Early warnings have been developed to provide rapid earthquake information, allowing people to prepare as much time as possible. However, since it takes several seconds for an earthquake warning to be issued, the blind zone is inevitable. To reduce the blind zone, information from a single observatory is used to operate an on-site earthquake warning. However, false and missed alarms are still high, requiring continued research and validation. This study predicted Peak Ground Acceleration (PGA) using the characteristic data to reduce false and missed alarms in on-site earthquake warnings. A machine learning prediction model was created using the initial P-wave parameters developed from the characteristic data to achieve this. Then, the model was used to predict the maximum ground acceleration in the southeastern region of the Korean Peninsula. The expected results for six target earthquakes were confirmed to have a standard deviation within 0.3 compared to the observed PGA and the values within ±2 sigma. This method is expected to help develop an on-site early warning system for earthquakes.

Recently, there has been growing anxiety about automotive due to accidents suspected to be caused by sudden unintended acceleration. A study was conducted on the effect of automotive defects on Sudden Unintended Acceleration. Experimental results were derived and analyzed by simulating the situation of sudden unintended acceleration while driving a automotive. It was experimentally confirmed that the defect in the TPS sensor had no direct effect on the rapid increase in RPM. It has been confirmed that the vehicle brakes normally when the brakes are applied even if there is a TPS sensor defect. In the future, it is necessary to investigate the correlation between automotive defects and sudden unintended acceleration through various experiments.

Recently, the number of elderly driver accidents has been steadily increasing. EDR(Event Data Recorder) helps a lot in understanding traffic accidents. In particular, as anxiety about SUA(Sudden Unintended Acceleration) increases, EDR data is playing an important role in accident analysis. In this study, EDR data of an accident vehicle suspected of SUA was analyzed to identify traffic accident circumstances and detailed accidents. Experimental results were derived and analyzed by simulating the situation of SUA while driving a car. As a result, it was found that normal braking is performed when the brake pedal is operated even in dangerous situations such as mechanical defects and driver malfunctions. Rather than finding the cause of an accident after a traffic accident, countermeasures are needed to prevent mechanical defects and driving malfunctions before a traffic accident.

We examine whether the radial acceleration relation (RAR) of dwarf galaxies can be explained by Verlinde’s emergent gravity. This is the extension of Yoon et al. (2023), which examine the RAR of typical spiral galaxies, to less massive systems. To do this, we compile the line-of-sight velocity dispersion profiles of 30 dwarf galaxies in the Local Group from the literature. We then calculate the expected gravitational acceleration from the stellar component in the framework of the emergent gravity, and compare it with that from observations. The calculated acceleration with the emergent gravity under the assumption of a quasi-de Sitter universe agrees with the observed one within the uncertainty. Our results suggest that the emergent gravity can explain the kinematics of galaxies without introducing dark matter, even for less massive galaxies where dark matter is expected to dominate. This sharply contrasts with MOND, where a new interpolating function has to be introduced for dwarf galaxies to explain their kinematics without dark matter.

During the formation of large-scale structures in the universe, weak internal shocks are induced within the hot intracluster medium (ICM), while strong accretion shocks arise in the warm-hot intergalactic medium (WHIM) within filaments, and the warm-cold gas in voids surrounding galaxy clusters. These cosmological shocks are thought to accelerate cosmic ray (CR) protons and electrons via diffusive shock acceleration (DSA). Recent advances in particle-in-cell and hybrid simulations have provided deeper insights into the kinetic plasma processes that govern microinstabilities and particle acceleration in collisionless shocks in weakly magnetized astrophysical plasma. In this study, we adopt a thermal-leakage type injection model and DSA power-law distribution functions in the test-particle regime. The CR proton spectrum directly connects to the Maxwellian distribution of protons at the injection momentum pinj = Qppth,p. On the other hand, the CR electron spectrum extends down to pmin = Qepth,e and is linked to the Maxwellian distribution of electrons. Here, pth,p and pth,e, are the proton and electron thermal momenta, respectively. Moreover, we propose that the postshock gas temperature and the injection parameters, Qp and Qe are self-regulated to maintain the test-particle condition, as the thermal energy is gradually transferred to the CR energy. Under these constraints, we estimate the self-regulated values of the temperature reduction factor, RT , and the proton injection parameter, Qp, along with the resulting CR efficiencies, ηp and ηe. We then provide analytical fitting functions for these parameters as functions of the shock Mach number, Ms. These fitting formulas may serve as valuable tools for quantitatively assessing the impact of CR protons and electrons, as well as the resulting nonthermal emissions in galaxy clusters and cosmic filaments.

It is very important to measure and analyze various driving performance in the vehicle development stage. Particularly in racing vehicles, analysis of driving characteristics on various courses is very important, and data measurement and analysis technology using actual measurement equipment are widely used in racing strategies. In this paper, we present an analytical approach using vehicle acceleration, which is relatively easy to measure among various factors. Measured acceleration data is used to analyze optimal driving performance.

Structures of high-rise buildings are less prone to earthquake damage. This is because the response acceleration of high-rise buildings appears to be small by generally occurring short-period ground motions. However, due to the increased construction volume of high-rise buildings and concerns about large earthquakes, long-period ground motions have begun to be recognized as a risk factor for high-rise buildings. Ground motion observed on each floor of the building is affected by the eigenmode of the building because the ground motion input to the building is amplified in the frequency range corresponding to the building's natural frequency. In addition, long-period components of ground motion are more easily transmitted to the floor or attached components of the building than short-period components. As such, high-rise buildings and non-structural components pose concerns about long-period ground motion. However, the criteria (ASCE 7-22) underestimate the acceleration response of buildings and non-structural components caused by long-period ground motion. Therefore, the characteristics of buildings’ acceleration response amplification ratio and non-structural components were reviewed in this study through shake table tests considering long-period ground motions.

병렬영상기법인 SENSE 기법은 슬관절 자기공명영상의 검사 시간을 획기적으로 단축할 수 있다. 그러나 기법 적용 시 SENSE factor를 증가시키면 영상에 인공물의 발생이 증가하는 문제점이 있어 개선을 위해 본 연구에서는 최소의 시간이 소요되면서 인공물이 발생하지 않는 최적의 SENSE factor를 제시하고자 하였다. 연구 방법은 SENSE factor 1.0을 기준 으로 0.5 간격씩 5.0까지 변화시켜 팬텀 실험과 임상실험을 시행하였다. 3.0T 초전도 자기공명영상장치와 dS Knee 코일 을 사용하여 T1, T2 강조영상을 획득하였으며, 영상의 비교평가는 임상 경력 10년 이상의 방사선사 10명이 5점 척도로 평가한 후, 일원배치 분산분석과 사후분석을 통해 유의한 차이가 있는지 판단하였다. 연구 결과 팬텀 실험은 T1, T2 강조 영상 모두 SENSE factor를 1.5 이하로 하였을 때 기준 영상과 차이가 없었으며, 임상실험은 SENSE factor를 2.0 이하로 하였을 때 기준 영상과 차이가 없었다. 결론적으로 슬관절 자기공명영상 시 검사 시간을 단축하면서 인공물이 발생하지 않는 최적의 SENSE factor는 팬텀 실험의 경우 1.5, 임상실험의 경우 2.0이 적정하리라 사료된다.

본 논문은 범용성 기기를 기반으로한 가속도계로 라즈베리파이 4B 기반 MEMS형 가속도계 ADXL345와 iPhone 12 pro 내 장형 가속도계를 사용하여 다자유도 축소 모형 구조물의 응답을 계측하고 그 결과를 IEPE타입 가속도계와 비교하여 계측 유효성을 확 인하고자 하였다. 1~3층 모형 구조물 최상층에 충격해머로 가진하였으며 각 층의 가속도를 측정하였다. 시간영역에서 모든 가속도계 의 계측값이 대체적으로 유사한 결과를 나타냈으며 진동수영역에서 모드진동수 또한 유사하게 나타났다. 감쇠비와 모드형상 추정에 있어서 라즈베리파이 기반 ADXL345보다 iPhone 12 pro가 더 정확한 결과를 보였으나 대체적으로 유사하게 나타났다. 실험 결과를 바 탕으로 라즈베리파이 기반 ADXL345와 iPhone 12 pro 가속도계의 구조물 식별 유효성을 확인하였다.

In 2000s, three-dimensional shapes of gluon particles in a proton were discovered. It has been demonstrated that asymmetrical gravitational forces exist between these particles. The asymmetric gravitational force between gluon particles in a proton causes that proton to accelerate on its own and this is the basis of the gas mo;ecular motions. In this work, a simplified acceleration model which simulated the asymmetric gravitational force in a proton was proposed. Here we report the comparative study between density distribution of gravitational forces obtained from the proposed model and Max well-Boltzmann velocity distribution that are in good agreement with expressing the behavior of gas molecules respectively.

최근 비구조요소의 피해사례가 증가하면서 비구조요소 내진설계에 관한 많은 연구가 진행되고 있다. 하지만 대부분의 연구는 평면 적 요소보다는 수직적 요소나 시스템적 요소를 변수로 층가속도를 평가하고 있다. 때문에 본 논문에서는 횡력저항에 많은 부분을 차 지하는 코어를 평면적 변수로 사용하여 비구조요소 내진설계를 위한 층가속도에 대해 평가하였다. 정사각형의 2축대칭의 평면에서 코어의 형태(위치 및 비중)변화에 따라 서로 다른 5개의 평면과 각 평면마다 5층, 10층, 15층, 20층의 층수를 가진 총 20개의 모델로 선 형시간이력해석을 수행하였다. 분석 결과 코어 위치에 따라 편심을 받는 평면에서는 층가속도가 최대 1.7배의 비틀림 증폭이 발생하 였고 구조물의 중층부에서 비틀림의 영향이 가장 큰 것을 확인할 수 있었다. 편심이 없이 코어의 비중만 변화한 평면에서는 주기 0.4694초를 기준으로 이하일 때는 주기가 증가할수록 층가속도가 저층부에서는 감소하고 고층부에는 증가하며, 반대로 주기 0.4694 초 이상일 때는 주기가 증가할수록 층가속도가 저층부에서는 증가하고 고층부에는 감소한다는 것을 확인할 수 있었다. 또한, 구조물 의 층수는 최대층가속도에 영향을 주지 못하는 것을 확인하였다. 핵심용어 :

PURPOSES : In a previous study, an error was detected in data pertaining to the direction and velocity of a roller. Hence, in this study, the correlation between these two variables and acceleration data is analyzed. Relevant algorithms are developed by adding variables to existing algorithms. METHODS : A tachometer and GPS are used to acquire the velocity, compaction direction of rollers, and number of compactions. Subsequently, data input to an accelerometer are compared and analyzed. RESULTS : Based on FFT analysis, it is discovered that the data are inaccurate when a forward reverse is performed. Using the GPS, the velocity of the roller is differentiated based on the number of pledges, and then added as a variable to the algorithm. Subsequently, it is evaluated and analyzed only with data during forward movement based on changes in the latitude and longitude. CONCLUSIONS : It is discovered that the acceleration data values from both the left and right rollers differ owing to their weight difference, as indicated by the asphalt gradient. Data changes based on asphalt gradients are analyzed using gyro sensors. If the correlation between the two sets of data is high, then the algorithm is advanced by introducing a cross spectrum after calibrating the acceleration value based on the gradient.

이 논문에서는 박스형 전력구의 지진응답해석에 사용되는 응답진도법의 보수성을 평가하였다. 이를 위해 25가지 전력구 단면과 각 전력구에 대한 2개의 지반조건을 고려한 총 50개 예제를 선정하였다. 응답진도법의 보수성을 평가하기 위해 동적 지반-구조물 상호 작용을 고려한 정밀해석법에 의한 응답과 비교하였다. 비교결과, 정밀해석 응답에 대한 응답진도법에 의한 응답의 비로 정의한 응답 비의 평균이 1.0에 근접하며, 응답비의 표준편차도 5% 이내로 매우 작아서, 응답진도법에 의한 해석이 정밀해석법과 일관됨을 알 수 있었다. 마지막으로 응답진도법에 의한 응답에 하중계수 1.1을 적용하면 전력구의 보수적인 내진설계가 가능할 것으로 나타났다.