• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.10-21
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• 2015

Many studies have been carried out on carbon fiber-reinforced plastic sheet(hereafter CFRP sheet)-confined concrete specimens for improve structural performance of concrete structures. To complement the existing studies, a parametric study is conducted to examine the effect of various design parameters such as layers of CFRP sheet, size and aspect ratio of specimens, and overlap length. The behavior of CFRP-confined concrete is compared using stress-strain curves of each specimen. And the strengthening effect of CFRP sheet is examined by maximum compressive strength. As the layers of CFRP sheet increases, structural performance of CFRP-confined concrete is significant increased. If the overlap length is more than 5% of circumstance, strengthening effect is not affected. In addition, a test database assembled from test results and existing studies is presented. Using these test database, accuracy and reliability of the existing strength models for CFRP-confined concrete are verified.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.499-503
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• 2019

Characteristics of solar cells employing a lattice matched GaInP/GaAs quantum well (QW) structure in a single N-AlGaInP/p-InGaP heterojunction (HJ) were investigated and compared to those of solar cells without QW structure. The epitaxial layers were grown on a p-GaAs substrate with $6^{\circ}$ off the (100) plane toward the <111>A. The heterojunction of solar cell consisted of a 400 nm N-AlGaInP, a 590 nm p-GaInP and 14 periods of a 10 nm GaInP/5 nm GaAs for QW structure and a 800 nm p-GaInP for the HJ structure (control cell). The solar cells were characterized after the anti-reflection coating. The short-circuit current density for $1{\times}1mm^2$ area was $9.61mA/cm^2$ for the solar cell with QW structure while $7.06mA/cm^2$ for HJ control cells. Secondary ion mass spectrometry and external quantum efficiency results suggested that the significant enhancement of $J_{sc}$ and EQE was caused by the suppression of recombination by QW structure.

• Archives of design research
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• v.13
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• pp.123-137
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• 1996

Weaving, is an ideal subject for study to designer who is concerned with interrelationship between art and technology. Double cloth is a two layered fabric that can be woven on the loom with more than 4 harnesses, is often used to produce special woven fabric such as double width fabric or reverse pattern fabric, etc, in textile industry. Because of the attractive characteristic of two layered structure, double cloth technique can be applied as expressive media in fiber art requiring aesthetics and creativty. in the work, the concept, types, and characteristics of double weave have been studied through literature survey and sample production and the potential characteristics of this technique is, especially, emphasized by analysing the representative works of artists specilized in a double weave. Double weave technique can provide various images or forms throught the variation of structures and expressive styles and therefore suggests another characteristic expression creative means for weaver to develope.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.477-480
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• 2011

The stress analyses of the 'U'-shaped multi-ply reinforced gimbal bellows under high pressure and rotational displacement loadings are performed at the room and cryogenic temperatures. The bellows are used for the Lox pipe line which connects the combustion chamber with the turbopump of a liquid rocket engine. The distributions of the stress, the strains and the contact pressures are obtained from the finite element analysis considering the geometric non-linearities of the contacts between the plies and the material one of the isotropic plasticity. Those are compared with the stress results from EJMA (Expansion Joint Manufacturing Association) standard. Also, the effects of the operating temperature and the reinforcing ring on the stresses are investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.159-159
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• 2011

최근 여러 화학 반응에 대해서 일층(1L) 그래핀(graphene)이 복층(multi-layered) 그래핀보다 10 배 이상의 높은 반응성을 보인다는 사실이 알려졌다. 본 실험에서는 기판의 편평도와 기판-그래핀 간의 상호작용이 그래핀의 반응성에 미치는 영향을 이해하기 위해서, AFM(atomic force microscopy)과 라만 분광법을 이용하여 그래핀의 기체상 고온 산화반응을 연구하였다. 기계적 박리법을 통해 산화실리콘(SiO2/Si)과 마이카(mica) 기판 위에 고착된 그래핀 시료를 대조군으로 비교하였다. AFM 형상 분석으로부터 편평도가 낮은 산화실리콘 위에서는 그래핀의 두께가 작을수록 산화 속도가 크다는 사실을 확인하였다. 그러나 편평도가 높은 마이카 기판 위에서는 단일층 그래핀의 산화 속도가 산화실리콘 기판 위에서보다 현저하게 감소하고 두 겹 이상의 두께에서는 반응성의 차이가 없음을 발견하였다. 특히 마이카 위의 단일층 그래핀에서는 복층 그래핀과는 달리 산화에 의한 식각이 거의 일어나지 않아 화학적 안정성이 증대되었음을 알 수 있었다. 본 연구는 기판의 표면구조와 상호 작용을 통해 그래핀의 화학적 특성을 조절 할 수 있다는 가능성을 보여 준다.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.1
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• pp.53-61
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• 2013

The characteristics of methane production from pig manure slurry was investigated using anaerobic digestor combined with compost filtration bed. In this study, raw pig manure slurry was digested in mesophilic rectangular digester (effective volume $250m^3$) for 25 days and anaerobic digestion wastewater was filtered through compost filtration bed, which is composed of double layer, sawdust and chaff. The characteristics of anaerobic digestion wastewater were BOD 1,800 mg/L, COD 3,500 mg/L, SS 11,800 mg/L, T-N 1,200 mg/L and T-P 350 mg/L. After the filtration process, the contents of BOD, COD, SS, T-N and T-P of the anaerobic digestion wastewater were reduced by 97%, 62%, 89%, 39% and 57%, respectively. The concentrations of N, $P_2O_5$, and $K_2O$ of the leachate were 1,024, 111 and 407 mg/L, respectively. However, there was no odor emitted from the leachate.

• Journal of the Korea Furniture Society
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• v.21 no.6
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• pp.469-478
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• 2010

Fire resistance of new hybrid timber framed wall systems was evaluated in this study. These wall systems are composed of two major structural parts. One part is a heavy timber frame part designed to take charge of whole vertical load using heavy timber post and beam, and the other is an infill wall structure, designed to take charge of whole horizontal load and to provide an established level of fire resistance. A basic concept of this hybrid wall is adopted from a typical furniture structure with frame. A timber post and beam frame is constructed with Japanese Larch solid timber post(180mm by 180mm) and beam(180mm by 240mm). As infill wall systems, two types of walls are applied. One is a typical light timber framed wall with solid blocking and another is a structural insulated panel wall, in which polystyrene insulation is filled between two structural panels to make single structure. For all tested walls, two layers of 12.5mm thick type-X gypsum boards are used on fire exposed side. Prior to tests for hybrid walls, only infill walls are tested without heavy timber frame. All fire resistance tests are carried out in accordance with KS F 2257, and temperatures on several points within wall structure and unexposed wall surface are measured during fire tests. It is considered that the reinforcement of heavy timber frame is significantly efficient for improving the fire resistance of timber framed walls.

• Korean Journal of Heritage: History & Science
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• v.45 no.3
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• pp.4-27
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• 2012

The five capital(五京) was installed in the $Li{\acute{a}}o$(遼) Dynasty. $Sh{\acute{a}}ngj{\bar{i}}ng$(上京) was the main capital city of the $Li{\acute{a}}o$(遼) Dynasty. $Zh{\bar{o}}ngj{\bar{i}}ng$(中京) was the second capital(陪都); and the other three was the capital city with symbolic meaning. The layout of $Sh{\grave{a}}ngj{\bar{i}}ng$ was the '日-shaped plan; this was newly advent structure of ancient Chinese capital city system. $Zh{\bar{o}}ngj{\bar{i}}ng$(中京) was surrounded by multiple ramparts influenced by the $Bi{\grave{a}}nli{\acute{a}}ng$ Fortress (?梁城). Three capitals, Nanjing(南京), $X{\bar{i}}j{\bar{i}}ng$(西京) and $D{\bar{o}}ngj{\bar{i}}ng$(東京), were reconstructed on the foundation of the previously constructed town in $T{\acute{a}}ng$(唐) or Bohai(渤海) Fortress (舊城). The structure and Planning of $Sh{\grave{a}}ngj{\bar{i}}ng$(上京) in the $Li{\acute{a}}o$(遼) Dynasty, had significantly influenced in the capital city planning of the $J\bar{i}n$(金), $Yu{\acute{a}}n$(元) and Qing(淸) Dynasties of China

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.260-267
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• 2019

Two aerophytic cyanobacteria from the rockwall of Haje port located in Geum river, Korea, were isolated in unialgal cultures and submitted to polyphasic evaluation. The filaments of the populations presented solitary or several to many parallel arranged. The straight trichomes were not attenuated with rounded apical cell. Phylogenetic analyses based on 16S rDNA sequences indicated that these populations formed the same clade with Wilmottia murrayi and had 99% or greater DNA similarity. Through the ultrastructure of the TEM, these populations showed parietal thylakoid arrangement, which coincides with family Coleofasciculaceae. From the above results, we reported the newly recorded genus Wilmottia, and species W. murrayi in Korea.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.3
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• pp.237-244
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• 2016

This paper presents a nonlinear Moving Least Squares(MLS) difference method for material nonlinearity problem. The MLS difference method, which employs strong formulation involving the fast derivative approximation, discretizes governing partial differential equation based on a node model. However, the conventional MLS difference method cannot explicitly handle constitutive equation since it solves solid mechanics problems by using the Navier's equation that unifies unknowns into one variable, displacement. In this study, a double derivative approximation is devised to treat the constitutive equation of inelastic material in the framework of strong formulation; in fact, it manipulates the first order derivative approximation two times. The equilibrium equation described by the divergence of stress tensor is directly discretized and is linearized by the Newton method; as a result, an iterative procedure is developed to find convergent solution. Stresses and internal variables are calculated and updated by the return mapping algorithm. Effectiveness and stability of the iterative procedure is improved by using algorithmic tangent modulus. The consistency of the double derivative approximation was shown by the reproducing property test. Also, accuracy and stability of the procedure were verified by analyzing inelastic beam under incremental tensile loading.