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We investigate the axial-vector transition form factors of the lowest-lying singly heavy baryons within the framework of the chiral quark-soliton model. We consider the linear $m_{\mathrm{s}}$ corrections, dealing with the strange current quark mass $m_{\mathrm{s}}$ as a small perturbation. Since we have various relations between different transitions because of isospin symmetry and flavor SU(3) symmetry breaking, only two axial-vector transition form factors are independent. We present the numerical results for these form factors. The effects of the flavor SU(3) symmetry breaking turn out tiny, so we neglect them. We also compute the decay rates for several strong decays of the singly heavy baryons and compare the results with the experimental data and those from other models. While the results for the $\Sigma_c\to \Lambda_c^++\pi$ and $\Sigma_c^*\to \Lambda_c^++\pi$ decays are slightly overestimated in comparison with the corresponding experimental data, those for the $\Xi_c^*\to \Xi_c+\pi$ are in remarkable agreement with the data., Comment: 20 pages, 3 figures

We investigate the quark spin content of the SU(3) baryon octet, decuplet, antitriplet, and sextet in a pion mean-field approach or the chiral quark-soliton model, considering the $1/N_c$ rotational corrections and SU(3) symmetry breaking effects. We compare the present results with those from various theoretical works and lattice QCD., 22 pages, 2 figures

We investigate the axial-vector transition form factors of the baryon octet to the baryon decuplet within the framework of the chiral quark-soliton model, with the effects of flavor SU(3) symmetry breaking included. We consider the rotational $1/N_c$ corrections and regard the strange current quark mass as a perturbation. We compare the present results for the $\Delta \to N$ axial-vector transition with those from other models and lattice QCD. We also compute all possible axial-vector transitions from the baryon decuplet to the octet with the strangeness changed, i.e., $|\Delta S|=1$. We obtain the value of the essential form factor $C_5^A$ for the $\Delta\to N$ axial-vector transition at the zero momentum transfer ($Q^2=0$). Furthermore, the present results are in good agreement with those fitted with the T2K data. We extract the value of the axial-vector mass $M_A$ compared to the data., Comment: 22 pages, 4 figures. Final version accepted for publication in Physical Review D

The axial-vector form factors and axial-vector constants of the baryon decuplet are investigated within a pion mean-field approach, which is also known as the chiral quark-soliton model. Given an axial-vector current with a specified flavor, there are four different form factors of a decuplet baryon. When we consider the singlet, triplet, and octet axial-vector currents, we have twelve different form factors for each member of the baryon decuplet. We compute all these axial-vector form factors of the baryon decuplet, taking into account the rotational $1/N_c$ corrections and effects of flavor SU(3) symmetry breaking. We find that, for a given flavor, two of the form factors for a decuplet baryon are only independent within the present approach. We first examine properties of the axial-vector form factors of the $\Delta^+$ isobar and $\Omega^-$ hyperon. We also compare the results of the triplet axial-vector form factors of $\Delta^+$ with those from lattice QCD and those of the present work for the axial-vector constants of the baryon decuplet with the lattice data. All the results for other members of the baryon decuplet are then presented. The results of the axial charges are compared with those of other works. The axial masses and axial radii are also discussed., Comment: 31 pages, 14 figures

We present results of a recent work on the reaction mechanism of \(\eta n\) photoproduction off the neutron in the range of \( \sqrt{s} \approx 1.5-1.9\) GeV and discuss the role of various nucleon resonances listed in the Particle Data Group (PDG). We make use of an effective Lagrangian approach combining with a Regge method. The total and helicity-dependent cross sections \(\sigma _{1/2},\,\sigma _{3/2}\) are computed and the numerical results are in good agreement with the A2 experimental data.

We investigate $\eta$ photoproduction off the neutron target, i.e., $\gamma n \to \eta n$, employing an effective Lagrangian method combining with a Regge approach. As a background, we consider nucleon exchange in the $s$-channel diagram and $\rho$- and $\omega$-meson Regge trajectories in the $t$ channel. The role of nucleon resonances given in the Review of Particle Data Group in the range of $W \approx 1500 - 2100$ MeV and the narrow nucleon resonance $N(1685,1/2^+)$ is extensively studied. The numerical results of the total and differential cross sections, double polarization observable $E$, and helicity-dependent cross sections $\sigma_{1/2}$, $\sigma_{3/2}$ are found to be in qualitative agreement with the recent A2 experimental data. The predictions of the beam asymmetry are also given., Comment: 12 pages, 6 figures

Objectives :『Donguibogam(東醫寶鑑)』is a medical book of the Joseon Dynasty compiled by Heo Jun and was first published in 1613. It recorded a great deal of prescriptions which contained pork and gave detailed explanations of parts of pork's natural properties and effects. Pork is widely used as a food ingredient in the world but the traditional medicine community has a contraindication of pork and traditional herbal medicines taken together. The aim of this study was to find the supports to develop pork functional foods for the treatment of diseases in『Donguibogam』.

This paper discusses a harmonic response estimation method on the Lvy plate with two opposite edges simply supported and the other two edges having free boundary conditions. Since the equation of motion of the plate is not self-adjoint, the modes are not orthogonal to each other on the domain. Noting that the Lvy plate can be expressed using one term sinusoidal function that is orthogonal to other sinusoidal functions, this paper suggested the calculation method that is equivalent to finding a least square error minimization solution of the finite number of algebraic equations. Example problems subjected to a distributed area loading and a distributed line loading are defined and their solutions are provided. The solutions are compared to those of the commercial code, ANSYS. According to the verification results, it is expected that the suggested method will be useful to predict the forced response on the Lvy plate with the distributed area or line loading conditions.

A reactor core structural model which is used to evaluate the structural integrity of the core contains nuclear fuel assembly models. Since the reactor core consists of many nuclear fuel assemblies, the use of a refined fuel assembly model leads to a considerable amount of computing time for performing nonlinear analyses such as the prediction of seismic induced vibration behaviors. The computational time could be reduced by replacing the detailed fuel assembly model with a simplified model that has fewer degrees of freedom, but the dynamic characteristics of the detailed model must be maintained in the simplified model. Such a model based on an optimal design method is proposed in this paper. That is, when a mass matrix and a mode shape matrix are given, the optimal stiffness matrix of a discrete fuel assembly model can be estimated by applying the least squares minimization method. The verification of the method is completed by comparing test results and simulation results. This paper shows that the simplified model's dynamic behaviors are quite similar to experimental results and that the suggested method is suitable for identifying reliable mathematical model for fuel assemblies.

Since the fuel is always exposed to turbulent flow, the grid strap shows flow induced vibration characteristics that impact on the nuclear fuel soundness. The dynamic behavior of grids in nuclear fuels is quite complex, since two pairs of spring and dimple support are contacted with rods by friction in the limited space. This paper focuses on investigation of the grid strap(test fuel strap, TFS) vibration in one cell. TFS consists of a single spring and double dimples. To identify the grid strap vibration, modal analysis of the strap is performed using finite element method(FEM). Modal testing on a grid structure without rods is performed. The modal testing results are compared to analytic results. In addition, random test considering rod effect is performed about a grid with rods under real contact condition in the air. Finally, the strap vibration of a fuel bundle in investigation of flow induced vibration(INFINIT) facility is measured in real fluid velocity condition without heating. It is shown that modal frequencies from the test are almost equal to those peak frequencies in the INFINIT test.

The spacer grid is one of the main structural components in a fuel assembly. It supports fuel rods, guides cooling water and maintains geometry from external impact load and cyclic stress by the vibration of nuclear fuel rod, it is necessary to have sufficient strength against dynamic external load and fatigue strength. In this study, the mechanical properties and fatigue characteristics of laser beam welded zircaloy thin sheet are examined. The fatigue strength under cyclic load was evaluated by staircase method at stress ratio R =0.1. The most appropriate distribution for probabilistic characteristics of fatigue strength at 2×106 cycles was 2-paramer Weibull distribution. Results show that reliability analysis strength was derived from the strength-stress interference model. As a result of the experimental approach, the design guide of fatigue strength for laser welded joint is proposed and the results obtained in this are to be the useful data for spacer gird design.

The paper concerns the study of the vibrational behavior of a fuel rod supported by elastoplastic supports. Nuclear fuel rods in reactor conditions are always exposed to turbulent flow, which in turn creates random vibrations. Shock vibration can also occur as a result of unwanted conditions, such as seismic and LOCA accidents. Excessive external forces can induce plastic deformation in the nuclear fuel rod. Therefore, a bilinear elastoplastic contact force model is utilized to simulate nonlinear behavior, and the plastic deformation of the supports is computed based on a predictor–corrector scheme. Once the contact force exceeds the yielding point, it can be shown that the supports behave nonlinearly, and that the gap becomes larger due to the plastic deformation. Three categories of vibration – harmonic, random, and shock vibration – are dealt with in this work. The elastoplastic response of supports subjected to such vibrations is reviewed, and the stress levels developed in the fuel cladding is evaluated. It has been found that the minimum required force to cause plastic deformation is dependent on excitation frequency as well as gap size, but it can be seen that the excitation frequency range is more sensitive for random vibrations. For all simulation cases, the stress level of the fuel cladding is below the yield limit, and results show that the most severe conditions are induced by random vibrations in terms of the stress intensity.

This paper proposes an approximated contact force model to identify the nonlinear behavior of a fuel rod with gap supports; also, the numerical prediction of interfacial forces in the mechanical contact of fuel rods with gap supports is studied. The Newmark integration method requires the current status of the contact force, but the contact force is not given a priori. Taylor’s expansion can be used to predict the unknown contact force; therefore, it should be guaranteed that the first derivative of the contact force is continuous. This work proposes a continuous and differentiable contact force model with the ability to estimate the current state of the contact force. An approximated convex and differentiable potential function for the contact force is described, and a variational formulation is also provided. A numerical example that considers the particularly stiff supports has been studied, and a fuel rod with hardening supports was also examined for a realistic simulation. An approximated proper solution can be obtained using the results, and abrupt changes from the contacting state to non-contacting state, or vice versa, can be relieved. It can also be seen that not only the external force but also the developed contact force affects the response.

These experimental studies are carried out to build a database for analyzing fuel performance in nuclear power plants. In particular, this study focuses on the mechanical and irradiation properties of three kinds of zirconium alloy (Alloy A, Alloy B and Alloy C) irradiated in the HANARO (High-flux Advanced Neutron Application Reactor), one of the leading multipurpose research reactors in the world. Yield strength and ultimate tensile strength were measured to determine the mechanical properties before and after irradiation, while irradiation growth was measured for the irradiation properties. The samples for irradiation testing are classified by texture. For the irradiation condition, all samples were wrapped into the capsule (07M-13N) and irradiated in the HANARO for about 100 days (E > 1.0 MeV, 1.1 x 10 21 n/cm²). These tests and results indicate that the mechanical properties of zirconium alloys are similar whether unirradiated or irradiated. Alloy B has shown the highest yield strength and tensile strength properties compared to other alloys in irradiated condition. Even though each of the zirconium alloys has a different alloying content, this content does not seem to affect the mechanical properties under an unirradiated condition and low fluence. And all the alloys have shown the tendency to increase in yield strength and ultimate tensile strength. Transverse specimens of each of the zirconium alloys have a slightly lower irradiation growth tendency than longitudinal specimens. However, for clear analysis of texture effects, further testing under higher irradiation conditions is needed.

Welding is required for a connection between two different components in the nuclear fuel of a pressurized water reactor. This work relies on a mechanical experiment and analytic results to investigate the structural integrity of nuclear fuel in a situation where some components are not welded to each other. A series of lateral vibration tests are performed in a test facility, and the test structures are examined in terms of dynamic behavior. In the tests, the displacement signal at every grid structure that sustains fuel rods is measured and processed to identify the dynamic properties. The fluid-elastic stability of the structure is also analyzed to evaluate susceptibility to a cross flow with an assumed conservative cross flow distribution. The test and analysis results confirm that the structural integrity can be maintained even in the absence of some welding connections.

The fluid-induced vibration at the nuclear fuel assembly may cause grid-to-rod fretting wear, and subsequently, fuel rod perforation. The fluid-induced grid-to-rod fretting wear occurs with a certain fuel assembly design and/or in certain nuclear power plants, which may be strongly correlated with external and internal vibration causes acting on the fuel assembly. The external vibration causes may include reactor coolant flow velocity, nonuniform radial flow profiles caused by reactor internals, and interfuel assembly gap and fuel assembly-shroud gap, whereas the internal vibration causes may include asymmetric mixing vane pattern across the spacer grid assembly and inadequate spacer grid design. In this study, the external and internal vibration causes are described including three internal vibration mechanisms acting on the fuel assembly. The impact of internal vibration on the grid-to-rod fretting wear was investigated, based on out-of-pile vibration and grid-to-rod fretting wear test results for two k...

The advanced PWR fuel for the OPR1000s in Korea, PLUS7, has been developed to enhance thermal performance, high burnup capability and fuel reliability against grid-to-rod fretting wear and debris. The outstanding design features of PLUS7 include mixing vane mid-grids for increasing thermal performance and minimizing vibration-induced fretting wear, optimized fuel dimensions and advanced zirconium alloys for high burnup capability of 72,000 MWD/MTU, and an optimized fuel rod diameter for reducing pressure drop and improving neutron economy. The fuel assembly and its components performances have been verified through a wide spectrum of mechanical, thermal hydraulic, vibration and fretting wear tests. Based on the verification test results and the evaluations with the help of the KNF design code system, it is found that the PLUS7 fuel will maintain its integrity up to the envisaged burnup of 72,000 MWD/MTU. In addition, the PLUS7 fuel performances were evaluated to be considerably improved in comparison with the current fuel used in the OPR1000s.

Nuclear fuel rods are exposed to axial flow in a reactor, and flow-induced-vibration due to the flow usually causes damage in the fuel rods. Thus a prior knowledge about dynamic behavior of a fuel rod exposed to the flow condition should be provided. This paper shows that dynamic characteristics of a nuclear fuel rod depend on axial flow velocity. Assuming small lateral displacement, the effects of uniform axial flow are investigated. The analytic results show that axial flow generally reduces fuel rod stiffness and raises its damping in normal condition. Also, the critical axial velocities which make the fuel rod behavior unstable were found. That is, solving generalized eigenvalue equation of the fuel rod dynamic system, the eigenvalues with positive real part are detected. Based on the simulation results, on the other hand, it turns out that the ordinary axial flow in nuclear reactors does not affect to stability of a nuclear fuel rod even in the conservative condition.

This paper discusses a harmonic response estimation method on the Levy plate with two opposite edges simply supported and the other two edges having free boundary conditions. Then, the harmonic response is processed to evaluate fatigue damage. Since the equation of motion of the plate is not self-adjoint, the modes are not orthogonal to each other on the structure domain. Noting that the Levy plate can be expressed using one term sinusoidal function that is orthogonal to other sinusoidal functions, this paper suggested the calculation method that is equivalent to finding a least square error minimization solution of the finite number of algebraic equations. Example problems subjected to a distributed area loading and a distributed line loading are defined and their solutions are provided. The solutions are compared to those of the commercial code, ANSYS. The plate motion due to high frequency vibration can be seen in the nuclear fuels subjected to highly turbulent coolant flow. The dominant exciting frequency is dependent on the coolant velocity and Strouhal number, a dimensionless number describing oscillating flow mechanism. This paper also discusses fatigue damage considering the high frequency vibration using the Dirlik equation.

Spacer grid springs support fuel rods so that the rods keep the position laterally and axially in pressurized water reactor fuel assemblies. The spring load-deflection characteristic, i.e. spring force and stiffness, is needed to evaluate the rod support conditions in the case of fuel assembly manufacturing, shipping and handling. In general, the load-deflection characteristic of grid spring is obtained by mechanical test, but it takes long time to get the new designed grid specimen because the grid manufacturing process comprises strip material manufacturing, stamping die and punch preparation, heat treatment and welding, etc. Therefore the analytic method such as finite element method (FEM) is tried to predict the nonlinear load-deflection characteristic of new designed grid. The spring characteristic mechanical test is simulated with unit cell model and analyzed by FEM tool. Comparing the results between test and analysis shows that more details are needed in the modeling because the boundary conditions of the spring are very complicated and the spring material thickness is changed by the stamping process. The analysis of modified model including expanded cells and thickness changed springs is performed. Using the analytic method of the work to obtain the load-deflection characteristic of spacer grid spring is expected to be useful in the prediction of the characteristic of new designed grids.Copyright © 2009 by ASME

목 적 : 본 연구는 농촌 지역 초등학생의 천식과 알레르기비염의 유병률을 조사하고 발병에 영향을 미치는 위험 인자를 분석하고자 하였다. 방 법: 2010년 11월에 전형적인 농촌지역인 전라북도 진안군 12개 초등학교 학생을 대상으로 한국어판 ISAAC 설문지를 이용하여 설문조사를 실시하였다. 결 과 : 총 947명의 설문지가 회수되었고 회수율은 89.1%였다. 지난 12개월 동안의 천식과 알레르기비염의 증상 유병률은 각각 7.4%, 28.1%이었고 천식과 알레르기비염의 평생 진단 유병률은 각각 7.2%, 22.2%이었다. 남자, 간접흡연 집안 , 내 곰팡이가 천식 진단의 위험 인자로 분석되었고(adjusted odds ratio [aOR] 2.35, 95% CI 1.30-4.26; aOR 2.49, 95% CI 1.38-4.48; aOR 2.19, 95% CI 1.23-3.89) 부모의 알레르기 질환 병력은 알레르기비염의 위험인자로 분석되었다.(aOR, 4.89; 95% CI, 3.37-7.10) 2명 이상의 형제가 있는 경우에 비해 형제가 없는 경우 알레르기비염의 유병률이 높았으며(aOR, 5.20; 95% CI, 2.38-11.35) 특히 생후 1년 이내에 항생제 사용이 3회 이상인 경우 항생제를 사용하지 않은 경우와 비교했을 때 천식(aOR, 8.45; 95% CI, 4.23-16.59)과 알레르기비염(aOR, 2.39; 95% CI, 1.36-4.19)의 유병률이 급격히 증가했었다. 결 론 : 진안군 초등학생에서의 지난 12개월 동안의 천식과 알레르기비염의 증상 유병률은 각각 7.4%, 28.1%이었고 천식과 알레르기비염의 평생 진단 유병률은 각각 7.2%, 22.2%이었다. 위험 인자를 분석한 결과 간접 흡연, 집안 내 곰팡이, 영아기 동안의 항생제 투여, 형제의 수와 같은 환경요소가 천식 혹은 알레르기비염의 유병률과 연관성이 있었다.

Purpose : The purpose of this study was to evaluate the clinical characteristics and outcomes of patients with neuroblastoma aged less than 1 year. Methods : From January 1997 to December 2007, 41 patients aged less than 1 year were diagnosed with neuroblastoma. Patients were divided into 3 risk groups according to the stage of the disease and N-myc amplification. Low-risk patients underwent surgery with (stage 2) or without (stage 1) short-term chemotherapy. Intermediate-risk patients underwent chemotherapy and surgery with or without local radiation therapy. High-risk patients underwent chemotherapy, surgery, radiation therapy, and high-dose chemotherapy/autologous stem cell rescue (HDCT/ASCR). Results : While tumor relapse occurred in only 1 patient, 7 patients died of treatment-related toxicities. Causes of treatment- related death included infection during conventional chemotherapy in 5 patients and acute myocarditis during HDCT/ASCR in 2 patients. The overall 5-year survival (standard error) and 5-year event-free survival (EFS) rates after diagnosis for all 41 patients were 82.85.9% and 80.06.3%, respectively, with a median follow-up of 58 (9-137) months. The 5-year EFS rates for low-risk, intermediate-risk, and high-risk patients were 100%, 68.410.8%, and 66.719.3%, respectively. Conclusion : Increased efforts to reduce infection-associated toxicity deaths during conventional chemotherapy are needed to further improve the survival of patients with neuroblastoma aged less than 1 year.

Purpose : To analyze the results of a 5-12 year (mean, 7 years, 5 months) follow-up of femoral revision THA using the Wagner® stem. Materials and Methods : Of 79 revision THA patients enrolled in the study between March 1991 and January 2000, there were 64 cases of aseptic loosening (69 hips, 44 males and 20 females) during a minimum 5-year follow-up. In addition, postoperative complications and clinical and radiographic results were evaluated. Results : The Harris hip score improved from 48.6 to 91.2 points, postoperatively. There were 3 revisions due to failed stem fixation and aseptic loosening. The Kaplan-Meier survivorship analysis, with failure defined as a removal of the Wagner® stem, revealed a 97.1% survival at a 12-year follow-up. Besides the revisions, there were 66 hips that were hip-related symptom-free. However, there was claudication in 1 case. Radiographic findings included subsidence of the implant (5 cases, 7.5%, all less than 10 mm), calcar femorale atrophy (4 cases, 6.0%), stress shielding (4 cases, 6.0%), and heterotopic ossification (5 cases, 7.5%). Postoperative peroneal nerve palsy (2 cases) resolved completely within the following 6 months. Conclusion : We obtained a stable fixation and satisfactory results in the cases we studied using the Wagner® revision stem.

An in-pile performance test of HANA claddings was conducted at up to 67 GWD/MTU in the Halden research reactor in Norway over a 6.5 year period. Four types of HANA claddings (HANA-3, HANA-4, HANA-5, and HANA-6) and a reference Zircaloy-4 cladding were used for the in-pile test. The evaluation parameters of the HANA claddings were the corrosion behavior, dimensional changes, hydrogen uptake, and tensile strength after the claddings were tested under the simulated operation conditions of a Korean commercial reactor. The oxide thickness ranged from 15 to 37 mm at a high flux region in the test rods, and all HANA claddings showed corrosion resistance superior to the Zircaloy-4 cladding. The creep-down rate of all HANA claddings was lower than that of the Zircaloy-4 cladding. In addition, the hydrogen content of the HANA claddings ranged from 54 to 96 wppm at the high heat flux region of the test rods, whereas the hydrogen content of the Zircaloy-4 cladding was 119 wppm. The tensile strength of the HANA and Zircaloy-4 claddings was similarly increased when compared to the un-irradiated claddings owing to the radiation-induced hardening.