• Nuclear Engineering and Technology
• /
• v.54 no.10
• /
• pp.3745-3765
• /
• 2022

The concrete structures related to nuclear safety are threatened by accidental impact loadings, mainly including the low-velocity drop-weight impact (e.g., spent fuel cask and assembly, etc. with the velocity less than 20 m/s) and high-speed projectile impact (e.g., steel pipe, valve, turbine bucket, etc. with the velocity higher than 20 m/s), while the existing studies are still limited in the impact resistant design of nuclear power plant (NPP), especially the primary RC slab. This paper aims to propose the numerical simulation and theoretical approaches to assist the impact-resistant design of RC slab in NPP. Firstly, the continuous surface cap (CSC) model parameters for concrete with the compressive strength of 20-70 MPa are fully calibrated and verified, and the refined numerical simulation approach is proposed. Secondly, the two-degree freedom (TDOF) model with considering the mutual effect of flexural and shear resistance of RC slab are developed. Furthermore, based on the low-velocity drop hammer tests and high-speed soft/hard projectile impact tests on RC slabs, the adopted numerical simulation and TDOF model approaches are fully validated by the flexural and punching shear damage, deflection, and impact force time-histories of RC slabs. Finally, as for the two low-velocity impact scenarios, the design procedure of RC slab based on TDOF model is validated and recommended. Meanwhile, as for the four actual high-speed impact scenarios, the impact-resistant design specification in Chinese code NB/T 20012-2019 is evaluated, the over conservation of which is found, and the proposed numerical approach is recommended. The present work could beneficially guide the impact-resistant design and safety assessment of NPPs against the accidental impact loadings.

• Journal of Fashion Business
• /
• v.6 no.6
• /
• pp.78-88
• /
• 2002

The purpose of this study is to provide for some basic data useful to production of the apparels fit and measured well for the Chinese men. For this purpose, 389 men aged between 20 and 49 and living in Beijing and Shanghai, China were sampled to be measured for their constitutions. Then, their constitutions were classified and thereupon, according to the Men's Wear Specifications (GB/T 1335.1-1997), National Standards of People's Republic of China. The collected data were statistically processed using SAS 6.12 for technical statistical analysis, correlation analysis, factor analysis, group-wise analysis. The results of this study can be summarized as follows; 1. As a result of the factor analysis aiming to determine Chinese men's constitutional components, five components could be identified: constitutional obesity, lateral body size, longitudinal body size, shoulder and back width, and shoulder drooping. 2. As a result of classifying Chinese men's constitutions according to drop measurements, four types could be identified. Y type had the lowest obesity and the highest longitudinal body size. A type had a lower obesity and had an average longitudinal body size. B Type had the second highest obesity, the smallest longitudinal body size and shoulders/back width. C Type had the highest obesity, upper body length and shoulders/back width. 3. In terms of distribution, 'B' type (39.10%) of the sample, followed by 'A' type (29.26%), 'C' type (19.95%) and 'Y' type (11.70%). In all, the results of this study suggests that 'B' type represents the Chinese men in contrast with GB specifying that 'A' type represents the Chinese men. On the other hand, Beijing region was dominated most by 'B' type (37.06%), followed by 'A' type (28.82%), 'C' type (22.35%) and 'Y' type (11.76%), while Shanghai region was dominated most by 'B' type (41.13%), followed by 'A' type (31.21%), 'C' type (19.15%) and 'Y' type (8.51%).

• Journal of Korean Society of Forest Science
• /
• v.108 no.3
• /
• pp.322-328
• /
• 2019

The purpose of this study was to provide basic data for maintenance and repair of the forest road surfaces using the light drop weight test (LDWT), density test, and grain size analysis at four sites in Yeongyang-gun Mt. (2011y, 2014y, 2016y, and 2017y). In terms of the density test results, the opening density in 2011 was the highest at $2.0694g/cm^3$, and the opening density in 2017 was the lowest at $1.7443g/cm^3$. The grain size analysis showed that the proportion of large aggregates was highest at the opening in 2017, and the proportion of large aggregates decreased with the delay of opening date. From the LDWT results, $E_{vd}$ (the dynamic deformation coefficient) of the 2011y forest road was $35.7MN/m^2$, 2014y was $30.5MN/m^2$, 2016y was $28.6MN/m^2$, and 2017y was $23.5MN/m^2$. The $E_{vd}$ value for the oldest forests opened with the 2011y forest road was the highest, the average $E_{vd}$ value of the center portion was $21.45MN/m^2$, the average $E_{vd}$ value of the wheel portion of the banking part was $31.31MN/m^2$, and the average $E_{vd}$ value of the wheel portion of the cut part was $36.71MN/m^2$.

• Nuclear Engineering and Technology
• /
• v.44 no.7
• /
• pp.735-744
• /
• 2012

In order to quantify the flow distribution characteristics of APR+ reactor, a test was performed on a test facility, ACOP ($\underline{A}$PR+ $\underline{C}$ore Flow & $\underline{P}$ressure Test Facility), having a length scale of 1/5 referring to the prototype plant. The major parameters are core inlet flow and outlet pressure distribution and sectional pressure drops along the major flow path inside reactor vessel. To preserve the flow characteristics of prototype plant, the test facility was designed based on a preservation of major flow path geometry. An Euler number is considered as primary dimensionless parameter, which is conserved with a 1/40.9 of Reynolds number scaling ratio. ACOP simplifies each fuel assembly into a hydraulic simulator having the same axial flow resistance and lateral cross flow characteristics. In order to supply boundary condition to estimate thermal margins of the reactor, the distribution of inlet core flow and core exit pressure were measured in each of 257 fuel assembly simulators. In total, 584 points of static pressure and differential pressures were measured with a limited number of differential pressure transmitters by developing a sequential operation system of valves. In the current study, reactor flow characteristics under the balanced four-cold leg flow conditions at each of the cold legs were quantified, which is a part of the test matrix composing the APR+ flow distribution test program. The final identification of the reactor flow distribution was obtained by ensemble averaging 15 independent test data. The details of the design of the test facility, experiment, and data analysis are included in the current paper.

• Journal of the Korean Society for Precision Engineering
• /
• v.10 no.3
• /
• pp.152-160
• /
• 1993

This paper presents experimental study of the static and dynamic fracture toughness behavior of a A1-6061 aluminum alloy reinforced alumina( .delta. -A1$_{2}$0$_{3}$) whiskers with 5%, 10%, 15% volume fraction. The static fracture tests using three-point bending specimen were performed by UTM25T. And drop weight impact tester performing dynamic fracture tests was used to measure dynamic locads applied to a fatigue-precracked specimes. The oneset of crack initiation was detected uwing a strain gage bonded near a crack tip. The value of static fracture toughness $K_{IC}$ and dynamic fracture toughness $K_{ID}$ were decided on the basis of linear elastic fracture mechanics. The effects of fiber volume fraction and loading on fracture toughness were investigated. The distribution of whiskers, bonding state and fracture interfaces involved in void, fiber pull-out state were investigated by optical microscopy(OM) and scanning electron microscopy(SEM)

• Proceedings of the KIPE Conference
• /
• 2007.11a
• /
• pp.218-220
• /
• 2007

A new 3-phase voltage disturbance generator is proposed. The voltage drop of the conventional generator in normal mode can be reduced significantly. The output voltage of the proposed generator is constant in normal mode and the efficiency of the series transformer is improved. The proposed generator has good feature of simple structure, cost effective implementation, high reliability, high efficiency, and easy control. The usefulness of the scheme is verified through simulation and experiments.

• Journal of Haehwa Medicine
• /
• v.13 no.1
• /
• pp.303-309
• /
• 2004

After treating a patient suffering from metacarpophalangeal joint extension disturbance which is caused by posterior interosseous nerve palsy, some results are gained as follows. The symptom of posterior interosseous nerve palsy is simillar to the it of radial nerve palsy. But posterior interosseous nerve palsy isn't accompany with wrist drop. posterior interosseous nerve palsy is accompany with metacarpophalangeal joint extension disturbance. This symptom is caused by posterior interosseous nerve palsy. Posterior interosseous nerve palsy is correspond to MAMOKBULIN(麻木不仁), SUTONG(手痛), SUGI(手氣) in oriental medicine. The cause of this case on oriental medicine is Deficiency of qi and blood. Treatment which based on cause of oriental medicine-herb medication, acupuncture treatment- have a good effect to patient.

• Proceedings of the KSME Conference
• /
• 2000.11a
• /
• pp.153-158
• /
• 2000

Nuclear reactor pressure vessel should be safety even in the case that hypothetical defects with allowable size are in vessel. Therefore, the materials should have excellent fracture resistance characteristics. The purpose of this study is to analyze the results of preirradiation baseline test of nuclear pressure vessel for Yonggwang Unit 5/6. In experiments, drop weight tests and impact tests are carried out to obtain nil-ductility transition reference temperature, $RT_{NDT}$ and static and dynamic fracture toughness tests are performed to compare with $K_{IR}$ curve in accordance with ASME Sec.III. The test results show that the materials had sufficiently fracture resistance characteristics for 40 years of design life.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.3
• /
• pp.431-436
• /
• 2013

A neutral section is installed around feeding substation(SS) and sectioning post(SP) that M phase and T phase are isolated in AC feeding system. Electric Train under "Notch-OFF" is operated by inertia within the neutral section. It causes disturbing the operation of electric trains for speed drop and driver's mistakes. A automatic changeover system with thyristor recently have taken under development. In the paper, it is introduced the configuration of train detection system and performance testing on automatic changeover system..

• Proceedings of the KSR Conference
• /
• 2000.05a
• /
• pp.660-668
• /
• 2000

The stress of connection points between railway vehicle equipment and carbody is considered as one of the important railway safety factor under the vehicle service condition. If any material or equipment drop in to the rail during the service condition, the vehicle call be lose its control as well as run off the rail. The be]t safety evaluation method by using hand calculation is broadly used by manufacturer is introduced in this paper. Two different kinds of the bolt, such as regular bolt and the bolt aluminum extruded carbody use, are tested based on U.I.C according to equipment fixed. The effect of holder and base to bolt under tile loading condition is analyzed on this paper.