• International Journal of Quality Innovation
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• 제9권1호
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• pp.68-93
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• 2008

The steel bars account for a high percentage of material costs for the current construction projects. At the present time, most of the construction projects for the factories of thin-film transistor liquid crystal display (TFT-LCD) complete the transactions of steel bars when the suppliers ship the steel bars to the temporary storage/processing sites. This paper applies the buy-in concept in the Theory of Constraint (TOC) on the supply chain of steel bars. In this study, suppliers are required to establish warehouses at the construction sites and complete the transactions when the formed and processed steel bars are shipped into the factory sites. The aim is to find a win-win solution to meet with the expectations from constructors as they hope that there is no need to build up inventories but supply is ready at any time. Also, this paper compares and analyzes the traditional supply/inventory model of steel bars and the Demand-Pull (D-P) model under the TOC framework. It is proved that Vendor Management Inventory (VMI) in the D-P model is able to more effectively manage steel bars as a material.

• 한국화재소방학회논문지
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• 제22권5호
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• pp.29-34
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• 2008

본 연구에서는 대피자의 최적 배연조건 확립을 위하여 CFD모델을 이용한 수치해석을 통해 지하철 승강장 내에서의 화재 시 다양한 배연조건에서의 화재 위험성을 검토하였다. 결과로 스크린도어를 설치한 경우가 설치하지 않은 경우보다 온도의 상승폭이 최대 $65.37%{\sim}74.97%$ 낮게 나타났다. 또한 급기나 압인배기시 승강장에 난류가 발생함에 따라 온도 및 연기층이 교란되어 하락됨에 따라 탈출시 위험을 유발할 수 있는 것으로 판단되었다. 따라서 배연용량 및 승강장 공간 설정시 배연조건에 따른 화재 특성을 고려한 설계가 필요하다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.192-194
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• 2005

Joint strength of spot friction welded 5J32 Al alloy were investigated according to the tool shape and the tool penetration depth. General spot friction stir welding tool consists of a shoulder having bigger diameter and a threaded pin projected from the shoulder, which resulted in the generation of large up-lifting of upper plate around the weld nugget because of the deeper penetration and the severe stirring effect of threaded pin. Two kinds of welding tools without the threaded pin were used to avoid the distortion and improve the joint strength. One was a simple cylindrical shape and the other was cylindrical shape with small projection. Therefore, the process was named as spot friction welding comparing to spot friction stir welding because spot friction welding don't use a stirring effect. Using the cylindrical shape tool with small projection, the up-lifting of upper plate were avoided and joint strength were superior to that of the joint using simple cylindrical shape tool. At the 0.5mm of too penetration depth using cylindrical tool with small projection, nugget pull fracture mode can be observed and shear fracture mode were dominant at the rest conditions.

• Advances in materials Research
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• 제4권2호
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• pp.97-111
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• 2015

Polypropylene short fiber (PP)-clay particulate-epoxy ternary composites were prepared by reinforcing PP short fiber and clay particles in the range of 0.1 phr to 0.7 phr into epoxy resin. Prepared hybrid composites were characterized for their mechanical, thermal and flame retardant properties. The obtained results indicated an increase in impact resistance, tensile strength, flexural strength and Young's modulus to an extent (up to 0.5 phr clay and 0.5 phr PP short fiber) and then decreases as the reinforcing phases are further increased. The thermal stability of these materials are found to increase up to 0.2 phr clay and 0.2 phr PP addition, beyond which it is decreased. Addition of clay is found to have the negative effect on epoxy-PP short fiber composites, which is evident from the comparison of mechanical and thermal properties of epoxy-0.5 phr PP short fiber composite and epoxy-0.5 phr PP short fiber-0.5 phr clay composite hybrid. UL-94 tests conducted on the composite hybrids have showed a reduction in the burning rate. Morphological observations indicated a greater fiber pull with the addition of clay. The performed tests in the present study indicated that materials under investigation have promising applications in construction, agriculture and decorative purposes.

• 지질공학
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• 제17권4호
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• pp.525-534
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• 2007

선단 확장식 소일네일링 공법의 특징은 천공홀보다 큰 직경의 특수 비트로 공저 30cm 정도를 확장하고, 천공직경보다 큰 쐐기형 몸체를 접어서 공저에 삽입한 다음, 쐐기형 몸체를 펼쳐 공벽에 밀착되도록 한 후 그 주위를 그라우팅하고 지반에 정착시키는 공법이다. 본 연구에서는 개발된 공법의 효과를 입증하기 위해 길이 1,300mm, 폭 1,000mm, 높이 1,100mm의 토조에 모형지반을 조성한 후 인발 및 하중재하실험을 실시하였고, 동일한 실험조건으로 일반 소일네일링과 비교하였다. 선단 확장식 네일링이 일반 네일링 공법에 비하여 인발력은 23% 정도 증가하였으며, 벽체의 수평변위는 $1.2{\sim}9.1%$ 정도 감소하였다. 또한 네일에 작용하는 축력은 선단 확장식은 7tonf, 일반 네일은 5tonf이후에서 크게 증가하였으며, 축인장 변형율 분석결과 예상 파괴선이 변체로부터 먼거리에 선단 확장식이 위치하고 있음을 확인하였다. 이들 결과로부터 선단 확장식 네일링이 일반적인 소일네일링 공법에 비하여 보강효과 면에서 우수한 공법임을 입증하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제14권5호
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• pp.128-135
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• 2010

폴리머시멘트 모르타르는 고강도 및 고내구성 등의 우수한 재료적 성질을 가지고 있어 철근콘크리트 구조물의 보수재료로 광범위하게 사용되어져 왔다. 폴리머시멘트 모르타르와 콘크리트 사이의 부착거동은 폴리머시멘트 모르타르에 의해 보수 보강된 철근콘크리트 부재의 보강성능을 좌우하는 매우 중요한 요소이다. 따라서 폴리머시멘트 모르타르와 콘크리트 접합면에서 발생되는 부착파괴의 메커니즘은 명확히 구명될 필요가 있다. 본 연구에서는 직접인발시험을 통해 국내에서 판매되는 폴리머시멘트모르타르와 콘크리트의 부착강도를 평가하였다. 표준, 침수, 온냉반복 및 동결융해 등의 전처리 조건에 노출된 폴리머시멘트모르타르의 부착강도를 실내시험을 통해 평가하였으며, 2차에 걸친 시험시공을 통한 현장부착강도도 함께 평가하였다. 시험결과 현장부착강도는 표준조건에서 실시한 실내 부착강도 시험결과보다 낮은 수준이었으며, 열충격조건에서의 실내시험결과와 유사한 것으로 나타났다. 본 연구결과를 기초로 KS에 규정된 폴리머시멘트모르타르의 시험방법 및 품질기준의 타당성을 검토하였다.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.327-331
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• 2006

This paper presents the analysis method for the torque characteristic of the 1-phase induction motor considering space harmonics in the air gap. The equivalent circuit method is used, where the circuit constants are obtained by classic theory. In addition, the space harmonic components in air gap magneto motive force are analyzed and added to the equivalent circuit to obtain accurate torque characteristics in low speed regions. Each torque component due to the harmonics is calculated and the total torque characteristic is obtained and compared with the measurement result.

• Earthquakes and Structures
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• 제4권1호
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• pp.41-62
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• 2013

A comprehensive experimental program of cyclic tests on 1:3-scale models of bridge piers is going to be carried out at the Laboratory of Structures and Materials of the University of Basilicata. The testing models include eight RC single shaft piers with hollow circular cross section. Four piers have been realised using corroded steel rebars. In this paper, the results of preliminary numerical simulation analyses of the cyclic behaviour of the piers, carried out with Opensees using fiber-based models, are presented. Pull-out and lap-splice effects of steel rebars have been taken into account in the numerical analyses. First, the experimental specimens and the test set up are presented. Next, the results of the numerical analyses are discussed. In the numerical analyses, different configurations and levels of corrosion have been considered. The effective stiffness and equivalent damping of the piers is reported as a function of pier ductility and pier drift.

• Journal of Photoscience
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• 제12권2호
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• pp.95-100
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• 2005

We have synthesized an azobenzene-containing polymer (PEA) and a stilbene-containing polymer (PAS) with second-order nonlinear properties. The second harmonic coefficient ($d_{33}$) of the poled polymer films was 84 and 36 pm/V for of PEA and PAS, respectively. The poled state of these polymers was stable at least up to 30 h at room temperature. $T_g$ of these polymers appeared in the range from 120 to $160^{\circ}C$ and onset of initial weight losses in the range from 260 to $270^{\circ}C$. Silicon moieties in the main chain enhanced the solubility of PEA and PAS in common organic solvents such as chloroform, N-methylpyrrolidinone (NMP), N, N-dimethylformamide (DMF), etc.

• 수산해양기술연구
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• 제41권1호
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• pp.78-84
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• 2005

The main goal of this work is to study the effects of temperature and volume fraction of fiber on the Charpy impact test with GF/PP composites. The critical fracture energy and failure mechanisms of GF/PP composites are investigated in the temperature range of 60^{\circ}C$ to -50^{\circ}C$ by impact test. The critical fracture energy increased as the fiber volume fraction ratio increased. The critical fracture energy shows a maximum at ambient temperature and it tends to decreases as temperature goes up or goes down. Major failure mechanisms can be classified such as fiber matrix debonding, fiber pull-out and/or delamination and matrix deformation.