• Korean Journal of Plant Resources
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• v.18 no.1
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• pp.186-193
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• 2005

This study was conducted to clarify the effects of different natural mordants and mordanting methods on the dyeing degree of silk using extracts from Coreopsis drummondii. Surface colors were shown as an order of descent Y in control, and an order of descent Y and YR treated by mordants. Extracts from Coreopsis drummondii was sufficient for the natural dyestuffs. $10\%,\;20\%\;and\;30\%$ mordants made from lime-juice of Camellia japonica, oyster shells. and Symplocos chinensis (Lour) Druce for. pilosa (Nakai) Ohwi were used for the dyeing of silk. Surface color of silk was not affected by the concentration of mordants and mordanting methods, however, $20\%$ mordant was suitable for the dye coloring. It was shown that dye coloring concentrations were highly in the order of mordanting later > mordanting ahead > co-mordanting, and so on. Silks were naturally dyed by the extracts from Coreopsis drummondii, and twenty-nine kinds of natural mordants were treated and screened. Surface color of silk was shown as an order of descent YR treated by the mordants made from the lime-juice of Camellia japonica and Eurya japonica, and as an order of descent Y by the other mordants. By the treatment of natural mordants, concentrations of dye coloring were significantly increased compared with control (none-mordanting), and the potentials as a natural mordant for the effective dye coloring was sufficiently ascertained.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.2
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• pp.130-135
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• 2015

Recently, as a result of the application of large and multi-blade propellers with high efficiency for large vessels, the vertical bending stiffness of propulsion shafting system tends to be declined. For some specific vessels, the shaft arrangement leads to the forward stern tube bearing to be omitted, decreasing vertical bending stiffness. In this respect, decreased vertical bending stiffness causes the problem which is the blade order resonance frequency to be placed within the operational rpm range of propulsion shafting system. To verify whirling vibration, the measurement should be carried out covering from operating rpm up to target rpm, however, the range is un-measurable generally. In order to resolve the measurement issue, this study shows the measuring method and the assessment method of relevant natural frequency of whiling vibration by using measured harmonic order component of whirling vibration.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.2
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• pp.173-183
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• 2021

Objectives: This study evaluated the skin permeability of lawsone in henna hair dyes to understand the exposure characteristics of henna hair dyes in the human body. It examined the protective effects of protectants by applying protectants A, B, and C to test skin. Methods: Skin absorption tests were conducted using Franz diffusion cells according to OECD test guideline 428. After applying one kind of natural henna hair dye and chemical henna hair dye, respectively, to a standardized pig skin model, samples of receptor fluid were collected at 1h, 3h, 6h, and 24h. The skin permeation of lawsone was determined using HPLC. After the skin absorption experiment, the skin to which hair dye was applied was analyzed to determine the residual amount of lawsone in the skin. Results: The cumulative permeation of both natural and chemical henna hair dyes increased over time, and the natural henna hair dye had a flux value (t=3.194, p<.05) high both in the K_p value (t=3.207, p<.05) and the residual amount (t=22.701, p<.001). For skin treated with a protectant, the cumulative permeation of natural henna hair dye 24h control and the cumulative permeation of protectant A, B, and C increased over time. Flux and K_p values were in the order control > protectant A > protectant C > protectant B. The residual amount (F=4.469, p<.05) was in the order of protectant C > protectant A > protectant B > control. At 3h, the dye application time of natural henna hair dye, the lawsone flux value (F=4.454, p<.05) and K_p value (F=4.455, p<.05) were higher in the control group than in the protectant groups. The 24h cumulative permeation of the chemical henna hair dye increased with time in both the control and the protectant groups, and the flux and K_p values were in the order of protectant A > protectant C > protectant B > control. The residual amount (F=7.901, p<.01) was in the order of protectant B > protectant A> protectant C > control. Conclusions: Within the normal dyeing time for henna hair dye (three hours for natural henna hair dyes and 30 minutes for chemical henna hair dyes) lawsone skin penetration was not observed even when no protective agent was applied. After that time, however, evidence of skin penetration and retention of lawsone and the protective effect of protective agents were observed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5199-5206
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• 2010

In this paper, we investigate the buckling analysis of laminated composite plates, using a improved assumed natural strain shell element. In order to overcome membrane and shear locking phenomena, the assumed natural strain method is used. The eigenvalues of the laminated composite plates are calculated by varying the width-thickness ratio and angle of fiber. To improve an shell element for buckling analysis, the new combination of sampling points for assumed natural strain method was applied and the refined first-order shear deformation theory which allows the shear deformation without shear correction factor. In order to validate the present solutions, the reference solutions are used and discussed. The results of laminated composite plates under the in-plane shear loading may be the benchmark test for the buckling analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2284-2291
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• 2010

In this paper, we investigate the vibration analysis of plates, using an 8-node shell element that accounts for the transverse shear strains and rotary inertia. The forced vibration analysis of plates subjected to arbitrary loading is investigated. In order to overcome membrane and shear locking phenomena, the assumed natural strain method is used. To improve an 8-node shell element for forced vibration analysis, the new combination of sampling points for assumed natural strain method was applied. The refined first-order shear deformation theory based on Reissner-Mindlin theory which allows the shear deformation without shear correction factor and rotary inertia effect to be considered is adopted for development of 8-node assumed strain shell element. In order to validate the finite element numerical solutions, the reference solutions of plates are presented. Results of the present theory show good agreement with the reference solution. In addition the effect of damping is investigated on the forced vibration analysis of plates.

• Journal of Technologic Dentistry
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• v.31 no.3
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• pp.47-58
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• 2009

Self-leadership means a person's ability to make his thought or behavior in a right way by controlling it himself. Strategies of the same leadership can be largely categorized into three, behavior focused, natural reward and constructive thought strategies. In this study, the foresaid styles of self-leadership strategy are discussed from the perspective of dental lab laboratories' business environment of Gyeongnam region. And accordingly, this researcher examined such strategy styles that dental lab managers, chief technicians and assistant technicians usually have. Results of the study can be summarized as follows. First, out of the self-leadership strategy styles, most remarkably found among the professional of dental technology was constructive thought strategy, followed by behavior-focused and natural reward strategies in order. In general, therefore, the professionals strongly tend to make their thoughts that can a positive effect on their work performance or in a constructive way. In other words, professional dental technicians are more likely to make efforts to persuade or persuade themselves to change their own unreasonable confidence or negative process in more positive way. Second, the extent to which constructive thought strategy is perceived was not different among dental lab managers, chief technicians and assistant technicians. While, behavior-focused and natural reward strategies were found most strongly perceived by dental lab managers, followed by chief and assistant technicians in order. This may be attributed to the fact that the higher professional dental technicians are in position, the higher they are in self-leadership, or in the ability to overcome crises by themselves and make their thought or behavior in a right way. Dental lab managers usually have lots of experiences in relation to behavior-focused or natural reward strategy. Therefore, they are very strongly capable of controlling themselves in order to overcome crises or make their thought or behavior in a right way. In contrast, assistant technicians are still having lots of trials and errors because they are less experienced and skilled. This suggests that chief technicians should make themselves fully capable as a medium that connects between dental lab managers and assistant technicians.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1579-1582
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• 2009

The reaction rates of 4-X-2,6-dinitrochlorobenzenes (X = $NO_2,\;CN,\;CF_3$) with Y-substituted pyridines (Y = 3-$OCH_3,\;H,\;3-CH_3,\;4-CH_3$) in methanol-acetonitrile mixtures were measured by conductometry at 25 ${^{\circ}C}$. It was observed that the rate constant increased in the order of X = 4-$NO_2\;>\;4-CN\;>\;4-CF_3$ and the rate constant also increased in the order of Y = 4-$CH_3\;>\;3-CH_3\;>\;H\;>\;3-OCH_3$. When the solvent composition was varied, the rate constant increased in order of MeCN > 50% MeOH > MeOH. The electrophilic catalysis by methanol may be ascribed to the formation of hydrogen bonds between alcoholic hydrogen and nitrogen of pyridines in ground state. Based on the transition parameters, ${\rho}_S,\;{\rho}_N,\;{\beta}_Y,\;{\rho}_{XY}$ and solvent effects, the reaction seems to proceed via $S_N$Ar-Ad.E mechanism. We also estimated the isokinetic solvent mixtures (${\rho}_{XY}$ = 0) based on cross-interaction constants, where the substituent effects of the substrate and nucleophile are compensated.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.71-74
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• 2002

A higher-order zig-zag theory is developed to refine the predictions of natural frequency and mode shape of laminated composite plates with multiple delaminations. By imposing top and bottom surface transverse shear stress-free and interface continuity conditions of transverse shear stresses including delaminated interfaces, the displacement field with minimal degree-of-freedoms are obtained. This displacement field can systematically handle the number, shape, size, and locations of delaminations. Through the dynamic version of variational approach, the dynamic equilibriums and variationally consistent boundary conditions are obtained. Through the numerical example of natural frequency analysis, the accuracy and efficiency of present theory are demonstrated. The present theory is suitable as an efficient tool to analyze the static and dynamic behavior of the composite plates with multiple delaminations.

• Structural Engineering and Mechanics
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• v.52 no.4
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• pp.687-699
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• 2014

Based on the energy method considering the second order effects, the natural frequencies of externally prestressed simply supported beam and the compression softening effect of external prestress force were analyzed. It is concluded that the compression softening effect depends on the loss of external tendon eccentricity. As the number of deviators increases from zero to a large number, the compression softening effect of external prestress force decreases from the effect of axial compression to almost zero, which is consistent with the conclusion mathematically rigorously proven. The frequencies calculated by the energy method conform well to the frequencies by FEM which can simulate the frictionless slide between the external tendon and deviator, the accuracy of the energy method is validated. The calculation results show that the compression softening effect of external prestress force is negligible for the beam with 2 or more deviators due to slight loss of external tendon eccentricity. As the eccentricity and area of tendon increase, the first natural frequency of the simply supported beams noticeably increases, however the effect of the external tendon on other frequencies is negligible.

• Korean Institute of Interior Design Journal
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• no.41
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• pp.236-245
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• 2003

Environment friendly architecture, which will reduce shortcomings of current architectural culture, can be achieved by using natural energy and environment friendly building materials together with their environmental architecture techniques. Particularly, even though the overall building system is perfect, it cannot be considered as comfortable architectural space if the materials are polluted, harmful to human bodies and producing wastes. Therefore, in order to build environment friendly architecture, the selection of the materials is very important and necessary from the planning stage with careful reviews and concern. This study tries to define what the environment friendly materials we, to investigate and to classify them, in order to provide some guidelines for selecting them at plans to build. For examples, the materials can be classified into natural materials, continuously usable materials, recycled materials from wastes, and less polluting materials mixed with natural materials. Finally, this study reviews the existing products in the market and proposes to develop new ones in the future. It will present the circulation of resources in the 21century through recycled and reused materials.