• 대한수학회보
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• 제37권1호
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• pp.171-179
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• 2000

We prove the following: (1) For a Hausdorff space X, the hyperspace K(X) of compact subsets of X is hemicompact if and only if X is hemicompact. (2) For a regular space X, the hyperspace $C_K(X)$ of subcontinua of X is hemicompact (hemiconnected) if and only if X is hemicompact (hemiconnected). (3) For a locally compact Hausdorff space X, each open set in X is hemicompact if and only if each basic open set in the hyperspace K(X) is hemicompact. (4) For a connected, locally connected, locally compact Hausdorff space X, K(X) is hemiconnected if and only if X is hemiconnected.

• Coupled systems mechanics
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• 제8권5호
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• pp.459-471
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• 2019

This paper presents post-buckling analysis of a functionally graded beam under hygro-thermal effect. The material properties of the beam change though height axis with a power-law function. In the nonlinear kinematics of the post-buckling problem, the total Lagrangian approach is used. In the solution of the problem, the finite element method is used within plane solid continua. In the nonlinear solution, the Newton-Raphson method is used with incremental displacements. Comparison studies are performed. In the numerical results, the effects of the material distribution, the geometry parameters, the temperature and the moisture changes on the post-buckling responses of the functionally graded beam are presented and discussed.

• Advances in nano research
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• 제7권2호
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• pp.135-143
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• 2019

The important effect of porosity on the mechanical behaviors of a continua makes it necessary to account for such an effect while analyzing a structure. motivated by this fact, a new two-step porosity dependent homogenization scheme is presented in this article to investigate the wave propagation responses of functionally graded (FG) porous nanobeams. In the introduced homogenization method, which is a modified form of the power-law model, the effects of porosity distributions are considered. Based on Hamilton's principle, the Navier equations are developed using the Euler-Bernoulli beam model. Thereafter, the constitutive equations are obtained employing the nonlocal elasticity theory of Eringen. Next, the governing equations are solved in order to reach the wave frequency. Once the validity of presented methodology is proved, a set of parametric studies are adapted to put emphasis on the role of each variant on the wave dispersion behaviors of porous FG nanobeams.

• Parasites, Hosts and Diseases
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• 제36권3호
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• pp.155-162
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• 1998

우리 나라 일부 해안 지역의 장내 기생충 감염현황을 파악하기 위해 전북 부안군 주민 153명 및 경남 사천군 주민 138명의 대변을 수집하여 셀로판 후층 도말법 및 포르말린-에테르 침전법을 실 시하였다. 전북 부안군의 기생충 감염률은 21.5% (33/153명)이었으며, 감염 기생충별 양성률은 이형흡충류 17.6%, 간흡충 2.6%, 회충 0.7%, 람블편모충 2.6%, 대장아메바 0.7% 및 작은와 포자충 0.75이었다. 경남 사천군의 기생충 감염률은 39.1% (54/138명)로서 이형흡충류 18.8%, 간흡충 12.3%, 편충 2.2%, 람블편모충 2.2%, 대장아메바 5.0%, 이질아메바 0.7%, 왜소아메바 3.6% 및 작은와포자충 4.3%의 양성률을 보였다. 부안군에서 이형흡충란 양성자 22 명으로부터 회수한 충체는 유해이형흡충이 총 3,284마리 (평균 149.3마리)였으며 표주박이형흡 충, 수세미이형홉충, 요코가와흡충, 미야타흡충, 자루이형흡충, 참굴큰입흡충, 긴이형흡충 및 Aconthopowphium kurogamo등이 중복 감염되어 있었다. 사천군에서 이형흡충란 양성자 중 6명으로부터 회수한 충체는 요코가와흡충이 총 3,007마리 (평균 501.2마리)였으며 유해이형흡충, 수 세미이형흡충, 긴이형흡충, 갈매기이형흡충 등의 이형흡충류가 중복감염되어 있었다. 이상의 결과로 우리 나라 남해 및 서해안 지역 주민들에서 담수어 또는 반염수어의 생식 습관으로 장내 흡충, 특히 이형흡충류의 유행이 지속되고 있음을 확인하였다.

• 말소리와 음성과학
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• 제4권3호
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• pp.43-49
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• 2012

This paper describes the categorical effects of pitch accent contrasts in a mimicry task. It focuses, specifically, on examining how fundamental frequency (f0) variation reflects phonological contrasts from speakers of two distinct varieties of Korean (i.e., North Kyungsang and South Cholla). The results showed that, in a mimicry task using synthetic speech continua, there was a categorical effect in f0 peak timing for North Kyungsang speakers, but the timing of f0 peaks and valleys in the responses of South Cholla speakers was more variable, presenting a gradient or non-categorical effect. Evidence of categorical effects was represented as the shift of f0 peak times along an acoustic continuum for North Kyungsang speakers. The range for the shift of f0 valley times was much narrower, compared to that of f0 peak times. The degree of a shift near the middle of the continuum showed variability across individual mimicry responses. However, the categorical structure in mimicry responses regarding the clustering of f0 peak points was more significant for North Kyungsang speakers than for South Cholla speakers. Additionally, the finding of the current study implies that the location of f0 peak times depends on individuals' imitative (or cognitive) abilities.

• Geomechanics and Engineering
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• 제14권5호
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• pp.429-437
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• 2018

In order to reduce deformation of roadway floor heave in deep underground soft rockmass, four support design patterns were analyzed using the Fast Lagrangian Analysis of Continua (FLAC)3D, including the traditional bolting (Design 1), the bolting with the backbreak in floor (Design 2), the full anchorage bolting with the backbreak in floor (Design 3) and the full anchorage bolting with the bolt-grouting backbreak in floor (Design 4). Results show that the design pattern 4, the full anchorage bolting with the bolt-grouting backbreak in floor, was the best one to reduce the deformation and failure of the roadway, the floor deformation was reduced at 88.38% than the design 1, and these parameters, maximum vertical stress, maximum horizontal displacement and maximum horizontal stress, were greater than 1.69%, 5.96% and 9.97%. However, it was perfectly acceptable with the floor heave results. The optimized design pattern 4 provided a meaningful and reliable support for the roadway in deep underground coal mine.

• Interaction and multiscale mechanics
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• 제4권3호
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• pp.187-206
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• 2011

Accurate estimations of pre-failure deformations and post-failure responses of geostructures require that the simulation tool possesses at least three main ingredients: 1) a constitutive model that is able to describe the macroscopic stress-strain-strength behavior of soils subjected to complex stress/strain paths over a wide range of confining pressures and densities, 2) an embedded length scale that accounts for the intricate physical phenomena that occur at the grain size scale in the soil, and 3) a computational platform that allows the analysis to be carried out beyond the development of an initially "contained" failure zone in the soil. In this paper, a two-scale micropolar plasticity model will be used to incorporate all these ingredients. The model is implemented in a finite element platform that is based on the mechanics of micropolar continua. Appropriate finite elements are developed to couple displacement, micro-rotations, and pore-water pressure in form of $u_n-{\phi}_m$ and $u_n-p_m-{\phi}_m$ (n > m) elements for analysis of dry and saturated soils. Performance of the model is assessed in a biaxial compression test on a slightly heterogeneous specimen of sand. The role of micropolar component of the model on capturing the post-failure response of the soil is demonstrated.

• Parasites, Hosts and Diseases
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• 제43권3호
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• pp.93-100
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• 2005

The present study was performed to investigate the infection status with helminth in a group of feral cats in Korea. More than 29 helminth species including adults or eggs were detected in visceral and fecal samples of the examined cats. Among these were a host of nematodes, including toxocarids, Ancylostoma sp. and the larva of Anisakis simplex; trematodes, including Clonorchis sinensis, Paragonimus westermani, Eurytrema pancreaticum, Pharyngostomum cordatum, Metagonimus spp., Heterophyes nocens, Pygidiopsis summa, Heterophyopsis continua, Stictodora fuscata, Stictodora lari, Acanthotrema felis, Stellantchasmus falcatus, Centrocestus armatus, Procerovum varium, Cryptocotyle sp., Echinostoma revolutum, Echinostoma hortense, Echinochasmus japonicus, Stephanoprora sp., Plagiorchis muris, Neodiplostomum sp. and diplostomulum. We also detected a variety of cestodes, including Spirometra erinacei, Taenia taeniaeformis and unidentified species of tapeworm. We also found examples of the acanthocephalan, Bolbosoma sp. In our assessment of the stools, we detected at least 12 species of helminth eggs. These findings confirmed that feral cats in Korea are infected with a variety of helminth parasite species. Furthermore, among the helminths detected, E. pancreaticum, S. fuscata, S. lari, A. felis, S. falcatus, C. armatus, P. varium, Cryptocotyle sp., E. revolutum, E. japonicus, Stephanoprora sp., P. muris, Neodiplostomum sp. and Bolbosoma sp. represent helminth fauna which have not been reported previously in feral cats in the Republic of Korea.

• Journal of Ecology and Environment
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• 제38권2호
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• pp.271-279
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• 2015

After the reversion of Okinawa (Ryukyu Islands) to Japan in 1972, extensive urban and agricultural development resulted in a significant increase in sediment discharge to coastal waters. The release of sediment has caused the degradation of freshwater and coastal ecosystems and biodiversity. A consideration for catchment-to-reef continua, as well as agricultural (socioeconomic) factors is necessary to establish proper land-based management plans for the conservation of the island environment. We have set up a framework to integrate biophysics and socioeconomics: 1) setting a conservation target and threshold, 2) identifying the sources and processes, and 3) examining cost-effectiveness and management priorities. The framework may be applicable to other tropical and subtropical islands with similar characteristics.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.411-414
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• 2014

Numerical modeling was conducted to estimate the amount of dislocation that may occur across a frictionless fracture during an earthquake using commercial code FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions). The applied motion was calculated to represent a Richter 6.0 magnitude earthquake at distances of 2 km from the fracture. The velocity-time history was generated from Svensk $K{\ddot{a}}arnbr{\ddot{a}}anslehantering$ AB report. In the report, The velocity field resulting from an earthquake on a fault located in the near-field (2 km distance) was modelled using a finite difference program, WAVE. The stress-time history was substituted for velocity-time history to perform dynamic analysis using FLAC3D. During the earthquake, the maximum dislocation and change of shear stress were about 1 cm and 2MPa, respectively. Because the fracture is frictionless in this study, all dislocations relax to zero after the earthquake motions have ceased.