본 연구에서는 SiO2 나노파티클-전도성 고분자 PEDOT:PSS 복합 구조 기반의 유기발광다이오 드용 내부 광추출 구조를 간단한 용액 공정으로 제작하였다. 또한, 다양한 농도의 SiO2 나노파티클을 PEDOT:PSS에 분산하여 그 구조를 확인하였고, 상부/하부 버퍼레이어의 도입이 내부 광추출 구조 형성에 미치는 영향에 관하여 알아보았다.

Microstructure, electric, and thermal properties of the Ta-Cu composite is evaluated for the application in electric contact materials. This material has the potential to be used in a medium for a high current range of current conditions, replacing Ag-MO, W, and WC containing materials. The optimized SPS process conditions are a temperature of 900oC for a 5 min holding time under a 30 MPa mechanical pressure. Comparative research is carried out for the calculated and actual values of the thermal and electric properties. The range of actual thermal and electric properties of the Ta-Cu composite are 50~300W/mk and 10~90 %IACS, respectively, according to the compositional change of the 90 to 10 wt% Ta-Cu system. The results related to the electric contact properties, suggest that less than 50 wt% of Ta compositions are possible in applications of electric contact materials.

In this paper, a structural design method of a smart tuned mass damper (TMD) for a retractable-roof spatial structure under earthquake excitation was proposed. For this purpose, a retractable-roof spatial structure was simplified to a single degree of freedom (SDOF) model. Dynamic characteristics of a retractable-roof spatial structure is changed based on opened or closed roof condition. This condition was considered in the numerical simulation. A magnetorheological (MR) damper was used to compose a smart TMD and a displacement based ground-hook control algorithm was used to control the smart TMD. The control effectiveness of a smart TMD under harmonic and earthquake excitation were evaluated in comparison with a conventional passive TMD. The vibration control robustness of a smart TMD and a passive TMD were compared along with the variation of natural period of a simplified structure. Dynamic responses of a smart TMD and passive TMD under resonant harmonic excitation and earthquake load were compared by varying mass ratio of TMD to total mass of the simplified structure. The design procedure proposed in this study is expected to be used for preliminary design of a smart TMD for a retractable-roof spatial structure.

Fluorine-doped tin oxide (FTO) coated NiCrAl alloy foam is fabricated using ultrasonic spray pyrolysis deposition (USPD). To confirm the influence of the FTO layer on the NiCrAl alloy foam, we investigated the structural, chemical, and morphological properties and chemical resistance by using USPD to adjust the FTO coating time (12, 18, and 24 min). As a result, when an FTO layer was coated for 24 min on NiCrAl alloy foam, it was found to have an enhanced chemical resistance compared to those of the other samples. This improvement in the chemical resistance of using USPD NiAlCr alloy foam can be the result of the existence of an FTO layer, which can act as a protection layer between the NiAlCr alloy foam and the electrolyte and also the result of the increased thickness of the FTO layer, which enhances the diffusion length of the metal ion.

본 연구에서는 Karman이 제시한 풍방향 변동풍속 스펙트럼 및 Liang이 제시한 풍직각방향 변동풍하중 스펙트럼을 이용하여 풍방향 및 풍직각방향 풍하중을 생성하고, 생성된 풍하중을 적용하여 고정기초 및 면진기초 구조물의 동적 거동을 해석하여 풍하중이 작용하는 고정기초 구조물과 면진기초 구조물의 동적거동을 해석하여 면진기초에 의한 풍응답 증가에 대하여 비교분석하였다.

The demand for skyscrapers is increasing worldwide. Until now, various lateral resistance structures have been used for lateral displacement control of high-rise buildings. An outrigger damper system has been introduced recently to improve lateral dynamic response control performance further. However, a study of outrigger damper system is yet to be sufficiently investigated. In this study, time history analysis was performed to investigate the control performance of an outrigger damper system of high-rise building under eccentric loading. To do this, an actual scale 3-dimensional tall building model with an outrigger damper system was prepared. The control performance of the outrigger damper system was evaluated by varying stiffness and damping values. On the top floor torsional angle response to the earthquake load, was greatly affected by damping value. And the displacement response was affected greatly by the stiffness value and damping value of damper system. In conclusion, it is necessary to select the proper damping and stiffness values of the outrigger damper system.

Transparent conducting oxides (TCOs) were fabricated using solution-based ITO (Sn-doped In2O3) nanoinks with nanorods at an annealing temperature of 200 oC. In order to optimize their transparent conducting performance, ITO nanoinks were composed of ITO nanoparticles alone and the weight ratios of the nanorods to nanoparticles in the ITO nanoinks were adjusted to 0.1, 0.2, and 0.5. As a result, compared to the other TCOs, the ITO TCOs formed by the ITO nanoinks with weight ratio of 0.1 were found to exhibit outstanding transparent conducting performance in terms of sheet resistance (~102.3 Ω/square) and optical transmittance (~80.2%) at 550 nm; these excellent properties are due to the enhanced Hall mobility induced by the interconnection of the composite nanorods with the (440) planes of the short lattice distance in the TCOs, in which the presence of the nanorods can serve as a conducting pathway for electrons. Therefore, this resulting material can be proposed as a potential candidate for solution-based TCOs for use in optoelectronic devices requiring large-scale and low-cost processes.

In order to reduce damages to major railroad components, which have the potential to cause interruptions to railroad services and safety accidents and to generate unnecessary maintenance costs, the development of rolling stock maintenance technology is switching from preventive maintenance based on the inspection period to predictive maintenance technology, led by advanced countries. Furthermore, to enhance trust in accordance with the speedup of system and reduce maintenances cost simultaneously, the demand for fault diagnosis and prognostic health management technology is increasing. The objective of this paper is to propose a highly reliable learning model using various machine learning algorithms that can be applied to critical rolling stock components. This paper presents a model for railway rolling stock component fault diagnosis and conducts a mechanical failure diagnosis of motor components by applying the machine learning technique in order to ensure efficient maintenance support along with a data preprocessing plan for component fault diagnosis. This paper first defines a failure diagnosis model for rolling stock components. Function-based algorithms ANFIS and SMO were used as machine learning techniques for generating the failure diagnosis model. Two tree-based algorithms, RadomForest and CART, were also employed. In order to evaluate the performance of the algorithms to be used for diagnosing failures in motors as a critical railroad component, an experiment was carried out on 2 data sets with different classes (includes 6 classes and 3 class levels). According to the results of the experiment, the random forest algorithm, a tree-based machine learning technique, showed the best performance.

본 논문에서는 와이어로프 손상의 정량화를 위하여 먼저 동일한 소재 및 직경을 가지는 강봉을 이용한 누설자속기반 결함 탐상 연구를 진행하였다. 현재까지 국외 및 국내에서 누설자속탐상 기법을 이용하여 결함을 탐상하는 연구가 많이 진행되어 왔지만, 그 손상을 진단하는 것에 그쳐 손상의 정도를 판별하여 그에 따른 적절한 조치를 취하는 것에 어려움이 있다. 따라 서 본 논문에서는 전자기적 유한요소 해석 프로그램을 이용하여 누설자속탐상 시스템을 모델링하였으며 강봉을 강자성체 시편으로 이용하여 누설자속탐상 시뮬레이션을 진행하였다. 또한 시뮬레이션 결과를 검증하기 위하여 실제 강봉에 시뮬레이 션과 동일한 종류의 손상을 가공하여 결함탐상 실험을 진행하였다. 시뮬레이션과 실험 데이터를 분석한 결과 탐상 속도는 신호의 크기에 미소한 영향을 주었으며, 손상의 너비 변화에 따라 신호의 크기가 동일하지 않음을 검증할 수 있었다. 본 분 석을 토대로 깊이 손상과 너비 손상에서의 신호 특성을 추출하여 손상의 종류를 분별할 수 있었고, 역으로 추출된 신호의 특 성을 이용하여 손상의 종류를 판별할 수 있는 가능성을 확인하였다.

A retractable-roof spatial structure is frequently used for a stadium and sports hall. A retractable-roof spatial structure allows natural lighting, ventilation, optimal conditions for grass growth with opened roof. It can also protects users against various weather conditions and give optimal circumstances for different activities. Dynamic characteristics of a retractable-roof spatial structure is changed based on opened or closed roof condition. A tuned mass damper (TMD) is widely used to reduce seismic responses of a structure. When a TMD is properly tuned, its control performance is excellent. Opened or closed roof condition causes dynamic characteristics variation of a retractable-roof spatial structure resulting in off-tuning. This dynamic characteristics variation was investigated. Control performance of a passive TMD and a smart TMD were evaluated under off-tuning condition.

The seismic isolation system reduces the seismic vibration that is transmitted from foundation to upper structure. This seismic isolation system can be classified into base isolation and mid-story isolation by the installation location. In this study, the seismic behavior of dome structure with mid-story isolation is analyzed to verify the effect of seismic isolation. Mid-story isolation is more effective than base isolation to reduce the seismic responses of roof structure. Also, this isolation would be excellent in structural characteristics and construction.

In recent years, an outrigger damper system has been proposed to reduce dynamic responses of tall buildings. However, a study on outrigger damper system is still in its early stages. In this study, time history analysis was performed to investigate the dynamic response control performance of outrigger damper. To do this, a actual scale 3-dimensional tall building model with outrigger damper system has been developed. El Centro earthquake was applied as an earthquake excitation. The control performance of the outrigger damper system was evaluated by varying stiffness and damping values. Analysis results, on the top floor displacement response to the earthquake load, was greatly effected by damping value. And acceleration response greatly was effected by stiffness value of damper system. Therefore, it is necessary to select that proper stiffness and damping values of the outrigger damper system.

An outrigger damper system has been proposed to reduce dynamic responses of tall buildings. In previous studies, an outrigger damper system was optimally designed to decrease a wind-induced or earthquake-induced dynamic response. When an outrigger damper system is optimally designed for wind excitation, its control performance for seismic excitation deteriorates. Therefore, a smart outrigger damper system is proposed in this study to make a control system that can simultaneously reduce both wind and seismic responses. A smart outrigger system is made up of MR (Magnetorheological) dampers. A fuzzy logic control algorithm (FLC) was used to generate command voltages sent for smart outrigger damper system and the FLC was optimized by genetic algorithm. This study shows that the smart outrigger system can provide good control performance for reduction of both wind and earthquake responses compared to the general outrigger system.

This study analyze the dynamic response property of latticed domes according to natural frequency ratio of substructure. Through eigenvalue analysis, it is was confirmed that the half-open angle 30° and 45° dominate vibration mode of the vertical direction and the half-open angle 60° and 90° dominate vibration mode of the horizontal direction. Through the dynamic response analysis, it is was confirmed that the first frequency about total structure largely appears about the vertical and the horizontal direction regardless of half-open angle.

To identify the cause of the error and maintain the health of system, an administrator usually analyzes event log data since it contains useful information to infer the cause of the error. However, because today’s systems are huge and complex, it is almost impossible for administrators to manually analyze event log files to identify the cause of an error. In particular, as OpenStack, which is being widely used as cloud management system, operates with various service modules being linked to multiple servers, it is hard to access each node and analyze event log messages for each service module in the case of an error. For this, in this paper, we propose a novel message-based log analysis method that enables the administrator to find the cause of an error quickly. Specifically, the proposed method 1) consolidates event log data generated from system level and application service level, 2) clusters the consolidated data based on messages, and 3) analyzes interrelations among message groups in order to promptly identify the cause of a system error. This study has great significance in the following three aspects. First, the root cause of the error can be identified by collecting event logs of both system level and application service level and analyzing interrelations among the logs. Second, administrators do not need to classify messages for training since unsupervised learning of event log messages is applied. Third, using Dynamic Time Warping, an algorithm for measuring similarity of dynamic patterns over time increases accuracy of analysis on patterns generated from distributed system in which time synchronization is not exactly consistent.

With increasing interest, there have been studies on LiDAR(Light Detection And Ranging)-based DEM(Digital Elevation Model) to acquire three dimensional topographic information. For producing LiDAR DEM with better accuracy, Filtering process is crucial, where only surface reflected LiDAR points are left to construct DEM while non-surface reflected LiDAR points need to be removed from the raw LiDAR data. In particular, the changes of input values for filtering algorithm-constructing parameters are supposed to produce different products. Therefore, this study is aimed to contribute to better understanding the effects of the changes of the levels of GroundFilter Algrothm’s Mean parameter(GFmn) embedded in FUSION software on the accuracy of the LiDAR DEM products, using LiDAR data collected for Hwacheon, Yangju, Gyeongsan and Jangheung watershed experimental area. The effect of GFmn level changes on the products’ accuracy is estimated by measuring and comparing the residuals between the elevations at the same locations of a field and different GFmn level-produced LiDAR DEM sample points. In order to test whether there are any differences among the five GFmn levels; 1, 3, 5, 7 and 9, One-way ANOVA is conducted. In result of One-way ANOVA test, it is found that the change in GFmn level significantly affects the accuracy (F-value: 4.915, p<0.01). After finding significance of the GFmn level effect, Tukey HSD test is also conducted as a Post hoc test for grouping levels by the significant differences. In result, GFmn levels are divided into two subsets ( ‘7, 5, 9, 3’ vs. ‘1’). From the observation of the residuals of each individual level, it is possible to say that LiDAR DEM is generated most accurately when GFmn is given as 7. Through this study, the most desirable parameter value can be suggested to produce filtered LiDAR DEM data which can provide the most accurate elevation information.

개발도상국인 몽골(울란바토르)은 경제가 발전하면서 물류의 원동력인 중차량이 많이 증가하고 있으며, 교류 활성화 및 국민들의 삶의 질을 개선하고자 기반 시설인 도로 건설과 유지관리에 많은 예산을 투자하고 있다. 하지만, 급격한 차량 증가 및 도로포장 기술의 부재로 인하여 도로 포장이 설계 당시의 공용수명에 이 르지 못하고 조기에 파손이 발생하는 일이 빈번하게 발생하고 있는 실정이다. 이러한 개발도상국(몽골, 베 트남, 캄보디아, 중국 등)의 중차량 증가 및 집중호우 등의 기후 변화와 맞물려 나타나는 것이 아스팔트 포 장 성능 저하, 공용 수명 저하로 나타난다. 또한, 이러한 현상은 도로 조건을 고려하지 못한 품질관리 체계 미흡, 시공 조건을 파악하지 못한 관리 불량 등에 기인하며, 개발도상국 현지화 기술 개발을 통한 도로 포장 의 파손 문제해결과 유지보수 비용 절감을 위한 대응 방안이 필요한 실정이다. 최근 개발도상국 기후, 차량 하중, 시공조건 및 경제여건 등을 고려할 때 맞춤형 택코팅 보호 필름이 부착된 아스팔트 보강재(ESGRID) 를 이용한 현지 사업을 통하여 중소기업 신규 시장 발굴, 기술개량 및 상용화 지원이 필요한 실정이다. 본 연구에서는 개도국 현지 적용을 위하여 국내에서 적용하는 비용의 40% 정도를 절감하는 제품을 개 발하였으나, 동일한 성능을 발현하도록 설계하여 비용 대비 제품 효용성을 향상시켰다. 이러한 개발을 통 하여 몽골의 Sharga morit Bridge구간에 2015년 10월에 시험 시공을 하였다. 시험시공 당시 방수층까지 시공되어 있었으나, 중앙분리대 부근 음지부에는 얼음이 얼어 있었으며, 일부 방수층에 균열이 발생한 상 태였다. ESGRID는 인력시공을 하였고, 겹이음 부분은 스프레이접착제를 이용해 부착을 하여 중앙 부분 을 강화하였다. 또한 방수층이 경화된 이후라 ESGRID의 접착력 확보를 위해 RSC-4 택코팅을 추천하였 으나, 장비의 부재로 AP-5를 녹여서 택코팅을 대체하였다. 이 방법은 방수층과 ESGRID와의 접착력 확 보에는 큰 도움이 되지는 않을 것으로 보인다. 2015년 12월에 추적 조사를 실시한 결과 문제가 없는 것으 로 확인되었다. 이로 인하여 아시아 개도국 현지 도로 조건에 적합한 적정 기술 개발로 신규 건설 및 유지 보수 비용의 절감 효과를 기대할 수 있다.

도로 포장의 열화 및 손상원인은 다양한 형태로 나타나고 있으나, 침투수 및 유해물질에 의한 내부층 열화, 동절기 염화물 살포에 의한 표면 손상, 차량 통행의 증가에 따른 포장층 처짐 및 균열 발생 등 복합 적인 요인에 의해서 발생하고 있다. 이러한 손상원인은 대부분 표층 상부에서 발생하여 하부층으로 침투 (전달)되는 형태가 대부분으로, 이에 대한 포장층 상부 보강 노력이 절실히 필요하다고 할 수 있다. 또한, 도로 보수공사시 발생할 수 있는 하부층의 반사균열 역시 제어가 필요한 부분이라 할 수 있다. 이러한 원 인에 대한 포장층 강화 수단으로 쉬트 형태의 아스팔트 보강재를 개발하고자 하였으며, 주요 구성요소인 섬유 그리드 및 필름 개선에 따른 실질적인 성능 향상을 목표로 포장가속시험(Acceleration Pavement Test, APT)을 진행하였다. 시험적용은 한국건설기술연구원 內의 포장가속 테스트 부지(10×3 m)에 그림 1과 같은 적용 절차로 진 행하였고, 아스팔트 보강재(ESGRID-AA) 설치구간과 미설치구간으로 나누어 실시하였다. 포장체에 적용 되는 차륜하중은 그림 2의 그래프에서 보는 것과 같이 하중을 점진적으로 증가시켜, 재하 하중별로 나타 나는 공용 특성을 분석하였다. 시험 결과, 일정 기준의 하중(시험에서는 6t 2만회 재하) 이하에서는 처짐이 거의 나타나지 않고 있다. 이는 보강재를 사용하지 않은 일반 아스콘의 4t 재하시의 처짐 형태와 비슷한 형상으로써, 차량하중을 견 딜 수 있는 능력이 무보강 상태보다 현저히 증가한 결과라고 할 수 있다. 또한, 이후 재하과정에서도 점진 적인 처짐 형상이 나타나고 있어, 급격한 처짐이 발생하는 시점에서의 보수･보강 시기를 상당히 지연시킬 수 있는 결과라고 할 수 있다. 이를 수치화하여 구체적이고, 정량적인 성능 개선효과를 판단하기 위해, ESAL(등가단축하중) 분석을 통한 보강재의 공용성을 확인하고자 하였다. 일반적으로 분석에 사용되는 소 성변형(Rutting) 깊이는 구체적인 기준이 존재하지 않지만, 일반적으로 13mm에 해당하는 구간의 데이터 를 확보하여 공용성을 판단한다. 이를 정량화 하였을 때, 약 170%의 성능 향상과 함께, 보수 시기 지연에 따른 공용기간 증대를 가져올 수 있는 것으로 나타났다. 향후, 추가적인 제품 개발(개선) 및 현장 적용성 평가를 통해서, 보강제품의 공용성을 더욱 증진시킬 수 있는 방안을 마련해 보고자 한다.