• Fire Science and Engineering
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• v.13 no.1
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• pp.37-47
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• 1999

The spreading fire of very small floating particles after they are ignited is fast and t therefore dangerous. The research on this area has been limited to experiments and global simulations which treat them as dusts or gaseous fuel with certain concentration well m mixed with air. This research attempted micro-scale analysis of ignition of those particles modeling them as liquid droplets. For the beginning, the in-line array of fuel droplets is modeled by two-dimensional, unsteady conservation equations for mass, momentum, energy and species transport in the gas phase and an unsteady energy equation in the liquid phase. They are solved numerically in a generalized non-orthogonal coordinate. The single step chemical reaction with reaction rate controlled by Arrhenius’ law is assumed to a assess chemical reaction numerically. The calculated results show the variation of temperature and the concentration profile with time during evaporation and ignition process. Surrounding oxygen starts to mix with evaporating fuel vapor from the droplet. When the ignition condition is met, the exothermic reactions of the premixed gas initiate a and burn intensely. The maximum temperature position gradually approaches the droplet surface and maximum temperature increases rapidly following the ignition. The fuel and oxygen concentration distributions have minimum points near the peak temperature position. Therefore the moment of ignition seems to have a premixed-flame aspect. After this very short transient period minimum points are observed in the oxygen and fuel d distributions and the diffusion flame is established. The distance between droplets is an important parameter. Starting from far-away apart, when the distance between droplets decreases, the ignition-delay time decreases meaning faster ignition. When they are close and after the ignition, the maximum temperature moves away from the center line of the in-line array. It means that the oxygen at the center line is consumed rapidly and further supply is blocked by the flame. The study helped the understanding of the ignition of d droplet array and opened the possibility of further research.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.4
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• pp.31-41
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• 1997

This paper describes a potential-based panel method formulated for the prediction of the steady performance of a waterjet propulsor. The method employs normal dipoles and sources distributed on the solid surfaces such as the impeller/stator blades, hub and duct, and normal dipoles in the shed wakes trailing the impeller and stator to represent the potential flow around the waterjet propulsor. To define a closed boundary surface, the inlet and outlet open boundary surfaces are introduced where the sources and dipoles are distributed. The kinematic boundary condition on the solid boundary surface is satisfied by requiring that the normal component of the total velocity should vanish. On the inlet surface, the total inflow flux into the duct is specified, and on the outlet surface the conservation of mass principle is applied to evaluate the source strength. The solid surfaces are discretized into a set of quadrilateral panel elements and the strengths of sources and dipoles are assumed constant at each panel. Applying this approximation to the boundary conditions leads to a set of simultaneous equations. Systematic numerical tests show that the present numerical method is fast and stable. In order to validate the present method, sample computations are carried out first for the case of a conventional axial flow fan which has a similar geometry as the waterjet propulsor, and then for the case of a waterjet propulsor on which experiments are carried out at KRISO(Korea Research Institute of Ships and Ocean Engineering).

• Journal of the Korean Chemical Society
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• v.51 no.6
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• pp.569-576
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• 2007

In this study, the effect of grouping by communication apprehension level in paired think-aloud problem solving was examined. Three classes of 9th graders (N=99) were randomly assigned to a control group, homogeneous group or heterogeneous group based on the test scores of their communication apprehension. After the instructions concerning ‘writing balanced chemical equation', ‘the law of conservation of mass', and ‘the law of definite proportions' for 7 class hours, students' chemistry problem solving ability and the perception to the paired think-aloud problem solving were examined. Two-way ANOVA results revealed that there was an interactive effect in the score of chemistry problem solving ability test. In simple effect test for the students of low communication apprehension, the scores of the heterogeneous group were found to be significantly higher than those of the control group. However, the students in homogeneous group had relatively positive perceptions to the paired think-aloud problem solving.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.933-940
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• 2009

To evaluate characteristics in spray flame, laminar counterflow is investigated on the effects of equivalence ratio and fuel by a two-dimensional DNS (direct numerical simulation). For the gaseous phase, Eulerian mass, momentum, energy, and species conservation equations are solved. For the disperse phase, all individual droplets are calculated by the Lagrangian method without the parcel model. n-Decane ($C_{10}H_{22}$) and n-heptane ($C_7H_{16}$) is used as a liquid spray fuel, and a one-step global reaction is employed for the combustion reaction model. As equivalence ratio increases, the fuel ignites early and the high temperature region spreads wider. The peak value of temperature, however, tends to once increase and then decreases with increasing equivalence ratio. The decrease in the peak value of temperature for the higher equivalence ratio condition is caused by the cooling effect associated with droplet group combustion. Since the evaporation of n-heptane is early, the high temperature region spreads wider than ndecane, but the peak values of temperature for both n-heptane and n-decane is almost same.

• Korean Journal of Plant Resources
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• v.30 no.4
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• pp.372-377
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• 2017

This research was performed to develop mass propagation method of Alpine modest primrose (Primula modesta var. hannasanensis T.Yamaz.) for improving the conservation and utilization of the species. Seeds were collected on August 2011 in Jeju-city and well-selected seeds were dry-stored at $4{\pm}1.0^{\circ}C$. Seed size ranged $0.44{\pm}0.07{\times}0.61{\pm}0.04mm$, and weight of 1,000 seeds was $51.78{\pm}0.021mg$. Thus the seed was classified as 'dwarf seeds'. As the result of dormancy characteristics, moisture content of freshly matured seeds increased rapidly by water-soaking treatment and seeds did not germinate at $20^{\circ}C$ for 4 weeks under the light condition. Therefore, seeds were estimated to have physiological dormancy. Germination conditions of dry-stored seeds were found to be $20^{\circ}C$ and light condition, and seeds did not germinated under dark condition regardless of all temperature regimes. Therefore, Alpine modest primrose seed was considered as photoblastic type. Percent germination (PG) and germination energy (GE) were greatly improved by soaking the seeds in $GA_3$ and kinetin for 24 hours. Especially, 200~500 mg/L $GA_3$ treatment resulted in the highest PG (95.5%) and GE (98.3%). So, chemical treatment such as $GA_3$ was thought to be a useful method for raising seedling uniformly.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.2
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• pp.136-150
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• 2002

To improve the water quality of the recently constructed Siwhaho, sluice gates were operated to allow free exchange of water with the sea. This estuarine lake connected to the outer sea through narrow gates is affected mainly by flushing by gate operation and river flows and wind forcing sometimes. As a predicting tool far the water qualities, a three-dimensional finite volume model CE-QUAL-ICM is incorporated into a finite element hydrodynamic model, TIDE3D. In coupling these two different modules, a new error minimization technique is applied by considering conservation of mass. Model tests for one year after calibration and validation using field observation show that eutrophication and other biological changes reach quasi-steady state after initial 60 days of simulation, thus it would be necessary to consider moderate ramp up option to remove initial uncertainties due to cold start option. Sediment-water interaction might not be a concern in the long-term simulation, since its effect is negligible. Simulated results show the newly applied scheme can be applied with satisfaction not only fur lessening of eutrophic processes in an estuarine lake but also looking for some active circulation to improve water quality.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.233-246
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• 2009

The partitioning of evapotranspiration (ET) into evaporation (E) and transpiration (T) is critical in understanding the water cycle and the couplings between the cycles of energy, water, and carbon. In forests, the total ET measured above the canopy consists of T from both overstory and understory vegetation, and E from soil and the intercepted precipitation. To quantify their relative contributions, we have measured ET from the floors of deciduous and coniferous forests in Gwangneung using eddy covariance technique from 1 June 2008 to 31 May 2009. Due to smaller eddies that contribute to turbulent transfer near the ground, we performed a spectrum analysis and found that the errors associated with sensor separation were <10%. The annual sum of the understory ET was 59 mm (16% of total ET) in the deciduous forest and 43 mm (~7%) in the coniferous forest. Overall, the understory ET was not negligible except during the summer season when the plant area index was near its maximum. In both forest canopies, the decoupling factor ($\Omega$) was about ~0.15, indicating that the understory ET was controlled mainly by vapor pressure deficit and soil moisture content. The differences in the understory ET between the two forest canopies were due to different environmental conditions within the canopies, particularly the contrasting air humidity and soil water content. The non-negligible understory ET in the Gwangneung forests suggests that the dual source or multi-level models are required for the interpretation and modeling of surface exchange of mass and energy in these forests.

• Journal of Plant Biotechnology
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• v.40 no.2
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• pp.65-71
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• 2013

Lilium cernum Komarvo. is an important endangered plant belonging to the family Liliaceae. A method was developed for the rapid micropropagation of L. cernum through plant regeneration from bulb scales explant-derived calli. The bulb scales segments were cultured on Murashige and Skoog (MS) medium supplemented with 0, 0.5, 1.0, $3.0mg{\cdot}L^{-1}$ kinetin and 0, 0.1, 0.5, $1.0mg{\cdot}L^{-1}$ NAA or 2,4-D for callus induction. In media with $0.5{\sim}3.0mg{\cdot}L^{-1}$ kinetin and $0.1{\sim}1.0mg{\cdot}L^{-1}$ NAA and 2,4-D, 95~100% of explants produced callus. They were then transferred to MS medium supplemented with various concentrations of NAA (0, 0.01, 0.05 and $1.0mg{\cdot}L^{-1}$) in combination with BA (0, 1.0 and $2.0mg{\cdot}L^{-1}$) for bulbet formation. Bulbet induction (78%), weight (468 mg) and size (15.5 mm) were obtained the highest on MS medium containing $2.0mg{\cdot}L^{-1}$ BA and $1.0mg{\cdot}L^{-1}$ NAA. In vitro frequency of plant regeneration was not significantly treated in strength of MS and sucrose concentration. Chlorophyll contents in 1/2MS with $50g{\cdot}L^{-1}$ sucrose treatments were higher than those in control and another treatment. This in vitro propagation protocol will be useful for conservation and mass propagation of this endangered plant.

• Molecules and Cells
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• v.38 no.8
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• pp.685-696
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• 2015

Rice is a model plant widely used for basic and applied research programs. Plant cell wall proteins play key roles in a broad range of biological processes. However, presently, knowledge on the rice cell wall proteome is rudimentary in nature. In the present study, the tightly-bound cell wall proteome of rice callus cultured cells using sequential extraction protocols was developed using mass spectrometry and bioinformatics methods, leading to the identification of 1568 candidate proteins. Based on bioinformatics analyses, 389 classical rice cell wall proteins, possessing a signal peptide, and 334 putative non-classical cell wall proteins, lacking a signal peptide, were identified. By combining previously established rice cell wall protein databases with current data for the classical rice cell wall proteins, a comprehensive rice cell wall proteome, comprised of 496 proteins, was constructed. A comparative analysis of the rice and Arabidopsis cell wall proteomes revealed a high level of homology, suggesting a predominant conservation between monocot and eudicot cell wall proteins. This study importantly increased information on cell wall proteins, which serves for future functional analyses of these identified rice cell wall proteins.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.6
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• pp.155-164
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• 2023

Sedirea japonica is one of the critically endangered species in South Korea mostly due to artificial harms such as illegal collection and habitat destruction. Therefore, artificial propagation through improving germination rate, increasing growth, and controlling flowering is meaningful for the conservation and reintroduction of S. japonica. It is suggested that cytokinins are one of the multi-factors that contribute to plant growth and floral responses. Especially, exogenous cytokinins have been known to induce or promote shoot growth or earlier flowering in orchids. Therefore, it was investigated how the application of 6-benzylaminopurine (BA) influenced the growth and inflorescence of S. japonica. A foliar spray containing BA at 100, 200, 300, and 400 ppm was applied from 1st July to 30th December 2021. Leaf length, leaf length growth rate, leaf width, and width and length ratio were measured as growth-related factors. Visible inflorescence rate, inflorescence length, the number of flowers per inflorescence, and the distance between the stalks were measured as flowering-related factors. Growth-related factors except for leaf growth rate were not affected by BA treatments, while leaf growth rate was significantly increased by 200 ppm of BA treatment. The visible inflorescence rate increased by 200 ppm of BA treatment, and there seems an optimal concentration and threshold of BA treatment. An iterative experiment with more seedlings and measurement factors would be helpful to figure out the effects of exogenous BA treatment on S. japonica, and it can be applied for mass propagation.