• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.4
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• pp.351-359
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• 2015

In order to exactly evaluate the seismic collapse capacity of a structure, probabilistic approach is required by considering uncertainties related to its structural properties and ground motion. Regardless of the types of uncertainties, they influence on the seismic response of a structures and their effects are required to be estimated. An incremental dynamic analysis(IDA) is useful to investigate uncertainty-propagation due to ground motion. In this study, a 3-story steel moment-resisting frame is selected for a prototype frame and analyzed using the IDA. The uncertainty-propagation is assessed with categorized parameters representing epistemic uncertainties, such as the seismic weight, the inherent damping, the yield strength, and the elastic modulus. To do this, the influence of the uncertainty-propagation to the seismic collapse capacity of the prototype frame is probabilistically evaluated using the incremental dynamic analyses based on the Monte-Carlo simulation sampling with the Latin hypercube method. Of various parameters related to epistemic uncertainty-propagation, the inherent damping is investigated to be the most influential parameter on the seismic collapse capacity of the prototype frame.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.291-300
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• 2020

The cartridges used for illuminating a desired point or area are virtually limited in tests and evaluations because of limitations, such as noise during launch, the possibility of fires caused by illuminant charge, and the annual testable quantity. Therefore, to solve these problems, a ground fixed test, which replaces the firing test, or an evaluation method to perform limited tests, can be applied more efficiently. In this paper, the results of an 81mm illuminating cartridge, KM series performed in 2019 were analyzed comprehensively to identify the trends in reliability and quality characteristics and to estimate the shelf life. The shelf life was estimated to be at least 10 years based on the time when the lower confidence level reached 80% at a confidence level of 90%. Considering only major defects, the shelf life can be estimated to be approximately 23 years. On the other hand, the shelf life was estimated to be approximately 11 to 15 years and 25 to 28 years according to the effective illuminating time. Finally, an assessment plan of illuminating cartridges for the mortars was also presented as an improvement plan for an assessment method in the future.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.559-569
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• 2001

With the growth of the Internet, applications using the reliable multicast protocol are increasing. Two important requirements of reliable multicasting are reliability and scalability. To enhance scalability, many methods have been proposed. A typical method is a local recovery scheme. This paper proposes a new stable and effective protocol with the following features. The first is to apply the discipline of the separations of concerns to NAK message. By dividing the functions of the NAK message into the error recovery request and the NAK-suppression, each function can be optimized. Second, a local representative, which is selected gradually and distributively, executes error recovery in somewhat deterministic manner. Finally, by dynamically adjusting the TTL value of the control message, the error recovery domain can be optimized. The proposed scheme has been implemented and experimented on Network Simulator. Compared to the existing schemes, the performance results show that scalability has not only been enhanced but also error recovery time and network overhead have been reduced.

• 한국지형공간정보학회:학술대회논문집
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• 2004.10a
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• pp.5-10
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• 2004

The purpose of this research is to measure a gravitational attraction about urban pulbic service facilities and to evaluate the location of public service facilities. It is important in that these facilities should provide more inexpensive and convenience public service to users. To do this, the GIS's spatial analysis and gravity model were used to analyze the efficiency of the public facilities. The gravity model was conducted as the main analysis method, and another model for this analysis was the discrete model. The gravity model is originally to anticipate migration flows, traffic flows and other types of movements so that this model compares the gravitational attraction between places. The discrete model is to find the optimal location and to evaluate a location of facility regarding urban areas as the combination of node and link. In this research, these two models were adopted to compare and analyze location of Mapo-Gu Office. The results of this research indicated that the locational evaluation of urban public service facilities discovered the appropriateness of those facilities, and the public facilities was necessary to displace to other site.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.147-156
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• 2024

The sustainable management and enhancement of marine resources are becoming increasingly important issues worldwide. This study was conducted in response to these challenges, focusing on the development and performance comparison of fish detection and classification models as part of a deep learning-based technique for assessing the effectiveness of marine resource enhancement projects initiated by the Korea Fisheries Resources Agency. The aim was to select the optimal model by training various sizes of YOLOv8-Seg models on a fish image dataset and comparing each performance metric. The dataset used for model construction consisted of 36,749 images and label files of 12 different species of fish, with data diversity enhanced through the application of augmentation techniques during training. When training and validating five different YOLOv8-Seg models under identical conditions, the medium-sized YOLOv8m-Seg model showed high learning efficiency and excellent detection and classification performance, with the shortest training time of 13 h and 12 min, an of 0.933, and an inference speed of 9.6 ms. Considering the balance between each performance metric, this was deemed the most efficient model for meeting real-time processing requirements. The use of such real-time fish detection and classification models could enable effective surveys of marine resource enhancement projects, suggesting the need for ongoing performance improvements and further research.

• Journal of dental hygiene science
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• v.10 no.1
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• pp.55-61
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• 2010

The main purpose of this study was to identify the service quality of some dental clinics located in Gwangju and find an association between service quality and patient's intention to re-visit the same dental clinic. The search objects were 197 patients from five dental clinics, and data collected by self-administered questionnaire which was composed general characteristics, characteristics relating to visit of clinics, quality of service, patients satisfaction and intentions to re-visit. The used statistical analysis to find the association between quality of service and intention to re-visit was multiple regression analysis. This study looked at relations between quality of dental service, service satisfaction and intentions to visit again, and found that quality of service including six service areas had a statistically significant positive correlations with satisfaction and intentions of re-visit. When this study conducted a multiple regression analysis to identify variables that influence intentions of re-visit, it found that patients revisited the dental clinic only when quality of service was included. In conclusion, quality of service evaluated by patients influenced on their intention of re-visit and especially. Therefore, this study concludes that improvement in satisfaction and intentions of re-visit relies on Accessibility, that is, providing of medical information, consultant telephone, how delivery the dental medical system is. Service quality of dental institutes measured by SERVQUAL model and intention to re-visit.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.601-609
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• 2022

Jack-up drilling rigs are mobile offshore platforms widely used in the offshore oil and gas exploration industry. These are independent, three-legged, self-elevating units with a cantilevered drilling facility for drilling and production. A typical jack-up rig includes a triangular hull, a tower derrick, a cantilever, a jackcase, living quarters and legs which comprise three-chord, open-truss, X-braced structure with a spudcan. Generally, jack-up rigs can only operate in water depths ranging from 130m to 170m. Recently, there has been an increasing demand for jack-up rigs for operating at deeper water levels and harsher environmental conditions such as waves, currents and wind loads. All static and dynamic loads are supported through legs in the jack-up mode. The most important issue by society is to secure the safety of the leg structure against collision that causes large instantaneous impact energy. In this study, nonlinear FE -analysis and verification of the requirement against collision for 35MJ recommended by DNV was performed using LS-Dyna software. The colliding ship used a 7,500ton of shore supply vessel, and five scenarios of collisions were selected. From the results, all conditions do not satisfy the class requirement of 35MJ. The loading conditions associated with chord collision are reasonable collision energy of 15M and brace collisions are 6MJ. Therefore, it can be confirmed that the identical collision criteria by DNV need to be modified based on collision scenarios and colliding members.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.305-313
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• 2023

With an increasing interest in the commercialization of research results in the present societal climate, especially in the construction industry, preliminary product analysis plays a critical role when introducing a new product to the market. It significantly influences the product's success or failure. In this context, this study aims to investigate the utility of Importance-Performance Analysis (IPA) as a management strategy tool for preliminary analysis in the commercialization of new architectural technologies. The study specifically assesses a smart ball product engineered for pipeline inspection. The evaluation is carried out based on product quality, convenience, and usability categories. Seventeen factors are recognized as sub-items, and a survey is conducted among relevant experts and consumer groups. From the survey, four key items are chosen: "Keep up the good work," "Concentrate here," "Low priority," and "Possible overkill." Suitable strategic measures are derived for each item. By conducting a correlation analysis between product importance and performance, this study offers a method to establish priority directions for future development. This analysis assists in identifying areas that necessitate improvement or additional focus to increase the product's commercial potential. On the whole, this study contributes to understanding and applying Importance-Performance Analysis as a valuable tool in the preliminary analysis and commercialization of novel technologies in the field of architecture.

• Journal of Korea Port Economic Association
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• v.27 no.1
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• pp.75-94
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• 2011

This paper is concerned about applying the AHP(Analytic Hierarchy Process) for a priority analysis of equipment operation plan to improve productivity of the container terminal in Gwangyang port. In this study, main elements of container terminal are assumed as into yard equipment area, transport equipment area, berth equipment area and C/Center area. A questionnaire is used to collect the opinions of equipment operating department and operational planning department. On the whole, the result of the analyses reveals that the most important area is yard equipment area. Examining each department is responses, equipment operating department preferred the C/Center area to other areas, on the other hand, operational planning department preferred yard equipment area. The result of this study suggests some guidelines for deciding priority of operation plan in the container terminal.

• Journal of the Korean Geosynthetics Society
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• v.20 no.4
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• pp.19-32
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• 2021

In this study, evaluation and consideration of domestic/overseas design, construction, and quality control performed by the authors on the deep cement mixing method were performed, and improvements for the development of the DCM method were suggested in the future. As a result of this study, it was found that the cross-sectional area correction for strength is required during the laboratory test of mix proportion, and caution is required because the extrapolation method may lead to different results from the actual one. Applicable design methods should be selected in consideration of both the improvement ratio and the type of improvement during design, and it was confirmed that the allowable compressive strength to which the safety factor was applied refers to the standard value for stability review and not the design parameters. In the case of the stress concentration ratio, rather than applying a conventional value, it was possible to perform economical design by calculating the experimental and theoretical stress concentration ratio reflecting the design conditions. In the case where pre-boring is expected during construction, if the increased water content is not large compared to the original, there were cases where a major problem did not occur even if the result that did not consider the increase in water content was used. In addition, it was confirmed that when the ratio of the top treatment length to the improved length is high, a small amount of design cement contents per unit length can be injected during construction. In the case of quality control, it was evaluated that D/4~2D/4 for single-axis and D/4 point for multi-axis were optimal for coring of grouting mixtures. As an item for quality control, it is judged that the standard that considers the TCR along with the unconfined compressive strength of grouting mixtures is more suitable for the domestic situation.