PURPOSES: This study developed a new backfill method for mini trenching. The purpose of this study is to evaluate the performance of the new backfill method in the field. METHODS: In this study, asphalt pavement was created to verify mini trenching. Trenching test sections were then made in various trench widths in the asphalt pavement. The trench widths were 10 cm, 15 cm, 20 cm, and 25 cm. For the trenching test section, a general backfill method and new backfill method (2-layer SCB) were devised and applied. To evaluate the test section, a vehicle loading test and FWD (falling weight deflectometer) test were performed. RESULTS : In the vehicle loading test, the duct vertical strain of the general section was up to 22 times larger than that of the 2-layer SCB section. According to the results of the FWD test, the D0 deflection of the 2-layer SCB section was smaller than that of the general section. These results indicate that 2-layer SCB has a good structural performance. With the use of FWD data, BLI (base layer index) and MLI (middle layer index) were analyzed. BLI is an indirect index for evaluating base layer. The BLI of the 2-layer SCB section was smaller than that of the general section, because the bottom layer (cellular mortar) of the 2-layer SCB is superior to that of the general section. MLI, on the other hand, is an indirect index for evaluating subbase layer. As the trench width increases, MLI increases. The MLI of the 2-layer SCB section was smaller than that of the general section. These results indicate that the damage is relatively greater when the trench width increases and that the 2-layer SCB strengthens a relatively weakened subbase. CONCLUSIONS: In this study, the performance of the 2-layer SCB was analyzed. The results of the study showed that good performance was obtained when 2-layer SCB was applied to a mini trenching section.

We used three gas sensors to monitor hydrogen sulfide, ammonia, and volatile organic compounds (VOCs), which were frequently emitted from environmental facilities, such as municipal wastewater treatment, livestock manure treatment, and food waste composting facilities. Two electrochemical (EC) sensors for detecting hydrogen sulfide and ammonia, and a photoionization detector (PID) sensor for detecting VOCs were characterized in this study. The performance of their linearity by concentration levels, lower detection limit (LDL), repeatability, reproducibility, precision, and response time were tested under the laboratory condition. The linearity according to concentration levels were favorable for all three sensors with high correlation coefficients (R2 > 0.98). The ammonia sensor showed the highest LDL (18.6 ppb) and the hydrogen sulfide and VOC sensors showed 22.3 ppb and 26.7 ppb of LDL, respectively. The reproducibility and precision were favorable for all three sensors, indicating a lower relative standard deviation (RSD) than 0.9% in the reproducibility test and 7.2% in the precision test. The response times to reach target concentration were varied from 1 to 12 minutes. The ammonia sensor needed 12 minutes of response time at 1 ppm target the NH3 concentration and the hydrogen sulfide and VOC sensors needed less than 2 minutes of response time.

본 연구는 나날이 중요하게 부각이 되는 대학생들의 진로에 관한 연구로 사회복지학과 학생들 중 현장실습을 이수하고 취업을 준비하는 학생들의 진로자기효능감에 대하여 살펴보고자 하였다. 일차적으로 진로자기효능감에 영향을 미치는 사회복지현장실습생의 진로의사를 세 가지 진로의사유형으로 보고 이를 독립변인으로 선정하여 진로의사결정 유형 각각의 변인이 진로자기효능감에 미치는 영향을 보고자 하였으며, 또한 진로스트레스 및 수퍼바이저와의 관계가 진로의사결정유형과 진로자기효능감 간을 조절하는 효과가 있는 지를 알아보고자 하는 목적으로 본 연구를 실시하였다. 본 연구결과는 다음과 같았다. 첫째, 연구문제1 연구문제 2는 지지되었다. 둘째, 연구 가설 3은 합리적, 직관적 의사결정유형은 지지되었고 의존적 의사결정유형은 지지되지 않았다.