• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.175-180
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• 2002

This study was conducted to examine the effect of row covering materials on the growth and yield of broccoli for early production in the open meld. Materials for plastic tunnel were row-covering (ventilating non-woven fabric), perforated film (2.3％ pore space) and P.E. film. The types of row covers were tunnel and covering period was one months after transplanting. The row cover and perforated film increased daily air and soil temperature by 3~4$^{\circ}C$ and 2~3$^{\circ}C$, respectively as compared to no covering. Also, relative humidities in those treatments were higher than those in P.E. and no covering. The row covering and perforated film enhanced plant growth. Broccoli grew best and abnormal head appeared the least with row covering treatment. Days taken for head formation, however, did not differ between treatments but the weight of curd was over 400 g in the treatment of row covering and perforated film covering. Marketable yield doubled under row covering as compared to no covering. The first harvest time was earlier by two weeks in row-covering. The results of this experiment indicated that covering row-cover film in spring cultivation was effective fer not only yield increase but also quality evaluation in early production of broccoli.

• Korean journal of applied entomology
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• v.15 no.3 s.28
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• pp.107-110
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• 1976

A Witches'-broom disease of jujube (Zizyphus jujuba) with which mycoplasma-like bodies are associated is wide spread in South Korea. Jujube trees with witches'-broom symptoms were selected from 15-20 year old planting and treated with solution of oxytetracycline hydrochloride (Terramycin). Treatments were 1) one injection on April; 2) one postharvest injection on October; 3) two injections (April and July); 4) three injections (April, June and August) and 5) an untreated control. Each injection consisted of 500ml of 1,000 p.p.m. solution of oxytetracycline HCl transfused into affected trees from plastic reservoir through plastic tubes connected to 3 small holes drilled in the basal part of the tree trunks. Complete remission of witches'-broom symptoms was accomplished within one growing season by one spring (April) injection. One postharvest (Oct.) injection also prevented the symptoms in the following growing season. Two and three injection treatments prevented the symptoms for at least two growing seasons and restored previously severely diseased trees to normal or near normal conditions. Remission of symptoms was found only above the injection site while current season witches'-brooms developed from areas below the injection site and from untreated main scaffolds. The results of this experiment demonstrates that transfusion treatment with oxytetracyclin HCl is feasible for the practical control of witches'-broom of jujube.

• Journal of Bio-Environment Control
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• v.20 no.2
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• pp.78-82
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• 2011

Ventilation rates, inside and outside weather data were measured in a arch-shape single-span plastic greenhouse growing tomatoes. On the roof of the experimental greenhouse, round windows which have a diameter of 0.6 m were installed at intervals of 8m. It showed that the number of air changes in this greenhouse were average 0.17 volumes per minute and in the range of 0.02 to 0.32 volumes per minute. These air changes are insufficient to meet the recommended ventilation rate for commercial greenhouses, and it is estimated that interval of 6 m is appropriate for spring or fall season. For summer season, it is necessary to narrow the space or to enlarge the open area of roof windows. Using the heat balance model, the evapotranspiration coefficients of greenhouse tomatoes were estimated from experimental ventilation data, overall heat transfer and solar radiation. It showed that the evapotranspiration coefficients were average 0.62 and in the 0.39 to 0.85 range. We suggest applying 0.6 as the evapotranspiration coefficient in design of ventilation for the single-span tomato greenhouses.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.3
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• pp.154-162
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• 2003

This study was conducted to investigate the effects of tile drain on Physicochemical properties and crop productivity of soils under plastic film house for three years (1999 - 2001). Tiles (${\Phi}100mm$ PVC pipe) were established at 50-60 cm depth with 1 m, 2 m, and 3 m intervals in Gangseo silt loam soil under 2W-type plastic film house. Cropping system was a pumpkin-pumpkin in the first year, a cucumber-spinach-crown daisy-spinach-young radish in the second year, and a green red pepper-tomato-spinach in last year, with conventional fertilization and drip or furrow irrigation by groundwater pumping. Bulk density and soil hardness of plot with tile drain were lower than those of control (plot without tile drain). Soil water content was also lower in tile drain plot than in control regardless of soil depth, and decreased at narrower interval and longer distance from tile in the same plot, thus suggesting that water flow and density of tile drain plot was higher than those of control. Rhizosphere of spinach, a final crop of third year, was expanded more than 2 cm due probably to improvement of soil physical properties caused by tiles establishment. Electrical conductivity (EC) of topsoil decreased from $1.22dS\;m^{-1}$ to $0.82dS\;m^{-1}$ by tile drain system, and the extent of EC decrease was different with season: higher in spring and lower in summer and autumn. The $NO_{3^-}-N$ concentration in topsoil decreased, from $200mg\;kg^{-1}$ to $39mg\;kg^{-1}$. The effect of tile drain on crop yield varied with crops. Average crop productivity obtained in tile drain plot than that of control crop: 18.2% in 2 m interval, 14.2% in 3 m interval, but lower 0.2% in 1 m interval.

• Journal of the Korean Geotechnical Society
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• v.15 no.4
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• pp.153-166
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• 1999

Since the reliability of results by the existing analyzing method is low, in the case of for excavation performed in urban area whose stability is of great importance, construction control based on field monitoring is always necessary. But the field monitoring reflects only the behavior of construction process that has already been carried out, and it has limitations in predicting the behavior of the expected construction process, which is practically more important for construction control. In this study, construction control system for excavation which can predict the behavior of the expected processes during construction with high degree of accuracy, is developed by adopting inverse analysis. The inverse analied applied field monitoring results to excavation analysis can improve the reliability of predicted results. The developed system uses an elasto-plastic soil spring model for the excavation analysis and the minimization of least squared errors between measured displacements and calculated displacements for the inverse analysis. All the required processes for construction control can be performed as an integrated work within the system reflecting real time application and user's convenience. Their applicabilitis are confirmed by two case studies.

• Journal of the Korean Society of Systems Engineering
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• v.13 no.1
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• pp.33-39
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• 2017

This paper describes the system engineering approach for the heat transfer analysis of plus7 fuel rod for APR1400 using, a commercial software, ANSYS. The fuel rod is composed of fuel pellets, fill gas, end caps, plenum spring and cladding. The heat is transferred from the pellet outward by conduction through the pellet, fill gas and cladding and further by convection from the cladding surface to the coolant in the flow channel. The goal of this paper is to demonstrate the temperature and heat flux change from the fuel centerline to the cladding surface when having maximum fuel centerline temperature at 100% power. This phenomenon is modelled using the ANSYS FEM code and analyzed for steady state temperature distribution across the fuel pellet and clad and the results were compared to the standard values given in APR1400 SSAR. Specifically the applicability of commercial software in the evaluation of nuclear fuel temperature distribution has been accounted. It is note that special codes have been used for fuel rod mechanical analysis which calculates interrelated effects of temperature, pressure, cladding elastic and plastic behavior, fission gas release, and fuel densification and swelling under the time-varying irradiation conditions. To satisfactorily meet this objective we apply system engineering methodologies to formulate the process and allow for verification and validation of the results acquired. The close proximity of the results obtained validated the accuracy of the FEM analysis of the 2D axisymmetric model and 3D model. This result demonstrated the validity of commercial software instead of proprietary in-house code that is more costly to develop and maintain.

• Steel and Composite Structures
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• v.34 no.5
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• pp.625-641
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• 2020

The realistic modeling of the beam-column semi-rigid connection in steel frames attracted the attention of many researchers in the past for the seismic analysis of semi-rigid frames. Comparatively less studies have been made to investigate the behavior of steel frames with semi-rigid connections under different types of earthquake. Herein, the seismic behavior of semi-rigid steel frames is investigated under both far and near-field earthquakes. The semi-rigid connection is modeled by the multilinear plastic link element consisting of rotational springs. The kinematic hysteresis model is used to define the dynamic behavior of the rotational spring, describing the nonlinearity of the semi-rigid connection as defined in SAP2000. The nonlinear time history analysis (NTHA) is performed to obtain response time histories of the frame under scaled earthquakes at three PGA levels denoting the low, medium and high-level earthquakes. The other important parameters varied are the stiffness and strength parameters of the connections, defining the degree of semi-rigidity. For studying the behavior of the semi-rigid frame, a large number of seismic demand parameters are considered. The benchmark for comparison is taken as those of the corresponding rigid frame. Two different frames, namely, a five-story frame and a ten-story frame are considered as the numerical examples. It is shown that semi-rigid frames prove to be effective and beneficial in resisting the seismic forces for near-field earthquakes (PGA ≈ 0.2g), especially in reducing the base shear to a considerable extent for the moderate level of earthquake. Further, the semi-rigid frame with a relatively weaker beam and less connection stiffness may withstand a moderately strong earthquake without having much damage in the beams.

• Research in Plant Disease
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• v.19 no.2
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• pp.118-120
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• 2013

During the early spring of 2007 to 2009, stem rot of sweet potato (Ipomoea batatas L.) caused by Sclerotium rolfsii occurred in seedling stage grown in plastic film house at Iksan. In seedling stage of sweet potato, symptoms were initially appeared in yellowing and then the seedlings were eventually wilted. The fungus produced abundant white silky mycelium on infected tissues and soil line. Seedlings were very susceptible and died quickly once they were infected. The whole area of a petridish was rapidly covered with white mycelium on agar medium. Sclerotia began to produce after 7 days of mycelial growth and white sclerotia quickly melanized to a dark brown coloration. The causal agent isolated from the diseased plants was identified as Sclerotium rolfsii Saccardo on the basis of the morphological and cultural characteristics. All isolates of S. rolfsii caused similar symptoms on the host petioles by artificial inoculation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.179-186
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• 2012

In the automobile industry, reducing the weight is the most important objective for reducing air pollution and improving the fuel efficiency. For this reason, the application of aluminum sheets is increasing. When the sheets are applied to the automobile, using inappropriate variables for the material, product design, and press processing can generate tearing, wrinkling, and spring-back problems, which are the main types of failure in the manufacturing process. Therefore, it is necessary to reduce these failures by harmonizing the many variables and strictly managing the processes. In this research, we study the theoretical plasticity instability of Al5454 and obtain the forming limit diagram (FLD) using MATLAB. Moreover, we compare the theoretical FLD with an experimental FLD obtained from a stretching test.

• Mycobiology
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• v.28 no.1
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• pp.54-56
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• 2000

A black scab disease occurred on sword bean (Canavalia gladiata) in plastic film houses around Chinju area during the spring season of 1999. The disease started from flower bud, then moved to flower stalk, pod, petiole, cirrus, stem and leaves. The lesions started with small dark brown spots then were gradually expanded. Severely infected plants reached 37.4% of whole plant covered with scab. Numerous conidia were produced on the diseased flower disk, pod, floral axis, stem and leaves. Most of the conidia were appeared to be readily dispersed in the air, but the mycelia were not suggested causing of sooty mold by ectoparasitism. A fungus was isolated from the diseased stem, and inoculated to healthy plants to satisfy the Koch's postulates and proved the fungus was the causal agent of the disease. The isolated fungus grew on potato dextrose agar, forming greenish black to pale brown colonies. Conidia were ellipsoidal, fusiform or subspherical, mostly one-celled but occasionally septated. The conidia were $3.9{\sim}34.1{\times}2.7{\sim}5.1\;{\mu}m$ in size and formed in long branched chains on the erected conidiophores which were pale olivaceous brown and variable in length between $7.2{\sim}210.7\;{\mu}m$ in size. Ramoconidia were $7.6{\sim}29.2{\times}3.2{\sim}14.4\;{\mu}m$ in size. The fungus was identified as Cladosporium cucumerinum based on the above morphological characteristics. The optimum temperature for mycelial growth and conidial formation was about 15 to $25^{\circ}C$. Cladosporium scab of sword bean caused by the fungi has not been reported in Korea previously.