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.

PURPOSES: This study was conducted to investigate the causes of damage and to suggest proper repair methods for the sections in which a number of transverse cracks and faulting occurred in JCP (Jointed Concrete Pavement) slabs during the early-age performance period. METHODS: Field crack survey, FWD (Falling Weight Deflectometer) investigation, dowel bar installation condition survey, longitudinal profile survey, and in-situ core specimen inspection were conducted. . RESULTS : As a result of the analysis, it was found that there was no decline in the composite modulus of the subgrade reaction (k-value). The dowel bars were properly installed, but the LTE (Load Transfer Efficiency) of the joint and transverse cracks were analyzed to be very low. In addition, it was found that there are voids in the bottom of the slab at the joints and corners. Due to the excessive built-in curling in the early age of concrete pavement construction, upward curling displacement occurred at the joints and corners, resulting in voids at the bottom of the slab. As a result, it was found that transverse cracks occurred due to the defective joint LTE. CONCLUSIONS: Excessive built-in curling can cause early age cracks in the JCP slabs. In order to minimize the occurrence of reflection cracks after the application of the asphalt overlay in the future, concepts of alternative repair methods were proposed.