• Tunnel and Underground Space
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• v.16 no.2 s.61
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• pp.109-134
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• 2006

Rocks undergo weathering processes influenced by changing in pressure-temperature condition, atmosphere, underground water, and rainfall. The weathering processes change physical and chemical characteristics of the rocks. Once the rocks are weathered, the characteristics of them are changed and, because of the changing, several disadvantages such as rock slope failures and underground water spouts are can occur. Before we cut a large rock slope, therefore, we must analyze current weathering conditions of rocks and predict weathering processes in the future. Through the results of such analyses, we can judge reinforcement works. In order to comply with such requests, chemical weathering sensitivity analysis which was analyzed from chemical weathering velocities and other characteristics of rocks has been applied in several prior construction works in Korea. But, It is defective to use directly in engineering fields because it was developed for soils(not rocks), it has too mny factors must be considered and the relationships between the factors are not clear, and it is hard to explain the weathering processes in engineering time range. Besides above, because it has been used for isotropic rocks, this method is hard to apply to anisotropic rocks such as sedimentary rocks. Acceding to studies from morphologists (e.g. Oguchi et al., 1994; Sunamura, 1996; Norwick and Dexter, 2002), time dependent strength reduction influenced by weathering shows a negative exponential function form. Appling this relation, one can synthesize the factors which influence the weathering processes to the strength reduction, and get meaningful estimates in engineering viewpoint. We suggest this weathering sensitivity characterization method as a technique that can explain time dependent weathering sensitivity characteristics through strength changes and can directly applied the rock slope design.

• Journal of Dairy Science and Biotechnology
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• v.34 no.4
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• pp.255-262
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• 2016

This study was conducted to investigate the difficulties of dairy farms in practicing 6th industrialization and methods for overcoming these difficulties. A qustionnaire survey was carried out to examine the present states of farms, recognition of the farmstead milk-processing market situation, possibility of farmstead milk processing for reducing the raw milk surplus, assessment of government policies, and difficulties dairy farmers confront in realizing the 6th industrialization. Farm sizes, types, and human resources organizations varied between farms. Most farmers were producing yogurt and/or fresh (string or barbecue) cheeses, which were marketed through 'Visit and Purchase' channel. Farmers who answered the questionnaire were relatively positive about the current situation of farmstead milk processing, expecting to be involved in the disposal of excess raw milk. Nevertheless, they responded negatively about current relevant policies, citing the main difficulties caused by 'excessive regulation'. Other barriers to successful '6th industrialization' are difficulties in marketing and lack of funds. Approximately 19% of dairy farms practicing the '6th industrialization' use automatic milking system (AMS) and 38.46% of dairy farmers whose milking depends on conventional milking system intend to introduce AMS in the future. Positive expectations of AMS adoption were mostly related to 'lack of time and labor', 'exhibiting for tourism', and 'succession of dairying'.

• Korean journal of applied entomology
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• v.25 no.4 s.69
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• pp.221-228
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• 1986

An empirical model to predict initial disease occurrence and subsequent progress of Alternaria leaf spot was constructed based on the modified degree day temperature and frequency of rainfall in three years field experiments. Climatic factors were analized 10-day bases, beginning April 20 to the end of August, and were used as variables for model construction. Cumulative degree portion (CDP) that is over $10^{\circ}C$ in the daily average temperature was used as a parameter to determine the relationship between temperature and initial disease occurrence. Around one hundred and sixty of CDP was needed to initiate disease incidence. This value was considered as temperature threshhold. After reaching 160 CDP, time of initial occurrence was determined by frequency of rainfall. At least four times of rainfall were necessary to be accumulated for initial occurrence of the disease after passing temperature threshhold. Disease progress after initial incidence generally followed the pattern of frequency of rainfall accumulated in those periods. Apparent infection rate (r) in the general differential equation dx/dt=xr(1-x) for individual epidemics when x is disease proportion and t is time, was a linear function of accumulation rate of rainfall frequency (Rc) and was able to be directly estimated based on the equation r=1.06Rc-0.11($R^2=0.993$). Disease severity (x) after t time could be predicted using exponential equation $[x/(1-x)]=[x_0/(1-x)]e^{(b_0+b_1R_c)t}$ derived from the differential equation, when $x_0$ is initial disease, $b_0\;and\;b_1$ are constants. There was a significant linear relationship between disease progress and cumulative number of air-borne conidia of Alternaria mali. When the cumulative number of air-borne conidia was used as an independent variable to predict disease severity, accuracy of prediction was poor with $R^2=0.3328$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.666-672
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• 1997

Twenty years' daily mean air temperature data was used to calculate the critical early seeding date(CESD), the optimum heading date(OHD), the critical late heading date for stable ripening(CHDR) and the critical late ripening date(CLRD) for rice seeded on dry paddy in different agroclimatic zones in Korea. The CESD was defined as the first day with mean air temperature of 13$^{\circ}C$, and the OHD as the first day of the 40 consecutive days with mean air temperature of 22$^{\circ}C$ or above after heading. The CHDR was defined as the date after which the cumulative daily mean air temperature would be at least 76$0^{\circ}C$. Lastly, the CLRD was defined as the last day when daily mean air temperature remains above 15$^{\circ}C$. This information was used for the estimation of periods from the earliest date of seeding to optimum heading date, the latest possible date of heading and the latest possible date of ripening in respective regions. For instance, in Suwon, those respective periods mentioned were found to be 104days, 124days, and 165days.

• Korean Journal of Remote Sensing
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• v.17 no.1
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• pp.1-14
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• 2001

The enhancement of the refractive index structure parameter $C_n^2$ often occurs where vertical gradients of virtual potential temperature ${\theta}_v$ and mixing ratio q have their maximum values. The $C_n^2$ can be a very useful parameter for estimating the convective boundary layer(CBL) height. The behavior of $C_n^2$ peaks, often used to locate the height of mixed layer, was investigated in the present study. In addition, a new method to determine the CBL height objectively using both $C_n^2$ and vertical air velocity variance ${\sigma}_w$ data of UHF radar was also suggested. The present analysis showed that the $C_n^2$ peaks in the backscatter intensity profiles often occurred not only at the top of the CBL but also at the top of a residual layer or at a cloud layer. The $C_n^2$ peaks corresponding to the CBL heights were slightly lower than the CBL heights derived from rawinsonde sounding data when vertical mixing owing to weak solar heating was not significant and the height of strong vertical ${\theta}_v$ gradients were not consistent with that of strong vertical q gradients. However, the $C_n^2$ peaks corresponding to the CBL heights were in good agreement with the rawinsonde-estimated CBL hegiths when vertical mixing owing to solar heating was significant and the vertical gradient of both ${\theta}_v$ and q in the entrainment zone was very strong. The maximum backscatter intensity method, which determines the height of $C_n^2$ peak as the CBL height, correctly estimated the CBL height when the $C_n^2$ profile had single peak, but this method erroneously estimated the CBL height when there was a residual layer or a cloud layer over the top of the CBL. The new method distinguished when there the CBL height from the peak due a cloud layer or a residual layer using both $C_n^2$ and ${\sigma}_w$ data, and correctly estimated the CBL height. As for estimation of diurnal variation of the CBL height, the new method backscatter intensity method even if the vertical profile of backscatter intensity had two peaks from the CBL height and a residual layer or a cloud layer.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.27 no.3
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• pp.127-143
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• 2022

Recently, many attempts to run numerical ocean models in cloud computing environments have been tried actively. A cloud computing environment can be an effective means to implement numerical ocean models requiring a large-scale resource or quickly preparing modeling environment for global or large-scale grids. Many commercial and private cloud computing systems provide technologies such as virtualization, high-performance CPUs and instances, ether-net based high-performance-networking, and remote direct memory access for High Performance Computing (HPC). These new features facilitate ocean modeling experimentation on commercial cloud computing systems. Many scientists and engineers expect cloud computing to become mainstream in the near future. Analysis of the performance and features of commercial cloud services for numerical modeling is essential in order to select appropriate systems as this can help to minimize execution time and the amount of resources utilized. The effect of cache memory is large in the processing structure of the ocean numerical model, which processes input/output of data in a multidimensional array structure, and the speed of the network is important due to the communication characteristics through which a large amount of data moves. In this study, the performance of the Regional Ocean Modeling System (ROMS), the High Performance Linpack (HPL) benchmarking software package, and STREAM, the memory benchmark were evaluated and compared on commercial cloud systems to provide information for the transition of other ocean models into cloud computing. Through analysis of actual performance data and configuration settings obtained from virtualization-based commercial clouds, we evaluated the efficiency of the computer resources for the various model grid sizes in the virtualization-based cloud systems. We found that cache hierarchy and capacity are crucial in the performance of ROMS using huge memory. The memory latency time is also important in the performance. Increasing the number of cores to reduce the running time for numerical modeling is more effective with large grid sizes than with small grid sizes. Our analysis results will be helpful as a reference for constructing the best computing system in the cloud to minimize time and cost for numerical ocean modeling.

• Korea Science and Art Forum
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• v.19
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• pp.281-292
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• 2015

For this study, I conducted a survey investigating current situation, user preference, and field experiment. Hospitals utilizing digital sign systems at least five years were selected, which are connected with visual elements (layout, typo, color) used in waiting areas and elements of the systems (time, video time line). The results obtained from the field survey showed that digital sign systems used the color of typo and background contrasted to one another to increase explicitness and to ensure easy understanding of contents. In addition, the Gothic typo with relatively high legibility was adopted. Time and video timeline, which characterize digital sign systems, showed the advertising screens of the hospitals and the guidance of medical treatment at regular intervals. Moreover, survey results on user satisfaction showed that a majority of respondents indicated they had difficulty in understanding digital information conveyed from digital sign systems due to time setting for rotational speed or the small size of typo although most of the users had previous experience with digital sign systems. The highest proportion of respondents (n=86, 86%) answered that information related to medical departments was what they sought most frequently and that this kind of information should be importantly considered in digital sign systems. For the experiment, new samples with restructured contents of current digital sign systems were created and tested while keeping its design unchanged as well as applying these new samples. Study participants were in their 20s through 50s. When the size of typo was larger under the same conditions for all age groups, study participants found the desired information approximately 3.5 seconds faster. In addition, those in their 20-30s and 40-50s showed the time difference of 4.7 seconds for small typo and 6 seconds for large typo, which suggested that there was a difference by age in the amount of time taken in the experiment to find the desired information from the rotating digital sign system regardless of age and the size of typo.

• Journal of Korean Society of Disaster and Security
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• v.16 no.4
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• pp.45-59
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• 2023

The global focus on mitigating climate change has traditionally centered on carbon dioxide, but recent attention has shifted towards methane as a crucial factor in climate change adaptation. Natural settings, particularly aquatic environments such as wetlands, reservoirs, and lakes, play a significant role as sources of greenhouse gases. The accumulation of organic contaminants on the lake and reservoir beds can lead to the microbial decomposition of sedimentary material, generating greenhouse gases, notably methane, under anaerobic conditions. The escalation of methane emissions in freshwater is attributed to the growing impact of non-point sources, alterations in water bodies for diverse purposes, and the introduction of structures such as river crossings that disrupt natural flow patterns. Furthermore, the effects of climate change, including rising water temperatures and ensuing hydrological and water quality challenges, contribute to an acceleration in methane emissions into the atmosphere. Methane emissions occur through various pathways, with ebullition fluxes-where methane bubbles are formed and released from bed sediments-recognized as a major mechanism. This study employs Biochemical Methane Potential (BMP) tests to analyze and quantify the factors influencing methane gas emissions. Methane production rates are measured under diverse conditions, including temperature, substrate type (glucose), shear velocity, and sediment properties. Additionally, numerical simulations are conducted to analyze the relationship between fluid shear stress on the sand bed and methane ebullition rates. The findings reveal that biochemical factors significantly influence methane production, whereas shear velocity primarily affects methane ebullition. Sediment properties are identified as influential factors impacting both methane production and ebullition. Overall, this study establishes empirical relationships between bubble dynamics, the Weber number, and methane emissions, presenting a formula to estimate methane ebullition flux. Future research, incorporating specific conditions such as water depth, effective shear stress beneath the sediment's tensile strength, and organic matter, is expected to contribute to the development of biogeochemical and hydro-environmental impact assessment methods suitable for in-situ applications.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.439-446
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• 2009

Nitrogen balance in the regional scale which was calculated the difference between nitrogen input and output was estimated to assess the impact of rice cultivation on water environment. Nitrogen balances in Gyeonggi province, where nitrogen concentration in irrigation water was high and in Chungnam province, where nitrogen absorbtion by rice was high, were -5.4 and -8.3 kg $-8.3kg\;ha^{-1}\;yr^{-1}$, respectively. Nitrogen balances of paddy field in Gangwon province, where nitrogen output was small and irrigation water was clean, and in Gyeongnam province, where organic matter content of soil was high and rice yield was low, were 4.9 and $14.0kg\;ha^{-1}\;yr^{-1}$, respectively. Average nitrogen balance and total nitrogen absorption of paddy field in Korea were estimated to $-0.3kg\;ha^{-1}\;yr^{-1}$ and $-3,315Mg\;yr^{-1}$, respectively. When the nitrogen concentration in irrigation water was increased by $1mg \;L^{-1}$, nitrogen balance of rice paddy changed by $-2.91kg\;ha^{-1}\;yr^{-1}$. Also, when nitrogen fertilizer applied was decreased from 110 to $90kg\;ha^{-1}$ and the same harvest was maintained, the nitrogen absorption by rice paddy from irrigation water was estimated to increase by 10,600 Mg per year in Korea. However, in cases, the harvest was reduced to either 90% or 85%, nitrogen balances were changed from -11.7 to -2.3 and $2.4kg\;ha^{-1}$, respectively. These results suggest that the reduction of nitrogen fertilizer use may not always lead to a negative nitrogen balance and sustainable agriculture can achieve by not cutting down the use of fertilizer only but by reduction of fertilizer application concurrently by maintenance of harvest and by utilization of environmental characteristics such as nutrient contents in irrigation water and soils.