• Korean Journal of Medicinal Crop Science
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• v.18 no.1
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• pp.46-50
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• 2010

In order to development medicinal Artemisia herbs of high quality, Korean A. annua L. were investigated with its ecological and morphological characteristics, and basic statistical data of agronomic characteristics. This species, which is annual herb, is mainly distributed to marginal land, riverside, roadside, grassland. Ecological niche is low species in competition of the others. Its pollination is basically anemogamous, but is frequency pollinated by insects. This species is characterized as tap root, 1~3 pinnate compound leaf of ovate or narrowly ovate, stem is green, erect and solitary. Inflorescence is paniculate, receptacle is not hair. Capitulum, consist of ray floret and disk floret, is subglobose shape. Additionally, this species could be easily discriminated from related Artemisia herbs by the capitulum size. Ray floret is female, disk floret is bisexual. Flowering season is from August to October. Seed is achene unattached hair. Stem length ranged from 179 cm to 225 cm, and stem diameter and number of branch were $17.14\;{\pm}\;1.68\;mm$, $2.43\;{\pm}\;0.51\;mm$, respectively. Length and width of leaf were $14.5\;{\pm}\;0.5\;cm$, $15.0\;{\pm}\;1.0\;cm$, and leaf number of main stem were $48.06\;{\pm}\;10.57\;cm$, respectively. Fresh weight of aerial parts and root were $364.7\;{\pm}\;14.1\;g$, $32.6\;{\pm}\;5.1\;g$, and its dry weight were $136.6\;{\pm}\;10.0\;g$, $14.9\;{\pm}\;2.34\;g$, respectively.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.213-217
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• 1997

AOhf(Hcousto-r)l)tic niodulator) with :!OOlIiz freclucncl- and Sfi(;(Seconrl harmonic generation) green lasel-Lvith 53% nm wavelength were used for Il\'IIII~Dii.it,ii v~ilco disk recorder) FOI rhe appli~aptin of high densit]. optical recording, a high po\ver I ~ c r is r c ~ ~ l i ~ i l - u l ic I !tic. s\-sti,m a n d optic.,~I io;iting l,t)c>rs of each optical device must have a high laser damage threshoid hie rn;itie ant] retlwtive coatings on a $TeO_{2}$ singlc crystal. which is used as an acoustooptic material, by E-beam evaporation method. Laser damage threshold \vas nicdsureci hy Ar laser with the input power oi 0.55LV 1,aser damage threiholti 01 $ZrO_{2}$ and $SiO_{2}$. filn-is were higher than $AI_{2}O_{3}$ f i l m U'e also investigated a long--tern1 stability of the output po\ver of St{(; green laser

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.11 s.104
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• pp.1276-1286
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• 2005

In this paper, the dual stage interaction between the coarse actuator and the fine actuator of an optical disk drive is studied, and the new control method to enhance the track pull-in performance using fine actuator control is proposed. First, the dynamic analysis for the dual stage and the experiments to find the each actuator dynamics are performed. From the experiments, some physical parameters of the actuators were derived, then, some simulations are performed to find the interaction effect of the fine actuator during seek motion. Second, the center servo which suppresses the vibration of fine actuator during seek motion is designed and evaluated. And the fine actuator control to reduce the relative velocity between the target track and beam spot is proposed. From simulations, we show that fine actuator control which has same frequency and same phase of the disturbance is effective to reduce the relative velocity, and this result leads to track pull-in enhancement. Hence, the proposed control method is good approach to improve the track pull-in performance. Finally, the realization of the proposed method and some comments of it are briefly discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.11
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• pp.1043-1049
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• 2007

Data transfer rate and storage capacity are main criteria of the performance of the optical disk drive. The highest data transfer rate and the largest storage capacity is most desirable. To increase these performances, the actuator of the optical disk drive should have a high servo bandwidth to compensate the vibration of an optical disk. The servo bandwidth is limited by some flexible modes of the actuator, thus it is essential to increase the natural frequencies of the flexible modes. In this paper, we suggested a moving magnet type actuator having high frequencies of the flexible modes. Generally, the moving magnet type actuator has an advantage to increase the natural frequencies of the flexible modes because the moving magnet type actuator has simple structure and the Young's modulus of magnet is high. However, large moving mass and inefficiency of EM(electromagnetic) circuit cut down driving sensitivities of the actuator. To improve driving sensitivities, we designed the model with the closed electromagnetic circuit for tracking direction. In addition, driving sensitivities and the natural frequencies of the flexible modes were improved by using DOE(design of experiments) for electromagnetic circuit and modifying the lens holder.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11
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• pp.2954-2964
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• 1999

In this paper, we propose the model to measure and compare the performances of the Linux, PC_Solaris and FreeBSD which are the heterogeneous PC based UNIX kernels connected by network. Using the stop-watch timer with the $mutextrm{s}$ unit, we measure the important performance indices of UNIX kernels which are the primitive and command execution time and disk I/O time. Also we measure the message transfer time using the TCP, UDP and RPC methods to compare the network performance of UNIX kernels. And we compare the performance of NFS for each UNIX kernels. And we display the measured data on internet.

• International Journal of Ocean System Engineering
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• v.2 no.4
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• pp.244-249
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• 2012

In this study, a monolithic MoSi2 matrix reinforced with 20 vol% SiC particles, a SiC/MoSi2 composite matrix reinforced with 20 vol% ZrO2 particles, and a ZrO2/MoSi2 composite were fabricated using hot press sintering at $1350^{\circ}C$ for 1 h under a pressure of 30 MPa. The Vickers hardness and sliding wear resistance of the monolithic MoSi2, ZrO2/MoSi2, and SiC/MoSi2 composite were investigated at room temperature. A wear behavior test was carried out using a disk-type wear tester with a silicon nitride ball. The ZrO2/MoSi2 composite showed an average Vickers hardness value and excellent wear resistance compared with the monolithic MoSi2 and SiC/MoSi2 composite at room temperature.

• Tribology and Lubricants
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• v.27 no.4
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• pp.204-208
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• 2011

Yaw brakes are used in wind turbines to control the orientation of blades to be perpendicular to the wind. These devices are very important machine elements because they are closely related to the overall efficiency of wind turbines. One unit of yaw brakes is composed of a friction pad and a caliper. In this study, a tangential force between the friction pad and the disk is calculated when the brake is acting in 750 kW wind turbine. Then, stress distribution and the deformation of the caliper are calculated using a finite element analysis. An experimental equipment is also developed to verify the exactness of calculated results. The analytical and experimental results are presented and discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.128-133
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• 2002

The main obstacle to high track density in HDD is the structural resonances of the suspension. The most critical mode is sway mode and second torsion mode, when a data is read and written. It is common fact that the effect of two modes is smaller when a thickness is bulky. But the stiffness of suspension is smaller, the slider can follow a disk better. Because these two fact are reciprocal, a compromise is needed. So we investigated another method to improve band width without changing of the thickness of suspension but with changing of the shape. In this paper, we use two method - Sensitivity analysis and SIP using ADS. And we obtained the optimized value close to target value.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.3
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• pp.129-134
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• 2012

The objective of cache is to reduce I/O access of physical storage device so that user accesses their data faster. Traditionally, the most important metric to measure the performance of cache is hitratio. Thus, when the cache maintains hitratio high, it is regarded as a good cache replacement policy. However, the cache miss latency is different when the storages are heterogeneous. Though the cache hitratio is high, if the cache often misses with low performance disk, then the user experiences low performance. To address this problem we proposed eviction cost estimation based cache management. In our result, the eviction cost estimation based cache management has 10~30% throughput improvement compared with LRU cache management.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.924-929
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• 2001

The flying height of contact slider is determined by vertical and pitching motions of slider. This paper performed the computer simulation for flying height change of contact slider. It is changed by many parameters, contact stiffness, contact damping, air bearing stiffness ratio, a location of mass center, and so on. Computer simulation is performed for knowing for what change of these parameters influences in flying height of contact slider. Disk surface is modeled in harmonic wave with from 10㎑ to 600㎑. Tri-pad slider is modeled in that contact slider has 2-DOF motion (vertical motion, pitching motion). Tri-pad contact slider is analyzed by numerical analysis method in computer simulation.