• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.9
• /
• pp.1235-1240
• /
• 2010

Wire-woven Bulk Kagome (WBK) is fabricated by assembling helically formed wires in six directions. To date, WBK samples have been assembled manually. For industrial application, the assembly process must be automated. Furthermore, if WBK is to be fabricated using flexible wires that cannot maintain their helical shape during fabrication, a specialized automatic machine, i.e., a loom needs to be developed. In this work, we designed and constructed a loom for fabricating WBKs using flexible wires. This loom is operated by one rotation of the upper plate, two translations of the insertion device, and insertion of wires. So-called "comb devices" are placed between multiple layers of Kagome nets to prevent the wires that are already in place from getting entangled with those that are being inserted. This loom can be also used to fabricate semi-WBKs composed of helically formed wires and rigid straight wires.

• Membrane Journal
• /
• v.7 no.2
• /
• pp.75-83
• /
• 1997

The disc plate and frame type modules for reverse osmosis were developed using three different types of baffles: linear (Type 1), curved (Type 2) and parallel shapes (Type 3). Separation performance tests were carried out for the modules using NaCl and sucrose solutions under the various concentrations and operating pressures. The permeation flux and solute rejection ratio for Type 3 module were the highest within operating pressure (35bar) and flow rate (6 l/min). The flux improvement ratio of Type 2 or 3 to Type 1 for NaCl solution decreased as operating pressure increased: flux improvement ratios of Type 3 for 1wt% of NaCl solution were about 100 and 10% at 10 and 35bar, respectively. However, the flux improvement ratio for sucrose solutions varied with the operating pressure and concentration. The permeation flux for Type 3 depended on the flow rate linearly, which is higher than that of turbulent flow region in the smooth channel.

• Journal of Fashion Business
• /
• v.13 no.4
• /
• pp.178-190
• /
• 2009

The purpose of this study is to make reference for geometric fashion by investigating geometric patterns by linear types and to propose high value added print and fashion design by designing and producing geometric prints and apparel with them focusing on digital textile printing. As a method of the study, visual and textural data were investigated for theory of geometric pattern and fashion design samples were illustrated. The geometric pattern could be defined as abstract pattern which was crossed with straight line or curve. We could group it into three classes such as straight linear, curved, and mixed type. Images varied with linear types. The image of straight linear type was sharp and modern, that of curved one was soft and feminine and that of mixed one was gorgeous and artistic. And then, 3 geometric prints and 3 one-pieces were designed. The concept of design was simple optimism which was based on sixties. Target was young optimistic women group from the mid teens to the mid twenties who continued to seek after their unique individuality keeping their modern lifestyle. Geometric patterns with straight linear, curved, and mixed type were designed and dresses which went well with them were designed and produced. According to the result of this study, images of geometric fashion can be represented diversely by varying linear type, digital textile printing is good method for high value added geometric fashion because of its high quality and degree of sensitivity, and geometric pattern is a good source for contemporary fashion.

• Journal of Korean Elementary Science Education
• /
• v.40 no.3
• /
• pp.326-342
• /
• 2021

In this study, experimental guide materials for teachers were developed so that algorithm expression, the core of computational thinking, can be applied to experimental activities. The experimental manuals presented in text was converted into an algorithmic form with a linear, branched, and repetitive structure according to the information visualization process using flowchart symbols. As an example, an experiment guide materials was developed by applying an algorithm expression to an experiment to find out the properties of a magnet. The developed experiment guide materials is different from the existing experiment guide materials expressed only sequentially in that it has an algorithmic structure of branching and repetition in which the suitability and judgment of information are expressed, and that the experiment process is visualized and expressed. It is expected that the experimental guide materials developed in this study will help teachers to understand algorithmic thinking and to implement experiments using it.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.92-92
• /
• 2009

조선업을 포함한 다양한 산업 분야에서 후판 강재의 수요량 증가와 함께 사용 범위 또한 폭넓게 되고 있다. 특히, 선박의 수송효율의 극대화를 위하여 컨테이너선의 대형화가 급속하게 진행되고 있으며, 2009년 현재1,300TEU 이상의 초대형 컨테이너선이 건조되고 이다. 이처럼 용접구조물의 초대형화에 따른 사용강재 또한 고강도 극후물화 되고 있다. 현재 선박에 적용중인 고강도 강재는 EH47 강재로 YP 460MPa 급의 강재가 Hatch Coamming부에 적용중에 있으며, 강재의 두께 또한 70mm 이상이다. 이러한 고강도 극후물재의 강구조물에 적용에 따른 선급협회에서는 용접부에서의 취성균열 전파에 의한 취성파괴의 위험성이 있으므로 강재의 두께를 제한하고 더욱 엄격한 파괴인성값을 요구하고 있다. 일본선급협회(NK)를 중심으로 취성균열의 정지를 위한 모재의 요구 성능등에 관한 연구들이 진행되고 있다. 이 연구의 대부분의 전제 조건은 선박의 블럭과 블럭의 조립시에 용접부가 직선형이 아닌 계단형(Butt shift)를 하는 것으로 하고 있으므로, 국내의 조선건조 공법의 현실과는 거리감이 있다. 본 연구에서는 국내 조선사에서 수행중인 직선 이음부에 대한 시공 공법에서 취성균열이 발생하여 진전 되더라도 균열을 정지 시킬 수 있는 기술에 관한 연구를 수행하였다. 균열의 진전은 대부부의 연속면에서는 정지를 시키지 못하고 직진 전파 하여서 파괴에 도달하게 된다. 따라서 뭔가의 불연속적인 면을 임의로 생성하여야 균열을 정지 시킬 수 있다. 본 연구에서는 이러한 균열의 정지 방법으로 형상적인 측면과 재료적인 측면에서 검토를 수행하였다. 형상적인 측면에서는 균열을 정지 시키고자 하는 위치에 불연속적인 면을 만들기 위하여 일정 크기의 hole을 만들어서 균열을 정지시켰으며, 재료적인 측면에서는 고인성의 용접재료를 사용하여서 취성균열이 진행하는 경로에 인성을 높은 재료를 적용하여 불연속적인 면의 생성과 함께 인성을 높여서 균열을 정지 시키는 기술을 개발하였다. 이러한 기술의 개발을 통하여 취성균열의 전파에 의한 파괴를 방지 할 수 있으며, 용접구조물의 안전성 확보를 가능하게 하였다.

• The Journal of the Korea Contents Association
• /
• v.10 no.11
• /
• pp.446-451
• /
• 2010

To investigate the vortex induced vibrations the 2-d.o.f. spring mounted circular cylinder was tested in the wind tunnel. The circular cylinder was designed to have the translational and the rotational mode uncoupled to each other. During the wind tunnel tests the resonance behaviors of the translational and the rotational modes by the locking-on phenomena were observed. From the locking-on phenomena observed it is shown that the vortex shedding is correlated with the responses of the structures. And the forces generated by the vortex shedding are influenced by the amplitudes and the frequencies of the cylinders.

• Journal of the Korean Vacuum Society
• /
• v.15 no.4
• /
• pp.331-337
• /
• 2006

Cavity-type beam position monitors were developed in collaboration with KEK to use for the future accelerators such as international linear collider (ILC) or x-ray free electron laser (XFEL) in PAL. BPM components such as BPM cavity, beam tubes, waveguides and feedthroughs were assembled by brazing at the same time to reduce mechanical errors during the fabrication. There are four screwed pins around outer rim of the cavity for the tuning of cavity frequency and x-y isolation. The resonance frequency of BPM is 6.422 GHz, the inner diameter of cavity is 53.822 mm, and the range of mechanical adjusting is $+ / - 250{\mu}m$. The x-y isolation was measured better than -40 dB after tuned. Test results of signal forms, x-y isolations, sensitivities are satisfied within requirements for the KEK ATF2 beam line.

• Journal of The Korean Association For Science Education
• /
• v.35 no.1
• /
• pp.121-130
• /
• 2015

Identifying students' achievement level and reflecting it on educational policy making or instructional improvement by analyzing the results of nationwide standardized assessment is an integral part of accountability in education. On the basis of this premise, we analyzed the characteristics of National Assessment of Educational Achievement (NAEA) items for middle school science subject conducted from 2010 to 2013 by using the option response rate distribution curve, the fittest graph estimated from the response rate of correct/incorrect options by achievement score. Furthermore, we classified the type of option response rate curve in terms of correct and incorrect options. Results of the analysis of option response curve showed that five types of correct option response curve (S-shaped, J-shaped, straight-shaped, F-shaped, and step-shaped) and 4 types of incorrect option response curve (down-slope, flat, mound, and up-slope) were identified. The most common type of items was the combination of S-shaped correct option response curve and down-slope incorrect option response curve, which are considered as appropriate items to discriminate the students according to achievement level. Moreover, correct option response was found to be correlated with incorrect option response. Based on the results, we also discussed some implications on teaching-learning method and classroom assessment in science education.

• Journal of the Korean Geosynthetics Society
• /
• v.18 no.2
• /
• pp.23-36
• /
• 2019

In this paper, field measurement of the Block Type Mechanically Stabilized Earth (MSE) wall curved section was performed, and the reinforced area of the curved part is studied through the result. MSE method has been applied to various fields because of easy construction and excellent economic efficiency, so that it can be easily access in our life. However due to lack of compaction and stress concentration phenomenon, cracks and collapse occur in the curve of MSE wall, which is important for safety. The cause of collapse is lack of research on curved section, lack of design criteria, lack of construction due to economical efficiency and shortening of construction period, insufficient compaction space. In this study, therefore, it was examined the existing design and construction standards, analyzed the cause through accident examples of the curved section of the Block Type MSE wall. As a result, the horizontal displacement of the curved section was 90% higher than that of the straight section and 60% higher than that of the concave section. In the case of the convex section in the curved section reinforcement region, the maximum displacement is shown in the H/2 section in the horizontal direction from the center of the MSE wall, and the range of influence from H is shown. In the case of the concave section, the maximum displacement is shown in the center, The minimum displacement was confirmed in H/4 section in the horizontal direction from the center of the MSE wall. As a basic study on the reinforcement area rehabilitation through the actual construction of block type MSE wall, the behaviors of the straight part and the curved part were compared and analyzed. And analyzed the reinforced area in order to reduce the damage of the stress concentration phenomenon and secure the safety.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1993.10a
• /
• pp.627-631
• /
• 1993

스크류 압축기는 진동이 적고, 소형이면서 고효율을 유지하기가 용이하다는 특징을 가지고 있으며, 원통형 밀패용기 내에 암,수로터가 서로 반대 방향으로 맞물려 회전하면서, 로터홈과 케이싱 사이에 생기는 공간의 용적이 로터회전에 의해서 가스를 흡입, 압축, 배출하는 합축기 이다. 본 연구는 로터의 치형 함수의 기하학적성질 및 제한사항을 고려하여, 대칭 치형을 치수의 조합과, 원, 점, 직선, 타원을 사용하여 비대칭 치형을 설계하였다. 본 연구의 목적은 설계된 치형과 기존의 치형을 치형 형상의 변화에 따른 특성값 (실라인길이, 누설삼각형, 용적곡선, 흡입 및 토출 홈면적)의 변화에 대하여 연구함으로서 성능검토를 시도하였다.