• Korean Journal of Environmental Agriculture
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• v.29 no.3
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• pp.282-286
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• 2010

The present studies were carried out for three years from 2007 until 2009 to control nematode and to increase yield of cucumber by crashed-rape seed application at polyethylene film house. Crashed-rape seed has a lot of glucosinolate. Myrosinase decompose gulcosinolate into isothiocyanate and thiocyanate when crashedrape seed go to decay at soil. Those chemical compounds act on poison to nematode at soil. When the crashedrape seed treated at soil, an amount of thiocyanate at soil was risen up. Thiocyanate of plot treated with 200 and 400 kg crashed-rape seed per 10a was 30 and 40 mg/kg, respectively. Nematode(meloidogyne spp) population at soil was 13 to 17 nematodes per dried soil 300g. Yield of cucumber increased 6 to 15 percent to be compared with control. While, Nematode(meloidogyne spp) population of control plot were 463 nematodes per dried soil 300 g. This level was much higher than 150 nematodes which can be brought about injury to plant. Even if the more an amount of crashed-rape seed application, the higher yield of cucumber and control effect of nematode. Consider economical efficiency, 200 kg of crashed-rape seed per 10a was the most effective. Therefore, we suggest applying 200 kg of crashed-rape seed per 10a to control soil nematode when culture cucumber at plastic film house.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.66-72
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• 2018

BACKGROUND: Constructed wetlands are low-cost alternatives for treating domestics sewage. However, previous study has reported that the removal of phosphorus in constructed wetlands was limited. Therefore, a new alternative was needed to extend the life of the constructed wetlands. The purpose of this study was to evaluate the effect of total phosphorus removal by oyster shell on longevity of constructed wetlands for treating domestic sewage. METHODS AND RESULTS: The changes of total phosphorus concentration and treatment efficiency in two constructed wetlands (CWs) classified as system A (coarse sand 100%) and system B (coarse sand 90%+oyster shell 10%) were investigated for 6 years. The actual saturation time of total phosphorus in the systems A and B was estimated to be longer than that of theoretical saturation by adsorption isotherm experiment. In particular, the saturation pattern of phosphorus in system A was maintained at a certain concentration level in the initial stage of operation, and finally saturation was reached as the saturation gradually progressed from the breaking point. In system B, the saturation period of phosphorus was prolonged as compared with system A due to the addition of oyster shells. CONCLUSION: Our results suggest that the longevity of the constructed wetlands can be extended due to the phosphorus saturation by adding the oyster shells to the coarse sands in constructed wetlands.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.146-156
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• 1998

Fly ash produced in coal combustion is a fine-grained material consisting mostly of spherical, glassy, and porous particles. A physical, morphological, and chemical characteristic of fly ash has been analyzed. This study may contribute to the data base of domestic fly ash, the improvement of combustion efficiency, ash recycling and ash collection in the electrostatic precipitator. The physical property of fly ash is determined using a particle counter for the measurement of ash size distribution and gravimeter. Morphological characteristic of fly ash is performed using a scanning electron micrograph and an optical microscope. The chemical components of fly ash are determined using an inductively coupled plasma emission spectrometry (ICP). The distribution of fly ash size was ranged from 15 to 25 $\mu$m in mass median diameter. Exposure conditions of flue gas temperature and duration within the combustion zone of the boiler played an important role on the morphological properties of the fly ash such as shape, relative opacity, coloration, cenosphere and plerosphere. The spherical fly ash might be generated at the condition of complete combustion. The size of fly ash was found to be increased the with particle-particle interaction of agglomeration and coagulation. Fly ash consisted of $SiO_2\;Al_2O_3\;and\;Fe_2O_3$ with 85% and carbon with 3~10% of total mass.

• Journal of Korean Society of Rural Planning
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• v.23 no.1
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• pp.85-96
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• 2017

Existing agricultural reservoirs are considered as alternative source for the water welfare of rural area. In this study, domestic water supply potential of 476 reservoirs, which has storage capacity more than one million cubic meter, out of 3,377 agricultural reservoirs managed by Korean Rural Community Corporation (KRC) were investigated. Among them water quality of 136 reservoirs met the criteria of domestic water source which show less than COD 3 ppm. Available amount for domestic water of reservoirs, which meet the water quality, for ten year return period of drought was analyzed with reservoir water balance model. The results showed that 116 reservoirs has potential for supplementary domestic water supply while satisfying irrigation water supply. Finally, economic analysis using Net Present Value (NPV), Benefit-Cost (B/C) ratio, Internal Rate of Return (IRR), and Profitability Index (PI) methods was also conducted. The analysis showed that 19 reservoirs satisfied economic feasibility when water is provided from reservoir outlet but only 9 reservoirs meet the economic feasibility if water delivered from a reservoir to treatment plant by newly built conveyance canal. In order to supply the domestic water through the agricultural reservoirs managed by KRC, it is necessary to flexibly interpret and operate the 'Rearrangement of Agricultural and Fishing village Act'. Also, it is reasonable to participate in the water service business when there is a supply request from other Ministries. In addition, the KRC requires further effort to change the crop system for saving water and improve efficiency of irrigation systems.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.758-766
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• 2008

To evaluate homologue patterns and removal efficiency before and after water treatment, the concentrations of dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs) were determined in 122 samples from 42 drinking water treatment plants throughout Japan over a two year period. The mean concentrations and toxic equivalent (TEQ) values of dioxins in raw and treated waters were 60.24 pg/L (0.14 pg-WHO-TEQ/L) and 4.15 pg/L (0.016 pg-WHO-TEQ/L), respectively. The dioxins contribution ratio of drinking water in relation to dioxins tolerable daily intake (TDI, 4 pg-TEQ/kg/day) was 0.016%. The mean TEQ removal rate of dioxins by drinking water treatment was over 88%. However, the mean removal rate of 2, 3, 7, 8-TeCDF (tetrachlorodibenzofuran) by water treatment in the 122 samples was minus 17%. Therefore, to identify which process affected the level of 2, 3, 7, 8-TeCDF, the removal efficiencies at both the advanced and conventional water treatment plants were investigated. For the TEQ removal rate across the processes, the dioxin congeners, TeCDF and non-ortho-PCBs remarkably indicated minus values after chlorination in both the advanced and conventional water treatments plant. From this study, the level of 2, 3, 7, 8-TeCDF was found to be increased as a result of chlorination.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.2
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• pp.137-141
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• 1971

In order to observe the effect of soil added to oil cake in the preparation of liquid fertilizer for flower culture use, a laboratory experiment was carried out, in addition to a pot experiment done with Petunia as an indicator plant. The results obtained are as follows; 1. Faster decaying, and heavier accumulation of ammonia was observed in the mixture of soil, oil cake and water than the mixture of only oil cake and water. At the same time, the former gave better effect on the growth of Petunia than the latter. It was considered that the early raise of pH in the mixture of soil, oil cake and water stimulated the decomposition of oil cake. 2. No pH raise and a small accumulation of ammonia even at the mixture of soil, oil coke and water was observed when temperature was low, around $12-25^{\circ}C$. However, the deficiency of ammonia in the mixture of soil, oil cake and water was large enough to result in the better growth of Petunia than in the mixture without soil.

• Korean Journal of Weed Science
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• v.32 no.2
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• pp.107-114
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• 2012

This study was conducted to evaluate the weed suppressing effects of different cropping system including hairy vetch (Vicia villosa) and rye (Secale cereale) cover crops, polyethylene plastic film, and transplanting film mulching in direct sowing and transplanted sorghum field in 2011. Crop growth and development and weed occurrences in the fields were examined to know the efficiency of proposed cropping system. In polyethylene film mulching treatment, heading date of sorghum was earlier by 3 days than control, on the other hands, rye cover crop mulching delayed heading date by 11 days. Besides the effect of cover crop on the heading of sorghum, the residues changed growth characteristics. Plant height of sorghum was increased by 27.3% at hairy vetch treatment although it was reduced by 47.5% in the rye cover crop treatment. Hairy vetch treatment showed beneficial effects on sorghum growth reduced the occurrences of grasses and broadleaf weeds to 84% and 96%, respectively, as compared to control in sorghum fields. While rye cover crop treatment showed poor sorghum growth reduced less strongly grasses and broadleaf weeds by 35% and 71%, respectively. At harvest, yield of sorghum was greater in order of hairy vetch cover crop > polyethylene film mulching > rye cover crop ${\fallingdotseq}$ control in both transplanted and direct sown fields.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.342-348
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• 2014

Onshore great fires can normally be extinguished by firefighters using special firefighting equipment and its suitable method. However, offshore fires on the ships are to be extinguished by the crew without any supports from the onshore. Also, crews working on board are exposed to high risk of emergency evacuation due to the complicated structure arrangement of the ships and different accident types such as fire and ship collisions. As most of damage and loss of life in fire are associated with suffocation, shortening of evacuation time is an important factor to improve a survival rate. In this study, visibility in the accommodation area is analyzed by using the temperature and smoke flow which are obtained by the Fire Dynamic Simulator(FDS) as a Three-Dimensional Fire Analysis program to understand the survival rate of the crew upon the fire. The fire doors for most of ships are designed to close automatically when the fire alarm is activated. These automatic closing of the fire doors is a very effective system to delay the spread of flame and smoke flow for the unmanned spaces of the fire protected area. However, if the crew cannot escape within the estimated time, the crew inside the fire protected area will be damaged a lot. In this paper, the comparative analysis between the evacuations by using the fire door from the fire protected area and the suggested fire shielding structure in this study is carried out by the smoke flow rate and the temperature rise rate.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.8
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• pp.1128-1135
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• 2011

This study was conducted to investigate the effect of dietary green tea extract (GTE) on the performance, carcass and gastrointestinal tract (gut) traits, caecal coliform bacteria count, and pH and color (CIE $L^*$, $a^*$, and $b^*$) values of the breast muscle in broilers. A total number of 600 day-old broilers (Ross 308) was allocated to three treatments with four replicates containing 50 (25 males and 25 females) birds. The dietary treatments consisted of the basal diet as the control (0GTE) and diets with GTE at 0.1 (0.1GTE) or 0.2 (0.2GTE) g/kg. Body weights and the feed intake of broilers were measured at 1, 21 and 42 days, the feed intake was measured for different periods and the feed conversion ratio was calculated accordingly. At 42 day four birds per replicate were slaughtered for the determination of carcass and organ weights, caecal coliform bacteria count, and also quality of the breast muscle. The dietary GTE increased the body weight, feed efficiency, carcass weight and dressing percentage and decreased caecal coliform bacteria count of broilers (p<0.05). The 0GTE broilers consumed (p<0.01) less feed than the 0.1GTE birds in the entire experimental period. The relative abdominal fat weight and gut length of broilers in the 0.2GTE were tended to be lower (p<0.07) than those in the 0GTE group. The breast meat from 0.1GTE birds had a lower pH value when compared to that from 0GTE birds. The 0.1GTE broilers had lighter breast meat than 0GTE and 0.2GTE birds. The dietary GTE increased $a^*$ and $b^*$ values of the breast meat. Thus this product appeared to have a measurable impact on CIE color values of the breast meat in broilers. The results of the present study may indicate that the improved production results in the group with added GTE are directly connected with physiological mechanisms such as the regulation of the caecal micro-flora.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.580-586
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• 2016

The ultra-long stroke engine was developed to generate greater power at lower speeds than previous designs to enhance the propulsion efficiency. The torsional exciting force, on the other hand, was increased significantly. Therefore, it is possible to control the torsional vibration of its shaft system equipped with the fuel efficient ultra-long stroke engine by adopting a damper although the torsional vibration could be controlled adequately by applying tuning and turning wheels on the engine previously. In this paper, the dynamic characteristics of a viscous-spring damper used to control the torsional vibration of the corresponding shaft system are reviewed and then examined to determine what vibration characteristics might be used to optimize the viscous-spring damper. In some cases, operators of eco-ships have recently experienced the problem of delayed RPM acceleration. It has been suggested that the proper measures for controlling the torsional vibration in the shaft system should involve adjusting the design parameters of its damper determined by the optimum damper design theory to avoid the fatigue damage of shafts.