본 연구에서는 차량-교량 상호작용 시스템의 고유진동수 변화를 분석하였다. 차량이 주행하는 교량의 동특성은 차량의 질량 및 진 동을 무시하지 않는 경우 상호작용을 반영해야 하는데, 이때 시스템은 시간가변적이므로 고유진동수 또한 시간가변적인 특성을 보인 다. 따라서 본 연구에서는 차량과 교량을 각각 2자유도를 갖는 시스템으로 모델링하여 차량의 위치와 질량비 그리고 시스템 강성비에 따른 시간가변적 고유진동수를 산출하였다. 분석 결과 일반적으로 초기 고유진동수가 작은 시스템은 상호작용으로 인하여 증폭비가 낮아지는 추세를 보이나 상호작용이 발생할 경우 증폭비는 분기점을 보이며 비선형적 추세를 보이는것을 알 수 있다. 따라서 상호작 용이 발생하는 시스템차수에 대한 이해가 필요함을 알 수 있다.

본 연구의 목적은 남자 테니스 선수의 생맥산 섭취가 혈중 지질 및 동맥경화 지수에 미치 는 영향을 조사하는 것이었다. 남자 대학 테니스 선수 17 명을 4 주간의 고강도 테니스 하계훈련 중 생 맥산 섭취 여부에 따라 생맥산 섭취군(n=9)과 위약 대조군(n=8)으로 나누었다. 테니스 하계훈련은 4 주 간 주 5 회 실시하였으며, 운동강도는 예비심박수의 70~90%로 실시하였다. 생맥산은 아침 식사 전, 운 동 중, 운동 중, 운동 후 1 회 110ml, 저녁 식사 후 1 일 총 7 회 770ml 를 섭취하였다. 모든 데이터에 대해 평균 및 표준 편차를 사용하였으며, 시기간 및 생맥산 섭취그룹의 효과를 확인하기 위하여 반복 측정분산분석법을 사용하였고, 생맥산 섭취 후 혈중 지질의 차이에 대한 관련성을 알아보기 위하여 Pearson 의 상관분석을 실시하였다. 본 연구결과, 생맥산 섭취군은 혈중 지질(중성지방, 총콜레스테롤, 고밀도지단백콜레스테롤, 저밀도지단백 콜레스테롤)과 동맥경화지수가 유의하게 개선되었으며, ⲆTG, Ⲇ LDL 및 ⲆTC 간에는 유의한 상관관계가 나타났다. 결론적으로 남자 대학 테니스 선수의 고강도 트레이 닝 시 생맥산 섭취는 혈중 지질 및 동맥경화 지수에 긍정적인 영향을 미칠 수 있어 운동 보조제로서 효 과적인 스포츠 음료가 될 수 있음을 시사한다.

PURPOSES : On a thin epoxy overlay pavement, epoxy is placed on the existing bridge deck pavement, followed by the spraying of aggregates on it. The bond strength between the existing pavement and overlay pavement is an important factor representing the performance of the thin epoxy overlay pavement, in addition to the skid resistance and roughness. Therefore, the bond strength, skid resistance, and roughness of a thin epoxy overlay pavement constructed for field tests under various field conditions are examined in this study. METHODS : The usability of epoxy and aggregates on a thin epoxy overlay pavement is identified by testing their material properties in a laboratory. A construction test is performed using the pretreatment conditions of the existing pavement surface and the number of layers of overlay pavement as variables. The bond strength, skid resistance, and roughness are analyzed 3 d after constructing the test pavement, and immediately before and after applying repetitive traffic loadings at 6 months. RESULTS : When the existing pavement is in good condition, as in this study, the bond strength of the thin epoxy overlay pavement is affected more significantly by the existing pavement condition than the material properties of epoxy, in which destruction is indicated in the existing pavement. The skid resistance is affected primarily by the condition of the aggregates sprayed on the epoxy. The pavement on which the aggregates are well sprayed indicate a high skid resistance. The roughness is not affected by any variables, such as the pretreatment conditions, number of thin pavement layers, and repetitive traffic loadings. CONCLUSIONS : A long-term evaluation of the bond strength, skid resistance, and roughness will be conducted on a test pavement. In addition, another construction test will be performed to investigate the performance of a thin epoxy pavement overlaid on a bridge deck pavement under inferior conditions.

파레시아는 미셸 푸코가 제기한 개념으로 ‘진실을 행하는 것’이라는 의미인 ‘진실-말하기’라고 명명할 수 있다. ‘진실-말하기’는 철학적 논의뿐 아니라 문학에서도 유용한 분석도구로 활용할 수 있다. 문학사는 각 연대마다 진실을 말하는 용기를 가진 자의 기록이기 때문이다. 본 논문은 파레시아의 특성이 현대시에 어떠한 양상으로 표출되었는지를 파악하는 것이다. 이를 통해 2010년대 이후 시 지형도의 한 단면을 분석 할 수 있을 것이다. 먼저 파레시아의 개념과 특성을 폭넓게 분석한다. 파레시아는 솔직함, 진실, 위험, 비판, 의무의 특성을 가지고 있다. 논문에서는 파레시아의 특성이 현대시와 어떤 영향관계를 갖고 현실인식을 드러내는지를 고구한다. 이러한 텍스트로 이산하와 김안의 시를 통해 정치적 파레시아와 윤리적 파레시아의 특성을 해명한다. 결론적으로 정치적 파레시아는 위험-말하기의 특성을, 윤리적 파레시아는 비판-말하기의 특성을 가지고 있음을 해명하였다. 이를 통해 시적 현실을 새롭게 파악하는 분석도구로서 파레시아가 폭넓게 사용될 수 있다는 학술적 의의를 가진다.

PURPOSES : Rut depth of asphalt pavements is a major factor that affects the maintenance of pavements as well as the safety of drivers. The purpose of this study was to analyze the factors influencing rut depth, using data collected periodically on national highways by the pavement management system and, consequently, predict annual rut depth change, to contribute to improved asphalt pavement management. METHODS : The factors expected to influence rut depth were determined by reviewing relevant literature, and collecting the related data. Further, the correlations between the annual rut depth change and the influencing factors were analyzed. Subsequently, the annual rut depth change model was developed by performing regression analysis using age, present rut depth, and annual average maximum temperature as independent variables. RESULTS : From the sensitivity analysis of the developed model, it was found that age affected the annual rut depth change the most. Additionally, the relationship between the dependent and independent variables was statistically significant. The model developed in this study could reasonably predict the change in the rut depth of the national highway asphalt pavements. CONCLUSIONS : In summary, it was verified that the model developed in this study could be used to predict the change in the National Highway Pavement Condition Index (NHPCI), which represents comprehensive conditions of national highway pavements. Development of other models that predict changes in surface distress as well as international roughness index is required to predict the change in NHPCI, as they are the independent variables of the NHPCI prediction model.

PURPOSES : In this study, an ASR-reducing (alkali-silica reaction) cement was developed to prevent the blow-up of concrete pavements. To develop ASR-reducing cement, various amounts of ground granulated blast furnace slag (GGBFS), and fly ash (FA) were substituted with Portland cement, and the ASR reduction effect was verified through various experiments. METHODS : The physical properties of ASR-reducing cement, varying with the substitution amounts of GGBFS and FA, were verified through compressive strength tests. In addition, the ASR reduction effect was examined using accelerated mortar bar tests. Furthermore, the reasons for the ASR reduction were investigated using microstructural analysis techniques, such as XRD and TG/DTG. RESULTS : There was a difference in the compressive strength results according to the amount of GGBFS and FA substitution. In addition, the samples with GGBFS and FA exhibited relatively lower compressive strengths at 3 days, than OPC samples, but the compressive strength at 28 days was higher than that of the OPC samples. The samples with GGBFS and FA had higher compressive strength at 28 days than OPC samples, because the substituted GGBFS and FA induced pozzolanic reaction. Through XRD and TG/DTG analyses, various degrees of pozzolanic reaction occurring in the samples were examined, and a more active pozzolanic reaction occurred in the samples with FA than in the samples with GGBFS. Therefore, it appeared that the ASR reduction effect occurred because of the induced pozzolanic reaction. CONCLUSIONS : GGBFS and FA substituting Portland cement indicated an ASR reduction effect, which was owing to the pozzolanic reaction. In addition, FA indicated a greater ASR reduction effect than GGBFS, which suggested that FA induced a more active pozzolanic reaction than GGBFS.

PURPOSES : The Korea Expressway Corporation has been working on an early remodeling project for the Jungbu Expressway, to prepare techniques for the rehabilitation of the old CRCP. In this study, a literature review, field survey, and thickness design using MEPGD were conducted. This is to provide a procedure for the pre-treatment, or repair of the existing pavement in the JungBu Expressway. METHODS : To evaluate the pavement condition of the JungBu Expressway, the existing PMS data were analyzed, and field surveys were conducted for each pavement condition. The SMA overlay thickness design was performed using the pavement thickness design program (MEPGD). In addition, the repair procedure was reviewed considering the characteristics of the old CRCP in Korea. RESULTS : From the analysis of existing PMS, field surveys, and laboratory tests, it was discovered that the old CRCP condition of the Jungbu Expressway was not satisfactory. Using MEPDG, the SMA thicknesses for each scenario were proposed as 5, 8, and 10 cm. In addition, appropriate repair procedures for each distress type(punchpout, multiple repair, re-failure, failure of longitudinal joint, etc.) of damaged CRCP in Korea were proposed. CONCLUSIONS : For the remodeling project of the Jungbu Expressway, appropriate repairs should be performed for each type of distress in the old CRCP. In this study, an appropriate overlay thickness and pre-treatment method are suggested.

PURPOSES : Korea Expressway Corporation has been working on an early remodeling project for the Jungbu Expressway to prepare methods for the rehabilitation of the old CRCP(Continuous Reinforced Concrete Pavement). In this study, the distress of the old CRCP was classified, and the engineering properties of the core specimens for each failure type were evaluated. Based on the test results, the concrete conditions of the existing CRCP were evaluated. This provides a basis for the pre-treatment or repair of the existing CRCP in the JungBu Expressway. METHODS : To evaluate the pavement condition of the Jungbu Expressway, existing PMS(Pavement Management System) data were analyzed, and field surveys were conducted for each pavement condition. The longitudinal rebar depth, rebar spacing, horizontal crack, and pavement thickness were examined through core sampling and non-destructive testing. In addition, the core specimens were used to evaluate the compressive strength, chloride penetration test, chloride ion penetration resistance, and freeze-thaw resistance. RESULTS : From the analysis of existing PMS data, field surveys, and laboratory tests, it was found that the old CRCP condition of the Jungbu Expressway was not good. Various types of failures occurred, and horizontal cracks at the rebar location, upward rebar locations, and rebar corrosion were confirmed. In addition, the compressive strength was considerably high, but the durability-related index was judged to be poor. CONCLUSIONS : For the remodeling project of the Jungbu Expressway, appropriate repairs should be carried out for each type of distress in the old CRCP.

One-dimensional (1D) piezoelectric nanostructures are attractive candidates for energy generation because of their excellent piezoelectric properties attributed to their high aspect ratios and large surface areas. Vertically grown BaTiO3 nanotube (NT) arrays on conducting substrates are intensively studied because they can be easily synthesized with excellent uniformity and anisotropic orientation. In this study, we demonstrate the synthesis of 1D BaTiO3 NT arrays on a conductive Ti substrate by electrochemical anodization and sequential hydrothermal reactions. Subsequently, we explore the effect of hydrothermal reaction conditions on the piezoelectric energy conversion efficiency of the BaTiO3 NT arrays. Vertically aligned TiO2 NT arrays, which act as the initial template, are converted into BaTiO3 NT arrays using hydrothermal reaction with various concentrations of the Ba source and reaction times. To validate the electrical output performance of the BaTiO3 NT arrays, we measure the electricity generated from each NT array packaged with a conductive metal foil and epoxy under mechanical pushings. The generated output voltage signals from the BaTiO3 NT arrays increase with increasing concentration of the Ba source and reaction time. These results provide a new strategy for fabricating advanced 1D piezoelectric nanostructures by demonstrating the correlation between hydrothermal reaction conditions and piezoelectric output performance.