• The KIPS Transactions:PartD
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• v.10D no.3
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• pp.407-416
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• 2003

As the usage of database systems dramatically increases and the amount of data pouring into them is massive, the performance administration techniques for using database systems effectively are getting more important. Especially in data warehouses, the performance management is much more significant mainly because of large volume of data and complex queries. The objectives and characteristics of data warehouses are different from those of other operational systems so adequate techniques for performance monitoring and tuning are needed. In this paper we extend functionalities of the DBMax, a performance administration tool for Oracle database systems, to apply it to data warehouse systems. First we analyze requirements based on summary management and ETL functions they are supported for data warehouse performance improvement in Oracle 9i. Then, we design architecture for extending DBMax functionalities and implement it. In specifics, we support SQL tuning by providing details of schema objects for summary management and ETL processes and statistics information. Also we provide new function that advises useful materialized views on workload extracted from DBMax log files and analyze usage of existing materialized views.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.535-541
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• 2013

The urbanization affects significantly on a natural water circulation system by increasing the imperviousness rate. It is also negatively affecting on urban temperature, environmental pollution, water quality, and aqua-ecosystems. The Korea MOE (Ministry of Environment) adapted a new environmental policy in order to reduce the impact of urbanization, which is the Green Stormwater Infrastructure (GSI) program. The GSI can be achieved by protecting conservable green spaces, enlarging more green spaces, and constructing more permeable pavements. The GSI is including many different techniques such as bioretention, rain garden, infiltration trench and so on. Also It is the infrastructures using natural mechanisms of soils, microorganisms, plants and animals on a water circulation system and pollutant reduction. In this research, a multi functional GSI technology with infiltration-filtration mechanisms has been developed and performed lab-scale tests to evaluate the performances about infiltration rate restoration and pollutant reduction. The most of pollutants including metals, organics and particulates were reduced about 50~90% due to water infiltration and storage functions. The clogging was found when the TSS loading rate was reached on $8.3{\sim}9.0kg/m^2$, which value is higher than the values in literatures. It means the new technology can show high performances with low maintenances.

• Journal of Korean Association for Spatial Structures
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• v.6 no.4 s.22
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• pp.81-92
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• 2006

This paper presents exact solutions for the free vibrations and buckling of rectangular plates having two opposite, simply supported edges subjected to linearly varying normal stresses causing pure in-plane moments, the other two edges being free. Assuming displacement functions which are sinusoidal in the direction of loading (x), the simply supported edge conditions are satisfied exactly. With this the differential equation of motion for the plate is reduced to an ordinary one having variable coefficients (in y). This equation is solved exactly by assuming power series in y and obtaining its proper coefficients (the method of Frobenius). Applying the free edge boundary conditions at y=0, b yields a fourth order characteristic determinant for the critical buckling moments and vibration frequencies. Convergence of the series is studied carefully. Numerical results are obtained for the critical buckling moments and some of their associated mode shapes. Comparisons are made with known results from less accurate one-dimensional beam theory. Free vibration frequency and mode shape results are also presented. Because the buckling and frequency parameters depend upon Poisson's ratio ( V ), results are shown for $0{\leq}v{\leq}0.5$, valid for isotropic materials.

• Journal of Biomedical Engineering Research
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• v.32 no.2
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• pp.165-176
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• 2011

The femoral nerve innervates the quadriceps muscles and its dermatome supplies anteromedial thigh and medial foot. Paralysis of the quadriceps muscles due to the injury of the femoral nerve results in disability of the knee joint extension and loss of sensory of the thigh. A child could walk independently even though he had injured his femoral nerve severely due to the penetrating wound in the medial thigh. We measured and analyzed his gait performance in order to find the mechanisms that enabled him to walk independently. The child was eleven-year-old boy and he could not extend his knee voluntarily at all during a month after the injury. His gait analysis was performed five times (GA1~GA5) for sixteen months. His temporal-spatial parameters were not significantly different after the GA2 or GA3 test, and significant asymmetry was not observed except the single support time in GA1 results. The Lower limb joint angles in affected side had large differences in GA1 compared with the normal normative patterns. There were little knee joint flexion and extension motion during the stance phase in GA1 The maximum ankle plantar/dorsi flexion angles and the maximum knee extension angles were different from the normal values in the sound side. Asymmetries of the joint angles were analyzed by using the peak values. Significant asymmetries were found in GA1with seven parameters (ankle: peak planter flexion angle in stance phase, range of motion; ROM, knee: peak flexion angles during both stance and swing phase, ROM, hip: peak extension angle, ROM) while only two parameters (maximum hip extension angle and ROM of hip joint) had significant differences in GA5. The mid-stance valleys were not observed in both right and left sides of vertical ground reaction force (GRF) in the GA1, GA2. The loading response peak was far larger than the terminal stance peak of vertical ground reaction curve in the affected side of the GA3, GA4, GA5. The measured joint moment curves of the GA1, GA2, GA3 had large deviations and all of kinetic results had differences with the normal patterns. EMG signals described an absence of the rectus femoris muscle activity in the GA1 and GA2 (affected side). The EMG signals were detected in the GA3 and GA4 but their patterns were not normal yet, then their normal patterns were detected in the GA5. Through these following gait analysis of a child who had selective injuries on the knee extensor muscles, we could verify the actual functions of the knee extensor muscles during gait, and we also could observe his recovery and asymmetry with quantitative data during his rehabilitation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.363-371
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• 2023

To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.2
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• pp.99-114
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• 2020

The characteristics of the Brazilian tensile strengths(σ_t) parallel to the rock cleavages in Jurassic granite from Geochang were analysed. The evaluation for the six directions of rock cleavages was performed using the parameter values on microcrack length and the above strength. The strength values of the five test specimens belonging to each direction were classified into five groups. The strength values of these five groups increase in order of group A < B < C < D < E. The close dependence between the above microcrack and strength was derived. The analysis results of this study are summarized as follows. First, the chart showing the variation and characteristics of strength among the three rock cleavages were made. In the above chart, the strength values of six directions belonging to each group were arranged in order of rift(R1 and R2), grain(G1 and G2) and hardway(H1 and H2). The strength distribution lines of the five groups concentrate in the direction of R1. And the widths among the above five lines indicating strength difference(Δσ_t) are the most narrowest in R1 direction. From the related chart, the variation characteristics among the two directions forming each rock cleavage were derived. G2(2)-test specimen shows higher value and lower value of the difference in strength compared to the case of G1(1)-test specimen. These kinds of phenomena are the same as the case between the test specimen H2(2) and H1(1). The strength characteristics of the above test specimens (2) suggest lower microcrack density value and higher degree of uniformity in the distribution of microcracks arrayed parallel to the loading direction compared to those of test specimens (1). The six strength values belonging to each group were arranged in increasing order in the above chart. The strength values of the test specimens belonging to both group D and E appear in order of R1 < R2 < G1 < H1 < G2 < H2. Therefore, the strength values of group D and E can be indicator values for evaluating the six directions of rock cleavages. Second, the correlation chart between slope angle(θ) and strength difference(Δσ_t) were made. The values of the above two parameters were obtained from the five strength distribution lines connecting between the two directions. From the chart related to rift plane(G1-H1, R'), grain plane(R1-H2, G') and hardway plane(R2-G2, H'), the slope values of linear functions increase in order of R'(0.391) < G'(0.470) < H'(0.485). Among three planes, the charts related to hardway plane show the highest distribution density among the five groups. From the related chart for rift(R1-R2, R), grain(G1-G2, G) and hardway(H1-H2, H), the slope values of linear functions increase in order of rift(0.407) < hardway(0.453) < grain(0.460). Among three rock cleavages, the charts related to rift show the highest frequency of groups belonging to the lower region. Taken together, the width of distribution of the slope angle among the three planes and three rock cleavages increase in order of H' < G < R' < R < G' < H. Third, the correlation analysis among the parameters related to microcrack length and the tensile strengths was performed. These parameters may include frequency(N), total length(Lt), mean length(Lm), median length(Lmed) and density(ρ). The correlation charts among individual parameters on the above microcrack(X) and corresponding five levels of tensile strengths for the five groups(Y) were made. From the five kinds of correlation charts, the values of correlation coefficients(R²) increase along with the five levels of strengths. The mean values of the five correlation coefficients from each chart increase in order of 0.22(N) < 0.34(Lt) < 0.38(ρ) < 0.57(Lmed) < 0.58(Lm). Fourth, the correlation chart among the corresponding maximum strength for group E(X) and the above five parameters(Y) were made. From the related chart, the values of correlation coefficient increase in order of 0.61(N) < 0.81(Lt) < 0.87(ρ) < 0.93(Lm) < 0.96(Lmed). The two parameters that have the highest correlations are median length with maximum strength. Through the above correlation analysis between microcrack and strength, the credibility for the results from this study can be enhanced.