• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.283-293
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• 2008

The objectives of the study were firstly to provide fundamental data for establishment of total maximum daily load (TMDL) management in Ulsan City, and secondly to make practical application of stream health assessment with tolerance range by each species when physiochemical and fish investigations were carried out together. A total of 44 sites in Taehwa River, Hoiya River, Dong Stream, and Cheongryang Stream were selected to monitor water qualities seasonally and fish investigation was performed in August 2006. Among the parameters of water quality, biological oxygen demand (BOD) and dissolved oxygen (DO) related to respiration, total nitrogen (T-N) and total phosphorus (T-P) related to nutrient and eutrophication, and total suspended solids (TSS) and $NH_4$-N were compared with vertical box plot by 8 dominant species. According to the fish investigation, 12 families 33 species were found including endangered species (Pungitius kaibarae) and introduced species (Lepomis macrochirus, Micropterus salmoides), and appearance rate of Korean endemic species was greater in Taehwa River (29.2%) than others. As the results of tolerance range by species, Zacco koreanus, Rhynchocypris oxycephalus, Iksookimia longicorpa, and Squalidus gracilis majimae had limited low range by water quality parameters indicating preference of good water quality. Whereas, Carassius auratus and Pseudorasbora parva were found downstream and urban-streams which were exposed from frequent inflow of pollutants. It concludes that the results help distinguishing sensitive, intermediate, and tolerant species when we evaluate stream health assessment with fish, and further making practical application for conservation and restoration of aquatic ecosystem.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.402-411
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• 2008

Grazing effects of two freshwater shellfish, Unio douglasiae (UNIO) and Cipangoplaudina chinese malleata (CCM), on the hibernal diatom communities in eutrophic water was examined in a laboratory. Two animals having different feeding types used in the study were collected from Keum River (Boryeong, Korea), acclimatized in the artificial management system in a laboratory over at least one month, and starved in a laboratory for 2 days before the experiment. Experimental waters, which dominated by Synedra ulna-Scenedesmus sp. (ca. 80%), was collected from eutrophic lake, Lake Ilgam (Seoul) in Feb., 19, 2008 at AM 10:00, and used in the study after the filtration with 1 mm Nylon mesh. Feeding experiments were largely divided into three kinds of animal treatments; five densities of UNIO (U0, U1, U2, U3, U4) and CCM (C0, C1, C2, C3, C4), and four combined densities of two shellfish (M0, M1, M2, M3). U0 and C0 were control (no addition of UNIO or CCM), U1 or C1 (each animal density at 0.5 ind. $L^{-1}$), U2 or C2 (1.0 ind. $L^{-1}$), U3 or C3 (1.5 ind. $L^{-1}$), and U4 or C4 (2.0 ind. $L^{-1}$), respectively. Four combined treatments were consisted of M0 (no animals), M1 (U1+C3), M2 (U2+C2), and M3 (U4+C1), respectively. Under the presence of animal, the concentration of Chl-a and algal abundance were clearly decreased with the increase of UNIO density and the treated time, while in combined group a strong decrease of algal density showed with the increase of UNIO density. Total phytoplankton density shifted as the similar patterns to that of Chl-a concentration (r=0.6527, p<0.0001), however, there showed the differences following a species. There were strong decreases of dominant species Synedra ulna, Scenedesmus sp., Ankistrodesmus falcatus in UNIO treatment group, Diatoma vulgare in combined group, while Cryptomonas ovata in high density of CCM increased about 20% in algal density. Grazing rates (GRs) based on the concentration of Chl-a was depend on the kind of shellfish and treatment time; a strong feeding of CCM showed in the initial stage, and four hours later, UNIO and combined group with high UNIO density showed the high GRs. Interestingly, faeces production of shellfish was highest in combined group with high density of CCM, while their size over 60 ${\mu}m$ was much higher in production magnitude than that less 60 ${\mu}m$. Collectively, these results suggest that two domestic shellfish and its combined treatment have a strong potential as an effective biological controller of diatom bloom in cold eutrophic waters.

• Korean Journal of Environmental Biology
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• v.26 no.3
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• pp.159-169
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• 2008

This study was aimed to classify the intertidal macrozoobenthic community status after 2 years of Sea Prince oil spill, and oil spill effects along oil spreading track from heavily impacted to unaffected reference site. Field sampling was initiated in late February and continued through November 1998 seasonally, after 2.5 years of oil spill. 7 rocky sampling sites were selected among coastal regions coated and/or affected by the Sea Prince spilled oil. Identified species was 158 species, 65 family, 24 order, 9 class, 5 phylum. Mollusca was the dominant faunal group comprising 100 species (63.3%), and followed by 38 species of Crustacea (24.1%), 12 species of Echinodermata (7.6%), 5 species of Porifera (3.2%), and 3 species of Cnidaria (1.9%). On Dugpo of Sori Island, the fewest species was collected from 28 species to 35 species seasonally among sampling stations. But far away Dugpo toward Gamak Bay, the number of species increased, collecting the maximum on Sohwoenggan Island. At the wreck site of Sori Island, especially the species number of attached animals such as poriferans and anthozoans was very low compared to another site. The density and biomass on the higher tidal zone increased toward the low affected sites, but biomass on middle tidal zone decreased. The invertebrate biomass of study area was dependent on the sessile animals. The major dominant species were small-sized barnacles, Chthmallus challengeri, periwinkles, Littorina brevicula, mussels, Septifer virgatus, and so on. The biomass of C. challengeri and L. brevicula on the higher tidal zone was highest in the wreck site of Sori Island and decreased further and further. However, mussels on the middle tidal zone showed the inverse trends because of the larger individual size of mussel inhabited in Sori Island than those of another sites. As a result of community analysis, the effect of oil spill was not found distinctly. Several ecological indices and cluster analysis did not show the meaningful variation with oil track despite of the conspicuous differences among tidal heights. These indicate that the macrozoobenthic community level of oil spreaded zone recovered in some degree after the Sea Prince oil spill accident, but population or individual levels of dominant sessile animals took more recovery times.

• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.963-974
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• 2015

This study was conducted to determine the effects of organic vegetable cultivation on the soil physical properties in 33 farmlands under plastic greenhouse in Korea. We were investigated 5~8 farms per organic vegetable crops during the period from August to November 2014. The main cultivated vegetables were leafy lettuce (Lactuca sativa L.), Perilla leaves (Perilla frutescens var. Japonica Hara), cucumber (Cucumis sativus L.), strawberry (Fragaria ananassa L.) and tomato (Lycopersicon spp.). We have analyzed soil physical properties. The measured soil physical parameters were soil plough layer, soil hardness, penetration resistance, three soil phase, bulk density and Porosity. The measurement of the soil plough layer, soil hardness and penetration resistance were carried out direct in the fields, and the samples for other parameters were taken using the soil core method with approximately 20 mm diameter core collected from each organic vegetable field. Soil plough layer was average 36 cm and ranged between 30 and 50 cm, and slightly different depending on the sorts of vegetable cultivation. The soil hardness was $0.17{\pm}0.15{\sim}1.34{\pm}1.02$ in the topsoil, $0.55{\pm}0.34{\sim}1.15{\pm}0.62$ in the subsoil. It was not different between topsoil and subsoil, but showed a statistically significant difference between the leafy and fruit vegetables. Penetrometer resistance is one of the important soil physical properties that can determine both root elongation and yield. The increase in density under leafy vegetables resulted in a higher soil penetrometer resistance. Soil is a three-component system comprised of solid, liquid, and gas phases distributed in a complex geometry that creates large solidliquid, liquid-gas, and gas-solid interfacial areas. The three soil phases were dynamic and typically changed in organic vegetable soils under greenhouse. Porosity was characterized as range of $54.2{\pm}2.2{\sim}60.3{\pm}2.4%$. Most measured soils have bulk densities between 1.0 and $1.6gcm^{-3}$. To summarize the above results, Soil plough layer has been deepened in organic vegetable cultivation soils. Solid hardness (the hardness of the soil) and bulk density (suitable for the soil unit mass) have been lowered. Porosity (soil spatial content) was high such as a well known in organic farmlands. Important changes were observed in the physical properties according to the different vegetable cultivation. We have demonstrated that the physical properties of organic cultivated soils under plastic greenhouse were improved in the results of this study.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.3
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• pp.180-190
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• 2014

It has been customary to exclude top 10-20% of velocity profiles in the Acoustic Doppler Current Profiler (ADCP) measurement due to side lobe effects at the boundary. To better understand the mixing in the Yeongsan estuary, the freshwater advection speed (FAS) was recovered from highly contaminated ADCP data near the surface. The velocity profiles were measured by using ADCP at two stations in the Yeongsan estuary during August 2011: one was located in front of the Yeongsan estuarine dam and the other was deployed near Goha Island. The FAS was recovered from the ADCP data set by applying rigorous post-processing methods and compared with the sediment advection speed (SAS). The SAS was determined by the peak time difference of suspended sediment concentration between two stations in the channel, divided by the distance of two stations. The FAS and the SAS showed very similar value when the freshwater discharge was greater than $2.0{\times}10^7$ ton and the SAS was a bit greater when the freshwater discharge was smaller. Since the FAS was on average about 0.8 m/s greater than the velocity at 0.8 of water depth from the bottom, the net discharge, estimated with recovered FAS and integrated over water depth and tidal cycle, was directed seaward during the high discharge contrary to the onshore direction of the net discharge estimated with 0.8 of water depth from the bottom. Moreover, the velocity shear and Richardson number changed when the FAS was used. Thus, the importance of the true FAS is appreciated in the investigation of the surface layer stability. If currents, temperature and salinity were observed for longer time in the future, it could be possible to more accurately understand the formation and decay of stratification as well as the suspended sediment transport processes.

• Journal of Korean Society of Transportation
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• v.33 no.5
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• pp.441-448
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• 2015

This study aims to suggest a reasonable signal operation method for right-turn traffic management. It was found that the right-turn vehicle supplementary signal is currently operated without clear regulations or criteria. It was also analyzed that right-turn supplementary signals are used without consistency, there is a risk of traffic accidents due to the discordance between supplementary signals and traffic signals of forward vehicles, there is a lack of basis for prohibition of a right turn when right-turn vehicle's supplementary signal is red and the flashing red signal is used in a different sense from the law. In order to see the effect of the installed right-turn vehicle supplementary signals on traffic signal violation, a field investigation was conducted. As the result, there was a high proportion of signal violation on the approach lane with right-turn supplementary signals and this means that right-turn supplementary signals hardly influenced the reduction in proportion of signal violation during a right turn. Additionally, a survey was carried out to see if there were differences in driver's interpretation of traffic signals depending on the installation of right-turn supplementary signals. As the result of the survey, there were no differences in interpretation of traffic signals depending on the installation of right-turn supplementary signals or the types of right-turn supplementary signals. A right turn when the signal was red did not lead to serious traffic accidents, so it is thought that there should be a careful consideration of a total ban on a right turn when the signal is red, in order to prevent driver's confusion due to the change of the signal system. Unless there is a disturbance to cars and pedestrians after a temporary stop when the signal is red, there is a need to specify that vehicles must stop temporarily in the Road Traffic Act to facilitate a right turn. What this study finally suggested is to use tri-colored arrow signals for right-turn car supplementary signals to convey a signal to a driver clearly.

• Journal of Veterinary Clinics
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• v.29 no.4
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• pp.309-314
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• 2012

The study was undertaken to evaluate sensitivity and specificity of rapid Avian Influenza (AI) and Newcastle Disease virus (NDV) combo antigen kits from field samples of domestic (broiler and layer chicken, native chicken) and semi-domestic (duck, goose, pigeon and quail) birds of Bangladesh. Samples were collected from naturally infected AI suspected domestic and semi-domestic birds of five different outbreak areas in Bangladesh. From each area two birds were selected for sampling, and from each bird three types of samples (tracheal, cloacal and oro-nasal swabs) were collected. A total of 210 field samples from a total of 70 birds were collected and tested using AI and NDV combo antigen rapid diagnostic kits in the study. All three different samples from a bird showed similar pattern of reaction. Out of 210 samples, 15 samples (5 birds), 63 samples (21 birds) and 27 samples (9 birds) were positive for AIV, NDV and both for AIV and NDV, respectively; whereas the remaining birds were negative for either AIV or NDV in this screening test. Among the five AIV positive, a layer chicken from wet market in Mymensingh, Netrokona, Gibandha and Kurigram and a native chicken from wet market in Kurigram area was positive to AIV. The semi-domestic birds are either positive to NDV or free from both AIV and NDV. This study revealed that the AIV and NDV rapid diagnostic kits could be effectively use to diagnose the respective virus in trachea, oro-nasal and cloacal samples simultaneously. AIV-NDV combo Ag test result clearly indicates that the test kit designed for AIV and NDV could diagnose the disease rapidly with less effort and higher scientific know how which could be used for the detection of AIV and NDV using field samples in large scale.

• Korean Journal of Remote Sensing
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• v.36 no.2_2
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• pp.379-399
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• 2020

The detection of illegal ship is one of the key factors in building a marine surveillance system. Effective marine surveillance requires the means for continuous monitoring over a wide area. In this study, the possibility of ship detection monitoring based on satellite SAR, HF radar, UAV and AIS integration was investigated. Considering the characteristics of time and spatial resolution for each platform, the ship monitoring scenario consisted of a regular surveillance system using HFR data and AIS data, and an event monitoring system using satellites and UAVs. The regular surveillance system still has limitations in detecting a small ship and accuracy due to the low spatial resolution of HF radar data. However, the event monitoring system using satellite SAR data effectively detects illegal ships using AIS data, and the ship speed and heading direction estimated from SAR images or ship tracking information using HF radar data can be used as the main information for the transition to UAV monitoring. For the validation of monitoring scenario, a comprehensive field experiment was conducted from June 25 to June 26, 2019, at the west side of Hongwon Port in Seocheon. KOMPSAT-5 SAR images, UAV data, HF radar data and AIS data were successfully collected and analyzed by applying each developed algorithm. The developed system will be the basis for the regular and event ship monitoring scenarios as well as the visualization of data and analysis results collected from multiple platforms.

• Korean Security Journal
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• no.14
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• pp.367-388
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• 2007

Some of individuals working at various fields of security guard are given the legal right to use a gun to cope with expected risks and crimes. Not only in Korea but also throughout the world, a pistol is being used as a device for the workers of security guard such as the army, the police and intelligence agencies to keep the law and social order. A pistol, which is regarded as the last safety measure of security guard, is easy to carry but, because of its short barrel for high portability, its hit ratio and long-range shooting performance are much lower than ordinary guns. Despite such weak points, a pistol can be a great tool because of its high portability and if the users make steady efforts to improve their skills and, for this reason, it has been being used widely until now. National agency workers' pistol shooting skills depend on several important factors, but for the fast and accurate shooting, the mot important factor is how to aim at the target. Because it takes a relatively longer time to align the sight on the target, the change of the sight alignment method is expected to improve pistol shooting skills a lot. In Korea, however, most of national agency training centers teach the basic aiming method that crosses the foresight and the backsight and aligns the crossing to the target. That is, they teach the sight alignment method for fixed targets. Some agencies in Korea and foreign countries that have used guns more frequently and longer than us are teaching different sight alignment methods as well. Representative ones of them are aiming only with the foresight and pointing shooting. These aiming methods are expected to produce good results against moving targets. While the basic sight alignment method has to cross the foresight and the backsight and then to align the crossing to the target, so takes a longer time than other aiming methods, the other two aiming methods are expected to be effective in fields where both swiftness and accuracy are require. Because domestic agencies are teaching mainly the basic sight alignment method, the present study purposed to examine the effects of different aiming methods on shooting records and ultimately to contribute to national agency workers' operation. For this purpose, we selected 20 policemen from local police commandos under the National Police Agency who were accustomed to pistol shooting and measured their pistol shooting. According to the results, the pointed shooting method showed the best record in 5m short.range shooting. As to hit ratio in 15m shooting, which is relatively long.range for pistol shooting, the basic aiming method showed the best record, but the results of statistical analysis showed that pointed shooting is most superior. Of course, the results were obtained from a group who were used to and skillful in pistol shooting, but they are considered meaningful in that all the police and national agency workers should have such high shooting skills.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.4
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• pp.292-301
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• 2000

To make a better use of the beneficial bacterial inoculants in the agricultural practice, dry forms of bacterial fertilizer or pesticides are prepared with carrier materials. During the drying process of bacterial inoculant, most of the cells face a severe osmotic pressure and dehydration, and die off. Our study describes the effect of osmoprotectants such as trigonelline and trehalose on the survival of bacterial cells in high salt concentration and drying conditions. A fluorescent Pseudomonas, strain SSL3, used in this study, could grow in high salt concentration of upto 5% but the cells could not overcome the growth retardation at over 7% of salt concentration. The addition of trigonelline, even on small amount, in liquid medium containing 4% NaCl was detrimental to the cell. However, the addition of trehalose of upto 10 mM to the liquid medium containing 4% NaCl, enhanced cell growth. The cell growth was retarded when 150mM trehalose was added to the medium. Upon dry formulation of cells, trehalose was added. And the dry cells were inoculated into the soil to determine the effect of osmoprotectants on the survival of the cells. The survival of the cells, both in wet or dry soil, was improved by the addition of trehalose during the dry cell formulation. The positive effect of trehalose on the cell survival at $-20^{\circ}C$ and $-70^{\circ}C$ was oven more pronounced. The FTIR (Fourier transformation infra-red) spectroscopic analysis showed that the change of the 2nd amide group was reduced by adding trehalose to the medium containing 4% NaCl. These results suggest that trehalose can protect the cell membrane from dryness or high concentration of salt, thereby diminishing the sudden change of the protein structure of the cell membrane and, as a consequence, improving the cell survival.