This study focused on natural organic matter and trihalomethane removal by ozonation with various ferrous concentration in surface water. Ozonation is more affected by injection concentration than reaction time. dissolved organic carbon removal rates in ozonation increased with the increase in ferrous concentration. The highest removal was obtained at 6 mg/L of ferrous concentration. When 1 mg/L of ferrous was added with 2 mg/L of ozone concentration, it was found to be a rapid decrease in specific ultraviolet absorbance at the beginning of the reaction because ferrous acts as a catalyst for producing hydroxyl radical in ozonation. As ozone concentration increased, trihalomethane formation potential decreased. When 2 mg/L of ozone was injected, trihalomethane formation potential was shown to decrease and then increase again with the increase in ferrous concentration.

This study is focused on effects of factors that affect the formation of THMs during chlorination in drinking water treatment. During the chlorination, chlorine consumption is increased by increasing the initial chlorine dose, the pH and the total dissolved solid (TDS) concentration. Also THMs formation is increased up to 58.82 μg/L and 55.54 μg/L by increasing initial chlorine concentration and increasing pH. However, concentration of chloroform is decreased by increasing TDS concentration. This is caused the cation(Na+) of the total dissolved solids preferentially reacts with the functional groups of the organic material which influence the trihalomethane formation. But total trihalomethane formation is increased up to 127.46 μg/L by Br- contained in the total dissolved solids. DOC reduction was not influenced by any of the factors.

Sludge transporting pipes in wastewater treatment plant are easy to be clogged with struvite when the digested sludge and dehydrated filtrate are transported through the pipes, which lowers the efficiency of sludge treatment system in a WWTP. pH is one of the most important factors in struvite formation, and carbon dioxide separated from biogas can be used to control pH and struvite formation. By controlling pH, the amount of dehydrating agent can be reduced by about 10%, which saves the budget for facility maintenance. As CO2 is reused and dehydrating chemicals are saved, the approach can contribute to global warming gas reduction.

Corrosion inhibitors including calcium hydroxide have been used to prevent corrosion in the pipes for tap water supply. The corrosion index (i.e., Langelier Index) differs by area and water quality. The corrosion indices of the areas studied differed by more than 2.0. The ‘homogenized’ calcium hydroxide was added to the treated water at the K water treatment plant, in order to increase the value of the corrosion index and the concentration of calcium. As the result, the concentration of calcium was increased while the turbidity and pH changed little. The corrosion rate of the tap water with the 'homogenized' calcium hydroxide could be slowed down pretty much. The results suggested that the technology of 'homogenization' of calcium hydroxide can applied to tap water and desalinated water to prevent corrosion in water pipes even in corrosive pipes.

This study is focused on manganese (Mn(II)) removal by ozonation in surface water. Instant ozone demand for the water was 0.5 mg/L in the study. When 0.5 mg/L of Mn(II) is existed in water, the optimum ozone concentration was 1.25 mg/L with reaction time 10 minutes to meet the drinking water regulation. The ozone concentration to meet the drinking water regulation was much higher than the stoichiometric concentration. The reaction of soluble manganese removal was so fast that the reaction time does not affect the removal dramatically. When Mn(II) is existed with Fe, the removal of Mn(II) was not affected by Fe ion. However As(V) is existed as co-ion the removal of Mn(II) was decreased by 10%. Adding ozone to surface water has limited effect to remove dissolved organic matter. When ozone is used as oxidant to remove Mn(II) in the water, the existing co-ion should be evaluated to determine optimum concentration.

This study is focused on manganese (Mn(II)) removal by potassium permanganate (KMnO4) in surface water. The effects of bicarbonate on Mn(II) indicated that bicarbonate could remove Mn(II), but it was not effectively. When 0.5 mg/L of Mn(II) was dissolved in tap water, the addition of KMnO4 as much as KMnO4 to Mn(II) ratio is 0.67 satisfied the drinking water regulation for Mn (i.e. 0.05 mg/L), and the main mechanism was oxidation. On the other hand, when the same Mn(II) concentration was dissolved in surface water, the addition of KMnO4, which was the molar ratio of KMnO4/Mn(II) ranged 0.67 to 0.84 was needed for the regulation satisfaction, and the dominant mechanisms were both oxidation and adsorption. Unlike Mn(II) in tap water, the increasing the reaction time increased Mn(II) removal when KMnO4 was overdosed. Finally, the optimum conditions for the removals of 0.5 - 2.0 mg/L Mn(II) in surface water were both KMnO4 to Mn(II) ratio is 0.67 - 0.84 and the reaction time of 15 min. This indicated that the addition of KMnO4 was the one of convenient and effective methods to remove Mn(II).

First of all, Fe or/and Mn immobilized granular activated carbons (Fe-GAC, Mn-GAC, (Fe, Mn)-GAC) were synthesized and tested to remove arsenate (As(V)). The results in batch test indicated that Fe-GAC removed As(V) effectively, even though the surface area of Fe-GAC was reduced largely. Moreover, adsorption isotherm test indicated that the experimental data fit well with Langmuir model and the maximum adsorption capacity (qmax) of Fe-GAC for As(V) was 3.49 mg g-1, which was higher than GAC (2.24 mg g-1). In column test, the simulated water, which consisted of As(V), Fe(III), Mn(II) and Ca(II) in tap water, was used. Fe-GAC column with 1 hr of pre-washing time treated As(V) effectively while GAC column removed Fe(III) better than Fe-GAC column. Moreover, the increasing pre-washing time from 1 to 9 hour in Fe-GAC column enhanced Fe(III) removal with little negative impact of As(V) removal. Mostly, the column filled with Fe-GAC and GAC (i.e. the mass ratio of Fe-GAC:GAC = 2:8) showed the higher treatability of both As(V) and Fe(III), even it operated with 1 hr pre-washing time.

The characteristics of filter/adsorber granular activated carbon (F/A GAC) were investigated by measuring various parameters, which include surface area, pore volume, abrasion number, floater, and water-soluble ash. The correlation between parameters was also evaluated. Moreover, rapid small-scale column test (RSSCT) was conducted for adsorption characteristics. Thirteen F/A GAC were tested, and the average values of abrasion number and water-soluble ash were 88.9 and 0.15%, respectively. F/A GAC with the larger external surface area and greater mesopore volume had the lower abrasion number, which indicated that it was worn out relatively easily. Water-soluble ash of coconut-based GAC (about 2.6%) was greater than that of coal-based GAC (less than 1%), and the pH of solution was increased with GAC, which had the higher water-soluble ash. On the other hand, floater of thirteen F/A GAC was divided as two groups, which one group had relatively higher floater (2.7~3.5%) and the other group had lower floater (approximately 0.5%). The results of RSSCT indicated that coconut-based GAC (i.e. relatively higher water-soluble ash) had less adsorption capacity. Moreover, adsorption capacity of coal-based GAC with larger surface area and greater mesopore volume was superior to others.

The effect of activated carbon particle diameter (i.e. US sieve No. 8×10 (dp ≈ 2.19 mm), 18×20 (dp ≈ 0.92 mm), 50×60 (dp ≈ 0.27 mm) and 170×200 (dp ≈ 0.081 mm)) on caffeine adsorption is investigated. BET surface area was increased with decreasing particle diameter (dp), and caffeine adsorption rates increased with decreasing dp. Moreover, pseudo-second order model is predicted the experimental data more accurately than pseudo-first order model, and the fastest rate constant (k2) was 1.7 g mg-1 min-1 when dp was 0.081 mm. Surface diffusion coefficient (Ds) was decreased with decreasing dp based on the minimum sum of square error (SSE). Practically, certain ranges of Ds are acceptable with high reliability (R2) and it is determined that the effect of dp on Ds is unclear. The effect of pH on caffeine adsorption indicated the dependency of m/L ratio (mass liquid ratio) and pHPZC. The pHPZC (i.e. 7.9 ± 0.2) was not affected by dp. The higher caffeine adsorption at pH 4 and pH 7 than at pH 10 is due to pHPZC, not pka of caffeine.

Two step rapid filter system as a pre-treatment for the injected water into aquifer storage and recovery (ASR) in Korea was developed to reduce physical blockage and secure the volume of the injected water. First, single rapid sand filters with three different media sizes (0.4~0.7, 0.7~1.0 and 1.0~1.4 mm) were tested. Only two sizes (0.4~0.7 and 0.7~1.0 mm) satisfied target turbidity, below 1.0 NTU. However, they showed the fast head loss. To prevent the fast head loss and secure the volume of the injected water, a rapid anthracite filter with roughing media size (2.0~3.4 mm) were installed before a single rapid sand filter. As results, both the target turbidity and reduction of head loss were achieved. It was determined that the media size for a rapid sand filter in two step rapid filter system (i.e. a rapid anthracite filter before a rapid sand filter) was 0.7~1.0 mm. In addition, the effects of coagulant doses on the removal of natural organic matter (NOM), which might cause a biological clogging, were preliminarily evaluated, and the values of UV254, dissolved organic carbon (DOC) and SUVA were interpreted.

In this paper, we introduce the pipe cleaning robot developed to clean the gas impurities of the iron manufacturing equipments. The pipe cleaning robot is composed of two driving modules and one cleaning module. 2-DOF joint units were developed for connections among the modules. To maximize the traction power of the driving parts, it became caterpillar type. The extension links have been developed to maintain the traction force in case the pipe inner diameters change. Three cleaning modules were developed for the effective cleaning in the pipe. The driving and cleaning performance tests of the pipe cleaning robot were proceeded in the field of the iron manufacturing equipments.

산업화의 영향으로 에너지 수요 증가에 따라 석탄수요의 증가 및 산업부산물인 재(Ash)의 발생량 또한 급증하는 추세이며, 재(Ash)의 재활용량은 지속적으로 증가하고 있으나 재활용에 의한 수익은 점차 감소하고 있어 재(Ash)의 재활용 부가가치가 점점 낮아지고 있는 실정이다. 본 연구는 산업부산물인 슬러지와 비산재 혼합에 따른 조경골재 생산을 하고자 하며, 하수슬러지 20~25%, 비산재 30~35%과 첨가제로서 물유리 및 알칼리제를 혼합한 후 소성온도 700~1000℃에서 1시간 동안 반응시켜 제조하여 화산석 대체의 조경골재 사용을 위한 가능성 연구를 하고자 한다. 소성시킨 멀칭용 조경재 제조 후 성분분석을 해본 결과 Si 성분이 20.77%으로 가장 많이 함유되어 있는 물질로 나타났으며 조경재의 구조에 영향을 미치는 Al, Ca, Fe 등의 원소로 구성되어 있는 것으로 나타났다. 주사 전자현미경(SEM)분석을 한 결과 다공성이 발달된 구조가 형성되어 토양에 통기성을 높일 수 있는 구조로 발달되어져 있음을 확인할 수 있었으며, 적정 배합비 및 소성온도 등의 특성을 보다 연구하여 화산석과 유사한 조건의 특성을 함유한 멀칭용 조경재를 제조할 수 있을 것으로 판단된다. 슬러지와 비산재의 혼합을 통한 조경골재 제조에 따른 결론은 폐자원을 활용하여 다양한 분야에서의 재활용 가능성을 높여줄 수 있을 것으로 사료되며, 이에 따른 기업 간의 협력을 통해 자원화 네트워크를 구축할 수 있는 방법을 통한 산업부산물의 다용도화가 가능하다.

Although understanding and interesting of safety and maintenance on domestic facilities are important, there is little recent on a comprehensive and integrated survey of actual condition. Therefore this study asserts the necessity of the survey methodology. The purpose of this study is to investigate current situation and to suggest integrated facility breakdown structure, and to establish survey process of actual condition on domestic infrastructure facilities and buildings.

The ultimate aim of this study is producing the plan of the safety and research on the actual condition for facility to prepare a deterioration of the public facility. Through this scientific and methodical research on the actual condition, we can obtain required information for making policy which is used for general maintenance and the result of this study will give us a primary plan.

Infrastructure safety and maintenance management(ISMM) is one of the most important parts for improving level of people's welfare. The government needs to set up their own improvement strategy for ISMM system. This study was initiated to suggest the strategy to improve ISMM system with long term perspective. In order to investigate the current status and problems of ISMM system, this study reviewed various literature related to the issues of the foreign ISMM systems and conducted the interview with ISMM experts. The strategy would be expected greatly to improve the safety and maintenance management system for domestic infrastructure.

화재가 발생하면 열과 연기생성물이 발생하는데 화재로부터 발생되는 온도변화는 일반적인 대기 온도의 변화와 상당한 차이가 있기 때문에 이 온도변화를 감지하여 조기에 화재발생을 포착할 수 있다. 또한 연기가 발생하면 시계(視界)가 줄어드는 것을 감지할 수 있다. 화재를 좀더 정확하게 감지하려면 화재에 의한 화재징후는 기기로 측정할 수 있을 만큼 주위 환경을 변화시키고 이 변화값은 그 환경의 평상시 변수보다 커야 한다. 화재감지기는 화재로부터 발생하는 화재징후인 열, 연기 등을 감지하여 화재발생을 조기에 관계자에게 경보하는 기기이다[1-3]. 실제 환경에서는 화재가 아닌 경우에도 화재감지기의 고정된 수치 이상 발생할 수 있고, 화재가 발생했어도 고정된 수치 이하로 열, 연기 등이 발생할 수 있다. 이와 같은 화재감지기의 완벽하지 못한 신뢰성 때문에 경종, 사이렌 등 경보장치의 소음으로 인하여 사람들이 불편을 겪는 경우가 있고, 심지어 화재감지기의 전원을 OFF시키는 경우도 있어 실제 화재가 발생하였을 때 화재로 인한 대참사를 야기시킬 수도 있다. 본 연구는 가연물 종류에 따른 화재감지기의 응답특성을 분석한 연구로 다양한 가연물을 연소시킨 다음 화재감지기의 설치위치 등에 따라 감도특성이 어떻게 변화하는 가를 확인하였다. 가연물 종류는 열이 주로 발생하는 알코올, 연기가 주로 발생하는 면심지와 열과 연기가 다량으로 발생하는 N-heptane을 사용하였고 화재감지기 설치위치는 벽체와 천장으로부터 이격된 거리에 따라 실험을 수행하였다. 그 결과 벽 또는 천장에서 이격거리가 클수록 감도특성이 저하되는 것을 확인하였다.

화재 현장은 매우 높은 온도 및 습도가 요구되는 장소이며, 또한 소화활동 중에도 폭발 및 붕괴 등의 위험이 상존하는 장소이다. 이러한 극한 환경에서 근무하고 있는 소방대원에게 소방진압복은 생명을 담보하는 중요한 장비이며, 이 기초장비의 성능이 화재진압의 성공과 실패에 큰 영향을 미칠 수 있다. 그러나 유럽 및 미국의 소방진압복의 성능기준과 국내 소방진압복의 성능기준에 있어 일부 차이가 있다. 본 연구에서는 각 대륙별 소방진압복의 성능기준을 비교 검토하여 공통시험기준 및 비공통시험기준을 도출하여 소방대원들이 보다 안전하고 효율적으로 화재진압활동을 수행할 수 있도록 기존 국내 소방진압복의 시험기준에 화재현장의 환경조건에 필수적인 시험기준(안)을 선정하여 추후 시험기준의 개정 추진시 신규 시험기준(안)을 추가할 수 있는 이론적 배경을 제시하고자 한다.