• Smart Structures and Systems
• /
• v.33 no.2
• /
• pp.165-175
• /
• 2024

Rotating beams play a crucial role in representing complex mechanical components that are prevalent in vital sectors like energy and transportation industries. These components are susceptible to the initiation and propagation of cracks, posing a substantial risk to their structural integrity. This study presents a two-stage methodology for detecting the location and estimating the size of an open-edge transverse crack in a rotating Euler-Bernoulli beam with a uniform cross-section. Understanding the dynamic behavior of beams is vital for the effective design and evaluation of their operational performance. In this regard, modal parameters such as natural frequencies and eigenmodes are frequently employed to detect and identify damages in mechanical components. In this instance, the Frobenius method has been employed to determine the first two natural frequencies and corresponding eigenmodes associated with flapwise bending vibration. These calculations have been performed by solving the governing differential equation that describes the motion of the beam. Various parameters have been considered, such as rotational speed, beam slenderness, hub radius, and crack size and location. The effect of the crack has been replaced by a rotational spring whose stiffness represents the increase in local flexibility as a result of the damage presence. In the initial phase of the proposed methodology, a damage index utilizing the slope of the beam's eigenmode has been employed to estimate the location of the crack. After detecting the presence of damage, the size of the crack is determined using a Genetic Algorithm optimization technique. The ultimate goal of the proposed methodology is to enable the development of more suitable and reliable maintenance plans.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.5
• /
• pp.7-18
• /
• 2005

Over the past twenty years, the maintenance system has been developed and its importance has been increased. For the effective maintenance of the urban transit, we have developed the maintenance system based on the concept of RCM(Reliability Centered Maintenance). RCM analysis is a systematic approach to developing a cost-effective maintenance strategy based on the various components's reliability of the system in question. It is performed according to process that includes the following steps; definition of function and functional failures of the systems, construction of RB D(Reliability Block Diagram), performance of FMEA(Failure Modes & Effects Analysis) and calculation of the reliability index. The final process of RCM is to determine appropriate failure maintenance strategies. This paper aims to define the procedure of maintenace based on the concept of RCM for urban transit. The key for a successful maintenance system is an automated scheduling to the maximum extent possible and timely executions. The developed system issues maintenance plan and repair request based on analyzed data and maintenance experience.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.35 no.10
• /
• pp.225-234
• /
• 2019

The purpose of this paper is to analyze the additional construction cost of G-SEED certification for domestic office building reflecting the latest standard(G-SEED 2016-2), and to derive cost impact by category and level. Therefore, it is intended to provide quantitave cost data according to G-SEED certification at the planning phase of the project, estimate the additional construction cost per level according to G-SEED Certification of similar project to be carried out in the future, and encourage G-SEED certification by supporting the decision of the owners. Method: The Process and method of this study are summarized in five steps, 1) Review of previous research, 2) Selection of target project, 3) Scenario setting by level, 4) Additional construction cost for each evaluation category, 5) Extraction of additional construction cost ratio by level. Result: This paper analyzed the cost impact by deriving the additional construction cost of detailed category for level improvement according to the revised G-SEED certification(G-SEED 2016-2). In conclusion, an additional construction cost(ratio) of G-SEED projects to the reference building is drawn as good level; 157,426,241 KWN(+0.43%), very good level; 321,907,802 KWN(+0.88%), excellent level; 999,371,478 KWN(+2.74%), and outstanding level; 1,467,047,718 KWN(+4.02%).

• Asian-Australasian Journal of Animal Sciences
• /
• v.21 no.9
• /
• pp.1355-1360
• /
• 2008

Effects of dietary ${\delta}$-aminolevulinic acid (ALA) supplementation on serum iron status, blood characteristics, egg production and quality were examined in laying hens in an 8-week feeding trail. Two hundred and forty (Hy-line brown, 40-week-old) layers were randomly assigned to four dietary treatments with ten replications (six layers in adjacent three cages). Dietary treatments included: 1) CON (basal diet), 2) ALA1 (CON+ALA 5 ppm), 3) ALA2 (CON+ALA 10 ppm) and 4) ALA3 (CON+ALA 15 ppm). All nutrient levels of diets were formulated to meet or exceed NRC (1994) recommendations for laying hens. During the entire experimental period, differences of serum iron concentration and total iron binding capacity (TIBC) were significantly increased in ALA1 supplemented treatment (quadratic effect, p<0.05). The difference of total protein between 8 and 0 weeks was significantly higher in ALA2 treatment than CON treatment (quadratic effect, p<0.05). No significant effects were observed on hemoglobin, WBC, RBC, lymphocyte and albumin concentrations. Egg production and egg weight were not influenced by the ALA supplementation. Egg yolk index was also significantly higher in ALA3 treatment than CON treatment at the end of 4 and 8 weeks (linear effect, p<0.05). Haugh unit was increased in ALA3 treatment compared to CON and ALA1 treatments at the end of 8 weeks (linear effect, p<0.05). However, egg shell thickness, breaking strength and yolk color unit were not affected by the ALA supplementation. In conclusion, dietary ALA supplementation at a level of 5 ppm can affect iron concentration in serum while higher levels (10 or 15 ppm) have some beneficial influences on blood profiles and egg quality.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.34 no.4
• /
• pp.413-423
• /
• 2016

Worldview-3 satellite sensor provides panchromatic image with high-spatial resolution and 8-band multispectral images. Therefore, an image-sharpening technique, which sharpens the spatial resolution of multispectral images by using high-spatial resolution panchromatic images, is essential for various applications of Worldview-3 images based on image interpretation and processing. The existing pansharpening algorithms tend to tradeoff between spectral distortion and spatial enhancement. In this study, we applied six pansharpening algorithms to Worldview-3 satellite imagery and assessed the quality of pansharpened images qualitatively and quantitatively. We also analyzed the effects of time lag for each multispectral band during the pansharpening process. Quantitative assessment of pansharpened images was performed by comparing ERGAS (Erreur Relative Globale Adimensionnelle de Synthèse), SAM (Spectral Angle Mapper), Q-index and sCC (spatial Correlation Coefficient) based on real data set. In experiment, quantitative results obtained by MRA (Multi-Resolution Analysis)-based algorithm were better than those by the CS (Component Substitution)-based algorithm. Nevertheless, qualitative quality of spectral information was similar to each other. In addition, images obtained by the CS-based algorithm and by division of two multispectral sensors were shaper in terms of spatial quality than those obtained by the other pansharpening algorithm. Therefore, there is a need to determine a pansharpening method for Worldview-3 images for application to remote sensing data, such as spectral and spatial information-based applications.

• Journal of the Society of Disaster Information
• /
• v.19 no.3
• /
• pp.689-697
• /
• 2023

Purpose: The purpose of this study is to automatically extract information on underground facilities using a general-purpose smartphone in the process of applying the mini-trenching method. Method: Data sets for image learning were collected under various conditions such as day and night, height, and angle, and the object detection algorithm used the R-CNN algorithm. Result: As a result of the study, F1-Score was applied as a performance evaluation index that can consider the average of accurate predictions and reproduction rates at the same time, and F1-Score was 0.76. Conclusion: The results of this study showed that it was possible to extract information on underground buried materials based on smartphones, but it is necessary to improve the precision and accuracy of the algorithm through additional securing of learning data and on-site demonstration.

• Journal of Korean Society for Atmospheric Environment
• /
• v.29 no.2
• /
• pp.186-198
• /
• 2013

The present work is an attempt to improve the performance of a regional air quality model by means of liking it with a global chemistry transport model. The global chemical transport model of GEOS-Chem is used to provide BC (Boundary Condition)s which reflect temporal and spatial variations at boundaries of regional chemical transport model of CMAQ over East Asia. First, GEOS-Chem outputs are evaluated by comparing predicted concentrations with observed monthly data of gas phase species and secondary inorganic aerosols from EANET (Acid Deposition Monitoring Network in East Asia) sites. The results show that predicted PM10 concentrations are in good agreement with the observations. This implies that GEOS-Chem outputs could be used to provide BCs to CMAQ. Simulated daily and monthly mean PM10 concentrations of CMAQ with the linkage of GEOS-Chem's BCs and constant BCs are then evaluated by comparing predicted concentrations with observations at API (Air Pollution Index) sites in China as well as EANET sites in Korea. CMAQ with the GEOS-Chem outputs improves model simulation in depicting observed PM10 concentrations comparing with those with constant BCs. It is also found that influence of aerosol species are largely dependent on the BCs over East Asia and Korea. Mean biases between simulated versus observed daily and monthly mean concentrations of PM10 with the GEOS-chem were improved by 1~8 ${\mu}g/m^3$ in China region, 3.26 ${\mu}g/m^3$ in Korea.

• Journal of Navigation and Port Research
• /
• v.33 no.10
• /
• pp.735-742
• /
• 2009

Information security is an essential factor that enables terminal to be operated. However, despite of this importance of information security, there has hardly been any research related to this topic. And moreover, current level of information security performance in container terminals has not been analyzed so far. The objective of this study is to evaluate current level of information security in container terminals. Through survey from the four leading container terminal operators in Korea, The results firstly showed that average of information security level of major container terminals was 71.7%. And from the results of data analysis, it revealed that the weak point of information security in Korean container terminals was security management, and in detail, lack of expertise of support group.

• Journal of Navigation and Port Research
• /
• v.39 no.3
• /
• pp.179-184
• /
• 2015

The purpose of this study is to provide appropriate methodology to ensure the safety and integrity of the production riser in offshore structure. In order to select integrity estimation methodology for production riser, level I and II Non-destructive Damage Evaluation (NDE) methods that were applied to existing structures are classified and reviewed. Numerical analysis is performed to verify the applicability and capability on damage detection of reviewed methods. As a result, the damage detection methodology using modal strain energy is more sensitive in detection of the damage than other methods. In practice, the number of sensors is limited due to the environmental and financial conditions. The impact on damage detection performance by reducing the number of sensors is systematically investigated through a series of numerical analyses and the results are discussed. The optimal number of sensor for the integrity estimation of production riser is recommended.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.59 no.3
• /
• pp.29-39
• /
• 2017

In this study, the GPM (Global Precipitation Mission) IMERG (Integrated Multi-satellitE retrievals for GPM) rainfall data was verified and evaluated using ground AWS (Automated Weather Station) and radar in order to investigate the availability of GPM IMERG rainfall data. The SPI (Standardized Precipitation Index) was calculated based on the GPM IMERG data and also compared with the results obtained from the ground observation data for the Hoengseong Dam and Yongdam Dam areas. For the radar data, 1.5 km CAPPI rainfall data with a resolution of 10 km and 30 minutes was generated by applying the Z-R relationship ($Z=200R^{1.6}$) and used for accuracy verification. In order to calculate the SPI, PERSIANN_CDR and TRMM 3B42 were used for the period prior to the GPM IMERG data availability range. As a result of latency verification, it was confirmed that the performance is relatively higher than that of the early run mode in the late run mode. The GPM IMERG rainfall data has a high accuracy for 20 mm/h or more rainfall as a result of the comparison with the ground rainfall data. The analysis of the time scale of the SPI based on GPM IMERG and changes in normal annual precipitation adequately showed the effect of short term rainfall cases on local drought relief. In addition, the correlation coefficient and the determination coefficient were 0.83, 0.914, 0.689 and 0.835, respectively, between the SPI based GPM IMERG and the ground observation data. Therefore, it can be used as a predictive factor through the time series prediction model. We confirmed the hydrological utilization and the possibility of real time drought monitoring using SPI based on GPM IMERG rainfall, even though results presented in this study were limited to some rainfall cases.