• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.1
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• pp.13-25
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• 2001

Recently there have been increasing demands and desire for the urban open space due to urban development or environmental deterioration. Urban natural parks in Seoul provide citizens with comfortable open space and thus play an important role as learning spaces to experience nature and understand the environment. Accordingly, this study aims to analyze existing vegetation and provide basic data for the conservation and management plans of urban natural parks and education programs. The contents of the study encompass natural environment such as topography, altitude, slope and aspect and botanical ecosystem including the structure of plant communities and tree growth. According to the result of topography analysis, the overall altitude was not high but the slope was relative steep. Vegetation of Seoo Royal Tomb, a urban natural park has been classified into 12 types, and they include; Quercus acutissima community(lowland type), Quercus acutissima community(valley type), quercus variabilis community, Quercus mongolica community, Castanea crenata community, Capinus laxiflora community, Pinus densiflora community(lowland type), Pinus densiflora community(slope type), Robinia pseudo-acacia community, Populos$\times$albaglandulosa community, Pinus rigida community, and Pinus koraiensis community. Based on the survey and analysis results, we have classified the study area into conservation, buffer, and utilization zones for the effective management. This study provides basic data to support the establishment of master plans for urban natural parks by analyzing vegetation conditions at Seoo Royal Tomb, an urban natural park, Based on the results presented in the study, consistent monitoring work needs to be conducted, and elaborate management plans also should be prepared.

• Journal of Environmental Impact Assessment
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• v.20 no.3
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• pp.381-395
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• 2011

Present work aims to establish an integrated management system of environmental data base for nine typical wind holes or air holes in Korea. It basically deals with definition, geographical distribution, morphological pattern, physical characteristics and anthropogenic environments of wind hole to propose systematic preservation strategy of their periglacial landscape and flora, which are known to be sensitive to global warming. Wind hole, in which cool air blows out during the summer, but mild air comes out during the winter from a cave or hole, is frequently found on northwest- and north-facing slopes on the terminal point of steep talus, block field, and block stream, and can be categorized into three types, i.e., talus, cave and sink types. Environmental characteristics of nine wind holes are analyzed on the basis of their geology, landform, climate, soil, hydrology, vegetation, road, footpath, land-use, and management system, and relevant DB are prepared. Wind hole areas with unique landscape and ecological values need to be designated as a nature reserve, and zoning of core, buffer, and transitional zones are required for the multi-dimensional preservation of periglacial landscape and ecosystem. Phytogeographical values of glacial relict plants, including mountain cranberry(Vaccinium vitis-idaea) at its global southernmost limit at Bangnaeri wind hole, Hongchon County, Gangwon Province of Korea are discussed in detail as a floristic refugia in connection with climate change during the Pleistocene Epoch and potential in-situ and ex-situ preservation sites in the future.

• 한국해양학회지
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• v.29 no.2
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• pp.183-187
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• 1994

The oxygen and carbon isotopic compositions of the foraminiferal species, Elphidirm dtigoense and Ammonia beccarii tepida, of the tidal flat in the Gomso Bay of the western coast of Korea have been measured. This work was intended to study the relationship between oxygen and carbon isotopic compositions of the foraminifera and present oceanographic environments, and also the difference between two foraminiferal species. The values of $\delta$/SUP 18/O and $\delta$/SUP 13/C of E. dtigoense varied from - 3.20% to + 0.58% and from - 5.26% to - 0.93%, respectively. The values of $\delta$/SUP 18/O and $\delta$/SUP 13/C of A. beccarii tepida varied from - 1.11% to + 0.61% and from - 2.04% to - 1.40%, respectively. Mo significant variations in these values occur from the samples among the upper, middle and lower tidal zones except for the one from the upper tidal zone that has extremely low value. The difference between the two foraminiferal species was 0.20% and 1.63% in the average values of $\delta$/SUP 18/O and $\delta$/SUP 13/C, respectively. The relationship between $\delta$/SUP 18/O and $\delta$/SUP 13/C values was positive in interspecies of two species.

• Smart Structures and Systems
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• v.30 no.4
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• pp.339-351
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• 2022

Evaluating the current condition of existing structures is of primary importance for economic and safety reasons. This can be addressed by Structural System Identification (SSI). A reliable static SSI depends on well-designed sensor configuration and loading cases, as well as efficient parameter estimation algorithms. Static SSI by the Measurement Error-Minimizing Observability Method (MEMOM) is a model-based deterministic static SSI method that could estimate structural parameters from static responses. In the current state of the art, this method is only applicable when structures are subjected to one loading case. This might lead to lack of information in some local regions of the structure (such as the null curvatures zones). To address this issue, the SSI by MEMOM using multiple loading cases is proposed in this work. Observability equations obtained from different loading cases are concatenated simultaneously and an optimization procedure is introduced to obtain the estimations by minimizing the discrepancy between the predicted response and the measured one. In addition, a Genetic-Algorithm (GA)-based Optimal Sensor Placement (OSP) method is proposed to tackle the OSP problem under multiple static loading cases for the very first time. In this approach, the Fisher Information Matrix (FIM)'s determinant is used as the metric of the goodness of sensor configurations. The numerical examples of a 3-span continuous bridge and a 13-story frame, are analyzed to validate the applicability of the extended SSI by MEMOM and the GA-based OSP method.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2444-2451
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• 2024

This work demonstrates a new sol-gel approach for synthesizing PbO₂-doped zirconia using zircon mineral precursors. The streamlined methodology enables straightforward fabrication of the doped zirconia composites. Comprehensive materials characterization was performed using XRD, SEM, and TEM techniques to analyze the crystal structure, microstructure, and morphology. Quantitative analysis of the XRD data provided insights into the nanoscale crystallite sizes achieved, along with their relationship to lattice imperfections. Furthermore, the gamma-ray shielding capacity for the PbO₂-doped zirconia samples was estimated by the Monte Carlo simulation, which proves an increase in the gamma ray shielding properties by raising the Pb concentration. The linear attenuation coefficient increased between 0.467 and 0.499 cm^-1 (at 0.662 MeV) by increasing the Pb content between 11 and 21 wt%. By increasing the Pb content to 21 wt%, the synthesized composites' lead equivalent thickness reaches 2.49 cm. The radiation shielding properties for the synthesized composites revealed a remarkable performance against low and intermediate γ-ray photons, with radiation shielding capacity of 37.3 % and 21.4 % at 0.662 MeV and 2.506 MeV, respectively. As a result, the developed composites can be employed as an alternative shielding material in hospitals and radioactive zones.

• Journal of Industrial Convergence
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• v.19 no.1
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• pp.17-26
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• 2021

This study was conducted to do in-depth exploration of coroperate employees' learning experiences for workplace under COVID-19. We collected data through depth interviews from August 10th to November 30th, 2020 with five employees of S Energy company, and a qualitative case study was conducted using Ricci's 3-step analysis procedure. As a result, In the process of adapting from the landing of COVID-19, "The Story of a Distant Country," "No More Safe Zones," "Exploring effective responses created by a Sense of Crisis," and "Learning the changed way of work for adaptation." appeared. In addition, It has been found that the experience of learning in the work environment of the With Corona era includes "learning experience for survival from a sense of crisis", "learning experience for adapting to Untact culture", "learning experience through SNS communication", and "competitive learning experience for performance creation". In conclusion, employees have adapted to changes in the workplace environment through various learning experiences, which can enhance workers' ability to cope with crisis situations and can be used as basic data for an effective learning. In the future, we suggested follow-up researches of corporate employees in various fields.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4B
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• pp.339-346
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• 2009

In this study, the flow characteristics of the sea region, where tidal current and shock waves are combined, are identified using a three-dimensional numerical model (Princeton Ocean Model, POM). The model is adopted and applied for simulating the flows of the sea region near the open sections during the seadike closure work of Sihwa Seadike which was closed in 1994. The simulation results show that the shock waves with high velocities propagate through the sections toward the inside and outside of the seadike during the periods of the spring and ebb tides, respectively. It is found that the phenomena of flow separation occur near the shock waves; as the shock waves extend to wider zones after passing the sections, their effects on the tidal current become weak. In addition, the longitudinal velocity profiles of the flows are revealed to be affected by the shock waves. For all the simulations, at the ebb tide, the drawdown of the water levels occurs in front of the open section, respectively, especially, hydraulic jump occurs when simulating the case of maximum difference in water level between the inside and outside of the seadike. As a result, it is thought that the flow characteristics of the sea region dominated by shock waves need to be identified employing three-dimensional analysis approach, which is expected to provide the information for ocean engineering works and facility management.

• Geophysics and Geophysical Exploration
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• v.11 no.3
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• pp.250-262
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• 2008

In order to assess the feasibility of the dipole-dipole electric method to the investigation of metallic ore deposit, both field data simulation and inversion are carried out for several simplified ore deposit models. Our interest is in a vein-type model, because most of the ore deposits (more than 70%) exist in a vein type in Korea. Based on the fact that the width of the vein-type ore deposits ranges from tens of centimeters to 2m, we change the width and the material property of the vein, and we use 40m-electrode spacing for our test. For the vein-type model with too small width, the low resistivity zone is not detected, even though the resistivity of the vein amounts to 1/300 of that of the surrounding rock. Considering a wide electrode interval and cell size used in the inversion, it is natural that the size of the low resistivity zone is overestimated. We also perform field data simulation and inversion for a vein-type model with surrounding hydrothermal alteration zones, which is a typical structure in an epithermal ore deposits. In the model, the material properties are assumed on the basis of resistivity values directly observed in a mine originated from an epithermal ore deposits. From this simulation, we can also note that the high resistivity value of the vein does not affect the results when the width of the vein is narrow. This indicates that our main target should be surrounding hydrothermal alteration zones rather than veins in field survey. From these results, we can summarize that when the vein is placed at the deep part and the difference of resistivity values between the vein and the surrounding rock is not large enough, we cannot detect low resistivity zone and interpret the subsurface structures incorrectly using the electric method performed at the surface. Although this work is a little simple, it can be used as references for field survey design and field data Interpretation. If we perform field data simulation and inversion for a number of models and provide some references, they will be helpful in real field survey and interpretation.

• Korea journal of population studies
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• v.19 no.1
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• pp.93-122
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• 1996

This is a study of the determinants of sexual, contraceptive, and abortion behavior among unmarried female adolescents and young adults, which has emerged as a growing and serious health problem in Korea. As part of a larger project, data were gathered in three export zones: Kuro (Seoul), Kumi (Kyngbuk) Masan Changwon (Kyongnam) ; and the study samples are regrouped into three categories: 1) factory workers, i.e. , the reference group serving as program participants, 2) entertainment workers, and 3) ob-gyn patients. This study indicates that entertainment workers are at highest risk of experiencing premarital sex, STDs, contraceptive failure, unwanted pregnancies, and induced abortion. Of them, 20 percent had STDs as a result of first sexual experience: and about seven tenths had two or more pregnancies due to the adoption of low-efficacy methods. The proportion of those who had ever been pregnant was 60 percent for the group as a whole: 36 percent for the program participants: 64 percent for the entertainment workers ; and 91 percent four the ob-gyn patients. These proportions are exactly the same for abortion in each group, which means that all pregnancies ended in induced abortion. Of the respondents who said that they were sexually active at the time of survey, abortions were very high: 1.6 for the program participants, 2.3 for the entertainment workers, and 1.9 for the ob-gyn patients. About 80 percent of the women had abortions during the first trimester, and two thirds of the first abortions took place between the ages of 20 and 23. About one fourth experienced post-abortion complication, which was highest among the program participants (39 percent). Sixty percent of those with complications visited a hospital or took medicine to treat the problem. Even after the experience of induced abortion, the use of contraception was very low, except among the entertainment workers, whose level of use reached 53 percent. The most obvious recommendation, arising from this research, is that 'good-quality' counselling and family planning services be established under the auspices of both national and local government, particularly targeted for the entertainment workers as well as the factory workers in various textile, electronic, manufacturing, and other industrial sectors. We believe that entertainment sectors should be restructured radically so that young women who work for amusement bars and other entertainment sectors obtain protection from the risk of having unwanted pregnancies, STDs, and induced abortion.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1071-1086
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• 2016

The safety of aircraft can be threatened by environmental factors, such as icing, turbulence, and lightning strike. Due to its adverse effects on aircraft structure and electronic components of aircraft, lightning strike is one of the biggest hazards on aircraft safety. Lightning strike can inject high voltage electric current to the aircraft, which may generate strong magnetic field and extreme hot spots, leading to severe damage of structure or other equipment in aircraft. In this work, mechanism of lightning strike and associated direct and indirect effects of lightning on aircraft were studied. First, on the basis of aircraft lightning regulations provided by Aerospace Recommended Practice (ARP), we considered different lightning waveform and zones of an aircraft. A coupled thermal-electrical computational model of ABAQUS was then used for simulating flow of heat and electric current caused by a lightning strike. A study on fuel tank, with and without lightning protection system, was also conducted using the computational model. Finally, electric current flow on two full scale airframes was analyzed using the EMA3D code.