• Composites Research
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• v.36 no.1
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• pp.37-41
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• 2023

The treated water inside the ballast electrolytic cell creates a highly alkaline atmosphere due to hydroxide generated at the DSA(Dimension Stable Anode) electrode during electrolysis. In this study, a composite material that can replace the weakness of the PE-coated steel pipe used in the existing ballast pipe was prepared. The test samples are BRE(Basalt fiber reinforced epoxy), BRP(Basalt fiber reinforced unsaturated polyester), GRE(Glass fiber reinforced epoxy), and GRP(Glass fiber reinforced unsaturated polyester). And then it was immersed in NaOH for 720 hours. The friction test of each specimen was conducted. The Friction coefficient analysis according to material friction depth and interfacial adhesion behavior between resin and fiber were analyzed. As a result, the mechanism of interfacial separation between resin and fiber could be analyzed. In the case of the unsaturated polyester resin with low interfacial bonding strength the longer the immersion time in the alkaline solution, the faster the internal deterioration caused by the deterioration that started from the surface, resulting in a decrease in the friction coefficient. It is hoped that this study will help to understand the degradation behavior of composite materials immersed in various chemical solutions such as NaOH, acid, and sodium hypochlorite in the future.

• Journal of Applied Reliability
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• v.14 no.3
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• pp.176-181
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• 2014

In these days, new and renewable energy is getting popular around globe and wind power generator is one of the renewable energy. In this study, we conducted a study on defect detection of composite material blade for wind power generator by applying active infrared thermography and produced a defect test piece by applying composite material used for blade of wind power generator. An infrared thermal camera and 2 kW halogen lamp are used for the purpose of research as equipments. Also, we analyzed temperature characteristic by using infrared thermal camera after checking a heat source on a test piece and found effectiveness of infrared thermography to blade of wind power generator by detecting defects resulting from temperature difference of a test piece, which eventually improve the safety and reliability of the composite material blade.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.174-180
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• 1998

In this work, the properties of FRP, which is applied recently in the composite insulating materials, by thermal treatment were investigated. The specimens were epoxy glass laminates fabricated by thermal press method and had the volume content of 46[%] cutted $45^{\circ}C$ in the fiber direction and 1.0[mm] thickness. The experimental results showed that the amount of weight loss, wettability, surface potential, and surface resistivity increased up to 200[$^{\circ}C$] as a function of temperature. Usually, most degradations caused the hydrophilic to decrease the contact angle. But, in this work on thermal-degradated FRP, we can confirm the introduction of hydrophobic properties by cross-linking and the ablation of polar small-molecules rather than chain scission and oxidation. Finally, weight loss and contact angle increased. These phenomena show the existence of hydrophobic surface. With the change to the hydrophobic surface and the electrical potential and resistivity on FRP surface increased. But, the dielectric properties and tensile stength are decreased.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.125-130
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• 2011

발전 설비는 기대 수명동안의 안정성을 확보하기 위하여 해당 규격에 부합하도록 설계하여 건설된다. 하지만 가동 중 다양한 복합 환경에 노출됨에 따라 구조물을 이루고 있는 재료의 열화 현상이 가속화되어 예기치 못한 파손이 발생할 수 있다. 기계적 물성은 재료의 기계적 거동을 나타내는 주요 척도가 되며 이는 신뢰성 및 안전과 직결된다. 하지만 기존의 역학물성을 측정하는 대부분의 시험법들은 특정 크기의 시편을 요구하고 파괴적인 시험법이기 때문에 가동 중 시설물에 적용하기가 불가능하였다. 이러한 한계점을 극복하고자 비파괴적이고 정량적인 시험이 가능한 연속압입시험법이 최근 각광받는 시험법으로서 많은 연구자들에 의해 연구되고 있다. 이 시험법은 시험 대상물의 형상에 제약을 받지 않으며 시험 절차가 매우 간단하다는 장점을 가진다. 또한 대상의 국소 부위에 시험할 수 있어 취약 부위 판별이 가능하다. 본 연구에서는 대표응력-대표변형률 기법을 통하여 인장물성을 평가하고, 압입 하중 차이를 이용하여 소재에 존재하는 잔류응력을 평가하는 기법을 소개한다. 또한, 연속압입시험을 이용하여 실제 발전소 파이프의 취약부위로 알려진 용접부에 대하여 인장물성 및 잔류응력을 측정함으로써 실제 산업체의 신뢰성 평가가 적용할 수 있음을 확인하였다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.3
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• pp.123-127
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• 2015

Thermochemical heat storage is a cutting-edge technology which can balance the energy usage between supplies and demands. Recent studies have suggested that thermochemical heat storage has significant advantages, compared to other storage methods such as latent heat storage or sensible heat storage. Nevertheless, ongoing research and development studies showed that the thermochemical heat storage has some serious problems. To bring the thermochemical heat storage method into market, we introduce experimental setup with composite material using perlite that supports calcium chloride sorbent. Also, to compare thermal properties with composite material, we used pure thermochemical material. Then, we found that the composite material has higher heat storage density by mass than pure calcium chloride. Moreover, it can be easily regenerated, which was impossible in the pure thermochemical materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.481-484
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• 2003

Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators have significant advantages over porcelain and glass insulators. With the gradual improvement of their design and material, their reliability has also increased. It is however difficult to establish how they will perform after several years of service. Aging of the insulator weathershed may lead to damages such as excessive chalking and crazing, erosion and tracking which affect the insulator performance. In service insulator are subjected to aging stresses such as humidity, pollution and electrical field which act singly or in combination. There have been numerous accelerated laboratory tests developed with the intention of evaluating suitability of polymeric materials. Some of these are strictly material tests, where as, others evaluate full scale devices. Service experience plays a key role in the utility selection of polymer insulator, but is time consuming, and may not always be available. Hence there is a need for a meaningful and reliable accelerated aging test for polymer insulator. This paper describes multi-stress aging test for reliability of polymer insulator This paper presents the rule of multi-stress aging test and test chamber for polymer insulator in korea electrotechnology research institute.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.91-94
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• 2003

Ceramic femoral heads in the total hip replacement have been developed to reduce the polyethylene liner wear. Alumina and zirconia (3Y-TZP) are using in clinical application worldwide and there are many good test reports. However, alumina has a risk of catastrophic failure, and zirconia has the low temperature degradation in spite of enhanced fracture toughness. Recently, novel zirconia/alumina composite having low temperature degradation-free character and high fracture tough . was developed and it leads the lower wear 3f polyethylene than alumina and zirconia. In the present study, in order to optimise the microstructure of low temperature degradation (LTD)-free zirconia/alumina composite for the best wear resistance of polyethylene, various compositions of (LTD)-free zirconia/alumina composites were fabricated, and the sliding wear of UHMWPE against these novel composites were examined and compared with that against alumina and zirconia ceramics used for total hip joint heads.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.4
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• pp.285-301
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• 1988

The symbol error rate equations of multi-level quadrature PRS(QPRS) system have been derived in the individual and composite environment of Gaussian/impulsive noise, cochannel CW interference, carrier offset, phase jitter and fading. And using the derived error rate equations, the probability of error has been evaluated and shown in graphs as functions of carrier to noise power ratio, carrier to interference power ratio, phase error, impulsive index, the ration of Gaussian noise to impulsive noise power component, signal to noise power ration in phase locked loop(PLL), and fading figures. The rseults show that the error rate performances are generally more more degraded by impulsive noise than by Gaussian noise. But on the contrary the erors occurred more frequently by Gaussian noise than impulsive noise in a fading environment.

• Journal of the Korean GEO-environmental Society
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• v.18 no.7
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• pp.5-12
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• 2017

The surface of the tunnel lining issues various problems such as cracks due to the cold weather. It is necessary to reduce the recovery costs by means of developing new recovery techniques. However, the research on reducing the damage of road tunnel lining caused by cold weather has not actively been conducted. Hence, this paper analyzes the effectiveness of using insulating materials such as aerogel and heat insulating liquid in enhancing insulating capability. The results show that these materials are effective in reducing heat transfer, confirming damage reduction in cold weather.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.141-142
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• 2017

New waterproofing technologies have emerged in the field of building waterproofing due to the recent diversification of the size and type of structures, the enhancement of required performance, and the diversification of new technologies (such as materials and methods)(Sheet waterproofing material, coating waterproofing material) is reduced, and composite waterproofing materials that utilize mutual benefits are widely used by compounding them (sheet+coating film, coating film+sheet). However, it is true that there is no evaluation method that can verify these composite waterproof materials, which is the most widely used at present, but the KS standard only specifies tests for individual materials However, there is a situation in which the countermeasures without a test method for composite waterproofing become sudden.