• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.8
• /
• pp.1089-1098
• /
• 2018

In this paper, we propose an autonomous feeding robot and its obstacle classification system using ultrasonic sensors to secure the driving safety of the robot and efficient feeding operation. The developed feeding robot is verified by operation experiments in a cattle shed. In the proposed classification algorithm, not only the maximum amplitude of the ultrasonic echo signal but also two gradients of the signal and the variation of amplitude are considered as the feature parameters for object classification. The experimental results show the efficiency of the proposed classification method based on the Support Vector Machine, which is able to classify objects or obstacles such as a human, a cow, a fence and a wall.

• Journal of Plant Biology
• /
• v.16 no.3_4
• /
• pp.1-6
• /
• 1973

The distribution of plant communities along the Bukhan Riverside in Chun-seong was studied by means of the methods fo Curtis and Pattern. The communities were arranged in a single-dimensioned ordination on the basis of the importance values of the persistent species. Leading dominant species, form the 'low' level to the 'high' levels of the ordination gradient, were Phalaris arundinacea, Salix gilgiana, Artemisia feddei, Zoysia japonica, Pennisetum japonicum, and Arundinella hirta. These species from a continuum from the river to the dry grassland depending upon available soil-moisture. Standing crops in terms of dry weight and the nitrogen content of the above-ground parts of these species showed a good relationship with gradients of available soil-moisture.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.13 no.1
• /
• pp.97-103
• /
• 2000

This paper deals with residual stresses induced at the viscoelastic adhesive layer between the semiconductor chip and the leadframe during adhesion process. The adhesive layer has been assumed to be“thermorheologically simple”. The time-domain boundary element method(BEM) has been employed to investigate the behavior of interface stresses. Numerical results show that very large stress gradients are present at the interface corner and such singularity might lead to local yielding or edge delamination.

• Korean Journal of Crystallography
• /
• v.1 no.1
• /
• pp.8-13
• /
• 1990

Synthetic citrines were grown by hydrothermal method. For the establishment of grown conditions of large citrine, various types and/or amount of nutrients, seed orientations, mineralizers, colorants and temperature gradients were studied. For the evaluation of the quality of as grown citrine, color tone, crystal form, macro-and micro-defects were observed and crystal structure and absorption spectrums were analyzed. As a result, large sized citrines of 205mm L x 58mm W x 35mm T with excellent color tone and minium defects were grown.

• Korean Journal of Materials Research
• /
• v.14 no.4
• /
• pp.281-286
• /
• 2004

The oxide scales formed on Ni-18W(at.%) coating that was electrodeposited on steel were investigated using XRD, SEM and TEM. The oxide scales consisted mainly of an outer NiO layer, and an inner thick ($NiWO_4$+NiO) mixed layer. The unoxidized coating below the oxide scale was rich in Ni and depleted in W, owing to the consumption of Wand the resultant Ni enrichment. The oxidation resistance of Ni-18W coating was poorer than that of the TiN coating, due to the formation of nonprotective NiWO$_4$. During oxidation, Ni and the substrate element of Fe diffused outward, while oxygen inward, according to the concentration gradients.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.05a
• /
• pp.205-208
• /
• 2001

Localized shear band is investigated through the analysis of one-dimensional model for simple shearing deformation of thermally rate dependent material. Generally mesh size or interval of nodes play an important role in determining the overall flow behavior of the material. In order to observe these size effects we adapted non-local theory by including higher order strain gradients of the equivalent strain into the constitutive equation for the flow stress. for the ease of convergence and numerical stability the inplicit finite difference scheme is employed.

• Transactions of Materials Processing
• /
• v.9 no.2
• /
• pp.193-202
• /
• 2000

The influence of rolling draughts on the formation of through-thickness textures in aluminum 5000X sheet was investigated by X-ray texture measurements and microstructure observations. In order to intensify the deformation inhomogeneities, cold rolling was performed without lubrication. Applying a large draught gave rise to the formation of the shear texture at the surface, whereas a normal plane strain testure formed at the surface after deformation with a small draught. The orientation density along the $\beta$-fiber orientations which developed in the center layer of the rolled specimen was also dependent on the strain gradients in a roll gap. Upon annealing, the deformed substructure of sample surfaces was transformed into a fine grained recrystallized microsturcture through extended recovery reaction. However, coarse grains developed after the discontinuous recrystallization which gave rise to the development of the Cube-texture.

• Food Science and Biotechnology
• /
• v.15 no.1
• /
• pp.133-137
• /
• 2006

Wheat gluten-chitosan composite film (WGCCF) can prevent moisture migration and enhance the antimicrobial properties of gluten in intermediate-moisture foods like sandwiches. To mimic the structure of actual sandwich-type products we developed multi-layer food models, where moisture content and water activity differ. Water activity gradients direct moisture migration and therefore determine product characteristics and product stability. A 10% wheat gluten film-forming solution was mixed with chitosan film-forming solution (0-3%, w/w) and evaporated to generate WGCCF. Addition of 3% chitosan enhanced the mechanical properties of the film composite, lowered its water vapor permeability, and improved its ability to protect against both, Streptococcus faecalis and Escherichia coli, in a 24 hr sandwich test (reduction of 1.3 and 2.7 log cycles, respectively, compared to controls). Best barrier and antimicrobial performance was found for 3% chitosan WGCCF at pH 5.1. Film of this type may find application as barrier film for intermediate-moisture foods.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1609-1611
• /
• 1994

In ECR and helicon reactors for plasma processing, a high density plasma is generated in a source region which is connected to a diffusion region where the processing takes place. Large density and potential gradients can develop at the orifice of the source which drive ion currents into the diffusion region. The average ion velocity may become the order of the sound velocity. Measurements of the ion saturation current to a Langmuir probe are used as a standard method of determining the plasma density in laboratory discharges. However, the analysis becomes difficult in a steaming plasma. We have used the HAMLET plasma simulator to simulate the ion flow to a large langmuir probe in an ECR plasma. The collection surface was aligned with the Held upstream, normal to the field, and downstream. ion trajectories through the electric and magnetic fields were calculated including ion-neutral collisions. We examines the ratio of ion current density to plasma density as a function of magnetic field and pressure.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.834-835
• /
• 2006

Manganese is an alloying element that improves the hardenability of steels. It could be a valid substitute in sintered steels, increasing mechanical properties. The hardenability of three low alloy Mn steels was studied to establish the influence of manganese on the heat treatments. The Grossmann approach was adopted, which uses cylinders with different diameters to induce different gradients of cooling rate in the cross section. The correlation of microstructure and microhardness to the actual cooling rate makes the results independent on the process parameters and applicable to each industrial condition, once the actual cooling rate in the parts is known.