• Journal of Korean Society of Forest Science
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• v.25 no.1
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• pp.1-12
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• 1975

In this study, warmth and cold-indices were calculated from the climatic records for 30 year from 1931 to 1960 observed at the 80 weather stations as illustrated in Table 1 and Figs. 4 and 5. Iso-warmth index and iso-cold index lines were carefully tracked. However, subjectivity might be involved in this delimitation. The well recognized phenomena of phenology, the natural distribution of specified tree species and potentially cultivable zones of some species of economic importance were discussed with regard to these indices. It is seemed that the forest zones of Korea accepted commonly by foresters and researchers were more rationally matched with the cold indices rather than warmth indices. The forest improvement works by introduction, planting works and other related fields could be refered to these data.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.3
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• pp.21-34
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• 2009

Usually in flood flow problems, one-dimensional approach does not provide the required details of complex flow phenomena such as the flow in braided rivers and river junction. In this study, two-dimensional finite element mesh is constructed using DEM and GIS tool, and applied to RMA-2model. The purpose of this study is to investigate the applicability of the two dimensional model in natural rivers and to analyze characteristics of river flow due to the change of cross section. For model calibration, the result of unsteady flow analysis was compared with the observed data. Accordingly, the SMS model in this study prove to be very effective and reliable tool for the simulation of hydrodynamic characteristics under the various flow conditions.

• Korean Journal of Remote Sensing
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• v.22 no.5
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• pp.313-323
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• 2006

Forest Canopy Density is a dynamic process mediated by various natural and anthropogenic factors. It can be changed over time and locations in the same forest type and landscape. However, human dimensions are considered as the primary force of landscape change and subsequent forest canopy loss in tropical regions of the world. Many studies have been indicated that roads have a far greater impact on forests than simply allowing access for human use. Similarly, rivers have been used as means of transportation, hence illegal logging and felling further deplete forest canopy density. The main objective of this study was to investigate the spatio-temporal dynamic alterations of Forest Canopy Density (FCD) across with site associated factors such as biophysical, physical and human interferences in tropical region of Nepal from 1988 to 2001. Landsat TM and ETM+ of 1988 and 2001 were used to assess the spatial and temporal dynamic alterations of FCD. This analysis revealed that distance to human settlements at P=<0.01, rivers, human interferences (path and fire) and species composition had a statistically significance at P=<0.05 level. However, other factors did not show any significant relation. So, we concluded that understanding of dynamic alterations of FCD with respect to factors was quite complex phenomena. Other surrounding environment could also playa significant role. A comprehensive analysis could be required to understand such complexities. Therefore, additional factors such as climatic, biophysical, social, and institutional with respect to spatio-temporal variability should be considered for the better understanding of canopy dynamic.

• The Korean Journal of Malacology
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• v.25 no.3
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• pp.203-210
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• 2009

Optical properties and color analysis of nacreous layers were performed using various pearl shells. The cross section and microstructure of the surface in each nacreous layers were observed through a SEM (Scanning Electron Microscope), and the diffraction pattern on SEM images was analyzed using FFT (Fast Fourier Transform). Through these analysises, it was verified that the color and optical characteristics are closely related to the structure of nacreous layers. Incident angle-dependent reflection spectrum was used to examine the phenomena of color differenceas the direction of observation. Quantified values on the color change were obtained by CIE $L^*a^*b^*$ color scale. Using this research, database for the characteristics of natural pearl shells can be established, and the precise analytic method for observation of pearl shells was suggested.

• Hwankyungkyoyuk
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• v.15 no.1
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• pp.137-147
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• 2002

The progress of environmental science and technology in the developed countries has been rapid in recent years. Particularly remarkable has been the advancement of various pollutant control measures, which have brought the pollution of inorganic factors such as air and water under control. In contrast, diversity of the ecosphere, of which man is a part, is being steadily Impoverished and the biological community is getting unvaryingly uniform. These phenomena were brought about by the expansion of artificial environment such as new industrial complexes, transportation facilities and urban development. Man has constructed uniform and artificial environment, believing in the premise of confrontation with nature, to such a scale that the natural environment and biological community have lost their balance. This will increasingly endanger the soundness of the biotic environment of nature, which constitutes the potential foundation both for the survival environment of man as biological entity and for the development of human civilization. In order to guarantee the soundness of man's body, intelligence and sensitivity as wholesome gene Pool on the earth and for the future of man, primarily important environmental education is the understanding of how man can everlasting exist in and with the survival environment. In view of this reality, it is vitally important to create ecologically diverse and well-balanced environment with living materials, i.e., vegetation in order to secure lasting survival environment for man. This task is urgently required in highly artificial environment where non-biological materials have forced the impoverishment of the biological community. Therefore, environmental education for the future should not be totally oriented to technology as that in the past nor it is limited to the medical aspect where well-being of human is the sole object of concern. That is to say, environmental education for the future should be one that provides knowledge that human can understand his place based on the ecological concept and thereby make him to have ethical consciousness that he can control his behavior within the reasonable level for ecological niche who he is located.

• Tribology and Lubricants
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• v.34 no.6
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• pp.292-299
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• 2018

The objective of this research is to investigate the impact of engine oil aging on PM(Particulate Matter), exhaust gases, and DPF. It is widely known that the specification of a lubricant and its consumption in an ICE considerably influences the release of regulated harmful emissions under normal engine operating conditions. Considering DPF clogging phenomena associated with lubricant-derived soot/ash components, a simulated aging mode is designed for DPF to facilitate engine dynamometer testing. A PM/ash accumulation cycle is developed by considering real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for ash accumulation. The test duration for DPF aging is approximately 300 h with high- and low-SAPs engine oils. Detailed engine lubricant properties of new and aged oils are analyzed to evaluate the effect of engine oil degradation on vehicle mileage. Furthermore, physical and chemical analyses are performed using X-CT, ICP, and TGA/DSC to quantify the engine oil contribution on the PM composition. This is achieved by sampling with various filters using specially designed PM sampling equipment. Using high SAPs engine oil causes more PM/ash accumulation compared with low SAPs engine oils and this could accelerate fouling of the EGR in the engine, which results in an increase in harmful exhaust gas emissions. These test results on engine lubricants under operating conditions will assist in the establishment of regulated and unregulated toxic emissions policies and lubricant quality standards.

• Journal of Wetlands Research
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• v.21 no.3
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• pp.236-243
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• 2019

Hydrologic time series has been analyzed and forecasted by using classical linear models. However, there is growing evidence of nonlinear structure in natural phenomena and hydrologic time series associated with their patterns and fluctuations. Therefore, the classical linear techniques for time series analysis and forecasting may not be appropriate for nonlinear processes. Daily streamflow series at St. Johns river near Cocoa, Florida, USA showed an interesting result of a low dimensional, nonlinear dynamical system but daily inflow at Soyang reservoir, South Korea showed stochastic property. Based on the chaotic dynamical characteristic, DVS (deterministic versus stochastic) algorithm is used for short-term forecasting, as well as for exploring the properties of the system. In addition to the use of DVS algorithm, a neural network scheme for the forecasting of the daily streamflow series can be used and the two techniques are compared in this study. As a result, the daily streamflow which has chaotic property showed much more accurate result in short term forecasting than stochastic data.

• Journal of Engineering Education Research
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• v.21 no.3
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• pp.56-65
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• 2018

With rapid advance of technologies including information and communication technologies, jobs are evolving faster than ever. Architectural engineering is no exception in this regard, and the green architectural engineering is emerging fast as a promising new field. In this study, a Delphi study of expert architectural engineers are conducted to find out (1) near future prospects of the field, (2) near future emerging jobs, (3) competencies needed for these jobs, and (4) educational content necessary to build these competencies with regards to the green architectural engineering. Initial Delphi survey consisting of open-ended questions in the above four areas were conducted and came out with 65 items after duplicate removal and semantic refinements. Further refinements via second and third wave of Delphi results into 40 items that the 13 architectural engineering experts may largely agree upon as future prospects with regards to the green architectural engineering. Findings indicate that it is expected that the demand for green architectural engineering and needs for automatic energy control system increase. Also, collaborations with other fields is becoming more and more important in green architectural engineering. The professional work management skills such as knowledge convergence, problem solving, collaboration skills, and creativity linking components from various related areas seem to also be on the increasing need. Near future ready critical skills are found to be the building environment control techniques (thermal, light, sound, and air), the data processing techniques like data mining, energy monitoring, and the control and utilization of environmental analysis software. Experts also agree on new curriculum for green building architecture to be developed with more of converging subjects across disciplines for future ready professional skills and experiences. Major topics to be covered in the near future includes building environment studies, building energy management, energy reduction systems, indoor air quality, global environment and natural phenomena, and machinery and electrical facility. Architectural engineering community should be concerned with building up the competencies identified in this Delphi preparing for fast advancing future.

• Korean Journal of Heritage: History & Science
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• v.46 no.3
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• pp.4-15
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• 2013

The study of corrosion products generated by archaeological bronzes that have been buried for a long time can provide certain evidence that enables us to understand the natural corrosion process of bronze and helps us develop conservation and preservation methods. In the present study, the specimens taken from two bronze mirrors and three bronze swords were used to study the corrosion morphology and the related phenomena such as selective corrosion of ${\alpha}$ or ${\alpha}+{\delta}$ phases, decuprification, destannification, and secondary copper. Furthermore, corrosion development was discussed based on the ions distributed throughout the corrosion layers.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.42.2-42.2
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• 2019

Turbulence is one of the natural phenomena in molecular clouds. It affects gas density and velocity fluctuation within the molecular clouds and controls the mode and tempo of star formation. However, despite many years of study, the properties of turbulence remain poorly understood. As part of the Taeduk Radio Astronomy Observatory (TRAO) Key Science Program (KSP), "mapping Turbulent properties In star-forming MolEcular clouds down to the Sonic scale (TIMES; PI: Jeong-Eun Lee)", we have fully mapped two star-forming molecular clouds, the Orion A and the Ophiuchus molecular clouds, in 3 sets of lines ($^{13}CO$ J=1-0, $C^{18}O$ J=1-0, HCN J=1-0, $HCO^+$ J=1-0, CS J=2-1, and $N_2H^+$ J=1-0) using the TRAO 14-m telescope. We apply a statistical analysis, Principal Component Analysis (PCA), which can recover an underlying turbulent-power spectrum from an observed P-P-V spectral map. We compare turbulence properties not only between the two clouds, but also between different parts within each cloud. We present the first result of our observation program.