• 한국기계가공학회지
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• 제2권3호
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• pp.20-25
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• 2003

The End-milling has been widely used in the industrial world because it is effective to cutting working with various shape. Recently the end-milling is demanded the high-precise technique with good surface roughness and rapid manufacturing time for precision machine and electronic elements. The cutting working of end-milling such as, cutting direction, revolution of spindle, feed rate and depth of cut have an effect on optimum surface roughness. This study was carried out to decide the working condition for optimum surface roughness and rapid manufacturing time by design of experiment and ANOVA. From the results of this study, the optimum working condition for end milling is upward cutting in cutting direction, 600rpm in revolution of spindle, 240mm/mm in feed rate, 2mm in axial depth of cut and 0 25mm in radial depth of cut. The design of experiment has become an useful method to select optimum working condition mend-milling.

• 대한조선학회지
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• 제25권1호
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• pp.11-20
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• 1988

From the engineering point of view, a synthesis as well as an analysis technique is explored to search for the improved design of grillage which is common in ship structure. As an approximate analysis method for the grillage, an interaction reaction method is developed and compared with the finite element method. It is found that the discrepancy between these two methods is so negligible that the percent method could be used effectively for the grillage analysis. As an optimization technique, a feasible direction method could be used is combined with the intersection reaction method in order to design a minimum weight optimal grillage. The feasible direction method shows a good numerical performance although it requires more calculation times compared with the direct search method. Finally, the application of multiple objective optimization method to grillage is investigated in order to resolve conflicts existed between the multiple objectives which is a common characteristic of structure design problem. Goal programming method is extended to handle a nonlinear property of constraints and objective functions. It seems that the nonlinear goal programming could help not only to establish a relative importance of each objective, but also enable the designer to choose the best combination of design variables.

• 한국산업융합학회 논문집
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• 제4권2호
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• pp.157-166
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• 2001

The purpose of this study is to examine the accuracy of the code provisions on lateral load distribution factors of prestressed concrete girder bridges. Most designers in Korea use the lever method or lateral load distribution formula in the existing design codes. However, the methods do not account for the effect of bridge skew or direction of diaphragm. Therefore, this study analysed the prestressed concrete girder bridge with grillage model for various girder spacings, directions of diaphragms, span lengths, and skews, and compared the results with those of existing design code. It has been found that lateral load distribution factors were proportional to the girder spacing while they were not significantly affected by the change of span length, direction of diaphragm, and skew. For bending moments, lateral load distribution factors from the grillage analysis were 60%~68% of those from Korean bridge design code. Therefore, the code provisions result in very conservative design. For support reactions, however, lateral load distribution factors from the grillage analysis were slightly greater than those from Korean bridge design code. Therefore, the capacity of bearings of the bridge with a large skew should be determined by grillage analysis.

• 디지털융복합연구
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• 제16권1호
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• pp.351-356
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• 2018

본 연구는 지능형 버스정류장 U-Shelter의 등장으로 인해 더욱 혼잡해진 버스 정보 디자인을 사례 연구와 표적 집단면접법을 통해 가이드라인을 제안하는 데 그 목적이 있다. 우선, 문헌 연구를 통해 정보 디자인의 개념과 정보디자인과 노선도의 상관관계에 대해 알아보았으며 국내외 사례 연구를 통하여 문제를 제기, 개선방안을 도출하였다. 마지막으로 표적 집단면접법을 통해 현재 버스정류장의 정보 디자인을 평가하고, 이용자들의 요구와 문제점을 도출하였다. 연구 결과 현재 버스정류장 정보 디자인은 정보의 우선순위 결여, 정보 중첩, 인지성 문제가 있었으며 다음과 같은 가이드라인을 제시하였다. 버스노선, 버스의 방향, 도착시각, 배차 간격, 운행시간 순으로 우선순위를 선정하고 버스 표지판은 하나로 축약, 중복 기재하지 않는다. 또한, 약도 및 2차원 선과 도형을 사용해 노선 간의 연결과 방향을 시각화한다. 본 연구를 통해 앞으로 국내 버스정류장 정보 디자인의 개선과 발전에 도움이 되는 참고 자료로 활용될 것을 기대한다.

• 대한전자공학회논문지SP
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• 제47권3호
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• pp.81-86
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• 2010

CORDIC (COordinate Rotation DIgital Computer) 은 간단한 하드웨어로 벡터의 위상으로의 변환이나 회전 등의 위상 연산을 할 수 있으므로 OFDM 수신 시스템에서의 주파수 동기부를 설계할 때 효과적으로 사용될 수 있다. 그러나 CORDIC 알고리듬에서 위상을 표현하는 방향 시퀀스 (direction sequence, DS) 가 선형적이지 않기 때문에 사용상의 많은 제약이 존재한다. 본 논문에서는 근사적 선형성을 지닌 LBDS (linearized binary direction sequence) 표현 방법을 제안하고, LBDS의 최대 위상오차에 대해 분석한다. 또한 DS로부터 LBDS로 변환하는 하드웨어와 그 역변환 하드웨어의 구조를 제안한다. LBDS를 채택하면 위상 추정, 주파수 오차 루프 필터링, 위상 보정 역회전 등 주파수 동기의 전 과정에 CORDIC과 일반적인 산술 연산기를 사용할 수 있다. T-DMB 복조기에 사용될 수 있는 22비트 LBDS에 대한 예도 기술된다.

• 한국산학기술학회논문지
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• 제17권3호
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• pp.310-316
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• 2016

도전성 평판에 부분적으로 걸쳐 회전하는 축형 동전기 휠을 구동원으로 이용하는 비접촉 반송 시스템을 제안한다. 회전하는 동전기 휠에는 3축력이 발생되는데 이 중 중력방향 힘과 횡방향 힘은 자기안정성을 갖고 있으므로 공간상에서 반송 시스템의 동적 안정성을 확보하기 위해서는 길이 방향 힘만을 제어하는 것으로 충분하다. 동전기 휠은 원주 방향을 따라 주기적으로 반복되는 극성을 갖는 영구자석으로 구성되어있으므로 기본 극의 기하학적 형상이나 극수 등은 안정성 여유에 큰 영향을 미친다. 또한 휠과 전도판간의 중첩된 영역 역시 횡방향으로의 강성을 결정하는 주요 인자이므로 본 논문에서는 안정성을 성능 지표로 휠을 구성하는 주요 설계 변수에 대한 민감도 해석을 수행한다. 얻어진 설계 값을 이용하여 제작된 시스템으로 휠을 포함하는 이동 개체의 수동적인 안정성을 실험적으로 검증한다.

• 한국실내디자인학회논문집
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• 제25권4호
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• pp.80-89
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• 2016

The analysis of spatial search direction and its concentration through eye movement can produce some useful data in that it enables to know the features of space elements and their effects on one another. The results by analysing the search features and concentration of spatial sections through the eye-tracking in shops in a department store makes it possible to define the followings. First, the features of 'eye's in & out' could be estimated through the division of sections by the characteristics of those shops and the extraction of central point based on the decision of continuative observation. The decision of continuative observations enabled to analyse the frequency of observation data which can be considered to be 'things watched longtime' and the stared points that is equivalent to 'things seen very often', by which the searching characteristics of spatial sections could be estimated. Second, as with the eye's [in], the right shops had 0.6 times more (3.5%) than those left and as with the eye's [out] the left ones had 0.6 times more (3.5%). It indicates that [in, out] of the right and the left shops had the same difference, which lets us know that with starting point of the middle space, [in] and [out] were paid more attention to the right shops and the left shops respectively. Third, as with the searching directions by section, the searching times [2.9 times] from [B] to [A] were than that [2.6 times] from [A] to [B]. It was also found that the left shops had more searching direction toward [C, D] than the right ones and that those searching activities at the left shops were more active. Fourth, when the searching directions by section are reviewed, the frequency of searching from [B] to [A] was 2.9 and that of the other way 2.6. Also the left shops were found to have more searching direction toward [C, D] than the right ones and those searching activities at the left shops were estimated to be more active.

• 한국의상디자인학회지
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• 제21권4호
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• pp.17-26
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• 2019

This research aims to obtain useful data on the development of compression garment products with high-stretch knitted materials. Using nylon SCY, four specimens were knitted. Then, appearance (width, length, weight, thickness), stretch property (stretch, recovery) and clothing pressure were measured and their interrelation was analyzed. In the comparison of appearance features, yarn floating caused shrinkage in both course and wale directions of the specimens. Yarn overlapping by tucking caused a release in the course direction and shrinkage in the wale direction. Also, structural change was affected by the weight and thickness change of the knitted fabric. In the analysis of fabric stretch, yarn floating reduced the extension in course direction and increased that in wale direction of the knitted fabric. However, yarn overlapping reduced the elongation in both directions. In the analysis of recovery, yarn floating and overlapping raised fabric recovery in both directions, and tuck structure was superior to float in recovery. In the analysis of clothing pressure, 'Plain-Float' structured fabrics showed a higher clothing pressure than 'Plain' and the clothing pressure value of 'Plain-Tuck' was lower than that of 'Plain'. As for the correlation between fabric appearance, stretch property, and clothing pressure, the appearance change in course direction had a major influence on the clothing pressure. The shrinkage of appearance led to a decrease in stretch and an increase in clothing pressure.

• Design & Manufacturing
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• 제16권3호
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• pp.58-65
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• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• 콘크리트학회지
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• 제18권4호
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• pp.14-23
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• 2006