• 한국해안해양공학회:학술대회논문집
• /
• 한국해안해양공학회 1993년도 정기학술강연회 발표논문 초록집
• /
• pp.38-41
• /
• 1993

본 모형은 미 공병단에서 개발한 Automated Coastal Engineering System(ACES)중에 포함되어 있는 것으로 바람자료로 부터 파랑을 손쉽게 추정하기 위한 것이다. 바람에 의한 파랑발달과정은 그 기구가 매우 복잡하여 아직도 그 일부만이 밝혀진 상해이다. 바람에 의한 파랑의 발생기구에 대한 연구와 이들 연구를 바탕으로 개발된 수치모형에 대해서는 Shore Protection Manual(SPM)(1984)에 잘 정리되어 있다. (중략)

• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 2007년도 한국우주과학회보 제16권1호
• /
• pp.74-74
• /
• 2007

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
• /
• pp.63-69
• /
• 2000

Korea Institute of Geology Mining and Materials(KIGAM) cooperating with Southern Methodist University(SMU) has been operating seismo-acoustic array in Chul-Won area to discriminate man-made explosions from natural earthquakes since at the end of July 1999. In order to characterize propagation parameters of detected seismo-acoustic signal and to associate these signals as a blast event accompanying seismic and acoustic signals simultaneously it is necessary to understand infrasound wave propagation in the atmosphere. Two comparable Effective Sound Velocity Structures(ESVS) in atmosphere were constructed by using empirical model (MSISE90 and HWM93) and by aerological observation data of Korea Meteorological Administration (KMA) at O-San area. Infrasound propagation path computed by empirical model resulted in rare arival of refracted waves on ground less than 200km from source region. On the other hand Propagation paths by KMA more realistic data had various arrivals at near source region and well agreement with analyzed seismo-acoustic signals from Chul-Won data. And infrasound propagation in specific direction was very influenced by horizontal wind component in that direction. Linear travel time curve drawn up by 9 days data of the KMA in autumn season showed 335.6m/s apparent sound velocity in near source region. The propagation characteristics will be used to associate seismo-acoustic signals and to calculate propagation parameters of infrasound wave front.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
• /
• pp.630-631
• /
• 2009

Recent developments such as concern over global warming, depletion of fossil fuels and increase in energy demands by the increasing world population has eventually lead to mass production of electricity using renewable sources. Apart from wind and solar, ocean holds tremendous amount of untapped energy in forms such as geothermal vents, tides and waves. The current study looks at generating power using waves and the focus is on the primary energy conversion (first stage conversion) of incoming waves for two different models. Observation of flow characteristics, pressure and the velocity in the augmentation channel as well as the front guide nozzle are presented in the paper. A numerical wave tank was utilized to generate waves of desired properties and later the turbine section was integrated. The augmentation channel consisted of a front nozzle, rear nozzle and an internal fluid region representing the turbine housing. The analysis was performed using the commercial CFD code.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
• /
• pp.938-941
• /
• 2006

Satellite synthetic aperture radar (SAR) images from 1995 to 2001 and field measurements of sea surface wind, sea state, and vertical stratification are used for statistical analyses of internal wave (IW) occurrence and SAR imaging conditions in the northern South China Sea (NSCS). Latitudinal distribution of IW packets shows that 22% of IW packets distributed in the east of $118^{\circ}E$ and 78% of IW packets in the west of $118^{\circ}E$. The yearly distribution of IW occurrence frequencies reveals an interannual variability. The monthly SAR-observed IW occurrence frequencies show that the high frequencies are distributed from April to July and reach a peak in June. The low occurrence frequencies are distributed in winter from December to February of next year. These statistical features are explained by solitary wave dynamics.

• International Journal of Ocean System Engineering
• /
• 제4권1호
• /
• pp.29-42
• /
• 2014

The objective of this paper is to present the implementation of a joint modeling system able to evaluate the propagation of the polluting agents in the marine environment. The system is composed by circulation model (Mohid) and a spectral wave model (SWAN). The results coming from the circulation model are provided as input to the SWAN simulations. Following this target the Mohid water circulation model was implemented and calibrated in the Black Sea basin. The current simulations were run for one year (2010) with a time step of 24 hours, using wind fields from ECMWF. The results concerning the current fields were introduced into SWAN, and the difference between the results of the SWAN simulations with and without the current input from Mohid was assessed. In this regard, 10 points where the significant wave height difference is higher were considered and analyzed. The conclusion of the work is that such a joint system provides more reliable results concerning the wave and current conditions in the Black Sea as it is very useful in providing the support in the case of the environmental alerts that may occur in marine environments.

• 한국유체기계학회 논문집
• /
• 제18권3호
• /
• pp.5-11
• /
• 2015

Ocean waves have huge amounts of energy, even larger than wind or solar, which can be extracted by some mechanical device. This can be done by creating a system of reacting forces, in which two or more bodies move relative to each other, while at least one body interacts with the waves. This moves the floater up and down. The floaters are connected to an arm structure, which are mounted on a fixed hull structure. Hence, the structure of the floater is very important. A static structural analysis with FSI (Fluid-Structure Interaction) analysis is conducted. To achieve the pressure load for the FSI analysis, the floater is simulated on a wave generator using rigid body motion. The structural analysis is done to examine the stresses on the whole system, and four types of flange and floater are optimized. The result shows that the structure of floater with wood support is the safest.

• 천문학회보
• /
• 제37권2호
• /
• pp.117.2-117.2
• /
• 2012

It is generally accepted that sudden compressions of the magnetosphere cause electromagnetic ion cyclotron (EMIC) wave growth by increasing the proton temperature anisotropy. These compression-associated EMIC waves are expected to be on higher latitudes (i.e., higher-L regions close to the magnetopause). In this study we examine Pc1 pulsations, which are believed to be generated by the EMIC instability, observed at subauroral latitude near the nominal plasmapause when the magnetosphere is suddenly compressed by solar wind dynamic pressure variations, using induction magnetometer data obtained from Athabasca, Canada (geomagnetic latitude = 61.7 N, L ~ 4.5). We identified 9 compression-associated Pc1 waves with frequencies of ~0.5-2.0 Hz. The wave activity appears in the horizontal H (positive north) and D (positive eastward) components. All of events show low coherence between H and D components. This indicates that the Pc1 pulsations in H and D oscillate with a different frequency. Thus, we cannot determine the polarization state of the waves. We will discuss the occurrence location of compression-associated Pc1 pulsations, their spectral structure, and wave properties.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
• /
• pp.331-334
• /
• 2011

램제트 엔진의 성능은 초음속 흡입구의 성능과 밀접한 연관이 있다. 초음속 흡입구 내부 유동 특성을 관찰하기 위해 실험적/전산해석적 연구를 수행하였다. 자발 시동이 가능한 2차원 실험 모델을 설계 제작하고 마하 2.5 초음속 풍동을 이용한 실험적 연구와 Menter's SST 난류 모델과 RANS 방정식에 기본한 전산해석 결과로부터 내부 유동 특성을 정리하였다. 흡입구의 안정 작동 조건에서의 의사충격파(Pseudo-shock wave)와 불안정 작동 조건의 버즈 현상에 대해 자세한 가시화 결과를 제시하였다.

• 한국해양공학회지
• /
• 제33권2호
• /
• pp.189-195
• /
• 2019

In this study, experiments with a floater using flapping foils were performed to develop a new station keeping system that can maintain its position in waves without mooring lines. The foils applied to this system generate thrust using wave energy. In this experiment, the motion of the floater was analyzed in three different wave periods. Sixteen foils were attached to the cylindrical floater. The thrust of each foil was controlled by changing its azimuth angle, and three cases were compared. Based on the previous data, we made more precise measurements and found an optimal model for stationkeeping under each wave condition. We verified the potential of this new stationkeeping system using flapping foils, and conclusions were drawn from the results.