• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.237-241
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• 2001

The uncertainties associated with fluence calculation at the pressure vessel have been evaluated for the Korean Next Generation Reactor, APR1400. To obtain uncertainties, sensitivity analyses were performed for each of the parameters important to calculated fast neutron fluence. Among the important parameters to the overall uncertainties, reactor modeling and core neutron source were examined. Mechanical tolerances, composition and density variations in the reactor materials as well as application of $r-{\theta}$ geometry in rectilinear region contribute to uncertainty in the reactor modeling. Depletion and buildup of fissile nuclides, instrument error related to core power level, uncertainty of fuel pin burnup, and variation of long-term axial peaking factors are main contributors to the core neutron source uncertainty. The sensitivity analyses have shown that the uncertainty in the fluence calculation at the reactor pressure vessel is +12%.

• The Journal of Society for e-Business Studies
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• v.14 no.4
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• pp.35-45
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• 2009

Domestic ASP (Application Service Provider) market has been dramatically enlarged under government supports for last 10 years. However ASP industry recently has been troubled for poor performance and market saturation. In this paper, firstly I derive core service groups through using BCG matrix for ASP market size and growth rate and secondly generate major critical success factors using focused group interview for selected core service groups. Finally I would like to propose a direction of ASP industry revitalization based on above critical success factors and transition strategy to SaaS (Software as a Service).

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.493-496
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• 2009

We report the EL property of blue and blue-violet emitting materials with anthracene moiety as well as a new core structure containing indenopyrazine. Non-doped device using one of indenopyrazine core derivatives was found to exhibit excellent blue-violet color purity of (0.173, 0.063), and narrow emission band of 42nm FWHM. One of anthracene core derivatives with bulky side group also exhibits excellent color coordinates (0.156, 0.088) and an external quantum efficiency of 7.18%.

• Earthquakes and Structures
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• v.7 no.5
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• pp.861-875
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• 2014

This paper studies the response of seismic behavior of reinforced concrete exterior beam-column joints under reversal loading with different anchorages and joint core details. The joint core was detailed without much confinement (group-I) and/or with proposed X-cross bars in the core (group-II). The beam longitudinal reinforcement's anchorages were designed as per ACI 352 (headed bars), ACI 318 (conventional $90^{\circ}$ bent hooks) and IS 456 ($90^{\circ}$ bent hooks with extended tails). The nonlinear finite element analysis response of the beam-column joints was studied, along with initial and progressive cracks up to failure. The experimental and analytical results were compared and presented in this paper to make more scientific conclusions.

• Nuclear Engineering and Technology
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• v.15 no.2
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• pp.87-97
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• 1983

The WBURN (2-D, 2-group, coarse mesh) code is developed to analyze the equilibrium core characteristics of CANDU-PHWR. The equilibrium characteristics of Wolsung reactor computed by using WBURN are compared with the values given in the Wolsung FSR. The changes of equilibrium core characteristics caused by the variation of design parameters for operating conditions are also investigated. The numerical results indicate that the average discharge irradiation in the Wolsung reactor can be increased up to about 5%.

• Journal of Korean Physical Therapy Science
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• v.29 no.2
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• pp.14-19
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• 2022

Background: Plank exercise (PE) is an effective exercise to enhance lower back stability by strengthening the core and lower limb muscles. However, in patients with a shortened hamstring muscle (HAM), PE may cause abnormal movement of the pelvis and lower back due to HAM hyperactivity. Therefore, the objective of this study was to investigate the effects of PE on the core muscles and HAM in subjects with a shortened HAM. Design: Cross-sectional study. Methods: Subjects were divided into a normal length of HAM group (NHG; 9 subjects) and a shortened length of HAM group (SHG; 14 subjects). The activities of the erector spinae (ES), rectus abdominis (RA), external oblique (EO), and HAM muscles were measured using surface electromyography. Results: The results showed that RA, EO, and ES muscle activities were higher in the NHG than in the SHG; however, no significant differences were detected. Conclusion: HAM activity was significantly higher in the SHG than in the NHG. In subjects with a shortened HAM, PE may hyperactivate the HAM, adversely affecting the pelvis and lower back.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.30-43
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• 2021

In the 2D/1D method, a global adjoint CMFD based on the generalized equivalence theory is built to synthesize the 2D radial MOC adjoint and 1D axial NEM adjoint calculation and also to accelerate the iteration convergence of 3D whole-core adjoint transport calculation. Even more important, an advanced yet accurate two-level (TL) CMFD acceleration technique is proposed, in which an equivalent one-group adjoint CMFD is established to accelerate the multi-group adjoint CMFD and then to accelerate the 3D whole-core adjoint transport calculation efficiently. Based on these method, a new code is developed to perform 3D adjoint neutron flux calculation. Then a set of VERA and C5G7 benchmark problems are chosen to verify the capability of the 3D adjoint calculations and the effectiveness of TL CMFD acceleration. The numerical results demonstrate that acceptable accuracy of 2D/1D adjoint calculations and superior acceleration of TL CMFD are achievable.

• Journal of Korea Foundry Society
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• v.33 no.4
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• pp.147-156
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• 2013

The effects of core materials on the microstructure and mechanical properties of Al casting products have been investigated. The Al casting samples and cylinder head were fabricated by using organic and inorganic binder core respectively, and their microstructure and mechanical properties were evaluated. The Al casting samples fabricated by using inorganic core showed the better mechanical properties such as tensile strength and elongation than those of the Al casting samples fabricated by using organic core. That's because the Al casting samples contained small amount of pore defects and had fine microstructure compared with the Al casting samples fabricated by using organic core. Also, the use of inorganic core effectively reduced harmful gas emission and pollution.

• Design & Manufacturing
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• v.14 no.1
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• pp.1-7
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• 2020

In this study, the variation of the shrinkage in the thickness direction of the molded parts according to the gate size of the polymer core fabricated through the 3D printer using the SLS method was studied. The polymer cores are laser sintered and the powder material is nylon base PA2200. The polymer cores have lower heat transfer rate and rigidity than the metal core due to the characteristics of the material. Therefore, the injection molding test conditions are set to minimize the deformation of the core during the injection process. The resin used in the injection molding test is a PP material. The packing condition was set to 80, 90 and 100% of the maximum injection pressure for each gate size. The runner diameter used was ∅3mm, and the gates were fabricated in semicircle shapes with cross sections 1, 2, and 3 ㎟, respectively. Thickness measurement was performed for 10 points at 2.5 mm intervals from the point 2.5 mm away from the gate, and the shrinkage to thickness was measured for each point. The shrinkage rate according to the gate size tends to decrease as the cross-sectional area decreases as the maximum injection pressure increases. The average thickness shrinkage rate was close to 0% when the packing pressure was 90% for the gate area of 1mm2. When the holding pressure was set to 100%, the shrinkage was found to decrease by 3% from the standard dimension due to the over-packing phenomenon. Therefore, the smaller the gate, the more closely the molded dimensions can be molded due to the high pressure generation. It was confirmed that precise packing process control is necessary because over-packing phenomenon may occur.

• Journal of dental hygiene science
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• v.13 no.4
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• pp.487-492
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• 2013

This study aimed to illuminate the correlatives between the surface processing of Zirconia core and the shear bond strength. The specimens were made by precipitating for two minutes in color liquid and drying to produce a colored Zirconia core following the manufacturer's instructions. The specimens were divided into 4 subgroups according to the surface treatment-sandblasted+liner treatment, SLT group; sandblasted treatment, ST group; liner treatment, LT group; non treatment (control), NT group. The specimens were put on the device with regard to ISO/TS 11405, then tested the shear bond strength with 1 mm shearing speed per minute using the Instron multi-purpose tester. The collected data was analysed by one way ANOVA and t-test. After applying the liner and sandblast to the Zirconia core, shear bond strength value were SLT (23.19 MPa), ST (21.17 MPa), LT (20.53 MPa) and NT (16.46 MPa) in the order. There was a significant difference in the surface roughness between NT and ST group (p<0.001), and in the compressive shear bond strength between NT and SLT group (p<0.05). Therefore, sandblasted plus liner treatment on pre-sintered substructure increased the bond strength of veneering ceramic, compared with other surface treatments.