• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.833-847
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• 2021

The horizontal porous baffle and its effect as an anti-slosh device have been investigated intensively in a swaying and rolling rectangular tank. To accurately assess the level at which porous baffles reduce liquid sloshing, the Matched Eigenfunction Expansion Method (MEEM) has been utilized as an analytical tool. The velocity potentials in the horizontal baffle-covered fluid region are expressed by the sum of the homogeneous and particular solutions to avoid solving the complex dispersion equation. By applying an equivalent linearized quadratic loss model, the nonlinear algebraic equation is derived and solved by implementing the Newton-Raphson iterative scheme. To prove the validity of the present theoretical model, a series of experiments have been conducted with different centered horizontal porous baffles with varying porosities and submerged depths in a swaying and rolling rectangular tank. Reasonably good agreements are obtained regarding the analytical solutions and the experiment's findings. The influence of porosity, submerged depth, and length of a centered horizontal porous baffle on anti-slosh performance have been analyzed, especially at resonance modes. The developed predictive tool can potentially provide guidelines for optimal design of the horizontal porous baffle.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1067-1074
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• 2022

An architect creates his/her design to meet owner's requirements. Floor plans, perspective drawings, and scale models are used in order for the owner to choose the design. The tools are a little helpful for communication between the architect and the owner in case the owner does not know architecture. The scale models are good, but it is hard to make scale models while design is in progress. 3D CAD is a good tool for communication, but it is time-consuming and requires high-performance computer hardware. Augmented reality is able to show 3D virtual models that are updated by the architect with smart devices such as a smart phone and a tablet PC. The owner frequently reviews the updated design anytime anywhere. This study proposes a method to use augmented reality for architectural design and construction management. The method supports the communication between the owner, the architect and the contractor to review updated designs, and to complete the building project. 3D models expressed in augmented reality are created using SketchUp with 2D drawings for building construction. An Android application implementing augmented reality is developed by Qualcomm Vuforia and Unity on smart devices. Drawings as markers and 3D models are connected in Unity. And functions that temporarily hide unnecessary parts can be implemented in C# programming language. If an owner, an architect, or a contractor looks at a smart phone on a 2D drawing, he/she can identify building elements such as 3D buildings or columns on a screen. This can help communication between them.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.118-124
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• 2024

A neural network is utilized for preprocessing of de-noizing in electrocardiogram signals, retinal images, seismic waves, etc. However, the de-noizing process could provoke increase of computational time and distortion of the original signals. In this study, we investigated a neural network architecture to analyze measurement data without additional de-noizing process. From the dynamical behaviors of DNA in aqueous solution, our neural network model aimed to predict the mole fraction of each DNA in the solution. By adding white noise to the dynamics data of DNA artificially, we investigated the effect of the noise to neural network's predictions. As a result, our model was able to predict the DNA mole fraction with an error of O(0.01) when signal-to-noise ratio was O(1). This work can be applied as a efficient artificial intelligence methodology for analyzing DNA related to genetic disease or cancer cells which would be sensitive to background measuring noise.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.4
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• pp.87-98
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• 2015

The natural monument forests (no.374) located at Pyeongdae-ri in Jeju island are described and classified by using phytosociological methods and numerical analysis. The purpose of this paper is to identify the ecological character of Torreya nucifera forests between natural habitat and artificial habitat, as well as their spatial and phytogeographical distribution in the Korea. The comparison of forests between Pyeongdae-ri and other regions was analyzed by using a non-metric multidimensional scaling analysis (NMDS) and hierarchical clustering. On the basis of the 12 phytosociological $relev{\acute{e}}s$, the vegetation of T. nucifera dominant forest in Jeju island was arranged in one syntaxon (Alangium platanifolium-Torreya nucifera community included typicum and one subcommunity) within Camellietea. The community of T. nucifera dominant forests were characterized floristically and ecologically. We discussed diagnostic species with references, and proposed a few important diagnostic species (Ilex crenata for. microphylla, Acer palmatum, Zingiber mioga, Mercurialis leiocarpa, Osmorhiza aristata, Mecodium wrightii etc.) to explain condition of the habitat and synecological character. The communities were described by concerning their edaphical and syndynamical niche; we discussed their total distribution in Korea. In most forests they are widespread in Korean peninsular and their distribution is primarily determined by artificial plantation and periodical management. The forests consisted of T. nucifera have developed from natural environment element and artificial management. As a result they have very unique characters with the floristic, structural characterization and distribution. Furthermore, we identified that they need to apposite management for sustainability.

• The Journal of the Acoustical Society of Korea
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• v.37 no.1
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• pp.31-38
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• 2018

Based on the measured data in the south western sea of Jeju Island during the SAVEX15(Shallow Water Acoustic Variability EXperiment 2015), the effect of internal waves on the PPD (Predictive Probability of Detection) of a sonar system was analyzed. The southern west sea of Jeju Island has complex flows due to internal waves and USC (Underwater Sound Channel). In this paper, sonar performance is predicted by probabilistic approach. The LFM (Linear Frequency Modulation) and MLS (Maximum Length Sequence) signals of 11 kHz - 31 kHz band of SAVEX15 data were processed to calculate the TL (Transmission Loss) and NL (Noise Level) at a distance of approximately 2.8 km from the source and the receiver. The PDF (Probability Density Function) of TL and NL is convoluted to obtain the PDF of the SE (Signal Excess) and the PPD according to the depth of the source and receiver is calculated. Analysis of the changes in the PPD over time when there are internal waves such as soliton packet and internal tide has confirmed that the PPD value is affected by different aspects.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.5
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• pp.105-112
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• 2017

In order to analyze the effect of street trees on human thermal sensation(thermal comfort) in summer, microclimatic data were measured and analyzed at sunny and shaded locations of two deciduous broadleaf and three broadleaf evergreen species of street trees. As a result, the mean differences by species in air temperature, relative humidity and wind speed were small: $0.2{\sim}1.5^{\circ}C$, 0.9~5.3% and $0.1{\sim}0.5 ms^{-1}$, respectively, but the mean difference in the mean radiant temperature was great, $27.1^{\circ}C$. In the results of physiological equivalent temperature(PET) and universal thermal climate index(UTCI), which are human thermal sensation(thermal comfort) indexes, the shaded locations by the trees showed mean reduction rates of 21.2~31.3% in the PET compared with the sunny location, which are equivalent to 1.5~2.5 levels of thermal perception. Also, 12.7~20.0% in the UTCI was reduced by the trees' shadows, which is equivalent to 1~1.5 levels of heat stress. In addition, although the broadleaf evergreen trees had 5% greater mean reduction in PET than that of the deciduous broadleaf trees, the Zelkova serrata that belonged to the deciduous broadleaf trees showed the equivalent thermal reduction effect as the broadleaf evergreen trees because of the high density of branches and leaves. Therefore, the mean radiant temperature and the density of the crown(branches and leaves) were the main influences in thermal modification by these street trees in summer.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.38 no.3
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• pp.64-74
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• 2020

The significance of Boseong Tea Agriculture System lies in its harmonious coexistence with the surrounding environment, producing high quality teas and maintaining its biodiversity. Boseong Tea Agriculture System has been inscribed as Korea's Important Agricultural Heritage System (KIAHS) in 2018, but the Aging Society of tea farmers is threatening the conservation and succession of tea farming of the region. The study suggests designation of Boseong Tea Agriculture System as one of Globally Important Agricultural Heritage System (GIAHS), objecting conservation and succession of Boseong Tea Agriculture System. The study has reviewed GIAHS, KIAHS, Boseong Tea Agriculture System and surveyed tea farmers of Boseong for 3 months from March to May, 2020. The survey method includes face to face interview, phone interview (ones couldn't be reached for face to face interview) and in-depth interview of community leaders and experts, verifying the Aging Society status in Boseong tea agricultural industry. The survey result includes the following. Average age of Boseong tea farmers is 69.4 years old. Family tea-farming over two generation is 36% (54 household), and 79.4% (119 household) depends on 90% of income from tea production. The in-depth interview shows the aging tea farming society is most serious concern of tea farmers and GIAHS designation will support reliability and recognition of Boseong tea, helping conservation and succession of Boseong Tea Agriculture System. GIAHS designation will enhance and share the value of Boseong Tea Agriculture worldwide and be able to inherit the heritage for our future generation.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.3
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• pp.12-21
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• 2019

In order to investigate the effect of various pavement materials (artificial grass, natural grass, and clay sand) on the human thermal environment, the microclimate data in early autumn (air temperature, humidity, wind speed, and shortwave and longwave radiation) were measured and compared on each surface. The mean air temperature, humidity and wind speed of the pavement materials did not differ significantly and showed the greatest difference in the mean radiant temperature. Natural grass, which has the highest albedo, has the highest amount of shortwave radiation. The artificial turf had the highest surface temperature and the highest amount of longwave radiation. In the human thermal environment index PET, artificial grass > clay sand > natural grass. Natural grass had a maximum 2/3 level lower and a mean 1/2 level lower in PET as compared to artificial grass. The clay sand pavement had a maximum 2/3 level lower and a mean 1/3 level lower than the artificial grass. Natural grass had a maximum 1/3 level lower than the clay sand pavement. Their UTCIs showed smaller differences than the PETs. Therefore, it is necessary to carefully choose materials from the planning stage when designing outdoor spaces, including playgrounds.

• Korean Journal of Environmental Biology
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• v.36 no.3
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• pp.412-423
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• 2018

In this study, we investigated the distribution and habitat of Tscherskia triton from 2014 to 2016 in Jeju Island. Nine individuals of T. triton were observed and captured from four habitat sites. Most of the habitats were of the natural and rural type, and urban type coexisted in some of the areas. The natural type of habitat comprised of forests, shrubs, and grasslands. The habitat of T. triton ranged vertically from 102 m in lowland to 742 m in a mountainous area and was not observed in altitude over 1,000 m. Small brooks, dry streams or wetlands were found to be located nearby the habitat of T. triton. The T. triton was distributed mainly in areas with natural vegetation and artificial plantation in company with the upper story vegetation on the ground of intact or incomplete layer structure, or the area with the relatively large distribution of shrubs and long grassland. The presence of roads and forest paths in these habitats suggested that the T. triton can thrive in areas with human disturbance. The designation of Halla Mountain National Park in Jeju Island as a conservation area prevents damage or loss of the habitat due to any artificial development. However, frequent human disturbances occurring in grassland is tolerated by small mammals. Therefore, in order to help T. triton maintain a stable population density, it is essential that various types of the habitat should be conserved in the middle mountain areas and the grasslands in lowlands should be well protected.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.2
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• pp.1-22
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• 2022

The modification effects of street trees on outdoor thermal comfort in summertime according to tree planting types and road direction were analyzed using a computer simulation program, ENVI-met. With trees, the air temperature and wind speed decreased, and the relative humidity increased. In the case of mean radiant temperature (T_mrt) and human thermal sensation, physiological equivalent temperature (PET) and universal thermal climate index (UTCI), there was a decrease during the daytime. The greatest change among the meteorological factors by trees happened in Tmrt, and PET and UTCI showed similar patterns with T_mrt·The most effective tree planting type on thermal comfort modification was low tree height, wide tree crown, high leaf area index, and narrow planting interval (LWDN). T_mrt, PET and UTCI showed a large difference depending on shadow patterns of buildings and trees according to solar altitude and azimuth angles, and building locations. When the building shade areas increased, the thermal modification effect by trees decreased. In particular, results on the east and west sidewalks showed a large deviation over time. When applying the LWDN, the northwest, west and southwest sidewalks showed a significant reduction of 8.6-12.3℃ PET and 4.2-4.5℃ UTCI at 10:00, and the northeast, east and southeast sidewalks showed 8.1-11.8℃ PET and 4.4-5.0℃ UTCI at 16:00. On the other hand, when the least effective type (high tree height, narrow tree crown, low leaf area index, and wide planting interval) was applied, the maximum reduction was up to 1.8℃ PET and 0.9℃ UTCI on the eastern sidewalks, and up to 3.0℃ PET and 0.9℃ UTCI on the western ones. In addition, the difference in modification effects on T_mrt, PET and UTCI between the tree planting types was not significant when the tree effects were reduced by the effects of buildings. These results can be used as basic data to make the most appropriate street tree planting model for thermal comfort improvement in urban areas in summer.