• Journal of Radiation Protection and Research
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• v.19 no.2
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• pp.121-132
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• 1994

This study concerns about the measurement and the investigation of environmental radiation characteristics which the components and the distribution of exposure rates by terrestrial y-rays in Taegu area. $4^{'}{\phi}{\times}4^{'}$ NaI(T1) scintillation detector with a multichannel analyzer was used in the measurement of y-rays as a part of in-situ spectrometry at twenty eight different locations in this area. The conversion into the exposure rate from the measured ${\gamma}-ray$ spectrum has been carried out leading to a net exposure rate and component ones by $^{40}K,\;^{238}U$ series and $^{232}Th$ series products which are known by the major parts in the terrestrial ${\gamma}-rays$ generally. As a result, the average exposure rate by the terrestrial ${\gamma}-rays$ in Taegu area is $9.4{\mu}R/h$ and the distribution of individual exposure rates shows more or less differences between these locations even after the consideration of diurnal and yearly variations which are always involved in these measurements. The component parts of exposure rates are distributed $^{40}K\;2.9{\sim}4.6{\mu}R/h,\;^{238}U$ series $1.2{\sim}3,\;1{\mu}R/h,\;^{232}Th$ series $2.5{\sim}5.0{\mu}R/h$ over the measured locations.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.217-227
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• 2019

The purpose of this study was to investigate the initial growth, burrowing depth, and relative growth of mud shrimps (Upogebia major and Austinogebia wuhsienweni), living in damaged high density tidal flat shellfish farms form 2008 in the Western coast of Korea. By August, young mud shrimps (Upogebia major), which had settled down on the tidal flats in early May, grew to more than 10 mm in carapace length (CL). At the end of the first year, their CL and total length (TL) increased to 14.21 mm and 42.28 mm, respectively. The inhabiting depth of the young mud shrimps (Upogebia major) increased rapidly up to about 6 months after stocking (5 cm in July, 12.5 cm in September, and 28 cm in November, respectively). The inhabiting depth of adult mud shrimps in their burrows was about 10-93 cm during the year. As results, the analysis of the relative growth between the carapace length (CL) - the total length (TL) and the CL - total wet weight (TWW), the total wet weight of mud shrimps at Boryeong Saho (inner part of the Cheonsu-bay) was estimated to be 1.2-4 g heavier than those of Boryeong Jugyo (Outer part of the Cheonsu-bay) tidal flat. The young mud shrimps primarily grew from April to October. It is therefore crucial to observe whether the settlement of young mud shrimps on tidal shellfish farms from May to June to minimize the damage of shellfish farms by newly stocked young mud shrimps. In addition, it is recommended that young mud shrimps grown in fisheries be harvested before they dig deep into the sediment until early December.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.4
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• pp.305-330
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• 2023

Unlike NATM tunnels, Shield TBM tunnels have split linings. Therefore, the stress distribution of the lining is different even if the lining is under the same load. Representative methods for analyzing the stress generated in lining in Shield TBM tunnels include Non-joint Mode that does not consider connections and a 2-ring beam-spring model that considers ring-to-ring joints and segment connections. This study is an analysis method by Break-joint Mode. However, we do not consider the structural role of segment lining connections. The effectiveness of the modeling is verified by analyzing behavioral characteristics against vibration loads by modeling with segment connection interfaces to which vertical stiffness and shear stiffness, which are friction components, are applied. Unlike the Non-joint mode, where the greatest stress occurs on the crown for static loads such as earth pressure, the stress distribution caused by contact between segment lining and friction stiffness produced the smallest stress in the crown key segment where segment connections were concentrated. The stress distribution was clearly distinguished based on segment connections. The results of static analysis by earth pressure, etc., produced up to seven times the stress generated in Non-joint mode compared to the stress generated by Break-joint Mode. This result is consistent with the stress distribution pattern of the 2-ring beam-spring model. However, as for the stress value for the train vibration load, the stress of Break-joint Mode was greater than that of Non-joint mode. This is a different result from the static mechanics concept that a segment ring consisting of a combination of short members is integrated in the circumferential direction, resulting in a smaller stress than Non-joint mode with a relatively longer member length.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.401-412
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• 2016

It is extremely difficult to apply conventional grouting methods to subsea tunnelling construction in the high water pressure condition. In such a condition, the rapid artificial freezing method can be an alternative to grouting to form a watertight zone around freezing pipes. For a proper design of the artificial freezing method, the influence of salinity on the freezing process has to be considered. However, there are few domestic tunnel construction that adopted the artificial freezing method, and influential factors on the freezing of the soil are not clearly identified. In this paper, a series of laboratory experiments were performed to identify the physical characteristics of frozen soil. Thermal conductivity of the frozen and unfrozen soil samples was measured through the thermal sensor adopting transient hot-wire method. Moreover, a lab-scale freezing chamber was devised to simulate freezing process of silica sand with consideration of the salinity of pore-water. The temperature in the silica sand sample was measured during the freezing process to evaluate the effect of pore-water salinity on the frozen rate that is one of the key parameters in designing the artificial freezing method in subsea tunnelling. In case of unfrozen soil, the soil samples saturated with fresh water (salinity of 0%) and brine water (salinity of 3.5%) showed a similar value of thermal conductivity. However, the frozen soil sample saturated with brine water led to the thermal conductivity notably higher than that of fresh water, which corresponds to the fact that the freezing rate of brine water was greater than that of fresh water in the freezing chamber test.

• Korean Security Journal
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• no.48
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• pp.147-176
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• 2016

Korean Peninsula is surrounded by ocean on three sides. Because of this geographical quality over 97% of export and import volumes are exchange by sea. Foreign ship and international passenger vessels carries foreign tourist and globalization and internationalization increases this trends. Leisure population grows with national income increase and interest of ocean. And accidents and incidents rates are also increases. Korea Coast Guard's jurisdiction area is 4.5 times bigger than our country. The length of coastline is 14,963km including islands. One patrol vessel is responsible for 24,068km and one coast guard substation is responsible for 94km. Efficient patrol activities can not be provided. This research focus on this problem. Analyze the status and trends of maritime crime and suggest efficient patrol activities. To deal with increasing maritime crime rate this study suggest to use geographical profile method which developed early 1900s in USA. This geographical profile analyse the spatial characteristic and mapping this result. With this result potential crime zone can be predicted. One of the result is hot spot management which gives data about habitual crime zone. In Korea National Police Agency adopt this method in 2008 and apply on patrol and crime prevention activity by analysis of different criteria. Korea National Police Agency analyse the crime rate with crime type, crime zone and potential crime zone, and hourly, regionally criteria. Korea Coast Guard need to adopt this method and apply on maritime to make maritime crime map, which shows type of crime with regional, periodical result. With this geographical profiling we can set a Criminal Point which shows the place where the crime often occurs. The Criminal Points are set with the data of numerous rates such as homicide, robbery, burglary, missing, collision which happened in ocean. Set this crime as the major crime and manage the data more thoroughly. I expect to enhance the reinforcement of marine crime using this Criminal Points. Because this points will give us efficient way to prevent the maritime crime by placing the patrol vessel where they needed most.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.2
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• pp.36-48
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• 2015

This study aims to contemplated the enjoying culture of Gyeonghwasejok's garden in late Joseon dynasty. It was track down the behavior from cultural perspective by using recorded in literature. The results were as follows. First, Gyeonghwasejok was the main principal of the garden at Hanyang in Joseon Dynasty. There are established residence in the downtown and make a garden. Garden organizer recognized to fine conditions of residences even crowded downtown. As a result people tried to include habitation and garden culture for preserve their cultural benefit. Secondly, Seongsisanrim culture has appeared of common in site selection of garden for occupies the scenic beauty. Garden was surrounded by scenic beauty. Garden organizer was formed archival culture for owning the beautiful landscape through creation of guguk(九曲), designation of space and lettering on rocks. Thirdly, Formation of the collection culture was placed of various ornaments inside garden. A behaviour of landscape view and ornaments appreciation led to the archival culture such as Won-rim-gi(園林記) and essay(小品文). Moreover, hold a friendship meeting for sharing garden culture. Fourthly, Attention of flowering plants was extended to development of gardening hobby such as fashion of pot-planting, planted to exotic tree. It was know that the plants are recognized as favorite elements by target of appreciation according to introduction of plants inside garden. In addition, facility of horticulture and kitchen garden were placed inside garden. Fifth, Influx of chinese garden culture influenced construction of garden space in late Joseon dynasty. Garden organizer recognizes garden as a ideal space by garden aesthetics that Hojungcheonji(壺中天地). And the imitation of Chinese garden culture such as collecting of Chinese's ornaments has become a high-level culture.

• Korean Journal of Environment and Ecology
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• v.18 no.3
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• pp.306-315
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• 2004

Yangjae stream, stretching through Seocho-gu and Gangnam-gu, is a representative city stream with its environmentally friendly stream makeover project model, launched in 1995. The district of Gangnam-gu, the subject of this study, is under high pressure from the residents for its use as a huge residential areas close to the stream. The study has two main purposes. The first is to identify the condition and characteristic of utilization of Yangjae stream which is currently being increased in use by the stream restoration. Secondly, the study aims to suggest the environment-friendly management to accomplish arrangement of the naturally friendly stream based on the identification survey, The result from the user survey with 303 valid answer sheets show that the people from neighboring residential areas use this stream a lot doing exercising(51.8%) and taking a walk(24.4%) in their free time. Also regular use rate is high, and people are likely to use it alone(30.4%) or as a family(28.4%). With regard to the need of facility increase, even though the respondents required resting places in the shade(80.8%) most, overall, additional introduction of facilities was analyzed as unnecessary(78.8%). safety issue(22.0%) and a lack of convenience facilities(17.6%) and resting places in the shade(16.6%) are pointed as main problems while the users are generally satisfied(59.5%) with the stream. Improving walk-way and planting trees for shade on the slope were designed as a solution for these problems. For securing safety through improvement of walk-way, the scattering of pressure of current walk with building new walk using berms was presented. In order to increase safety on the walk-way(see above figure), the study proposes to build a new walk-way with berms to disperse excessive pressure. It also suggests the tree planting to provide shade in the stream and to make a provision for the planting of forest trees in the current law.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.945-957
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• 2019

In this study, we propose a coarse to fine image registration method for eliminating geometric error between images over agricultural areas acquired using Unmanned Aerial Vehicle (UAV). First, images of agricultural area were acquired using UAV, and then orthophotos were generated. In order to reduce the probability of extracting outliers that cause errors during image registration, the region of interest is selected by using the metadata of the generated orthophotos to minimize the search area. The coarse image registration was performed based on the extracted tie-points using the Speeded-Up Robust Features (SURF) method to eliminate geometric error between orthophotos. Subsequently, the fine image registration was performed using tie-points extracted through the Mutual Information (MI) method, which can extract the tie-points effectively even if there is no outstanding spatial properties or structure in the image. To verify the effectiveness and superiority of the proposed method, a comparison analysis using 8 orthophotos was performed with the results of image registration using the SURF method and the MI method individually. As a result, we confirmed that the proposed method can effectively eliminated the geometric errors between the orthophotos.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.999-1009
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• 2019

The importance of high-resolution sea ice maps of the Arctic Ocean is increasing due to the possibility of pioneering North Pole Routes and the necessity of precise climate prediction models. In this study,sea ice classification algorithms for two deep learning models were examined using Sentinel-1 A/B SAR data to generate high-resolution sea ice classification maps. Based on current ice charts, three classes (Open Water, First Year Ice, Multi Year Ice) of training data sets were generated by Arctic sea ice and remote sensing experts. Ten sea ice classification algorithms were generated by combing two deep learning models (i.e. Simple CNN and Resnet50) and five cases of input bands including incident angles and thermal noise corrected HV bands. For the ten algorithms, analyses were performed by comparing classification results with ground truth points. A confusion matrix and Cohen's kappa coefficient were produced for the case that showed best result. Furthermore, the classification result with the Maximum Likelihood Classifier that has been traditionally employed to classify sea ice. In conclusion, the Convolutional Neural Network case, which has two convolution layers and two max pooling layers, with HV and incident angle input bands shows classification accuracy of 96.66%, and Cohen's kappa coefficient of 0.9499. All deep learning cases shows better classification accuracy than the classification result of the Maximum Likelihood Classifier.

• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.563-581
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• 2010

In this paper, we perform subjective visual quality assessments on UHD video for UHD TV services and analyze the assessment results. Demands for video services have been increased with availabilities of DTV, Internet and personal media equipments. With this trend, the demands for high definition video have also been increasing. Currently, 2K-HD ($1920{\times}1080$) video have been widely consumed over DTV, DVD, digital camcoders, security cameras and other multimedia terminals in various types, and recently digital cinema contents of 4K-UHD($3840{\times}2160$) have been popularly produced and the cameras, beam projects, display panels that support for 4K-UHD video start to come out into multimedia markets. Also it is expected that 4K-UHD service will appear soon in broadcasting and telecommunications environments. Therefore, in this paper, subjective assessments of visual quality on resolutions, color formats, frame rates and compression rates have been carried to provide basis information for standardization of signal specification of UHD video and viewing environments for future UHDTV. As the analysis on the assessments, UHD video exhibits better subjective visual quality than HD by the evaluators. Also, the 4K-UHD test sequences in YUV444 shows better subjective visual quality than the 4K-UHD test sequences in YUV422 and YUV420, but there is little perceptual difference on 4K-UHD test sequences between YUV422 and YUV420 formats. For the comparison between different frame rates, 4K-UHD test sequences of 60fps gives better subjective visual quality than those of 30fps. For bit-depth comparison, HD test sequences in 10-bit depth were little differentiated from those in 8-bit depth in subject visual quality assessment. Lastly, the larger the PSNR values of the reconstructed 4K-UHD test sequences are, the higher the subjective visual quality is. Against the viewing distances, the differences among encoded 4K-UHD test sequences were less distinguished in longer distances from the display.