in domestic geothermal power generation.

Brine과 bittern으로부터 Li, Mg 및 다른 유가금속 회수

쿠엔, 트란 치 전남대학교 대학원 2013 국내석사

Lithium and its compounds have been used in variety of applications such as rechargeable batteries, glass and ceramic, aluminum, rubbers, pharmaceuticals or greases. Due to the widespread application, lithium production is required to meet the global demand. The production of lithium from brine is about 2 times less expensive than minerals. Locating in Bolivia’s highland, Salar de Uyuni is known to have the richest lithium resources in the world (of 10.2 Mt). A high Mg to Li ratio of 21.2 is a significant factor hindering the lithium production in Uyuni brine. Mg removal from brine is required in order to prepare for Li production. Three reagents namely sodium hydroxide, sodium phosphate and oxalic acid were used for the test-work. Oxalic acid showed its efficiency in Mg removal from brine. The effect of pH and the amount of oxalic acid added were also studied in order to selectively removal Ca and optimize the subsequent Mg removal yield. At an addition of oxalic acid at oxalate:Ca molar ratio of 6.8:1 and pH<1, about 80% of Ca could be removed from the brine without co-precipitation of magnesium oxalate. A molar ratio of 1:1 to 1.6:1 oxalate:Mg in the pH range of 3 5.5 was used for ? Mg precipitation as oxalate with the amount of NaOH addition for pH adjustment according to molar ratio of 1.95:1?3.2:1 NaOH:Mg. A recovery of >95% Mg was achieved (precipitate containing both magnesium hydroxide and magnesium oxalate), along with the loss of ∼30% Li and 30% K in this stage. The NaOH addition used for pH adjustment is the main reason causing the formation of Mg(OH)2. Washing tests were conducted for the removal of impurities such as sodium chloride, sodium sulphate, carnalite etc. The XRD pattern shows a highly efficient removal of sodium chloride, sodium sulphate, carnalite as well as the high purity of >99% Mg oxalate yielded. Weight reduction of 24.5-24.7% for pure product b and c in the first step and 46.6-47.1% in the 2nd step were obtained by DTA from MgC2O4.2H2O during roasting. Compared to pure MgC2O4.2H2O these weight losses would correspond to the removal of water (24.27% weight lost) at 220oC and conversion at 500oC to MgO (48.55% weight lost).

Health acculturation and type 2 diabetes management among Vietnamese, Chinese, Korean, and Latino adult immigrants in the US

Nguyen, Thuc-Nhi ProQuest LLC UMI Dissertation Publishing 2015 국내박사

Liquid Phase Sintering of BaY0.1Zr0.9O2.95 Proton Conducting Ceramics

니구겐 트란 휴엔 디에우 전남대학교 대학원 2013 국내석사

Liquid Phase Sintering of BaY0.1Zr0.9O2.95 Proton Conducting Ceramics For Use in Intermediate Temperature Solid Oxide Fuel Cells Huyen Dieu Nguyen Tran Department of Materials Science and Engineering Graduate School Chonnam National University (Supervised by Professor John Fisher) Abstract Ytrria-doped BaZrO3 with the perovskite structure shows potential as a proton conducting electrolyte for solid oxide fuel cells (SOFCs), which represent the state of the art in recent years. The present thesis consists of two research topics concerning Yttria-doped BaZrO3: in the first part, we have presented results on the influence of sintering aids on the densification of polycrystalline BaZr0.9Y0.1O3-δ (BZY10); in the second part, the solid state crystal growth method was used to grow single crystals of BaZr0.9Y0.1O3-δ and the structurally related material SrTiO3. In the first part, powders of BaZr0.9Y0.1O2.95 (BYZ10) were prepared by using the solid-state reaction method with BaCO3, Y2O3 and ZrO2 starting chemicals. The appropriate amounts of Bi2O3, MnCO3 and CuO were then added into the calcined powder as liquid phase sintering aids. The effects of sintering aids on densification, microstructure and electrical properties were studied. Samples were pressed into pellets by cold isostatic pressing at 1500 kg/cm2 (147 MPa) and sintered in the range of temperature from 1400ºC to 1700ºC for 5 hours. Densification of samples was measured by the bulk density method; the density of 3wt% MnCO3 and CuO doped BZY10 reached 93% and 93% theoretical density respectively. The microstructure of samples was studied by scanning electron microscopy (SEM). The structure of the sintered ceramics and the possibility of secondary phases were examined by X-ray diffraction (XRD). All samples were single phase perovskite with cubic structure. Electrical properties of the as-prepared samples was examined below 220?C with impedance spectroscopy. In polycrystalline ceramics, the electrical or ionic conductivity often consists of two components; a bulk conductivity and a grain boundary conductivity. In particular, for acceptor-doped BaZrO3 the grain boundary conductivity is substantially lower than that of the bulk conductivity and dominates the impedance plots. In order to study the bulk conduction mechanisms, it is necessary to grow single crystals of BZY or materials with a similar structure such as SrTiO3. In the second part of this work, the solid-state crystal growth (SSCG) technique is used to grow single crystals of BZY10 and SrTiO3. The principle of the SSCG method is based on inducing abnormal grain growth of the ceramic composition on a seed crystal. This method shows many advantages compared to other single crystal growth techniques e.g. it takes place without melting of the ceramic matrix, it does not need expensive Pts crucible or high temperature processing. Calcined powders of BYZ and Fe-doped SrTiO3 are used to grow single crystals using 8 mol % Yttrium doped ZrO2 and SrTiO3 seed crystals respectively. A single crystal of BZY10 has grown to a thickness of about 5μm on a <100> oriented YSZ seed. Single crystals of Fe-doped SrTiO3 grew to thicknesses of 5 - 25?m on <100> oriented SrTiO3 seeds, with the growth distance varying with sintering atmosphere.

Physics-based impedance modeling of mixed ionic electronic conductors, liquid/polymer/solid electrolytes, and human body segments

TRAN THI HUYEN TRAN 전남대학교 2024 국내박사

Impedance spectroscopy, with its roots extending over a century, remains a cornerstone technique in the characterization of material properties. Despite its extensive history, the inter- pretation of impedance data has often been fraught with challenges, with models frequently prioritizing curve fitting over a comprehensive understanding of the underlying mechanisms and material properties. A significant contributor to the problem is the over-reliance on the Constant Phase Element (CPE), which can obscure the true characteristics of the materials under investigation. This thesis addresses these critical issues, motivated by the necessity for more accurate and insightful impedance analysis. The scope of this research encompasses the characterization and modeling of impedance behavior across a diverse range of materials, including mixed electronic-ionic conductors, solid, liquid, and polymer electrolytes, as well as human body segments. By developing physics-based impedance models, this work aims to deliver a more thorough and precise understanding of these materials, thereby enhancing the reliability and applicability of impedance spectroscopy in material science. This dissertation investigates the electrical properties of mixed ionic-electronic conductors (MIECs) and human body segments through systematic in-situ impedance analysis. The primary focus is on cathode materials such as lithium vanadium phosphate (LVP) and sodium vanadium phosphate (NVP), exploring their charge transport mechanisms, phase transitions, and tempera- ture influences. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) confirmed the successful synthesis and phase transitions, respectively. The study applies the transmission line model (TLM) to elucidate temperature-dependent parameters, providing insights into the ionic and electronic conductivities of NVP and LVP. Similarly, as for the ions and electrons in mixed conductors, Nernst-Planck flux model can be applied for cation and anion in liquid and polymer electrolytes for batteries. PEO:LiTFSI electrolyte is found to have Li+ transference number abound 0.1 independent of the temperature. The transference number of 1 M LiPF6 in EC/DMC increases with temperature from 0.01 at 10 °C to 0.25 at 60 °C. While the solid electrolytes like LLZO and LLTO have lithium transference number 1, electronic conduction is known to become substantial at grain boundaries to form dendrites. Heuristic modeling of temperature-dependent LLZO impedance is assisted by Python algorithms. Additionally, the research extends to biological impedance analysis, particularly in human body segments. Utilizing principles of porous electrode theory and the Nernst-Planck flux model for body solution within the transmission line framework, as for the battery liquid electrolytes, the study offers an innovative approach to understanding the complex impedance behavior of human body segments. The integration of stray capacitance in automated Keithley channel circuitry simulations revealed an average stray capacitance with mode-dependent variations. This incorporation improved the accuracy of impedance simulations, although challenges in merging high-frequency stray effects with analytical functions were noted. The work further employs Python simulations, based on Miran Gaberšček’s matrix tools, to enhance visualization and understanding of body fluid dynamics. The Nernst-Planck theory is applied to explain fluid distribution variations, with simulations corroborating the model’s accuracy. Despite the time-intensive nature of individual EIS data simulation, the study under- scores the need for developing approximate analytical models to efficiently analyze extensive impedance databases. 임피던스 분광법은 100년 이상의 역사를 가지며, 물질 특성화를 위한 핵심 기술로 자 리매김하고 있다. 그러나 임피던스 데이터 해석은 종종 도전적인 과제로 여겨지며, 모델이 기본 메커니즘과 물질 특성을 포괄적으로 이해하는 것보다 곡선 맞추기에 우선하는 경우가 많다. 이러한 문제에 크게 기여하는 요소 중 하나는 Constant Phase Element (CPE)에 대한 과도한 의존으로, 이는 조사 대상 물질의 진정한 특성을 가릴 수 있다. 이 논문은 더 정확하고 통찰력 있는 임피던스 분석의 필요성에 의해 이러한 중요한 문제를 해결하려고 하였다. 이 연구의 범위는 혼합 전자-이온 전도체, 고체, 액체 및 폴리머 전해질, 인체를 포함한 다양한 물질의 임피던스 거동을 특성화하고 모델링하는 것을 포함한다. 물리 기반 임피던스 모델 을 개발함으로써 이 연구는 이러한 물질에 대한 더 철저하고 정확한 이해를 제공하여 물질 과학에서 임피던스 분광법의 신뢰성과 적용 가능성을 향상시키는 것을 목표로 한다. 체계적인 인시투 임피던스 분석을 통해 혼합 이온-전자 전도체(MIECs)와 인체 분절의 전기적 특성을 조사하였다. 주요 초점은 리튬 바나듐 인산염(LVP) 및 나트륨 바나듐 인산염 (NVP)과 같은 캐소드 물질에 있으며, 이들의 전하 전달 메커니즘, 상 전이 및 온도 영향을 탐구하였다. X선 회절(XRD) 및 차등 주사 열량 측정(DSC)은 이러한 물질의 성공적인 합성 및 상 전이를 확인하였다. 이 연구는 전송선 모델(TLM)을 적용하여 온도 의존적 매개변수를 해명하며, NVP 및 LVP의 이온 및 전자 전도성에 대한 통찰력을 제공하였다. 혼합전도체에서의 이온나르개와 전자나르개 처럼, 배터리 액체 전해질 및 폴리머전 해질에서는 양이온과 음이온이 전하중성을 맞추는 Nernst-Planck 모델을 따르게 된다. PEO:LiTFSI 는 온도에 관계없이 0.1 정도의 t+ 를 보이는 반면 EC/DMC 용매에 1M LiPF6 액체전해질은 10도에서 0.01 에서 60도에서 0.25 로 증가하였다. 인체 임피던스 연구도 진행되었는데, 다공성 전극 이론과 생체액의 전해질 거동을 고 려한 Nernst-Planck 모델을 전송선 프레임워크 내에서 활용하여, 인체의 복잡한 임피던스 거동을 이해하기 위한 혁신적인 접근 방식을 제공하였다. 자동화된 Keithley 채널 회로의 불필요한 커패시턴스를 통합한 시뮬레이션은 모드 의존적 변동과 함께 평균 약 0.1 nF의 불필요한 커패시턴스를 밝혀내었다. 이러한 통합은 임피던스 시뮬레이션의 정확성을 향상 시켰지만, 고주파 불필요한 효과를 분석 함수와 결합하는 데 있어 어려움이 있었다. Miran Gabersˇcek ˇ 등이 제안한 수치해석적으로 구하는 불균일한 TLM 을 인체임피던스에 적용하 였다. 개별 EIS 해석을 위해 여러 패러미터 들을 최적화 해야 하므로, 근사해석모델 개발이 필요하다.

Pomegranate (Punica granatum) Seed Linolenic Acid Isomers : Selective Estrogen Receptor Modulators? = 석류(Punica granatum) 종자유에서 분리된 리노렌산 이성체들의 선택적 에스트로겐 리셉터 수식자 (SERMs) 로의 작용성 : Tran Hoang Ngoc Ai

Hoang, Ngoc Ai Tran 경북대학교 2006 국내석사