• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.830-836
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• 2001

An one-zone heat release analysis was studied for a 4 cylinder indirect diesel engine. The object of the study is to calculate the heat release accurately including the effect of specific heat ratio, heat transfer and crevice volume and to find out combustion characteristics of an indirect diesel engine cosidering the effect of both pressure in the main and swirl chambers. The integrated gross heat release values were close to the measured fuel energy at various full load operating conditions.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(1)
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• pp.369-373
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• 1998

증기발생기에서 부식에 의한 전열관 손상은 전열관과 관판사이의 틈새에서 대부분 발생되고 이 틈새에서의 수질환경에 좌우된다. 틈새에서는 과열도가 높아 미량의 불순물이 농축되면서 틈새수화학 (crevice chemistry)은 증기발생기 내부수 수화학과는 달라진다. 전열관 손상을 억제하기 위해서는 틈새수질을 적절히 제어하여야 하는데 이는 틈새수화학을 정확히 분석평가할 수 있는 기술을 기반으로 하여야 한다. .기존의 틈새수질을 계산하는 방법으로는 증기발생기 내부수에 비해 틈새에서 화학종들이 얼마나 농축되는지를 가정하는 농축도 (concentration factor) 방법이 있으나 가정에 의한 불확실성으로 인해 틈새수질을 정확히 해석할 수 없었다. 그러나 원전 증기발생기의 잠복불순물 방출시험 자료로부터 틈새수질을 보다 정확히 평가할 수 있는 새로운 개념의 몰비지수(molar ratio index) 방법이 최근 EPRI에서 제시되었고 EPRI 산하의 많은 발전소에서 적용중이다. 본 연구에서는 PWR 원전 증기발생기의 틈새수화학을 평가할 수 있는 기술을 개발하기 위해 잠복불순물 방출시험 자료로부터 틈새에서의 몰비지수를 계산할 수 있는 CRAP (CRevice-chemistry Analysis Program) 전산프로그램을 작성하였다 CRAP를 국내원전에 적용하여 증기발생기 및 그 틈새에서의 수화학을 평가하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.585-586
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• 2006

Several chemicals were studied to suppress the damage due to stress corrosion cracking (SCC) of steam generator (SG) tubes in nuclear power plants. The effects on the SCC of the compounds, $TiO_2$, TyzorLA and $CeB_6$, were tested for several types of SG tubing materials. The test with the addition of $TiO_2$ and $CeB_6$ showed an effect in decreasing the SCC for the SG tubing material. However, $CeB_6$ caused some more SCC for Alloy 800. The penetration property into a crevice of the inhibitors was investigated by using Alloy 600 specimens with different gap.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 춘계학술발표회요약집
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• pp.285-285
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• 2001

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.222.2-222
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• 1999

• 공업화학
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• 제20권2호
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• pp.177-185
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• 2009

자동차용 써모스타트 하우징 피팅부상의 침전물(스케일)에 대한 고장분석을 실시하였다. 에너지분산형분석기와 전자현미분석기를 이용하여 침전물이 부동액의 주요 첨가제 성분임을 확인하였다. 자세한 유기성분 분석을 위해 열분해 기체크로마토그래피/질량분석을 수행한 결과, 침전물의 주성분이 벤조산이며, 소량의 아세토페논, 벤젠 및 페닐계 화합물 등으로 이루어져 있음을 확인하였다. 더불어 침전물 생성 원인은 알루미늄 하우징과 고무호스 사이에 존재하는 틈새 공간에 부동액 성분의 침전에 따른 틈새부식에 기인한 것으로 판단된다. 이런 결과를 바탕으로 하여 써모스타트 하우징상의 침전물 생성과 틈새부식을 재현할 수 있는 가속시험기법을 개발하였다. 가속인자(온도, 습도)를 변화시키면서 실제 가동조건을 묘사하였다. 가속시험에서 얻은 침전물을 성분 분석을 통해 완벽히 재현되었음을 확인하였다.

• Corrosion Science and Technology
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• 제20권4호
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• pp.204-209
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• 2021

Corrosion failure analysis of the flow plate, which is one of the accessories of the plate heat exchanger in a district heating system, was performed. The flow plate is made of 316 stainless steel, and water at different temperatures in the flow plate exchanges heat in a non-contact manner. The flow plate samples in which water mixing issues occurred were collected. Corrosion-induced pits, oxides, and contaminants were observed at locations where two plates are regularly in contact. The EDS analysis of the surface oxides and contaminants revealed that they were composed of carbon, silicon, and magnesium, which came from chemical adhesives. The IC/ICP analyses showed that the concentration of chloride ions was 30 ~ 40 ppm, which was not sufficient to cause corrosion of stainless steel. In the crevice, a local decrease in dissolved oxygen occurs along with an increase in chloride ions, thus forming an acidic environment. These environments destroyed the passive film of stainless steel, resulting in pits. Moreover, contaminants formed a narrower gap between the two metal plates and inhibited the diffusion of ions, thereby accelerating crevice corrosion.

• Corrosion Science and Technology
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• 제22권6호
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• pp.435-446
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• 2023

Corrosion behaviors of laser-welded super duplex stainless steel (SDSS) tubes after exposure to an actual power plant environment for one year and those of fin-tube welded SDSS were evaluated. Results showed that corrosion damage on the back side of the SDSS tube in the direction of hot air was higher than that on the front side regardless of weldment location. However, corrosion damage showed no difference between weldment and base metal due to recovery of phase fraction in the weldment through post weld heat treatment (PWHT). Nevertheless, the SDSS tube showed severe corrosion damage along grain boundary due to surface phase transformation (δ → γ) and Cr₂N precipitation caused by PWHT with a high N₂ atmosphere. Corrosion resistance of the SDSS tube was recovered when degraded surface was removed. Corrosion sensitivity of a fin-tube increased significantly due to pre-existing crevice, unbalanced phase fraction, and σ phase precipitation adjacent to the fusion line. Although corrosion resistance was improved by recovered phase fraction and sufficient dissolution of σ phase during PWHT, corrosion reaction was concentrated at the pre-existing crevice. These results suggest that welding conditions for fin-tube steel should be optimized to improve corrosion resistance by removing pre-existing crevice in the weldment.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 춘계공동학술발표회요약집
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• pp.205-205
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• 2002

• Corrosion Science and Technology
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• 제4권3호
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• pp.75-80
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• 2005

This work dealt with the evaluation of galvanic corrosion rate in a corrosion cell having annular gap of 0.5 mm between carbon steel 1018 and alloy 600 as a function of temperature and boron concentration. Temperature and boron concentration were ranged from 110 to 300 $^{\circ}C$ and 2000~10000 ppm, respectively. After the operating temperature of the corrosion cell where the electrolyte was injected was attained at setting temperature, galvanic coupling was made and at the same time galvanic current was measured. The galvanic corrosion rate decreased with time, which was described by corrosion product such as protective film as well as boric acid deposit formed on the carbon steel with time. From the galvanic current obtained as a function of temperature and boron concentration, it was found that the galvanic corrosion rate decreased with temperaturewhilethe corrosionrate increasedwith boronconcentration. The experimental resultsobtained from galvanic corrosion measurement were explained by adhesive property of corrosion product such as protective film, boric acid deposit formed on the carbon steel wall and dehydration of boric acid to be slightlysolubleboric acid phase.Moreoverthe galvaniccorrosionrate calculatedusing initialgalvaniccoupling current instead of steady state coupling current was remarked, which could give us relatively closer galvanic corrosion rate to real pressurized water reactor.