정변위 인장시험기를 사용하여 SUS 304강 용접열 영향부의 여러 가지 염화 마그네슘용액 중에서의 SCC 발생 특성을 연구한 결과 다음과 같은 결론을 얻었다. 1) SCC 발생 잠복기간은 초기 응력강도계수 K 하(Ii) 값은 낮게 함으로써 크게 지연된다. 2) 비등 염화 마그네슘 용액 중에서의 SCC 발생은 부하와 Cl 이온의 농도에 의한 부동태 피막의 파손에 기인된다. 3) SUS 304 강 용접열 영향부의 SCC 발생 감수성은 높은 농도의 염화 마그네슘 용액일수록 온도를 낮게 함으로써 둔화된다.

백엽고병에 대한 저항성품종으로 알려진 밀양 30호의 이병화원인을 구명하기 위하여 수원, 밀양, 해남산에 대한 최고분얼기, 출수기엽과 기본식물에 대한 각균군의 균주별 저항성 관계를 조사한 결과 가. 년 전국에서 이병된 밀양 30호의 침해균군 비친화성으로 밝혀진 I, II균군의 균주가 다수분리되었다. 나. 산지 및 생육시기별 저항성 정도의 차는 인정할 수 없었으나 II 균군의 특수균주(병원성 분화형)에 대해 침해받았음이 원인이었다. 다. 밀양 30호의 기본식물에서도 동일 균군 균주에 의해 반응이 일치되므로 품종보다 균주의 병원성 분화에 따른 이병화임을 알 수 있었다.

Si-Cr계 내열강 SUH3와 Cr-Ni계 stainless강 SUS 303 및 이들이 마찰용접재 SUH3-SUS303을 1,060℃에서 용체화처리하고 다시 700℃에서 10, 100시간 시효열처리한 각 시험편의 고온 피로강도에 대한 시효열처리의 효과를 알기 위하여 700℃에서 고온 회전굽힘 피로시험을 하고 파약거동을 미시적으로 관찰하여 다음과 같은 결과를 얻었다. 1) SUH3재와 SUS303재의 최적마찰용접조건은 회전수 2420rpm, 마찰가압력 8kg/mm2, 전 upset량 7mm(마찰가압시간 3sec, upset시간 2sec)이었다. 2) 700℃ 고온에서 장시간 이루어지는 고온피로시험에 있어, 용체화처리재의 S-N 곡선 경사부의 기울기가 가장 급하게 나타났다. 3) SUH3-SUS303 마찰용접재는 1,060℃에서 1시간용체화 처리하고, 700℃에서 시효처리하는 경우 최적시효시간은 10시간이었다. 4) 10시간 시료재의 고온피로한도는 모재보다 SUH3은 75.4%, SUS303은 28.5% 높았으며, 용접재 SUH3-SUS303은 44.2% 정도 높았다. 100시간 시효재는 모재보다 SUH3은 64.91% SUS303은 30.4% 높았으며, SUH3-SUS303은 30.4% 높았으며, SUH3-SUS303은 36.6% 높았다. 5) 마찰용접재의 상온 및 고온의 피로파단은 모두 SUS303의 모재측에 발생하였으며, 용접면에서의 파단은 전혀 없었다. 6) SUS303재와 마찰용접재 SUH3-SUS303재의 크랙은 입내파양형이었으나 SUH3은 입계크랙의 전파로 파양한다.

This study sought to confirm the inhibitory ability of Clostridioides difficile KCTC 5009 strain using the bacteriocin-producing Lactococcus lactis CJNU 3001 strain. For this purpose, bacterial culture and partially purified bacteriocin verified the antibacterial activity against C. difficile strain. As a result, both samples showed strong antibacterial activity against the target strain. Co-culture tests were performed to more closely analyze the competition between the two strains. As a result, a similar inhibitory effect was confirmed in RCM broth and CMM (colon model medium) broth. In particular, inhibition of C. difficile KCTC 5009 strain was not observed until the exponential phase of the growth of L. lactis CJNU 3001 strain, because bacteriocins were produced during that period. It was inferred that it actively suppressed the growth of the target strain after that. Therefore, as it was proven that the bacteriocin-producing L. lactis CJNU 3001 strain can effectively control C. difficile strain in co-cultures, it was judged that it could be an alternative for CDI (Clostridioides difficile infection) treatment.

As the decommissioning of domestic nuclear power plants (Gori Unit 1 and Wolseong Unit 1) becomes more visible, many research projects are being conducted to safely and economically decommissioning of domestic nuclear power plants (NPPs). After permanent shutdown, decommissioning of NNPs proceeds through decontamination, cutting of main equipment, waste disposal and site restoration stages. And various technologies are applied at each stage. In particular, remote cutting of neutron induced structures (RV, RVI, etc.) is a technology used in developed countries in the cutting stage, and remote cutting has been evaluated as a core technology for minimizing workers’ radiation exposure. Generally, remote cutting technologies are divided into mechanical/thermal/electrical cutting. Among various thermal cutting technologies, plasma arc cutting (PAC) is more economical and easily to remote control than other cutting technologies, and is also effective in cutting STS304 plates. PAC is a thermal cutting technology that melts the base material at the cutting area with a plasma arc heat source and removes melted material by blowing it out with cutting gas. The cutting quality depends on the stand-off distance and power (current), material thickness, cutting speed, etc., while double arcing will occur if the cutting conditions are not suitable. A monitoring system that can confirm double arcing during remote cutting is necessary because double arcing can reduce cutting quality, increase secondary waste (increase kerf and aerosol), and cause non-cutting. In this study, we used an ultrahigh-speed camera equipped with a band-pass filter to capture clear arc shapes, and measured voltage waveforms with a data acquisition system. We studied a monitoring method that can confirm the occurrence of double arcing by synchronizing the obtained arc shape and voltage waveform, and the effects of double arcing on the STS304 plates. The results of this study are expected to be helpful in the development of the remote cutting process using plasma arc cutting when decommissioning of domestic NPPs.

The decommissioning of nuclear power plants will generate a lot of low and intermediate-level radioactive waste (LILW), and preliminary radioactive evaluation for these wastes should be carried out before decommissioning work. Mainly, Concrete, Carbon Steel, Stainless Steel-304 (SS304) and Inconel are used in many parts of nuclear power plants and considered as main resource of nuclear wastes. Depending on the material location, the number of neutrons irradiated to material varies, which can range from self-disposal waste to LILW. In this paper, activation analysis was performed to compare the radiation dose according to the presence or absence of impurity elements present in SS304. For the calculation, SS304 composition and impurity elements were used as described in the report of NUREG-3474. This report lists 41 impurity elements for SS304 and other materials. Calculation code is used ORIGEN-S module in SCALE 6.1 code. Neutron flux is used as arbitrary value that around 1E+11 level and irradiation time is set as 30 year with 10-year cooling time. In the ORIGEN-S calculation, 1g of SS304 is used for easy calculation of specific activity. The ORIGEN-S calculation results are as follows. All impurity elements contained case calculated 9.32E+07 Bq activity. In the absence of all impurity elements case and most cases shows that total Becquerel value after 10-year cooling time around 9.11E+07 Bq, and Co impurity case had larger result. The calculation was performed again by increasing the amount of impurity substances by 100 times to perform the sensitivity evaluation more reliably. Representatively, Li, N, Co, and Ba impurity elements cases were calculated to have a particularly high Becquerel. Especially Co impurity element case, a total Becquerel of 3.03E+08 was calculated. Accordingly, evaluation of impurities mixed in SS304 must be considered, and in particular, the inclusion rate for Co must be considered.

This study investigated characteristics of meteorological parameters and ionic components of PM2.5 during Asian dust events on November 28 and 30, 2018 at Busan, Korea. The seasonal occurrence frequencies of Asian dust during 1960∼2019 (60 years) were 81.7% in spring, 12.2% in winter, and 6.1% in autumn. Recently, autumn Asian dust occurrence in Busan has shown an increasing trend. The result of AWS (automatic weather station), surface weather chart, and backward trajectory analyses showed that the first Asian dust of Nov. 28, 2018, in Busan came with rapid speed through inner China and Bohai Bay from Mongolia. The second Asian dust of Nov. 30, 2018, in Busan seems to have resulted from advection and deposition of proximal residual materials. These results indicated that understanding the characteristics of meteorological parameters and ionic components of PM2.5 during Asian dust events could provide insights into establishing a control strategy for urban air quality.

Corrosion cells that simulates engineering barrier system have been stored in an aerobic KURT environment for 10 years, which were recovered and dismantled in 2021. The test specimens were compressed copper (Com. Cu), Cold spray copper (CSC Cu), Ti Gr.2, STS 304, and Cast nodular iron. The specimens were buffered by compact Ca-type Gyeongju bentonite (KJ-I) and compact Na-type Wyoming bentonite. And the corrosion cells were exposed to KURT groundwater at 30°C for about 10 years (3,675 days). As a result of the long-term experiment in aerobic environment, it was confirmed that Na-bentonite is more advantageous for inhibiting corrosion than Ca-bentonite. The corrosion thickness of the most specimens in Ca bentonite was slightly lower than in Na bentonite until the initial 500 days, but after 10 years, the corrosion thickness of copper and cast iron specimens in Na bentonite was clearly lower. The corrosion thickness of the copper specimen in Na bentonite was very low about 0.5 um in both Com. Cu and CSC Cu. Moreover, the corrosion thickness in Ca bentonite was very high about 4 um for Com. Cu and 6 um for CSC Cu. In the case of cast iron, the corrosion thickness in Na bentonite was about 13 um, and 15 um in Ca bentonite. The common feature of copper and cast iron specimens in Ca bentonite, which showed a high corrosion thickness, is the forming of a white mineral deposition layer on the specimen surface, which was presumed to be some kind of feldspar. On the other hand, it was found that the STS304 and Ti specimens were hardly corroded even after 10 years. In conclusion, when a white mineral deposition layer was formed on the specimen surface, the corrosion thickness always increased sharply than before, and thus it was estimated that the generation of the mineral deposition layer cause the increase of bentonite permeability, and rather the weakening of existing passive corrosion film.

엘리엇은 비비엔과의 이혼과 헤일과의 재혼을 간곡히 소망하며 「재의 수요일」을 썼으나 결국 이혼도 재혼도 못했다. 엘리엇과 헤일의 관계는 1930-56년간 그들의 연서와 1963년 엘리엇의 입장문에서 밝힌 바와 같이 사회법과 교회법을 넘지 못했고 결국 명예로운 관계로 끝날 수밖에 없었다. 하지만 엘리엇이 헤일에게 보낸 연서는 그들의 깊은 사랑과 헤 일의 영향력을 증명하였고, 그의 1963년 입장문은 그들의 슬픈 운명을 재확인시킨다. 엘리엇은 이미 「재의 수요일」에서 그의 간절한 사랑과 이로 인해서 용서받을 수 없는 그들의 죄의식과 슬픈 운명을 예감하였고, 오직 하나님의 자비와 용서를 간구할 뿐이었다. 따라서 그는 자신의 연인이자 뮤즈, 그리고 비공식 아내인 헤일을 현재나 미래의 시간의 차원에 둔 것이 아닌 영원의 차원의 성령과 같은 존재로 박제하고자 했던 것 같다. 이런 재의 수요일의 침묵의 여인은 죄인들/우리들을 위하여 기도하는 성모와 같은 모습의 여성적 원형에 성령 하나님의 영성이 반영되어 영원히 아름답고 성스럽게 빛나게 된다.

록킹 거동은 구조체가 수평력을 받을 때, 수직 중심을 기준으로 좌우로 회전하는 거동을 의미한다. 본 연구에서는 최신의 연구 동향을 개념으로 하여 강체 좌우에 댐퍼를 설치하여 에너지를 소산시키는 방법을 고안하였다. 강재 댐퍼는 SS275 강종을 사용하였으며, 두께 12mm, 폭 30mm, 높이 140mm인 S형 스트럿을 가지는 형상을 사용하였다. 실험은 변위를 점진적으로 증가시키면서 진행하였다. 향후 댐퍼 스트럿 형상 및 스트럿 높이를 변수로 한 성능실험 결과를 발표할 예정이다.

스테인리스강은 최근에 다양한 구조 부재와 산업분야에서 스테인리스강의 상용이 증가하고 있다. 그러나 스테인리스강은 건축구조기준에 구조재료로 포함되어 있지 않고 해당 설계기준은 규정되어 있지 않다. 본 논문에서는 오스테나이트계 스테인리스강 STS304로 제작된 이면전단 볼트접합부에 대한 실험적을 수행되었다. 주요 변수는 볼트배열과 하중방향 연단거리로 설정하였다. 실험 결과, 순단면파단과 블록전단파단이 발생하였고, 블록전단파단 접합부의 경우연단거리가 증가함에 따라 내력이 증가하였다. 또한, 현행 기준식에 의한 예측내력과 실험 내력을 비교하였다.