• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.99-110
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• 1999

Settlement and consolidation time were predicted through systematic soil investigation at the delta of Nakdong river where the preloading method was applied. Field measurements were executed with well-selected instruments. As the results of the comparison, the predicted settlement on the sand layer of about 20m thick underestimated the observed one by 20%. This underestimation was due to the effects of vibration during installation of PBD, creep, the overestimated deformation modulus, and so on. For the clay layer of about 20m in thickness under the sand layer, an ID analysis for underconsolidated soil initially overestimated the observed settlement by 240%. However, when the laboratory compression curve was reconstructed and a conventional ID analysis for NC clay was applied, the re-calculated settlement of the clay layer was relatively similar with the observed one. And the predicted consolidation time was about 45% less than the observed one, because of different influencing factors.

• Wind and Structures
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• v.23 no.2
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• pp.127-142
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• 2016

Aerodynamic effects, such as drag force and flow-induced vibration (FIV), on civil engineering structures can be minimized by optimally modifying the structure shape. This work investigates the turbulent wake of a square prism with its faces modified into a sinusoidal wave along the spanwise direction using three-dimensional large eddy simulation (LES) and particle image velocimetry (PIV) techniques at Reynolds number $Re_{Dm}$ = 16,500-22,000, based on the nominal width ($D_m$) of the prism and free-stream velocity ($U_{\infty}$). Two arrangements are considered: (i) the top and bottom faces of the prism are shaped into the sinusoidal waves (termed as WSP-A), and (ii) the front and rear faces are modified into the sinusoidal waves (WSP-B). The sinusoidal waves have a wavelength of $6D_m$ and an amplitude of $0.15D_m$. It has been found that the wavy faces lead to more three-dimensional free shear layers in the near wake than the flat faces (smooth square prism). As a result, the roll-up of shear layers is postponed. Furthermore, the near-wake vortical structures exhibit dominant periodic variations along the spanwise direction; the minimum (i.e., saddle) and maximum (i.e., node) cross-sections of the modified prisms have narrow and wide wakes, respectively. The wake recirculation bubble of the modified prism is wider and longer, compared with its smooth counterpart, thus resulting in a significant drag reduction and fluctuating lift suppression (up to 8.7% and 78.2%, respectively, for the case of WSP-A). Multiple dominant frequencies of vortex shedding, which are distinct from that of the smooth prism, are detected in the near wake of the wavy prisms. The present study may shed light on the understanding of the underlying physical mechanisms of FIV control, in terms of passive modification of the bluff-body shape.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.6
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• pp.1506-1512
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• 2007

In order to investigate the totale yield, the content of soluble polysaccharide and the others of FEW extract from the yeast fermentated Ganoderma lucidium by supersonic method, the yeast strain was inoculated after pretreatment and subsequently followed fermentation and supersonic extract. The main construction of the extract method is composed of the main glucose and together with the xylose, fucose, galactose and mannose. Results show that because of the generated lactic acid and ethanol, pH value of extract decreases and the safety as well as the preservation is improved. The extract yield, the total soluble polysaccharide, SOD-like activity, cytotoxic effect and growth inhibitory effect against cancer cell line are much higher in FE method than RE method, especially FEW3 extracts fermented during 24hrs. It is concluded that yeast fermentation makes the extract yield increase because of the cell disintegration, the useful ingredients of the germ body, the metabolic products, the insoluble ingredients due to the generation of ethanol, and the cell fragmentation caused by the supersonic waves vibration. Content of generated ethanol, total soluble polysaccharide and extract yield all increase during the fermentation time from 24 to 72 hours and the optimum fermentation condition is at $27^{\circ}C$ for 72 hours. The bitter taste and smell of the Ganoderma lucidium extract is diminished, fragrant-bitter taste and smell is generated so that the whole functional quality is improved.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.260-264
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• 1981

The purpose of the present study is to measure the sound spectrum of the underwater noise generated by a stern trawler M/S Saebada (2,275 GT, 3600 ps) in the various operational conditions. Underwater noises were recorded by a hydrophone (B & K 8100) and analyses were made rising a digital frequency analyzer (B & K 2131) and level recorder (B & K 2370). The predominant frequency range was 100-500 Hz, and maximum sound pressure level was 121 dB(re. $1{\mu}Pa$). Underwater noise level increased with the increased speed of the vessel. Sound pressure level measured in the course of astern cruising was higher than that measured in the course of ahead cruising and also the noise spectrums were different in these two cases. At the time of cruising the underwater noise was higher than 10 dB compared to those values measured at the time at rest with only engine operation. The underwater noise of the vessel was mainly due to the main engine revolution of the propeller and the vibration of hull.

• Advances in aircraft and spacecraft science
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• v.3 no.3
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• pp.243-257
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• 2016

The increase of air traffic volume has brought an increasing amount of issues related to carbon and NOx emissions and noise pollution. Aircraft manufacturers are concentrating their efforts to develop technologies to increase aircraft efficiency and consequently to reduce pollutant discharge and noise emission. Ultra High By-Pass Ratio engine concepts provide reduction of fuel consumption and noise emission thanks to a decrease of the jet velocity exhausting from the engine nozzles. In order to keep same thrust, mass flow and therefore section of fan/nacelle diameter should be increased to compensate velocity reduction. Such feature will lead to close-coupled architectures for engine installation under the wing. A strong jet-wing interaction resulting in a change of turbulent mixing in the aeroacoustic field as well as noise enhancement due to reflection phenomena are therefore expected. On the other hand, pressure fluctuations on the wing as well as on the fuselage represent the forcing loads, which stress panels causing vibrations. Some of these vibrations are re-emitted in the aeroacoustic field as vibration noise, some of them are transmitted in the cockpit as interior noise. In the present work, the interaction between a jet and wing or fuselage is reproduced by a flat surface tangential to an incompressible jet at different radial distances from the nozzle axis. The change in the aerodynamic field due to the presence of the rigid plate was studied by hot wire anemometric measurements, which provided a characterization of mean and fluctuating velocity fields in the jet plume. Pressure fluctuations acting on the flat plate were studied by cavity-mounted microphones which provided point-wise measurements in stream-wise and spanwise directions. Statistical description of velocity and wall pressure fields are determined in terms of Fourier-domain quantities. Scaling laws for pressure auto-spectra and coherence functions are also presented.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.8 no.1
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• pp.5-11
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• 1997

To set up an objective basis for the evaluation of the stroboscopic findings, video-strobolaryngoscopic images of vocal fold vibration in 5 female and 5 male normal speakers were analyzed using an image analysis computer program called KSIP(Kay Storoboscopy Image Processing, Kay Elemetrics Corp., NJ, USA). Four consecutive vibratory cycles were compared in comfortable, louder, high-pitched /ee/ phonation for every subject. findings mostly replicated earlier studies including glottal chinks which were observed in most female speakers throughout the cycles and clear distinction between female and male speakers in their vibratory patterns as well as intensity and frequency-re-lated differences. However, there were some findings incompatible with those from previous studies which may be attributable to technical problems. This study may provide an objective basis of the stroboscopic findings such as image shape, amplitude, area, and their changes according to frequency and intensity variations. We anticipate that funker study with larger samples ran provide an objective criteria for normal vibratory characteristics of the laryngostro-boscopic findings.

• Geomechanics and Engineering
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• v.35 no.2
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• pp.121-133
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• 2023

The demand for cement and limestone crushed materials has increased many folds due to the tremendous increase in construction activities in Pakistan during the past few decades. The number of cement production industries has increased correspondingly, and so the rock-blasting operations at the limestone quarry sites. However, the safety procedures warranted at these sites for the blast-induced ground vibrations (BIGV) have not been adequately developed and/or implemented. Proper prediction and monitoring of BIGV are necessary to ensure the safety of structures in the vicinity of these quarry sites. In this paper, an attempt has been made to predict BIGV using artificial neural network (ANN) at three selected limestone quarries of Pakistan. The ANN has been developed in Python using Keras with sequential model and dense layers. The hyper parameters and neurons in each of the activation layers has been optimized using randomized and grid search method. The input parameters for the model include distance, a maximum charge per delay (MCPD), depth of hole, burden, spacing, and number of blast holes, whereas, peak particle velocity (PPV) is taken as the only output parameter. A total of 110 blast vibrations datasets were recorded from three different limestone quarries. The dataset has been divided into 85% for neural network training, and 15% for testing of the network. A five-layer ANN is trained with Rectified Linear Unit (ReLU) activation function, Adam optimization algorithm with a learning rate of 0.001, and batch size of 32 with the topology of 6-32-32-256-1. The blast datasets were utilized to compare the performance of ANN, multivariate regression analysis (MVRA), and empirical predictors. The performance was evaluated using the coefficient of determination (R²), mean absolute error (MAE), mean squared error (MSE), mean absolute percentage error (MAPE), and root mean squared error (RMSE)for predicted and measured PPV. To determine the relative influence of each parameter on the PPV, sensitivity analyses were performed for all input parameters. The analyses reveal that ANN performs superior than MVRA and other empirical predictors, andthat83% PPV is affected by distance and MCPD while hole depth, number of blast holes, burden and spacing contribute for the remaining 17%. This research provides valuable insights into improving safety measures and ensuring the structural integrity of buildings near limestone quarry sites.

• Tunnel and Underground Space
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• v.34 no.5
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• pp.461-476
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• 2024

As the paradigm of urban development has recently changed to development of underground space, the road tunnels and railway tunnels are increasing to relieve traffic congestion. This technical notes is related to the development of underground spaces using NATM (New Austrian Tunneling Method). Limitations of conventional 2D blasting pattern design method were analyzed, and BIM-based automatic design method was developed to overcome them. Since it was developed to facilitate modeling of all safety facilities along a alignment using coordinates and GIS data, it can overcome the limitations of the number of safety facilities that can be considered and time required for conventional design. In the conventional design, the results of borehole test blasting were used to predict the blasting impact. However, the developed technology is possible to recalculate by applying the measurement results obtained from actual tunnel blasting, enabling rapid re-evaluation of the blasting impact on all safety facilities during construction, leading economical design. As a result of applying it to GTX-A5 and 6 sites, it took about 5 minutes, which is 1/480 compared to the conventional design method. In addition, the construction cost was reduced by about 8 billion won/km and the period was reduced by about 41 days/km. It is expected to be used as technical basis for calculating the optimal blasting pattern in the BIM-based design and construction management process.