• Journal of the Korean institute of surface engineering
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• v.44 no.5
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• pp.226-231
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• 2011

Graphene was coated on STS 316L by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite (graphene) was made of the graphite by chemical treatment. Graphene is distributed using dispersing agent, and STS 316L was coated with diffuse graphene solution by electro spray coating method. The structure of the exfoliated graphite was analyzed using XRD and the coating layer of surface was analyzed by using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed into fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3~5 ${\mu}m$ thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the PEM fuel cell stack inside. And interfacial contact resistance test was measured to simulate the internal operating conditions of PEM fuel cell stack. The results of measurements show that stainless steel coated with graphene was improved in corrosion resistance and surface contact resistance than stainless steel without graphene coating layer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.237-243
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• 2010

In this study, the effect of the shape of a pintle(obstacle) on thrust-modulation performance and drag in a pintle rocket was investigated by a cold flow test and by computational fluid dynamics. Pintle movement caused a monotonic increase in the chamber pressure. Thrust generated by the pressure distribution on the pintle body was linearly changed to the chamber pressure, and this thrust was greater than that generated by the nozzle-wall pressure distribution. Because the shock pattern in the nozzle changes with the shape of the pintle body and pressure ratio, the thrust generated by the nozzle-wall pressure is not directly affected by chamber pressure. The drag due to the pintle(obstacle) can be minimized for a fully linear pintle shape, regardless of chamber pressure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.519-526
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• 2009

This paper describes a research result of a external shape optimization study to maximize the range of the guided missile with canards and tailfins in atmospheric flight. For this purpose, the external shape optimization program which can enhance the range of a missile was developed, incorporated with the trajectory analysis and the optimization technique. In the trajectory analysis part, Missile DATCOM which utilizes the semi-empirical method was directly connected to the trajectory code to supply the aerodynamic coefficients efficiently at every time step. In the gliding flight trajectory after apogee, a maximum $C_L/C_D$ trim condition calculation module was attached under the assumption of the missile continuously flying at maximum $C_L/C_D$ condition. In the optimization part, a Response Surface Method(RSM) was adopted to reduce the computing time.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.8
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• pp.3-14
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• 2019

The research is to track the morphological transformation of residential towers of apartment complexes in Busan. Though apartment is one of the most important components in Korean society, it has not drawn enough attention from academia as well as the public, especially regarding its shape. In result, its morphological change has barely been recognized. Instead, negative, but superficial, evaluation has become dominant tendency to deal with the shape of apartment tower. There are numerous 'partial' evidences to inform the morphological change of apartment plan type, and understanding the change is critical since morphological resultant reflects culture, politics, economy of a society. The research has been done on the 261 apartment complexes built through 2016 in Busan. The analysis shows that $I^0$ type, to represent 'typical boring architectural shape' of Korean apartments, has been dominant until the year 2000. However, its portion has become drastically decreased since the mid-2000. Composite plan type, the geometrical precedents of which had never been existent, emerged in the mid-2000, and this phenomenon may symbolize the change of morphology of apartment. When tower plan types are grouped together according to geometrical shape, three types, I-type, L-type and Y-type, take the most of residential towers, explaining 97% of the total. As expected, I-type is the most dominant, but its influence has decreased as time passes. Y-type might become one of the most important type in the period V. L-type has become the leading type in the Period VI to exceed I-type by 12 percent.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.1029-1036
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• 2014

Several types of automatic 3D scanners are available for use in the 3D scanning industry, e.g., an automatic 3D scanner that uses a robot arm and one that uses an automatic rotary table. Specifically, these scanners are used to obtain a 3D shape using automatic assisting devices. Most of these scanners are required to perform numerous operations, such as merging, aligning, trimming, and filling holes. We are interested in developing an automatic 3D shape collection device using a spherical-coordinate-based guiding system. Then, the aim of the present study is to design an automatic guiding system that can automatically collect 3D shape data. We develop a 3D model of this system and measuring data which are collected by a personal computer. An optimal design of this system and the geometrical accuracy of the measured data are both evaluated using 3D modeling software. The developed system is then applied to an object having a highly complex shape and manifold sections. Our simulation results demonstrate that the developed system collects higher-quality 3D data than the conventional method.

• Korean Journal of Agricultural Science
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• v.46 no.4
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• pp.1007-1018
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• 2019

In the present study, according to morphological observations followed by recent circumscriptions, we have classified the Korean taxa of the family Linderniaceae into Scrophulariaceae sensu lato has been considered in several works, though the taxa have remained undefined because identification work was mostly done according to vegetative morphological features, such as the leaf shape, leaf margins, and leaf venation. The taxa of Linderniaceae are mostly considered to be weeds and, for correct identification, it is necessary to clarify their taxonomic characteristics. Morphological studies were carried out using samples collected in the field. Micro-morphological observations of the vegetative and floral parts were also performed using light microscopy (LM) and scanning electron microscopy (SEM). We concluded that important characteristics are reproductive morphologies viz. calyx, stamen structure, capsule shape, calyx ratio with capsule, inflorescence morphology, and seed morphology. As a result, we formulated taxa descriptions and provided a key of the genera of Linderniaceae in Korea. Lindernia crustacea (L.) F. Muell. is transferred to Torenia crustacea (L.) Cham. & Schltdl. Lindernia micrantha D. Don and L. angustifolia (Benth.) Wettstein are a synonym of Vandellia micrantha (D. Don) Eb. Fisch., Schäferh. & Kai Müll. Lindernia attenuata Muhl. and L. dubia var. major (Pursh) Pennell are a synonym of Lindernia dubia (L.). Lindernia verbenifolia (Colsm.) Pennell is a synonym of Bonnaya antipoda Druce. Our study reports the presence of four genera: Bonnaya, Lindernia, Torenia, and Vandellia, comprising six taxa under the family Linderniaceae in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.296-302
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• 2013

The effects of temperature on spore release, growth and photosynthetic efficiency of Lithophyllum yessoense and Hildenbrandia rubra were examined. L. yessoense was collected at Galnam and H. rubra was collected at Gyeokpo, Korea. The experimental temperatures were different for spore release (10, 15, $20^{\circ}C$), sporeling growth (10, 15, 20, 25, $30^{\circ}C$) and photosynthetic efficiency (10, 15, 20, $25^{\circ}C$). All other culture conditions were the same: 34 psu, 12:12 LD and $50{\mu}mol$ photon $m^{-2}s^{-1}$. Spore liberation was maximal at $10^{\circ}C$ for L. yessoense and at $20^{\circ}C$ for H. rubra. After 14 days, the surface area of L. yessoense was 0.031 $mm^2$ at $25^{\circ}C$ and for H. rubra was 0.032 $mm^2$ at $20^{\circ}C$. Sporelings of L. yessoense were a dark-red color and grew in a round shape. In contrast, H. rubra was bright pink and changed from a round shape in the early growth stage to later become flabelliform. Photosynthetic efficiency was highest between $20-25^{\circ}C$ in both species. In conclusion, L. yessoense and H. rubra display different physiological features based on the optimal temperatures for spore release and sporling growth.

• Korea-Australia Rheology Journal
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• v.15 no.4
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• pp.197-208
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• 2003

Two measures of distributive mixing are examined: the standard deviation $\sigma$ and the maximum error E, among average concentrations of finite-sized samples. Curves of E versus sample size L are easily interpreted in terms of the size and intensity of the worst flaw in the mixture. E(L) is sensitive to the size of this flaw, regardless of the overall size of the mixture. The measures are used to study distributive mixing for time-periodic flows in a rectangular cavity, using the mapping method. Globally chaotic flows display a well-defined asymptotic behavior: E and $\sigma$ decrease exponentially with time, and the curves of E(L) and $\sigma$ (L) achieve a self-similar shape. This behavior is independent of the initial configuration of the fluids. Flows with large islands do not show self-similarity, and the final mixing result is strongly dependent on the initial fluid configuration.

• Steel and Composite Structures
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• v.21 no.1
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• pp.217-247
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• 2016

Five extended cylindrical reticulated shells are proposed by changing distribution rule of diagonal rods based on three fundamental types. Modeling programs for fundamental types and extended types of cylindrical reticulated shell are compiled by using the ANSYS Parametric Design Language (APDL). On this basis, conditional formulas are derived when the grid shape of cylindrical reticulated shells is equilateral triangle. Internal force analysis of cylindrical reticulated shells is carried out. The variation and distribution regularities of maximum displacement and stress are studied. A shape optimization program is proposed by adopting the sequence two-stage algorithm (RDQA) in FORTRAN environment based on the characteristics of cylindrical reticulated shells and the ideas of discrete variable optimization design. Shape optimization is achieved by considering the objective function of the minimum total steel consumption, global and locality constraints. The shape optimization for three fundamental types and five extended types is calculated with the span of 30 m~80 m and rise-span ratio of 1/7~1/3. The variations of the total steel consumption along with the span and rise-span ratio are analyzed with contrast to the results of shape optimization. The optimal combination of main design parameters for five extended cylindrical reticulated shells is investigated. The total steel consumption affected by distribution rule of diagonal rods is discussed. The results show that: (1) Parametric modeling method is simple, efficient and practical, which can quickly generate different types of cylindrical reticulated shells. (2) The mechanical properties of five extended cylindrical reticulated shells are better than their fundamental types. (3) The total steel consumption of cylindrical reticulated shells is optimized to be the least when rise-span ratio is 1/6. (4) The extended type of three-way grid cylindrical reticulated shell should be preferentially adopted in practical engineering. (5) The grid shape of reticulated shells should be designed to equilateral triangle as much as possible because of its reasonable stress and the lowest total steel consumption.

• Fashion & Textile Research Journal
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• v.11 no.1
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• pp.103-111
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• 2009

This study is to help make-up and coordination for image-making after analysis of facial color and shape of elderly women. The data was analyzed 55-75 years old 212 elderly women's face color and pictures by means of SPSS 12.0 statistics package. On the basis of the colorimetric data on face by Minolta CM2500D, this research considered the analysis of facial color, patternization of facial color and its analysis by age group; for the analysis of facial shape, this research patternized facial shape and analyzed its characteristic using both contour-based facial shape analysis and Kamata facial shape analysis. As for facial color, it was found that the lower age bracket has bright and reddish face, looking fine, while the higher age bracket has a conspicuously yellowish face, looking bad. The community of facial color is classified as 3 types and it was found out that the facial color of the subjects belonging to Type 3, whose L value is the largest, looked the brightest; the face of the subjects belonging to Type 2, whose a value is the largest, was much tinged with red, and the face of the subjects belonging to Type 1, whose b value is the largest were tinged with yellow. According to the analysis of facial shape, there appeared oval & long forms in the classification by contour, while there appeared a lot of downward-directed power and inner-directed power in the classification by Kamata, which is believed to reflect the phenomenon that their chin line becomes roundish and the facial length also tend to be longer due to aging.