• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.671-680
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• 2009

We performed a study to obtain kinematic data on the characteristics of spike serving techniques used by volleyball players, including other basic data that will be useful for in-field applications. We used three-dimensional videography to compare good tough serves and serve errors. The subjects were 3 left attackers whose spike serves were videographed (60 fileds/s). The three-dimensional coordinates were calculated using the direct linear transformation method and then analyzed using the Kwon 3D software program version 3.1. There was no difference in time elapsed. However, the vertical displacement of the center of body mass(CM) differed between the 2 types of serves: in successful serves, the CM tended to be lower, as did the maximum ball height at the time of hitting. Further, the higher the level of the hitting hand was at the moment of impact, the higher was the likelihood of scoring points. In good serves, the players tended to accelerate their CM movement just before jumping to hit the ball and descend rapidly at the moment of hitting. The hand speed along with ball velocity during the impact was proven to be higher in successful serves. Moreover, in successful serves, the shoulder angles increased to a greater extent while the elbow angles were maintained constant. This possibly resulted in faster and more precise serves. An important observation was that the angle of trunk inclination during the jump did not increase with the swing of the shoulders, muscle tendon complex.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.11
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• pp.1349-1354
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• 2013

Sealing structure to prevent flowing hot gas into the driving device, located between the driving shaft and the liner of On-Off valve for controlling the hot gas flow path was studied. Wear occurs due to the constant movement of the driving shaft controlled by actuator on graphite as the sealing material. In this paper, the dynamic wear behavior in high temperature of graphite(HK-6) to be used as sealing material was evaluated. Reciprocating wear test was carried out for the graphite(HK-6) to the relative motion between shaft materials(W-25Re). The results of friction coefficient and specific wear rate according to contact load, sliding speed at room temperature and $485^{\circ}C$ considering the actual operating environment were evaluated. Through the SEM analysis of the worn surface, third body as lubricant films were observed and lubricant effect of third body was considered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.464-473
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• 2016

The air temperatures of the coast and inland are rising due to an increase in carbon dioxide emissions and abnormal climate phenomena caused by global warming, El Nino, La Nina and so on. The sea levels of the Earth are rising by approximately 2.0 mm per year (global average value) due to the thermal expansion of sea water, melting of glaciers and other causes by global warming. On the other hand, when it comes to designing a hydraulic structure or coastal hydraulic structure, the standard of the design water level is decided by analyzing four largeness tide values and a harmonic constant with the observed tidal water level or simulating numerical model. Therefore, the design tidal water level needs to consider an increasing speed of the seawater level, which corresponds to the design frequency. In the present study, the observed tidal water levels targeting 46 tidal stations operated by the Korea Hydrographic and Oceanographic Administration (KHOA) from the beginning of observations to 2015 per hour were collected. The variation of the monthly and yearly and increasing ratio were performed and divided into 7 seas, such as east and west part of the Southern Sea, south part and middle of the East Sea, south part and middle of the Western Sea, and Jeju Sea. The current study could be used to determine the cause of local seawater rises and reflect the design tidal water level as basic data.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.234-240
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• 2017

In this study, the influences of rail surface roughness on dynamic wheel-rail forces currently employed in conventional lines were assessed by performing field measurements according to grinding of rail surface roughness. The influence of the grinding effect was evaluated using a previous empirical prediction model for dynamic wheel-rail forces; model includes first-order derivatives of QI (Quality Index) and vehicle velocity. The theoretical dynamic wheel-rail force determined using the previous prediction equation was analyzed using the QI, which decreased due to rail grinding as determined through field measurements. At a constant track support stiffness, an increase in the QI caused an increase in dynamic wheel-rail forces. Further, it can be inferred that the results of dynamic wheel-rail analysis obtained using the measured data, such as the variation of QI due to rail grinding, can be used to predict the peak dynamic forces. Therefore, it is obvious that the optimum amount of rail grinding can be determined by considering the QI, that was regarding an operation characteristics of the target track (vehicle velocity and wheel load).

• Korean Journal of Optics and Photonics
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• v.28 no.1
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• pp.9-15
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• 2017

We precisely measured and analyzed the dynamics of peptide-antibody interactions, using an ellipsometric biosensor based on a silicon substrate. To reduce the signal error due to the imperfect flatness of the substrate for extremely low concentrations of peptide, we fabricated the biosensor with a silicon substrate coated with Dextran SAM, instead of a glass prism coated with a thin metallic thin film. At an injection speed of $100{\mu}l/min$ of buffer liquid, we detected the dynamics of antibody-Dextran SAM or peptide-antibody fixed on biosensor, respectively. We detected the dynamics of antibody-Dextran SAM interactions down to a low concentration of 5 ng per liter, and we precisely measured the dynamics of association and dissociation of peptide and antibody down to 100 nM of peptide. We obtained the rate constants for association and dissociation from fitting the data by using deduced dynamical equation. As a result, we obtained an equilibrium constant for dissociation of 97 nM of peptide-antibody complex, which belongs to Class I.

• Korean Journal of Plant Resources
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• v.20 no.4
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• pp.267-271
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• 2007

This study was carried out to examine optimal hot water treatment time in Albizzia julibrissin seeds. Germination and moisture absorption characteristics among intact seeds, immersed seeds for 24 hours in distilled water and hot water treated seeds were surveyed. As result, treated seeds showed a highly significant difference with intact and immersed seeds (p<0.0l). Especially, treated seed for 2.0 minutes represented the highest percent of germination (PG). But mean germination time (MGT) did not have significant difference between non-treatment and treatments (p=0.502). Germination speed and germination performance index showed similar tendency with PG. In percent of moisture absorption (PMA) and moisture absorption rate constant (MARC) treatments had higher values than non-treatment whereas 2.0 minutes treatment was lower than non-treatment in initial moisture absorption rate (IMAR). In relation between germination properties and moisture absorption characteristics, all properties except MGT among germination properties had high correlations with PMA and MARC ($r=0.854{\sim}0.931$,p<0.01) whereas IMAR didn't have correlation.

• Atmosphere
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• v.16 no.2
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• pp.97-110
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• 2006

This study investigates the response of a typhoon model to the change of the sea surface temperature (SST) throughout the model integration. The SST change is parameterized as a formulae of which the magnitude is given as a function of not only the intensity and the size but the moving speed of tropical cyclone. The formulae is constructed by referring to many previous observational and numerical studies on the SST cooling with the passage of tropical cyclones. Since the parameterized cooling formulae is based on the mathematical expression, the resemblance between the prescribed SST cooling and the observed one during the period of the numerical experiment is not complete nor satisfactory. The agreements between the prescribed and the observed SST even over the swath of the typhoon passage differ from case to case. Numerical experiments are undertaken with and without prescribing the SST cooling. The results with the SST cooling do not show clear evidence in improving the track prediction compared to those of the without-experiments. SST cooling in the model shows its swath along the incomplete simulated track so that the magnitude and the distribution of the sea surface cooling does not resemble completely with the observed one. However, we have observed a little improvement in the intensity prediction in terms of the central pressure of the tropical cyclone in some cases. In case where the model without the SST treatment is not able to yield a correct prediction of the filling of the tropical cyclone especially in the decaying stage, the pulling effect given by the SST cooling alleviates the over-deepening of the model so that the central pressure approaches toward the observed value. However, the opposite case when the SST treatment makes the prediction worse may also be possible. In general when the sea surface temperature is reduced, the amount of the sensible and the latent heat from the ocean surface become also reduced, which results in the weakening of the storms comparing to the constant SST case. It turns out to be the case also in our experiments. The weakening is realized in the central pressure, maximum wind, horizontal temperature gradient, etc.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.101-106
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• 2016

This paper proposes the SU-SE-MMA algorithm which applying the concept of selective updaing to the SE-MMA that is possible to reduce the intersymbol interference due to distortion occurred at the channel when transmit the nonconstant modulus 16-QAM signal. The SE-MMA emerged for the simplifying the computational operation from the current MMA adaptation algorithm, then it's has the fast convergence speed and has a problem of increase the residual component in the steady state. The SU-SE-MMA performs the selectively tap updating when the distance of equalizer output and specified transmit signal point is greater than the given threshold value and tap updaing does not occurred in the small distance. By this selective updating process, it is possible to more reduction in the computational operation in the propose algorithm. The improved adaptive equalization performance of SU-SE-MMA like as the equalizer output signal constellation, residual isi, MD, SER were confirmed by computer simulation compared to SE-MMA. As a result of simulation, the AV-SE-MMA has better performance in output signal constellation, residual isi and MD compared to the SE-MMA, but it was confirmed that the AV-SE-MMA has similar in the SER performance that means the robustness to the noise.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.931-938
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• 2005

When concrete structures are exposed under marine condition for a long time, the steel in concrete is corroded due to the ingression of chlorides in the seawater. Because the damages of corrosion resulting from the chloride ion are very serious, many researches have been performed. Silver nitrate colormetric method that can measure easily penetration depth of chloride ion has been executed, recent)y. However, characteristics of silver nitrate colormetric method were not fully examined. Therefore, the objective of this paper Is to study the applicability of colormetric method. For the purpose of this, effect factors and reaction mechanism of colormetric method were investigated, and the colormetric method is applied for marine concrete structures. According to the results of silver nitrate colored method, two reactions such as white reaction of AgCl and brown reaction of AgOH were shown when $AgNO_3$ was sprayed in splited section. And velocity constant ratio(K) of two reactions appeared that white reaction, AgCl reacts with the fast speed by 3240. When the colormetric method was applied in concrete, it is reasonable that $AgNO_3$ solution more than 0.05N concentration was sprayed. It is confirmed that the colormetric method is useful tool for estimating the chloride of concrete structures in situ. The average chloride amount of colored parts indicates $0.9kg/m^3$ per concrete unit weight.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.62-62
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• 2008

As micro-system move toward higher speed and miniaturization, requirements for embedding the passive components into printed circuit boards (PCBs) grow consistently. They should be fabricated in smaller size with maintaining and even improving the overall performance. Miniaturization potential steps from the replacement of surface-mount components and the subsequent reduction of the required wiring-board real estate. Among the embedded passive components, capacitors are most widely studied because they are the major components in terms of size and number. Embedding of passive components such as capacitors into polymer-based PCB is becoming an important strategy for electronics miniaturization, device reliability, and manufacturing cost reduction Now days, the dielectric films deposited directly on the polymer substrate are also studied widely. The processing temperature below $200^{\circ}C$ is required for polymer substrates. For a low temperature deposition, bismuth-based pyrochlore materials are known as promising candidate for capacitor $B_2Mg_{2/3}Nb_{4/3}O_7$ ($B_2MN$) multi layers were deposited on Pt/$TiO_2/SiO_2$/Si substrates by radio frequency magnetron sputtering system at room temperature. The physical and structural properties of them are investigated by SEM, AFM, TEM, XPS. The dielectric properties of MIM structured capacitors were evaluated by impedance analyzer (Agilent HP4194A). The leakage current characteristics of MIM structured capacitor were measured by semiconductor parameter analysis (Agilent HP4145B). 200 nm-thick $B_2MN$ muti layer were deposited at room temperature had capacitance density about $1{\mu}F/cm^2$ at 100kHz, dissipation factor of < 1% and dielectric constant of > 100 at 100kHz.