• Journal of the Korea Institute of Military Science and Technology
• /
• v.24 no.1
• /
• pp.84-98
• /
• 2021

The hydrodynamic characteristics of amphibious assault vehicles are investigated using commercial CFD code, STAR-CCM+. Resistance performances of a displacement-type vehicle and a semi-planing type vehicle are analyzed in calm water. The self-propelled model is also computed for the semi-planing type vehicle. All computations are performed using an overset mesh system and a RANS based flow-solver coupled with a two-degree of freedom equations of motion. A moving reference frame is applied to simulate revolutions of impeller blades for a waterjet propulsion system. Grid dependency tests are performed to evaluate discretization errors for the mesh systems. The numerical analysis results are compared with the experimental results obtained from model tests. It is shown that RANS is capable of investigating the resistance and self-propulsion characteristics of high-speed amphibious assault vehicles. It is also found that a fully covered side skirt, which is covering tracks, reduces resistance and stern trim, besides increasing propulsive efficiency.

• Journal of muscle and joint health
• /
• v.30 no.3
• /
• pp.208-217
• /
• 2023

Purpose: The aim of this study was to investigate the degree of stress, resilience, focusing manner, and quality of life among burn rehabilitation patients. Furthermore, it seeks to identify factors affecting the quality of life in this patient group. Methods: The participants of this study were 129 burn patients, aged 19 or older, who received treatment at the rehabilitation of a university hospital in Seoul. Data were collected from June 22 to August 31, 2022 through self-report questionnaires covering stress, resilience, focusing manner and quality of life.The data were analyzed using the SPSS 29.0 program. Results: Multiple regression analysis showed that education level, cause of burn, area of burn, pain, stress, and focusing manner significantly affected the quality of life, explaining 74.5% of the variance. Conclusion: In particular, focusing manner was a major factor affecting the quality of life in burn rehabilitation patients. Therefore, there is a need to develop intervention programs aimed at increasing focusing manner in this patient group.

• Korean Journal of Plant Resources
• /
• v.33 no.1
• /
• pp.15-23
• /
• 2020

There is high vulnerability of soil loss in sloping and highland used for agricultural production due to the low surface covering in summer rainy season. This study evaluated the surface-covering rate of landscape crop in reducing soil loss in the highland. The experiment was conducted in a 55% sloped lysimeter with three treatments of planting density using Korean native chrysanthemum, and investigated the soil coverage rate, run-off water, and soil erosion. The three treatments according to the degree of soil covering are bare soil as the control treatment TC, coverage rate of 43-59% for treatment T1, and, coverage rate of 63-81% for treatment T1, and T2. During the cultivation period, the average reduction of run-off water was 71% for treatment T1 and 76% for treatment T2, which are better, compared with the control. The reduction in eroded soil was 84% in treatment T1 and 98% for treatment T2, which is also better than the control treatment. Therefore, it is possible to alleviate the soil loss in sloping lands by planting chrysanthemum, which is superior among the perennial plant species and considered as a crop with economic value.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.15 no.1
• /
• pp.39-67
• /
• 1987

The purpose of this thesis is to suggest objective basic data for the environmental design through the quantitative analysis of the visual quality included in the physical environment of forest landscape. For this, landscape values of forest landscape have been evaluated by using the Iverson method, the images structure of forest landscape's main utilizing space have been analysed by the factor analysis algorithm, degree of visual preferences have been pleasured mainly by questionnaries and SBE method, and finally these thesis can be summarized as fallow LCP with high values of Iverson factors I and IV yield high landscape value. Specifically, Iverson factor IV has been found to play the dominant. For all experimental points, significant seasonal variations in S.D. scale values have been observed. In natural parks, where artificial structures are complementary to the natural landscape, main factors of image are S.D. scales such as the visual sequence, the formal simplicity of structures, the emphasis, the unification of heterogeneous factors and the assimilation. Factors covering the spatial image of natural parks have been found to be the overall evaluation, the individual characteristics, the tidiness, the potentiality, the dignity, the intimacy and the space volume. For all seasons, factors such as the individual characteristics, the dignity, the tidiness, the potentiality, yield high factor scores. As for factors determining the degree of visual preference, variables such as the summit, the skyline, rocks, the water and the degree of natural destruction by artificial structures yield high values for all seasons.

• Resources Recycling
• /
• v.29 no.4
• /
• pp.67-72
• /
• 2020

Recycling processes of spent copper wires cosisnt of several steps of cutting and chopping processes for peeling covering materials followed by gravity separation processes, where copper is recovered. Because copper thin wires could be lost during further recycling processes, the wire may need to be further treated. In the present study, the copper thin wire was treated with ball milling to prevent the loss. Since the aggregation of the copper wire could be formed by bending and entangling the copper wire each other, the degree of flexion of the copper wire was measured after ball milling. When the 0.5 cm and 3 cm copper wires were used, the 0.5 cm copper wire was not bent and the 3 cm copper wires were aggregated regardless of the ball addition. When the 1 cm and 2 cm copper wires were used, the degree of flexion was remarkable when the balls were added. In the tests using 2 cm copper wires, the aggregation ratio of the copper wire gradually increased with the amount of the 20 mm alumina ball, and when 200 ml of 30 mm alumina ball was used, the aggregation ratio increased to 89.29 %, but after increasing the ball amount further, the aggregation ratio decreased. Thus, it is expected that the loss of the copper wire could be reducedif when the copper thin wire is treated with ball milling by the aggregation of copper thin wires.

• Magazine of the Korea Concrete Institute
• /
• v.10 no.6
• /
• pp.213-222
• /
• 1998

Covering polmer mortar as a filter for permeable polymer concrete on the base polymer concrete is nessary for good permeability from infiltration continuously. Therefore, three covering polymer mortars on the optimum base polymer concrete were cast immediatly following on the casting of the base polymer concrete. They are tested for compressive and flexural strengths, adhesion in tension, hardening shrinkage and permeability, and the effects of the mix proportioning factors on the properties of the permeable polymer concrete are discussed. From the test results, increase in the compressive strength and decrease in the coeffiecient of permeability of base polymer concrete are clearly obserbed with increasing filler-binder ratio. The base polymer concretes having a compressive strength of 9.4~28.3MPa and a coefficient of permeability of 0.12~1.93 cm/s can be produced in the consideration of the mix proportioning factors. Binder and filler contents in mix proportions had a great influence on the permeability of polymer concretes. The mechanical properties of permeable polymer concretes covered with polymer mortar using crushed stone are superior to other filters, and hardening shrinkage is the smallest in filters. It is apparent that adhesion between the base polymer concrete and polymer mortar is affected by the degree of hardening shrinkage. From this study, proper mix proportions can be recommended in the consideration of properties of the permeable polymer concrete.

• Journal of Bio-Environment Control
• /
• v.17 no.1
• /
• pp.1-8
• /
• 2008

Four cover plants such as Phlox subulata, Glechoma hederacea var. longituba, Sedum middendorffianum and Saxifraga laciniata were evaluated to investigate the effect of companion planting on reducing soil erosion in Chinese cabbage cultivated highland. The experiment was conducted using lysimeters of $5\;m{\times}2\;m$ (length$\times$width) with 5, 15 and 30% slopes. Companion plants except Sedum middendorffianum did not interface with growth of Chinese cabbage Glechoma hederacea var. longituba and Sedum middendorffianum grew faster than Phlox subulata and Saxifraga laciniata in the early growth stage suer transplanting, resulting in fast ground covering, but the ground covering by Phlox subulata and Saxifraga laciniata was delayed because growth suppression by high air temperature during summer season. Soil erosion became severe as increasing degree of slope. Assessments of the four cover plants were conducted in relation to soil conservation characteristic of scenery, endurance to the environment stress, plant growth and weed suppression. From the assessments, Phlox subulata was superior to other intercropping crops tested for reducing soil erosion in highland cultivation of Chinese cabbage.

• Korea journal of population studies
• /
• v.24 no.1
• /
• pp.149-182
• /
• 2001

Due to the sustained increase in lifts expectancy, the number and proportion of the aged population has substantially increased, the proportion of the total population aged 65 and over was 7.1% in 2000 and 14.3% in 2022. But All public pension schemes in Korea, including the National Pension scheme, civil servants pension scheme, private school teachers pension scheme and the military pension scheme, are facing valving degree of financial problems at present because of their weak and unstable financial bases. with the result that some of them have recorded deficits for some time and the others are expected to run deficits in the near future. This crisis in financial sustainability in public pension schemes is attributable to the structural weakness of the schemes which can be characterized as high benefits, low contribution. Therefore, this article focuses on alternative of public pension schemes reform in Korea. The results is as follows. First, a basic pension is proposed to be newly established and the earnings related portion of National Pension Scheme will be as national pension. Secondly, the Basic Pension is a universal basic pension covering all nationals over 18 years and older, thereby achieving \"one pension for everybody\" Thirdly, National Pension will be operated as an earnings related pension covering only those participants with assessed income. Fourth1y, the current participants of public occupational pensions will also join the Basic Pension as well as the public occupational pensions whose scope of works will be reduced. And finally, The conversion of Retirement Allocation Scheme into a corporate pension should be left to the discretion of the company concerned.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.41 no.1
• /
• pp.28-33
• /
• 1996

This experiment was carried out at National Crop Experiment Station in 1994 to obtain basic information of growth characters and yield of rice under various seeding methods in direct seeding on dry paddy. Hwaseongbyeo sown on April 27 by flat drill seeding, high ridged drill seeding and hill seeding under different seed conditions, soil convering after seeding and irrigation methods. Nitrogen applied 150kg /ha by 3 times split application at rate of 40:30:30％ (basal: 5th leaf stage:panicle initiation stage). Seedling stands were higher in flushed irrigation water after seeding than in irrigation at 3rd leaf stage, and it also was higher in high ridged drill seedings than in flat drill seedings. Days for seedling stand, heading date were shorten 6~10 days, 2~3 days by flushed irrigation water after seeding, respectively. Number of tiller was more in high ridged drill seedings than conventional seedling method(Flat drill seeding ＋ intact seed ＋ soil covering after seeding ＋ irrigation at 3rd leaf stage after seedling stand) at early growth stage, but the most tiller number was highest in developed seeding method(Flat drill seeding ＋ soaked seed ＋ non soil covering after seeding ＋ fulshed irrigation water after seeding) at heading stage among used seeding methods. Lodging index was slightly high in high ridged drill seeding and conventional seeding. Field lodging was degree 1 in high ridged drill seedings and developed seeding, Milled rice yield in developed seeding was increased 7％ compaired with conventional seeding(5.35t /ha).

• Horticultural Science & Technology
• /
• v.16 no.4
• /
• pp.517-519
• /
• 1998

This experiment was carried out to find out the effects of heat conservation materials (burying in soil, lagging, lagging +straw, nonwoven fabric, nonwoven fabric+straw) on freezing damage, labor saving, and crown gall occurrence of 'Kyoho' grapes. Temperature differences in burying in soil and lagging with $2.8^{\circ}C$ and $6.4^{\circ}C$, respectively and were considered favorable for over-wintering of grapevines. Heat conservation index in lagging +straw and burying in soil calculated from degree-hours below $-10^{\circ}C$ was 5 to 7 times higher than that of open field. Budbreak started earlier in lagging with+straw and nonwoven fabric+straw covering, and percent budbreak was increased by 22% and 7%, respectively, as well as higher than burying in soil. Diameter of bearing mother branch and length of internode and daughter branch were gross or long with soil and lagging straw and nonwoven fabric+straw. Cane growth was enhanced by burying in soil and lagging with+straw treatment. Crown gall occured higher in soil covered grape vines Labor saving was obtained in lagging with as much as 44% compared to burying in soil.