• 제목/요약/키워드: far field

검색결과 1,917건 처리시간 0.023초

가로흐름 수역으로 방출되는 3차원 온배수 난류모형 (A Three-Dimensional Turbulence Model far the Thermal Discharge into Cross-Flow Field)

  • 이남주;최흥식;허재영
    • 한국해안해양공학회지
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    • 제7권2호
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    • pp.148-155
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    • 1995
  • 가로흐름이 존재하는 무한수역으로 방출되는 표면 온배수에 의한 온도장 예측을 위하여 k-$\varepsilon$ 난류모델을 이용한 근해역 3차원 온배수 수치모델을 개발하였다. 개발된 모델에 의한 수치실험 결과는 다소 제한적이긴 하나, 실험결과 자료와 비교적 잘 일치하였다. 3차원 온배수 난류모델의 적용을 통해 가로흐름과 상호작용은 물론 수심적분 2차원 수치모델에서 해석이 곤란한 온배수 확장에 따른 성층화 현상, 부력에 기인된 횡방향의 중력확장 및 제트 저면에서의 포획연행 현상을 잘 나타내었다.

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CSP-DH 구조 반도체 레이저의 캐리어 확산 방정식을 위한 모델링 (The Carrier Diffusion Modeling of CSP-DH Semiconductor Laser Structures)

  • 이상태;전현성;이찬용;엄금용;윤종욱;윤석범;오환술
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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    • pp.469-471
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    • 1988
  • The basic modeling is analyzed on the optoelectronic properties of CSP-DH laser structure using self-consistent calculation of optical field and the electron-hole distribution in the active region. Laser properties is modelled include gain profile, threshold, near field and far field pattern. This new characterization is allowed for consideration such as carrier spatial hole burning due to strong optical fields which stimulate recombination.

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월성원전 구조물의 지진응답 특성 분석 (Analysis of Seismic Response Characteristics for Wolsong Nuclear Power Plant Structures)

  • 허택영
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 1997년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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    • pp.90-97
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    • 1997
  • The purpose of this study is to evaluate the seismic response characteristics of Wolsong nuclear power plant (NPP) structures for the Kyeongju earthquake(ML=4.3) occurred on June 26, 1997. The seismograms are obtained from five accelerographs of nuclear power plant at Wolsong, Kyeongbuk. The distance from the epicenter is about 25km. The peak acceleration (PA) due to the earthquake is 0.0235g, which is far lower value than that of design basis earthquake(DBE). The PA at the containment wall is about twice as large as that at free field. Also, the higher the accelerograph is located in, the larger the PA is measured to be From the response spectrum analysis, the dominant frequency of the response is close to 4 Hz, which is similar to the free field is poor because of contamination by high frequency waves as a result of reflection and diffraction between ground and NPP structure. We are of opinion that the accelerograph at the free field should be moved approximately twice the building dimension away from the containment structure.

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천해 수중소음의 수평적 상관관계 (Horizontal Cross Correlation of Shallow Water Noise)

  • 이효근;김영선;김성부
    • 한국음향학회지
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    • 제2권1호
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    • pp.35-40
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    • 1983
  • 수심 65m의 godutr에서 해면으로부터 10m 깊이에 수평 청음기 배열을 설치하여 수중소음의 상 관관계를 측정하였다. 분석은 FFT 방식을 이용하여 63Hz에서 315Hz 까지의 저주파 영역에서 True 상 관계수를 직접 얻었다. Buckingham의 천해모델과 비교한 결과 160 Hz 이하에서는 이론치와 거의 같았 으나 200Hz 이상에서는 이론치와 많은 차이를 보였다. 이는 200 Hz 이상에서 결과치의 Zero-Crossing point 가 이동된 것을 보보인면이나 Kuperman과 Ingenito의 천해 모델에서 NEAR-FIELD의 영향이 Zero-crossing point를 이동시킨다는 사실, 또 주파수가 높아질수록 해상상태의 영향을 받는다는 심해 수중소음의 상관관계에 대한 싫머결과등을 비교해 볼 Eio near-field 소음원의 영향을 무시한채 far-field 소음원의 영향만을 고려한 Buckingham의 천해모델이 갖는 제한성을 나타낸 것이라 볼 수 있다.

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정형 모서리 구조를 갖는 옵\ulcornerV 파라볼릭 안테나의 산란 특성 해석 (The Analysis of Scattering Characteristics of a Prime-focus Offset Parabolic Antenna with a Shaped Edge Structure)

  • 박대성;김형규;최재훈
    • 한국전자파학회논문지
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    • 제10권3호
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    • pp.412-418
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    • 1999
  • 기하학적 균일 회절 이론 (Uniform Geometrical Theory of Diffraction)을 이용하여 옵\ulcorner 파라볼릭 안테나의 산란 특성을 분석하였다. 먼저 파추적법(Ray Tracing)에 의하여 음영경계를 나눈후, 각 영역에 존재하는 반사파와 회절파를 기하학적 균일 회절 이론을 이용해 구하였다. 또한, 옵\ulcorner 파라볼릭 안테나의 모서리(edge)의 형태가 전자파의 산란 특성에 미치는 영향을 알아보기 위해 knife 모서리인 경우와 원형 캡을 부착한 경우를 분석하여 비교하였다.

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Applications of Field-Effect Transistor (FET)-Type Biosensors

  • Park, Jeho;Nguyen, Hoang Hiep;Woubit, Abdela;Kim, Moonil
    • Applied Science and Convergence Technology
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    • 제23권2호
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    • pp.61-71
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    • 2014
  • A field-effect transistor (FET) is one of the most commonly used semiconductor devices. Recently, increasing interest has been given to FET-based biosensors owing totheir outstanding benefits, which are likely to include a greater signal-to-noise ratio (SNR), fast measurement capabilities, and compact or portable instrumentation. Thus far, a number of FET-based biosensors have been developed to study biomolecular interactions, which are the key drivers of biological responses in in vitro or in vivo systems. In this review, the detection principles and characteristics of FET devices are described. In addition, biological applications of FET-type biosensors and the Debye length limitation are discussed.

계통상태를 고려한 송전선의 ELF 전자계 (ELF Electric and Magnetic Fields under the Transmission Line Including Electric Power System States)

  • 김두현;김상철
    • 한국안전학회지
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    • 제11권3호
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    • pp.89-96
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    • 1996
  • This paper presents a study on the analysis and evaluation for ELF( Extremely Low Frequency) electric and magnetic fields under the transmission line according to the power system states. The power system states are classified into two types, normal state resulting from normal operation and alert state from outages. The current in a system is changed continually owing to the load fluctuations even in a normal operation. To calculate the current of the concerned line in a normal state, the system load level is devided into light, base and heavy load level. In case of contingency, an efficient algorithm based on matrix inversion lemma is developed to figure out the current changes. In order to analyze the variations of ELF field caused by the current fluctuations the electrostatic field approach which is far simpler than the electromagnetic field one based on Maxwell equation is introduced in this paper. The suggested method is applied to the IEEE 14 bus system to demonstrate the usefulness.

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유전자 알고리즘을 이용한 무인잠수정의 와조류장에서의 전역경로계획 (Global Path Planning for an Autonomous Underwater Vehicle in a Vortical Current Field by Using Genetic Algorithm)

  • 이기영;김수범;송찬희
    • 한국군사과학기술학회지
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    • 제16권4호
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    • pp.473-480
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    • 2013
  • The purpose of this paper is to demonstrate that the genetic algorithm can be useful for the global path planning when the obstacles and current field data are given. In particular, the possibilities for a novel type small AUV mission deployment in tidal regions, which experience vortical currents, were examined. Experimental simulations show feasibility and effective in generate the global path regardless of current and obstacles. By choosing an appropriate path in space, an AUV may both bypass adverse currents which are too fast to be overcome by the vehicle's motor and also exploit favorable currents to achieve far greater speeds than motors could otherwise provide, while substantially saving energy.

Estimation of a mixed-mode cohesive law for an interface crack between dissimilar materials

  • Song, Sung-Il;Kim, Kwang-Soo;Kim, Hyun-Gyu
    • Multiscale and Multiphysics Mechanics
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    • 제1권1호
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    • pp.35-51
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    • 2016
  • In this paper, a mixed-mode cohesive law for an interface crack between epoxy and TR (transparent thermoplastic) resin is inversely estimated by the field projection method using numerical solutions and experimentally measured displacements. Displacements in a region far away from the crack tip are measured by digital image correlation technique. An inverse analysis, the field projection method formulated from the interaction J- and M-integrals with numerical auxiliary fields, is carried out to estimate a mixed-mode cohesive law for an interface crack between dissimilar materials. In the present approach, nonlinear deformations and damage near the crack tip are converted into the relationships of tractions and separations on crack surfaces behind the crack tip. The phase angle of mixed-mode singularities of the interface crack is also obtained from measured displacements in this study.

Efficiency of Exponential Deperm Protocol

  • Kim, Yongmin;Kim, Young-Hak;Shin, Kwang-Ho
    • Journal of Magnetics
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    • 제18권3호
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    • pp.326-330
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    • 2013
  • Magnetic treatment of surface vessels and submarines (Deperm) is required to camouflage them against magnetic detection from enemy marine force. So far, deperm has been accomplished by applying an alternating magnetic field of which amplitude decreases linearly. However, the reduction of the residual flux density in the direction of magnetic field is not linear in the case of the linear protocol, since the ferromagnetic material used to construct a surface vessel, mainly Fe-C, shows a nonlinear behavior in an alternating magnetic field. This is one of main reasons to make an ordinary deperm protocol inefficient. In this paper, we propose the exponential deperming protocol and compare the exponential protocol to conventional linear protocol within the framework of deperm performance. We found out that step number could be reduced in the exponential protocol compare with in the linear protocol, because the larger numbers of deperm steps are dedicated in the irreversible domain process region on the magnetic hysteresis.