• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.16 no.3
• /
• pp.359-367
• /
• 2018

Long-lived Small Modular Reactors are being promoted as an innovative way of catering to emerging markets and isolated regions. They can be operated continuously for decades without requiring additional fuel. A novel configuration of long-lived reactor core employs a mixed neutron spectrum, providing an improvement in nonproliferation metrics and in safety characteristics. Starting with a base sodium reactor design, moderating material is inserted in outer core assemblies to modify the fast spectrum. The assemblies are shuffled once during core lifetime to ensure that every fuel rod is exposed to the thermalized spectrum. The Mixed Spectrum Reactor is able to maintain a core lifetime over two decades while ensuring the plutonium it breeds is below the weapon-grade limit at the fuel discharge. The main drawbacks of the design are higher front-end fuel cycle costs and a 58% increase in core volume, although it is alleviated to some extent by a 48% higher power output.

• Journal of Digital Convergence
• /
• v.12 no.12
• /
• pp.37-47
• /
• 2014

The characteristics of the spectrum, which are necessary for mobile telecommunication services, may determine the advantage of operators' competition for mobile services. We have a focus on the possibility that there would be the core spectrum within the frequencies. We define the core spectrum of frequencies in terms of 4 criteria (global source/roaming, cost-effectiveness, the experience of utilization and the possibility of use). They are based on the aspects of applicative and economic effectiveness by not technological and but market conditions. We have explored the current core spectrum by using the stepwise selection from these criteria. Our result indicates that the core spectrum may be movable with the development of technology and the flow of time. The results of this paper could be practically used as the reasonable justifications of the policies for not only the competition management but also the alignment about the frequencies for mobile telecommunication.

• Nuclear Engineering and Technology
• /
• v.35 no.4
• /
• pp.336-346
• /
• 2003

This study is intended to evaluate the dependency of TRU recycling characteristics on the neutron spectrum shift in a Pb-Bi cooled core. Considering two Pb-Bi cooled cores with the soft and the hard spectrum, respectively, various characteristics of the recycled core are carefully examined and compared with each other. Assuming very simplified fuel cycle management with the homogeneous and single region fuel loading, the burnup calculations are performed until the recycled core reached to the (quasi-) equilibrium state. The mechanism of TRU recycling toward the equilibrium is analyzed in terms of burnup reactivity and the isotopic compositions of TRU fuel. In the comparative analyses, the difference in the recycling behavior between the two cores is clarified. In addition, the basic safety characteristics of the recycled core are also discussed in terms of the Doppler coefficient, the coolant loss reactivity coefficient, and the effective delayed neutron fraction.

• Journal of Technologic Dentistry
• /
• v.23 no.2
• /
• pp.189-202
• /
• 2002

A study on reflective spectrum between In-Ceram alumina plate(IAP) and IPS empress 2 plate were carried out in order to determine the difference of reflective spectrum rates between materials and between thicknesses of materials(0.8mm, 1.0mm, 1.2mm) by visible wave. The rates are measured by spectrophotometer(Top scan model TC-1800). And an analysis of ANOVA and paired sample t-test were carried out. The results are summarized as follows. 1. The reflective rates of IAP and IPS increased slowly as visible wave spectrum increased. 2. The difference of reflective rates of IAP between 0.8mm and 1.0mm is significant but a little(less than 1%). The differences of reflective rates of IAP between 0.8mm and l.2mm and between 1.0mm and l.2mm are significant(8%, 10% ). 3. The differences of reflective rates of IPS between 0.8mm and 1.0mm and between 0.8mm and 1.2mm and between 1.0mm and 1.2mm are significant(0.06 %, 0.01 %, 2 %). 4. The differences of reflective rates of 0.8mm, 1.0mm between IAP and IPS are significant but a little(less than 0.9%, 0.5%). The difference of reflective rates of l.2mm between IAP and IPS is significant and larger than the other thicknesses relatively(7 %).

• Journal of the Korean Vacuum Society
• /
• v.15 no.1
• /
• pp.31-36
• /
• 2006

By analyzing the Ge 34 core-level photoelectron spectrum, we studied the structure of the $Li/Ge(111)-3\times1$ surface. Two surface related components tying on either side of the main bulk peak were identified in the Ge 3d spectrum. The existence and the position of the two surface components in the core-level spectrum from $Li/Ge(111)-3\times1$ is similar to those of the $Li/Ge(111)-3\times1$, suggesting the similarities in structure of the two surfaces. The core-level photoelectron spectra of the Li-induced $Li/Ge(111)-3\times1$ surface are well consistent with the honeycomb-chain-channel model, which was proposed as the structure of the $Si/Ge(111)-3\times1$ induced by alkali metals.

• Agricultural and Biosystems Engineering
• /
• v.7 no.1
• /
• pp.8-12
• /
• 2006

This study was conducted to develop a real-time internal quality evaluation technique for Korean red ginseng using NIR spectroscopy while they were moving to be graded. Internal qualities of Korean red ginseng were defined by color, amount of white core and cavity in the red ginseng. To evaluate the internal quality, PLS (Partial Least Square) model was developed. Spectrum saturation can be occurred when most red ginseng has a sound internal quality expressed by higher light transmittance ratio, but that could not found in the ginseng of internal white core under the same light situation. And, if spectrum saturation is obtained, it is hard to identify the exact information of internal quality. In order to evaluate of the internal quality regardless of having internal normal core or white core, an integral time controlled method was used to obtain traditional spectrum. This procedure was applied in real-time process when red ginseng was moving to be graded in the line. Among the 450 samples including 223 internal normal ginsengs and 227 internal white core ginsengs, 315 ginsengs (70%) were used to develop a calibration model and 135 ginsengs were spent to validate the model. The result of quality evaluation by the model was very good showing SEP and bias were 0.3573 and 0.0310, respectively, and the accuracy was 95.6%.

• Earthquakes and Structures
• /
• v.15 no.4
• /
• pp.443-452
• /
• 2018

In this paper the new intensity measures (IMs) for probabilistic seismic analysis of RC high-rise buildings with core wall structural system are proposed. The existing IMs are analysed and the new optimal ones are presented. The newly proposed IMs are based on the existing ones which: 1) comprise a wider range of frequency velocity spectrum content and 2) are defined as the integral along the velocity spectrum. In analysis characteristics of optimal IMs such as: efficiency, practicality, proficiency and sufficiency are considered. As prototype buildings, RC high-rise buildings with core wall structural system and with characteristic heights: 20-storey, 30-storey and 40-storey, are selected. The non-linear 3D models of the prototype buildings are constructed. 720 non-linear time-history analyses are conducted for 60 ground motion records with a wide range of magnitudes, distances to source and various soil types. Statistical processing of results and detailed regression analysis are performed and appropriate demand models which relate IMs to demand measures (DMs), are obtained. The conducted analysis has shown that the newly proposed IMs can efficiently predict the DMs with minimum dispersion and satisfactory practicality as compared to the other commonly used IMs (e.g., PGA and $S_a(T_1)$). The newly proposed IMs overcome difficulties in calculating of integral along the velocity spectrum and present adequate replacement for IMs which comprise a wider range of frequency velocity spectrum content.

• Nuclear Engineering and Technology
• /
• v.53 no.8
• /
• pp.2716-2727
• /
• 2021

The core shroud is one of the most important internal components of the reactor vessel internals because it meets the neutron fluence directly emitted by the nuclear fuel. In particular, dynamic effects for an earthquake should be evaluated with respect to the neutron irradiation flux. As a prerequisite to this study, simplified and detailed finite element models are developed for the core shroud using the ANSYS Design Parametric Language. Using the El Centro earthquake, seismic analyses are performed for the simplified and detailed core shroud models. Modal characteristics are obtained and their results are used for a time history analysis. Response spectrum analyses are also performed to access the degree of seismic excitation. The results of these analyses are compared to investigate the response characteristics between the simplified and detailed core shroud models from the time history and response spectrum analyses.

• Nuclear Engineering and Technology
• /
• v.30 no.1
• /
• pp.8-16
• /
• 1998

In this work a method to detect the vibrational peak and to decide the vibrational mode of detected peak for core internal vibration monitoring system which is particularly concerned on the core support barrel (CSB) and fuel assemblies is developed. Flow induced vibration and aging process in the reactor internals cause unsoundness of the internal structure. In order to monitor the vibrational status of core internal, signals from the ex-core neutron detectors are transformed into frequency domain. By analyzing transformed frequency domain signal, an analyst can acquire the information on the vibrational characteristics of the structures, i.e., vibration frequencies of each component, vibrational level, modes of vibration, and the causes of the abnormal vibration, if any. This study is focused on the development of the automated monitoring system. Several methods are surveyed to define the peaks in power spectrum and fuzzy theory is used to automatic detection of the vibrational peaks. Fuzzy algorithm is adopted to define the modes of vibration using the peak values from fuzzy peak recognition, phase spectrum, and coherence spectrum.

• Applied Biological Chemistry
• /
• v.46 no.4
• /
• pp.305-310
• /
• 2003

Hydrophobic core variant of ubiquitin appeared to have partially folded structure at pH around 2. The intrinsic tryptophan fluorescence emission maximum of this ubiquitin variant at pH 2 showed slight blue shift compare to that of unfolded state, suggesting that some residual tertiary structures remain in this solvent condition. At the same solvent condition, this ubiquitin variant binds with hydrophobic dye, 8-anilinonaphthalene-1-sulfonic acid(AMS), which is known to bind to exposed hydrophobic surface. Furthermore, far-UV circular dichroic spectrum of this ubiquitin variant in the diminished pH was remarkably different from the far-UV CD spectrum of the native state or unfolded state. Based on the molar ellipticity at 220 nm, this ubiquitin variant at pH 2 appeared to have significant amount of secondary structures. All these observations suggest that this ubiquitin variant in the diminished solvent pH has loosely folded hydrophobic core with some secondary structures, which are key features of molten globule conformation. Since molten globule has long been considered as a protein folding intermediate, it is considered that this hydrophobic core variant ubiquitin will serve as a valuable model to study protein folding process.