• Fire Science and Engineering
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• v.33 no.6
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• pp.20-27
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• 2019

In this study, a new function with higher accuracy for fire heat release rate prediction was developed. The 'αt²' curve, which is the major exponential function currently used for fire engineering calculations, must be improved to minimize the prediction gap that causes fire system engineering inefficiency and lower cost-effectiveness. The newly developed prediction function was designed to cover the initial fire stage that features rapid growth based on logistic function theory, which has a more logical background and graphical similarity compared to conventional exponential function methods for 'αt²'. The new function developed in this study showed apparently higher prediction accuracy over wider range of fire growth durations. With the progress of fire growth pattern studies, the results presented herein will contribute towards more effective fire protection engineering.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.338-348
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• 2020

This study examined the longitudinal relationship between paternal depressive symptoms and maternal depressive symptoms simultaneously. This study also identified the interplay of paternal and maternal depressive symptoms for predicting elementary children's language development, their problem behaviors and their school adjustment. Using the data from the Panel Study on Korean Children for the 4th-8th years (2011~2015 year), this study used the Latent Growth Curve Model, which is helpful for examining longitudinal relationship differences among variables. The sample subjects were 1,754 parents and children. The results are as follows. The initial level of paternal depressive symptoms had a positive impact on the rate of change in maternal depressive symptoms. The initial level of maternal depressive symptoms had a negative impact on the rate of change in maternal depressive symptoms. Mothers' depressive symptoms showed not only the mothers' own depression problem. but also the self-effect and counterpart effect of depression on the fathers' depression problem. The rate of change in maternal depressive symptom mediated the relation between the initial level of parental depressive symptoms and children's receptive language, internalizing/externalizing problems, and school adjustment. Therefore, depression prevention and intervention programs for both fathers and mothers are needed for the healthy development and school adaptation of school-age children.

• Korean Journal of Social Welfare
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• v.63 no.1
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• pp.187-215
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• 2011

This study examined the longitudinal relationship between depressive symptoms and alcohol use based on the tension reduction hypothesis and the intoxication hypothesis considering for path of depressive symptoms on alcohol use and vice versa simultaneously. And this study examined the effect of psychosocial behavior factors (i.e. smoking level, self-esteem, satisfaction with family relationships, and satisfaction with social relationships) on depressive symptoms and alcohol use. Using the data on the Korea Welfare Panel Study for the 1st, 2nd, and 3rd years, this study were estimated using the Latent Growth Curve Model which is helpful for examining differences between the two. The results are as follows: the initial level of alcohol use had a positive impact on the rate of change in depressive symptoms, thereby supporting the intoxication hypothesis. Second, self-esteem and satisfaction with family relationships act as variables with the biggest effect on the initial level and the rate of change in depressive symptoms, whereas other psychosocial behavior factors such as smoking level and satisfaction with social relationship exert the largest influence over the initial level and the rate of change in alcohol use. This study has implications in that it clarified the confused relationship mechanism between alcohol use and depressive symptoms the two. Based on the finding of the study, political and practical implications were discussed.

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.3
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• pp.186-194
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• 1994

Lack of seedling vigor is considered a serious deterrent to use of broadleafed birdsfoot trefoil (Lorus comicul~rus L.). Our objectives were to compare early seedling growth of broadleafed birdsfoot trefoil cultivar "MO-20" and the large-seeded accession 302921 at $15^{\circ}C$ and $25^{\circ}C$. in controlled-environment chambers. Cabon dioxide exchange rate (CER) was measured in a closed or open system using infrared gas analysis. Dark respiration rate was measured manometrically. Net carbon accumulated per day and growth analysis of the seedlings were calculated. Initial seed mass of 302921 was 3.5 times larger and final cotyledon area was 2 times larger than those of MO-20, and early seedling growth was better. But, from 3 weeks after emergence until the end of the test period at $25^{\circ}C$, MO-20 showed higher CER per unit leaf area and faster dry weight accumulation than did 302921. Compared with $25^{\circ}C$, growth of MO-20 at $15^{\circ}C$ was suppressed more than that of 302921. Dark respiration rate of MO-20 was slightly higher than that for 302921, but not COz uptake per day for MO-20 was highest at$25^{\circ}C$ and lowest at $25^{\circ}C$. The relative growth rate (RGR) of MO-20 was higher than 302921 at $25^{\circ}C$ due to high net assimilation rate, but there was little difference in RGR between entries at $15^{\circ}C$.}C$.

• The Korean Journal of Malacology
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• v.30 no.3
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• pp.219-226
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• 2014

The effects of different stocking densities on the growth and survival rate of the abalone, Haliotis discus hannai, were investigated in marine net cage for two years. Stocking density was set 15, 30, 45 and 60 percentage $(=per.)/m^2$ with share to cross-sectional area per shelter. The primary rearing period (PRP) and the secondary rearing period (SRP) were conducted by a year. One year mean water temperature of PRP and SRS showed the difference about $2^{\circ}C$. In the growth (initial mean shell length of abalone : $36.14{\pm}2.28mm$) of PRP, the absolute growth rate (ARG), daily growth rate (DGR) and specific growth rate (SGR) of the $15per./m^2$ were higher than those of density groups (P < 0.05). Survival rates of all density groups were showed no significant difference. In the growth (mean shell length of abalone : $55.26{\pm}6.93mm$) of SRP, ARG, DGR and SGR of stocking density groups showed no significant difference except for $45per./m^2$ density group. Survival rate in the low-density (15, $30per./m^2$) was more than 70%, and those of the high-density (45, $60per./m^2$) were less than 31% and 9%, respectively. These results showed that the appropriate stocking density for $15per./m^2$ was seven hundred fifty number per one net cage ($2.4{\times}2.4m$), during PRP using 3-4 cm abalone in length. Also for the secondary rearing period, the optimal stocking density (shell length 5-6 cm of abalone) consider with the economical efficiency was determined to be $30per./m^2$, resulting the productivity improved.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.3
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• pp.611-618
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• 2016

A $3{\times}2$ factorial experiment was conducted to investigate effects of water temperature and feeding rate on growth and body composition of olive flounder. Triplicate groups of fish (initial body weight of 118 g) fed a extruded pellet (55% protein and 4708 cal/g) to satiation and at restricted feeding rates of 0.25 and 0.4% body weight per day (BW/d) at the different water temperatures (13 and $18^{\circ}C$) for 9 weeks. Weight gain increased significantly with increase in feeding rates at each temperature. Weight gain of fish fed to satiation was significantly higher at 18 than $13^{\circ}C$, whereas, that of fish fed at 0.25 and 0.4% BW/d were significantly or slightly lower at 18 than $13^{\circ}C$. Feed efficiency and protein efficiency ratio of fish fed to satiation were not significantly different between 13 and $18^{\circ}C$, but those of fish fed at 0.25 and 0.4% BW/d were significantly higher at 13 than $18^{\circ}C$. The major finding of this study is that satiation feeding is efficient for optimal growth and feed efficiency of grower oliver flounder (116-164 g) in suboptimal water temperatures. The maintenance feeding ration which is zero growth performance, were 0.30 and 0.41% BW/day at 13 and $18^{\circ}C$, respectively. In the restricted feeding regime, compromised growth of fish were worsen in higher water temperature ($18^{\circ}C$ vs. $13^{\circ}C$). It might be related to high metabolic rate of fish that spend more energy for maintenance metabolism. Based on these results, we suggest that a satiation feeding regime is recommended for a productive growth of grower olive flounder in the suboptimal temperature.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2116-2124
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• 2015

To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO₃ concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m²/s; temperature: 30℃ pH: 7-8; NaHCO₃ concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R² = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NO_X.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.6
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• pp.563-569
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• 1999

The numerical simulation method was utilized to investigate the optimal condition for synthesizing ultrafine SiC powders by using $TMS[Si(CH_3)_4]-H_2$ gaseous mixtures in the horizontal reactor. As a result of the theoretical analysis, the conversion percentage of TMS source was increased with increasing reaction temperature, however, which was decreased with increasing H$_2$flow rate. Though the SiC particles concentration synthesized was decreased with increasing the reaction temperature due to the higher collision rate in the gas phase, they were increased with increasing the H$_2$flow rate and TMS concentration. The SiC particle size showed a tendency to become larger as the reaction temperature and the initial TMS concentration were increased and smaller as the H$_2$ flow rate was increased. The variation of experimental particle size with the reaction temperature, H$_2$flow rate and TMS concentration was agreed with the theoretical results.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.360-367
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• 1996

The OISF (Oxidation Induced Stacking Fault)is expected to affect the electrical properties in Si single crystals, and the nuclei of OISF are believed to be formed during the crystal growing process. Initial oxygen concentration, dopant type and its density, and cooling rate are regareded as major factors on OISF formation. In this study, the variations of OISF density under various cooling rate were investigated. Si single crystal was heated to $1400^{\circ}C$ in Ar ambient and cooled down to room temperature at different cooling rate, using horizontal tube furnace. After that, they were oxidized at $1150^{\circ}C$, and then, OISF was observed with optical microscope. The relation between oxide procipitates and OISF nucleation was investigated by FTIR analysis. As a result, it was found that there exists the intermediate cooling rate range in which OISF nucleation is highly enhanced. And also, it was found that OISF nucleation is closely related with silicon oxide procipitation in Si single crystals.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.4
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• pp.789-796
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• 2014

This study was conducted to investigate the effects of feeding rate on growth performance, blood components and histology of growing olive flounder. The experiment was carried out to determine the optimum feeding rate of the fish (initial fish mean weight of $97{\pm}3.0$ g) at the optimum water temperature. Two replicated groups of fish were fed commercial diet at the feeding rates of 0, 1.0, 1.65 and 2.3% body weight (BW)/day and satiation. Feeding trial was conducted under a flow-through system with ten 1.2 metric ton aquaria receiving filtered seawater at $21{\pm}2^{\circ}C$ for three weeks. Weight gain and specific growth rate (SGR) for fish fed to satiation were significantly higher than those for the unfed fish and for fish fed at 1.0 and 1.65% BW/day. There were no significant differences in values of such parameters between fish fed at 1.65% and those fed at 2.3% BW/day and between fish fed at 2.3% and those fed to satiation. Weight gain and SGR for the unfed fish were significantly lower than those for fish in the other treatments. All the tissues (hepatopancreas, kidney and anterior intestine) were in good condition in fish fed the experimental diet at different feeding rates. This result indicates that the optimum feeding rates of olive flounder (97-160 g) was approximately 2.52% BW/day at the optimum water temperature.