• Geomechanics and Engineering
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• 제5권4호
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• pp.313-329
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• 2013

Vetiver grass (Vetiveria zizanioides) is being effectively used in many countries to protect embankment and slopes for their characteristics of having long and strong roots. In this paper, in-situ shear tests of the ground with the vetiver roots have been conducted to investigate the stabilization properties corresponding to the embankment slopes. Numerical analyses have also been performed with the finite element method using elastoplastic subloading $t_{ij}$ model, which can simulate typical soil behavior. It is revealed from field tests that the shear strength of vetiver rooted soil matrix is higher than that of the unreinforced soil. The reinforced soil with vetiver root also shows ductile behavior. The numerical analyses capture well the results of the in-situ shear tests. Effectiveness of vetiver root in geotechnical structures-strip foundation and embankment slope has been evaluated by finite element analyses. It is found that the reinforcement with vetiver root enhances the bearing capacities of the grounds and stabilizes the embankment slopes.

• 한국자원식물학회지
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• 제34권4호
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• pp.278-286
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• 2021

유전자 가위 기술 등 생명공학 기술을 콩에 적용하여 새로운 품종을 개발하기 위해서는 효율적인 조직배양 기술이 필수적이다. 식물의 유전형은 조직배양 효율에 의존하는 형질전환 기술의 성공 여부를 결정짓는 중요한 요소로 알려져 있다. 본 연구에서는 우리나라 콩 핵심 집단 내 21개 자원들을 선발하여, 외래 품종 2종과 함께 조직배양 효율을 조사하였다. 그 결과, 근연 관계가 높은 Kwangan, Anpyeong, Seonam은 발아율과 재분화 효율이 높았으며, Daepung, Daewon 품종은 발아율과 재분화율 모두 낮게 관찰되었다. 또한 3종의 외래 품종에서는 표준 유전체 해독에 사용된 Williams82와 Jack, Maverick 모두 높은 조직배양 효율을 보였다. 조직배양 효율이 높은 자원들을 대상으로 Agrobacterium법에 의한 형질전환을 수행하여 PCR 및 bar-strip 분석한 결과 Kwangan, Pungwon, Seonam, 그리고 Maverick 품종에서 제초제 저항성 유전자의 삽입을 확인할 수 있었다. 이들 결과를 바탕으로 농업적 가치가 높은 다양한 콩 품종들의 형질전환을 통한 새로운 품종 개발이 가능할 것이다.

• 대한기계학회논문집A
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• 제38권10호
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• pp.1171-1177
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• 2014

전자파차폐용 문세트는 기계적 강도 및 내구성과 전자파 차폐라는 전기적 성능 요구를 동시에 충족시켜야 하므로 이에 알맞은 신뢰성입증시험법의 정립이 요구된다. 특히 전자파 차폐 성능에 직접적인 영향을 미치는 핑거스트립이라고 불리는 베링륨동 재질의 박형 스프링 하위 부품은 문짝과 직접적인 반복 건조마찰이 발생하므로 내구성에 만전을 기해야 하는 부위인데, 산업계에서는 주기적인 보전이 필요한 이 핑거스트립의 교체주기에 대한 보증도 또한 필요한 실정이다. 이러한 요구들에 대응하여 본 연구에서는 전자파차폐용문세트의 시험항목들을 정하고 전체 시스템 수명뿐만 아니라 교체품의 교체주기에 대한 보증을 단순한 방법으로 동시수행하는 입증시험을 설계하였다. 결론적으로 하위 교체부품을 가지는 직렬 시스템의 신뢰성입증시험에서는 교체품의 교체주기에 대한 보증도 항상 함께 포함시킬 것을 제안한다.

• Earthquakes and Structures
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• 제2권3호
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• pp.257-277
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• 2011

An evaluation is presented of the response of a 3-storey R/C structure during the destructive Lefkada earthquake of 14/08/2003. Key aspects of the event include: (1) the unusually strong levels of ground motion (PGA = 0.48 g, $SA_{max}$ = 2.2 g) recorded approximately 10 km from fault, in downtown Lefkada; (2) the surprisingly low structural damage in the area; (3) the very soft soil conditions ($V_{s,max}$ = 150 m/s). Structural, geotechnical and seismological aspects of the earthquake are discussed. The study focuses on a 3-storey building, an elongated structure of rectangular plan supported on strip footings, that suffered severe column damage in the longitudinal direction, yet minor damage in the transverse one. Detailed spectral and time-history analyses highlight the interplay of soil, foundation and superstructure in modifying seismic demand in the two orthogonal directions of the building. It is shown that soil-structure interaction may affect inelastic seismic response and alter the dynamic behavior even for relatively flexible systems such as the structure at hand.

• Geomechanics and Engineering
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• 제13권2호
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• pp.269-284
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• 2017

A new technique is proposed to obtain more effective screening efficiency against the ground vibration using intermittent geofoam (IF) in-filled trench. The numerical analysis is performed by employing two-dimensional finite element method under dynamic condition. Vertically oscillated strip foundation is considered as the vibration source. In presence of the ground vibration, the vertical displacements at different locations (pick-up points) along the ground surface are captured to determine the amplitude reduction factor (ARF), which helps to assess the efficiency of the vibration screening technique. The efficiency of IF over continuous geofoam (CF) in-filled vibration barriers is assessed by varying the geofoam density, the location of trench and the frequency of excitation. The results from this study indicate that a significant reduction in ARF can be achieved by using intermittent geofoam as compared to continuous geofoam. Further, it is noticed that the efficiency of IF increases with an increase in the frequency of the vibrating source. These encouraging results put forward the potential of utilising intermittent geofoam as a vibration screening material.

• 한국주거학회논문집
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• 제26권6호
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• pp.139-146
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• 2015

In this study, the plane type of main building relics of unified Silla period house site which excavated in Gyeongju city after 1990s was classified and the architectural characteristic of them was investigated. The chronology of building relics in Silla capital city site was mostly known as 8-9th century, and by standard of column arrangement, the plane types of them could be classified as grid type, front veranda-grid type, outer column type. The outstanding characteristic of plane is wide span and open front veranda. In most relics the span were over 4 meters, and inner foundations for small post and strip foundation were found between columns. The front veranda added type buildings were composited of enclosed main room and open front veranda, and column arrangement of them dose not fall into line in most case. Thus it thought that the structures of enclosed main room and open front veranda were independent. The interior space of enclosed main room were divided two rooms by partition wall in some case. In this case, one room is enclosed by wall, and the other room has open front side. This plane is considered for the pleasant life in cold winter and hot summer.

• Geomechanics and Engineering
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• 제14권1호
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• pp.51-60
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• 2018

The foundations are classified into shallow and deep, which have important differences: in terms of geometry, the behavior of the soil, its structural functionality, and its constructive systems. The shallow foundations may be of various types according to their function; isolated footings, combined footings, strip footings, and slabs foundation. The isolated footings are of the type rectangular, square and circular. The combined footing may be rectangular, trapezoidal or T-shaped in plan. This paper presents a new model for T-shaped combined footings to obtain the most economical contact surface on the soil (optimal dimensioning) to support an axial load and moment in two directions to each column. The new model considers the soil real pressure, i.e., the pressure varies linearly. The classical model uses the technique of test and error, i.e., a dimension is proposed, and subsequently, the equation of the biaxial bending is used to obtain the stresses acting on each vertex of the T-shaped combined footing, which must meet the conditions following: The minimum stress should be equal or greater than zero, and maximum stress must be equal or less than the allowable capacity that can withstand the soil. To illustrate the validity of the new model, numerical examples are presented to obtain the minimum area of the contact surface on the soil for T-shaped combined footings subjected to an axial load and moments in two directions applied to each column.

• 한국지반공학회지:지반
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• 제10권3호
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• pp.97-110
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• 1994

Lining이 타설되기 이전의 unlink 안정 문제를 야기시킬 수 있으며 이 구조물의 역학적 상호작용에 관한 unlined 터널의 3차원적 거동에 관한 원 탄소성 유한요소해석 프로그램을 기초의 극한 지지력, 지반과 터널주컴퓨터 해석 결과를 고찰하여 정방형 unlined 터널은 기초의 극한 지지력을 기초의 형상이나 근입깊이 등에 의해 치하는 터널은 터널의 축방향으로 발생하는 응력의 크기는 정방형 기초 위치와 음력의 종류에 따라 다른 것으로 상호작용의 정도에 따라 다름을 볼 수 있었다.

• Geomechanics and Engineering
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• 제31권2호
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• pp.223-235
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• 2022

Bearing capacity of shallow foundations is often determined for either dry or saturated soils. In some occasions, foundations may be subjected to external loading which is inclined and/or eccentric. In this study, the ultimate bearing capacity of shallow foundations resting on partially saturated coarse-grained cohesionless and fine-grained cohesive soils subjected to a wide range of combined vertical (V) - horizontal (H) - moment (M) loadings is rigorously evaluated using the well-established limit equilibrium method. The unified effective stress approach as well as the suction stress concept is effectively adopted so as to simulate the behaviour of the underlying unsaturated soil medium. In order to obtain the bearing capacity, four equilibrium equations are solved by adopting Coulomb failure mechanism and Bishop effective stress concept and also considering a linear variation of the induced matric suction beneath the foundation. The general failure loci of the shallow foundations resting on unsaturated soils at different hydraulic conditions are presented in V - H - M spaces. The results indicate that the matric suction has a marked influence on the bearing capacity of shallow foundations. In addition, the effect of induced suction on the ultimate bearing capacity of obliquely-loaded foundations is more pronounced than that of the eccentrically-loaded footings.

• 한국의류학회지
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• 제26권6호
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• pp.821-832
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• 2002

The purpose of this study was to develop grading method of the basic brassiere patterns therewith, provide for 12 size's brassiere patterns and prove fitness of their's and shape. The collected data were statistically processed using the SAS 6.12 for Means, Standard Deviation, etc. The results of this study can be summarized as follows; 1. The basic sizes adopted at the first design stage (see fig.1-2) were 75AA, 75A and 75B each of which was designed as upper foundation basic pattern in reference to the cup size. At the second stage, each of the upper body foundation basic pattern was used to design lower cup, upper up, front panel and wing in their order(see fig.3-6). At the third stage, the other sizes were graded in reference to the three brassiere patterns (75AA, 75A and 75B) to produce 12 brassiere sizes(see Tab. 7-8). In order to develop the basic patterns of adult women's brassieres, 33 women were selected per 11 size combination(3 women per size combination), and then, their brassiere fitting was teated. As a result, the fronts of the basic patterns were found to have such problems as undone front center, poor levelling of upper cup's bottom line or lower cup's top line, poor shape of upper cup's outside top line and shoulder strip position. On the other hand, on the rear side of the basic patterns, the central part of the wing was slightly lifted, while the wing width and straps'interval did not befit the ful1-cup brassiere. The result of this first brassiere fitting test showed that the functionality and aesthetics of the basic pattern brassieres were more or less satisfactory, and thus, the problems were addressed for the second teat. In the second test, the aesthetics, breast-shaping effect and functionality of the basic pattern brassieres were much improved. 2. We were to present the final brassiere sizing system to extend the interior length of breast and the exterior length of breast on the basis of fitting test. Thereby, 75B$.$80A$.$80B$.$85A$.$85B's the interior lengths of breast were enlarged to 0.7cm, the rest size was enlarged to 0.5cm and the exterior length of breast was enlarged to 0.5cm regardless of sizes. 3. The upper foundation basic patterns of 75AA and 75B were presented and and the basic brassiere pattern and grading pattern were presented through to.