based on comparison with Israel, France and UK

Thesis(Master) --KDI School:Master of Public Policy,2016The purpose of this study is to review the transformation trend of other advanced nations’ defense GRIs cases and find some implications that can be applied to the Republic of Korea (“ROK”) defense Government Research Institutes (“GRIs”). In order to prepare for future warfare and military tension with military powers and North Korea, the ROK should secure its own core and strategic technology through efficient defense Research and Development (“R&D) policy. Through case study and comparison study between Korea and three advanced nations (France, the UK and Israel), this paper suggests 3 main implications. First of all, a special defense GRI which is in charge of core and strategic defense R&D is required. Secondly, the ROK defense industry should develop their own defense R&D capacity and lead practical R&D for weapon system projects. Government and GRI support are essential to strengthening Korean defense industries’ competitiveness. Thirdly, entire governance reform is required for ultimate change. To deal with the current ROK defense R&D issues and conduct consistent defense R&D procedure, some parts of three GRIs(DAPA, ADD and DTAQ) should be merged or relocated under MOD.Ⅰ. Chapter 1: Introduction Ⅱ. Chapter 2: Literature Review Ⅲ. CHAPTER 3: Case Study Ⅳ. Chapter 4: Comparison Study Ⅴ. Chapter 5: ConclusionOutstandingmasterpublishedSooyoon HWANG

Atomic Scale Analysis of the Origin in Highly Enhanced Thermal Stability of Lead-Free Piezoelectric Ceramics

1

Atomic-scale analysis of the origin in highly enhanced thermal stability of lead-free piezoelectric ceramics

2

Highly enhanced thermal stability in lead-free piezoelectric ceramics by polar order engineering

2

3-Dimensional Analysis of Ferroelastic Twin Structures in Epitaxial WO3 Thin Films with TEM&STEM

1

Highlyenhancedthermalstabilityinlead-freepiezoelectricceramicsbygrainsizeengineering

2

Highly enhanced thermal stability in lead-free piezoelectric ceramics by grain size engineering

2

STEM observation and diffraction pattern analysis f crystal structure of room temperature vdW ferromagnet

2

Atomic scale analysis of the origin in high performance and stability of lead free piezoelectric ceramics

2

Thermal Stability Enhanced by Short-range Ordered Ferroelectricity in K0.5Na0.5NbO3-based Oxide

Lead-free piezoelectric ceramics have been widely investigated as a replacement for the lead-based piezoelectric materials due to the toxicity and environmental issues of lead. However, the temperature ranges at which the lead-free piezoelectric ceramics can maintain piezoelectric properties is limited below 200°C, and the loss of piezoelectricity is still large within that temperature range. This lack of thermal stability of lead-free piezoelectric ceramics has hindered their use at high temperature environment. In this study, we report lead-free (K,Na)NbO3 (KNN)-based system with remarkably enhanced thermal stability of piezoelectric properties with little loss up to 300°C by exploiting grain size. We synthesized a set of BiScO3 (BS)-doped KNN-based ceramics with a meticulous BS doping control near the optimal chemical composition [1] predicted based on the phase-field simulations and first principles calculations. Through comprehensive evaluation of microstructure by (scanning) transmission electron microscopy ((S)TEM), we demonstrated the correlation of grain size and thermal stability. In addition, we realized the applicability of the thermally stable actuating devices composed of KNN ceramics, and confirmed that the thermal stability of KNN-based ceramics is well reflected when fabricated as devices. This is the first time to achieve lead-free piezoelectric ceramics with an outstanding thermal stability up to 300°C and suggest an applicability as an actual device with highly stable piezoelectricity. [1] M. K. Lee, S. A. Yang, J. J. Park, & G. J. Lee. (2019). Proposal of a rhombohedral-tetragonal phase composition for maximizing piezoelectricity of (K,Na)NbO3 ceramics. Scientific Reports, 9(1), 4195.2