• Journal of Ocean Engineering and Technology
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• v.25 no.6
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• pp.1-8
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• 2011

This paper describes a new method for a digital gas metal arc welding (GMAW) system. The GMAW system is an arc welding process that incorporates the GMAW power source (PS-GMAW) with a wire feed unit (WFU). The PS-GMAW requires an electric power of constant voltage. A constant magnitude is maintained for the arc current by controlling the wire-feed speed of the WFU. A mathematical model is derived, and a self-tuning fuzzy proportional-integral-derivative (PID) controller is designed and applied to control the welding current. The electrode wire feeding mechanism with this controller is driven by a DC motor, which can compensate for both the molten part of the electrode and undesirable fluctuations in the arc length during the welding process. By accurately maintaining the output welding current and welding voltage at constant values during the welding process, excellent welding results can be obtained. Simulation and experimental results are shown to prove the effectiveness of the proposed controller.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.253.1-253.1
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• 2014

Plasma technology has been widely used for decontamination, differentiation, and disease treatment. Recently, studies show that plasma has effects on increasing seed germination and plant growth. In spite of increasing number of studies about plasma effects, the interaction between plasma and plants has been rarely informed. In this study, we have analyzed the effects of nonthermal atmospheric pressure plasma on seed germination and growth of coriander (Coriandum sativum), a medicinal plant. We used to Ar, air, and N2 plasma on seed as feeding gases. Plasma was discharged at 0.62 kV, 200 mA, 9.2 W. Seed germination was increased over time when treated with N2 based DBD plasma for exposure times of 30 seconds and 1 minute, everyday. After 7 days, about 80~100% of seeds were germinated in the treatment with N2 based DBD plasma, compared to control (about 40%, only gas treated seeds). In order to elucidate the mechanism of increased germination, we have analyzed characteristics of changes in plant hormones and seed surface structure by SEM.

• Journal of the Korean Applied Science and Technology
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• v.6 no.1
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• pp.1-7
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• 1989

To developed new process for obtaining maximum molecular weight of anionic acrylamide and acrylic acid copolymer by inverse emulsion polymerization. Concentration of initiator, reducing agent, surfactant and mole ratio of acrylamide-acrylic acid were studied for the process. Semi-batch processes with method of redox, control of reaction temperature, feeding method of monomer and reaction time, was suitable for maximum molecular weight of P(AMAC) from this process obtained $3.09\;{\time}\;10^6({\bar{M}}n.)$ and $4.41\;{\time}\;10^6({\bar{M}}w.)$ in molecular weight measured by the intrinsic viscosity method. inverse emulsion polymerization mechanism of P(AMAC) does not followed the Smith-Ewart and Medvedev theory, but selected for concentration of initiator, reducing agent, surfactant, water solubility of monomer.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.6
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• pp.1576-1580
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• 2007

Aralia cordata Thunb. (Araliaceae, ACT) is an remarkable herbal plant that has been widely used in traditional oriental medicine for the treatment of inflammatory diseases and cardiovascular disorders. In this study, we have established a vascular aging model in rats by orally administrating excessive vitamin $D_2$ (500,000 IU/kg/day) for 4 days followed by feeding high cholesterol diet for 16 weeks and then rats were randomly divided into control group, high cholesterol diet (HCD) group, HCD+ACT (30 mg/kg) and HCD+ACT (60 mg/kg) group. ACT (30, 60) significantly reduced total cholesterol (TC) content compared with HCD, but no significant differences in the serum lipids. Secondly, we measured the serum levels of Oxidized Low-dencity Lipoprotein (OxLDL) and malondialdehyde (MDA) in order to further investigate the anti-vascular aging mechanism of ACT. The results, ACT (30, 60) treatments decreased OxLDL, MDA　content　and increased Cu/Zn superoxide dismutase activity compared with HCD treatments. The results suggested that ACT inhibited OxLDL production rather than serum lipids lowering and that ACT could be used as potential anti-atherosclerotic agent in aged cells.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.68-74
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• 2007

Critical Chain Project Management(CCPM) is a new project management system paradigm which maintains the advantages of PERT/CPM and improves the shortcomings of it. In CCPM the task durations are determined as 50% time estimates, ie average time discarding the their contingency. CCPM determines the critical chain the constraint of a projects considering the logical precedence relationship and resource conflict resolution. Project buffer is located at the end of critical chain to absorb the variations of critical chain. The size of project buffer is usually calculated as the half of the sum of critical chain length. Also feeding buffer is inserted after each non-critical chain which feeding into the critical chain to prevent the time delay of critical chain from uncertainties of non-critical chains. Resource buffer can be utilized to improve the availability of resources of critical chain. Buffer management is a project execution and control mechanism. Buffers are classified into 3 zones. They are OK zone, Watch and Plan zone and Expediting zone. If the project status is within Watch and Plan zone, contingency plan is established. And if it changes into Expediting zone, the preplanned contingency plan are executed to recover the time delay. In CCPM the workers are asked to work with relay runner work mechanism that they work fast if possible and report their completion to project manager for the succeeding task to start as soon as possible. The task durations are not considered as the promised time schedule. The multi-tasking is prohibited.

• Korean Journal of Ecology and Environment
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• v.49 no.2
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• pp.67-79
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• 2016

Cyanotoxins in aquatic ecosystems have been investigated by many researchers worldwide. Cyanotoxins can be classified according to toxicity as neurotoxins (anatoxin-a, anatoxin-a(s), saxitoxins) or hepatotoxins (microcystins, nodularin, cylindrospermopsin). Microcystins are generally present within cyanobacterial cells and are released by damage to the cell membrane. Cyanotoxins have been reported to cause adverse effects and to accumulate in aquatic organisms in lakes, rivers and oceans. Possible pathways of microcystins in Lake Suwa, Japan, have been investigated from five perspectives: production, adsorption, physiochemical decomposition, bioaccumulation and biodegradation. In this study, temporal variability in microcystins in Lake Suwa were investigated over 25 years (1991~2015). In nature, microcystins are removed by biodegradation of microorganisms and/or feeding of predators. However, during water treatment, the use of copper sulfate to remove algal cells causes extraction of a mess of microcystins. Cyanotoxins are removed by physical, chemical and biological methods, and the reduction of nutrients inflow is a basic method to prevent cyanobacterial bloom formation. However, this method is not effective for eutrophic lakes because nutrients are already present. The presence of a cyanotoxins can be a potential threat and therefore must be considered during water treatment. A complete understanding of the mechanism of cyanotoxins degradation in the ecosystem requires more intensive study, including a quantitative enumeration of cyanotoxin degrading microbes. This should be done in conjunction with an investigation of the microbial ecological mechanism of cyanobacteria degradation.

• Agricultural and Biosystems Engineering
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• v.4 no.1
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• pp.8-15
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• 2003

In Korea, quality evaluation of dried oak mushrooms are done first by classifying them into more than 10 different categories based on the state of opening of the cap, surface pattern, and colors. And mushrooms of each category are further classified into 3 or 4 groups based on its shape and size, resulting into total 30 to 40 different grades. Quality evaluation and sorting based on the external visual features are usually done manually. Since visual features of mushroom affecting quality grades are distributed over the entire surface of the mushroom, both front (cap) and back (stem and gill) surfaces should be inspected thoroughly. In fact, it is almost impossible for human to inspect every mushroom, especially when they are fed continuously via conveyor. In this paper, considering real time on-line system implementation, image processing algorithms utilizing artificial neural network have been developed for the quality grading of a mushroom. The neural network based image processing utilized the raw gray value image of fed mushrooms captured by the camera without any complex image processing such as feature enhancement and extraction to identify the feeding state and to grade the quality of a mushroom. Developed algorithms were implemented to the prototype on-line grading and sorting system. The prototype was developed to simplify the system requirement and the overall mechanism. The system was composed of automatic devices for mushroom feeding and handling, a set of computer vision system with lighting chamber, one chip microprocessor based controller, and pneumatic actuators. The proposed grading scheme was tested using the prototype. Network training for the feeding state recognition and grading was done using static images. 200 samples (20 grade levels and 10 per each grade) were used for training. 300 samples (20 grade levels and 15 per each grade) were used to validate the trained network. By changing orientation of each sample, 600 data sets were made for the test and the trained network showed around 91 % of the grading accuracy. Though image processing itself required approximately less than 0.3 second depending on a mushroom, because of the actuating device and control response, average 0.6 to 0.7 second was required for grading and sorting of a mushroom resulting into the processing capability of 5,000/hr to 6,000/hr.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.8
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• pp.1072-1079
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• 2013

The NLRP12 (NLR family, pyrin domain containing 12) serves as a suppressor factor in the inflammatory response and protects the host against inflammation-induced damage. In the present study, we aimed to study the polymorphisms of NLRP12 gene and its association with susceptibility to non-specific digestive disorder (NSDD) in rabbits. We re-sequenced the entire coding region of the rabbit NLRP12 gene and detected a total of 19 SNPs containing 14 synonymous and five non-synonymous variations. Among them, the coding SNP (c.1682A>G), which would carry a potential functional implication, was subsequently subjected to genotyping for case-control association study (272 cases and 267 controls). The results revealed that allele A was significantly protective against NSDD with an odds ratio value of 0.884 (95% confidence interval, 0.788 to 0.993; p = 0.038). We also experimentally induced NSDD in growing rabbits by feeding a fibre-deficient diet and subsequently investigated NLRP12 mRNA expression. The mRNA expression of NLRP12 in healthy status was significantly higher than that in severe NSDD (p = 0.0016). The highest expression was observed in individuals carrying the protective genotype AA (p = 0.0108). These results suggested that NLRP12 was significantly associated with the NSDD in rabbits. However, the precise molecular mechanism of NLRP12 involving in the development of rabbit NSDD requires further research.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.8
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• pp.1049-1056
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• 2010

This study was conducted to investigate the effects of dietary glutamine (Gln) on the productive performance and egg quality of laying hens. A total of four hundred Lingnan Yellow laying hens aged 34 weeks were randomly assigned into four groups (100 laying hens/group), and fed, respectively, with diets supplemented with 0% (control group), 0.2%, 0.4%, and 0.8% Gln during the 6-week feeding period. The results were as follows. First, the productivity of laying hens fed with 0.8% Gln in diet was significantly increased (p<0.05); however, the egg quality (egg weight, yolk weight, shell weight, egg shape index, shell thickness, shell density, shell breaking strength, yolk color, yolk index, and Haugh unit) was not affected compared with that of the control group (p>0.05). Second, luteinizing hormone (LH) (p<0.01), follicle stimulating hormone (FSH) (p<0.01), triiodothyronine ($T_3$), and tetraiodothyronine ($T_4$) contents (p<0.05) in blood of laying hens fed with 0.8% Gln in diets were also significantly improved, and greater improvement in the duodenum and oviduct structure was observed in that treatment group. This study indicated for the first time that diets with 0.8% Gln were able to increase the productive performance of laying hens through stimulating hormone secretion and better development of both the duodenum and oviduct structure in laying hens.

• IMMUNE NETWORK
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• v.3 no.3
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• pp.248-254
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• 2003

Oral administration of antigen has long been used in the induction of immune tolerance in various animal models of autoimmune diseases including rheumatoid arthritis (RA). Alleveation of arthritogenic symptoms has been reported from RA patients who received oral administration of type II collagen (CII) without side effects, however its rather inconsistent therapeutic efficacy and variation among patients calls for more detailed investigation on the mechanism of oral tolerance to be settled as regular treatment for RA. In an attempt to understand the immunogenic processes underpinning tolerance induction by orally administered CII, we analyzed changes in the expression of costimulatory molecules and STAT/SOCS signaling messengers in the mouse model of collagen induced arthritis (CIA). We found thatin the spleen of CIA mice, that has been undergone repeated oral feeding of CII prior to the induction of arthritis, showed increased promortion of CTLA4 expressing lymphocytes than in the spleen of PBS fed control. On the other hand, cells expressing CD28 or ICOS were decreased in the spleen of tolerized mice. Tolerance induction by oral CII administration also enhanced the expression of STAT6 in both RNA and protein level, while not affecting the expression of STAT3. The expression of SOCS3, which hasbeen known to transmit STAT-mediated signals from Th2 type cytokines, remained unchanged in the spleen of tolerized mice. Interestingly transcript of SOCS1, which has been associated with Th1 related pathways, was only visible in the spleen of tolerized but not of control mice, suggesting that as in the case of IL-6 signaling, it may exert a feed back inhibition toward the Th1 type stimulation.