• 한국지반환경공학회 논문집
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• 제11권8호
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• pp.49-55
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• 2010

병렬터널의 이격거리가 근접할수록 응력집중으로 인하여 필라(pillar)의 파괴 위험이 큰 만큼 필라의 응력 검토 및 필라의 강도를 고려한 필라의 안정성 평가는 병렬터널의 이격거리 검토 시 매우 중요한 사항이다. 본 연구에서는 필라의 안정성을 구하는 방법 중 하나인 수치해석의 요소크기를 검토하여 필라부 안정성 검토에 대한 체계적인 분석을 제안하였다. 그 결과, 강도응력비는 요소크기에 따른 영향이 크게 없었고, 강도강소법에 의한 안전율은 요소가 작을수록 안전율이 작게 나왔다. 특히 지반이 풍화암인 경우 요소크기에 대한 안전율 값 차이가 크므로 지반이 불량한 경우 요소의 크기를 작게하는 것이 안정적인 결과를 나타냈다.

• Genomics & Informatics
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• 제12권3호
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• pp.87-97
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• 2014

Although the number of protein-coding genes is not highly variable between plant taxa, the DNA content in their genomes is highly variable, by as much as 2,056-fold from a 1C amount of 0.0648 pg to 132.5 pg. The mean 1C-value in plants is 2.4 pg, and genome size expansion/contraction is lineage-specific in plant taxonomy. Transposable element fractions in plant genomes are also variable, as low as ~3% in small genomes and as high as ~85% in large genomes, indicating that genome size is a linear function of transposable element content. Of the 2 classes of transposable elements, the dynamics of class 1 long terminal repeat (LTR) retrotransposons is a major contributor to the 1C value differences among plants. The activity of LTR retrotransposons is under the control of epigenetic suppressing mechanisms. Also, genome-purging mechanisms have been adopted to counter-balance the genome size amplification. With a wealth of information on whole-genome sequences in plant genomes, it was revealed that several genome-purging mechanisms have been employed, depending on plant taxa. Two genera, Lilium and Fritillaria, are known to have large genomes in angiosperms. There were twice times of concerted genome size evolutions in the family Liliaceae during the divergence of the current genera in Liliaceae. In addition to the LTR retrotransposons, non-LTR retrotransposons and satellite DNAs contributed to the huge genomes in the two genera by possible failure of genome counter-balancing mechanisms.

• 대한전자공학회논문지SP
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• 제41권5호
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• pp.165-173
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• 2004

수리형태학을 이용한 영상분할의 분할 성능은 우수하지만 너무 많은 영역으로 분할되는 경향이 있는데, 후처리 과정을 사용하지 않고 이러한 문제를 해결하기 위해서는 마커 추출에 사용되는 구조요소의 크기를 증가시켜야 한다. 그러나 구조요소의 크기가 너무 크면 영역의 경계를 제대로 분리해낼 수 없기 때문에 본 논문에서는 영상분할의 성능 개선을 위해 수리형태학적 구조요소를 선택적으로 적용하였다. 이를 위해 평균국부분산과 영상의 기울기를 이용하여 입력 영상을 질감 영역, 에지 영역, 단순 영역으로 분류하였다. 그리고 각 영역별로 구조요소의 크기를 선택적으로 적용하여 영상이 과분할 되는 원인을 제거하였다. 실험 결과, 화소의 밝기 값이 비슷한 영역에 대해서도 영상이 잘 분할됨을 확인하였고 기존의 방법보다 질감 영역 및 에지영역을 정확하게 찾아냄을 확인할 수 있었다.

• 한국지반공학회논문집
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• 제28권12호
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• pp.77-86
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• 2012

본 연구에서는 개별요소법을 적용하여 화강암 기원의 풍화토에서 입자 크기와 입자크기 분포 특성 중 최대입경/최소입경의 비가 강도정수에 미치는 영향을 살펴보았다. 입자크기와 입도분포가 변화할 때의 전단강도 특성 변화를 규명하기 위하여 개별요소법 수치해석을 실시하였다. 점착력이 0.25MPa, 내부마찰각이 $29^{\circ}$인 강도특성을 갖는 기준시료를 수치해석적으로 구현한 후, 간극률을 기준시료와 동일하게 유지하면서 입자의 크기와 입도분포를 바꾸어 가며 점착력과 내부마찰각의 변화를 살펴보았다. 수치해석결과 평균입자의 크기가 커질수록 점착력의 현저한 감소가 관찰되었으며, 내부마찰각의 변화는 미미하지만 증가하는 경향을 보였다. 이러한 연구결과는 입도만을 이용하여 간편하게 화강풍화토의 강도정수 산정 시 활용될 수 있을 것으로 판단된다. 특히 풍화상태가 점이적으로 변화하는 화강풍화토의 경우, 현장시험과 실내시험을 통하여 일부 구간에서 측정된 입도-강도 자료가 있을 때, 이러한 시험들이 수행되지 않은 구간에 대해서도 입도분포를 통해 간편하게 강도특성을 규명할 수 있을 것으로 여겨진다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1410-1413
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• 2004

Finite element method is very effective method to simulate the forming processes with good prediction of the deformation behaviour. For the finite element modeling of sheet mental forming the accurate tool model is required. Due to the geometrical complexity of real-size part stamping tools it is hard to make FE model for real-size auto-body stamping parts. In this paper, it was focussed on the drawability factors on auto-body panel stamping by AUTOFORM with using tool planning alloy to reduce law price as well as high precision from Design Optimization of die. According to this study, the results of simulation will give engineers good information to access the Design Optimization of die.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.62-65
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• 2000

For saving time and cost of experiment Finite Element Method has been developed for several decades. It's the defect of FEM that when we are in processing of finite element analysis, the material if deformed so much that we can't proceed analysis any more. In this case, the remeshing process should be done on this material. In hot forging process, almost all remeshing process does not consider flash of the material. Because as mesh size become swatter, consuming time become larger. But if mesh size is big, there is the defect that the result of analysis is not so accurate. So, new remeshing algorithm is needed to save time and to get more accurate result.

• E2M - 전기 전자와 첨단 소재
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• 제8권1호
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• pp.1-5
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• 1995

In this study, a piezoelectric fan was fabricated using piezoelectric element of 0.13PZN-0.41PZ-0.46PT prepared by extruding method. The sizes of the piezoelectric element and the piezoelectric fan were adjust to utilize commercial ac source(100V, 6OHz). The size of the piezoelectric element was $0.26{\times}19.5{\times}45$mm and the resonant frequency and the electromechanical coupling coefficient were 31.26KHz, 31.58% respectively. The size of the piezoelectric fan was $0.62{\times}19.5{\times}78.5$mm and the maximum displacement was 40mm.

• 대한기계학회논문집A
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• 제29권3호
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• pp.484-494
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• 2005

Finite element method is very effective method to simulate the forming processes with good prediction of the deformation behaviour. For the finite element modeling of sheet mental forming the accurate tool model is required. Due to the geometrical complexity of real-size part stamping tools it is hard to make FE model for real-size auto-body stamping parts. In this paper, it was focussed on the drawability factors on auto-body panel stamping by AUTOFORM with using tool planing alloy to reduce law price as well as high precision from Design Optimization of die. According to this study, the results of simulation will give engineers good information to access the Design Optimization of die.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.794-798
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• 2004

This paper is analysis of stiffened opening thick plate on foundation. This paper has the object of investigating natural frequencies of opening thick plates on Pasternak foundation by means of finite element method and providing Kinematic design data for mat of building structures. In this paper, vibration analysis of rectangular opening thick plate is done by use of Serendipity finite element with 8 nodes by considering shearing strain of plate. And vibration analysis of stiffener is done by used of Timoshenko beam-column element wit 3 nodes. It is shown that natural frequencies depend on not only Winkler foundation parameter but also shear foundation parameter, opening position, opening size, stiffener size.

• 진공이야기
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• 제1권2호
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• pp.24-29
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• 2014

Display is a key component in electronic devices. OLED is growing very fast recently due to the explosion of the smart phone market although still LCD is the dominating display technology in the display market at the moment. Also needs for the large area and high resolution TVs and flexible displays are increasing these days. Especially flexible display is expected to be one of the key technologies in mobile devices requiring small device size and large display size. Contrary to the conventional displays, flexible display requires organic materials for the substrate, the active driving element and also for the display element. Plastic film as a substrate, organic semiconductor as an active component of the transistor and organic light emitting materials or electronic paper as a display element are studied actively. In this article, mainly backplane technologies such as substrates and the transistor materials for flexible display will be introduced.