• Journal of the Korea Organic Resources Recycling Association
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• v.2 no.1
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• pp.65-73
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• 1994

Earthworm cast was investigated in this study in order to domestically develop inexpensive and safe plug nursery soil. 20,30,40 and 50% of earthworm cast were added to the nursery soil as vegetable plant growth media, in which peatmoss and vermiculite constituted the rest of the soil. The effects of earthworm cast on the growth of pepper (Capsicum annuum L.) seedling were obtained as follows. 1. According to the growth stages, significant differences(p=0.001) were recorded in number of leaves, leaf area and biological dry matter yield per plant(shoor or root dry matter yield per plant). In view of mixing ratios in the nursery soil, number of leaves, leaf area and stem weight per plant showed differences significantly at 1% level and leaf weight, root weight and biological dry weight per plant at 5% level, respectively. 2. The nursery soil with earthworm cast showed increased number of leaves and leaf area per plant compared to the commercial nursery soil particularly in the later stage of this study than in the earlier stage 3. Through the total period of seedling growth, leaf weight, stem weight and root weight per plant in the nursery soil with earthworm cast were genrally higher than those in the control and this trend was apparant in the treatment of more than 40% of mixing ratio with earthworm cast. 4. Although leaf weight per plant was higher than stem weight per plant till the 3rd week, from the 4th week stem weight per plant was getting higher. In the later stage of seedling growth, the stem weight was higher in the earthworm cast mixed treatment than that in the control. 5. There was no significant difference on biological dry matter yield in the earlier stage of this study, however in the later stage, it was higher in the earthworm cast mixed treatment than that in the control.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.337-345
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• 2015

After the Fukushima nuclear accident in 2011, concerns about radiation by people are increasing rapidly. If people could know how much they will be exposed by radiation, it may help them avoiding it and understand what exactly radiation is. By doing this, we were helping to reduce the anxiety of radiation contamination. In this study, we have researched figures of radioactivity with 'Captus-3000 thyroid uptake measurement systems' in well counter detector system. The materials were measured with Briquette, Shiitake, Pollock, Button type battery, Alkaline battery, Topsoil, Asphalt, Gasoline, Milk powder, Pine, Basalt stone, Pencil lead, Wasabi, Coarse salt, Tuna(can) Cigar, Beer, and then we categorized those samples into Land resources, Water resources, Foodstuff and Etc (Beer classified as a water resources has been categorized into Foodstuff). Also, we selected the standard radiation source linear 137Cs to measure the sensitivity of well counter detector. After that, we took cpm(counter per minute) for the well counter detector of thyroid uptake system's sensitivity. Then we compared the results of each material's cpm and converted those results to Bq/kg unit. There were a little limitation with the measurement equipment because it has less sensitivity than other professional equipment like 'High purity germanium radiation detector'. Moreover, We didn't have many choices to decide the materials. As a result, there are macroscopic differences among the rates of material's spectrum. Therefore, it had meaningful results that showed how much each material had emitted radiation. To compare the material's cpm with BKG, we've compounded their spectrums. By doing that, we were able to detect some differences among the spectrums at specific peak section. Lastly, Button type battery, Alkaline Battery, Briquette, Asphalt and Topsoil showed high value. There were classified emitting high radiation Group A and emitted lower radiation Group B. The Group A, alkaline battery showed higher rate of radiation by 7.67 %, and Button type battery was yield 4.65 % higher rate than BKG. Additionally, Asphalt (8.03 %), Topsoil (3.76 %), Briquette (7.46 %) were yield for higher values. Several samples of the daily supplies were yield little higher, but it seems safe to use in daily lives. In the case of the 'Foodstuff', all of the samples were safe and they were under the radiation limits of the Ministry of Food and Drug Safety for Food; thus, we highly recommend this study to you as a reference of common daily routine.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.6
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• pp.447-451
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• 2004

This study was conducted to establish the proper techniques of the recirculating wick hydroponics for safe seed tuber proliferation of potatoes (Solanum tuberosum L. CV. Dejima). To achieve these, several intact tubers (5, 10 and 20 g) and cut seed-pieces (two or four) were treated in wick hydroponic system beds. A polystyrene box (31cm in width, 20cm in height, 51cm in length, and $0.031m^3$ in volume) was placed on a styrofoam hox. Eight wicks $(width\;1.5cm\;{\times}\;length\;40cm) $ were put into each polystyrene hox and the boxes were filled with perlite + peatmoss (1 : 2, v/v) medium. Top fresh weight per plant increased with increasing the tuber size from 10 to 30g/tuber. As the tuber size increases from 10 to 30 g/tuher in case of uncut tuber, the marketable tuber (>5g) production per plant increased from 83.8 to 141.8 g/plant and the marketable tuber (>5g) production per plant of cut tuber was slightly higher than that of uncut treatment. Total tuber yield ranged from 4.16 to $6.56kg/m^2$ and the percentage of seed tubers was greater than $97\%$ for all treatments. These results indicate that seed tuber should be cut to produce large tuber $(\geq10g)$ in the recirculating wick hydroponic system.

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.72-77
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• 2018

This paper presents the FEM analysis results on the strength safety of LPG fuelling nozzle, which is composed of ball valve and long cylinder tube. For the strength safety analysis of LPG fuelling Nozzle, the gas pressure of 0.5~3.5MPa has been supplied to the ball valve and long cylinder tube bodies with the wall thickness of 1.7~3.5mm. The maximum von Mises stress of the ball valve with 1.7mm wall thickness is 25.4MPa for the supply gas pressure of 3.5MPa, which is 25.9% compared with that of the yield stress of the brass. And the maximum von Mises stress was 23.7MPa when a 3.5MPa gas pressure was applied to a long cylinder tube with a wall thickness of 1.7mm, which was 6.7% more safe than the ball valve which was analyzed under the same conditions. For the increased wall thickness, 2.0mm of the long cylinder tube, the maximum von Mises stress of 20.2MPa is 14.8% more safe compared with that of 1.7mm wall thickness of the same cylinder tube. Thus, the wall thickness of the ball valve and cylinder tube is recommended as an optimized thickness of 1.7~2.0mm for the strength safety of the LPG fuelling nozzle.

• Journal of the Korean Institute of Gas
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• v.16 no.2
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• pp.25-30
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• 2012

This paper presents a stress safety of a composite pressure cylinder in which is composed of an aluminum liner and composite layers with carbon fiber/epoxy and glass fiber/epoxy resigns. The composite pressure cylinder for a hydrogen gas vehicle contains 9.2 liter hydrogen gas, and hydrogen gases are compressed by a filling pressure of 35MPa. The FEM computed results are analyzed based on the US DOT-CFFC basic requirement for a hydrogen gas cylinder and KS B ISO specification. The FEM results indicate that the stress, 247MPa of an aluminum liner is sufficiently low compared with that of 272MPa, which is 95% level of a yield stress for aluminum. And, the carbon fiber composite layers in which are wound on the surface of an aluminum cylinder are safe because the maximum carbon fiber stresses from 29.43% to 28.87% in hoop and helical directions are below 30% for a given minimum required burst pressure level, respectively. The carbon fiber composite layers are also safe because the stress ratios from 3.40 to 3.46 in hoop and helical directions are above 2.4 for a minimum safety level, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.3
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• pp.471-480
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• 2002

In this paper, the thermal stress analysis of spent nuclear fuel disposal canister in a deep repository at 500 m underground is carried out for the basic design of the canister. Since the nuclear fuel disposal usually emits much heat, a long term safe repository at a deep bedrock is used. Under this situation, the canister experiences the thermal load due to the heat generation of spent nuclear fuels in the basket. Hence, in this paper the thermal stress analysis is executed using the finite element method. The finite clement code Eot the analysis Is not written directly, but a commercial code, NISA, is used because of the complexity of the structure and the large number of elements required for the analysis. The analysis result shows that even though the thermal stress is added to the stress generated by the hydrostatic underground water pressure and the swelling pressure of the bentonite buffer, the total stress is still smaller than the yield stress of the cast iron. Hence, the canister is still structurally safe when the thermal loads we included in the external loads applied on the canister.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.333-340
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• 2010

This paper presents the distributions of the tensile and fracture properties of an alloy 82/182 dissimilar weld joint between an SA508 Gr.3 nozzle and F316L SS safe-end at ambient temperature. Tensile and J-R tests were conducted using specimens extracted from base metals, heat-affected zones (HAZs), buttering regions, and various regions of the weld metal. The results show that the root region of the weld has higher strength than the upper region. The yield and tensile strengths vary considerably within the root region of the weld. The buttering region had the lowest strengths. The strengths gradually increased as the F316L stainless steel weld boundary was approached. The variation of the strengths within the upper region of the weld is insignificant. The fracture toughness of the alloy 82/182 weld metal is less than those of both the base metals and both HAZs. Within the alloy 82/182 weld, the center of weld has a slightly lower fracture toughness than the weld boundary and buttering region, and the root region has greater toughness than the upper region of the weld.

• Journal of the Korean Institute of Gas
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• v.14 no.2
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• pp.1-6
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• 2010

The strength safety of high pressure gas cylinder has been analyzed by using a finite element method. In this study, the internal gas pressures of a steel bombe include a service charging pressure of $9kg/cm^2$, high limit charging pressure of $18.6kg/cm^2$, high limit of safety valve operation pressure $24.5kg/cm^2$, and hydraulic testing pressure of $34.5kg/cm^2$. The computed FEM results indicate that the strength safety for a service charging pressure of $9kg/cm^2$ and high limit charging pressure of $18.6kg/cm^2$ is safe because the stress of a gas cylinder is within yield strength of steel. But the stress for a hydraulic testing pressure of $34.5kg/cm^2$ sufficiently exceeds the yield strength and remains under the tensile strength. If the hydraulic testing pressures frequently apply to the gas cylinder, the bombe may be fractured because a fatigue residual stress is accumulated on the lower round end plate due to a plastic deformation. The computed results show that the concentrated force in which is applied on a skirt zone does not affect to the lower round end plate, and the most weak zone of a bombe is a middle part of a lower round end plate between a bombe body and a skirt for a gas pressure. Thus, the FEM results show that the profile of a lower round end plate is an important design parameter of a high pressure gas cylinder.

• Journal of Bio-Environment Control
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• v.12 no.4
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• pp.200-206
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• 2003

Pleurotus eryngii(King oyster) is one of the most promising mushrooms produced on the domestic farms. The quality as well as quantity of Eryngii is sensitively affected by micro climate factors such as temperature, relative humidity, $CO_2$ concentration, and light intensity. To safely produce high-quality Eryngii all the year round, it is required that the environmental factors be carefully controlled by well designed structures equipped with various facilities and control systems. At the commercial mushroom cultivation house(A,B), this study was carried out to find out reasonable range of each environmental factor and yield together with economic and safe structures influencing on the optimal productivity of Eryngii. this experiment was conducted for about two-month from Nov. 11, 2002 to Dec. 30, 2002 in Eryngii. cultivation house-A, B. Ambient temperature during the experiment period was not predominantly different from that of a normal year. The capacity of the hot water boiler and the piping systems were not enough. Maximum air temperature difference between the upper and lower growth stage during a heating time zone was about 2~3$^{\circ}C$. The max. and min. relative humidity were ranged approximately 60~100%, and average relative humidity was ranged approximately 80~100%. And $CO_2$concentration increased until maximum 1,600~1,800 ppm with the passing growing period. The illuminance in cultivation house was widely distributed from 20lx to 160 lx in accordance with position, and it was maintained lower than the recommended illuminance range 100~200 lx. The average yield per bottle was about 67~85g. But the optimal productivity will be evaluated by considering the quality and quantity of mushroom production, energy requirements, facility construction and management cost, etc.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.14
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• pp.111-115
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• 1973

This experiment was carried out to study the effects of planting density and amount of fertilizer applied on the morphological, physiological and physical characteristics of barley culm. The results are summarized as follows: 1. Heavy application of fertilizer increased the diameter of the inside and outside thickness of culm, dry weight per unit culm, culm length, spike weight and number of per hill. 2. Thined planting density increased lodging resistance. But lodging resistance in sparse-planted plot of$20{\times}$ 20cm was almost the same as that in the plot of $15{\times}$ 15cm. 3. In the heavy fertilized plot weight of culm at breaking, bending moment of culm atbreaking, secondary moment of inertia and section modulus increased more than those in the standard fertilized one. As a result heavy application of fertilizer gave high lodging resistance. On the other hand thined planting density increased the above-mentioned physical characters of culm. 4. In the case of dense planting lodging index became higher in standard fertilized plot, but in the case of sparse planting over 10 x 10cm there were no significant differences in lodging index as affected by amount of fertilizer applied and planting density. 5. Grain yield was increased by heavy application of fertilizer and proper planting density was $5{\times}$ 5cm or $10{\times}$10cm for the safe maximum yield.