• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제6권1호
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• pp.15-21
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• 2003

A common feature in the three-dimensional numerical model experiments of coastal discharge with simplified model and idealized external forcings is investigated. The velocity fields due to the buoyancy and flaw flux, are spreaded radiately and the surface velocites are much greater than the homegeneous discharges. The coastal dischargd due to the Coriolis force and flaw flux are shaped a anticyclical gyre (clockwise) and determined the scale of the gyre in the coastal zone, respectively. The bottom topography restricts a outward extention of the coastal fronts and it accelerates a southward flow.

• Smart Structures and Systems
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• 제4권2호
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• pp.123-135
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• 2008

Damping capacity of SMA damping devices is simulated numerically under distinct geometry and loading conditions. Two-dimensional numerical simulations are performed on the basis of a phenomenological model of dynamics of martensite-austenite phase boundaries. Results of the simulations predict the time delay and the value of the stress transferred to other parts of a construction by a damper device.

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2000년도 추계수산관련학회 공동학술대회발표요지집
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• pp.164-164
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• 2000

일반적으로 해양에서 전선이란 서로 다른 수괴간의 불연속면을 일컫는다. 이러한 전선의 양측 면에는 유속, 수온, 염분, 수질 등이 급변한다. 본 연구는 1997년 8월 26일부터 9월 2일까지 제주도 서부에서 중국 상해 양쯔강 하구역까지 21개 정점에서 관측된 물리ㆍ화학적 관측자료로부터 연안과 외양간의 수온, 염분, 밀도 등 물리적 인자 특성으로부터 전선역을 찾아내고 전선역을 중심으로 양측의 수질특성을 용존산소, 인산염, 질산염, 규산염 등 영양염류의 분포 특성과 아울러 생산력 인자인 엽록소 a의 분포량을 파악하여 전선역을 중심으로 한 수괴간의 특성을 규명하였다

• Composites Research
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• 제12권5호
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• pp.23-30
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• 1999

Fiber reinforced composite materials are widely used in automotive industry to produce parts that are large, thin, lightweight, strong and stiff. It is very important to know a charge shape in order to have good products in the compression molding. In particular, the product such as a bumper beam is composed of the random and unidirectional fiber mats. The characteristics of flow fronts such as a bulging phenomenon for random mat and unidirectional fiber mat and slip parameters are studied numerically. And the effects of viscosity ratio and stack type on mold filling parameters are also discussed.

• Bulletin of the Korean Chemical Society
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• 제21권12호
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• pp.1213-1216
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• 2000

Localized structures with fronts connecting a Turing patterns and Hopf oscillations are found in discrete reaction-diffusion system. The Chorite-Iodide-Malonic Acid (CIMA) reaction model is used for a reaction scheme. Localized structures in discrete reaction-diffusion system have more diverse and interesting features than ones in continuous system. Various localized structures can be obtained when a single perturbation is applied with variation of coupling strength of two intermediates. Roles of perturbations are not so simple that perturbations are sources of both Turing patterns and Hopf oscillating domains, and spatial distribution of them is determined by strength of a perturbation applied initially.

• 대기
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• 제14권4호
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• pp.3-18
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• 2004

Neglecting the vertical transport from the surface, most of the previous studies on the long-range transport of pollutants have only considered the horizontal transport caused by the free atmosphere wind. I used a three dimensional numerical model, MM5 (The fifth generation Penn State Univ./NCAR Mesoscale Model) for the simulation of vertical transport of pollutants and investigated the mechanism of the vertical transport of atmospheric pollutants between planetary boundary layer(PBL) and free atmosphere by fronts. From the three dimensional simulation of MM5, the amount of pollutants transport from PBL to free atmosphere is 48% within 18 hour after the development of front, 55% within 24 hour, and 53% within 30 hour. The ratios of the vertically transported pollutant for different seasons are 62%, 60%, 54%, and 43% for spring, summer, fall, and winter, respectively. The most active areas for the vertical transport are the center of low pressure and the warm sector located east side of cold front, in which the strong upward motion slanted northward occurs. The horizontal advection of pollutants at the upper level is stronger than at the lower level simply because of the stronger wind speed. The simulation results shows the well known plum shape distribution of pollutants. The high concentration area is located in the center and north of the low pressure system, while the second highest concentration area is in the warm sector. It is shown that the most important mechanism for the vertical transport is vertical advection, while the vertical diffusion process plays an important role in the redistribution of pollutants in the PBL.

• 한국가스학회지
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• 제17권1호
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• pp.13-18
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• 2013

높이/길이 비가 0.86을 가지는 폭발챔버 내에서 전파하는 화염과 서로 다른 형태의 다중 장애물 사이의 상호작용을 조사하기 위해 폭발실험을 수행하였다. 챔버 내에 장애물 형태는 삼각기둥, 사각기둥 및 원통형으로 변화시켰으며, 장애물의 blockage ratio는 0.43으로 하였다. 전파하는 화염과 장애물 형태에 따른 상호작용을 조사하기 위해 고속카메라를 사용하였으며, 고속카메라로 얻어진 화염 이미지로부터 장애물 주위의 국부 화염속도 및 그 화염속도의 확률밀도함수를 계산하였다. 실험결과, 장애물 형태가 삼각형이었을 때 국부 화염속도가 가장 높게, 원형에서는 가장 낮게 나타났으며, 장애물 후류에서의 국부 화염속도는 장애물 형태에 큰 의존성을 가지는 것으로 나타났다. 또한, 전파하는 화염이 장애물 후류의 미연소가스의 유동과 상호작용할 때 국부 화염속도의 확률밀도함수는 화염속도가 높은 방향으로 광범위하게 분포되는 것으로 나타났다.

• 한국수산과학회지
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• 제47권4호
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• pp.424-430
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• 2014

Two major temperature fronts, the Subpolar (Gosung, Gang-won-do; $38^{\circ}-41^{\circ}N$) and Thermal (Jukbyun, Gyeong-sang-buk-do; $36^{\circ}-37^{\circ}N$) fronts, are found in the East Sea along the east coast of Korea. These are located roughly where the Tsushima Warm Current and North Korea Cold Current intersect. To clarify the effect of the Thermal Front, we investigated seasonal variation in fish species composition using set nets in two areas located north (Jangho, Gang-won-do) and south (Hupo, Gyeong-sang-buk-do) of Jukbyun, Gyeong-sang-buk-do, and compared the sea water temperature and salinity. We collected a total of 38 fish species in Hupo and 25 in Jangho. Trachurus japonicus was the most common species at both sites, but the subdominant species differed. At Hupo, the subdominant species were Konosirus punctatus and Diodon holocanthus, whereas Clupea pallasii and Scomber japonicus were subdominant at Jangho. Based on Froese and Pauly (2014), subtropical fishes accounted for 55% of fish in Hupo but only for 33% in Jangho. The difference in fish species composition was most obvious in May and August. According to the Korea Hydrographic and Oceanographic Administration, sea surface temperature and salinity were slightly higher at Hupo than at Jangho. Our findings suggest that the oceanographic boundary resulting from the Thermal Front near Jukbyun, Gyeong-sang-bukdo may have a major effect on the distribution of migratory fish species.

• 한국광학회지
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• 제14권5호
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• pp.504-508
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• 2003

최근 전자산업계에 새롭게 널리 생산되는 마이크로 전자부품들은 왜곡이 최소화된 정밀한 외관 형상을 갖도록 제조되고 관리되지만, 측정 대상의 표면이 가시광 영역에서 광산란되는 특징을 가짐으로 인해, 기존의 피죠나 마이켈슨 형태의 비교간섭법으로는 고정밀의 삼차원 형상측정이 용이하지 아니하였다. 본 논문에서는 광섬유를 이용한 새로운 개념의 점회절 간섭계를 제안하고, 이를 광산란 거친표면의 대표적인 제품인 칩패키지와 실리콘 웨이퍼의 삼차원 형상 측정에 적용하였다. 측정결과 66 mm 측정영역에서 측정 형상오차 PV(peak-to-valley value) 5.6 $\mu\textrm{m}$, 분산값($\sigma$) 1.5 $\mu\textrm{m}$를 획득함으로써 기존의 비교 간섭 측정법에 비해 더욱 향상된 측정 정밀도를 획득하였다.

• Wind and Structures
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• 제31권2호
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• pp.85-102
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• 2020

Accurate load evaluation is essential in any performance-based design. Design wind speeds and associated wind loads are well defined for synoptic boundary layer winds but not for thunderstorms. The method presented in the current study represents a new approach to obtain design wind speeds associated with thunderstorms and their gust fronts using historical data and Monte Carlo simulations. The method consists of the following steps (i) developing a numerical model for thunderstorm downdrafts (i.e. downbursts) to account for storm translation and outflow dissipation, (ii) utilizing the model to characterize previous events and (iii) extrapolating the limited wind speed data to cover life-span of structures. The numerical model relies on a previously generated CFD wind field, which is validated using six documented thunderstorm events. The model suggests that 10 parameters are required to describe the characteristics of an event. The model is then utilized to analyze wind records obtained at Lubbock Preston Smith International Airport (KLBB) meteorological station to identify the thunderstorm parameters for this location, obtain their probability distributions, and utilized in the Monte Carlo simulation of thunderstorm gust front events for many thousands of years for the purpose of estimating design wind speeds. The analysis suggests a potential underestimation of design wind speeds when neglecting thunderstorm gust fronts, which is common practice in analyzing historical wind records. When compared to the design wind speed for a 700-year MRI in ASCE 7-10 and ASCE 7-16, the estimated wind speeds from the simulation were 10% and 11.5% higher, respectively.