• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.228-233
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• 2016

Auxetic material is a material which has negative Poisson's ratio(NPR). Auxetic material shows some distinctive property like high energy absorbing property and high shear modulus. Among these, synclastic curvature is very interesting characteristic. When synclastic-curvature-material bends, it changes its shape like dome, contrary to non-auxetic material which changes its shape like saddle(anticlastic). This distinctive property could make it easy to manufacture curved structure like nose cone or wing panel in aerospace engineering. In this study, we studied a quantitative analysis about synclastic curvature of re-entrant panel with finite element model. We suggested a concept 'Degree of Synclasticity(DOS)', which means a ratio of curvature of load-direction and load-orthogonal direction. We studied the variation of DOS with two factor, unit cell inner angle(${\theta}$) and load position angle(${\phi}$). DOS decreases as ${\theta}$ increases because the unit cell goes out of auxetic-shape. As ${\phi}$ varies, DOS changes in a large range. So proper optimization of ${\phi}$ would be needed for application.

• 한국소음진동공학회논문집
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• 제12권11호
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• pp.864-872
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• 2002

In this study, the effect of planform curvature on the stability of coupled flow/structure vibration is examined in transonic and supersonic flow regions. The aeroelastic analysis for the frequency and time domain is performed to obtain the flutter solution. The doublet lattice method(DLM) in subsonic flow is used to calculate unsteady aerodynamics in the frequency domain. For all speed range, the time domain nonlinear unsteady transonic small disturbance code has been incorporated into the coupled-time integration aeroelastic analysis (CTIA). Two curved wings with experimental data have been considered in this paper MSC/NASTRAN is used for natural free vibration analyses of wing models. Predicted flutter dynamic pressures and frequencies are compared with experimental data in subsonic and transonic flow regions.

• 한국의류학회지
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• 제44권3호
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• pp.485-498
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• 2020

Sanitary pads are used with for the sanitization of menstruation bleeding. In this research, twenty medium size disposable sanitary pads were selected from domestic and international brands in order to analyze their shape and size. Additionally, 6 sanitary pads were selected among the 20, and user experience evaluations were completed. The analysis on the shape of the 20 sanitary pads showed that straight-shape pads existed more than curved-shape pads. The means of total pad length, wing length, wing width, front pad width, back pad width, front pad length, and back pad length were 24.5 cm, 8.8 cm, 3.0 cm, 10.0 cm, 10.2 cm, 11.6 cm, and 13.0 cm, respectively. All selected pads were medium size; however, detailed sizes varied between brands. Eighty-one women participated on user experience evaluation. Participants felt that brand F was the longest and brand D the shortest. The results matched with the results on actual pad length measurement. Participants evaluated the fit of brand E most positively and fit of brand A most negatively. The current study provides valuable information for developing disposable sanitary pads.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.366-366
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• 2016

Nanoscale observation of attachment systems of animals has revealed various exquisite multiscale architectures for essential functions such as gecko's locomotion, beetles' wing fixation, octopuses' sucking and crawling. In particular, the hierarchical 3-dimensional hexanonal nano-architectures in the tree frog's adhesion is known to have the capability of the enhancement of adhesion forces on the wet or rough surfaces due to the conformal contacts against rough surfaces and water-drainable micro channels. Here, we report that tree frog-inspired patches using unique artificial 3-dimensional hexagonal structures can be exploited to form reversibly enhanced adhesion against various highly curved and rough surfaces in dry and wet condition. To investigate the adhesion effect of micro-channels, we changed the arrangement of microstructure and spacing gaps between micro-channels. In addition, we introduced the 3-dimensional hexagonal hierarchical architectures to artificial patches to enhance to conformal contacts on the various rough surfaces such as skin and organs. Using the robust adhesion properties, we demonstrated the self-drainable and comfortable skin-attachable devices which can measure EKG (electrokardiogramme) for in-vitro diagnostics. As a result, bio-inspired programmable nano-architectures can be applied in versatile devices such as, medical patches, skin-attachable electronics etc., which would shed light on future smart, directional and reversible adhesion systems.

• 대한조선학회논문집
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• 제48권2호
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• pp.113-120
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• 2011

Fins are widely used for roll stabilization of passenger ferries and high performance naval ships, among others. The Coanda effect is noticeable when a jet stream is applied tangentially to a curved wing surface since the jet can augment the lift by increasing the circulation. The Coanda effect has been found useful in various fields of aerodynamics and speculated to have practical applicability in marine hydrodynamics where various control surfaces are used to control motions of ships and the other offshore structures. In the present study, numerical computations have been performed to find proper jet momentum coefficients $C_j$ and trailing edge shapes suitable for the application of the Coanda effect to a stabilizer fin. The results show that the lift coefficient of the modified Coanda fin at the zero angle of attack ${\alpha}$ identically coincides with that of the original fin at ${\alpha}\;=\;25^{\circ}$ when Coanda jet is supplied at the rate of $C_j$ = 0.1. It is also shown that a fixed type fin stabilizer utilizing the Coanda effect can be implemented without changing the fin angle to actively control the motions of ships and the other offshore structures.

• 한국의류학회지
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• 제27권3_4호
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• pp.407-417
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• 2003

The purpose of this study is to develop designs and patterns of a functional brassiere. For this purpose, women who have protruding and drooping breasts with 75B for their brassiere size were sampled. The fitting test for the fitness and function of test brassiere and control brassiere were carried out twice and compared the results from the both in terms of front, rear and side looks. The results of this study can be summarized as follows; 1. The results from measuring the level of sag and spread, and volume and protrusion of breasts shows that there are some distinctive differences in the measurements before and after wearing the test brassiere and the test brassiere is proved to be very effective in correcting breasts' shapes. 2. Front look: Since the two front cutting lines of the test brassiere served to have the curved main part pressing against the breasts, it could support breasts to more than satisfactory level. In addition, upperline panel and side panels of the test brassiere were found to have the upperline of the upper cup pressed against the breasts and at the same time it pressed and gathered the flab around upper part of the breasts and armpits that helped to rearrange the shape of the breasts. It is also proved that the two-pieced test brassier was found to be more functional in supporting the lower cup of the breasts. 3. Rear look: The test brassier was made up of two wide U-shaped wings with 2.5cm tape on its lower sides. Each wing has 4 lines and 3 hems (5.5cm). For this reason, the test brassiere was tighter and better fitted on its back. 4. Side look and entire look: The wings of the test brassiere might look wider than that of the control brassier which has conventional straight-shaped wings, but it was analyzed that the test brassiere held the upper and lower sides of the wings more effectively to be more pressed against the breast. Therefore, the test brassiere scored higher in terms of adjusting to body movements, while the control brassiere looked better in overall terms. 5. The functional brassier fur protruding and drooping breasts developed from the experiments of this study is a full side stretch brassiere which covers the entire breasts satisfactorily. The pattern drafting methods are suggested in to .

• Journal of Biosystems Engineering
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• 제12권3호
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• pp.30-41
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• 1987

The geometrical shape of a plow bottom may be the most important factor affecting the performance of a plow for a given soil and operating conditions. There are various designs of the Jaenggi (Korean plow) available commercially, which may be different from each other and from the plow (Western plow) in respect to the shape and performance. This study was intended to investigate the geometrical characteristics of Jaenggi. The coordinate digitizer equipped with 3 potentiometers was designed and manufactured for measurement of the shape of curved plane of moldboard and share. The digitizer was connected to a microcomputer having the data acquisition system. This device was used to analyze the plow bottoms of 5 differently-made Jaenggis and one cylindrical plow. The results of the study are summarized as follows: 1. It was possible to measure easily and quickly the curved plane of plow bottom and to plot the view on three major plans using the coordinate digitizer electrically connected to a microcomputer system. 2. The shape of five Jaenggi bottoms analyzed could be characterized by the cutting angle having the range of $33-42^{\circ}$, the maximum share-lift angle of $41-50^{\circ}$, and the setting angle of moldboard wing of $46-70^{\circ}$. The most critical difference of the shape factors between the Jaenggi and the plow was found in the maximum share-lift angle, the former was more than twice as much as the latter. 3. The analysis of the shape of Jaenggi bottoms showed that the share projections on 3 major plans had a varied triangle, which was quite different from that of plow bottom. Especially, it was analyzed that the shape of furrow slice for the Jaenggi had a skewed rectangle, leaving a considerable height of the ridge at the furrow bottom. 4. The dihedral angle was similar range of $30-85^{\circ}$ for the all bodies investigated, but the directional angle was somewhat different from each other. The difference in directional angle was $5^{\circ}$ for the plow, $20^{\circ}$ for the Jaenggi A and $30^{\circ}$ for the Jaenggi B. 5. Area of the spherical representation region was 0.0328 for the plow, 0.1194 for the Jaenggi A and 0.1716 for the Jaenggi B. This may indicate that the plow came close to a working surface and the Jaenggi A and the Jaenggi B departed from a working surface to a somewhat greater extent.

• 비파괴검사학회지
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• 제34권5호
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• pp.369-376
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• 2014

항공기 구조물 표면에 발생하는 외부 충격은 크랙과 같은 손상을 발생시킬 수 있으며 이는 차후 큰 결함을 야기하기 때문에 충격과 손상을 탐지하고 위치를 추정하는 것은 구조 안정성 모니터링에 있어 중요한 부분이다. 본 연구에서는 능동, 수동 센싱기법을 조합한 L-형상 압전체 센서 배열을 사용하여 충격과 손상을 탐지할 수 있는 기법을 개발하였다. 수동 센싱기법으로 1개 센서군 당 3개의 센서를 L-형상으로 배치하여 충격 발생 각도를 추정하고 2개의 센서군을 사용하여 충격위치를 탐지하는 방법을 도입하였다. 이 수동 센싱기법을 유도초음파 기반의 능동 센싱기법에 확대 적용하여 동일한 압전소자로 충격 탐지와 더불어 손상을 탐지할 수 있는 방법을 개발하였다. 이 기법은 방향에 따른 파동의 속도 변화와 같은 구조물에 대한 정보 없이도 위치 추정이 가능하여 비등방성 구조 내에서도 정확한 충격 및 손상 위치 정보를 얻을 수 있다. 개발된 기법을 날개 형태 구조물 및 CFRP 판에 적용하여 실험적으로 정확한 충격 및 손상 위치를 추정할 수 있음을 증명하였다.

• 건축역사연구
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• 제31권6호
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• pp.59-68
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• 2022

This paper is an architectural historical study on Chimi of Hwangnyongsa Temple. In this research, the shape and cross-section of the chimi are reviewed. The results of the study are as follows. The chimi is a form in which the head part facing the maru is omitted, and the upper and lower body are separated. The upper and lower bonds are assembled into a two types of joint throughout the side of the torso, and then bound with an iron strap. Because of the absence of ridge line in the front, and the narrow curved surface which makes the side plate close to the plane, the entire cross-section is triangular, and the rear plate maintains the shape of the chimi. The naerimmaru connected to the side of the chimi has a slope, so it is clear that the chimi was used on the woojingak-jibung(hipped-roof), and the wing part and back of the chimi are erected on the side roof. The height of the yongmaru and chunyeomaru is about the same and the roofing tiles of those are in contact. The roofing tiles of chunyemaru should be cut to fit the angle of the contacting part. The maru is 30 stories high of roofing tiles as a result of the on-board survey. Based on reference on the shape and timing of the production of chimi, the height of chimi, and the maru is believed to have been built before the Unified Silla Period and used in buildings with at least seven-kan frontage. Buildings corresponding to these construction conditions can be seen as Central hall and East hall in Hwangnyongsa temple.