• Structural Engineering and Mechanics
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• 제88권1호
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• pp.83-94
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• 2023

An accurate and highly efficient inverse element labelled iPCB is developed based on the inverse finite element method (iFEM) for real-time shape estimation of plane-curved structures (such as arch bridges) utilizing onboard strain data. This inverse problem, named shape sensing, is vital for the design of smart structures and structural health monitoring (SHM) procedures. The iPCB formulation is defined based on a least-squares variational principle that employs curved Timoshenko beam theory as its baseline. The accurate strain-displacement relationship considering tension-bending coupling is used to establish theoretical and measured section strains. The displacement fields of the isoparametric element iPCB are interpolated utilizing nonuniform rational B-spline (NURBS) basis functions, enabling exact geometric modelling even with a very coarse mesh density. The present formulation is completely free from membrane and shear locking. Numerical validation examples for different curved structures subjected to different loading conditions have been performed and have demonstrated the excellent prediction capability of iPCBs. The present formulation has also been shown to be practical and robust since relatively accurate predictions can be obtained even omitting the shear deformation contributions and considering polluted strain measures. The current element offers a promising tool for real-time shape estimation of plane-curved structures.

• 한국정밀공학회지
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• 제24권1호
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• pp.93-100
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• 2007

In this study, an investigation was made on bristles for the prosthetic and periodontally involved patients based on the previous studies. The purpose of this study was to investigate the ideal location and dimensions of bristles for the patients who were installed with fixed prostheses and severely involved periodontitis. 3D scanner was used to develop 3D visual models of bristles and teeth. These models were developed to be used for designing the ideal bristles for the prosthetic and periodontally involved patients. For the ideal design of bristle, interproximal area of dental arch and bristle must get into maximum and standard teeth may have to be chosen from many gypsum molds. During the design process the factors should be considered that influence the removal of plaque by bristle.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 가을 학술발표회논문집
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• pp.98-105
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• 1993

A method for shape design sensitivity analysis for axisymmetric shells of general shapes is developed. The basic approach is to divide the structures into many segments. For each of the segments, the formula for a shallow arch or shell can be applied and the results assembled. To interconnect those segments, the existing sensitivity formula, obtained for a variation only in the direction perpendicular to the plane on which the structure is mapped, has been extended to include a variation normal to the middle surface. The method follows the adjoint variable approach based on the material derivative concept as established in the literature. Numerical examples are taken to illustrate the method and the applicability to practical design problems.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.542-547
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• 2004

The objective of this study is 0 estimate wind pressure acting on soundproof tunnel and noise reduction through the tunnel. For the purpose various shape of scale models were prepared and drag forces acting on each models were measured in wind tunnel. And numerical simulation was performed to confirm experimental results. As a result the lowest drag force coefficient of 0.59 was obtained in the case of arch roof shape model. Noise reduction through soundproof tunnel was simulated by using ray tracing method according to various open ratio of its roof area.

• 한국의상디자인학회지
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• 제20권4호
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• pp.117-130
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• 2018

As women wear shoes for a long time due to aesthetic elements and working environment, many women experience discomfort and deformation in their feet due to their shoes and the production of comfortable shoes is becoming an important issue. The purpose of this study is to investigate the factors affecting the grip of shoes by foot type, shoe design, and wearing attitude of shoes. Through this, we suggest solutions for foot discomfort due to wearing shoes and help to prevent foot related diseases. The study results are as follows; first, a wide foot, square-type, and high or low arch (hollow foot or flat foot) among foot shapes influenced the fatigue and pain of feet, and big feet over 250mm-long, wide feet, square-type feet, and high-arch feet (hollow foot) had an influence on distortion and side effects. Second, among the characteristics of wearing shoes influencing foot discomfort, the higher the shoe heels were, the narrower the surface covering the feet was (pumps and mule), and the shoes with high front heels and narrow back heel area, the shoe wearer had a higher possibility of experiencing fatigue and pain and even had not only fatigue and pain but also side effects when she wore pointed shoes. Third, a shoe wearer experiences fatigue and pain if she wears shoes for a shorter period of time, stay stood while wearing shoes for a short time, and wears shoes that are bigger or smaller than the actual shoe size. Fourth, fatigue and pain experiencers and distortion and side effects experiencers all responded that they change into other shoes to deal with foot discomfort and that they directly massage their feet.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.27-32
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• 2022

There has always been a demand for orthodontic treatment. Orthodontic treatment allows tooth to be arranged by flexible arch wire fixed with tooth-attached brackets. Arch wire generate constant pressure to tooth brackets which moves the teeth to proper place. When the bracket transmits force, the braced wing of the bracket may deform. Deformed tie wing will lead to lost tension of elastic ligature. Then, lacking grip between tie wing and ligature might delay the tooth movement. Furthermore, tooth brackets used for orthodontic treatment make contact with in direct oral surface and this cause feeling of irritation that comes from height of tooth braces. This study suggests an optimal teethe bracket design to make up for inconvenience by shorten the height of bracket and complement the shape of bracket to reduce strain rate using finite element analysis. As a result, new optimal design of teethe bracket indicates lower strain rate of the bracket wing and takes good effects of shorten body height in terms of convenience.

• 한국강구조학회 논문집
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• 제10권3호통권36호
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• pp.509-523
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• 1998

본 연구에서는 이축 대칭단면을 갖는 박벽 원형아치의 안정성해석을 수행할 수 있는 유한요소 이론 및 엄밀해를 제시하기 위하여, 가상일의 원리를 이용한 3차원 연속체의 운동방정식을 제시한다. 박벽단면의 구속된 비틂(restrained warping)효과를 고려하는 박벽 곡선보의 변위장을 도입하고 이를 연속체의 운동방정식에 대입하여 단면에 대해 적분함으로써 박벽 곡선보의 운동방정식을 유도한다. 단순지지되고 이축 대칭단면을 갖는 박벽 곡선보의 면외좌굴에 대한 엄밀해를 제시하고 박벽 곡선보를 유한요소로 분할하여 요소의 변위장을 요소 변위벡터에 관한 3차의 Hermitian 다항식으로 나타내어 운동방정식에 대입함으로써 탄성 강도행렬과 기하학적 강도행렬을 유도한다. 또한 본 연구에서 얻어진 엄밀해와 박벽 곡선보요소를 이용한 유한요소해석결과를 다른 연구자들의 결과 및 직선 박벽보 요소를 이용한 해석결과와 비교 검토를 함으로써 분 연구의 타당성을 입증한다.

• 한국응용곤충학회지
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• 제35권3호
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• pp.216-220
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• 1996

Drosophila simulans와 D. mauritiana는 동일 subgroup에 속하는 동포종으로, 전자는 전세계 분포종이며, 후자는 Mauritius 섬에만 서식하는 지역종이다. D. simulans의 성즐(sex comb)은 약 9.83개의 치열로 구성되어 있으며, D, mauritiana의 성즐 치열수는 약 12.90개 정도이다. D. simulans의 생식궁(genital arch)은 큰 반월형이며, D. mauritiana는 가는 막대형이다. 두 종간 성즐의 치열수와 생식궁의 형태적 차이에 미치는 X 염색체의 효과를 알아보기 위한 유전적 분석을 실시하였으며, 이를 위하여 X 염색체상 돌연변이 유전자들을 가지는 D. simulans 계통과 정상의 D. mauritiana 사이의 잡종 {TEX}$F_{1}${/TEX}을 부모계통과 역교배를 실시하여 얻은 자손들을 대상으로 상기 두가지 형질의 분석을 실시하였다. F1의 성즐 치열수는 평균 11.79개 정도였으며, 외부생식기의 일반적인 형태는 D. simulans와 D. mauritiana의 중간형이었다. 성즐의 치열수와 외부생식기의 주요 특징분석에서 X 염색체 효과에 따른 유의적인 차이는 거의 없는 것으로 나타났다.

• 한국공간구조학회논문집
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• 제10권3호
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• pp.81-90
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• 2010

대공간구조물은 일반 라멘구조와는 다른 동적특성을 가지고 있으며, 이런 동적특성에 관해 많은 연구가 수행되고 있다. 그러나 대부분의 연구는 특정 형태의 대공간구조물에 대해 수행되었으며, 내진설계를 위해 직접적으로 이용 가능한 연구결과는 매우 제한적이다. 본 연구에서는 대공간구조물의 기본적인 동적특성을 내재한 트러스-아치구조물을 대상으로 양단의 기둥의 길이가 다른 경우에 트러스-아치구조물의 지진응답변화를 분석하고자 한다. 양단 기둥 길이의 차이에 따라, 가속도 응답이 수평방향에 비해 수직방향에서 더 많은 영향을 받는다. 따라서 상부구조물을 지지하는 하부구조물의 강성이 다른 경우에 대공간구조물의 내진설계에 있어서 수직방향 응답에 대한 고려가 더욱 많이 요구된다.

• 치과방사선
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• 제28권2호
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• pp.491-503
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• 1998

A cystic compound odontoma in the maxillary sinus occurred in a 13-year-old boy. who had missing right upper third molar without having the history of extraction of the wisdom tooth. He complained nasal stuffiness. headache. and pain on the affected face. resembling any sign and symptoms of the maxillary sinus problems. The cystic compound. sized 2 x 1.5 cm in diameter was pedunculated and attached on the posterior wall of the right maxillary sinus and above the antral floor. The location of the compound odontoma in the maxillary sinus was confirmed after panoramic. waters. spiral tomographic. CT examinations and surgical exploration. Its location was on the medial. posterior. superior to the normal position of the maxillary third molar or the maxillary dental arch. The cystic odontoma in the maxillary sinus made the patient have the signs and symptoms of maxillary sinusitis. The cystic compound odontoma might be originated from the dental lamina of the missing upper right third molar. The 'V principle' of the upper jaw growth and the pneumatization process of the maxillary sinus could explain why the compound odontoma had peduncular shape and the location of odontoma was on the medial. superior to the normal position of the maxillary dental arch.