• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.5 no.3
• /
• pp.261-268
• /
• 1995

In transforming $K_2Ti_4O_9$ whisker, synthesized by calcination and slow cooling method, into $K_2Ti_6O_{13}$ whisker with boiling water and hydrochrolic acid, the effect of their treatment time and concentration on phase transformation, surface state and scattering of whisker was examined. The result was that the surface state of whisker was improved and whisker with a small diameter and a considerable aspect ratio was obtained by inducing scattering of a bundle of whisker. The treatment by boiling water and hydrochrolic acid induced the phase transformation of $K_2Ti_4O_9$ into $K_2Ti_6O_{13}$ and the phase transformation proceeded by extration of $K^+$ ion.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.8 no.1
• /
• pp.15-22
• /
• 1990

The purpose of this study is to suggest possibility to analyze the three-dimensional positions of the whole surface of an object simultaneously and precisely by close-range photogrammetry. For this purpose, the geometry of network, namely imaging geometry and control configuration etc was considered, and then the whole surface of the object was analyzed by bundle adjustment through forma. lion of strip and block with which cover the whole surface of the object. As a result, we were able to prove possibility of the whole surface analysis of an object and to extract characteristics of accuracies in accordance with the number and configuration of control points. Also as desirable accuracies were able to be acquired even by employing configuration of only a few control point stationed on a limited surface, it is expected that the difficulties of control surveying will be able to be reduced considerably.

• Bulletin of the Korean Mathematical Society
• /
• v.49 no.2
• /
• pp.307-317
• /
• 2012

We say (W, {${\phi}_1,\;{\ldots}\;,{\phi}_t$}) is a polarizable dynamical system of several morphisms if ${\phi}_i$ are endomorphisms on a projective variety W such that ${\otimes}{\phi}_i^*L$ is linearly equivalent to $L^{{\otimes}q}$ for some ample line bundle L on W and for some q > t. If q is a rational number, then we have the equidistribution of small points of given dynamical system because of Yuan's work [13]. As its application, we can build a polarizable dynamical system of an automorphism and its inverse on a K3 surface and can show that its periodic points are equidistributed.

• Journal of Sensor Science and Technology
• /
• v.29 no.6
• /
• pp.369-373
• /
• 2020

A hydrogen sensor was fabricated by utilizing a bundle of metal oxide nanostructures whose growth positions were selectively controlled by utilizing graphene, which is a carbon of atomic-unit thickness. To verify the reducing ability of graphene, it was confirmed that the multi-composition metal oxide V₂O₅ was converted into VO₂ on the graphene surface. Because of the role of graphene as a reducing catalyst, it was confirmed that ZnO and MoO₃ nanostructures were grown at high density only on the graphene surface. The fabricated gas sensor showed excellent sensitivity.

• Transactions of Materials Processing
• /
• v.13 no.7
• /
• pp.623-628
• /
• 2004

This paper is concerned with pressure welding, which has been known as a main bonding mechanism during the cold and warm forming such as clad extrusion or bundle extrusion/drawing. Bonding characteristics between the Cu and Al plates by pressure welding are investigated focusing on the weak bonding. Experiments are performed at the cold and warm temperatures ranging from the room temperature to $200^{\circ}C$. The important factors examined in this work are the welding pressure, pressure holding time, surface roughness, and temperature. A bonding map, which can identify the bonding criterion with a weak bonding strength of IMPa , is proposed in terms of welding pressure and surface roughness fur the cold and warm temperature ranges.

• Journal of the Korean Mathematical Society
• /
• v.49 no.4
• /
• pp.733-743
• /
• 2012

For the "Hopf bundle" $S^1{\rightarrow}S^{2n,1}{\rightarrow}\mathbb{C}H^n$, horizontal lifts of simple closed curves are studied. Let ${\gamma}$ be a piecewise smooth, simple closed curve on a complete totally geodesic surface $S$ in the base space. Then the holonomy displacement along ${\gamma}$ is given by $$V({\gamma})=e^{{\lambda}A({\gamma})i}$$ where $A({\gamma})$ is the area of the region on the surface $S$ surrounded by ${\gamma}$; ${\lambda}=1/2$ or 0 depending on whether $S$ is a complex submanifold or not. We also carry out a similar investigation for the complex Heisenberg group $\mathbb{R}{\rightarrow}\mathcal{H}^{2n+1}{\rightarrow}\mathbb{C}^n$.

• Korean Journal of Plant Taxonomy
• /
• v.53 no.2
• /
• pp.102-109
• /
• 2023

The basic information of ovule and seed characteristics was investigated for five monotypic and endemic genera in the Korean peninsula as categorized by the Flora of Korea category. The carpels and seeds were sectioned with a rotary microtome. Mature seeds were coated with platinum using an ion sputter and observed using a scanning electron microscope. As a result, Abeliophyllum was found to be anatropous and a unitegmic ovule, with a slightly colliculate seed surface and exotestal seed coat type. The ovule of Coreanomecon was anatropous and bitegmic, having a distinct echinate seed surface, and exo-endotestal seed coat type with a prismatic crystal in the mesotesta. The ovule of Hanabusaya was anatropous and a unitegmic, with a long reticulate seed surface sculpture, and distinct exotestal seed coat type. In addition, a wing developed at the opposite side of the raphe bundle. Megaleranthis was an anatropous and bitegmic ovule, having a small pentagonal disk shape, a concave seed surface and exotestal seed coat type. Finally, Pentactina was also anatropous and a unitegmic ovule, reticulate seed sculpture, and endotestal seed coat type. These data will be proving to be a source of good information for securing bio-sovereignty in the near future.

• Nuclear Engineering and Technology
• /
• v.26 no.3
• /
• pp.440-452
• /
• 1994

Nuclear fuel bundles are designed such that the heat flux at a-fuel pin surface should not exceed the critical heat flux (CHF) during normal operation and anticipated transient. Therefore, evaluation of the CHF for fuel bundle is demanded in an exact and reliable manner. One of the major concerns with the current application of CHF correlations is that the CHF based on circular tubes is applied to the fuel bundle subchannel analysis, mainly in terms of the hydraulic diameter with correction factors which may result in a source of possibly large uncertainties in CHF prediction. The hydraulic diameter does not recognize the local properties of fluid nor such effect as the surface curvature; the turbulence action on the convex surface is much more pronounced than that on the concave surface. Even for the tube having concave curvature, the effect of tube diameter on CHF becomes important with decreasing diameter. These facts imply that the convex curvature effect is significant and crucial to the reliable CHF prediction. This paper reviews and discusses analytical and experimental aspects of effect of transverse convex curvature in incompressible turbulent flow and heat transfer, and on CHF. Flow models to quantify this effect are briefly mentioned and future works are recommended.

• The Korea Journal of Herbology
• /
• v.22 no.1
• /
• pp.71-79
• /
• 2007

Objectives : This study was designed to establish a characteristic discrimination of internal and external morphological standard of original plants and herbal states in Polygoni Multiflori and Cynanchi Wilfordii Radix. Methods : In this studies, the external-internal morphological standards were determined by using stereoscope and butanol series. Results: 1. The external characteristics of original plants: Polygonum Multiflorum has alternate leaves, and its flower with white color blooms at the shoot apex or leaf axil. In the other hand, Cynanchum wilfordii has opposite leaves, and its flower with yellowish green color blooms at the leaf axil. 2. The physical characteristics of herbal slates: Polygoni Multiflori Radix is red-brown in outer surface pink-brown in section. In the other hand, Cynanchi Wilfordii Radix is earthly-brown in outer surface greyish white in section. 3. The physical characteristics according to the place of production: Demonstrable difference according to the place of production is not seen. Polygoni Multiflori Radix is brown or dark brown in outer surface, soft $Yellow{\sim}dark$ brown in section. In the other hand, Cynanchi Wilfordii Radix is white in outer surface, $white{\sim}weak$ red in section, and has power type. 4. The internal characteristics: Polygonum multiflorum has hetero-vascular bundle and lignification of cork layer is progressive. In the other hand, Cynanchum wilfordii has not hetero-vascular bundle, and lignification of cork layer is weak. Conclusion: In the future, many fundamental study such as how to discriminate between Polygoni Multiflori Radix and Cynanchi Wilfordii Radix in origin and efficacy will be necessary. Also the standard of discrimination must be specific and distinct in that several kinds of fo-ti has been traded. It is considered the results of this study will be furnish κ I the basis Lo succeeding studies and it is needed to extensive comparative study for the same genus-degree of relatedness.

• Fibers and Polymers
• /
• v.4 no.3
• /
• pp.124-128
• /
• 2003

Dark brown Alpaca fiber was reduced in shade via selective bleaching with peroxide. Two selective oxidative bleaching methods were tested on alpaca top to assess their effectiveness for color removal and fiber quality properties. Color change, bundle strength, weight loss, fiber diameter, surface modification, dye-ability and dye wash fastness were assessed for both methods and compared with the original brown top. Bleach method 1 (BL-I) showed little surface modification, 5.8% weight loss and 2.4% strength loss. D1925 yellowness index was reduced to 74.3 from 83.1 and provided a good base for the dyeing of medium to deep shades. Bleach method 2 (BL-II) displayed considerable surface modification, 7.8% weight loss and 18% strength loss. BL-II also resulted in a mean diameter reduction of 1.9 micron during bleaching. Yellowness was reduced to 64.5 from 83.1 and provided a very good base for the dyeing of medium to deep shades. BL-I showed better exhaustion of the premetallised dye Lanaset Violet B than BL-II. Wash fastness for BL-II was 1 grey scale unit poorer than BL-I. BL-II showed far better color clarity at pale depths however the wash fastness of the finished product was not good enough to maintain the depth or clarity of the color. BL-I showed poorer clarity of color but exhibited better wash fastness results.