• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.2
• /
• pp.79-89
• /
• 2009

Naphthalene is a volatile, hydrophobic, and possibly carcinogenic compound that is known to have a severe detrimental effect to aquatic ecosystem. Our research examined the effects of various operating conditions (temperature, pH, initial concentration, and frequency and type of ultrasound) on the sonochemical degradation of naphthalene and OH radical production. The MDL (Method detection limit) determined by LC/FLD (1200 series, Agilient) using C-18 reversed column is measured up to 0.01 ppm. Naphthalene vapor produced from ultrasound irradiation was detected under 0.05 ppm. Comparison of naphthalene sonodegradion efficiency tested under open and closed reactor cover fell within less than 1% of difference. Increasing the reaction temperature from $15^{\circ}C$ to $40^{\circ}C$ resulted in reduction of naphthalene degradation efficiency ($15^{\circ}C$: 95% ${\rightarrow}$ $40^{\circ}C$: 85%), and altering pH from 12 to 3 increased the effect (pH 12: 84% ${\rightarrow}$pH 3: 95.6%). Pseudo first-order constants ($k_1$) of sonodegradation of naphthalene decreased as initial concentration of naphthalene increased (2.5 ppm: $27.3{\times}10^{-3}\;min^{-3}\;{\rightarrow}$ 10 ppm : $19.3{\times}10^{-3}\;min^{-3}$). Degradation efficiency of 2.5 ppm of naphthalene subjected to 28 kHz of ultrasonic irradiation was found to be 1.46 times as much as when exposed under 132 kHz (132 kHz: 56%, 28 kHz: 82.7%). Additionally, its $k_1$ constant was increased by 2.3 times (132 kHz: $2.4{\times}10^{-3}\;min^{-1}$, 28 kHz: $5.0{\times}10^{-3}\;min^{-1}$). $H_2O_2$ concentration measured 10 minutes after the exposure to 132 kHz of ultrasound, when compared with the measurement under frequency of 28 kHz, was 7.2 times as much. The concentration measured after 90 minutes, however, showed the difference of only 10%. (concentration of $H_2O_2$ under 28 kHz being 1.1 times greater than that under 132 kHz.) The $H_2O_2$ concentration resulting from 2.5 ppm naphthalene after 90 minutes of sonication at 24 kHz and 132 kHz were lower by 0.05 and 0.1 ppm, respectively, than the concentration measured from the irradiated M.Q. water (no naphthalene added.) Degradation efficiency of horn type (24 kHz) and bath type (28 kHz) ultrasound was found to be 87% and 82.7%, respectively, and $k_1$ was calculated into $22.8{\times}10^{-3}\;min^{-1}$ and $18.7{\times}10^{-3}\;min^{-1}$ respectively. Using the multi- frequency and mixed type of ultrasound system (28 kHz bath type + 24 kHz horn type) simultaneously resulted in combined efficiency of 88.1%, while $H_2O_2$ concentration increased 3.5 times (28 kHz + 24 kHz: 2.37 ppm, 24 kHz: 0.7 ppm.) Therefore, the multi-frequency and mixed type of ultrasound system procedure might be most effectively used for removing the substances that are easily oxidized by the OH radical.

• Korean Journal of Agricultural Science
• /
• v.22 no.1
• /
• pp.49-53
• /
• 1995

The tea red spider mite has recently outbroken as the major pest of tea at tea plantation area in southern part of Korea. This study was carried out to investigate some development of the tea red spider mite. The results were summarized as follows: 1. The body length and width of adult female and male were 0.40mm and 0.22mm, and 0.31mm and 0.20mm, respectively. 2. Durations of immature stage of females were 24.8 days at $16^{\circ}C$, 17.0 days at $20^{\circ}C$, 11.0 days at $24^{\circ}C$, 8.2 days at $28^{\circ}C$, and 6.7 days at $32^{\circ}C$. 3. The average longevities of female of the tea red spider mite were 31.5 days at $16^{\circ}C$, 13.4 days at $20^{\circ}C$, 8.4 days at $24^{\circ}C$, 7.8 days at $28^{\circ}C$, and 5.8 days at $32^{\circ}C$.

• Korean journal of food and cookery science
• /
• v.28 no.4
• /
• pp.391-397
• /
• 2012

This study was carried out to investigate commercialization of Kimchi made of cabbage (Brassica oleracea var. capitata L.) using pre-fermentation conditions. The pre-fermentation conditions were 0, 18, 24, and 28 h at $20^{\circ}C$, and then the samples were stored at $10^{\circ}C$ to assess changes in quality characteristics. A comparison of the quality characteristics during storage showed that PF24 (pre-fermented cabbage Kimchi during 24 h at $20^{\circ}C$) and PF28 (pre-fermented cabbage Kimchi during 28 h at $20^{\circ}C$) had pH 4.47 and pH 4.23 on the second day of storage, respectively. It was possible to shorten the fermentation time to less than that of PF0 (not pre-fermented cabbage Kimchi at $20^{\circ}C$), by approximately 3 days. Total acidity was 0.26 to 0.29% immediately after making the Kimchi. However, PF0, PF18 (pre-fermented cabbage Kimchi during 18 h at $20^{\circ}C$), PF24 and PF28 became well-fermented when they were stored for 8~14 days, 3~10 days or 2~3 days. The number of lactic acid bacteria increased with the passage of time in all treatment groups regardless of fermentation conditions. However, the longer pre-fermentation time became, the faster the number of lactic acid bacteria increased. Most samples showed similar results late in the storage period; 7.2~7.4 log CFU/mL. PF0 had the greatest volume change 2.1 times increase late in the storage period. The sensory evaluation showed significant differences for flavor, taste, and overall acceptability after a partial storage period. PF28 stored for 2~3 days showed excellent flavor, and PF24 and PF28 stored for 2~3 days showed the highest scores of 6.27 to 6.67. The PF24 and PF28 treated samples were appropriate for commercializing small packed cabbage Kimchi and for alleviating the expansion problem of the packing material. However, because mass commercial production requires a large number of samples to be used at once, the results should be assessed for industrial product development in the future.

• Journal of Aquaculture
• /
• v.9 no.4
• /
• pp.339-344
• /
• 1996

The effect of temperature ($24\~36^{\circ}C$ and salinities ($5\~30$ ppt) on hatching rate of the resting egg of the Korean rotifer, Brachionus plicatilis was investigated. The highest hatching rate of the resting egg was $85.7\%$ at $28^{\circ}C$ and 15 ppt. The hatching rates of the resting eggs with salinities were not significant at $326{\circ}C$ and $36^{\circ}C$. Hatching was faster at higher temperature. The resting eggs stored at $5^{\circ}C$ in dark hatched simultaneously within two days, however, those at $28^{\circ}C$ in dark hatched intermittently within 14 days. But, final hatching rate of the resting egg at $28^{\circ}C$ was higher at $28^{\circ}C$ than that at $5^{\circ}C$. With regard to drying temperature and time of resting egg, the resting egg dried at $30^{\circ}C$ for 1 hour showed the highest hatching rate ($46.4\%$).

• Journal of Bio-Environment Control
• /
• v.23 no.1
• /
• pp.39-42
• /
• 2014

The objective of this study was to estimate cardinal temperatures for germination of lettuce (Lactuca sativar L.) using bilinear, parabolic, and beta distribution functions. Seeds of lettuce were germinated in a growth chamber at 7 constant temperatures: 10, 14, 16, 20, 24, 28, and $32^{\circ}C$. Four replicates of 100 seeds were placed on two layers of filter paper in a 9 cm petri-dish. Radicle emergence of 1 mm was scored as germination. The time course of germination was modeled using a logistic function. These minimum, optimum, and maximum temperatures were estimated by regression of the inverse of time to 50% germination rate against the temperature gradient. In bilinear function, minimum, optimum, and maximum temperatures were $7.9^{\circ}C$, $23.3^{\circ}C$, and $28.0^{\circ}C$, respectively. In parabolic function, minimum, optimum, and maximum temperatures were $9.7^{\circ}C$, $19.5^{\circ}C$, and $29.4^{\circ}C$, respectively. In beta distribution function, minimum, optimum, and maximum temperatures were $3.7^{\circ}C$, $20.7^{\circ}C$ and $32.0^{\circ}C$, respectively. Minimum, optimum, and maximum ranges of temperatures were $3.7{\sim}9.7^{\circ}C$, $19.5{\sim}23.3^{\circ}C$, and $28.0{\sim}32.0^{\circ}C$, respectively.

• The Korean Journal of Malacology
• /
• v.19 no.2
• /
• pp.133-142
• /
• 2003

For the effective seedling production of flat oyster, Ostrea denselamellosa, dietary value of live food, densities, water temperature and salinity on growth and survival rate of the larvae were examined. In rearing larvae by feeding them phytoplankton diets, the optimal survival rate and growth rate of larvae were found using a mixed phytoplankton diet which was mixed with Isochrysis galbana, Chaetoceros calcitrans and Chlorella sp. The highest growth and survival rates of the larvae were 208.4% and 38.8% with the phytoplankton diet. In growth and survival rates of larvae with various rearing densities, the highest survival and growth rates were 228.1% and 29.0% at the density of 2 individuals/ml. In observing rearing experiments of the flat oyster larvae under various temperature conditions, average growth rates of the larvae in respect to shell length were 202.2%, 240.4%, 250.6% and 121.3% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32 $^{\circ}C$, respectively. And average survival rates of the larvae were 16.0%, 32.0%, 13.0% and 0% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32$^{\circ}C$, respectively. In rearing at various salinities, the highest growth rates of the larvae in shell length was 240.0% at 30.0 psu and the highest survival rate was 31.0% at 25 psu.

• Korean Journal of Ichthyology
• /
• v.17 no.2
• /
• pp.131-141
• /
• 2005

The ichthyofauna and structure of the fish community of Hapcheon Lake on the Hwang River were surveyed at six localities from May 2004 to Feb. 2005. There were 36 species belonging to 31 genera and 12 families in the Hapcheon Lake system. Of these, 24 species (66.7%) were cyprinids; cobitids and centropomids were next with 2 species (5.6%) each. The dominant species in the Hapcheon Lake system was Hemiculter eigenmanni (relative abundance 28.4%), the subdominant species Hemibarbus labeo (24.1%). Ten species (28.3%) of the 36 were Korean endemic species. Among the endemic species, H. eigenmanni and Squalidus chankaensis tsuchigae were abundant at each locality except site 6, but the eight other species were rare. In biomass, H. labeo comprised about 36.5% of the total weight, H. eigenmanni 22.3%, Cyprinus carpio 7.5%, Hypomesus nipponensis 6.9%, Culter brevicauda 3.7% and Lepomis macrochirus 3.6%. Average dominance, diversity, and evenness index of the fish community collected from six localities in the Hapcheon Lake system were 0.21, 0.85, and 0.67, respectively.

• Journal of the Korean Wood Science and Technology
• /
• v.35 no.4
• /
• pp.21-28
• /
• 2007

To analyze the changes in pH and elemental content ratio of wood charcoal and in FT-IR spectra of their surfaces, wood charcoals carbonized from Pinus koraiensis were used. pHs of wood charcoals carbonized from Pinus koraiensis at 300 and $400^{\circ}C$ were 5-27 and 6.80, respectively, whereas they were between 9.25~10.35 for the wood charcoals manufactured between $500{\sim}900^{\circ}C$ From the changes in the elemental ratios of Pinus koraiensis wood charcoal by increasing carbonization temperature, carbon (C) contents increased by elevating the carbonization temperature with the decreasing in content ratios of O and H. The largest changes in the ratio was found between the carbonization temperature 400 and $500^{\circ}C$. Ratios of C, O, H of the wood charcoal manufactured at 300 and $400^{\circ}C$ were 67.7, 28.9, 3.0% and 72.2, 24.9, 2.5%, respectively, while those at $500{\sim}900^{\circ}C$ were between 83.3~90.5, 13.6~9.0, 2.7~0.3%. The surface functional groups of Pinus koraiensis wood charcoals were determined by comparison of FT-IR spectra of the wood powder and the wood charcoal carbonized with the wood powder. The functional groups on the surface of wood charcoals carbonized at 300 and $400^{\circ}C$ were considered to be acidic groups like Lactone, Lactol, Carboxylic acid, Carboxylic anhydride, whereas Pyrone types could be the major functional groups for the wood charcoals carbonized between 500 and $900^{\circ}C$.

• Korean journal of applied entomology
• /
• v.44 no.4 s.141
• /
• pp.325-330
• /
• 2005

This study was conducted to determine the effect of temperatures on the egg and nymphal development, adult longevity and oviposition of bean bug, Riptortus clavatus Thunberg, using Saealkong seed as food sources in fibrous nylon-tube at four different temperatures (20, 24, 28 and $32^{\circ}C$). Hatchability showed the highest value of 100% at $28^{\circ}C$ and decreased with increasing temperature. Egg duration ranged from 7 days at $32^{\circ}$ to 16.7 days at $20^{\circ}C$. Instar duration was longer with increasing instar stage. Nymphal duration was 38 days at $20^{\circ}C$, 30 days at $24^{\circ}C$, 23 days at $28^{\circ}C$, and 18 days at $32^{\circ}C$ Emergence rates to adult were 16, 41, 72 and 68% at 20, 24, 28 and $32^{\circ}C$, respectively. Female adult longelity ranged from a minimum 20 days at $20^{\circ}C$ to a maximum 63 days at $28^{\circ}C$, while the longevity of male ranged from 19 days at $20^{\circ}C$ to 60 days at $28^{\circ}C$. Preoviposition duration was shorter with increasing temperature and ranged from 11 days at $20^{\circ}C$ to 5 days at $32^{\circ}C$. Total number of eggs laid per female ranged from a minimum 21 eggs at $20^{\circ}C$ to a maximum 67 eggs at $28^{\circ}C$. Consequently, the estimated lower threshold tempeatures of each developmental stage were $10.3^{\circ}C$ for egg, and 9.3, 12.7, 10.0, 11.0 and 8.7 for the 1st, 2nd, 3rd, 4th and 5th instar, respectively.

• Parasites, Hosts and Diseases
• /
• v.24 no.2
• /
• pp.115-120
• /
• 1986

This study was carried out to reveal the effect of temperature, salinity and aeration on maturation and hatching of Fibricola seoulensis eggs. The eggs were incubated and were observed daily for the appearance of eyespots and hatching. The results were summarized as follows. 1. From $4{\sim}5$ days after incubation in distilled water at $28^{\circ}C$ or at $11{\sim}26^{\circ}C$, the eyespots began to appear and the rates of eggs with eyespots were over 90% in $28^{\circ}C$ on the 7th or 8th day. However, eyespots did not appear in $5{\sim}15^{\circ}C$ or $4^{\circ}C$ by the 18th day. 2. The mature eggs began to hatch at the 8th day, and hatching rate 2 weeks after incubation was over 90% at $28^{\circ}C$, but it was below 5% at $11{\sim}26^{\circ}C$, and 0% at $5{\sim}15^{\circ}C$ and at $4^{\circ}C$. 3. Aeration did not influence the appearance of eyes pots nor hatching. 4. In salines under 0.6%, the rates of eyespots appearance were over 90% on the 7th day. The rate was 55.0% in 0.9% at 20 days, and 0% in 1.2%. 5. The hatching rates in salines below 0.3% concentration were over 90% by 14 days of incubation. However, the rate decreased to 44% in 0.6% saline and to 0% over 0.9% salinity. 6. The eggs incubated in the dark hatched in 12.5% on the 10th day, but hatching rate of mature eggs increased to 85.7% within 2 hours after exposure to light. Above results demonstrated that the best temperature for maturation and hatching of F. seoulensis eggs was $28^{\circ}C$, and the miracidia began to hatch at $8{\sim}9$ days after incubation. In the field, hatching and invasion into snails of the miracidia may occur from May to September in Korea. In salines under 0.3% concentration maturation and hatching were not influenced, but as salinity increased hatching was inhibited more than maturation was.