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We calculated the transition of edge pedestal properties in jϕ-α space for a KSTAR-like plasma and compared the results with those from the analytical transition model. The transition is from a critical equilibrium that is marginally stable to the peeling or the ballooning mode to another critical equilibrium when plasma parameters such as triangularity, elongation, and βp change. The transition should not be confused with the L-H transition. We have divided the transition into two. The first transition is when plasma parameters change for fixed pedestal width while the second transition is when the pedestal width changes for fixed plasma parameters. The direction of the first transition when triangularity or elongation increases is as such that jϕ decreases and α increases. The direction of the first transition with varying βp depends on the choice of how the temperature or the current density is modified. The direction of the second transition is determined from the stability condition of the new equilibrium after the first transition.

We constructed an underground laboratory called Cheongpyeong Underground Radiation Laboratory (CURL) for measuring the radioactivity levels of various samples by using HPGe detectors. CURL is located underground at a depth of 1000-m water equivalent in the Cheongpyeong Pumped Storage Power Plant. We developed a shielding system, which consists of 15-cm-thick Pb blocks and 5-cm-thick Cu blocks and completely surrounds a 100% HPGe detector. We measured the background radiations and the gamma peaks from sources with and without the shield. The shielding efficiencies were also estimated using MCNP5 simulations, and they were compared to our measured data. The shielding system blocked more than 99.99% of gamma rays with energies up to 3.0 MeV. The HPGe detector with the shielding system at CURL blocked both high-energy cosmic rays and background radiation from surrounding rocks and materials. Our CURL detector system was optimized for gamma-ray measurements of meterials with ultra-low radioactivity.

ZnO transparent conductive electrodes (TCEs) embedded with Pt nanoclusters were developed for the fabrication of reliable and efficient GaN-based light-emitting diodes (LEDs). The 200-nmthick ZnO films sputtered on Pt nanoclusters showed good TCE performance, i.e., a specific contact resistance of ∼10−5 Ωcm2, a sheet resistance of 50 Ω/sq, and an optical transmittance of 81.5% at 450 nm. LEDs fabricated with the ZnO TCEs embedded with Pt nanoclusters showed lower forward voltages and improved device reliability as compared to the reference LEDs fabricated with pure ZnO TCEs. This is attributed to the role of the interfacial Pt nanoclusters, suppressing the generation of sputtering surface damage on p-GaN and hence enhancing the carrier transport via Ohmic formation.

The efficiencies of the fueling system in the KSTAR have been studied for the 2013 experimental results. The absolute amount of injected fuel or deuterium has been calibrated in advance of the main plasma experiments. This includes the primary actuator of fueling, i.e., gas puffing (GP) with piezoelectric valves located on mid-plane, and supersonic molecular beam injector (SMBI). In addition, neutral beam injectors (NBIs) and their base facility chamber also contribute to the amount of fuel injection whenever they are operated. Low fueling efficiency combined with particle loss due to wall retention essentially results in poor performance of density feedback control magnetic fusion devices such as the KSTAR.

As semiconductor devices currently are integrated with high density, they are converted into 3-dimensional form. The interconnections between the layers of the devices are linked through via holes which have diameters of a few hundred nanometers and depths on a micrometer scale, typically. This kind of deep via hole scanning in 3 dimension has become a key issue in semiconductor industry. The only non-destructive method to image it directly is critical-dimension atomic force microscopy (CD-AFM) with a long probing tip. The concept of CD-AFM was suggested by other groups, but a substantial scanning algorithm has not been released yet. We suggest an algorithm, which is composed of a raster scanning and a vector scanning, for scanning samples including many via holes. If a feedback scheme with amplitude-detection mode is used, 3-dimensional scanning can be completed within a few conventional raster scannings.

We developed a reflection polarization convertor by using the conventional metamaterial absorber. The metal-dielectric-metal sandwich structure, in which copper split ring at the front and metallic plane at the back are separated by FR-4, was employed to investigate for the GHz regime. This shows that a broadband of 14–18 GHz with reflectance of 36–55% is converted to 90°-polarization mode, while the original one is nearly harvested (absorption of 95–100%). In other words, the original electromagnetic (EM) wave is “perfectly” absorbed and partly emitted as 90°-twisted EM wave, and the remaining is dissipated as heat.

We propose a broadband reflective metamaterial polarization converter which is composed of arrays of split-ring resonators (SRRs), a dielectric layer and a continuous metallic layer. For the case of a loss-free dielectric layer, the average transformation rate is around 90% at frequencies from 6.68 to 10.91 GHz, and the bandwidth is 56.66% of the central wavelength. The increased loss tangent of the dielectric layer is shown to induce a reduced transformation rate due to enhanced absorption.

We report on the magneto-optical and the magnetic properties of 2-dimensional (2-D) spin photonic crystals (SPCs), which were fabricated using photolithography and wet-etching processes. Circular-shape holes with rhomboidal lattice symmetry were grooved into the top ferromagnetic layer composed of Co while the bottom Ni layer was kept unpatterned. Such structures having the same lattice symmetry but different periodicities (viz., 1.3 and 1.6 µm) were investigated using magneto-optical Kerr effects (MOKE) measurements. The change in periodicity was found to be useful in tailoring the magnetic properties. An in-plane easy-axis magnetization was observed for both samples. Significant enhancement of the switching field by nearly 2.5 times was noticed for the sample having smaller periodicity. This is attributed to a change in the magnetostatic energy due to the varied lateral dimension. Additionally, the MO measurement showed a strong dependence on the incident angle. These experimental results manifest the ability of controlling the MO, as well as the magnetic, properties of 2-D SPCs by modifying the periodicity and by forming a bilayer structure.

We fabricated a 2-dimensional spin lattice of circular anti-dots on a silicon substrate by using the photolithography and the wet-etching techniques. A rhomboid lattice symmetry of anti-dots with a diameter of about 1 μm was formed in a 40-nm-thick Co layer with a 5-nm-thick Ni underlayer. The magnetic anisotropy was investigated by using magneto-optical Kerr-effect magnetometry to identify the easy and the hard axes. A systematic study of the magnetic-reversal process was performed using magnetization and magneto-transport measurements with the field applied along the hard axis of the lattice. Anomalous features, a 3-step transition of the magnetization, a nonmonotonous temperature dependence of the coercive field, and a complex behavior of the magneto-resistance data, were observed in the magnetic-reversal process. We speculate that these anomalies originate from the vortex-related phenomena that are inherent in the submicrostructures.

The growth of an AlGaN-based non-phosphor white light emitting diode (LED) on a templated n-GaN (0001) sapphire substrate is performed by using mixed-source hydride vapor phase epitaxy (HVPE) with a multi-sliding boat. The DH (doublehetero) structure is grown by using a selective area growth (SAG) method. The non-phosphor white LED structure consists of a Te-doped AlGaN cladding layer, an AlGaN active layer, a Mg-doped AlGaN cladding layer and a Mg-doped GaN capping layer. The gas ow rates of HCl and NH3 are maintained at 20 sccm and 800 sccm, respectively. The growth temperatures of the source zone and the growth zone are 900 C and 1090 C, respectively. The electroluminescence (EL) main peak of the AlGaN-based white LED is observed at 400 nm and minor peaks are emitted in a broad spectrum from 450 nm to 600 nm. A combination of blue and broadband yellow peaks creates a white light. The non-phosphor white LED has a measured color rendering index (CRI) from 76 to 87. These results show mixed-source HVPE with a multi-sliding boat can be used to fabricate a non-phosphor white LED. Additionally, optical module measurements and X-ray di raction (XRD) veri ed the optical and the crystal quality of the white LED.

The neutral-current neutrino-nucleus scattering is calculated through the neutrino-induced knocked-out nucleon process in the quasielastic region by using a relativistic single particle model for the bound and continuum states. The incident energy range between 500 MeV and 1.0 GeV is used for the neutrino (antineutrino) scattering on the 12 C target nucleus. The effects of the final state interaction of the knocked-out nucleon are studied not only on the cross section but also on the asymmetry due to the difference between neutrinos and antineutrinos, within a relativistic optical potential. We also investigate the sensitivity of the strange quark contents in the nucleon on the asymmetry. (Some figures in this article are in colour only in the electronic version)

We fabricated a magnetic field sensor made of an InAs quantum-well. Various numbers of magnetic particles were located on the sensor and the stray field generated by the magnetic particles was detected using micro-Hall magnetometry at room temperature. A numerical calculation carried out for this device successfully explained the experimental results and a useful equation relating the signal of the device and the number of particles was deduced.

interfacial regions in Fe/Si multilayers to their magneto-optical and optical properties has been investigated by using magnetooptical and optical spectroscopies. The experimental spectra were compared with the computersimulated ones assuming various stoichiometries for the nonmagnetic spacer separating the antiferromagnetically coupled Fe layers. A reasonable agreement between experimental and simulated equatorial-Kerr-eect spectra was obtained by using the tted optical parameters of the spacer for FeSi and Fe5Si3 stoichiometries. In contrast to FeSi2 or FeSi, the tted optical properties of the spacer show a typical metallic behavior. In order to determine the exact chemical composition of the spacer we are performing rst-principles calculations for various silicides, as well as additional experiments.

The electronic structures of α-Fe (bcc structure) and γ-FeMn (L10 structure) were calculated by using the all-electron full-potential linearized-augmented-plane-wave method within the generalizedgradient approximation. Both diagonal and off-diagonal components of the optical-conductivity (OC) tensor were calculated from the calculated electronic structures. The calculated OC spectra, both diagonal and off-diagonal, are compared with the experimental spectra of pure Fe, Mn-diluted (2.5 at.% of Mn concentration) Fe alloy film, and near-equiatomic FexMn1−x alloy films with x = 0.642 and 0.409. By applying the so-called λ-fitting, which simulates the effects of the real part of self-energy, the calculated OC spectra can successfully reproduce the experimental ones.

In this study, the chemical and nanomechanical characteristics of fluorocarbon (FC) films deposited by using plasma-enhanced chemical vapor deposition on Al were evaluated to apply them as antistiction layers. The calculated deposition rate with C4F8 was 325 nm/min at an optimized process condition of 10 sccm, 30 W, and 340 mTorr. The contact angles of the FC thin films on Al were around 110 , regardless of the deposition time. The surface energies were around 14 mN/m, and the contact angle hysteresis was lower than 35 . FTIR-ATR (Fourier transform infrared attenuated total reflection) spectra showed the presence of fluorocarbon groups. The adhesion and friction force after FC film deposition showed lower and more stable values than those of bare Al. Depositing the FC films at powers above 50 W increased the hysteresis, the adhesion force, the roughness and the friction force. The addition of Ar resulted in a decrease in the thickness of the FC film during deposition. The deposited FC films gradually decomposed at 200 C.