• Korean Journal of Environmental Agriculture
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• v.4 no.2
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• pp.108-113
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• 1985

Aerial application tests with a biological insecticide (Thuricide$^{(R)}$) and two low toxicity insecticides, Diflubenzuron (Dimilin$^{(R)}$) and Triflumuron (Alsystin$^{(R)}$) were carried out against the fall webworm (Hyphantria cunea Drury). For experimental application by helicopter, dilutions of 30x and 45x Thuricide, 180x and 240x Alsystin, and 180x Dimilin were utilized. The solutions were applied at a rate of 30 liters per hectare. The results are as follows: 1) All treatments, Dimilin 25% wp, Thuricide wp, and Alsystin 25% wp, were found to very effec tive against fall webworm larvae. Percentages of mortality averaged between 93.9% and 97%. 2) No significant differences in percentages of larval kill were found between dilutions of Thuricide (30x and 45x) or Alsystin (180x and 240x). 3) Assessment of parasite densities in the treated areas 35 days after treatment indicated that percentages of reduction for all five species found, including Brachymeria lasus(Walker) (=obscurata [Walker]), were lower than for areas treated with the conventional insecticide Diplox$^{(R)}$ (trichlorfon) 25% wp. In particular, the percentage of reduction in Thuricide-treated areas was only 21% as compared with the untreated (control) areas. 4) Aerial applications of Dimilin were very effective and economical for control of the fall webworm by comparison with [aerial] applications of Thuricide.

• Journal of Energy Engineering
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• v.7 no.2
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• pp.194-201
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• 1998

In electric commuter trains using AC motors, lots of GTO thyristors and diodes are needed for power controls. These semiconductors generate heat about 1~2 kW, and for cooling which perfluorocarbon(PFC) heat pipes have been in use for the last two decades. The present study was investigated on the effects of such important design parameters as structure of internal surface (grooved or smooth), fill charge ratio, and inclinating angle from a vertical on heat transfer coefficients at both evaporators and condensers. To obtain experimental data, several heat pipes of the same geometry of 520 mm long and diameter of 15.88 mm but different in fill charge ratio and internal surface structure were designed and fabricated. For prediction of the heat transfer coefficients, related expressions were examined and the results of calculations were compared with experimental data. Performance tests were conducted while heat pipes operated at mode of thermosyphons. High enhancements of heat transfer coefficient were obtained internal grooves. In these cases, the evaporating heat transfer coefficients distributed in the range of 2~5.5 kW/$m^2$K, with an increase of heat flux from 15~45 kW/$m^2$. These experimental data were in good agreement with Rohsenow's expression based on nucleate boiling when correction factor $C_R$=1.3 was encountered. In addition, the condensation heat transfer coefficients were distributed from 1.5 to 3.5 kW/$m^2$K, and the data were in good agreements with Nusselt's correlation, based on filmwise condensation on vertical plate, when choosing a correction factor $C_N=4$. A fill charge ratio of 40~100% were recommended, and the in clination angle effects were negligible when the angle was higher then 30$^{\circ}$.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.6
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• pp.31-37
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• 2010

This study was carried out to investigate the thermal decomposition and execute EIDS slow cook-off test for the propellant ingredients and 2 kinds of HTPE propellants. The thermal analysis of the propellant ingredients used in this study showed that the thermal stability of these materials decreases in the following order : AP > HTPE > AN > BuNENA. In addition, propellant HTPE 002 containing AN showed that an endothermic process at around $125^{\circ}C$ corresponding to the solid phase change(II$\rightarrow$I) of AN was followed by the exothermic process of BuNENA/AN mixture up to $200^{\circ}C$. In EIDS slow cook-off tests, HTPE 001 and HTPE 002 reacted at around $250^{\circ}C$ and $152^{\circ}C$ respectively, and both of them showed sudden temperature increase curves at $115^{\circ}C$. The critical temperatures, $T_c$, of thermal explosion for the propellants HTPE 001 and HTPE 002, were obtained from both the non-isothermal curves at various heating rates and Semenov's thermal explosion theory. Kissinger's method that was used to calculate $T_c$ was also employed to obtain the activation energies for thermal decompositions.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.2
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• pp.49-57
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• 2020

Due to the sewage sludge's characteristics of high water content and low calorific value, it is hard to use sewage sludge as an energy source. In this study, we investigated production of bio-solid fuel which is mixed both sewage sludge and woody biomass in order to improve the sewage sludge's characteristics and replace fossil fuels. A thermogravimetric analysis was used to investigate the co-combustion characteristics of the mixed coal and bio-solid fuel of 5%, 10%, 15%, respectively. The analysis was carried out under non-isothermal conditions by raising the internal temperature of 25℃ to 900℃ with an increment of 10℃/min. In the case of comparing single coal sample and mixture sample of coal and bio-solid fuel, the initiation combustion temperature has slightly changed. However, both the maximum combustion temperature and the termination start combustion temperature were hardly noticeable. The initiation combustion was occurred between 200~315℃ and the thermal decomposition causing a significant weight change occurred between 350~700℃. As a result of the kinetic analysis of the co-combustion, the activation energy was decreased as the mixing rate was higher. Therefore, it is able to co-combust the mixed coal and bio-solid fuel in power plants.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4039-4045
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• 2014

The crystallization behavior of irradiated polypropylene (PP) and the blend is an important parameter for polymer processing. Blends of PP/low density polyethylene (LDPE) with different LDPE contents were prepared by melt mixing in a twin screw extruder. The effect of the LDPE content on the irradiation effectiveness of the PP/LDPE blend with trimethylolpropane-trimetacrylate (TMPTMA) as a crosslinking co-agent was investigated in conjunction with the LDPE loading in the blend. The non-isothermal crystallization and crystal structure were measured by DSC, X-ray diffraction (XRD), and polarized optical microscopy (POM). A decrease in the melting temperature of PP was observed due to irradiation, which may be due to the PP chain scissioning effect of irradiation. The Ozawa component n represents a rod shaped, disc shaped and sphere-shaped geometry of the crystal if the value corresponds to 2, 3 and 4, respectively. Based on Ozawa analysis, the values of n were 3.8 and 2.3 for the pure PP and PP blends with 30 wt% LDPE, respectively. The fact that the crystal geometry of PP changed from spherical to disc and rod shaped was confirmed by Ozawa analysis and POM. The ${\beta}$ form XRD peak of the PP/LDPE blend at $16.1^{\circ}$ disappeared after irradiation due to the crosslinking reaction.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.676-682
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• 2009

Devolatilization of the Refuse Derived Fuel(RDF) which is produced at WonJu in Korea was characterized in air atmosphere with variation of heating rate(10, 20 and $30^{\circ}C/min$) in TGA. The results of TG Analysis have shown that the pyrolysis and char combustion of the RDF occurred in the range of $350{\sim}700^{\circ}C$ depending on the heating rate. Activation energy of the RDF which was determined by using Friedman and Ozawa-Flynn-Wall method was in the range of 14.44~18.40 kcal/mol. Also, reaction order(n) and pre-exponential factors(A) were 1.219 and $3.02{\times}10^5$ by using Friedman method, respectively. In order to find out the devolatilization mechanism of the RDF, twelve solid-state mechanisms defined by Coats Redfern Method were tested. The results of the Coats Redfern Method have shown that chemical reaction is the effective mechanism by comparison with the value of the activation energy which was derived from the Friedman and Flynn-Wall-Ozawa method and correlation coefficient from twelve solid-state mechanisms of Coats Redfern Method. The solid state decomposition mechanism of the RDF was found to be a decelerated $F_1$ type, random nucleation with one nucleus on the individual particle.

• Economic and Environmental Geology
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• v.39 no.5 s.180
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• pp.583-595
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• 2006

Quartz veins from the Hwawon area are an epithermal quartz vein that is filling the fault zone within Precambrian metasedimentary rocks and Jurassic granite. Mineralization can be divided into hypogene and supergene stages. Hypogene stage is associated with hydrothermal alteration minerals(propylitic and argillic zones) such as epidote, chlorite, illite, sericite and sulfides such as pyrite, sphalerite, chalcopyrite, galena, bornite, cubanite, argentian tetrahedrite, Pb-Ag-S system and Pb-Te-S system. Supergene stage is composed of Fe-Mn oxide, Zn-Fe oxide and Pb oxide. Fluid inclusion data indicate that homogenization temperatures and salinity of hypogene stage range from $291.2^{\circ}C$ to $397.3^{\circ}C$ and from 0.0 to 9.3 wt.% eq. NaCl, respectively. It suggests that ore forming fluids were cooled and diluted with the mixing of meteoric water. Oxygen($-0.7{\sim}3.5%_{\circ}$(white quartz: $-0.7{\sim}3.5%_{\circ}$, transparent quartz: $2.4%_{\circ}$)) and hydrogen($-70{\sim}55%_{\circ}$(white quartz: $-70{\sim}55%_{\circ}$, transparent quartz: $-62%_{\circ}$)) isotopic composition indicates that hydrothermal fluids were derived from magmatic and evolved by mixing with meteoric water during mineralization.

• Journal of Sericultural and Entomological Science
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• v.24 no.1
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• pp.19-24
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• 1982

This experiment was carried out to develope a new planting system from the economical point of view, using the various sizes of mulberry saplings ranged from 3mm to 7mm (3, 4, 5 and 7mm) in diameter of branches. They were planted densely (2,285 trees/10a) in vinyl film-and non-mulching system. The results are summarized as follows. 1. There are no differences in growth and yield of the planting year between 6mm and 7mm saplings. 2. The vinyl mulching affords an abundant growth of the saplings due to retaining of soil temperature and moisture. The dense planting with vinyl film mulching gave rise to 26% and 7% increase of leaf yield, using the saplings sized of 7mm and 5mm, respectively. 3. On the other hand, it was evident that the use of 6mm saplings in non-mulching and 5mm ones in mulching redused possibly the sapling cost. It was also noteworthy an additional profit took places in the yield increase, the cost reduction of saplings and weeding by using the 7mm and 5mm saplings in mulching system. It amounted to the increase of ￦33,800 and ￦24,520, respectively over the use of 7mm saplings in non-mulching system.

• Journal of the Korean Geotechnical Society
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• v.18 no.6
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• pp.33-42
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• 2002

Ground reaction curve is a very important information for evaluating the side wall displacements and installation time of the tunnle support. The ground reaction curve can be estimated by analytical closed form solutions derived on the supposition of circular section and isotropic stress condition. The conditions of stress field and tunnel configurations, however, are quite different in practice. Therefore, it is necessary to investigate the effects of stress anisotropy and tunnel configurations in order to use simply in practical design. This paper describes a study of influence factors in the ground reaction curve. In order to evaluate the applicability of analytical closed form solution in practical design, two sets of parametric studies were carried out by numerical analysis in elastic tunnel behaviour: one set of studies investigated the influence of the K and the other set investigated the influence of the tunnel configurations such as circular and horse-shoe shape. In the studies, K value varies between 0.5 and 3.0, initial ground vertical stress varies between 5～30MPa far each K values. The results indicated that the self-supportability of ground is larger in the ground having lower K value. However, it is suggested that the applicability of closed form solution may not be adequate to determine directly the installation time of the support and self-supportability of ground. It is necessary to consider stress anisotropy and tunnel configurations.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.4
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• pp.604-608
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• 2002

Accelerated solvent extraction (ASE) was used for a rapid and simple extraction of propylenchlorohydrin (PCH) residue in hydroxylpropyl modified starch. The effects of temperature, pressure and extraction solvent on the extraction efficiency were investigated to find the optimal condition of ASE. The optimal conditions for PCH extraction in hydroxylpropyl modified starch were static time of 50 min, purge time of 300 sec, heating time of 5min, temperature of 12$0^{\circ}C$, pressure of 2500 psi, flush (%) with 100 volumes, and ethylacetate as an extraction solvent. The recovery (96.1%) of this method was higher than that (76.4%) of Code of Food Additive. Therefore, the ASE was a good method in both aspects of efficiency and effectiveness.