토마토황화잎말림바이러스병에 대한 저항성 품종과 항바이러스 활성 물질 3종의 효과 검증

권용남(Yongnam Kwon),차병진(Byeongjin Cha),김미경(Mikyeong Kim) 한국식물병리학회 2022 식물병연구 Vol.28 No.2

최근에는 작물의 유도 저항성을 이용한 항바이러스제 개발에 관한 많은 연구가 수행되고 있으나 실제 농업현장에 널리 보급되지 못하고 있는 실정이다. 본 실험은 시설토마토 재배현장에 외생 살리실산, 키토산, 유제놀 처리에 따른 토마토황화잎말림바이러스(Tomato yellow leaf curl virus, TYLCV) 감염억제효과를 검증하고자 수행되었다. 실내검정에서 TYLCV에 감수성품종인 ‘슈퍼도태랑’은 항바이러스제 처리 후 TYLCV에 감염된지 12일 후 VP (virus infected control plants)에서 바이러스 증상이 나타나기 시작했다. 접종 32일 후 TYLCV 발병도는 VP에서 98.8%였고, SAT (2 mM salicylic acid)+VP, EGT (200 μg/ml eugenol)+VP에서는 각각 98.8%, 98.7%로 발병도가 높았으나, CHT (0.1% chitosan)+VP는 85.7%로 다른 처리들과 통계적으로 유의한 차이를 보였다. 그러나 TYLCV 농도는 CHT+VP에서 OD값이 0.3으로 오히려 가장 높게 나타났으며, 토마토의 초장, 지상부 및 지하부 생체중에서도 뚜렷한 효과를 보이지 않았다. 여름작형 시설재배지에서 도태랑 계열의 토마토품종 ‘도태랑솔라’를 사용하여 항바이러스 3종의 효과를 조사한 결과, 수확기에 모든 처리구에서 100.0%에 가까운 TYLCV 감염률은 나타냈으며, 수확량에도 처리간의 통계적 유의차가 인정되지는 않았다. 이와 대조적으로 Ty-1과 Ty-3a 유전자를 보유한 TYLCV에 내병성 품종인 ‘TY자이언츠’는 저항성 유묘검정의 전 조사기간 동안 바이러스 증상이 전혀 관찰되지 않았고, 식물체내 바이러스 농도도 무접종 수준이었다. 본 실험 결과 ‘TY자이언츠’ 품종은 TYLCV 발생이 만연한 지역 및 재배시기에 감수성 품종을 대체할 수 있을 것으로 생각된다. 반면, 저항성 유도물질인 살리실산, 유제놀, 키토산의 항바이러스 효과는 입증되지 않았기 때문에, 아직 시설토마토 재배현장에 적용하기는 어려울 것으로 판단된다. Recently, several in vitro studies have reported antiviral activity of agents of systemic acquired resistance against plant virus infection, but the approach has not been applied in a wide range of agricultural fields. The objective of this study was to evaluate the inhibitory effect of the exogenous application of salicylic acid (SA), chitosan (CH), or eugenol (EG) in tomato yellow leaf curl virus (TYLCV) infection of greenhouse-grown tomato plants. In vitro, the initial time of symptom was observed in TYLCV-infected plants (VP) of the resistant cultivar ‘Superdotaerang’ at 12 days post inoculation (dpi) after application of antiviral agents. At 32 dpi, the disease rate of TYLCV in the CHT+VP (0.1% chitosan and virus infected control) treated plants was 87.5%, lower than that of the other treatment. However, the virus content in the CHT+VP treated plants was higher than those of the other treatments, and SA, EG, and CH did not show significant effect on plant height or shoot and root fresh weight. Our results from summer-cultivated greenhouse-grown tomatoes show that none of the tested agents had an inhibitory activity on viral infection or yield of tomato ‘Dotaerangsola’cultivar. In contrast, all treated ‘TY Giants’ cultivars that possessed TYLCV resistance genes Ty-1 and Ty-3a did not show typical symptoms and the virus content was remarkably lower than those in the TYLCV treated plants in ‘Superdotaerang’. The results of this research indicated that the planting of resistant tomato cultivars was effective method instead of using SA, EG, and CH (known as resistance-inducing factors for control) of TYLCV in the field.

담배 잎-peroxidase와 다중벽 탄소 나노튜브를 이용한 dopamine의 정량

권효식(Hyoshik Kwon),전병숙(Byong-Suk Jeon),박용남(Yongnam Pak) 한국분석과학회 2015 분석과학 Vol.28 No.2

Effect of Superplastic Forming Exposure on Fatigue Crack Propagation Behavior of Ti-6Al-4V Alloy

Daeho Jeong,Yongnam Kwon,Masahiro Goto,Sangshik Kim 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.5

The effect of superplastic forming (SPF) exposure on the ε (strain)-N (number of cycles to failure) fatigue and fatigue crack propagation (FCP) behaviors of Ti-6Al-4V (Ti64) alloy was examined at 298 and 473 K. To simulate the thermal exposure during superplastic forming process, the mill-annealed Ti64 alloy sheet was heated in the vacuum chamber with the pre-determined temperature profile. Notable microstructural change during the SPF exposure included the shape of transformed β phase from fine and round particles in the as-received specimen to coarse angular particles in the as-exposed specimen. The effective grain size tended to increase with the exposure, enhancing the slip reversibility and the resistance to FCP. However, the crack hindering effect by fine, particle-like β phase became weak with the exposure, offseting the beneficial effect associated with the increment of effective grain size. The effect of SPF exposure on ε-N fatigue and FCP behavior of mill-annealed Ti64 alloy was therefore marginal, excluding the effect of α- case (the oxygen-enriched phase) on the surface.

다목적댐 용량재할당에 의한 용수공급량 증대방안 연구

이재응(Yi Jaeeung),권용익(Kwon Yongik),정의택(Jung Uitaek),윤용남(Yoon Yongnam) 대한토목학회 2003 대한토목학회 학술대회 Vol.2003 No.10

Mechanical and corrosion properties of rheocast and low-pressure cast A356-T6 alloy

Park, Chul,Kim, Sangshik,Kwon, Yongnam,Lee, Youngseon,Lee, Junghwan Elsevier 2005 Materials science & engineering. properties, micro Vol.391 No.1

<P><B>Abstract</B></P><P>In this study, the mechanical and corrosion behavior of rheocast and low-pressure cast A356-T6 alloy were examined and compared with each other. Tensile, impact and high-cycle fatigue tests were conducted to characterizing the mechanical behavior. For the study of general corrosion and stress corrosion cracking behavior of A356-T6 alloy, polarization, potentiostatic and in situ slow strain rate tests were performed on both products of A356-T6 alloy in a 3.5% NaCl solution. It was found that the mechanical and corrosion behaviors, as well as the microstructural features, of A356-T6 alloy were substantially affected by different processing routes. The tensile elongation and the impact energy values of A356-T6 were, e.g., greatly improved with rheocasting process. The resistance to general corrosion and stress corrosion cracking was also improved with rheocasting process. This study strongly suggests that the microstructural features, including the volume fraction and the shape of eutectic Si particles, are largely responsible for the variation in the mechanical and corrosion properties of A356-T6 alloy with different processing routes.</P>

Effect of Microstructure on High Cycle Fatigue and Fatigue Crack Propagation Behaviors of β-Annealed Ti–6Al–4V Alloy

Heesoo Choi,Sumin Kim,Yongnam Kwon,Masahiro Goto,Sangshik Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

High cycle fatigue (HCF) and fatigue crack propagation (FCP) behaviors of β-annealed Ti64 alloys having a microstructureof either α colonies or basketweave were studied. It was found that the resistance to HCF of β-annealed Ti64 alloys with amicrostructure of α colonies was similar but slightly inferior to those with a microstructure of basketweave. On the otherhand, the FCP rates of β-annealed Ti64 alloys having a microstructure of α colonies were lower than those of basketweave,particularly in low ΔK regime. Crack path observation on the surfaces of β-annealed Ti64 alloy specimens suggested thatcrystallographic crack growth prevailed in the microstructure of α colonies, leaving cleavage facets on the fracture surfaceand less fatigue damage at the tip of crack. Based on the fractographic and micrographic examination, the effects of microstructureon the HCF and FCP behaviors of β-annealed Ti64 alloys were discussed.

냉간 단조 스퍼기어의 치수정밀도 향상을 위한 연구

이영선(Youngseon Lee),권용남(Yongnam Kwon),권용철(Yongchul Kwon),이정환(Junghwan Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

The dimension of forged part is different from that of die. Therefore, a more precise die dimension needs to produce the precise part, considering the dimensional changes from forging die to final part.<br/> In this paper, both experimental and FEM analysis are performed to investigate the effect of several features including die dimension at each forging step and heat-treatment on final part accuracy in the closed-die upsetting. The dimension of forged part is checked at each stage as machined die, cold forged, and post-heat-treatment steps. The elastic characteristics and thermal influences on forging stage are analyzed numerically by the DEFORM-2D<SUP>TM</SUP>. The effect of residual stress after heat-treatment on forged part could be considered successfully by using DEFORM-HT<SUP>TM</SUP>.

Hydrogen-Affected Tensile and Fatigue Properties of Ti-6Al-4V Sheets by Superplastic Forming

Jinil Son,Junhyuk Park,Daeho Jeong,Yongnam Kwon,Masahiro Goto,Sangshik Kim 대한금속재료학회(구 대한금속학회) 2017 대한금속·재료학회지 Vol.55 No.9

Abstract: Mill-annealed Ti-6Al-4V (Ti64) sheets were formed into rectangular shaped pans with two square recesses by the superplastic forming (SPF) technique under high pressure using commercial grade argon gas. The SPF process induced a significant decrease in the tensile ductility and high cycle fatigue (HCF) resistance of the Ti64 alloy. The fractographic analysis of as-fabricated Ti64 sheets showed a hydrogen-affected layer on the surface, possibly incurred by a small amount of water vapor in the commercial grade argon gas. This hydrogen-affected layer with a depth of approximately 60 μm tended to decrease tensile ductility and the resistance to HCF, by encouraging easy crack initiation on the surface. The effect of hydrogen on the mechanical properties of the SPF processed Ti64 sheets was discussed based on fractographic and micrographic observations. (Received May 8, 2017; Accepted May 19, 2017)

Effect of Superplastic Forming Exposure on Tensile and S-N Fatigue Behavior of Ti64 Alloy

Daeho Jeong,Semi Hyun,Hyokyung Sung,Yongnam Kwon,Sangshik Kim 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.4

The effect of superplastic forming (SPF) on tensile and S (stress)-N (number of cycles to failure) fatigue properties of Ti64 alloy was examined at 298 and 473 K. For simulating the superplastic forming exposure, millannealed Ti64 alloy sheet was heated in a vacuum chamber with a pre-determined temperature profile. For some as-exposed specimens, the α-case formed on the surface during expousre was mechanically removed to understand the effect of α-case on the mechanical properties of Ti64 alloy. It was found that the presence of α-case significantly affected the tensile and the fatigue properties of Ti64 alloy at 298 and 473 K by providing an easy initiation site for both tensile and fatigue fracture. The microstructural change during the SPF exposure was marginal in affecting the S-N fatigue properties of Ti64 alloy. Different testing temperature of 298 and 473 K affected the S-N fatigue behavior of as-received and as-exposed (α-case removed) Ti64 specimens, but not that of as-exposed specimen.

Effect of Cooling Rate on SCC Susceptibility of β-Processed Ti–6Al–4V Alloy in 0.6M NaCl Solution

Soojin Ahn,Jiho Park,Daeho Jeong,Hyokyung Sung,Yongnam Kwon,Sangshik Kim 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.2

The effects of cooling rate on the stress corrosion cracking (SCC) susceptibility of β-processed Ti–6Al–4V (Ti64) alloy,including BA/S specimen with furnace cooling and BQ/S specimen with water quenching, were investigated in 0.6M NaClsolution under various applied potentials using a slow strain rate test technique. It was found that the SCC susceptibility ofβ-processed Ti64 alloy in aqueous NaCl solution decreased with fast cooling rate, which was particularly substantial underan anodic applied potential. The micrographic and fractographic analyses suggested that the enhancement with fast coolingrate was related to the random orientation of acicular α platelets in BQ/S specimen. Based on the experimental results, theeffect of cooling rate on the SCC behavior of β-processed Ti64 alloy in aqueous NaCl solution was discussed.