• Journal of Aquaculture
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• v.13 no.1
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• pp.39-46
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• 2000

Successive management of prawn farm is strongly dependent upon monitoring of pond seawater quality which is generally influenced by an excessive food supplied sediment type and phytoplankton composition in the pond. For good condition of seawater quality it must need exchangning of fresh seawater by tidal current. Two distinct shrimp ponds Galha and Yunho which were different in seawater exchanging system and sediment type were selected to understand how some factors affected to seawater and sediment qualities in the pond. Prawn growth was also determined. Galha pond characterized by sand bottom with water exchanging by turn of the tidal current accumulated 1.8 mgS/g-dry as sulfide in sediment while Yunho pond mud- bottomed with seawater exchanging of pumping system showed 4.7mgS/g-dry when it was highest, Ammonia-N and hydrogen sulfide measured in the seawater were 0.31mg/${\ell}$ and 21.2 ${\mu}$${\ell}$/${\ell}$in Yunho and 0.10mg/${\ell}$and 10.8${\mu}$${\ell}$/${\ell}$in Galha pond respectively. Dissolved oxygen remained below 6.0mg/${\ell}$ in Galha and 5.0mg/${\ell}$in Yunho pond from June through August. Less growth of prawn was found in Yunho pond than in Galha pond. Prawn growth expressed as body length and weight were 138.3mm 22.9g in Yunho pond while they were length 158.2mm and 28.9g in Galha pond respectively when they were harvested in October. These results indicate that higher levels of ammonia-N and hydrogen sulfide and lower dissolved oxygen in bottom seawater of Yunho pond might affect the growth of cultured prawn.

• Journal of Korea Port Economic Association
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• v.30 no.2
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• pp.113-132
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• 2014

With the global warming phenomenon, the deep sea water area that fishing vessels can enter and operate is ever widening. For example, the Arctic Ocean recently has overall competitive advantages due to having many deep-sea fish stocks. The North Pacific region is a strategic coastal district, the closest access point of Arctic Ocean. For Korean fishing vessels which now operate in North Pacific region, and want to entry the Arctic Ocean, the analysis of technical efficiency is needed for preparing the better industry's future. This paper aims to analyze the relative efficiency, and select the low effective deep-sea fishing vessels in the North Pacific, and to suggest their desirables strategies. As a research methodology, Data Envelopment Analysis (DEA) and Malmquist Index are applied to 16 fishing vessels for the periods(2009 to 2013). To draw out the efficiency of targeted deep-sea fishing vessels, gross tons, horsepowers, and operating days are used as input variables while total catch stands for an output variable. As a result, CCR efficiency, BCC efficiency and scalability efficiency are measured to be 0.8405, 0.9484 and 0.8858 respectively for 5 years (2009 to 2013). In conclusion, 38% of total tons, 36% of horsepowers and 29% of operating days each fishing vessel should be reduced to keep their competitive powers.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.106-112
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• 2014

Very few plant growth-promoting rhizobacteria (PGPR) are known to produce gibberellins (GAs). The current study aimed to isolate a phytohormone-producing PGP rhizobacterium from soil and assess its potential to enhance plant growth. The newly isolated bacterium was identified as Leifsonia soli sp. SE134 on the basis of partial 16S ribosomal RNA gene sequence. Application of L. soli culture filtrate significantly increased the biomass, hypocotyl, and root lengths of cucumber seeds as compared with non-inoculated sole medium and distilled water treated controls. Furthermore, the PGPR culture was applied to the GA-deficient mutant rice cultivar Waito-C. Treatment with L. soli SE134 significantly increased the growth of Waito-C rice seedlings as compared with controls. Upon chromatographic analysis of L. soli culture, we isolated, detected and quantified different GAs; namely, $GA_1$ ($0.61{\pm}0.15$), $GA_4$ ($1.58{\pm}0.26$), $GA_7$ ($0.54{\pm}0.18$), $GA_8$ ($0.98{\pm}0.15$), $GA_9$ ($0.45{\pm}0.17$), $GA_{12}$ ($0.64{\pm}0.21$), $GA_{19}$ ($0.18{\pm}0.09$), $GA_{20}$ ($0.78{\pm}0.15$), $GA_{24}$ ($0.38{\pm}0.09$), $GA_{34}$ ($0.35{\pm}0.10$), and $GA_{53}$ ($0.17{\pm}0.05$). Plant growth promotion in cucumber, tomato, and young radish plants further evidenced the potential of this strain as a PGP bacterium. The results suggest that GA secretion by L. soli SE134 might prove advantageous for its ameliorative role in crop growth. These findings can be extended for improving the productivity of different crops under diverse environmental conditions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.484-491
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• 2015

The productivity of Manila clam(Ruditapes philippinarum) aquaculture farm is closely related to suitable site selection, so it is essential to assess the habitat suitable for aquaculture species in order to manage yield. This study evaluated the habitat suitable index(HSI) with 9 sites for tidal flat farm, Gochang(Hajun) on May 2014. The suitability index was selected Growth(hydrodynamics, chlorophyll a), Survival(sediment-sand, silt-clay) and Water Environment(dissolved oxygen, salinity). Both Weight and No weight were tried for objective judgment as HSI scoring method. As a result, it shows lower tidal flat(HSI; No weight: 0.60~0.76, Weight: 0.47~0.70) is higher than upper(HSI; No weight: 0.25~0.27, Weight: 0.09~0.10), hydrodynamics and sediment particle size are the most effective. This research can consider the potential suitable site for Manila clam through scientific approach, and provide the basis for optimal management practices in tidal flat farm.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.1
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• pp.71-77
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• 2013

The world demand of renewable bioenergy as an alternative transportation fuel is greatly increasing. Research for bioethanol production is currently being progressed intensively throughout the world. Therefore it will be necessary to develop bioethanol production with cellulosic materials. In this study, the yield of ethanol production was evaluated by simultaneous saccharification and fermentation (SSF) using sodium hydroxide pretreated sorghum ${\times}$ sudangrass hybrids. Composition analysis of 11 varieties of sorghum ${\times}$ sudangrass hybrids was performed for selection of excellent variety to efficiently produce bioethanol. The content of cellulose, hemicellulose, lignin and ash of these varieties were 32~39%, 19~24%, 17~22% and 6~11%, respectively. Among these varieties, 4 varieties of sorghum ${\times}$ sudangrass hybrids were selected for the evaluation of ethanol yield and those were pretreated with 1 M NaOH solution at $150^{\circ}C$ for 30 min using high temperature explosion system. After pretreatment, samples were neutralized with tap water. It contained 52~57% of cellulose. Simultaneous saccharification and fermentation (SSF) was carried out for 48 h at $33^{\circ}C$ by Saccharomyces cerevisiae CHY1011 using Green star variety. The yield of ethanol was 92.4% and the amount of ethanol production was estimated at 6206 L/ha.

• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.30-37
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• 2015

BACKGROUND: During the winter, the use of deicers was rapidly increased for reduction of traffic accidents as well as injuries in Korea, whose components are largely comprised of calcium chloride and sodium chloride. Recently, to reduce the adverse effects of chloride-deciers such as pollution of water and soil, and decrease of agricultural productivity, the attention of eco-friendly deciers have been increased. This study aimed to investigate biological effects of magnesium chloride deicer (PC-10) and organic acid deicer (EFD-1) against wheat, barley, and spinach. METHODS AND RESULTS: We examined the effect of two deciers, PC-10 and EFD-1 on the seed germination and growth of wheat, barley and spinach. EFD-1 showed higher suppression of the germination than PC-10 among tested crop seeds. In demage index of the seedlings of the crops, there was no symptoms in spinach such as spotting and color change of leaves. EFD-1 showed much stronger inhibitory effect on the germination of tested crop seeds than PC-10 when crops were exposed continuously to tested deciers in soils. The growth and shoot and root in examined crops was relatively higher in PC-10 treatment than in EFD-1 treatment when compared to the control. The biomass decrease was found in all examined conditions of deciers. PC-10 showed 23-35% reduction of biomass whereas EFD-1 exhibited 39-84% loss in all examined crops at over 2% concentration. CONCLUSION: These results suggest that the effects of deicers used in this study by inputting into soil against growing tested crops cause the reduction of germination of seeds, growth, and biomass compared to the control.

• Korean Journal of Poultry Science
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• v.42 no.3
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• pp.205-214
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• 2015

This study aimed to investigate the effects of reducing feed intake on performance and meat quality in old laying hens. A total of 200 Hy-Line Brown laying hens (100 weeks old) were randomly allotted to five dietary treatments: control (100% daily feed intake), 90%, 60%, 50%, and 20% daily feed intake. Each treatment was replicated four times with 10 birds per replication and two birds per cage. Ten-bird units were arranged according to a randomized block design. The feeding trial lasted for 4 weeks under a 16L:8D lighting regimen. The results indicated that the daily feed intake correlated with hen-day egg production and feed conversion ratios (P<0.05). The carcass yields and partial ratios were also correlated with daily feed intake (P<0.05). The levels of leukocytes (without basophils) were higher in the 50% and 20% daily feed intake groups than in the other groups. The concentrations of dry matter, crude ash, crude fat, and crude protein, water holding capacity, cooking loss, and fatty acids in the breast meat did not decrease as the daily feed intake decreased. In conclusion, reducing daily feed intake decreased laying performance and carcass yield but had no effect on breast meat quality.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.1
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• pp.55-63
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• 2001

N fertilizer recommendations to optimize with consideration to maximum crop yields, maximum profits, and minimum N losses to ground or runoff water, an advisory system. Nitrogen Expert System (NES), was developed. The system was to estimate the optimal rate of N fertilizer application cornfields in Illinois. NES was constructed using Smart Elements, a knowledge-based system that manages the expertise of human experts. NES was reinforced by addition of the effect of a productivity index (PI), soil organic matter content (SOM), and pre-sidedressing of nitrate concentration (PSNT) to the optimal N fertilizer recommendation. NES contains 49 rules, 1 class, 14 objects, and 2 properties. NES was successfully operated, showing N recommendations with inputs of three soil properties including PI, SOM, and PSNT. NES can reduce N loss to the environment, but adherence to the recommendations may also reduce farmers income. Therefore, NES will be more effective by evaluating both environmental damage assessment and other economic agricultural management parameters and other soil physico-chemical parameters.

• Journal of Climate Change Research
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• v.5 no.4
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• pp.277-284
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• 2014

Biochar application to soil is widely known to have effects of climate change mitigation and soil quality improvement. However, effects of biochar on soil ecosystem are not always positive and some biochars are reported to contain toxic materials which might influence soil ecosystem. In this context, this study aims to investigate behavioral changes of earthworms(Eisenia fetida, Eisenia andrei) in response to different application rates of biochar to artificial soil. Treatment included two types of biochars made from rice husk (RH_Char) and wastewater sludge (SL_Char) with 1% and 10% application rates, respectively. Avoidance test revealed that earthworms did not avoid SL_Char treatments at 1% and 10%, while they rather moved to the RH_Char treatments probably due to higher labile carbon content(Hot water extractable carbon) of the RH_Char. The HWC content of RH_Char was 4 times higher than that of the SL_Char. Results of reproduction test showed that the survival rates, number of juveniles and number of cocoons were not influenced by biochar application except for the treatment of SL_Char at 10% rate. In the SL_Char 10% treatment, fatality was approximately 3.3 times as high as the control and the number of cocoons was 1.3 times higher in the same treatment than the control, indicating that earthworms were under environmental stress. The possible explanation for the stress condition was related to higher Cd, Ni, Cr, and As contents in the SL_Char. Overall results imply that biochar application at low rate might not change earthworms' behavior for the short term, while the reproduction behavior might be negatively influenced under the high application rate.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.90-103
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• 2018

This paper presents the development of two ANN models which can predict an optimum production rate by controlling choke size in oil well, and gas injection rate in gas-lift well. The input data was solution gas-oil ratio, water cut, reservoir pressure, and choke size or gas injection rate. The output data was wellhead pressure and production rate. Firstly, a range of each parameters was decided by conducting sensitive analysis of input data for onshore oil well. In addition, 1,715 sets training data for choke size decision model and 1,225 sets for gas injection rate decision model were generated by nodal analysis. From the results of comparing between the nodal analysis and the ANN on the same reservoir system showed that the correlation factors were very high(>0.99). Mean absolute error of wellhead pressure and oil production rate was 0.55%, 1.05% with the choke size model, respectively. And the gas injection rate model showed the errors of 1.23%, 2.67%. It was found that the developed models had been highly accurate.