• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.429-432
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• 2011

The feasibility of applications of the char obtained from a gasification process of municipal-waste refuse derived fuel (RDF) as an auxiliary fuel was evaluated by combustion experiments. The higher heating value of the RDF char was 3000~4000 kcal/kg and its chlorine content was below the standard requirement demonstrating its potential as an auxiliary fuel. In the combustion exhaust gas, the maximum $NO_x$ and $SO_2$ concentrations were 240 ppm and 223 ppm, respectively. If an aftertreatment is applied, it is possible to control their concentrations low enough to meet the air pollutant emission standard. The HCl concentration was relatively high indicating that a care should be taken for HCl emission from the combustion of RDF. Based on the temperature distribution within the reactor, the concentration change of $O_2$ and $CO_2$, and the amount and the loss on ignition of solid residue, it was inferred that the combustion reaction was the most reliable when the excess air ratio of 1.3 was used.

• FLOWER RESEARCH JOURNAL
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• v.26 no.4
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• pp.187-194
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• 2018

This study was conducted to investigate the facilities, cultivation, postharvest management, and distribution status of 27 cut chrysanthemum farms in Korea. The 60% of farms have cultivated the cut chrysanthemum using soil fertigation system in the PE plastic house. In Jeonnam and Busan provinces, Standard type of chrysanthemum was cultivated mainly than spray type of chrysanthemumJeoas. Most farms have been producing the rooted cuttings by plug system using cuttings self-propagated or purchased from the company, but farms in Jeonnam have been planting cuttings directly on cultivation bed. And the 66.6% of cut chrysanthemum farms have been pretreating with dipping in hot water or tap water after harvesting. Precooling was not performed on 70.4% of the farms, and precooling farms have been mainly conducted at temperature of $2-4^{\circ}C$. After harvesting, 70.4% of the farms stored the cut flowers at $2-4^{\circ}C$ for more than 48 hours to control the distribution volume. Cut chrysanthemum was graded mainly by individuals before distribution, and some export farmers have been conducting the cooperative grading. In distribution, all farms have distributed the cut flowers to the domestic markets, and 44.4% of these farms have been also exporting. The 63.0% of farms distributed to domestic market have been trading with flower auction sites.

• Korean Journal of Environment and Ecology
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• v.36 no.4
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• pp.381-389
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• 2022

This study investigated the ecological characteristics of Microphysogobio yaluensis at Dugye Stream of Geum River basin from January to December 2021. The river bed structure of this species' habitat was rich in pebbles and gravel. The water depth ranged from 12 to 85 cm with an average of 23 cm, which was shallow. The stream velocity was rapid at 1.03±0.34(0.72-1.47) m/sec. The ratio of females to males was 1:0.86. The age according to the total length-frequency distribution as of summer (June, July) indicated that the group with less than 50 mm (30.4-49 mm) in total length was one year old, the group with 50-69 mm was two years old, and the group over 70-92 mm was three years old. Both male and female fish sexually matured at 50 mm long and two years old in June and July. The spawning season was from July to August, and the water temperature was between 25.8℃ and 28.2℃ during the period. The prosperous spawning season was July. The matured eggs were yellowish and spherical with a mean diameter of 0.52±0.16 (0.33-0.77) mm, and the average number of eggs found in the ovaries of mature female fish was 2,593 (1,343-4,672). As for the food of M. yaluensis, only attached algae, which grow by attaching to stones and gravel of the stream rapids, were identified. The feeding habit of M. yaluensis was reported to be herbivorous, ingesting Cyanophyta, Chlorophyta and Bacillariophya. Also, the species belonging to Bacillariophya and Chlorophyta were abundant in Dugye Stream.

• Clean Technology
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• v.15 no.4
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• pp.258-264
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• 2009

Thermodynamic measurements were performed to show the possibility of recovering $CO_2$ from fuel gas (the mixture of $CO_2$ and $H_2$) by forming gas hydrates with water where water was dispersed in the pores of silica gel particles having nominal 100 nm of pore diameter. The hydrate-phase equilibria for the ternary $CO_2+H_2$+water in pores were measured and $CO_2$ concentrations in vapor and hydrate phase were determined under the hydrate-vapor two phase region at constant 274.15 K. It was shown that the inhibition effect appeared due to silica gel pores, and the corresponding equilibrium dissociation pressures became higher than those of bulk water hydrates at a specific temperature. In addition, direct measurement of $CO_2$ content in the hydrate phase showed that the retrieved gas from the dissociation of hydrate contained more than 95 mol% of $CO_2$ when 42 mol% of $CO_2$ and balanced Hz mixture was applied. Compared with data obtained in case of bulk water hydrates, which showed just 83 mol% of $CO_2$ where 2-stage hydrate slurry reactor was intended to utilize this property, the hydrate formation in porous silica gel has enhanced the feasibility of $CO_2$ separation process. Hydrate formation as not for slurry but solid particle makes it possible to used fixed bed reactor, and can be a merit of well-understood technologies in the industrial field.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.375-383
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• 2023

To determine the cause of the population decline in Gobiobotia naktongensis, substrate preference and burying behaviour were investigated in this study. In general, the species was shown to prefer a substrate size of 1 mm or less, depending on the flow. In addition, the burying depth varied according to the size of the fish and increased with a decrease in water temperature. Our findings showed that the main cause of the population reduction was the physical changes in the substrate structure due to the dams or barrages construction. Notably, the accumulation of silt and mud in the substrate upon the formation of an upstream lentic water region for structural construction and bed armouring caused by scouring and reduced downstream inflow of fine sediment were deterministic in the fish habitat changes, causing problems in burying. As sand substrate structure is critical for the survival and inhabitation of psammophilous species, efficient strategies should be developed with proper habitat management to reduce the anthropogenic damage

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.507-514
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• 2023

The selective catalytic reduction (SCR) of nitrogen oxides (NO_x) was investigated in a catalyst (Ag/γ-Al₂O₃) packed dielectric barrier discharge plasma reactor. The intermittent generation of plasma in the catalyst bed partially oxidized the hydrocarbon reductant for NO_x removal to several aldehydes. Compared to using the catalyst alone, higher NO_x conversion was observed with the intermittent generation of plasma due to the formation of highly reductive aldehydes. Under the same operating conditions (temperature: 250 ℃; C/N: 8), the NO_x reduction efficiencies were 47.5%, 92%, and 96% for n-heptane, propionaldehyde, and butyraldehyde, respectively, demonstrating the high NO_x reduction capability of aldehydes. To determine the optimal condition for intermittent plasma generation, the high voltage on/off cycle was adjusted from 0.5 to 3 min. The NO_x reduction performance was compared between continuous and intermittent plasma generation on the same energy density basis. The highest NO_x reduction efficiency was achieved at 2-min high voltage on/off intervals. The reason that the intermittent plasma discharge exhibited higher NO_x reduction efficiency even at the same energy density, compared to the continuous plasma generation case, is that the intermediate products, such as aldehydes generated from hydrocarbon, were more efficiently utilized for the reduction of nitrogen oxides.

• Korean Journal of Agricultural Science
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• v.15 no.1
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• pp.47-68
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• 1988

This study was conducted to define the optimal conditions for embryo growth during seed stratification and for breaking dormancy as well as seed germination of stratified ginseng seeds. The experiments were also carried out to detect some materials which were expected to induce seed dormancy in the ginseng seeds. The results summarized as follows; 1. The growth of embryo during seed stratification was significantly inhibited by the existence of endocarp. The fastest embryo growth was resulted at $15^{\circ}C$ and an estimated optimal temperature for embryo growth was about $18^{\circ}C$. 2. There was no significant difference between the embryo growth and germination ratio of ginseng seeds which were sown in seed bed at Aug-5 without seed stratification and that of artificial seed stratification. 3. Embryo growth and germination ratio was significantly inhibited by high temperature treatment at $30^{\circ}C$ for 24 hours or respiration stress by immersing seeds in water for 10 days or more. 4. When the seed stratification was started at $10^{\circ}C$, growth of embryo in the ginseng seeds were almost stopped. But, when the seeds were stratified first at $20^{\circ}C$ for 50 days and next at $10^{\circ}C$ for 50 days, the embryo growth was significantly promoted compared with the embryo growth in the seeds which were stratified at $20^{\circ}C$ for 100 days. 5. The successive embryo growth after seed stratification was significantly accelerated at $10^{\circ}C$ but the seeds chilled at $5^{\circ}C$ for 100 days were resulted in the highest germination ratio as well as the shortest days for germination. 6. The successive embryo growth during chilling treatment and seed germination were significantly inhibited by immersing seeds in water just before chilling treatment or during chilling treatment and by interruption of chilling treatment with raising temperature to $20^{\circ}C$ for 20 days during chilling treatment. 7. The germination ratio of ginseng seeds which finished chilling treatment was highest at $10^{\circ}C$ and 62.5% was the estimated soil moisture for the best germination of ginseng seeds. The ginseng seeds were found to require high amount of oxygen for germination. 8. Only water soluble material in homogenized ginseng seeds showed a significant inhibiting effect on the seed germination of sesame, millet and soybean. Water soluble material dissolved from undehisced ginseng seeds showed stronger inhibiting effect on the seedling growth of sesame than material from dehisced ginseng seeds. Extraction temperature did not influence the inhibiting effect of the material dissolved from ginseng seeds on the seedling growth of sesame. 9. Water soluble materials dissolved from the berry pulps, leaves, fresh roots and dried roots also showed a significant inhibiting effect on the seedling growth of sesame. 10. Water soluble materials dissolved from the ginseng seeds, leaves and fresh roots showed a significant inhibiting effect on the germination of true fungi and the growth of spawn but the growth of phytopathogenic bacteria was not. 11. Among the water soluble materials dissolved from ginseng seeds, the materials of low molecular weight less than 3,000 were resulted a significant inhibiting effect on the seedling growth of sesame and the materials of high molecular weight also showed an inhibiting effect.

• Journal of the Mineralogical Society of Korea
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• v.6 no.2
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• pp.122-144
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• 1993

The Kimhae napseok clay deposit was studied to characterize its mineralogy and genesis. Geology of the deposit is composed of Tertiary volcanic rocks and granodiorite. Tertiary volcanic rocks consist of andesitic tuff with minor interstratified tuffaceous shale, and rhyodacitic tuff. The main ore body of 2.4 to 4 m in thickness developed parallel to the bedding of andesitic tuff bed. Its strike and dip are $N70^{\circ}E-N85^{\circ}E$ and $16^{\circ}NW-32^{\circ}NW$, respectively. Two alteration zones; the propylitic zone of albite-epidote-chlorite-quartz assemblage and advanced argillic zone of pyrophyllite-dickite-alunite-diaspore assemblage are developed. Correlation of $SiO_2$ to $Al_2O_3$ shows no relation in propylitic zone, while a negative linear relation in advanced argillic zone. Chemical variation shows that $SiO_2$, $Al_2O_3$, MgO, CaO, $Na_2O$ and $K_2O$ were leached out during hydrothermal alteration. Pyrophyllite, the most abundant mineral in advanced argillic zone, occurs as low temperature 2M polytype. It is closely associated with dickite, diaspore and alunite. The Hinckley index of dickite is 0.83 showing moderate crystallinity. Na content is increasing in the M site with the increasing content of cations in the R-site. the mole percent of Na replacing K in alunite ranges from 53.2 to 71.6. It is also found that pyrophyllite grows in the dissolution site of diaspore. Plagioclase was albitized. Lowering of pH caused mainly by sulfide and sulfate decomposition resulted in preferential leaching of Si. It is inferred that aluminum released from plagioclase in the volcanic rocks as well as from the tuffaceous shale intercalated in andesitic tuff were the main sources of aluminum required for the formation of clay deposit. pH in hydrothermal fluid decreased from propylitic zone to advanced argillic zone with increasing degree of alteration. Based on experimental data reported in the literature and mineral assemblages, the formation temperature of the deposit ranges 270 to $320^{\circ}C$.

• Journal of the Korean Wood Science and Technology
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• v.16 no.4
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• pp.10-39
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• 1988

This study investigated the temperatures and relative humidities in the semi-greenhouse type solar dryer with a black rock-bed heat storage and without heat storage and outdoor temperature and relative humidity at 9 a.m. and 2 p.m.. A comparison was made of the drying rates, final moisture contents, moisture content distributions, casehardening stresses, drying defects, volumetric shrinkage of dried lumber for solar- and air-drying from the green condition of mixtures of Douglas-fir, lauan, taun, oak and sycamore 25mm- and 50 mm-thick lumber during the same period for four seasons, and heat efficiencies for solar dryer with and without the heat storage for saving of heat energy and the cost of lumber drying using the solar energy. The results from this study were summarized as follows: I. The mean weekly temperatures in the solar dryers were 3 to $6^{\circ}C$ at 9 a.m. and 9 to $13^{\circ}C$ at 2 p.m. higher than mean outdoor temperature during all the drying period. 2. The mean weekly relative humidities in the solar dryers were about 1 to 19% at 9 a.m. higher than the outdoor relative humidity. and the difference between indoor and outdoor relative humidity in the morning was greater than in the afternoon. 3. The temperatures and relative humidities in the solar dryer with and without the heat storage were nearly same. 4. The overall solar insolation during the spring months was highest and then was greater in the order of summer, atumm, and winter month. S. The initial rate of solar drying was more rapid than that of air drying. As moisture content decreased, solar drying rate became more rapid than that of air drying. The rates of solar drying with and without heat storage were nearly same. The drying rate of Douglas-fir was fastest and then faster in the order of sycamore, lauan, taun and oak. and the faster drying rate of species, the smaller differences of drying rates between thicknesses of lumber. The drying rates were fastest in the summer and slowest in the winter. The rates of solar drying during the spring were more slowly in the early stage and faster in the later stage than those during the autumn. 6. The final moisture contents were above 15% for 25mm-thick air dried and about 10% for solar dried lumber, but the mean final MCs for 50mm-thick lumber were much higher than those of thin lumber. The differences of final MC between upper and lower course of pile for solar drying were greater than those of pile for air drying. The differences of moisture content between the shell and the core of air dried lumbers were greater than those of solar dried lumber, smallest in the drying during summer and greatest in the drying during winter among seasons. 7. Casehardening stresses of 25mm- and 50mm-thick dried lumber were slight, casehardening stress of solar dried lumber was severer than that of air dried lumber and was similar between solar dried lumber with and without heat storage, Casehardening stresses of lumber dried during spring were slightest and then slighter in the order of summer, autumn, and winter. Casehardening stresses of Douglas -fir, sycamore and lauan were slight, comparing with those of taun and oak. 8. Maximum initial checks of 25mm-thick lumber occurred above and below fiber saturation point and those of 50mm-thick lumber occurred in the higher moisture content than thin lumber. As the moisture content decreased, most of checks were closed and didn't show distinct difference of the degree of checks among drying methods. The degree of checks were very slight in case of Douglas-fir and lauan, and severe in case of taun and oak. The degree of checks for 50mm-thick lumber were severer than those for 25mm-thick lumber. 9. The degree of warpage showed severe in case of oak and sycamore lumber, but no warping was found in case of Douglas-fir, lauan and taun. 10. The volumetric shrinkages of taun and oak were large and medium in case of Douglas-fir, lauan and sycamore. 11. Heat efficiencies of solar dryer with heat storage were 6.9% during spring, 7.7% during summer, 12.1% during autumn and 4.1% during winter season. Heat efficiency of solar dryer with heat storage was slightly greater than that of without heat storage. As moisture content of lumber decreased, heat efficiency decreased.

• Clean Technology
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• v.26 no.2
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• pp.137-144
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• 2020

Metal-impregnated activated carbons were prepared via ultrasonic-assisted impregnation method for regeneration and low ammonia concentration. Magnesium and copper were selected as metals, while chloride (Cl^-) and nitrate (NO₃^-) precursors were used to impregnate the surface of activated carbon. The physical and chemical properties of the prepared adsorbents were characterized by TGA, BET, and NH₃-TPD. The ammonia breakthrough test was carried out using a fixed bed and flowing ammonia gas (1000 mg L^-1 NH₃, balanced N₂) at 100 mL min^-1, under conditions of temperature swing adsorption (TSA) and pressure swing adsorption (PSA, 0.3, 0.5, 0.7, 0.9 Mpa). The adsorption and desorption performance of ammonia were in the order of AC-Mg(Cl) > AC-Cu(Cl) > AC-Mg(N) > AC-Cu(N) > AC through NH₃-TPD and TSA and PSA processes. AC-Mg(Cl) using MgCl₂ showed the average adsorption amount of 2.138 mmol/g at TSA process. Also, AC-Mg(Cl) showed the highest initial adsorption amount of 3.848 mmol/g at PSA 0.9 Mpa. When metal impregnated the surface of the activated carbon, it was confirmed that not only physical adsorption, but also chemical adsorption increased, making enhancement in adsorption and desorption performances possible. Also, the prepared adsorbents showed stable adsorption and desorption performances despite repeated processes, confirming their applicability in the TSA and PSA processes.