• Earthquakes and Structures
• /
• 제18권5호
• /
• pp.527-542
• /
• 2020

In traditional eccentrically braced steel frames, damages and plastic deformations are limited to the links and the main structure members are required tremendous sizes to ensure elasticity with no damage based on the force-based seismic design method, this limits the practical application of the structure. The high strength steel frames with eccentric braces refer to Q345 (the nominal yield strength is 345 MPa) steel used for links, and Q460 steel utilized for columns and beams in the eccentrically brace steel frames, the application of high strength steels not only brings out better economy and higher strength, but also wider application prospects in seismic fortification zone. Here, the structures with four type eccentric braces are chosen, including K-type, Y-type, D-type and V-type. These four types EBFs have various performances, such as stiffness, bearing capacity, ductility and failure mode. To evaluate the seismic behavior of the high strength steel frames with variable eccentric braces within the similar performance objectives, four types EBFs with 4-storey, 8-storey, 12-storey and 16-storey were designed by performance-based seismic design method. The nonlinear static behavior by pushover analysis and dynamic performance by time history analysis in the SAP2000 software was applied. A total of 11 ground motion records are adopted in the time history analysis. Ground motions representing three seismic hazards: first, elastic behavior in low earthquake hazard level for immediate occupancy, second, inelastic behavior of links in moderate earthquake hazard level for rapid repair, and third, inelastic behavior of the whole structure in very high earthquake hazard level for collapse prevention. The analyses results indicated that all structures have similar failure mode and seismic performance.

• 농업과학연구
• /
• 제43권2호
• /
• pp.194-204
• /
• 2016

The pear psylla, Cacopsylla pyricola, is a very small sap-feeding insect of many commercial pear varieties that could be considered the most serious insect pest of pear. Detailed information on plant penetration activities of the pear psylla is essential to study its feeding behavior used to evaluate resistant traits to chemical control. The application of the electrical penetration graph technique (EPG) could provide a relevant insight into the nature of this resistance. EPG waveforms of C. pyricola were characterized on the basis of amplitude, frequency, voltage level, and electrical origin. Feeding behaviors of C. pyricola were recorded and analyzed by EPG analysis. During EPG monitoring, waveform PA occurred at the start of stylet penetration of pear leaf epidermal cell. Waveform PB followed, in which stylet secreted saliva was observed. Waveforms PC1 and PC2 involved penetrating and sucking behaviors in parenchyma cells and vascular parenchyma, respectively. In addition, waveform PC1 represented salivation into bundle sheath cells and ingestion from parenchyma. Otherwise, behaviors of salivation into phloem and ingestion from phloem produced waveforms PE1 and PE2, respectively. On the other hand, ingestion from xylem tissues showed waveform PG. Among the feeding patterns of C. pyricola described above, phloem feeding patterns occurred most frequently, followed by xylem feeding and parenchyma penetration patterns in descending order.

• 농업과학연구
• /
• 제38권3호
• /
• pp.405-411
• /
• 2011

In this study, we evaluated the changes of fruit quality indices during fruit development and ripening in Korean new pear cultivar 'Wonhwang' and 'Whasan' to determine appropriate harvest time and to enhance the marketability. The fruit of each cultivar harvested from 100 days after full bloom (DAFB) to 135 and 150 DAFB in 'Wonhwang' and 'Whasan', respectively. The fruit growth of both cultivars showed a typical single sigmoidal pattern. Flesh firmness of two cultivars decreased continuously with fruit development and ripening, reaching a final level of about 2.6 kgF at harvest stage. The starch content of fruit sap was much higher in the fruits of early development stage than the later stage of fruit ripening. In 'Wonhwang' pears, the starch level decreased coincide with fruit ripening (130 DAFB), while that of 'Whasan' decreased from very early stage of fruit development (120 DAFB), 30 days before full ripe. 'Whasan' pear showed much lower acidity level of about 0.13% during fruit development and ripening period compared with that of 'Wonhwang'. Therefore, the ratio of soluble solids to total acidity (TSS/acid) increased gradually with fruit development and ripening, reaching a final level of 80 and 98 in 'Wonhwang' and 'Whasan', respectively. There were no climateric rise of fruit respiration during fruit ripening periods in two oriental pear cultivar. The changes of skin color difference including hunter vale $a^*$ which means loss of green color occurred only after onset of ripening in two cultivars.

• 한국응용곤충학회지
• /
• 제32권2호
• /
• pp.208-217
• /
• 1993

벼멸구의 식이행동을 전기적인 측정 방법을 통하여 관찰하였으며 이들을 각각의 특성에 따라 분류하였고, 그결과 type P, S, SB, O, X, Ph 등 6가지로 나누어 볼 수 있었다. Type P는 벼멸구가 식물에체 처음 접근하여 기주를 탐색할 때 볼 수 있었으며, 구침을 조직내에 찔어 넣거나조직내에서 이동할 때에는 type S를 관찰 할 수 있었다. 또한 매우 규칙적인 S패턴은 체관부에 구침을 찔어 넣을때만 볼 수 있어 type SB로 따로이 분류하였다. X와 Ph패턴은 각각 물관부와 채관부에서 흡즙할 때 나타나는 것을 확인하였으며, type O는 기타 다른 조직내에 구침이 있을 때 이러한 전기적 패턴을 보여 주었다. 이러한 각각의 전기적 패턴을 확인하기 위하여 원하는 패턴이 나타날 때에 식흔이 있는 벼의 조직을 잘라서 현미경으로 관찰하였으며, 각각의 타입별로 벼멸구 배설물을 측정하였다.

• The Plant Pathology Journal
• /
• 제22권2호
• /
• pp.125-130
• /
• 2006

An isolate of Peanut stunt virus (PSV) isolated from black locust tree (Robinia pseudo-acacia L.) showing severe mosaic and malformation symptoms, was designated as PSV-Rp. PSV-Rp was characterized by the tests of host range, physical properties, RNA and coat protein composition and RT-PCR analysis. Nucleotide sequences of the cucumoviruses CP genes were also used for identification and differentiation of PSV-Rp. Six plant species were used in the host range test of PSV-Rp. PSV-Rp could be differentiated from each Cucumovirus strain used as a control by symptoms of the plants. The physical properties of PSV-Rp virus were TIP $65^{\circ}C$, DEP $10^{-3}$, and LIP $2{\sim}3$ days. In dsRNA analysis, PSV-Rp consisted of four dsRNAs, but satellite RNA was not detected. Analysis of the coat proteins by SDS-PAGE showed one major protein band of about 31 kDa. RT-PCR using a part of Cucumovirus RNA3 specific primer amplified ${\sim}950bp$ DNA fragments from the crude sap of virus-infected black locust leaves. RFLP analysis of the RT-PCR product could differential PSV-RP from CMV The nucleotide sequence identity between the PSV-Rp CP and the TAV-P CP genes and the PS-V-RP CP and CMV-Y CP genes were 61.6% and 40.5%, respectively. On the other hand, the nucleotide sequence identity of the PSV-Rp CP gene was $70.9%{\sim}73.4%$ in comparison with those of PSV subgroup I (PSV-ER and PSV-J) and 67.3% with that of PSV subgroup II(PSV-W). Especially, the nucleotide sequence identity of PSV-Rp CP gene and that of PSV-Mi that was proposed recently as the type member of a novel PSV subgroup III was 92.4%.

• 한국식물병리학회지
• /
• 제3권3호
• /
• pp.203-209
• /
• 1987

Pseudomonas solanacearum의 병원성균주 및 비병원성균주를 담배의 뿌리에 접종하여 그 잎과 줄기, 뿌리에서 P. solanacearum과 Erwinia carotovora subsp. carotovora, Escherichia coli에 대한 항균물질을 분리하였다. 담배즙액을 TLC plate에 발전시킨 결과 비병원성균주에 접종된 담배에서는 $R_f$ 0.6 부근에서, 병운성균주에 접종된 담배에서는 $R_f$ 0.9 부근에서 각각 항균물질을 분리할 수 있았다. 그러나 고압살균된 담배즙액배지에 병원성균주 및 비병원성균주를 3일간 배양한 배양여액에서는 항균물질의 생성이 인정되지 않았다. 비병원성균주 및 병원성균주에 접종된 담배잎에서는 무처리 담배에 비하여 peroxidase와 polyph-enoloxidase의 활성이 높았으나, 그 줄기와 뿌리에서는 효소활성의 차이가 없었다. 비병원성균주와 병원성균주로 처리된 담배 사이, 감수성품종인 BY4와 저항성품종 NC82 사이에도 두 효소의 활성과 동위효소형태의 차이가 없었다.

• 식물병연구
• /
• 제24권1호
• /
• pp.81-85
• /
• 2018

2016년 충북 충주에서 모자이크 병징을 보이는 초석잠을 채집하였다. 담배와 명아주에 즙액접종을 실시한 결과 담배에서 접종엽에 괴사반점이 나타나고 명아주 2종에서 상엽에 퇴록반점을 동반한 모자이크 병징이 관찰되었다. 기주반응과 결과를 통해 여러 바이러스의 복합감염을 추정할 수 있었고, 추정되는 바이러스의 확인을 위해 속특이 및 종특이 프라이머를 이용하여 RT-PCR을 수행하여 3종의 바이러스(AMV, CMV, TMV)를 검정하였다. 본 연구는 국내 초석잠에서 3종의 바이러스 감염을 확인하였고 CMV의 감염에 대한 첫 보고이다.

• 대한교통학회지
• /
• 제22권3호
• /
• pp.95-105
• /
• 2004

교통기본도(Fundamental Diagram)는 교통류와 관련된 다양한 연구에서 중요한 요소로 생각되어져 왔다. 지금까지 다양한 형태의 교통기본도가 제시되었고 실제 데이터를 가장 잘 설명하는 교통기본도의 형태에 대해 많은 논의가 이루어졌지만, 서로 다른 형태의 교통기본도를 결정하는 원인에 대한 분석이 충분히 이루어지지 않고 있다. 본 연구는 서로 다른 지점과 교통조건에서 운전자의 행태차이를 이해하는데 중요한 파라메타로서 차간시간(time gap)을 소개하였고, 차간시간과 교통기본도의 형태와의 연관성을 분석하였다. 개별차량 검지기 자료를 토대로, 차간시간은 확률분포를 따르고 평균값은 지점에 따라 변화하는 것과 다른 통행속도에서 다른 차간시간을 보이는 것으로 분석되었다. 또한, 차간시간-속도 분포도의 3가지 형태들이 확인되었고 이것들은 교통류율-밀도 교통기본도로 전환되면 기존의 Greenberg, 역 ${\lambda}$, 전도된 V형태의 교통기본도와 일치하였다. 본 연구는 미시적 교통변수인 차간시간을 이용하여 교통기본도의 특징을 해석하였고, 운전자들의 행태에 관한 특성을 교통조건과 도로의 기하구조에 따라 설명하였다.

• Earthquakes and Structures
• /
• 제4권5호
• /
• pp.451-470
• /
• 2013

It generally accepted that most building structures shall exhibit a nonlinear response when subjected to medium-high intensity earthquakes. It is currently known, however, that this phenomenon is not properly modelled in the majority of cases, especially at the design stage, where only simple linear methods have effectively been used. Recently, as a result of the exponential progress of computational tools, nonlinear modelling and analysis have gradually been brought to a more promising level. A wide range of modelling alternatives developed over the years is hence at the designer's disposal for the seismic design and assessment of engineering structures. The objective of the study presented herein is to test some of these models in an existing structure, and observe their performance in nonlinear static and dynamic analyses. This evaluation is done by the use of two of a known range of advanced computer programs: SAP2000 and SeismoStruct. The different models will focus on the element flexural mechanism with both lumped and distributed plasticity element models. In order to appraise the reliability and feasibility of each alternative, the programs capabilities and the amount of labour and time required for modelling and performing the analyses are also discussed. The results obtained show the difficulties that may be met, not only in performing nonlinear analyses, but also on their dependency on both the chosen nonlinear structural models and the adopted computer programs. It is then suggested that these procedures should only be used by experienced designers, provided that they are aware of these difficulties and with a critical stance towards the result of the analyses.

• Structural Engineering and Mechanics
• /
• 제64권5호
• /
• pp.543-555
• /
• 2017

The non-linear behaviour of integral infilled frames (in which the infill and the frame are bonded together with help of various interface materials) is studied both experimentally and numerically. The experiments were carried out on one-sixth scale two-bay and three-storey reinforced concrete frames with and without infill against static cyclic loading. Three interface materials - cement mortar, cork and foam have been used in between the infill and the frame. The infill, interface and the frame are bonded together is called integral frame. The linear and non-linear behaviors of two dimensional bare frame and integral infilled frame have been studied numerically using the commercial finite element software SAP 2000. Linear finite element analysis has been carried out to quantify the effect of various interface materials on the infilled frames with various combinations of 21 cases and the results compared. The modified configuration that used all three interface materials offered better resistance above others. Therefore, the experiments were limited to this modified infilled frame case configuration, in addition to conventional (A1-integral infilled frame with cement mortar as interface) and bare frame (A0-No infill). The results have been compared with the numerical results done initially. It is found that stiffness of bare frame increased by infilling and the strength of modified frame increased by 20% compare to bare frame. The ductility ratio of modified infilled frame was 42% more than that of the conventional infilled frame. In general, the numerical result was found to be in good agreement with experimental results for initial crack load, ultimate load and deformed pattern of infill.