• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.5
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• pp.281-302
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• 2021

Railway projects have been consistently increasing in Korea. In relation to this trend, the mechanized tunneling using Tunnel Boring Machine (TBM) is preferably applied for mining urban areas and passing under rivers. The TBM tunneling under difficult grounds like mixed faces with high water pressure could require ground improvements for stable TBM advance or safe cutter head intervention (CHI). In this study, pre-grouting works for CHI in Daegok-Sosa railway project are presented in terms of the grouting zone design, the executions and the results, the lessons learned from the experience. It should be mentioned that the grouting from inside TBM was carried out several times and turned out to be inefficient in the project. Therefore, grouting experiences from the surface are highlighted in this study. Jet grouting was implemented on CHI points on land, while permeation grouting off shore in the Han River, which mostly allow to access the cutter head of TBM in free air with stable faces. The results of CHI works have been analyzed and the lesson learned are suggested.

• The Korean Journal of Mycology
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• v.3 no.1
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• pp.21-25
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• 1975

This is a study to determine the content of the mercury compound and the distribution of microorganisms in the waste waters flowing from the chemical plants in the Ulsan area (at 4 stations). The summary of the result of this study is as follows: 1. The content of the mercury compound has ranged from non-detection to 0.075 ppm with an average of 0.03 ppm. The highest content has been detected from the water at station A. 2. As for the distribution of the microorganisms, one species each of bacteria, Mucor, Aspergillus, Cladosporium, and Trichothecium (T. roseum); 4 species of Penicillium; and 3 species of Sterile hyphae; a total of 12 species have been isolated. 3. The following results have been found with regard to the growth of these microorganisms in terms of the content of the mercury compound. In the case of an inorganic mercury compound, most of the microbes can grow in water with a content of up to 10 ppm. Pe. sp No. 1 particularly can grow even in 50 ppm. In the case of an organic mercury compound, the growth of the microbes seems to be somewhat restrained even in 2 ppm.