• Journal of Korean Society of Forest Science
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• v.65 no.1
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• pp.54-59
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• 1984

Research was conducted in a minirotation plantation with four different planting densities at Tatae-ri, Chongwoon-myon, Yangpyong-gun, Kyonggi-do, to investigate the relation between volume and biomass production. Nine-year-old Alnus hirsuta var. sibirica analyzed to determine volume yield and weight equations for aboveground parts. The results suggest that the most suitable harvesting or thinning period at highly dense plots, more than 6,000 trees per hectare, is five years after planting, and the most fitted regression equation model for estimating aboveground biomass or total tree biomass is $logY=b_0+b_1logd^2h$.

• Journal of Preventive Medicine and Public Health
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• v.36 no.2
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• pp.147-152
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• 2003

Objectives : To develop a Diagnosis-Related Group (DRG) fraud candidate detection method, using data mining techniques, and to examine the efficiency of the developed method. Methods ; The Study included 79,790 DRGs and their related claims of 8 disease groups (Lens procedures, with or without, vitrectomy, tonsillectomy and/or adenoidectomy only, appendectomy, Cesarean section, vaginal delivery, anal and/or perianal procedures, inguinal and/or femoral hernia procedures, uterine and/or adnexa procedures for nonmalignancy), which were examined manually during a 32 months period. To construct an optimal prediction model, 38 variables were applied, and the correction rate and lift value of 3 models (decision tree, logistic regression, neural network) compared. The analyses were peformed separately by disease group. Results : The correction rates of the developed method, using data mining techniques, were 15.4 to 81.9%, according to disease groups, with an overall correction rate of 60.7%. The lift values were 1.9 to 7.3 according to disease groups, with an overall lift value of 4.1. Conclusions : The above findings suggested that the applying of data mining techniques is necessary to improve the efficiency of DRG fraud candidate detection.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.1234-1249
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• 2017

One of the difficulties developers encounter in maintaining tasks of a large-scale software system is the updating of suitable libraries on time. Developers tend to miss or make mistakes when searching for and choosing libraries during the development process, or there may not be a stable library for the developers to use. We present a novel approach for helping developers modify software easily and on time and avoid software failures. Using a tool previously built by us called GPES, we collected information of projects, such as abstract syntax trees, tokens, software metrics, relations, and evolutions, for our experiments. We analyzed the contexts of source codes in existing projects to predict changes automatically and to recommend suitable libraries for the projects. The collected data show that researchers can reduce the overall cost of data analysis by transforming the extracted data into the required input formats with a simple query-based implementation. Also, we manually evaluated how the extracted contexts are similar to the description and we found that a sufficient number of the words in the contexts is similar and it might help developers grasp the domain of the source codes easily.

• International Journal of Fluid Machinery and Systems
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• v.8 no.4
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• pp.264-273
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• 2015

This presentation describes an experimental approach for the detection of cavitation in hydraulic machines by use of ultrasonic signal analysis. Instead of using the high frequency pulses (typically 1MHz) only for transit time measurement different other signal characteristics are extracted from the individual signals and its correlation function with reference signals in order to gain knowledge of the water conditions. As the pulse repetition rate is high (typically 100Hz), statistical parameters can be extracted of the signals. The idea is to find patterns in the parameters by a classifier that can distinguish between the different water states. This classification scheme has been applied to different cavitation sections: a sphere in a water flow in circular tube at the HSLU in Lucerne, a NACA profile in a cavitation tunnel and two Francis model test turbines all at LMH in Lausanne. From the signal raw data several statistical parameters in the time and frequency domain as well as from the correlation function with reference signals have been determined. As classifiers two methods were used: neural feed forward networks and decision trees. For both classification methods realizations with lowest complexity as possible are of special interest. It is shown that two to three signal characteristics, two from the signal itself and one from the correlation function are in many cases sufficient for the detection capability. The final goal is to combine these results with operating point, vibration, acoustic emission and dynamic pressure information such that a distinction between dangerous and not dangerous cavitation is possible.

• Journal of Korean Society of Forest Science
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• v.88 no.3
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• pp.320-326
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• 1999

In this study, 15 survival functions in integral and difference forms for forest plantation were derived based on assumptions for the number of surviving trees and the differential forms of the mortality rate model. Then, performance of the models was evaluated by fitting to remeasurement data of unthinned white pine(Pinus strobes) forest plantation. As a result, three equations associated with a power function of age, $t^{\beta}$, are somewhat more suitable for describing the effect of self-thinning over time. On the other hand, a general survival function for Japanese larch(Larix leptolepts) forest plantation was derived in order to exam the effect of site quality on self-thinning procedures. The results indicate that the $N_{min}$ is negatively correlated with site index and, even though the same initial stand density was assumed, the survival function curves differ in shapes associated with site index values.

• Korean Journal of Environment and Ecology
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• v.13 no.1
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• pp.34-48
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• 1999

본 연구는 주요 조경수목에 대한 생장예측모델을 추정하여 적정 식재간격을 산정하기 위해 실시하였다. 조경식재에서 많이 사용되는 9개 수종을 대상으로 수종별 30주 이상씩의 개체를 선정한 후, 상관성이 높은 측정변수 간에 회귀분석을 실시하여 생장예측모델을 추정하였다. 그리고 서울 시내 2개 아파트단지 녹지를 사례연구지로 선정하여 생육상태를 파악하고 모델과 비교하였다. 전체적으로 교목층 위주의 식재로 인해 식재밀도가 과밀하여 수관이 왜곡되고 기형적으로 생장하는 현상이 발생하고 있는 바, 수관중복률과 수관왜곡률을 분석한 결과에 의하면 현재의 식재간격이 매우 조밀한 것으로 밝혀졌다. 결론적으로 시간경과에 따른 주요 조경수종의 규격별 생장예측을 통해 목표년도별 적정 식재간격을 제안하였는데, 목표년도를 식재 후 5년으로 본다면 상록교목은 2.0m, 낙엽교목은 3.0~4.0m, 낙엽아교목은 2.0~2.5m의 식재간격이 적당하고, 식재 후 10년을 목표년도로 한다면 상록교목의 경우 3.0m, 낙엽교목은 4.0~6.0m, 낙엽교목은 2.5~3.0m의 간격을 유지하여야 한다. 한편, 본 연구의 결과와 서울시 조례기준 식재밀도를 비교하였는데, 식재후 5년이 경과한 시점에서는 0.23본/m2, 10년 경과시점에서는 0.12본/m2이 적정 식재밀도로 밝혀져 현재 0.2본/m2으로 정하고 있는 서울시 교목식재 관련 기준은 5년 정도를 목표시점으로 한다면 적절한 수준임을 알 수 있었다. 그러나 식재 후 10년이 경과하면 수관중복률이 25%를 초과하게 되므로 쾌적한 녹지환경을 유지하기 위해 반드시 적절한 관리를 실시해야 할 것으로 판단되었다.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.32.2-32.2
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• 2013

We examine large-scale environmental effects on the formation and the mass growth of dark matter halos. To facilitate this, we constructed dark matter halo merger trees from a cosmological N-body simulation, which enabled us to trace the merger information and the assembly history of individual halos. In fact, since the massive halos are more likely to be distributed in denser regions than in less dense regions (Mo & White, 1996), the large-scale environment dependence of the properties of halos can be partly originated from the halo mass effect. In order to avoid such contamination, caused by the mass dependence of halo properties, we carefully measured the local overdensity as the indicator of large-scale environment, which was calculated to be as independent of halo mass as possible. Small halos (${\sim}10^{11-12}M_{\odot}$), which usually host isolated single galaxies, show a notable difference on the formation time of galaxies depending on their large-scale environments, which reconfirms halo assembly bias (Gao & White, 2007). Furthermore, we investigate how this environmental effect on small halos is correlated with the mass assembly history of galaxies by using our semi-analytic model. We found that assembly bias in small halos does not have significant effects on the formation time or on the star formation history of galaxies residing in those halos except for the individual stellar mass of galaxies at z = 0. On average, isolated galaxies in high-density regions tend to be slightly more massive than those in low-density regions. Although the observational data from the current galaxy surveys is not yet sufficient for testing this prediction, future galaxy surveys will be able to explore these small galaxies more thoroughly.

• Journal of Family Resource Management and Policy Review
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• v.8 no.2
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• pp.61-84
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• 2004

This thesis attempted to generate ideal tea culture space that connects environment and culture. Therefore, this examines: First, history of tea and the characteristics of tea culture space from Gochosun to modern times was reviewed Second, psychological factors (spirit of tea) of Korea tea culture space were reviewed. Third, the connection between the concept of tea culture space and Human Ecosystem Model by was analyzed. Also, this thesis examined how the culture of ecosystem and why tea culture space is needed. because tea includes varieties of ingredients for protecting environmental pollution. Finally, tea culture spaces were reviewed each region during Chosun dynasty, and tea culture space of recent tea users. In order to study tea culture space, complex residential area and single residential areas were compared. The useful of tea culture space as a ecological space was also examined. To achieve the purpose of this study, related literatures were reviewed, and investigations of museums and a survey on modern living space were also conducted. The results show that the space of our tea culture were affected by nature worshipping of Gochosun, Buddhism of Koryo, and Confusianism of Chosun with 'Pungryu', the idea that enjoys nature, thereby applying environment-friendly ecological beauty to their living space and life. The cultyral space in Korea is composed of natural environment such as mountain, sea, rock, or trees and artificial environment such as pond or pavilion. In the future, oriental culture with metaphysical value will lead the world culture, and especially, tea culture would play an important role regardless of nationality, race, religion, and ideology. Therefore, establishing a tea culture space in a living space would be the fundamental methods that would be able to settle down such tea life into our daily life. Our attempts to create ecological tea culture space as a integrated cultural space of natural, artificial, and human behavioral environment will contribute to enhance our quality of life.

• Journal of Korea Game Society
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• v.14 no.5
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• pp.97-106
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• 2014

This study proposes an efficient method to model various and diverse leaves required to express digital plants such as flowers and trees in virtual landscape easily and intuitively. The proposed procedural method divides a leaf mainly into a blade and vein thereby detecting contours from binary images that correspond to blades and generating leaves by modeling leaf veins procedurally based on the detected contours. First of all, a complicated leaf vein structure is divided into main veins, lateral veins, and tertiary vein while all veins grow procedurally directing from start auxin to destination auxin. Here, to calculate destination auxin required for growth automatically, approximated contours from binary images that correspond to blades are found thereby calculating candidate destination auxin. Finally, natural digital leaves are generated by applying a color combination method. Through the proposed method, natural and various leaves can be generated and whether the proposed method is efficient or not is verified through the experiment.

• Journal of Korean Society of Forest Science
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• v.89 no.2
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• pp.249-255
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• 2000

This study has been carried out to estimate aboveground biomass and net primary production in a 22-year-old Betula platyphylla and 24-year-old juglans mandshurica plantations. Nine sample trees were cut in each plantation. Estimations for aboveground biomass and net primary production were made by the equation model $Wt=aD^b$ where Wt is ovendry weight in kg and D is DBH in cm. Total aboveground biomass was 79.33t/ha in Betula platyphylla plantation and 67.47t/ha in Juglans mandshurica plantation. The proportion of each tree component to total aboveground biomass was high in order of bolewood, branches, bolebark, and leaves in the two plantations. Aboveground total net primary production was estimated at 9,92t/ha in Betula platyphylla plantation and 11.79t/ha in Juglans mandshurica plantation. There was greater net primary production in Juglans mandshurica plantation than in Betula platyphylla plantation because of greater bolewood, bolebark, current twig, and branch net primary productions in Juglans mandshurica plantation than in Betula platyphylla plantation.