• The Journal of shipping and logistics
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• v.34 no.4
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• pp.545-563
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• 2018

This study analyzes the major factors affecting the freight rates of Very Large Crude-Oil Carriers (VLCC) using co-integration and vector error correction models (VECM). Particularly, we estimate the long-term equilibrium function that determines the VLCC freight rate by conducting difference conversion. In the VECM regression analysis, the error term converges toward long-term balance irrespective of whether the previous period's freight rate is bigger or smaller than the long-term equilibrium rate. Thus, even if the current rate is different from the long-term rate, it eventually converges to the long-term balance irrespective of a boom or recession. This study follows Ko and Ahn (2018), which analyzed the factors affecting the chemical carrier freight rate and was published in the Journal of Shipping and Logistics (Vol. 34, No. 2). It is expected that an academic comparison of the results of each study will be possible if further research is conducted on other vessel types, such as container ships and dry cargo vessels.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.4
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• pp.304-312
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• 2002

In this study, the performance of the $5Nm^3/hr$ compact type steam reformer which was developed for application of fuel cell or hydrogen station was evaluated in terms of gas process efficiency. For these purposes, reforming efficiency and total efficiency with system load change were analyzed. The reforming efficiency was calculated from the total molar flow of hydrogen output over total fuel flow input to the reformer and the burner on the higher heating value(HHV). In the case of the total efficiency, recovered heat at the heat recovery exchanger was considered. From the results, it was known that system performance was stable, because methane conversion showed the a slight decline which is about 2% though increasing system load to full. Reforming efficiency was increased from 20% to 58%, respectively as increasing system load from 10% to 90%. It was found that total efficiency was higher then reforming efficiency because of terms of heat recovered. As a results, it was known that total efficiency was increased form 75% to 83% at the 10% and 90% system load, respectively. From these results, it is concluded that compact steam reformer which is composed of stacking plate-type reactors is suitable to on-site hydrogen generator or to fuel cell application because of quick start within 1 hr and good performance.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.2
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• pp.185-191
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• 1997

This experiment was conducted to determine the effects of a low-protein diet supplemented with DL-methionine plus L-cystine (Met + Cys) on the growth performance and fat accumulation of female broiler chicks during the growing period (3-6 wks old). A low-protein diet (17% CP; 3,200 ME kcal/kg) was supplemented with Met + Cys (1.1 : 1.0) at levels 0.75, 0.94, 1.25, 1.31 or 1.50% of diet, respectively. Another diet with 21% CP and 3,200 ME kcal/kg served as the control group. All essential amino acids were adjusted to meet the National Research Council (1984) requirement for chicks. Feed and water were given ad libitum. Body weight of the chicks fed the low-CP diets supplemented with Met + Cys were heavier than those of the control birds. Feed conversion ratio and feed intakes were not significantly different between and among the treatment groups. Similary, abdominal fat content was not significantly different among the various treatments except that of the chicks fed the low CP diet with 1.25% Met + Cys which was higher than that of the control group. Fatty acid synthetase (FAS), acetyl-CoA carboxylase (ACC) activities and carcass protein content were not influenced by dietary treatments. Carcass fat content was lowest in chicks fed low CP diet with 0.75% Met + Cys and highest in the group that received 1.50% Met + Cys supplementation. Liver triglyceride increased as Met + Cys supplementation level increased. Various lipid fraction concentrations (cholesterol ester, free cholesterol, and phospholipid) in the serum went up as Met + Cys increased up to 1.25% after which it levelled off. Results of this experiment suggest that it is possible to reduce dietary protein level from 21% to 17% for growing broiler chicks by the supplementation of Met + Cys when other EAA were sufficient.

• Journal of Animal Science and Technology
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• v.64 no.2
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• pp.312-329
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• 2022

Feed cost is the main factor affecting the economic benefits of pig industry. Improving the feed efficiency (FE) can reduce the feed cost and improve the economic benefits of pig breeding enterprises. Liver is a complex metabolic organ which affects the distribution of nutrients and regulates the efficiency of energy conversion from nutrients to muscle or fat, thereby affecting feed efficiency. MicroRNAs (miRNAs) are small non-coding RNAs that can regulate feed efficiency through the modulation of gene expression at the post-transcriptional level. In this study, we analyzed miRNA profiling of liver tissues in High-FE and Low-FE pigs for the purpose of identifying key miRNAs related to feed efficiency. A total 212~221 annotated porcine miRNAs and 136~281 novel miRNAs were identified in the pig liver. Among them, 188 annotated miRNAs were co-expressed in High-FE and Low-FE pigs. The 14 miRNAs were significantly differentially expressed (DE) in the livers of high-FE pigs and low-FE pigs, of which 5 were downregulated and 9 were upregulated. Kyoto Encyclopedia of Genes and Genomes analysis of liver DE miRNAs in high-FE pigs and low-FE pigs indicated that the target genes of DE miRNAs were significantly enriched in insulin signaling pathway, Gonadotropin-releasing hormone signaling pathway, and mammalian target of rapamycin signaling pathway. To verify the reliability of sequencing results, 5 DE miRNAs were randomly selected for quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The qRT-PCR results of miRNAs were confirmed to be consistent with sequencing data. DE miRNA data indicated that liver-specific miRNAs synergistically acted with mRNAs to improve feed efficiency. The liver miRNAs expression analysis revealed the metabolic pathways by which the liver miRNAs regulate pig feed efficiency.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.10
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• pp.1407-1413
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• 2009

An experiment was conducted to investigate the effects of dietary supplementation of feather meal (FM) on the performance of pigs and taurine content in pork. A total of 135 cross-bred (L${\times}$Y${\times}$D) pigs, weighing an average 46 kg, were assigned to five dietary treatments; Control, 3% FM supplemented diet (3% FM), 3% FM and 10 ppm pyridoxin supplemented diet (3% FMpyridoxin), 6% FM supplemented diet (6% FM) and 6% FM and 10 ppm pyridoxine supplemented diet (6% FM-pyridoxin). Each treatment had 3 replications of 9 pigs (4 gilts and 5 barrows) each. Pigs were fed for 11 weeks under a phase feeding program which consisted of grower (0-3 week), grow-finisher (4-8 week) and finisher (9-11 week) periods. During the whole feeding period, ADG and ADFI of pigs fed FM treatments tended to increase in general compared to the control. Feed conversion ratio (feed/gain) of the control was significantly (p<0.05) lower than FM treatments. Taurine content of the control was highest in heart muscle (1,393.8 ppm) followed by liver (647.3 ppm), tenderloin (601.2 ppm), ham (462.4 ppm) and loin (375.8 ppm). Taurine contents of heart, tenderloin, ham and loin were significantly (p<0.05) increased by FM treatments. Taurine content was highest in the 6% FM-pyridoxin treatment. Taurine content of heart, tenderloin, ham and loin on 6% FM-pyridoxin supplementation were increased by 91%, 23%, 27% and 29%, respectively, compared with the control. Sensory tests of the pork showed that there was no consistent response among the treatments. In conclusion, supplementation of FM and pyridoxin to a pig diet can increase taurine content of the pork.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.44-52
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• 2024

This study presents a novel approach to hydrogen production by biogas from organic waste without CO₂ removal. A process model was developed to reduce the costs associated with biogas pretreatment and purification processes. Through optimization of heat exchange networks, the simulation aimed to minimize process costs, maximizing hydrogen production and flue gas temperature. The results reveal that the most efficient process model maximizes the flue gas temperature while following the constraint of the number of heat exchangers. These findings hold promise for contributing to the expansion of "Biogas-to-clean hydrogen" energy conversion technology.

• Journal of Bio-Environment Control
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• v.13 no.4
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• pp.266-270
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• 2004

A rose factory type is a system that enables year-round, planned and mass production of high quality cut-rose. Conversion of a conventional system to a rose factory is essential to increase cut-rose export. Controlling root Bone in culled rose production factory is very important for economic and efficient production of rose. This study was conducted to determine optimum root zone temperature of nutrient solution in single-stemmed rose production system. The optimum temperature of the nutrient solution for growth, photosynthetic and transpiration rates for 'Red Velvet' was $15\~20^{\circ}C$. Whereas the optimum temperature for 'Vital' was $10\~15^{\circ}C$. However, growth was almost sloped at $30^{\circ}C$, resulting in concluding the adaptation of 'Vital' to high temperature was poor as compared with 'Red Velvet'.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.347-351
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• 2013

The preparation of glycerol carbonate (GC) from urea through carbonylation with renewable glycerol was investigated by using ionic liquid catalysts. It was found that quaternary ammonium salt and imidazolium salt ionic liquids with a shorter alkyl chain length and higher nucleophilic anion showed better catalytic performance. The effects of reaction temperature, reaction time and degree of vacuum on the reactivity of TBAC catalyst ware discussed. Zinc chloride ($ZnCl_2$) was used as co-catalyst with the ionic liquid catalyst. The mixed catalyst showed a synergy effect on the glycerol conversion and GC yield probably due to the acid-base properties of the catalysts.

• Journal of the Korean Solar Energy Society
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• v.29 no.1
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• pp.44-49
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• 2009

Steam reforming of methane in the high temperature solar chemical reactor bas advantage in its heating method. Using concentrated solar energy as a heating source of the reforming reaction can reduce the $CO_2$ emission by 20% compared to hydrocarbon fuel. In this paper, the simulation result of methane-steam reforming on a high temperature solar chemical reactor(SCR) using Fluent 6.3.26 is presented. The high temperature SCR is designed for the Inha Dish-1, a Dish type solar concentrator installed in Songdo city. Basic SCR performance factors are referred to the former researches of the same laboratory. Inside the SCR porous metal is used for a receiver/reactor. The porous metal is carved like a dome shape on the incident side to increase the heat transfer. Also, ring-disc set of baffle is inserted in the porous metal region to increase the path length. Numerical and physical models are also used from the former researches. Methane and steam is mixed with the same mole fraction and injected into the SCR. The simulation is performed for a various inlet mass flow rate of the methane-steam mixture gas. The result shows that the average reactor temperature and the conversion rate change appreciably by the inlet mass flow rate of 0.0005 kg/s.

• Clean Technology
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• v.20 no.3
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• pp.330-336
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• 2014

Mg-Al mixed oxides with molar ratio of Mg/Al = 1-3 were prepared by co-precipitation and characterized by using X-ray diffraction, scanning electron microscopy, BET surface area and pore volume measured by $N_2$ sorption analysis, and temperature programmed desorption of iso-propanol. As Al content in Mg-Al mixed oxide increased, the acidity and BET surface area proportionally increased. This increase of acidity directly influenced the catalytic activity of iso-propanol conversion and selectivity to propylene.