• 대한조선학회논문집
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• 제39권4호
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• pp.32-41
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• 2002

본 논문에서는 고차경계요소법을 사용하여 폰툰형 초대형 구조물의 유탄성 응답을 해석하였다. 폰툰형 구조물의 설치가 예상되는 천수심 해역에서 유탄성 응답 해석에서 흘수의 영향을 고찰하였다. 초대형 구조물인 경우 실제 해상파의 파장 범위인 단파장 구간일 때 흘수의 영향을 무시한 해석은 구조물의 유탄성 응답과 상대파고를 과소평가 하는 것으로 나타나 폰툰형 구조물에서도 흘수 영향을 고려한 해석이 중요함을 보였다.

• 한국지구과학회지
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• 제41권4호
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• pp.344-355
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• 2020

Tropical cyclone scale vortices and associated Rossby waves were investigated numerically using high-resolution barotropic models on the global domain. The equations of the barotropic model were discretized using the spectral transform method with the spherical harmonics function as orthogonal basis. The initial condition of the vortex was specified as an axisymmetric flow in the gradient wind balance, and four types of basic zonal states were employed. Vortex tracks showed similar patterns as those on the beta-plane but exhibited more eastward displacement as they moved northward. The zonal-mean flow appeared to control not only the west-east translation but also the meridional translation of the vortex. Such a meridional influence was revealed to be associated with the beta gyre and the Rossby wave, which are formed around the vortex due to the beta effect. In the case of the basic zonal state of climatological mean, the meridional translation speed reached the maximum value when the vortex underwent recurving.

• 한국해안해양공학회지
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• 제6권3호
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• pp.266-274
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• 1994

우리나라 서해안에 위치한 인천해역의 개발에 따른 조석특성을 분석하기 위하여 2차원 수치모형을 이용한 수치분석을 수행하였다. 먼저 기존 및 새로운 조석관측 자료를 분석하고, 수학적 모형으로서 수심 적분한 천수방정식을 선정하였으며, 이에 따른 수치모형은 Flather and Heaps(1975)의 모형을 사용하였다. 관측된 2개 주요분조 M$_2$와 S$_2$를 외해 경계조건으로 입력하여 모형을 수립하고, 수립된 모형을 2종류의 인천해역 개발안에 따라 적용하였다. 이 해역이 개발될 때 대조시 조석 변화양상을 평가한 결과 진폭변화는 미약하나 조류변화는 부분적으로 크게 나타낸다.

• 한국농공학회논문집
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• 제46권3호
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• pp.3-14
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• 2004

A two-dimensional numerical model based on a finite volume method was formulated to solve the shallow water equations and applied for evaluating drainage characteristics at large-sized paddy fields. Manning roughness coefficient was calibrated using the observed inundating depths at drainage tests, and used for validating the model with the results from another drainage test. The simulated results were in good agreement with the observed inundating depths. The result of surface drainage showed that the longer width of the outlet was or the more the number of drainage outlet was, the shorter the drainage time was taken, and the larger the size of the field become, the longer the drainage time was taken, and the field shape had little effect on drainage time. To reduce the drainage time to 24 hours, the outlet is located lower than the elevation of the basin and small drainage ditch is constructed at the field. The results showed that the drainage time was taken short as the small drainage ditch was constructed. The comparison of drainage time as to the size of field constructed small drainage ditch showed the field, 100m ${\times}$ 200 m, can be drained in 24 hours.

• 물과 미래
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• 제16권4호
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• pp.245-252
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• 1983

근년에 이르러 국내 지표수의 오염 현상은 사회적으로 매우 심각한 문제를 야기시키고 있어 수자원의 보호문제가 매우 중요한 시점에 이르렀다. 한강유역내에 발달 분포된 천층의 충적 퇴적층과 결정질암내에 저유된 지하수에 대해 동위원소를 이용한 환경 조사를 시행하였으며 결과를 분석한 바 다음과 같은 가정을 확인하였다. 1) 천층지하수의 함양원은 서울 도심지역은 하천수였고, 교외 외각의 농촌 지역은 강우의 직접 지하 침투에 의해 일어나고 있으며, 2) 충적 퇴적층으로 피복된 결정질 암은 상부충적퇴적층내에 저유된 천층 지하수가 충진원의 역할을 한다. 한강하류부의 해안 가까운 곳에 분포된 일부 충적층과 그 하부의 결정질암내에 저유된 지하수는 $H^3$의 함량이 매우 낮은치를 나타내는데 이는 핵실험이전의 기상수가 상당히 먼곳에서 충진되었기 때문으로 시료된다. 안정동위원소 조사에 의하면 한강상류에 분포된 석회암 대수층의 함양지역은 하류부의 충적층과는 달리 비교적 고지대였으며 석회암 대수층내에서 지하수의 체제 시간은 수개월 정도였다. 지하수의 포함된 극소량의 Pb, Mn, Zn 량과 충진메카니즘을 대비하려고 시도하였으나 명확한 관계가 나타나지 않았다.

• Asian-Australasian Journal of Animal Sciences
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• 제13권7호
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• pp.1010-1016
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• 2000

Effect on the bio-mass and nutrient yield of Lemna perpusilla Torry was studied at two nutrient loading frequencies. Six polythene sinks ($6{\times}2{\times}0.5m^{3}$ area) randomly allocated to two treatments having three sinks in each treatment. Each sink containing $6{\times}2{\times}0.35m^{3}$ water body, was changed either daily with 12.6 kg anaerobically fermented cattle manure (effluent) or with 76 kg efluent at six-day interval. Media Kjeldhal-N (40 vs. 36 mg/L; p>0.05) and $NH_3$-N (9 vs 7 mg/L; p<0.05) concentration were higher in daily charged sinks than those charged at six-day interval. However, temperature ($28.48{^{\circ}C}\;vs.\;28.60{^{\circ}C}$) and pH (6.82 vs. 6.84) were sinilar in both groups of sinks. Biomass (93 vs. $80g/m^{2}/d$) and crude protein (1.24 vs. $1.11g/m^{2}/d$) yield were non-significantly (p>0.05) higher in the daily charged than 6-d interval charged ponds. However, dry matter (4.52 vs. 4.15%), organic matter (83 vs. 84%), crude protein (31.4 va. 29.6%) and organic carbon (47 vs. 47%) content were similar in both daily and 6-d interval charged ponds. There were no apparent relationships between the crude protein content of Lemna and the media Kjeldhal-N or $NH_3$-N concentration apparently due to saturated level of nutrient (N in particular). It was concluded that with the level of effluent used for two treatments, nutrient-loading frequency had no significant effect on the biomass and protein yield of Lemna. Technique described here can be used for year-round duckweed production from fermented cattle manure for feeding poultry/fish in smallholder production system.

• 자원환경지질
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• 제32권2호
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• pp.177-187
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• 1999

Gravity, magnetic and VLF surveys were conducted to investigat the structural stability and hazards associated with the Ubong landfill in Pohang City, which has been built to dump industrial wastes. In 1994, the collapse of a bank happened in the 6th landfill site due to sudden heavy rain, and a large quantity of waste materials flowed out to the nearby landfill sites, factories and roads. We used $10{\times}10m$ resolution DEM data for gravity reductions. The maximum variation of the terrain effect in the survey area is about 0.5 mgal and the terrain effect is large in the vicinity of bank boundary. The Bouguer gravity anomaly map shows the effect due to the variatino of thickness and type of waste materials. The small negative gravity anomaly increases from the 9th site to the 6th site. The small negative gravity anomaly of the 9th site reflects the relatively shallow dumping depth of average 14.5 m in this site and increased density of waste materials by the repeated stabilization process of soil overlaying. The 6th site is located at the center of the former valley and rainfall and groundwater are expected to flow from south-east to north-west. Therefore, considering the previous accident of mixing waste and bank materials at the north-west boundary of the landfill, there may be some environmental problems of leakage of contaminated water and bank stability. The complex inversion technique using Simulated annealing and Marquardt-Levenberg methods was applied to calculate three-dimensional density distribution from gravity data. In the case of 6th site, it is apparent that the landfill had been dumped in four sectors. However, most part of the 9th site and showed that high magnetic industrial wastes were concentrated in the 6th site. The result of magnetic survey showing low magnetic anomalies along the boundaries of two sites is similar to that of gravity data. The VLF data also reveals four divided sectors in the 6th site, and overall anomaly trend indicates the directio of former valley.

• 한국음향학회지
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• 제21권3호
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• pp.213-220
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• 2002

해수중에서 음파는 수심, 음속구조 및 해저지질 등의 영향을 받으면서 전파한다. 특히 천해의 경우 해수중의 음속구조는 시공간적으로 심하게 변동하고 있고, 해저지질도 공간적으토 다양하게 분포한다. 황해에 있어서 저주파 음파전파의 계절변동을 조사하기 위하여 황해의 중앙부분에 위치하는 동일한 정선에서 봄철, 여름철, 가을철 등 서로 다른 계절에 저주파 광대역 음원을 이용하여 음파 전파실험을 실시하였다. 그리고 이 때에는 수중음파 전락환경을 파악하기 위하여 해수중 음속구조를 측정하였다. 이 논문에서는 황해에 있어서 음속구조 및 음파 전달손실의 측정결과에 관하여 고찰하였고, 음파 전달손실의 계절변동을 조사하였다. 그 결과 여름철에 측정된 전달손실은 봄철 및 가을철에 측정된 전달손실보다 크게 나타났고, 가을철에 측정된 전달손실은 봄철에 측정된 전달손실보다 다소 작게 나타났다. 그리고 계절에 의한 전달손실의 차이는 주파수 및 전파거리의 증가와 함께 증가하였다.

• 한국해안해양공학회지
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• 제19권5호
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• pp.484-491
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• 2007

규칙파와 수면아래 잠긴 수평판 사이의 비선형 상호작용을 규명하기 위하여 수치파동수조를 이용하여 수치 실험을 수행하였다. 수치모델로 비선형 포텐셜 이론을 근거로 한 고차 경계요소법과 Navier Stokes 방정식과 엄밀한 자유표면 경계조건식을 푸는 CADMAS-SURF을 사용하였다. 두 모델 모두 수평판 위의 천수역에서 발생하는 고차 조화항들을 예측할 수 있으며 점성효과를 포함하는 CADMAS-SURF는 수평판 양단에서 발생하는 와류와 박리에 의한 고차 조화항의 발생을 재현할 수 있다. 수평판의 잠긴 깊이와 길이 변화에 따른 반사율과 투과율을 Patarapanich and Cheong(1989)의 모형실험결과와 비교하였고 서로 잘 일치함을 확인하였다. 수평판의 길이가 길어지고 잠긴 깊이가 얕아질수록 입사파의 에너지가 고차 조화항으로 더 많이 전이됨을 확인하였다.

• 한국항해항만학회지
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• 제28권7호
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• pp.619-627
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• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. We also considered the increase of water depth at the entrance channel by dredging work up to 15 meters depth in order to see the dredging effect. Among several model analyses, the nonlinear and breaking wave conditions are showed the most applicable results. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.