PURPOSES : There has been increasing interest in South Korea on warm-mix asphalt (WMA) and cold-mix asphalt (CMA) technologies that allow production of asphalt pavement mixtures at comparatively lower temperatures than those of hot-mix asphalt (HMA) for use in pavement engineering. This study aims to evaluate the feasibility of replacing HMA pavement with WMA pavement with the goal of reducing CO2 emissions associated with asphalt production for road construction. METHODS : Changes in the dynamic modulus characteristics of WMA and HMA according to short-term and long-term aging were evaluated. In addition, the effects of water damage were evaluated for short- and long-term aging stages. RESULTS : For WMA, in the process of mixing and short-term aging, early-age dynamic modulus decreased owing to low temperature and reduced short-term aging (STA) time. This could result in early damage to the asphalt pavement depending on the applied traffic load and environmental load. CONCLUSIONS : Mastercurves of the dynamic modulus were used for comparative analysis of WMA and HMA. Compared to the dynamic modulus after STA of HMA, the estimated aging time determined by experiments for WMA to achieve the required stiffness was more than 48 hours, which is equiva-lent to approximately 4 to 5 years real service life when converted. It is considered that further studies are needed for performance optimization to achieve early-age performance of the asphalt mixes.

환경오염에 의한 미세먼지의 증가로 피부는 산화적 손상과 노화가 가속화된다. 본 연구에서는 선발된 한약재 추출물의 항산화, hyaluronic acid, filaggrin, MMP-1, ROS 항목을 평가함으로써 PM10으 로 부터의 각질형성세포 보호 효능을 확인하였다. 그 결과 1,1-diphenyl-2-picrylhydrazyl(DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid(ABTS), FRAP assay에서 농도의존적으로 항산화능 이 증가하는 것을 확인하였다. 각질형성세포에 PM10 300 ㎍/㎖을 단독으로 처리한 군에서는 hyaluronic acid 및 filaggrin이 50% 이상 감소하였으며, 고량강, 유백피, 토복령 추출물을 처리한 군에서는 증가하였 다. MMP-1의 경우 PM10 단독처리군에는 55% 이상 증가하였으나, 추출물을 처리한 경우 감소하여 콜라 겐, 엘라스틴의 분해를 저해하는 것으로 평가된다. 또한 제브라피쉬 배아를 이용한 ROS 측정의 경우 추출 물을 처리하였을 때 감소되는 것을 확인하였다. 특히 토복령 추출물의 25 μg/ml에서 음성대조군과 유사 한 형광의 세기를 나타내어 ROS의 생성이 유의적으로 감소한 것을 확인하였다. 본 연구를 통하여 선별된 한약재 소재인 고량강, 유백피, 토복령은 미세먼지로부터 피부를 보호하거나 개선할 수 있는 소재로서 피 부 개선을 위한 안티에이징 제품으로 활용될 수 있을 것으로 사료된다.

In this study, the physical properties and fracture characteristics according to the tensile load are evaluated on the materials of the polymeric filler and carbon fiber-based composite sleeve technique. The polymeric filler and the composite sleeve technique are applied to areas where the pipe body thickness is reduced due to corrosion in large-diameter water pipes. First, the tensile strength of the polymeric filler was 161.48~240.43 kgf/cm2, and the tensile strength of the polyurea polymeric filler was relatively higher than that of the epoxy. However, the tensile strength of the polymeric filler is relatively very low compared to ductile cast iron pipes(4,300 kgf/cm2<) or steel pipes(4,100 kgf/cm2). Second, the tensile strength of glass fiber, which is mainly used in composite sleeves, is 3,887.0 kgf/cm2, and that of carbon fiber is up to 5,922.5 kgf/cm2. The tensile strengths of glass and carbon fiber are higher than ductile cast iron pipe or steel pipe. Third, when reinforcing the hemispherical simulated corrosion shape of the ductile cast iron pipe and the steel pipe with a polymeric filler, there was an effect of increasing the ultimate tensile load by 1.04 to 1.06 times, but the ultimate load was 37.7 to 53.7% compared to the ductile cast iron or steel specimen without corrosion damage. It was found that the effect on the reinforcement of the corrosion damaged part was insignificant. Fourth, the composite sleeve using carbon fiber showed an ultimate load of 1.10(0.61T, 1,821.0 kgf) and 1.02(0.60T, 2,290.7 kgf) times higher than the ductile cast iron pipe(1,657.83 kgf) and steel pipe(2,236.8 kgf), respectively. When using a composite sleeve such as fiber, the corrosion damage part of large-diameter water pipes can be reinforced with same level as the original pipe, and the supply stability can be secured through accident prevention.

본 연구는 수직 벽체형 콘크리트 구조물의 정밀안전진단을 위한 외관조사시 고품질 정밀영상을 자동화된 방식으로 획득하여 균열손상을 탐지하고 시설물의 상태를 평가하기 위하여 개발된 등벽드론 탑재형 균열진단 시스템에 대한 것이다. 본 논문에서는 영상기반 균열진단 시스템을 이용한 정밀영상 획득기술, 자동화된 영상처리 알고리즘을 이용한 데이터 처리 기법을 제시하였으며, 실험적으로 도출된 지상표본거리를 기반으로 영상처리 자동화 알고리즘을 이용하여 생성된 균열모사 시험벽체의 평면전개 이미지 상 균열손상의 위치 정확도를 평가 분석하였다. 평가분석 결과, 가로축 길이 대비 최대 1.1%, 세로축 길이 대 비 최대 1.4%의 오차율을 보이는 것으로 나타났다. 제안된 영상 내 픽셀 좌표와 지상표본거리를 기반으로 균열손상의 위치를 추정하는 기법은 실측 좌표 대비 평균 1.0% 이하의 위치 오차를 가지는 것으로 평가되었다. 최종적으로 영상기반 진단과 긴급 보수와 같은 일반적인 시설물의 유지관리에 요구되는 위치 정확도를 확보하고 있는 것으로 분석되었다.

In this paper, seismic performance evaluation was carried out for eight circular reinforced concrete columns designed seismically by KRTA[1]and KCI[8]. Primary design parameters for such columns included many longitudinal reinforcements, yield strength of reinforcements, the vertical spacing of spirals, aspect ratio, and axial force ratio. The test results showed that all the columns exhibited stable hysteretic and inelastic responses. Based on the test results, drift ratios corresponding to each damage state, such as initial yielding, initial cover spalling, initial core concrete crushing, buckling, and fracture of longitudinal reinforcement and final spalled region, were evaluated. Then, those ratios were compared with widely accepted damage limit states. The comparison revealed that the existing damage states were considerably conservative. This implies that additional research is required for the damage limit states of such columns designed seismically by current Korean design codes.

본 연구에서는 하수 재이용을 위한 역삼투막 공정에서 전처리 정밀여과막(MF) 손상에 대한 누출되는 다양한 수 질변화로써 막 손상 검지 방안을 제시하였다. 이를 위하여 역삼투막 유입수질 적합성 평가지표인 SDI (silt density index)를 3에서 5의 범위 내에서 막 손상 시 검지 감도를 정량화하기 위하여 전처리 분리막이 1에서 3가닥 파단에 따라 SDI는 1.92에 서 6.11까지 증가한 결과를 확인할 수 있었다. 일반적으로 3을 기준으로 역삼투막 유입수질로 설정하였을 때 분리막이 3가닥 까지 파단이 되어야만 막 손상 검지가 가능하다는 것을 의미하며 역삼투막의 오염은 잠재적으로 가속화되어 효율을 저하시 킬 수 있다. 또한 이때 누출되는 입자성과 유기물질에 대하여 0.45 μm 이상의 크기만 걸러주는 입자계수는 입도분포별 막 파 단 개수에 따라 일정한 패턴을 확인할 수 없었으며, TOC 농도는 약 2배의 변화패턴으로써 SDI와의 상관관계로써 TOC가 막 손상 수질지표로써 신뢰성이 높은 것으로 확인되었다. 수질분석결과와 더불어 USEPA에서 제시하는 막 손상 검지 방법 중 압력손실시험과 이를 기반으로 LRVDIT 모델의 적합성 평가를 한 결과 막 손상 또는 역삼투막 공정으로 유입되는 막오염물질 을 신속하게 확인할 수 있는 SDI 및 TOC를 포함한 LRVDIT 모니터링과 UCL 설정을 병행해야 한다.

후쿠시마 원전사고 발생으로 다수기의 지진안전성에 관한 연구의 필요성이 부각되었다. 한 부지에 건설된 원자력발전소의 경우 유 사한 지진응답을 보이기 때문에 적게나마 원자력발전소 SSCs간의 지진손상에 대하여 상관성이 존재하므로 합리적 지진안전성 평가 를 위하여 지진손상 상관성을 고려하여야 한다. 본 연구에서는 쌍둥이 호기의 필수전원상실사건에 대하여 확률론적 지진안전성 평가 를 수행하였다. 적절한 지진손상 상관계수를 도출하기 위하여 확률론적 지진응답해석을 수행하여 적용하였다. External Event Mensuration System 프로그램을 활용하여 다수기의 필수전원상실사건의 고장수목을 구성하여 지진취약도 및 지진리스크를 분석하 였다. 또한 SSCs간의 지진손상 상관성을 완전독립 및 완전종속으로 고려하여 비교 분석을 수행하였다.

The purpose of this study was to evaluate the corrosion damage of large diameter metallic pipes buried in reclaimed land due to the corrosion effect by soil, and to propose a method of installing metal pipes in the reclaimed land. The results are as follow. First, the soil of the reclaimed land was gray clay, the soil specific resistance indicating soil corrosiveness was at least 120 Ω-cm, the pH was weakly acidic(5.04 to 5.60), the redox potential was at least 62 mV, the moisture content was at most 48.8%, and chlorine ions and sulfate ions were up to 4,706.1 mg/kg and 420 mg/kg. Therefore, the overall soil corrosivity score was up to 19, and the external corrosion effect seems to be very large. Second, the condition of straight part of pipes was in good condition, but most of KP joints were affected by corrosion at a severe level. The reason for this seems to be that KP joints accelerated corrosion due to stress and crevice corrosion in addition to galvanic corrosion in the same environment. Third, as a result of evaluating correlations of each item that affects the corrosion on the external part, the lower the soil resistivity and redox potential, the greater the effect on the KP joints corrosion, and the moisture content, chloride ion, and sulfate ion, the higher the value, the greater the effect on the corrosion of KP joints. In addition, among soil corrosion items, the coefficient of determination of soil resistivity with corrosion of KP joints was the highest with 0.6439~0.7672. Fourth, when installing metal pipes or other accessories because the soil of the reclaimed land is highly corrosive, it is necessary to apply a corrosion preventive method to extend the life of pipes and prevent leakage accidents caused by corrosion damage to the joint.

This study introduces a newly developed PC non-bearing wall system to prevent the damage of RC wall-type apartments that have been heavily damaged by the 2017 Pohang Earthquake. In order to evaluate the performance of the developed PC non-bearing wall system, a static cyclic test is conducted. The prototype of test specimen is from the RC wall-type apartment which has been severely damaged by the 2017 Pohang Earthquake. The specimen with the conventional non-bearing wall system showed the similar damage of RC wall type apartment suffered from the Pohang Earthquake. In case of the specimen with the developed PC non-bearing wall system, cracks and damages were not transmitted between the walls due to the seismic slit and there were almost no cracks in the non-bearing walls. Therefore, the proposed non-bearing wall system, separated from the structural walls, could prevent spreading cracks to bearing walls and make it possible to effectively control damage due to earthquake loads.

PURPOSES: Spalling is one of the primary problems that lead to the damage of concrete pavements. The purpose of the study is to analyze the impact range of spalling that occurred in an area of concrete pavement by applying a variety of nondestructive and destructive testing methods. METHODS: Spalling of the concrete pavement was categorized into four different sizes, 0 cm, 7.5 cm, 15 cm, and 30 cm. Nondestructive and destructive tests were performed at the point of spalling and 1 m away, respectively, and the obtained results were compared. The nondestructive tests included the electrical resistance test and the ultrasonic velocity test as well as strength tests by Schmidt hammer and concrete tester. The destructive tests included the direct compressive strength test and the chloride content test using field cored specimens. The test results helped in the analysis of the correlation between the current spalling damage condition and the expected damage acceleration. RESULTS: Based on the present study, the repair area and depth of spalling for a partial depth repair was suggested. It was also shown that the size of the spalling is highly correlated with the chloride content and the electrical resistance of the concrete pavement. CONCLUSIONS: The degree of spalling deterioration was found to be highly correlated with the chloride content and electrical resistance of the concrete pavement and based on the results, the extent of repair could be determined more quantitatively.

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.

The purpose of this study is to evaluate the structural safety of cultural altar since its bearing capacity has been questioned due to weathering damages and sectional defections. This evaluation process consists two stages; which the first is field investigation and the second is structural modeling and analysis. Based on field investigation, all of the structural members supporting the altar were carefully examined and all the findings were accounted for the development of the structural modeling using the Midas computer program. Using a 3D scanner, the weight of the Buddha statue was applied to the structural modeling. Then, according to the allowable stress design method of KBC2016, the structural safety was evaluated. Based on this result, replacements of several structural members were recommended to increase the structural safety and value of cultural property.

목적 : 본 연구는 국내 재활의 결과 측정 및 지역사회 참여와 통합의 정도를 확인하기 위해 미국에서 개발된 Craig Handicap Assessment and Reporting Technique(CHART)를 번역과정을 거쳐 한국 번역판 CHART를 완성하였으며, 신뢰도 및 타당도를 검증하였다. 연구방법 : 연구 대상자로는 지역사회에 거주하는 척수손상 환자 100명과 장애가 없는 일반인 100명으로 총 200명이었다. 번역 및 역번역 검증을 통해 CHART-K를 완성하였고, 국내에 적용하기 위해 예비연구를 진행하였다. 이 후 신뢰도와 타당도를 확인하였다. 결과 : 내용타당도는 0.97로 높은 수준을 수립하였으며, 삭제된 문항은 없었다. 판별타당도 검증에서는 척수손상 환자의 총점수의 평균은 일반인 대상자보다 낮은 점수를 확인하였고 통계적으로 유의미한 차이를 보였다 (p<.01). 수렴타당도 검증에서 Korean-Community Integration Questionnaire(K-CIQ)와 상관관계 분석을 실시한 결과 .524로 통계적으로도 유의미하였다(p<.01). 내적일치도는 Cronbach’s α .628로 양호한 수준이었으며, 검사-재검사 .730~ .992로 유의미한 상관관계를 보였다(p<.01). 결론 : 본 연구를 통해 CHART를 번역하고 국내의 실정에 맞게 CHART-K를 완성하고, 신뢰도 및 타당도를 확인하였다. 따라서 척수손상 환자의 국내 재활의 결과 측정 및 지역사회 참여와 통합의 정도를 측정하고 기존 평가도구의 한계점을 보완한 도구로 활용될 수 있을 것으로 기대된다.

Stone pagoda structures have continued to be aged due to the combination of various damage factors. However, some studies on nonstructural damage have been carried out, but assessment studies on structural damage have not been done in various ways. Therefore, in this study, structural and nonstructural influencing factors according to the damage types are classified and the damage assessment according to the structural influencing factors affecting the behavior of the stone pagoda structure is performed. In addition, the damage rating classification criteria for each type of structural damages or damage locations are presented, and the damage index is calculated by providing the criteria for the classification of damage according to the degree of damage to which the damage is caused. Therefore, this study can evaluate quantitatively the damage status of stone pagoda structures.

In the present study, the impact of RO polyamide layer by long-term chemical exposure was evaluated. Basic cleaning chemicals such as NaOH increased the pure water flux and salt passage of RO membrane up to 1.6 times and 2 times, respectively. In contrast, membranes exposed to acidic chemicals such as HCl have experienced no discernible change of permeability, which indicated that basic chemicals caused the more serious damage to RO polymeric layers. However, XPS analysis showed that both membranes were experienced significant damages on cross-linking of polyamide structures. It can be concluded that basic cleaning chemicals induced the enlarged pore structure due to electrostatic repulsion between damaged polymers, while acidic chemicals caused less performance deterioration by shrinkage of the polyamide structure.