Effects of High Intensity Interval Training on Muscle Function and Body Composition in Prostate Cancer Patients Receiving Androgen Deprivation Therapy

이경희 서울대학교 대학원 2019 국내석사

ABSTRACT Introduction: Majority of patients with prostate cancer experience negative changes in body composition and physical function after receiving androgen deprivation therapy. These increase a risk to contract metabolic syndrome and chronic diseases which consequentially decrease the patients’ health-related quality of life and increase mortality. As exercise has been considered as a key solution to ameliorate these adverse effects, numerous exercise intervention studies have been conducted. However, there is a lack of research to clarify the effect of high-intensity interval training that may be more effective and more necessary for prostate cancer patients. The purpose of this study is to define the effect of high-intensity interval training compared to moderate-intensity continuous training in a change of body composition and physical performance focusing on muscle function in patients with prostate cancer. Methods: Twenty-four patients who met study criteria were recruited and allocated to either high-intensity interval training group (n=12) or moderate-intensity continuous group (n=12). Before and after participating 12 weeks of the exercise program, all patients were measured (1) body composition and bone mineral density, (2) muscle strength and endurance, (3) self-reported questionnaires, (4) physical fitness. The type of exercise in both groups was combined exercise using an elastic band. High-intensity interval training group exercised twice a week targeting 75-85% of individual heart rate max and 14 to 17 rated perceived exertion (RPE). Patients in moderate-intensity continuous training group received exercise education at the beginning and in the middle of the intervention in order to do walking and resistance exercise in moderate intensity targeting 12 to 15 RPE at home. The amount of the exercise was monitored by pedometer record and daily log file in this group. Results: Of the twenty four patients, eighteen patients (High-intensity interval training group; n=9, Moderate-intensity continuous training group; n=9) completed the exercise program and six patients failed for various reasons (body pain 2, hospital movement 2, personal reason 2). Following 12 weeks of the high-intensity interval training program, there was significant difference of interaction between group and time in upper body muscle endurance measured by arm curl test(p=.019), lower body muscle endurance measured by isokinetic dynamometer at angular velocity of 180°/sec (p=.035) and chair stand test(p=.012). Also, FACT-P which is a questionnaire to evaluate the quality of life was improved by over 10% in high-intensity interval training group, a significant difference in interaction (p=.011). However, there was no significant result found in body composition and bone mineral density, muscle strength. Conclusion: 12 weeks of high-intensity interval training clearly demonstrated a beneficial effect on upper and lower body muscle endurance and quality of life in prostate cancer patients who have been receiving androgen deprivation therapy. The other outcomes were similar to moderate-intensity continuous training. Therefore, high-intensity interval training may be a time-efficient exercise strategy. The further study is needed to verify the exercise program to improve body composition and certain aspects of the health of prostate cancer patients. Keywords : High-intensity interval training, Prostate cancer, Androgen deprivation therapy, Body composition, Muscle function Student Number : 2017-23579 국 문 초 록 서론: 안드로겐 박탈 치료를 받은 후 전립선 암 환자의 대다수는 신체 조성 및 신체 기능에서 부정적인 변화를 경험한다. 이로 인해, 대사 증후군 및 만성 질환에 걸릴 수 있는 위험이 증가하여 환자의 건강 관련 삶의 질을 저하시키고, 이차적 요인으로 인한 사망률을 높인다. 운동은 이러한 부작용을 완화시키는데 긍정적인 영향을 주는 것으로 알려졌으며, 전립선암환자에서 수 많은 운동 중재 연구가 이루어져왔다. 그러나, 전립선 암환자에게 더 효과적일 수 있는 고강도 인터벌 운동의 효과를 하는 연구는 부족한 실정이다. 따라서, 본 연구의 목적은 고강도 인터벌 운동이 전립선 암 환자의 근 기능과 신체조성 변화에서 미치는 영향을 중등도 지속 운동과 비교하여 규명해 보고자 한다. 연구방법: 연구참여기준을 충족시킨 24 명의 암환자가 모집되어, 고강도 인터벌 운동군(n=12) 또는 중강도 지속 운동군(n=12)으로 할당되었다. 모든 암환자는 운동프로그램의 사전/사후에 (1) 신체조성과 골밀도, (2) 근력 및 지구력, (3) 노인체력, (4) 삶의 질, 신체활동량 관련 설문지를 측정하였다. 두 그룹의 운동 유형은 저항성 밴드를 이용한 복합운동으로 하였다. 고강도 인터벌 그룹은 주당 2회 운동을 실시 하였으며, 최대 심박수의 75-85%와 운동자각도 14-17을 목표로 이루어졌다. 중강도 지속 운동군에서는 운동자각도 12-15를 목표로 걷기와 근력운동을 하기 위해 두 번의 운동교육을 받았으며, 운동량은 만보계 기록과 로그파일을 통해 확인하였다. 연구결과: 12주 운동프로그램에서 전립선 암 환자 18명(고강도 인터벌 운동군, n=9; 중강도 지속 운동군, n = 9)이 참여를 완료하였고, 6명의 환자가 다음과 같은 사유로 중도 탈락하였다(통증호소, n=2; 병원이동, n=2; 개인사유, n=2). 고강도 인터벌 운동군에서 상지 근지구력 평가를 위한 Arm curl test(p = .019)와 하지 근지구력 평가를 위한 각 속도 180°/초에서의 등속성 운동검사(p = .035) 및 Chair stand test (p = .012)에서 유의한 증가를 보였다. 또한, 삶의 질을 평가하는 설문지 인 FACT-P의 점수가 고강도 인터벌 운동군에서 10% 이상 증가하여, 유의한 차이를 보였다(p = .011). 그러나, 신체조성, 골밀도, 근력에서 그룹시기간 유의한 차이는 나타나지 않았다. 결론: 12 주간의 고강도 인터벌 운동은 안드로겐 박탈 치료를 받는 전립선 암 환자의 상, 하체 근지구력과 삶의 질을 향상시키는데 그룹 시기간 유의한 차이가 나타났다. 이외에 변인은 중강도 지속 운동과 유사했기 때문에 고강도 인터벌 운동은 시간 대비 효율적인 운동 전략이 될 수 있다. 후속 연구로 전립선 암 환자의 신체조성, 골밀도 그리고 근력을 포함한 건강관련 체력을 개선하기 위한 운동중재연구가 필요하다. 주요어: 고강도 인터벌 운동, 전립선암, 안드로겐 박탈치료, 신체조성, 근 기능 학 번: 2017-23579

Manipulating Electronic Structure of Low- dimensional Materials using High Gas Pressure

장현석 인천대학교 대학원 2024 국내박사

Since graphene and MoS2 were discovered, they have received considerable attention due to their exotic electrical and structural properties, and possibilities for various applications. Graphene shows unique electrical properties due to linear dispersion relation at the Dirac point. However, to alter the former silicon industries, the electronic structures such as ambipolarity and zero band gap must be manipulated. MoS2 has received great attention due to its strong spin-orbit coupling, superconductivity, high mobility (μ), and large on-off ratio. Moreover, it is considered a candidate of thermoelectric material due to its high thermoelectric power (TEP). However, it remains to get high electrical conductivity (σ) and low thermal conductivity for practical applications. High-pressure gas exposure to graphene and MoS2 is considered a cost-effective method of manipulating electronic structures. The dissociative adsorption of hydrogen on graphene induces an n-doping effect and increases the carrier concentration, increasing σ. The creation of oxygen functional groups due to the exposure to high-pressure O2 induces p-type behavior of graphene. The high-pressure H2 exposure on MoS2 creates sulfur vacancies (VS) in the structure and causes to n-doping, midgap state creation at the density of state, and convergence of multiple degenerated electronic band structures. These phenomena result in an increase of σ and TEP. In this study, we demonstrated the evolution of electronic and geometric structure of graphene and MoS2 after exposure to high-pressure gas. The structural changes due to the high- pressure gas exposure obtained by X-ray photoelectron spectroscopy, X-ray diffraction patterns, Raman spectroscopy, transmission electron microscope, and atomic force microscope showed a very small change compared to before exposure. However, the electrical conductance (G) of graphene increased 168.6% after exposure to 80 bar of H2 at 343 K, and the conductivity of MoS2 increased 1785% and 5223% for few-layer and bulk MoS2, respectively. In the field effect characteristics, the shift to the n-type region was clearly observed after H2 exposure. For graphene, the charge neutrality point splitting and transfer curve flattening were observed induced by hydrogen adsorption. For the MoS2, the increase ratios of PF reached 3355% and 22205% for few-layer and bulk MoS2, respectively. Manipulating electronic structures using high-pressure gas exposure has the potential and advantages of convenience, cost-effective, absence of environmental hazards, application to large-scale fabrication, and controllability. In this study, we demonstrated the controllability of the electrical structure by high-pressure gas exposure methods using tuning the exposure gas type, pressure, time, and temperatures.

Ultraconcentrated Sodium Bis(fluorosulfonyl)imide- Based Electrolytes for High-Performance Sodium Metal Batteries

Jaegi Lee Graduate School of UNIST 2017 국내석사

Rechargeable Na metal batteries have gained great recognition as a promising candidate for next-generation battery systems, largely on the basis of the high theoretical specific capacity (1165 mAh g−1) and low redox potential (−2.71 V versus the standard hydrogen electrode) of Na metal, as well as the natural abundance of Na and the similarities between these batteries and lithium batteries. Much effort has been dedicated to improving the electrochemical performance of rechargeable Na batteries through the development of high-performance cathodes, anodes, and electrolytes. Nevertheless, the practical application of Na metal batteries is quite challenging because the high chemical and electrochemical reactivity of Na metal electrodes with organic liquid electrolytes leads to low Coulombic efficiencies and limited cycling performance. Severe electrolyte decomposition at the Na metal electrode results in the formation of a resistive and non-uniform surface film, leading to dendritic Na metal growth. To control the Na metal electrode–electrolyte interface for high performance Na metal batteries, considerable efforts have been made to find electrolyte systems that are stable at the Na metal electrode. Using fluoroethylene carbonate (FEC) as an electrolyte additive for in situ formation of an artificial solid electrolyte interphase (SEI) layer could stabilize the anode- electrolyte interface. However, the FEC-derived SEI acted as a resistive layer, impeding the sodiation–desodiation process and reducing the reversible capacity of the anodes. Finding new electrolyte systems that are stable at the Na metal electrode and possess high oxidation durability at high-voltage cathodes is necessary for the development of high-performance Na metal batteries. Very recently, there are some papers which introduced significant breakthroughs in lithium battery electrolytes. It is reported that improving the cycling efficiency of lithium plating/stripping and suppressing the formation of dendritic lithium metal is possible by using highly concentrated electrolytes, even at high current densities. And it is also reported that highly concentrated electroltyes can inhibit the dissolution of transition metals out of the 5 V-class LiNi0.5Mn1.5O4 (LNMO) electrode material and the corrosion of the Al current collector at high voltage conditions. After reading these papers, I thought that applying this highly concentrated electrolyte system to sodium metal batteries could be the solution for improvements in the electrochemical performance of Na metal anodes coupled with high-voltage cathodes. In this study, an ultraconcentrated electrolyte composed of 5 M sodium bis(fluorosulfonyl)imide in 1,2-dimethoxyethane will be introduced for Na metal anodes coupled with high-voltage cathodes. Using this electrolyte, a very high Coulombic efficiency of 99.3% at the 120th cycle for Na plating/stripping is obtained in Na/stainless steel (SS) cells, with highly reduced corrosivity toward Na metal and high oxidation durability (over 4.9 V versus Na/Na+) without corrosion of the aluminum cathode current collector. Importantly, the use of this ultraconcentrated electrolyte results in substantially improved rate capability in Na/SS cells and excellent cycling performance in Na/Na symmetric cells without the increase of polarization. Moreover, this ultraconcentrated electrolyte exhibits good compatibility with high-voltage Na4Fe3(PO4)2(P2O7) and Na0.7(Fe0.5Mn0.5)O2 cathodes charged to high voltages (>4.2 V versus Na/Na+), resulting in outstanding cycling stability (high reversible capacity of 109 mAh g−1 over 300 cycles for the Na/Na4Fe3(PO4)2(P2O7) cell) compared with the conventional dilute electrolyte, 1 M NaPF6 in ethylene carbonate/propylene carbonate (5/5, v/v).

초기 설계 단계에서 트위스트 형태 초고층 건물의 에너지 성능 평가를 위한 파라메트릭 시뮬레이션 방법에 관한 연구 : A Parametric Energy Performance Simulation Approach in Twisted High-rise Buildings at an Early Design Stage

김사겸 단국대학교 2012 국내석사

In these days, a number of high-rise buildings have been constructed in worldwide. High-rise buildings are reported to consume more energy than low-rise buildings due to a large envelope surface area and huge mass. Therefore, it is important to evaluate energy performance at an early design stage for low energy building design. However, energy performance evaluation of high-rise buildings at an early design stage is very limited due to insufficient information at the design process. Also, often irregular shapes make the evaluation even harder. Thus, a new method for energy performance evaluation of high-rise buildings with an irregular shape should be studied at an early design stage. This study examined an approach for energy performance simulation in a high-rise building with twisted shapes using building information modeling technologies and parameters at an early design stage. First, this study utilized a simplification method of an architectural model to implement energy performance analyses. This simplified architectural model was generated based on limited data at an early design stage. The simplified architectural model was converted to a gbXML based data model through interoperability technology. Then, the data model could generate an energy performance analysis model. Finally, energy performance simulation is conducted for a high-rise building with a twisted shape. Based on this approach, an energy performance evaluation process is established for energy saving. This new approach could conduct energy performance simulation until an optimized alternative shape was achieved. Currently, we developed a user interface to automate this process, which is called Sustainable High-rise building Energy Planer (SHEP). The SHEP was able to conduct energy analysis of various high-rise buildings with twisted shapes through parameters with a range and automatically generated an energy optimal high-rise building shape. 오늘날, 전 세계적으로 수많은 초고층 건축물이 건설되고 있다. 이러한 초고층 건물들은 저층 건물보다 넒은 입면 면적과 매스 등의 영향으로 많은 에너지를 소비되는 것으로 보고되고 있다. 따라서 초고층 건물의 에너지 저감을 위한 초기 설계 단계의 에너지 성능 평가가 매우 중요하다. 하지만 초기 설계 단계에서 초고층 건물의 에너지 성능 평가는 설계 단계의 제한된 정보만으로 수행하기에는 한계가 있다. 또한 초고층 건물의 형태가 비정형일 경우 에너지 성능 평가는 많은 어려움이 있다. 따라서 초기 설계 단계의 트위스트 형태와 같은 비정형 건축물의 에너지 성능 평가를 위한 새로운 방법이 필요하다. 따라서 본 연구에서는 트위스트 형태의 초고층 건물을 중심으로 초기 설계 단계 건물 정보 모델링 기술과 파라미터를 이용한 에너지 성능 시뮬레이션 방법을 연구 하였다. 먼저 에너지 성능 분석을 위한 설계 모델의 단순화 방법을 연구하였다. 이 단순화된 설계 모델은 초기 설계 단계에서의 주요 파라미터에 대한 제한된 데이터를 이용하여 생성되었고 상호운용성 기술을 통해 gbXML 기반 데이터 모델로 변환되었다. 변환된 gbXML 기반 데이터 모델은 에너지 성능 시뮬레이션이 가능한 에너지 성능 분석 모델로 생성되었다. 이러한 프로세스를 이용하여 본 연구에서 비틀린 형태 초고층 건물의 에너지 성능 시뮬레이션을 수행 할 수 있었다. 본 연구에서는 최종적으로 트위스트 형태의 초고층 건물에 대한 에너지 성능 분석을 하고 최적화된 형태를 도출하기 위한 프로세스를 개발하고 인터페이스를 개발하였다. 이 프로세스는 에너지 저감 할 수 있는 최적 대안을 선택할 때까지 반복적으로 에너지 시뮬레이션을 수행할 수 있다. 본 연구에서는 에너지 성능 평가 프로세스를 자동화 할 수 있는 사용자 인터페이스인 SHEP(Sustainable High-rise building Energy Planer)를 개발하였다. SHEP는 파라미터 변화에 따른 다양한 트위스트 형태의 초고층 건물에 대한 에너지 성능 분석 시뮬레이션이 가능하며 에너지 최적 건물 형태를 자동적으로 도출 할 수 있다.

고비저항 Germanium 단결정의 극저온 고주파 특성 및 고비저항 Germanium 및 Silicon 단결정에 대한 열처리가 전기적 특성에 미치는 영향 연구

김지웅 건국대학교 대학원 2016 국내석사

유전체의 비저항(resistivity)과 유전적 손실(dielectric loss)에서 기인하는 tan δ(loss tangent)는 고성능 고주파 소자의 제작 시 고려되어야 하는 중요한 물리량이다. 고비저항(high-resistivity) Si 및 Ge을 이용한 큐비트(qubit)를 제작할 경우, tan δ가 decoherence의 직접적인 원인이 된다는 것은 잘 알려진 바 있고[13], 또한 고비저항 Ge을 이용하여 만드는 방사능 검출기(radiation detector)의 경우 tan δ는 전자-양공 쌍(electron-hole pair)을 낮은 에너지 준위에서 발생하게 하여 잡음(noise)을 발생시키는 것으로 알려져 있다.[10, 11] 본 논문에서는 고비저항 Si의 고주파 특성 측정에 사용된 방법[50, 51]을 이용하여 고비저항 Ge의 고주파 특성을 측정하고 고비저항 Si의 고주파 특성과 비교하였다. 이 과정에서 국제전기기술위원회(IEC)의 국제표준[49]으로 등재된 ‘변형된 유전체 공진기법’[17, 52]을 활용하였다. 6 - 11 K의 극저온 영역에서 고비저항 n-type Ge의 tan δ가 9 × 10-5 정도임을 측정하였으며 고비저항 Ge의 경우 유전적 손실(dielectric loss)이 매우 작은 고비저항 Si의 경우와 유전적 손실이 전도성 손실(conductive loss)과 비교될 만한 크기를 지닌다는 것을 확인할 수 있었다. Si와 동일한 4 족 원소이면서 Si 보다 원자량이 큰 Ge의 유전적 손실이 Si 보다 월등히 크게 관측된 것에 대한 이유는 아직 이해되고 있지 않은 바, 향후 추가 연구를 통해 이러한 원인 규명이 시도될 예정이다. 또한 고비저항 Si 및 Ge의 전기적 특성과 이들 시편들이 열처리(annealing)된 후 지니는 특성을 측정하여 고비저항 Si 및 Ge 단결정에 대한 열처리 효과(annealing effect)를 연구하였다. 고비저항 Si와 Ge의 경우 모두 열처리 후에 carrier형 변환(carrier type-conversion)이 발생함을 확인하였으나, Si와 Ge 간에 carrier형 변환의 경향성이 상이한 것으로 나타났다. 고비저항 n-type Ge에 대한 열처리 효과는 열처리 온도와 무관하게 285 K 이하의 온도에서 p-type으로 carrier형 변환이 발생하였으며, 285 K 이상의 온도에서는 다시 n-type으로 돌아가는 carrier형 변환이 발생하였다. 650 ℃로 열처리된 pristine Ge 단결정의 경우 dislocation density의 증가로 인해 280 K 근처에서 carrier형 변환현상이 관측된 것[36]과 같이, 각각 516 ℃와 825 ℃에서 열처리된 Ge 단결정에서도 유사한 현상이 관측되었다. 또한 650 ℃ 열처리 결과[43]와 비교했을 때, 516 ℃와 825 ℃ 열처리에서도 유사한 효과를 가질 수 있는 것을 확인하였다. 한편 고비저항 n-type Si는 825 ℃ 열처리 이후 p-type으로 carrier형 변환이 발생하였다. 또한 carrier 농도의 절댓값이 1000 배 이상 증가하면서 비저항 역시 1/30 이하로 감소하게 됨을 확인하였다. 이러한 결과는 Pt를 분산(diffusion)시키거나[37, 48] 중성자 조사(neutron irradiation)[30, 31]를 실시하지 않고 열처리만 하여도 고비저항 Si에서 carrier형 변환이 발생하게 됨을 보여 주는데, 이 경우 carrier 농도는 증가하는 것으로 관측되었다. The resistivity and the loss tangent(tan δ) of dielectric materials are important physical parameters that need to be taken into account for fabricating microwave devices of high performances. The tan δ of dielectric material has been known as the main source for the decoherence of qubit signals[13] and, for radiation detectors made of high-resistivity Ge, the tan δ is known to generate noise by creating a lower level energy electron-hole pair[10, 11]. In this thesis, the microwave properties of high-resistivity Ge crystals were measured by using the modified dielectric resonator method, which were compared with those of high-resistivity Si crystals[50, 51]. An international standard, which enables us to measure the intrinsic surface impedance of high-temperature superconductor films such as YBa2Cu3O7-δ, was used throughout this study[49]. It appeared that the tan δ of high-resistivity Ge crystals measured at 6 K was as low as 9 × 10-5and that, unlike Si crystals, contribution of the dielectric loss to the tan δ of Ge appeared to be significant. Considering that both Ge and Si are group 4 elements with the atomic mass of Ge being greater than that of Si, the reason for the significantly high dielectric loss compared to Si cannot be addressed at the moment. Further studies are needed to understand the related mechanism. The electrical properties of high-resistivity Si and Ge were also measured by using the Hall-effect measurement system from 80 K to 350 K. After the annealing process, both high-resistivity Si and high-resistivity Ge showed conversions of the carrier type. However, conversions of the carrier type appeared to be different between n-type Si and n-type Ge: The main carrier type for the annealed high-resistivity Ge became p-type at temperatures below 285 K, which, then, switched to the n-type at temperatures higher than 285 K. At 285 K, drastic variations in the mobility and carrier concentration were also observed for the Ge crystals. The conversion of the major carrier type has been reported for high-resistivity Ge annealed at 650 ℃, which was attributed to increase of the dislocation density[36]. Similar carrier-type conversion was observed for our Ge crystals annealed at 516 ℃ and 825 ℃. This is in contrast with another report[43], where the type conversion did not appear for the 500 ℃ annealing process. Meanwhile, the major carrier type of the high-resistivity Si changed from the n-type to the p-type after the specimens were annealed at 825 ℃. Furthermore, the resistivity of Si became 30 times lower after the annealing process due to an increase of the carrier concentration by more than 1000 times. Our results show that conversion of the major carrier type could be realized for annealed high-resistivity Si even without diffusion of Pt or being irradiated with neutrons. Increase of the carrier concentration was also observed for the annealed high-resistivity Si.

A Statistical Analysis of the Formation and Location Factors of High-Tech Centers in the United States, 1950-1997 : An Evaluation Using Quasi-Experimental Control Group Methods

기정훈 Univ. of Southern California 2002 해외박사

In this thesis, I examine when high-tech centers were formed in the United States and what location factors contributed significantly to the formation of high-tech centers during the period. I examine these questions by using quasi-experimental control group methods with the high-tech center group and the twin group that is composed of U.S. counties whose educational and economic conditions are most similar to those of the high-tech center group. There are major three findings from the research results. First, the high-tech centers were substantially formed during the 1970-1980 period in the United States. High-tech industries had their origin in the 1940s or 1950s, but their becoming high-tech centers came true in the 1970-1980 period. Second, high-tech services played a leading role in the formation of high-tech centers during the 1970-1980 period in the United States. Meanwhile, high-tech manufacturing played a smaller role because it followed the general trend of manufacturing decentralization into non-metropolitan areas. Third, most of the conventional high-tech location factors did not play a role in building up high-tech centers during the 1970-1980 period in the United States. This finding confirms that high-tech centers were established spontaneously without specific planning or policy during the period of formation. More careful approach and interpretation of research results, however, provide some insights that a local educated and affluent class can be a significant location factor of high-tech centers through "quality of life" improvements. Universities and university medical centers seem to have played a unique role in incubating and spinning off such educated and affluent class and workers who have a higher statistical relation with the formation of high-tech centers in the United States.

Synthesis and Characterization of High Entropy Alloy Film using Magnetron Sputtering

김영석 세종대학교 대학원 2020 국내박사

Hard coatings are widely utilized in industry as the protection of materials due to effectively improving the mechanical properties, oxidation, wear resistance, and thermal stability. Specifically, the lifetime of the materials for cutting tools depends on the material, shape and coating. Among them, the improvement of performance in cutting tools by hard coatings is one of the most important methods because there is a limit to improving the lifetime of the cutting tool by only modifying the base material and the shape of the tool. Thus, much research on high performance coating materials and coating processes have been carried out in order to cope with the recent demand for cutting tools. High entropy alloys (HEAs), which are defined as multiple principal alloy with equi-atomic or near equi-atomic percent, have received great attention as potential candidates for hard coatings. Compared to conventional metallic materials containing one or two principal elements, HEAs are designed by having five or more principal elements with the near-equimolar ratios. The basic idea of HEAs leads to high mixing entropy, sluggish diffusion, and severe lattice distortion, which tends to form simple solid-solution phases rather than complicated phases, such as intermetallic compounds. For those reasons, novel HEAs exhibit special and outstanding properties, such as high hardness and strength, high corrosion and wear resistance, and characteristic electrical properties, and have been extensively studied as potential for applications in diverse areas, such as hard coatings, and diffusion barriers. Recently, there has been increasing effort to develop thin film deposition of HEAs to improve the mechanical and thermal properties. Generally, high entropy thin films are widely prepared by the HE alloy target, which can easily have same stoichiometry between the deposited thin film and the starting target. However, the alloy target has a restriction in the selection of its composition due to the difficulty in fabricating target in bulk-scale. In other way, powder targets have been rarely employed although it has many advantages, such as diverse selection of elemental composition and uncomplicated method for target preparation, because it is difficult to control sputtering yields of the individual elements. Here, we have tried to synthesize the TiZrHfNiCuCo and AlCoCrNi HEA and HEN thin films utilizing single powder target, respectively. The structural and mechanical properties of the thin films was systematically investigated. In Chapter 3, TiZrHfNiCuCo high entropy metallic and nitride films were fabricated by using a reactive DC magnetron sputtering and TiZrHfNiCuCo single powder target. The effect of sputtering parameters, such as DC power, time, and nitrogen flow ratio, on the microstructure and mechanical properties of the HEA metallic and nitride films were systematically investigated. In Chapter 4, the structural and mechanical properties of AlCoCrNi high entropy metallic and nitride films were investigated by modulating nitrogen flow ratio and process pressure. Especially, we studied the effect on the mechanical properties in the high-entropy systems, caused by shifting the structure zone model. In Chapter 5, we discussed a mechanism of the phase formation on TiZrHfNiCuCo and AlCoCrNi high entropy metallic and nitride thin films. From the results of Chapter 3 and 4, we tried to demonstrated the mechanism of the phase formation related with the TiZrHfNiCuCo and AlCoCrNi high entropy metallic thin film, by introducing thermodynamic parameters and a kinetic approach. Furthermore, the phase transformation behaviors by inclusion of nitrogen during the reactive sputtering process were discussed.

High-resolution Portable Microscope for in situ Real-time Monitoring of Stomata and other Biological & Non-biological Applications

Purwar, Prashant 서울대학교 대학원 2019 국내박사

Commercial high-resolution optical microscopes are essential for microscopy imaging; however, they are expensive and bulky, which limits their use in point-of-care devices, resource-limited areas, and real-time imaging of a sample in a large apparatus. In this study, we report a novel compact lightweight submicron-resolution reflected and inverted optical microscope at low cost. Our technique utilizes the proximity of the image sensor to a commercial microscope objective lens for compactness of the microscope. The use of an image sensor with a small pixel size helps to reduce the information loss, which provides high-resolution images. Moreover, our technique offers a freedom to tailor the design of microscope according to the required resolution, cost, and portability for specific applications, which makes it a suitable candidate for affordable point-of-care devices. Unlike conventional reflected microscope, which consists of downward facing objective lens, our portable reflected microscope is designed with upward facing objective lens. Such configuration with high-resolution imaging capability and portability makes it suitable for imaging of abaxial (lower side) surface of a plant leaf. Stoma, functionally specialized micrometer-sized pores on the epidermis of leaves (mainly on the lower epidermis) were observed and analyzed. Since stomata control the flow of gases and water between the interior of the plant and atmosphere, real-time monitoring of stomatal dynamics can be used for predicting the plant hydraulics, photosensitivity, and gas exchanges effectively. To date, several techniques offer the direct or indirect measurement of stomatal dynamics, yet none offer real-time, long-term persistent measurement of multiple stomal apertures simultaneously of an intact leaf in a field under natural conditions. Our technique is capable of analyzing and quantifying the multiple lower epidermis stomal pore dynamics simultaneously and does not require any physical or chemical manipulation of a leaf. An upward facing objective lens in our portable microscope allows the imaging of lower epidermis stomatal opening of a leaf while upper epidermis being exposed to the natural environment. Small depth of field (~ 1.3 μm) of a high-magnifying objection lens assists in focusing the stomatal plane in highly non-planar tomato leaf having a high density of trichome (hair-like structures). For long-term monitoring, the leaf is fixed mechanically by a novel designed leaf holder providing freedom to expose the upper epidermis to the sunlight and lower epidermis to the wind simultaneously. In our study, a direct relation between the stomatal opening and the intensity of sunlight illuminating on the upper epidermis has been observed in real-time. In addition, real-time porosity of leaf (ratio between the areas of stomatal opening to the area of a leaf) and stomatal aspect ratio (ratio between the major axis and minor axis of stomatal opening) along with stomatal density have been quantified. Therefore, this portable and inexpensive microscopeic technique provides the essential functionalities of a bulky expensive high-performance microscope along with the specific applications at a lower cost. Images of several micron-to-submicron scale patterns and spherical beads are acquired to observe the resolution and quality of the images obtained using our microscope. In addition, we demonstrate the applications of our microscope in various fields such as recording of high-speed water microdroplet formation inside a microfluidic device, high-resolution live cell imaging inside an incubator, and real-time imaging of crack propagation in a sample under stretching by a material testing system (MTS).

Microstructure and Superelasticity of Ti-Zr-Hf-Ni-Co-Cu Multi-Component High Entropy Shape Memory Alloys

레흐만 이자즈 경상국립대학교 대학원 2025 국내박사

Multi-component high-temperature shape memory alloys (HTSMAs) with nominal compositions of Ti16.667Zr16.667Hf16.667Ni25Co10Cu15, Ti16.833Zr16.833 Hf16.833Ni24.834Co9.834Cu14.834, Ti17Zr17Hf17Ni24.667Co9.667Cu14.667 and Ti17.333Zr17.333Hf17.333Ni24.333Co9.333Cu14.333 (at%) were prepared by arc-melting and then microstructures, transformation temperatures, phase constituents and superelasticity were investigated by scanning electron microscope observation, differential scanning calorimetry, X-ray diffraction and dynamic mechanical analysis in tensile mode, respectively. The microstructure of solution-treated TiZrHfNiCoCu HTSMAs specimens consisted of (TiZrHf)(NiCoCu)-type matrix and (TiZrHf)2(NiCoCu)-type second phase. The area fraction of the second phase increased from 1.7% to 17.2% with the increase in (TiZrHf) content from 50 at% to 52 at%. The martensitic transformation start temperature of the solution-treated specimens increased from 53.5 °C to 188.7 °C with the increase in (TiZrHf) content from 50 at% to 52 at%. TiZrHfNiCoCu HTSMAs showed clear superelasticity in the solution-treated state. The superelastic recovery strain of solution-treated TiZrHfNiCoCu HTSMAs was in the range of 4.2–4.6% depending on the alloy composition. The effect of Mn content on microstructure and transformation behavior of TiZrHfNiCoCu multi-component high-entropy shape memory alloys were investigated. A new (TiZrHf)(NiCoCuMn)-type second phase along with (NiCoCuMn)-rich matrix and brittle (TiZrHf)2(NiCoCuMn)-type phase was observed in Ti16.667Zr16.667Hf16.667Ni25Co10Cu15-XMnX at.% (X = 0, 1, 3, 5 and 7) high-entropy shape memory alloys (HESMAs). The area fraction of (TiZrHf)2(NiCoCuMn)-type phase increased from 1.7 to 5.1% with increasing Mn content from 0 to 7 at.%. The area fraction of the (TiZrHf)(NiCoCuMn)- type phase increased from 1.9 to 17.2% with increasing Mn content from 3 to 7 at.%. The martensitic transformation start temperature decreased with the addition of Mn content up to 3 at.% and then increased with increasing Mn content from 3 at.% to 7 at.% and the total recovered strain decreased with increasing Mn content suggesting that the addition of Mn for Cu in Ti16.667Zr16.667Hf16.667Ni25Co10Cu15 alloy is not beneficial for transformation temperature and superelastic properties. The rapid solidification process is beneficial for increasing the transformation temperature and improving the superelastic properties of Ti-Ni-based alloy. Therefore, the microstructures, transformation temperatures and superelastic properties of the rapidly solidified Ti16.667Zr16.667Hf16.667Ni25Co10Cu15 HESMAs were investigated. The as-spun Ti16.667Zr16.667Hf16.667Ni25Co10Cu15 fibers were prepared by a rapid solidification process. The solution-treated Ti16.667Zr16.667Hf16.667Ni25Co10Cu15 alloy bulk specimen consisted of a (NiCoCu)-rich matrix, (TiZrHf)2(NiCoCu)-type phase and carbide, while the as-spun fiber specimen consisted of (TiZrHf)-rich matrix and carbide. The (TiZrHf)2(NiCoCu)-type phase is suppressed in the matrix of as-spun fibers due to the rapid solidification process. The martensitic transformation start temperature of the Ti16.667Zr16.667Hf16.667Ni25Co10Cu15 alloy increased from 53.5 ◦C to 91.5 ◦C and the total superelastic recovery strain increased from 4.6 % to 5.7% after the rapid solidification process. It is also well known that aging/annealing at moderate temperatures is widely used to improve the mechanical and functional properties of rapidly solidified Ti-Ni (thin films, ribbons, fibers, etc.) alloys. Therefore, as-spun (TiZrHf)50Ni25Co10Cu15 alloy fibers were aged at 400 ℃, 450 ℃ and 500 ℃ for 1.5 hours. The 400 ℃ aged (TiZrHf)50Ni25Co10Cu15 alloy fibers consisted of (TiZrHf)2(NiCoCu)-type precipitates and matrix, while the 450 ℃ and 500 ℃ aged fibers consisted of (TiZrHf)2(NiCoCu)3-type precipitates and matrix with some carbide particles. The martensitic transformation start temperature of the as-spun (TiZrHf)50Ni25Co10Cu15 alloy fiber decreased from 91.5 °C to 88.3 °C with increasing aging temperature up to 500°C. Both the aged and as-spun (TiZrHf)50Ni25Co10Cu15 alloy fiber specimens showed clear superelasticity with large superelastic recovered strains of 4.4%, 4.7% 5.3% and 5.7% depending on aging temperature.

Research on the Impact of High-tech Industries and FDI on China’s High- Quality Economic Development : A Spatial Panel Approach

YANG BINBIN 건국대학교 대학원 2025 국내박사

중국이 초강대국으로 성장하고 지속발전하기 위해서 경제의 고도화 된 발전이 중요한 전제조건이 되었으며, 이러한 차원에서 고품질 경제발전에 대한 관심이 제고되고 있다. 자주적인 핵심기술을 바탕으로 혁신을 주도하는 중국의 하이테크 산업은 고품질 경제발전의 내적 동력으로 작용한다. 전통산업과 비교할 때, 하이테크 산업은 기술 확산을 효과적으로 촉진하고 지역 간 경쟁과 부존 자원의 공유를 통해 산업 집적화를 빠르게 실현함으로서 지역 경제발전을 촉진 할 수 있다. 동시에 외국인 직접투자(FDI)의 유입은 중국 하이테크 산업발전에 필요한 자본을 지원하는 중요한 요인이다. FDI는 자본의 이전뿐만 아니라 기술의 이전을 촉진하여 중국의 과학기술 혁신과 산업구조 발전을 촉진하고 이는 궁극적으로 중국 경제의 고품질 발전을 견인하기 때문이다. 이에 더해 2020년 중국 정부가 제안한 “쌍순환”개념은 고품질 경제발전이 국내외 협력을 필요로 한다는 점을 더욱 강조하며, 정책적인 지원을 하고 있다. 이에 본 연구는 2009년부터 2022년까지 중국 31개성의 패널 데이터를 수집하여 고품질 경제발전 수준을 측정하고, “쌍순환”프레임워크 하에서 FDI와 하이테크 산업이 중국의 고품질 경제발전에 미치는 영향과 그 공간적 효과를 연구 분석하였다. 이를 통해 중국 경제의 고품질 발전 목표달성을 위한 이론적 근거와 정책적 제안을 제시하고자 노력하였다. 첫째, 경제 고품질 발전 지표에 대한 측정 및 분석을 통해 중국의 고품질 경제발전 수준이 전반적으로 꾸준한 상승 추세를 보이고 있고 동시에 공간적 이질성이 존재함을 확인하였다. 특히, 동부 지역의 고품질 경제발전이 기타 지역보다 높은 것으로 나타났다. 둘째, 고차원 고정효과 패널회귀 분석 결과, 중국의 하이테크 산업과 FDI가 고품질 경제발전에 상당한 긍정적 영향을 미치는 것으로 나타났다. 이는 하이테크 산업과 FDI의 증가가 고품질 경제발전 수준을 크게 향상시킬 수 있음을 의미한다. 또한 하이테크 산업의 R&D 투자와 중국의 인적 자본, 고정자본 투자 및 기술에 대한 외국인 투자가 고품질 경제발전을 촉진하는데 핵심적 역할을 했다는 것을 반영한다. 셋째, 공단 더빈모형(Spatial Durbin Model, SDM) 평가를 통해 하이테크 산업과 고품질 경제발전은 공간적 효과를 가지고 있으나, 하이테크 산업과 경제 고품질 발전은 강한 외부효과를 갖지 않았으며 반면, FDI와 고품질 경제발전은 부정적인 외부효과를 가진다는 결과가 나타났다. 이는 하이테크 산업이 강한 지역 집중성을 가지고 있음을 반증하는 결과이다. 또한 FDI와 고품질 경제발전의 부정적 외부효과는 주요 자원 경쟁, 산업 블랙홀 효과, 산업의 집적과 기술 확산의 불균형에 의해 나타나며, 이는 주변 지역의 경제발전을 일정수준에서 저해할 수 있다는 점이 확인되었다. 마지막으로 중국 하이테크 산업발전과 FDI는 고품질 경제발전과 관련하여 강한 이질성을 보였으며, 동부 지역에서는 보다 높은 이질성, 그리고 서부지역에서는 상대적으로 낮은 이질성을 나타냈다. 또한, 중부 및 동북 지역의 하이테크 산업과 FDI는 고품질 경제발전에 대한 강한 직접 효과와 외부효과를 보이지 않는 것으로 나타났다. 이러한 연구분석에 따라 본 연구에서는 ‘쌍순환’개념을 전제로 중국의 하이테크산업과 FDI 전략의 공동 추진을 통해 중국의 고품질 경제발전 달성이 필요하며, 이러한 정책을 추진하는 정책 입안가들에게 정책을 설계하기 위한 이론적 근거와 정책적 제언을 제공한다. 이론적 측면에서, 본 연구결과는 내/외부 순환의 연계가 경제 고품질 발전에 미치는 영향을 강조하고 있다. 또한 본 연구 결과는 지역간의 연계와 동시 자원 배분의 중요성을 다시 한번 부각하고 있다. 이를 바탕으로 정책적 시사점을 살펴보면, 첫째, 중국의 지속적인 고품질 경제발전을 위해서 하이테크 산업의 집적을 촉진하고 지역 간 조화로운 발전을 추진해야 한다. 둘째, 지역 간 사업 체인의 연계를 강화하고 FDI와의 시너지 효과를 극대화 할 수 있는 접점을 찾도록 노력해야 한다. 셋째, 외국인 투자환경을 업그레이드하여 다양한 분야, 고부가가치 분야에서 투자가 이루어 질 수 있는 질 좋은 투자생태계를 조성해야 한다. 마지막으로 글로컬 자원에서 국가간 협력이 진행되어야 하며, 내부적으로 지역 정부간의 협력을 강화하는 노력이 이루어져야 한다. China’s rapid economic growth over the past 40 years has reached a point in which its own sustainability has now come into question. This has prompted China to shift focus from speed of development to quality of development, an essential element for transitioning China into a modern society. As a result, in 2017 the concept of High-Quality Economic Development (HQED) was introduced. High-tech industries are the internal driving force behind HQED, as they are a leading industry for the independent creation of fundamental technologies. Compared to traditional industries, high-tech industries can effectively generate technological spillovers, accelerate industrial agglomeration, and boost regional economic development via inter-regional competitive effects and resource endowments. At the same time, foreign direct investment (FDI) provides the capital required to grow China's high-tech businesses. Likewise, FDI technology transfer helps China's scientific and technological innovation and its industrial structure, hence encouraging China's HQED. Furthermore, the Chinese government's 2020 "dual circulation" proposal highlights the importance of local and international cooperation in achieving the necessary quality of economic development required for transition to a modern society. As a result, this study collects panel data from 31 Chinese provinces from 2009 to 2022, measuring the level of HQED, and investigates the impact and spatial effects of FDI and high-tech industries on such development using the "dual circulation" framework. This provides a theoretical foundation underpinning recommendations for policy makers, enabling them to achieve the highest possible quality of economic development for China. In the first instance, measurement and analysis of the indicators of HQED, the “dual circulation” study shows that the overall quality of China’s economic development is fluctuating in an upward trend with spatial heterogeneity. Development in the eastern region is of a higher quality than in other regions. In the second instance, application of high-dimensional fixed effects panel regression show that China's high-tech industries and FDI significantly impact HQED. This indicates that expanding these businesses and attracting foreign direct investment will boost the quality of development. This reflects that the R&D investment of high-tech industries and foreign investors in China's human resources, capital, and technology have played a core role in promoting HQED. Thirdly, application of the Spatial Durbin Model (SDM) for evaluation of the quality of economic development demonstrates that high-tech industries and HQED have spatial implications and weak spillover benefits, with FDI and HQED indicating negative spillover effects. This demonstrates that high-tech industries have considerable regional concentration. Furthermore, the negative spillover effects of FDI and HQED are mostly shown in resource rivalry, the industrial siphon effect, imbalances in industrial agglomeration, and technical diffusion, all of which impede the economic development of neighboring areas. Lastly, China's high-tech industry development and FDI have strong heterogeneity in the impacts on the quality of economic development, showing a trend of high impact in the east and low impact in the west. In addition, the high-tech industries and FDI in the central and northeastern regions have little direct effects and spillover benefits on HQED. The findings of the study provide a useful theoretical foundation for policy recommendations, better enabling future theoretical research and policymakers to achieve HQED through the joint promotion of high-tech businesses and FDI initiatives under the dual circulation model. In terms of content illumination, the study's findings highlight the importance of the link between internal and external circulation in promoting HQED. They also underline the necessity of regional cooperation and efficient resource distribution. On this basis, policy recommendations are made from the following four perspectives: First, encouraging the consolidation of high-tech industries to achieve regional co-development. Second, improving cross-regional industrial chain coordination and thereby enhancing FDI spillovers. Third, improving the quality of international circulation by optimizing the foreign investment climate. The final recommendation encourages transnational regional economic integration and enhances regional cooperation. The main innovations of this study are listed below. In terms of content, this study employs the "dual circulation" theoretical framework to address a gap in the literature on the synergy between FDI and high-tech industries in HQED in China. In terms of methodology, this study utilizes SDM to investigate the geographical effects of FDI and high-tech industries on HQED.