• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.481-487
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• 2010

A room scale fire test was done for interior materials from a subway vehicle installed within an ISO 9705 fire test room. The interior materials are the old ones which were made before the new fire safety guideline of subway vehicles. The output of ignition burner was increased in controlled steps to CEN/TS 45545-1. The objectives of this interior fire test are to assess the fire performance in terms of ignition and flame spread on interior lining materials and to provide data on an enclosure fires involving subway vehicle interior materials that grow to flashover. Temperatures, heat flux and heat release rate variations verse time of the test are measured. Heat release rate is compared with that of calculated by modified flaming area based summation method. These test results will be used for verification of CFD fire simulation of full subway vehicle.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.243-249
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• 2005

The chemical and toxicological studies were conducted with acetamiprid 2% granules including different controlling agents for development of controlled-release acetamiprid 2% granule. The fundamental formulation recipe of acetamiprid 2% granule was prepared by the insoluble matrix using polyethylene wax. Starch, cellulose and mineral (calcium carbonate) were used as controlling agents. As a result of studies, release rate of active ingredient from granules into water static condition at $25^{\circ}C$ was increased by addition of starch and cellulose, but was decreased by addition of calcium carbonate. We could select calcium carbonate as controlling agent and make three granules which there were difference in release profiles of active ingredient according to contents of polyethylene wax. 24 hours-release rates of acetamiprid from three granules into water static condition at $25^{\circ}C$ were respectively 75, 50 and 25% when contents of wax were 2, 10 and 20%. The granule which 24 hours-release rate was 25% showed lower acute toxicity against mice and rats.

• Composites Research
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• v.35 no.2
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• pp.61-68
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• 2022

Composite materials have been used in aerospace industry and many applications because of many advantages such as specific strength and stiffness and corrosion resistance etc. However, it is vulnerable to impacts, these impact lead to formation of cracks in composite laminate and failure of structures. In this paper, we analyzed Mode I fracture toughness of Carbon/Epoxy laminates using acoustic emission signal. DCB test was carried out to analyze Mode I failure characterization of Carbon/Epoxy laminates, and AE sensor was attached to measure AE signal induced by failure of specimen. Fracture toughness was calculated using cumulative AE energy and measured crack length using camera. The calculated fracture toughness was applied in FE model and the result of FE analysis compared with DCB test results. The results show good agreement with between FEM and DCB test results.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.5
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• pp.343-352
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• 2006

In the present paper, the nondestructive test method was suggest to establish the bonding status of a motor case assembly composed of a steel motor case, adiabatic rubber layer and an ablative composite tube with strain data, AE(acoustic emission) signals and UT(ultrasonic test) data. And, finite element analysis was conducted to verify quantitatively the bonding status of motor case assembly under inner pressure loading. The bonding status could be judged whether the bonding status is perfect or contact condition by the data correlation study with AE signals and strain data measured from air pressure test. And, to classify the bonding status of motor case and rubber layer among bonding layers, UT method was also applied. From this study, the bonding status could be classified and detected into fourth types for all bonding layers as follows: (1) initial un-bonding, (2) perfect do-bonding during an air pressure test, (3) partially de-bonding during an air pressure test, and (4) perfect bonding.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.11a
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• pp.133-134
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• 2009

조사 핵연료 및 구조재료의 핫셀시험을 위한 조사재시험시설은 고방사능물질의 시험 및 취급과정에서 발생한 각종 방사성 물질에 오염된 공기를 정회하기 위한 특수 공기조화설비를 운영하고 있다. 시설의 배기 계통은 핫셀 계통 및 핫셀 이외의 계통으로 니눠지고 있다. 그 중 핫셀 구역 이외의 공기는 1차적으로 프리필터와 HEPA 필터로 구성된 AFU(Air Filtering Unit)로 정화하여 외부에 방출하는 MUP(Medium Under Pressure) 시스템을 채용하고 있다. 외부에 방출하는 배기의 오염을 최소화하기 위하여 설치된 AFU에 대한 풍량 측정 및 HEPA필터의 성능시험을 실시하였으며, 그 결과에 대하여 고찰하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.7
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• pp.891-897
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• 2013

In this study, the compressive deformation behaviors of aluminum alloy under high strain rates were investigated by means of a SHPB test. An acoustic emission (AE) technique was also employed to monitor the signals detected from the deformation during the entire impact by using an AE sensor connected to the specimen with a waveguide in real time. AE signals were analyzed in terms of AE amplitude, AE energy and peak frequency. The impacted specimen surface and side area were observed after the test to identify the particular features in the AE signal corresponding to the specific types of damage mechanisms. As the strain increased, the AE amplitude and AE energy increased whereas the AE peak frequency decreased. It was elucidated that each AE signal was closely associated with the specific damage mechanism in the material.

• Composites Research
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• v.17 no.4
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• pp.61-67
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• 2004

Nondestructive damage sensitivity on single-basalt fiber/epoxy composites was evaluated by micromechanical technique and acoustic emission (AE). Piezoelectric lead-zirconate-titanate (PZT), polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer were used as AE sensor, respectively. In single-fiber composite, the damage sensing with different sensor types were compared to each other. Piezoelectric PVDF polymer sensor was embedded in and attached on the composite, whereas PZT sensor was only attached on the surface of specimen. In case of embedded polymer sensors, responding sensitivity was higher than that of the attached case. It can be due to full constraint inside specimen to transfer elastic wave coming from micro-deformation. For both the attached and the embedded cases, the sensitivity of P(VDF-TrFE) sensor was almost same as that of conventional PVDF sensor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.4
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• pp.373-378
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• 2012

The objective of this research is to examine the probabilistic approach to evaluating turbine ejection frequency considering common-cause failure. This paper identifies basic turbine ejection mechanisms under high and low speeds and presents a detailed probabilistic methodology (fault tree) for assessing ejection frequency. The alpha factor methodology is applied to common-cause failure evaluations. The frequencies under different test schemes are compared and the propagation of uncertainty through the fault tree model is evaluated. The following conclusions were reached: (1) the turbine blade ejection frequency due to ductile failure under high speed is around 8.005E-7/yr; (2) if common-cause failure is considered, the frequency will be increased by 11% and 33% depending on the test scheme; and (3) if the parameter uncertainties are considered, the frequency is estimated to be in the range of 9.35E-7 to 1.13E 6, with 90% confidence.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.4
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• pp.323-330
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• 2008

High cycle bending fatigue of socket welded small bore pipe was characterized, and also the fatigue crack initiation of small bore pipe was monitored in situ by the acoustic emission (AE) technique. The STS 316L stainless steel specimens were prepared by gas tungsten arc welding (GTAW) process having the artificial defect (i.e., lack of penetration) and defect free at the root. The fatigue failure was occurred at the loc for high stress and root for relatively low stress. The crack initiation cycles ($N_i$) was defined to the abrupt increase in AE counts during the fatigue test, and then the cracks were observed by the radiographic test and electron microscope before and after the fatigue crack initiation cycles. The socket welded pipe damaged by bending fatigue was studied regarding the welding defect, failure mode, and crack initiation cycles for the diagnosis and monitoring.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.3
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• pp.183-190
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• 2011

This study investigated the emissions characteristics of air freshener using small emission chamber method. The emission of VOCs from air freshener were determined in the small chambers in the temperature (25, $30({\pm}1)^{\circ}C$), relative humidity ($50{\pm}5%$), ventilation rate (0.3, 0.5, ($0.8({\pm}0.005)/hr$), and sample loading factor ($1.4{\sim}551.0g/m^2$) in this study. The emission tests from air freshener for sample loading factor resulted in TVOC emission rates of $0.7{\sim}64.4mg/m^2{\cdot}h$ after 5 hours. For most target VOCs such as limonene, ${\alpha}$-pinene and linalool, higher temperature and ventilation rate levels exhibited increased emission rates.