• Title/Summary/Keyword: wave and current

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Analysis of Sediment Transport in the Gaeya Open Channel by Complex Wave Field (복합 파랑장에 따른 개야수로 퇴적물이동 분석)

  • Jang, Changhwan
    • Journal of Wetlands Research
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    • v.23 no.2
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    • pp.107-115
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    • 2021
  • In order to analyze wave propagation, tidal current, and sediment transport in the vicinity of the Gaeya open channel, it was classified into before(CASE1W) and after(CASE2W) installation of various artificial structures, and the calculation results for CASE1W and CASE2W were compared. For wave propagation, the results of incident and reflected waves were derived using the SWAN numerical model, and the tidal current velocity results were derived using the FLOW2DH numerical model for tidal current. The results of the SWAN numerical model and the FLOW2DH numerical model became the input conditions for the SEDTRAN numerical model that predicts sediment transport, and the maximum bed shear stress and suspended sediment concentration distribution near the Gaeya open channel were calculated through the SEDTRAN numerical model. As a result of the calculation of the SWAN numerical model, the wave height of CASE2W was increased by 40~50 % compared to CASE1W because the incident wave was diffracted and superimposed and the reflected wave was generated by about 7 km long northen jetty. As a result of the calculation of the FLOW2DH numerical model, According to the northen breakwater, the northen jetty and Geumrando, CASE2W was calculated 10~30 % faster than CASE1W in the tidal current of the Gaeya open channel. As a result of the calculation of the SEDTRAN numerical model, the section where the maximum bed shear stress is 1.0 N/m2 or more and the suspended concentration is 80mg/L or more was widely distributed in the Gaeya open channel from the marine environment by the complex wave field(incident wave, reflected wave and tidal wave) and the installation of various artificial structures. it is believed that a sedimentation phenomenon occurred in the Gaeya open channel.

Sensorless Control of IPMSM with a Simplified High-Frequency Square Wave Injection Method

  • Alaei, Ahmadreza;Lee, Dong-Hee;Ahn, Jin-Woo;Saghaeian Nejad, Sayed Morteza
    • Journal of Electrical Engineering and Technology
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    • v.13 no.4
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    • pp.1515-1527
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    • 2018
  • This paper presents a sensorless speed control of IPMSM (Interior Permanent Magnet Synchronous Motor) using the high-frequency (HF) square wave injection method. In the proposed HF pulsating square wave injection method, injection voltage is applied into the estimated d-axis of rotor and high-frequency induced q-axis current is considered to estimate the rotor position. Conventional square wave injection methods may need complex demodulation process to find rotor position, while in the proposed method, an easy demodulation process based on the rising-falling edge of the injected voltage and carrier induced q-axis current is implemented, which needs less processing time and improves control bandwidth. Unlike some saliency-based sensorless methods, the proposed method uses maximum torque per ampere (MTPA) strategy, instead of zero d-axis command current strategy, to improve control performance. Furthermore, this paper directly uses resultant d-axis current to detect the magnet polarity and eliminates the need to add an extra pulse injection for magnet polarity detection. As experimental results show, the proposed method can quickly find initial rotor position and MTPA strategy helps to improve the control performance. The effectiveness of the proposed method and all theoretical concepts are verified by mathematical equations, simulation, and experimental tests.

Analysis of Wave Parametric Characteristics using WAVEWATCH-III Model and Observed Buoy Data (파랑모델과 부이 자료를 이용한 파랑인자 특성 분석)

  • 장유순;서장원;김태희;윤용훈
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.8 no.3
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    • pp.274-284
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    • 2003
  • The analysis of wave parametric characteristics in sea regions in the vicinity of Korean Peninsula have been carried out using the third generation wave model, WAVEWATCH-III (Tolman, 1999) and four observed buoy data of Korea Meteorological Administration (KMA). Significant wave height increases about 2-3 hours later after the increase of wind speed. Maximum correlation coefficient between two parameters appears in Donghae buoy data, which is at off-shore region. When land breeze occurs, it can be found that the correlation coefficient decreases. Time differences between wind speeds and wave heights correspond to significant tidal periods at all of the buoy locations except for Donghae buoy. After verifying the WAVEWATCH-III model results by the comparing with observed buoy data, we have carried out numerical experiments near the Kuroshio current and East Sea areas, and then reconfirmed that when there exist an opposite strong current in the propagation direction of the waves or wind direction, wave height and length get higher and shorter, respectively and vice versa. It has been shown that these modulations of wave parameters are considerable when wind speed is week or mean current is relatively strong, and corresponding values have been represented.

Study on the Extraction of Ocean Wind, Wave and Current using SAR (SAR를 이용한 해풍, 파랑, 해류 추출 기법 연구)

  • Kang, Moon-Kyung;Park, Yong-Wook;Lee, Moon-Jin;Lee, Hoon-Yol
    • Journal of Navigation and Port Research
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    • v.31 no.1 s.117
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    • pp.35-42
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    • 2007
  • Recently satellite SAR techniques have become essential observation tools for various ocean phenomena such as wind, wave, and current. The CMOD4 and CMOD-IFR2 models are used to calculate the magnitude of wind at SAR resolution with no directional information. Combination of the wave-SAR spectrum analysis and the inter-look cross-spectra techniques provides amplitude and direction of the ocean wave over a square-km sized imagette, The Doppler shift measurement of SAR image yields surface speed of the ocean current along the radar looking direction, again at imagette resolution. In this paper we report the development of a SAR Ocean processor(SOP) incorporating all of these techniques. We have applied the SOP to several RADARSAT-1 images of the coast of Korean peninsula and compared the results with oceanographic data, which showed reliability of spaceborne SAR-based oceanographic research.

Study on the extraction of ocean wind, wave and current using SAR (SAR를 이용한 해풍, 파랑, 해류 추출 기법 연구)

  • Kang, Moon-Kyung;Park, Yong-Wook;Lee, Moon-Jin;Lee, Hoon-Yol
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.1
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    • pp.187-194
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    • 2006
  • Recently satellite SAR techniques have become essential observation tools for various ocean phenomena such as wind, wave, and current. The CMOD4 and CMOD-IFR2 models are used to calculate the magnitude of wind at SAR resolution with no directional information. Combination of the wave-SAR spectrum analysis and the inter-look cross-spectra techniques provides amplitude and direction of the ocean wave over a square-km sized imagette, The Doppler shift measurement of SAR image yields surface speed of the ocean current along the rador looking direction, again at imagette resolution. In this paper we report the development of a SAR Ocean processor (SOP) incorporating all of these techniques. We have applied the SOP to several RADARSAT-1 images of the coast of Korean peninsula and compared the results with oceanographic data, which showed reliability of spaceborne SAR-based oceanographic research.

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Characteristics of Seasonal Wave, Wave-Induced Current and Sediment Transport in Haeundae Beach (해운대 해수욕장의 계절별 파랑, 해빈류 및 퇴적물이동 특성)

  • Lee, Jong-Sup;Tac, Dae-Ho;Woo, Jin-Gap
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.19 no.6
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    • pp.574-585
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    • 2007
  • To analyze the incident wave characteristics around Haeundae beach the long-term deep water wave data computed by wave hindcast method were used and a continuous wave observation was carried out for 1 year at the 20 m of water depth in front of Haeundae beach. Wave observation data showd that the prevalent wave direction was SSW-S in spring and summer seasons while E-SE in autumn and winter. A numerical modeling shows that the waves from E-SE are refracted strongly due to the shoal developed at the south-east side of Haeundae beach. The simulation also shows inflowing nearshore current along the east coast of the beach develops strongly in autumn and winter. Radioactive isotope tracer experiment for 155 days indicated that the tracers moves to the on-shore direction in the 1st and 2nd tracking then dispersed to the E-W direction along the shore.

IPMSM Sensorless Control Using Square-Wave-Type Voltage Injection Method with a Simplified Signal Processing (구형파 신호 주입을 이용한 IPMSM 센서리스 제어에서 개선된 신호처리 기법)

  • Park, Nae-Chun;Kim, Sang-Hoon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.18 no.3
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    • pp.225-231
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    • 2013
  • This paper presents an improved signal processing technique in the square-wave-type voltage injection method for IPMSM sensorless drives. Since the sensorless method based on the square-wave voltage injection does not use low-pass filters to get an error signal for estimating rotor position and allows the frequency of the injected voltage signal to be high, the sensorless drive system may achieve an enhanced control bandwidth and reduced acoustic noise. However, this sensorless method still requires low-pass and band-pass filters to extract the fundamental component current and the injected frequency component current from the motor current, respectively. In this paper, these filters are replaced by simple arithmetic operations so that the time delay for estimating the rotor position can be effectively reduced to only one current sampling. Hence, the proposed technique can simplify its whole signal process for the IPMSM sensorless control using the square-wave-type voltage injection. The proposed technique is verified by the experiment on the 800W IPMSM drive system.

Determination of Frequency for decision of heavy metal ion concentration in Square Wave Voltammetry with FPGA SoC (FPGA SoC를 이용한 네모파 전압전류법의 주파수 변화에 따른 계측 분석)

  • Lee, Jaechoon
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.14 no.4
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    • pp.101-107
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    • 2018
  • In the stripping scan square wave voltammetry (SV+SWV) polarography that is often used to analyze the concentration of heavy metals in water, we must measure the point where the faradic current that flows by the pure oxidation-reduction reaction at the electrode is greater than the capacitive current, the frequency cannot be too high. Therefore we wanted to find the frequency range that can be measured. In order to do this, we came up with a method to analyze the signal using FPGA Soc. With this method, the frequency of the square wave was increased from 10Hz to 400Hz by 10Hz, and the measuring time of the square wave was changed from 96.695% to 96.765% by 0.005% while 1600 experiments were conducted. As a result, the frequency of the square wave maintained a stable area of potential-current within 320Hz and it was possible to measure the potential-current signal when calculating the measuring time within the frequency range of 96.7155%.

Extreme Value Analysis of Metocean Data for Barents Sea

  • Park, Sung Boo;Shin, Seong Yun;Shin, Da Gyun;Jung, Kwang Hyo;Choi, Yong Ho;Lee, Jaeyong;Lee, Seung Jae
    • Journal of Ocean Engineering and Technology
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    • v.34 no.1
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    • pp.26-36
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    • 2020
  • An extreme value analysis of metocean data which include wave, wind, and current data is a prerequisite for the operation and survival of offshore structures. The purpose of this study was to provide information about the return wave, wind, and current values for the Barents Sea using extreme value analysis. Hindcast datasets of the Global Reanalysis of Ocean Waves 2012 (GROW2012) for a waves, winds and currents were obtained from the Oceanweather Inc. The Gumbel distribution, 2 and 3 parameters Weibull distributions and log-normal distribution were used for the extreme value analysis. The least square method was used to estimate the parameters for the extreme value distribution. The return values, including the significant wave height, spectral peak wave period, wind speed and current speed at surface, were calculated and it will be utilized to design offshore structures to be operated in the Barents Sea.

A Study on The Frequency Allocation of WAVE for Smart Vehicle Industry (스마트 자동차 산업 발전을 위한 WAVE 통신용 주파수 분배에 대한 고찰)

  • Kim, Seungcheon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.6
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    • pp.183-189
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    • 2014
  • A recent trend of 'Smart Technology' has changed the simple and normal car into smart vehicle. Smart vehicle has a complex aspects of technologies and Wireless Access in Vehicular Environment (WAVE) is the technology that is mentioned for the communication infrastructure of Smart Vehicle. The current status about WAVE in Korea, however, is not good to be used in smart vehicular communication. The reason for that is that the frequency band for WAVE is not assigned or allocated in Korea. In this paper, we will explore the current status of technology standard for WAVE and investigate the way of frequency allocation for WAVE with the survey analysis from the smart vehicle industry.