• Ecology and Resilient Infrastructure
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• 제5권1호
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• pp.1-10
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• 2018

We examined the effect of simultaneous application of phosphorus (P) and iron (Fe) on the phytotoxicity of lettuce in arsenic (As) contaminated soil using response surface methodology (RSM). To stabilize As and supply nutrient into soil, Fe and P were treated, respectively. Water soluble As and P was decreased by Fe application but increased by P application. Through phytotoxicity test, the result showed that only the addition of P affected lettuce root elongation even though both P and Fe were added. The correlation coefficients between root elongation and other indices indicated that the As content in the roots seemed to be the main reason that root growth was impeded. We could verify that the former result was not a passing phenomenon and Fe was necessarily needed to protect secondary pollution by exclusive usage of P fertilizer.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.35-35
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• 2017

How do plants take up water from soils especially when water is scarce in soils? Plants have a strategy to respond to water deficit to manage water necessary for their survival and growth. Plants regulate water transport inside them. Water flows inside the plant via (i) apoplastic pathway including xylem vessel and cell wall and (ii) cell-to-cell pathway including water channels sitting in cell membrane (aquaporins). Water transport across the root and leaf is explained by a composite transport model including those pathways. Modification of the components in those pathways to change their hydraulic conductivity can regulate water uptake and management. Apoplastic barrier is modified by producing Casparian band and suberin lamellae. These structures contain suberin known to be hydrophobic. Barley roots with more suberin content from the apoplast showed lower root hydraulic conductivity. Root hydraulic conductivity was measured by a root pressure probe. Plant root builds apoplastic barrier to prevent water loss into dry soil. Water transport in plant is also regulated in the cell-to-cell pathway via aquaporin, which has received a great attention after its discovery in early 1990s. Aquaporins in plants are known to open or close to regulate water transport in response to biotic and/or abiotic stresses including water deficit. Aquaporins in a corn leaf were opened by illumination in the beginning, however, closed in response to the following leaf water potential decrease. The evidence was provided by cell hydraulic conductivity measurement using a cell pressure probe. Changing the hydraulic conductivity of plant organ such as root and leaf has an impact not only on the speed of water transport across the plant but also on the water potential inside the plant, which means plant water uptake pattern from soil could be differentiated. This was demonstrated by a computer simulation with 3-D root structure having root hydraulic conductivity information and soil. The model study indicated that the root hydraulic conductivity plays an important role to determine the water uptake from soil with suboptimal water, although soil hydraulic conductivity also interplayed.

• 한국식물학회:학술대회논문집
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• 한국식물학회 2002년도 춘계학술발표대회:발표눈문요지록
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• pp.91-91
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• 2002

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 춘계학술대회
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• pp.51-51
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• 2022

• Journal of Welding and Joining
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• 제27권1호
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• pp.95-101
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• 2009

In case of manufacturing the high quality welds or pipeline, the full penetration weld has to be made along the weld joint. Thus the root pass welding is very important and has to be selected carefully. In this study, an experimental method for the selection of optimal welding condition was proposed in the root pass welding which was done along the V-grooved butt weld joint. This method uses the response surface analysis in which the width and height of back bead were chosen as the quality variables of the weld. The overall desirability function, which is the combined desirability function for the two quality variables, was used as the objective function for getting the optimal welding condition. In the experiments, the target values of the back bead width and the height are 6mm and zero respectively for the V-grooved butt weld joint of 8mm thickness mild steel. The optimal welding conditions could predict the back bead profile(bead width and height) as 6.003mm and -0.003mm. From a series of welding test, it was revealed that a uniform and full penetration weld bead can be obtained by adopting the optimal welding condition which was determined according to the method proposed.

• Communications for Statistical Applications and Methods
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• 제17권2호
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• pp.241-253
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• 2010

표준 단위근 검정이 실제 시계열자료의 단위근 귀무가설을 기각하지 못하는 경우가 많아지고 검정력에 문제점을 드러내면서 이와는 반대로 정상성 귀무가설을 단위근 대립가설에 대해 검정하는 방안이 제기되어 왔다. 본 연구는 국내 광역지역의 주택가격 시계열자료에 귀무가설과 대립가설이 바뀐 두 가지 종류의 단위근 검정법을 모두 적용시켜 보았다. 그리고 지역 자료간 통계적 역학관계를 검정하기 위한 인과관계, 교차상관관계 또 충격반응 및 분산분해 등에 대한 분석 결과는 대체로 일관된 성향을 보이는 것으로 나타났다.

• 제어로봇시스템학회논문지
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• 제10권4호
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• pp.295-303
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• 2004

Previously it has been shown that the all pole systems resulting good time responses can be characterized by so called K-polynomial. The polynomial is defined in terms of the principal characteristic ratio $\alpha_1$ and the generalized time constant $\tau$ . In this paper, Part II presents several sensitivity analyses of such systems with respect to $\alpha_1$ and $\tau$ changes. We first deal with the root sensitivity to the perturbation of $\alpha_1$ . By way of determining the unnormalized function sensitivity, both time response sensitivity and frequency response sensitivity are derived. Finally, the root sensitivity relative to $\tau$ change is also analyzed. These results provide some useful insight and background theory when we select of and l to compose a reference model of which denominator is a K-polynomial, which is illustrated by examples.

• 한국약용작물학회지
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• 제24권5호
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• pp.360-369
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• 2016

Background: Cylindrocarpon destructans (Zins) Scholten is an important pathogenic fungus that causes ginseng root rot in many ginseng growing areas in China. Although C. destructans have been studied worldwide, research on its chemotaxis towards ginseng (Panax ginseng C. A. Meyer) root exudates in the rhizosphere remains limited. Methods and Results: In this study, we collected ginseng root exudates with three different polarities from three-year-old ginseng roots, and performed chemotaxis and spore germination assays to investigate the ability of these exudates to induce the response in C. destructans. The results showed that, compared with other conditions, when C. destructans cultivated at $20^{\circ}C$ and a pH of 6 exhibited a strong positive chemotactic response toward $2mg/{\ell}$ aqueous phase, $20mg/{\ell}$ butanol phase, and $0.2mg/{\ell}$ petroleum ether from ginseng root exudates, the chemotactic moving indexes were 0.1581, 0.1638 and 0.1441, respectively. In addition, the spore germination rate with optimal chemotactic parameters were 48%, 53%, and 41% in the aqueous phase, butanol phase and petroleum ether groups, respectiviely, which were significantly higher than that in the control group (23%) (p < 0.05). The mycelial growth rate with optimal chemotactic parameters increased with culture time, and the maximum growth rates in the aqueous phase, butanol phase and petroleum ether groups were 0.425, 0.406 and 0.364 respectively, on the 4th day. The optimal chemotactic parameters were $39.73mg/50mg/{\ell}$, $48.93mg/50mg/{\ell}$, and $31.43mg/50mg/{\ell}$, in aqueous phase, butanol phase and petroleum ether respectively, from ginseng root exudates, compared with $5.5mg/50mg/{\ell}$, in the control group. Conclusions: The present study revealed that certain ginseng root exudates containing chemical attractants act as nutritional sources or signals for C. destructans and support its colonization of ginseng roots.

• Plant Biotechnology Reports
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• 제5권3호
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• pp.225-234
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• 2011

Arabidopsis mutants with T-DNA insertion in seven calmodulin genes (CAM) were used to determine the specific role of CAM in the tolerance of plants to oxidative stress induced by paraquat and hydrogen peroxide ($H_2O_2$) treatments. Arabidopsis calmodulin mutants (cam) were screened for seedling growth, seed germination, induced oxidative damage, and levels of ${\gamma}$-aminobutyric acid (GABA) shunt metabolites. Only the cam5-4 and cam6-1 mutants exhibited an increased sensitivity to paraquat and $H_2O_2$ during seed germination and seedling growth. In response to treatments with $3{\mu}M$ paraquat and 1 mM $H_2O_2$, only the cam5-4, cam6-1 mutants showed significant changes in malonaldehyde (MDA) levels in root and shoot tissues, with highly increased levels of MDA. In terms of the GABA shunt metabolites, GABA was significantly elevated in root and shoot tissues in response to the paraquat treatments in comparison to alanine and glutamate, while the levels of all shunt metabolites increased in root tissue but not in the shoot tissue following the $H_2O_2$ treatments. GABA, alanine and glutamate levels were significantly increased in root and shoot of the cam1, cam4, cam5-4, and cam6-1 mutants in response to paraquat (0.5, 1 and $3{\mu}M$), while they were increased only in the root tissue of the cam1, cam4, cam5-4, and cam6-1 mutants in response to $H_2O_2$ (200 and $500{\mu}M$, 1 mM). These data show that the cam5-4 and cam6-1 mutants were sensitive to the induced oxidative stress treatments in terms of seed germination, seedling growth, and oxidative damage. The accumulation of GABA shunt metabolites as a consequence of the induced oxidative stress treatments (paraquat and $H_2O_2$ treatments) suggests that the GABA shunt pathway and the accumulation of GABA metabolites may contribute in antioxidant machinery associated with reactive oxygen species and in the acquisition of tolerance in response to induced oxidative stress in Arabidopsis seedlings.

• 응용통계연구
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• 제34권5호
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• pp.671-683
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• 2021

멱배정의 전체 효율은 최적배정보다 감소하지만, 층별 표본을 골고루 배정하는 기법이며 조사 현장에서는 제곱근 비례배정으로 많이 사용된다. 그리고 실제조사에서는 무응답을 고려하여 이론적 공식에서 나오는 것보다 더 많은 표본크기를 추출한다. 본 연구에서는 층별 표본크기를 결정함에 있어서 멱배정 방법에 층별 응답률의 정보를 추가하여 배정하는 기법을 연구한다. 제안된 배정기법들을 비례,최적,제곱근 비례 배정과 비교하며 응답률이 추가된 비례, 최적배정과도 비교하는 것을 모의실험을 통해 살펴봄으로써 배정방법들의 장단점을 살펴본다.