• Steel and Composite Structures
• /
• 제50권1호
• /
• pp.89-105
• /
• 2024

Multichannel analysis of surface waves (MASW) method has exhibited broad application prospects in the nondestructive detection of interfacial debonding in steel-concrete composite structures (SCCS). However, due to the structural diversity of SCCS and the high stealthiness of interfacial debonding defects, the feasibility of MASW method needs to be investigated in depth. In this study, synthetic parametric study on MASW nondestructive debonding detection for SCCSs is performed. The aim is to quantitatively analyze influential factors with respect to structural composition of SCCS and MASW measurement mode. First, stress wave composition and propagation process in SCCS are studied utilizing 2D numerical simulation. For structural composition in SCCS, the thickness variation of steel plate, concrete core, and debonding defects are discussed. To determine the most appropriate sensor arrangement for MASW measurement, the effects of spacing and number of observation points, along with distances between excitation points, nearest boundary, as well as the first observation point, are analyzed individually. The influence of signal type and frequency of transient excitation on dispersion figures from forwarding analysis is studied to determine the most suitable excitation signal. The findings from this study can provide important theoretical guidance for MASW-based interfacial debonding detection for SCCS. Furthermore, they can be instrumental in optimizing both the sensor layout design and signal choice for experimental validation.

• Journal of Astronomy and Space Sciences
• /
• 제37권3호
• /
• pp.171-185
• /
• 2020

This paper presents a methodology for Initial Orbit Determination (IOD) based on a modification of the Laplace's geocentric method. The orbital elements for Near-Earth asteroids (1864) Daedalus, 2003 GW, 2019 JA8, a Hungaria-type asteroid (4690) Strasbourg, and the asteroids of the Main Belt (1738) Oosterhoff, (2717) Tellervo, (1568) Aisleen and (2235) Vittore were calculated. Input data observations from the Minor Planet Center MPC database and Astronomical Observatory of the Technological University of Pereira (OAUTP; MPC code W63) were used. These observations cover observation arcs of less than 22 days. The orbital errors, in terms of shape and orientation for the estimated orbits of the asteroids, were calculated. The shape error was less than 53 × 10^-3 AU, except for the asteroid 2019 JA8. On the other hand, errors in orientation were less than 0.1 rad, except for (4690) Strasbourg. Additionally, we estimated ephemerides for all bodies for up to two months. When compared with actual ephemerides, the errors found allowed us to conclude that these bodies can be recovered in a field of vision of 95' × 72' (OAUTP field). This shows that Laplace's method, though simple, may still be useful in the IOD study, especially for observatories that initiate programs of minor bodies observation.

• 대기
• /
• 제27권3호
• /
• pp.359-370
• /
• 2017

In this study, the oceanic Total Precipitable Water (TPW) retrieval algorithm at 16 km altitude of High Altitude Long Endurance Unmanned Aerial Vehicle (HALE UAV) is described. Empirical equation based on Wentz method (1995) that uses the 18.7 and 22.235 GHz channels is developed using the simulated brightness temperature and SeeBor training dataset. To do radiative simulation, Satellite Data Simulator Unit (SDSU) Radiative Transfer Model (RTM) is used. The data of 60% (523) and 40% (349) in the SeeBor training dataset are used to develop and validate the TPW retrieval algorithm, respectively. The range of coefficients for the TPW retrieval at the altitude of 3~18 km with 3 km interval were 153.69~199.87 (${\alpha}$), 54.330~58.468 (${\beta}$), and 84.519~93.484 (${\gamma}$). The bias and RMSE at each altitude were found to be about $-0.81kg\;m^{-2}$ and $2.17kg\;m^{-2}$, respectively. Correlation coefficients were more than 0.9. Radiosonde observation has been generally operated over land. To validate the accuracy of the oceanic TPW retrieval algorithm, observation data from the Korea Meteorological Administration (KMA) Gisang 1 research vessel about six clear sky cases representing spring, autumn, and summer season is used. Difference between retrieved and observed TPW at 16 km altitude were in the range of $0.53{\sim}1.87kg\;m^{-2}$, which is reasonable for most applications. Difference in TPW between retrieval and observation at each altitude (3~15 km) is also presented. Differences of TPW at altitudes more than 6 km were $0.3{\sim}1.9kg\;m^{-2}$. Retrieved TPW at 3 km altitude was smaller than upper level with a difference of $-0.25{\sim}0.75kg\;m^{-2}$ compared to the observed TPW.

• 대한원격탐사학회지
• /
• 제28권4호
• /
• pp.435-448
• /
• 2012

증발산은 토양 표면에서 일어나는 증발 과정과 식물의 광합성 작용으로 인해 일어나는 증산 작용을 포함하는 수문기상인자로 외부 환경에 민감하게 작용한다. 현재 국내외에서는 이를 정확하게 관측하여 활용하기 위해 증발접시(evaporation pan), 침루계(lysimeter) 등을 이용하여 실측하거나 Eddy covariance technique, Bowen ratio method 등을 이용하여 경험적으로 산정하고 있으나 공간적인 제약이 따른다. 따라서 본 연구에서는 Terra 인공위성에 탑재된 Moderate Resolution Imaging Spectroradiometer (MODIS) 다중분광 센서를 이용, 원격탐사 기술을 적용함으로써 이러한 지상 관측의 단점을 보완하고자 하였다. 이전 연구들에서 소개가 되었던 원격탐사 기반 증발산 산정 모형을 개선하여 별도의 외부 입력자료 없이 MODIS 위성 이미지 자료만을 이용, 우리나라의 지역적 특성을 반영한 Penman-Monteith 기반 증발산을 산정하였다. 유량조사사업단에서 운영 및 관리하고 있는 설마천/청미천 플럭스 타워의 증발산 관측치와 MODIS 기반 증발산 산정값과의 비교를 통해 각각 0.69, 0.74의 높은 상관계수를 보여 산정 방법의 적용성을 검증하였다.

• 융합정보논문지
• /
• 제12권5호
• /
• pp.40-50
• /
• 2022

본 연구는 간호대학생이 시뮬레이션 실습 시 동료 팀의 만성폐쇄성폐질환 환자 시나리오 구현 동영상을 실시간으로 관찰하면서 구조화된 동영상 관찰 기록지에 기록한 간호술 영역의 내용을 분석한 질적 연구이다. 4개의 세부영역으로 구분하여 기록된 내용을 효과적, 비효과적 측면으로 구분한 후 내용분석 방법을 사용하여 분석하였다. 연구결과 절차의 정확성에 있어서 효과적 측면은 필요한 물품준비와 증상완화를 위한 중재, 비효과적인 측면은 원칙 미준수, 부적절한 처방 이행, 이론과 수행의 연계 미흡으로 나타났다. 무균술 준수에 있어 효과적 측면은 내과적 무균술 적용과 외과적 무균술 적용, 비효과적 측면은 내과적 무균술 미수행과 외과적 무균술 미수행이었다. 안전과 안위 고려에 있어 효과적 측면은 심리적 안위 고려과 물리적 안전 고려, 비효과적 측면은 안위에 대한 실재감 부족과 환자안전 인식 미흡으로 나타났다. 설명 및 교육의 효과적 측면은 목적 설명과 방법 교육, 비효과적 측면은 설명 부족과 환자수준 미고려이었다. 본 연구에서 간호대학생은 관찰을 통하여 얻은 시각적 정보를 기록하는 과정을 통해 학습에 집중하고 기억을 강화시킬 수 있었을 것으로 사료된다. 또한 본 연구는 시뮬레이션 기반 실습을 통한 간호술 교육의 효율성을 높일 수 있는 요소들을 제시하였다는 점에서 의의가 있다.

• 대한지구과학교육학회지
• /
• 제3권3호
• /
• pp.184-190
• /
• 2010

This study is to verify the effects of classes at a finishing stage using cartoons depicting certain science textbook units on scientific attitudes and academic achievements of students, compared to those of classes using experiment and observation oriented textbooks. Participants of this study were 56 fifth graders at B Elementary School in Busan, and cartoon textbooks were developed based on 'Unit 1. Mirror & Lens' and 'Unit 3. Temperature & Wind' from a science textbook for the 1st semester, the year 5 to conduct cartoon led lessons just before ending a class till the 10th lesson, for the period of 4 weeks. The result of this study can be summarized as follows: Firstly, scientific attitudes improved better from the cartoon based lesson of a final stage than from the experiment and observation method, and especially more effective in lower groups among all other academic achievement levels as well as in male students. Secondly, academic achievements scored higher when cartoons were used in lessons than when the experiment and observation type was used, with higher groups of academic achievement levels working better, despite no significant gap existing between two genders. Thirdly, the memory transfer and sustenance of lessons were more effective in finishing class stage with cartoon studies than with experiment and observation one, and among all levels and both sexes, higher academic groups and male pupils exceeded. Fourthly, when questioned about their opinions on a cartoon led lesson for a final stage, 65% of those participants responded positively, while higher groups preferred more than lower groups. responded positively, while higher groups preferred more than lower groups.

• 대기
• /
• 제23권2호
• /
• pp.171-186
• /
• 2013

Recently, the number of observations used in a data assimilation system is increasing due to the enormous amount of observations, including satellite data. However, it is not clear that all of these observations are always beneficial to the performance of the numerical weather prediction (NWP). Therefore, it is important to evaluate the effect of observations on these forecasts so that the observations can be used more usefully in NWP process. In this study, the adjoint-based Forecast Sensitivity to Observation (FSO) method with the KMA Unified Model (UM) is applied to two high-impact weather events which occurred in summer and winter in Korea in an effort to investigate the effects of observations on the forecasts of these events. The total dry energy norm is used as a response function to calculate the adjoint sensitivity. For the summer case, TEMP observations have the greatest total impact while BOGUS shows the greatest impact per observation for all of the 24-, 36-, and 48-hour forecasts. For the winter case, aircraft, ATOVS, and ESA have the greatest total impact for the 24-, 36-, and 48-hour forecasts respectively, while ESA has the greatest impact per observation. Most of the observation effects are horizontally located upwind or in the vicinity of the Korean peninsula. The fraction of beneficial observations is less than 50%, which is less than the results in previous studies. As an additional experiment, the total moist energy norm is used as a response function to measure the sensitivity of 24-hour forecast error to observations. The characteristics of the observation impact with the moist energy response function are generally similar to those with the dry energy response function. However, the ATOVS observations were found to be sensitive to the response function, showing a positive (a negative) effect on the forecast when using the dry (moist) norm for the summer case. For the winter case, the dry and moist energy norm experiments show very similar results because the adjoint of KMA UM does not calculate the specific humidity of ice properly such that the dry and moist energy norms are very similar except for the humidity in air that is very low in winter.

• The Journal of the Acoustical Society of Korea
• /
• 제16권3E호
• /
• pp.19-23
• /
• 1997

The goal of postprocessing in automatic speech recognition is to improve recognition performance by utterance verification at the output of recognition stage. It is focused on the effective rejection of out-of vocabulary words based on the confidence score of hypothesized candidate word. We present two methods for computing confidence scores. Both methods are based on the distance between each observation vector and the representative code vector, which is defined by the most likely code vector at each state. While the first method employs simple time normalization, the second one uses a normalization technique based on the concept of on-line garbage mode[1]. According to the speaker independent isolated words recognition experiment with discrete density HMM, the second method outperforms both the first one and conventional likelihood ratio scoring method[2].

• 대한음성학회지:말소리
• /
• 제47호
• /
• pp.131-140
• /
• 2003

We propose a new method of generating client models for HMM based text-dependent speaker verification system with only a small amount of training data. To make a client model, statistical methods such as segmental K-means algorithm are widely used, but they do not guarantee the quality or reliability of a model when only limited data are avaliable. In this paper, we propose a blind speech segmentation based on level building DTW algorithm as an alternative method to make a client model with limited data. In addition, considering the fact that voiced sounds have much more speaker-specific information than unvoiced sounds and energy of the former is higher than that of the latter, we also propose a new score evaluation method using the observation probability raised to the power of weighting factor estimated from the normalized log energy. Our experiment shows that the proposed methods are superior to conventional HMM based speaker verification system.

• 로봇학회논문지
• /
• 제10권2호
• /
• pp.112-118
• /
• 2015

This paper proposes a pose-graph based SLAM method using an upward-looking camera and artificial landmarks for AGVs in factory environments. The proposed method provides a way to acquire the camera extrinsic matrix and improves the accuracy of feature observation using a low-cost camera. SLAM is conducted by optimizing AGV's explored path using the artificial landmarks installed on the ceiling at various locations. As the AGV explores, the pose nodes are added based on the certain distance from odometry and the landmark nodes are registered when AGV recognizes the fiducial marks. As a result of the proposed scheme, a graph network is created and optimized through a G2O optimization tool so that the accumulated error due to the slip is minimized. The experiment shows that the proposed method is robust for SLAM in real factory environments.