• Journal of Korean Port Research
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• v.7 no.1
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• pp.79-88
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• 1993

This study deals with the case of a fixed floating structure(FFS) at the mouth of a rectangular harbor under the action of waves represented by the linear wave theory. Modified forms of the mild-slope equation is applied to the propagation of regular wave over constant water depth. The model is extended to include bottom friction and boundary absorption. A hybrid element approximation is used for calculation of linear wave oscillation in and near coastal harbor. Modification of the model was necessary for the FFS. For the conditions tested, the results of laboratory experiments by Ippen and Goda(1963), and Lee (1969) are compared with the calculated one from this model. The cases of flat cylinderical structures, both fixed and floating, were taken to be in an intermediate water depth.

• Bulletin of the Society of Naval Architects of Korea
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• v.17 no.4
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• pp.13-20
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• 1980

The integral equation method to solve the boundary-value problem of a 2-dimensional body oscillating in the presence of a free surface generally breaks down at and near irregular frequencies due to the hypothetical flow inside the body. In this paper singularity distributions were extended to an inner free surface to remove the irregular frequency as Ohmatsu's work in 1978, and the solution for the above problem was found by using stream function. For various bodies including Lewis form cylinders, the hydrodynamic forces were calculated numerically at various wave numbers. From the results we concluded that the irregular frequencies can be removed even for the Lewis form cylinder as Ohmatsu done for circular cylinders, and calculated hydrodynamic forces by the present method are little higher than those of Ohmatsu's when the singularities are put on the inner free surface of the body. We specially point out that the solution for heaving motion converges in an oscillatory manner but not for swaying and rolling motions.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.31-35
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• 2006

The delta-formulation of the Navier-Stokes equations has been popularly used in the aerodynamics area. Implicit algorithm can be easily implemented in that by using Taylor series expansion. This formulation is extended for an unsteady analysis by using a dual-time integration. In the meanwhile, the incompressible flows with heat transfers which occur in the area of thermo-hydraulics have been solved by a segregated algorithm such as the SIMPLE method, where each equation is discretised by using an under-relaxed deferred correction method and solved sequentially. In this study, the dual-time delta formulation is implemented in the segregated Navier-Stokes solver which is based on the collocated cell-centerd scheme with un unstructured mesh FVM. The pressure correction equation is derived by the SIMPLE method. From this study, it was found that the Euler dual-time method in the delta formulation can be combined with the SIMPLE method.

• Journal of the Korean Geophysical Society
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• v.9 no.3
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• pp.199-207
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• 2006

Fukuoka earthquake on March 20, 2005 showed the potential hazard of large events out of S. Korea. From the viewpoint of seismic hazard, seismic amplitude decrease Q-1 is very important. Related to the crustal cracks induced by the earthquakes, the value of Q-1- high Q-1 regions are more attenuating than low Q-1 regions - shows a correlation with seismic activity; relatively higher values of Q-1 have been observed in seismically active areas than in stable areas. For the southeastern and central S. Korea, we first simultaneously estimated QP-1 and QS-1 by applying the extended coda-normalization method to KIGAM and KNUE network data. Estimated QP-1 and QS-1 values are 0.009 f-1.05 and 0.004 f-0.70 for southeastern S. Korea and 0.003 f -0.54 and 0.003 f -0.42 for central S. Korea, respectively. These values agree with those of seismically inactive regions such as shield. The low QLg-1 value, 0.0018f -0.54 was also obtained by the coda normalization method. In addition, we studied QLg-1 by applying the source pair/receiver pair (SPRP) method to both domestic and far-regional events. The obtained QLg-1 for all Fc is less than 0.002, which is reasonable value for a seismically inactive region.

• Wind and Structures
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• v.12 no.1
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• pp.49-61
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• 2009

A method is presented to estimate the form drag and the base pressure on a triangular cylinder in the presence of blockage effect. The Strouhal number, which is found to increase with the flow constriction experimentally by Ramamurthy & Ng (1973), may be decoupled from the blockage effect when re-defined by using the velocity at flow separation and a theoretical wake width. By incorporating this wake width into the momentum equation by Maskell (1963) for the confined flow, a relationship between the form drag and the base pressure is derived. Independently, the experimental data of surface pressure from Ramamurthy & Lee (1973) are found to be independent of the blockage effect when expressed in terms of a modified pressure coefficient involving the pressure at separation. Using the potential flow model by Parkinson & Jandali (1970) and its subsequent development in Yeung & Parkinson (2000) for the unconfined flow, a linear relation between the pressure at separation and the form drag is formulated. By solving the two equations simultaneously with a specified blockage ratio and an apex angle of the triangular cylinder, the predictions of the drag and the base pressure are in reasonable agreement with experimental data. A new theoretical relationship for the Strouhal number, pressure drag coefficient and base pressure proposed in this study allows the confinement effect to be appropriately taken into consideration. The present approach may be extended to three-dimensional bluff bodies.

• Electronics and Telecommunications Trends
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• v.33 no.5
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• pp.103-110
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• 2018

Studies on artificial intelligence have been developed for the past couple of decades. After a few periods of prosperity and recession, a new machine learning method, so-called Deep Learning, has been introduced. This is the result of high-quality big- data, an increase in computing power, and the development of new algorithms. The main targets for deep learning are 1D audio and 2D images. The application domain is being extended from a discriminative model, such as classification/segmentation, to a generative model. Currently, deep learning is used for processing 3D data. However, unlike 2D, it is not easy to acquire 3D learning data. Although low-cost 3D data acquisition sensors have become more popular owing to advances in 3D vision technology, the generation/acquisition of 3D data remains a very difficult problem. Moreover, it is not easy to directly apply an existing network model, such as a convolution network, owing to the variety of 3D data representations. In this paper, we summarize the 3D deep learning technology that have started to be developed within the last 2 years.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.4
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• pp.494-498
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• 2008

MTT (3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) reduction assay is a method that validates the viability of an active cell. Dehydrogenase in mitochondria converts yellow colored insoluble tetrazolium salt to purple colored water-soluble formazan. Sperm also have mitochondria in the midpiece, therefore sperm viability could be evaluated by MTT reduction assay. Several studies have already demonstrated the capability of application of the MTT reduction assay to sperm of several species in Hepes-BSA buffer. Because most liquid semen was diluted in extender like BTS (Beltsville Thawing Solution), Modena or Androhep when it is used or transferred, semen needed another dilution in Hepes-BSA buffer to assess sperm viability. In this study, we evaluated boar sperm viability especially in BTS extended semen and compared the efficiency of this test with eosin-nigrosin staining. We used the fresh BTS extended semen from a local A.I center. Semen sample was diluted to $3.0{\times}10^7$ sperms/ml in BTS. The rates of formazan production were measured in 96-well microtiter plates immediately and 1h after incubation at $17^{\circ}C$ using a spectrophotometer at wave length 560 nm. Simultaneously, split samples of the same semen were tested, using eosin-nigrosin staining to compare the efficiency of the MTT assay of sperm viability in BTS. The correlation between the results of these tests was calculated using Student-t test and ANOVA. The results revealed a strong correlation between the results of MTT reduction rate and the results that were simultaneously determined by eosin-nigrosin staining at 1 h. In conclusion, the MTT reduction test was an effective and simple method to validate sperm viability and it could be used as a simple tool to evaluate sperm viability in the local A.I center and laboratory.

• International Journal of Automotive Technology
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• v.6 no.1
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• pp.71-77
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• 2005

This paper presents a systematic approach which determines the optimal period to minimize performance measure subject to the schedulability constraints of a real-time control system by formulating the scheduling problem as an optimal problem. The performance measure is derived from the summation of end-to-end response times of processed I/Os scheduled by the static cyclic method. The schedulability constraint is specified in terms of allowable resource utilization. At first, a uniprocessor case is considered and then it is extended to a distributed system connected through a communication link, local-inter network, UN. This approach is applied to the design of an automotive body control system in order to validate the feasibility through a real example. By using the approach, a set of optimal periods can easily be obtained without complex and advanced methods such as branch and bound (B&B) or simulated annealing.

• Management Science and Financial Engineering
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• v.16 no.3
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• pp.21-47
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• 2010

Quantity discounts provide a practical foundation for supply chain inventory policies, improving the supplier's profit and reducing the buyer's inventory cost simultaneously. Traditional quantity-discount research, which deals with inventory coordination between a buyer and a supplier, is extended to a stationary stochastic environment. This research shows that the magnitude of the optimal discounts scheduled by the deterministic quantity discount models may not be large enough to cover the buyer's additional inventory stocking risks under uncertain conditions. As a result, the buyer's total inventory cost may often increase rather than decrease. In contrast, the proposed model allows the supplier to identify the discount level, which shares the buyer's amplified risk associated with temporary overstocking and ensures that both buyer and supplier benefit economically. The performance of the proposed model was tested in the continuous review environments via numerical experiments. The experimental results support the proposed method as a feasible alternative in coordinating inventory decisions under stochastic demand.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.638-641
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• 2002

This paper presents design and construct of flat type step-down piezoelectric transformer for the application to AC-adapters. This piezoelectric transformer operated in resonance vibration mode. In this paper, Finite element method(FEM) was used for analysis piezoelectric transformers. Vibration mode and electric field of piezoelectric transformer at resonance frequency were simulated. Using this simulation, we manufactured flat type piezoelecric transformer and measured its output characteristics. As results, output power was linearly increased by increasing input power at resonance frequency. And it was found that the transformer exhibited an output power of 11.4[W] at 60[V] input voltage. From these results, we expect that this piezoelecric transformer can be applied to AC adapters.