• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.307-311
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• 1997

This paper describes influence of thermal deformation on nosic characteristics in high speed spindle systems. Heat generation in front, rear spindle bearings and built in motor lead to diverse thermal deformation of headstock with time. This deformation changes assemble tolerance in bearing housing, especially to elliptic form. The elliptic assemble tolerance generate high nosie level with dominant amplitude in double rotational frequency.

• Animal Systematics, Evolution and Diversity
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• v.27 no.2
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• pp.123-130
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• 2011

The primitive beachflea, Paciforchestia pyatakovi (Derzhavin, 1937) living in gravel beaches was previously reported only from Japan and Russia. This species can be easily distinguished from another species in the same genus, P. klawei (Bousfield, 1961), by the degradation of all plepods and both rami that each consist of single article bearing 2-4 distal plumose setae. Descriptions of the diagnostic characteristics of the species are presented.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1221-1225
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• 2008

In this paper, analysis of pressure and flow characteristics have been performed with a servo valve. A number of servo valve have been used in various applications including the inserting device, bearing transportation and welding machine. By analysis of flow and pressure gradient, technology can be obtained about optimal simulation of high response servo valve for competitiveness. Spool displacement and ratio of inlet/outlet pressure can give big effects to flow and pressure inside servo valve.

• Tribology and Lubricants
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• v.17 no.2
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• pp.116-123
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• 2001

A theoretical analysis has been undertaken to show the influence of bearing geometry on the steady state characteristics of air lubricated spherical tilting pad bearings. The geometry variations considered are the number of pads, the eccentricity ratio, the direction of load, and the preloading. Dynamic characteristic equations are derived with pad assembly method.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.177-178
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• 2005

The load/unload behavior of the hard disk drive slider is studied in terms of the air bearing static characteristics. The numerical continuation methods are applied to calculate suspension force - equilibrium position curve. The critical preloads of the femto size slider are analyzed. The hi-stability conditions are depicted on the skew angle - preload diagram. The perturbation method is used to check the stability of the solution branches.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.47-51
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• 1996

Unsteady-state temperature distributions and thermal deformations of a spindle system are studied in this paper. Three dimensional model is built for analysis, and the amount of heat generation of bearing and the thermal characteristic values including heat transfer coefficient are estimated. Temperature distributions and thermal deformations of a model are analyzed using the finite element method and the termal boundary values. Numerical results are compared with the measured data. The results show that thermal deformations and temperature distributions of a high precision spindle system can be reasonably estimated using the three dimensional model and the finite element method.

• Tribology and Lubricants
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• v.13 no.3
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• pp.33-41
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• 1997

In this paper the linearized stiffness and damping coefficients of tilting pad thrust bearing are calculated by the perturbation method. The coefficients are obtained for a wide range of pivot positions. The effects of exciting frequency and pad mass on stiffness and damping coefficients are investigated. Critical frequencies due to the tilting motions of the pad are presented and are shown to be strongly influenced by the pivot position and the pad mass.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.96-102
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• 1998

The characteristics of roadbed are very important factors in the design of railways. Laboratory model tests were performed to investigate the effectiveness of geogrid placement in the subbase layers on reinforcement. Design parameters of reinforcement were determined through the laboratory model tests. The results indicated that geogrid reinforcement is increased the bearing capacity and reduced the settlement of railway foundation. The optimum length of geogrid reinforcement is about 4B. The effective depth of geogrid placement from the bottom of ballast is about 0.1B-0.2B depended on magnitude of applied load.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.4
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• pp.409-421
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• 2022

Achieving a highly resolved spatial distribution of Mn-bearing minerals and elements in the natural ferromanganese nodules can provide detailed knowledge of the temporal variations of geochemical conditions affecting the formation processes of nodules. While a recent study utilizing Raman spectroscopy has reported the changes in the manganate mineral phases with growth for spherical nodules from the Arctic Sea, the distributions of minerals and elements in the nodules from the shallow Arctic Sea with non-spherical forms have not yet fully elucidated. Here, we reported the micro-laser Raman spectra with varying data acquisition points along three different profiles from the center to the outermost rim of the non-spherical ferromanganese nodules collected from the East Siberian Sea (~73 m). The elemental distributions in the nodule (such as Mn, Fe, etc.) were also investigated by energy dispersive X-ray spectroscopy (EDS) analysis to observe the internal structure and mineralogical details. Based on the microscopic observation, the internal structures of a non-spherical nodule can be divided into three different regions, which are sediment-rich core, iron-rich substrate, and Mn-Fe layers. The Raman results show that the Mn-bearing mineral phases vary with the data acquisition points in the Mn-Fe layer, suggesting the changes in the geochemical conditions during nodule formation. In addition, we also observe that the mineral composition and structural characteristics depend on the profile direction from the core to the rim. Particularly, the Raman spectra obtained along one profile show the lack of Fe-(oxy)hydroxides and the noticeably high crystallinity of Mn-bearing minerals such as birnessite and todorokite. On the other hand, the spectra obtained along the other two profiles present the presence of significant amount of amorphous or poorly-ordered Fe-bearing minerals and the low crystallinity of Mn-bearing minerals. These results suggest that the diagenetic conditions varied with the different growth directions. We also observed the presence of halite in several layers in the nodule, which can be evidence of the alteration of seawater after nodule formation. The current results can provide the opportunity to obtain detailed knowledge of the formation process and geochemical environments recorded in the natural non-spherical ferromanganese nodule.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.601-609
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• 2021

The fructification characteristics, fruit quality, and yield of the 'Hwangsil' jujube tree were analyzed at various stages of growth age (3-8 years old) to obtain basic data for developing high-quality jujube production technology. The average height, crown area, stem diameter near the root, stem clear length, the number of the main branches, and the distance between any two main branches were 230.8 cm (224.4~247.2 cm), 3.0 m² (2.1~3.8m²), 4.8 cm (2.4~6.2 cm), 69.1 cm (46.6~78.0 cm), 12.9 (8.6~19.6), and 8.1 cm (7.4~9.0 cm), respectively. Tree age was positively correlated with the crown area, stem diameter near the root, but stem clear length negatively correlated with the number of main branches. The average number of fruits per mother bearing shoot and tree was 20.0 (14.3~26.3) and 302.8 (257.3~373.5), respectively. There was no correlation between tree age and fructification characteristics, such as the number of fruit-bearing mother shoots per the main branch, the number of fruit-bearing shoots per fruit-bearing mother shoot, and the number of fruits per fruit-bearing shoot. Since the shape of the jujube tree is constantly managed based onthe growing area and type of greenhouse where the tree grown. The average fruit weight, fruit hardness, and soluble solid content were 24.2 g (22.4~26.8 g), 28.4 N (27.3~30.0 N), and 19.0% (17.1~19.8%), respectively, with no correlation between the tree age and fruit quality. The average yield was 7.4 kg per tree (5.7~9.1 kg), with significantly high quantities were produced in six and seven years old trees.