• Journal of Plant Biology
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• v.25 no.2
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• pp.83-99
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• 1982

In this study, thirty-two stands in Kwangnung forest located in the central part of Korea were preferentially selected. In each stand, all stems for trees and shrubs were recorded by species and their girths were measured down to 5cm. In addition, several enviromental factors such as field soil pH, field soil moisture, soil compressibility, depth of soil, thickness of litter layer, elevation and basal area were measured. Three soil cores were sampled and various physical and chemcial properties was determined. The vegetational data were subjected to three kinds of multivariate ordination(PO, PCA, RA). The results suggested that Kwangnung forest was consisted of three forest types: coniferous, mixed and broad leaved forest communities. The relation between the stand scores of ordination and several environmental factors were investigated in terms of correlation analysis in order to examine the relationships between the vegetation and certain environmental factors. As a result of this analysis, the amount of sand content in A1 horizon decreased frm the coniferous to broad leaved forest, while maximum field capacity, pore space, exchangeable cations, loss on ignition, soil pH nad the amount of total nitrogen had a tendancy to increase significantly. However, easily soluble phosphorus appeared to have little to do with the forest types. The result of species ordination of centered-standardized PCA suggested that the major successional pathway in Kwangnung forest was; Pinus densifloralongrightarrowQuercus mongolica, Q. serrata, Q. alienalongrightarrowCarpinus laxifloralongrightarrowC. erosa in sequence. This trend is in good agreement with the past studies. In three kinds of ordination (centered PCA, centered-standardized PCA and RA) based on nineteen species and twenty-five stands, the total variances accounted for the first three axes were 77%, 46% and 63% respectively. The estimated beta diversity in Kwangnung forest assumed as a coenocline, was 1.5~1.8 HC. Increasing the effect of the sampling errors on ordination perfermance, this low heterogeneity seems to cause the poor concentration of the total variance. The results from the four kinds of ordination were in good agreement with each other, especially between PO, centered-standardized PCA and RA appeared robust. It seems to be worthy of applying multivariate method for analyzing other forest communities in Korea.

• Journal of Preventive Medicine and Public Health
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• v.7 no.1
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• pp.131-138
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• 1974

The author has conducted survey on the status of physical growth and morbidity of the children for christian children's fund programme, as a means of collecting basic data for the anticipated establishment of a health planning. A total 345 children aged 9 to 16 underwent C.C.F. programme while as a control, a total of 480 children of same ages from the middle-class school children in Jeonju area was also studied. As results of survey conducted for a period of one month (form July 1 to 31, 1974) on a total 429 children in 347 households living in Jeonju area. I. Socio-economic background 1. By educational status of the children, 39.9 per cent of the total children was attending at primary school, 33.8 per cent in middle school and 15.6 per cent in high school. 2. The greatest proportion or 28.8 per cent of the household head were engaged in labor, 17.9 per cent in peddler and 13.2 per cent in retail. 3. As for the living standard of the households, low class constitued 90.1 per cent, middle and high classes only 9.9 per cent. 4. 39.5 per cent of the households had their own house, 39.1 per cent lived in rent deposit house or rooms and 14.6 per cent in monthly rented house and rooms. II. Physical growth and nutritional status 1. The growth of children for C.C.F. programme in terms of height was found to be slightly smaller than the school children. The ages frm 9 to 16 corespond to the 'secondary growth and replenishment period and this period was regarded to be the one most affected by environmental and nutritional factors of all the other periods of growth and developmet. 2. The body weight of the children for C.C.F. presented a quite different pattern from that of the school children. The above findings appeared thin-and-long stature from the famillies with higher living standard while those from the household with low standard of living had a short-and-plump one. 3. According to the values of Rohrer's index, the children of C.C.F carried a higher degree of 'replenishment' than the children in Jeonju area and adolesecence comes later for the girls under C.C.F. programme. III. Morbidity 1. The monthly prevalence rate was 110.0 per thousand persons for the children under C.C.F. programme. 2. The total number of case was classified by timing of the incidence as follws. 40.0 per cent was constituted by diseases carried over from tile previous month and 60.0 per cent by new incidences. 3. The diseases were broken down by W.H.O. disease classification into the greatest proportion or 39.1 per thousand person constituted by disease of the digestive system.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.2
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• pp.102-106
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• 2007

While the effort has been made in recycling the FRP (Fiber Reinforced Plastic) used for the medium-to-small size ships, researchers try to find out the methods more favorable for the environments and more value-added. In respect to the fact that the FRP consists of two types of layers, roving and mat, differentiated by the 2-dimensional structure, our group was able to separate the layers of FRP instead of grinding it. The roving cloth was cut to the long glass fibers (about 50 mm long; calling it 'F-fiber' afterwards). F-fiber showed increasing tensile strength and chemical-resistance possibly due to the remained resin (about 25% by weight). In this experiment fiber-reinforced mortars are made of the F-fiber as a recycling method of FRP. The mortar containing 2% (v/v) F-fiber results in 34.6% increment of bending strength from the standard after 28 day curing. The resulting strength is similar to that of the mortar with imported polyvinyl fiber P-54. These results imply that F-fiber can be applied to the 'fiber reinforced mortar' and furthermore may be a substitute for the imported fibers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.81-88
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• 2008

The purpose of this study is to improve and modify the evaluation method of load carrying capacity for simply supported PSC I Typed girder bridge. To do this, conventional ASD(Allowable Stress Design) and USD(Ultimate Strength Design) evaluation method were initially investigated and it was evaluated that the conventional USD evaluation method may perform the load carrying capacity as conservative because it do not consider the prestressing upper-force effect of simply supported PSC I Typed girder bridge. To reasonably evaluate the load carrying capacity, the upper-force effect should be considered to the PSC I Typed girder bridge. Thus, in this study, the MUSD method was Suggested and compared to the nonlinear FEM based-load carrying capacity using the live load factor and the efficiency of the evaluation method of load carrying capacity was investigated by experimental and analytical result. In the result of this study, the suggested MUSD evaluation method showed a reasonable evaluating result for the simply supported PSC bridge. For the new technique of load carrying capacity based on the nonlinear FEM analysis, it could effectively simulate the load-deflection relationship and the load carrying capacity of the PSC I Typed girder bridge.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.8-15
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• 2021

This paper describes a design method using an optimization technique to satisfy the longitudinal handling quality of high maneuverable jet aircraft. The dynamic inversion technique was applied to the target aircraft, and the control gain optimization satisfied the longitudinal short-period handling quality, however, the stability margin was not considered. If the stability margin is not satisfied, it is necessary to directly readjust the gains through trial and error methods for improvement. To improve this, an additional compensator and an optimization constraint were added to the control gain optimization procedure. In addition, the degree of handling quality satisfaction with the optimization result was reevaluated, and additional control evaluation criteria for the convergence of the time response and the steady state error that the flight performance requirement set as the optimization constraint cannot be reflected, and the results are described.

• Journal of Korea Foresty Energy
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• v.19 no.2
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• pp.93-101
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• 2000

Wood of Robinia pseudoacacia and bark of Populus alba$\times$P. glandulosa, Fraxinus rhynchophylla and Ulmus davidiana var. japonica were collected and extracted with acetone-water(7:3, v/v) in glass jar to examine whether its bioactive compounds exist. The concentrated extracts were fractionated with hexane, chloroform, ethylacetate and water, and then freeze-dried for column chromatography and bioactive tests. The isolated compounds were sakuranetin-5-O-$\beta$-D-glucopyranoside from Populus alba $\times$Pl glandulosa, 4--ethyoxy-(+)-leucorobinetinidin frm R. pseudoacacia and fraxetion from F. rhynchophylla and were characterized by $^1H$ and$^{13}C $ NMR and positive FAB-MS. Decay-resistant activity was expressed by weight loss ratio and hyphae growth inhibition in the wood dust agar medium inoculated wood rot fungi. R. pseudoacacia showed best anti-decaying property in both test and its methanol untreated samples, indicating higher activity than methanol treated samples in hyphae grwoth test. In antioxidative test, $\alpha$-tocopherol, one of natural antioxidants, and BHT, one of synthetic antioxidants, were used as references to cmpare with the antioxidant activities of the extacted fractions. Ethylacetate fraction of F. rhynchophylla bark indicated the hightest activity in this test and all fractions of R. pseudiacacia extractives also indicated higher activities compared with the other fractions. In the isolated compounds, aesculetin isolated from F. rhynchophylla bark showed best activity and followed by robonetinidin from R. pseudoacaica.