Pavement performance usually depends on the pavement’s material property, traffic and environmental conditions. Current pavement design programs such as the Mechanistic Empirical Pavement Design Guide use these factors in assessing the pavement life and performance in terms of different distresses like rutting and fatigue cracking. Theoretically, the cracking and rutting behaviour of pavements are based on accumulated strains experienced by the pavement which is brought by the weight and loading speed of vehicles. A steady state loading device was used in the field to evaluate pavement deflection’s behaviour in varying loading frequencies. It was observed that the pavement deflection increases as the loading frequency also increases until it approaches a certain frequency wherein the deflection decreases thereafter. In this study, a three-dimensional finite element pavement model was established using ABAQUS wherein the effect of the vehicle’s loading frequencies was analysed. The calculated static deflection and stress from the finite element (FE) model were found to have good correlation with the KENPAVE measured deflection and stress. The deflections of different pavement conditions were further studied and analysed by generating several pavement geometries and strength from the FE model using a frequency sweep response analysis. It was found that the geometric condition and the current modulus of the pavement can amplify the pavement deflection by a factor, β, depending on the loading frequency. The peak deflection was found to be occurring when the loading frequency approaches one of the pavement’s natural frequencies. Based on the finding from this study, the natural frequency is an important factor to be considered in designing pavements. Further study is recommended to understand more on how to minimize the effect of natural frequency to pavement life.

With interconnecting voids, porous asphalt provides drainage of rainwater in vertical and lateral direction during rainfall. In addtition, it also offers remarkable advantages compare to traditional asphalt: reduce vehicle splash and spray behind, reduce night time surface glare in wet season and increase tire-pavement friction...On the other hand, the following aspects are recognized as disavantages: reduced performance, winter maintenance issues and high construction cost. For flexible pavement, dynamic modulus master curve is an important parameter in the mechanistic-empirical pavement design guide. In this study, the results of experiment of dynamic modulus test of porous asphalt are discussed for understanding well about the viscoelastic characteristics of porous asphalt.

Membranes techniques used to convert chemical energy into electrical energy from energy sources such as hydrogen, salt water, and water. Membrane materials have transport property of desire molecular and barrier property for satisfy to requirement of cell performance. Typically, PFSA polymer is used to fabricate membrane. Each material has different characteristics depending on the membrane formation conditions. Macroscopic characteristics are difficult to correlation with molecular motion, mobility, and transport within membrane matrices. NMR spectroscopy can analysis about these characteristics by observing the molecule level. In this study, NMR spectroscopy can provide fundamental information of PFSA ionomers and correlation with macroscopic characteristics.

Membrane filtration has been considered as an promising harvesting technology in the fields of microalgal biorefinery to produce biofuels and valuable chemicals from microalgal biomass. For developing the effective membrane-based harvesting process to produce highly concentrated biomass, membrane fouling should be controlled because it leads to not only reduced filtration rate but also insufficient reachable concentration of harvested biomass for downstream process. For that, a dynamic filtration using a rotating disk was evaluated in this study, efficiently generating high shear flow near the membrane surface by an independently moving part. It was demonstrated to achieve feasible filtration performance even under high biomass concentration with complete biomass recovery and moderate energy consumption observed.

Optimization was performed on the static dynamic behavior of a simply supported laminated composite plate. Thickness optimization was performed with respect to Gr/E laminated composites with simultaneous mechanical load, thermal load and hygro-load. Displacement, fundamental frequency and composite damping were imposed as constraints for optimization. The results of the optimization were much better than those of the conventional methods.

We carried out a dynamic instability assessment of carbon nanotube reinforced composite (CNTRC) and carbon nanotubes/fiber/polymer composite (CNTFPC) skew plates based on the high-order shear deformation plate theory (HSDT). The multiscale interactions between carbon nanotube (CNT) ratios and skew angles on the dynamic instability for various length-thickness ratios are studied using a two-dimensional finite element model developed for this study. The results were verified by those reported in the literature show the interactions between the CNT reinforcement and skew angles in the skew laminate. Numerical examples show the importance of CNT reinforcement when assessing the dynamic instability of CNTRC and CNTFPC skew plates.

목적: 동체시력의 특성을 파악하기 위해 동체시력과 정지시력, 순간시력 및 안구움직임의 관계를 분석하였다. 방법: 20-30대 일반인 40명을 대상으로 동체시력, 고대비 및 저대비 정지시력, 순간시력, 주시 및 홱보기 안구움직임을 측정하였다. 동체시력은 상하좌우 방향으로 반전된 Snellen E 시표를 임의로 투사하여 측정하였으며, 시표의 방향을 식별할 수 있는 최고 각속도를 동체시력으로 지정하였다. 정지시력은 4 m 거리 에서 logMAR 시표를 이용하여 측정하였고, 시표의 대비에 따라 고대비(100%) 및 저대비(10%) 시력으로 나 누었다. 순간시력은 다섯 자리 숫자 시표를 이용하여 평가하였고, 시표 노출 시간은 14 ms와 7 ms이었다. 안구움직임은 고정형 안구추적장치를 이용하여 측정하였다. NYSOA King-Devick 검사의 하위 세 가지 시표를 읽는 동안 주시 및 홱보기 안구움직임을 추적하였다. 결과: 동체시력은 고대비 정지시력(r=-0.43, p=0.01), 저대비 정지시력(r=-0.40, p=0.01)과 통계적으 로 유의한 상관관계를 보였다. 순간시력은 동체시력과 상관관계가 없었고(r=-0.29, p=0.07), 시표 식별 시 개입되는 시기억능력(visual memory)의 영향을 축소시켰을 때에도 상관성이 없었다(r=-0.10, p=0.57). 동 체시력과 주시 및 홱보기 안구움직임은 상관관계를 보이지 않았다(fixation counts: r=0.07, p=0.65, fixation duration: r=0.27, p=0.10, saccade counts: r=0.02, p=0.93, saccade duration: r=0.01, p= 0.98, saccade amplitude: r=0.22. p=0.18, saccadic velocity: r=0.23, p=0.15). 다중회귀분석 결과, 동체시력에 영향을 미치는 요인은 고대비 정지시력으로 나타났다(β=-0.43, p=0.01). 결론: 동체시력은 고대비 및 저대비 정지시력에 따른 시각 능력 및 시각의 질과 관련이 있었다. 정지시력, 순간시력 및 안구움직임 중 동체시력에 영향을 미치는 성분은 고대비 정지시력이었으며, 순간시력이나 안구움직임이 동체시력에 미치는 영향은 추가적인 분석이 필요하다고 사료된다.

The purpose of this study is to determine the stiffness of rubber of dynamic damper. This damper system reduces the steering wheel vibration caused by idling oscillation of the engine. Therefore, in order to measure the stiffness of the silicone rubber in the dynamic damper system, the material test of the silicone rubber was carried out. Using the measured stiffness, the FEM model of the dynamic damper system was constructed and the correlation by the experimental data was shown at an error of less than 2%. In addition, the dynamic damper system was simplified to a two-degree-of-freedom spring-mass model and the effect of the stiffness change of the rubber on the natural frequency of the column shaft was analyzed theoretically. As a result, the amplitude of the column shaft was reduced as the stiffness of the silicone rubber was lowered.

이 연구는 운항자가 항해 중 위험을 느끼는 고정 및 이동 물표에 대한 해상교통위험성평가에 대한 것이다. 이를 위해 선박 길이와 속력, 선박조종성능이 고려된 동적선박영역을 기초로 한 충돌위험평가식을 구하였다. 특히, 동적선박영역과 충돌위험평가식을 하이브리드 결합하여 자선의 크기, 속력 등의 영향을 정량적으로 지표화한 항해위험성평가모델을 검토 및 개선하고자 한 것이다. 기존 항해위험성평가 모델에 적용이 부족한 속장비(speed length ratio) 즉, 선박의 길이와 속력에 대한 비가 고려된 새로운 형태의 해상교통위험성평가 모델을 제안하고자 한다. 그 결과 무차원 속력 즉, 속장비가 클수록 CJ 값이 크며, CJ 값은 속장비에 의해 잘 표현되고 있다. 또한, 속장비가 크면 속장비가 작은 경우보다, 보다 먼 거리에서부터 [주의], [경계], [위험] 또는 [매우위험]상태에 도달한다. 이 연구의 결과는 위험항로 회피 또는 최적항로 구축, 방파제폭이나 교량경간 등을 포함한 항로나 항만개발, 연안항해용 안전해도 개발 및 향후 자율운항선박과 같은 스마트선박의 운항 중 충돌방지와 최적항로 선정에 자료로 사용될 수 있을 것이다.

For the German energy transition, offshore wind energy is a significant factor of success. The number of installed offshore wind energy turbines is steadily increasing. Currently, the subject matter of offshore wind energy turbine maintenance and its optimization is increasingly in the focus of research and development work. The present contribution examines the logistics of offshore wind energy turbine maintenance and the impact of the actual sea state and of sea state forecasts. To this end, the coordination processes between the players involved in the planning of service operations will be presented and analysed. Based on this, the impact of the quality of wave height forecasts on operation decisions and the mean time to repair will be determined as well as the availability of the turbines at different forecast quality levels. Proceeding on the basis of these results, the concept of a decision-making support system for operative logistics planning will be presented.

구조물의 감쇠비는 내풍성능을 평가하는 가장 중요한 요소 중의 하나이다. 구조물의 실제 감쇠비는 대부분 계측된 응답을 기반으로 시스템 식별기술에 의하여 이루어진다. 그러나 예측된 감쇠비는 계측조건, 계측시간 및 시스템 식별기술에 따라 오차를 보이는 등 불확실성을 가지고 있다. 본 연구에서는 기 개발된 가상 동적진동기(Virtual Dynamic shaker)에 주요 개념으로 사용되었던 외부하중 스펙트럼의 전체 평탄성을 국부 평탄성으로 개념을 확대하여 감쇠비 추정을 보다 정교하게 하는 기법을 개발하였다. 국부 평탄성을 개념을 사용하여 감쇠비를 구하고자 하는 대상 모드의 고유진동수 부근에 적용함으로서 보다 정확하게 감쇠비 추정하는 기법을 다루었다. 본 개발된 기법을 검증하기 위하여 고층건물의 상시진동에 대하여 적용하였으며, 기존 시스템 식별법, 자유진동실험에 의한 결과와 비교 평가하였다. 그 결과 전체 평탄성을 가지는 개념에 비하여 국부평탄성을 가지는 VDS가 보다 정확하게 감쇠비를 추정하는 것을 보였다.

This paper proposes a dynamic magnetic field emulator (DMFE), which can electrically emulate information for the magnetic stripes of most widely used credit cards. Payment transactions with most common credit cards are performed by reading the card’s information, encoded in magnetic stripes, using the reader head of a point-of-sale (POS) system. A stripe-type permanent magnet is attached to the back side of the credit card, and information for payments or value-added service is reorganized by exposing it to strong magnetic field. The process of data recording and retrieving as stated above has been pointed out as a major cause of illegal credit card use, because the information on the magnetic stripe is always exposed, and is thus vulnerable to forgery or alteration. A dynamic magnetic field emulator displays card information only when necessary by using the principle of solenoidal magnets. The DMFE proposed in this paper can prevent fraudulent use if it is operated with a device, like a smart phone, or a separate user-authentication procedure. In addition, because it is possible to display various information as needed, it can be utilized for a smart multi-card application, in which information for multiple cards is stored in one card, and can be selected and used as needed. This paper introduces the necessity of the DMFE and its manufacturing principles. As a result, this study will be helpful for making various application cases in payment, which is a core area of the Fintech (a newly-coined word of finance and technology) industry.

An Automatic feed mechanism is one of the most important systems that make up the air defence gun. The System which consists of consecutive mechanisms from a magazine to the breech of automatic machine gun(Dual) carries ammunitions through the feeding pass with a high speed by the electric boosters to synchronize with gun firing speed. In order to feed the rounds smoothly without jamming, it is necessary to optimize the design of the driving torque needed to carry them and to get a proper distribution of power between rounds after performing mathematical calculation. In this study, in order to predict and prevent malfunctions of feeding and unloading ammunition, we have developed an optimal computational model using CATIA and multi-body dynamics software, ADAMS.

We developed a regenerable antifouling membrane using photo-dynamic reversible cross-linking. We modified a branched polymer with photo-responsive group, and coated it to a membrane by dip-coating method. The combined results of Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy measurements clearly revealed that the modified polymer were successfully synthesized ,and coated to the membrane by photo-dynamic reversible cross-linking. As expected, the modified film could be detached by UV irradiation. In addition, the photo-reversible membrane surface was recovered decreased water flux by photo-induced regeneration process.

Polymer electrolyte membrane (PEM) is one of key elements to determine both electrochemical performances and lifetimes of fuel cell electric vehicles (FCEVs). PEM is exposed to a variety of dynamic stimuli (e.g., temperature, humidity, pressure, fuel gases and so on) under their operation conditions and meets unavoidable mechanical damages derived from unequal pressure difference between anode and cathode feed gases. Even though there have been approaches to evaluate the mechanical strength of PEM materials, most of the trials could provide static information on their mechanical strength. In this study, a pressure-loaded blister hybrid system connected with gas chromatography was developed to disclose the efficacy of the system as an evaluation tool of dynamic PEM strength under realistic FCEV operation conditions.

PURPOSES: This study aims to evaluate the effects of vehicle dynamic behaviors on ride quality. METHODS: Simulation and field test were conducted to analyze the behavior of a driving vehicle. The simulation program CarSIM was applied and an INS (Inertial Navigation System) was used for field experiments. A small simulator was developed to simulate vehicle behavior such as roll, pitch, and bounce. The panels evaluated the ride quality in five stages from “very satisfied”to “very dissatisfied.”Experiments were conducted on a total of 144 cases of vehicle behavior combinations. RESULTS: In both simulation and field tests, pitch is the largest and yaw the smallest. Especially in the field test, the amount of yaw is very low, about 7% of pitch and 18% of roll. The sensitive and extensive analysis conducted related ride quality with changing the frequency and amplitude. It was found that the most sensitive frequency range is 8 Hz across all amplitudes. Moreover, the combination of the roll and bounce was most sensitive to the ride quality at the low-frequency range. CONCLUSIONS: This result show that the vertical vehicle behavior (bounce) as well as the rotational behavior (roll and pitch) are highly correlated with ride quality. Therefore, it is expected that a more reasonable roughness index can be developed through a combination of vertical and rotational vehicle behavior.