• Journal of the Korean Society for Railway
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• v.16 no.1
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• pp.20-25
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• 2013

The frame elements of modern high speed trains are typically fabricated with extruded aluminum panels. However, the sound transmission loss (STL) of extruded aluminum panels is less satisfactory than flat panels with the same surface density. This study proposes a method for prediction of the sound transmission loss of extruded aluminum panels using finite element analysis. The panel is modeled by finite element analysis, and the STL is calculated using a measure of Sommerfeld radiation at the specimen surface, boundary conditions, and the internal loss factor of the material. In order to verify the validity of the predicted value, intensity transmission loss was measured on the aluminum specimen according to ASTM E2249-02. The proposed method of analysis will be utilized to predict the sound insulation performance of extruded aluminum panels for railway vehicles in the design stage, and to establish measures for their improvement.

• Korean Journal of Environmental Agriculture
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• v.33 no.2
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• pp.69-77
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• 2014

BACKGROUND: The purpose of this study was to investigate the effects of clothianidin on the soil in terms of clothianidin dissipation and degradation to evaluate its safety in order to provide an analytical foundation for clothianidin and the 5 metabolites related to it. METHODS AND RESULTS: High-performance liquid chromatography(HPLC) was used to separate clothianidin and its metabolites in this study. In soil, after suppressing dissociation-proned ions with weak alkalic $NH_4OH$ and extracting the metabolites with methanol, clothianidin, Methylaminoimidazole(MAI), Methylnitroguanidine(MNG), Thiazolylmethylurea(TZMU) and Thiazolylnitroguanidine(TZNG). Thiazolylmethylguanidine(TMG) were extracted with the addition of neutral $NH_4OAC$ to increasing the intensity of ions. Compounding elements were separated by using Hydrometrix ($ChemElut^{TM}$) and ion-exchanging Solid-phase extraction(SPE) Strong cation-exchanger(SCX) and C18 were used. The recovery rates of clothianidin and 5 metabolites in soil and water ranged from 87.4% to 104.3%. A standard deviation of our analysis for the soil and water samples were less than 5%. CONCLUSION: Well accepted detection limits for clothianidin and 5 metabolites in soil samples based on a dissipation analysis is 0.005 mg/kg and 0.001 mg/L in water samples. The dissipation concentration of this study was decided to be enough to evaluate the dissipation levels of clothianidin and its metabolites.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.5
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• pp.215-221
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• 2017

The effect of austenitizing temperature on the degree of carbides re-solutionizing, mean graine size, hardness and the volume fraction of retaind austenite ($V_{\gamma}$) etc., has been studied by means of metallography, X-ray diffractometry and hardness measurement in STD 11 tool steel. As austenitizing temperature increases, the amount of alloying elements which is re-dissolved into matrix increases, resulting in increase of $V_{\gamma}$, due to the chemical stabilization of austenite. The Vickers hardness value decreases with increasing austenitizing temperature, which is attributed to grain size as well the volume fractions of $V_{\gamma}$ and carbides. Theoretical diffraction intensity of (200) ${\alpha}^{\prime}$, (211) ${\alpha}^{\prime}$ (200) ${\gamma}$ and (220) ${\gamma}$ peaks obtained by $CuK_{\alpha}$ chracteristics X-ray (${\lambda}=0.15429nm$) was calculated, and quantitative analysis of $V_{\gamma}$ could be carried out by X-ray diffraction method. The resultant value is well coincided with the value obtained by image analysis method. When the quenched specimen is tempered above $200{\sim}400^{\circ}C$ for 30 min, the transition carbides i.e., MC and $M_2C$ in the size of about 20 nm begin to precipitate at $300^{\circ}C$.

• Journal of Biosystems Engineering
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• v.35 no.6
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• pp.420-425
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• 2010

We produced a basic system of sterilization of nutrient solution based on the characteristics of coated filter with the visible light-reactive titanium oxide photocatalyst according to the findings of the first stage. We developed a model system with a proper number and arrangement of filter elements, the visible light-reactive titanium oxide photocatalyst according to findings from the basic performance test. Main results of this study were as followers; The ceramic filters showed the best performance of sterilization of nutrient solution. The visible light-reactive titanium oxide photocatalyst sterilized more effectively the nutrient solution under the sunlight than UV light. The sterilization performance by passing repeatedly through a few filter was more efficient than that by treating simultaneously with a large number of filters. The filter with 15ppi in pore size, 20 mm in thickness, and 3 layers in titanium oxide coating was desirable in the intensity and sterilization performance.

• Geomechanics and Engineering
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• v.36 no.3
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• pp.231-245
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• 2024

In recent decades, the protection and vulnerability of civil structures under explosion loads became a critical issue in terms of security, which may cause loss of lives and structural damage. Concrete retaining walls also restrict soils and slopes from displacements; meanwhile, intensive temporary loading may cause massive damage. In the current study, the modified Johnson-Holmquist (also known as J-H2) material model is implemented for concrete materials to model damages into the ABAQUS through user-subroutines to predict the blasting-induced concrete damages and volume strains. For this purpose, a 3D finite-element model of the concrete retaining wall was conducted in coupled Eulerian-Lagrangian simulation. Subsequently, a blast load equal to 500 kg of TNT was considered in three different positions due to UFC 3-340-02. Influences of the critical parameters in smooth blastings, such as distance from a free face, position, and effective blasting time, on concrete damage rate and destroy patterns, are explored. According to the simulation results, the concrete penetration pattern at the same distance is significantly influenced by the density of the progress environment. The result reveals that the progress of waves and the intensity of damages in free-air blasting is entirely different from those that progress in a dense surrounding atmosphere such as soil. Half-damaged elements in air blasts are more than those of embedded explosions, but dense environments such as soil impose much more pressure in a limited zone and cause more destruction in retaining walls.

• Culinary science and hospitality research
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• v.19 no.4
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• pp.231-242
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• 2013

This study was performed to develop cod bone stock using various nutritional elements in cod bone with the addition of various amounts of tomatoes (2%, 4%, 6% and 8%). Moisture contents, pH, L value and Na contents decreased, while the salinity, sugar contents, a value, b value and Mg, K, Ca, Fe contents increased with increased rates of tomatoes. Fourteen types of free amino acid were detected, and stock containing 6% of tomato addition had the highest free amino acid content. In the test on different attributes, tomato content significantly affected the properties of the stock including color intensity, savory flavor, tomato flavor, tomato taste, savory taste and after taste. In the acceptance test, 6% of tomato addition was preferred for appearance, flavor, taste, texture and overall quality. Consequently, the optimal tomato content for maximizing the overall quality of cod bone stock was 6%.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.2
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• pp.85-102
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• 2021

Phytosociological characteristics on Quercus acutissima forests distribution in Daechong-dam basin survey has been carried out using Z.-M. School's methodology and numerical-classification analyses. A total of 43 phytosociological relevés were sampled. Syntaxa were described as Oplismenus undulatifolius-Quercus acutissima community(typicum subcommunity, Phryma leptostachya var. asiatica subcommunity, Ulmus davidiana var. japonica subcommunity), Quercus acutissima community and Quercus variabilis-Quercus acutissima community (typicum subcommunity, Castanea crenata subcommunity). The above three plant communities were classified with species composition reflecting local environmental characteristics of mountain topographies, inclination degrees, and rock exposure rates. Conclusively, those communities were recognized as secondary vegetation affected by high intensity and frequency of human impacts as they inhabited in southward hill lands and low lying grounds in mountains adjacent to human settlements and arable lands. Quercus acutissima community was classified as rural type syntax based on their inlandward distribution and species composition differences from urban forests. Afforest process and natural succession were discussed in relation with habitat environmental elements of Quercus acutissima forest in the survey area.

• Journal of Environmental Science International
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• v.17 no.4
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• pp.413-422
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• 2008

This study aims to find out a state of the damages and vulnerable areas from natural disasters in the Korean peninsula using the prevention meteorological database information made by Park(2007b). Through the correlation analysis between damage elements and total property losses, we investigate the damages of public facilities, which have high correlation coefficient, and the cause of disasters and want to propose the basic information to set up the disaster prevention measures in advance. As a result, because most of the total property losses is the damages of public facilities, we can reduce the damages of natural disasters if we can predict the damages of public facilities or carry out the prevention activities in advance. The most vulnerable area for the natural disasters are Cangwon-do and Gyeongsangnam-do provinces. The vulnerable areas for the damages of public facilities by typhoon are Daegu metropolitan city, Cangwon-do, and Gyeongsangbuk-do provinces. These vulnerable areas will take place more frequently due to the climate change including Gyeongsangnam-do province so that we need to set up the disaster prevention measures and natural disaster mitigation plan. Also, we think that it has effect on reducing the damages of natural disasters to predict the damage scale and strongly perform the prevention activities in advance according to typhoon track and intensity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.9
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• pp.961-971
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• 2008

In the design of a rotor shaft, care should be taken to minimize vibration by taking into account the sources of vibration. In addition, the intensity critical speed, stability, and other related aspects of the system must be considered. especially when it is operated at a critical speed, it is important to address issues related to vibration, as an increase in the whirling response of the rotor shaft can cause damage to the shaft, destruction of the rotor parts, and detrimental abrasions on the bearings. In this thesis, the vibration characteristics of a rotor shaft are investigated through the use of the finite element method. Variations of the diameters and lengths were used to determine the effect of a rotor shaft using Beam No.188(3D linear strain beam) in ANSYS version 11.0 as a universal interpretation program for finite elements. Special care was taken to prevent excessive vibration, which can result from resonance at the initial stage, in the formulation of a dynamic design for a rotor shaft through calculations while changing the diameters and the lengths of the shaft. Moreover, the dynamic characteristics of the critical speed, total mass, D/L(diameter to length) ratio, and natural frequency were verified. Furthermore, the rotor shaft applied by bearing element was calculated and compared by using Combi No. 214(2-D spring-damper bearing).

• Proceedings of the Korea Contents Association Conference
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• 2005.11a
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• pp.153-160
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• 2005

It is within bounds to say that the mood expressed in the Scenes of 3D Animation influences by mostly setting up of 3D CG lighting. Tn the context of CG, lighting is the process of illuminating digital scenes in an artistic and technical manner so the audience can perceive what the director intends to display on the screen with the appropriate clarity and mood. The lighting has the role of making the scenes beautiful and harmonious as an aesthetics of light and color created and controlled by people. It can be also stylized in symbolic and metaphorical methods environmental mood which we pursue to expose and story which we want to express. It thus appears that the concept of lighting style is intimately related to the particular context and art direction of animation film. But unfortunately, there are no foolproof formulas to the process of lighting a scene. In short, the lighting contributes to define the style of the scene as a conditional lighting setups' elements including position, color, intensity, shadow's area and scope. But at the same time, we must not overlook the artistic aspects that the lighting might suggest over all moods the animation genre and the style of scene like tranquility, suspense, and high-drama.