• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.3
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• pp.97-106
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• 1989

This paper is on the modeling of two-dimensional groundwater flow, which is the first step of the development of Dynamic System Model for groundwater flow and pollutant transport in subsurface porous media. The particular features of the model are its versatility and flexibility to deal with as many real-world problems as possible. Points as well as distributed sources/sinks are included to represent recharges/pumping and rainfall infiltrations. All sources/sinks can be transient or steady state. Prescribed hydraulic head on the Dirichlet boundaries and fluxes on Neumann or Cauchy boundaries can be time-dependent or constant. Sources/sinks strength over each element and node, hydraulic head at each Dirichlet boundary node and flux at each boundary segment can vary independently of each other. Either completely confined or completely unconfined aquifers, or partially confined and partially unconfined aquifers can be dealt with effectively. Discretization of a compound region with very irregular curved boundaries is made easy by including both quadrilateral and triangular elements in the formulation. Large-field problems can be solved efficiently by including a pointwise iterative solution strategy as an optional alternative to the direct elimination solution methed for the matrix equation approximating the partial differential equation of groundwater flow. The model also includes transient flow through confining leaky aquifers lying above and/or below the aquifer of interest. The model is verified against three simple cases to which analytical solutions are available. The groundwater flow model shall be combined with the model of pollutant transport in subsurface porous media. Then the combined model, with the applications of the Eigenvalue technique and the Dynamic system theory, shall be improved to the Dynamic System Model which can simulate the real groundwater flow and the pollutant transport accurately and effectively for the analyses and predictions.

• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.1
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• pp.277-290
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• 1995

The study was carried out to analyze the fracture behavior and the acoustic emission(AE) characteristics and to find the relationship among tensile strength, fracture toughness and cure pressure in owe process of the carbon fiber reinforced composites of two types, $[0^{\circ}/90^{\circ}]_{2S}$ and $[0^{\circ}\;_2/90^{\circ}\;_2]_S$. AE signals were detected during the curing process, tensile tests and fracture toughness tests by acoustic emission(AE) measurements, respectively. Tensile strengths showed that the less cure pressurizing steps and the side of $[0^{\circ}/90^{\circ}]_{2S}$ specimens had the higher strengths than those of the others. Fracture toughness by the change of test temperature showed nearly same values in the same temperature region, but the higher test temperature had the lower fracture toughness values. In order to examine the relationship between fracture behavior of CFRP in tensile and fracture toughness tests and AE signals, the post processing for AE parameters of AE data and the observations of microscope and SEM have been carried out respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 1990.07a
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• pp.221-221
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• 1990

진하 해수욕장은 부산에서 약 40km 정도 동해안도로를 거슬러 올라가면 경남 울주군 진하리에 위치한 조그마한 자연해변의 해수욕장이다. 해수욕장의 동쪽에서는 회야천이 흘러 들어오고, 이 하천의 3km 상류지점에는 댐을 축조하여 온산공단 및 주변지역의 생활용수를 공급하고 있다. 어울려서, 쾌적한 위락시설 단지로서는 최적이라고 생각된다. 현재 이 해안은 매년 침식이 진행되면서 해수욕을 할 수 있는 해변 공간이 줄어들고 있는 실정이다. 따라서 이 해안을 보전하기 위해서 관청과 주민들은 많은 심혈을 기울이고 있는 실정이다. 본 연구의 조사단은 1987년부터 해마다 수침측량을 실시하여 해수욕장의 지형변화를 조사하고 있다. 특히 이 해수욕장의 사빈은 몇년전 부터, 침식형의 사빈으로 변화되어 매년 많은 모래가 유실되는 현상이 발생하고 있어, 관청 및 주민들의 관심을 집중시키고 있다. 따라서, 금년에도 울주군청에서는 회야강 하구에 생성된 사주를 준설하여 준설된 모래를 해수욕장에 인공적으로 투입하여 양빈을 실시하고 있는 실정이다. 이 작업은 하구폐색의 문제를 해결할 뿐만 아니라 선박의 운행에도 큰 도움을 주고 있다. 이러한 작업은 기초해안 자료를 충분히 검토된 상태에서 실시되어야 한다. 그러치 못할 경우는 인위적으로 투입된 모래는 파랑에 의해서 다시 심해방향이나, 해안류를 따라서 다시 하구로 밀려오는 현상이 일어 날 것이다. 본 연구는 회야강 하구의 지형변화와 진하 해수욕장의 사빈의 변화를 정확히 파악하고져 단기간 동안 심천 측량을 실시한 결과를 이용하여 기존이론으로 해석한 결과를 제시함을 목적으로 한다.고 동시에 광 스트레스에 대한 저해를 감소시키는 것으로 보인다. 있다. 청주권의 무심천도 계획상은 대청댐의 물을 공급 받을수도 있도록 되어 있으나 현실상으로 상수도 원수로서의 공급마저도 매년 심한 원수 수질 문제(5-6월, 10월경의 취수장 부근의 부영양화 현상으로 인한 악취와 물 맛의 문제)를 1984년부터 겪고 있다. 이와 같이 도시권 하천의 수자원은 자연적, 인위적, 경제적, 법적, 제도적 여러 제한 요소로서 특성을 가지고 있으며 이는 날로 심해 가고 있는 실정이다. 그러므로 최적 물관리 시스템의 개발이 새로이 시작하는 수자원 개발 사업에서는 계획 단계에서부터 절실히 요구되는 바이며 기존 시설물의 관리 운영은 과감히 그 운영 관리 기준을 보완 재 정비하여야 할 것이다. 지금까지 대부분의 수자원 종합 개발 계획이 홍수방이나 용수 공급 및 수력 개발 등에 주력하여 왔으나 이제는 보다 더 수자원의 환경 보전적 차원과 도시의 안정적 발달을 위한 지역 및 권역 계획과 연계지워져서 양적인 안정 공급과 더불어 질적인 향상과 연계지워서 경제-사회적 요구에 부응할 수 있도록 도시권의 수자원을 최적 관리할 수 있는 방안을 강구하여야 할 것이다. 이는 각 도시 하천의 수자원의 정량적·정성적인 특성 및 제한 요소를 충분히 감안하여 수요-공급 개념에 의하여 과감히 기존 시설(예: 팔당댐의 운영, 대청댐의 운영 등)의 관리 운영 체계를 개선하여 나가야 할 것이며, 수질 보전적-환경 보전 차원에서 저수관리 체계를 확고히 할 수 있는 방안을 강구하여야 할 것이다.펄스주입법에 의해 증착된 박박은 강유전성 이력을 나타내었다.지역

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.1-8
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• 2017

Three small scale hollow circular reinforced concrete columns with aspect ratio 4.5 were tested under cyclic lateral load with constant axial load. Diameter of section is 400 mm, hollow diameter is 200 mm. The selected test variable is transverse steel ratio. Volumetric ratios of spirals of all the columns are 0.302~0.604% in the plastic hinge region. It corresponds to 45.9~91.8% of the minimum requirement of confining steel by Korean Bridge Design Specifications, which represent existing columns not designed by the current seismic design specifications or designed by seismic concept. The longitudinal steel ratio is 2.017%. The axial load ratio is 7%. This paper describes mainly crack behavior, load-displacement hysteresis loop, seismic performance such as equivalent damping ratio, residual displacement and effective stiffness and flexural over-strength of circular reinforced concrete bridge columns with respect to test variable. The regulation of flexural over-strength is adopted by Korea Bridge Design Specifications (Limited state design, 2012). The test results are compared with nominal strength, result of nonlinear moment-curvature analysis and the design specifications such as AASHTO LRFD and Korea Bridge Design Specifications(Limited state design).

• Journal of the Society of Naval Architects of Korea
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• v.28 no.1
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• pp.12-18
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• 1991

Three-dimensional nonlinear sloshing effects due to tank motions are simulated by solving boundary value problem using the panel method based on boundary integral technique. While Shinkai used boundary elements on which source strengths vary linearly between nodes, the source of constant strength is distributed on each triangular panel in the present study. The source strength at each time step is determined by solving the Fredholm integral equation of the second kind obtained from Green's theorem. To avoid cumulative numerical errors as time elapses, Adam-Bashforth-Moulton method is employed. Numerical examples for the case of partially filled spherical tank on board oscillating in harmonic sway mode or pitch mode are solved. The elevation of the free surface is compared with the result by Shinkai and confirmed in good agreement during early time. The input and the output energy are comparatively evaluated to check the overall accuracy of the present numerical scheme. Although some leakage of energy are found as time marches, it is plausible when we take into account nonlinearities of the problem and the number of panels of the model.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.65-72
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• 1993

A numerical method for nonlinear free-surface-wave problem is developed in this paper. The final goal of this study is to simulate the towing tank experiment of a ship model and to partially replace the experiment by the numerical model. The exact problem in the scope of potential flow theory is formulated by a variational principle based on the classical Hamilton's principle. A localized finite element method is used in the present numerical computations which made use of the following two notable steps. The first step is an efficient treatment of the numerical radiation condition by using the intermediate nonlinear-to-linear transition buffer subdomain between the fully nonlinear and linear subdomains. The second is the use of a modal analysis in the final stage of the solution procedures, which enables us to reduce the computation time drastically. With these improvements the present method can treat a much larger computational domain than that was possible previously. A pressure patch on the free surface was chosen as an example. From the present computed results we could investigate the effect of nonlinearity on the down-stream wave pattern more clearly than others, because much larger computational domain was treated. We found, specifically, the widening of the Kelvin angle and the increase of the wave numbers and the magnitude of wave profiles.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1171-1176
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• 1996

The changes in volatiles of the model system were analyzed by GC and GC-MS before and after retorting. The GC data were analyzed statistically by applying the analysis of variance, and 42 peaks were selected at 5% significance level. Multivariate statistical analysis was performed with these 42 peaks as independent variables. Through the stepwise discriminant analysis, 8 peaks, which corresponded to the compounds such as 2-heptanone, cis-3-hexenal, 2-pentyl-furan, 1-methyl-trans-1,2-cyclohexanediol, 2-hexanone, 3-octanone, trans, trans-nona-2,4-dienal and 1-octen-3-ol, were obtained in sequence to distinguish the samples with and without retorting. The principal component analysis of a set of 8 independent variables resulted in 3 principal components which accounted for 96.1% of the variance, while the first principal component (PC 1) explained 76.5% of the total variance. In addition, through the factor analysis of the principal components, the peaks 11, 20 and 21 could be grouped togather in accordance with the direction and the size while the peaks 9, 33 and 39 constituted the second group in the direction.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.57-64
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• 2004

In order to establish the design method of anchored retention walls in cut slope, the behavior of anchored retention walls and backside ground needs to be investigated and checked in detail. In this study, the behavior of anchored retention walls was investigated by instrumentation installed in cut slope for an apartment construction site stabilized by a row of piles and anchored retention walls. When the anchor was installed at each excavating stages, the horizontal deflection of retention wall decreased, while the horizontal deformation of backside ground increased. The deflection of anchored retention wall decreased as the anchor was prestressed. The prestressed anchor farce has a great effect on the deflection of retention walls, while it has little effect on the deformation of its backside ground. The maximum horizontal deflection of anchored retention walls was developed between $1\%\;and\;4\%$ of excavation depth, which are $2\~8$ times larger than max. horizontal deflection of anchored retention walls including rock layers with backside horizontal ground. Meanwhile, SLOPILE (ver. 3.0) program analyzes the slope stability effects for anchored retention walls. As a result of analysis on slope stability analysis, the lateral earth pressure applied at anchored retention piles could be used as the mean values of empirical lateral pressures using anchored retention wall with horizontal ground at its backside.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.17-27
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• 2014

As the importance of Cooperative Engagement Capability and network-centric warfare has been dramatically increasing, it is necessary to develop distributed tracking systems. Under the development of distributed tracking systems, it requires tracking filters and data fusion theory for nonlinear systems. Therefore, in this paper, the problem of nonlinear track fusion, which is suitable for distributed networks, is formulated, four algorithms to solve the problem of nonlinear track fusion are introduced, and performance of introduced algorithms are analyzed. It is a main problem of nonlinear track fusion that cross-covarinaces among multiple platforms are unknown. Thus, in order to solve the problem, two techniques are introduced; a simplification technique and a approximation technique. The simplification technique that help to ignore cross-covariances includes two algorithms, i.e. the sample mean algorithm and the Millman formula algorithm, and the approximation technique to obtain approximated cross-covariances utilizes two approaches, by using analytical linearization and statistical linearization based on the sigma point approach. In simulations, BCS fusion is the most efficient scheme because it reduces RMSE by approximating cross-covariances with low complexity.

• Journal of Korean Philosophical Society
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• v.130
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• pp.1-22
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• 2014

Li Zehou(李澤厚) regards Chuang-tzu's fatalism as a kind of pessimism and slavish conformism. The main issue of this paper is to opposes Li Zehou(李澤厚)'s view, and reveal that Chuang-tzu's fatalism is not the negative and slavish conformism but the true positivism of the fate. These Chuang-tzu's fatalism can be conceptualized as a 安之若命. When the human was faced with unavoidable fate, Chuang-tzu's 安之若命 is not pessimistically surrender itself to the fate such as a slave, but pleasantly accepts and affirms the fate. Now, the next three process proves that Chuang-tzu's 安之若命 affirms the fate.The attitude of 安之若命, First, takes the unavoidable(不得已) fate as it is. Second, it resolves a humane 'sadness and joy(哀樂)' through 'the forgetting(忘).' Third, it understands the life and death, the change of world, the human body as the stream of energy(氣). Fourth, in conclusion, it affirms the fate by these processes. These point of view can conceptualize as Chuang-tzu's Amor Fati. That is to say, Chuang-tzu' 安之若命 is not a pessimistic but a positive view of the fate.