• Geomechanics and Engineering
• /
• 제34권5호
• /
• pp.547-559
• /
• 2023

We evaluated the applicability of machine learning techniques and the Kuz-Ram model for predicting the mean fragmentation size in open-pit mines. The characteristics of the in-situ rock considered here were uniaxial compressive strength, tensile strength, rock factor, and mean in-situ block size. Seventy field datasets that included these characteristics were collected to predict the mean fragmentation size. Deep neural network, support vector machine, and extreme gradient boosting (XGBoost) models were trained using the data. The performance was evaluated using the root mean squared error (RMSE) and the coefficient of determination (r²). The XGBoost model had the smallest RMSE and the highest r² value compared with the other models. Additionally, when analyzing the error rate between the measured and predicted values, XGBoost had the lowest error rate. When the Kuz-Ram model was applied, low accuracy was observed owing to the differences in the characteristics of data used for model development. Consequently, the proposed XGBoost model predicted the mean fragmentation size more accurately than other models. If its performance is improved by securing sufficient data in the future, it will be useful for improving the blasting efficiency at the target site.

• 한국환경복원기술학회지
• /
• 제19권3호
• /
• pp.29-44
• /
• 2016

The purpose of this study is to quantitatively and visually analyze the degree of green biotope fragmentation caused by road construction and other development work using FRAGSTATS and GUIDOS tool. Moreover, linking of the endangered species research, we mapped "Biotope Fragmentation Map" of Daejeon-city. The findings of the study are summarized as follows: First, as the result of FRAGSTATS, landscape indices : number of patch(NP), mean patch size (MPS), edge length(TE), mean nearest neighbor distance(MNN), edge shape(LSI) showed meaningful change from fragmentation. Moreover, the result of GUIDOS analysis, middle core-small core-bridge-branch-edge-islet-perforation showed increase of area percentage without large core. Lastly, analysis result of 'Biotope Fragmentation Map' revealed that changing site of large core's size appeared eighteen-site and designated as the special protection area appeared forty-one site. As the result of the two data, overlapping areas that showed both change of core size and revealed special protection areas revealed four site. For example, five species of endangered species appeared on the NO. 4 site in 'Biotope Fragmentation Map'. The findings of this study as summarized above are considered to play an important role in basic data preventing green biotope fragmentation at the planned level from various development work.

• 화약ㆍ발파
• /
• 제22권3호
• /
• pp.1-12
• /
• 2004

암석 파쇄도는 노천의 벤치발파에서 생산성을 좌우하는 요소이다. 벤치발파에서 암석 파쇄도는 여러 가지 조건의 영향을 받게 되는데, 특히 암반의 불연속면 조건과 자연상태 암반 블록의 크기는 큰 영향을 미치는 것으로 알려져 있다. 이 연구에서는 석회석을 생산하는 3개 노천광산에서 발파조건 뿐 아니라 암반의 불연속면 조건과 자연상태 암반 블록크기를 면밀히 조사하여 이들 조건이 암석 파쇄도에 미치는 영향을 검토하였다. 분석 결과 암반의 불연속면 조건과 발파조건은 복합적인 상호작용에 의해 영향을 미치는 것으로 밝혀졌으며, 특히 자연상태 암반 블록의 크기는 암석 파쇄도에 가장 큰 영향을 미치는 것으로 나타났다. 암석 파쇄도는 암반의 불연속면 조건 중 주절리군의 방향에 의해서도 영향을 받는 것으로 확인되었는데, 주절리군의 방향이 벤치 앞쪽 자유면과 $30^{\circ}$의 경사를 이룰 때 파쇄물의 평균크기가 가장 작게 되는 것으로 나타났다. 이런 현상은 발파로 만들어진 탄성파의 전파경로 차이에 기인하는 것으로 판단된다.

• Geomechanics and Engineering
• /
• 재33권6호
• /
• pp.567-581
• /
• 2023

The prediction and achievement of a proper rock fragmentation size is the main challenge of blasting operations in surface mines. This is because an optimum size distribution can optimize the overall mine/plant economics. To this end, this study attempts to develop four improved artificial intelligence models to predict rock fragmentation through cascaded forward neural network (CFNN) and radial basis function neural network (RBFNN) models. In this regards, the CFNN was trained by the Levenberg-Marquardt algorithm (LMA) and Conjugate gradient backpropagation (CGP). Further, the RBFNN was optimized by the Dragonfly Algorithm (DA) and teaching-learning-based optimization (TLBO). For developing the models, the database required was collected from the Midouk copper mine, Iran. After modeling, the statistical functions were computed to check the accuracy of the models, and the root mean square errors (RMSEs) of CFNN-LMA, CFNN-CGP, RBFNN-DA, and RBFNN-TLBO were obtained as 1.0656, 1.9698, 2.2235, and 1.6216, respectively. Accordingly, CFNN-LMA, with the lowest RMSE, was determined as the model with the best prediction results among the four examined in this study.

• 한국조경학회지
• /
• 제26권2호
• /
• pp.240-250
• /
• 1998

This study is to have attempted to analyze the characteristics of the change in forest landscape pattern of Seoul for 18 years by grasping it through satellite image data on the forest area in Seoul where a rapid change according urbanization and industrialization is going on. On the basis of Landsat MSS data- satellite image data, this writer analyzed the change in the number and size of patch and the mean edge length of each forest land, and the index of patch shape by each year from a landscape -ecological point of view. The results are as follows; First, in the pattern change of the forest patch of Seoul, the highest patch fragmentation area is the forest of the Yangchon-gu district where is decreasing it forest area by 654ha, 511ha, 495ha, 402ha each year from its total size of 742ha in 1979. Second, the change tendency shows that the average forest size decreased at 552.58ha in 1983, 435.03ha in 1988, 396.23ha in 1992, and 379.96ha in 1996. And analysis showed that even in the number of patches, the forest fragmentation phenomenon was presenting by the increase of development disturbance. Third, the mean edge by year was longest at 23,385m in 1979, but it is decreasing continuously. This shows the regular and artificial uniformity of forest landscape by disturbance-effect increase of the built-up development and shows low portion against edge effect by the time-series change like 1979>1983>198>1992>1996. Finally, in the analysis of a shape index indicated by ratio of size and edge, total averages were 2.56, 2.33, 2.17, 2.14, 2.14 each year, so that it is considered that the disturbance and ecological health status against forest landscape can be grasped according to being examined as 1979>1983>1988>1992, 1996 by the time-series change of the landscape.

• 터널과지하공간
• /
• 제26권2호
• /
• pp.120-130
• /
• 2016

노천광산에서 발파파쇄석의 입도예측에 널리 활용되고 있는 Kuz-Ram 모델의 국내 석회석 노천광산에 대한 적용성을 분석하기 위해, 강원도 동해지역 석회석 노천광산을 대상으로 총 21회의 현장 시험을 수행하였다. 현장시험결과와 Kuz-Ram 모델 예측의 비교 분석 결과, 평균 파쇄입도에서는 최대 56.45%, 균등계수에서는 최대 37.52%의 오차가 나타나는 등, 암석계수와 균등계수에 대한 다양한 보정요소를 제시함에도 불구하고 Kuz-Ram 모델의 예측값에는 상당한 수준의 오차가 발견되었다. 또한 동일한 벤치에서 유사한 발파패턴으로 시험발파를 수행했음에도 각기 다른 보정요소를 적용해야 하는 문제점도 도출되었다. 따라서 국내 노천광산의 발파패턴 및 암반조건과는 다른 경험값을 바탕으로 개발된 Kuz-Ram 모델의 국내 적용성 확대를 위해서는 반드시 해당 광산의 현장조건에 맞도록 수정, 보완되어야 할 것이다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.1162-1165
• /
• 2004

Size and crystalline phase changes of $Fe_{2}O_{3}$ nanoparticles formed in a $H_{2}/O_{2}$ flame have been investigated. At flame temperatures below $1350^{\circ}C$, the mean particle size increased monotonously with the distance from the burner edge; but in high-temperature flames above $1650^{\circ}C$, it suddenly decreased from 20 nm to ${\sim}3$ nm with the distance from the burner edge. The results of X-ray diffraction and HRTEM showed that this sudden reduction of the size of nanoparticles was accompanied by a partial phase transformation from ${\gamma}$-$Fe_{2}O_{3}$ into ${\alpha}$-$Fe_{2}O_{3}$. We suggest the structural instability due to ${\gamma}-$ to ${\alpha}-phase$ transformation as a mechanism for a rapid fragmentation of 20 nm particles into 3 nm ones.

• ALGAE
• /
• 제23권2호
• /
• pp.141-150
• /
• 2008

Populations of Codium amplivesiculatum were found in association with rhodolith beds. We present population trends of C. amplivesiculatum from surveys conducted in the southwestern Gulf of California based on monthly sampling from June 1999 to August 2000. Surveys were conducted at 2 sites in the San Lorenzo Channel at depths of 8 - 12 m. The parameters measured were percent cover, biomass and structure in relation to size of the thalli. From each thallus the following measurements were taken: length and diameter, proportion of each thallus with reproductive structures and the degree of fragmentation (measured as number of small thalli). Mean biomass and cover varied seasonally with the maximum (1036.6 gm$^{-2}$ and 100% cover) present in June 2000 and the minimum in winter (0 gm$^{-2}$ and 0% cover). The longest fronds (3 m) occurred during July 1999 and August 2000, while the maximum diameters of 1.0 cm were present during October and November 1999. There were no significant linear relationships between length and diameter of the fronds, suggesting independent growth. Reproductive structures were common in June and July 1999 with monoic and dioic thalli present. Most fronds were monoic, and this is the first record of this feature for this species. Fragmentation occurred in September, and may be associated with stress from early gametangial reproduction and the combination of high temperatures and low nutrients. A hypothetical life cycle for the species is presented.

• 한국지구과학회지
• /
• 제18권6호
• /
• pp.493-499
• /
• 1997

한반도 동해 남부 대륙붕에 분포하는 탄산질-쇄설성분 혼합 퇴적물에서 성분별 입도분석을 실시하여, 퇴적 환경 및 퇴적기작을 해석하였다. 쇄설성분은 평균입도가 중립사와 세립사 범위였으며, 분급이 양호한 단빈도 입도분포를 나타내었다. 이들 쇄설 퇴적물은 해수면이 낮았던 지난 빙하기동안 해빈 퇴적환경에서 집적되었으며, 전형적인 잔류퇴적물로 해석된다. 패각류가 우세한 탄산질 성분은 거의 파쇄된 상태이며, 표면이 심하게 풍화되었다. 이들 패각도 빙하기동안 천해환경에서 서식하였던 잔류기원 패각편으로 해석된다. 한편 입도특성은 쇄설성 성분에 비하여 다소 조립하며, 분급도는 불량하였다. 이들 패각편 탄산질 성분은 집적된 이후 지속적인 파쇄 및 분급작용에 의해 입도분포의 특징이 조절된 것으로 해석된다.

• 한국환경복원기술학회지
• /
• 제8권1호
• /
• pp.63-72
• /
• 2005

Chirisan National Park, the first and largest one out of 20 national parks in Korea, is divided into five zones. They are composed of nature preservation zone, natural environment zone, natural residential zone, concentrated residential zone, and collective facility zone. However, the park is not a continuous habitat: roads, trails, local residences, and various facilities created the habitat mosaics severely fragmented. We investigated the fragmentation pattern of the park due to roads and mountain trails using GIS. Based on perimeter length, area, and the ratio of perimeter to area of each patch, we obtained landscape analysis indices which reflect the regularity of the patch shape. The 1 m-wide hiking trails divided the park into 491 fragments. The legal trails with 1.5 m - 3 m width which have been heavily used by hikers generate 58 fragments. Even the nature preservation zone, corresponding to a core zone comprising 31.8% of the park area, was divided into 37 fragments because of the roads and mountain trails. With the different widths of buffer applied, the core sizes of the fragments were reduced. When the 60 m buffer was applied, the patch interior areas ranged from 0.0001 to 47.77 $km^2$ with a mean of 7.08 $km^2$. The landscape shape indices were far greater than 1 for most of the cases with a maximum value of 25. These results clearly indicate that Chirisan National Park is not a continuous habitat, but mosaics of small, irregularly shaped habitat fragments. It is necessary to take the size and shape of the fragmented habitats into consideration when nature conservation is planned, especially for large wildlife such as brown bears.