• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.7
• /
• pp.693-700
• /
• 2008

High-Pressure gas Pipeline which is buried in underground has the Possibility that will be exposed to unexpected dangerous impact of construction equipment. To protect from this kind of danger, the real-time health monitoring system of the high-pressure gas pipeline is necessary. First of all, to make the real-time health monitoring system clearly, the acoustic wave propagation characteristics which are made from various construction equipment impacts must be identified. In link of technical development that prevents the damage of high-pressure gas pipeline, this paper gives FEM(finite element method) and BEM(boundary element method) solutions to identify the acoustic wave propagation characteristic of the various impact input signals which consist of Direc delta function and convolution signal of 45 Hz square signal and random signal.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.48 no.1
• /
• pp.42-47
• /
• 1999

This paper presents the information transmission between on-board and ground-site in MAGLEV. considering safety and high speed operation and density operation, information transmission between them is necessary. Therefore it is necessary for transmission system to ensure high speed transmission, low error rate, massive information, and reliability of information. To provide above conditions, 1.1km signal line assembly was constructed and Frequency Shift Keying(FSK) modulation and Open System Interconnection(OSI) based high-level data link control(HDLC) protocol are applied. To modulate digital signal for transmission from ground-site to on-board, carrier frequency of 70kHz is used and 90khz is used for transmission from on-board to ground-site. Transmission speed is 2400bps for consideration of train speed, quantity of information, and data error rate. And this paper introduces information monitoring considering user interface and presents the method for an effective data transmission in MAGLEV which is now being tested and intends to provide for an intelligent train operation system in future.

• Journal of Power Electronics
• /
• v.15 no.2
• /
• pp.399-410
• /
• 2015

A 6.5 V/50 kA high-frequency switching power supply (HSPS) system composed of 10 power modules is developed to meet the requirements of copper-foil electrolysis. The power module is composed of a two-leg pulse width modulation (PWM) rectifier and a DC/DC converter. The DC/DC converter adopts two full-wave rectifiers in parallel to enhance the output. For the two-leg PWM rectifier, the ripple of the DC-link voltage is derived. A composite control method with a ripple filter is then proposed to effectively improve the performance of the rectifier. To meet the process demand of copper-foil electrolysis, the virtual impedance-based current-sharing control method with load current full feedforward is proposed for n-parallel DC/DC converters. The roles of load current feedforward and virtual impedance are analyzed, and the current-sharing control model of the HSPS system is derived. Virtual impedance is used to adjust the current-sharing impedance without changing the equivalent output impedance, which can effectively reduce current-sharing errors. Finally, simulation and experimental results verify the structure and control method.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.7
• /
• pp.1180-1186
• /
• 2008

The LNB phase noise of user terminal for high data rate satellite transmission was analyzed in this paper. The phase noise severely affects the service performance in low data rate transmission as well as multi-mode signal for high data rate. As the satellite link frequency is increased, the effects of phase noise for multi-mode signal is increased. The phase noise of LNB, which is operated in high frequency band, is about equal to the transmission system phase noise and have an major effects on service performance degradation. The available transmission mode was analyzed in presence of phase noise of LNB and analysis method for LNB phase noise spectrum distribution was proposed in multi-mode signal.

• Journal of Korea Multimedia Society
• /
• v.17 no.4
• /
• pp.478-489
• /
• 2014

Recently, flood damage by frequent localized downpours in cities are on the increase on account of abnormal climate phenomena and growth of impermeable area by urbanization. In this study, we are focused on flooding on roads which is the basis of all means of transportation. To calculate real-time accumulated rainfall on a road link, we use the Coefficient of Correlation Weighting method (CCW) which is one of the revised methods of missing rainfall as we consider a road link as a unobserved rainfall site. CCW and real-time accumulated rainfall entered through the Internet are used to estimate the real-time rainfall on a road link. Together with the real-time accumulated rainfall, flooding history, rainfall range causing flooding of a road link and frequency probability precipitation for road design are used as factors to determine the Flood Risk Index on roads. We simulated two cases in the past, July, 7th, 2009 and July, 15th, 2012 in Busan. As a result, all of road links included in the actual flooded roads at that time got the high level of flood risk index.

• Journal of Advanced Navigation Technology
• /
• v.10 no.4
• /
• pp.356-363
• /
• 2006

The demand for digital multimedia service using Ka band satellite communication are growing rapidly. So, in this paper, we have analyzed rain attenuation with typical model, and proposed prediction model of rain attenuation in high frequency(20 GHz). This paper illustrates Korea rain attenuation characteristics at the Ka band Koreasat beacon frequency based on the theoretical and empirical approaches and seek for efficient techniques by rain attenuation estimate and analyzed performance of adaptive modulation system. Propose prediction model of rain attenuation and parameter of satellite link can be available for the Ka band satellite communication.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.15 no.1
• /
• pp.60-68
• /
• 2010

Recently, Power Conditioning System (PCS) tends to require more compact, higher efficiency and power density with better performance. A novel topology consisted of LLC resonant inverter and Low Frequency (LF) cyclo-converter for connecting to utility line is able to meet these requirements. The technical operating analysis is described and 1kW prototype is tested and verified the performances through connecting the 110Vac 60Hz utility line. Efficient results are described.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.2
• /
• pp.242-251
• /
• 2000

Design of wireless link in Ka and mm-wave bands is critically affected by rain attenuation. In this paper, we compared and analyzed the main distributions of rain drop size to estimate the rain attenuation which can be used in domestic environment. Mie scattering theory was checked to agree with Rayleigh theory in its low frequency limit and agree with optical scattering theory in its high frequency limit. We intended to provide more specific criteria to estimate rain attenuation with a generalized approach.

• Wind and Structures
• /
• v.4 no.6
• /
• pp.495-504
• /
• 2001

With a newly developed multi-force-balance system(MFB), a twin-tower structure was studied for its wind-induced responses. The MFB system allowed the twin towers, which were linked structurally, to be treated as a single structural system with its corresponding modes of vibration involving coupled motions of the two towers. The towers were also studied using a more conventional force balance approach in which each tower was treated as an isolated structure, i.e., as though no structural link existed. Comparison of the results reveals how the wind loads between the towers are redistributed through the structural links and the modal couplings. The results suggest that although the structural links usually have beneficial impacts on wind-induced response, they may also play a negative role if the frequency ratios of pair modes are near 1.0.

• The Research Journal of the Costume Culture
• /
• v.7 no.2
• /
• pp.230-241
• /
• 1999

The purpose of this study is to classify frequency of advertisement and types of advertisement by items and to analyze a primary factors were factors were reflected in the costumes by a policy of rule under the Japanese rule. Data was MaIl Shin Bo\`s advertisement connected with costumes from 1910 to 1945 years. The results are as follows : 1. The order of the advertisement\`s frequency was footwear, cosmetics, soap[, headgear, western style clothes, precious metals and so on. 2. The type of the advertisement was a format that transmits informs in all items. Cosmetics, hairdye and shampoo applied positive appeals. 3. In the military government, the advertisement\`s frequency connected with costumes was 37.5% and a shoe store was the first order. A shoes and headgear were high level, because of these were essential imports and were allowded as a proper articles for a western style clothes by a civilized policy. In the political periods of civilization, the advertisement\`s frequency connected with costumes was 54%. This result indicates industrial development of this period. Soap was the first order during 1924∼1933 and cosmetics was the first order during 1934∼1940. High level of the advertisement\`s frequency in these imports were reflected by a cultural policy as a link of an appeasement measure In the political periods of a racial liquidation, the advertisement\`s frequency connected with costumes was 8.5% and the advertisement\`s order by items was cosmetics, a shoe store. The reason was that reflected the phases of the times that was serious by a shortage of goods and an reinforcement of wartime\`s attitudes throughout war.