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Sintered samples of Ti added TiO2 nanopowders were fabricated by combined application of magnetic pulsed compaction (MPC) and sintering. The effect of Ti nano powder on density, shrinkage and hardness of the samples were investigated as part of the study. The optimum processing conditions were found to be around 0.5 GPa MPC pressure and 1450°C sintering temperature, illustrating maximum density, hardness and minimum shrinkage. High pressure compaction using MPC was found to enhance density with increasing MPC pressure up to 0.9 GPa, and significantly reduce the total shrinkage (about 16% in this case) in the sintered bulks compared to other general processes (about 18%). While sintered samples blended with micro Ti showed presence of microstructural cracks, the samples with 1-2% nano Ti had less or no cracks on them. Overall, the inclusion of nano Ti indicated improvement in mechanical properties of TiO2 nanopowders sintered preforms as opposed to micro Ti-added TiO2.

As a participant of ITER project, ITER Korea has to supply two ITER vacuum vessel sectors (Sector #6, #1) of total nine ITER VV sectors. After the procurement arrangement with ITER Organization, ITER Korea made the contract with Hyundai Heavy Industries (HHI) for fabrication of two sectors. Then the start of the manufacturing design was initiated from January 2010. HHI made three real scale R&D mock-ups to verify the critical fabrication feasibility issues on electron beam welding, 3D forming, welding distortion and achievable tolerances. The documentation according to IO and the French nuclear safety regulation requirement, the qualification of welding and nondestructive examination procedures conform to RCC-MR 2007 were proceed in parallel. The mass production of raw material was done after receiving ANB (agreed notified body) verification of product/parts and shop qualification. The manufacturing drawing, manufacturing and inspection plan of VV sector with supporting fabrication procedures are also verified by ANB, accordingly the first cutting and forming of plates for VV sector fabrication started from February 2012. This paper reports the latest fabrication progress of ITER vacuum vessel Sector #6 that will be assembled as the first sector in the ITER pit. The overall fabrication route, R&D mock-up fabrication results with forming and welding distortion analysis, qualification status of welding and nondestructive examination (NDE) are also presented.

The structural analyses of vacuum vessel have been performed to investigate the effect of shell thickness reduction on structural integrity. The finite element models of vacuum vessel considering original design and thickness reduction have been developed. The expected maximum thickness reduction possibly caused by forming and bending processes during fabrication was applied to the curved region of the analysis models. The linear elastic and nonlinear limit analyses have been performed. The structural integrity of main vessel including lower port stub extension has been verified in accordance with the requirements of RCC-MR. It is concluded that the inner and outer shells of main vessel still have enough strength margins under pressure and VDE (Vertical Displacement Event) load conditions in spite of thickness reduction. These results have been reviewed and approved by ITER Organization and ANB (Agreed Notified Body).

A vacuum vessel is one of the core facilities of ITER (International Thermonuclear Experimental Reactor) and basically all-welded structure. Korea is responsible for the procurement of sector 1 and 6 of the main vessel. Accordingly, the design review for the fabrication is in progress by ITER Korea and Hyundai Heavy Industries. Due to anticipated manufacturing problems such as the welding distortion, the design of some components of main vessel, IWS (In-Wall Shield) supporting rib and ELM (Edge Localized Mode) coil support, needs to be modified. To release the risk of welding distortion, the welding method called “bridge type” is suggested and the shape of weld joint is adjusted to secure the manufacturability of the issued components. The elastic and limit analyses with fatigue evaluation have been performed under the most critical loading condition to verify the structural integrity of modified design. Analysis results show that the proposed designs meet the design criteria of RCC-MR. The design deviation requests have been submitted to ITER Organization and ANB (Agreed Notified Body) for approval and their verification is currently in progress.

Gas insulated switchgear is large-sized electric equipment for providing a reliable supply of electric power. Recently, seismic tests of electric equipment using a shaking table have been mandated because seismic performance has become an increasingly important issue. However, basic analysis methods continue to be used because some electric equipment is too large for shaking table facilities. Thus, a reliable analysis method should be developed for large-scale electric equipment. This study aims to evaluate the seismic qualification of a 245kV GIS in accordance with IEEE-693 and to validate the analysis method by comparing it with test results. Both the test and the analysis showed that the 245kV GIS has proper seismic safety. Furthermore, the differences between the analysis and the test results are less than 10% for an accurately given mass, stiffness, and input acceleration. It is expected that this study can be used for the seismic qualification of large-scale electrical structures.

The ITER vacuum vessel (VV) consists of three main sub-components; main vessel, port structures and the VV supporting system. In this study, the modified designs for the main vessel and the supporting system have been proposed, and the stress analyses have been conducted to investigate their structural integrities. In the original design of the main vessel, the assembling works of the flexible support housing into the outer shell is so difficult that the modified design concept is suggested for easier fabrication. To simplify the VV supporting system for better maintainability and to reduce its fabricating cost, the multi-flexible plates with rigid restraint for the VV support have been proposed. The flexible plate support is surrounded by a rigid restraint with a rectangular cask. As a result of this study, the availability to adopt the modified design concept of the supporting system as well as the main vessel in the ITER VV design has been reviewed.

The ITER vacuum vessel support systems located in the lower level sustain loads in radial and vertical direction. The support system consists of various sub-components like a linkage system, a pot type bearing, a vertical rope, a toroidal constraint, and dampers. In order to examine performance of the mechanism of the system, a mock-up of the linkage system which is comparatively complicated has been manufactured. Various fabrication methods were studied through the mock-up fabrication, and also several tests have been done using the mock-up. Those include assembly study, stroke test, static load test and fatigue test. In the full stroke test, the functional mechanism of the support structure has been demonstrated. In the structural test, the strength of the all components is evaluated by measuring reaction and strain of each component. In order to investigate the effect of tolerances and the damage due to the tests, the performance tests were conducted before and after the static and fatigue tests. The backlash for each stage is found from measured displacement hysteresis. As results of those tests, the performance of the ITER vacuum vessel support structure as well as its structural integrity has been evaluated in this study.

To investigate the structural integrity of the ITER vacuum vessel (VV) and ports, the structural analyses of the regular equatorial and the lower remote handling (RH) ports have been performed. The advanced design of the equatorial regular port adopting a pure friction type flange has been recommended as a reference design by the ITER International Organization. The structural integrity of the equatorial port flange, sealing unit, and connecting duct has been reviewed by conducting nonlinear finite element analyses. The advanced design of the regular equatorial port flange with proper pretension is acceptable in the structural design point of view. From the local analyses for a connecting duct and a sealing unit, it has been found that the stresses are less than the allowable values. The structural analyses of the lower RH port have been also performed to verify the capability for supporting the VV. Since high local stress occurs at the gusset and supporting block, the case study for the lower port has been conducted to mitigate the stress concentration and to modify the component design. The strength of the lower RH port structures can be improved by the design modification of poloidal and toroidal gusset.

Based on the design done by the ITER international organization (ITER-O) and other participant teams, the more detail engineering design of the ITER vacuum vessel port and support is progressed by the Korea ITER project team. In this work, the recent design elaboration and manufacturing feasibility study from 2006 mainly focused on the equatorial and lower port are reported. The fabrication status and test plan of vacuum vessel support mock-up are also introduced.

The international thermonuclear experimental reactor (ITER) vacuum vessel (VV) upper port has a trapezoidal/rectangular cross-section and consists of a port stub, a stub extension and a port extension with a connecting duct. To investigate the structural integrity and to increase the structural reliability of the VV and ports, the structural analyses of the upper port structure have been performed. Two advanced designs from the ITER international team have been deeply analyzed. To verify the strength of the reinforcing ribs for the connecting duct and of the fastening/sealing units, the local analyses utilizing the sub-modeling technique have been performed. The upper port flange based on the original design could withstand design loads, but the flange surface could be detached under the design condition. The advanced design using large superbolts is highly acceptable in the structural design point of view. The deflection of the plug for the other advanced design with a removable flange is relatively large since the stiffness of a port and a plug is reduced by the nut groove and the removable flange.

The poloidal field magnet system of the KSTAR consists of three pairs of coils using the cable-in-conduit conductors cooled by forced super-critical helium. The conductor of PF5 is Nb/sub 3/Sn superconductor with Incoloy 908 conduit, and that of PF6 and PF7 is NbTi superconductor with SS 316LN. The PF coils are self-supporting with regard to radial loads, and they are arranged symmetrically with respect to the equatorial plane. PF5 coil is connected to the TF coil structure at eight points by hinges, while PF6 and PF7 coils are connected at sixteen points by flexible plates to allow relative radial movements. In order to investigate the structural integrity, structural analysis has been conducted including buckling and fatigue analyses. The major design loads are dead weight, assembly loads, thermal load due to cool down, and electromagnetic loads under the critical load conditions. It is found that the PF magnet structures can safely withstand all operating conditions. In addition, AISI 316LN can be substituted for JJ1 as the material of the PF coil structures.

The Central Solenoid (CS) magnet system of the Korea Superconducting Tokamak Advanced Research (KSTAR) device consists of four pairs of superconducting coils compressed with the CS coil structure. The CS coil structure is operated as a preload structure to give an axial compression on the CS coils. The required axial compression is applied partly by using the pre-compression components in assembly stage and by the thermal contraction difference between the coil winding pack and the structure during cool down stage as well. In order to investigate the structural integrities and to increase the structural reliabilities of the KSTAR CS magnet, global and local structural analyses have been performed for various operation scenarios by developing three-dimensional finite element models. From the analysis results, it has been found that the CS magnet system can safely withstand the reference operation scenarios and the structural integrity of the CS magnet complies with requirements of the design criteria for KSTAR magnet system.

The central solenoid (CS) magnet system of the Korea Superconducting Tokamak Advanced Research (KSTAR) device consists of four pairs of segmented CS coils and a CS coil structure. The maximum repulsive force between CS coils is about 12 MN. The functions of the CS structure are to apply preload on the CS coils and to support the repulsive force between CS coils during operation. The designed axial compression of 15 MN at 4.5 K will be applied partly by assembling the preload structure at room temperature with preload of about 13.4 MN and partly by the thermal contraction difference between the CS coils and the structure during cool down. Additional preload will be given by minute adjustment of wedges. The structural analysis of the CS magnet system has been performed to verify the CS structure design reliability.

The toroidal field (TF) magnet system of Korea Superconducting Tokamak Advanced Research (KSTAR) device consists of 16 superconducting coils enclosed in steel cases. The TF cases are wedged along the inboard straight legs to sustain in-plane centering forces. The inter-coil structures contain adjustable shear keys and conical bolts to provide pre-loading in toroidal direction and to resist in-plane and out-of-plane forces, which are the most critical loads on the TF magnet system. For effective cooling of the TF case, a pad-type cooling channel has been designed to ensure structural and thermal stability. In order to investigate the structural integrity and to increase the structural reliability of the KSTAR magnet system, structural analyses have been conducted. From the analysis results, it has been found that the TF magnet structure can safely withstand the reference scenario operations.

An appropriate physical modeling and the corresponding numerical analysis system were developed to predict residual stresses and birefringence in injection molded parts such as a center-gated disk. The Leonov constitutive equation is adopted in order to predict flow-induced residual stresses and birefringence. Also the linear viscoelastic and photoviscoelastic constitutive equation taking into account density relaxation phenomena is employed to investigate the thermally induced residual stresses and birefringence. In the preliminary study, constrained quenching was investigated to consider only thermally induced residual stresses and birefringence. Residual stresses are tensile at the center, become compressive near the surface and then return to tensile again at the surface. Flow-induced birefringence has two peaks each of which originated from the filling and packing stages, respectively, and the thermally induced peak has a little flat shape over the whole thickness. Free volume theory was effective in predicting thermally induced residual stresses and birefringence.

Powder Injection Molding (PIM) filling process is one of the key processes towards a successful PIM. In this regard, the methods of slip characterization of powder-binder mixtures and a quasi-3-dimensional finite element simulation program based on Hele-Shaw approximation has been presented.In contrast to conventional injection molding of thermoplastics, there are many PIM parts that include thick regions. To simulate such thick PIM parts properly, a full 3-dimensional simulation program is needed. In this regard, we have been developing a full 3-dimensional finite element program for PIM filling process with the slip phenomena taken into account. For a computational efficiency, a pre-meshed finite element mesh was used with a scalar fill-factor to automatically update the computational domain during the filling.

Many particle-filled materials, such as powder/binder mixtures, are known to show slip phenomena at a solid wall. It is thus of great importance to characterize the slip phenomena for rheological data of particle-filled plastic materials and ultimately to introduce an appropriate slip modeling into the numerical simulations of the extrusion process. In order to simulate screw extrusion processes of such particle-filled materials, numerical analysis programs were developed via a finite element method and a finite difference method for quasi three-dimensional and two-dimensional flow models of extrusion processes, respectively, with the slip phenomena taken into account in terms of a slip velocity. The present paper presents detailed numerical methods to incorporate the slip velocity as a function of wall shear stress and discusses essential slip effects in the screw extrusion process using the slip-corrected and uncorrected viscosity data for both the two-dimensional flow and the quasi three-dimensional flow model. It was confirmed that the quasi three-dimensional result at the center line of the channel from the finite element analysis was in good agreement with the two-dimensional one from the finite difference analysis. Slip effects were found to be very significant on the overall flow behavior during the extrusion process from the numerical results based on viscosity data without the slip correction. These deviated from those based on the slip-corrected viscosity data, especially in analyzing the screw characteristics.

Our experimental data from a capillary rheometer clearly show that powder/binder mixtures for powder injection molding (PIM) experience so-called slip phenomena at the wall, like many particle-filled materials. It is thus of great importance to characterize quantitatively the slip, together with shear-thinning viscosity data of power/binder mixtures in view of proper numerical simulations of the PIM filling process. The slip at the wall could be quantified in terms of a slip velocity or in terms of a very thin slip layer. The present paper adopted the well-known Mooney's method for determining slip velocity, whereas the slip layer thickness was determined by a newly-proposed method. The slip velocity, or the slip layer thickness, thus determined were then introduced into the finite element analysis of the PIM filling process. This was found to have a significant effect on the overall flow behavior during the injection molding filling.

The effects of various dosages of equine chorionic gonadotropin (eCG) on superovulation induction for in vivo and in vitro embryo production were examined in stray cats (Felis catus). Cats (n=286) were allocated into five treatment groups with 0, 50, 100, 200, or 400 IU eCG, followed by 100 IU human chorionic gonadotropin (hCG). In vivo- and in vitro-produced blastocysts were obtained by artificial insemination (AI) and in vitro fertilization (IVF), somatic cell nucleus transfer (SCNT), or parthenogenetic activation (PA). The percentage of cats that developed mature follicles, the percentage of cats with collected embryos, and the mean number of in vivo blastocysts per cat were higher in the 200 IU treatment group (43.9%, 31.8%, and 1.53, respectively) compared with those of the other groups (P

The objective was to evaluate the effect of cytoplasmic lipid content on the embryonic developmental efficiency of bovine in vitro embryo production (IVP) embryos. Ovaries from Korean native cows (Bos taurus coreanae) were collected from a local abattoir, and cumulus-oocyte complexes (COCs) were recovered from follicles 2 to 8mm in diameter. The oocytes were divided into three groups, dependent on their cytoplasm color: pale color (PC), brown color (BC), and dark color (DC). The COCs were fertilized using frozen-thawed semen from a single Hanwoo bull. Based on measurement of the cytoplasmic color intensity of oocytes after 22h of in vitro maturation (IVM), the DC group had lower (P

Recently polymer arresters are being used widely, but we don't have appropriate long term characteristic test methods. Therefore, we need to develop a special test facility to evaluate long term reliability of polymer arresters. Its polymeric housing can be degraded by environmental stress and the interface between housing and inner module can be affected by moisture absorption. This moisture absorption can cause leakage current and tracking in the interface. We developed a multi-stress accelerated ageing test facility to simulate field conditions including UV, temperature, humidity, voltage, salt fog and rain. In addition, we carried out field exposure test at the outdoor test yard and characteristic analysis of field operated specimens to evaluate the accelerating factor of this accelerated aging test.

RESURF LDMOS transistors are utilized in high side driver applications and other applications that mandate electrical isolation between source and substrate by using isolated RESURF technology. However, the BCD process using conventional isolated RESURF LDMOS structures cannot provide high efficiency vertical NPN transistors due to the dependence of the RESURF LDMOS BV/sub dss/ (source to drain breakdown voltage) upon the epi thickness. In this paper, we propose a new isolated RESURF LDMOS. With the use of n-well near the drain region, we can avoid electric field concentration below the drain region. P-well dose, p-well length and extended drain dose should be optimized to reduce surface field of the proposed isolated RESURF LDMOS regardless of epi thickness.

A compensating ion-implantation method is introduced to make self-aligned extended-drain of 30 V lateral NMOS and PMOS transistors with the only one mask and to help the improvement of electrical SOA through the shift of the critical electric field position. In general, high voltage lateral MOS has been useful for high current and high voltage applications. In that case, we have to check up the critical electric field position and the current flow line occurring hot-carrier injection phenomenon because it results in unfavorable device destruction by secondary breakdown. In this paper, we shifted the critical electric field position from n+ drain edge to n+ drain bottom using self-aligned extended-drain formed by compensating ion-implantation. As a result, the occurrence of the secondary breakdown due to Kirk effect would be postponed.

Hierarchical Cu2ZnSnS4 nanostructures with various morphologies and sizes have been synthesised successfully using a simple solvothermal reaction. For the control of the size and morphology of Cu2ZnSnS4, polyvinylpyrrolidone was used as a structure-directing ligand. By changing the molecular weights and concentrations of the polyvinylpyrrolidone ligands, we prepared unique Cu2ZnSnS4 nanostructures ranging from discrete nanoparticle aggregates to nanoflower-like particles. Owing to the unique control of the nanostructures and their ecofriendly nature, the nanoflower-like Cu2ZnSnS4 materials are promising as excellent absorber materials for low-cost solar cells.

ZnO nanowire arrays were synthesised for dye-sensitised solar cell applications using the chemical bath deposition technique. To study the effect of the particle size in the seed layer on the growth and resultant photoconversion efficiency, we prepared various seeded FTO substrates by repeating the seed layer sol-gel coating process. It was found that changing the number of coating process merely increases the particle size of the ZnO seeds, and the increase in the seed particle size induces low growth rates. In addition, to enhance the nanowire growth rates, ammonia was added with polyethylenimine. Based on various characterisations such as XRD, SEM, and J-V curves, we discuss the effect of ammonia on the growth rates of ZnO nanowire, and suggest the optimum ammonia concentration for solar cell applications.

Using a projection theorem the time- and temperature-dependent spin correlations and their wavevector-dependent frequency transforms are obtained in the Oguchi model of the Heisenberg antiferromagnet. The results obtained are valid for all spin values but for only a limited range of temperature.

Exact expressions are obtained for dynamical spin correlations and their wavevector dependent frequency transforms in the Oguchi model of Heisenberg ferromagnet at any temperature.

The magnetic neutron scattering function for a Heisenberg antiferromagnet with spin 3 2 per atom in a bcc lattice at finite temperature is evaluated from first principles in the Bethe-Peierls-Weiss cluster model, and the temperature dependence of the frequencies and half widths of spin excitations is deduced from the scattering function for the temperature range 0 ⩽ T T N ⩾ 1.5. The results show the essential features observed in recent experiments.