[en] We construct metastable configurations of branes and anti-branes wrapping 2-spheres inside local Calabi-Yau manifolds and study their large N duals. These duals are Calabi-Yau manifolds in which the wrapped 2-spheres have been replaced by 3-spheres with flux through them, and supersymmetry is spontaneously broken. The geometry of the non-supersymmetric vacuum is exactly calculable to all orders of the t Hooft parameter, and to the leading order in 1/N. The computation utilizes the same matrix model techniques that were used in the supersymmetric context. This provides a novel mechanism for breaking supersymmetry in the context of flux compactifications

[en] We present a Majorana neutrino scenario in a F-theory SU(5) GUT model, which is recently proposed in [1]. The mass scale of the neutrinos arises from integrating out heavy Kaluza-Klein modes on the right-handed neutrinos. The participation of non-holomorphic Kaluza-Klein mode wave functions dilutes the mass hierarchy in comparison to the quark and charged lepton sectors, in agreement with experimentally measured mass splittings. The neutrinos are predicted to exhibit a 'normal' mass hierarchy, with masses (m₃, m₂, m₁)∼.05x(1,α_GUT^1/2,α_GUT) eV. The neutrino mixing matrix exhibits a mild hierarchical structure with θ₁₃∼α_GUT^1/2∼0.2. We also predict mass measurements in single and double beta decay experiments.

[en] Spent nuclear fuel from nuclear reactors needs to be disposed of in isolation from humans and the environment as much as possible due to high heat and high radioactivity. Among the disposal methods of spent nuclear fuel, deep geological disposal, which is disposed of in the ground more than 500 m underground, is being considered as the most promising method. In the case of deep geological disposal, an engineered barrier is required to prevent radioactive material from leaking from the disposal container and spreading to the natural environment, and structural safety and criticality safety are required. In this study, to secure the structural safety of the disposal container and at the same time increase the handling efficiency, a study was conducted on a method of reducing the weight through structural change. During deep geological disposal, the critical safety evaluation of engineered barriers including the spent fuel copper disposal container was performed to calculate the interval among baskets for the spent fuel required for the design of the disposal cask. And by applying the analytical stress calculation method based on the beam theory, the efficient optimization of the cross-section of the disposal cask was performed. It was confirmed that a design that can have handling efficiency while securing structural and critical safety through the developed optimal design process can be secured

[en] There are studies to measure and model the radon concentration in soil gas and some studies have been carried out in the field to confirm regional and seasonal characteristics. in this study of radon exhalation rate from soil around Daegu, measuring radon concentration in a detector volume as a function of time and getting the initial increase rate from fitting were conducted outdoor by using RAD7 detector and its surface emission chamber. In this study, for two locations near Daegu, radon was measured outdoor and radon exhalation rates were calculated from the increase rates. In KNU, radon exhalation rate from soil was 15.14±0.87 Bq/m²s, in GC, 5.13±1.25 Bq/m²s. And radon's parent nuclides' concentration in KNU was also higher than GC's. But as for thoron, correlation between thoron exhalation rate and parent nuclide concentration can't be seen clearly. Afterward the measurement will be made in more sites and exhalation rate will be analyzed in association with parent nuclides activity in soil and spatial gamma dose rates or gamma exposure rates from monitoring ion chambers.

[en] As the use of X-ray tubes is widely spread mainly for medical diagnostic purposes or industrial applications, there is increasing demand for accurate and convenient way getting of X-ray beam spectral information. While measurement methods may provide quite accurate spectral information, these methods still require expensive detectors (example: HPGe, High Purity Germanium detector) and some conversion of measurement information into real spectrum. It is concluded that Laplace transform-based spectral reconstruction technique given in equations (1) and (2) works well for a 50-kV X-ray source. In this paper we obtained the attenuation curve by the use of MCNPX simulations. We were able to rebuild the X-ray spectrum of 50 kV through this research by Monte Carlo simulation (fitting parameters, a: 1.2921, b: 0.2342, ν: 0.6190, R-squared: 0.9930)

[en] For the denuclearization, nuclear activities must be reported and the reported documents must be confirmed through nuclear disarmament verification process. Sampling from undeclared area is an essential task of the verification to obtain information about the concealment of nuclear material. However, it is not possible to get the environmental radioactivity information of undeclared areas, so the safety of workers for sampling cannot be guaranteed. Therefore, before collecting samples, it is necessary to secure the information about radioactivity of the sampling region through the radiation measurement. In this study, we propose a compact gamma detection probe that can be transported by drones and distributed over a wide area in a short period of time. A plastic scintillator was applied to reduce weight and increase efficiency. In addition, the total weight and power consumption of the probe were optimized by applying a measurement method that counts photons generated from the scintillator. The performance of the probe was evaluated under the same dose conditions as the actual measurement environment. It was confirmed that the probe developed in this study exceeded more than twice the count value of background radiation at 25 meters. In addition, it was confirmed that the count value increased at a linear rate as the dose rate. As a result, it is possible to estimate the dose rate from the measured count value

[en] Highlights: • The tidal characteristics of Uldolmok Strait is briefly reviewed. • Optimal design of blade shape is carried out. • The performance of the horizontal axis rotor are discussed with respect to different operational conditions. • The performance of the tidal current turbine is discussed considering the advantages in terms of maintenance. -- Abstract: Ocean energy is a promising renewable energy resource. In particular, South Korea is a country with a large amount of tidal current energy needed for the economically and technically feasible development of a tidal current power plant. In this study, the environmental conditions including the bathymetry and tidal conditions for Uldolmok Strait and previous studies carried out in Uldolmok Strait are first briefly reviewed, and the optimal design of the blade shape and performance of an optimally designed horizontal axis rotor for a 200-kW class tidal current turbine are discussed. For the optimal blade shape design, the design code, the Horizontal Axis Rotor Performance Optimizer developed by the National Renewable Energy Laboratory in the United States, is utilized, and the performance is investigated with respect to the number of blades (two or three) and the pitch control algorithms (variable or fixed). The results indicate that a variable speed fixed pitch turbine with three blades showed the best performance. However, the performances of four alternative cases did not show significant differences. Considering the advantages in terms of maintenance, we also conducted an analysis under various rotor and cut-in speed conditions. Hence, to select the final design, it is necessary to consider the structural integrity related to fatigue, as well as the economic feasibility in manufacturing the blades.

[en] The Republic of Korea is expected to participate in the denuclearization verification activities by the International Atomic Energy Agency (IAEA) in case any neighboring countries declared denuclearization. In this study, samples for the verification of nuclear activities in undeclared areas were selected for the denuclearization of neighboring countries, and the appropriateness of the procedures was considered. If a country with nuclear weapons declares denuclearization, it must be accompanied by the IAEA’s verification regarding nuclear materials and weapons in the declared and undeclared areas. The analysis of the process samples or on-site environmental samples and the verification of undeclared nuclear facilities and materials aid in uncovering any evidence of concealment of nuclear activity in undeclared areas. Therefore, a methodology was established for effective sampling and analysis in accordance with proper procedures. Preparations for sampling in undeclared areas were undertaken for various potential scenarios, such as, the establishment of zones according to radiation dose, methods of supplying electricity, wireless communication networks, targets of sampling according to characteristics of nuclides, manned sampling method, and unmanned sampling method. Through this, procedures were established for pre- and post-site settings in preparation for hazards and limiting factors at nuclear inspection sites

[en] We carry out a detailed superspace analysis of the OPE of two N=2 stress-tensor multiplets. Knowledge of the multiplets appearing in the expansion, together with the two-dimensional chiral algebra description of N=2 SCFTs, imply an analytic bound on the central charge c. This bound is valid for any N=2 SCFT regardless of its matter content and flavor symmetries, and is saturated by the simplest Argyres-Douglas fixed point. We also present a partial conformal block analysis for the scalar superconformal primary of the multiplet.

[en] We further analyze a class of recently studied metastable string vacua obtained by wrapping D5-branes and anti-D5-branes over rigid homologous S²'s of a non-compact Calabi-Yau threefold. The large N dual description is characterized by a potential for the glueball fields which is determined by an auxiliary matrix model. The higher order corrections to this potential produce a suprisingly rich phase structure. In particular, at sufficiently large 't Hooft coupling the metastable vacua present at weak coupling cease to exist. This instability can already be seen by an open string two loop contribution to the glueball potential. The glueball potential also lifts some of the degeneracy in the vacua characterized by the phases of the glueball fields. This generates an exactly computable non-vanishing axion potential at large N