• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.425-429
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• 2006

The understanding and prediction of the behavior of flow in open channels are important to the solution of a wide variety of practical flow problems in water resources engineering. Recently, frequent drought has increased the necessity of an effective water resources control and management of river flows for reserving instream flow. The objective of this study is to develop an efficient and accurate finite element model based on Streamline Upwind/Petrov-Galerkin(SU/PG) scheme for analyzing and predicting two dimensional flow features in complex natural rivers. Several tests were performed in developed all elements(4-Node, 6-Node, 8-Node elements) for the purpose of validation and verification of the developed model. The U-shaped channel of flow and natural river of flow were performed for tests. The results were compared with these of laboratory experiments and RMA-2 model. Such results showed that solutions of high order elements were better accurate and improved than those of linear elements. Also, the suggested model displayed reasonable velocity distribution compare to RMA-2 model in meandering domain for application of natural river flow. Accordingly, the developed finite element model is feasible and produces reliable results for simulation of two dimensional natural river flow. Also, One contribution of this study is to present that results can lead to significant gain in analyzing the accurate flow behavior associated with hydraulic structure such as weir and water intake station and flow of chute and pool.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1669-1679
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• 2010

Related to the on-going "Train Control System Project of Pilot Line Construction for Urban MAGLEV Train", activities by each phase shall be conducted to achieve SIL4 level and obtain safety certification from the Independent Safety Assessment(ISA), based on the IEC standards((IEC 62278/62279 and IEC 62425) for the first time in Korea. This thesis describes the introduction of IEC standards, system assurance activities (such as plan, analysis, test, verification and validation) in compliance with requirements management and project life-cycle and relations with the safety assessment activities; and certification activities (such as document reviews and audits) through system RAMS activities, software quality assurance activities and safety assessment, for the purpose of achieving a successful safety certification at the time of completing the project as system assurance activities including software and safety certification activities in order to acquire the safety certification for train control system which does not exist at all in domestic cases. It is believed that overall system safety assurance activities in this project will contribute to develop more upgraded products of the domestic train control system on the quality and safety point of view, find overseas markets and establish a bridgehead in the future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.4
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• pp.315-322
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• 2012

In these days, importance of HVAC system in office building is steadily growing in terms of thermal comfort and energy savings. As a energy efficient heating and cooling system, system air-conditioner which can be controlled distinctly and has a high COP is more widely adopted nowadays. However, the features and advantages of system air-conditioner were not reported well because system air-conditioner did not describe yet by conventional simulation methods such as TRNSYS, e-Quest, Energyplus, etc. In this study, by using the TRNSYS program which is able to show module implementation and building energy consumption analysis, system air-conditioner module will be proposed and validated through comparison between the simulation results and measurement results.

• The Journal of Korea Robotics Society
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• v.16 no.4
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• pp.327-335
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• 2021

In this paper, we propose an embedded robot system based on "ROS2 on Yocto" that can support various robots. We developed a lightweight OS based on the Yocto Project as a next-generation robot platform targeting cloud robotics. Yocto Project was adopted for portability and scalability in both software and hardware, and ROS2 was adopted and optimized considering a low specification embedded hardware system. We developed SLAM, navigation, path planning, and motion for the proposed robot system validation. For verification of software packages, we applied it to home cleaning robot and indoor delivery robot that were already commercialized by LG Electronics and verified they can do autonomous driving, obstacle recognition, and avoidance driving. Memory usage and network I/O have been improved by applying the binary launch method based on shell and mmap application as opposed to the conventional Python method. Finally, we verified the possibility of mass production and commercialization of the proposed system through performance evaluation from CPU and memory perspective.

• Journal of Korean Clinical Nursing Research
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• v.29 no.1
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• pp.75-84
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• 2023

Purpose: This study developed a protocol for nursing care after death for adult patients in hospitals. Methods: This was a methodological study to develop a care after death protocol. The preliminary protocol was developed based on a literature review, guidelines, and practice recommendations from groups of experts and clinical nurses. Content validity was evaluated by a group of experts (n=6) and nurses (n=30) in two hospitals. Results: The preliminary protocol recommendations were modified by validation and the open-question analysis results. The final protocol comprised three general recommendations and 43 recommendations in five steps that are verification and notification of a death, personal care of the body, viewing the patient, patient transfer, and documentation and self-care. Conclusion: This study result provides nurses with a consensus information on patient care after death and family support in a hospital setting. This nursing protocol is expected to improve the quality of care after death for adult patients and their families, and can be used for developing educational and emotional support for nurses to accomplish their important role.

• Journal of Wind Energy
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• v.15 no.1
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• pp.60-68
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• 2024

In this study, a hardware-in-the-loop simulation (HILS) environment was established using MATLAB/Simulink to simulate and verify the power performance of a wind turbine. The target wind turbine was selected as the NREL 5 MW model, and modeling was performed based on the disclosed specifications. The HILS environment consists of a PC equipped with a MATLAB/Simulink program, a programmable logic controller (PLC) for uploading and linking control algorithms, and data acquisition (DAQ) equipment to manage wind turbine data input and output. The operation of the HILS environment was carried out as a procedure of operation (PC) of the target wind turbine modeled based on MATLAB/Simulink, data acquisition (PLC) of control algorithms, control command calculation (PLC), and control command input (PC). The simulation was performed using the HILS environment under turbulent wind conditions and compared with the simulation results performed under the same conditions in the HILS environment using the commercial program Bladed for performance verification. From the comparison, it was found that the dynamic simulation results of the Bladed HILS and the MATLAB HILS were close in power performances and the errors in the average values of rotor rotation speed and power generation between the two simulations were about 0.44 % and 3.3 %, respectively.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.269-269
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• 2001

Maintainability refers to the ease with which maintenance work can be done. It involves the process of ensuring that products can be easily and safely maintained and that the maintenance support requirement is minimized. When a product has a reasonably long life, the cost of operation and support during that life can greatly exceed the initial capital cost. The value to the customer of optimizing maintainability should be evident. Some effort and expense applied to achieving a product which can be easily and cheaply maintained will make very significant savings in the life cycle costs. In this paper, the International Standard IEC 60300-3-10, which is the application guide for maintainability, is considered. This standard can be used to implement a maintainability program covering the initiation, development and in-service phases of a product. It provides guidance on how the maintenance aspects of the tasks should be considered in order to achieve optimum maintainability. The elements of a maintainability program, which are maintenance policy and concept, maintainability studies, project management, design for maintainability, analysis and prediction methods, maintenance verification and validation, analysis of life cycle cost, maintenance support planning, and collection and analysis of maintenance data, are fully discussed in this paper.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.409-413
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• 2005

Even though the relative importance of length scale of flow system allow us to simplify three dimensional flow problem to one or two dimensional representation, many systems still require three dimensional analysis. The objective of this study is to develop an efficient and accurate finite element model for analyzing and predicting three dimensional flow features in natural rivers and to offend to model spreading of pollutants and transport of sediments in the future. Firstly, three dimensional Reynolds averaged Navier-Stokes equations with the hydrostatic pressure assumption in generalized curvilinear coordinates were combined with the kinematic free-surface condition. Secondly. to simulate realistic high Reynolds number flow, the model employed the Streamline Upwind/Petrov-Galerkin(SU/PG) scheme as a weighting function for the finite element method in conjunction with an appropriate turbulence model(Smagorinsky scheme for the horizontal plain and Mellor-Yamada scheme for the vertical direction). Several tests is performed for the purpose of validation and verification of the developed model. A simple rectangular channel, 5-shaped and U-shaped channel are used for tests and comparisons are made with RMA-10 model. Runs for each case is converged stably without a oscillation and calculated water-surface deformation, longitudinal and transversal velocities, and velocity vector fields are in good agreement with the results of RMA-10 model.

• Computers and Concrete
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• v.21 no.1
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• pp.47-54
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• 2018

Artificial neural network models can be successfully used to simulate the complex behavior of many problems in civil engineering. As compared to conventional computational methods, this popular modeling technique is powerful when the relationship between system parameters is intrinsically nonlinear, or cannot be explicitly identified, as in the case of concrete behavior. In this investigation, an artificial neural network model was developed to assess the residual compressive strength of self-compacted concrete at elevated temperatures ($20-900^{\circ}C$) and various relative humidity conditions (28-99%). A total of 332 experimental datasets, collected from available literature, were used for model calibration and verification. Data used in model development incorporated concrete ingredients, filler and fiber types, and environmental conditions. Based on the feed-forward back propagation algorithm, systematic analyses were performed to improve the accuracy of prediction and determine the most appropriate network topology. Training, testing, and validation results indicated that residual compressive strength of self-compacted concrete, exposed to high temperatures and relative humidity levels, could be estimated precisely with the suggested model. As illustrated by statistical indices, the reliability between experimental and predicted results was excellent. With new ingredients and different environmental conditions, the proposed model is an efficient approach to estimate the residual compressive strength of self-compacted concrete as a substitute for sophisticated laboratory procedures.

• Journal of Korea Multimedia Society
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• v.21 no.12
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• pp.1407-1416
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• 2018

The purpose of this study was to train a model for the ulna and radius bone segmentation based on Convolutional Neural Networks and to verify the segmentation model. The data consisted of 840 training data, 210 tuning data, and 200 verification data. The learning model for the ulna and radius bone bwas based on U-Net (19 convolutional and 8 maximum pooling) and trained with 8 batch sizes, 0.0001 learning rate, and 200 epochs. As a result, the average sensitivity of the training data was 0.998, the specificity was 0.972, the accuracy was 0.979, and the Dice's similarity coefficient was 0.968. In the validation data, the average sensitivity was 0.961, specificity was 0.978, accuracy was 0.972, and Dice's similarity coefficient was 0.961. The performance of deep convolutional neural network based models for the segmentation was good for ulna and radius bone.