• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.53-61
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• 2019

The seismic capacity of electric cabinets in Nuclear Power Plants (NPPs) should be qualified before installation and be maintained during operation. However it can happen that identical devices cannnot be produced for replacement of devices mounted in electric cabinets. In case of when no In-Cabinet Response Spectrum (ICRS) is available for new devices, ICRS can be generated by using Finite Element Analysis (FEA). In this study we investigate structural response and ICRSs of battery charger which is supplied to NPPs. Test results on the battery charger are utilized in this study. The response is measured by accelerometers installed on the housing of the battery charger and local panels in the battery charger. Numerical analysis model is established based on resonant frequency search test results and validated by comparison with 2 types of earthquake testing results. ICRSs produced from the numerical model are compared with measured ICRSs in the seismic tests. Developed analysis model is a simple reduced model and anticipates ICRSs quite well as measured response in the tests overall despite of its structural limitation.

• Geomechanics and Engineering
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• v.29 no.5
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• pp.487-496
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• 2022

Most of the pile's vertical static load tests in construction sites are the proof load tests, which is difficult to accurately estimate the ultimate bearing capacity and analyze the reliability of piles. Therefore, a reliability analysis method based on the proof load-settlement (Q-s) data is proposed in this study. In this proposed method, a simple ultimate limit state function based on the hyperbolic model is established, where the random variables of reliability analysis include the model factor of the ultimate bearing capacity and the fitting parameters of the hyperbolic model. The model factor M = R_uR / R_uP is calculated based on the available destructive Q-s data, where the real value of the ultimate bearing capacity (R_uR) is obtained by the complete destructive Q-s data; the predicted value of the ultimate bearing capacity (R_uP) is obtained by the proof Q-s data, a part of the available destructive Q-s data, that before the predetermined load determined by the pile test report. The results demonstrate that the proposed method can easy and effectively perform the reliability analysis based on the proof Q-s data.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1252-1252
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• 2022

Temporary work that utilizes temporary equipment (e.g., system scaffold and system pipe support) in construction work is one of the most vulnerable work from a safety perspective in South Korea. Typically, temporary equipment is reused at construction sites. The Korea Occupational Safety and Health Agency announced guidelines regarding the performance standards for reusable temporary equipment to prevent the accidental collapse of temporary facilities. Nevertheless, temporary facilities' collapse still occurs, which could be attributed to a degradation in the performance due to the reuse of temporary equipment. Therefore, this study investigated the performance of simple temporary structures assembled with new and reused equipment. To this end, an experimental module was designed based on previous research cases, and two experimental models were constructed, in which one was assembled using new equipment (Model A), and the other was built using reused equipment (Model B). To determine the performance of each model, a load test was conducted to measure the maximum load that each model could withstand. The experimental results revealed that the maximum load of Model B was 15% lower than that of Model A. This indicates that there is a meaningful performance difference between those two models. Based on this result, the authors decided to perform additional tests with more realistic models than previous ones. The new experimental module was designed to ensure compliance with the Korean design guidelines. In this presentation, the authors show details of the first tests and their results and plan for the additional test.

• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.34-37
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• 2023

The practical application of REBCO coated conductor (CC) tapes, vital for energy transmission (e.g., cable application) and high-field magnets (e.g., coil application), necessitates efficient and simple quality assessment procedures. This study introduces a systematic approach to assess the electromechanical properties of REBCO CC tapes under 77 K and self-field conditions. The approach involves customized tensile and bending tests that clarify the critical current (I_c) response of the CC tapes under mechanical loads induced by tension and bending. This study measures the retained Ic values of commercially available GdBCO CC tapes under 250 MPa tensile stress and 40 mm bending diameter. Through experimentation, the study demonstrates the resilience of these tapes and their suitability for applications. By presenting a simplified stress-based analysis and a bending test of the tapes, the study contributes to effective quality assessment methods for the development of practical superconducting products.

• Korean Journal of Ecology and Environment
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• v.49 no.3
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• pp.228-235
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• 2016

Aquatic ecosystems are receiving various harmful effects due to anthropogenic chemical pollutions. To protect wildlife, risk assessments of the chemicals are conducted using reference indexes of toxicity estimated by species-level laboratory tests and/or micro-/mesocosm community-level studies. However, the existing micro-/mesocosm communities are structurally too complicated, and it is also difficult to compare the experimental results directly with those from species-level tests. Here, we developed a procedure of a simple bi-trophic microcosm experiment which contains the common species (a green algae, Pseudokirchneriella subcapitata and a cladoceran, Daphnia magna) for testing chemical toxicities. For the proper operation of bitrophic microcosm experiment, the minimum required concentration of primary producer (P. subcapitata) is $5{\times}10^5cells\;mL^{-1}$. The microcosm system showed higher stability when the initially introduced D. magna population was composed of neonates (<24-h old) than adults and those mixture. This simple microcosm system would be an applicable tool to estimate the disturbing impacts of pollutants on plant-herbivore interactions, and linking the species- and population-/community level risk assessments in the future studies.

• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.1-11
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• 2004

Foam reduces the mobility of gas phase in porous media to overcome gravity override and to divert acid into desired layers in the petroleum industry and to enhance the efficiency of environmental remediation. Recent experimental studies on foam show that foam exhibits a remarkably different flow rheology depending on the flow regime. This study, for the first time, focuses on the issues of foam diversion process under the conditions relevant to groundwater remediation, combining results from laboratory linear-flow experiments and a simple numerical model with permeability contrasts. Linear flow tests performed at two different permeabilities (k = 9.1 and 30.4 darcy) confirmed that two flow regimes of steady-state strong foams were also observed within the permeability range of shallow geological formations. Foam exhibited a shear-thinning behavior in a low-quality regime and near Newtonian rheology in a high-quality regime. Data taken from linear flow tests were incorporated into a simple numerical model to evaluate the efficiency of foam diversion process in the presence of permeability contrasts. The simple model illustrated that foam in the high-quality regime exhibited a successful diversion but foam in the low-quality regime resulted in anti-diversion, implying that only foam in the high-quality regime would be applicable to the diversion process. Sensitivity study proved that the success of diversion process using foam in the high-quality regime was primarily controlled by the limiting capillary pressures (${P_c}{^*}$) of the two layers of interest. Limitations and implications are also discussed and included.

• Journal of the Korean Geotechnical Society
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• v.32 no.6
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• pp.49-59
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• 2016

We develop liquefaction resistance curves, which represent the correlation between cyclic resistance ratio (CRR) and number of cycles (N) to estimate the build-up of residual excess pore pressure from simple shear tests performed for this study and also from published literature. The liquefaction curve is calculated from two models. The comparisons show that one of the models is not reliable because it underestimates CRR. The scatter of the data is shown to be significantly reduced when CRR is normalized to the resistance ratio at N = 15 ($CRR_{N=15}$). Use of the normalization is particularly useful because CRR can be easily estimated from field tests. From normalization, we propose mean, upper, and lower curves. The corresponding design equation and its parameters are also proposed. We believe that the proposed curves can be used for effective stress site response analyses and evaluation of the seismic performance of port structures.

• Journal of Gifted/Talented Education
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• v.15 no.2
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• pp.101-125
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• 2005

We applied functional magnetic resonance imaging (fMRI) techniques to examine whether general intelligence (g) could be assessed using a neurobiological signal of the brain. Participants were students in a national science academy and several local high schools. They were administered diverse intelligence (RAPM and WAIS) and creativity tests (TTCT-figural and TTCT-verbal). Forty of them were scanned using fMRI while performing complex and simple g tasks. In brain regions of greater blood flow in complex compared with simple g tasks, the gifted group with an exceptional g level was not significantly different from the average group with an ordinary g level: both of them activated the lateral prefrontal, anterior cingulate, posterior parietal cortices. However, the activation levels of the gifted group were greater than those of the average group, particularly in the posterior parietal cortex. Correlation analysis showed that the activity of the posterior parietal cortex has the highest correlation ($(r=0.73{\sim}0.74)$) with individual g levels and other regions also have moderate correlation ($(r=0.53{\sim}0.66)$). On the other hand, two-sample t test showed a striking contrast in intelligence tests scores between the gifted and the average group, whereas it did not show in creativity tests scores. These results suggest that it is within the bounds of possibility that a neurobiological signal of the brain is used in the assessment of the gifted and also suggest that creativity has to be given a great deal of weight on the assessment of the gifted.

• The Journal of the Korea Contents Association
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• v.13 no.6
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• pp.339-349
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• 2013

This study was conducted to evaluate the correlation between the Korean version of Mini Mental State Examination (MMSE-K) and the Korean Computerized Neurobehavioral Test (KCNT) and the usefulness of KCNT for discriminating the patients with suspected dementia from normal persons in patients with a brain injury. The results of each items of KCNT had passed the test for normality. T test for group comparison and bivariate correlation analysis for correlation between two tests were used. There were no significant differences in characteristics of two groups. The differences in results of eight tests of KCNT between two groups were statistically significant (p<.05) and the Pearson correlation coefficients (r) between two tests were statistically significant (p<.05) : simple reaction time (-.580), choice reaction time (-.341), color word vigilance (-.661), digit classification (-.703), 2-digit addition (-.582), 3-digit addition (-.610), symbol digit substitution (-.642), and digit span (.807). These results suggested that simple reaction time and 2-digit addition were useful in discriminating the patients with suspected dementia from normal persons because the Pearson correlation coefficients of the two items of KCNT showed anticlastic association between two groups. And each items of KCNT may use in follow up cognitive function for patients in two groups.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.12 no.2
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• pp.194-198
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• 2009

Purpose: Severe abdominal distension is not uncommon symptom in the neonate. Two major causes of this symptom are benign transient intestinal ileus (BTII) and Hirschsprung`s disease (HD). But it is difficult to differentiate BTII from HD based on the symptoms and simple abdominal x-ray findings. The aim of this retrospective study was to assess the clinical aspects and diagnostic tests differencing two diseases. Methods: From August 2004 to March 2009, nineteen patients with severe abdominal distension, who underwent barium enema, anorectal manometry, and rectal suction biopsy (triple tests) due to a suspicion of HD, were enrolled. A comparison of clinical data associated with BTII and HD based on the clinical features and results of triple tests. Results: The age of onset of symptom was between 2 and 6 weeks in BTII and within 3 weeks in HD. On the barium enema, transitional zone revealed in 6 (50%) patients in BTII and 4 (57.1%) in HD. On anorectal manometry, the anorectal inhibitory reflex was present in 11 (91.7%) patients in BTII and 1 (14.3%) in HD. On rectal suction biopsy, ganglion cell was present in 9 (75%) patients in BTII and 0 (0%) in HD. Abdominal distension was improved within 3 months of life in all cases of BTII. Conclusion: We think that anorectal manometry may be more simple and useful diagnostic method than barium enema and rectal suction biopsy for differential diagnosis of transient intestinal ileus and Hirschsprung's disease.