• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.112-119
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• 2009

The mechanical fastening has some advantages in respect of the fastening strength and disassemble of the fastened parts. However, at the same time it has some dangerous factors, can cause fatigue crack initiation and propagation due to not only the static loading such as cargo and passengers but also the dynamic loading like vibrations which occur in the engines and the propellers. For this reason, the strength evaluation for the mechanical fastenings along with the sophisticated and detailed mechanical design and the safety evaluation should be executed, In this paper, we were carried out experiments to study fatigue crack growth paths in structures containing the multiple circular holes. It was investigated that how circular holes are affected on fatigue crack growth paths using the specimen consists of A5052-H112, which is widely used as the ship materials. It was found from the experimental results that the fatigue crack as if it is drawn to circular holes when crack tip approach to circular holes. However, it did not go into circular hole if there is the next circular hole. Therefore, the clarification of mechanism on the fatigue crack initiation and the propagation in structures containing the multiple circular holes can be expected in this study.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.12 s.255
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• pp.1147-1154
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• 2006

An experimental investigation was conducted to enhance the heat/mass transfer for impingement/effusion cooling system when the initial crossflow was formed. For the improvement of heat transfer, the circular guide is installed on the injection hole. At the fixed jet Reynolds number of 10,000, the measurements were carried out for blowing ratios ranging from 0.5 to 1.5. The local heat/mass transfer coefficients on the effusion plate are measured using a naphthalene sublimation method. The result presents that the circular guide protects the injected jet from the initial crossflow, increasing the heat/mass transfer. The heat transfer of stagnation region is hardly changed regardless of the blowing ratio. The secondary peak is obviously formed by flow transition to turbulent flow. At high blowing ratio of 1.5, the circular guide produces $26{\sim}30%$ augmentation on the averaged heat/mass transfer while the case without circular guide leads to the low and non-uniform heat/mass transfer. With the increased heat/mass transfer, the installation of circular guide is accompanied by the increase of pressure loss in the channel. However, the pressure drop caused by the circular guide is lower than that for other cooling technique with the circular pin fin.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.905-910
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• 2008

In this paper, a circular motion table which is able to simulate movement of object is designed and the experiment of control system using circular motion table is presented. Circular motion table is consisted of three axes changed on length and of ball splines which keep vertical centre axis of circular plate. Variable length of three axes make circular plate incline as vertical centre axis is kept on vertical center axis of circular motion table. It is designed that control system drives three servo motor, that is, make change length of axis simultaneously or independently. And this paper presents example of flight simulation using circular motion table. it will contribute toward nurture expert manpower of aerospace/robotics to popularize circular motion table and make an experiment using it.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.399-404
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• 2001

In CNC machining, a 3D(3-dimension) linear segment and a 2D(2-dimension) circular arc are general forms given by CAD/CAM system. Generally, the 2D circular arc machining is processed using dividing into some linear segments. A 3D circular arc also don't exist in the standard form of NC data. This paper present a algorithm and method for real-time machining of a circular arc(not only the 2D one, but also the 3D one). The 3D circular arc machining is based on the 2D circular arc machining. It only needs making a new coordinate system, converting given 3D points(a start point, a end point, and a center point of a 3D circular arc) into points of the new coordinate system, and processing a inverse transformation about a interpolated point. The proposed algorithm was implemented and simulated on PC system. It was confirmed to give a gcod result.

• Fashion & Textile Research Journal
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• v.18 no.5
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• pp.637-646
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• 2016

The goal of this study is to provide basic data on developing circular knit basic pattern for women in their 20's. Production conditions of circular knit product pattern making among domestic women's apparel industry was researched, and collected data on sizes and ease amounts from woven and circular knit pattern were compared and analyzed. According to the result of the survey, product measurements adjusted to the actual body size fit for the brand's image were used, and the common problem among manufacturers and consumers regarding circular knit products turned out to be change in size and form due to stretching. For the basic pattern of circular knit, stretching quality was reflected in the woven basic pattern based on plain stitch(single knit) and then dart was removed and ease amount was reduced. The result of looking into size and ease amount about woven and circular knit torso & sleeve block shows that there is a significant difference among chest circumference, hip circumference, bi-shoulder length, interscye back, interscye front, scye depth, upper arm circumference and wrist circumference, and it was clear that circumference and width on the areas around the wrist tended to fit around the body more when circular knit was used instead of woven fabric.

• Journal of Korea Spatial Information System Society
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• v.11 no.4
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• pp.85-88
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• 2009

In multimedia database systems, the nearest neighbor Query occurs frequently and requires the processing cost higher than other spatial Queries do. It needs the measurement of search distance that the number of searched nodes and the computation time in an index can be minimized for optimizing the cost of processing the nearest neighbor query. The circular location property of objects is considered to accurately select the nodes which will be searched in the nearest neighbor query. In this paper, we propose the processing method of nearest neighbor queries be considered a circular location property of object where the search space consists of a circular domain and show its characteristics. The proposed method uses the circular minimum distance and the circular optimal distance, the search measurement for optimizing the processing cost of nearest neighbor queries.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1233-1238
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• 2003

In this paper, radially corrugated circular-type microstrip patch antenna was devised and manufactured for GPS (center frequency: 1.575 GHz). Radially corrugated circular-type microstrip patch antenna having radiational corrugation-patch contributed to add size reduction ratio by lowering the resonant frequency because the edge current also has the extended and perpendicular path. As a result, radially corrugated circular-type microstrip patch antenna has 28 % area reduction than planer circular-type patch antenna for linear polarization and 27.7 % area reduction than planer circular-type patch antenna for circular polarization. Radially corrugated circular-type microstrip patch antenna is suitable for miniaturized receive antenna for GPS which has the characteristic of gain 2.1 dBd, axiai ratio 1.3 dB, 2 dB axial bandwidth 15 MHz(0.9 %).

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.274.2-274.2
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• 2013

We described a simple and efficient fabrication method for generating microfluidic channels with a circular-cross sectional geometry by exploiting the reflow phenomenon of a thick positive photoresist. Initial rectangular shaped positive photoresist micropatterns on a silicon wafer, which were fabricated by a conventional photolithography process, were converted into a half-circular shape by tuning the temperature to around $105^{\circ}C$. Through optimization of the reflow conditions, we could obtain a perfect circular micropattern of the positive photoresist, and control the diameter in a range from 100 to 400 ${\mu}m$. The resultant convex half-circular photoresist was used as a template for fabricating a concave polydimethylsiloxane (PDMS) through a replica molding process, and a circular PDMS microchannel was produced by bonding two half-circular PDMS layers. A variety of channel dimensions and patterns can be easily prepared, including straight, S-curve, X-, Y-, and T-shapes to mimic an in vivo vascular network. To inform an endothelial cell layer, we cultured primary human umbilical vein endothelial cells (HUVECs) inside circular PDMS microchannels, and demonstrated successful cell adhesion, proliferation, and alignment along the channel.

• Journal of the Korea Society of Computer and Information
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• v.15 no.1
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• pp.83-90
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• 2010

The number of searched nodes and the computation time in an index should be minimized for optimizing the processing cost of the nearest neighbor query. The Measurement of search distance considered a circular location property of objects is required to accurately select the nodes which will be searched in the nearest neighbor query. In this paper, we propose the processing method of the nearest neighbor query be considered a circular location property of object where the search space consists of a circular domain and show its performance by experiments. The proposed method uses the circular minimum distance and the circular optimal distance which are the search measurements for optimizing the processing cost of the nearest neighbor query.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.309-315
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• 2021

The purpose of the article is to analyze the functioning of economic systems in the context of the development of their potential in a circular economy. It is determined that the functioning of economic systems to ensure their sustainability should meet modern challenges and provide for the formation of competitive institutional architecture, the introduction of structural and regulatory innovations, the transition to an innovative model of development. The specific principles of functioning of economic systems include openness, nonlinearity, multivectority, dynamism, emergence, uncertainty about the development of economic processes. It is substantiated that the linear nature of development and equilibrium are not dominant in the functioning of economic systems, and increasing the level of economic efficiency should go hand in hand with minimizing the activities of enterprises, which necessitates the use of circular economy. The main prerequisites for the transition to a circular economy are analyzed. It is determined that the basic concept of the circular economy involves the development of a system of production and consumption, which is based on processing, reuse, repair, product sharing, change of consumption patterns and new business models and systems. The main elements of the circular economy include: a closed cycle, the use of renewable energy sources, systems thinking. The correlation of the principles of sustainable development and the peculiarities of the application of the circular economy is analyzed. It is determined that the circular economy contrasts with the traditional linear economic model, which is based on the model of "take-do-consume-throw away". The advantages and disadvantages due to the use of the principles of circular economy are given. Based on the study, steps are identified to accelerate the transition from a linear economy to a circular economy.