• 한국도로학회논문집
• /
• 제17권1호
• /
• pp.7-16
• /
• 2015

PURPOSES : This study was performed to determine a systematic approach for measuring the coefficient of thermal expansion (COTE) of concrete specimens. This approach includes the initial calibration of measurement equipment. Test variables include coarse aggregate types such as natural aggregate, job-site produced recycled concrete aggregate, and recycled aggregate processed from an intermediate waste treatment company. METHODS : First, two cylindrical SUS-304 specimens with a known COTE value of $17.3{\times}10^{-6}m/m/^{\circ}C$. were used as reference specimens for the calibration of each measurement system. The well-known AASHTO TP-60 COTE apparatus for concrete measurement was utilized in this study. Four different measurement apparatuses were used with each LVDT installed and a calibration value was determined using each measurement apparatus. RESULTS : In the initial experimental stage, calibration values for each measurement apparatus were assumed to be almost identical. However, using the SUS-304 samples as a reference, the calibration values for the four different measurement apparatuses were found to range from 3.49 to $8.86{\times}10^{-6}m/m/^{\circ}C$. Using different adjusted values for each measurement apparatuses, COTE values for the three different concrete specimens were obtained. The COTE value of concrete made with natural coarse aggregate was $9.91{\times}10^{-6}m/m/^{\circ}C$, that of job-site produced recycled coarse aggregate was $10.45{\times}10^{-6}m/m/^{\circ}C$, and that of recycled aggregate processed from the intermediate waste treatment company was $10.82{\times}10^{-6}m/m/^{\circ}C$. CONCLUSIONS : We observed that the COTE value of concrete made from recycled concrete aggregates (RCA) was higher than that of concrete made from natural coarse aggregate. This difference is due to the fact that the total volumetric mortar proportion in the RCA mix is higher than that in the concrete mix made with natural coarse aggregate.

• 한국도로학회논문집
• /
• 제15권2호
• /
• pp.57-63
• /
• 2013

PURPOSES : This study was performed to investigate a feasibility of job-site use of recycled concrete aggregate exceeding 3% of absorption rate. Test variables are coarse aggregate types such as natural aggregate, job-site processed recycled aggregate, and recycled aggregate processed from the intermediate waste treatment company. METHODS : First, aggregate properties such as gradation, specific gravity and absorption rate were determined. Next a basic series of mechanical properties of concrete was tested. RESULTS : All strength test results such as compression, flexure and modulus were satisfied for the minimum requirements. Finally up to first 48 elapsed days the shrinkage strains of concretes made from both recycled aggregates (in case of volume-surface ratio of 300) appeared to be greater than 26% of the companion concretes made from natural aggregates. CONCLUSIONS : Drying shrinkage result is ascribed to greater absorption rate and specific gravity of those specimens made from recycled aggregate. This may be reduced with an addition of admixtures.

• KIEAE Journal
• /
• 제14권1호
• /
• pp.131-138
• /
• 2014

The recent interests in securing alternative resource have increased due to environmental issues and exhaustion of natural resources. The government notices production of recycled aggregate using waste concrete as the substitute of the natural aggregate. However, It's important to reduce environmental burden being inevitably made in the process producing recycled aggregate. In this study, the scenarios of transportation distance were set in the transportation phase of production of recycled aggregate. In addition, The possibility of emissions and reduction of carbon dioxide were studied depending on the scenarios. For this study, data about a amount of waste concrete, transportation distance, kind of vehicle, the number of required vehicle, fuel efficiency of vehicle and etc were gathered from 15 companies of intermediate treatment and 60 constructions sites located in Daegu city and Kyungpook area. Based on those data, fuel consumptions and $CO_2$ emissions according to the transportation scheme of waste concrete were calculated. As a result of the study, the emission of carbon dioxide was possible to be reduced by 27.8~75.4% depending on the scenarios of transportation distance.

• 가정간호학회지
• /
• 제6권
• /
• pp.5-18
• /
• 1999

This study was attempt to encourage for developing on rehabilitation delivery system and programs as a substitute service instead of hospitalization for accident patients at work, such as hospital based home health care nursing service. It needs vary substitutes service of hospitalization to curtail the length of stay for inpatients who were hospitalized with workers compensation insurance. It focused on developing an estimation of early discharge day of accident inpatients based on a detail statement of treatment for 115 inpatients who were hospitalized at General Hospital in 1997. This study has four specific purpose as follows. First, to find out the status of health service utilization. Second, to estimate the early discharge days and income increasing effect based on the early discharge for those patients. Third, to identify the factors to affect total medical expenditure and the length of stay for those inpatients. Forth, to figure out the need of utilizing home health care nursing service for accident patients. In order to analyze of the length of stay and medical expenditure for inpatients who were hospitalized due to the accident, the authors conducted with micro-analysis and macroanalysis from medical records and medical expenditure records. Micro-analysis was done by nominal group discussion of 4 expertise with the critical criteria. such as a decrease in the amount of treatment after surgery, treatments, tests, drugs and changes in the tests consistency, drug methods, vital signs, start of ROM exercise, doctor's order, patient's outside visiting ability, stable conditions. In addition to identify affected variables for medical expenditure. the length of stay and income effect due to early discharge day, the data was analyzed with multiple regression analysis and linear regression analysis model by SPSS-PC for windows and Excell program. Results of this study as follows. First, the mean length of stay was 37.1 days, whereas the mean length of stay due to early discharge was 28.2 days at the hospital. The estimation of early discharge days were shown that depends on the length of stay. The longer length of stay, the longer length of early discharge days, such as under 7 days length of stay patients was to estimated the mean length of stay was 4.9 days and early discharge days was 4.6. whereas the mean length of stay was 122.6 days and early discharge days was 92.0 respectively. The mean medical expenditure per day were found to be 133.409 Won. whereas the mean medical expenditure per day was shown negative linear trends according to the length of stay at the hospital. The estimation results of the income effect due to 11 early discharge days per bed was around 2,150,000 won. However, it means not the real benefits from early discharge, but the income increasing amount without considering medical prime cost in general hospital. Therefore, it needs further analysis on the cost containments and benefits under the considering as well turn over rates per bed as the medical prime costs. The length of stay was most significant and the sign was positive to the total medical expenditure, as expected. Surgery and patient's residential area also an important variable in explaining medical expenditure. The level of complications was most significant variable in explaining the length of stay. The level of the needs on horne health care nursing service which can be used for early discharge accident patients were shown very high. The needs distribution varied from 65.5% of patients and 88.9% of caregivers, to 96.4% of doctors, and 99.1% of nurses. In addition horne health nurse responded that they can be managed the accident inpatients from early discharge. From these research findings. the following suggestions has been drawn it needs to develop strategies on rehabilitation delivery system in order to focused on consumer's side which is planned for 21 century health policy in Korea. Vary intermediate facilities and horne health care would have been developed in the community based for comprehensive rehabilitation services as a substitutes of hospitalization for shortening the length of stay of hospitalizations. In hospital based horne health care nursing service, it's available immediately to utilize for the patients who wanted rehabilitation services as a substitutes of hospitalization under the cooperations with workers compensation insurance company.