• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.372-379
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• 2023

International oil prices are expected to increase from $85 a barrel this year to up to $100 a barrel in the second half of the year; this is likely to increase orders for offshore plants in the global market. One main characteristic of offshore plants is that a large helideck is located on the top side, and aluminum alloys are used as the basic material of the structure for weight reduction and corrosion resistance. Shipowners are increasing the size of helicopters to quickly evacuate lives in the event of an emergency, and the safety use load of devices that can stably secure helicopters to the deck is also required to increase. Owing to the nature of the aluminum material, the structural strength caused by welding is greatly reduced; therefore, the fixing device must be designed by embedding it in the deck and fixing it with bolts. In this study, a model applying aluminum alloy 6082-T6 was developed to develop a helicopter fastening device that can be used for large helidecks (diameter = 28 m). The developed item was verified through nonlinear structural strength calculation to satisfy the load used for the actual fastening condition. The load condition with a 45° showed a lower ultimate strength than the 90° case owing to local plastic collapse. The nonlinear structural collapse behavior showed a result similar to that of the experimental test. The main contents derived from this study are considered to be reference materials when evaluating the structural strength of similar aluminum equipment.

• Applied Biological Chemistry
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• v.40 no.2
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• pp.134-138
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• 1997

The objective of this study was to examine the effect of phosphorus deficiency on nitrogen fixation and photosynthesis of nitrogen fixing soybean plant under $CO_2$ enrichment condition. The soybean plants(Glycine max [L.] Merr.) inoculated with Bradyrhizobium japonicum MN 110 were grown with P-stressed(0.05 mM-P) and control(1 mM-P) treatment under control$(400\;{\mu}l/L\;CO_2)$ and enrichment$(800\;{\mu}l/L\;CO_2)$ enviromental condition in the phytotron equipped with high density lamp$(1000\;{\mu}Em^{-2}S^{-1})$ and $28/22^{\circ}C$ temperature cycle for 35 days after transplanting(DAT). At 35 DAT, phosphorus deficiency decreased total dry mass by 64% in $CO_2$ enrichment condition, and 51% in control $CO_2$ condition. Total leaf area was reduced significantly by phosphorus deficiency in control and enriched $CO_2$ condition but specific leaf weight was increased by P deficiency. Phosphorus deficiency significantly reduced photosynthetic rate(carbon exchange rate) and internal $CO_2$ concentration in leaf in both $CO_2$ treatments, but the degree of stress was more severe under $CO_2$ enrichment condition than under control $CO_2$ environmental condition. In phosphorus sufficient plants, $CO_2$ enrichment increased nodule fresh weight and total nitrogenase activity(acetylene reduction) of nodule by 30% and 41% respectively, but specific nitrogenase activity of nodule and nodule fresh weight was not affected by $CO_2$ enrichment in phosphorus deficient plant at 35 DAT. Total nitrogen concentrations in stem, root and nodule tissue were significantly higher in phosphorus sufficient plant grown under $CO_2$ enrichment, but nitrogen concentration in leaf was reduced by 30% under $CO_2$ enrichment. These results indicate that increasing $CO_2$ concentration does not affect plant growth under phosphorus deficient condition and phosphorus stress might inhibit carbohydrate utilization in whole plant and that $CO_2$ enrichment could not increase nodule formation and functioning under phosphorus deficient conditions and phosphorus has more important roles in nodule growth and functioning under $CO_2$ enrichment environments than under ambient condition.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.262-269
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• 2013

Though focused ion beam (FIB) is one of the candidates to fabricate the nanoscale patterns, precision milling of nanoscale structures is not straightforward. Thus this poses challenges for novice FIB users. Optimal determination in FIB parameters is a crucial step to fabricate a desired nanoscale pattern. There are two main FIB parameters to consider, beam current (beam size) and dose (beam duration) for optimizing the milling condition. After fixing the dose, the proper beam current can be chosen considering both total milling time and resolution of the pattern. Then, using the chosen beam current, the metal nano hole structure can be perforated to the required depth by varying the dose. In this experiment, we found the adequate condition of $0.1nC/{\mu}m^2$ dose at 1 pA Ga ion beam current for 100 nm thickness perforation. With this condition, we perforated the periodic square array of elliptical nano holes.

• Journal of Technologic Dentistry
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• v.23 no.2
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• pp.179-188
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• 2002

With regard to the manufacture of dental prosthesis, all the dental mechanism is of vital significance at the aspect of activating its function by fixing the prosthesis to Patient's oral cavity. However, if there we will take our immediate action without the discretion about its process none the less for the importance of dental mechanism, then we might have a serious problem. Accordingly, there need to pay attention to the dilatability makes up for the shrinkage state occurring by the feature of metal materials and manufacturing process which appeared in the process of dental mechanism, which eventually is expected to playa very important role in casting a dental prosthesis appropriate to one's oral tissue. This study was designed to take into account of the effects on margin consistency of prosthesis according to the continued time of casting-ring in the course of the casting of dental alloy. For this, the researcher made an experiment on the casting of dental alloy, its dilatability, and the change of phase. The results of this study were as follows: First, the researcher could see that the sample which was cast under the condition of $650^{\circ}C/20$ Minutes(the continued time) was far superior to others at the aspect of margin consistency. Second, according to the measurement of expansion coefficient by Dilatometer, the researcher perceived the fact that the expansion-coefficient showed a maximum of $37.1{\mu}m$ considering the sample's length which was cast with ordinary temperature under the condition of $650^{\circ}C/20$ Minutes. Third, from the result of X-ray diffraction under the condition of $650^{\circ}C/20$ Minutes(the continued time), the researcher could find that there's no difference between the change of phase and its intensity. As mentioned above, the researcher could ascertain the fact that its contraction don't give rise to the change of phase.

• Journal of the Korean institute of surface engineering
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• v.52 no.4
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• pp.194-202
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• 2019

A systematic investigation was made on the influence of processing parameters such as gas composition and treatment temperature on the surface characteristics of hardened layers of low temperature plasma nitrided 316L Austenitic Stainless Steel. Various nitriding processes were conducted by changing temperature ($370^{\circ}C$ to $430^{\circ}C$) and changing $N_2$ percentage (10% to 25%) for 15 hours in the glow discharge environment of a gas mixture of $N_2$ and $H_2$ in a plasma nitriding system. In this process a constant pressure of 4 Torr was maintained. Increasing nitriding temperature from $370^{\circ}C$ to $430^{\circ}C$, increases the thickness of S phase layer and the surface hardness, and also makes an improvement in corrosion resistance, irrespective of nitrogen percent. On the other hand, increasing nitrogen percent from 10% to 25% at $430^{\circ}C$ decreases corrosion resistance although it increases the surface hardness and the thickness of S phase layer. Therefore, optimized condition was selected as nitriding temperature of $430^{\circ}C$ with 10% nitrogen, as at this condition, the treated sample showed better corrosion resistance. Moreover to further increase the thickness of S phase layer and surface hardness without compromising the corrosion behavior, further research was conducted by fixing the $N_2$ content at 10% with introducing various amount of $CH_4$ content from 0% to 5% in the nitriding atmosphere. The best treatment condition was determined as 10% $N_2$ and 5% $CH_4$ content at $430^{\circ}C$, where the thickness of S phase layer of about $17{\mu}m$ and a surface hardness of $980HV_{0.1}$ were obtained (before treatment $250HV_{0.1}$ hardness). This specimen also showed much higher pitting potential, i.e. better corrosion resistance, than specimens treated at different process conditions and the untreated one.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.6
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• pp.79-86
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• 2012

The aim of this general remarks is to introduce the results concerning the thermo physical, charging, developing and fusing characteristics of micro-encapsulated (MC) model toners in order to apply to the toner of electrophotographic system at the condition of a low temperature. In order to clarify the fusing mechanism of MC toner, rheological analysis of the toner was chosen. It was suggested that MC toner had a different fusing mechanism compared with non-MC toner. Some kinds of MC model toners showed a good result on adhesion test as well as cohesion test. Also, it was possible to get the good charging and development characteristic of MC toner for printing test with laser printer.

• Journal of the Korea Fashion and Costume Design Association
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• v.11 no.2
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• pp.169-181
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• 2009

The purpose of this study was to provide basic information for developing a smart taekwondo uniform with enhanced functionality for children by investigating the wearing condition and satisfaction of taekwondo uniform among taekwondo training children. The data were collected from 162 children living in Seoul and Daegu. For data analysis were performed descriptive statistics, ${\chi}2$ -test and t-test using SPSS Ver. 12. The results of the analysis are as follows. The results revealed that respondents wearing the general training uniform during their training period were the most. The dissatisfaction for the general training uniform was a high price, lack of symbolic, lack of functionality in textiles, lack of variety in design and unfittness of size in order. The developed uniform can adjust the length using a zipper type fastener, and can be used in all seasons as the lining is detachable. It also uses nano-silver material, and soil release finish. It enhances the functionality of movement by treating with raglan sleeve and sleeve hem velcro tape, and designs the upper garment in the draping. Safety is improved through attaching GPS, and elastic material is mixed in the neckline for putting on and off easily. Piece of cloth is added inside the closing of the upper garment. Rings are made for fixing the taekwondo uniform belt. Pocket is designed in the lower garment and colors are multiplied.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.593-601
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• 2012

Heavy metals and metalloids removal can be considered as one of the most important world challenges because of their toxicity and direct impact on human health. Many processes have been introduced but biological processes of remediation seem to offer the most suitable solution in terms of efficiency and low cost. Actinobacteria constitute one of the major microbial populations in soil, and this can be attributed to their adaptive morphological structure as well as their exceptional metabolic power. Among microbes, actinobacteria are morphologic intermediate between fungi and bacteria. Studies on microbial diversities in metal contaminated lands have shown that actinobacteria may constitute a dominantly active microbiota in addition to ${\alpha}$ Proteobacteria. Furthermore, isolation studies have shown metal removal mechanisms which are reminiscent of notable multiresistant strains, such as Cupriavidus metallidurans. Apart from members of genus Streptomyces, which produce more than 90% of commercialized antibiotics, and the nitrogen fixing Frankia, little attention has been given to other members of this phylum. This is because of difficult culture condition requirements and maintenance. In this review, we focused on specific isolation of actinobacteria and their potential applications in metal bioremediation and plant growth promotion.

• Journal of Microbiology and Biotechnology
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• v.5 no.2
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• pp.100-104
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• 1995

Production of $poly-{\beta}-hydroxybutyrate$ (PHB) in a strain of Azotobacter chroococcum, a nitrogen-fixing bacteria, was investigated at various levels of nitrogen and oxygen. Feeding nitrogen source increased both cell growth and PHB accumulation. Oxygen supply appeared to be one of the most important operating parameters for PHB production. Both cell growth and PHB accumulation increased with the sufficient supply of air in the fed-batch fermentation of the strain. However, it was also noted that keeping the oxygen level under limited condition was critical to achieve high PHB productivity. A high titer of PHB (52 g/l) with a high cellular content (60%) was obtained after 48 hr of fed-batch operation by controlling the oxygen supply. Dual limitation of nitrogen and oxygen did not further increase the PHB accumulation probably due to the greater demand for reducing power and ATP for nitrogen fixation.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.122-127
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• 2015

We carried out three-dimensional flow analysis in a clean room. Flow field in a robot experiment system, induced from the moving robot, is numerically studied in this paper. The effects of moving robot in a clean room are investigated in order to find the section of dust accumulation. Contamination on the bottom produced from the moving robot is predicted from the analysis results from the flow fields. Results show that a large swirl flow is formed around the moving robot. Consequently, the optimal flow condition can be obtained by controlling the fluid velocity through the fixing of inlet or outlet position.