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Between Engagement and Isolation: Population Genetics and Transnational Nationalism in South Korea
( Hyun Jaehwan ) 한국과학사학회 2020 한국과학사학회지 Vol.42 No.2
This paper examines the rise and fall of genetic research on the Korean population from the 1960s to the 1980s. The research program, which was mainly undertaken by Korean geneticists who worked at or graduated from the Department of Zoology, Seoul National University, was inherently nationalist in sentiment. Engaging with the recent literature in Cold War scientific collaboration in population genetics, this paper focuses on the role of transnational exchange in the shaping of this nationalist science in South Korea. It argues that the dynamics of opportunistic collaboration of the Korean geneticists with foreign researchers over three decades was one of the crucial factors in the emergence and eclipse of the research program. This study will contribute to the previous literature by illuminating the marginal nature of Korean geneticists’ collaboration and their ambivalent attitudes towards collaboration, and suggesting the needs to pay more attention to the multidimensional aspects of trans-national exchange during that period.
Kim, Hyun Chan,Mun, Seongcheol,Ko, Hyun-U,Zhai, Lindong,Kafy, Abdullahil,Kim, Jaehwan IOP 2016 Smart materials & structures Vol.25 No.7
<P>The use of renewable materials is essential in future technologies to harmonize with our living environment. Renewable materials can maintain our resources from the environment so as to overcome degradation of natural environmental services and diminished productivity. This paper reviews recent advancement of renewable materials for smart material applications, including wood, cellulose, chitin, lignin, and their sensors, actuators and energy storage applications. To further improve functionality of renewable materials, hybrid composites of inorganic functional materials are introduced by incorporating carbon nanotubes, titanium dioxide and tin oxide conducting polymers and ionic liquids. Since renewable materials have many advantages of biocompatible, sustainable, biodegradable, high mechanical strength and versatile modification behaviors, more research efforts need to be focused on the development of renewable smart materials.</P>
Ko, Hyun-U,Kim, Hyun Chan,Kim, Jung Woong,Zhai, Lindong,Jayaramudu, Tippabattini,Kim, Jaehwan Institute of Physics Publishing 2017 Smart materials & structures Vol.26 No.8
<P>This paper reports cellulose nanocrystal (CNC) based transparent and electroactive polyurethane (CPPU), suitable for actively tunable optical lens. CNC is used for high dielectric filler to improve electromechanical behavior of CPPU. For high transparency and homogeneous distribution of CNC in polyurethane, CNC-poly[di(ethylene glycol) adipate] is used to play a role of polyol and isocyanate salt. The fabricated CPPU exhibits high transparency (>90%) and 10% of electromechanical strain under 3 V <I>μ</I>m<SUP>−1</SUP> electric field. Mechanical, dielectric properties as well as physical and chemical characteristics are investigated to prove the electromechanical behavior of CPPU.</P>
Perspective and potential of smart optical materials
Choi, Sang H,Duzik, Adam J,Kim, Hyun-Jung,Park, Yeonjoon,Kim, Jaehwan,Ko, Hyun-U,Kim, Hyun-Chan,Yun, Sungryul,Kyung, Ki-Uk Institute of Physics Publishing 2017 Smart materials & structures Vol.26 No.9
<P>The increasing requirements of hyperspectral imaging optics, electro/photo-chromic materials, negative refractive index metamaterial optics, and miniaturized optical components from micro-scale to quantum-scale optics have all contributed to new features and advancements in optics technology. Development of multifunctional capable optics has pushed the boundaries of optics into new fields that require new disciplines and materials to maximize the potential benefits. The purpose of this study is to understand and show the fundamental materials and fabrication technology for field-controlled spectrally active optics (referred to as smart optics) that are essential for future industrial, scientific, military, and space applications, such as membrane optics, filters, windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, and flat-panel displays. The proposed smart optics are based on the Stark and Zeeman effects in materials tailored with quantum dot arrays and thin films made from readily polarizable materials via ferroelectricity or ferromagnetism. Bound excitonic states of organic crystals are also capable of optical adaptability, tunability, and reconfigurability. To show the benefits of smart optics, this paper reviews spectral characteristics of smart optical materials and device technology. Experiments testing the quantum-confined Stark effect, arising from rare earth element doping effects in semiconductors, and applied electric field effects on spectral and refractive index are discussed. Other bulk and dopant materials were also discovered to have the same aspect of shifts in spectrum and refractive index. Other efforts focus on materials for creating field-controlled spectrally smart active optics on a selected spectral range. Surface plasmon polariton transmission of light through apertures is also discussed, along with potential applications. New breakthroughs in micro scale multiple zone plate optics as a micro convex lens are reviewed, along with the newly discovered pseudo-focal point not predicted with conventional optics modeling. Micron-sized solid state beam scanner chips for laser waveguides are reviewed as well.</P>
Hyun Chan Kim,Debora Kim,Ji Yun Lee,Lindong Zhai,Jaehwan Kim 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.6 No.3
Long filament made with nanocellulose has been researched due to its eminent mechanical and physical properties for next generation of natural fiber reinforced polymer composites. Wet spinning process for long filament fabrication in conjunction with stretching method has advantages of high efficiency and low-cost. To fabricate homogeneous and strong cellulose nanofiber filament, this paper experimentally investigates the process parameters, including spinning speed, pre-dry temperature and inner diameter of needle. In addition to the spinning process, a mechanical stretching process is taken into account to further improve the mechanical properties of the cellulose nanofiber filament. The effects of wet spinning and stretching are evaluated by using scanning electron microscope, tensile test and 2D wide angle X-ray diffraction. As a result, the stretched cellulose nanofiber filament exhibits its Young’s modulus of 37.5 GPa and tensile strength of 543.1 MPa, which are significantly improved from the previous reports. All about the fabrication process, characterization and evaluation of the cellulose nanofiber filaments are illustrated.