• 한국생물환경조절학회:학술대회논문집
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• 한국생물환경조절학회 2004년도 추계학술대회 논문집
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• pp.139-143
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• 2004

To evaluate the biological and physiological response of Picea koraiensis Nakai to elevated $CO_2$ and nitrogen.3-year old seedlings were planted in an ambient and 700 ppm $CO_2$ at low (2mM $NH_4NO_3$) or high nitrogen (16mM $NH_4NO_3$) supplying treatments for 3 months. Photosynthetic parameters were measured monthly. Seedlings were harvested at monthly intervals and growth parameters of root system, stem and needle fractions were evaluated. The result showed that height of the seedlings grown at both of elevated $CO_2Xhigh$ nitrogen and elevated CO2×low nitrogen supplying treatments increased significantly more than that of at ambient CO2 treatments. Seedlings grown at elevated $CO_2Xhigh$ nitrogen produced more root biomass than at elevated $CO_2Xlow$ nitrogen and ambient $CO_2Xhigh$ nitrogen treatments. This result suggested that the root growth response of Picea koraiensis seedlings was greater in elevated $CO_2{\times}high$ nitrogen regime, which is very important for carbon sequestration in soil. $A_{max}$ of the seedlings grown at elevated $CO_2Xhigh$ nitrogen increased during the three months significantly, and $A_{max}$ of the seedlings grown at the other three treatments decreased significantly, suggesting that the interaction between elevated $CO_2$ and high nitrogen supplying stimulates the $A_{max}$ of Picea koraiensis. $A_{max}$ of the seedlings grown at elevated $CO_2Xlow$ nitrogen showed higher than other three treatments in the first month of the experiment, but decreased in succedent two months, suggesting that elevated $CO_2$ promotes the photosynthesis of the seedlings. However long term growth in elevated $CO_2Xlow$ nitrogen supplying condition resulted in an acclimatory decreased in leaf photosynthesis.

• 생명과학회지
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• 제21권7호
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• pp.969-975
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• 2011

본 연구에서는 식물뿌리의 굴중성 반응에 있어서 식물호르몬과 AtEXPA3 유전자와의 관계를 밝히고자 하였다. AtEXPA3 유전자의 RT-PCR을 통한 발현분석 결과 잎, 근출엽, 뿌리 꽃 등 생장이 활발한 조직에서 발현률이 높게 나타났으며, 굴중성 자극과 BRs, IAA에 의해서도 발현이 증가되었다. 또한 ethylene 생합성 저해제인 AVG를 처리하면 굴중성 반응이 현저히 억제되었는데 이는 ethylene 그 자체도 BR과 IAA처럼 굴중성을 촉진시키는 활성을 갖고 있음을 의미한다. 한편 호르몬을 처리하지 않은 AtEXPA3 RNAi mutant에서 굴중성 반응이 억제되는 현상은 애기장대 뿌리의 생장에 관여하는 AtEXPA3의 조절 인자로 BRs, auxin, ethylene 등의 식물호르몬이 관여하고 있음을 나타낸다. 아울러 BRs signaling mutant에서 변화된 굴중성(bri1-301, bak1에서 감소, BRI-GFP에 서 증가) 반응의 감소와 증가는 굴중성 반응이 BRs의 신호전달 과정을 통하여 일어남을 의미한다. 결론적으로 애기장대 뿌리의 굴중성 반응은 식물호르몬에 의한 AtEXPA3 유전자의 발현 증가의 결과로 인해 애기장대 뿌리의 생장이 촉진되어 나타나는 결과라 하겠다.

• 대한기계학회논문집A
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• 제41권4호
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• pp.321-327
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• 2017

본 연구에서는 수평 자세에서의 TIG 용접 시 반응표면법(RSM)을 이용하여, 최적의 이면비드 형상을 구하는 연구를 진행하였다. 입력변수로는 베이스 전류, 피크 전류, 용접속도를 선정하였고, 이면비드 폭을 용접품질에 관한 출력변수로 하여 목표값을 5.4 mm로 설정하였다. Box-Behnken 실험계획법에 따라 실험을 진행하였고, 비드 폭에 관한 2차 회귀모형을 구한 후, F-테스트를 이용하여 회귀모델을 검정하였다. 그리고 망목특성의 호감도 함수를 사용하여 이면비드 형상을 평가함으로써 최적화를 수행하였다. 이렇게 도출된 최적의 용접조건은 코드화된 값으로 베이스 전류; 0.9204, 피크 전류; 0.8676, 용접속도; 0.3776이었다. 검증실험 결과 목표값에 근접한 5.38 mm의 이면비드 폭을 얻을 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제21권7호
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• pp.686-696
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• 2011

To deal with pathogens, plants have evolved sophisticated mechanisms including constitutive and induced defense mechanisms. Phytohormones play important roles in plant growth and development, as well as in the systemic response induced by beneficial and pathogen microorganisms. In this work, we identified an Aspergillus ustus isolate that promotes growth and induces developmental changes in Solanum tuberosum and Arabidopsis thaliana. A. ustus inoculation on A. thaliana and S. tuberosum roots induced an increase in shoot and root growth, and lateral root and root hair numbers. Assays performed on Arabidopsis lines to measure reporter gene expression of auxin-induced/ repressed or cell cycle controlled genes (DR5 and CycB1, respectively) showed enhanced GUS activity, when compared with mock-inoculated seedlings. To determine the contribution of phytohormone signaling pathways in the effect elicited by A. ustus, we evaluated the response of a collection of hormone mutants of Arabidopsis defective in auxin, ethylene, cytokinin, or abscisic acid signaling to the inoculation with this fungus. All mutant lines inoculated with A. ustus showed increased biomass production, suggesting that these genes are not required to respond to this fungus. Moreover, we demonstrated that A. ustus synthesizes auxins and gibberellins in liquid cultures. In addition, A. ustus induced systemic resistance against the necrotrophic fungus Botrytis cinerea and the hemibiotrophic bacterium Pseudomonas syringae DC3000, probably through the induction of the expression of salicylic acid, jasmonic acid/ethylene, and camalexin defense-related genes in Arabidopsis.

• 한국초지조사료학회지
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• 제41권3호
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• pp.162-167
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• 2021

Aluminum (Al) stress in acidic pH is known to decrease the growth and productivity of alfalfa. However, not much is known about how the application of silicon (Si) affects the Al stress response in alfalfa. This study was conducted to evaluate the effect of exogenous application of Si on the growth of alfalfa seedlings exposed to Al stress in pots. Alfalfa seedlings grown in pots for 2 weeks were treated either Al stress (pH 4.0, 0.2 mM Al) or Al stress + Si (1 mM) for 5 days, lengths and biomass of shoot and root, and chlorophyll and carotenoid contents in leaf tissues were analyzed respectively. Al stress treatment inhibited shoot and root growth, and decreased fresh and dry weights, and chlorophyll content in leaves, but increased carotenoid content. In contrast, when alfalfa seedlings treated with Al stress combined with Si, delayed growth caused by Al stress of shoot and root of alfalfa seedlings was restored, dry weight was increased and chlorophyll content of leaf tissue was increased, but carotenoid content was decreased. These results suggest that Si has a function of alleviating Al toxicity in alfalfa, of which it exhibits a mitigating effect by a function that overlaps with some of the intracellular functions of carotenoids.

• 한국약용작물학회지
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• 제8권3호
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• pp.283-289
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• 2000

내추대성 참당귀 노지육묘 이식재배시 묘두직경에 따른 생육 및 추대반응을 구명하고자 수행한 시험결과를 요약하면 다음과 같다. 출현율은 묘두직경이 클수록 높고 적올수록 낮았으며, 지상부 및 뿌리생육은 묘두직경이 클수록 양호하고 묘두직경이 적을수록 부진하였다. 추대시기는 묘두직경이 굵을수록 빨라지고 적을수록 늦어졌으며, $0.11{\sim}0.3,\;0.31{\sim}0.5,\;0.51{\sim}0.7,\;0.71{\sim}0.9,\;0.91{\sim}1.1cm$로 묘두직경이 굵어짐에 따라 각각 0.2%, 1.6%, 3.3%, 11.8%, 46.6%로 증가되었다. 10a당 수량은 $0.51{\sim}0.7cm$에서 319kg 으로 가장 높았으며, $0.51{\sim}0.7cm$보다 묘두직경이 작을수록 수량이 낮아지고 0.91cm 이상 묘에서는 추대율이 높아 수량이 낮았다. 추대율은 초장과 정(正)의 상관을 보였으며, 건근수량은 추대율과 부(負)의 상관을 보였다. 추대율이 비교적 낮고 수량이 가장 많은 묘두직경은 $0.51{\sim}0.7cm$였으며, 당귀재배시 적정 묘두직경의 범위는 $0.31{\sim}0.7cm$였다.

• Earthquakes and Structures
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• 제14권1호
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• pp.45-53
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• 2018

A family of the structure-dependent methods seems very promising for time integration since it can simultaneously have desired numerical properties, such as unconditional stability, second-order accuracy, explicit formulation and numerical dissipation. However, an unusual overshoot, which is essentially different from that found by Goudreau and Taylor in the transient response, has been experienced in the steady-state response of a high frequency mode. The root cause of this unusual overshoot is analytically explored and then a remedy is successfully developed to eliminate it. As a result, an improved formulation of this family method can be achieved.

• Structural Engineering and Mechanics
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• 제60권1호
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• pp.149-162
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• 2016

Structure-dependent integration methods seem promising for structural dynamics applications since they can integrate unconditional stability and explicit formulation together, which can enable the integration methods to save many computational efforts when compared to an implicit method. A newly developed structure-dependent integration method can inherit such numerical properties. However, an unusual overshooting behavior might be experienced as it is used to compute a forced vibration response. The root cause of this inaccuracy is thoroughly explored herein. In addition, a scheme is proposed to modify this family method to overcome this unusual overshooting behavior. In fact, two improved formulations are proposed by adjusting the difference equations. As a result, it is verified that the two improved formulations of the integration methods can effectively overcome the difficulty arising from the inaccurate integration of the steady-state response of a high frequency mode.

• Wind and Structures
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• 제9권5호
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• pp.397-412
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• 2006

This paper presents the wind excited acceleration responses of a 50 m guyed mast under the action of Typhoon Dujuan. The response of the structure is reconstructed from using a full finite element model and an equivalent beam-column model. The wind load is modelled based on the measured wind speed and recommendations for high-rise structures. The nonlinear time response analysis is conducted using the Newton Raphson iteration procedure. Comparative studies on the measured and computed frequencies and acceleration responses show that the torsional vibration of the structure is significant particularly in the higher vibration modes after the first few bending modes. The equivalent model, in general, gives less accurate amplitude predictions than the full model because of the omission of torsional stiffness of the mast in the vibration analysis, but the root-mean-square value is close to the measured value in general with an error of less than 10%.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.233-240
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• 1999

A general procedure is presented here to develope seismic design and analysis method for cable-supported bridges like suspension bridges subjected to ground motion. For representing a numerical model of suspension bridges. a new approach which satisfy design conditions for the initial equilibrium state of suspension bridges. without any nonlinear iterations. is proposed. The dynamic behavior of that model is verified by free vibration analysis. This study uses the response spectrum analysis to determine the Peak response of a suspension bridge to earthquake-induced ground motion. The SRSS(Square Root of Sum of Square). modal combination rule, is adopted for each direction, longitudinal and transverse. To illustrate the potential applicability for the seismic design of suspension bridges, a numerical example is presented in which the dynamic response of the Nam-hae suspension bridge subjected to earthquake