• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.191-194
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• 2001

The availability of the inexpensive, large main memories coupled with the demand for faster response time are bringing a new perspective to database technology. The Web GIS used by u unspecified number of general public in the internet needs high speed response time and frequent data retrieval for spatial analysis rather than data update. Therefore, it is appropriate to use main memory as a underlying storage structures for the Web GIS data. In this paper, we propose a data representation method based on relative coordinates and the size of the MBR. The method is able to compress the spatial data widely used in the Web GIS into smaller volume of memory. We also propose a memory resident spatial index with simple mechanism for processing point and region queries. The performance test shows that the index is suitable for managing the skewed data in terms of the size of the index and the number of the MBR intersection check operations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.168-168
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• 2008

Dimension of a transistor has rapidly shrunk to increase the speed of device and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate dioxide layer and low conductivity characteristic of poly-Si gate in nano-region. To cover these faults, study of new materials is urgently needed. Recently, high dielectric materials like $Al_2O_3$, $ZrO_2$, and $HfO_2$ are being studied for equivalent oxide thickness (EOT). However, poly-Si gate is not compatible with high-k materials for gate-insulator. Poly Si gate with high-k material has some problems such as gate depletion and dopant penetration problems. Therefore, new gate structure or materials that are compatible with high-k materials are also needed. TiN for metal/high-k gate stack is conductive enough to allow a good electrical connection and compatible with high-k materials. According to this trend, the study on dry etching of TiN for metal/high-k gate stack is needed. In this study, the investigations of the TiN etching characteristics were carried out using the inductively coupled $BCl_3$-based plasma system and adding $Cl_2$ gas. Dry etching of the TiN was studied by varying the etching parameters including $BCl_3$/Ar gas mixing ratio, RF power, DC-bias voltage to substrate, and $Cl_2$ gas addition. The plasmas were characterized by optical emission spectroscopy analysis. Scanning electron microscopy was used to investigate the etching profile.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.84-90
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• 2017

Explosive bolt is coupled in a variety of guided weapons and space projectiles, to perform the separation function. Thus, the role of the explosive bolt in guided weapons systems is very important, as it can cause failure of the entire system in the case of mission failure. For this reason, the design life prediction for explosive bolt is highly and frequently required recently, but its accurate prediction method has not been presented. In order to apply the existing accelerated aging process, we should know the activation energy and the acceleration factor of the explosive bolt. Since the information required for accelerated aging is not presently secured, it is difficult to predict the design life of explosive. Thus, in the present study, we have evaluated the performance of actual explosive bolts in the condition of natural aging over 10 years in order to present a minimum design life.

• Smart Structures and Systems
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• v.17 no.6
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• pp.1107-1127
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• 2016

Studies on dynamic characteristics of the hanger vibration using field monitoring data are important for the design and evaluation of high-speed railway truss arch bridges. This paper presents an analysis of the hanger's dynamic displacement responses based on field monitoring of Dashengguan Yangtze River Bridge, which is a high-speed railway truss arch bridge with the longest span throughout the world. The three vibration parameters, i.e., dynamic displacement amplitude, dynamic load factor and vibration amplitude, are selected to investigate the hanger's vibration characteristics in each railway load case including the probability statistical characteristics and coupled vibration characteristics. The influences of carriageway and carriage number on the hanger's vibration characteristics are further investigated. The results indicate that: (1) All the eight railway load cases can be successfully identified according to the relationship of responses from strain sensors and accelerometers in the structural health monitoring system. (2) The hanger's three vibration parameters in each load case in the longitudinal and transverse directions have obvious probabilistic characteristics. However, they fall into different distribution functions. (3) There is good correlation between the hanger's longitudinal/transverse dynamic displacement and the main girder's transverse dynamic displacement in each load case, and their relationships are shown in the hysteresis curves. (4) Influences of the carriageway and carriage number on the hanger's three parameters are different in both longitudinal and transverse directions; while the influence on any of the three parameters presents an obvious statistical trend. The present paper lays a good foundation for the further analysis of train-induced hanger vibration and control.

• Coupled systems mechanics
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• v.9 no.2
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• pp.111-123
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• 2020

Wastewater treatment plants (WWTPs) with activated sludge system are widely used throughout the most common technologies in the world. Most treatment plants require optimization of certain treatment processes using dynamic modeling. A lot of examples of dynamic simulations require reliable data base of diurnal variation of the inflow and typical concentrations of parameters such as Chemical Oxygen Demand (COD), Total Kjeldahl Nitrogen (TKN), etc. Such detailed data are not available, which leads to problemsin the application of dynamic simulations. In many examples of plants, continuous flow measurements are only performed after the primary clarifier, whereas measurements from influent to the plant are missing, as is the case with the examples in this paper. In some cases, a simpler, faster and cheaper way can be applied to determine influent variations, such as the "HSG-Sim" method ("Hochschulgruppe Simulation"). "Hochschulgruppe Simulation" is a group of researchers from Germany, Austria, Switzerland, Luxembourg, Netherlands and Poland (see http://www.hsgsim.org). This paper presents a model for generating daily variations of inflow and concentration of municipal wastewater quality parameters, applied to several existing WWTPs in Bosnia and Herzegovina (B&H). The main goal of the applied method is to generate realistic influent data of the existing plants in B&H, in terms of flow and quality, without any prior comprehensive survey and measurements at the site. The examples of plants show the influence of overflow facilities on the dynamics of input flow and quality of wastewater, and a strong influence of the problems of the sewerage systems.

• Korean Journal of Plant Resources
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• v.23 no.3
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• pp.233-241
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• 2010

In vitro elimination of Sweet potato leaf curl virus (SPLCV) from infected sweet potato is difficult due to low number of virus-free plants obtained from meristem tip culture and long growth period required for the virus detection. In this study, efficient production of the SPLCV-free sweet potato by in vitro therapy coupled with a PCR assay for virus detection was investigated. Infected shoots cultured on Murashige and Skoog medium were treated at three different temperatures for 7 weeks followed by meristem tip culture on the medium with or without ribavirin at 50 mg/L. The regenerated plantlets were tested for virus infection by a PCR assay. The results showed that the both heat- and cold-treatments, and addition of the ribavirin did not have significant effect on efficiency of the virus elimination. The meristem size, however, greatly affected the survival rate. Meristems sized over 0.4 mm survived better than smaller ones (0.2-0.3 mm). The PCR assay was approved to be a rapid, sensitive and reliable for the SPLCV detection in regenerated plantlets. Therefore, combination of cultivating meristem tips sized 0.4-0.5 mm on the medium at $22^{\circ}C$ without ribavirin and detection of SPLCV in the regenerated plantlets by the PCR assay was an efficient system for the SPLCV elimination from infected sweet potato.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.107-113
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• 2014

A VCO (Voltage Controlled Oscillator) and a divide-by-4 high speed frequency divider are implemented using 65nm CMOS technology for 60GHz wireless communication system. The mm-wave VCO was designed by NMOS cross-coupled LC type using current source. The architecture of the divide-by-4 high speed frequency divider is differential ILFD (Injection Locking Frequency Divider) with varactor to control frequency range. The frequency divider also uses current sources to get good phase noise characteristics. The measured results show that the VCO has 64.36~67.68GHz tuning range and the frequency divider divides the VCO output by 4 exactly. The high output power of 5.47~5.97dBm from the frequency divider is measured. The phase noise of the VCO including the frequency divider are -77.17dBc/Hz at 1MHz and -110.83dBc/Hz at 10MHz offset frequency. The power consumption including VCO is 38.4mW with 1.2V supply voltage.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.8
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• pp.51-57
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• 2004

We have analyzed the effect of out-band dispersion in the cascaded fiber Bragg Elating(FBG) based optical add-drop multiplexers(OADM) when bypassed wavelengths contain SCM signals. In order to compute this impairment the dispersion characteristics of FBG have been analytically calculated by solving their coupled wave equations, and the Fourier method is applied to IMD analysis. The out-band dispersion effects over WDM/SCM signals are analyzed under different and common system situations as: ITU channel spacing(100, 50, 25 GHz), channel density parameter, frequency extension of the SCM plan, modulation characteristics, FBG length, etc. From this results, the transport of WDM/SCM signals in future DWDM transport networks could be limited by this effect which has to be taken into account for designing future networks.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.37-47
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• 1999

Among the geophysical exploration methods, electromagnetic (EM) survey must have the broadest range of instrumental systems and remarkable range of applications. There is a plethora of available techniques and instruments, and the depth of investigation and resolution are highly dependent on the particular systems used according to their operating frequency and source-receiver configuration. This diversity of EM systems, however, provides a wide range of instruments or methodologies to choose in order to select the most appropriate tool for the task in hand. This rather than being a disadvantage, would be a major strength of EM methods. Modern EM equipments are remarkably portable, considering their sophistication. Coupled with major advances in recent computer technology, accurate modeling and interpretation techniques are on the way of continuous development and upgrade which, in turn, make the EM methods to become much more heavily used, especially for engineering and environmental applications. We aim to provide a brief theoretical principles, survey techniques and case histories of some selected EM methods that can be applied to geotechnical and environmental problems in Korea.

• Journal of the Semiconductor & Display Technology
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• v.10 no.2
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• pp.115-119
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• 2011

A tip-type carbon nanotube(CNT)-based field emitter was studied to consider it as electron source for micro-focused x-ray tube. The CNT was grown directly on a metal (tungsten) substrate by using an inductively coupled plasma-chemical vapor deposition (ICP-CVD) method. Prior to CNT growth, the metal substrate was etched to have various tip angles from $10^{\circ}$ to $180^{\circ}C$ (flat-type). The morphologies and microstructures of all the grown CNTs were analyzed via field-emission SEM. Furthermore, the effects of substrate tip-angles on the emission properties of CNT-based field emitters were characterized to estimate the maximum current density, the turn-on voltage, and the spatial distribution of electron beams. Prolonged long-term stability testing of the CNT emitters was also performed. All the experiment results obtained from this study indicated why a tip-type CNT emitter, compared with a flat-type CNT emitter, would be more desirable for a micro-focused x-ray system, in terms of the emission current level, the focused beam area, and the emission stability.