• 한국전문물리치료학회지
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• 제16권2호
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• pp.50-58
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• 2009

The purpose of this study was to test that motor skill training enhance motor function and cerebellar development. Using an animal model of fetal alcohol syndrome-which equates peak blood alcohol concentrations across developmental period-critifical periods for the effect of alcohol on body and cerebellar weigh was examined. The effect of motor skill training on motor function and cerebellar development of rat exposed alcohol on postnatal days 4 through 10 were studied. Newborn rats were assigned to one of two groups: (1) Control group (CG), via artificial rearing to milk formula and (2) experimental groups (EG), via 4.5g/kg/day of ethanol in a milk solution. After completion of the treatments, the pups were fostered back to lactating dams, and wearing they were raised in standard caged until they were postnatal 48 days. Rats from experimental group of postnatal treatment then spent 10 days in one of two groups: Experimental group II (EGII) was had got motor skill training (training traverse a set of 6 elevated obstacles) for 4 weeks. Experimental group I (EGI) was not trained. Before sacrificing, the rat got examined two behavioral test, body weigh and cerebellar weigh, then coronal sections were processed. The section was investigated the Purkije cell in the cerebellum using light microscope. The results of this study were as follows. 1. In body weight test, the outcome of alcohol groups were significantly lower than the normal group. 2. In cerebellar weight test, the outcome of EGI were significantly lower than CG and EGII. 3. In motor behavioral test, the outcome of EGI was significantly lower than NG and EGII. 4. In Purkinje cells counting test, the outcome of EGI was significantly lower than the NG and EGII. These result suggest that improved motor function induced by motor skill training after postnatal exposure is associated with dynamically altered expression of Purkinje cells and that is related with cerebellar function. Also, these data can potentially serve as a model for therapeutic intervention.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.837-846
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• 2014

A lead slowing down spectrometer (LSDS) is under development for analysis of isotopic fissile material contents in pyro-processed material, or spent fuel. Many current commercial fissile assay technologies have a limitation in accurate and direct assay of fissile content. However, LSDS is very sensitive in distinguishing fissile fission signals from each isotope. A neutron spectrum analysis was conducted in the spectrometer and the energy resolution was investigated from 0.1eV to 100keV. The spectrum was well shaped in the slowing down energy. The resolution was enough to obtain each fissile from 0.2eV to 1keV. The detector existence in the lead will disturb the source neutron spectrum. It causes a change in resolution and peak amplitude. The intense source neutron production was designed for ~E12 n's/sec to overcome spent fuel background. The detection sensitivity of U238 and Th232 fission chamber was investigated. The first and second layer detectors increase detection efficiency. Thorium also has a threshold property to detect the fast fission neutrons from fissile fission. However, the detection of Th232 is about 76% of that of U238. A linear detection model was set up over the slowing down neutron energy to obtain each fissile material content. The isotopic fissile assay using LSDS is applicable for the optimum design of spent fuel storage to maximize burnup credit and quality assurance of the recycled nuclear material for safety and economics. LSDS technology will contribute to the transparency and credibility of pyro-process using spent fuel, as internationally demanded.

• Journal of Korean Society for Atmospheric Environment
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• 제17권E3호
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• pp.91-99
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• 2001

Plasma reactor was used to generate a high potential difference between two surfaces of concentric pyrex tubes by electrical current. The annular gap of the reactor was calculated by trial and error from the breakdown voltage equation and set at 0.45 cm. The overall objective of this research was to know the effects of the frequency, humidity, and residence time on the formation of nitrogen oxides in a plasma reactor. The primary voltage varied from 50 to 90 volts and the frequency was varied in increments of 10 Hz from 60 to 650 Hz at the primary voltage of 90. The increase in the secondary voltage was not linear but exponential at high frequencies. At a maximum concentration of about 745 ppm, the frequency and secondary voltage was 600 Hz and 4,200 volts, respectively. All tests for the effects of humidity on NO$_{x}$ production were performed at the optimal setting of 90 colts and 600 Hz frequency. Since the NO$_{x}$ production was not an one dimensional phenomenon, competing reactions were assumed to occur in the discharge chamber. The sharp peak concentration of 1,810 ppm was observed at 38% of relative humidity, The enhanced production was choked off, and the production rate rapidly dropped to 3 ppm at above 40% of relative humidity. It is assumed that the corona attacks the most vulnerable molecules in the reaction chamber before attacking other more lightly bonded molecules, possibly at humidities above 38% and the optimized 90 volt setting. Thus, there was not enough energy left after attacking all water molecules to decompose an appreciable amount of $N_2$. If nitrogen breakdown does not occur, then oxides of nitrogen are not likely to be produced.ced.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.185-190
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• 2016

Background: In order to measure neutron energy spectra, the conventional Bonner Sphere Spectrometers (BSS) are widely used. In this spectrometer, several measurements with different size Bonner spheres are required. Operators should, therefore, place these spheres in several times to a measurement point where radiation dose might be relatively high. In order to reduce this effort, novel neutron energy spectrometer using an onion-like single Bonner sphere was proposed in our group. This Bonner sphere has multiple sensitive spherical shell layers in the single sphere. In this spectrometer, a band-shaped thermal neutron detection medium, which consists of a LiF-ZnS mixed powder scintillator sheet and a wavelength-shifting (WLS) fiber readout, was looped to each sphere at equal angular intervals. Amount of LiF neutron converter is reduced near polar region, where the band-shaped detectors are concentrated, in order to uniform the directional sensitivity. The LiF-ZnS mixed powder has an advantage of extremely high light yield. However, since it is opaque, scintillation photons cannot be collect uniformly. This type of detector shows no characteristic shape in the pulse height spectrum. Subsequently, it is difficult to set the pulse height discrimination level. This issue causes sensitivity fluctuation due to gain instability of photodetectors and/or electric modules. Materials and Methods: In order to solve this problem, we propose to replace the LiF-ZnS mixed powder into a flexible and Transparent RUbber SheeT type $LiCaAlF_6$ (TRUST LiCAF) scintillator. TRUST LiCAF scintillator can show a peak shape corresponding to neutron absorption events in the pulse height spectrum. Results and Discussion: We fabricated the prototype detector with five sensitive layers using TRUST LiCAF scintillator and conducted basic experiments to evaluate the directional uniformity of the sensitivity. Conclusion: The fabricated detector shows excellent directional uniformity of the neutron sensitivity.

• 천문학회보
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• 제41권1호
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• pp.40.1-40.1
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• 2016

Recent integral-field spectrograph surveys have found that similar-looking early type galaxies have wide range of rotational properties (Emsellem et al. 2007). This finding initiated a new point of view to the galaxies; rotation of galaxy as the first parameter of galaxy classification (Emsellem et al. 2011, Cappellari et al. 2011, for example). Some theoretical studies tried to address the origin of galaxy rotation. Idealized galaxy merger simulations have shown that galaxy-galaxy interactions have significant effects on the rotation of galaxies. Cosmological simulations by Naab et al. 2014 also added some more insights to the rotation of galaxies. However, previous studies either lack cosmological background or have not enough number of samples. Running a set of cosmological hydrodynamic zoom-in simulations using the AMR code RAMSES(Teyssier 2002). we have constructed a sample of thousands of galaxies in 20 clusters. Here we present a kinematic analysis of a large sample of galaxies in the cosmological context. The overall distribution of rotation parameter of simulated galaxies suggests a single peak corresponding to fast rotating galaxies. But when divided by mass, we find a strong mass dependency of galaxy rotation, and massive galaxies are distinctively slow rotating. The cumulated effective of mergers seems to neutralize galaxy rotation as suggested by previous studies (Khochfar et al. 2011, Naab et al. 2014, and Moody et al. 2014). This is consistent with the fact that massive galaxies tend to rotate more slowly after numerous mergers. However, if seen individually, merger can either increase or decrease galaxy rotation depending on mass ratio, orbital parameter, and relative rotation axis of the two galaxies. This explains the existence of some non-slow rotating massive early type galaxies.

• Structural Engineering and Mechanics
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• 제56권6호
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• pp.959-982
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• 2015

In this study, a non-stationary random earthquake Clough-Penzien model is used to describe earthquake ground motion. Using stochastic direct integration in combination with an equivalent linear method, a solution is established to describe the non-stationary response of lead-rubber bearing (LRB) system to a stochastic earthquake. Two parameters are used to develop an optimization method for bearing design: the post-yielding stiffness and the normalized yield strength of the isolation bearing. Using the minimization of the maximum energy response level of the upper structure subjected to an earthquake as an objective function, and with the constraints that the bearing failure probability is no more than 5% and the second shape factor of the bearing is less than 5, a calculation method for the two optimal design parameters is presented. In this optimization process, the radial basis function (RBF) response surface was applied, instead of the implicit objective function and constraints, and a sequential quadratic programming (SQP) algorithm was used to solve the optimization problems. By considering the uncertainties of the structural parameters and seismic ground motion input parameters for the optimization of the bearing design, convex set models (such as the interval model and ellipsoidal model) are used to describe the uncertainty parameters. Subsequently, the optimal bearing design parameters were expanded at their median values into first-order Taylor series expansions, and then, the Lagrange multipliers method was used to determine the upper and lower boundaries of the parameters. Moreover, using a calculation example, the impacts of site soil parameters, such as input peak ground acceleration, bearing diameter and rubber shore hardness on the optimization parameters, are investigated.

• 설비공학논문집
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• 제21권2호
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• pp.94-102
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• 2009

Conceptual design of scroll expander and scroll compressor for 10kW-class Stirling engine utilizing solar energy as heat source has been carried out to estimate the applicability of scroll mechanism for Stirling cycle. CO2 was chosen as working fluid, since it has lower expansion index and higher density among probably usable gases. Gas temperature at the expander inlet was set at $700^{\circ}C$, and that at the compressor inlet was at $40^{\circ}C$. System efficiency reached maximum at the pressure ratio of about 2.5, and the peak efficiency increased with increasing high side pressure. Due to safety concern, the pressure condition of 6 MPa/2.5 MPa was chosen as design condition. Orbiting scroll members for the expander and compressor were designed to have double-sided structure in order to reduce the overall scroll size and to cancel out the axial gas forces acting on the orbiting scroll base plate. By parametric study on the scroll profile, smaller possible size for the scroll members was obtained. With the shaft speed of 3600rpm, the shaft output of the designed scroll expander was calculated to be 45.4kW, while input power for the scroll compressor was 34.5kW, yielding 10.9kW for the output power of the Stirling engine. System efficiency was estimated to be about 7.3%, and overall efficiencies of the scroll expander and compressor were around 84.1% and 88.3%, respectively.

• 대한치과보철학회지
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• 제30권4호
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• pp.582-610
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• 1992

The long-term success of any dental implant is dependent upon the optimization of stresses which occur during oral function and parafunction. Especially, it has been suggested that there is an unique set of problems associated with joining an osseointegrated implant and a natural tooth with a fixed partial denture. For this particular case, although many literatures suggest different ways to avoid high stress concentrations on the bone surrounding the implant under static and dynamic loading conditions, but few studies on the biomechanical efficacy of each assertion have been reported. The purpose of this investigation was to evaluate the efficacies of clinically suggested methods on stress distribution under static load and shock absorption under dynamic load, using two dimensional finite element method. In FEM models of osseointegrated implant-natural tooth supported fixed partial dentures, calculations were made on the stresses in surrounding bone and on the deflections of abutments and superstructure, first, to compare the difference in stress distribution effects under static load by the flexure of fastening screw or prosthesis, or intramobile connector, and second, to compare the difference in the shock absorption effects under dynamic load by intramobile connector or occlusal veneering with composite resin. The results of this analysis suggest that : 1. Under static load condition, using an implant design with fastenign screw connecting implant abutment and prosthesis or increasing the flexibility of fastening screw, or increasing the flexibility of prosthesis led to the .increase in height of peak stresses in cortical bone surrounding the implant, and has little effect on stress change in bone around the natural tooth. 2. Under static load condition, intramobile connector caused the substantial decrease in stress concentration in cortical bone surrounding the implant and the slight increase in stress in bone around the natural tooth. 3. Under dynamic load condition, both intramobile connector and composite resin veneering showed shock absorption effect on bone surrounding the implant and composite resin veneering had a greater shock absorption effect than intramobile connector.

• Journal of Electrical Engineering and Technology
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• 제2권1호
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• pp.136-141
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• 2007

The Purpose Of This Paper Is To Use A Tactile Sensor To Compensate The Error Rate. Most Automated Sphygmomanometers Use The Oscillometric Method And Characteristic Ratio To Estimate Systolic And Diastolic Blood Pressure. However, Based On The Fact That Maximum Amplitude Of The Oscillometric Waveform And Characteristic Ratio Are Affected By Compliance Of The Aorta And Large Arteries, A Method To Measure The Artery Stiffness By Using A Tactile Sensor Was Chosen In Order To Integrate It With The Sphygmomanometer In The Future Instead Of Using Photoplethysmography. Since Tactile Sensors Have Very Weak Movements, Efforts Were Made To Maintain The Subject's Arm In A Fixed Position, And A 40hz Low Pass Filter Was Used To Eliminate Noise From The Power Source As Well As High Frequency Noise. An Analyzing Program Was Made To Get Time Delay Between The First And Second Peak Of The Averaged Digital Volume Pulse(${\Delta}t_{dvp}$), And The Subject's Height Was Divided By ${\Delta}t_{dvp}$ To Calculate The Stiffness Index Of The Arteries($Si_{dvp}$). Regression Equations Of Systolic And Diastolic Pressure Using $Si_{dvp}$ And Mean Arterial Pressure(Map) Were Computed From The Test Group (60 Subjects) Among A Total Of 121 Subjects(Age: $44.9{\pm}16.5$, Male: Female=40:81) And Were Tested In 61 Subjects To Compensate The Error Rate. Error Rates Considering All Subjects Were Systolic $4.62{\pm}9.39mmhg$, And Diastolic $14.40{\pm}9.62mmhg$, And Those In The Test Set Were $3.48{\pm}9.32mmhg,\;And\;14.34{\pm}9.67mmhg$ Each. Consequently, Error Rates Were Compensated Especially In Diastolic Pressure Using $Si_{dvp}$, Various Slopes From Digital Volume Pulse And Map To Systolic-$1.91{\pm}7.57mmhg$ And Diastolic $0.05{\pm}7.49mmhg$.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.192-205
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• 2020

Seismic design practices and seismic response analyses of civil structures and nuclear power plants (NPPs) have conventionally used the peak ground acceleration (PGA) or spectral acceleration (S_a) as an intensity measure (IM) of an earthquake. However, there are many other earthquake IMs that were proposed by various researchers. The aim of this study is to investigate the correlation between seismic responses of NPP components and 23 earthquake IMs and identify the best IMs for correlating with damage of NPP structures. Particularly, low- and high-frequency ground motion records are separately accounted in correlation analyses. An advanced power reactor NPP in Korea, APR1400, is selected for numerical analyses where containment and auxiliary buildings are modeled using SAP2000. Floor displacements and accelerations are monitored for the non- and base-isolated NPP structures while shear deformations of the base isolator are additionally monitored for the base-isolated NPP. A series of Pearson's correlation coefficients are calculated to recognize the correlation between each of the 23 earthquake IMs and responses of NPP structures. The numerical results demonstrate that there is a significant difference in the correlation between earthquake IMs and seismic responses of non-isolated NPP structures considering low- and high-frequency ground motion groups. Meanwhile, a trivial discrepancy of the correlation is observed in the case of the base-isolated NPP subjected to the two groups of ground motions. Moreover, a selection of PGA or S_a for seismic response analyses of NPP structures in the high-frequency seismic regions may not be the best option. Additionally, a set of fragility curves are thereafter developed for the base-isolated NPP based on the shear deformation of lead rubber bearing (LRB) with respect to the strongly correlated IMs. The results reveal that the probability of damage to the structure is higher for low-frequency earthquakes compared with that of high-frequency ground motions.