• Journal of Advanced Marine Engineering and Technology
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• v.27 no.3
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• pp.437-446
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• 2003

A large eddy simulation (LES) is performed for turbulent pipe flow. The simulation code is constructed by using a general coordinate system based on the physical contravariant velocity components. The effects of grid fineness which can be well prediction of turbulent behavior in near wall region is investigated. The subgrid scale turbulent models are applied and validated emphasis is placed on the flow details of turbulent pipe flow The calculated Reynolds number is 360 based on the wall shear velocity and the inlet pipe diameter. The predicted turbulent statistics are evaluated by comparing with the DNS data of turbulent pipe flow Performed by Eggels et al. The agreement of LES with DNS data is shown to be satisfactory. The proper grid fineness of the well prediction of turbulent pipe flow is suggested and the turbulent behavior is analyzed by depict the contour plot of fluctuating velocity components.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.3
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• pp.578-597
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• 2014

Understanding of 'spatial' pressure distribution is required to determine design loads on local structures, such as plating and framing. However, obtaining a practical 'spatial' pressure distribution is a hard task due to the sensitivity of the data acquisition frequency and resolution. High-resolution Pessure-Idicating Flm (PIF) was applied to obtain pressure distribution and pressure magnitude using stepped crushing method. Different types of PIF were stacked at each test to creating a pressure distribution plot at specific time steps. Two different concepts of plotting 'spatial' pressure-area curve was introduced and evaluated. Diverse unit pixel size was chosen to investigate the effect of the resolution in data analysis. Activated area was not significantly affected by unit pixel size; however, total force was highly sensitive.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.623-628
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• 2000

This paper deals with an analysis and reduction of escalator vibration by using the response surface model. Optimization of the escalator vibration is performed by minimization of the vibration responses which are measured at steps. The response surface models of the factors are constructed by using the experimental data based on the D optimal design method. The multi-objective optimization is also performed by applying desirability function and overlaid contour plot techniques. The optimal solution, which is obtained for a typical escalator system, is applied to reduce the escalator vibration.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.621-626
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• 2021

A sequential design of experiments was used to optimize MOF-801 synthesis process. For the initial screening, a general 2^k factorial design was selected followed by the central composition design, one of the response surface methods. A 2³ factorial design based on the molar ratio of fumaric acid, dimethylformamide (DMF), and formic acid was performed to select the more suitable response variable for the design of experimental method among the crystallinity and BET specific surface area of MOF-801. After performing 8 synthesis experiments designed by MINITAB 19 software, the characteristic analysis was performed using XRD analysis and nitrogen adsorption method. The crystallinity with R² = 0.999 was found to be more suitable for the experimental method than that of BET specific surface area. Based on analysis of variance (ANOVA), it was confirmed that the molar ratio of fumaric acid and formic acid was a major factor in determining the crystallinity of MOF-801. Through the response optimization and contour plot of two factors, the optimal molar ratio of ZrOCl₂·8H₂O : fumaric acid : DMF : formic acid was 1 : 1 : 39 : 35. In order to optimize the synthesis process, the central composition design on synthesis time and temperature was performed under the identical molar ratio of precursors. The results derived through the designed 9 synthesis experiments were calculated using the quadratic model equation. Thus, the maximum crystallinity of MOF-801 predicted under the synthesis time and temperature of 7.8 h and 123 ℃, respectively.

• Journal of the Korean GEO-environmental Society
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• v.12 no.10
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• pp.57-62
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• 2011

This study investigated the effects of various inorganic anions($Cl^-$, $NO_3{^-}$, $HCO_3{^-}$) on the Methyl tert Butyl Ether(MTBE) degradation by photocatalysis using statistical method. Generally, this process in general demands the generation of hydroxyl radicals(OH radical) in solution in the presence of UV light. The generation of radicals were affected by inorganic anions in solution that inhibited the photodegradation by their trapping hydroxyl radicals. The effects of inorganic anions were mathematically described as the independent variables such as $Cl^-$, $NO_3{^-}$, and $HCO_3{^-}$, and these were designed by mixture analysis that was one of the response surface methodology(RSM). Regression analysis on ANOVA showed significant p-value(p<0.0001) and high coefficients for determination value($R^2$=99.28%, ${R^2}_{adj}$=98.91%). Contour and response surface plots showed that the effects of inorganic anions for MTBE photodegradation based on $UV/H_2O_2$ process. In the result, $Cl^-$ and $HCO_3{^-}$ inhibited the photodegradation of the MTBE by their trapping hydroxyl radicals, and the interaction by these two factors was observed.

• Journal of Ocean Engineering and Technology
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• v.23 no.5
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• pp.71-78
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• 2009

In ship design or offshore structure design, the evaluation of buckling strength (or ultimate strength) is critical to the determination of scantling of stiffened plates. For this reason, it is useful to study the effect of applying different formula or the relationship between stiffened plate with buckling utilization factor (UF). It can facilitate a designer to decide how much the scantling should be reinforced or how much can be reduced for an optimal design. This paper conducts a comparative study for three buckling check methods; DNV-Ship-Rule, DNV-RP-C201, DNV-PULS. The capacity curves and 2D contour plot for utilization factors versus bi-axial in-plane stresses are compared. The contour plots of DNV-Ship-Rule and DNV-PULS show smoothly increasing trends of UF as the applied in-plane stresses increase, however that of DNV-RP-C201 shows rapidly increasing trend as the applied stresses go beyond transverse buckling stress. A sensitivity analysis is performed to investigate the influence level of each parameter of a stiffened plate on UF. Resulting from the analysis, plate thickness is identified to be the most affective parameter to UF regardless of the buckling check methods. Based on the addressed study, optimal designs for bottom plate of 165 K tanker corresponding to three formulas are compared with each other. DNV-PULS yields 1 mm and 2 mm less thickness than DNV-Ship-Rule and DNV-RP-C201, respectively.

• Journal of Korean Society of Forest Science
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• v.31 no.1
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• pp.43-47
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• 1976

This study was carried out to find out the effect of soil and water storable pits on reducing the surface runoff. 10 pits were digged in each plot of $50m^2$ along contour line. One kind of pits has a size of 30 cm width, 100cm length and 30cm depth, and the other has 30cm width, 100cm length and 20cm depth. 1. The soil and water storable pits have a significant effect on reducing surface runoff. Control plot had surface runoff 2.3-2.6 times more than the plots with pits. 2. There is no significant difference in surface runoff between 30cm depth pit and 20cm depth pit. 3. The soil and water storable pits did not have any effect on coverage, survival and growth of three species. 4. Steep slope had worse results than the other slopes in coverage, growth and fresh weight of experiment species.

• Korean Journal of Environmental Agriculture
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• v.24 no.1
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• pp.29-33
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• 2005

To develop proper soil management practices for reducing soil erosion, experiments were carried out by using lysimeters in Pyeongchang highland, Korea. Lysimeters installed at Hoenggye bad 13% slope, 15 m slope length and 3 m width. Lysimeters with 23% slope, 15 m slope length and 3 m width were also installed at Yongsan. Soil textures in Hoenggye and Yongsan lysimeter plots were silty clay loam and sandy loam, respectively. In the lysimeters potato was cultivated, and slant furrow culture and contour culture were applied. Up-down furrow and continuous fallow lysimeter was included in the experiments as a control plot. For the slant furrow and contour culture methods, minimum furrow mulching and gravel barrier were placed at each end of the furrows in the lysimeters from April to October in 2000 and 2001 to prevent soil and nutrient losses. In Heonggye, in two years experiments, average soil loss of 17 Mg/ha was found in the up-down and continuous fallow lysimeter and 2.6 Mg/ha from furrow minimum straw and slant furrow treatment, and 1.8 Mg/ha from slant furrow and gravel bag treatment. In the contour culture, the soil losses were further reduced. In Yongsan, soil loss in the slant furrow culture without any protection treatment was 167 Mg/ha, and the soil loss was reduce to 61 and 86 Mg/ha with minimum straw and gravel bag treatments, respectively. The soil loss could be reduced more than 45% by furrow minimum straw and gravel barrier. The furrow minimum straw or gravel bag barrier successfully reduced soil loss in clay loam soil in Heonggye, but still the treatments were not enough to reduce soil loss in saprolite piled sandy loam soil in Yongsan.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.191-210
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• 2017

The concern study, present the results of experimental study on the performance of deep excavation by using image processing technique particle image velocimetry (PIV). The purpose of present study is to check the application of PIV for the successive ground deformation during deep excavation. To meet the objectives of concern study, a series of reduce scale model test box experiments are performed by considering the wall stiffness, ground water table effect and ground relative density. The results are presented in form of contour and vector plots and further based on PIV analysis wall and ground displacement profile are drawn. The results of present study, indicate that, the PIV technique is useful to demonstrate the ground deformation zone during the successive ground excavation as the degree of accuracy in PIV analysis and measured results with LVDT are within 1%. Further the vector and contours plot effectively demonstrate the ground behavior under different conditions and the PIV analysis results fully support the measured results.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.1
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• pp.57-67
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• 1989

Acoustic intensity method is applied to a 4-cylinder gasoline engine in order to identify the noise sources and the response characteristics. Acoustic intensity is analyzed by 1/3 octave band filter for each center frequency. Radiational characteristics of acoustic intensity at overall and the maximum intensity level are represented by using the contour and three-dimensional plot. It is verified that this method is effective to the assessment of engine noise. It can be found that the maximum intensity is radiated from the front side of the engine under idling condition and the right side of it under 2, 000 rpm running with no loading condition at overall level, and also that the maximum intensity is radiated from the oil pan and the intake and exhaust manifold at the center frequency of 100 Hz.