• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.313-321
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• 2008

Recently in Japan, fracturing was observed on the diagonal member of a through truss bridge at the boundary region with the concrete slab. Local corrosion damage where the diagonal member was enclosed in the concrete slab is an important factor in the fracture. In this study, accelerated exposure tests were carried out on concrete-steel model specimens simulating steel members at the boundary with concrete. Fatigue tests were then performed on the corroded model specimens. Accelerated exposure tests of the S6-cycle, which is carried out on the model specimens for 150, 300, 450 and 600 da ys. Their surface geometry was then measured. From the accelerated exposure test results, change in maximum and mean corrosion depths was determined according to the testing periods. The effect of local corrosion on fatigue strength was also presented based on the fatigue test results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.143-148
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• 2011

Corrosion at the top of a distillation column is a common problem in refineries and chemical plants. In particular, severe damage has been inflicted in refineries by corrosive materials such as hydrogen sulfide and chlorine. Therefore, the mechanism of the corrosion occurring at the top of a distillation column has been analyzed, and a model for forecasting the corrosion rate has been developed. Four major materials were selected for modeling: $H_2S$, $CO_2$, $H^+$ and $Cl^-$. These were selected by taking into consideration their effect on the corrosion rate. Studies on the transport phenomenon and reaction engineering for this model were carried out, and the reliability of the model was verified on the basis of the data measured at a real refinery.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.2
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• pp.83-93
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• 1998

The twin aims of the present study are to develop a PC program for the statistical analysis of the measured cohesion data and to suggest a probabilistic corrosion rate estimation model for longitudinal members of tanker structures. A data analysis for the corrosion rate statistics(i.e., mean, standard deviation) as a function of the corrosion parameters is established for various structural member categories/locations of interest. Development of the computer program is focused on possible operation together with future addition of more corrosion data as they become available. To investigate the influence of the corrosion protection scheme a series of the corrosion analysis varying the life of coating are carried out and several different corrosion models as a function of time are suggested depending on the coating life.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.643-647
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• 2021

The purpose of this study was to access the possibility and ideal model for corrosive-induced tissue hyperplasia in the rat esophagus. Twenty rat were divided into two group: a healthy group, corrosive group. corrosive burn in esophagus were produced using 30% NaOH on the distal esophagus. After surgical procedure, behavioral and weight changes were monitored on a weekly. At 3 weeks after surgical procedure, fluoroscopic esophagogram was performed and then all rats sacrificed for histological analysis by administering inhalable pure carbon dioxide. Technical surgery for corrosive stricture were 100%. A total of 2 rats died in corrosive group from a corrosive burn related to dysphagia within 14 days. The esophageal stenosis ratio was significantly higher in the corrosive group than in the healthy group (40.1 ± 9.2 % and 1.4 ± 7.2%, respectively; p = 0.001). The tissue hyperplasia ratio was also significantly higher in the Corrosive group (62.5 ± 9% and 22.08 ± 6%, respectively; p = 0.001). Infusion of 30% NaOH may suggest alternative option to evaluation tool for preclinical study in a rat corrosive model.

• Journal of the Korean GEO-environmental Society
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• v.9 no.1
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• pp.17-25
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• 2008

In this study, external and internal pit growth rate model and external non-linear regression corrosion model were proposed by measuring pit depths and evaluating various soil factors known to contribute to the corrosion for metallic water pipes. Average pit depths of external and internal for metallic water pipes were measured 1.38 mm and 2.13 mm, and internal pit growth rate also fasted twice than external pit growth rate. This means the corrosion potential of water quality was higher than soil. The corelation between external corrosion rate and each soil corrosion factor was low. However, proposed external non-linear regression corrosion model considering all soil corrosion factors showed a little higher correlation ($R^2=0.46$) than conventional model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.2
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• pp.191-198
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• 2005

This study was carried out to investigate quantitatively the relationship between the degree of rebar corrosion and the strength of reinforced concrete beams. After producing equations for the relationship between both the tensile properties of rebars and bond properties and the corrosion percentage of rebars, finite element analysis and bending tests were conducted for RC beams damaged by corrosion of tension main rebar. As a result, it was made that the strength of RC beams damaged by corrosion could be practically simulated by FEM analysis using experimentally determined material properties representing the bond and the mechanical characteristics of corroded rebars.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.727-732
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• 2022

Applying the calculated cross-sectional reduction due to the corroded rebar investigated in the field to the numerical analysis model, the damage pattern and delamination of concrete in the field showed a tendency relatively similar to the numerical analysis results. It was analyzed that when the expansion pressure due to corrosion of the reinforcing bar is greater than the tensile stress of the concrete, cracks are generated and the concrete cover can be fracture. As a result of this study, the correlation between the corrosion rate of reinforcing bars and the crack occurrence of the concrete cover of the subway box structure was verified based on the numerical analysis and field test results. To prevent rebar corrosion, the corrosion rate can be reduced by applying rust prevention to the reinforcing bar and changing the material. In the case of exposed to a corrosive environment, the tensile strength of the concrete is improved by adjusting the concrete compressive strength to secure durability against the expansion pressure caused by the corroded rebar.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.1
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• pp.130-135
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• 2007

In order to examine the corrosiveness of tap water, we studied methods calculating various indices including calcium carbonate saturation indices, using RTW model and LPLWIN model. Indices such as LI, RI and AI could be computed using the RTW model, whereas the LPLWIN model could find indices as LI, LR and CCPP. With water quality data obtained from tap water of Han River and Nak-Dong River watersheds, based on the indices found from the models, the water quality of the Nak-Dong River is better than that of Han River in the point of resisting corrosiveness. Further, the water quality of winter is highly corrosive than that of summer, as long as the temperature rises up, the corrosiveness is reduced.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.325-327
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• 2003

원자력 발전소 2차계통수에는 pH를 조절하여 부식을 억제하기 위해 pH제어제로 암모니아를 사용하였으나 상변화 지역에서 액상의 pH가 낮아 부식생성물이 생성, 증기발생기로 유입되어 진열관의 부식을 촉진 시킨다. pH 제어제로 암모니아 대신 ETA를 도입하여 pH를 증가시키고 증기발생기로 유입되는 부식생성물의 양을 감소하여 진열관의 부식을 억제시키고 있다. 그러나 암모니아에서 ETA로 변경함에 따라 증기 발생기취출수계통의 탈염의 운진기간이 단축되었다. 따라서 본 연구의 목적은 탈염기의 수지 교체주기도 연장시키고 안전성도 확보할 수 있는 탈염기내 양ㆍ음이온 이온교환수지 조성 비율을 최적화하는데 있다. 연속화학평형모델을 이용한 결과 양ㆍ음이온 이온교환수지 비율이 10:1일 경우 최적인 것으로 조사되었다.

• CORROSION AND PROTECTION
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• v.12 no.1
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• pp.12-23
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• 2013

원자력 발전소 주요 부품에 사용되는 Alloy 600의 PWSCC 개시와 전파기구를 살펴보고 그 억제 기술을 소개하였다. ○ 균열은 경화된 표면 산화층이 깨질 경우, 입계부식, 공식(pitting), 열처리 또는 물속에 노출되었을 때 일어나는 선택부식(selective corrosion), MnS등 게재물의 용출등에 의해 시작된다. ○ 균열의 전파는 '느린 성장'과 '빠른 성장'으로 구별해 볼 수 있는데 빠른 균열성장은 균열 선단에서의 응력확대 계수(K_I)가 균열이 전파하는 임계값(K_Iscc)을 넘는 경우에 일어난다. ○ Slip Dissolution/Film Rupture Model, Enhanced surface mobility model, Hydrogen assisted creep rupture, Internal oxidation 등의 모델이 제시되어 있으며 Internal oxidation 모델이 여러 실험자료로 잘 뒷 받침되고 있다. ○ PWSCC 억제 방안으로는 부식환경과의 격리 및 보수용접이 대표적이며 부품의 교체를 통한 안전 확보의 방안도 있다. 수소량 조절을 통한 억제 방안도 제시되어 있다. ○ Alloy 600 PWSCC열화 관리 전략프로그램은 결함 발생 가능성이 높은 부위 선정, 우선 순위에 따른 계획적인 검사, 결함이 발견될 경우 완화조치를 취하거나 필요시 교체/보수를 실시하고 그 운영프로그램을 지속적으로 갱신관리하는 방안으로 유지되어야 한다.