• Journal of Korean Society of Water and Wastewater
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• v.35 no.3
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• pp.237-246
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• 2021

The ILI, developed by the IWA (International Water Association), has been used in many countries as an indicator of water leakage. In Korea, the revenue water has been used as a performance indicator for waterworks although there is an opinion to replace it with the ILI. Hence, it has been necessary to investigate whether the ILI can replace the revenue water in Korea. The four main operating indicators (i.e., water service population, profit-loss ratio, fiscal self-reliance, and aged pipe rate) of 162 Korean waterworks were compared with the ILI with the linear regression method. Local water authorities with more than 1 million water service population, with more than 60% profit-loss ratio, more than 40% and less than 60% fiscal self-reliance, and more than 20% aged pipe rate showed meaningful correlation between the four parameters and the ILI. In the remaining cases, their correlations were little or weak. This means that using the ILI may not be an efficient method to represent the performance of the water supply system in Korea because of the lack of UARL (Unavoidable Annual Real Losses) data accuracy. To use the ILI in Korea, it will be required to carry out an additional research to accumulate reliable CARL (Current Annual Real Losses) and UARL data in the future.

• Corrosion Science and Technology
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• v.16 no.6
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• pp.305-316
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• 2017

Austenitic stainless steels have been widely used for various systems of nuclear power plants. Among these stainless steels, small pipes with diameter less than 14 inch have been produced in the form of seamless pipe. Annealing and cooling process during the manufacturing process can affect corrosion properties of seamless stainless steels. Therefore, 12 inch-diameter of as-received 304L stainless steel pipe was annealed and aged in this study. Intergranular corrosion resistance was evaluated by ASTM A262 Practice A, C, and E methods. The degree of sensitization was determined using a DL-EPR test. U-bend method in an autoclave was used to evaluate the SCC resistance in 0.01 M $Na_2S_4O_6$ or 40% NaOH solution at $340^{\circ}C$. As-received specimen showed relatively high degree of sensitization and intergranular corrosion rate. Carbon segregation was also observed near grain boundaries. Annealing treatment could give the dissolution of segregated carbon into the matrix. Aging treatment could induce segregation of carbon and finally form carbides. Microstructural analysis confirmed that high intergranular corrosion rate of the as-received seamless pipe was due to micro-galvanic corrosion between carbon segregation and grains.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.519-527
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• 1997

AISI 316 steel has been used extensively for heater and boiler tube of the structural plants such as power, chemical and petroleum plants under severe operating conditions. Usually, material degradation due to microcrack or precipitation of carbides and segregation of impurity elements, is occured by damage accumulated for long-term service at high temperature in this material. In this study, the effect of aging time on fracture toughness was investigated to evaluate the measurement of material degradation. The elastic-plastic fracture toughness behaviour of AISI 316 steel pipe aged at $550^{\circ}C$for 1h-10000h (the aged material) was characterized using the single specimen J-R curve technique and eletric potential drop method at normal loading rate(load-line displacement speed of 0.2mm/min) in room temperature and air environment. The fracture toughness data from above experiments is compared with the $J_{in}$ obtained from predicted values of crack initiation point using potential drop method.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.4
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• pp.413-428
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• 2013

In this study, Ant Colony Algorithm(ACO) was used for optimal model. ACO which are metaheuristic algorithm for combinatorial optimization problem are inspired by the fact that ants are able to find the shortest route between their nest and food source. For applying the model to water distribution systems, pipes, tanks(reservoirs), pump construction and pump operation cost were considered as object function and pressure at each node and reservoir level were considered as constraints. Modified model from Ostfeld and Tubaltzev(2008) was verified by applying 2-Looped, Hanoi and Ostfeld's networks. And sensitivity analysis about ant number, number of ants in a best group and pheromone decrease rate was accomplished. After the verification, it was applied to real water network from S water treatment plant. As a result of the analysis, in the Two-looped network, the best design cost was found to $419,000 and in the Hanoi network, the best design cost was calculated to $6,164,384, and in the Ostfeld's network, the best design cost was found to $3,525,096. These are almost equal or better result compared with previous researches. Last, the cost of optimal design for real network, was found for 66 billion dollar that is 8.8 % lower than before. In addition, optimal diameter for aged pipes was found in this study and the 5 of 8 aged pipes were changed the diameter. Through this result, pipe construction cost reduction was found to 11 percent lower than before. And to conclusion, The least cost design model on water distribution system was developed and verified successfully in this study and it will be very useful not only optimal pipe change plan but optimization plan for whole water distribution system.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.3
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• pp.1919-1923
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• 2013

Background: Smoking is known as a major risk factor for different types of cancer, as well as cardiovascular disease. Its prevalence is increasing in developing countries. The aims of this study were to determine the prevalence of smoking and its associated factors among the population aged 40-64 years in the city of Shahroud which is a representative urban population in Iran. Materials and Methods: A cross-sectional population-based study with stratified random cluster sampling was conducted in 2009 as the first phase of Shahroud Eye Cohort Study. Of 6,311 people, 5,190 participated (82.2%). Information about smoking habit was obtained by face-to-face interview. Results: The overall prevalence of current tobacco smoking was 11.3% (95%CI: 10.5-12.3). It was significantly higher among males than females (25.7% and 0.71%, P<0.001). The prevalence of current cigarette smoking was 10.8% and 1.75% were past smokers. The smoking rate of water-pipe was 0.67%. Unemployed people smoked more than employed (OR=2.66, 95%CI: 1.38-5.14). Conclusions: The prevalence of smoking is low in Shahroud compared with other parts of Iran and other countries. Age, sex, job and marital status were associated with smoking. The low smoking rate among women may be attributed to cultural and social reasons.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.1819-1822
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• 2012

Background: In the United Arab Emirates (UAE) tobacco use is rampant. A less reported, yet widely used form of smoking native to UAE is midwakh or dhokha. The aim of the study is to assess the acute effects of smoking dokha (Arabian pipe) on the cardiovascular and respiratory systems among male university students in the UAE. Method: A quasi-experimental study was conducted among 97 male volunteers aged more than 17 years. Blood pressure, heart rate and respiratory rate of each participant, were measured before and immediately after smoking. A self administered questionnaire was used to collect personal details and data about smoking pattern. Results: Mean increases in systolic blood pressures ($12{\pm}1$ mmHg), heart rates ($20{\pm}2$ bpm) and respiratory rates ($4{\pm}1$ breaths/min) were observed (p < 0.001). A mean decrease in diastolic blood pressures ($1{\pm}1$ mmHg) was observed (p = 0.483). Conclusion: Smoking dokha has a significant acute effect on systolic blood pressure, heart rate and respiratory rate. Anti smoking campaigns must address the ill effects of this form of smoking. Results from the study warrant further research into this method of smoking which is becoming more popular.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1017-1020
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• 2008

Carburization at concrete structures is being processed independently or compositively and each unique Carburization will appear depending on the condition of circumstance. Therefore, the depletion rate was being estimated at this research for buildings and civil construction structures of different environments and of more than 10 - 60 years old by calculating the depth of carburization and the density of Alkali. As the results of the test, buildings (interior) had a deeper and a faster carburization than civil construction structures being exposed to open air as closer to the shore. And also, concrete structures being used as an underdrain of sewage were proven to have a deeper carburization than utility-pipe conduits or underground tunnels.