• Applied Biological Chemistry
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• v.41 no.3
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• pp.247-252
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• 1998

To obtain the basic information for suitable use of soybean-Bradyrhizobium japonicum symbiosis, on soybean cv. Danweonkong and Namhaekong the symbiotic potential of B. japonicum indigenous to plain upland (PU), plain paddy(PP), and mountainous upland(MU) soils in southern part of Korea were surveyed and discussed. Populations of B. japonicum in soils were the highest in MU soils with $5.7{\times}10^4\;cells/g.soil$ followed by PU with $5.0{\times}10^4$ and PP soils with $4.0{\times}10^3\;cells/g.soil$. Shoot dry weight at flowering stage and grain yields at harvesting stage, which mutually showed an high correlation $(P{\leqq}0.001)$, were high in the order of PU > MU > PP soil inocula. Amongst PU soils, Namhae acid Seonsan soils were prominent inocula for shoot dry weight and Kimhae for grain yields at P 0.05, respectively. In cases of nodule number and nodule mass surveyed at the flowering stage, shoot dry weight gave an higher correlation with the latter $(r=0.439^*)$ than the former $(r=0.383^*);$ grain yields with the former $(r=0.505^{**})$ that flue latter $(r=0.449^{**})$. In comparison with Namhaekong showed 1.7 and 1.4 fold higher values in shoot dry weight and grain yields per nodule mass, respectively.

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

• Journal of Korean Society of Forest Science
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• v.65 no.1
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• pp.107-112
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• 1984

Theoretical studies on the effects of forest road are considered to be significant from a present viewpoints which is headed for mordernization and activation of forestry. 1) From a viewpoint of wood production techniques, forest road is enable to economical transport of all kinds of forest products and easy transport to forest of operative tools and necessary materials, and largely contribute to efficiency of all operations, including reforestation, tending, forest protection and conservation of forests. 2) And, from a viewpoint of forest management, development of forest road makes wood marketability be secured and curtailment of various indirect expenditure with the operation efficiency be possible. 3) Forest road, also in living aspects of inhabitants in mountainous villages, plays direct and indirect roles in promoting their welfare including improvement of employment for forest labor, traffic benefits in mountainous area and introduction of culture. Therefore, as a premise to realize intensive management in forestry, the necessities of forest road were increased in its aspects of important and fundamental facilities as well as production basis.

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.76-86
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• 2008

The seasonal variations of primary production were investigated by phyto-PAM chlorophyll fluorometry as well as classical methods (standing crops of phytoplanktons and chlorophyll ${\alpha}$) in the Beopsu Marsh, Haman-gun, Gyeongsangnam-do. The amounts of turbidity, SS, T-N, T-P, BOD, COD, Ca$^{2+}$ and Cl$^-$ were the highest at the station 3, where located in flowout site of wastewater treated by the filtration plants. The water quality was the third level by the standard of BOD and COD. The amount of chlorophyll a (268.8 mg L$^{-1}$) was the highest at the station 2 in April because the cell density (2,677 cells mL$^{-1}$) of Micractinium pusillum increased suddenly from February (180 cells mL$^{-1}$). The patterns of primary production of phytoplankton by phyto-PAM chlorophyll fluorometry were fallen in with those of standing crops and chlorophyll a of phyto-planktons. The primary production was varied according to stations and seasons. The water environments of the Beopsu Marsh as a natural mounument should be under the control of a regular examination in order to preserve the ecosystem.

• Korean Journal of Agricultural Science
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• v.4 no.1
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• pp.34-42
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• 1977

Three kinds of selection indexes were calculated and compared for effectiveness in selecting best performing hybrids from yield trial of corn. The following four characters were used in calculating indexes; yield, moisture content, and root and stalk lodging. 1. Among three indexes calculated, William's base index was more simple in calculation and more efficient in selection of a hybrid than other indexes. 2. Pesek and Baker's estimated index was considered less effective in this test, because of low estimation of genetic variance and covariances of characters from the limited materials and years of experiment. 3. Index calculated according to the Purdue University method (1976) was least effective, even though calculation was simple and easy. The less effectiveness of the index was due to the fact that equal importance of characters were given to each character without considering the differences in economic weight of each character. 4. Equations for expressing moisture content and root and stalk lodging in terms of market price were formulated and they were as follow : 1) Moisture content : $(Y-15.5){\times}$0.0065{\times}bushels/acre$, where Y was the average moisture content of a hybrid at the time harvest. The $0.0065 was the expenses required for removing one per cent of moisture from a bushel of shelled corn in 1976. 2) Root and stalk lodging:$Percent\;lodging{\times}price/Bu.{\div}50{\div}average$ yield of all entries in the test.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.484-491
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• 2015

The productivity of Manila clam(Ruditapes philippinarum) aquaculture farm is closely related to suitable site selection, so it is essential to assess the habitat suitable for aquaculture species in order to manage yield. This study evaluated the habitat suitable index(HSI) with 9 sites for tidal flat farm, Gochang(Hajun) on May 2014. The suitability index was selected Growth(hydrodynamics, chlorophyll a), Survival(sediment-sand, silt-clay) and Water Environment(dissolved oxygen, salinity). Both Weight and No weight were tried for objective judgment as HSI scoring method. As a result, it shows lower tidal flat(HSI; No weight: 0.60~0.76, Weight: 0.47~0.70) is higher than upper(HSI; No weight: 0.25~0.27, Weight: 0.09~0.10), hydrodynamics and sediment particle size are the most effective. This research can consider the potential suitable site for Manila clam through scientific approach, and provide the basis for optimal management practices in tidal flat farm.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.96-100
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• 1984

To give basic information on the agricultural mechanization and multiple cropping adoptability of the paddified clayey terrace soils which have poor permeability and poor adoptability to mechanization, a scheme of drainage classification as well as taxonomic classification was intended. 1. The degrees of gleization of terrace paddy soils were well distinguished by the comparison of "Redness rating" of their profiles. 2. When the criteria of "Imperfectly drained" soils were defined as follows; Soils have more than 50cm of accumulated depth which has less than 0.5 in Redness rating within 1.2m of the profile, the Geugrag series could be classified to "Imperfectly drained." The tentative classification of drainage class of Geugrag soils seemed to well matching with land suitability groups, and give possibility of drainage recommendation in the case of dry land crop cultivation. 3. The Geugrag soil which was well paddified by artificial surface irrigation, could be proposed to classify "Anthroaquic Ochraqualfs."

• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.596-604
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• 2019

This study conducted a sediment culture experiment to investigate the effects of sediment oxygen demand (SOD) and environmental factors on sediment and water quality. We installed a leaching tank in the laboratory, cultured it for 20 days, and analyzed the relationship between P and Fe in the sediment. As a result, the dissolved oxygen of the water layer decreased with time, while the oxidation-reduction potential of the sediment progressed in the negative direction to form an anaerobic reducing environment. The SOD was measured to be 0.05 mg/g at the initial stage of cultivation and increased to 0.09 mg/g on the 20th day, indicating the tendency of increasing consumption of oxygen by the sediment. The change is likely to have caused by oxygen consumption from biological-SOD, which is the decomposition of organic matter accumulated on the sediment surface due to the increase of chl-a, and chemical-SOD consumed when the metal-reducing product produced by the reduction reaction is reoxidized. The correlation between SOD and causality for sediment-extracted sediments was positive for Ex-P and Org-P and negative for Fe-P. The analysis of the microbial community in the sediment on the 20th day showed that anaerobic iron-reducing bacteria (FeRB) were the dominant species. Therefore, when the phosphate bonded to the iron oxide is separated by the reduction reaction, the phosphate is eluted into the water to increase the primary productivity. The reduced substance is reoxidized and contributes to the oxygen consumption of the sediment. The results of this study would be useful as the reference information to improve oxygen resin.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1111-1124
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• 2021

Mudflats are crucial for understanding the ecological structure and biological function of coastal ecosystem because of its high primary production by microalgae. There have been many studies on measuring primary productivity of tidal flats for the estimation of organic carbon abundance, but it is relatively recent that optical remote sensing technique, particularly hyperspectral sensing, was used for it. This study investigates hyperspectral sensing of chlorophyll concentration on a tidal flat surface, which is a key variable in deriving primary productivity. The study site is a mudflat in Geunso bay, South Korea and field campaigns were conducted at ebb tide in April and June 2021. Hyperspectral reflectance of the mudflat surfaces was measured with two types of hyperspectral sensors; TriOS RAMSES (directionalsensor) and the Specim-IQ (camera sensor), and Normal Differenced Vegetation Index (NDVI) and Contiuum Removal Depth (CRD) were used to estimate Chl-a from the optical measurements. The validation performed against independent field measurements of Chl-a showed that both CRD and NDVI can retrieve surface Chl-a with R² around 0.7 for the Chl-a range of 0~150 mg/m² tested in this study.

• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1507-1515
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• 2021

If chlorophyll-a is estimated through ocean color remote sensing, it is able to understand the global distribution of phytoplankton and primary production. However, there are missing data in the ocean color observed from the satellites due to the clouds or weather conditions. In thisstudy, the missing data of the GOCI (Geostationary Ocean Color Imager) chlorophyll-a product wasreconstructed by using DINEOF (Data INterpolation Empirical Orthogonal Functions). DINEOF reconstructs the missing data based on spatio-temporal data, and the accuracy was cross-verified by removing a part of the GOCI chlorophyll-a image and comparing it with the reconstructed image. In the study area, the optimal EOF (Empirical Orthogonal Functions) mode for DINEOF wasin 10-13. The temporal and spatialreconstructed data reflected the increasing chlorophyll-a concentration in the afternoon, and the noise of outliers was filtered. Therefore, it is expected that DINEOF is useful to reconstruct the missing images, also it is considered that it is able to use as basic data for monitoring the ocean environment.