• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.4
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• pp.66-78
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• 2003

The effects of several factors such as heavy metals, living microorganims, high molecular conglomerator in sewage sludge were analysed. And the effects of the sewage sludges which were mixed with other organic waste such as paper mill sludge or night soil sludge upon the feeding rate and biomass of earthworm population were also estimated. The earthworm populations could not survive when newly produced sewage sludges were fed without any pretreatment. The contents of heavy metals were under the levels that could inhibit earthworm's growth. The living microorganisms and the high molecular conglomerator in the sewage sludge had no relations with ecotoxicological effects of sewage sludge upon the earthworm population. Sewage sludge which had been mixed with paper mill sludge and aged for more than 21 days showed no ecotoxicological effects on tiger worm(Eisenia fetida) population. And the feeding rate of earthworm population and the turnover rate of earthworm biomass were higher in those sewage sludges than in the sewage sludges pretreated by other ways.

• Journal of the Korean Regional Science Association
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• v.10 no.1
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• pp.105-125
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• 1994

This paper reviews the achievements of the infrastructure investment policies since around 1990 and identifies policy area in which further efforts should be made. Traditional definition of social overhead capital has implied that the government should be the main, if not sole, supplier of the service. However, many sectors or sub-sectors of infrastructure investment and service allow room for private sector involvement. Expanding the role of the private sector will supplement the resources of the public sector, but more importantly, introduce competition in infrastructure provision. Competition will enhance the efficiency even a particular service remains in the hand public supplier. Private sector involvement, however, raises special problems in Koran context. They are the concentration of the Capital region and regional imbalance; excessive economic powers of large business conglomerator, so-called land problems. We examine each problems in detail and suggests possible solutions.