• Computers and Concrete
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• v.13 no.5
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• pp.587-601
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• 2014

A sophisticated finite element modeling approach is proposed to simulate unbonded post-tensioned concrete slabs. Particularly, finite element contact formulation was employed to simulate the sliding behavior of unbonded tendons. The contact formulation along with other discretizing schemes was selected to assemble the post-tensioned concrete system. Three previously tested unbonded post-tensioned two-way and one-way slabs with different reinforcement configurations and boundary conditions were modeled. Numerical results were compared against experimental data in terms of global pressure-deflection relationship, stiffness degradation, cracking pattern, and stress variation in unbonded tendons. All comparisons indicate a very good agreement between the simulations and experiments. The exercise of model validation showcased the robustness and reliability of the proposed modeling approach applied to numerical simulation of post-tensioned concrete slabs.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3_1spc
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• pp.587-592
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• 2013

Until recently, the primary users of wheelchairs were people with lower body disabilities. However, the number of patients recovering from accidents or surgery, as well as the number of elderly people using wheelchairs, is constantly increasing. This study examined the design and manufacture of standing and gait assist wheelchairs that assist temporary gait disturbed patients to take rehabilitation training and elderly people to engage in walking exercise. A kinematic analysis was used to select a drive motor and design a four-bar linkage mechanism for lifting the backrest vertically. Using a multibody dynamic simulation, detailed design was performed taking into consideration the spatial motion and partial interference, and the necessary push force and stroke of the linear actuator were also calculated. To ensure structural safety, the von-Mises equivalent stresses of the upper and lower brackets of the linear actuator were verified through a finite element analysis. The manufactured wheelchair was shown to operate successfully as intended, using the developed controller for the drive motors and linear actuator.

• Journal of Korea Water Resources Association
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• v.56 no.12
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• pp.969-980
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• 2023

Since the 2000s, ensemble streamflow prediction (ESP) has been actively utilized in South Korea, primarily for hydrological forecasting purposes. Despite its notable success in hydrological forecasting, the original objective of enhancing water resources system management has been relatively overlooked. Consequently, this study aims to demonstrate the utility of ESP in water resources management by creating a simple hypothetical exercise for dam operators and applying it to actual multi-purpose dams in South Korea. The hypothetical exercise showed that even when the means of ESP are identical, different costs can result from varying standard deviations. Subsequently, using sampling stochastic dynamic programming (SSDP) and considering the capacity-inflow ratio (CIR), optimal release patterns were derived for Soyang Dam (CIR = 1.345) and Chungju Dam (CIR = 0.563) based on types W and P. For this analysis, Type W was defined with standard deviation equal to the mean inflow, and Type P with standard deviation ten times of the mean inflow. Simulated operations were conducted from 2020 to 2022 using the derived optimal releases. The results indicate that in the case of Dam Chungju, more aggressive optimal release patterns were derived under types with smaller standard deviations, and the simulated operations demonstrated satisfactory outcomes. Similarly, Soyang Dam exhibited similar results in terms of optimal release, but there was no significant difference in the simulation between types W and P due to its large CIR. Ultimately, this study highlights that even with the same mean values, the standard deviation of ESP impacts optimal release patterns and outcomes in simulation. Additionally, it underscores that systems with smaller CIRs are more sensitive to such uncertainties. Based on these findings, there is potential for improvements in South Korea's current operational practices, which rely solely on single representative values for water resources management.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.4
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• pp.420-430
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• 2003

This paper presents an immersive multimodal Gumdo simulation game that allows a user to experience the whole body interaction with an intelligent cyber fencer. The proposed system consists of three modules: (i) a nondistracting multimodal interface with 3D vision and speech (ii) an intelligent cyber fencer and (iii) an immersive feedback by a big screen and sound. First, the multimodal Interface with 3D vision and speech allows a user to move around and to shout without distracting the user. Second, an intelligent cyber fencer provides the user with intelligent interactions by perception and reaction modules that are created by the analysis of real Gumdo game. Finally, an immersive audio-visual feedback by a big screen and sound effects helps a user experience an immersive interaction. The proposed system thus provides the user with an immersive Gumdo experience with the whole body movement. The suggested system can be applied to various applications such as education, exercise, art performance, etc.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.722-727
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• 2009

The technology of distinguishing human motion states is required in the areas of measuring and analyzing biosignals changing according to physical activities, diagnosing sleep disorder, screening the effect of treatment, examining chronic patients' kinetic state, prescribing exercise therapy, etc. The present study implemented a fuzzy inference system based on fuzzy rules that distinguish human motion states (tying, sitting, walking, and running) by acquiring and processing data of LAA, TAA, L-MAD, and T-MAD using ADXL202AE of Analog Devices embedded in an armband. The membership degree and fuzzy rules in each area of input (LAA, TAA, L-MAD, and T-MAD) and output (tying, sitting, walking, and running) data used here were determined using numeric data obtained from experiment. In the results of analyzing data for simulation generated in order of tying$\rightarrow$walking$\rightarrow$running$\rightarrow$tying, the sorting rate for motion states tying, sitting, walking, and running was 100% for each motion.

• Korean Journal of Remote Sensing
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• v.30 no.2
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• pp.293-302
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• 2014

Radar systems are used in remote sensing mainly as space-borne, airborne and ground-based Synthetic Aperture Radar (SAR), scatterometer and Doppler radar. Those systems are composed of expensive equipments and require expertise and professional skills for operation. Because of the limitation in getting experiences of the radar and SAR systems and its operations in ordinary universities and institutions, it is difficult to learn and exercise essential principles of radar hardware which are essential to understand and develop new application fields. To overcome those difficulties, in this paper, we present the construction and experiment of a low-cost educational radar system based on the blueprints of the MIT Cantenna system. The radar system was operated in three modes. Firstly, the velocity of moving cars was measured in Doppler radar mode. Secondly, the range of two moving targets were measured in radar mode with range resolution. Lastly, 2D images were constructed in GB-SAR mode to enhance the azimuth resolution. Additionally, we simulated the SAR raw data to compare Deramp-FFT and ${\omega}-k$ algorithms and to analyze the effect of antenna positional error for SAR focusing. We expect the system can be further developed into a light-weight SAR system onboard a unmanned aerial vehicle by improving the system with higher sampling frequency, I/Q acquisition, and more stable circuit design.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.4
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• pp.51-59
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• 2008

Incontinence is the urination disorder as the leakage of urine without her own volition and the woman's representative disease which reduce the life quality. The electromagnetic therapy has high possibility of development cause it has no needs of operant exercise, no arousing of shame and impossibility of infection. But, it has improvement points such as uniformity of the treatment protocol, patient dependance and absent of patient monitoring system. With these demands, the system which stimulate the pelvic flaw muscle with electromagnetic and monitoring the patient status during the therapy is proposed, in this study. And individually adapted electromagnetic therapy system for incontinence patient is also suggested. The proposed system consisted of electromagnetic generation device, cooling device, treating chair, patient monitoring device with pulsation and control software. The simulation for high power system and evaluation confirm was performed. With the development of control software, the convenience of using and maintenance are ensured and the patient adapted therapy protocol is applied. The developed patient adapted electromagnetic therapy system with monitoring device is regarded as the patient affinitive treating method by reducing the riskiness, improving the efficiency with patterned protocol and pre/post therapy. These results, in this study, can bring the safe and organized treatment method to incontinence patients and can lead the variable study for electromagnetic therapy in incontinence.

• The Korean Journal of Applied Statistics
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• v.28 no.5
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• pp.921-932
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• 2015

This study analyzed military personnel survivability in regards to offensive operations according to the scientific military training data of a reinforced infantry battalion. Scientific battle training was conducted at the Korea Combat Training Center (KCTC) training facility and utilized scientific military training equipment that included MILES and the main exercise control system. The training audience freely engaged an OPFOR who is an expert at tactics and weapon systems. It provides a statistical analysis of data in regards to state-of-the-art military training because the scientific battle training system saves and utilizes all training zone data for analysis and after action review as well as offers training control during the training period. The methodologies used the Cox PH modeling (which does not require parametric distribution assumptions) and decision tree modeling for survival data such as CART, GUIDE, and CTREE for richer and easier interpretation. The variables that violate the PH assumption were stratified and analyzed. Since the Cox PH model result was not easy to interpret the period of service, additional interpretation was attempted through univariate local regression. CART, GUIDE, and CTREE formed different tree models which allow for various interpretations.