• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.359-361
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• 2001

In this paper, 3-dimensional charge simulation method was applied to analyze electric field distributions of special conductor bundles equipped with spiral rods for reducing aeolian noise in a corona cage. We found calculation error of this method was w a reasonable boundary of 0.5%.

• Earthquakes and Structures
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• 제16권2호
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• pp.221-234
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• 2019

Today, many important concrete face rockfill dams (CFRDs) have been built on the world, and some of these important structures are located on the strong seismic regions. In this reason, examination and monitoring of these water construction's seismic behaviour is very important for the safety and future of these dams. In this study, the nonlinear seismic behaviour of Ilısu CFR dam which was built in Turkey in 2017, is investigated for various reservoir water heights taking into account 1995 Kobe near-fault and far-fault ground motions. Three dimensional (3D) finite difference model of the dam is created using the FLAC3D software that is based on the finite difference method. The most suitable mesh range for the 3D model is chosen to achieve the realistic numerical results. Mohr-Coulomb nonlinear material model is used for the rockfill materials and foundation in the seismic analyses. Moreover, Drucker-Prager nonlinear material model is considered for the concrete slab to represent the nonlinearity of the concrete. The dam body, foundation and concrete slab constantly interact during the lifetime of the CFRDs. Therefore, the special interface elements are defined between the dam body-concrete slab and dam body-foundation due to represent the interaction condition in the 3D model. Free field boundary condition that was used rarely for the nonlinear seismic analyses, is considered for the lateral boundaries of the model. In addition, quiet artificial boundary condition that is special boundary condition for the rigid foundation in the earthquake analyses, is used for the bottom of the foundation. The hysteric damping coefficients are separately calculated for all of the materials. These special damping values is defined to the FLAC3D software using the special fish functions to capture the effects of the variation of the modulus and damping ratio with the dynamic shear-strain magnitude. Total 4 different reservoir water heights are taken into account in the seismic analyses. These water heights are empty reservoir, 50 m, 100 m and 130 m (full reservoir), respectively. In the nonlinear seismic analyses, near-fault and far-fault ground motions of 1995 Kobe earthquake are used. According to the numerical analyses, horizontal displacements, vertical displacements and principal stresses for 4 various reservoir water heights are evaluated in detail. Moreover, these results are compared for the near-fault and far-faults earthquakes. The nonlinear seismic analysis results indicate that as the reservoir height increases, the nonlinear seismic behaviour of the dam clearly changes. Each water height has different seismic effects on the earthquake behaviour of Ilısu CFR dam. In addition, it is obviously seen that near-fault earthquakes and far field earthquakes create different nonlinear seismic damages on the nonlinear earthquake behaviour of the dam.

• 헤리티지:역사와 과학
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• 제47권2호
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• pp.68-84
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• 2014

백제의 능묘는 금강유역으로 천도 후 송산리식의 횡혈식석실묘 ${\rightarrow}$ 남조식의 전실묘 ${\rightarrow}$ 능산리식의 횡혈식석실묘로 변천하였다. 이 변화에서 가장 눈에 띄는 것이 천장 구조의 변화이다. 천장은 궁륭천장(송산리식) ${\rightarrow}$ 터널천장(전실묘와 능산리식 과도기) ${\rightarrow}$ 집지붕천장(능산리식으로 제형, 삼각형, 평천장 세 아류의 형식)으로 변천했다. 이러한 변천과정에서 가장 특징적인 것은 능산리식 횡혈식석실로 이는 백제에서 창출된 특수한 형식이다. 백제의 능묘는 봉분을 중시하지 않아 현저하지 않았다. 이는 개별 능묘를 과시하여 표지하고자 하는 의도보다는 능원의 영역을 중시하는 가족공동체적인 성격이 강화된 것이고 남조의 영향으로 볼 수 있다. 백제의 능원은 백제가 남천한 후 왕가의 능원에서 단독의 독립능원으로 변천한다. 전자는 송산리와 능산리의 능원이고, 후자는 익산의 쌍릉이다. 전자는 완벽한 풍수지리와 함께 남조의 영향으로 볼 수 있고, 후자는 중국이 재통일된 수와 당초의 능원제 영향이다. 왕가의 능원에는 왕릉만 존재하는 것이 아니고 그와 관련된 인물을 배장하였다. 그리고 능원에는 제의시설이 존재했다. 송산리 능원에는 제단이 설치되어 있었는데, 이는 시조묘적인 성격도 가지고 있었을 가능성이 크다. 능산리 능원에는 공동의 능묘에 대해 제의를 시행할 수 있는 노천의 제의 공간이 마련되었고, 이 제의를 담당하면서 선왕에 대한 명복을 빌기 위한 능사가 설치되었다. 이러한 배치나 구조는 신라의 서악동 능원과 아주 유사하다.

• 토지주택연구
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• 제7권1호
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• pp.31-41
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• 2016

이 논문은 최근 천영수 등(2011)에 의하여 제안된 벽체 단부 횡보강상세를 지닌 벽체를 중심으로 벽체의 구조성능 영향 변수들을 대상으로 한 실험결과와 그에 따른 내진거동 및 이력특성을 제시하고 있다. 제시된 결과는 동 벽체의 비선형이력특성을 규명함으로써 향후 성능기반설계의 적용을 위한 기초자료를 제공하게 될 것이다. 실험결과, 제안된 횡보강 상세를 채용한 실험체의 균열 및 파괴 양상은 축력과 내진철근의 적용 여부와 상관없이 유사한 경향을 나타내었으며, 기준에서 제시하고 있는 설계식에 의하여 실험체의 최대강도를 잘 예측할 수 있는 것으로 나타났다. 또한, 축력이 높을 수록 초기강성과 최대강도는 증가하나 변형능력은 떨어지는 경향이 있어 고 축력으로 인한 변형능력 감소에 대한 고려가 필요할 것으로 보이며, 고 축력이 작용하는 벽체의 경우 내진철근의 사용이 변형능력의 확보라는 관점에서 매우 효과적인 방안이 될 것으로 보임으로 가능하다면 소성힌지 영역은 내진철근을 사용한 경계요소로 보강하는 것이 바람직한 것으로 판단된다.

• 대한기계학회논문집
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• 제4권4호
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• pp.152-159
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• 1980

The temperature and the grain boundary precipitation have the great influence on the low-cycle fatigue behavior of austenite stainless steel at elevated temperature. For the purpose of investigating the mechanism concerning the change of fatigue micro crack mode in SUS 316 under various conditions low-cycle fatigue test was carried out at the elevated temperature 600.deg.C, plastic strain range 2% and constant strain rate .5c.p.m. A special attention is given to the observation of intergranular crack initiation. The results obtained are summarized as follows. The low-cycle fatigue behavior of SUS 316 at 600.deg.C is affected by transition of crack initiation mode from intergranular to transgranular. The transition is due to the aging effect, which is caused by grain boundary precipitations of Cr$\_$23/C$\_$6/. Since the intergranular crack initiation is brought about by the grain boundary sliding, the transgranular crack initiates in case that the strengthening of grain boundary due to the precipitation of Cr$\_$23/C$\_$6/ carbides takes place ahead of the intergranular crack initiation.

• Ocean and Polar Research
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• 제29권1호
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• pp.55-67
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• 2007

A reference to natural prolongation appeared for the first time in the North Sea Judgement. Although it was not suggested that the concept of natural prolongation would automatically allow for the fixing of a continental shelf boundary, that concept encouraged States to request international tribunals to determine continental shelf boundaries on the basis of the geological and geomorphological features of the seabed. In the Libya v. Malta Case, however, the rejection of geological and geomorphological factors was total. Especially, Natural prolongation was the then checkmated as a relevant fact in delimitation between coasts situated less than 400 nm. apart. There can be no doubt that, in several disputed cases, prominent geomorphological variations are simply ignored ; nevertheless, there are also a few agreements where geological and geomorphological characteristics come into play and, to a certain extent, affect maritime boundaries. Physical characteristics of sea-bed are generally given serious consideration in the boundary delimitation such as the final negotiated boundary of the Australia-Indonesia Continental Shelf boundary Agreement(Timor and Arafura seas) which follows the continental slope bordering the Timor Trench.

• 한국해양공학회지
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• 제36권6호
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• pp.353-363
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• 2022

The azimuth thruster is mainly installed on a vessel that requires a dynamic positioning (DP) function for special purposes. When the azimuth thruster on a vessel operates for DP, the thrust loss is induced by the thruster-hull interaction. This study examined the influence of boundary conditions in numerical simulations for predicting thrust loss. Wind turbine installation vessels (WTIV) and floating production storage and offloading (FPSO) were chosen as a target vessels. In this study, two types of boundaries were defined. The first consideration is that the boundary condition was assigned with consideration of the azimuth angle of the thruster, whereas it is fixed regardless azimuth angle of the thruster. The predicted thrust loss according to these boundary conditions showed a difference. This observation originated from the current load of the vessel. Therefore, the boundary conditions for which the current load is not induced need to be designated to obtain a realistic thrust loss in a numerical simulation.

• 대한수학회지
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• 제37권5호
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• pp.665-685
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• 2000

The aim of this paper is to obtain nonlinear operators in suitable spaces whise fixed point coincide with the solutions of the nonlinear boundary value problems ($\Phi$($\upsilon$'))'=f(t, u, u'), l(u, u') = 0, where l(u, u')=0 denotes the Dirichlet, Neumann or periodic boundary conditions on [0, T], $\Phi$: N N is a suitable monotone monotone homemorphism and f:[0, T] N N is a Caratheodory function. The special case where $\Phi$(u) is the vector p-Laplacian $\mid$u$\mid$p-2u with p>1, is considered, and the applications deal with asymptotically positive homeogeneous nonlinearities and the Dirichlet problem for generalized Lienard systems.

• 한국유체기계학회 논문집
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• 제13권2호
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• pp.12-17
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• 2010

A kind of disk-shape boundary layer pump is designed numerically by using a software of computational fluid dynamics, which is widely used for the special purposes such as artificial hearts, bio-fluidics and transportation of oceanic lives, etc. From the numerical simulation with an axisymmetric model, some benchmark problems are tested and compared with experimental results. The performance of disk pump is graphically visualized from the computational results, and converted to the dimensionless parameters. Finally, the obtained numerical data in the present investigation can be used for the baseline for new design to achieve a more efficient disk pump.

• 한국해안해양공학회지
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• 제13권2호
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• pp.100-108
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• 2001

지진해일 또는 조석과 같은 장파의 거동을 모의할 때 해안선의 위치는 파랑의 움직임에 따라 연속적으로 이동된다. 따라서, 수치모형에 이를 효과적으로 반영하기 위해서는 해안선을 파랑에 따라 이동시켜야 한다. 본 연구에서는 경사지형을 계단지형으로 단순화한 이동경계조건을 이용하여 해일이나 조석에 의한 최대범람구역을 결정한다. 이동경계조건을 이용하여 특정지역의 최대범람구역을 결정한 후 기존의 관측자료와 비교하였으며, 결정된 최대범람구역은 기존의 자료와 잘 일치한다.