• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.21-28
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• 2018

In recent years, payability of shale gas production has worsened due to oil and gas price declines resulting from sharply increasing shale gas production. Reliable economic evaluation in shale gas development has become important. In this study, Monte Carlo simulation of probabilistic analysis technique was applied to analyze the economic feasibility considering the uncertainty involved in shale gas development. For this, the range of major variables is set and a random number is generated to derive the probability distribution of Net Present Value(NPV) and Internal Rate of Return(IRR). Consequently, we estimated the probability that the feasibility of the project is evaluated to be positive when developing shale gas in the study area. In addition, sensitivity analysis of major parameters affecting economic efficiency in shale gas development was carried out, and the effect of major variables in economic evaluation for commercial production was identified. In the future, this study could be used to make decision for shale gas production by presenting the range of variation of economic index and probability value.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.575-585
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• 2011

The effect of wavelet pair choice in the compression of the satellite images is studied. There is a trade-off between compression rate and perception quality. The encoding ratio is used to express the compression rate, and Peak Signal-to-Noise Ratio (PSNR) is also used for the perceptional performance. The PSNR and the encoding ratio are not matched well for the images with various wavelet pairs, but the tendency is remarkable. It is hard to find the pattern of PSNR for sampled images. On the other hand, there is a pattern of the variation range of the encoding ratio for each image. The satellite images have larger values of the encoding ratio than those of nature images (close range images). Depending on the wavelet pairs, the PSNR and the encoding ratio vary as much as 13.2 to 21.6% and 16.8 to 45.5%, respectively for each image. For Synthetic Aperture Radar (SAR) images the encoding ratio varies from 16 to 20% while for the nature images it varies more than 40% depending on the choice of wavelet pairs. The choice of wavelet for the compression affects the nature images more than the satellite images. With the indices such as the PSNR and the encoding ratio, the satellite images are less sensitive to the choice of wavelet pairs. A new index, energy concentration ratio (ECR) is proposed to investigate the effect of wavelet choice on the satellite image compression. It also shows that the satellite images are less sensitive than the nature images. Nevertheless, the effect of wavelet choice on the satellite image compression varies at least 10% for all three kinds of indices. However, the important of choice of wavelet pairs cannot be ignored.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.73-79
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• 2012

Seasonal changes in biochemical composition of muscle, gonad-viceral, mass and whole body of the cultured ark shell, Scapharca broughtonii in the Gamag bay of Yeosu city were studied from December 2008 to November 2009 in relation to environmental condition and reproductive cycles. Average monthly water temperature in the winter was in the range of $7-12^{\circ}C$ and $20-25^{\circ}C$ in the summer, while the salinity fluctuated in the range of 30.1%-33.8‰ on the average. Seasonal fluctuation of the concentration of nutrient salt was the highest in September ($13.04{\mu}g/L$) with average annual concentration of $4.6{\mu}g/L$. The main spawning season of the ark shell was during the months of July and August, and the gonads were in inactive stage during the winter. The gonad-visceral mass contained lower amounts of proteins than the other body parts. The most marked changes in body composition were lipids and carbohydrates within the gonad-visceral mass, and protein for each of the organs was relatively consistent throughout the year. All the parts in the visceral sac displayed the highest changes during the gametogenic cycle while the contents of moisture and lipid within the visceral act displayed somewhat inverse relations with each other. Moisture content was the lowest during the inactive stage during which the lipid content is the highest. The lipid content was the lowest immediately following spawning with increase in the moisture content as the lipid is being consumed. Protein mass within the visceral sac was low in comparison to the muscle mass. It is deemed that carbohydrates, lipids and proteins in the visceral sac play the major role as the source of energy during the development process of the gonads, and used for maintenance of base metabolism when available food is scarce.

• Journal of Hydrogen and New Energy
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• v.24 no.1
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• pp.44-49
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• 2013

Hydrogen penetration into a metal leads to damages and mechanical degradations and its content measurement is of importance. For a precise measurement, a sample preparation procedure must be optimized through a series of studies on sample washing and drying. In this study, two-step washing with organic solvents and thermal soaking in inert gas were tried with a rod-shaped, API X65 steel sample. The samples were machined from a steel plate and then washed in acetone and etyl-alcohol for 5 minute each and dried with compressed air. After then, the samples were thermally soaked in a home-made nitrogen gas chamber during 10 minute at different heat gun temperatures from 100 to $400^{\circ}C$ and corresponding temperature range in the soaking chamber was from 77 to $266^{\circ}C$ according to the temperature calibration. Hydrogen residue in the samples was measured with a hot extraction system after each soaking step; hydrogen residue of $0.70{\pm}0.12$ wppm after the thermal soaking at $77^{\circ}C$ decayed with increase of the soaking temperature. By adopting the heat transfer model, decay behavior of the hydrogen residue was fitted into an exponential decay function of the soaking temperature. Saturated value or lower bound of the hydrogen residue was 0.36 wppm and chamber temperature required to lower the hydrogen residue about 95% of the lower bound was $360^{\circ}C$. Furthermore, a thermal desorption spectroscopy was done for the fully soaked samples at $360^{\circ}C$. Weak hydrogen peak was observed for whole temperature range and it means that hydrogen-related contaminants of the sample surface are steadily removed by heating. In addition, a broad peak found around $400^{\circ}C$ means that parts of the hydrogen residue are irreversibly trapped in the steel microstructure.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.229-234
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• 1982

Environmental factors are known in general to influence much on the development of abscission layer and thereby on shedding of plant parts. The present study was carried out to determine the effect of meterological condition during ripening on the grain shatterability of rice plants at harvest. Different meteorological conditions were obtained by shifting transplanting timing of 40 days old rice seedlings 4 times with a 15 days-interval. Grain shatterability was measured as tensile strength of rice grains: it varied within a range of 214g. to 251g. in a practically non-shattering Japonica variety'Jinheung' and l27.5g. to 204g. in an easy shattering Indica \times Japonica progeny variety'Taeback'. In view of field loss of rice, the variation in tensile strength with time of transplanting and harvest did not matter in Jinheung, but was an important factor in Taeback. In Taeback the tensile strength was significantly correlated positively with mean, maximum and minimum air temperature and relative humidity during a certain period of grain ripening, especially during 30 days period before harvest, but diurnal range of air temperature showed a significant, negative correlation with it. The tensile strength seemed to be more closely related with min. air temperature than max. air temperature, and it was not significantly correlated with radiation amount during any period of pre-harvest. Meteorological effect on grain shatterability may vary with variety, but temperature regime during ripening appears to play major role among the meteorological factors in easy shattering and more thermophilic Indica \times Japonica varieties: lower the temperature, greater the shatterability.

• Journal of Korean Society of Forest Science
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• v.90 no.6
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• pp.717-724
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• 2001

This study was conducted in an attempt to quantify some traits that may be involved in the reproductive process of Pinus thunbergii. During the past 6 years (1995-2000), we surveyed flowering patterns of 60 P. thunbergii clones in a seed orchard which was established in Anmyon-do, 1979. From this survey, we estimated clonal contributions of male and female flowers and sexual asymmetry. Among 60 clones, 18 clones (30%) accounted for 0.37 (1999)~0.46 (1995) of clonal contribution in female flowers and 0.44 (1999)~0.57 (1995) of clonal contribution in male flowers. As compared with the previous reports in other pine species, more clones made contributions to reproductive process in P. thunbergii seed orchard. The relative effective population numbers for females (v♀) varied from 0.59 (1995) to 0.91 (1999) and those for males ( v♂) were between 0.56 (1995) and 0.83 (1998) at gamete level. This showed that the female gametes effectively contribute to the reproductive process more than did the male gametes. The relative effective population numbers at clonal level ($v_b$) were in the range of 0.72 (1995) and 0.93 (1999). More than 73% of the total clones showed values of 0.4~0.6 ($0.5{\pm}0.1$) in maleness index. The values averaged over all the clones were temporally variable with the range of 73% in 1996 and 100% in 2000. The degree of sexual asymmetry ($A_s$) ranged from 0.09 to 0.26. These values were relatively low when compared with those of other trees, suggesting that P. thunbergii seed orchard remains a high level of homogeneity in the number of male and female. All of the various types of effective population numbers were positively correlated with each other while they were negatively correlated with the degree of sexual asymmetry.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.8
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• pp.54-61
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• 2001

A fully on-chip open-drain CMOS output driver was designed for high bandwidth DRAMs, such that its output voltage swing was insensitive to the variations of temperature and supply voltage. An auto refresh signal was used to update the contents of the current control register, which determined the transistors to be turned-on among the six binary-weighted transistors of an output driver. Because the auto refresh signal is available in DRAM chips, the output driver of this work does not require any external signals to update the current control register. During the time interval while the update is in progress, a negative feedback loop is formed to maintain the low level output voltage ($V_OL$) to be equal to the reference voltage ($V_{OL.ref}$) which is generated by a low-voltage bandgap reference circuit. Test results showed the successful operation at the data rate up to 1Gb/s. The worst-case variations of $V_{OL.ref}$ and $V_OL$ of the proposed output driver were measured to be 2.5% and 7.5% respectively within a temperature range of $20^{\circ}C$ to $90^{\circ}C$ and a supply voltage range of 2.25V to 2.75V, while the worst-case variation of $V_OL$ of the conventional output driver was measured to be 24% at the same temperature and supply voltage ranges.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.35-44
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• 2005

Microclimate of Gwangneung forest watershed is characterized by analyzing wind, radiation, profiles of air temperature and humidity, soil and bole temperature, precipitation and soil water content measured at and around the flux tower from April 2000 to September 2003. Mountain-valley wind was prevalent due to the topographic effect with dominant wind from east during daytime and relatively weak wind from west during nighttime. Air temperature reaches its peak in July-August whereas monthly-averaged incoming shortwave radiation shows its peak in May due to summer monsoon. Albedo ranges from 0.12 to 0.16 during the growing season. Monthly-averaged bole temperature is in phase with monthly- averaged air temperature which is consistently higher. Monthly-averaged soil temperature lags behind air temperature and becomes higher with leaf fall. With the emergence of leafage in April, maximum temperature level during midday shifts from the ground surface to the crown level of 15-20m in May. Profiles of water vapor pressure show a similar shift in May but the ground surface remains as the major source of water. Vapor pressure deficit is highest in spring and lowest in winter. Monthly averaged surface soil temperatures range from 0 to 20℃ with a maximum in August. Monthly averaged trunk temperatures of the dominant tree species range from -5.8 to 21.6℃ with their seasonal variation and the magnitudes similar to those of air temperature. Annual precipitation amount varies significantly from year to year, of which >60% is from July and August. Vertical profiles of soil moisture show different characteristics that may suggest an important role of lateral movement of soil water associated with rainfall events.

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.463-470
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• 2015

The angular dependence of active dosimeters, EPD, is analysed and compared with that of passive dosimeters, OSLD, after evaluating their relative response and uncertainty of measurement, where it is known that the personal use of them has been increased recently. There appeared a minor variation for average relative response of OSLD in the horizontal and vertical directions within the range $0^{\circ}{\sim}{\pm}90^{\circ}$, which are 0.97 and 0.95 respectively. The variations of angular dependence in the same situations with OSLD are 0.65 and 0.62, respectively, which also reveals a negligible effect on the overall uncertainty. EPDs within the interval $0^{\circ}{\sim}{\pm}60^{\circ}$ for horizontal and vertical directions are 0.94 and 0.97, respectively. These satisfy the requirements of IEC 61526. Uncertainties about the dependence of direction from horizontal and vertical directions are 0.44, 0.40, respectively. The impact of these uncertainties on the overall uncertainty was negligible. However, we observed a significant change in reactivity: the relative reactivities for $+90^{\circ}$ and $-90^{\circ}$ from the horizontal direction are 0.60, 0.37, while that form vertical direction is 0.06. The direction dependence of OSLD was superior to EPD in the range of $0^{\circ}{\sim}{\pm}90^{\circ}$. There appeared a rapidly changing structural features in EPD response for a certain direction. Therefore, we conclude that concurrent use of passive dosimeters and auxiliary dosimeter provides accurate data for personal dose measurements.

• Journal of the Korean Chemical Society
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• v.17 no.2
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• pp.73-79
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• 1973

The ultrasonic absorption of Dodecyl pyridinium bromide (D.P.B.) in aqueous solution has been measured at $20^{\circ}C$ over a range of frequencies between 0.1 mc and 90 mc and a range of concentrations from 5 to 100 mM. The excess absorption was observed only in the solutions the concentration of which was higher than the critical micellar concentration (c.m.c.) both in the presence and absence of salt. The excess absorption of sound and the relaxation frequencies obtained from the absorption curves show a discontinuity with the variation of the concentration of D.P.B. in the neighborhood of 60 mM. Other properties such as viscosity, conductivity and velocity of sound also exhibit such a change near the same concentration. It is concluded that a change in the properties of the micelles of D.P.B. occurs in the neighborhood of this concentration. The mechanism of the observed ultrasonic excess absorption in attributed to the reaction $M_2{\rightleftarrow}M_1+2Br^-$where$M_2$ and$M_1$are two types of micelles. The rate constants of forward and backward reactions are found to be $6.9 {\times} 10^5 sec^{-1)$and $6.7{\times}10^{10}sec^{-1}mole{-2}$ respectively. Some kinetic characteristics including free energy, enthalpy, entropy and activation energy were calculated.