• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.4
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• pp.56-61
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• 2009

This paper presents the ground surface potential profiles and hazard voltages around the metallic structure connected to a small-sized model ground electrode. Because it is very difficult to draw valid conclusions concerning a general grounding problem from actual field data, scale model tests can be used to determine the touch and stop voltages and surface potential profiles around ground electrode. In this work, a hemispherical vessel with a diameter of 1,100[mm] was employed to simulate uniform soil. As a result, the ground surface potential around the ground electrode was significantly raised In particular the ground surface potential at the just upper point of ground rod was higher than other points. When the buried depth of ground rod is increased, the ground surface potential and step voltage were lowered but the touch voltage was elevated.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.345-352
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• 2018

In this study, rainfall data with various temporal scales (3-, 6-, 12-, 24-hr) are disaggregated into 1-hourly rainfall data to evaluate the performance of rainfall disaggregation technique. The rainfall disaggregation technique is based on a database generated by the stochastic point rainfall model, the Neyman-Scott Rectangular Pulse Model (NSRPM). Performance evaluation is carried out using July rainfall data of Ulsan, Changwon, Busan and Milyang weather stations in Korea. As a result, the rainfall disaggregation technique showed excellent performance that can consider not only the major statistics of rainfall but also the spatial correlation. It also indirectly shows the uncertainty of future climate change scenarios with daily temporal scale. The rainfall disaggregation technique is expected to disaggregate the future climate change scenarios, and to be effective in the future watershed management.

• Fire Science and Engineering
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• v.33 no.4
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• pp.41-49
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• 2019

In the present experimental study, based on a real-scale theater, a 1/14 reduced-scale model was constructed, and the effects of natural vent and fire curtain in fire of a theater stage were investigated. The case without fire curtain under the opened natural vent showed lower temperatures in the stage, whereas the case with fire curtain under the opened natural vent showed lower temperatures in the auditorium. On the other hand, through analyzing the starting time of the temperature rise at the point near the proscenium opening in the auditorium, it was found that the opened natural vent condition can delay the starting time of smoke spread from the stage to the auditorium and suppress the temperature rise in the auditorium. Under the present experimental conditions, the fire curtain installation did not affect significantly the velocity and mass flow rate of the outflow through the natural vent of the stage, which might be due to openings in the stage. The present results can be used to examine the effects of natural vent and fire curtain in a real-scale fire of a theater and to check the accuracy of the numerical simulation code.

• Structural Engineering and Mechanics
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• v.40 no.4
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• pp.517-539
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• 2011

This paper presents the seismic responses of a 1:5-scale five-story reinforced concrete building model, which represents a residential apartment building that has a high irregularity of weak story, soft story, and torsion simultaneously at the ground story. The model was subjected to a series of uni- and bi-directional earthquake simulation tests. Analysis of the test results leads to the following conclusions: (1) The model survived the table excitations simulating the design earthquake with the PGA of 0.187 g without any significant damages, though it was not designed against earthquakes; (2) The fundamental mode was the torsion mode. The second and third orthogonal translational modes acted independently while the torsion mode showed a strong correlation with the predominant translational mode; (3) After a significant excursion into inelastic behavior, this correlation disappeared and the maximum torsion and torsion deformation remained almost constant regardless of the intensity of the two orthogonal excitations; And, (4) the lateral resistance and stiffness of the critical columns and wall increased or decreased significantly with the large variation of acting axial forces caused by the high bi-directional overturning moments and rocking phenomena under the bi-directional excitations.

• Composites Research
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• v.36 no.1
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• pp.16-24
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• 2023

This paper presents a multi-scale progressive fatigue damage model incorporating the model for interfacial debonding between fibers and matrix. The micromechanics model for the progressive interface debonding was adopted, which defined the four different interface phases: (1) perfectly bonded fibers; (2) mild imperfect interface; (3) severe imperfect interface; and (4) completely debonded fibers. As the number of cycles increases, the progressive transition from the perfectly bonded state to the completely debonded fiber state occurs. Eshelby's tensor for each imperfect state is calculated by the linear spring model for a damaged interface, and effective elastic properties are obtained using the multi-phase homogenization method. The fatigue damage evolution formulas for fiber, matrix and interface were proposed to demonstrate the fatigue behavior of CFRP laminates under cyclic loading. The material parameters for the fiber/matrix fatigue damage were characterized using the chaotic firefly algorithm. The model was implemented into the UMAT subroutine of ABAQUS, and successfully validated with flat-bar UD laminate specimens ([0]₈,[90]₈, [30]₁₆) of AS4/3501-6 graphite/epoxy composite.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.4 s.304
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• pp.159-166
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• 2005

This thesis deals with a method to deliver more realistic sound by cancelling the cross-talk which is inherent to the 5.1 channel speaker system. First, the cross-talk cancellation method that eliminates cross-talks on the path from left speaker to right ear and from right speaker to left ear is explained. Then the application and replaying method using the cross-talk cancellation explained here is introduced. The acoustical model for cross-talk cancellation is the free field model This model minimizes distortion of sound. Many experts also make studies on this model. I used the bark scale sound quality compensation based on psycho-acoustic. For the surround channels, band-limited sound quality compensation is performed in the frequency domain.

• Journal of Convergence for Information Technology
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• v.12 no.1
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• pp.31-38
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• 2022

This paper applies an expert independent unsupervised neural network learning-based multivariate time series data analysis model, MSCRED(Multi-Scale Convolutional Recurrent Encoder-Decoder), and to overcome the limitation, because the MCRED is based on Auto-encoder model, that train data must not to be contaminated, by using learning data sampling technique, called Subset Sampling Validation. By using the vibration data of power plant equipment that has been labeled, the classification performance of MSCRED is evaluated with the Anomaly Score in many cases, 1) the abnormal data is mixed with the training data 2) when the abnormal data is removed from the training data in case 1. Through this, this paper presents an expert-independent anomaly diagnosis framework that is strong against error data, and presents a concise and accurate solution in various fields of multivariate time series data.

• Journal of Biosystems Engineering
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• v.18 no.3
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• pp.209-219
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• 1993

A series of soil bin experiment was carried out on sand to investigate if true model theory is applicable to blade-soil system and finally to find mathematical relationship between the dimensionless terms which contain the blade-soil parameters. The following conclusions were derived from the study. 1. It was proved that the draft of the prototype blade can be predicted without distortion by those of model blades with the length scale of 1.2, 2 and 2.4. 2. For the sand, bulk density was found to be a good measure of soil physical properties which are pertinent to predict the draft of the blade-soil system. 3. The mathematical relationship between $D/{\gamma}W$ and d/W, ${\beta}$, and $V^2/Wg$ are as follows ; $$\frac{D}{{\gamma}W^3}=124.98[\frac{d}{W}]^2+7.16[\frac{d}{W}]+0.43 \\ \frac{D}{{\gamma}W^3}=-0.00099{\beta}^2+0.13{\beta}-2.01 \\ \frac{D}{{\gamma}W^3}=0.041[\frac{V^2}{Wg}]^2+0.08[\frac{V^2}{Wg}]+1.3$$

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.4
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• pp.1-8
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• 2012

This study is to assess the reduction of non-point source pollution loads for rice straw surface covering of upland crop cultivation at a watershed scale. For Byulmi-cheon watershed ($1.21km^2$) located in the upstream of Gyeongancheon, the HSPF (Hydrological Simulation Program-Fortran), a physically based distributed hydrological model was applied. Before evaluation, the model was calibrated and validated using 9 rainfall events. The Nash-Sutcliffe model efficiency (NSE) for streamflow was 0.62~0.78 and the NSE for water quality (Sediment, T-N, and T-P) were 0.68, 0.60, and 0.58 respectively. From the field experiment of 16 rainfall events, the rice straw covering reduced surface runoff average 10 % compared to normal surface condition. By handling infiltration parameter (INFILT) in the model, the value of 16.0 mm/hr was found to reduce about 10 % reduction of surface runoff. For this condition, the reduction effect of Sediment, T-N, and T-P loads were 87.2, 28.5, and 85.1 % respectively. The rice straw surface covering was effective for removing surface runoff dependent loads such as Sediment and T-P.

• Journal of the Korean Solar Energy Society
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• v.28 no.6
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• pp.78-86
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• 2008

The aim of this paper is to show the daylight environment of a light pipe system according to sun movement. A light pipe system has been mounted on the roof of the windowless full scale model: the solar spot has diameter of 0.65m and is 1.3m long, giving an aspect ratio of 1:2. The full scale model was installed on the rooftop of the SHINAN apartment in Yongin city that has no obstructions against sunlight. The test room is equipped with sensors for the measurements of the internal illuminance and has an area of 6m(W)$\times$6m(D)$\times$4m(H). The system has been monitored with a data-logger to evaluate the cumulative distribution of illuminance on a floor-plane from 16th, April to 29th, May, 2008 over one month and selected clear sky condition. For the daylight performance of floor area, the totally 49 measuring points has been used to determine the internal illuminance and an HP datalogger(HP34970A) records the measurements for one consecutive month. The horizontal external illuminance has been measured with two outdoor sensors. This paper presents the results of monitoring light pipe system with internal/external illuminance ratio and cumulative frequency distribution of floor-plane illuminance are discussed The results show that lightpipe is proficient device for introducing daylight into the building. However It provided different daylight indoor environment with wide or narrow Interquatile range of illuminance, internal/external illuminance ratio and cumulative frequency distribution according to solar positions under suuny sky condition. For more achieving the improvement of lightpipes also include energy savings, user visual comfort with various indicators; seasonal solar height, room and lightpipes geometries.