• 한국구조물진단유지관리공학회 논문집
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• 제20권6호
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• pp.10-19
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• 2016

본 연구의 목적은 OPC, GGBFS 그리고 FA를 사용한 삼성분계 시멘트(TBC) 페이스트의 자기치유 특성에 관한 것이다. 초음파속도(UPV)측정으로 통해 삼성분계 시멘트의 자기치유 능력에 대한 OPC-GGBFS-FA의 영향을 분석하였다. TBC 페이스트는 0.5의 일정한 물-결합재 비에 GGBFS-FA를 20%, 40% 그리고 60% 치환한 배합이다. 본 연구는 재령 28일(하중 재하 후)이후의 거동에 초점을 맞추었다. 재령 28일에 휨시험을 통해 사각형의 보 시험체에 미리 균열을 발생시켰다. 시험체들은(균열을 발생시키지 않은 것과 균열을 발생시킨) 60일까지 담수와 해수에 침지하였다. 시험결과에 따르면 TBC 페이스트의 자기치유 능력은 GGBFS의 혼합률이 증가함에 따라 증가하였다. 이는 GGBFS와 FA는 재령 28일 이후에도 계속해서 수화가 진행되는데, GGBFS와 FA의 수화반응 물질들이 미세구조의 변화와 균열을 폐합한다. 이러한 결과들로부터, 균열을 발생시킨 모든 시험체에서 자기치유가 일어났고 이는 침지 30일에서 가장 많이 발생하였다. 더구나 담수와 해수에 침지한 시험체의 치유의 대부분이 침지 30일 동안 일어났다. 해수에 침지한 시험체의 균열 치유는 담수보다 빨랐다. 해수와 담수에 침지한 시험체의 치유효과의 차이는 해수에 포함된 이온들 때문이다. 더구나 재령효과를 고려한 자기치유효과는 침지 30일까지가 가장 강력하고 그다음엔 차츰 약해졌다.

• 한국환경보건학회지
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• 제22권1호
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• pp.1-4
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• 1996

I have conducted two testings to find out which water is better for drinking water. First, I made 20 mM L-DOPA solutions by solving L-DOPA (3,4-Dihydroxyphenylalanine) in tap water, Waters' mineral water and reverse osmotic water. Then I measured activities after adding Tyrosinase (purifide enzyme, step 3), which was extracted from Salanum melongena(mad apple), in each L-DOPA solution. Second, I solved 0.1, 0.5 and 0.9% salt in each 20 mM L-DOPA distilled water to measure activity of each salt solution. The results of the testings are as follows: 1. 10 minutes after adding Salanum melongena(mad apple) tyrosinase in each L-DOPA solution, activity of Waters' mineral water was 0.867 tap water 0.777 and reverse osmotic water 0.742. 2. Activity of Waters' mineral water was higher than that of tap water by 10.4% and higher then reverse osmotic by 14.4%. 3. Activity of Waters' mineral water was much higher than that of 0.9% salt water by 41.8%. 4. The optimum pH of Salanum melongena (mad apple) tyrosinase is 9.0. Most enzymes working in the human metabolism are alkaline and body fluids' pH also alkaline. In conclusion, an alkaline water is believed better than an acidic water for drinking.

• 한국산업융합학회 논문집
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• 제24권5호
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• pp.581-587
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• 2021

In recent years, contamination of drinking water sources has emerged as a serious social problem, such as a large number of impurities in tap water or groundwater or the supply of suitable water due to rust of pipes. Although the government and public institutions are implementing various measures to protect water sources, they cannot improve water quality in a short period of time because of the enormous cost involved. Therefore, in recent years, preference has been given to a device that converts tap water, which is hard water, into soft water by installing a separate water softener at the faucet from which tap water is discharged. However, the existing filtration device has a problem that filtration performance is gradually lowered when impurities accumulate in the filter, requiring continuous filter replacement. In this study, the optimal design of the filter housing was performed to develop a water softener that can be washed when impurities accumulate on the filter inside the water softener connected to the faucet. For optimal design of the filter housing, fluid and fluid-structural interaction analysis were performed on the design pressure to determine the shape and thickness of the housing, and design review was performed through prototype.

• 한국환경보건학회지
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• 제39권1호
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• pp.32-42
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• 2013

Objectives: Cryptosporidium, a protozoan parasite, has been recognized as a frequent cause of waterborne disease due to its extremely strong resistance against chlorine disinfection. Although there has as yet been no report of a Cryptosporidium outbreak through drinking water in Korea, it is important to estimate the health risk of Cryptosporidium in water supply systems because of the various infection cases in human and domestic animals and frequent detection reports on their oocysts in water environments. Methods: This study evaluated the annual infection risk of Cryptosporidium in tap water using the quantitative microbial risk assessment technique. Exposure assessment was performed upon the results of a national survey on Cryptosporidium on the water sources of 97 large-scale water purification plants in Korea, water treatment efficacy, and daily unboiled tap water consumption. The estimates of the US Environmental Protection Agency on the mean likelihood of infection from ingesting one oocyst were applied for effect assessment. Results: Using probabilistic methods, mean annual infection risk of Cryptosporidiosis by the intake of tap water was estimated to fall within the range of $2.3{\times}10^{-4}$ to $1.0{\times}10^{-3}$ (median $5.7{\times}10^{-4}$). The risk in using river sources was predicted to be four times higher than with lake sources. With 0.5-log higher removal efficacy, the risk was estimated to be $1.8{\times}10^{-4}$, and could then be lowered by one-third. Conclusions: These estimations can be compared with acceptable risk and then used to determine the adequacy and priority of various drinking water quality strategies such as the establishment of new treatment technology.

• 미생물학회지
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• 제31권3호
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• pp.245-254
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• 1993

1991년 9월부터 1992년 9월까지 23회에 걸쳐 서울시 구의정수장의 상수도계통 즉 원수와 정수 및 이곳에서 공급되는 단일 배급수계통의 3개 수돗물에서 종속영양세균(heterotrophic plate count : HPC) 과 장내세균(Enterobacteriaceae : total coliforms) 의 분포를 조사하였다. $R_{2}A$ 한천배지에서의 종속영양세균수는 원수 $1.22{\times}10^{3}~3.05{\times}10^{5}$ 정수 $1.50{\times}10^{1}~4.29{\times}10^{3}$, 수돗물 $2~5.41{\times}10^{3}$ cfu/100ml, 수돗물 0-47.5 cfu/100 ml 의 범위였으며, m-T7 한천배지에서의 손상된장내세균을 포함하는 장내세균수는 전수 0-27, 수돗물 0-35 cfu/100 ml/의 범위였다. 이러한 결과로부터 정수장에서 공급된 물이 배급수관을 통하여 공급되면서 종속영양세균 및 장내세균의 개체수가 증가하는 세균재생장 현상이 발생한다는 것을 확인하였다. 종속영양세균의 동정결과 원수, 정수, 수돗물을 포함하는 상수도계통의 물에서는 Peudomonas 와 Acinetobacter 가 우점하였으나, 원수에서는 Pseudomonas 의 비율이, 그리고 정수와 수돗물에서는 Acinetobacter 의 비율이 상대적으로 높은 것으로 나타났다. 장내세균은 Enterobacter agglomerans 가 우점종이었으며, 수돗물에서는 정수에서 검출되지 않았던 Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, Shigella dysenteriae 등의 기회성 및 병원성 장내세균도 검출되었다.

• 한국태양에너지학회 논문집
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• 제27권3호
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• pp.45-54
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• 2007

For a conventional natural-circulation type solar water heater, the pressure head is limited by the height between the storage tank and hot water tap. Therefore, it is difficult to provide sufficient hot water flow rate for general usage. This study deals with a design modification of the storage tank to utilize the tap-water pressure to increase hot-water supply Based on fluid dynamic and heat transfer theories, a series of modeling and simulation is conducted to achieve practical design requirements. An experimental setup is built and tested and the results are compared with theoretical simulation model. The storage tank capacity is 240 l and the outer diameter of piping was 15 mm. Number of tube turns tested are 5, 10, and 15. Starting with initial storage tank temperature of $80^{\circ}C$, the temperature variation of the supply hot water is investigated against time, while maintaining minimum flow rate of 10 1/min. Typical results show that the hot water supply of minimum $30^{\circ}C$ can be maintained for 34 min with tap-water supply pressure of 2.5 atm, The relative errors between modeling and experiments coincide well within 10% in most cases.

• Journal of Applied Biological Chemistry
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• 제55권1호
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• pp.1-5
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• 2012

Recently, we reported that Jeju ground water contains vanadium components and exerts antioxidant effects in vitro and in vivo via the scavenging of reactive oxygen species and enhancement of antioxidant enzyme activities. In the present study, the antioxidant actions of Jeju ground water were compared with those of tap water against gamma-ray radiation in mice. C57BL/6 mice were irradiated with gamma-ray at a dose rate of 2 Gy. The mice were then given tap water or Jeju ground water for 90 days. Jeju ground water compared with tap water enhanced the activities and levels of superoxide dismutase, catalase, and glutathione peroxidase in irradiated liver tissues. Jeju ground water also enhanced the levels of intracellular reduced glutathione, which is vital for normal liver function and repair. These results suggest that vanadium-containing Jeju ground water can safeguard against the harmful actions of gamma-ray radiation through the support of hepatic antioxidant processes.

• 한국콘텐츠학회논문지
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• 제20권11호
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• pp.28-37
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• 2020

본 연구는 '수돗물 유충' 사태의 뉴스 빅데이터를 분석함으로써, '수돗물 유충'과 관련된 주요 키워드와 토픽을 파악하여, 환경문제에 대한 위기 대응력 제고방안을 제안하기 위해 수행되었다. 2020년 7월 13일부터 8월 31일까지 보도된 1,975건의 '수돗물 유충' 뉴스를 토픽 모델링 기법으로 분석하였다. 그 결과 언론에서 나타난 '수돗물 유충' 사태가 발생기, 확산기, 수습기로 구분되며, 각 5개의 토픽을 선정하여, 환경문제의 발생과 추진 과정을 확인할 수 있었다. 분석 결과를 바탕으로 환경문제에 대한 위기 대응 방안을 다음과 같이 제언하였다. 첫째, '수돗물 유충' 사건을 중심으로 얽혀있는 다양한 맥락을 탐구하고 통합적인 안목을 형성하는 교육으로 환경문제에 대한 대응력을 기를 수 있도록 해야 한다. 둘째, 인터넷 커뮤니티를 활용한 시민참여의 환경정보 공유와 환경감시 역할 부여가 필요하다. 셋째, 신속하고 정확한 환경정보 제공과 소통을 담당하는 환경 커뮤니케이터의 양성 및 배치가 필요하다. 본 연구는 '수돗물 유충' 관련 뉴스 빅데이터를 기반으로 국내에서 처음으로 토픽 모델링 분석기법을 활용하여 분석한 연구로서, 비정형 데이터로 나타나는 환경 관련 이슈를 실증적이고 체계적으로 분석했다는 학술적 의의와 환경교육 및 커뮤니케이션 개선 방안을 제시했다는 정책적 의의를 지닌다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1990년도 추계학술대회논문집; 한양대학교, 서울; 24 Nov. 1990
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• pp.113-124
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• 1990

Tap lines are small branch piping generally less than two inches in diameter. They typically branch off of header piping having a much larger diameter. An example of a common tap line is a 3/4 inch size high point vent or low point drain. Most tap lines have at least one valve near the header tap connection to provide isolation. Two valves are often required for double isolation. A light water reactor(LWR) nuclear power plant will have several hundred tap lines. These lines come in many sizes and shapes and serve numerous functions. A single process piping valve may have three different tap lines associated with it (figure 1). Table 1 delineates the different categories of tap lines. Vibration failures of tap lines are a common occurrence in all industrial plants including nuclear and fossil power plants. These types of failures constitute a significant percentage of all piping related failures. An unscheduled plant shutdown or outage resulting from the failure of a tap line decreases plant reliability and may have a detrimental effect on plant safety. Most tap line vibration failures can be avoided through the use of appropriate routing and support techniques. Standardized designs can be developed for use in a myriad of applications. These designs will not only minimize failures but will also reduce the necessary analysis and installation efforts.

• International Journal of Fluid Machinery and Systems
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• 제4권2호
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• pp.223-228
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• 2011

The performance characteristics of centrifugal pump were measured experimentally when running with tap water and drag-reducing surfactant (Octadecyl dimethyl amine oxide (OB-8)) solutions. Tests have been performed on five cases of surfactant solutions with different concentrations (0ppm (tap water), 200ppm, 500ppm, 900ppm and 1500ppm) and four different rotating speeds of pump (1500rpm, 2000rpm, 2500rpm and 2900rpm). Compared with tap water case, the experimental results show that the total pump heads for surfactant solution cases are higher. And the pump efficiency with surfactant solutions also increases, but the shaft power for surfactant solutions cases decreases compared to t hat for tap water. There exists an optimal temperature for surfactant solutions, which maximizes the pump efficiency.