• 한국기후변화학회지
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• 제9권2호
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• pp.133-142
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• 2018

Climate change will affect not only the crop productivity but also the pattern of rice disease epidemics in Korea. Impact assessments for the climate change are conducted using various climate change scenarios from many global climate models (GCM), such as a scenario from a best GCM or scenarios from multiple GCMs, or a combination of both. Here, we evaluated the feasibility of using a climate change scenario from the best GCM for the impact assessment on the potential epidemics of a rice leaf blast disease in Korea, in comparison to a multi?model ensemble (MME) scenario from multiple GCMs. For this, this study involves analyses of disease simulation using an epidemiological model, EPIRICE?LB, which was validated for Korean rice paddy fields. We then assessed likely changes in disease epidemics using the best GCM selected for individual agro?climatic zones and MME scenarios constructed by running 11 GCMs. As a result, the simulated incidence of leaf blast epidemics gradually decreased over the future periods both from the best GCM and MME. The results from this study emphasized that the best GCM selection approach resulted in comparable performance to the MME approach for the climate change impact assessment on rice leaf blast epidemic in Korea.

• Structural Engineering and Mechanics
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• 제65권5호
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• pp.587-600
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• 2018

Infill panel is the first element of a building subjected to blast loading activating its out-of-plane behavior. If the infill panel does not have enough ductility against the loading, it breaks and gets damaged before load transfer and energy dissipation. As steel infill panel has appropriate ductility before fracture, it can be used as an alternative to typical infill panels under blast loading. Also, it plays a pivotal role in maintaining sensitive main parts against blast loading. Concerning enough ductility of the infill panel out-of-plane behavior, the impact force enters the horizontal diaphragm and is distributed among the lateral elements. This article investigates the behavior of steel infill panels with different thicknesses and stiffeners. In order to precisely study steel infill panels, different ranges of blast loading are used and maximum displacement of steel infill under such various blast loading is studied. In this research, finite element analyses including geometric and material nonlinearities are used for optimization of the steel plate thickness and stiffener arrangement to obtain more efficient design for its better out-of-plane behavior. The results indicate that this type of infill with out-of-plane behavior shows a proper ductility especially in severe blast loadings. In the blasts with high intensity, maximum displacement of infill is more sensitive to change in the thickness of plate rather the change in number of stiffeners such that increasing the number of stiffeners and the plate thickness of infill panel would decrease energy dissipation by 20 and 77% respectively. The ductile behavior of steel infill panels shows that using infill panels with less thickness has more effect on energy dissipation. According to this study, the infill panel with 5 mm thickness works better if the criterion of steel infill panel design is the reduction of transmitted impulse to main structure. For example in steel infill panels with 5 stiffeners and blast loading with the reflected pressure of 375 kPa and duration of 50 milliseconds, the transmitted impulse has decreased from 41206 N.Sec in 20 mm infill to 37898 N.Sec in 5 mm infill panel.

• 한국군사과학기술학회지
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• 제13권5호
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• pp.933-940
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• 2010

A numerical analysis for the space frame structure under ballistic and blast loads was performed using LS-DYNA, a commercial code. The space frame structure was developed to be adapted to the ground vehicle in the future and it was designed to build with Al7039 frames and lightweight multi-layered panels for the purpose of weight reduction and shock mitigation. The analyses have done for side impacts by a cylindrical projectile and Comp. C-4 explosive representing major threats to the vehicle. The deformed shape of the panel section and stresses as well as accelerations of the frames calculated from LS-DYNA were compared to the test results to validate the analysis model. The internal energies for panels and frames from LS-DYNA were also compared to each other to discern their role in absorbing the ballistic and blast impact.

• 대한조선학회논문집
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• 제57권2호
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• pp.70-79
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• 2020

The offshore installation units may be subjected to various accidental loads such as collision from supply vessels, impact from dropped objects, blast load from gas explosion and thermal load from fire. This paper deals with the design and strength evaluation method of the stiffened plate structures in response to a blast load caused by a gas explosion accident. It is a comprehensive review of various items used in actual project such as the size and type of the explosive loads, general design procedure/concept and analysis method. The structural analyses using simple analysis methods based on SDOF model and nonlinear finite element analysis are applied to the particular FPSO project. Also validation studies on the design guidance given by simple analysis method based on SDOF model have also considered several items such as backpressure effects, material behavior and duration time of the overpressure. A good correlation between the prediction made by simple analysis method based on SDOF model and nonlinear finite element analysis can be generally obtained up to the elastic limit.

• Interaction and multiscale mechanics
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• 제6권2호
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• pp.173-195
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• 2013

Meshfree methods are known to have the capability to overcome the strict regularization requirements and numerical instabilities that encumber the finite element method (FEM) in large deformation problems. They are also more naturally suited for problems involving material perforation and fragmentation. To take advantage of the high efficiency of FEM and high accuracy of meshfree methods, a coupled finite element (FE) and reproducing kernel (RK, one of the meshfree approximations) formulation is described in this paper. The coupling of FE and RK approximation is implemented in an evolutionary fashion, where the extent and location of the evolution is dependent on a triggering criteria provided by the material constitutive laws. To enhance computational efficiency, Gauss quadrature is applied to integrate both FE and RK domains so that no state variable transfer is required when mesh conversion is performed. To control the hourglassing that might occur with 1-point integrated hexahedral grids, viscous type hourglass control is implemented. Meanwhile, the FEM version of the K&C concrete (KCC) model was modified to make it applicable in both FE and RK formulations. Results using this code and the KCC model are shown for the modeling of concrete responses under quasi-static, blast and impact loadings. These analyses demonstrate that fragmentation phenomena of the sort commonly observed under blast and impact loadings of concrete structures was able to be realistically captured by the coupled formulation.

• 한국건설순환자원학회논문집
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• 제10권4호
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• pp.402-410
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• 2022

본 연구에서는 초고성능 강섬유 보강 콘크리트(UHPC)의 재료특성을 고려하기 위해 해석프로그램 LS-DYNA에 있는 CSC모델의 입력상수값 보정기법을 제안하였다. 1축 압축, 3축 압축, 압력-체적 변형률 곡선, 동적증가계수 등 이전 재료단위 실험 연구결과를 기반으로 입력상수값 보정을 수행하였다. 단일요소 해석결과를 실험결과와 비교하여 보정기법의 검증을 수행하였다. 또한, 유한요소모델을 구축하고 충격 및 폭발해석을 수행하여 UHPC 구조물 해석 수행 시 보정된 CSC 모델의 적용 가능성을 확인해보았다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2018년도 춘계학술대회 및 임시총회
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• pp.19-19
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• 2018

Fungal pathogens have huge impact on health and economic wellbeing of human by causing life-threatening mycoses in immune-compromised patients or by destroying crop plants. A key determinant of fungal pathogenesis is their ability to undergo developmental change in response to host or environmental factors. Genetic pathways that regulate such morphological transitions and adaptation are therefore extensively studied during the last few decades. Given that epigenetic as well as genetic components play pivotal roles in development of plants and mammals, contribution of microbial epigenetic counterparts to this morphogenetic process is intriguing yet nearly unappreciated question to date. To bridge this gap in our knowledge, we set out to investigate histone modifications among epigenetic mechanisms that possibly regulate fungal adaptation and processes involved in pathogenesis of a model plant pathogenic fungus, Magnaporthe oryzae. For functional and comparative analysis of histone modifications, a web-based database (dbHiMo) was constructed first to archive and analyze histone modifying enzymes from eukaryotic species whose genome sequences are available. Based on the database entries, we carried out functional analysis of genes encoding histone modifying enzymes. Here I provide examples of such analyses that show how histone acetylation and methylation is implicated in regulating important aspects of fungal pathogenesis. Current analysis of histone modifying enzymes is followed by ChIP-seq and RNA-seq experiments to pinpoint the genes that are controlled by particular histone modifications. We anticipate that our work will provide not only the significant advances in our understanding of epigenetic mechanisms operating in microbial eukaryotes but also basis to expand our perspective on regulation of development in fungal pathogens.

• 한국지반신소재학회논문집
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• 제22권3호
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• pp.71-86
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• 2023

본 연구에서는 암반 발파 시 발생하는 사면 재해를 방지하기위해 지중 관입형 변위센서를 이용한 암반 발파 시험을 수행하고 3차원 유한요소 수치해석을 통해 지중 관입형 변위센서의 적용성 검증 및 암반 발파 시 진동속도에 영향을 미치는 매개변수에 대해 고찰하였다. 암반 발파 시험 결과 지중 관입형 변위센서는 암반사면 거동 계측에 적용 가능한 시스템임을 확인하였으며, 수치해석 결과 암반 발파 시 진동속도에 가장 큰 영향을 미치는 매개변수는 단위중량인 것으로 분석되었다. 또한, 발파원과 멀어질수록 진동속도는 급격하게 줄어들고 발파원과 가까울수록 동탄성계수와 단위중량의 차이에 따라 최대 진동속도 차이는 크게 발생하며 내부마찰각과 점착력 변화에 따른 영향은 거의 없는 것으로 판단된다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 추계학술대회 및 정기총회
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• pp.11-11
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• 2014

Fungal pathogens have huge impact on health and economic wellbeing of human by causing life-threatening mycoses in immune-compromised patients or by destroying crop plants. A key determinant of fungal pathogenesis is their ability to undergo developmental change in response to host or environmental factors. Genetic pathways that regulate such morphological transitions and adaptation are therefore extensively studied during the last few decades. Given that epigenetic as well as genetic components play pivotal roles in development of plants and mammals, contribution of microbial epigenetic counterparts to this morphogenetic process is intriguing yet nearly unappreciated question to date. To bridge this gap in our knowledge, we set out to investigate histone modifications among epigenetic mechanisms that possibly regulate fungal adaptation and processes involved in pathogenesis of a model plant pathogenic fungus, Magnaporthe oryzae. M. oryzae is a causal agent of rice blast disease, which destroys 10 to 30% of the rice crop annually. Since the rice is the staple food for more than half of human population, the disease is a major threat to global food security. In addition to the socioeconomic impact of the disease it causes, the fungus is genetically tractable and can undergo well-defined morphological transitions including asexual spore production and appressorium (a specialized infection structure) formation in vitro, making it a model to study fungal development and pathogenicity. For functional and comparative analysis of histone modifications, a web-based database (dbHiMo) was constructed to archive and analyze histone modifying enzymes from eukaryotic species whose genome sequences are available. Histone modifying enzymes were identified applying a search pipeline built upon profile hidden Markov model (HMM) to proteomes. The database incorporates 22,169 histone-modifying enzymes identified from 342 species including 214 fungal, 33 plants, and 77 metazoan species. The dbHiMo provides users with web-based personalized data browsing and analysis tools, supporting comparative and evolutionary genomics. Based on the database entries, functional analysis of genes encoding histone acetyltransferases and histone demethylases is under way. Here I provide examples of such analyses that show how histone acetylation and methylation is implicated in regulating important aspects of fungal pathogenesis. Current analysis of histone modifying enzymes will be followed by ChIP-Seq and RNA-seq experiments to pinpoint the genes that are controlled by particular histone modifications. We anticipate that our work will provide not only the significant advances in our understanding of epigenetic mechanisms operating in microbial eukaryotes but also basis to expand our perspective on regulation of development in fungal pathogens.

• 한국식품영양과학회지
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• 제45권2호
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• pp.230-238
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• 2016

본 연구는 공기를 이용한 송풍식과 초저온 에탄올을 이용한 침지식 냉동방법 및 저온 송풍식과 유수식 해동방법을 조합하고 저장 중 냉동-해동 반복에 따른 한우 설도의 품질에 미치는 영향을 살펴보았다. 송풍식 냉동은 냉동이 완료되는데 약 800분이 소요됐지만 침지식 냉동방법은 8분에 한우 시료를 급속하게 동결시켰다. 한편 송풍식 해동은 한우 시료가 해동이 완료되는 데 약 350분 소요되었지만, 유수식 해동은 약 70분으로 해동시간이 280분 단축되었다. 송풍식 냉동시료는 송풍식 해동과 유수식 해동에 의해 4.05와 4.54%의 드립 감량이 발생했지만 침지식 냉동시료는 송풍식 해동과 유수식 해동에 의한 드립 감량이 2.59와 2.09%로 냉동방법에 따라 유의적(P<0.05) 차이를 보였다. 냉동과 해동 처리로 한우 설도의 보수력은 64.40~66.05%로 감소하였지만 냉동과 해동 조건에 따른 차이가 거의 나타나지 않았다. 송풍식 냉동-송풍식 해동과 침지식 냉동-송풍식 해동 처리구의 TBARS 값은 각각 1.12와 1.18 mg MDA/kg으로 송풍식 냉동-유수식 해동 처리구와 침지식 냉동-유수식 해동 처리구의 0.82와 0.77 mg MDA/kg과 비교하여 높은 값을 나타냈다. 휘발성 염기질소 함량은 TBARS 결과와 유사하게 송풍식 해동 처리구가 유수식 해동 처리구보다 높은 값을 보였다. 냉동과 해동이 조합된 모든 처리구의 총 호기성 세균수는 4.45~4.67 log CFU/g으로 냉동 및 해동 방법에 따라 유의적(P<0.05) 차이는 나타나지 않았다. 송풍식 냉동된 한우육은 해동 후 근섬유 조직이 불균일하게 찢어지거나 근섬유 간의 간격이 더 넓어졌지만, 침지식 냉동된 한우육은 송풍식 해동 또는 유수식 해동 후 조직의 구조적 손상이나 변화가 훨씬 적은 것으로 나타났다. 한편 저장 중 냉동-해동의 3반복 처리로 드립 감량 증가, 보수력 감소, TBARS 값 및 휘발성 염기질소 함량 증가, 근섬유 조직 손상 등 품질 저하가 발생하였다. 앞으로 고품질 냉동 한우육의 생산 및 유통을 위한 부위별, 포장단위별 중량에 따른 냉동 및 해동 방법에 따른 이화학적 품질에 미치는 영향, 관능평가 등의 추가 연구가 필요할 것으로 사료된다.