• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.151-160
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• 2004

In the present study, Loop scheme is applied to generate smooth surfaces. To be consistent with the limit points of target surface, the initial sampling points are properly rearranged. The pointwise errors of curvature and position in the sequence of subdivision process are evaluated in the Loop subdivision scheme. A first-order shear deformable Loop subdivision triangular element which can handle transverse shear deformation of moderately thick shell are developed. The developed element is more general than the previous one based on classical shell theory, since the new one includes the effect of transverse shear deformation and has standard six degrees of freedom per node. The quartic box spline function is used as interpolation basis function. Numerical examples for the benchmark static shell problems are analyzed to assess the performance of the developed subdivision shell element and locking trouble.

• Korean Journal of Veterinary Research
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• v.40 no.2
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• pp.237-245
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• 2000

The regional distribution and relative frequency of somatostatin-immunoreactive cells in the gastrointestinal tract were studied during the postnatal development(1 day old, 1 month old, 6-month-old and adult) of the Korean native goat by immunohistochemical methods. Somatostatin-immunoreactive cells were found in the entire gastrointestinal tract and were most predominant in the fundic gland region except for the pyloric gland region of the 1 day old. The number of these cells was observed to decrease along the gastrointestinal tract and to decrease according to the increase with age in all postnatal stages. In this study, immunoreactive cells revealed the differences of regional distribution and the relative frequency in the gastrointestinal tract during postnatal development. These results suggest that although the functional significance of fetal endocrine cells remains unknown, this was caused by changing of feeding habits and physiological conditions during different ages.

• The Transactions of the Korea Information Processing Society
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• v.3 no.2
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• pp.339-347
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• 1996

object-oriented programming is used to develop next-generation telecommu- nications services running on the distributed processing environment. In order to test these services efficiently at the system-level during not only in the development phase but also in the operation phase, we define an embedded monitor service within the infrastructure to monitor the operation of the distributed programs, and describe a system-level test mechanism based on the monitor service. By separating the function of monitor server which monitors operations of objects and collects monitored data and that of tester which makes analysis and decides the sequence of test events, the invasive effect of monitoring can be minimized. At the same time, accurate diagnosis on the system can be achieve by exploiting the test mechanism. The mechanism, as a core component for the implementation of real-time fault-tol-erant systems, is applicable to general-purpose distributeded systems as well.

• Journal of Korean Association for Spatial Structures
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• v.5 no.3 s.17
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• pp.65-74
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• 2005

An analytical model was developed to investigate the flexural behavior of a pultruded fiber-reinforced plastic deck of rectangular unit module. The model is based on first-order shea. deformable plate theory (FSDT), and capable of predicting deflection of the deck of arbitrary laminate stacking sequences. To formulate tile problem, two-dimensional plate finite element method is employed. Numerical results are obtained for FRP decks under uniformly-distributed loading, addressing the effects of fiber angle and span-to-height ratio. It is found that the present analytical model is accurate and efficient for solving flexural behavior of FRP decks. Also, as the height of FRP deck plate is higher, the necessity of higher order Shear deformable plate theory(HSDT) is announced, not the FSDT in the plate analysis theory.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1177-1184
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• 2011

Gas-to-Solid (GTS) technology is composed of three stages: hydrate production, transportation, and regasification. For efficient operation of regasification plants, it is crucial to predict the temperature and flow rate of hot water necessary to dissociate the hydrate pellets. Dissociated gas escaping from the pellet surface, when in contact with hot water, will alter the flow field and consequently alter the heat transfer rate. Methane hydrate pellet dissociation characteristics in low- to moderatetemperature water were investigated by taking images of the changes in the hydrate pellets' shapes in a pressurized reactor and measuring the total time required for complete melting of the pellets. The effects of water temperature, hydrate conversion rate, and flow speed on the dissociation completion time were also investigated. Bubbling gas released from the pellet surface induced a secondary flow that enhanced the heat transfer rate and thus decreased the dissociation time. It was also found that a considerable flow rate was needed to significantly decrease the dissociation time.

• Computational Structural Engineering
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• v.9 no.2
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• pp.121-131
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• 1996

This work proposes an optimality criteria applicable to the optimum design of plane frames subject to multiple behavioral constraints on member stresses and lateral displacements of nodes and also to side constraints on design variables. The method makes use of a first order approximation for both deflection and stress constraints instead of the zero order approximation based on the concept of FSD (fully stressed design). A redesign algorithm is derived from a mathematically rigorous method which uses the Newton-Raphson method to solve the system of nonlinear constraint equations and reduces the design space whenever minimum size restrictions become active. When applied to worked examples it proved more accurate and efficient, and it is often found that optimum designs are not fully stressed designs. This fact suggests that this rigorous method is worth what it claims for complicated computing and thus had better replace the crude stress ratio algorithm adopted by the majority of optimality criteria approaches. This is particularly true as long as we enjoy ever-increasing computing power at negligible costs.

• Journal of the Korean Geophysical Society
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• v.2 no.1
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• pp.57-64
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• 1999

To effectively identify near-surface faults with vertical slips from seismic refraction data, the GRM interpretation technique is tested and investigated in terms of various parameters through computer modeling. A characteristic change in shape of the velocity-analysis function near faults is noticed, and a new strategy of `Slope Variation Indicator (SVI)' is developed and tested in this study. The SVI is defined as a first horizontal derivative of the difference of velocity analysis functions for a large XY value and a small one, respectively. As the dip of refractor decreases and as the difference in XY value increases, the peak value of SVI increases and its duration decreases. Consequently, the SVI indicates accurately the location of buried fault in the test models. The SVI is believed to be an efficient tool in seismic refraction method to investigate location and distribution of shallowly buried faults.

• Geophysics and Geophysical Exploration
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• v.14 no.3
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• pp.203-213
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• 2011

Time-lapse seismic surveys make repeated seismic surveys at different stages of oil production of a hydrocarbon reservoir to monitor changes in reservoir like fluid saturation. Since the repeatable surface seismic measurements can identify fluid types and map fluid saturations, oil and gas companies can make much more informed decision during not only production but also drilling and development. If time-lapse seismic surveys compare 3D seismic surveys, the time-lapse surveys are widely called as 4D seismic. A meaningful time-lapse interpretation is based on the repeatability of seismic surveys, which mainly depends on improved positioning and reduced noise (if surveys were designed properly through a feasibility study). The time-lapse interpretation can help oil and gas companies to maximize oil and gas recovery. This paper discusses about time-lapse seismic surveys mainly focused on feasibility, repeatability, data processing and interpretation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.8
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• pp.521-529
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• 2017

Three-dimensional flow characteristics within a high-acceleration first-stage turbine vane passage has been investigated in a newly-built vane cascade for propulsion. The result shows that there is a strong favorable pressure gradient on the vane pressure surface. On its suction surface, however, there exists not only a much stronger favorable pressure gradient than that on the pressure surface upstream of the mid-chord but also a subsequent adverse pressure gradient downstream of it. By employing two different oil-film methods with upstream coating and full-coverage coating, a four-vortex model horseshoe vortex system can be identified ahead of each leading edge in the cascade, and the separation line of inlet boundary layer flow as well as the separation line of re-attached flow is provided as well. In addition, basic flow data such as secondary flow, aerodynamic loss, and flow turning angle downstream of the cascade are obtained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.1
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• pp.9-14
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• 1999

One of the IIDSt difficult problems in a tri-band fluorescent lamp manufacture is to search a desired color by an adequate mixing of tri-color phosphors. When a light spectrum of a phosphor is slightly changw or distorted due to process variable or when another spectrum such as from Ar, Kr or a iDosphor of calcium halo-phosphate as a first layer exist, it is even rrnre difficult to search a desired color. In this work, a rapid awuaching rrethod to a desired light color was studied. 1bree single-color fluorescent lamps and three-color-mixed fluorescent lamps with different mixing ratios were prepared and the spectra of these lamps were measured, from which the rrercury and the argon spectra were eliminatffl to obtain the rrndifiw color coordinates. From this rrndifiw color coordinate, h.lIlHl ratios of green and blue to red were correlatffl with their weight ratios. This correlation was awliw to the industrial line for single and double layer coating and proven to be valuable as a desired color matching procWure in tri-color fluorescent lamp manufacture.acture.