• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.461-467
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• 2017

Shrimps infected with WSSV(White Spot Syndrome Virus) generally exhibit white spots in their inner space of carapaces as an acute clinical sign. In an effort to identify the correlation between this acute clinical sign and the condition, the index factors (RNA/DNA concentration and ratio, trypsin activity) were analyzed. A total 580 farmed Fenneropenaeus chinensis and 130 Lithopenaeus vannamei were collected from western and southern fifteen outdoor ponds in Korea. The status of the white spot pathology was divided into four stages (stage 0, stage I, stage II, and stage III), in accordance with the clinical signs as to the size and area of white spots. A significant decrease in RNA concentration and RNA/DNA ratio for multi-infected fleshy prawn (WSSV and vibrio sp.) occurred during the stage III (the whole carapace is covered with a white spot). In particular, RNA/DNA ratio was significantly lower as $1.47{\pm}0.04$ than other groups. A similar trend was also found in the single infection (WSSV), but the decrease was less than the multi-infection. In the species comparison, both species were vulnerable to the multi-infection, but L. vannamei was more sensitive than F. chinensis(ANOVA, p<0.05): A significant decrease in RNA concentration and RNA/DNA ratio was first found in stage II for the former species, while it was found in stage III for the latter species. Trypsin activity was also showed a similar tendency with nucleic acid variation. Multi-infected shrimp showed drastically decrease of trypsin activity. According to the results, clinical signs of the white spot under carapace have an only physiological effect on shrimp if they covered entirely with white spots.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.4
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• pp.7-15
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• 2010

This study proposes a rad o resource management scheme to maximize the performance of the LTE(Long Term Evolution) uplink, using SC-FDMA(Single Carrier-Frequency Division Multiple Access). Rather than the single-cell SC-FDMA system the existing studies are mainly concerning, this study focuses on multi-cell system which needs considering the interaction among cells. Radio resource management is divided into two phases, planning and operation phases. The former is for the master eNB(e-NodeB) to allocate RBs(radio bearer) to eNB, the latter for eNB to assign RBs to the mobiles in the cell. For each phase, an optimization model and greedy algorithm are proposed. Optimization models aim to maximize the system performance while satisfying the constraints for both QoS and RB continuity. The greedy algorithms, like generic ones, move from a solution to a neighboring one having the best objective value among neighboring ones. From the numerous numerical experiments, the performance and characteristics of the algorithms are analyzed. This study is expected to play a volunteering role in radio resource management for the multi-cell SC-FDMA system.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.331-336
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• 2012

This study was aimed at the design of the dies for the guide valve for the fuel pressure regulator using the computer simulation to shorten the period of production, on the basis of the process planning which was designed by the field experts. In the computer simulation, 'Deform-3d' and 'Eesy-DieOpt' have been used, which are the commercial process analysis and die design program. Through the process analysis, we could know the propriety of the forming process, the inner pressure of the die and the suitable fitting pressure between the insert and the sleeve which was not showing any positive tangential stresses in the insert. Through the simulation of die design, we could know the number of the stress ring, the diameter ratios, the stresses of the die, the shrink fitting tolerance and temperature in the condition of the already determined maximum outer die diameter of the multi-stage former. The validity of the die design using the computer simulation was analyzed by the experiments and the results were satisfactory. As the results of this study, the new and easy die design system for multi-forging has been developed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.413-418
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• 2005

Vibration test using the MAST(Multi Axial Simulation Table) is more reliable test than conventional testing process focused on one directional vibration test. The former test could be possible with a advanced control algorithm and hardware supports so that most of the operation is automatically conducted by MAST system itself except the input information that is derived from the measured data. That means the reliability of the vibration test is highly depended on the input profile than any other cases before. In this paper, the optimal algorithm based on energy method is introduced so that the best combination of candidated input PSD data could be constructed. The optimal algorithm renders time information so that the vibration fatigue test is completely possible for any measured signals one wants. The real road test is conducted in short intervals containing some rough roads and the candidated input PSD is obtained from the extra road in proving ground. The testing is targeted for the electronically operated door and seat.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1188-1200
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• 2020

In this paper, we consider a SDMS (Self-Diagnostic Monitoring System) for a reciprocating pump for the purpose of not only diagnosis but also prognosis. We have replaced a multi class estimator that selects only the most probable one with a multi label estimator such that we are able to see the state of each of the components. We have introduced a measure called certainty so that we are able to represent the symptom and its state. We have built a flow loop for a reciprocating pump system and presented some results. With these changes, we are not only able to detect both the dominant symptom as well as others but also to monitor how the degree of severity of each component changes. About the dominant ones, we found that the overall recognition rate of our algorithm is about 99.7% which is slightly better than that of the former SDMS. Also, we are able to see the trend and to make a base to find prognostics to estimate the remaining useful life. With this we hope that we have gone one step closer to the final goal of prognosis of SDMS.

• International Journal of Fluid Machinery and Systems
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• v.7 no.4
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• pp.160-173
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• 2014

Surge phenomena in multi-stage axial flow compressors were studied with attention to the frequency behaviors. A new parameter "volume-modified reduced surge frequency" was introduced, which took into consideration the essential surge process, i.e., emptying and filling of the working gas in the delivery plenum. The behaviors of the relative surge frequencies at the stall stagnation boundaries, compared with the corresponding duct resonance frequencies, have demonstrated the existence of two types of surges; i.e., a near-resonant surge and a subharmonic surge. The former, which has fundamentally a near-resonance frequency, occurs predominantly at the stall stagnation boundary for the short -and-fat plenum delivery flow-path and the long-and-narrow delivery duct flow-path, and possibly in the intermediate conditions. The latter, which has a subharmonic frequency of the fundamental near-resonant one and occurs mainly in the intermediate zone, is considered to be caused by the reduced frequency restricted to a limited range. In relation with those dimensionless frequencies at the stall stagnation boundary, the surge frequency behaviors in more general situations away from the boundaries could be estimated, though very roughly.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.582-588
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• 2011

This study was aimed at the design of the dies for the unified shaft joint using the computer simulation to shorten the period of production, on the basis of the process planning which was designed by the field experts. In the computer simulation, 'Deform-3d' and 'Eesy-DieOpt' have been used, which are the commercial process analysis and die design program. Through the process analysis, we could know the propriety of the forming process, the inner pressure of the die and the suitable fitting pressure between the insert and the sleeve which was not showing any positive tangential stresses in the insert. Through the simulation of die design, we could know the number of the stress ring, the diameter ratios, the stresses of the die, the shrink fitting tolerance and temperature in the condition of the already determined maximum outer die diameter of the multi-stage former. The validity of the die design using the computer simulation was analyzed by the experiments and the results were satisfactory. As the results of this study, the new and easy die design system for multi-forging has been developed.

• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.559-573
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• 2012

An adaptive modeling and simulation technique is introduced for the effective and reliable fluid-structure interaction analysis using MSC/Dytran for large-scale complex pressurized liquid containment. The proposed method is composed of a series of the global rigid sloshing analysis and the locally detailed fluid-structure analysis. The critical time at which the system exhibits the severe liquid sloshing response is sought through the former analysis, while the fluid-structure interaction in the local region of interest at the critical time is analyzed by the latter analysis. Differing from the global coarse model, the local fine model considers not only the complex geometry and flexibility of structure but the effect of internal pressure. The locally detailed FSI problem is solved in terms of multi-material volume fractions and the flow and pressure fields obtained by the global analysis at the critical time are specified as the initial conditions. An in-house program for mapping the global analysis results onto the fine-scale local FSI model is developed. The validity and effectiveness of the proposed method are verified through an illustrative numerical experiment.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.116.2-116.2
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• 2012

The structure of plasmasphere plays an important role in determining properties of geomagnetic ULF pulsations such as Pi 2 pulsations and field line resonances (FLRs) in the Earth's magnetosphere. We have performed a 3-D MHD wave simulation to investigate the generation and propagation of ULF waves in dipole geometry. Various 3-D density structures are assumed, which include a relatively sharp density gradient and gradually less slopes at the plasmapause. The former condition can refer to the plasmasphere from local midnight to dawn, whereas the latter represents the region near noon to dusk where it bulges out. We show how Pi 2 pulsations and FLRs differentially appear at both multi-point satellite locations and ground stations for different local times. Our results suggest that 1) the local radial density structure significantly affects the peak frequencies for Pi 2 oscillations, while the polarization changes remain similar in the radial direction, and 2) the radial location of strong FLRs varies for different density profiles. It is also suggested how multi satellite measurements and ground-based observations can confirm this differential feature in space.

• Structural Engineering and Mechanics
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• v.10 no.6
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• pp.517-532
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• 2000

A direct output feedback control scheme was recently proposed by the authors for single-story building structures resting on flexible soil body. In this paper, the control scheme is extended to mitigate the seismic responses of multi-story buildings. Soil-structure interaction is taken into account in two parts: input at the soil-structure interface/foundation and control algorithm. The former reflects the effect on ground motions and is monitored in real time with accelerometers at foundation. The latter includes the effect on the dynamic characteristics of structures, which is formulated by modifying the classical linear quadratic regulator based on the fundamental mode shape of the soil-structure system. Numerical result on the study of a $\frac{1}{4}$-scale three-story structure, supported by a viscoelastic half-space of soil mass, have demonstrated that the proposed algorithm is robust and very effective in suppressing the earthquake-induced vibration in building structures even supported on a flexible soil mass. Parametric studies are performed to understand how soil damping and flexibility affect the effectiveness of active tendon control. The selection of weighting matrix and effect of soil property uncertainty are investigated in detail for practical applications.