• 한국산림과학회지
• /
• 제83권4호
• /
• pp.450-459
• /
• 1994

본(本) 연구(硏究)는 최근(最近) 잣나무넓적잎벌의 피해(被害)가 급진적(急進的)으로 확산(擴散)되고있는 경기도(京畿道) 가평군(加平郡)과 강원도(江原道) 홍천군(洪川郡)의 2개(個) 피해임분(被害林分)에 대(對)한 피해해석(被害解析)을 통(通)하여 경제적(經濟的) 피해허용수준(被害許容水準)을 결정(決定)하고 해충(害蟲) 관리(管理)를 위한 종합적(綜合的) 체계수립(體系樹立)의 기초자료(基礎資料)를 얻고자 1984년(年)부터 4개년간(個年間) 실시(實施)하여 다음과 같은 결과(結果)를 얻었다. 1. 임목(林木)의 피해양상(被害樣狀)은 수관(樹冠) 하부(下部) 보다는 상부(上部)에서 심(甚)하게 나타나며 지상부(地上部) 건물질량(乾物質量)의 수직(垂直) 분포(分布)는 건전목(健全木)의 C형(型) 분포(分布)에서 피해(被害)가 증가(增加)할수록 L형(型) 분포화(分布化) 되었다. 2. 잣나무넓적잎벌 피해(被害)로 인(因)한 엽손실(葉損失)은 수고생장(樹高生長)과 직경생장(直徑生長)의 저해(沮害)를 동시(同時)에 일으키며 생장저해(生長沮害)는 엽손실율(葉損失率) 50% 수준(水準)에서 부터 일어나며 이때의 생장감소율(生長減少率)은 10% 내외(內外)였다. 3. 잣나무넓적잎벌 피해(被害)로 인(因)한 직경생장(直徑生長) 감소(減少)는 수관(樹冠) 상부(上部)에서 현저(顯著)하며 하부(下部)로 갈수록 낮은 감소율(減少率)을 보였다. 4. 엽손실(葉損失)에 의한 재적생장(材積生長) 손실(損失)은 피해발생(被害發生) 3년(年) 후(後)인 엽손실율(葉損失率) 50% 범위(範圍)에서 나타났으며 70% 및 90% 피해목(被害木)의 총재적(總材積) 손실율(損失率)은 건전목(健全木)에 비(比)하여 각각(各各) 9%와 20%였다.

• 한국육종학회지
• /
• 제41권4호
• /
• pp.488-495
• /
• 2009

자연발생포장 및 톱다리개미허리노린재 접종구에서 협 피해 및 수량 감소가 적었던 품종은 풍산나물콩, 소백나물콩, 두유콩, 신팔달콩 2호로 다른 품종에 비해 노린재 선호도가 낮은 품종으로 생각되었고, 명주나물콩, 만리콩, 황금콩은 피해가 심한 품종으로 분류되었다. 콩 품종간 톱다리개미허리노린재 선호성으로 모용색이 회백색인 품종군의 피해율이 13.0%인데 비해 갈색모용의 품종군은 8.2%로 피해율이 낮았으며, 제색도 황색에 비해 담갈색>갈색>회갈색 순으로 제색이 짙은 품종군에서 피해율이 낮은 경향이었고, 협색도 담갈색에 비해 갈색에서 피해가 적어, 모용색, 협색, 제색이 노린재 저항성에 관여하는 형질로 생각되었다. 품종별 R6(입비대성기) 단계의 협 길이가 짧은 품종군이 긴 품종군에 비해 피해율이 낮아, 협의 길이도 노린재 저항성에 관여하는 형질로 생각되었다.

• 대한의생명과학회지
• /
• 제22권1호
• /
• pp.18-23
• /
• 2016

Ultraviolet (UV) irradiation induces cellular damage. A variety of cellular responses for repairing cellular damage including DNA damage occur after UV irradiation. During the repair processes, expression and activation of various molecules are regulated depending on the types of cellular damage. Parkin is an E3 ligase and act as a tumor suppressor. Recently, it has been reported that Parkin is involved in the DNA repair process. In the current study, we investigated whether UVB irradiation influences expression of Parkin. Parkin expression transiently decreased after UVB irradiation both at the mRNA and protein levels, but returned to normal levels thereafter. Taken together with cell viability data, Parkin expression is down-regulated during UVB-induced suppression of cell growth and is increased again in accordance with recovery of UVB-induced cell growth inhibition. However, Parkin overexpression or knockdown did not influence UVB-induced cell growth inhibition and recovery. We propose that Parkin could be a useful molecular marker for evaluating conditions of cells after UVB irradiation.

• Smart Structures and Systems
• /
• 제2권2호
• /
• pp.101-113
• /
• 2006

Structural health monitoring results obtained with the electro-mechanical (E/M) impedance techniqueand Lamb wave transmission methods during fatigue crack propagation of an Arcan specimen instrumented with piezoelectric wafer active sensors (PWAS) are presented. The specimen was subjected in mixed-mode fatigue loading and a crack was propagated in stages. At each stage, an image of the crack and the location of the crack tip were recorded and the PWAS readings were taken. Hence, the crack-growth in the specimen could be correlated with the PWAS readings. The E/M impedance signature was recorded in the 100 - 500 kHz frequency range. The Lamb-wave transmission method used the pitch-catch approach with a 3-count sine tone burst of 474 kHz transmitted and received between various PWAS pairs. Fatigue loading was applied to initiate and propagate the crack damage of controlled magnitude. As damage progressed, the E/M impedance signatures and the waveforms received by receivers were recorded at predetermined intervals and compared. Data analysis indicated that both the E/M impedance signatures and the Lamb-wave transmission signatures are modified by the crack progression. Damage index values were observed to increase as the crack damage increases. These experiments demonstrated that the use of PWAS in conjunction with the E/M impedance and the Lamb-wave transmission is a potentially powerful tool for crack damage detection and monitoring in structural elements.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1998년도 춘계학술대회논문집
• /
• pp.220-223
• /
• 1998

The failure of die often occurs as a result of growth of microcracks - referred as a brittle damage. In this study, an analysis of brittle damage evolution cupled with elastic finite element analysis of die deformation is presented. A local transformation from the tractions of a workpiece mesh to those of a die mesh is developed. The brittle damage is defined as a vector considering the shape of common microcracks in the brittle metals and the damage function suggested by Krajcinovic is utillized. Applications of the proposed model to modeling damage evolution in the extrusion die and forging die are given and the characteristics of brittle damage evolution in die are in detail examined.

• Structural Engineering and Mechanics
• /
• 제10권2호
• /
• pp.139-156
• /
• 2000

This paper concerns the development of a computational model for the damage evolution of engineering materials under dynamic loading. Two models describing the anisotropic damage evolution of a material are presented; the first is based on a power function of the effective equivalent stress and the second on the damage strain energy release rate. The methods for computing the damage accumulated in structural components and their implementation in a finite element programme are presented together with some numerical results. The dynamic response of a damaged structural component and the dynamic behaviour of a damaged material have been studied numerically. This study shows that the frequency spectrum of a damaged structure is down-shifted, while the damping ratio of damaged materials becomes higher, the amplitude of the response significantly increases and the resonance ensuing from the damage growth still occurs in a damaged structure.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 춘계학술대회논문집
• /
• pp.120-126
• /
• 2003

Finite element analysis model is suggested for analysis of milli-forming process, which forms milli-size products. Since the size of workpiece in a milli-forming process ranges from a few hundred micrometers to a few millimeters, microstructural changes such as the growth of micro-voids and the development of preferred orientation in a grain become crucial factors for the success of milli-forming. This analysis model incorporates anisotropy from deformation torture and deterioration of mechanical properties due to the growth of micro-voids. Applications of the proposed modeling to milli-forming are given and the results are carefully examined to understand the deformation characteristics such as texture development and damage evolution during extrusion/drawing of a milli-bar.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1994년도 춘계학술대회 논문집
• /
• pp.71-79
• /
• 1994

Strip drawing of strain-hardening, viscoplastic materials with damage is analyzed by a rigid plastic finite element method. A process model is formulated using two state variables, one for strain hardening from slip dominated plastic distortion and the other for damage from growth of microvoids. Application of the model to steady state drawing is given via implementation in a consistent penalty finite element formulation. The predicted density changes as a result of void growth are compared to those from experiments reported in the literature. The effects of drawing conditions such as drawing speed and die angle on the mechanical property changes are studied.

• 한국공작기계학회논문집
• /
• 제10권4호
• /
• pp.14-21
• /
• 2001

To estimate crack growth rate and cycle ratio uniquely, many investigators have developed various kinds of mechanical parameters and theories. But, thes have produced local solution space through single parameter. Neural Networks can perform patten classification using several input and output parameters. Fatigue damage model by neural networks was used to recognize the relation between da/dN/N/N(sub)f, and half-value breadth ratio B/Bo, fractal dimension D(sub)f, and fracture mechanical parameters in 2024-T3 aluminium alloy. Learned neural networks has ability to predict both crack growth rate da/dN and cycly ratio /N/N(sub)f within engineering estimated mean error(5%).

• The Korean Journal of Ecology
• /
• 제21권2호
• /
• pp.125-131
• /
• 1998

Histological damage and growth inhibition of Pinus densiflora were analysed in different areas around the Metropolitan area of Seoul urban (heavily polluted), suburban (lightly polluted), and rural(unpolluted) areas. Soil properties of each area were also investigated. Contact angles of water droplet on needle leaves growing in polluted areas were lower than that in unpolluted area. Transpiration rates of needle leaves growing in polluted areas were more rapid than that in unpolluted area. These results represented that needle leaves growing in polluted areas were more susceptible to water deficit than that growing in unpolluted area was. Growths of annual ring of Pinus densiflora growing in polluted areas were lower than that in unpolluted area. On the other hand, soil pH in polluted areas was lower than that in unpolluted area. That is, the former was more acidified than that the latter was. Ca and Mg contents in polluted areas were lower than that in unpolluted area, while Al contents in polluted areas were higher than that in unpolluted area. These soil properties revealed that the effects of acid precipitates in urban and suburban areas were severer than that in rural area.