• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.911-919
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• 2004

IP address lookup is one of the essential functions on internet routers, and it determines overall router performance. The most important evaluation factor for software-based IP address lookup is the number of the worst case memory accesses. Binary prefix tree (BPT) scheme gives small number of worst case memory accesses among previous software-based schemes. However the tree structure of BPT is normally unbalanced. In this paper, we propose weighted binary prefix tree (WBP) scheme which generates nearly balanced tree, through combining the concept of weight to the BPT generation process. The proposed WBPT gives very small number of worst case memory accesses compared to the previous software-based schemes. Moreover the WBPT requires comparably small size of memory which can be fit within L2 cache for about 30,000 prefixes, and it is rather simple for prefix addition and deletion. Hence the proposed WBPT can be used for software-based If address lookup in practical routers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3B
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• pp.305-313
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• 2004

Group multicast refers to the kind of multicast in which every member of a group is allowed to transmit data to the group. The goal of routing algorithms for group multicast is to construct a set of low cost multicast trees including all the group members with QoS (e.g., bandwidth) constraint. There have been several algorithms proposed: source tree and shared tree approaches. However, the latter approach has a low success rate in constructing a shared multicast tree, and the former approach suffers from high control overhead and low scalability as stoup size increases. In this paper, we present a heuristic algorithm which varies the number of multicast trees according to the network load. The simulation results show not only that our algorithm outperforms the shared tree approach in terms of the success rate, but also that it has lower control overhead than the source tree approach while guaranteeing the same success rate.

• The Korean Journal of Applied Statistics
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• v.27 no.5
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• pp.717-729
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• 2014

Projection pursuit classification tree uses a 1-dimensional projection with the view of the most separating classes in each node. These projection coefficients contain information distinguishing two groups of classes from each other and can be used to calculate the importance measure of classification in each variable. This paper reviews the variable importance measure with increasing interest in line with growing data size. We compared the performances of projection pursuit classification tree with those of classification and regression tree(CART) and random forest. Projection pursuit classification tree are found to produce better performance in most cases, particularly with highly correlated variables. The importance measure of projection pursuit classification tree performs slightly better than the importance measure of random forest.

• Korean Journal of Plant Resources
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• v.36 no.1
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• pp.91-99
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• 2023

Plus tree selection is the essential first step in a tree improvement program. This study was carried out to select plus trees of black locust (Robinia pseudoacacia L.) for tree improvement in Korea. The candidate plus trees of black locust were selected from twenty-one places in the four provinces (Gangwon, Gyeonggi, Chungcheong and Gyeongsang) following comparison selection. The trees were examined for qualitative and quantitative traits of economic interest like tree height (H), diameter at breast height (DBH), clear bole height (CBH), stem straightness (SS), crown size (CS) and disease resistance. The 64 selected trees showed higher quality in growth characteristics than control trees. Average of height, DBH, CBH, SS and CS were 20.5 m, 31.1 cm, 10.1 m, 1.2 and 5.2 m respectively. In particular, it was shown that the growth characteristics were higher in Chungcheong population. The superiority percentage of selected candidate plus trees of black locust over their respective check trees ranged from 7.3% to 18.9% in height, 20.0% to 40.6% in DBH, 32.8% to 73.5% in CBH, 42.9% to 55.2% in SS and -11.1% to 9.4% in CS, respectively. The selected black locust will be useful in future tree breeding programs based on their clonal and progeny performance.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1939-1944
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• 2003

This paper presents a global path planning algorithm based on a visibility graph method, and applies additionally various constraints for constructing the reduced visibility graph. The modification algorithm for generating the rounded path is applied to the globally shortest path of the visibility graph using the robot size constraint in order to avoid the obstacle. In order to check the visibility in given 3D map data, 3D CAD data with VRML format is projected to the 2D plane of the mobile robot, and the projected map is converted into an image for easy map analysis. The image processing are applied to this grid map for extracting the obstacles and the free space. Generally, the tree size of visibility graph is proportional to the factorial of the number of the corner points. In order to reduce the tree size and search the shortest path efficiently, the various constraints are proposed. After short paths that crosses the corner points of obstacles lists up, the shortest path among these paths is selected and it is modified to the combination of the line path and the arc path for the mobile robot to avoid the obstacles and follow the rounded path in the environment. The proposed path planning algorithm is applied to the mobile robot LCAR-III.

• Journal of Ecology and Environment
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• v.32 no.3
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• pp.137-143
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• 2009

Pre-dispersal seed predation by a granivorous bird, the masked grosbeak (Eophona personata, Fringillidae), was investigated in two bird-dispersed trees, Celtis sinensis and Aphananthe aspera (Ulmaceae). The objectives of this study were to 1) measure direct damage of predation by grosbeaks on plant crops, 2) reveal the temporal pattern of predation within each tree species and its causal factors, and 3) test whether foraging grosbeaks hinder foraging of frugivorous birds, thereby indirectly impacting the reproduction of both tree species. A substantial amount of fruit and seed crop was consumed by grosbeaks (24.3% in Celtis; 55.5% in Aphananthe), and only 17.7% (Celtis) and 16.7% (Aphananthe) were removed by frugivorous birds. At the study site, the grosbeak population size fluctuated greatly during the fruiting seasons of both plant species. As for Celtis, predated seed density also fluctuated temporally, and the local population size of grosbeaks was responsible for predated seed density. In Aphananthe, predation was not fully explained by grosbeak populations or plant phenology, but its peak coincided with that of grosbeak population. These results suggest that predispersal seed predation by granivorous birds can have large negative impacts on the bird-dispersed plants. Changes in local population size of granivorous birds can influence predatation and can affect reproductive success of the bird-dispersed plants available to the birds.

• Survey Research
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• v.5 no.1
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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.

• Korea Journal of Hospital Management
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• v.10 no.1
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• pp.71-92
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• 2005

The purpose of this study is to analyze the efficiency in management of general hospitals and investigate the major factors on efficiency. Specifically, the management of each general hospital is evaluated by using Data Envelopment Analysis(DEA) technique which is a nonparametric statistical method for measurement of efficiency. Then, the influencing factors are investigated through analyses of Decision-Tree Model and Tobit Regression. The target hospitals were general hospitals in which bed sizes are between 200 and 500 among a total of 276 general hospitals. The main data of financial indicators were collected from 48 hospitals, and it was analyzed by using two statistical models. For Model I, three input and two output variables were used for efficiency evaluation. In particular, three input variables were the number of medical doctors, the number of paramedical personnel, and the bed size. And, two output variables were the numbers of inpatients and outpatients per year, adjusted by bed-size. The results of DEA analysis showed that only seven out of 48 hospitals(15%) turned out to be efficient. The decision-tree analysis also showed that there were six significant influencing factors for Model I. Six factors for Model I were Bed Occupancy Rate, Cost per Adjusted Inpatient, New Visit Ratio of Outpatients, Retired Ratio, Net Profit to Gross Revenues, Net Profit to Total Assets. In addition, the management efficiency of hospital is proved to increase as profit and patient-induced indicators increase and cost-related indicators decrease, by the Tobit regression model of independent variables derived from the decision-tree analysis. This study may be contributable to the development of analytic methodology regarding the efficiency of hospital management in that it suggests the synthetic measures by utilizing DEA model instead of suggesting simple ratio-analyzing results.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.407-414
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• 2016

Ex-situ catalytic pyrolysis of a Korean native oak tree over microporous zeolites (HZSM-5, HBeta, and HY) was performed by using a fixed bed reactor. The effect of sample to catalyst ratio and reaction temperature was also investigated to optimize production conditions of high quality bio-oil. Among three catalysts, HZSM-5 showed the highest aromatic formation due to its proper pore size and strong acidity. Although HY and HBeta also showed the catalytic activity, they produced larger amounts of coke due to their larger pore size. The smaller ratio of the sample to the catalyst and higher reaction temperature were also required to maximize the yields of aromatic hydrocarbons via the catalytic pyrolysis of oak tree over HZSM-5.

• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.1
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• pp.53-68
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• 1990

The purpose of this study was to establish the more rational and practical basic theory for the landscape planning in the aparment complex. In this study, the actual conditions of exterior space, the residens' satisfaction degree and the correlation between exterior space and the residents' satisfaction defree were investigated and analyzed on the 13apartment complexes in Taegu City. Through the statistical analysis, the main results were obtained as fellows : It was found that the size of green area ratio in the apartment complexes were in the order of Jugong Apt. (Korean Housing Corporation), Siyoung Apt. (City Operation), Minyoung high-rise Apt. (Private Business) and Minyoung low-rise Apt. (Private Business) complex. The highest ratio of footway and Parking area were shown in Minyoung high-rise Apt. complex. The important factors at the exterior space of apartment complex were composed by 6 major factors, importance degrees of which are Visual, Practical, Convenient, Sentimental, Recreational and Spatial factors for teenagers in orders. The residents' satisfaction degrees to the exterior space were highly correlated with the spatil organization, size of green area and quantity of trees, view, management situation, defensibility of outside noise, rest place, water landscapings by turns. In order to get more than the average satisfaction degree 18 exterior space, the green area should be occupied by 35% of the apartment complex area and more than 76% of the green area (i. e. 16% of the apartment complex area) should be planted with trees. In the Taegu City regulation, the ratio of tree composition is proposed for only the number of tree. But it was shown that the satifaction degree are more correlated with the species and afforestation of trees than the nuts her of trees in this study. therefore, the species of tree and the afforestation of tree should be considered when the landscape planning of the apartment complex begins. It was found that the ratio of afforestation to make the more desirable exterior space In the apartment complex shoule be 8 to 2 in the ratio of arbor to shrub. It was also required that 30 species of arbor and 15 species of shrub should be planted for the more desirable landscape of the apartment complex.