• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.335-342
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• 1998

A soil-structure interaction (SSI) experiment is being conducted in a seismically active region in Hualien, Taiwan. To obtain earthquake data for quantifying SSI effects and providing a basis to benchmark analysis methods, a 1/4-th scale cylindrical concrete containment model similar in shape to that of a nuclear power plant containment was constructed in the field where both the containment model and its surrounding soil, surface and sub-surface, are extensively instrumented to record earthquake data. In between September 1993 and May 1996, fifteen earthquakes with Richter magnitudes ranging from 4.2 to 6.2 were recorded. The recorded data were analyzed to provide information on the response characteristics of the Hualien soil-structure system, the SSI effects and the ground motion characteristics. The ground response data were analyzed for their variations with depth, with distance from the model structure, and at the same depths along downhole arrays. Variations of soil stiffness and soil-structure system frequencies were also evaluated against maximum ground motion. In addition, the site soil properties were derived based on correlation analysis of the recorded data and then correlated with those from the geotechnical investigation data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.725-733
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• 2019

Sand dams are structures that can be used as auxiliary water resources in case of drought as sand accumulates due to barriers crossing valley rivers and valley water is stored in the voids, increasing the water level. This structure, which is mainly used in arid regions such as Africa, has not been installed in Korea. In Korea, there are only a few cases where water is taken from debris barriers that prevent debris flow. The purpose of this study is to evaluate the effect of water supply when the sand dam is installed downstream of the existing intake barrier in Seosang-ri valley, Chuncheon. For this purpose, modeling was performed by linking the basin hydrologic model and reservoir routing model. Changes in the water level, storage and discharge in the sand dam reservoir according to the size and intake of the sand dam are presented on a case-by-case basis. As a result of application, it was found that the water supply capacity due to the sand dam installation was improved at 95% reliability. Especially, when the size is L × B × H_o = 25 m × 15 m × 1 m and the pumping rates from intake barrier and sand dam are (Q₁, Q₂) = (30, 20), (35, 15) ㎥/day, the efficiency was the best for water supply of 50 ㎥/day.

• Journal of the Korean Magnetic Resonance Society
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• v.21 no.4
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• pp.139-144
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• 2017

Ni(II) containing coenzyme F430 catalyzes the reduction of $CO_2$ in methanogen. Macrocyclic Ni(II) complexes with N,O shiff bases have been received a great attention since metal ions play an important role in the catalysis of reduction. The reducing power of metal complexes are supposed to be dependent on oxidoreduction state of metal ion and structural properties of macrocyclic ring moiety that can enhance electrochemical properties in catalytic process. Six different ${\alpha}$-oximinoketone compounds, precursor of macrocyclic ligands used in $CO_2$ reduction coenzyme F430 model complexes, were synthesized with yields over 90% and characterized by NMR. The molecular geometries of ${\alpha}$-oximinoketone analogues were fully optimized at Beck's-three-parameter hybrid (B3LYP) method in density functional theory (DFT) method with $6-31+G^*$ basis set using the ab initio program. In order to understand molecular planarity and substitutional effects that may enhance reducing power of metal ion are studied by computing the structure-dependent $^{13}C$-NMR chemical shift and comparing with experimental results.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.1
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• pp.64-74
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• 1997

A CELTHYM(CEll-based Long-term HYdrologic Model), a pre-processor and a post-processor that can be integrated with geographic information system(GIS) were developed to predict the stream flow from the small agricultural watershed on the daily basis. The CELTHYM calculates the direct runoff from a grid using SCS curve number method and then sum up all of cells with respect to a sub-catchment area belonged to a stream grid and integrated to an outlet. Base flow of a watershed outlet was computed by integrating of the base flow of each stream grid that was averaged the sub-catchment deep-percolation and calculated with the release rate. Two kind of water budget equation were used to compute the water balance in a grid that was classified into not paddy field and paddy field. One of the two equation is a soil water balance equation to account the soil moisture of the upland, forest and excluding paddy field grid. The other is a paddy water balance equation for the paddy field, calculating the ponding depth, the effective rainfall, the deep percolation and the evapotranspiration.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.730-731
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• 2015

This study aims at giving the framework to estimate the environmental load at planning and schematic phase. With increasing awareness of environmental issues, the effort to reduce the environmental impacts caused by human activity has been increasingly enlarged. So far most of researches estimating CO₂ emissions have analyzed energy consumption based on BOQ (Bills of Quantity) acquired after detailed design. There is also lack of reliability in the estimated environmental impact using the basic unit of a facility at the planning stage, because it uses a limited specific section of historical data. Thus, this study is targeted at developing framework to assess reliable environmental loads based on information available at project early phases by making case-bases from historical design information on PSC Beam Bridge. Historical database is built on the basis of the LCA (Life Cycle Assessment) and in order to set input information for estimating model, the literature about information in an early project phase are reviewed. Using the information available in the planning and schematic design stage, the Framework is presented to estimate the environmental load in an early stage in the project. Developing an environmental load estimation model in accordance with the Framework presented in this study, it is expected that the environmental load in the initial project phase can be estimated more quickly and accurately.

• Applied Chemistry for Engineering
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• v.2 no.4
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• pp.385-392
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• 1991

Nonstoichiometry and defect model for $Ni_{1-x}O$ were determined by coulometric titration method. In the temperature range of 1123-1198K and oxygen partial pressure of 0.21-0.1 atm, the nonstoichiometry was found to be proportional to the fourth root of the oxygen partial pressure. This pressure dependence can be explained by the fact that nonstoichiometric $Ni_{1-x}O$ contains singly ionized metal vacancies as the predominant point defects. At T=1173K and $Po_2=0.21atm$, the nonstoichiometry, x was $1.21{\times}10^{-4}$. The standard formation enthalpy of defects in $Ni_{1-x}O$ was found, on the basis of this defect model, to be 0.95 eV. Also the result indicates that both of singly and doubly ionized metal vacancies are simultaneously present at above 1248K.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.5
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• pp.627-642
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• 2012

The purpose of this study was to develop and validate a teacher's praise dispositions scale(TPDS). On the basis of a literature review of praise, we developed 19 Likert-type items to measure praise dispositions of elementary and secondary school teachers. The developed scale was examined with 342 teachers. With an exploratory factor analysis we extracted 3 sub-factors of the scale consisted of 16 items; frequency, intention, and standard of praise. Cronbach's ${\alpha}$ coefficients of sub-scales were from .60 to .85 and split-half reliabilities were from .60 to .84. A confirmatory factor analysis was conducted to assess the suitability of three components model. It was found that some correlation coefficients, not all of them, between gratitude disposition and praise disposition were statistically significant. It suggested that teachers'praise disposition scale is related to gratitude disposition but is not the same scale. In conclusion, TPDS could be used to measure praise dispositions of teachers. However, for further validity and reliability, repeated research is necessary.

• Journal of Environmental Health Sciences
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• v.48 no.2
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• pp.59-65
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• 2022

Background: Since people move through microenvironments rather than staying in one place, they may be exposed to both indoor and outdoor PM_2.5 concentrations. Objectives: The aim of this study was to assess the exposure level of each sub-population group and evaluate the contribution rate of the major microenvironments. Methods: Exposure scenarios for sub-population groups were constructed on the basis of a 2019 Time-Use survey and the previous literature. A total of five population groups were classified and researchers wearing MicroPEM simulated monitoring PM_2.5 exposure concentrations in real-time over three days. The exposure contribution for each microenvironment were evaluated by multiplying the inhalation rate and the PM_2.5 exposure concentration levels. Results: Mean PM_2.5 concentrations were 33.0 ㎍/m³ and 22.5 ㎍/m³ in Guro-gu and Wonju, respectively. When the exposure was calculated considering each inhalation rate and concentration, the home showed the highest exposure contribution rate for PM_2.5. As for preschool children, it was 90.8% in Guro-gu, 94.1% in Wonju. For students it was 65.3% and 67.3%. For housewives it was 98.2% and 95.8%, and 59.5% and 91.7% for office workers. Both regions had higher exposure to PM_2.5 among the elderly compared to other populations, and their PM_2.5 exposure contribution rates were 98.3% and 94.1% at home for Guro-gu and Wonju, respectively. Conclusions: The exposure contribution rate could be dependent on time spent in microenvironments. Notably, the contribution rate of exposure to PM_2.5 at home was the highest because most people spend the longest time at home. Therefore, microenvironments such as home with a higher contribution rate of exposure to PM_2.5 could be managed to upgrade public health.

• Smart Structures and Systems
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• v.31 no.2
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• pp.101-111
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• 2023

Structural health monitoring (SHM) covers a range of damage detection strategies for buildings. In real-time, SHM provides a basis for rapid decision making to optimise the speed and economic efficiency of post-event response. Previous work introduced an SHM method based on identifying structural nonlinear hysteretic parameters and their evolution from structural force-deformation hysteresis loops in real-time. This research extends and generalises this method to investigate the impact of a wide range of flag-shaped or pinching shape nonlinear hysteretic response and its impact on the SHM accuracy. A particular focus is plastic stiffness (K_p), where accurate identification of this parameter enables accurate identification of net and total plastic deformation and plastic energy dissipated, all of which are directly related to damage and infrequently assessed in SHM. A sensitivity study using a realistic seismic case study with known ground truth values investigates the impact of hysteresis loop shape, as well as added noise, on SHM accuracy using a suite of 20 ground motions from the PEER database. Monte Carlo analysis over 22,000 simulations with different hysteresis loops and added noise resulted in absolute percentage identification error (median, (IQR)) in K_p of 1.88% (0.79, 4.94)%. Errors were larger where five events (Earthquakes #1, 6, 9, 14) have very large errors over 100% for resulted K_p as an almost entirely linear response yielded only negligible plastic response, increasing identification error. The sensitivity analysis shows accuracy is reduces to within 3% when plastic drift is induced. This method shows clear potential to provide accurate, real-time metrics of non-linear stiffness and deformation to assist rapid damage assessment and decision making, utilising algorithms significantly simpler than previous non-linear structural model-based parameter identification SHM methods.

• Proceedings of the Korean Reliability Society Conference
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• 2000.04a
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• pp.223-230
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• 2000

This work aims to develop modeling methodology of machine part reliability. The reliability model is to be used for predicting and improving reliability in planning and design processes of products. In order to develop the reliability model of machine parts, the functions and interactions of sub-units of machine parts are analyzed first and function network is constructed. Using the function network, function block diagram is developed, which can be the basis for deriving reliability block diagram. Modeling of machine part reliability has not been widely studied since the reliability modeling of machine parts requires understanding of the functions and failures of their components in several viewpoints. This work tries to find general methodology of reliability modeling and proposes a framework for reliability improvement during machine part development.