• Asian Journal of Turfgrass Science
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• v.17 no.1
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• pp.1-12
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• 2003

Research was Initiated to investigate germination characteristics of cool-season grasses (CSG). Several turfgrasses were tested in different experiments. Experiments I and III were conducted under a room temperature condition of 16$^{\circ}C$ to 23 $^{\circ}C$ and under a constant light condition at 25 $^{\circ}C$, respectively. An alternative environment condition that is a requirement for a CSG germination test by International Seed Testing Association (ISTA) was applied in the Experiment II, consisting of 8-hr light at 25 $^{\circ}C$ and 16-hr dark at 15 $^{\circ}C$. In each experiment, data such as early germinating vigor, germination speed and germination rate were evaluated. Six turfgrass entries were comprised of two varieties each from Kentucky bluegrass (KB, Poa pratensis L.), perennial ryegrass (PR, Lolium perenne L.), and tall fescue (TF, Festuca arundinacea Schreb.), respectively. Significant differences were observed in early germinating vigor, germination speed and germination rate. Early germinating vigor as measured by days to 70% seed germination was variable according to environment conditions, turfgrasses and varieties. It was less than 6 days in PR and 6 to 9 days in TF. However, KB resulted in 11 to 13 days under an alternative condition and 11 to 28 days under a room temperature condition. The germination speed was fastest in PR of 7 to 10 days and slowest in KB of 14 to 21 days. However, intermediate speed of 10 to 14 days was associated with TF. There were considerable variations in germination rate among turfgrasses according to different conditions. Generally, PR and TF germinated well, regardless of environment conditions. However, a great difference was observed among KB varieties, when compared with others. Under a room temperature condition, total germination rate was 71.0% in Midnight and 77.7% in Award. And it increased under an alternative condition, which was 81.7% and 91.7% in Award and Midnight, respectively. However, the poorest rate was found under a constant temperature condition, resulting in 18.0% in Award and 15.3% in Midnight. These results suggest that an intensive germination test required by ISTA be needed prior to the decision of seeding rate, including early germinating vigor and germination speed as well as total germination rate. KB is very sensitive to environment conditions and thus its variety selection should be based on a careful expertise.

• Weed & Turfgrass Science
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• v.6 no.3
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• pp.235-248
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• 2017

This study was initiated to investigate seed germinating vigor, germination speed, and establishment characteristics of Festuca species under natural conditions ($5-25^{\circ}C$). Germination rate was 62.0% in CRF 'Audubon' to 97.0% in TF 'Olympic Gold'. It was greater with TF over fine-type fescues, being TF>SF>CF, HF>CRF. The germination speed, measured as days to seed germination of 50% through 80%, was fastest with TF, medium to high with CF, medium with HF and SF, and slowest with CRF. However, it was approximately 4 days slower under natural conditions, as compared with that under alternative conditions ($15-25^{\circ}C$). Germination peak time was much faster with TF. It ranged from 0.73 to 1.84 days with TF, being 1.45 days in average. But it varied with 2.16 to 11.75 days among fine-type species. The peak time was longer in order of SFCF>SF>HF>CRF.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.3
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• pp.183-190
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• 2017

Carton clamp truck is widely perceived as the high-efficient handling equipment of factory premises and warehouse by its capability of palletless handling. Therefore, the significance of a lab-based handling simulation is becoming higher with the growth of clamp truck usage. In this study, preliminary FEA and design of handling test courses for the lab-based simulation of carton clamp truck handling were performed, and the PSD analyses were performed for the modified one for the test course proposed by Park et al. (2017) as well as ASTM D 6055 and ISTA 3B standards. For the vibration in all directions, the vibration energy intensity analyzed by ISTA 3B standard showed higher than that by the other two cases. A FEA was performed for the handling operation of the sudden stop of the clamps after lifting the target HCP (heavyweight refrigerator corrugated package, w=180 kgf) up to the specified height. The slip distance between the clamp arm and the target HCP was 0.85 mm. The simulation result of 0.85 mm was 3.7 times lower than the experimental result (3.2 mm) obtained by Park et al. (2017), and it was estimated that the deviation comes from both the experimental error by weight imbalance of target HCP, and excessive simplification during the FE modelling of target HCP.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.3
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• pp.47-56
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• 2018

Research was initiated to investigate germination characteristics and germination pattern of 14 herbaceous plant entries used on the road slope during 30 days. An alternative germination condition for 14 herbaceous plant entries required by International Seed Testing Association(ISTA) was applied in the experiment, consisting of 8-hr light at $25^{\circ}C$ and 16-hr dark at $15^{\circ}C$. Significant differences were observed in the first germination rate(0.3%~40.7%)and in the final germination rate(7.7%~93.3%). Days to the first germination(2~8days), days to the 30% germination(2~6days) and days to the peak germination(6~18days) were different among 14 herbaceous plant entries in the study. From this result, we could find out higher final germination rate of 14 herbaceous plant entries in the following order; First, forage crops and cool-season turfgrasses; Second, herbeceous flowers; Third, wild plants. We could also divide germination rate among 14 herbaceous plant entries as 6 groups(I;very high, II;high, III;medium high, IV;medium low, V;low, VI;very low) based on the final germination rate and divide germination speed as 5 groups(A;very fast, B;fast, C;normal, D;slow, E;very slow)based on days to the peak germination. Considering germination characteristics and pattern of 14 herbaceous plant entries Medicago sativa, Lolium perenne, Festuca arundinacea and Cosmos sulphureus were regard as dominating species while Lespedeza cuneata, Silene armeria, Lotus corniculatus var.japonicus, Coreopsis tinctoria and Centaurea cyanus as competitive species following dominating species. However, Chrysanthemum burbankii, Pennisetum alopecuroides, Chrysanthemum boreale., Artemisia princeps var. orientalis and Arundinella hirta were not almost expected to emerge.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.699-702
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• 2004

In this study, the affect of mounting axisymmetrical supersonic inlet to airfoil, which has 65 degree swept angle was numerically investigated. The parameter for this calculation are tree stream Mach number M=2.0 and 2.5, the distance between inlet spike and airfoil lower surface $L_{sw}$/$R_{cowl}$ = 1.21-1.54 and angle of attack to the airfoil 0-4. The mass capture ratio improved 3points in M=2.0 condition and 1points in M=2.5 while the mass capture ratio without airfoil surface was 57% and 71 % for each case. These are the result from increase of density and change of velocity deflection by the shock wave structure formed between inlet and airfoil surface. On the other hand, the distortion of Mach number at cowl lip plane increased by 13% in M=2.0, 3% in M=2.5 condition. The effects of the angle attack on the mass capture ratio is greater than that of the shock wave interaction between inlet and cowl, but the effects to the distortion is smaller in the range of this calculation condition. In the condition of M=2.0 with 4 degrees of angle of attack, inlet distortion of Mach number is mainly caused by the affects of the shock wave interaction between inlet and airfoil surface, while the largest angle of the velocity vector in the radial direction at cowl lip plane is caused by the affect of angle of attack. This large velocity vector made the flow inside the cowl subsonic and caused spillage, which interfere with the boundary layer of airfoil surface.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.5
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• pp.536-543
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• 2009

Dynamic behaviour of a package of a microwave oven under the drop-impact conditions is evaluated by the finite element analysis and tests. PAM-CRASH software is used for the finite element analysis and the tests are performed according to the ISTA(International Safe Transit Association) specification. Results of the analyses are compared with those of the tests and accuracy is shown to be favourable. Under the drop-impact condition of the original design, severe deformation occurs and an improved design is proposed to reduce it. The approach presented in this research can be successfully applied to reduce costs and time required to develop new models of the microwave oven.

• Journal of Power System Engineering
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• v.13 no.3
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• pp.53-58
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• 2009

The importance of cost reduction has grown bigger to ensure the competetive power of products in the electric home appliances industry. Thus, it is necessary to assess the reliability due to drop-impact happenning in process of distribution of microwave ovens with the panel and cavity of thinner thickness for cost reduction. In the present study, the drop/impact simulation using the explicit code LS-DYNA3D has been carried out for improving the impact resistance of a microwave oven. This CAE-based design approach can be successfully applied to enhance the deteriorated dynamic behavior under the impact conditions of dropping height 70cm according to ISTA procedure 2A.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.330-337
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• 2015

Research was conducted to investigate germination and establishment characteristics of five fescue species. Alternative conditions of 8-hr light at $25^{\circ}C$ and 16-hr dark at $15^{\circ}C$ were applied. Significant differences were observed in seed germination power, germination speed and germination peak time. Germination power was 62.25% in CRF 'Audubon' to 96.75% in TF 'Olympic Gold'. It was greater with TF over FF, being TF > HF > SF > CF > CRF. Germination speed, measured as days to seed germination of 50% through 80%, was fastest with TF, medium with CF and HF, and slowest with CRF and SF, being TF > CF, HF > CRF, SF. Germination peak time was much faster with TF over FF. It ranged from 0.94 to 1.47 days with TF. But it varied with 2.80 to 12.36 days among FF species. The peak time was longer in order of HF, SF < CF < CRF. Considering germination power, germination speed and germination peak time, TF 'Arid III' was the best cultivar under alternative conditions, while CRF 'Audubon' the poorest. Overall establishment characteristics among Festuca species were even better with TF over FF in order of TF > CF, HF > SF > CRF.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.2
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• pp.103-108
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• 2017

The amount of delivered parcels have been increasing according to the change and expansion of consumption pattern through e-commerce, and they are required to minimize breakout or failure under the delivery. In this study, we measured and analyzed the distribution environment data (vibration and impact) occurred in the packaging, which were prepared with 5 types by the weight and dimension, distributed from Seoul to Busan in Korea by 2 parcel delivery service companies through e-commerce order. Date showed the parcels had 3-5 times of drop impact and 0.3-0.7 m of drop height on average, and 0.8 Grms of vibration acceleration from equivalent equation to the vertical direction. The significant gap in service quality was not found between 2 parcel delivery service companies. This study is expected to be useful for designing the suitable packaging in order to enhance safe transportation of the delivered packaging, and furthermore useful for developing Korean testing method for Field-to-Lab simulation.

• Advances in aircraft and spacecraft science
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• v.6 no.6
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• pp.529-550
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• 2019

The effect of multiple process parameters on a set of continuous response variables is, especially in experimental designs, difficult and intricate to determine. Due to the complexity in aeroacoustic and vibroacoustic studies, the often-performed simple one-factor-at-a-time method turns out to be the least effective approach. In contrast, the statistical Design of Experiments is a technique used with the objective to maximize the obtained information while keeping the experimental effort at a minimum. The presented work aims at giving insights on Design of Experiments applied to aeroacoustic and vibroacoustic problems while comparing different experimental designs and approximation models. For this purpose, an experimental rig of a ducted low-pressure fan is developed that allows gathering data of both, aerodynamic and aeroacoustic nature while analysing three independent process parameters. The experimental designs used to sample the design space are a Central Composite design and a Box-Behnken design, both used to model a response surface regression, and Latin Hypercube sampling to model an Artificial Neural network. The results indicate that Latin Hypercube sampling extracts information that is more diverse and, in combination with an Artificial Neural network, outperforms the quadratic response surface regressions. It is shown that the Latin Hypercube sampling, initially developed for computer-aided experiments, can also be used as an experimental design. To further increase the benefit of the presented approach, spectral information of every experimental test point is extracted and Artificial Neural networks are chosen for modelling the spectral information since they show to be the most universal approximators.