• Title/Summary/Keyword: Rotating Source

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On the Development of a Microwave Navigational Aid System Suitable for Small Fishing Boats (마이크로파를 이용한 소형어선용 선위측정방식 개발에 관한 연구)

  • 정세모;이상집
    • Journal of the Korean Institute of Navigation
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    • v.3 no.1
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    • pp.47-77
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    • 1979
  • A microwave Navigational Aid system is suggested suitable for fishing boats too small to be equipped with Radar or Radio-Direction-Finder. The system proposed here is similar to that of Talking-Beacon developed in Japan, but the distinctive modification proposed is that an increase of sixteen times in peak transmitting power, thus an accompanying increase of coverage, is achieved with the same mean transmitting power as that of Japan without sacrificing the clearness of azimuth information, by adopting a pulse repetition modulation instead of pulse width modulation as in Japan system. An experimental land station transmitter of transmitting frequency of 9, 370MHz and of peak power of 35kw with a microwave beam of 1 degree in horizontal width and 7 degrees in vertical width rotating once every three minutes, and also an experimental receiver of 20-dB in sensitivity and of an assumed cost of 100 dollars, operated by a 12 volts battery source are made, and the sail test results are reported showing that a bearing infromation of an accuracy of within two degrees can be obtainable every three minutes at a distance of as far as 24 miles from the transmitter if the transmitter is located as high as 100 meters above sea-level.

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Analysis of Spectral Fatigue Damage of Linear Elastic Systems with Different High Cyclic Loading Cases using Energy Isocline (에너지 등고선을 이용한 고주파 가진 조건들에 따른 선형 시스템의 피로 손상도 분석)

  • Shin, Sung-Young;Kim, Chan-Jung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.11
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    • pp.840-845
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    • 2014
  • Vibration profiles consist of two kinds of pattern, random and harmonic, at general engineering problems and the detailed vibration test mode of a target system is decided by the spectral condition that is exposed under operation. In moving mobility, random responses come generally from road source; whereas the harmonic responses are triggered from rotating machinery parts, such as combustion engine or drive shaft. Different spectral input may accumulate different damage in frequency domain since the accumulated fatigue damage dependent on the pattern of input spectrum in high cyclic loading condition. To evaluate the sensitivity of spectral damage according to different loading conditions, a linear elastic system is introduced to conduct a uniaxial vibration testing. Measured data, acceleration and strain, is analyzed using energy isocline function and then, the calculated fatigue damage is compared by different loading cases, random and harmonic.

A Study on the Numerical Analysis of Magnetic Flux Density by a Solenoid for MIAB Welding (MIAB용접에서 코일에 의한 자속밀도 분포의 수치적 해석에 관한 연구)

  • Choe, Dong-Hyeok;Kim, Jae-Ung
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.12
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    • pp.73-81
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    • 2001
  • The MIAB welding uses a rotating arc as its heat source and is known as an efficient method fur pipe butt welding. The arc is rotated around the weld line by the electro-magnetic force resulting from the interaction of arc current and magnetic field. The electro-magnetic force is affected by magnetic flux density, arc current, and arc length. Especially, the magnetic flux density is an important factor on arc rotation and weld quality. This paper presents a 2D finite element model for the analysis of magnetic flux density in the actual welding conditions. The magnetic flux density is mainly dependent on gap between two pipes, the position of coil from gap center, exciting current, and relative permeability. Thus, the relations between magnetic flux density and main factors were investigated through experiment and analysis. Experiments were performed for the steel pipes(48.1mm O.D and 2.0mm thickness). The analysis results of magnetic flux density reveal that it increases with increasing exciting current, increasing relative permeability, decreasing distance from gap center to coil, and decreasing gap size. It is considered that the results of this study can be used as important data on the design of coil system and MIAB welding system.

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High Strength Slaughter Wastewater Treatment in a Novel Combined System of Hybrid-Rotating Biological Contactor and Biological Aerated Filter (Hybrid-RBC와 BAF의 조합공정을 이용한 고농도 도축폐수의 처리 특성)

  • Jung, Chan-Il;Ahn, Jo-Hwan;Bae, Woo-Keun;Kim, Seung-Jin
    • Journal of Korean Society of Environmental Engineers
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    • v.33 no.2
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    • pp.77-84
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    • 2011
  • This study was conducted to develop a novel combined system of a hybrid rotating biological contactor (RBC) process that was composed of an attached- and suspended- biomass reactor, followed by a settler and a biological aerated filter (BAF) column to treat a high strength slaughter wastewater. Long term influences of organic and nitrogen loading rates were investigated to see how the combined system worked in terms of the removal efficiency. A synthetic wastewater containing a pork cutlet steak source (commercially available) and swine blood was used to feed the combined system. The hybrid RBC process showed excellent removals: about 95% for soluble COD and 85% for ammonium nitrogen. However, the unsettled solids seriously deteriorated the removal efficiency of total COD (TCOD) and total nitrogen (TN) in the RBC process. A significant fraction of the TCOD and suspended solids (SS) was further removed in the BAF column although the effluent quality was still unsatisfactory, giving TCOD 300 mg/L, SS 180 mg/L and TN 59 mg/L. An addition of polyaluminium chloride into the RBC effluent improved the performance of the settler and BAF, producing an excellent quality of final effluent; TCOD 16.5 mg/L, SS 0 mg/L, TN 55.5 mg/L, TP 1.3 mg/L. Therefore, it was confirmed that the combined system of hybrid RBC and BAF could treat a high strength slaughter wastewater excellently.

Characteristics on the Incubation of Sulfur Compound-Oxidizing Strains Separated for the Removal of Malodor (악취제거를 위하여 분리한 황화합물 산화균주의 배양특성)

  • Lim, Dong Joon;Lim, Kwang-Hee
    • Korean Chemical Engineering Research
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    • v.47 no.6
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    • pp.788-794
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    • 2009
  • Both strains of KD-1212 and DAH-1056 were isolated and identified from animal manure-contaminated soil by screening bacterial strains for the removal of sulfur compound-malodor with such substrate as sodium thiosulfate or free sulfur. Then the characteristics on the incubation of these microbes were observed under various incubating-condition such as pH, temperature, aerobic or anaerobic, substrate(sulfur compound) concentration, nitrogen and carbon source and rotating speed for mixing, and the optimum incubating condition was established. The optimum pHs of KD-1212 and DAH-1056 were 7.0 and 4.0, respectively, and their optimum temperatures were in the range of $30{\sim}35^{\circ}C$. Another autotrophic strain, ED-1138, was isolated from contaminated soil. The strain DAH-1056 excelled a strain Thiobacillus sp. IW in eliminating hydrogen sulfide during the process of malodor-biofiltration with a fixed strain. The characteristics on the incubation of strain KD-1212 were observed under various substrate-concentrations, nitrogen and carbon sources. KD-1212 favored glucose and maltose, and yeast extract as carbon sources and nitrogen source, respectively. The optimum concentrations of substrate and nitrogen source were 25 mM of sodium thiosulfate and 0.5% yeast extract, respectively for the growth of strain KD-1212.

The Analysis and Implementation of Realistic Sound using Doppler Effect (도플러 효과를 이용한 실감 음향 분석 및 구현)

  • Yim, Yong-Min;Lim, Heung-Jun;Heo, Jun-Seok;Park, Jun-Young;Do, Yun-Hyung;Lee, Kangwhan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2017.05a
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    • pp.523-526
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    • 2017
  • In modern recently technology, 3D-Audio is used to enhance immersion in Virtual Reality. This includes interest of people about VR and AR, which related to the field of computer graphics. In fact, a lot of research has been carried out in recent years into a 3D sound field. However, the existing 3D generator device used for virtual reality does not contain Doppler effect occurred by the sound comes to or leave from a listener, while an angle from the listener and the altitude of the source sound are applied. Therefore, this paper present 3D real sound utilizing Doppler effect with spatial-rotation-speaker. We map the source sound in 3D-space into a real space where a user stays and present 3D real sound by manipulating with rotation angle, phase difference, sound output volume of the sound in 3D-space, according to the location of a virtual source sound. Utilizing both natural Doppler effect of rotating sound that is occurring by spatial-rotation-speaker and artificial Doppler effect generated by frequency-modulation of sound quality could improving the virtual reality for sound condition for perspective listening.

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Image Quality of a Rotating Compton Camera Evaluated by Using 4-D Monte Carlo Simulation Technique (4-D 전산모사 기법을 이용한 호전형 컴프턴 카메라의 영상 특성 평가)

  • Seo, Hee;Lee, Se-Hyung;Park, Jin-Hyung;Kim, Chan-Hyeong;Park, Sung-Ho;Lee, Ju-Hahn;Lee, Chun-Sik;Lee, Jae-Sung
    • Journal of Radiation Protection and Research
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    • v.34 no.3
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    • pp.107-114
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    • 2009
  • A Compton camera, which is based on Compton kinematics, is a very promising gamma-ray imaging device in that it could overcome the limitations of the conventional gamma-ray imaging devices. In the present study, the image quality of a rotating Compton camera was evaluated by using 4-D Monte Carlo simulation technique and the applicability to nuclear industrial applications was examined. It was found that Compton images were significantly improved when the Compton camera rotates around a gamma-ray source. It was also found that the 3-D imaging capability of a Compton camera could enable us to accurately determine the 3-D location of radioactive contamination in a concrete wall for decommissioning purpose of nuclear facilities. The 4-D Monte Carlo simulation technique, which was applied to the Compton camera fields for the first time, could be also used to model the time-dependent geometry for various applications.

Analysis on Noise of Automotive Alternator Considering the Number of Stator Slots (승용차용 교류발전기의 고정자 슬롯 수가 소음에 미치는 영향 분석)

  • Song, Jin-Seo;Kim, Gwang-Jun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.1 s.173
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    • pp.126-133
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    • 2000
  • Noise of automotive alternators can be classified into mechanical noise, aerodynamic noise and electro-magnetic noise. which is the same as for electric motors. Previous studies show that the elect ro-magnetic noise takes a maw peak at the rotating frequency multiplied by the number of stator slots. It has not been proved clearly so far, however, that the major peak is wholely due to the stator slots. On the contrary it is well known that noise of motors. which has a mechanism similar to the alternator except that the number of stator slots in automotive alternators is in gene\integer multiple of that of rotor segments, is closely related to the number of rotor slots. Therefore, the statement that only the stator slots is the source of the major peak in the noise spectrum of alternators is suspicious although not easy, to show theoretically, that the statement is incorrect. In this paper. effects of the stator slots on the noise in an automotive alternator are experimentally investigated by intentionally modifying the number of stator slots in such a way that the number of the states is not an integer multiples of the rotor slots. It is shown that both the stator slots are not so much influential as the rotor slots and claimed that the major peak in the noise spectrum of conventional alternators is due to superposition of a component caused by the stator and a higher harmonic component caused by the rotor

A Numerical Study of the Effects of Design Parameter upon Fan Performance and Noise (원심홴의 설계 변수가 홴의 성능과 소음에 미치는 영향의 수치적 연구)

  • Jeon, Wan-Ho;Lee, Duck-Joo
    • The KSFM Journal of Fluid Machinery
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    • v.2 no.3 s.4
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    • pp.45-51
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    • 1999
  • Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise due to the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan and to calculate the effects of rotating velocity, flow rate, cut-off distance and the number of blades and its effects on the noise of the fan. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated with the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The cut-off distance is the most important factor effecting the noise generation. Acoustic pressure is proportional to 2.8, which shows the same scaling index as the experimental result. In this paper, the cut-off distance is found to be the dominant parameter offecting the acoustic pressure.

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Study on the Electromagnetic Excitation System for the Measurement of Dynamic Coefficients of Air Foil Bearing for High Speed Rotor (초고속 회전체용 공기 포일 베어링의 동특성 계수 측정을 위한 전자석 가진장치에 관한 연구)

  • Park, Cheol-Hoon;Choi, Sang-Kyu;Ham, Sang-Yong
    • The KSFM Journal of Fluid Machinery
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    • v.16 no.3
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    • pp.18-25
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    • 2013
  • Recently the requirement of long-term mobile energy source for mobile robot or small-sized unmanned vehicle is highly increased, and the micro turbine generator(MTG) which is known to have high energy and power density is under development. MTG is designed to have air foil bearing and high speed rotor of which operating speed is 400,000rpm. In the development stage of high speed rotor and bearing, stability analysis for the full operational speed range is essential and the dynamic coefficients such as stiffness and damping coefficients of bearing depending on the rotational speed are required for that. Although perturbation method is usually used to identify the dynamic coefficients, it's not easy to give the perturbation to the high speed rotating rotor. In this study, we present the dynamic coefficients measurement system for air foil bearing which consists of electromagnets, gap sensors, high speed motor and controller. This measurement system can exert the sine sweep force to the rotor-bearing, measure the displacement of rotor and get FRF(Frequency response function) of rotor-bearing. The least square estimation method is applied to identify the dynamic coefficients of bearing from the measured frequency response at the different rpm and the identified dynamic coefficients for the wide rotational speed range are presented.