• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.1
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• pp.55-61
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• 2015

When a radiation detector is applied to the measurement of the radioactivity of high-level of radioactive materials or the rapid response to the nuclear accident, several collimators with the different inner radii should be prepared according to the level of dose rate. This makes the in-situ measurement impractical, because of the heavy weight of the collimator. In this study, an IRIS collimator was developed so as to have a function of controlling the inner radius, with the same method used in optical camera, to vary the attenuation ratio of radiation. The shutter was made to have the double tungsten layers with different phase angles to prevent the radiation from penetrating owing to the mechanical tolerance. The performance evaluation through the MCNP code was conducted by calculating the attenuation ratio according to the inner radius of the collimator. The attenuation ratio was marked on the outer scale ring of the collimator. It is expected that when a radiation detector with the IRIS collimator is used for the in-situ measurement, it can change the attenuation ratio of the incident photon to the detector without replacing the collimator.

• Journal of Astronomy and Space Sciences
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• v.22 no.3
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• pp.283-292
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• 2005

Ionosphere is deeply coupled to the space environment and introduces the perturbations to radio signal because of its electromagnetic characteristics. Therefore, the status of ionosphere can be estimated by analyzing the GPS signal errors which are penetrating the ionosphere and it can be the key to understand the global circulation and change in the upper atmosphere, and the characteristics of space weather. We used 9 GPS Continuously Operating Reference Stations (CORS), which have been operated by Korea Astronomy and Space Science Institute (KASI) , to determine the high precision of Total Electron Content (TEC) and the pseudorange data which is phase-leveled by a linear combination with carrier phase to reduce the inherent noise. We developed the method to model a regional ionosphere with grid form and its results over South Korea with $0.25^{\circ}\;by\;0.25^{\circ}$ spatial resolution. To improve the precision of ionosphere's TEC value, we applied IDW (Inverse Distance Weight) and Kalman Filtering method. The regional ionospheric model developed by this research was compared with GIMs (Global Ionosphere Maps) preduced by Ionosphere Working Group for 8 days and the results show $3\~4$ TECU difference in RMS values.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.224-236
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• 2017

This study analyzed the characteristics of traffic accidents among elderly drivers according to area type in Gyeonggido(urban areas, urban-rural complex areas, and rural areas). Traffic accidents caused by unsafe driving are common in all three types of areas. In urban areas and urban-rural complex areas, traffic accidents were more frequent due to traffic violations and intersection accidents, while rural areas were more affected by central lines. Urban areas and urban-rural complex areas require simpler signal exposures, such as a simple straight line, left turn, or straight line and left turn signal rather than complex signal operations, such as overlaps in a signal operation. Improvement of non-signal intersections and unprotected traffic signal processing is also needed. In order to prevent the intrusion of the central line in rural areas, the center line guard rail should be prevented from penetrating the center line, and the influence of the vehicle headlamp should be reduced in the opposite direction. It is necessary to improve the visibility by using fluorescent letters to enlarge the font size of traffic signs and road signs, particularly to increase visibility at night and prevent traffic accidents at sunset. Minimal, simplified should be provided rather than complex phrases and information.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6610-6617
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• 2013

This study examined the current and future Indoor Air Quality (IAQ) control device markets and analyzed the recent studies on indoor air pollutantr emoval to develop a new technology for fine dust control. Currently, the mechanical filter technique occupies the bulk of the IAQ control market but the electronic technique is emerging as an alternative to control fine dust efficiently. Among the gaseous VOCs and fine dust particles contaminating the indoor air quality, fine dust particles are more problematic because they threaten human health by penetrating deep into the body and producing secondary contaminants by chemical reaction with VOCs. The electronic IAQ control device using dielectrophoretic and electrostatic forces is a good option for public spaces where many people pass, and at the same time, it needs to consider temperature, humidity, and the particle properties of specific areas to highlight the control efficiency. Electronic-related technology is expected to be used widely in many public/private spaces wherever a dust-free environment is required.

• Journal of the Korean Geophysical Society
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• v.6 no.3
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• pp.165-177
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• 2003

The purpose of this paper is to analyze the behavior and to study the safety evaluation of the Unmun Dam located in Cheongdo-Gun of GyeongBuk Province, Korea. For this purpose, soil analyses including boring data, geophysical surveys were conducted. In this paper, especially many geophysical methods were adopted to configure out the subsurface situation of dam. Applied geophysical methods were: 1) electric resistivity survey, 2) high frequency magnetotelluric (HFMT) survey, 3) ground penetrating radar (GPR) survey, 4) seismic refraction survey, 5) seismic cross-hole tomography survey, and 6) high frequency impedance (ZHF) survey. Each of geophysical surveys were analyzed and joint analyses between geophysical surveys were also performed to deduce the more reliable subsurface information of Dam by using the features and characteristics of each geophysical survey. Since many defects, such as gravel and weathered rock blocks in the dam core, and lots of amounts of leakage, by boring analyses were found, reinforcement by compaction grouting system (CGS) has been conducted in some range of dam. Some geophysical data and data of geotechnical gauges were also used to confirm the effects of reinforcement. Electric resistivity, EM, GPR, ZHF, seismic refraction and seismic tomography surveys show that left side of dam is weak, which means the possibility of existence of gravel, rock block, water and cavities in the core of dam. This result coincides with the boring data. Especially, electric survey after reinforcement shows that even the right side of the dam has been deformed by the strong pressure during the reinforcement itself. As a conclusion, some problems in the dam found. Especially, the dam near spillway shows the high possibility of leakage. It should be pointed out that only the left side of he dam has not a leakage problem. As a whole, the dam has problems of weakness, because of unsatisfactory construction. It is strongly recommended that highly intensive monitoring is required.

• Geophysics and Geophysical Exploration
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• v.23 no.3
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• pp.117-130
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• 2020

Noises can distort acquired geophysical data, leading to their misinterpretation. Potential noises sources include anthropogenic activity, natural phenomena, and instrument noises. Conventional denoising methods such as wavelet transform and filtering techniques, are based on subjective human investigation, which is computationally inefficient and time-consuming. Recently, many researchers attempted to implement neural networks to efficiently remove noise from geophysical data. This study aims to review and analyze different types of neural networks, such as artificial neural networks, convolutional neural networks, autoencoders, residual networks, and wavelet neural networks, which are implemented to remove different types of noises including seismic, transient electromagnetic, ground-penetrating radar, and magnetotelluric surveys. The review analyzes and summarizes the key challenges in the removal of noise from geophysical data using neural network, while proposes and explains solutions to the challenges. The analysis support that the advancement in neural networks can be powerful denoising tools for geophysical data.

• Journal of the Korean Wood Science and Technology
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• v.41 no.3
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• pp.201-210
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• 2013

The purpose of this study was to examine the species of 117 wooden elements which were used in the Daewungjeon Hall (National Treasure No. 805, constructed in A. D. 1659) of Bukjijangsa Temple, Daegu, Korea. Pillars were identified as 5 red pines (hard pines; most likely, Pinus densiflora S. et Z.), 2 Cerris section of subgenus Lepidobalanus (deciduous oaks) and 3 Tsuga spp. Hwalju columns were 3 Abies spp. and 1 red pine. Head-penetrating ties were 8 red pines and 1 Cerris sp.; Pyeongbang, 3 red pines and 6 Cerris spp. Purlins were identified as 17 red pines, 16 Cerris spp. and 1 Tsuga sp. Angle rafters were 3 red pines and 1 Cerris sp., and end angle rafters, 2 red pines, 1 Zelkova serrata and 1 exotic hard pine. All of brackets (31 woods), jangyeo (4) and deot-chunyeo (2) were identified as red pines. As a whole, red pines (70.1%) and Cerris (22.2%) were major species used in the Daewungjeon Hall of Bukjijangsa Temple. Tsuga, Abies and exotic hard pines seem imported woods used for recent repairs.

• Journal of Trauma and Injury
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• v.23 no.1
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• pp.21-28
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• 2010

Purpose: In Korea, most abdominal penetrating wounds are caused by stab wounds rather than gun-shot wounds. However, not many studies have been performed on stab injuries and their epidemiologic characteristics. Disagreements of opinions of obligatory surgical exploration and conservative treatment exist, and this subject is still being debated. Therefore, the authors studied the epidemiologic characteristics of abdominal stab wound patients visiting the emergency department and reviewed the proportion of patients that received nontherapeutic surgery and conservative treatment. Methods: This study included patients visiting the emergency department with abdominal stab wounds. A retrospective chart review was done on the abdominal stab wound patients. Sex, age, cause of injury, location of wound, initial vital signs, operation results, injured organs and CT & LWE results were reviewed. Results: The median age of the 121 patients was 40.9 years, of these patients, 88 were males, of which 52 (43.0%) were drunken. Of the patients that received non-therapeutic operations, only 3 patients (15.0%) were drunken, significantly lower than the therapeutic operation group. For the location of the wound, most patients were injured in the right and left upper quadrants, 27 patients each. The most common injured organ was the small bowel; 13 patients were injured in the small bowel. With abdominal CT scans and local wound explorations together, the results exhibited a sensitivity of 97%, a specificity of 44%, a positive predictive value of 56%, and a negative predictive value of 95%. Conclusion: In our study, the sensitivity was 97% when CT & LWE were performed together; thus we can conclude that CT and LWE can be used together to select the treatment method. Although in our study, the surgical indications in abdominal stab wound patients is not sufficient, our results showed a higher rate of nontherapeutic surgery compared to previous studies. Therefore, more research is needed to prevent unnecessary laparotomies in hemodynamically-stable patients without symptoms.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.891-901
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• 2016

By comparing test blasting data experimented in three layered-structure polymorphic grounds to a geological profile, influence of blast vibration with respect to uncontrollable ground characteristics was analyzed. Inefficient blast have been performed without sufficient verifications or confirmations because insufficiencies with regard to experiments and data of blasting engineering on the layered structures to be irregularly repeated clinker layer consisted of volcanic clastic zones. It is difficult to quantify N values of clinkers within test blasting region because they have diverse ranges, or coverages. An absolute value of attenuation coefficient N in a field, estimated by blasting vibration predictive equation (SRSD), are lesser than criteria of a design instruction, meaning that vibrations caused by blast can spread far away, and the vibrational characteristics of blasting test No.1, indicating relatively small values, inferred by the geological profile, pressures of gas by the explosion may be lost into a widely distributed clinker layers by penetrating holes resulted from blast into vicinity of clinker layers located in bottom of soft rock layers at the moment of blast. As a result, amounts of spalling rocks are decreased by almost half. Also, ranges of primary frequencies in the fields are identified as similar to those of natural frequency of typical structures.

• Korean Journal of Environment and Ecology
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• v.18 no.3
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• pp.288-296
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• 2004

This study was conducted from March to October 2003 to investigate the distribution status and environmental index of naturalized plants at 14 sites at rivers penetrating the downtown area of Gwangju Metropolitan City. The flora consisted of 309 taxa, 76 families, 211 genera, 273 species, 35 varieties and one form, while the naturalized plants consisted of 46 taxa, 14 families, 36 genera, 44 species and two varieties. The dominant species of Gwangju-cheon were nine taxa. Panicum dichotomiflorum, Rumex crispus, Chenopodium album, Trifolium repens, Veronica persica, Ambrosia artemisiifolia var. elatior, Aster pilosus, Bidens frondosa and Taraxacum offici-nale. The dominant species of Hwangryong River were five taxa: Rumex crispus, Trifolium repens, Oenothera odorata, Ambrosia artemisiifolia var. elatior and Erigeron canadensis. At Yeongsan River appeared 16 dominant species: Patspalum distichum, Ckenopodium ficifolium, Lepidium apetalum, Erigeron annuus and Xanthium strumarium in addition to the same dominant species of Gwangju-cheon and Hwangryong River The Urbanization Index (UI) was 17.2% and the Naturalized Index (NI) was 14.9% at urban rivers of Gwangju. The naturalized plants consisted of 16 taxa, which originated in both Europe and North America. Based upon the UI and NI, the urban rivers and their riversides must be considered a major corridor for the invasion of naturalized plants.