• Proceedings of the Korea Contents Association Conference
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• 2014.06a
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• pp.429-430
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• 2014

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1987.10a
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• pp.35-38
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• 1987

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.34-37
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• 2007

The safety of ships is one of the most important concerns in terms of the environment and human life. A ship in bad condition is likely to be subject to accidents, such as collision and grounding. When a ship has minor collision damages in the form of circle or ellipse, its ultimate strength will be reduced. It is important to evaluate the reduction ratio of a ship's ultimate strength that results from damages. The strength reduction of a plate with a cutout in the form of hole has been treated by many researchers. A closed-form formula for the reduction of ultimate strength of a plate, considering the effect of several forms of cutout, has been suggested. However, the structure of ships is composed of plates and stiffeners so-called stiffened plates and it is likely that plates and stiffeners will be damaged together in collisions. This paper investigates the effect of minor collision damages on the ultimate strength of a stiffened plate by using numerical analysis. For this study, the deformed shape of minor collision damages on a stiffened plate was made by using a contact algorithm and was used as the initial shape for ultimate stress analysis. Then, a series of nonlinear FE analyses was conducted to investigate the reduction effects on the ultimate strength of the stiffened plate. The boundary conditions were simply supported at all boundaries, and the tripping of stiffener was neglected. The results are presented in the form of reduction ratio between the ultimate strength of an original, intact stiffened plate and that of a damaged stiffened plate.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.248-256
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• 2011

The inherent efficiency of a ship would be prior to any other quality factors in ship's safety, because lack of it may give rise to a serious sea casuality even if it were a light mistake in operation. And the representative casualty comes from a deficiency of stability and an operating error combined would be capsizing. The Korean offshore large purseiner looks to have a structural weak point with small range of stability in spite of her big initial metacentric height, and have various type of roll reduction devices in order to cover up the defect. The aim of this study is to grasp for the roll reduction characteristics of the purseiner with bilge keel only and a stern keel additionally attached. The results are summarized as follows; The rolling angle of the model ship was increased in accordance with increase of the wave period and height, especially at close to the natural wave period of her, and the trends were more distinguished in the situation of bilge keel only installation than in the stern keel additionally installed. And stern keel has not noticeable effect on the reduction of the roll in the light ship condition, but has a little effect in full load condition.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.2
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• pp.29-36
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• 2013

The objective of the research was to describe the effect of straw mat cover and soil amendments on the reduction of runoff and non-point source load from steep sloped highland agricultural fields. Four $5{\times}30$ m plots on sandy loam soil with 28 % slope were prepared. Experimental treatments were bare (control), rice straw mat cover (3,000 kg/ha) (S), PAM (5 kg/ha)+Gypsum (1 ton/ha) (PG) and rice straw mat cover+PAM+Gypsum (SPG). A variety of lettuce was cultivated and runoff was monitored during a growing season in 2011. Natural monitoring was conducted to three times. Runoff rate of S, PG and SPG plots were significantly lower than those of control plot. Especially, the runoff rate is zero in SPG plot at a first rainfall events. The reduction rate of runoff from the S, PG and SPG plots was 30.8 %, 29.0 % and 81.8 % compared to control plots, respectively. The reduction rate of NPS pollution load of S, PG and SPG was ranged of 50~90 %, 30~70 % and 90~100 %, respectively. Yield of lettuce from S, PG and SPG plots was respectively 400 (567 kg/ha), 320 (453 kg/ha) and 760 (1,067 kg/ha) that of compared to control plots greater than that from control plots (140 kg/ha). We speculated that the experimental treated plots could hold more nutrients and moisture than the control and helped the crop grow healthier. When analyzing the above results, in terms of reduction of runoff and NPS pollution load and crop yields, SPG experimental treatment had the best effect. It was concluded that the use of rice straw mats cover and soil amendments on soil surface could not only reduce the NPS pollution loads in receiving waters but also help increase the crop yield.

• Journal of Biosystems Engineering
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• v.36 no.5
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• pp.355-360
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• 2011

This study was carried out to analyze the installation effect of an anti-wind net on reducing wind velocity which was used to protect orchards as well as single-span plastichouses. The pressure drop through three types of anti-wind net was measured in a subsonic wind tunnel. The wind reduction through the anti-wind facility for several sets in respect to three types of the net and heights of the facility ranging from 3 to 11 m was analyzed by using computational fluid dynamics (CFD). The measured data showed that the pressure drop increased as an equation of the second degree of the inlet wind velocity. Numerical computations exhibited that the effect of wind reduction definitely augmented as the net size became smaller and increased with the height of the facility being heightened to some extent. For the typical and widely used anti-wind facility with a height of 5 m and a net size of 4mm, the amount of wind reduction came up to 5.1 m/s for the inlet wind velocity of 20 m/s, and also 7.6 and 10.1 m/s for the inlet wind velocities of 30 and 40 m/s, respectively. In case for the orchard's longitudinal length to be within about 200 m, the appropriately effective height of the facility was predicted to be 5 m. Finally, the negative total pressure on the top face of the single-span plastichouse certainly reduced for all the cases with the anti-wind facility being installed. In particular, the reduction of the negative total pressure was more considerable as the inlet wind velocity increased.

• Journal of Powder Materials
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• v.20 no.5
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• pp.359-365
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• 2013

In this study, we fabricated $Nd_2Fe_{14}B$ hard magnetic powders with various sizes via spray drying combined with reduction-diffusion process. Spray drying is widely used to produce nearly spherical particles that are relatively homogeneous. Thus, the precursor particles were prepared by spray drying using the aqueous solution containing Nd salts, Fe salts and boric acid with the target stoichiometric composition of $Nd_2Fe_{14}B$. The mean particle sizes of the spray-dried powders are in the range from one to seven micrometer, which are adjusted by controlling the concentrations of precursor solutions. After debinding the as-prepared precursor particles, ball milling was also conducted to control the particle sizes of Nd-Fe-B oxide powders. The resulting particles with different sizes were subjected to subsequent treatments including hydrogen reduction, Ca reduction and washing for CaO removal. The size effect of Nd-Fe-B oxide particles on the formation of $Nd_2Fe_{14}B$ phase and magnetic properties was investigated.

• Nutrition Research and Practice
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• v.3 no.3
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• pp.200-207
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• 2009

This study examined the effects of com gluten (CG) and its hydrolysate consumptions on weight reduction in rats fed a high-fat diet. Eight-month-old male Sprague-Dawley rats (n=40) were fed a high-fat diet (40% calorie as fat) for 4 weeks. They were then randomly divided into four groups and fed the isocaloric diets with different protein sources for 8 weeks. The protein sources were casein (control group), intact CG (CG group), CG hydrolysate A (CGHA group, 30% of protein as peptides and 70% as free amino acids) and CG hydrolysate P (CGHP group, 93% of protein as peptides and 7% as free amino acids). Body weight gain, adipose tissue weights, nitrogen balance, absorptions of energy, protein and fat, lipid profiles in plasma, liver and feces and hepatic activities of camitine palmitoyl transferase (CPT), fatty acid synthase (FAS), malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G6PDH) were assessed. The CGHA diet had the highest amount of BCAAs, especially leucine, and most of them existed as free amino acid forms. The CGHA group showed significant weight reduction and negative nitrogen balance. Protein absorption and apparent protein digestibility in the CGHA group were significantly lower than those in other groups. Adipose tissue weights were the lowest in the CGHA group. Activity of CPT tended to be higher in the CGHA group than in other groups and those of FAS, ME and G6PDH were significantly lower in the CGHA group than in other groups. In conclusion, the CGHA diet which had relatively high amounts of free amino acids and BCAAs, especially leucine, had a weight reduction effect by lowering adipose tissue weight and the activities of FAS, ME and G6PDH in experimental animals, but it seemed to be a negative result induced by lowering protein absorption, increasing urinary nitrogen excretion and protein catabolism.

• Journal of Korean Society on Water Environment
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• v.36 no.2
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• pp.109-115
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• 2020

Recently, since impervious areas have increased due to urban development, the water cycle system of urban watersheds has been destructed. Hence, researches on LID (Low Impact Development) technique have been conducted to solve such problems environmentally. In order to verify suitability with the scale and arrangement of LID technique, the runoff reduction effect of the LID technique should be analyzed per small watershed unit. In this study, pre-post difference of the runoff by applying the LID was estimated using the rational method and rainwater treatment capacity equation. As a result, the runoff before and after the application of LID were estimated as 22,533.5 ㎥ and 14,992.1 ㎥, respectively. In addition, rainfall-runoff simulations were carried out using SWMM to evaluate the efficiency of the LID technique. The SWMM simulation results showed that the runoff before and after the application of LID were 21,174 ㎥ and 15,664 ㎥, respectively. Based on the results of the two methods, the scale and arrangement of the LID technique were revised in order to maximize the effect of the water cycle improvement. Rainfall-runoff simulations were carried out using the SWMM with the revised LID techniques. As a result, despite 34.8 % reduction of pervious pavement area, the rate of runoff reduction increased by 2.1 %. These results indicate that designing the scale and arrangement of LID technique, while considering the total amount of inflow entering into each LID techniques, is essential to effectively achieve the goals of runoff reduction in urban development.

• KIEAE Journal
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• v.14 no.2
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• pp.11-19
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• 2014

Building energy consumption takes up almost 25% of the total energy consumption. Therefore, diversified ways, such as improving wall and window insulation, have been considered to reduce building energy consumption. Recently, green roof system has been explored as an effective alternative for dealing with reducing heating and cooling energy, thermal island effect and improving water quality. However, recent studies regarding a green roof system have only focused on building energy reduction without considering the applied usage, location, and story of the green roof system. Therefore, this study pays attention to the heating and cooling energy in relation to the applied usage, location, and story of a green roof system for investigating its impact on energy reduction. The result of simulations show that the reduction in heating energy consumption is higher when applied to Cherwon-gun province which has a continental climate condition, compared to the city of Busan that is distinguished by its warm climate. Cooling energy saving turns out to be higher when the green roof system is applied to Busan in comparison with Cherwon. As for the applied usage or function of the building, residential space acquires the highest heating and cooling energy saving effect rather than commerce, educational or office space because of HVAC's running time based on usage. When it comes to the story of the green roof, both heating and cooling energy saving become the highest when the green roof is applied to single-storied buildings. The reason is that single story building is affected by the ground largely. Generally, the variations of heating energy consumption are larger than the cooling energy consumption. The outcome of the simulations, when a green roof system is applied, indicates that the energy consumption reduction rate is dynamically responding to the applied usage, location, and story. Therefore, these factors should be counted closely for maximizing the reduction of energy consumption through green roof systems.