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.

본 논문은 고준위폐기물 처분시스템에서 공학적방벽의 열-수리-역학적(Thermal-hydraulic-mechanical) 복합거동 실증을 위 In-DEBS (In-situ Demonstration of Engineered Barrier System) 를 개발하여 구축하는 과정에 대해 설명한다. 공학적방벽은 크게 처분용기, 완충재 그리고 근계암반으로 이루어져 있는데, In-DEBS는 완충재 및 근계암반을 대상으로 지하수 유입 및 처분용기의 발열에 의한 THM 복합거동을 분석할 수 있도록 설계되어 있다. In-DEBS 현장시험은 A-KRS의 1/2.3 규모로 설계되어 있기 때문에 처분공의 지름이 약 860 mm로 작게 굴착하였다. 따라서, 처분공 안에서 센서와 히터를 삽입하면서 완충재 블록을 조립하는 것은 힘들기 때문에 완충재 블록 일체형 설치 틀(OBPA)를 개발하여 외부에서 모두 조립하였다. 완충재블록, 센서 및 히터가 조립 완료된 일체형 설치 틀은 총 무게가 약 3톤으로 매우 무겁기 때문에, 처분공에 정확히 삽입하기 위해서는 특별한 운송기구가 필요하다. 본 연구에서는 레일을 이용하여 5톤 이상의 무게를 들어서 정확한 위치에 정치 시킬 수 있는 In-DEBS 전용 크레인을 개발하여 조립완료된 완충재 블록을 삽입하였다. 근계암반의 THM 복합거동을 분석하기 위해 In-DEBS 주위로 4개의 시험공을 굴착하여 총 40개의 온도 센서와 5개의 간극수압계를 설치하였다. 또한 근계암반의 변위를 측정하기 위해 원거리에서 두 개의 경사공을 굴착하여 총 10개의 변위 센서를 삽입하였다. In-DEBS에는 공학적방벽시스템에 온도, 상대습도, 압력, 그리고 변위 센서 등 총 185개의 센서가 설치되어 있으며, 이 센서들은 모두 다채널 동시 측정이 가능한 계측시스템에 연결되어 실시간으로 현장데이터를 저장하게 된다.

선진핵주기고준위폐기물처분시스템(A-KRS, Advanced Korean Reference Repository System)을 기반으로 한 공학규모 공학적방벽시스템 열-수리-역학적 복합거동 현장시험(In-DEBS, In-situ Demonstration of Engineered Barrier System)은 2012년부터 기획되었다. 한국원자력연구원의 자체기술로 전체 시스템 구성요소를 설계하고 제작하여 2016년 5월 한국원자력 연구원의 지하처분연구시설(KURT, KAERI Underground Research Tunnel)에 설치하였다. 2016년 7월에 정상운영을 시작하여 현재까지 양질의 열-수리-역학 데이터를 생산하고 있다. 이 시험은 국내에서 최초로 설치하여 운영되는 고준위폐기물 심층처분시스템 공학규모 현장시험으로써, 대규모 공학적방벽 제작기술 개발 및 검증, 처분시스템 설치방법 개발 및 검증, 국내산 벤토나이트의 장기 열-수리-역학 거동 자료 확보, 공학적방벽 국내산 벤토나이트 완충재의 열-수리-역학(THM, thermal-hydro-mechanical) 복합거동특성 현장시험 및 THM 복합모델링 기술 검증, 공학적방벽 완충재 THM 특성 측정 및 모니터링 기술 개발 등을 통한 국내 고준위폐기물 심층처분시스템 공학적방벽의 성능검증 기술개발을 최종 목표로 하고 있다. KURT 기반 In-DEBS의 성공적인 설치와 운영을 통해 공학규모 공학적방벽의 제작 및 설치 기술을 확보할 수 있을 뿐 아니라 여기에서 생산되는 데이터를 이용하여 처분기술개발의 핵심 분야인 공학적방벽 THM 복합모델링 기술의 개발 및 검증 능력도 갖추게 될 것이다. 따라서 향후에 수행될 우리나라 고유의 실규모 처분시스템 실증기술 개발을 위한 귀중한 정보를 제공해 줄 것으로 기대된다.

목적 : 안경광학과 학생들의 현장실습 스트레스와 회복탄력성 간의 관련성을 알아보고자 하였다. 방법 : 충남지역에 소재한 안경광학과 학생 59명을 대상으로 설문조사를 시행하였다. 일반적 특성에 따른 회복 탄력성과 현장실습 스트레스에 차이가 있는지 알아보기 위하여 t-test와 one-way ANOVA를 이용하였고, 사후 검증으로는 Scheffe 검증을 실시하였다. Pearson의 상관분석을 이용하여 회복탄력성과 현장실습 스트레스간의 관계를 알아보았고, 회복탄력성이 현장실습 스트레스에 미치는 영향을 파악하기 위해 stepwise 방식에 의한 다중 회귀분석을 실시하였다. 결과 : 회복탄력성은 성별, 현장실습 만족도, 건강상태에 대한 평가, 평소의 대인관계에 따라 유의한 차이를 보였으며, 현장실습 스트레스는 성별, 현장실습 만족도, 건강상태에 대한 평가, 평소의 대인관계에 따라 유의한 차이를 보였다. 현장실습 스트레스는 회복탄력성의 하위요인 중 자기조절능력과 유의한 음의 상관관계를 보였다(r=-0.313, p=0.016). 또한, 회복탄력성 중 자기조절능력(β=-0.313, p=0.016)은 현장실습 스트레스에 통계적으로 유의한 부(-)의 영향을 미치는 것으로 분석되었다. 결론 : 안경광학과 학생의 회복탄력성은 현장실습 스트레스를 감소시키는 중요한 요인이므로, 회복탄력성 증가를 위한 교과과정의 개발 및 적용을 통하여 현장수행능력을 향상시켜야 할 것이다.

PURPOSES : This study compares the results of field-monitored unsaturated hydraulic data to verify the wetting path estimation method using the drying path on roadside soil slope. METHODS: A method proposed by Fredlund was used to estimate the wetting curves of soil water characteristic curves. Wetting curves were estimated from the drying curve acquired mainly from laboratory testing, and the estimated wetting curve was applied to the infiltration analysis to verify the estimation method. The infiltration analysis results obtained from the drying, wetting, and estimated wetting curves were compared to the field-monitored data at the same location. RESULTS : The volumetric water contents measured at 40 cm were closest to analysis results obtained from the wetting curve, whereas the volumetric water content measured at 80 cm were closest to the analysis results obtained from the drying curve. The results of the estimated wetting curves were between the results of the drying and wetting curves. The measured suction results were within the drying and wetting curves, and the estimated wetting curves were within the drying and wetting curves. Additionally, the safety factor obtained from applying the drying curves was carefully calculated, and the factor of safety of the estimated wetting curves was close to the results of the wetting curves. CONCLUSIONS : Applying a drying curve to calculate the slope stability during the rainy season will cause an overestimation of the factor of safety at roadside soil slopes. However, if the proposed estimation method of the wetting curve can be applied to the numerical analysis, the stability of the road slope can be reasonably estimated.

Ginseng has a unique production system that is different from those used for other crops. It is subject to the Ginseng Industry Act., requires a long-term cultivation period of 4-6 years, involves complicated cultivation characteristics whereby ginseng is not produced in a single location, and many ginseng farmers engage in mixedfarming. Therefore, to bring the production of Ginseng in line with GAP standards, it is necessary to better understand the on-site practices of Ginseng farmers according to established control points, and to provide a proper action plan for improving efficiency. Among ginseng farmers in Korea who applied for GAP certification, 77.6% obtained it, which is lower than the 94.1% of farmers who obtained certification for other products. 13.7% of the applicants were judged to be unsuitable during document review due to their use of unregistered pesticides and soil heavy metals. Another 8.7% of applicants failed to obtain certification due to inadequate management results. This is a considerably higher rate of failure than the 5.3% incompatibility of document inspection and 0.6% incompatibility of on-site inspection, which suggests that it is relatively more difficult to obtain GAP certification for ginseng farming than for other crops. Ginseng farmers were given an average of 2.65 points out of 10 essential control points and a total 72 control points, which was slightly lower than the 2.81 points obtained for other crops. In particular, ginseng farmers were given an average of 1.96 points in the evaluation of compliance with the safe use standards for pesticides, which was much lower than the average of 2.95 points for other crops. Therefore, it is necessary to train ginseng farmers to comply with the safe use of pesticides. In the other essential control points, the ginseng farmers were rated at an average of 2.33 points, lower than the 2.58 points given for other crops. Several other areas of compliance in which the ginseng farmers also rated low in comparison to other crops were found. These inclued record keeping over 1 year, record of pesticide use, pesticide storages, posts harvest storage management, hand washing before and after work, hygiene related to work clothing, training of workers safety and hygiene, and written plan of hazard management. Also, among the total 72 control points, there are 12 control points (10 required, 2 recommended) that do not apply to ginseng. Therefore, it is considered inappropriate to conduct an effective evaluation of the ginseng production process based on the existing certification standards. In conclusion, differentiated certification standards are needed to expand GAP certification for ginseng farmers, and it is also necessary to develop programs that can be implemented in a more systematic and field-oriented manner to provide the farmers with proper GAP management education.