• Journal of Industrial Technology
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• v.18
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• pp.195-202
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• 1998

The effect of the number of nodes on the heat loss from a rectangular fin for a finite difference method is studied. There are two ways for selecting nodes for the upper half fin in this finite difference method. In the first place, all the ${\Delta}x$ are the same and all the ${\Delta}y$ are the same for the entire upper half fin. Incremental length of x (i.e. ${\Delta}x$) is divided by two near the fin tip while all the ${\Delta}y$ are the same for another way. The results show that 1) About 30 nodes are enough to obtain the satisfactory exact analysis (relative error < 5%) on the heat loss for a given range of Biot number in case of short fin (i.e. $L{\leq}2$). 2) Under usual circumstances (Bi<0.1), the relative error of heat loss between using 30 nodes and 90 nodes is within 4% for given range of non-dimensional fin length. 3) The relative error of the calculated heat loss (the number of node=90) as compared to the expected exact heat loss is less then 1.5% for Bi=0.1 and L=10 while that is over 13% for Bi=1.0 and L=10.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.827-832
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• 2003

This study presented the reinforcing effect of sands by using newly devised 3D Tirecell. Plate loading tests for sand were conducted for different relative density and number of reinforced layers. From the tests, the ultimate bearing capacity of reinforced sand increased with increasing relative densities. The effect of reinforced layers with 0.4B interval is limited to 2 layers and further reinforcing effects can not be obtained beyond 3 layers. Especially the bearing capacity increased remarkably at 1 layer of Tirecell reinforcement and the degree of increase was small for 1 layer to 2 layers increase of reinforcement. Test results show that the reinforcing effect of Tirecell is prominent compared with commercial geocell in the literature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.60-63
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• 2000

In this study, efficient force reflection algorithm is developed for the Haptic Display by using a proxy concept and friction model. When there are not any contacted obstacles the proxy is following human operator's command trajectory in the 3D virtual space. But when the operator's command trajectory is locating inside of the object, the proxy is constrained by the surface of the object. Here only with the information of the proxy position and operator's command trajectory at every time step, we can calculate the reflection force and its orientation. To display the friction force between two virtual stiff material which are sliding against each other, modified Karnopp's friction model is used. In the friction model, a damping term and a Stribeck effect term are included to display the relative velocity effect and stick-slip effect at the very low relative velocity region respectively.

• Biomolecules & Therapeutics
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• v.2 no.1
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• pp.54-58
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• 1994

BALB/C mice were intraperitoneally injected with methamphetamine (5 mg/kg) to observe the effect of methamphetamine on the immune system. Body weights were decreased in both acutely treated group (twice for 2 weeks with 7 days interval) and subchronically treated group (daily injection for 14 days). The relative spleen weights and the numbers of splenocytes were unexpectedly increased (p<0.05) in acutely treated group, but subchronically treated group showed the trend of decrease without significance. But there was no significant effect on antibody formation to hen egg Iysozyme which was immunized during the treatment of methamphetamine and on plaque forming cell number. The relative thymus weights of both groups were significantly decreased by the treatment of methamphetamine (acutely treated group, p<0.05; subchronically treated group, p<0.01). These results suggest that the effect of methamphetamine on the immune system may be caused by thymic dysfunction.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1027-1028
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• 2007

In this paper, the variation of air-gap field intensity caused by the slot-opening in interior permanent magnet (IPM) motor is investigated, which is for predicting the instantaneous magnetic field more preciously in analytical method further. It is different with the approach of dealing the slot-opening effect on the air-gap field distribution with the "relative permeance" function in surface permanent magnet (SPM) motor. The prediction of the air-gap field in IPM motor is much more complex than SPM motor. In this study, an approximate estimation method is adopted based on analyzing the changing of flux path in both the IPM rotor part and stator part, and in additional an analytical function defined as "relative pole-arc" is built. The finite element method(FEM) is used for confirming the slot-opening effect on the field prediction.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.1
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• pp.61-65
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• 1988

To examine the effects of light intensity on photosynthesis, corn and sorghum species were grown under shade cloths, which reduced light intensity by 25,50 and 75%. Photosynthetic rates were measured between 10 a.m. to noon on a clear day in early and mid - summer. 1. The degree of shading had a little effect on microenvironment. Air, soil and leaf temperatures were reduced as shade increased. 2. The degree of shading in early summer had relatively a little effect on photosynthesis of corn. However, the rates of photosynthesis in mid-summer decreased by 36%, 55% with relative light intensities of 50% and 25%, respectively. 3. The rate of photosynthesis was highly correlated with light intensity. The rates of photosynthesis with relative light intensities of 75,50 and 25% were decreased by 20, 40 and 5 4% in early summer, and by 17-53%, 36-64% and 5570% in mid-summer, respectively. 4. The 75% of light intensity had relatively little effect on dry matter yield of corn and sorghum species, however dry matter yield with 50 and 25% relative light intensities was decreased 17 and 36% in corn, 13-3 1 and 50-68% in sorghum species, respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.6
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• pp.59-67
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• 2006

Particles of soil are crushed when soil is compacted in the in-situ or lab. Among many factors that affect the crush of particles, compaction energy is a major factor. Because the crush of particles can change physical properties, the analysis of effect of compaction energy is very important. In this study, the fragmentation fractals were used for determining the change in grain size distribution and the effect due to change in grain size distribution was estimated. Compaction energy was increased by 50, 100, 200 and 300% based on the energy of standard A compaction test. As a result, grain size distribution curves were changed and fine particles increased as compaction energy were increased. Relative compaction were ranged between $93.38{\sim}107.67$. Fractal dimension of each site increased as compaction energy increased. Relative compaction is proportional to the fractal dimension but coefficients of permeability were in inverse proportional to the involution of fractal dimension.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.433-442
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• 1993

Coolstore air relative humidity (RH) is an important factor affecting the quality of horticultural products, particularly via product moisture loss. RH also has an important effect on the performance of the refrigeration evaporators and can affect the strength of paper-based packaging materials. In a large New Zealand apple coolstore, RH increased from about 75% early in season to 90% at the end, as activities in the coolstore and external conditions changed. A steady-state analysis of sensible and latent heat entry and heat removal during four typical operational periods over the season was carried out. Predicted RH was in good agreement with measured dat. For the coolstore studied, evaporator surface area and the occurrence of pre-cooling within the coolstore were the design and operational factors having greatest effect on RH. Door protection and management, and floor insulation were the next more significant factors. The method of analysis has more general application and ould be used in a variety of situations so that design for optimum RH can be performed systematically.

• Transactions of Materials Processing
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• v.13 no.3
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• pp.225-229
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• 2004

Chemical Mechanical Polishing(CMP) process becomes one of the most important semiconductor processes. But the basic mechanism of CMP still does not established. Slurry fluid dynamics that there is a slurry film between a wafer and a pad and contact mechanics that a wafer and a pad contact directly are the two main studies for CMP. This paper based on the latter one, especially on the abrasion wear model. Material Removal Rate(MRR) is calculated using the trajectory length of every point on a wafer during the process time. Both the rotational velocity of a wafer and a pad and the wafer oscillation velocity which has omitted in other studies are considered. For the purpose of the verification of our simulation, we used the experimental results of S.H.Li et al. The simulation results show that the tendency of the calculated MRR using the relative velocity is very similar to the experimental results and that the oscillation effect on MRR at a real CMP condition is lower than 1.5%, which is higher than the relative velocity effect of wafer, and that the velocity factor. not the velocity itself, should be taken into consideration in the CMP wear model.

• Journal of Environmental Science International
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• v.30 no.5
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• pp.379-389
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• 2021

Soil microorganism activity in an agricultural field is affected by various factors including climate conditions, soil chemical properties, and crop cultivation. In this study, we elucidate the correlation between microorganism activity and agricultural environment factors using the dehydrogenase activity (DHA) value, which is one of the indicators of soil microbial activity. As a result, the various factors noted above were related to the DHA value. Annual rainfall, soil Mg2+, bacterial and fungal diversities, types of crops, developmental stages, seasons, and cultivation status were highly correlated with the DHA value. Furthermore, next-generation sequencing (NGS) analysis was used to identify that the type of crop affected soil microbial compositions of both bacteria and fungi. Soil used for soybean cultivation showed the highest relative abundance for Verrucomicrobia, Planctomycetes, and Acidobacteria but Actinobacteria and Firmicutes had the lowest relative abundance. In the case of soil used for potato cultivation, Actinobacteria had the highest relative abundance but Proteobacteria had the lowest relative abundance. Armatimonadetes showed the highest relative abundance in soil used for cabbage cultivation. Among the fungal communities, Mortierellomycota had the highest relative abundance for soybean cultivation but the lowest relative abundance for cabbage cultivation; further, Rozellomycota, Chytridiomycota, and Cercozoa had the highest relative abundance for cabbage cultivation. Basidiomycota had the highest relative abundance for potato cultivation but the lowest relative abundance for soybean cultivation.