• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.501-510
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• 2002

During drought or impending drought period, the reservoir operation method is required to incorporate demand-management policy rule. The objective of this study is focused to the development of demand reduction rule by incorporating hedging-effect for a single reservoir system. To improve the performance measure of the objective function and constraints, we could incorporate three risk performance criteria proposed by Hashimoto et al. (1982) by mixed-integer programming and also incorporate successive linear programming to overcome nonlinear hedging term from the previous study(Shih et al., 1994). To verify this model, this hedging rule was applied to the Daechung multi-purpose dam. As a result, we could evaluate optimal hedging parameters and monthly trigger volumes.

• Journal of Korea Water Resources Association
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• v.36 no.3 s.134
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• pp.375-384
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• 2003

Severe drought tends to occur in almost event five years in Korea. Drought responses have been well operated in close collaboration with the central, local government and the water management authorities on the institutional framework. However, the responses are usually post-activities to a drought event. The responses often face difficulties in operating and managing process due to an absence of a drought monitoring system and drought triggers. The objective of this study is to set up drought triggers through a time-spatial interpretation of drought index and the government responses during historical drought events. Drought triggers are divided into four categories: advisory, watch, warning and emergency stage. The range and drought-impacted area of an each stage in triggers have been addressed using drought index. Furthermore, a web-based drought monitoring system is illustrated.

• Journal of Plant Biotechnology
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• v.44 no.2
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• pp.142-148
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• 2017

Drought stress is one of the important factors that restrict the expansion of Hevea brasiliensis cultivation to non-traditional regions experiencing extreme weather conditions. Plants respond to drought stress by triggering expression of several drought responsive genes including transcription factors which in turn trigger expression of various downstream signalling pathways and adaptive networks. Expression of such drought responsive genes may revert back to their original level upon re-watering. However, no reports are available on such phenomenon in Hevea and hence, this study was initiated. For this purpose, NAC transcription factor (NAC tf) was chosen as candidate gene. Its expression levels were monitored under intermittent drought as well as irrigated conditions in two clones (RRII 105 and RRIM 600) of H. brasiliensis with contrasting tolerance level. Copy number of NAC tf was found similar in both the clones. Expression of NAC tf was found highly up-regulated in RRIM 600 (a relatively drought tolerant clone) than in RRII 105 (a relatively drought susceptible clone) throughout the drought incidences which upon re-watering, reached back to its original levels in both the clones. The study indicated the existence of an association between expression of NAC tf and drought tolerance trait exhibited by the tolerant clone RRIM 600. The study also proves the influence of drought and re-watering on the leaf photosynthesis and expression of NAC tf in H. brasiliensis.

• Journal of Korea Water Resources Association
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• v.39 no.3 s.164
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• pp.199-214
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• 2006

The efficient management strategies of reservoirs in periods of drought event are an essential element for drought planning. A Water Supply Capacity Index (WSCI) has been developed for the evaluation and effective monitoring of the supply capacity of a reservoir during a drought event. The WSCI is a measure of the duration that a reservoir can supply a required demand under the worst drought condition. The WSCI is not only a useful standard to refer to when making decisions on reservoir operations in a period of drought, but it can be also applied for setting the drought trigger in water demand sites supplied from the reservoir. The correlation between the standardized WSCI and existing drought indices such as PDSI, SPI and SWSI has been analyzed to the applicability of WSCI.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.4
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• pp.499-505
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• 2015

Trend Impact Analysis(: TIA) is an advanced forecasting tool used in futures studies for identifying, understanding and analyzing the consequences of unprecedented events on future trends. An adaptive neuro-fuzzy inference system is a kind of artificial neural network that integrates both neural networks and fuzzy logic principles, It is considered to be a universal estimator. In this paper, we propose an advanced mechanism to generate more justifiable estimates to the probability of occurrence of an unprecedented event as a function of time with different degrees of severity using Adaptive Neuro-Fuzzy Inference System(: ANFIS). The key idea of the paper is to enhance the generic process of reasoning with fuzzy logic and neural network by adding the additional step of attributes simulation, as unprecedented events do not occur all of a sudden but rather their occurrence is affected by change in the values of a set of attributes. An ANFIS approach is used to identify the occurrence and severity of an event, depending on the values of its trigger attributes. The trigger attributes can be calculated by a stochastic dynamic model; then different scenarios are generated using Monte-Carlo simulation. To compare the proposed method, a simple simulation is provided concerning the impact of river basin drought on the annual flow of water into a lake.

• Horticultural Science & Technology
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• v.32 no.5
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• pp.684-693
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• 2014

Abiotic stress conditions such as cold, drought, and salinity trigger physiological and morphological changes and yield loss in plants. Hence, plants adapt to adverse environments by developing tolerance through complex regulation of genes related to various metabolic processes. This study was conducted to construct a coexpression network for multidirectional analysis of salt-stress response genes in Brassica rapa (Chinese cabbage). To construct the coexpression network, we collected KBGP-24K microarray data from the B. rapa EST and microarray database (BrEMD) and performed time-based expression analyses of B. rapa plants. The constructed coexpression network model showed 1,853 nodes, 5,740 edges, and 142 connected components (correlation coefficient > 0.85). On the basis of the significantly expressed genes in the network, we concluded that the development of salt tolerance is closely related to the activation of $Na^+$ transport by reactive oxygen species signaling and the accumulation of proline in Chinese cabbage.

• Journal of Korea Water Resources Association
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• v.47 no.10
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• pp.891-906
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• 2014

This study suggests the hedging rule of MIP (Mixed Integer Programing) in counting the risk evaluation criteria of the objective function and constraints in order to provide the optimum operating rule in reservoir system as constraining water shortage as much as possible which may happen in the downstream control point of water supply in the aspect of water system management. The proposed model is applied to the Han-river reservoir system for two testing periods (Case I: Jan. 1993~Dec. 1997, Case II: Jan. 1999~Dec. 2003). The model based on the hedging rule with trigger volume, estimated in this study shows that in Case I, the monthly minimum discharge was $310.6{\times}10^6m^3$ in the single operation, $56.3{\times}10^6m^3$ in the joint operation, and $317.5{\times}10^6m^3$ in the hedging rule and also, in Case II, the monthly minimum discharge was found to be $204.2{\times}10^6m^3$ in the single operation, $111.2{\times}10^6m^3$ in the joint operation, and $243.7{\times}10^6m^3$ in the hedging rule. In conclusion, the hedging rule, proposed in this study can decrease vulnerability while guarantees reliability and resiliency.