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The selection and effective utilization of peak-fitting software for conventional gamma-ray spectrum analysis is significant for accurate determination of the mass fraction of elements, particularly in complex peak regions. Majority of the peak-fitting programs can derive similar peak characteristics for singlet peaks, but very few programs can deconvolute multi-peaks in a complex region. The deconvolution of multi-peaks requires special peak-fitting functions, such as left and right-skew distributions. In the this study, 843.76 keV (27Mg) peak area from the complex region (840 keV–850 keV) determined and compared using four different peak-fitting programs, namely, GammaVision, Genie2000, HyperLab, and HyperGam. The 843.76 keV peak interfered with 841.63 keV (152mEu) and 846.81 keV (56Mn). The total Mg concentration was determined through k0-instrumental neutron activation analysis by applying the isotopic interference correction factor 27Al(n,p)27Mg through the simultaneous determination of Al concentration. HyperLab and HyperGam peak-fitting programs reported consistent peak areas, and resultant concentrations agreed with the certified values of matrix-certified reference materials.

Non-destructive testing (NDT) technology is a widely used inspection method for agricultural products. Compared with the conventional inspection method, there is no extensive sample preparation for NDT technology, and the sample is not damaged. In particular, NDT technology is used to inspect the internal structure of agricultural products infested by pests. The introduction and spread of pests during the import and export process can cause significant damage to the agricultural environment. Until now, pest detection in agricultural products and quarantine processes have been challenging because they used external inspection methods. However, NDT technology is advantageous in these inspection situations. In this pilot study, we investigated the feasibility of X-ray computed tomography (X-ray CT) and magnetic resonance imaging (MRI) to identify pest infestation in agricultural products. Three kinds of artificially pest-infested fruits (mango, tangerine, and chestnut) were non-destructively inspected using X-ray CT and MRI. X-ray CT was able to identify all pest infestations in fruits, while MRI could not detect the pest-infested chestnut. In addition, X-ray CT was superior to the quarantine process than MRI based on the contrast-to-noise ratio (CNR), image acquisition time, and cost. Therefore, X-ray CT is more appropriate for the pest quarantine process of fruits than MRI.

The neutron flux distribution in the core region of the JRTR was measured through the neutron activation analysis method. Sample mount and a tool for withdrawing the sample mount were devised to irradiate the Au wires and foils. The measured data were compared with calculated values to confirm the reliability of the power distribution calculation. The reactor power during irradiation was estimated to be 9% lower than indications of power monitoring systems calibrated at around 10 μW. The measured transversal and axial neutron reaction rate distributions showed agreement within 1.32% difference with the calculated results.

Nowadays, Neutron Transmutation Doping (NTD) of silicon ingots is successfully used to produce the n-type semiconductor. NTD’s main advantage, which is to say its uniform resistivity distribution, leads to semiconductor materials with fewer defects and, accordingly, better performance. Radial uniformity usually is achieved by rotating the ingot during irradiation. However, due to neutron attenuation, the neutron reaction rate in the ingot’s center region generally is lower than in the outer region. Such radial non-uniformity becomes severe when the diameter of the ingot is larger, or when materials with a high-neutron-reaction cross-section are used. In this study, a slit method to selectively shield neutrons that react with the ingot’s outer region and increase radial uniformity thereby was devised and herein is proposed. Dark matter (DM), graphite, stainless steel (SS) and borated stainless steel (BSS) were considered as shielding materials in a Monte Carlo-simulation-based evaluation of the radial uniformity of a Silicon Carbide (SiC) ingot. In the case of DM, the relative reaction rate at the center region of the ingot was increased; graphite did not enhance the radial uniformity; for both SS and BSS, the radial uniformity was under 1% with the optimized slot size. Therefore, it is expected that if the NTD technique is used in concert with the proposed slit method, semiconductors of exceedingly uniform dopant distribution can be produced.

In the process of neutron transmutation doping (NTD), Si, C, and impurities in the SiC become radioactive nuclides by neutron capture reaction (n, $\gamma $ ) and several threshold reactions. The radiations emitted from the residual radionuclides constantly damage the SiC until they completely decay. The radiation damage can create many defects in the SiC, and the defects can reduce the electron mobility and distort the band structure. This radiation damage to the SiC should be evaluated in terms of quality management. In order to quantify the sources of radiation damage, time variations of the residual radionuclides’ radioactivity in 5-in cylindrical SiC ingot after neutron irradiation were calculated using the DCHAIN program linked to the particle and heavy ion transport code system (PHITS). In the calculation, it was assumed that the SiC ingot was irradiated in the NTD1 irradiation hole of the High-Flux Advanced Neutron Application Reactor (HANARO) at the Korea Atomic Energy Research Institute (KAERI). The energy spectrum of neutrons in the HANARO NTD1 irradiation hole calculated by using the Monte Carlo N-particle code version 6.1 (MCNP6.1) code was considered as a neutron source for the calculation. Based on the radioactivity data, the total flux and energy spectra of the electrons and gamma-rays in the SiC were calculated to analyze the properties of the radiation sources. Most of the radiations were emitted from the beta decay of 31Si, but they decayed early, and radionuclides with a relatively long half-life, such as 59Fe and 32P, became the major radiation sources. Finally, the radiation damage was calculated in the displacement per atom (DPA) unit. The time variations of the DPA rate and cumulative DPA in the SiC are presented.

This study investigates design procedures and experimental results of power converters for the tidal current power generation system installed at Jin-Do in Korea. The designed power converters consist of a grid-connected converter and a power converter to control the permanent magnet synchronous generator. Many theoretical control algorithms are required to design the power converter for a tidal current power generation system. In this study, the effective algorithm of power converters for a tidal current generation on the phase lock loop algorithm of the grid-connected converter and maximum power point tracking algorithm of generator-side converter was investigated. For the feasibility study of the commercial tidal current power generation system, the down-scaled 20-kW tidal generation system has been installed and empirically evaluated.

Because wind turbines and tidal current generation rely on irregular wind or tidal speed, maximum power-point tracking (MPPT) control is required in order to generate maximum turbine power. The most common turbine generation is obtained by employing the MPPT scheme using the tip speed ratio (TSR). However, this scheme has a disadvantage in that it relies on the characteristics of tidal current turbines, and it requires expensive tidal current speed-measurement equipment. The tidal current speed measurement is also affected by the installed location and distance to the equipment. To avoid these disadvantages, this paper proposes the maximum power control scheme using perturb and observe (P&O) for tidal current generation systems. The proposed P&O MPPT scheme can generate maximum power regardless of the characteristics of the turbine and the information about the tidal current speed. The reliability and suitability of the proposed scheme are proven using simulation and experiment results at the tidal current generation laboratory in Jin-do, South Korea.

To improve the accuracy and safety of irradiation tests in High flux Advanced Neutron Application ReactOr (HANARO), the nuclear energy deposition rate, which is called nuclear heating, was estimated for an irradiation capsule with an iridium sample in the irradiation hole in order. The gamma rays emitted from the radioisotopes (RIs) of the structural materials such as flow tubes of fuel assemblies and heavy water reflector tank were considered as radiation source. Using the ORIGEN2.1 code, emission rates of delayed gamma rays were calculated in consideration of the activation procedure for 8 years and 2 months of HANARO operation. Calculated emission rates were used as a source term of delayed gamma rays in the MCNP6 code. By using the MCNP code, the nuclear heating rates of the irradiation capsules in the inner core, outer core, and heavy water reflector tank were estimated. Calculated nuclear heating in the inner core, outer core, and heavy water reflector tank were 200–260 mW, 80–100 mW, and 10 mW, respectively. Keywords: Delayed Gamma-ray, HANARO, MCNP, Nuclear Heating, Neutron Irradiation, ORIGEN, Reactor Structure

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.

A calibration technology of the self-powered neutron detectors (SPNDs) using a large vertical irradiation hole of HANARO is developed. The 40 Rh-SPNDs are installed on the polycarbonate plastic support, and the gold wires with the same length as the effective length of the rhodium emitter of the SPND are also installed to measure the neutron flux on the SPND. They are irradiated at a low reactor power, and the SPND current is measured using the pico-ammeter. The external gamma-rays which affect the SPND current response are analyzed using the Monte Carlo simulation for various irradiation conditions in HANARO. It is confirmed that the effect of the external gamma-rays to the SPND current is dependent on the reactor characteristics, and that it is affected by materials around the detector. The current signals due to the external gamma-rays can be either positive or negative, in that the net flow of the current may be either in the same or the opposite direction as the neutron-induced current by the rhodium emitter. From the above procedure, the effective calibration methodology of multiple SPNDs using the large hole of HANARO is developed. It could be useful for the calibration experiment of the neutron detectors in the research reactors.

A neutron depth profiling (NDP) system has been designed and developed at HANARO, a 30 MW research reactor at the Korea Atomic Energy Research Institute (KAERI). The KAERI-NDP system utilizes cold neutrons that are transported along the CG1 neutron guide from the cold neutron source and it consists of a neutron beam collimator, a target chamber, a beam stopper, and charged particle detectors along with NIM-standard modules for charged particle pulse-height analysis. A 60 cm in diameter stainless steel target chamber was designed to control the positions of the sample and detector. The energy distribution of the cold neutron beam at the end of the neutron guide was calculated by using the Monte Carlo simulation code McStas, and a neutron flux of 1.8×108 n/cm2 s was determined by using the gold foil activation method at the sample position. The performance of the charged particle detection of the KAERI-NDP system was tested by using Standard Reference Materials. The energy loss spectra of alpha particles and Li ions emitted from 10B, which was irradiated by cold neutrons, were measured. The measured peak concentration and the areal density of 10B in the Standard Reference Material are consistent with the reference values within 1% and 3.4%, respectively.

Prompt gamma activation analysis (PGAA) is a nuclear analytical technique for non-destructive determination of elemental and isotopic compositions. The principle of PGAA technique is based on detection of captured gamma-ray emitted from an analytical sample while being irradiated with neutrons. Use of a cold neutron beam guide greatly reduces the gamma-ray background at the analytical sample while maintaining a neutron capture rate is comparable to that of standard thermal neutron PGAA. A new cold neutron induced prompt gamma activation analysis (CN-PGAA) system has been under construction since April of 2009 at the HANARO Cold Neutron Building (KAERI, Republic of KOREA). In this study, the Compton suppression factor of the CN-PGAA system was estimated to be 5.5 using a 60Co radioactive source in conjunction with the MCNPX simulations. Several parameters of the CN-PGAA system were studied to estimate and optimize the performance of the system: scintillation material in the guarded detector of a Compton suppression spectrometer (CSS); the relative positions of the HPGe detector and annular detector; and the distance between the HPGe detector and back catcher BGO detectors of the CSS. In addition, the neutron ray-trace simulation package, McStas, was adopted to predict the neutron flux and wavelength distribution at the end of the cold neutron beam guide. These results served as input for the MCNPX simulation of the CN-PGAA system.

These days, many cable-stayed bridges were constructed in accordance with the trend in Korea. At the moment, construction technology of cable-stayed bridges has been remarkably developed but design technology still relies upon foreign technology very much. The cable anchor system that is one of key technologies of cable-stayed bridge brings powerful cable tension to produce local stress concentration and to disturb stress seriously, so for safety must be designed by a local detailed analysis is required. But without a clear design standard or design theory relying on F.E.M, and engineers don`t understand theoretical basic mechanism of cable anchor system. As a result, engineers can be lose their judgement. Accordingly, this study examined theoretical design flow of fixing pipe in guide pipe-anchor system and additional considerations, in accordance with design standards at home and abroad to keep them in order and to suggest supplementary design flow.

The line shape functions for the Doppler-broadened gamma ray spectrum are considered in the 10 B(n,αγ) 7 Li reaction occurring in a surrounding medium where the excited 7 Li nucleus is slowed down and stopped before decay. The phenomenological form of the stopping power was used for the broadening effect. Convolution with the detailed response of a germanium detector is taken into consideration for the simplest case of solely electronic stopping. A numerical study for the analysis of 10 B by thermal neutron capture is conducted by performing a parametric search and fitting the measured spectrum in a leastsquares approach. In comparison with the previous numerical approach using the same analysis, the computational speed is increased and reliable information concerning the stopping power of the medium is obtained while estimating the uncertainty. Implementation of the routine analysis of 10 B is facilitated on a recent version of the gamma ray spectrum analysis package HyperGam.

The Advanced Spent Conditioning Process (ACP) developed by the KAERI is based on pyrometallurgy and the electrolytic reduction plays a central role in transforming spent oxide fuels into metals. The constituents of the spent fuels are distributed between a salt and a reduced metal phase during electrolysis. Lithium metal is produced in a molten LiCl-Li2O cell and then it reacts with the metal oxides of the spent fuel producing Li2O and reduced metals. By focusing on the activity of Li2O and the electric potential, the electrolytic reduction process of the ACP is discussed. Thermodynamic considerations are defined and operation conditions are proposed including Li2O activity and cell potential.

The purpose of this study is to compare the efficacy of intratympanic steroid injection (ITSI) with that of systemic steroids as an initial treatment of sudden sensorineural hearing loss (SNHL) with diabetes.Prospective, nonrandomized multicenter clinical trial.Multicenter study in Busan and Masan, South Korea.A total of 114 sudden SNHL patients who were diagnosed with diabetes were divided into peroral (PO) group (n = 48), intravenous (IV) group (n = 32), and intratympanic (IT) group (n = 34). In the PO group, prednisolone was used orally for 10 days, per schedule. In the IV group, prednisolone was administered intravenously for seven days, followed by oral administration of tapered doses for another several days. In the IT group, dexamethasone was injected into the tympanic cavity four times within a two-week period. Hearing outcome was assessed before and after the treatment.All groups showed significant improvement with criteria of 15 dB (P0.05). However, there was no significant difference in hearing gain and recovery rate among groups (P0.05). Systemic steroid treatment was stopped for two patients in the IV group and for one in the PO group due to uncontrolled hyperglycemia. However, in the IT group, there were no patients who failed to control their blood sugar level.ITSI is as effective as systemic steroid treatment for sudden SNHL patients with diabetes and it can avoid undesirable side effects. Therefore, we consider ITSI to be a more reasonable alternative as an initial treatment for sudden SNHL patients with diabetes.

This paper proposes an improved synchronization control scheme of a low cost 400 Hz power supply for no-break power transfer. In the case of aircraft application, the 400 Hz power supply called as ground power units (GPU) has been accepted as external electrical power system during stopovers in ground. When transferring from one power source to the other, there is a momentary break in supply. To transfer without a break, the two power sources are momentarily connected in parallel. The proposed synchronization control is achieved by connecting an existing synchronization bus to a voltage zero-crossing signal of a generator power with discrete logic ICs and analog circuits. Therefore, this proposed control scheme is rather simple and the cost may be decreased, compared with expensive controller such as DSP and CAN. The practical feasibility of the proposed control scheme is proved by simulation.

Suggests a receding horizon control of discrete-time linear systems that possess randomly jumping parameters described by finite-state Markov processes. The suggested receding horizon control is based on a finite input and state horizon cost with a finite terminal weighting matrix. For the guaranteed stability of the closed loop system under the receding horizon control, we propose a matrix inequality condition on the terminal weighting matrix. The terminal weighting matrix can be obtained by solving a LMI (linear matrix inequality). The receding horizon control and the matrix inequality condition are easily computed for time-varying Markovian jump linear systems, and this receding horizon control can be used in practical applications.

This paper presents an approach to obtain the optimal gains of a discrete two degrees of freedom PID controller. The optimal gains are obtained by minimizing the performance index of the GPC (generalized predictive control). The tracking performance is improved by the feedforward controller which is tuned through the proposed method. It is also shown that this method in one commercial loop controller operates well with a PC based simulation plant.