• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.275-278
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• 2006

Systematic experiments in $CH_4/Air$ counterflow diffusion flames diluted with He have been undertaken to study the oscillatory instability in which lateral heat loss could be remarkable at low global strain rate. The oscillatory instability arises for Lewis numbers greater than unity and occurs near extinction condition. The dynamic behaviors of extinction in this configuration can be classified into three modes; growing, harmonic and decaying oscillation mode near extinction. As the global strain rate decreases, the amplitude of the oscillation becomes larger. This is caused by the increase of lateral heat loss which ran be confirmed by the reduction of lateral flame size. Oscillatory edge flame instabilities at low global strain rate are shown to be closely associated with not only Lewis number but also heat loss (radiation and lateral heat loss).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.5
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• pp.9-15
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• 2001

This paper describes measurement method of dielectric properties of dielectric materials using cylindrical cavity resonator's. Dielectric properties of concern here are relative permittivity, loss- tangent, quality factor and so on. An analysis of $TE_{011}$mode in dielectric properties of concentric dielectric-rod inserted cylindrical cavity resonator is presented. The frequency variation by the air gap at $TE_{011}$ mode turns out to be the least sensitive. A technique using a $TE_{011}$ mode of concentric dielectric-rod inserted cylindrical cavity resonator and an exact field representation of neo non-decaying mode are introduced for measurement of dielectric properties.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.279-282
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• 2006

Experiments in low strain rate methane-air counterflow diffusion flames diluted with $CO_2$ have been conducted to investigate the flame extinction behavior and edge flame oscillation The critical mole fraction at flame extinction is examined in terms of velocity ratio and global strain rate. Onset conditions of the edge flame oscillation and the relevant modes are also provided with global strain rate. It is observed that flame length is intimately relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation considerably. Edge flame oscillations are categorized into three: a growing-, a decaying-, and a harmonic-oscillation mode.

• Journal of Korean Society of Forest Science
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• v.105 no.1
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• pp.108-114
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• 2016

The effects of $SO_2$ treated pads ($SO_2$ 0, 0.5, 1, and 2 g/kg) on the quality of dried persimmons slices were investigated. The $SO_2$ treated pads for storage did not affect to weight, moisture loss rate, and soluble solid contents of dried persimmons slices. The color change after storage for 12 weeks was the highest (value = 3.5) in control ($SO_2$ 0 g/kg), whereas that was the lowest (value = 2.0) under $SO_2$ 2 g/kg condition. When we measured the browning degree after 12 weeks, they showed O.D. 0.24, 0.22, 0.20, and 1.7 in serial dilution treated pads with $SO_2$ 0, 0.5, 1, and 2 g/kg, respectively. The decaying rate was the highest (7.0%) in control after 12 weeks storage, whereas it did not show any spoilage in $SO_2$ 1 g/kg and 2 g/kg treated condition for whole storage period. The concentration of residual $SO_2$ in dried persimmons slices was detected within a safe range of 20.3~40.3 ppm. Therefore, the shelf-life of dried persimmons slices was lengthened in $SO_2$ treated pads (especially in $SO_2$ 2 g/kg) for inhibiting of browning and decaying.

• Journal of Korean Society of Forest Science
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• v.105 no.2
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• pp.202-207
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• 2016

The effects of $SO_2$ generating pads ($SO_2$ 0, 0.5, 1, and 2 g/kg) on the quality of dried persimmons slices were investigated. The $SO_2$ generating pads for storage did not affect to weight, moisture loss rate, and soluble solid contents of dried persimmons. The color change(E) after storage for 12 weeks was the highest (value = 3.5) in control ($SO_2$ 0 g/kg), whereas that was the lowest (value = 2.6) under $SO_2$ 2 g/kg condition. When we measured the browning degree after 12 weeks, they showed O.D. 0.15, 0.14, 0.10, and 0.05 in serial dilution treated pads with $SO_2$ 0, 0.5, 1, and 2 g/kg, respectively. The decaying rate was the highest (9.0%) in control after 12 weeks storage, whereas it did not show any spoilage in $SO_2$ 2 g/kg treated condition for whole storage period. The concentration of residual $SO_2$ in dried persimmons was detected within a safe range of 3.3~97.0 ppm. Therefore, the shelf-life of dried persimmons was lengthened in $SO_2$ generating pads (especially in $SO_2$ 2 g/kg) for inhibiting of browning and decaying.

• Journal of Korean Society of Forest Science
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• v.80 no.3
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• pp.311-316
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• 1991

Butt-rot fungi were isolated from decayed portion in butt rotted larch trees[Larix leptolepis(Sieb. et Zucc.) Gord.]. From a total of 216 affected trees in 38 forests of five provinces, Sparassis crispa(Wulf. ex Fr.) Fr. was isolated with the highest frequency, i.e.. 28% of the total trees. Laetiporus sulphureus(Fr.) Bond. et Sing, with 19%, and Phaeolus schweinitzii(Fr.) Pat. with 8%. However, none of these fungi was isolated from 45% of the trees. Wood decaying abilities and interaction of four basidiomycetous and three non-basidiomyo:etous fungi isolated from butt rotted trees were investigated. The weight loss of larch wood blocks, when exposed to the culture of a fungus for six months, was 19.6% for P. schweinitzii, 10% for S. crispa, 8.2% for L. sulphurous, 5.1% for Coriolus hirsutus, and less than 4.4% for three non-basidiomycetous fungi. In incubation with combinations of the fungi, the wood decay activity of S. crispa, L. sulphurous and C. hirsutus was increased by the non-basidiomycetous fungi of Geotrichum candidacy, G. sp. and Verticillium sp., but that of P. schweinitzii was not.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1185-1191
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• 1999

Radiation-induced oscillatory instability in diffusion flames is numerically investigated with nonlinear dynamics considered. As the simplest flame model, a diffusion flame established in the stagnant mixing layer is employed with optically thin gas-phase radiation and unity Lewis numbers for all species. Attention is focused on the radiation-induced extinction regime, which occurs at large $Damk\ddot{o}hler$ number. Once the steady flame structure is obtained for a prescribed value of the initial $Damk\ddot{o}hler$ number, transient solution of the flame is calculated after a finite amount of the $Damk\ddot{o}hler$-number perturbation is imposed on the steady flame. Transient evolution of the flame exhibits three types of flame-evolution behaviors, namely decaying oscillatory solution, diverging solution to extinction and stable limit-cycle solution. A dynamic extinction boundary is identified for laminar flamelet library.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.295-298
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• 2006

Experiments in methane-air low strain rate counterflow diffusion flames diluted with nitrogen have been conducted to study the behavior of flame extinction and edge flame oscillation in which lateral conduction heat loss in addition to radiative heat loss could be remarkable at low global strain rates. Onset conditions of edge flame oscillation and flame oscillation modes are also provided with global strain rate. It is seen that flame length is closely relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation. Edge flame oscillations in low strain rate flames are categorized into three: a growing oscillation mode, a decaying oscillation mode, and a harmonic oscillation mode. The regime of flame oscillation is also provided at low strain rate flames.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.476-482
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• 2001

This experiment was conducted to evaluate the effect of slow-release fertilizer application on quality elevation of onion (Allium cepa L.) in southwestern sea. The slow-release fertilizers used were NIAST (National Institute of Agricultural Science and Technology) I, II, CDU (Crotonylidene Diurea), UF (Urea-Formaldehydes), and IBDU (Isobutylidene Diurea) 30, 50. Growth of the onion plant treated with slow-release fertilizer showed better than the control. However, a rate of infected plant to downy mildew was low as compared with control. Chlorophyll and total nitrogen contents were high in control, whereas firmness, soluble solid content, number and thickness of scaly leaves were high in slow-release fertilizer plot. In early maturing onion, total marketable bulb yield was higher in slow-release fertilizer plot than all other fertilizer treatments. Total marketable bulb yield in late maturing onion treated with slow-release fertilizer was slightly decreased. Decaying loss and the rate of sprouting during storage period decreased in slow-release fertilizer application. In summary, application of slow-release fertilizer increased marketable yield, storability after harvest and also reduced labor needs for top dressing.

• Journal of the Korean Wood Science and Technology
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• v.49 no.3
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• pp.234-253
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• 2021

The Quercus mongolica has a high utilization value in industrial economic sector. The species is distributed throughout Korea, however, the damage caused by deterioration such as discoloration and decay is severe. For this reason, the deterioration of Q. mongolica is an obstacle to its use as wood, but research on deterioration factors is insufficient. In this study, we focused on fungi as a factor influencing the deterioration of Q. mongolica, and isolated and identified the fungi from the deteriorated Q. mongolica. In additions, in order to confirm whether the identified fungi actually affects wood deterioration, enzyme activities of the identified fungi were evaluated and related mass loss of wood treated with the fungi was measured by wood decay test. As a result of sequencing analysis using the ITS region of the genomic DNA of the fungi isolated from Q. mongolica, Mucor circinelloides, Cunninghamella elegans, and Umbelopsis isabellina 3 species belonging to Mucoromycota phylum, and Ophiostoma piceae and Aureobasidium melanogenum 2 species belonging to Ascomycota phylum were identified. These five fungi had enzyme (i.e. cellulase, laccase) activities related to wood decay and reduced the mass of heartwood and sapwood of Q. mongolica in practice. In particular, O. piceae and A. melanogenum, which have both cellulase and laccase activities, showed 6.9% and 1.5% mass loss, respectively. These results indicated that five fungi identified in this study influence the deterioration of Q. mongolica and are wood decaying fungi for Q. mongolica potentially.