• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.28.1-28.1
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• 2009

고해상도 카메라 혹은 영상레이더 안테나를 장착하여 지구를 관측하는 인공위성의 구조체는 발사하중 및 우주환경의 궤도 상에서 탑재된 장비를 보호하게끔 설계되고 제작된다. 구조체는 발사체와의 공진을 피할 수 있는 강성을 가져야 하며, 주 구조물의 강도는 발사체로부터의 하중을 견딜 수 있도록 설계된다. 또한, 극한 우주환경 하에서 구조체의 변형이 최소화 되도록 설계된다. 상기 설계 내용이 완벽하게 구조체에 반영되기 위해서는 우주용자재 및 공정의 적절한 선정이 이루어 져야 한다. 이 논문은 인공위성 구조체에 사용된 Metal, Non-metal 및 조립용 Hardware 자재 (규격 포함)와 측면패널/플랫폼 및 태양전지판 Substrate 등 주요 구조물의 제작공정에 대하여 기술한다. 그리고, 국산화가 이루어진 조립용 Hardware의 Dry Film Lubricant 공정에 대해서도 기술한다.

• 식품문화 한맛한얼
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• v.2 no.1
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• pp.42-45
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• 2009

술! 우리 주변에서 쉽게 접할 수 있는 술. 이 술이라는 말에는 어떤 뜻이 내포되어 있을까? 현재 우리가 사용하고 있는 술이라는 말은 본래 '수불'이라고 불렸다고 한다. 물과 불! 우리 선조들은 술을 빚는 과정에서 효모가 생성하는 이산화탄소에 의해 술덧(술밑) 표면에 거품이 생기는 현상을 보고는 물에 불이 붙어서 부글부글 끓어오르는 것으로 생각하고 '수불'이라고 표현한 것 같다. 어찌 보면 비약적인 해석일 수 있으나 우리 선조들이 말 속에 과학 현상을 잘 표현한 것이라 할 수도 있다. 술의 한자어인 주(酒)는 물 수(水)자와 본래 술을 뜻하는 유(酉)자가 합쳐진 것으로 '물이 익은 것' 이라는 뜻이 내포되어 술이 만들어지는 현상을 표현한 것이라면, 술이라는 말은 효모에 의해 술이 만들어지는 과정의 일부를 과학적으로 표현한 말이라고 할 수 있다. 또 이 말 속에는 끓는다는 뜻의 라틴어 'ferverve'에서 유래된 'fermentation', 즉 발효의 의미도 포함되어 있다. 이러한 뜻을 내포하고 있는 술에 대해 우리나라 주세법에서는 알코올 도수 1% 이상의 음용 가능한 것이라고 정의하고 있으나, 각각의 개인이 내리는 술에 대한 정의는 천차만별일 것이다.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.301-315
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• 2001

본 연구에서는 최근 5년간 국내 각 지역에서 채취한 802개의 절리면 시료에 대하여 전단시험을 실시하여 얻은 결과를 이용하여, 절리면의 여러 공학적 성질들을 조사, 연구하였다. 절리면 전단시험에서 얻어진 최대마찰각 및 잔류마찰각을 지체구조별, 암종별로 분류하고 통계적으로 구하였으며, Barton의 전단강도식의 입력변수인 JRC, JCS를 측정하고 Barton식의 적용성에 대해서도 검토하였다. 그 결과 설계의 기초자료로 활용할 수 있는 지역별, 주요 암종별 최대마찰각, 잔류마찰각을 제시하였다. 또한, JRC, JCS, 수직응력에 따른 마찰각과 전단강성 및 팽창각의 변화를 분석하였다. 마지막으로, Barton의 식에서 구한 이론적 전단강도와 이 실험에서 얻어진 전단강도를 비교한 결과, Barton의 경험식은 높은 상관도로 암석 절리면 전단강도를 예측할 수 있음을 확인하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.374-376
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• 2012

우리나라 항만 입출항 통항 선박의 대형화, 고속화에 따른 해양안전사고가 증가하고 있어 항만 연안 해역에서의 해상교통 안전 확보가 절실히 요구되고 있는 실정으로, 최근 국제항로표지협회(IALA)에서 항로표지 설계와 배치계획에 대한 의사결정을 지원할 수 있는 항로표지 전문 기능 시뮬레이터의 개발과 주요 항로의 항로표지 설계 및 계획 등을 검증할 수 있는 시스템 필요성을 제기하였다. 우리나라 주요 항로의 항로표지 설계와 적정 배치 여부 등을 검증하고 보완할 수 있는 시뮬레이션 시스템이 필요하며 3차원 가상현실 기법을 이용하여 항로표지의 신설 및 이설에 따른 여러 가지 효과를 직관적으로 파악하고 대상 해역의 특성이 고려된 다양한 해상교통환경 변화에 따른 항로표지의 신설 및 이설 효과를 선박 운항자 관점에서 검증하거나, 새로운 항만 항로 건설시 최적 항로표지 배치에 대한 의사결정을 지원하기 위한 항로표지용 시뮬레이터 시스템 개발이 진행되고 있다. 이러한 항로표지 시뮬레이터 개발에 필요한 항로표지 관련 속성에 대하여 기술하였다.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.159-168
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• 2005

In the previous studies, settlement behaviors of granular compaction piles have generally been analyzed with an evaluation of the settlement reduction factor based on tile load-sharing ratio and the replacement ratio. In this approach, however, since the reinforced ground with granular compaction piles is simplified as the composite ground, only the difference of a relative vertical strength between piles and soils is taken into account without reflecting lateral behaviors of granular compaction piles. In the companion research paper, the method of estimating the settlement of granular compaction piles was proposed by synthetically considering a vertical strength of the ground, lateral behaviors of granular compaction piles, the strength of pile materials, a pile diameter, and an installation distance of the pile. In the presented study, to validate a propriety of the previously proposed method, large scale field load tests and three dimensional numerical analyses are performed. The results are analyzed in detail and compared with the predicted settlements by the proposed method. Finally, a simple method to estimate the settlement of granular compaction piles is suggested for an easy application of the practical design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.2
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• pp.10-18
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• 2012

Most of studies on existing strengthening methods were mainly on increase of stiffness and strength of shear strengthening to rectangular beam. As concrete of beam and slab is poured simultaneously on the characteristics of construction in reinforced concrete beam-slab structure, adjacent slab uniformed after hardening has T-shaped beam cross section which makes the flange of beam, enhances the stiffness of the beam and widens the area supporting compressive strength, but available data of flexural behavior of T-shaped beam are lacking. In this research the T-shaped beams would be made, then the reinforced effects and structural properties can be estimated according to the kinds of reinforced materials and reinforced position. The conclusions are shown as below. To sum up the experimental results, The specimen which was reinforce by CB embedded inside of concrete indicated excellent resistive behavior, internal force and stiffness when it was destroyed. The steel plate reinforced specimen of stiffness and internal force were increase but it expressed lower reinforce effects because of lowering anchored force between concrete. Fiber sheet strengthening showed superior effects but the interfacial delamination was found due to the lack of anchored force in destruction. So the measure is needed now.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.70-81
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• 2024

In this study, Tridimensional Hybrid Isolation System(THIS) was proposed as a vibration isolator for traffic loads, combining vertical and horizontal isolation systems. Its efficacy in improving serviceability for vertical vibration was analytically evaluated. Firstly, for the analysis, the major vibration modes of the existing apartment were identified through eigenvalue analysis for the system and pulse response analysis for the bedroom slab using commercial structural analysis software. Subsequently, a 16-story model with horizontal, vertical and rotational degrees of freedom for each slab was numerically organized to represent the achieved modes. The dynamic analysis for the measured acceleration from an adjacent ground to high-speed railway was performed by state-space equations with the stiffness and damping ratio of THIS as variables. The result indicated that as the vertical period ratio increased, the threshold period ratio where the slab response started to be suppressed varied. Specifically, when the period ratio is greater than or equal to 5, the acceleration levels of all slabs decreased to approximately 70% or less compared to the non-isolated condition. On the other hand, it was ascertained that the influence of damping ratios on the response control of THIS is inconsequential in the analysis. Finally, the improvement in vertical vibration performance of THIS was evaluated according to design guidelines for floor vibration of AIJ, SCI and AISC. It was confirmed that, after the application of THIS, the residential performance criteria were met, whereas the non-isolated structure failed to satisfy them.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4A
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• pp.315-327
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• 2009

In this study, the static test of CFT truss girders for different f/L ratios was conducted to determine how the ultimate strength of the CFT truss girder was affected by different f/L ratios. A total of two CFT truss girders were constructed and tested under bending condition. The length of all specimens is 20,000 mm. The CFT truss girder is a tubular truss composed of chord members made of concrete-filled circular tubes. The main parameter analyzed in the experimental study was the f/L ratio. This factor was experimentally investigated to assess their influence on ultimate strength and stiffness. The test results show that CFT truss girder has good elastic-plastic property and ductility. The presence of the f/L ratios in CFT truss girders alters its ultimate strength because of the global stiffness of the CFT truss girders. The ultimate strength of CFT truss girders increases as the f/L ratio increases. If the f/L ratio of the CFT truss girders increases twofold, the ultimate strengths increase by 80%. The CFT truss girders showed that they retained large deformation capacity, even after reaching the ultimate strength. Results of this investigation demonstrated the potential for efficiently using a CFT truss as a bridge girder.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.70-78
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• 2023

The ordinary concentrically braced frame has an advantage of having simple design procedure. For this reason, it has been widely used for the small-sized frame structures subject to moderate or lower magnitude earthquake, even though its seismic performance against the earthquake load is not much effective compared to that of other frame systems. To enhance seismic performance of the ordinary concentrically braced frame where the bracing has a weakness for compressive behavior under lateral earthquake, seismic retrofitting by viscous damper has been commonly introduced. However, the viscous damper, itself, generally does not have stiffness for restoring the structure to the original position. This may cause residual displacement to the structure. In this paper, a self-centering viscous damper system in which upper and lower beams having flexural rigidity play a role as a nonlinear-elastic spring, restoring the spring-damper system subject to external displacement history to its original location, is developed. The numerical analysis for a simplified frame structure shows how including the developed self-centering viscous damper system leads to an enhanced seismic performance of the frame structure through energy dissipation during earthquake excitation.

• International Journal of Highway Engineering
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• v.10 no.1
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• pp.105-115
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• 2008

It is known that the long-term behavior and performance of jointed concrete pavement due to slab curling are affected by the environmental factors such as temperature, moisture, and so on. However, any relationships between the curling and its factors have not been defined clearly yet because of insufficient detailed investigation. The temperature, relative humidity, strain, vertical displacement of a concrete slab, and horizontal movement of its transverse joints were investigated by various sensors and devices instrumented in the slab of a concrete pavement section constructed for this study. The constraint of the curling by joint stiffness was investigated in addition to effect of the temperature and moisture on the early aged concrete slab by analyzing the field data measured for approximately 4days from concrete placement. The curling of the concrete slab showed 24hour cycles mainly because of the temperature effect, and the upward curling gradually increased because of the long-term effect of drying shrinkage of the concrete. The magnitude and variation of the curling were significantly affected by the joint stiffness which is comprised of aggregate interlocking and other factors. The effect of the variation of the seasonal joint stiffness varying with the temperature and long-term drying shrinkage on the slab curling will be investigated as a further study.