• ICROS
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• v.3 no.3
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• pp.36-48
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• 1997

본 원고에서는 극 좌표계를 기준으로 하여 추정기를 구성함으로써 속도 검출기가 없는 유도전동기의 회전자 자속 및 회전 속도를 정확히 추정해 내고, 다시 이 정보를 이용하여 유도전동기를 고성능으로 제어할 수 있는 드라이브 시스템의 구현 과정과 이를 이용한 간단한 실험 결과에 대하여 소개하였다. 본 원고에서 제시한 몇가지의 실험 결과들은 소프트웨어의 알고리즘에 의하여 전동기의 회전축에 부착된 속도 검출기는 충분히 대치될 수 있음을 말해주는 것이므로, 속도 검출기가 가격과 내구성 등에서 실제적으로 산업 현장에 적용하기에 많은 문제점을 안고 있다는 점을 감안할 때 그 유용성을 입증하는 것이다.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.12
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• pp.1368-1373
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• 2003

본 연구에서는 견직물에 강경한 촉감을 부여하여 한복지 뿐만 아니라 현대의 패션경향에도 부합되는 소재를 개발하고자 하였다. 견직물에 강경성을 부여하기 위하여 의마가공용 폴리우레탄 수지를 이용하여 수지농도와 큐어링온도에 따른 수지부착율을 조사하였고, 여기에 수반되는 물리적 특성의 변화를 살펴보았다. 또한 가공된 견직물의 세탁에 대한 내구성도 살펴보아 동시에 실용가능성도 검토하였다. 이상의 연구를 통해 다음과 같은 결과를 얻었다. 1. 의마가공용 폴리우레탄 수지를 견직물에 처리할 경우 수지 농도가 증가할수록 수지 부착량이 증가하였다. 2. 열처리온도를 변화시켜 수지부착량의 변화를 살펴본 결과 열처리 온도가 증가할수록 수지의 부착량이 감소하여 본 실험에 사용된 수지의 적정 열처리 온도가 160-18$0^{\circ}C$인 것을 고려해 볼 때 견직물의 경우 17$0^{\circ}C$의 열처리 온도가 적절한 것으로 나타났다. 3. 수지 처리된 견직물의 역학적 특성치의 변화를 살펴본 결과 RT, EM, MIU값은 감소하는 경향을 가지며, LT, B, 2HB, G, 2HG, 2HG5값은 증가하는 경향을 나타내어 폴리우레탄 수지처리로 의마가공 효과를 갖는 견직물을 얻을 수 있었다. 4. 수지 처리된 견직물의 역학적 특성치는 물세탁 후에도 크게 변화가 없어 세탁에 대한 내구성을 지니고 있는 것으로 나타났다.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.362-370
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• 2006

차량의 충격과 진동을 완화하고 링크의 조정역할을 하는 Rubber Bushing제품의 내구성이 약하게 되면 Control arm에서의 이탈사고나 차량의 떨림, 소음으로 인한 고객 불만이 발생하게 된다. 따라서, 국내외 시장에서의 경쟁력 향상을 위해 Rubber Bushing에 대한 내구성, 정특성, 동특성의 개선을 위한 기술의 개발이 요구되고 있다. 본 연구의 목적은 Rubber Bushing을 개발하는데 있어서 종전의 재료설계, 형상설계 및 공정설계에 대한 분석을 행하고, 실험계획법(DOE)을 활용하여 가장 적은 샘플의 시험으로 최적의 설계요소를 찾아내는 방법을 연구하는데 있다. Bushing의 품질특성이 재료, 형상 및 공정에서 어떠한 조건을 가질 때 특성치가 가장 높은 바람직한 반응을 얻을 수 있는 가를 연구하여 최적반응 조건을 결정하고자 한다.

• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.9-15
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• 2001

The low-durability performance of concrete structure occurs by interactive deterioration factors. In particular, carbonation increased with its time elapse is known as the general manner of deterioration characteristics. Recently, the fundamental researches of the carbonation mechanism, besides method and technique for durability improvement of deteriorated structure are advanced actively. So in this paper, alkali-recovery and maintenance performance when the impregnating alkalization agents are used, are compared and examined quantitively with the basis of past proposed study. As a result, alkali-recovery performance be ensured by impregnating alkalization agent on the carbonated concrete which has low pH by accelerated carbonation test. And alkali maintenance performance was effected by the finishing materials on the alkali recovered concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.173-179
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• 2003

Currently, in the mix design of high strength concrete, cement content depend on the target slump which is fixed with tests. However this cause high content cement use because it is based on the mix design of normal strength concrete. Also, comparatively high content cement might decrease the durability of the concrete. Therefore, in this study, we investigated proper cement content satisfying durability, workability, compressive strength, and reviewed use of admixtures, proper sand-aggregate ratio to the cement content. The results indicate that cement content ranging $370{\sim}550kg/m^3$ did not affect the compressive strength. The field workers should consider durability, workability as well as compressive strength for determining the optimal cement content in the mix design of the high strength concrete.

• Journal of the Society of Disaster Information
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• v.9 no.4
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• pp.493-502
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• 2013

The purpose of this research is to estimate the drying shrinkage and durability of concrete using the fine river sand to utilize it actively as an alternative aggregate for concrete. For this purpose, the fine river sand samples were collected at the mid and down stream of main stream of Nakdong-River, and then the concrete specimens using the fine river sand were made according to strength level. After obtaining relation equation between compressive strength and cement-water ratio from the mix experiment result, the concrete specimens using different fine river sand were made for the specified concrete strength of 35MPa, and then their drying shrinkage and durability such as the resistance to freeze and thaw and carbonation were evaluated. It was observed from the test result that the durability of concrete using fine river sand was similar to that of concrete using reference sand, but the drying shrinkage of concrete using the fine river sand with small fineness was comparatively larger than that of concrete using reference sand.

• Journal of the Korea Convergence Society
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• v.12 no.1
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• pp.199-204
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• 2021

In this study, the configurations of the two engine exhaust manifolds were designed. And the strengths and durabilities were analyzed through the structural analysis and natural frequency analyses of these models. As the result of structural analysis, the strength of model A is much better than that of model B because the maximum stress and deformation of model B are considerably greater than those of model A by more than 9 and 39 times, respectively. It can also be confirmed that model A has the durability better than model B because the maximum frequency of model A is greater than the natural frequency of model B and its maximum deformation is smaller than model B. The result of this study can be used to investigate the durability due to the exhaust manifold shape of medium-sized car without actual test. It also seems to be helpful in the aesthetic convergent design of small car muffler.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.317-328
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• 2016

This research intends to understand the impact of super-absorbent polymer (SAP) as an internal curing agent in Ultra-High Performance Concrete (UHPC). Two different types of SAPs of acrylic acid (SAP_AA) and acrylic acid-co-acrylamide (SAP_AM) were examined with UHPC formulation. Isothermal calorimetry and x-ray diffraction experiments revealed the impact of polymers with the different chemical bonds on cement hydration. To test its feasibility as a shrinkage reducing admixture for UHPC, a series of experiments including flowability, compressive strength, rapid chloride permeability and autogenous shrinkage profile was performed. While both SAPs showed a reduction in autogenous shrinkage, it has been concluded that the SAP size and chemical form significantly affect the performance as an internal curing agent in UHPC by controlling cement hydration and porosity modification. Between the tested SAPs, SAP_AM which absorbs more water in UHPC than SAP_AA, shows better mechanical and durability performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.943-948
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• 2013

In this study, the characteristics of polymer-modified mortar which include UM resin, eco-friendly resin, was studied for improving the durability of concrete. UM and cement mortar were mixed with a certain percentage. Eco-friendly UM resin polymer-modified mortar was evaluated by compressive strength, splitting tensile strength, flexural strength, water absorption and chemical resistance experiments. The characteristics of eco-friendly UM resin polymer-modified mortar were evaluated by experiments. Performance of compressive strength and splitting tensile strength were decreasing. On the other hand, performance of flexural strength, water absorption and chemical resistance were increasing. Eco-friendly UM resin polymer-modified mortar reinforced concrete durability performance is excellent.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.319-319
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• 2015

본 연구에서는 강재의 부식 방지를 목적으로 기존의 도장 방식법에 비해 내식성 및 내구성을 향상시키기 위해 아크 용사코팅법을 적용하였다. 실험은 실제 환경을 고려하여 캐비테이션 환경 하에서 다양한 전기화학적 실험을 동시에 병행하여 캐비테이션-부식 복합손상 거동을 분석하고자 하였다.