• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.529-535
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• 2011

In this study, evaluation of acoustic emission signals characteristics for the post weld heat treated (PWHT) multi-pass weldment and weldment was dealt. Charpy standard specimens were taken from the lowest, middle and highest regions of the weld block. Pre-crack was made using the repeated load. Four point bend and AE tests were conducted simultaneously. Regardless of the specimens, AE signals were absent within elastic region and produced in the process of plastic deformation. AE signals for all specimens were not emitted after the maximum load. Value of signal strength for the all PWHT specimens was lower than that of the weldment. Besides, relations of plastic deformation zone size and accumulated AE counts for the PWHT specimens were more simple compared with the weldment. In case of the PWHT specimen, particles on the fractured surface decreased prominently compared with the weldment due.to PWHT. From these results, it can be concluded that PWHT was effective in reducing the AE sources for the weldment.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.458-461
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• 2011

수산화마그네슘을 첨가한 저밀도 폴리에틸렌-에틸렌 비닐 아세테이트 복합체의 연소성을 시험하였다. 저밀도 폴리에틸렌-에틸렌 비닐 아세테이트에 수산화마그네슘을 40~80wt% 첨가하여 용융 혼합하고 성형 후 콘칼로리미터(ISO 5660-1)를 이용하여 연소성을 시험하였다. 수산화마그네슘을 첨가한 시편은 첨가하지 않은 시험편에 비하여 그의 플래시오버 가능성이 감소하였다. 수산화마그네슘을 첨가한 시험편은 첨가하지 않은 시험편에 비해 낮은 총열방출량과 낮은 CO 발생량을 나타내었고, 수산화마그네슘 함량이 증가할수록 총연기발생량과 비소화면적이 감소하였다.

• Fire Science and Engineering
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• v.29 no.6
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• pp.13-19
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• 2015

This study was performed to test the combustive properties of Pinus rigida specimens treated with phosphorus (P) and nitrogen (N) additives. Each Pinus rigida specimen was painted three times with 15 wt% P-N additive solutions at room temperature. After drying the treated specimens, the combustion properties were examined using a cone calorimeter (ISO 5660-1). The time to ignition (TTI) for the treated specimens was 90 to 148 s except for the specimen treated with PP/$4NH_4^+$, and the time to flameout (TF) was 556 to 633 s, which was longer than that of virgin plate. While the The specimens treated with P-N additives showed 12.5 to 43.4% higher mean heat release rate ($HRR_{mean}$) and 11.8 to 43.1% higher total heat release (THR) than virgin plate. The effective heat of combustion (EHC) was by 2.9 to 17.5% lower than that of virgin plate. It can thus be concluded that the combustion-retardation properties were partially improved compared to those of virgin plate.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.286.1-286
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• 2001

• The Magazine of the IEIE
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• v.41 no.8
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• pp.52-57
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• 2014

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.34 no.1
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• pp.49-59
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• 2005

• Proceedings of the Korean Nuclear Society Conference
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• 1999.10a
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• pp.83.2-83
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• 1999

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.716-722
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• 2009

4000MW급 유연탄발전소는 기존 500MW급 4기의 발전설비 운영조건에서 지역공동체는 긍정적이었으나, 500MW급의 증설 호기가 늘어나면서 지역 공동체는 발전소 증설과 관련하여 기존 동쪽 부지 경계지역의 소음환경에 대하여 부정적인 문제를 제기하였다. 2000MW급 증설이 진행되어온 4000MW급 발전소의 다양한 소음원에 의한 소음파워 증대와 증가방출 과도소음 에 대하여 고저가 다양한 주변지역에 미치는 영향음 평가하고자 3차원 모델링기법을 적용한다. 기존호기를 비롯한 전체의 발전소 전면부 소음원응 비교 시험결과 증가방출 소음 파워가 기존 설계의 변경 제작되어 기존호기에 비해 20~30dBA 높아져 동시 방출사 주변지역에 과도하게 영향을 미치는 상태였으며 500MW급 4기를 추가 증설에 따라 일상소음원에 의한 소음 영향도 증설전 대비 2~3dBA 증가된 것으로 평가되었다. 따라서 증설호기의 과도 소음원 제거 방안으로 대가 방출증가가 회수되도록 증설호기의 증가방출설비를 개선하였고, 증설에 의하여 증가된 소음 영향음 저감하고자 기존 경계지역에 미치는 소음원음 고려하여 방음벽음 설치한 결과 47 ~ 49dBA를 나타내고 인근 주거건물의 전면부 소음은 43dBA이었다.

• Journal of the Korean Institute of Gas
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• v.16 no.2
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• pp.18-24
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• 2012

This research seeks to evaluate damage on type II gas cylinder by an acoustic emission test when executing 20000 cycles fatigue test and thereafter burst test. Used gas cylinders in the experimental are three types as follows; one is sound cylinder, others are cylinders which contain longitudinal and transverse artificial defect. The size of artificial defect is a depth of 3 mm, width of 3 mm and length of 50 mm. In the case of the cylinder which artificial defect, unlike the expectation that it will burst in low pressure, the burst pressure of the cylinder did not differ much according to whether or not there were defects. However, when there was longitudinal defect, the location of burst was near the location of defect. This leads to the effect in which the thickness of the composite material becomes thinner according to the length of the longitudinal defect and this is judged to have an effect on the location of initiation and growth of crack in the liner. Also, for the acoustic emission signal, when there is longitudinal defect, the ratio of an event occurring at defect position among overall hits is more than 50 %, and the source location also accords very precisely with defect position.

• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.290-296
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• 2009

In this study, we considered the combustion of the various herbs in youngdong areas such as festuca ovina, isodeon japonicus, oplismenus undulatifolius, pueraria thunbergiana, and cirsium japonicum var. ussuriense using the ignition temperature tester, cone calorimeter, smoke density chamber. We confirmed that the range of ignition temperature was $400{\sim}455^{\circ}C$ and the time to ignition and flameout were not recorded. The total heat release of isodeon japonicus was highest and the smoke release of festuca ovina was highest, and the yield of CO and $CO_2$ of pueraria thunbergiana, and cirsium japonicum var. ussuriense were highest among the samples. As a result, we concluded that isodeon japonicus will impact the fire intensity and fire spread and festuca ovina, pueraria thunbergiana, and cirsium japonicum var. ussuriense will influence the refuge.