• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.63-64
• /
• 2018

In this study, a design method for a circular polarization patch antenna operating at a frequency 1.5 GHz~1.7 GHz was studied. To obtain the wide bandwidth and high gain, air substrate between patch and ground plane was applied. The impedance bandwidth is improved by adjusting the sizes of patch, the distance between main patch and ground plate, the length of internal slots, the position of feeding point, the length of external stub, etc. The antenna is designed and simulated for an operation in the frequency range of 1.5GHz~1.7GHz band. The results show that antenna characteristics such as return loss, gain, axial ratio, radiation patterns are appropriate for the satellite navigation system.

• Korean Journal of Medicinal Crop Science
• /
• v.7 no.2
• /
• pp.129-137
• /
• 1999

The structure of amyloplasts and intercellular transport in the old and new bulbs of Frjtillaria pallidiflora were observed by means of electron microscope. The structure of internal membrane system was different between new and old amyloplasts. The active intercellular transport was observed in both new and old bulbs. The phenomena of encytosis and exocytosis always could be found in the cell membrane, and plasmodesmata established a symplasmic pathway for intercellular transport. Groups of vesicles often located at the ends of plasmodesmata, showing that they participated in the intercellular transport. These results laid a foundation for the further study on the mechanism of growth and development in Fritillaria pallidiflora.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.413-416
• /
• 2008

Reinforcement corrosion is generally prohibited under normal condition by the alkalinity of the pore water in the concrete. However, concrete structures in marine environment are subjected to chloride attack due to the high salinity of the sea water. Thus the probability of steel corrosion becomes higher when the chloride ions are introduced into the concrete. Steel corrosion is a decisive factor for the determination of service life of the marine concrete structure because chloride ions are abundant in the sea, and piers are the typical construction elements in concrete structures in marine environment. Hence, it is of great importance to evaluate the service life of the piers. In this paper, chloride penetration analysis for the rectangular pier in the marine environment is performed considering the diffusion and convection movement of chlorides. Result reveals that the service life of the reinforcement with drying-wetting cycles is much shorter than that of the reinforcement with saturated condition. This may be due to the fact that moisture movement is much faster that chloride diffusion.

• Journal of the Korean Society for Railway
• /
• v.14 no.3
• /
• pp.240-247
• /
• 2011

Finite element analysis was undertaken to investigate the effect of freezing force of water unexpectedly penetrated into inserts used in railway sleeper on pullout capacity of anchor bolts for fixing base-plate onto concrete sleeper. Based on the in-situ investigation and measurement of geometry of railway sleeper and rail-fastener, the railway sleeper was modeled by 3D solid elements. Nonlinear and fracture properties for the finite element model were assumed according to CEB-FIP 1990 model code. And the pullout maximum load of anchor bolt obtained from the model developed was compared with experimental pullout maximum load presented by KRRI for verification of the model. Using this model, the effect of position of anchor bolt, amount of fastening force applied to the anchor bolt, and compressive strength of concrete on pull-out capacity of anchor bolts installed in railway sleeper was investigated. As a result, it is found that concrete railway sleepers could be damaged by the pressure due to freezing of water penetrated into inserts. And the pullout capacity of anchor bolt close to center of railway is slightly greater than that of the others.

• Science of Emotion and Sensibility
• /
• v.16 no.4
• /
• pp.527-534
• /
• 2013

In this study, we analyzed spatial-frequency relationship related brain function for change of the time during attentional visual stimulus through the analysis of Coherence. With experimentation about ERP(Event Related Potential)data, it revealed that change of the phase synchronization between different scalp locations at ${\theta}$, ${\alpha}$ band. ERP between left and right frontal lobes, between the frontal and central lobes showed the phase synchronization at the P100, N200, ERP between the frontal and occipital lobes showed the phase synchronization at the P300 related information of visual stimulus. Compared to STFT using the window of a fixed length, CWT is able to multi-resolution analysis with the adjustment of parameters of mother wavelet. Thus, coherence results with CWT was found to be effective for analysis of time-varying spatial-frequency relationship in ERP. The phase synchronization for inattentional visual stimulus was not observed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.9
• /
• pp.800-807
• /
• 2016

In this paper, we study the characteristics of dual band microstip antenna with modified inset feeder and a single slot. The modified inset feeder consists of the vertical inset feeder placed in x direction and the horizontal one in y direction for shortening the total length of inset feeder. The optimun feeding position for good impedance matching at two resonant frequencies can be easily found by adjusting the horizontal inset distance. And Various frequency ratios can be simply obtained by the parameters of slot. The measurements for fabricated antenna prototypes are carried out for validation. The measured results show a tunable frequency ratio from 1.25 to 1.88 with the variation of slot parameters. It is worthwhile to point out that the radiation patterns are similar at both bands. and below -20.0 dB of cross polarization level at the E plane.

• The Journal of the Korea Contents Association
• /
• v.13 no.2
• /
• pp.32-43
• /
• 2013

These days, there are more and more IT research institutions which foresee cloud services as the predominant IT service in the near future and there, in fact, are actual cloud services provided by some IT leading vendors. Regardless of physical location of the service and environment of the system, cloud service can provide users with storage services, usage of data and software. On the other hand, cloud service has challenges as well. Even though cloud service has its edge in terms of the extent to which the IT resource can be freely utilized regardless of the confinement of hardware, the availability is another problem to be solved. Hence, this paper is dedicated to tackle the aforementioned issues; prerequisites of cloud computing for distributed file system, open source based Hadoop distributed file system, in-memory database technology and high availability database system. Also the author tries to body out the high availability mass distributed data management architecture in cloud service's perspective using currently used distributed file system in cloud computing market.

• Journal of Bio-Environment Control
• /
• v.13 no.3
• /
• pp.149-155
• /
• 2004

On this study, a multipurpose operating system was developed to adjust a configuration of a moving path which have no connection with a form of greenhouse. To being performance the multipurpose working system, we have experienced growth quality on the plants in greenhouse. Some of the results are as follows. While watering by the hand spray. the condition of plant was generally no good. It was shown that plant height and leaf area were all high without wind during watering by the automatic spray. The effect to retrain a plant growth was high as a ventilation was strong. The diameter of a plant stem was small without ventilation condition during watering 3 times by automatic spray. The number of leaf was relatively large during 3 times by automatic spray compared to 2 times by automatic spray or hand spray. Growth of plant was fast as the times of spray were large.

• Journal of Labour Economics
• /
• v.27 no.2
• /
• pp.1-27
• /
• 2004

The share of self-employment shows a downward trend until 1990 and then an upward trend since then. The upward trend is mainly due to more employers and more male self-employed, which implies that self-employment plays a significant role as an alternative form of employment. This paper examines whether self-employment can be a bridge between no work and wage work in the processes entering into or exiting labor market, and if so, what determines the choice of self-employment as a bridge, using the data from the Korea Labor and Income Panel Survey(Wave 1 to Wave 5). Empirical analysis employing the probit model shows that the older, female, the less educated, and persons with bad health are more likely to choose self-employment as a bridge in the exit process and that they are less likely to choose it as a bridge in the entry process. Business cycle has a statistically significant negative effect on its role of bridge employment in the exit process but not in the entry process. The result implies that, in the ageing society, labor market policy should consider self-employment as a better alternative than wage work for the aged.

• Journal of Chest Surgery
• /
• v.36 no.2
• /
• pp.118-121
• /
• 2003

A 25-year-old female patient was adimitted due to discomfort in the right chest and left epigastric area. Chest X-ray and chest CT showed a round 4$\times$4$\times$4cm sized mass located in the right lower lobe and abutted on the right diaphragm and metastatic lesions in the right lower lobe and right middle lobe. In exploratory thoracotomy, we discovered a mass originating from the right diaphragm which directly invaded the right lower lobe and metastatic subpleural lesions in the right lower lobe and right middle lobe. The mass was diagnosed as sarcoma by frozen section biopsy and we removed the mass by on bloc resection of the right diaphragm and right lower lobe. Metastatic subpleural lesions in the right lower lobe and right middle lobe were removed by wedge resection. The mass was malignant fibrous histiocytoma of the diaphragm in permanent pathologic examination and chemotherapy was done as adjuvant measure. We report one extremely rare case of malignant fibrous histiocytoma of the diaphragm with literature.