A national infrastructure is a physical and human system that can have a significant impact on life, property, and the national economy if its function is paralyzed. It is also used for energy, telecommunications, transportation, finance, healthcare, nuclear energy, environment, important government facilities, etc. In this paper, we present a disaster risk assessment method and alternative method considering the regional characteristics of the national infrastructure through the evaluation of disaster risk.

Recently, the importance of facility maintenance has been increasing due to the problems caused by the occurrence of new types of disasters and the deterioration of facilities. However, it is difficult to maintain consistent facilities because the related laws are dispersed depending on the size and purpose of facilities. In addition, when a collapse occurs, there is difficulty in response activity. This paper analyzes the problems in the maintenance of facilities in accordance with the deterioration of facilities and draws out the Mediumand long-term development plans of facility maintenance field

Since there is no computer system for general management of dangerous and disaster prone facilities that handle dangerous substances and data for disaster prevention facilities in Industrial Complex of Korea, much manpower and time are required to discover risk factors and identify spreading of dangerous. This paper proposes an disaster prevention platform system based on sensor, scenarios for disaster response, collective Intelligence for detection of chemical disaster signs and effective initial response to disasters on Yeosu Industrial Complex.

This study analyzes the existing case studies on the harmful chemical accident response system and analyzes the factors for decision - making and decision - making in the hazardous chemical accident site. Based on the conceptual model of collective intelligence as a new decision - making method, we will build a decision - making model based on collective intelligence that can be applied in the hazardous chemical accident site. The collective intelligence model proposed in this study is designed around hazardous chemical accidents, and it is necessary to conduct empirical studies through the composition of more specific expert groups.

Since there is no computer system for general management of dangerous and disaster prone facilities that handle dangerous substances and data for disaster prevention facilities in Industrial Complex of Korea, much manpower and time are required to discover risk factors and identify spreading of dangerous. This paper proposes an disaster prevention platform system based on sensor, scenarios for disaster response, collective Intelligence for detection of chemical disaster signs and effective initial response to disasters on Yeosu Industrial Complex.

This research studied the characteristics and applicability of electrocoagulation using aluminium electrode for the color and COD removal in textile wastewater. Electrocoagulation reactor used two different electrode, Fe and Al, since in the general chemical wastewater treatment, aluminium and ferrous salts were used as coagulants. Aluminium electrode showed higher removal efficiency of color and COD than ferrous electrode did. The COD and color removal efficiency improved at the 0.192A/dm2 current density. Thus, the electrocoagulation process with bipolar aluminium electrode showed better efficiency in the decolorization and COD removal rate of textile wastewater effluent than custom coagulants did.

The basic mechanism of the granular sludge formation which is the most important factor in the start-up and stable operaton is not confirmed yet. In this study, the effect of granular sludge formation was investigated with the different substrate concentrations and the various ratios of substrate supply/deficiency. The granular sludge formation in the UASB reactor was closely related to the substrate concentrations and the ratio of substrate supply/deficiency. The granular sludge formation was not accelerated at low substrate concentration. It was convinced that granular sludge formation was accelerated when the substrate supply with high concentration was stopped at UASB reactor. From this experiment, it was estimated that granular sludge was formed by the combination of hydrogen utilizing bacteria that form hydrogen condition and acid forming bacteria at substrate deficit condition by mutual symbiosis. Though the removal efficiency of organic matter was decreased as the influent substrate concentration was increased, the higher the influent substrate the better the granular sludge formation.

Laboratory investigation was conducted to evaluat the mixing effects on organic removal efficiency to treat low-strength synthetic wastewater using modified anaerobic filter reactor combining anaerobic filter and upflow anaerobic sludge blanket. Using the modified process the low-strength wastewater like municipal sewage could be treated with 85% T-COD removal efficiency at hydraulic retention time of 6 hours. At the constant organic loading of 0.5㎏ COD/㎥-day, the organic removal efficiency and effluent COD concentration are increased as influent COD concentration increased from 125 ㎎/ℓto 500 ㎎/ℓ. Mixing effects on organic removal efficiency are evident and optimum mixing speed is found as 50RPM. Placing the granular studge and media on which slime layer was pre-formed into the reactor seemed to be very effective in achieving short start-up period. Therefore the steady state was achived after 4 weeks and 1 week based on T-COD and S-COD, respectively.

Granular sludge formation and it`s activity change are the most important factors in achieving successful start-up and operation of UASB reactor. Nevertheless, the detailed mechanism is still unknown. On the basic of the experiments in laboratory-scale UASB reactor, the effect of hydrogen partial pressure on sludge granulation was evaluated. Size distribution method and specific metabolic activity of the sludge with the operation time were used as a means for estimating the degree of the sludge granulation. At the constant hydrogen loading, the granulation increased as starvation periods in hydrogen supply increased, resulting in high organic removal efficiency. It was evidient that hydrogen play very important role in granulation and sludge granulation was achieved through mutual symbiosis between hydrogen utilizing bacteria and hydrogen producing bacteria under the hydrogen deficient conditions.

This study was conducted to evaluate the effects of pressure and dissolved oxygen concentration on the activated sludge and to determine the optimum depth of deep shaft process. Some results from this study were summarized as follows. 1. It is considered that low sludge product in the activated sludge system maintaining high dissolved oxygen concentration is attributed to the increase of endogeneous respiration rate caused by the increase of aerobic zone in the sludge floc. 2. The increase of dissolved oxygen concentration does not affect to the increase of organic removal efficiency greatly and therefore the limiting factor is the substrate transfer into the inner part of floc. 3. The yield coefficient, Y is decreased in proportion to the increase of oxygen concentration. In this study, Y values arre ranged from 0.70 to 0.41 according to the variation of dissolved oxygen concentration from 18.0㎎/ℓ to 258 ㎎/ℓ. 4. The optimum depth of deep shaft process should be determined within the limits of non-toxicity to the microorganism and it is about 100m in this study.