• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.751-759
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• 2014

Currently, due to global warming, occurrences of extreme climate phenomena such as heat wave, heavy snow, heavy rain, super typhoon are continuously increasing all over the world. Due to these extreme climate phenomena, concrete structures and infrastructures are exposed to serious deterioration and damage. However, researches on construction technologies and standards to confront the climate change generated problems are needed presently. In order to better handle these problems, the validity of the present concrete mixture proportions are evaluated considering wind speed and sunlight exposure time based on climate change record in Seoul, Korea. The specimens cured at various wind speed and sunlight exposure time conditions were tested to obtain their compressive and split tensile strengths at various curing ages. Moreover, performance based evaluation (PBE) method was used to analyze the target strength satisfaction percentage of the concrete cured for the curing conditions. From the probabilistic method of performance evaluation of concrete performance, feasibility and usability of current concrete mix design practice for climate change conditions can be evaluated.

• Journal of the Korean earth science society
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• v.30 no.2
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• pp.210-222
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• 2009

Lightning data, observed from total lightning detection system (TLDS) of KMA, for the recent five years (2002-2006) have been analyzed for temporal and spatial characteristics of frequency, intensity, duration, and flash rate. Lightning frequency varies largely with years (most frequent in 2006) and the lightning during the summer accounts for 75% of total flashes and only 0.6% of lightnings strike in cold season. In rainy season (JJAS), the ratio of positive flashes to negative ones is as low as 0.15, but it increases up to 0.98 in February. The seasonal variation of lightning duration is strongly linked with lightning occurrences, whereas flashes rates show weak seasonal variability. In a daily scale, lightning, on average, occurs more often at dawn (2 am, 5-7 am) and in the mid-afternoon (15 pm), and the lightning at dawn (around 5 am) is most intense during the day. The western inland areas md the West/South Sea show high lightning density during JJAS, whereas eastern part and the East Sea exhibit a low density of lightning. Considering the low ratio of positive flashes (0.15) for the whole analysis domain during summer period, Chungnam and Jeonbuk areas have a high ratio of flashes over 0.4. However, these should be analyzed with much caution because weak positive cloud-to-cloud discharges can be regarded as cloud-to-ground flashes. The western inland also exhibits long annual flash hours (15-24). And the W3st Sea has high flash rates as a result of large density and low flash hours. The most frequent time of lightning occurrence over most inland areas lies between mid-afternoon and early-evening, whereas mountainous and coastal areas, and the northern Kyoungki and Hwanghae provinces show the maximum lightning strikes in the morning and at dawn, respectively.

• Journal of Environmental Policy
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• v.4 no.1
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• pp.1-19
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• 2005

On January 1, 2005, the Special Act on Metropolitan Air Quality Improvement, known as the Blue Sky 21 Program, entered into force. This Special Act is aimed at reducing the annual average concentrations of $PM_{10}$ and $NO_2$ to $40{\mu}g/m^3$ and 22ppb, respectively, from their current levels of $76{\mu}g/m^3$ and 36ppb, within the next 10 years. While the main focus of the Act is to reduce $PM_{10}$ and $NO_2$ emissions, the government also anticipates that these reductions would lessen high ozone occurrences and improve visibility. However, reducing local PM emissions would not decrease $PM_{10}$ concentrations as much as expected since other significant sources, such as continental inflow and/or secondary formation from photochemical reactions, exist. This is corroborated by the fact that $PM_{10}$ in the greater Seoul Metropolitan area during the ozone season is mostly in the form of $PM_{2.5}$, which is secondarily formed on a regional scale. Furthermore, many modeling results indicate so-called '$NO_x$ disbenefits,' referring to the fostering of an increase in ozone concentrations from a decrease in $NO_x$ emissions, over an extensive area. In this paper, the current status of air quality in the Seoul Metropolitan area is reviewed, and several other issues, including the effect of long-range transport, photochemical characteristics, and tasks for successful implementation of the Special Act are discussed.

• Journal of Biomedical Engineering Research
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• v.18 no.3
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• pp.273-283
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• 1997

Electrogastrography(EGG), the cutaneous recording of the myoelectrical activity of the stomach using surface electrodes, is attactive due to its non-invasiveness. Despite many attempts made over the decades, analysis of surface EGG has not led to identification of contraction-related electrical response activity of the stomach that would help the clinician to diagnose motility disorders of the stomach. We propose feasible methods to detect the gastric contraction by spectrum analysis and vector analysis of the surface EGG signal. A running spectral analysis(RSA) based on the fast Fourier transform (FFT) was applied to the filtered EGG signal. The powers of dominant frequency and its harmonics were compared with gastric contraction signals such as the strain gauge signal from the gastric serosa in dog or the antropyloric pressure in human. And we also carried out vector analysis of the filtered EGG signals obtained from three paired electrodes. The amplitude and direction of the calculated EGG vector were analyzed and compared with the gastric contraction signals. From the spectrum analysis, we found that the increase of the power of the first harmonic of the dominant frequency was highly correlated with the gastric contraction. And from the vector analysis of the EGG signal, we found a typical change of the amplitude and direction of the EGG vector, which can indicate occurrences of the gastric contraction.

• The Korean Journal of Quaternary Research
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• v.20 no.1 s.26
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• pp.39-50
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• 2006

Jeonjangri site of Geochang area is located in the Geochang Basin, and lies on the river terrace of upstream part of Hwang River. Fluvial deposits are well distributed at the northern and southern walls of trench 2(district 2) in the Jeonjangri archeological site. This study aims to interpret the occurrences of fluvial sedimentary deposits on the basis of grain size analysis and palynological analysis in the representative sections of Jeongjangri site. The sedimentary profile shows that the upper units are typified by paleosols with soil wedge formed at about $25,000{\sim}30,000yr$ B.P, and the lower units are characterized by reddish brown muddy sands, organic muds and sand/gravel downwards in the profile. Particularly palynological study on the organic muds of southern wall section showed a result that lower unit is dominant with grass vegetation, and upper unit with Alnus-Quercus-Pinus vegetation. The former is interpreted to be formed at $60,000{\sim}50,000yr$ B.P (stadial), while the latter at $80,000{\sim}70,000yr$ B.P. In general broad-leaved/coniferous mixed forests are mostly dominant in Jeongjangri site and the climate was presumed to be cool temperate at that time.

• Journal of the Korean association of regional geographers
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• v.6 no.2
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• pp.57-69
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• 2000

The purpose of this study is to identify distributional characteristics of autumn droughts in occurrence frequency and to analyze synoptic characteristics on the surface pressure fields and 500hPa levels for autumn droughts in Korea. The regional distributions of autumn droughts in occurrence frequency vary according to the monthly regional distributions of the precipitation variabilities in Korea. In september, the southwestern and the mid western parts of Korean Peninsula have high rate of drought frequency, while the eastern coast regions have low rate of it. It means that the regional distribution of the drought frequency in september indicates west-high and east-low pattern. In October, the regional distribution of the drought frequency shows low variations on regions, but in November the inland areas have low rate of drought frequency, whereas the coastal areas have high rate of it. Negative anomalies appear on the surface and 500hPa level, around Korean Peninsula during the drought period of early autumn. Positive height anomalies areas are extended from the Sea of Okhotsk to the central part of the North Pacific Ocean. It indicates that the occurrence frequencies of blocking high and ridge are high around the Sea of Okhotsk. When the pressure system, such as migratory anticyclone, stays around the Korean Peninsula, a drought occurs. In late autumn drought, the positive anomalies appear in the west and the negative anomalies in the east are generated, respectively and therefore, zonal wind is strong around Korean Peninsula. In consequence, occurrences of droughts in early autumn have a different mechanism from those of late autumn.

• Economic and Environmental Geology
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• v.34 no.2
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• pp.227-241
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• 2001

Several $Co_2$-rich springs in the Chungcheong area, Le., the Angsung spring, the Chojung spring, the Myungam spring, the Bukang spring and the Daepyung spring have been long known for their particular water chemistry. The occurrences of these springs are closely related to the geologic structure of Mesozoic granite such as dyke swarms, fault zones and the geologic boundary between granite and its adjacent gneiss. The $Co_2$-rich water samples show a high $Co_2$ concentration ($P_{CO2}$ 0.25 atm to 0.99 atm), weak acidic pHs and the electrical conductivity ranging from 101 to 2,950 ${\mu}$S/cm. The $Co_2$-rich water samples are classified into the Ca-$HC0_3$ type and the Ca(Na)-$HCO_3$) type in chemical composition. Environmental isotopic data $^{2}H/^{1}H, ^{18}O/^{16}O$) indicated that $Co_2$-rich water was meteoric origin. The ${\delta}^{13}C$ values of $Co_2$-rich water range from -3.1$\textperthousand$ to -6.8$\textperthousand$ PDB. The values indicate that $H_2CO_3^0$ and $HC0_3^-$ of the water samples are mainly originated from a deep-seated source and partly contributed from carbonatc minerals. The major minerals determining the chemistry of $Co_2$-rich watcr arc probably the carbonate minerals which are present as veins and secondary minerals, and the plagiocalse in granite and gneiss.

• Economic and Environmental Geology
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• v.42 no.1
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• pp.1-8
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• 2009

The Haman mineralized area is located within the Cretaceous Gyeongsang Basin along the southeastern part of the Korean peninsula. Almost all occurrences in the Haman area are representative of copper-bearing polymetallic hydrothermal vein-type mineralization. Within the area are a number of fissure-filling hydrothermal veins which contain tourmaline, quartz and carbonates with Fe-oxide, base-metal sulfide and sulfosalt minerals. The Gunbuk, Jeilgunbuk and Haman mines are each located on such veins. The ore and gangue mineral paragenesis can be divided into three distinct stages: Stage I, tourmaline + quartz + Fe-Cu ore mineralization; Stage II, quartz + sulfides + sulfosalts + carbonates; Stage III, barren calcite. Equilibrium thermodynamic data combined with mineral paragenesis indicate that copper minerals precipitated mainly within a temperature range of $350^{\circ}C$ to $250^{\circ}C$. During early mineralization at $350^{\circ}C$, significant amounts of copper ($10^3$ to $10^2\;ppm$) could be dissolved in weakly acid NaCl solutions. For late mineralization at $250^{\circ}C$, about $10^0$ to $10^{-1}\;ppm$ copper could be dissolved. Equilibrium thermodynamic interpretation indicates that the copper in the Haman-Gunbuk systems could have been transported as a chloride complex and the copper precipitation occurred as a result of cooling accompanied by changes in the geochemical environments ($fs_2$, $fo_2$, pH, etc.) resulting in decrease of solubility of copper chloride complexes.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.2
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• pp.113-119
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• 2011

Safe operation and maintenance of engineered dry storage systems for spent fuel from nuclear power plants basically depends on adequately adopted design requirements. The most important design target of the system are those which provide the necessary assurances that spent fuel can be received, handled, stored and retrieved without undue risk to health and safety of workers and the public. To achieve these objectives, the design of the system incorporates features to remove spent fuel residual heat, to provide for radiation protection, and to maintain containment over the lifespan of the system as specified in the design specifications. The features also provide for all possible anticipated operational occurrences and design basis events in accordance with the design basis as guided by the designated regulations. The general performance requirements of a projected storage system are introduced in this paper. The storage system is designed to store fuel assemblies in associated with designated regulatory requirements. Small increases/decreases in maximum burnup can be adjusted with cooling time. These variations are compensated for by a corresponding small site-specific increase/decrease in the design basis-cooling period, as long as the maximum heat load and radioactivity of loaded fuel assemblies are met. Generic design basis events considered for the storage system are summarized. Shielding and radiological requirements along with mechanical and structural are derived in this study.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.5_6
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• pp.273-279
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• 2003

Hypercube multicomputers have been drawing considerable attention from many researchers due to their regular structure and short diameter. One of keys to the performance of Hypercube is the efficiency of communication among processors. Among several communication patterns, multicast is important, which is found in a variety of applications as data replication and signal processing. As the number of processors increases, the probability of occurrences of fault components also increases. So it would be desirable to design an efficient scheme that multicasts messages in the presence of faulty component. In fault-tolerant routing and multicast, there are local information based scheme, global information based scheme and limited information based scheme in terms of information. In general, limited information is easy to obtain and maintain by compressing information in a concise format. In this paper, we propose a new routing scheme and a new multicast scheme using recently proposed fully reachability information scheme and new local information scheme. The proposed multicast scheme increases multicast success possibility and reduce deroute cases. Experiments show that multicast success possibility can increase at least 15% compared to previous method.