• Title/Summary/Keyword: Focal Position

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A Study on the Declination According to Length of Utterance, Clause Boundary and Focus in Korean (한국어의 발화 길이 및 절 경계와 초점에 의한 점진하강(declination) 연구)

  • Kwak, Sook-Young
    • Phonetics and Speech Sciences
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    • v.2 no.3
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    • pp.11-22
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    • 2010
  • The present study attempts to investigate declination in Korean and its relevant aspects to the length of utterance, the clause boundary, and focus. More specifically, I examine the relation of declination with the length of utterance, the declination reset at the clause boundary, and the effect of focus on declination. Results showed that the length of utterance had no relation with the first and last pitch values of the utterance but that they were consistent regardless of the length of utterance. However, the declination slope changed to be relatively gentle from the fourth accentual phrase to the end of the whole intonational phrase. There was a reset of declination in such a way that the first pitch in the second phrase was always lower than that of the first phrase, but the first pitch in the third phrase was not always lower than that of the second phrase when the whole utterance was composed of three phrases. Finally, the pitch values of the focusing words decreased as their position went back in a sentence. One declination line was formed in the case of focused utterance, but in the case of an utterance that contained a clause boundary, a new declination line was formed at the start of each new clause. These findings can be applied to developing a Korean speech synthesizer that contains natural prosody; they can be also utilized for teaching Korean prosody.

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Comparison of Welding Characteristics of Austenitic 304 Stainless Steel and SM45C Using a Continuous Wave Nd:YAG Laser (오스테나이트계 스테인리스강과 SM45C의 연속파형 Nd:YAG 레이저 용접특성비교)

  • 유영태;오용석;노경보;임기건
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.3
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    • pp.58-67
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    • 2003
  • Welding characteristics of austienite 304 stainless and SM45C using a continuous wave Nd:YAG laser n experimentally investigated Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much Inter than those involved in conventional welding processes, leading to a rather small weld zone. Experiments are performed for 304 stainless steel plates changing several process parameter such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between the similar and dissimilar and plates, etc. The Nd:YAG laser welding process is one of the most advanced manufacturing technologies owing to its high speed and penetration. This paper describes the weld ability of SM45C carbon steel for machine structural use by Nd:YAG laser. The follow conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/aspect ratio and hence a decrease in the fusion zone size. The penetration depth increased with the increase in laser power.

Analysis of Soret-type Fresnel Zone Plate Lens Antenna using TLM method (TLM법을 이용한 Soret 타입 프레넬 존 플레이트 렌즈 안테나 해석)

  • Kim, Tae-Yong;Jo, Heung-Kuk
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.6
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    • pp.1221-1226
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    • 2011
  • In order to analyze the receiver gain characteristic of the Soret-type FZPL lens antenna which is operated at 12GHz, TLM method can be applied. The application of the FZPL lens antenna is often use the receiver for satellite TV system, radio telescope, and Geodetic System. Some numerical results computed by TLM method are compared with Kirchhoff's approximation and PO method. The focal characteristic of receiver gain on main axis of the FZPL is mostly shown at the front side, which means that the position of the receiver should be properly calibrated.

A Study on the Weldability for fillet joint of light weight alloy 5mm Al 5083 using Hybrid(CW Nd:YAG Laser+MIG) Welding

  • Park, Ho-Kyoung;Bang, Hee-Seon;Rajesh, S.R.;Oh, Chong-In;Bang, Han-Sur
    • Proceedings of the KWS Conference
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    • 2006.10a
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    • pp.216-218
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    • 2006
  • The application of aluminium alloy is increasing for lightweight and high quality transport vehicle. In this study, therefore, it is intended to apply the high speed hybrid welding method for marine grade aluminium alloy(A5083) used for shipbuilding that consists of 3 kW CW Nd:YAG laser and MIG welding process. For this purpose, the characteristics of process parameters(laser & arc combine angle and focal position of hybrid head to specimen) are investigated for hybrid fillet joint. This study also describes determination of heat distribution using finite element model of the T-joint fillet weld using the in-house solver which has been validated for different type of welding problems.

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Imaging with terahertz electromagnetic pulses (테라헤르츠 전자기파 펄스의 변조를 이용한 이미징의 해상도 연구)

  • Oh, Seung-Jae;Kang, Chul;Son, Ju-Hyuk
    • Korean Journal of Optics and Photonics
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    • v.15 no.1
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    • pp.46-50
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    • 2004
  • Images were acquired by the modulation of terahertz electromagnetic signals and compared by modulation frequencies. For the real-time acquisition of images a fast scanning method has been adopted utilizing a galvanometer. The acquired time domain waveforms were transformed into frequency domain data by fast Fourier transformations (FFT). We chose some frequency components to compare the resolution of images. The beam profiles at the focal position were measured by a knife-edge technique. Beam diameter was shown to decrease as the frequency increased. By scanning one- and two-dimensional samples a significant image enhancement was observed with the frequency increment. A nondesouctive imaging system using ㎔ electromagnetic pulses was also demonstrated.

Theoretical Limits Analysis of Indoor Positioning System Using Visible Light and Image Sensor

  • Zhao, Xiang;Lin, Jiming
    • ETRI Journal
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    • v.38 no.3
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    • pp.560-567
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    • 2016
  • To solve the problem of parameter optimization in image sensor-based visible light positioning systems, theoretical limits for both the location and the azimuth angle of the image sensor receiver (ISR) are calculated. In the case of a typical indoor scenario, maximum likelihood estimations for both the location and the azimuth angle of the ISR are first deduced. The Cramer-Rao Lower Bound (CRLB) is then derived, under the condition that the observation values of the image points are affected by white Gaussian noise. For typical parameters of LEDs and image sensors, simulation results show that accurate estimates for both the location and azimuth angle can be achieved, with positioning errors usually on the order of centimeters and azimuth angle errors being less than $1^{\circ}$. The estimation accuracy depends on the focal length of the lens and on the pixel size and frame rate of the ISR, as well as on the number of transmitters used.

A Study on the Surface Hardening of SCM4 Steel Using a Continuous Wave Nd:YAG Laser (연속파형 Nd:YAG 레이저를 이용한 SCM4강의 표면경화에 관한 연구)

  • Na, Gi-Dae;Shin, Byung-Heon;Shin, Ho-Jun;Yoo, Young-Tae
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.5
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    • pp.24-32
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    • 2007
  • Laser surface hardening is beneficially used for surface treatment of structural steel. Due to very rapid heating and cooling rates, structural low-alloy steel(SCM4) can be hardened as self quenching. The aim of this research project is to improve the influence of the process laser parameters: laser power, spot size, surface roughness, and traverse speed. The laser beam is allowed to scan on the surface of the workpiece at the constant power(1095W), varying the traverse speed at 0.3m/min, 0.5m/min and 0.8m/min. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with uniform hardness. From the results of the experiment, it has been shown that the stable hardness is about 600$\sim$700Hv, when the laser power, focal position and the traverse speed are P=1095W, z=0mm and v=0.3m/min.

Acoustic Field Analysis of Ultrasonic Focusing Transducer by Using Finite Element. Method and Hybrid Type Infinite Element Method (유한요소법과 하이브리드형 무한요소법을 이용한 초음파 집속변환자의 음장 해석)

  • Park, Soon-Jong;Yoon, Jong-Rak;Ha, Kang-Lyeol;Kim, Chun-Duck
    • The Journal of the Acoustical Society of Korea
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    • v.14 no.5
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    • pp.36-43
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    • 1995
  • This paper presents the lousing characteristics and the time. response of ultrasonic focusing transducer which is a coupled system with an electromechanical and an acoustical component. The Finite Element Method and the Hybrid Type Infinite Element Method are applied for the analysis. The position of the focal points and the resolutions is obtained from the loosing characteristics and the time response. It is found that the transducer with the damper, which stabilizes the displacement of the radiation surface, gives a better resolution. In conclusion, the results could be applied to the design and the performance analysis of the ultrasonic focusing transducer.

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Effect Analysis in Laser Metal Deposition of SKD61 by Track Pitch (트랙 이행거리에 따른 SKD61 재질의 레이저 메탈 디포지션 기초 특성 분석)

  • Kim, Won-Hyuck;Jung, Byung-Hun;Oh, Myeong-Hwan;Choi, Seong-Won;Kang, Dae Min
    • Journal of Power System Engineering
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    • v.18 no.5
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    • pp.94-99
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    • 2014
  • In this study, AISI M2 powder was selected primarily through various literature in order to improve the hardness and wear resistance. Among the laser metal deposition parameters, laser power was studied to improve the deposition efficiency in the laser metal deposition using a diode pumped disk laser. SKD61 hot work steel plate and AISI M2 powder were used as a substrate and powder for laser metal deposition, respectively. Fixed parameters are CTWD, focal position, travel speed, powder feed rate, etc. Experiments for the laser metal deposition were carried out by changing laser power. Through optical micrographs analysis of cross-section in LMD track, effect of the major parameters were predicted by track pitch. As the track pitch increased, so the reheated zone width, the overlap width and the minimum thickness was decreased. The hardness was decreased in the HAZ area, the hardness in the reheated HAZ area was decreased significantly and regularly in particular.

VRML image overlay method for Robot's Self-Localization (VRML 영상오버레이기법을 이용한 로봇의 Self-Localization)

  • Sohn, Eun-Ho;Kwon, Bang-Hyun;Kim, Young-Chul;Chong, Kil-To
    • Proceedings of the KIEE Conference
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    • 2006.04a
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    • pp.318-320
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    • 2006
  • Inaccurate localization exposes a robot to many dangerous conditions. It could make a robot be moved to wrong direction or damaged by collision with surrounding obstacles. There are numerous approaches to self-localization, and there are different modalities as well (vision, laser range finders, ultrasonic sonars). Since sensor information is generally uncertain and contains noise, there are many researches to reduce the noise. But, the correctness is limited because most researches are based on statistical approach. The goal of our research is to measure more exact robot location by matching between built VRML 3D model and real vision image. To determine the position of mobile robot, landmark-localitzation technique has been applied. Landmarks are any detectable structure in the physical environment. Some use vertical lines, others use specially designed markers, In this paper, specially designed markers are used as landmarks. Given known focal length and a single image of three landmarks it is possible to compute the angular separation between the lines of sight of the landmarks. The image-processing and neural network pattern matching techniques are employed to recognize landmarks placed in a robot working environment. After self-localization, the 2D scene of the vision is overlaid with the VRML scene.

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