An Analytic Study of Channeled substrate planar Phased Arrays

Butler,J.K.,Oh, Hwan Sool 건국대학교 부설 산업기술연구소 1986 논문집 Vol.11 No.-

CSP 레이저들의 線形 어레이들의 모우드에 대한 발진 波長과 利得特性을 나타내었다. 어레이 모우드들의 利得값들은 배열이 인접한 요소들의 場을 이용하여 계산된 복소 결합 계수들로 결정된다. 계산결과는 거의 실수값인 場을 가지는 index guided lasers에 대하여 最高次 어레이 모우드가 쉽게 발진함을 보았다. Far field radiation pattern에서, 단지 하나의 단일 로브빔만으로 이루어지는 基本 모우드는 모든 배열 모우드들 중 가장 낮은 모우드 利得을 가진다. 最高次 모우드와 基本 모우드들 사이에서 ??보다 적은 모우드 利得差를 가지며 이것은 약 20%의 光拘束因子에 대해서, 利得差는 근사적으로 ??의 활성층 利得에 해당한다. The lasing wavelengths and gain characteristics of the modes of linear arrays of channel-substrate-planar (CSP) lasers are presented. The gain values of array modes are determined from the complex coupling coefficients calculated using the fields of neighboring elements of the array. The computations show that for index guided lasers which have fields that are almost real valued, or have only slight phase curvature, the highest order array mode will have preferred oscillation. The inphase or fundamental mode which produces only one major lobe in the far-field radiation, will have the lowest modal gain of all array modes. Some of the devices discussed have modal gain differences, between the highest and fundamental modes, of less than ??. For optical field confinement factors of about 20%, this gain difference corresponds to active layer gains of approximately ??.

Computational materials design of crystalline solids

Butler, K.,Frost, J.,Skelton, J.,Svane, K.,Walsh, A. Royal Society of Chemistry 2016 Chemical Society reviews Vol.45 No.22

<P>The modelling of materials properties and processes from first principles is becoming sufficiently accurate as to facilitate the design and testing of new systems in silico. Computational materials science is both valuable and increasingly necessary for developing novel functional materials and composites that meet the requirements of next-generation technology. A range of simulation techniques are being developed and applied to problems related to materials for energy generation, storage and conversion including solar cells, nuclear reactors, batteries, fuel cells, and catalytic systems. Such techniques may combine crystal-structure prediction (global optimisation), data mining (materials informatics) and high- throughput screening with elements of machine learning. We explore the development process associated with computational materials design, from setting the requirements and descriptors to the development and testing of new materials. As a case study, we critically review progress in the fields of thermoelectrics and photovoltaics, including the simulation of lattice thermal conductivity and the search for Pb-free hybrid halide perovskites. Finally, a number of universal chemical-design principles are advanced.</P>

Final report on APMP.RI(I)-K1: APMP/TCRI key comparison report of measurement of air kerma for ⁶⁰Co gamma-rays

Chun, K J,Butler, D J,Webb, D,Mahant, A K,Meghzifene, A,Lee, J H,Hah, S H,Kadni, T B,Zhang, Y,Kurosawa, T,Msimang, Z L M,Caseria, E S Springer-Verlag 2013 METROLOGIA -BERLIN- Vol.50 No.-

<P>The APMP.RI(I)-K1 key comparison of the measurement standards of air kerma for <SUP>60</SUP>Co gamma-rays was undertaken by the APMP/TCRI Dosimetry Working Group between 2004 and 2006, coordinated by the Korean Research Institute of Standards and Science (KRISS). In total, 10 institutes took part in the comparison, among which 7 were APMP member laboratories. Three Farmer-type commercial cavity chambers were used as transfer chambers and circulated among the participants. All the participants carried out their measurements according to the guidelines for the comparison established by the KRISS with the cooperation of the ARPANSA. For each transfer chamber, an NMI calibration coefficient was obtained and a ratio derived by dividing by the average result from the linking laboratories, ARPANSA and NMIJ. The APMP comparison reference value for each chamber was calculated as the mean of the NMI-determined calibration coefficients divided by the average result from the linking laboratories. The results showed that the maximum difference between the APMP linked ratio of a participating NMI and the APMP reference value was 1.76%.</P><P>The measured ratios of the calibration coefficient R<SUB>NMI, BIPM</SUB> between the participating NMI and the BIPM via the link laboratories for the transfer chambers were obtained. The maximum expanded uncertainty of R<SUB>NMI, BIPM</SUB> for any participating laboratory was 2.0%.</P><P>The degree of equivalence of each participating laboratory with respect to the key comparison reference value was also evaluated. The expanded uncertainty of the difference between the results ranged from 0.5% to 1.2%. The pair-wise degree of equivalence between each pair of laboratories was also obtained and the largest difference of the expanded uncertainty of the difference for any pair-wise degree of equivalence was within the expanded uncertainty of the measurement for the pair of laboratories.</P><P>Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.</P><P>The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>

Chemical bonding at the metal-organic framework/metal oxide interface: simulated epitaxial growth of MOF-5 on rutile TiO2

Bristow, J.,Butler, K.,Svane, K.,Gale, J.,Walsh, A. Royal Society of Chemistry 2017 Journal of materials chemistry. A, Materials for e Vol.5 No.13

<P>Thin-film deposition of metal-organic frameworks (MOFs) is now possible, but little is known regarding the microscopic nature of hybrid hetero-interfaces. We first assess optimal substrate combinations for coherent epitaxy of MOFs based on a lattice matching procedure. We then perform a detailed quantum mechanical/molecular mechanical investigation of the growth of (011) MOF-5 on (110) rutile TiO2. The lowest energy interface configuration involves a bidentate connection between two TiO6 polyhedra with deprotonation of terephthalic acid to a bridging oxide site. The epitaxy of MOF-5 on the surface of TiO2 was modelled with a forcefield parameterised to quantum chemical binding energies and bond lengths. The microscopic interface structure and chemical bonding characteristics are expected to be relevant to other hybrid framework-oxide combinations.</P>

ARRAY MODE CHARACTERISTICS OF CHANNELED SUBSTRATE-PLANAR PHASE ARRAYS

오환술,J.K.Butler 대한전자공학회 1986 대한전자공학회 학술대회 Vol.1986 No.1

ARRAY MODE CHARACTERISTICS OF CHANNELED-SUBSTRATE-PLANAR PHASE ARRAYS

hwan sool Oh,J.K. Butler 대한전자공학회 1986 대한전자공학회 학술대회 Vol.1986 No.6

The X-ray counterpart to the gravitational-wave event GW170817

Troja, E.,Piro, L.,van Eerten, H.,Wollaeger, R. T.,Im, M.,Fox, O. D.,Butler, N. R.,Cenko, S. B.,Sakamoto, T.,Fryer, C. L.,Ricci, R.,Lien, A.,Ryan Jr, R. E.,Korobkin, O.,Lee, S.-K.,Burgess, J. M.,Lee, Nature Publishing Group 2017 Nature Vol. No.

A long-standing paradigm in astrophysics is that collisions—or mergers—of two neutron stars form highly relativistic and collimated outflows (jets) that power γ-ray bursts of short (less than two seconds) duration. The observational support for this model, however, is only indirect. A hitherto outstanding prediction is that gravitational-wave events from such mergers should be associated with γ-ray bursts, and that a majority of these bursts should be seen off-axis, that is, they should point away from Earth. Here we report the discovery observations of the X-ray counterpart associated with the gravitational-wave event GW170817. Although the electromagnetic counterpart at optical and infrared frequencies is dominated by the radioactive glow (known as a ‘kilonova’) from freshly synthesized rapid neutron capture (r-process) material in the merger ejecta, observations at X-ray and, later, radio frequencies are consistent with a short γ-ray burst viewed off-axis. Our detection of X-ray emission at a location coincident with the kilonova transient provides the missing observational link between short γ-ray bursts and gravitational waves from neutron-star mergers, and gives independent confirmation of the collimated nature of the γ-ray-burst emission.