• Structural Engineering and Mechanics
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• 제31권5호
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• pp.481-506
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• 2009

The present study is concerned with the stochastic linear free vibration study of laminated composite plate embedded with piezoelectric layers with random material properties. The system equations are derived using higher order shear deformation theory. The lamina material properties of the laminate are modeled as basic random variables for accurate prediction of the system behavior. A $C^0$ finite element is used for spatial descretization of the laminate. First order Taylor series based mean centered perturbation technique in conjunction with finite element method is outlined for the problem. The outlined probabilistic approach is used to obtain typical numerical results, i.e., the mean and standard deviation of natural frequency. Different combinations of simply supported, clamped and free boundary conditions are considered. The effect of side to thickness ratio, aspect ratio, lamination scheme on scattering of natural frequency is studied. The results are compared with those available in literature and an independent Monte Carlo simulation.

• 동굴
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• 제65호
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• pp.11-19
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• 2004

This study is basic research to present the activation of cave tourism. So first of all for establishing of this study, we examined the distribution characteristics of natural caves and monument caves. The results of this study are as follows; First, monument caves concentrate upon Gangwon-do and Jeju-do. Second, open caves concentrate upon Gangwon-do and Chungcheongbuk-do. Third, typical linkage characteristics of tourism resources surrounding open caves are very high in natural tourism resources. Fourth, It is necessary to develop tourism route though the linkage with other tourism resources. But this study have been partial and fragmentary. In order to increase the number of tourists, we should make them curious about the specific region by presenting the unique characteristics of the region, for example its cultural, social, recreational etc. In other words, in order to attract the tourists open caves should differentiate from other open caves.

• 충청수학회지
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• 제25권3호
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• pp.455-462
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• 2012

The purpose of this paper is to show that the coset bound can be used to prove the floor bound. Our proof provides a natural relation between the floor bound and the order bound.

• 한국지구과학회지
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• 제35권5호
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• pp.324-332
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• 2014

Many problems in naming natural monuments have been repeatedly argued by many researchers, and four different types of naming problems were identified: 1) name of unknown nationality (natural monument no. 82 and 108), 2) morphological name rather than scientific name (natural monument no. 180, 295, and 409), 3) name of fable character (local cultural property of Changnyeonggun), and 4) scientifically wrong name (natural monument no. 413). Among them, two cases (case 3 and 4) using wrong names are found in natural monument of geologic heritages, which should be ascribable to a hasty designation without an accurate and thorough scientific research. In order to solve these problems and to establish an ideal policy in designating natural monument, National Research Institute of Cultural Heritage has been carrying out a research project of "Pre-study and Post-designation (PSPD)", especially targeting the rod-shaped stromatolite. It is likely that this new strategy of PSPD is a unique and the first step to solve many problems in designating and naming geologic heritages as natural monuments. As a consequence, we strongly suggest that PSPD system must be applied to natural monument designation as an institutional arrangement.

• 한국안전학회지
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• 제31권2호
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• pp.119-126
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• 2016

Across the world, the industrialization has increased the frequency of climate anomaly. The size of damage due to recent natural disasters is growing large and fast, and the human damage and economic loss due to disasters are consistently increasing. Urbanization has a structure vulnerable to natural disasters. Therefore, in order to reduce damage from natural disasters, both hardware and software approaches should be utilized. Currently, however, the development of a statistical access process for 'analysis of disaster occurrence factor' and 'prediction of damage costs' for disaster prevention and overall disaster management is inadequate. In case of local governments, overall disaster management system is not established, or even if it is established, unscientific classification system and management lead to low utility of natural statistics of disaster year book. Therefore, in order to minimize disaster damage and for rational disaster management, the disaster damage survey process should be improved. This study selected gale as the focused analysis target among natural disasters recorded in disaster year book such as storm, torrential rain, gale, high seas, and heavy snow, and analyzed disaster survey process. Based on disaster year book, the gale damage size was analyzed and the issues occurring from the correlation of gale and damage amount were examined, so as to suggest an improvement plan for reliable natural disaster information collection and systematic natural disaster damage survey.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.302-310
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• 2011

A fluid in an enclosure can be heated by electric heating, chemical reaction, or fission heat. In order to remove the volumetric heat of the fluid, the walls surrounding the enclosure must be cooled. In this case, a natural convection occurs in the pool of the fluid, and it has a dominant role in heat transfer to the surrounding walls. It can augment the heat transfer rates tens to hundreds times larger than conductive heat transfer. The heat transfer by a natural convection in a regular shape such as a square cavity or semi-circular pool has been studied experimentally and numerically for many years. A pool of an inverted triangular shape with 10 degree inclined bottom walls has a good cooling performance because of enhanced boiling critical heat flux (CHF) compared to horizontal downward surface. The coolability of the pool is determined by comparing the thermal load from the pool and the maximum heat flux removable by cooling mechanism such as radiative or boiling heat transfer on the pool boundaries. In order to evaluate the pool coolability, it is important to correctly expect the thermal load by a natural convection heat transfer of the pool. In this study, turbulence models with modifications for buoyancy effect were validated for unsteady natural convections by volumetric heating. And natural convection in the triangular pool was evaluated by using the models.

• 한국지역지리학회지
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• 제9권1호
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• pp.66-76
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• 2003

습지는 물과 물 생태계의 점이지대로서 생태학적 및 경제학적 가치가 매우 높다. 내륙 담수습지 중에서 가장 중요한 하천습지는 서식지라기보다 유로(channel)로 인식되어 왔다. 본 연구에서는 낙동강 하류 연안의 지류 내에 형성된 자연습지의 특성을 고찰하고 그 관리방안을 모색하였다. 지류 내의 자연습지는 하천이 중간 규모일수록 본류에서 먼 곳에 넓게 소택지를 이룬다. 이것은 자연습지가 지류의 하상종단곡선에 빙기에 굴삭된 구간과 간빙기에 매적된 구간이 불협화로 만나는 구간에 형성되기 때문이다. 이러한 자연습지들을 효과적으로 보전하기 위해서는 습지의 세부사항을 목록화 하고 정밀 지도를 작성하여야 한다. 그리고 자연습지를 개간한 농경지의 일부를 습지생태계로 되돌려 생태학습장이나 생태관광지로 개발하는 역간척이 필요하다.

• 패션비즈니스
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• 제15권4호
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• pp.144-154
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• 2011

Polygoum tinctoria dye is the one using the method of reducing dyeing, and so is made by the mechanism different from natural dye in general, and the reproductive dye is more difficult because it varies in accordance with manufacturing method and days being manufactured in case of natural indigo dye that has been used traditionally. In addition, overall analysis is short of color changes in accordance with natural dyeing condition and barely none of the research for cellulose system such as cotton in particular. Accordingly, this study tries to research on the natural dyeing method optimal for color development that is desirable in designing and development of natural dyeing as comparing and contemplating the change of dyeing quality and color in accordance with reduction temperature and time, reductant quantity, dyeing temperature and time, NaOH quantity, and dyeing repetition times in order to expand dyeing methods and use variously polygoum tinctoria by improving traditional dyeing methods as well as to establish exact dyeing method of cotton which is a fabric of cellulose system in order to make such polygoum tinctoria quantificated and reproductive. The optimum conditions in the dyeing procedure are as follows: Reducing temperature is $50^{\circ}C$. Added concentration of the reducing agent is $3g/{\ell}$. Reducing time is 30minutes. Dyeing temperature is $30^{\circ}C$. Added concentration of NaOH is $1g/{\ell}$. Dyeing time is 30minutes.

• 한국조경학회지
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• 제29권2호
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• pp.22-31
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• 2001

The purpose of this paper is to investigate in resources of natural recreation forest(RNRF) developed both publicly and privately in order to answer the research question: what are the differences in RNRF development between public and private developers. After reviewing the literature, the developer´s decision-making and motivation of investment, and the planning process of natural recreation forest, We constructed the conceptual framework and have formulated the hypothesis of this research. We had obtained data through a questionnaire, which surveyed of 625 visitors at 9 of the 72 natural recreation forests in Korea in 1999, We have analyzed the data using the mean difference test and logistic regression method. We found that 1) the overall quality of resource elements in RNRF has been development excellent except for the sociocultural element of recreational resources, and public recreation forest have been of higher quality than that fo private development, 20 in bivariate analysis, all the variables on quality of RNRF by public developers have turned out to be better than those of private ones, 3) in multivariate analysis, such variable as valley and water, forest and wildness area, wild life, and landscape have been statistically significant at one percent level, 4) the higher the value of valley and water, the higher the probability of public development, while the higher the value of other variables excluding water and valley, the more likelihood the recreational forest is developed by a private developer, and 5) forest and wildness area has been turned out to be the most important independent variable in contributing to the value of dependent variable. The research results suggest that 1) the differences in the quality of resource elements in RNRF developed by public and private body be considered in the planning and design process in order to develop diverse activities to make use of the resource potential, and 2) considering the resource characteristics of private natural recreation forest and the motivation of private developers, private natural recreation forest will possibly be more dynamic and dynamic attractive areas. It is recommended that the difference in the degree of visitor´s satisfaction between public and private development be examined.

• 한국전산유체공학회지
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• 제16권3호
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• pp.66-74
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• 2011

A fluid in an enclosure can be heated by electric heating, chemical reaction, or fission heat. In order to remove the volumetric heat of the fluid, the walls surrounding the enclosure must be cooled. In this case, a natural convection occurs in the pool of the fluid, and it has a dominant role in heat transfer to the surrounding walls. It can augment the heat transfer rates tens to hundreds times larger than conductive heat transfer. The heat transfer by a natural convection in a regular shape such as a square cavity or semi-circular pool has been studied experimentally and numerically for many years. A pool of an inverted triangular shape with 10 degree inclined bottom walls has a good cooling performance because of enhanced boiling critical heat flux (CHF) compared to horizontal downward surface. The coolability of the pool is determined by comparing the thermal load from the pool and the maximum heat flux removable by cooling mechanism such as radiative or boiling heat transfer on the pool boundaries. In order to evaluate the pool coolability, it is important to correctly expect the thermal load by a natural convection heat transfer of the pool. In this study, turbulence models with modifications for buoyancy effect were validated for unsteady natural convections by volumetric heating. And natural convection in the triangular pool was evaluated by using the models.