• Korean Journal of Environmental Agriculture
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• v.41 no.1
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• pp.24-31
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• 2022

BACKGROUND: The most common litter materials used in South Korea are sawdust, rice husk, etc. Recently, the cost of litter has been steadily rising, and the maturity test has been strengthened. For this reason, new litter materials are needed for better water control ability to solve the problems. The object of this study was to evaluate the water absorption properties for litter materials. METHODS AND RESULTS: The volumetric water capacity according to the addition of cow manure was investigated to calculate the water absorption speed of litter materials (sawdust, peatmoss, cocopeat, and biochar). The water absorption speed constant (-K) in the first stage was high in the order of cocopeat (0.1190), sawdust (0.0961), biochar (0.0762), and peatmoss (0.0523). The optimal period of the litter use was in the following order: peatmoss (48d), biochar (42d), sawdust (30d), and cocopeat (24d). The water absorption rate (%) of the used litters was high in the order of biochar ≈ cocopeat, sawdust, and peatmoss, which was significantly correlated with the water absorption speed of the first stage. CONCLUSION(S): Considering the water absorption speed and water absorption rate, biochar and peatmoss were found to be the best and optimal litter materials among the tested materials. These litter materials can be used as water control agents in livestock facilities.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.145-149
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• 2001

In this study, an acoustical characteristics of sound proof panel for high speed train was performed. A sound absorption coefficient and transmission loss of sound proof panels for high speed train were tested in reverberation chambers and compared those of ordinary sound proof panel. The effect of noise barrier was simulated by using ray noise program with measured sound absorption coefficient for high speed train case and for ordinary case.

• Journal of Power System Engineering
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• v.12 no.4
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• pp.46-51
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• 2008

Honeycomb panel has a constructive advantage because it is constructed with a honeycomb core, so it has relatively higher strength ratio to weight. Therefore honeycomb panel has been used as the light weight panels in the high-speed railway technology and high-speed ship like as cruise yachts. Also it has been used in the aircraft and aerospace industry as a structural panel because light weight structure is indispensible in that field of industry. Recently, the honeycomb panel is embossed in the viewpoints of high oil prices as the lightweight panel of the transport machine, however the sound insulation capacity of the honeycomb panel is poorer than those of uniform and another sandwich panels. In this paper a method to improving the sound absorption coefficient of a honeycomb panel Is studied by using the Helmholtz resonator. The sound absorption coefficients for some kinds of honeycomb cores are demonstrated by the normal incident absorption coefficient method.

• International Journal of Railway
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• v.6 no.3
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• pp.85-89
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• 2013

The purpose of this paper is investigating the effect and influence rates of utilizing thin walled energy absorption tubes for improving crashworthiness parameter by increasing energy absorption of the body in high speed railcars. In order to find this, a proper profile of available tubes is chosen and added to the structure of selected high speed train in Iranian railway network (Pardis Trainset) and then examined in the scenario of impact with other moving rolling stock. Because of the specific features of LS-DYNA 3D software at collision analysis, the dynamic simulation has been performed in LS-DYNA 3D. The results of the analysis clearly indicate the improvement of train crashworthiness as the energy absorption of structure increases more than 30 percent in comparison with the original body. This strategy delays and reduces the shock to the structure. The verification of the simulation is by using ECE R66 standard.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.165-171
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• 1999

An oil layer fuel absorption /desorption modeling was developed. Multi-component fuel model has showed more reasonable condition than single component model. Henry's constant which is related to solubility is the most important variable in the oil layer absorption/desorption mechanism. The oil segments close to the top of the cylinder liner have more significant contribution to the fuel absorption and desorption process than other oil segments. At the warmed-up condition, the effect of the engine speed on the precent fuel absorbed/desorbed is minimal. But at low il film temperature, percent of fuel abosrbed/desorbed is decreased with increasing the engine speed because of low value of molecular diffusion coefficient of fuel. The amount of fuel trapped in the piston crevice is from 2 to 2.3 times larger than that of fuel in the oil fim. However, fuel form oil film slowly desorbs into the combustion chamber compared with fuel from the piston crevices when the engines is cold.

• Ocean and Polar Research
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• v.29 no.2
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• pp.113-121
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• 2007

The sound wave in the sea propagates under the effect of water depth, sound speed structure, sea surface roughness, bottom roughness, and acoustic properties of bottom sediment. In shallow water, the bottom sediments are distributed very variously with place and the sound speed structure varying with time and space. In order to investigate the seasonal propagation characteristics of low-frequency sound wave in the Yellow Sea, propagation experiments were conducted along a track in the middle part of the Yellow Sea in spring, summer, and autumn. In this paper we consider seasonal variations of the sound speed profile and propagation loss based on the measurement results. Also we quantitatively investigate variation of bottom loss by dividing the propagation loss into three components: spreading loss, absorption loss, and bottom loss. As a result, the propagation losses measured in summer were larger than the losses in spring and autumn, and the propagation losses measured in autumn were smaller than the losses in spring. The spreading loss and the absorption loss did not show seasonal variations, but the bottom loss showed seasonal variations. So it was thought that the seasonal variation of the propagation loss was due to the seasonal change of the bottom loss and the seasonal variation of the bottom loss was due to the change of the sound speed profile by season.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.4
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• pp.460-476
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• 2012

High-speed crafts suffer from losing a huge amount of their machinery energy in the form of heat loss with the exhaust gases. This will surely increase the annual operating cost of this type of ships and an adverse effect on the environment. This paper introduces a suggestion that may contribute to overcoming such problems. It presents the possibility of reusing the energy lost by the ships' exhaust gases as heating source for an absorption air condition unit onboard high-speed crafts. As a numerical example; the proposed method was investigated at a high-speed craft operating in Red Sea between Egypt and the Kingdom of Saudi Arabia. The results obtained are very satisfactory. It showed the possibility of providing the required ship's air condition cooling load during sailing and in port. Economically, this will reduce the annual ship's operating cost. Moreover, it will achieve a valuable reduction of ship's emissions.

• Journal of the Korean Wood Science and Technology
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• v.26 no.1
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• pp.51-56
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• 1998

The bast fiber of paper bush misumada have been cultivated in south coast bay of the Korean peninsula were not used to handmade painting paper. Therefore, in using the bast fiber of paper bush misumada manufactured handmade painting paper, tested absorption speed, blot characteristics and organic functions. The results are summarized as follows; The handmade painting paper manufacured only the bast fiber of paper bush misumada proper to the absorption speed of China ink, didn't have difference of the length and width for blot. And it was most fitted to east writing-and-painting using. Also the flexibility excell, and light and shade in overpainting directly appeared, and fitted to black-and-white drawing. And the using increase plan of the paper bush misumada demanded.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.365-372
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• 2010

This paper was to evaluate the influence of kiln process parameter(kiln angle, kiln rotating speed) of lightweight aggregate using waste glass and bottom ash with industrial by-products on thermal conductivity, density, water absorption, fracture load and porosity by response surface analysis. In the results of surface plot and contour plot, it has verified that kiln residence time of lightweight aggregate increase as kiln angle and rotating speed decreases. For this reason, pore size and quantity tend to increase by active reaction of forming agent. It seems to be that increase in pore size and quantity have caused decreasing density, fracture load and thermal conductivity, and increasing water absorption. In conclusion, optimization of kiln process parameter on thermal conductivity, density, water absorption, fracture load and porosity by response surface analysis are kiln angle 2.4646%, kiln rotating speed 40.7089 rpm.

• Structural Engineering and Mechanics
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• v.91 no.1
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• pp.75-86
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• 2024

In this paper, the porous metal PM-35 is proposed as the filler material of filled thin-walled tubes (FTTs), and a series of experimental study is conducted to investigate the dynamic behavior and energy absorption performance of PM-35 filled thin-walled tubes under impact loading. Firstly, cylinder solid specimens of PM-35 steel are tested to investigate the impact mechanical behavior by using the Split Hopkinson pressure bar set (SHP); Secondly, the filled thin-walled tube specimens with different geometric parameters are designed and tested to investigate the feasibility of PM-35 steel applied in FTTs by the orthogonal test. According to the results of this research, it is concluded that PM-35 steel is with the excellent characteristics of high energy absorption capacity and low yield strength, which make it a potential filler material for FTTs. The micron-sizes pore structure of PM-35 is the main reason for the macroscopic mechanical behavior of PM-35 steel under impact loading, which makes the material to exhibit greater deformation when subjected to external forces and obviously improve the toughness of the material. In addition, PM-35 steel core-filled thin-wall tube has excellent energy absorption ability under high-speed impact, which shows great application potential in the anti-collision structure facilities of high-speed railway and maglev train. The parameter V0 is most sensitive to the energy absorption of FTT specimens under impact loading, and the sensitivity order of different variations to the energy absorption is loading speed V0>D/t>D/L. The loading efficiency of the FTT is affected by its different geometry, which is mainly determined by the sleeve material and the filling material, which are not sensitive to changes in loading speed V0, D/t and D/L parameters.