• Fisheries and Aquatic Sciences
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• v.24 no.4
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• pp.139-152
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• 2021

The main purpose of this study is to fit catch-per-unit-effort (CPUE) data about Korea chub mackerel (Scomber japonicus) stock with a state-space production (SSP) model, and to provide stock assessment results. We chose a surplus production model for the chub mackerel data, namely annual yield and CPUE. Then we employed a state-space layer for a production model to consider two sources of variability arising from unmodelled factors (process error) and noise in the data (observation error). We implemented the model via script software ADMB-RE because it reduces the computational cost of high-dimensional integration and provides Markov Chain Monte Carlo sampling, which is required for Bayesian approaches. To stabilize the numerical optimization, we considered prior distributions for model parameters. Applying the SSP model to data collected from commercial fisheries from 1999 to 2017, we estimated model parameters and management references, as well as uncertainties for the estimates. We also applied various production models and showed parameter estimates and goodness of fit statistics to compare the model performance. This study presents two significant findings. First, we concluded that the stock has been overexploited in terms of harvest rate from 1999 to 2017. Second, we suggest a SSP model for the smallest goodness of fit statistics among several production models, especially for fitting CPUE data with fluctuations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.269-274
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• 2009

Recently, the construction of Liquefied Natural Gas Carriers(LNGC) is being promoted larger and larger depending on long voyage. In 1950 years, $5,000m^3$ class of LNGC had been changed to $71,500m^3$ class in 1973. and to $210,000-266,000m^3$ class in 2007. Especially, the system of main engines and cargo control, Re-liquefaction of natural gases have become possible in LNGC. This research deals with the LNG projects, world markets of energy and developing tendency of liquefied natural gas carriers.

• Journal of Crop Science and Biotechnology
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• v.11 no.3
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• pp.193-198
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• 2008

To develop a natural re-seeding technology, the optimum soil incorporation time of Chinese milk vetch(CMV) plant residues, seed persistence in soil, biomass production and subsequent rice yield were determined from 2005 to 2007 in rice with CMV green manure in southern Korea. Generally, insufficient seedling stand was regenerated with CMV incorporation to the soil at 20 and 25 days after flowering(DAF), while high regeneration of greater than 400 seedlings per $m^2$ was observed at 35 and 40 DAF. High re-seeding stand of CMV incorporated at 35 DAF or later was related with high seed viability and heavy seed weight. Appreciable number of CMV seeds remained 4 month after burial in soil and a good number of CMV seedlings regenerated from this seed bank at rice harvest time in the fall. Based on the relationships among re-seeding number of CMV plants, seed weight and seed viability, CMV plants should be incorporated into the soil 35 DAF(May 30) or later when CMV seeds were sufficiently matured. The natural re-seeding stand for the 3-year trials was stable ranging from 437 to 700 plants per $m^2$ and the biomass production was sufficient to supply nitrogen for rice growth. The use of re-seeding CMV plant can produce similar rice yield like that of rice without CMV green manure.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.5
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• pp.415-420
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• 2018

The development of sail gas has increased the production of ethane as well as natural gas. The decline in the market price for ethane has led to a change in the petroleum-based ethylene production process into an ethane-based ethylene production process and an increase in the ethane/ethylene trade volume. Large-scale ethane/ethylene carrier have been needed due to an increase in long-distance trade from the US, and cargo type change have leaded to consider a liquefaction process to re-liquefy Boil-Off gas generated during the voyage. In this paper, the liquefaction system of Liquefied Ethane Gas carrier was evaluated with Low-GWP (Low-Global Warming Potential) refrigerant and process parameters, Boil-Off Gas pressure and expansion valve outlet pressure, were optimized. Low-GWP refrigerants were propane (R290), propylene(R1270), carbon dioxide(R744) was considered at two type of liquefaction process such as Linde and cascade cycle. The results show that the optimal pressure point depends on the individual refrigerant and the highest liquefaction efficiency of carbon dioxide (R744) - propane (R290) refrigerant.

• Natural Product Sciences
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• v.10 no.3
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• pp.134-139
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• 2004

In this study, an immunoactivity of panaxtriol ginsenosides Re and Rg1 against infection due to Candida albicans was investigated. The ginsenosides were extracted from Red Ginseng with 85% ethanol and heat-treatment and were analyzed by HPLC on water-acetonitrile as a mobile phase. The HPLC analysis revealed that the extract contained ginsenosides Re and Rg1, which were eluted as a combined peak. By agar diffusion susceptibility, the mixture of Re and Rg1 had no growth-inhibitory activity on C. albicans yeast cells. However, in animal tests BALB/c mice given the mixture of Re and Rg1 intraperitoneally (Lp.) before intravenous (Lv.) infection with live C. albicans yeast cells had longer mean survival times (MST) than MST of control mice groups that received only buffer solution instead of Re and Rg1. In experiments 60% of the ginsenosides-treated mice survived the entire duration of the 50-day observation. The Re and Rg1 mixture induced production of nitric oxide when interacted with RAW 264.7 macrophage cell line. In addition, the mixture caused morphological change of the macrophages. These data indicate that immunostimulation by the Re and Rg1 may be responsible for the protection of mice against disseminated candidiasis.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.1-7
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• 2018

We aimed to develop a high quality 3.5 ton class swing reducer by studying the efficiency improvement of the reducer through the optimum design and performance evaluation of the assembled, high efficiency, lightweight 3.5 ton swing reducer. Based on the optimal design of the worm and worm wheel, the optimal manufacturing method of the worm wheel, the optimized casing design, and the optimum design of the output pinion, Respectively. Therefore, in this paper, to improve the efficiency of the worm gear reducer system, we will develop the manufacturing technology and verify the mass production by combining the manufacturing process design, processing and assembling technology according to the optimization design. We have conducted research to realize mass production by product verification such as product efficiency, reliability and durability according to optimal design of worm gear reducer.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.235-235
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• 2015

This study investigates the impact of event characteristics on runoff dynamics during extreme flood events observed in a $8.5km^2$ experimental watershed located in South Korea. The 37 most extreme flood events with event rainfall in excess of 50 mm were analysed using an event-based rainfall-runoff model; the Revitalised Flood Hydrograph (ReFH) routinely used for design flood estimation in the United Kingdom. The ReFH model was fitted to each event in turn, and links were investigated between each of the two model parameters controlling runoff production and response time, respectively, and event characteristics such as rainfall depth, duration, intensity and also antecedent soil moisture. The results show that the structure of the ReFH model can effectively accommodate any nonlinearity in runoff production, but that the linear unit hydrograph fails to adequately represent a reduction in watershed response time observed for the more extreme events. By linking the unit hydrograph shape directly to rainfall depth, the consequence of the observed nonlinearity in response time is to increase design peak flow by between 50% for a 10 year return period, and up to 80% when considering the probable maximum flood (PMF).

• Journal of Industrial Technology
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• v.36
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• pp.23-31
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• 2016

This paper presents EMQ models in which some proportion of defective items are produced and some of them are converted to good items through rework process and items not converted are disposed. Numerical models are developed for three cases of disposal and optimal solution of each model is derived. In the first model, if a defective item is found during the production process, only re-workable items are stored and reworked after normal production is finished. Not re-workable items are disposed immediately during normal production. The second model deals with the case where all defective items are stored and items to be disposed are determined in rework process. In the third model, an additional inspection process exists before rework to determine rework or disposal. Numerical examples are presented to validate the proposed models.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.290-291
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• 2001

The relationship between velocity, viscosity, diffusion coefficient, mass transfer coefficient and characteristic length and mass transfer data can be correlated by dimensionless relationship in electrolytic process. The performance of dyestuff removal was decreased as the flow rate of electrolyte was increased. It was due to the effect of retention time decreasing was superior to that of turbulent inlet mixing. Sh/Sc$\^$1/3/ vs Re plot for Al flat electrode did not showed the general tendency of the relationship between Sh/Sc$\^$1/3/ and Re. It can be thought that flow rate was not sufficiently high to increase the effect of mixing.

• YAKHAK HOEJI
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• v.42 no.3
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• pp.296-301
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• 1998

To investigate the effects of ginsenosides from Panax ginseng on mitogenic responses in macrophages and splenocytes from murine, we examined the effects of representative protopanaxadiol and protopanaxatriol ginsenosides ($Rb_1,\;Rb_2,\;Re\;and\;Rg_1$) on tumor necrosis factor-${\alpha}$ (TNF-(${\alpha}$) production in murine macrophage cell line (RAW264.7 cells) stimulated by lipopolysaccharide (LPS) and T cell proliferation in splenocytes stimulated by concanavalin A (Con A). Among the ginsenosides tested, protopanaxadiol ginsenosides ($Rb_1\;and\;Rb_2$) significantly inhibited TNF-${\alpha}$ production in a dose-dependent manner. However, protoppanaxatriol ginsenosides (Re and $Rg_1$) showed little inhibitory activity. The molar concentrations of $Rb_1\;and\;Rb_2$ producing 50% inhibition ($IC_{50}$) of TNF-${\alpha}$ production were $55.8{\mu}g/ml\;(48.0{\mu}M)\;and\;31.8{\mu}g/ml (27.9{\mu}M)$, respectively. As a positive control, prednisolone also exhibited inhibitory activity with an $IC_{50}$ value of $21.7{\mu}M$. In T cell proliferation, $Rg_1$, was not effective but $Rb_1$ and Re or $Rb_2$ significantly increased or inhibited at high concentration, 75 and $100{\mu}g/ml$. In contrast, prednisolone showed potent inhibitory activity with an $IC_{50}$ value of 6.1nM. These results suggest that ginsenosides may take part in the mitogen-induced signaling pathway for TNF-${\alpha}$ production and T cell proliferation from macrophages and splenocytes.