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We present a derivation of the Schwinger parametrization and the Feynman parametrization in detail and their elementary applications. Although the parametrizations are essential to computing the loop integral arising in relativistic quantum field theory, their detailed derivations are not presented in usual textbooks. Beginning with an integral representation of the unity, we derive the Schwinger parametrization by performing multiple partial derivatives and utilizing the analyticity of the gamma function. The Feynman parametrization is derived by the partial-fraction decomposition and the change of variables introducing an additional delta function. Through the extensive employment of the analyticity of a complex function, we show the equivalence of those parametrizations. As applications of the parametrizations, we consider the combinatorial factor arising in the Feynman parametrization integral and the multivariate beta function. The combinatorial factor corresponds to an elementary integral embedded in the time-ordered product of the Dyson series in the time-dependent perturbation theory. We believe that the derivation presented here can be a good pedagogical example that students enhance their understanding of complex variables and train the use of the Dirac delta function in coordinate transformation.

We derive the formulas for the energy and wavefunction of the time-independent Schrödinger equation with perturbation in a compact form. Unlike the conventional approaches based on Rayleigh–Schrödinger or Brillouin–Wigner perturbation theories, we employ a recently developed approach of matrix-valued Lagrange multipliers that regularizes an eigenproblem. The Lagrange-multiplier regularization makes the characteristic matrix for an eigenproblem invertible. After applying the constraint equation to recover the original equation, we find the solutions of the energy and wavefunction consistent with the conventional approaches. This formalism does not rely on an iterative way and the order-by-order corrections are easily obtained by taking the Taylor expansion. The Lagrange-multiplier regularization formalism for perturbation theory presented in this paper is completely new and can be extended to the degenerate perturbation theory in a straightforward manner. We expect that this new formalism is also pedagogically useful to give insights on the perturbation theory in quantum mechanics.

We employ the barycentric coordinate system to evaluate the inertia tensor of an arbitrary triangular plate of uniform mass distribution. We find that the physical quantities involving the computation are expressed in terms of a single master integral over barycentric coordinates. To expedite the computation in the barycentric coordinates, we employ Lagrange undetermined multipliers. The moment of inertia is expressed in terms of mass, barycentric coordinates of the pivot, and side lengths. The expression is unique and the most compact in comparison with popular expressions that are commonly used in the field of mechanical engineering. A master integral that is necessary to compute the integral over the triangle in the barycentric coordinate system and derivations of the barycentric coordinates of common triangle centers are provided in appendices. We expect that the barycentric coordinates are particularly efficient in computing physical quantities like the electrostatic potential of a triangular charge distribution. We also illustrate a practical experimental design that can be immediately applied to general-physics experiments.

We employ the generating-function representation for an n-dimensional vector in Euclidean or Hilbert space to evaluate scalar products. The generating function is constructed as a power series in a complex variable weighted by the components of a vector. The scalar product is represented by a convolution of the generating functions for the vectors integrated over a closed contour in the complex plane. The analyticity of the generating functions associated with the Laurent theorem reduces the evaluation of the scalar product into counting combinatoric multiplicity factors. As applications, we provide two exemplary computations: the sum of the squares of integers and the normalization of normal modes in a vibrating loaded string. As a byproduct of the latter example, we find a new alternative proof of a famous trigonometric identity that is essential for Fourier analyses.

We present a generating-function representation of a vector defined in either Euclidean or Hilbert space with arbitrary dimensions. The generating function is constructed as a power series in a complex variable whose coefficients are the components of a vector. As an application, we employ the generating-function formalism to solve the eigenproblem of a vibrating string loaded with identical beads. The corresponding generating function is an entire function. The requirement of the analyticity of the generating function determines the eigenspectrum all at once. Every component of the eigenvector of the normal mode can be easily extracted from the generating function by making use of the Schlafli integral. This is a unique pedagogical example with which students can have a practical contact with the generating function, contour integration, and normal modes of classical mechanics at the same time. Our formalism can be applied to a physical system involving any eigenvalue problem, especially one having many components, including infinite-dimensional eigenstates.

We recently demonstrated a repurposing beneficial effect of 4-aminopyridine (4-AP), a potassium channel blocker, on functional recovery and muscle atrophy after sciatic nerve crush injury in rodents. However, this effect of 4-AP is unknown in nerve transection, gap, and grafting models. To evaluate and compare the functional recovery, nerve morphology, and muscle atrophy, we used a novel stepwise nerve transection with gluing (STG), as well as 7-mm irreparable nerve gap (G-7/0) and 7-mm isografting in 5-mm gap (G-5/7) models in the absence and presence of 4-AP treatment. Following surgery, sciatic functional index was determined weekly to evaluate the direct in vivo global motor functional recovery. After 12 weeks, nerves were processed for whole-mount immunofluorescence imaging, and tibialis anterior muscles were harvested for wet weight and quantitative histomorphological analyses for muscle fiber cross-sectional area and minimal Feret's diameter. Average post-injury sciatic functional index values in STG and G-5/7 models were significantly greater than those in the G-7/0 model. 4-AP did not affect the sciatic functional index recovery in any model. Compared to STG, nerve imaging revealed more misdirected axons and distorted nerve architecture with isografting. While muscle weight, cross-sectional area, and minimal Feret's diameter were significantly smaller in G-7/0 model compared with STG and G-5/7, 4-AP treatment significantly increased right TA muscle mass, cross-sectional area, and minimal Feret's diameter in G-7/0 model. These findings demonstrate that functional recovery and muscle atrophy after peripheral nerve injury are directly related to the intervening nerve gap, and 4-AP exerts differential effects on functional recovery and muscle atrophy.

We present a four-vector analogue Uμ ≡ (U0, U) = (|V′|, V) that can be directly constructed from the velocity of a projectile. Here, V and V′ are the velocities of a projectile at heights h + H and h, respectively. In the non-relativistic regime, the mathematical structure of this four-vector analogue has an exact correspondence to the relativistic counterpart four-velocity uμ = γ(1, β)c of a massive particle. Based on this observation, we illustrate the design of an introductory laboratory experiment to investigate the Lorentz invariance and its covariant nature by measuring the velocity of a projectile. The experiment may help students to acquire a concrete perspective of Lorentz covariance through their own measurements and analyses of a free-fall motion.

This paper presents the results of the first intercomparison exercise performed by the Korea retrospective dosimetry (KREDOS) working group using electron paramagnetic resonance (EPR) spectroscopy. The intercomparison employed the alanine dosimeter, which is commonly used as the standard dosimeter in EPR methods. Four laboratories participated in the dose assessment of blind samples, and one laboratory carried out irradiation of blind samples. Two types of alanine dosimeters (Bruker and Magnettech) with different geometries were used. Both dosimeters were blindly irradiated at three dose levels (0.60, 2.70, and 8.00 Gy) and four samples per dose were distributed to the participating laboratories. Assessments of blind doses by the laboratories were performed using their own measurement protocols. One laboratory did not participate in the measurements of Magnettech alanine dosimeter samples. Intercomparison results were analyzed by calculating the relative bias, En value, and z-score. The results reported by participating laboratories were overall satisfactory for doses of 2.70 and 8.00 Gy but were considerably overestimated with a relative bias range of 10–95% for 0.60 Gy, which is lower than the minimum detectable dose (MDD) of the alanine dosimeter. After the first intercomparison, participating laboratories are working to improve their alanine-EPR dosimetry systems through continuous meetings and are preparing a second intercomparison exercise for other materials.

In the present study, improved two-parameter mixed models for large eddy simulations are proposed based on previous two-parameter mixed models of Salvetti and Banerjee [1] and Horiuti [2]. The subgrid-scale (SGS) stress in our models is decomposed into the modified Leonard stress, modified cross stress and modified SGS Reynolds stress terms. Although the modified Leonard stress term is explicitly calculated based on the scale-similarity, the modified cross stress term is built using an extension of the filtered Bardina model proposed by Horiuti [3] for better predictions of the interaction between resolved and unresolved scales (i.e., energy exchange). The modified SGS Reynolds stress is modeled by the dynamic Smagorinsky model or by a dynamic global model, leading to two unknown model coefficients for the modified cross stress and the modified SGS Reynolds stress terms. In order to demonstrate the reliability of the proposed SGS models, large eddy simulations of two types of flows (i.e., a fully developed turbulent channel flow and a transitional boundary layer flow) are performed. It is shown that the modified cross stress term makes an important contribution to the accurate predictions of such flows because the emergence of negative SGS dissipation (backward scatter) by the modified cross stress term decreases the excessive positive SGS dissipation (forward scatter). A direct comparison of the turbulent statistics with those from previous SGS models shows that the proposed SGS models result in better prediction performance both in transitional and turbulent flows.

We discuss vacuum structure and vacuum stability in classically scale-invariant renormalizable models with a scalar dark matter multiplet of global O(N) symmetry together with an electroweak singlet scalar mediator. Our conformally invariant scalar potential generates the electroweak symmetry breaking via the Coleman-Weinberg mechanism, and the new scalar singlet mediator acquires its mass through radiative corrections of the scalar dark matters as well as of the standard model particles. Taking into account the present collider bounds, we find the region of parameter space where the scalar potential is stable and all the massless couplings are perturbative up to the Planck scale. With the obtained parameter sets satisfying the vacuum stability condition, we present the allowed region of new physics parameters satisfying the recent measurement of relic abundance, and predict the elastic scattering cross section of the new scalar multiplet into target nuclei for a direct detection of the dark matter. We also discuss the collider signatures and future discovery potentials of the new scalars., 11 pages, 6 figures (partly updated), journal version. arXiv admin note: text overlap with arXiv:1904.10209

We show how to compute directly the renormalization/evolution of the radiative jet function that appears in the factorization theorems for $B\to \gamma\ell\nu$ and $H\to \gamma\gamma$ through a $b$-quark loop. We point out that, in order to avoid double counting of soft contributions, one should use in the factorization theorems a subtracted radiative jet function, from which soft contributions have been removed. The soft-contribution subtractions are zero-bin subtractions in the terminology of soft-collinear effective theory. We show that they can be factored from the radiative jet function and that the resulting soft-subtraction function gives rise to a nonlocal renormalization of the subtracted radiative jet function. This is a novel instance in which zero-bin subtractions lead to a nonlocality in the renormalization of a subtracted quantity that is not present in the renormalization of the unsubtracted quantity. We demonstrate the use of our formalism by computing the order-$\alpha_s$ evolution kernel for the subtracted radiative jet function. Our result is in agreement with the result that had been inferred previously by making use of the factorization theorem for $B\to \gamma\ell\nu$, but that had been ascribed to the unsubtracted radiative jet function., Comment: 34 pages, 4 figures, substantial clarifications to the discussions, version published in PRD

In the present study, we perform an active proportional (P) feedback control of laminar and turbulent flows over a circular cylinder with an averaged velocity sensor to reduce its drag and lift fluctuations. As a sensor for the feedback control, we adopt an averaged transverse velocity on the centerline of the wake. For the averaging of the transverse sensing velocity, we consider both temporal averaging over a finite period and spatial averaging in the spanwise direction. As a control input, the blowing/suction actuation is provided on the cylinder surface near the flow separation, and its magnitude is linearly proportional to the averaged transverse sensing velocity. With the control, the fluctuations of the transverse sensing velocity are significantly reduced and the vortices right after the cylinder and the Kármán vortex shedding in the wake are weakened, resulting in substantial reductions of the mean drag and lift fluctuations. Furthermore, it is shown that the adoption of the averaged sensing velocity makes the P control successful for a wider range of sensing locations in laminar flow at Re = 100 and is essential for the success of the P control in turbulent flow at Re = 3900. With the optimal control parameters, the reductions of the mean drag and lift fluctuations for turbulent flow at Re = 3900 are about 11% and 61%, respectively. The present P control maintains the magnitude of the blowing/suction actuation less than 1% of the free-stream velocity, and thus, the control input power is very small, leading to an excellent control efficiency.

It remains unclear whether atherosclerotic plaque structure or composition is related to translesional biomechanical stresses in coronary artery disease. The aim of this study was to evaluate the association between translesional pressure parameters (using a pressure wire) and plaque characteristics (using a combined near-infrared spectroscopy [NIRS] and intravascular ultrasound [IVUS] imaging catheter).Fractional flow reserve (FFR), delta (Δ) FFR, and Δ pressure were obtained during adenosine-induced maximum hyperemic status. Lipid core burden index (LCBI) and maximum LCBI within 2 mm (maxLCBI2mm) and tomographic anatomy were evaluated by NIRS-IVUS.Sixty-six lesions from 57 patients were analyzed (57 lesions for FFR, 45 lesions for ΔFFR). There was a negative correlation between FFR and maxLCBI2mm (r=-0.264; P=.049) and a positive correlation between ΔFFR and maxLCBI2mm (r=0.299; P=.049). ΔFFR of lesions with maxLCBI2mm ≥500 was significantly higher than maxLCBI2mm500 (0.159 ± 0.085 vs 0.104 ± 0.075, respectively; P=.04). By receiver-operating characteristic curve analysis, ΔFFR ≥0.1 was a predictor for maxLCBI2mm ≥500 (area under curve, 0.707; 95% confidence interval, 0.552-0.862; P=.03). On multivariate analysis, ΔFFR was the only predictor of maxLCBI2mm (β=0.347; P=.03).ΔFFR across a coronary artery lesion is related to lipid core burden assessed using NIRS-IVUS and might be a meaningful predictor of high-risk plaque (plaque with high lipid content).

Forty mobile phones using active-matrix organic light-emitting diode (AMOLED) display glasses were tested as emergency dosimeters. The target material was a substrate glass for AMOLED layers located under a cover glass. The measured thermoluminescence (TL) emission spectra and glow curves showed that the glasses are all included in category A and B of a previous study, and the ratio between category A and B was about 8 to 2 for all measured samples. A pre-bleach was applied for 500 s, and TL signals were acquired by measuring the whole wavelength region by removing a UV filter (U-340). This was possible in the same measurement sequence by modifying the Riso TL/OSL DA-20 reader in such a way, that the LED module, used for pre-bleaching, is separated from the detector unit, used for the TL measurement. The signal increase after removing the filter was approximately 50 and 90 times for category A and B, respectively. The zero dose distribution with an average of 34 mGy and a minimal detectable dose (3σ) of 90 mGy was recorded for the forty mobile phones. The position distribution of zero doses across the entire substrate glass of a phone showed a standard deviation of more than 60% for three phone samples. Linear dose response from 30 mGy to 10 Gy was observed, and fading data of the TL signal from glass samples of 22 mobile phones assessed, for up to twenty days after irradiation.

We compute the renormalization and evolution of the soft-quark function that appears in the factorization theorem for Higgs-boson decays to two photons through a $b$-quark loop. Our computation confirms a conjecture by Liu, Mecaj, Neubert, Wang, and Fleming for the form of the renormalization and evolution of the soft-quark function in order $\alpha_s$. We also work out the analyticity structure of the soft-quark function by making use of light-cone perturbation theory., Comment: 40 pages, 12 figures, as usual plus additional diagrams calculated, typos corrected, text improved, references added

An inter-laboratory comparison of a small-scale field experiment was conducted in the framework of the Korea retrospective dosimetry network (KREDOS) to verify the reliability and compatibility of thermoluminescence and optically stimulated luminescence techniques for accident dosimetry. Three institutes participated in this comparison, including the Korea Atomic Energy Research Institute, the Korea Institute of Nuclear Safety and the University of Salzburg. Two adult CIRS torso phantoms were used as virtual subjects exposed to a high-activity Ir-192 source, developing both homogeneous and inhomogeneous exposures in a shielded enclosure. The target materials for dose estimation were mobile phone components, such as resistors, display glasses, and chip cards. LiF:Mg,Cu, Si thermoluminescent (TL) detectors were used as reference dosimeters. The mobile phones were attached to the chest, hip, and thighs of the anthropomorphic phantoms. The measured doses ranged from 100 mGy to 2 Gy, depending on the position of the mobile phone on the phantom. The proficiency of the dose assessment was tested at three laboratories. Using the applied protocols, the local dose distribution on the display glasses was unclear, but the distribution around the body was confirmed.

International audience; With the use of ionising radiation comes the risk of accidents and malevolent misuse. When unplanned exposures occur, there are several methods which can be used to retrospectively reconstruct individual radiation exposures; biological methods include analysis of aberrations and damage of chromosomes and DNA while physical methods rely on luminescence (TL/OSL) or EPR signals. To ensure the quality and dependability of these methods, they should be evaluated under realistic exposure conditions. In 2019, EURADOS Working Group 10 and RENEB organised a field test with the purpose of evaluating retrospective dosimetry methods as carried out in potential real-life exposure scenarios. A 1.36 TBq 192Ir source was used to expose anthropomorphic phantoms in different geometries to doses of several gray in an outdoor open-air geometry. Materials intended for accident dosimetry (including mobile phones and blood) were placed on the phantoms together with reference dosimeters (LiF, NaCl, glass). The objective was to estimate radiation exposures received by individuals as measured using blood and fortuitous materials, and to evaluate these methods by comparing the estimated doses to reference measurements and Monte Carlo simulations. The aim of this paper is to describe the overall planning, goals, execution, and preliminary outcomes of the 2019 field test. Such field tests are essential for the development of new and existing methods. The outputs from this field test include useful experience in terms of planning and execution of future exercises, with respect to time management, radiation protection, and reference dosimetry to be considered to obtain relevant data for analysis.

We demonstrate how to make the coordinate transformation or change of variables from Cartesian coordinates to curvilinear coordinates by making use of a convolution of a function with Dirac delta functions whose arguments are determined by the transformation functions between the two coordinate systems. By integrating out an original coordinate with a Dirac delta function, we replace the original coordinate with a new coordinate in a systematic way. A recursive use of Dirac delta functions allows the coordinate transformation successively. After replacing every original coordinate into a new curvilinear coordinate, we find that the resultant Jacobian of the corresponding coordinate transformation is automatically obtained in a completely algebraic way. In order to provide insights on this method, we present a few examples of evaluating the Jacobian explicitly without resort to the known general formula., 18 pages, no figures

We investigate the motion of a massive particle constrained to move along a path consisting of two line segments on a vertical plane under an arbitrary conservative force. By fixing the starting and end points of the track and varying the vertex horizontally, we find the least-time path. We define the angles of incidence and refraction similar to the refraction of a light ray. It is remarkable that the ratio of the sines of these angles is identical to the ratio of the average speeds on the two partial paths as long as the horizontal component of the conservative force vanishes., 10 pages, 1 figure, Version published in J. Korean Phys. Soc

We present a new proof of Cramer's rule by interpreting a system of linear equations as a transformation of $n$-dimensional Cartesian-coordinate vectors. To find the solution, we carry out the inverse transformation by convolving the original coordinate vector with Dirac delta functions and changing integration variables from the original coordinates to new coordinates. As a byproduct, we derive a generalized version of Cramer's rule that applies to a partial set of variables, which is new to our best knowledge. Our formulation of finding a transformation rule for multi-variable functions shall be particularly useful in changing a partial set of generalized coordinates of a mechanical system., 7 pages, 1 figure, version published in Eur. J. Phys

We test the nonrelativistic QCD factorization conjecture for inclusive quarkonium production at two loops by carrying out a covariant calculation of the nonrelativistic quantum chromodynamics (NRQCD) long-distance matrix element (LDME) for a heavy-quark pair in an $S$-wave, color-octet state to fragment into a heavy-quark pair in a color-singlet state of arbitrary orbital angular momentum. The NRQCD factorization conjecture for the universality of the LDME requires that infrared divergences that it contains be independent of the direction of the Wilson line that appears in its definition. We find this to be the case in our calculation. The results of our calculation differ in some respects from those of a previous calculation that was carried out by Nayak, Qiu, and Sterman using light-cone methods. We have identified the sources of some of these differences. The results of both calculations are consistent with the NRQCD factorization conjecture. However, the general principle that underlies this confirmation of NRQCD factorization at two-loop order has yet to be revealed., Comment: 74 pages, 9 figures, minor reorganization and clarifications, typos corrected, published version

We consider a Z' model where the Z' boson couples only to up and top quarks. As a simple setup, one can consider a family-dependent $U(1)'$ symmetry, under which only right-handed up-type quarks are charged. After symmetry breaking, the right-handed quarks mix with each other and top flavor-changing neutral currents (FCNCs) mediated by the Z' boson can be generated at tree level. We take into account several processes to probe the top FCNCs, and find that the same sign top quark pair production or the triple top quark production is the most capable of testing the top FCNCs. We also consider a few non-FCNC processes to probe the Z' boson, for example, dijet production at the LHC., 21 pages, 11 figures, version published in PRD, detector simulation added

We employ Dirac's bra-ket notation to define the inertia tensor operator that is independent of the choice of bases or coordinate system. The principal axes and the corresponding principal values for the elliptic plate are determined only based on the geometry. By making use of a general symmetric tensor operator, we develop a method of diagonalization that is convenient and intuitive in determining the eigenvector. We demonstrate that the bra-ket approach greatly simplifies the computation of the inertia tensor with an example of an $N$-dimensional ellipsoid. The exploitation of the bra-ket notation to compute the inertia tensor in classical mechanics should provide undergraduate students with a strong background necessary to deal with abstract quantum mechanical problems., Comment: 18 pages, 1 figure, Version published in J. Korean Phys. Soc

Phototransferred thermoluminescence (PTTL) characteristics of LiF:Mg,Cu,Si, developed by the Korea Atomic Energy Research Institute, are presented as part of a simple and reliable method for dose re-evaluation that is compatible with routine personal dosimetry services. A 4.5 mm diameter 0.8 mm thick pellet-type thermoluminescence dosimeter (TLD) was used after dual-step thermal annealing at 300 °C for 10 min, and then at 260 °C for 10 min, in order to obtain thermal stability. For optimal UV illumination, samples were placed under a 254 nm ultraviolet (UV) lamp for 90 min. The PTTL signal was only lower than 2% that of the TL because of low residual signals in high-temperature deep traps. The difference of the PTTL signals between samples appeared up to two times, indicating high variation in the charge density of the deep traps between samples. Various thermal treatments were performed after each PTTL measurement to remove the residual PTTL signal. UV exposure at 250 °C for 20 min fully reset the residual PTTL signals to the same level as that after dual-step annealing. No degradation of the TL peak from repeated thermal treatments was observed until after the eighth treatment when a decrease was noticeable. The measured dose response of PTTL in the range of 1.14–51.3 mGy showed good linearity. The zero dose and minimal detectable dose of the PTTL were 1.36 ± 0.51 mGy and 1.53 mGy, respectively. The attenuation of the PTTL signal resulting from successive TL measurements was recorded to provide a correction factor for quarterly recorded TL measurements applicable to the dose re-evaluation of TLDs in routine personal dosimetry services.

We study the rapidly oscillating contributions in the sinc-function representation of the Dirac delta function and the Fourier transform of the Coulomb potential. Starting from the derivation of the standard integral representation of the Heaviside step function, we examine the representation of the Dirac delta function that contains a rapidly oscillating sinc function. By employing the contour-integral approach, we prove that the representation satisfies the properties of the Dirac delta function, although the representation is a function divergent at nonzero points. This is a good pedagogical example to show the difference between a function and a distribution. The rapidly oscillating contribution in the Fourier transform of the Coulomb potential into the momentum space has been ignored in most textbooks because only the regulated screened potential of Wentzel was employed to compute the amplitude free of such a rapidly oscillating contribution. By performing the inverse Fourier transform of the rapidly oscillating contribution rigorously, we demonstrate that the contribution is a well-defined distribution that is zero, even if it is an ill-defined function. We extend our proofs carried out for those oscillating contributions to show that the Riemann-Lebesgue lemma can hold for a sinc function, which is not absolutely integrable.

We derive a general formula for the inertia tensor of a three-body system. By employing three independent Lagrange undetermined multipliers to express the vectors corresponding to the sides in terms of the position vectors of the vertices, we present the general covariant expression for the inertia tensor of the three particles of different masses. If $m_a/a=m_b/b=m_c/c=\rho$, then the center of mass coincides with the incenter of the triangle and the moment of inertia about the normal axis passing the center of mass is $I=\rho abc$, where $m_a$, $m_b$, and $m_c$ are the masses of the particles at $A$, $B$, and $C$, respectively, and $a$, $b$, and $c$ are the lengths of the line segments $\overline{BC}$, $\overline{CA}$, and $\overline{AB}$, respectively. The derivation and the corresponding results are closely related to the famous Heron's formula for the area of a triangle., Comment: 14 pages, 3 figures

N-type and p-type silicon were irradiated by neutrons and protons from low to high fluence range (108 − 1011 cm-2 for neutrons and 1010 − 1013 cm-2 for protons). The carrier recombination lifetime of each irradiated silicon was measured using a microwave photoconductance decay method, and the resistivity of the irradiated silicon was also measured. Both neutron and proton irradiation induced a similar lifetime at the same irradiation fluence. The defect formation rates were determined to vary with irradiation fluence from the inverse lifetime dependence on irradiation fluence. The sheet resistance was increased above a threshold fluence. The result shows that at least three different values of defect formation rate are present in the fluence range of 109 − 1015 cm-2, and it may have potential for practical use as low-dose dosimeters.

Photorealistic three-dimensional (3-D) models are important tools for urban and disaster management planning because they contain useful visual and spatial information for assessing the situation a...

A flame deflector is a structure that prevents damage to a launch vehicle and a launch pad due to exhaust plumes of a lifting-off launch vehicle. The shape of a flame deflector should be designed to restrain the discharged gas from backdraft inside the deflector and to reflect the impact to the surrounding environment and the engine characteristics of the vehicle. This study presents the five preliminary flame deflector configurations which are designed for the first-stage rocket engine of the Korea Space Launch Vehicle-II and surroundings of the Naro space center. The gas discharge patterns of the designed flame deflectors are investigated using the 3D flow field analysis by assuming that the air, in place of the exhaust gas, forms the plume. In addition, a multi-species unreacted flow model is investigated through 2D analysis of the first-stage engine of the KSLV-II. The results indicate that the closest Mach number and temperature distributions to the reacted flow model can be achieved from the 4-species unreacted flow model which employs H2O, CO2, and CO and specific heat-corrected plume.

We study a classically scale-invariant model with an electroweak singlet scalar mediator together with a scalar dark matter multiplet of global $O(N)$ symmetry. Our most general conformally invariant scalar potential generates the electroweak symmetry breaking via the Coleman-Weinberg mechanism, and the new scalar singlet acquires its mass through radiative corrections of the SM particles and the scalar dark matter. Taking into account the collider bounds, we present the allowed region of new physics parameters satisfying the recent measurement of relic abundance. With the obtained parameter sets, we predict the elastic scattering cross section of the new scalar multiplet into target nuclei for a direct detection of the dark matter. We also perform a full analysis with arbitrary set of parameters for $N \geq 2$, and discuss the implication of the constraints from the on-going direct and indirect detections of dark matter., Comment: Minor corrections, including the discussion on Landau pole. Published version