• International Journal of Naval Architecture and Ocean Engineering
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• 제4권2호
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• pp.123-131
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• 2012

When the object is traveling in the water at tremendously high speeds, the cavity forms and grows up at a fore part of the object called cavitator, and the object is eventually enveloped by vaporized water, supercavitation. As a result, the only part of the object in direct contact with the water is the cavitator, so skin-friction drag is significantly reduced. This is why recently supercavitating objects have been interested in many applicable fields. In this study we are focused out attention on supercavitating flows around various shapes of two and three dimensional cavitators. First, general features of supercavitation are examined by analyzing results obtained by the previously developed numerical method. Second, experimental observations are carried out at a cavitation tunnel at the Chungnam National University (CNU CT), and supercavity dimensions are scrutinized.

• 한국컴퓨터정보학회논문지
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• 제13권5호
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• pp.111-116
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• 2008

레이더 시스템은 간섭채널에서 목표물을 신속, 정확하게 예측하여야 한다. 무선채널의 간섭요소로는 인공구조물, 자연구조물에 의해서 다중경로가 형성되어 신호의 추정이 어렵다. 이러한 간섭신호를 제거하기 위해서 디지털 빔형성, 적응배열안테나 등 많은 연구가지속 되어왔다. 본 논문에서는 적응배열 안테나와 코히어런트 간섭신호를 제거하는 SPT-SALCMV 빔형성 알고리즘을 제안하였다. 적응 배열은 간섭신호의 방향에 대해서는 널 패턴을 형성하여 이득을 감소시킨다. 그리고 표적신호 방향으로는 빔 패턴의 이득을 일정하게 유지함으로서 원하는 신호를 추정한다. 본 논문에서 제안한 SPT-SALCMV 알고리즘은 목표물에 대한 위치를 정확히 수신하였다. 그러나 기존의 SPT-LCMV 알고리즘은 약 30 정도의 빔 오차가 생겼다. 따라서 본 논문에서 제안한 SPT-SALCMV 알고리즘이 기존의 SPT-LCMV알고리즘보다 우수함을 입증하였다.

• Advances in concrete construction
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• 제5권6호
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• pp.671-683
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• 2017

Commonly used concrete in general, consists of cement, fine aggregate, coarse aggregate and water. Natural river sand is the most commonly used material as fine aggregate in concrete. One of the important requirements of concrete is that it should be durable under certain conditions of exposure. The durability of concrete is defined as its ability to resist weathering action, chemical attack or any other process of deterioration. Durable concrete will retain its original form, quality and serviceability when exposed to its environment. Deterioration can occur in various forms such as alkali aggregate expansion, freeze-thaw expansion, salt scaling by de-icing salts, shrinkage, attack on the reinforcement due to carbonation, sulphate attack on exposure to ground water, sea water attack and corrosion caused by salts. Addition of admixtures may control these effects. In this paper, an attempt has been made to replace part of fine aggregate by tailing material and part of cement by fly ash to improve the durability of concrete. The various durability tests performed were chemical attack tests such as sulphate attack, chloride attack and acid attack test and water absorption test. The concrete blend with 35% Tailing Material (TM) in place of river sand and 20% Fly Ash (FA) in place of OPC, has exhibited higher durability characteristics.

• International Journal of Computer Science & Network Security
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• 제21권7호
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• pp.8-16
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• 2021

The tourism industry is influenced by a large number of factors that affect the development scenarios of the tourism in different ways. At the same time, tourism is an important component of the national economy of any state, forms its image, investment attractiveness, is a source of income and a stimulus for business development. The aim of the article is to conduct an empirical study to identify the importance of cognitive determinants in the development of tourism. The study used general and special methods: systems analysis, synthesis, grouping, systematization, cognitive modeling, cognitive map, pulse method, predictive extrapolation. Target factors, indicators, and control factors influencing the development of tourism in Ukraine are determined and a cognitive model is built, which graphically reflects the nature of the influence of these factors. Four main scenarios of the Ukrainian tourism industry are established on the basis of creating a matrix of adjacency of an oriented graph and forecast modeling based on a scenario approach. The practical significance of the obtained results lies in the possibility of their use to forecast the prospects of tourism development in Ukraine, the definition of state policy to support the industry that will promote international and domestic tourism.

• 기록학연구
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• 제5호
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• pp.87-109
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• 2002

The issue of how to manage the existing records at an archives is very important from the aspects of principle and practicality in record management since it is deeply related with the system of managing new records. Although there are a few studies on filing and criteria on organizing records, they do not often help in the actual site of record and archives management. Therefore, we need to raise the issues that could develop in actual sites and find the ways or resolving these issues, other than the general criteria proposed. Refiling is a very important task for recovering the original order and needs to be a task that should be done according to the overall system and process of record management at an archives. Furthermore, it is very important to objectify and regulate the contents and methods of the task of refiling through the refiling criteria with the content of criteria being specific. From the arguments presented until now, we could tell that refiling falls in the area of record management at an archive directly related with the department of reproducing records at public organizations. Moreover, the role of archivists relates with the task of refiling is critical. Especially, distinguishing job according to chief object is a critical issue in the status and role of archivists at record and archives institutions. This process is important not only at the level of simple job makeup but also in record management. Archivists should be responsible for preparing refiling criteria, reviewing of problems developed in job process, classifying records for refiling, reviewing and refiling of catalogs and key words, selecting equipment and tools, and establishing various forms.

• Journal of Electrochemical Science and Technology
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• 제9권4호
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• pp.251-259
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• 2018

In general, the charge storage characteristics and overall performance of electrochemical energy devices (such as lithiumion batteries and supercapacitors) significantly depends on the structural and geometrical factors of the electrodes' active materials. The most widely used active materials of electrochemical energy storage devices are based on carbons of various forms. Each carbon type has drawbacks and advantages when used as the electrode material. Studies have been recently carried out to combine different types of carbons, in particular nanostructured carbons, in order to overcome the structure-originated limitations and thus enhance the overall electrochemical performances. In this feature article, we report the recent progress on the development of this novel class of materials (multidimensional nanocarbons), and their applications for supercapacitors. Multidimensional nanocarbons include graphenes/carbon nanotubes (CNTs), CNTs/carbon films, CNTs/fullerenes, and ternary carbon nanostructures. Various applications using these multidimensional nanocarbons have been proposed and demonstrated in the literature. Owing to the recent extensive studies on electrochemical energy storage devices and considering that carbons are their most fundamental electrode materials, the number of reports on nanocarbons employed as electrodes of the electrochemical energy storage devices is rapidly increasing. Recently, numerous multidimensional nanocarbons have been designed, prepared, and utilized as electrodes of electrochemical capacitors or supercapacitors, which are considered next-generation energy devices owing to their unique merits compared to the conventional structures. In this review, we summarize the basic motivations, preparation methods, and resultant supercapacitor performances of each class of multidimensional nanocarbons published in the literature, focusing on recent reports.

• Wind and Structures
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• 제29권2호
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• pp.139-147
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• 2019

One of the most important factors in tall buildings design in urban spaces is wind. The present study aims to investigate the aerodynamic behavior in the square and triangular footprint forms through aerodynamic modifications including rounded corners, chamfered corners and recessed corners in order to reduce the length of tall buildings wake region. The method used was similar to wind tunnel numerical simulation conducted on 16 building models through Autodesk Flow Design 2014 software. The findings revealed that in order to design tall 50 story buildings with a height of about 150 meters, the model in triangular footprint with aerodynamic modification of chamfered corner facing wind direction came out to have the best aerodynamic behavior comparing the other models. In comparison to the related reference model (i.e., the triangular footprint with sharp corners and no aerodynamic modification), it could reduce the length of the wake region about 50% in general. Also, the model with square footprint and aerodynamic modification of chamfered corner with the corner facing the wind could present favorable aerodynamic behavior comparing the other models of the same cluster. In comparison to the related reference model (i.e., the square footprint with sharp corners and no aerodynamic modification), it could decrease the wake region up to 30% lengthwise.

• 한국의류산업학회지
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• 제21권5호
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• pp.527-539
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• 2019

This study examined the Chinese style in the Vivienne Tam collection as well as explored diversity and modern interpretation of a Chinese style used in modern fashion. The study also investigated the concept and history of the Chinese style as well as analyzed the Chinese style in the collection based on a consideration of a Chinese element that is the basic structure with an understanding of Vivienne Tam and general collection themes. As a result of research, the Chinese style appeared in the Vivienne Tam collection was comprehensive with 43 Chinese elements including Animals, Flower & Grass among the Nature elements, Mythology Religion among the Figure elements, Historical Artifacts, Clothing, Oral Literature, Entertainment, Fine Arts. Technique, Folk holiday among Culture elements and Philosophy among Spirit elements, which accounted for 57.6% of the collection. The formative characteristics that included Chinese elements were extended, abstracted, distorted or transformed; in addition, some abstract elements were embodied into animals, images and certain particular forms to present a theme. In addition to two-dimensional method to print Chinese elements on fabric, they were also expressed as a three-dimensional texture or a silhouette, achieving clear and bold harmony. The aesthetic characteristic is a mixture of Eastern and Western way of thinking. Her costume has a political and historical meaning beyond the imitation of elements that represent the development of a pleasant and interesting design.

• Structural Engineering and Mechanics
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• 제72권3호
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• pp.293-304
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• 2019

In this paper, a general model is developed to predict the distribution of interfacial shear and normal stresses of FG beam reinforced by porous FGM plates under mechanical loading. The beam is assumed to be isotropic with a constant Poisson's ratio and power law elastic modulus through the beam thickness. Stress distributions, depending on an inhomogeneity constant, were calculated and presented in graphicals forms. It is shown that both the normal and shear stresses at the interface are influenced by the material and geometry parameters of the composite beam, and it is shown that the inhomogeneities play an important role in the distribution of interfacial stresses. The results presented in the paper can serve as a benchmark for future analyses of functionally graded beams strengthened by imperfect varying properties plates. Numerical comparisons between the existing solutions and the present new solution enable a clear appreciation of the effects of various parameters. The results of this study indicated that the imperfect functionally graded panel strengthening systems are effective in enhancing flexural behavior of the strengthened FGM beams. This research is helpful in understanding the mechanical behaviour of the interface and design of hybrid structures.

• Journal of Chest Surgery
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• 제52권2호
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• pp.100-104
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• 2019

Shone complex is a rare congenital disorder that involves 4 obstructive lesions of the left heart, as follows: parachute mitral valve, supravalvular mitral ring, subaortic stenosis, and coarctation of the aorta. Incomplete forms with 2 or 3 of these lesions in adult patients have been rarely reported in the literature, meaning that insufficient general data exist concerning the surgical strategy and clinical follow-up. Herein, we report the case of a 31-year-old woman with a diagnosis of incomplete form of Shone complex with parachute mitral valve and coarctation of the aorta who underwent successful single-stage surgical repair.