• Title/Summary/Keyword: High-efficient power

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Accuracy Analysis of ADCP Stationary Discharge Measurement for Unmeasured Regions (ADCP 정지법 측정 시 미계측 영역의 유량 산정 정확도 분석)

  • Kim, Jongmin;Kim, Seojun;Son, Geunsoo;Kim, Dongsu
    • Journal of Korea Water Resources Association
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    • v.48 no.7
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    • pp.553-566
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    • 2015
  • Acoustic Doppler Current Profilers(ADCPs) have capability to concurrently capitalize three-dimensional velocity vector and bathymetry with highly efficient and rapid manner, and thereby enabling ADCPs to document the hydrodynamic and morphologic data in very high spatial and temporal resolution better than other contemporary instruments. However, ADCPs are also limited in terms of the inevitable unmeasured regions near bottom, surface, and edges of a given cross-section. The velocity in those unmeasured regions are usually extrapolated or assumed for calculating flow discharge, which definitely affects the accuracy in the discharge assessment. This study aimed at scrutinizing a conventional extrapolation method(i.e., the 1/6 power law) for estimating the unmeasured regions to figure out the accuracy in ADCP discharge measurements. For the comparative analysis, we collected spatially dense velocity data using ADV as well as stationary ADCP in a real-scale straight river channel, and applied the 1/6 power law for testing its applicability in conjunction with the logarithmic law which is another representative velocity law. As results, the logarithmic law fitted better with actual velocity measurement than the 1/6 power law. In particular, the 1/6 power law showed a tendency to underestimate the velocity in the near surface region and overestimate in the near bottom region. This finding indicated that the 1/6 power law could be unsatisfactory to follow actual flow regime, thus that resulted discharge estimates in both unmeasured top and bottom region can give rise to discharge bias. Therefore, the logarithmic law should be considered as an alternative especially for the stationary ADCP discharge measurement. In addition, it was found that ADCP should be operated in at least more than 0.6 m of water depth in the left and right edges for better estimate edge discharges. In the future, similar comparative analysis might be required for the moving boat ADCP discharge measurement method, which has been more widely used in the field.

A Survey on the Break-down and Repair of the Power Tillers in Korea (동력경운기(動力耕耘機) 이용실태(利用實態) 조사분석(調査分析)(II) -고장(故障) 및 수리(修理)에 관(關)하여-)

  • Hong, Jong Ho;Lee, Chai Shik
    • Journal of Biosystems Engineering
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    • v.6 no.1
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    • pp.28-38
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    • 1981
  • A survey has been conducted to investigate the presents of breaks down and repair of power tiller for efficient use. Eight provinces were covered for this study. The results are summarized as follows. A. Frequency of breaks down. 1) Power tiller was breaken down 9.05 times a year and it represents a break down every 39.1 hours of use. High frequency of breaks down was found from the fuel and ignition system. For only these system, the number of breaks down were 2.02 and it represents 23.3% among total breaks down. It was followed by attachments, cylinder system, and traction device. 2) For the power tiller which was more than six years old, breaks down accured 37.7 hours of use and every 38.6 hours for the power tiller which was purchased in less than 2 years. 3) For the kerosene engine power tiller, breaks down occured every 36.8 hours of use, which is a higher value compared with diesel engine power tiller which break down every 42.8 hours of use. The 8HP kerosene engine power tiller showed higher frequency of break down compared with any other horse power tiller. 4) In October, the lowest frequency of break down was found with the value of once for every 51.5 hours of use, and it was followed by the frequency of break down in June. The more hours of use, the less breaks down was found. E. Repair place 1) 45.3% among total breaks down of power tiller was repaired by the owner, and 54.7% was repaired at repair shop. More power tiller were repaired at repair shop than by owner of power tiller. 2) The older the power tiller is, the higher percentage of repairing at the repair shop was found compared with the repairing by the owner. 3) Higher percentage of repairing by the owner was found for the diesel engine power tiller compared with the kerosene engine power tiller. It was 10 HP power tiller for the kerosene power tiller and 8 HP for the diesel engine power tiller. 4) 66.7% among total breaks down of steering device was repaired by the owner. It was the highest value compared with the percentage of repairing of any other parts of power tiller. The lowest percentage of repairing by owner was found for the attachments to the power tiller with the value of 26.5%. C. Cause of break down 1) Among the total breaks down of power tiller, 57.2% is caused by the old parts of power tiller with the value of 5.18 times break down a year and 34.7% was caused by the poor maintenance and over loading. 2) For the power tiller which was purchased in less than two years, more breaks down were caused by poor maintenance in comparison to the old parts of power tiller. 3) For the both 8-10 HP kerosene and diesel engine power tiller, the aspects of breaks down was almost the same. But for the 5 HP power tiller, more breaks down was caused by over loading in comparison to the old parts of power tiller. 4) For the cylinder system and traction device, most of the breaks down was caused by the old parts and for the fuel and ignition system, breaks down was caused mainly by the poor maintenance. D. Repair Cost 1) For each power tiller, repair cost was 34,509 won a year and it was 97 won for one hoar operation. 2) Repair cost of kerosene engine power tiller was 40,697 won a year, and it use 28,320 won for a diesel engine power tiller. 3) Average repair cost for one hour operation of kerosene engine power tiller was 103 won, and 86 won for a diesel engine power tiller. No differences were found between the horse power of engines. 4) Annual repair cost of cylinder system was 13,036 won which is the highest one compared with the repair cost of any other parts 362 won a year was required to repair the steering device, and it was the least among repair cost of parts. 5) Average cost for repairing the power tiller one time was 3,183 won. It was 10,598 won for a cylinder system and 1,006 won for a steering device of power tiller. E. Time requirement for repairing by owner. 1) Average time requirements for repairing the break down of a power tiller by owner himself was 8.36 hours, power tiller could not be used for operation for 93.58 hours a year due to the break down. 2) 21.3 hours were required for repairing by owner himself the break down of a power tiller which was more than 6 years old. This value is the highest one compared with the repairing time of power tiller which were purchased in different years. Due to the break down of the power tiller, it could not be used for operation annually 127.13 hours. 3) 10.66 hours were required for repairing by the owner himself a break down of a diesel engine power tiller and 6.48 hours for kerosene engine power tiller could not be used annually 99.14 hours for operation due to the break down and it was 88.67 hour for the diesel engine power tiller. 4) For both diesel and kerosene engine power tiller 8 HP power tiller required the least time for repairing by owner himself a break down compared with any other horse power tiller. It was 2.78 hours for kerosene engine power tiller and 8.25 hours fur diesel engine power tiller. 5) For the cylinder system of power tiller 32.02 hours were required for repairing a break down by the owner himself. Power tiller could not be used 39.30 hours a year due to the break down of the cylinder system.

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A Study on the Shaped-Beam Antenna with High Gain Characteristic (고이득 특성을 갖는 성형 빔 안테나에 대한 연구)

  • Eom, Soon-Young;Yun, Je-Hoon;Jeon, Soon-Ick;Kim, Chang-Joo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.1 s.116
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    • pp.62-75
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    • 2007
  • This paper describes a shaped-beam antenna for increasing the antenna gain of a radiating element. The proposed antenna structure is composed of an exciting element and a multi-layered disk array structure(MDAS). The stack micro-strip patch elements were used as the exciter for effectively radiating the electromagnetic power to the MDAS over the broadband, and finite metallic disk array elements - which give the role of a director for shaping the antenna beam with the high gain - were finitely and periodically layered onto it. The efficient power coupling between the exciter and the MDAS should be carried out in such a way that the proposed antenna has a high gain characteristic. The design parameters of the exciter and the MDAS should be optimized together to meet the required specifications to meet the required specifications. In this study, a shaped-beam antenna with high gain was optimally designed under the operating conditions with a linear polarization and the frequency band of $9.6{\sim}10.4\;GHz$. Two methods constructed using thin dielectric film and dielectric foam materials respectively were also proposed in order to implement the MBAS of the antenna. In particular, through the computer simulation process, the electrical performance variations of the antenna with the MDAS realized by the thin dielectric film materials were shown according to the number of disk array elements in the stack layer. Two kinds of antenna breadboard with the MDAS realized with the thin dielectric film and dielectric foam materials were fabricated, but experimentation was conducted only on the antenna breadboard(Type 1) with the MDAS realized with the thin dielectric film materials according to the number of disk array elements in the stack layer in order to compare it with the electrical performance variations obtained during the simulation. The measured antenna gain performance was found to be in good agreement with the simulated one, and showed the periodicity of the antenna gain variations according to the stack layer number of the disk array elements. The electrical performance of the Type 1 antenna was measured at the center frequency of 10 GHz. As the disk away elements became the ten stacks, a maximum antenna gain of 15.65 dBi was obtained, and the measured return loss was not less than 11.4 dB within the operating band. Therefore, a 5 dB gain improvement of the Type 1 antenna can be obtained by the MDAS that is excited by the stack microstrip patch elements. As the disk array elements became the twelve stacks, the antenna gain of the Type 1 was measured to be 1.35 dB more than the antenna gain of the Type 2 by the outer dielectric ring effect, and the 3 dB beam widths measured from the two antenna breadboards were about $28^{\circ}$ and $36^{\circ}$ respectively.

Front-End Processing for Speech Recognition in the Telephone Network (전화망에서의 음성인식을 위한 전처리 연구)

  • Jun, Won-Suk;Shin, Won-Ho;Yang, Tae-Young;Kim, Weon-Goo;Youn, Dae-Hee
    • The Journal of the Acoustical Society of Korea
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    • v.16 no.4
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    • pp.57-63
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    • 1997
  • In this paper, we study the efficient feature vector extraction method and front-end processing to improve the performance of the speech recognition system using KT(Korea Telecommunication) database collected through various telephone channels. First of all, we compare the recognition performances of the feature vectors known to be robust to noise and environmental variation and verify the performance enhancement of the recognition system using weighted cepstral distance measure methods. The experiment result shows that the recognition rate is increasedby using both PLP(Perceptual Linear Prediction) and MFCC(Mel Frequency Cepstral Coefficient) in comparison with LPC cepstrum used in KT recognition system. In cepstral distance measure, the weighted cepstral distance measure functions such as RPS(Root Power Sums) and BPL(Band-Pass Lifter) help the recognition enhancement. The application of the spectral subtraction method decrease the recognition rate because of the effect of distortion. However, RASTA(RelAtive SpecTrAl) processing, CMS(Cepstral Mean Subtraction) and SBR(Signal Bias Removal) enhance the recognition performance. Especially, the CMS method is simple but shows high recognition enhancement. Finally, the performances of the modified methods for the real-time implementation of CMS are compared and the improved method is suggested to prevent the performance degradation.

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Reservoir Operating System Using Sampling Stochastic Dynamic Programming for the Han River Basin (표본 추계학적 동적계획법을 사용한 한강수계 저수지 운영시스템 개발)

  • Eum, Hyung-Il;Park, Myung-Ky
    • Journal of Korea Water Resources Association
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    • v.43 no.1
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    • pp.67-79
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    • 2010
  • Korea water resources corporation (K-Water) has developed the real-time water resources management system for the Nakdong and the Geum River basin to efficiently operate multi-purpose dams in the basins. This study has extended to the Han River basin for providing an effective ending target storage of a month to the real-time water resources management system using Sampling Stochastic Dynamic Programming (SSDP), consequently increasing the efficiency of the reservoir system. The optimization model were developed for three reservoirs, named Soyang, Chungju, and Hwacheon, with high priority in terms of the amounts of effective capacity and water supply for the basin. The number of storage state variable for each dam to set an optimization problem has been assigned from the results of sensitivity analysis. Compared with the K-water operating policy with the target water supply elevations, the optimization model suggested in this study showed that the shortfalls are decreased by 37.22 MCM/year for the required water demands in the basin, even increasing 171 GWh in hydro electronic power generation. In addition, the result of a reservoir operating system during the drawdown period applied to real situation demonstrates that additional releases for water quality or hydro electronic power generation would be possible during the drawdown period between 2007 and 2008. On the basis of these simulation results, the applicability of the SSDP model and the reservoir operating system is proved. Therefore, the more efficient reservoir operation can be achieved if the reservoir operating system is extended further to other Korean basins.

A study on the estimation of river water intake using the operating time of the pumping station (양수장의 가동시간을 이용한 하천수 취수량 산정방안 연구)

  • Baek, Jongseok;Kim, Chiyoung;Cha, Jun-Ho;Song, Jaehyun
    • Journal of Korea Water Resources Association
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    • v.53 no.2
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    • pp.89-96
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    • 2020
  • Water management agencies under the Ministry of Environment produce and accumulate qualified basic data for major rivers. However, the integrated management of the river water has been weak since the artificial water circulation process, such as the intaking and drainage of agricultural water, has not been examined in the basin, which includes many agricultural land. In this study, a study was conducted on how the power usage method (operating time method) based on the running time can be applied and improved among indirect flow rate measurement methods used to investigate flow rates collected by the riverside for agricultural water purposes, and thus the resultant data of high reliability can be obtained at low cost. The operation time method is suitable for small-scale water pumping stations where it is difficult to secure real-time power supply data. The reliability of the data was verified through the correlation analysis with the actual flow rate, and it was found that the flow rate calculated by the operation time method reflecting the level of the stream to which the inlet of the pumping station is connected can be reasonably matched with the actual flow rate. In addition, it was confirmed that the investment cost at the time of initial installation of the facility was highly efficient by generating qualified flow data at low cost through comparison with direct flow rate measurement methods. If flow data is secured by applying the operation time method to large and small water farms located along the riverside, it is expected that more quantitative and integrated stream water management will be possible.

A Traffic Pattern Matching Hardware for a Contents Security System (콘텐츠 보안 시스템용 트래픽 패턴 매칭 하드웨어)

  • Choi, Young;Hong, Eun-Kyung;Kim, Tae-Wan;Paek, Seung-Tae;Choi, Il-Hoon;Oh, Hyeong-Cheol
    • Journal of the Institute of Electronics Engineers of Korea CI
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    • v.46 no.1
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    • pp.88-95
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    • 2009
  • This paper presents a traffic pattern matching hardware that can be used in high performance network applications. The presented hardware is designed for a contents security system which is to block various kinds of information drain or intrusion activities. The hardware consists of two parts: the header lookup and string pattern matching parts. For implementing the header lookup part in hardware, the TCAMs(ternary CAMs) are popularly used. Since the TCAM approach is inefficient in terms of the hardware and memory costs and the power consumption, however, we adopt and modify an alternative approach based on the comparator arrays and the HiCuts tree. Our implementation results, using Xilinx FPGA XC4VSX55, show that our design can reduce the usage of the FPGA slices by about 26%, and the Block RAM by about 58%. In the design of string pattern matching part, we design and use a hashing module based on cellular automata, which is hardware efficient and consumes less power by adaptively changing its configuration to reduce the collision rates.

The Question of 'State and Art' with regard to Soviet Socialist Realism (소련 사회주의 리얼리즘에 관하여: '국민과 예술'의 문제)

  • Alexander, Morozov
    • The Journal of Art Theory & Practice
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    • no.7
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    • pp.125-163
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    • 2009
  • The artworks of Socialist Realism of the former Soviet Union, with the beginning of the 21st century, are gaining a new attention from art collectors. One reason for this might consist in the fact that relevant art pieces exemplify the ways in which they visualize ideas on the basis of their high-profile art tradition and also in which they integrate their utopian ideals with mysticism. These aspects of the Soviet art goes far beyond the wide-spread assumption that their art, as a means of propaganda, principally represents a political allegiance to the system. With Stalin coming into power in the 1930s, the artistic trend of Socialist Realism obtained a nationwide sympathy and support from people, giving birth to a new art which essentially corresponded to the demands of the political power. An official art current of the USSR over the period from the 1930s to 1950s, Socialist Realism was in tandem with the Communist commitment to the party and popularity, symbolizing a loyalty to the cause. It was thus characterized by plainness and lucidity so that ordinary people could gain easy access to art. Its salient feature, over an entire range of art, was an optimistic pursuit of a utopian dream. Therefore, it tallied with the popular sentiment for a Communist paradise, giving form to their beliefs in human agency working at the materialist world and also to such abstract concepts as force, fitness, and beauty by adding even mythical ideals. Its main subject matter includes harvest feasts of collective farms, imaginary socialist cities, grand marches of heroic laborers and in this way it served as a propaganda for a sacred utopia of socialist totalitarianism. On the other end of the spectrum, however, rose the second camp of art, which put an emphasis on bona-fide artistic activities of plastic art and on an artist's personal expression and freedom, as opposed to the surface optimism of Socialist Realism. Central to the Russian Avant Garde art, which prized the above-mentioned values, were Malevich's Geometric Abstraction and A. Rodchenko's Constructivism. Furthermore, in the transitional era of the late 20th century and the 21st century it was recognized that film art or electronic media art, rather than traditional genre of paintings, would function as a more efficient way of propaganda. These new genres were made possible by ridiculing the stereotypes of the Russian lifestyle and also by ignoring ethical or professional dimensions of artworks. That is, they reinvented themselves into a sort of field art, seemingly degrading the quality of artworks and transforming them into artifacts or simulacres in the very sense of post-modernism. The advent of the new era brought about the formation and occupation of pop culture of the younger generations, calling into question the idea of art as the class-determined. It also increased the attention to field art, which extensively found way to modern art centers, galleries, and exhibition projects. It can be stated that this was a natural outcome of human nature.

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Comparative Study on Energy Consumption in Steam-Humidification- and Water-Spray-Humidification-Type Outdoor Air-Conditioning Systems for Semiconductor Manufacturing Clean Rooms (반도체 클린룸용 증기가습 및 수분무가습 외기공조시스템의 에너지소비량 비교연구)

  • Kim, Hyung-Tae;Song, Gen-Soo;Kim, Ki-Cheol;Yoo, Kyung-Hoon;Son, Seung-Woo;Shin, Dae-Kun;Park, Dug-Jun;Kwon, Oh-Myung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.12
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    • pp.1249-1255
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    • 2011
  • In modern large-scale semiconductor manufacturing clean rooms, the energy consumed by the outdoor air-conditioning system during heating, humidification, cooling, and dehumidification of the incoming outdoor air represents about 45% of the total air-conditioning load required to maintain a clean-room environment. In particular, the energy required for humidification of the outdoor air in winter is very high. Therefore, evaluation and comparison of the energy consumption in key humidification systems, viz., steam-humidification and water-spray-humidification systems, used in outdoor air-conditioning systems would be useful to reduce the outdoor air-conditioning load in clean rooms. In the present study, an experiment with an outdoor air flow of 1000 $m^3$/h was conducted to compare the air-conditioning process and energy consumption in outdoor air-conditioning systems with electrodeboiler steam humidifiers and air-washer water spray humidification systems. The experimental results showed that the water-spray-humidification-type outdoor air-conditioning system consumed less electrical power than did the steam-humidification-type system and was more energy efficient during winter.

A Study on Seawater Flow Characteristics inside the Shrouds used in Tidal Current Generation Systems for Various Geometric Angles under Constant Tidal Current Velocity (조류발전 시스템용 쉬라우드의 형상각도별 일정 조류속도장 내 해수유동 특성연구)

  • Kim, Jong-Won;Lee, Sang-Ho
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.24 no.2
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    • pp.77-83
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    • 2012
  • Numerical analyses through Computational Fluid Dynamics have been performed to investigate the seawater flow field characteristics for various shrouds used in horizontal axis tidal current turbine systems. Seawater flow characteristics are largely influenced under constant tidal current velocity by the shroud geometry and there is considerable difference in fluid velocity distributions around the shrouds. Especially the location and magnitude of maximum seawater flow velocity directly affect turbine performance for power generation. For the cylinder-diffuser type shroud system whose cylinder and diffuser parts have the same length accelerated flow region is formed in the overall cylinder part while maximum velocity in the nozzle-diffuser type whose nozzle and diffuser parts have the same length with symmetry, locally appears near the minimum sectional area. In case of cylinder-diffuser type shroud fluid velocity increases rather high compared with current velocity. And fluid velocity at the centerline gradually increases from the entrance, and then decreases rapidly after reaching a peak close to the middle of the cylinder part unlike the nozzle-diffuser while there is not much variation near the rear of the shroud. These results of the seawater flow characteristics with various shroud geometries can be applied to optimal design for the development of efficient tidal current power generation systems.