• International conference on construction engineering and project management
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• 2020.12a
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• pp.3-12
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• 2020

Nowadays, as-is BIM generation has been popularly adopted in the architecture, engineering, construction and facility management (AEC/FM) industries. In order to generate a 3D as-is BIM of a structural component, current methods require a registration process that merges different sets of point cloud data obtained from multiple locations, which is time-consuming and registration error-prone. To tackle this limitation, this study proposes a registration-free 3D point cloud data acquisition technique for as-is BIM generation. In this study, small-size mirrors that rotate in both horizontal and vertical direction are used to enable the registration-free data acquisition technique. First, a geometric model that defines the relationship among the mirrors, the laser scanner and the target component is developed. Second, determinations of optimal laser scanner location and mirror location are performed based on the developed geometrical model. To validate the proposed registration-free as-is BIM generation technique, simulation tests are conducted on key construction components including a PC slab and a structural wall. The result demonstrates that the registration-free point cloud data acquisition technique can be applicable in various construction elements including PC elements and structural components for as-is BIM generation.

• Journal of the Korean GEO-environmental Society
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• v.24 no.1
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• pp.51-60
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• 2023

Unlike the vertical drilling in the directional drilling should be minimized torque and drag in the well trajectory that avoided problems such as drillstring transformation, casing wear and key-seating. These torque and drag magnitude is determined by variations such as the well trajectory geometry, drilling mud, drillstring type and kick-off point. Therefore, it is essential to consider these variations for designing directional well trajectory. In this study, it was selected well trajectory by the most common build-hold type well and calculated torque and drag on each section by Analytical friction model. Analysis indicates that torque and drag could be minimized by using high lubricity drilling mud, kick-off point appropriate according to the well geometry and possible minimize dogleg severity. The results of this study is useful to minimize torque and drag from directional well trajectory design.

• Journal of Korea Multimedia Society
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• v.24 no.5
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• pp.659-666
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• 2021

With the continuous development of deep learning, human behavior recognition algorithms have achieved good results. However, in a multi-person recognition environment, the complex behavior environment poses a great challenge to the efficiency of recognition. To this end, this paper proposes a multi-person pose estimation model. First of all, the human detectors in the top-down framework mostly use the two-stage target detection model, which runs slow down. The single-stage YOLOv3 target detection model is used to effectively improve the running speed and the generalization of the model. Depth separable convolution, which further improves the speed of target detection and improves the model's ability to extract target proposed regions; Secondly, based on the feature pyramid network combined with context semantic information in the pose estimation model, the OHEM algorithm is used to solve difficult key point detection problems, and the accuracy of multi-person pose estimation is improved; Finally, the Euclidean distance is used to calculate the spatial distance between key points, to determine the similarity of postures in the frame, and to eliminate redundant postures.

• Earthquakes and Structures
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• v.12 no.3
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• pp.297-307
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• 2017

Evaluation on the sidesway seismic collapse capacity of the widely used low- and medium-height structures is meaningful. These structures with such type of collapse are recognized that behave as inelastic deteriorating single-degree-of-freedom (SDOF) systems. To incorporate the deteriorating effects, the hysteretic loop of the nonlinear SDOF structural model is represented by a tri-linear force-displacement relationship. The concept of collapse capacity spectra are adopted, where the incremental dynamic analysis is performed to check the collapse point and a normalized ground motion intensity measure corresponding to the collapse point is used to define the collapse capacity. With a large amount of earthquake ground motions, a systematic parameter study, i.e., the influences of various ground motion parameters (site condition, magnitude, distance to rupture, and near-fault effect) as well as various structural parameters (damping, ductility, degrading stiffness, pinching behavior, accumulated damage, unloading stiffness, and P-delta effect) on the structural collapse capacity has been performed. The analytical formulas for the collapse capacity spectra considering above influences have been presented so as to quickly predict the structural collapse capacities.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1153-1164
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• 2024

In recent years, unmanned ground vehicles (UGVs) have been used to search for lost or stolen radioactive sources to avoid radiation exposure for operators. To achieve autonomous localization of radioactive sources, the UGVs must have the ability to automatically determine the next radiation measurement location instead of following a predefined path. Also, the radiation field of radioactive sources has to be reconstructed or inverted utilizing discrete measurements to obtain the radiation intensity distribution in the area of interest. In this study, we propose an effective source localization framework and method, in which UGVs are able to autonomously explore in the radiation area to determine the location of radioactive sources through an iterative process: path planning, radiation field reconstruction and estimation of source location. In the search process, the next radiation measurement point of the UGVs is fully predicted by the design path planning algorithm. After obtaining the measurement points and their radiation measurements, the radiation field of radioactive sources is reconstructed by the Gaussian process regression (GPR) model based on machine learning method. Based on the reconstructed radiation field, the locations of radioactive sources can be determined by the peak analysis method. The proposed method is verified through extensive simulation experiments, and the real source localization experiment on a Cs-137 point source shows that the proposed method can accurately locate the radioactive source with an error of approximately 0.30 m. The experimental results reveal the important practicality of our proposed method for source autonomous localization tasks.

• Knowledge Management Research
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• v.9 no.3
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• pp.107-123
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• 2008

Company strategy that considers market trend becomes a more important key to success in the new product development. Well-being as a present social trend has created a huge new product market. but with increasing number of camouflaged well-being products that are not fulfilled consumer needs. The purpose of this study is to understand the concept of well-being products from a consumer point of view an to find five consumer values based on the consumer value model of Sheth, Newman, and Gross(1991) through conducting content analysis from semi-structured individual In-depth Interviews. This study has a significance in identifying the detailed consumer value attributes and influence factors by collecting practical and reach qualitative data in the lack of systematic research of domestic well-being market and its products from a consumer point of view. The result of this study will be a foundation of future quantitative researches and provide a guideline to companys' well-being marketing strategy.

• Nuclear Engineering and Technology
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• v.50 no.8
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• pp.1277-1288
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• 2018

In this work, the reactor kinetics capability is used to compute the design safety parameters in a PWR due to complete loss of coolant flow during protected and unprotected accidents. A thermal-hydraulic code coupled with a point reactor kinetic model are used for these calculations; where kinetics parameters have been developed from the neutronic SRAC code to provide inputs to RELAP5-3D code to calculate parameters related to safety and guarantee that they meet the regulatory requirements. In RELAP5-3D the reactivity feedback is computed by both separable and tabular models. The results show the importance of the reactivity feedback on calculating the power which is the key parameter that controls the clad and fuel temperatures to maintain them below their melting point and therefore prevent core melt. In addition, extending modeling capability from separable to tabular model has nonremarkable influence on calculated safety parameters.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.317-320
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• 2015

Documenting work-in-progress on construction sites using images captured with smartphones, point-and-shoot cameras, and Unmanned Aerial Vehicles (UAVs) has gained significant popularity among practitioners. The spatial and temporal density of these large-scale site image collections and the availability of 4D Building Information Models (BIM) provide a unique opportunity to develop BIM-driven visual analytics that can quickly and easily detect and visualize construction progress deviations. Building on these emerging sources of information this paper presents a pipeline for model-driven visual analytics of construction progress. It particularly focuses on the following key steps: 1) capturing, transferring, and storing images; 2) BIM-driven analytics to identify performance deviations, and 3) visualizations that enable root-cause assessments on performance deviations. The information requirements, and the challenges and opportunities for improvements in data collection, plan preparations, progress deviation analysis particularly under limited visibility, and transforming identified deviations into performance metrics to enable root-cause assessments are discussed using several real world case studies.

• International Journal of Fluid Machinery and Systems
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• v.10 no.3
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• pp.287-295
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• 2017

The most detrimental pressure pulsations in high-head pump-turbines is caused by the rotor-stator interaction (RSI) between the guide vanes and runner blades. When the pump-turbine operates in the S-shaped region of the characteristic curves, the deteriorative flow structures may significantly strengthen RSI, causing larger pressure pulsations and stronger vibration with an increased risk of mechanical failure. CFD simulations were carried out to analyze the impacts of flow evolution on the pressure pulsations in the S-shaped region of a model pump-turbine. The results show that the reverse flow vortex structures (RFVS) at the runner inlet have regular development and transition patterns when discharge reduces from the best efficiency point (BEP). The RFVS first occur at the hub side, and then shift to the mid-span near the no-load point, which cause the strongest pressure pulsations. The locally distributed RFVS at hub side enhance the local RSI and makes the pressure fluctuations at the corresponding sections stronger than those at the rest sections along the spanwise direction. Under the condition of RFVS at the mid-span, the smaller flow rate make the smaller difference of pressure pulsation amplitudes in the spanwise direction. Moreover, the rotating stall, rotating at 35.7%-62.5% of the runner rotational frequency, make the low frequency components of pressure pulsations distribute unevenly along the circumference in the vaneless space. However, it have little influence on the distributions of high components.

• International Commerce and Information Review
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• v.6 no.2
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• pp.107-127
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• 2004

The rapid development of internet information technology has increased interest in e-Trade these days, but it is not activated greatly up to now. In order to promote e-Trade, it is essential to construct cooperative process such as connecting systems among trade related parties. Building e-Trade platform which is based on the infrastructure of the past trade automatic system is key point of promoting e-Trade. To do this, a study on the basic concept and specific components of e-Trade platform is needed absolutely. At this point of view, after this paper has examined domestic and foreign studies on the fundamental technologies about electronic commerce, it drew several key technologies that could be applied to e-Trade considering the current IT trend. Then it evaluates these technologies according to Technology Reference Model(TRM) of the National Computerization Agency. This will help us to show the operation strategy as well as the concept of future e-Trade platform and its composition. On the basis of the theoretical background, this paper classified NCA's technology model into 6 fields, which are application. data, platform, communication, security and management. Considering the key technologies, e-Trade platform has to be mutually connected and accept international standards such as XML. In the aspect of business side, trade relative agencies' business process as well as trading company's process has to be considered. Therefore, e-Trade platform can be classified into 3 parts which are service, infrastructure and connection. Infrastructure part is compared of circulating and managing system of electronic document, interface and service framework. Connecting service (application service) and additional service (application service) consist of service part. Connecting part is a linking mutual parts and can be divided into B2B service and B20 service. The organization operating this e-trade platform must have few responsibilities and requirements. It needs to positively accept existing infrastructure of trade automatic system and improving the system to complete e-trade platform. It also have to continuously develop new services and possess ability to operate the system for providing proper services to demanders. As a result, private sector that can play a role as TTP(Third Trust Party) is adequate for operating the system. In this case, revising law is necessary to support the responsibility and requirement of private sector.