• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.731-743
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• 2018

In bio-jet fuel production, selecting operating conditions of hydro-upgrading is of great importance to make iso-Paraffin rich hydrocarbons with carbon distribution including jet fuel range. Herein, iso-Paraffin rich biofuel including jet fuel range hydrocarbons ($C_8-C_{16}$) is produced from simultaneous cracking and isomerization using n-Paraffin rich hydrocarbon derived from hydrotreated vegetable oil over 0.5 wt..% Pt/Zeolite catalyst. We report and analyze the yields and compositions in the produced hydrocarbons affected by various operating conditions, such as reaction temperature, reaction pressure, molar ratio of reactants, and weight hourly space velocity. Aforementioned operating conditions not only can help interpret the reaction dynamics of hydro-upgrading, but also further produce bio jet-fuel after distillation.

• Journal of Korea Multimedia Society
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• v.16 no.6
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• pp.678-688
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• 2013

Different Different from a single attack, in DDoS Attacks, the botnets that are distributed on network initiate attacks against the target server simultaneously. In such cases, it is difficult to take an action while denying the access of packets that are regarded as DDoS since normal user's convenience should also be considered at the target server. Taking these considerations into account, the DDoS botnet detection system that can reduce the strain on the target server by detecting DDoS attacks on each user network basis, and then lets the network administrator to take actions that reduce overall scale of botnets, has been implemented in this study. The DDoS botnet detection system proposed by this study implemented the program which detects attacks based on the database composed of faults and abnormalities collected through analyzation of hourly attack traffics. The presence of attack was then determined using the threshold of current traffic calculated with the standard deviation and the mean number of packets. By converting botnet-based detection method centering around the servers that become the targets of attacks to the network based detection, it was possible to contemplate aggressive defense concept against DDoS attacks. With such measure, the network administrator can cut large scale traffics of which could be referred as the differences between DDoS and DoS attacks, in advance mitigating the scale of botnets. Furthermore, we expect to have an effect that can considerably reduce the strain imposed on the target servers and the network loads of routers in WAN communications if the traffic attacks can be blocked beforehand in the network communications under the router equipment level.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.195-204
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• 2016

In this paper, the applicability and usefulness of windprofiler input data were investigated to generate three dimensional wind field. A logical diagnostic model CALMET with windprofiler data at ten sites and with weather forecasting model WRF output was evaluated by statistically comparing with the radiosonde data at eight sites. The horizontal wind speed from CALMET simulated with hourly windprofiler data is in good agreement with radiosonde observations within 1.5 m/s of the root mean square error, especially local circulation of wind such as sea breeze over the coastal region. The root mean square error of wind direction ranged $50^{\circ}{\sim}70^{\circ}$ is due to the wind direction error from the windprofiler polluted by ground clutters. Since the exact wind can be produced quickly and accurately in most of the altitude with windprofiler data on CALMET, we expect the method presented in this study to be useful for the monitoring of safe environment as well as weather in the coastal zone.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.10
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• pp.1403-1406
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• 2005

The present study was undertaken to study the effect of thermal stress on sexual behaviour of superovulated ewes. Fourteen adult Bharat Merino ewes with an average body weight of 29.4${\pm}$2.34 kg were randomly allocated into two groups of 7 each. All the animals were grazed on natural pasture in the morning and evening hours and housed in shed during night. Animals of Group-1 were housed in shed from 10:00 to 16:00 h while the animals of Group-2 were exposed to thermal stress in a hot chamber ($40^{\circ}C$ /6 h/day). All the animals were offered drinking water once a day at 16:30 h. Meteorological observations i.e. dry bulb, wet bulb, minimum and maximum temperature were recorded daily inside the shed as well as in hot chamber throughout the experimental period. For superovulation of animals, standard protocol developed at the Institute, using FSH (Ovagen 5.4 mg in eight injections) and PMSG (200 IU) was followed. Various sexual behaviour parameters (circling, tail fanning, head turning, standing and approaching to ram) and estrus incidence (onset of estrus and estrus duration) were observed in both the groups. The different estrus symptoms were graded subjectively on arbitrary scale of 0-5 where 0 representing no sexual behaviour (0%) and 5 representing maximum intensity in sexual behaviour (100%). Estrus was detected with the help of a marked aproned ram of proven vigor at six hourly intervals. The average percent values for sexual behaviour parameters recorded in Group-1 and Group-2 animals were 53.7${\pm}$3.76 vs. 41.1${\pm}$2.18 for circling, 71.8${\pm}$5.42 vs. 49.0${\pm}$4.41 for tail fanning, 64.7${\pm}$3.30 vs. 44.5${\pm}$4.34 for head turning, 90.1${\pm}$3.16 vs. 75.8${\pm}$4.02 for standing and 63.8${\pm}$4.8 vs. 41.9${\pm}$4.58 for approaching to ram. Animals exposed to thermal stress had significantly lower values of these sexual behaviour parameters. The animals kept in shed exhibited estrus earlier (25.4${\pm}$1.12 h) and duration was higher (37.7${\pm}$1.59 h) as compared to animals exposed to thermal stress i.e. 30.6${\pm}$1.16 h and 31.7${\pm}$3.57 h, respectively. The findings of the study indicate that thermal stress reduces the intensity of sexual behaviour in ewes and may result in failure of the animal to mate and conceive.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.2
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• pp.169-182
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• 2007

To evaluate the possibly potent role of Asian Dust (AD) on the long range transport of Hg, statistical analyses were carried out using the hourly concentration data of gaseous elemental mercury (Hg) along with relevant environmental parameters. For the purpose of this study, Hg data were collected from Yang-Jae monitoring station in Seoul, Korea during Sept. 1997 to June 2002. During the study period, Hg concentrations in non-AD period ranged from $0.03\;to\;32.70\;ng\;m^{-3}$ with a mean $5.27{\pm}3.06\;ng\;m^{-3}$, while those in AD period from $1.79\;to\;32.60\;ng\;m^{-3}$ with a mean $5.20{\pm}3.06\;ng\;m^{-3}$. The air quality during AD were typically deteriorated by enhanced PM10 mass concentration (by $2{\sim}5$ times) compared to non-AD period, however comparison of the Hg concentration data indicates that they are not critically distinguished between events of AD and non-AD, except for the high minimum level of Hg during AD. The results of correlation and factor analysis also indicated somewhat complex patterns; in the case of AD events, Hg and $SO_{2}$ were assorted concurrently into a same factor. Evidence collected from this study thus suggests that long-range transport of Hg, if occurring, is unlikely to raise statistically Hg concentration levels such as seen during AD event. However, in nighttime of winter season, Hg concentrations are higher during AD (along with PM10 levels) than non-AD period. Although such observations suggest the effect of long range transport on the enhancement of Hg concentrations, more deliberate analysis may be required to track down the effect of such mechanism in relation with various factors including the air mass transport route.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.2
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• pp.225-241
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• 2007

A closed flux chamber system was used for measuring major greenhouse gas (GHG) emission from tideland and/or wetland soils in estuarine area at Saemankum, Kunsan in southwestern Korea during from months of February to June 2006. Hourly averaged GHG soil emissions were measured two to three times a day during the ebb tide hours only. Site soils were analyzed for soil parameters (temperature, pH, total organic contents, N and C contents in soil) in the laboratory. Soil GHG fluxes were calculated based on the GHG concentration rate of change measured inside a closed chamber The analysis of GHG was conducted by using a Gas Chromatography (equipped with ECD/FID) at laboratory. Changes of daily, monthly GHGs' fluxes were examined. The relationships between the GHG emissions and soil chemical contents were also scrutinized with respect to gas production and consumption mechanism in the soil. Soil pH was pH $7.47{\pm}0.49$ in average over the experimental period. Organic matter contents in sample soil was $6.64{\pm}4.98\;g/kg$, and it shows relatively lower contents than those in agricultural soils in Kunsan area. Resulting from the soil chemistry data, soil nitrogen contents seem to affect GHG emission from the tidal land surface. The tidal soil was found to be either source or sink for the major GHG during the experimental periods. The annual average of $CH_{4}\;and\;CO_{2}$ fluxes were $0.13{\pm}0.86\;mg\;m^{-2}h^{-1}\;and\;5.83{\pm}138.73\;mg\;m^{-2}h^{-1}$, respectively, which will be as a source of these gases. However, $N_{2}O$ emission showed in negative flux, and the value was $-0.02{\pm}0.66\;mg\;m^{-2}h^{-1}$, and it implies tidal land surface act as a sink of $N_{2}O$. Over the experimental period, the absolute values of gas fluxes increased with soil temperature in general. Averages of the ambient gas concentration were $86.8{\pm}6.\;ppm$ in $CO_{2},\;1.63{\pm}0.34\;ppm\;in\;CH_{4},\;and\;0.59{\pm}0.15\;ppm\;in\;N_{2}O$, respectively. Generally, under the presence of gas emission from agricultural soils, decrease of gas emission will be observed as increase in ambient gas concentration. We, however, could not found significant correlation between the ambient concentrations and their emissions over the experimental period. There was no GHG compensation points existed in tide flat soil.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.6
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• pp.563-580
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• 2010

In 2009 the Korea Ministry of Environment announced 'A Comprehensive Plan for the Improvement of Sewer Service in Rural Area' aiming at reduction of the sewer service gap between urban and rural areas as well as improvement in the residential environment of the rural area. According to the plan, the sewer system supply rate for the rural area is expected to reach up to 75% until 2015 with the budget of 4.7 trillion won (Korean currency). It is not certain, however, that the increase in the sewer system supply rate will accompany improvement of water quality in receiving water because several veiled problems that can occur in small-scale sewer treatment plants are poorly addressed in the plan. In this study, those issues for the small-scale sewer treatment plants and their solutions were discussed based on a case study in which we investigated 19 treatment facilities at two rural regions in Gyeonggi province. This study also included strategies useful for the plan. From the results of investigation, some problems, e.g., high hourly variations but low in flowrates and low mass loading were commonly identified. Although operation parameters in sewer treatment plants require to be modified depending on the mass loading, most of the plants were operated with the initial design parameters which causes the decrease of removal efficiency. In the intensive diagnosis, we arranged and applied solutions (e.g., flow equalization, air on/off time control, etc) to the two selected plants and found out improvement of effluent water quality, especially organic matters (COD and SS) and T-N with better denitrification performance.

• The Journal of the Korea Contents Association
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• v.15 no.3
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• pp.192-198
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• 2015

Checked out by the moving vehicle health checks for patients, practitioners, and the increase in radiation dose outside the vehicle, but an investigation into the leakage of radiation can still be negligible. In this study, through experimental results were as follows: Dose that occurs most often where the leak in the right door $1.14{\pm}1.75mR/h$, X-ray generator in terms of proximity to the top $0.65{\pm}1.25mR/h$, X-ray generator and away to the bottom in terms $0.91{\pm}1.25mR/h$, the adjacent rear detector in the upper part $96.98{\pm}158.88mR/h$ dose of the leak appeared in various locations. By measuring position from the rear of the adjacent detector $67.48{\pm}97.03mR/h$ dose had the highest leakage into. Generating device for diagnosis of radiation safety regulations regarding the maximum leakage dose per week, but all met back when it is displayed in the leakage dose Hourly rates do not ignore the leakage radiation dose were measured. Therefore, a mobile health screening in a vehicle outside of the leakage radiation dose to the liver and move on we are not interested twelve barrier leakage radiation dose of defense has a chance to re-evaluate the standards required, and move the vehicle health check using the X-ray increases as the dose per hour, depending on the criteria for choosing the appropriate measures that will require effort.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.1
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• pp.39-45
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• 1997

Subtidal zonation of a cumacean Bodotria biplicata was investigated in the sandy shore surf zone of Dolsando, southern Korea. Three replicate samples were taken with a sledge net at three sites, such as the surface and bottom of 1 m depth and waters edge, at hourly intervals over the neap and spring tide cycles on January 1993 (n=225). B. biplicata, the most dominant cumacean in this area, exhibited peak density at the bottom while about $0.6\%$ of total catch was collected at the surface. Mean density during the neap tide cycle was slightly higher than that during the spring tide cycle. The depth of subtidal zone influenced the total catch of B. biplicata. The changes in density were related to the depth of subtidal zone rather than day-night cycle or ebb-flood tide. The results obtained in this study suggest that the diel vertical migration is not distinct. During both neap and spring tide cycles, B. biplicata attained a density maximum at the same level of about 90 cm below lower low water (LLW). It is likely, therefore, that this species performs shore- and seaward horizontal migration fortnightly. The speed and distance of migration may be directly related to the beach slope and tide range. Ontogenetic differences in subtidal distribution were observed. Juveniles and manca larvae tended to occur lower areas than the adults. Such differences may reduce intraspecific competition for diets.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.1
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• pp.86-96
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• 2013

The realtime monitoring of radon ($^{222}Rn$) concentrations has been carried out from Gosan site, Jeju Island for three years of 2006~2008, in order to evaluate the background level and timely variational characteristics of atmospheric radon. The mean concentration of radon measured during the studying period was $2965mBq/m^3$ with its annual mean values in the range of $2768{\sim}3124mBq/m^3$. The relative ordering of the seasonal mean concentrations was seemed to vary such as winter ($3578mBq/m^3$) > fall ($3351mBq/m^3$) > spring ($2832mBq/m^3$) > summer ($2073mBq/m^3$). The monthly mean concentrations were in the order of Jan>Feb>Oct>Nov>Dec>Mar> Sep>Apr>May>Jun>Aug>Jul, so that the highest January value ($3713mBq/m^3$) exceeded almost twice as the July minimum ($1946mBq/m^3$). The hourly concentrations in a day showed the highest level ($3356mBq/m^3$) at around 7 a.m., increasing during nighttime, while reaching the lowest ($2574mBq/m^3$) at around 3 p.m. From the backward trajectory analysis for a continental fetch of radon, the high concentrations (10%) of radon matched with the air mass moving from the Asia continent to Jeju area. In contrast, the low concentrations (10%) of radon were generally correlated with the air mass of the North Pacific Ocean. In comparison by sectional inflow pathways of air mass, the radon concentrations were relatively high from the north China and the Korean peninsula.