• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.3
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• pp.15-20
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• 2015

After the US government declared 3D printing technology a next-generation manufacturing technology, there have been many practical studies conducted to expand 3D printing technology to manufacturing technologies, called AMERICA MAKES. In particular, the Keck Center, located at the University of Texas at El Paso, has studied techniques for easily combing the 3D stacking process with space mobility and expanded these techniques to simultaneous staking techniques for multiple materials. Additionally, it developed convergence manufacturing techniques, such as direct inking techniques, in order to produce a module structure that combines electronic circuits and components, such as CUBESET. However, in these studies, it is impossible to develop a unified system using traditional independent through simple sequencing connections. This is because there are many problems in the integration between the stacking modeling of 3D printers and post-machining, such as thermal deformations, the precision accuracy of 3D printers, and independently driven coordinate problems among process systems. Therefore, in this paper, the integration method is suggested, which combines these 3D printers and subsequent machining process systems through an Internet-based cloud. Additionally, the sequential integrated system of a 3D printer, an NC milling machine, machine vision, and direct inking are realized.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.6
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• pp.512-519
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• 2004

This paper described the free vibration characteristics of Optimized H Type (OHT) spacer grids (SG) supporting the PWR fuel rod. The vibration test and the finite element (FE) analysis are performed under the free boundary condition and the clamped at two points (or three points) in the bottom which is the same one as the experimental condition for the dummy rod continuously supported by spacer grids. A modal test is conducted by the impulse excitation method using an impulse hammer and an accelerometer, and the TDAS module of the I-DEAS software is used to acquire and analyze the sensor signals. The softwares related to the FE analysis are the I-DEAS for the geometrical shape modeling and meshing, and the ABAQUS for solving. The fundamental frequency of the OHT SG by experiment under a clamped condition at two points is 175.18 Hz, and shows a bending mode. We think there is no resonance between the fuel rod and the SG because the SG's frequency is higher than that of the fuel rod existing in the range from 30 to 120 Hz. The fundamental frequency of the SG under the free boundary condition is 349.2 Hz showing a bending mode, and the results between the test and the analysis have a good agreement with maximum 7 ％ in error It is also found that the FE analysis model of the OHT SGs to analyze an impact, a buckling and vibration et al. has been generated with reliability.

• Journal of IKEEE
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• v.25 no.1
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• pp.95-100
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• 2021

If we know the location of the hull block and the welding feeder in the shipyard, we can easily obtain the location information of the worker. That data is very useful for implementing a workplace safety monitoring system. However, it is difficult to apply a fixed communication network to the workplace due to the specificity of the hull structure and welding process. In this study, inductive power line communication, which can replace dedicated communication line, was reviewed. A ferrite core was used as an inductive coupler to be installed on the power cable of the welding machine, and a nano-crystalline core was applied as a coupler to be fastened to the support rod of the metal block. In order to visualize the operating principle of the proposed couplers, 3D modeling and finite element analysis were performed with the COMSOL AC/DC module. In the communication performance test using an aluminum profile, when the communication channel was formed by the contact of the welding electrode, the bandwidth was kept above 6 Mbps.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.375-383
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• 2012

Soil erosion has been emphasized as serious environmental problem affecting water quality in the receiving waterbodies. Recently, Best Management Practices (BMPs) have been applied at a field to reduce soil erosion and its effectiveness in soil erosion reduction has been monitored with various methods. Although monitoring at fields/watershed outlets would be accurate way for these ends, it is not possible at some fields/watersheds due to various limitations in direct monitoring. Thus modeling has been suggested as an alternative way to evaluate effects of the BMPs. Most models, which have been used in evaluating hydrology and water quality at a watershed, could not reflect rainfall intensity in runoff generation and soil erosion processes. In addition, source codes of these models are not always public for modification/enhancement. Thus, runoff-sediment evaluation system using hourly rainfall data and vegetated filter strip (VFS) evaluation module at field level were developed using open source MapWindow GIS component in this study. This evaluation system was applied to Bangdongri, Chuncheonsi to evaluate its prediction ability and VFS module in this study. The NSE and $R^2$ values for runoff estimation were 0.86 and 0.91, respectively, and measured and simulated sediment yield were 15.2 kg and 16.5 kg indicating this system, developed in this study, can be used to simulate runoff and sediment yield with acceptable accuracies. Nine VFS scenarios were evaluated for effectiveness of soil erosion reduction. Reduction efficiency of the VFS was high when sediment inflow was small. As shown in this study, this evaluation system can be used for evaluation BMPs with local rainfall intensity and variations considered with ease-of-use GIS interface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.190-196
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• 2016

This paper proposes a humanoid robot performance system for performing in public places, such as an event, exhibition, or street performance. The system of modular structures can be moved easily, and can be played by a module or a combination of modules. The system developed with open source-based software and hardware is easy to adapt and improve. The robot performance control program for controlling robots, displays, audios, videos, and performance instruments was developed using the open source language, Processing. The performance instruments were developed using the open source hardware, Arduino. The contents of the robot performance were composed of scene-specific image, background audio, computer graphics, and videos. For their control and synchronization, the performance control program communicates with the humanoid robots and the performance instruments. In addition, performance accessories required to represent the performance concepts are produced by 3D modeling and printing. In a public place, the robot performance is performed with the theme of celebrating a Halloween day.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.6
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• pp.1-12
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• 2018

The objectives of this study were to develop a system linking hydrologic and water quality models considering the mechanisms of agricultural reservoir and paddy cultivation and to evaluate whether the developed system simulates hydrologic and water quality processes better than a hydrologic model that do not consider the mechanisms. The system consisted of Hydrological Simulation Program-Fortran (HSPF) as a watershed model, Module-based hydrologic Analysis System for Agricultural watersheds (MASA) as reservoir water balance model, and Chemical, Runoff and Erosion from Agricultural Management System-Paddy (CREAMS-PADDY) as a hydrologic and water quality model for paddy fields. This study carried out on the Seolseong-Cheon watershed in Icheon, and the water level and water quality had been monitored for two years at the outlet of the watershed. According to the results of this study, the performance of the simulation using HSPF-MASA-CREAMS-PADDY system was better than others, but they did not show a statistically significant difference. This seemed to be due to the uncertainty of the farming data and the water quality data of the reservoir. Therefore, if accurate input data for the system is obtained, HSPF-MASA-CREAMS-PADDY system could be used to model an agricultural watershed to obtain more realistic results. The results of this study could be utilized to the modeling of agricultural watersheds in Korea where paddy rice cultivation is dominant.

• International Journal of Reliability and Applications
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• v.7 no.1
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• pp.27-39
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• 2006

Many real world cases in material failure analysis do not follow perfectly the normal distribution. Forcing of the normality assumption may lead to inaccurate predictions and poor product quality. We examine the failure process of the internal bond (IB or tensile strength) of medium density fiberboard (MDF). We propose a forced censoring technique that closer fits the lower tails of strength distributions and better estimates extremely smaller percentiles, which may be valuable to continuous quality improvement initiatives. Further analyses are performed to build an accelerated common-shaped Weibull model for different product types using the $JMP^{(R)}$ Survival and Reliability platform. In this paper, a forced censoring technique is implemented for the first time as a software module, using $JMP^{(R)}$ Scripting Language (JSL) to expedite data processing, which is crucial for real-time manufacturing settings. Also, we use JSL to automate the task of fitting an accelerated Weibull model and testing model homogeneity in the shape parameter. Finally, a package script is written to readily provide field engineers customized reporting for model visualization, parameter estimation, and percentile forecasting. Our approach may be more accurate for product conformance evaluation, plus help reduce the cost of destructive testing and data management due to reduced frequency of testing. It may also be valuable for preventing field failure and improved product safety even when destructive testing is not reduced by yielding higher precision intervals at the same confidence level.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.385-390
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• 2005

LMTT (Linear Motor-based Transfer Techn-ology) is a horizontal transfer system for the yard automation, which has been proposed to take the place of AGV (Automated Guided Vehicle) in the maritime container terminal. The system is based on PLMSL (Permanent Magnetic Linear Synchronous Motor) that consists of stator modules on the rail and shuttle car. It is desirable to reduce the weight of LMTT in order to control the electronic devices with minimum energy. In this research, the DACE modeling, known as the one of Kriging interpolation, is introduced to obtain the surrogate approximation model of the structural responses. Then, the GRG(Generalized Reduced Gradient) method built in Excel is adopted to determine the optimum. The objective function is set up as weight. On the contrary, the design variables are considered as transverse, longitudinal and wheel beam's thicknesses, and the constraints are the maximum stresses generated by four loading conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6B
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• pp.575-583
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• 2004

In this paper, we extend the multiple time scale control framework to the window-based congestion control, in particular, such as the TCP. This is performed by interfacing the TCP with a large time scale control module which adjusts the aggressiveness of the bandwidth consumption behavior exhibited by the TCP as a function of large time scale Self-Similar network state. i.e., conformation that exceeds the horizon of the feedback loop as determined by the RTT. How to effectively utilize such an information-due to its probabilistic nature, dispersion over the multiple time scales, and affection on the top of the existing window-based congestion controls-is a non-trivial problem. The evaluation performance of the multiple time scale TCP is facilitated by a simulation of the bench-mark environment which is based on the physical modeling of a self-similar traffic. We explicate our methodology for discerning and evaluating the impact of changes in transport protocols in the protocol stack under the self-similar traffic conditions. We discuss issues arising in the comparative performance evaluation under heavy-tailed workloads.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.4
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• pp.430-439
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• 2011

In this paper, we design a digital predistortion(DPD) for linearity enhancement of RF power amplifier operating in 900 MHz band. We verify improvement of linearity by comparing the proposed DPD using tanh as a nonlinear indexing function and the DPD using linear indexing function based on signal amplitude. The digital predistortion is realized by look-up table(LUT) method, and the Saleh model is employed for power amplifier modeling, then a commercial power amplifier module is used for measurement. The LUT has 256 tables, and the NLMS(Normalized Least Mean Square) algorithm was utilized for an adaptive algorithm for estimation. As a result, we improve the ACLR(Adjacent Channel Leakage Ratio) by around 15 dB.