• Journal of Plant Biology
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• 제34권2호
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• pp.93-100
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• 1991

Juglans regia L. 나무밑에는 다른 식물이 잘 자라지 못하고 있다. 그래서 그 임상토양, 수용추출액, 빗물 등을 써서 작물을 심어 본 결과 발아와 생장이 심하게 억제되었다. 그 억제물질을 찾기 위해서 Juglans regia L. 나무의 수용추출액과 빗물을 종이크로마토그래피법으로 분석하여 ferulic acid, p-coumaric acid, caffeic acid, vanillic acid, p-hydroxybenzoic acid, chlorogenic acid, gallic acid를 분리확인했으며, 이 물질들이 억제작용에 관계한 것으로 추정한다.

• The Korean Journal of Ecology
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• 제24권6호
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• pp.341-348
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• 2001

Population dynamics of the oldest relic stand of Pinus densiflora for. erecta which remains as a status of patch in Sokwang-Ri area, Uljin-Gun, was studied to provide the basic data for conservation of the oldest pine stand in Korea. The upper slope site and ridge site including total 12 plots mainly represented Pinus densiflora for. erecta and Quercus mongolica. These two tree species showed reverse J-shaped distribution. From this information, it was concluded that intensive interspecific competition between two species could be occurring. Age distribution of P. densiflora for. erecta on the sites above middle slope area was indicated bi-modal type or tri-modal type which was known as an age structure of climax forest. Therefore, it was estimated that Pinus densiflora for. erecta population could be continuously maintained in the each patch above middle slope area. In the valley sites, hardwood species such as Q. mongolica, Q. variabilis, Styrax obassia and Acer pseudosieboldianum occupied most part of the under crown-cover area and their seedlings and saplings were developing into the closed upper layer crown because the height of upper layer crown reached about 35 meters and such a high crown height was more suitable for light utilization by plants of under layer. The growth patterns were mainly fluctuated for the entire life time of the oldest tree caused by frequent disturbance. And the initial growth curves of the mature trees and suppressed juvenile trees showed different tendencies along the sites.

• Journal of Advanced Marine Engineering and Technology
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• 제36권5호
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• pp.662-673
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• 2012

This study introduces a condition diagnosis technique for a turbine governor system. The governor system is an important control system to handle turbine speed in a nuclear power plant. The turbine governor system includes turbine valves and stop valves which have their own functions in the system. Because a turbine governor system is operated by high oil pressure, it is very difficult to maintain under stable operating conditions. Turbine valves supply oil pressure to the governor system for proper operation. Using the pressure variation of turbine and governor valves, operating conditions of the turbine governor control system are detected and identified. To achieve automatic detection of valve status, time-based and frequency-based analysis is employed. In this study, a new approach, wavelet decomposition, was used to extract specific features from the pressure signals of the governor and stop valves. The extracted features, which represent the operating conditions of the turbine governor system, include important information to control and diagnose the valves. After extracting the specific features, decision rules were used to classify the valve conditions. The rules were generated by a decision tree algorithm (a typical simple method for data-based rule generation). The results given by the wavelet-based analysis were compared to detection results using time- and frequency-based approaches. Compared with the several related studies, the wavelet transform-based analysis, the proposed in this study has the advantage of easier application without auxiliary features.

• Journal of Communications and Networks
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• 제18권5호
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• pp.846-856
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• 2016

Wireless sensor networks (WSNs) are widely applied in monitoring and control of environment parameters. It is sometimes necessary to disseminate data through wireless links after they are deployed in order to adjust configuration parameters of sensors or distribute management commands and queries to sensors. Several approaches have been proposed recently for data dissemination in WSNs. However, none of these approaches achieves both high efficiency and low complexity simultaneously. To address this problem, cluster-tree based network architecture, which divides a WSN into hierarchies and clusters is proposed. Upon this architecture, data is delivered from base station to all sensors in clusters hierarchy by hierarchy. In each cluster, father broadcasts data to all his children with instantly decodable network coding (IDNC), and a novel scheme targeting to maximize total transmission gain (MTTG) is proposed. This scheme employs a new packet scheduling algorithm to select IDNC packets, which uses weight status feedback matrix (WSFM) directly. Analysis and simulation results indicate that the transmission efficiency approximate to the best existing approach maximum weight clique, but with much lower computational overhead. Hence, the energy efficiency achieves both in data transmission and processing.

• 한국환경과학회지
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• 제18권2호
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• pp.153-167
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• 2009

Riparian vegetation gives basic habitats for animal and other biological organisms. It is one of essential landscapes in river ecosystem. This floral study was conducted to give basic information for management of the Geum river ecosystem. We discovered total 69 plant communities out of 40 sites studied and mean 8 plant communities were analysed per study site. Salix koreensis and Salix subfragilis community were dominant of all communities at tree layer and Salix gracilistyla and Rubus parvifolius were dominant communities at shrub layer. Phalaris arundinacea, Phragmites japonica, Miscanthus sacchariflorus and Artemisia princeps var. orientalis appeared most as perennial grasses and Humulus japonicus, Persicaria thunbergii and Persicaria hydropiper appeared most as annual grasses. Robinia pseudoacacia, Amorpha fruticosa and Bidens frondosa were frequently present as exotic species. Grass communities were higher than tree communities because of human disturbance by artificial banks. The number of species was 182 appeared as 53 families 144 species, 34 varieties and 4 forma and mean species number was 25.5 per site. The most abundant site was Yanggang bridge site (14 vegetation association, 49 species) and the least abundant site was Namdaechon, Muju site (3 vegetation association, 12 species). We suggest that continuous riparian vegetation monitoring should be carried out to manage water environment ecologically.

• 환경영향평가
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• 제20권5호
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• pp.663-673
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• 2011

In the face of accelerating biodiversity loss and its significance in our coexistence with nature, biodiversity is becoming more crucial in sustainable development perspective. To estimate biodiversity in the future which provides valuable information for decision making system especially in the national level, a quantitative approach must be studied forehand as a baseline of the present status. In this study, we developed a large-scale map of Plant Species Richness (PSR, typical indicator of biodiversity) for Young-dong and Pyung-chang provinces. Due to the accessibility of appropriate data and advance of modelling techniques, reduction of variables without deteriorating the predictive power is considered by applying Genetic algorithm. In addition, a number of Correctly Classified Instances (CCI) with 10-fold cross validation which indicates the predictive power, was carried out for evaluation. This study, as a fundamental baseline, will be beneficial in future land work as well as ecosystem restoration business or other relevant decision making agenda.

• 한국조사연구학회지:조사연구
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• 제5권1호
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• pp.1-26
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• 2004

The aim of this study lies in answering the question "How to form weighting cells to enhance sample representativeness in telephone, Internet and mobile surveys\ulcorner". For this, we explored 2% raw data of Year 2000 Population and Housing Census of Korea looking for meaningful patterns for ownership of telephones, the usage of Internet and/or mobile phones. We found that telephone coverage rates vary significantly by household size; 84.6% for one member households, contrasting 98.5% for two-or-more member households. Thus, telephone survey samples need to be weighted differently in sub-groups by household size for proportional representation of target population. Searching socio-demographic factors influencing the use of Internet by C5.0 tree models, we found that education levels and the occupation (or housing type, the automobile ownership) are two most important factors in addition to gender and age. Thus, surveyor might form weighting cells by such factors at the stage of post-stratification or set quotas, a priori, proportional to size of the cells by such factors. For mobile surveys, we approached similarly and found that education levels and the occupation (or the automobile ownership, marriage status) are two additional factors that may be used in forming weighing cells or in setting quotas for cells.

• Journal of Communications and Networks
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• 제16권4호
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• pp.371-377
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• 2014

Localized topology control is attractive for obtaining reduced network graphs with desirable features such as sparser connectivity and reduced transmit powers. In this paper, we focus on studying how to prolong network lifetime in the context of localized topology control for wireless multi-hop networks. For this purpose, we propose an energy efficient localized topology control algorithm. In our algorithm, each node is required to maintain its one-hop neighborhood topology. In order to achieve long network lifetime, we introduce a new metric for characterizing the energy criticality status of each link in the network. Each node independently builds a local energy-efficient spanning tree for finding a reduced neighbor set while maximally avoiding using energy-critical links in its neighborhood for the local spanning tree construction. We present the detailed design description of our algorithm. The computational complexity of the proposed algorithm is deduced to be O(mlog n), where m and n represent the number of links and nodes in a node's one-hop neighborhood, respectively. Simulation results show that our algorithm significantly outperforms existing work in terms of network lifetime.

• 한국산림과학회지
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• 제95권5호
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• pp.532-538
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• 2006

Triphala is an important combination of three important forest fruits, i.e., Emblica officinalis, Terminalia chebula and Terminalia bellirica. Chittagong region in Bangladesh was once rich in triphala trees presently subject to the depletion. Thus, these forest resources are being threatened day by day. The study was conducted to learn the present using pattern of the triphala, causes of its depletion and the conservation strategies agreed by the villagers. Eight major uses of triphala trees were recognized. It was revealed that 100% respondents used the triphala as fruit tree followed by 71-78% as fuelwod. The present status of growing stock of triphala was found in depleted condition particularly in the Muslim dominated area. It was found that unawareness was the major cause for depleting the triphala trees agreed by the 87% respondents followed by depleting the village groves by 84%. Awareness creation (100%) and induction of social forestry program (92%) were found major recomendations by the vilagers to retard depleting the triphala tree species in the Chittagong region of Bangladesh.

• 한국양봉학회지
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• 제33권4호
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• pp.227-237
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• 2018

The majority parasitic bee mites of Thailand in genus Tropilaelaps are infesting colonies of native bees (Apis dorsata) and introduced bees (A. mellifera). The investigation aims to study morphological and genetic variation of Tropilaelaps mites infected different hosts. Adult mites were collected from honey bee brood throughout Thailand. Traditional and geometrical morphometrics were measured on photograph by using TPS program. Additional, COI gene variations were examined by PCR-RFLP and nucleotides sequencing. Tree of mites relationships were constructed by NJ and MP assumptions. Morphometric results indicated T. mercedesae were major species infesting on A. dorsata and A. mellifera. Mophological variation represented at anal and epigynial plate, which the shape of the anal plate apex margin has been key character to identify between T. mercedesae (bell to blunt shape) and T. koenigerum (pear shape). However, the discriminant analysis suggested that geometric results were potential to classify Thai Tropilaelaps populations from different hosts better than traditional morphometric. Otherwise, PCR-RFLP clearly detected the site of Dra I and Xba I digestion of Thai Tropilaelaps morphotypes. The COI sequences of T. koenigerum were founded infesting only A. dorsata in Thailand and four sequences that related to the Thai T. mercedesae morphotypes. The NJ and MP tree were clearly classified Thai Tropilaelaps species which were suggested both from morphological and molecular analysis. This information might be basically of taxonomic status, but this should have implication for controlling these mites in Thailand and other countries.