• Publications of The Korean Astronomical Society
• /
• v.23 no.2
• /
• pp.91-107
• /
• 2008

In this paper, we introduce the performance evaluation and development of Raw VLBI Data Buffer(RVDB) system for the synchronized playback processing of observed data in Korea-Japan Joint VLBI Correlator(KJJVC). The high-speed correlation processing system is under development so that the radio data obtained with 8192 channels and 8 Gbps speed from 16 stations will be able to be processed. When the recorded data of each station are played to correlator, the time synchronization of each station is very important because the correlator should process the data obtained with same time and condition. There are many types of recorder systems in the East Asia VLBI Network (EAVN). Therefore it is required to prepare the special time synchronized playback processing system to synchronize the time tag of observed data. The developed RVDB system consists of Data Input Output(DIO), 10GbE switch, and Disk Data Buffer(DDB). It can record the data with maximum 2 Gbps speed, and can play back the data to correlator with nominal 2 Gbps speed. To enable to play back the data of different playback system to the correlator, we developed the high-speed time synchronized playback processing system. We carried out the experiments of playing back and correlation for gigabit correlator and VCS trial product so as to confirm the performance of developed time synchronized playback processing system. In case of online and offline playing back experiment for gigabit correlator, we confirmed that the online and offline correlation results were the same. In case of playing back experiment for VCS trial product, we verified that the wide band and narrow band correlation results were also the same. Through the playing back experiments of RVDB system, the effectiveness of developed RVDB system was verified. In this paper, the system design, construction and experimental results are shown briefly.

• Journal of Advanced Navigation Technology
• /
• v.1 no.1
• /
• pp.81-94
• /
• 1997

The construction of Incheon International Airport(IIA) was planned in order to meet the national air transport demand which has been rapidly increased, and to be a major hub airport in Northeast Asia. However, it is inevitable to compete with Japanese airports because Japanese government also planned to expand greatly the airport capacity in Tokyo area and Kansai Airport in Osaka area. Since a hub airport should have convenient connecting flights to spoke cities, it is required for IIA to have plenty of short-haul flights to the cities around Seoul, for example, to the cities in East China, Japan and other East Asian countries. IIA authority and Korean national air carriers should coordinate to develop air transport demand for short-haul international route and establish efficient hub-spoke flight schedules. This would be a essential precondition to function as a hinterland hub in Northeast Asia. Reflecting the geographical position, the function as a hourglass hub could be possible, if IIA is utilised by major airlines as a bridge to connect passengers between cities in Southeast Asia and 'cities in North America. To be a successful hourglass hub, the Korean national carriers must try to engage in the joint operations or the alliances with the major airlines of Southeastern countries or North American countries. All of these could be accomplished through the cooperation among government, airport and national air carriers.

• Korean Chemical Engineering Research
• /
• v.50 no.4
• /
• pp.595-603
• /
• 2012

International Thermonuclear Experimental Reactor (ITER) will be constructed in 2019 according to the JIA (Joint Implementation Agreement) of 7 countries. The ITER fusion fuel cycle consists of fusion vacuum vessel, tritium plant and fuelling system. The tritium plant provides the functions of storage, delivery, separation, removal and recovery of the deuterium and tritium used as fusion fuels for the ITER. The tritium plant systems supply deuterium and tritium from external sources and treat all tritiated fluids from ITER operation through Storage and Delivery System (SDS), Tokamak Exhaust Processing (TEP), Isotope Separation System (ISS), Water Detritiation System & Atmosphere Detritiation System (WDS & ADS) and Analysis System (ANS). In this paper, the functions and design requirements of the major systems in the tritium plant and the status of R&D are described. Korean party is developing the SDS for ITER tritium plant and partially attaining the WDS technology through the construction and operation experience of the Wolsong Tritium Removal Facility (WTRF). Now it is expected that researchers in other fields such as chemical engineering take part in the development of upcoming technologies for ISS and TEP.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.9 no.4
• /
• pp.22-33
• /
• 2006

The objective of this paper is to discuss geographic information policies and strategies of British government and suggest effective policies for Korea National GIS project GIS that has been implemented geographic information infrastructures into public sectors and private markets for the last ten years. To obtain the research aim, this paper reviews the main factors of the Britain GIS project such as distribution structure and process of GI markets, government policies and strategies that are led by Ordnance Survey, most leading mapping agency in the UK. In conclusion, some issues have been explored with reference to the experiences of the Britain GIS projects. The first of these is the nature of geographic information and the second concerns the notion of the circulation policies of spatial data, and the last proposes Korea GIS policies and strategies for successful geographic information and spatial data implementation. The findings of the analysis of the Britain GIS development indicate that a shift began to take place from central government coordinate toward more extensive utilization of private and commercial sectors. This reflects both the increasing importance of geospatial data circulation in all levels of GIS stakeholders. Finally these discussions are particularly to be the issues where multi-agency collaboration of Korea government is concerned and can take the form of joint ventures by consortiums of both involving data producers and data users in order to increase commercial participation for value-added geospatial items, and to encourage both research and development sectors with low or free price policies.

• KDI Journal of Economic Policy
• /
• v.14 no.3
• /
• pp.97-124
• /
• 1992

The recent sharp increase in wages has driven many Korean manufacturing firms to move into technology-intensive fields. The task of industrial restructuring is, however, rather difficult for small and medium-sized enterprises (hereafter, "SMEs") which suffer from limited R&D resources. If the R&D activities of SMEs are left unattended, industrial restructuring process may be retarded. Hence, the government-sponsored programs can be justified when used to promote the technological level of SMEs. Because of the limited internal R&D resources of SMEs, in particular human resources, the government-sponsored programs that depend on financial subsidies to stimulate the R&D activities of SMEs may not be recommended. Rather, a more desirable policy is programs to subsidize outside sourcing of SMEs. Basic principles of the program are; (i) that the government should establish R&D laboratories which are specialized in joint researches with SMEs in each industry; (ii) research projects of the laboratories should be funded by SMEs; the government's support covers only fixed costs such as construction costs in order to avoid moral hazard problem. (iii) technology adviser programs sponsored by the government should be improved; geographical distribution is to be expanded and the activities are to be monitored by local governments. Also foreign networks need be strengthened.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.9
• /
• pp.4277-4283
• /
• 2012

Slip coefficient, whose value is dependent on the condition of contact surface at the friction joint of high tension bolt, is determined by slip load. Because contact area affects slip load, contact area that varies with bolt hole size is also related to the slip coefficient. In this study, we manufactured 32 specimens and performed bending and tension tests in order to examine changes in slip coefficient and load with material type, bolt diameter, and size of bolt hole. Slip load of specimens with oversize bolt hole had strength that was more than 80% higher than the slip load of specimens with standard bolt hole, and it also exceeded the design slip strength. In addition, we observed significant correlation between net-section ratio and slip ratio of specimens with oversize and standard bolt hole. However, some differences between the specimens are thought to have been caused by reduction in initial axial force of high tension bolt, which is an important parameter of slip coefficient. It is self-evident that increased bolt hole size would lead to decrease in design strength as it reduces both slip coefficient and bolt axial force. Nevertheless, we suggest that some flexibility in regulation of bolt hole, as long as it does not threaten the structural stability, may be a positive factor in terms of workability and efficiency.

• Tunnel and Underground Space
• /
• v.16 no.4 s.63
• /
• pp.281-287
• /
• 2006

Intake of groundwater by tunneling in a mountainous area mostly results from groundwater flow through fractured parts of total rock mass. For reasonable analysis of this phenomenon the representative joint groups 1, 2, and 3 have been selected by previous investigations, geological/geophysical field tests and boring works. Three dimensional fractures were generated by the FracMan and MAFIC which is a three dimensional finite element model has been used to analyse a groundwater flow through fractured media. Monte Carlo simulation was applied to reduce the uncertainty of this study. The numerical results showed that the average and deviation of amounts of groundwater intaked into tunnel per unit length were $5.40{\times}10^{-1}$ and $3.04{\times}10^{-1}m^3/min/km$. It is concluded that tunnel would be stable on impact of groundwater environment by tunneling because of the lower value than $2.00{\sim}3.00m^3/min/km$ as previous and present standard on the application of tunnel construction.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.7
• /
• pp.38-45
• /
• 2020

A magnetically levitating capsule train, which runs inside the sub-vacuum tube, can reach ultra-fast speeds by dramatically reducing the aerodynamic drag and friction. The capsule train uses the superconductor electrodynamic suspension (SC-EDS) method for levitation. The SC-EDS method has advantages, such as a large levitation gap and free of gap control, which could reduce the infra-construction cost. On the other hand, disadvantages, such as the large variation of the levitation-guidance gap and small damping characteristics in levitation-guidance force, could degrade the running stability and ride comfort of the capsule train. In this study, a dynamic analytical model of a capsule train based on the SC-EDS was developed to analyze the running dynamic characteristics. First, as important factors in the capsule train dynamics, the levitation and guidance stiffness in the SC-EDS system were derived, which depend non-linearly on the velocity and gap variation. A 3D dynamic analysis model for capsule trains was developed based on the derived stiffness. Through the developed model, the effects of the different running speeds on the ride comfort were analyzed. The effects of a disturbance from infrastructure, such as the curve radius, tube sag, and connection joint difference, on the running stability of the capsule train, were also analyzed.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.6 no.4
• /
• pp.327-343
• /
• 2004

During tunnel construction, ground failures often occur due to existence of weak zones, such as faults, joints, and cavities, ahead of tunnel face. It is hard to detect effectively weak zones, which can lead underground structure to fail after excavation and before supporting, by using conventional characterization methods. In this study, an enhanced analytical method of predicting weak zones ahead of tunnel face is developed to overcome some problems in the conventional geophysical exploration methods. The analytical method is based on Coulomb's and Gauss' laws with considering the characteristics of electric fields subjected to rock mass. Using the developed method, closed form solutions are obtained to detect a spherical shaped zone and an oriented fault ahead of tunnel face respectively. The analytical results suggest that the presence of weak zones and their sizes, location, and states can be accurately predicted by combining a proper inversion process with resistance measured from several electrodes on the tunnel face. It appears that the skin depth or resistivity in rock mass is affected by the diameter of tunnel face, natural electric potential and noises induced by experimental measurement and spatial distribution of uncertain properties. The developed analytical solution is verified through experimental tests. About 1800 concrete blocks of 5cm by 5cm by 5cm in size are prepared and used to model a joint rock mass around tunnel face. Weak zones are simulated ahead of tunnel face with a material which has relatively higher conductivity than concrete blocks. Experimental results on the model test show a good agreement with analytical results.

• Journal of the Korean Geophysical Society
• /
• v.6 no.3
• /
• pp.165-177
• /
• 2003

The purpose of this paper is to analyze the behavior and to study the safety evaluation of the Unmun Dam located in Cheongdo-Gun of GyeongBuk Province, Korea. For this purpose, soil analyses including boring data, geophysical surveys were conducted. In this paper, especially many geophysical methods were adopted to configure out the subsurface situation of dam. Applied geophysical methods were: 1) electric resistivity survey, 2) high frequency magnetotelluric (HFMT) survey, 3) ground penetrating radar (GPR) survey, 4) seismic refraction survey, 5) seismic cross-hole tomography survey, and 6) high frequency impedance (ZHF) survey. Each of geophysical surveys were analyzed and joint analyses between geophysical surveys were also performed to deduce the more reliable subsurface information of Dam by using the features and characteristics of each geophysical survey. Since many defects, such as gravel and weathered rock blocks in the dam core, and lots of amounts of leakage, by boring analyses were found, reinforcement by compaction grouting system (CGS) has been conducted in some range of dam. Some geophysical data and data of geotechnical gauges were also used to confirm the effects of reinforcement. Electric resistivity, EM, GPR, ZHF, seismic refraction and seismic tomography surveys show that left side of dam is weak, which means the possibility of existence of gravel, rock block, water and cavities in the core of dam. This result coincides with the boring data. Especially, electric survey after reinforcement shows that even the right side of the dam has been deformed by the strong pressure during the reinforcement itself. As a conclusion, some problems in the dam found. Especially, the dam near spillway shows the high possibility of leakage. It should be pointed out that only the left side of he dam has not a leakage problem. As a whole, the dam has problems of weakness, because of unsatisfactory construction. It is strongly recommended that highly intensive monitoring is required.