• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.19-20
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• 2006

As the Mobile and Display technology are being developed quickly, new wireless devices are released in great numbers. They reduce existing devices' life time and demand a reduction of developing period of portable devices. With these demands, existing film cutting mold used many films of portable devices, especially LCD Display, needs to be more precise, and cheaper. In this research, we have analyzed machining characteristics of cutter shapes, materials, and cutting conditions for application to other films. Cutter edge was machined by slot cutting method and CAD program to select the cutter shape and cutter angle. Also, we have determined the optimal cutting conditions using high speed machining experiments to improve the productivity.

• Geomechanics and Engineering
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• 제9권1호
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• pp.25-37
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• 2015

To predict the surface subsidence of salt rock storage, a new surface subsidence basin model is proposed based on the Logistic function from the phenomenological perspective. Analysis shows that the subsidence curve on the main section of the model is S-shaped, similar to that of the actual surface subsidence basin; the control parameter of the subsidence curve shape can be changed to allow for flexible adjustment of the curve shape. By using this model in combination with the MMF time function that reflects the single point subsidence-time relationship of the surface, a new dynamic prediction model of full section surface subsidence for salt rock storage is established, and the numerical simulation calculation results are used to verify the availability of the new model. The prediction results agree well with the numerical simulation results, and the model reflects the continued development of surface subsidence basin over time, which is expected to provide some insight into the prediction and visualization research on surface subsidence of salt rock storage.

• 한국기계가공학회지
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• 제15권2호
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• pp.38-45
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• 2016

Since a 5-axis machine tool has two rotary axes, it offers numerous advantages, such as flexible accessibility, longer tool life, better surface finish, and more accuracy. Moreover, it can conduct whole machining by rotating the rotary feed axes while setting the fixture at once without re-fixing in contrast to conventional 3-axis machining. However, it is difficult to produce complicated products that have a hollow shape. In contrast, 3D printing can produce an object with a complicated hollow shape easily and rapidly. However, because of layer thickness and shrinkage, its surface finish and dimensional accuracy are not adequate. Therefore, this study proposes hybrid technology by integrating the advantages of these two manufacturing processes. 3D printing was used as the additive manufacturing rapidly in the whole body, and 5-axis machining was used as the subtractive manufacturing accurately in the joining and driving places. The reliability of the proposed technology was verified through a comparison with conventional technology in the aspects of processing time, surface roughness. and dimensional accuracy.

• 한국공간구조학회논문집
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• 제17권1호
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• pp.31-40
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• 2017

The objective of this study is to analysis the mechanical characteristics and nonlinear behaviors on the geometric nonlinear behavior of a cable spoke wheel roof system for long span lightweight roof structures. The weight of a cable spoke wheel roof dramatically can reduce and the cable roof system can easily make the required rigidity and shape by the sag ratio and pretension forces. Determining the pretension and initial sag of cable roof system is essential in a design process and the shape of roof is changed by pretension. The nonlinear behavior of flexible cable system has greatly an affect on the sag and pretension. This paper will be carried out analyzing and comparing the tensile forces and deflection of a cable spoke wheel system for the large span retractable roof, and analyzed to deflections and tensile forces by the post height of center hub. The double arrangement of a spoke wheel system with reverse curvature works more effectively as a load bearing system, the pretension can easily increase the structural stiffness. The cable truss system can carry vertical load in up and downward direction, and act effectively as load bearing elements.

• 한국의류학회지
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• 제32권4호
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• pp.598-607
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• 2008

Bast fibers were applied for various usages from fabrics to household care products long time ago. In this study, we investigated the physical characteristrus of water retted & chemically rotted fibers of Yucca, New Zealand hemp, Corn, Kuzu vine, Indian mallow, and Mulberry paper that have been harvested by domestic cultivation. Water retting is more effective than chemical rotting for six kinds of plant fibers. When all fibers were rotted chemically with 1% sodium hydroxide, only Kuzu vine and Indian mallow were retted. Indian mallow, Yucca, New Zealand hemp, and Com fibers have higher tensile strength than any other fibers. The crystallinity of Kuzu vine, Indian mallow, Yucca, New Zealand hemp, and Corn was as low as 60% but Yucca, New Zealand hemp were flexible. Yucca had fewer lumina whereas New Zealand hemp more lumina in cross sectional shape. Especially com fibers have a structure like sponge, and Indian mallow had a net shape. The longitudinal section of New Zealand hemp showed smooth and long shape. Mulberry paper was proved to be short and thin, which is quite appropriate for making paper. In this study, we found that plant fibers for living material could be used for cloth materials.

• 한국강구조학회 논문집
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• 제24권5호
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• pp.521-534
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• 2012

본 연구에서는 합성보의 특징을 활용하고, 일부 고강도강 적용이 가능한 단면을 개발하여 이에 대한 기초연구를 실시하였다. 본 논문은 그 첫 번째로 단위부재인 합성보의 휨성능을 실험을 통해 평가하였다. 실험결과를 통해 기존 합성보의 공칭강도 산정식 적용여부를 검토하였고, 각 구성부재를 주요변수로 하여 실험하였다. 실험결과 신형상 U형 합성보의 내력평가는 콘크리트 압축강도와 강재의 인장강도에 의한 우력모멘트로 소요모멘트에 저항하는 것으로 평가하는 것이 적합하며, 보 춤 및 강판 두께에 비례하여 내력이 안정적으로 증가하였으며, 연성거동을 하는 것으로 나타났다.

• 한국전자파학회논문지
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• 제20권10호
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• pp.1114-1120
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• 2009

전도성을 띄는 다양한 도전사(electro-thread)의 도전율을 분석하여, 그 특성에 맞게 T 매칭 구조가 없는 글자 모양에 T매칭 구조를 인가하여 닦을 수 있는 자수형 UHF RFID tag 안테나를 설계하였다. 도전사를 이용한 RFID tag 안테나는 기존의 태그와는 달리 착용감과 구부러짐의 변화에 문제가 없어 옷에 자수하여 입을 수 있는 안테나로 사용되기가 쉽다. 자수형 태그의 모양은 일반 의류에 적용하기 쉬운 영어 알파벳 'F'와 한글 자음 'ㄹ' 형태로 설계하였다. 설계된 태그를 최적화하여 제작하였으며 제작한 태그의 특성과 인식 거리 패턴을 측정하였다. 또한 물 비눗물과 소금물에 태그가 젖었을 때 인식 거리를 측정하였다.

• 한국실내디자인학회논문집
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• 제16권2호
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• pp.87-96
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• 2007

This study analyzes the place of modem architecture based on the place theory of C. N, Schultz. For applying Schultz's theory to the modern architecture, It is required to examine the modern cityscape, features of inner space of architecture and features of program. By analyzing the avant-garde architecture of Rem Koolhaas on such basis, the potentiality of placeness of modern architecture could be verified and the alternatives would be searched. It is inferred that the placeness features of Rem Koolhaas' public architecture is under the influence of the interpretation of program based on the humane background rather than the physical aspects of surroundings. The inner space shows the non-linear features, the metaphor of city. The obscurity of physical boundary illustrates the flexible features with ambiguous boundary. Consequently, the inner space expresses the surreal atmosphere that doesn't match the purposes of usage of architecture, the traditional concept. The outer shape is recognized as the by-product from the interpretation of internal program rather than it considered the surrounding context. The outer shape has the relatively simple formative shape and contrasts against the complicated inner space by using the non-physical materials. It is found that Koolhaas' architecture doesn't pursue the features of placeness of traditional concept. However, It is inferred that his architecture has the possibility of placeness by attaching the meaning through the social roles of each architecture. It gives the substantial suggestion to the modern architecture that can't easily acquire the placeness of traditional concept due to the environment of modern city.

• 한국해양공학회지
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• 제22권6호
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• pp.75-82
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• 2008

Flame bending has been extensively used in the shipbuilding industry for hull plate forming In flame bending it is difficult to obtain the desired shape because the residual deformation dependson the complex temperature distribution and the thermal plastic strain. Mechanical bending such as reconfigurable press forming multi-point press forming or die-less forming has been found to improve the automation of hull plateforming because it can more accurately control the desired shape than line heating. Multi-point forming is a process in which external forces are used to form metal work-pieces. Therefore it can be a flexible and efficient forming technique. This paper presents an optimal approach to determining the press-stroke for multi-point press forming of curved shapes. An integrated configuration of Finite element analysis (FEA) and spring-back compensation algorithm is developed to calculate the strokes of the multi-point press. Not only spring-back is modeled by elastic plastic shell elements but also an iterative algorithm to compensate the spring-back is applied to adjust the amount of pressing stroke. An iterative displacement adjustment (IDA) method is applied by integration of the FEA procedure and the spring-back compensation work. Shape deviation between the desired surface and deform￡d plate is minimized by the IDA algorithm.

• 대한의용생체공학회:의공학회지
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• 제16권4호
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• pp.481-491
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• 1995

Endovaginal and endorectal receiver only surface coils were designed for MR imaging (MRI) and $^1H$ MR spectroscopy (MRS) for the uterine cervix and the prostate. The shape of endovaginal coil wire was rectangular with round corner. Size of the coil wire was empirically determined for 7cm and 4cm along the long and short axis, respectively. The coil wire loop was supported by acryl handle and bent about $150^{\circ}$ at one side of the loop considering the average angle of the cervix to the vagina. We called this as a "spoon-type endovaginal coil". The wire of the endorectal coil was made of the flexible materials so that the wire loop became long elliptic shape by pushing the acryl handle into the plastic tube for the comfort of patients when the coil was inserted into the cervix. Then, the shape was maintained to be circle by popping out handle. Conventional spin echo (SE) and fast spin echo (FSE) sequences were used as 71 and 72 weighted imaging sequences, respectively. Matrix size was 128~$256{\times}256$. FOVs for surface coil and body coil were 14cm and 24cm, respectively. 3D volume localized in vivo $^1H$ MR spectroscopy of the human cervix and prostate was performed using PRESS or STEAM localization method with the following parameters . TR=3 sec, TE=135 msec for PRESS or 30 msec for STEAM, NEX=2, NS=48, Sl=2048, and SW=2500 Hz. Using home-built endovaginal and endorectal coils, excellent T1- and T2-images were obtained to visualize early cervical and prostate tumors. 3D volume localized in vivo IH MRS was useful to differentiate the cancerous tissue from the normal tissue.