• Journal of Environmental Science International
• /
• v.26 no.10
• /
• pp.1111-1124
• /
• 2017

This study aimed to understand the distribution of vegetation in the eastern and western sides of the Baekdudaegan (ridge) dividing the Odaesan National Park, as influenced by its topography and climate. The actual vegetation, topography and climate for each side were used in the overlay analysis. The results of the analysis of actual vegetation showed a high distribution rate of Quercus mongolica forest on both the eastern and western sides. On the eastern side, the distribution rate of Pinus densiflora forest and P. densiflora-Q. variabilis forest was high, while the western side had a high distribution rate of deciduous broad-leaved tree forest and Abies hollophylla forest. A clear trend was identified for vegetation distribution with respect to elevation but not with respect to slope or aspect. The results of micro-landform analysis showed that the P. densiflora forests in the ridge and slope and the deciduous broad-leaved tree forest in the valley were respectively distributed with a high ratio. In terms of climate, the eastern side revealed an oceanic climate, with a relatively high average annual temperature, while the western side was characterized by relatively high average annual humidity and average annual precipitation. The distribution rate of P. densiflora forest was found to be high on the eastern side of the mountain range.

• The Journal of the Acoustical Society of Korea
• /
• v.24 no.1E
• /
• pp.21-27
• /
• 2005

Environmental mismatch has been one of important issues discussed in matched field processing for underwater source detection problem. To overcome this mismatch many algorithms professing robustness have been suggested. Feature extraction method (FEM) [Seong and Byun, IEEE Journal of Oceanic Engineering, 27(3), 642-652 (2002)] is one of robust matched field processing algorithms, which is based on the eigenvector estimation. Excluding eigenvectors of replica covariance matrix corresponding to large eigenvalues and forming an incoherent subspace of the replica field, the processor is formulated similarly to MUSIC algorithm. In this paper, by using the ocean experimental data, processing results of FEM and MVDR with white noise constraint (WNC) are presented for two levels of multi-tone source. Analysis of eigen-space of CSDM and FEM performance are also presented.

• The Journal of the Acoustical Society of Korea
• /
• v.25 no.1E
• /
• pp.1-7
• /
• 2006

This study examines the reflection characteristic of a thin transition layer of the ocean bottom showing variability with respect to depth. In order to model the surficial sediment simply, we reduce the Biot model to the depth dependent wave equation for the pseudo fluid using the fluid approximation (weak frame approximation). From the reduced equation, the difference between the inherent frequency dependency of the reflection and the frequency dependency resulting from a thin transition layer is investigated. Using Tang's depth porosity profile model of the surficial sediment [D. Tang et al., IEEE J. Oceanic Eng., vol.27(3), 546-560(2002)], we numerically simulated the reflection loss and investigated the contribution from both frequency dependencies. In addition, the effects of different sediment type and varying depth structure of the sediment are discussed.

• Journal of Navigation and Port Research
• /
• v.36 no.1
• /
• pp.27-34
• /
• 2012

The systematic criteria and rational standard for site selection of marine recreational floating architecture are in urgently need in respect of structural safety, use of facilities, economics of construction and management, relationship with surrounding areas or cities and impact on marine environment. Nevertheless, at present, there is not any study nor guideline for site selection of marine recreational floating architecture which is now being planned and elected at many places of a body of water such as river or coastal area all over the country. Therefore this study is to propose a systematic process and a rational criteria and guideline for site selection of marine recreational floating architecture. Especially the results are suggested in forms of diagrams and tables in order to be utilized so easily by related local governments and individual enterprises.

• Journal of Navigation and Port Research
• /
• v.43 no.5
• /
• pp.328-334
• /
• 2019

Underwater architecture in providing a comfortable living space underwater is mandated to survive prevailing environmental loads, especially hydrostatic ambient water pressure exerted on the structure of individual habitat hulls at depth and hydrodynamic fluctuation of external forces that perturb the postural equilibrium and mooring stability of the underwater housing system, for which the design including the hull shape and mooring system constraint the responses. In this study, the postural stability of a proposed underwater floating housing system with three vertically connected ellipsoidal-shape habitat hulls of different sizes are theorized and calculated for hydrostatic stability, using MATLAB in the volumetric integration of a hull and the weight of operational loads under assumed scenarios. The assumptions made in the numerical method to estimate the stability of the habitat system include the fixed weight of the hulls, and their adjustable loads within operational limits for the set meteorological oceanic conditions. The purpose of this study was to numerically manipulate a) The buoyancy and b) The adjusted center of mass of the system within the range of designed external and internal load changes, by which the effective mooring system capability and postural equilibrium requirements were argued with the quantitative analysis.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.3 s.76
• /
• pp.33-39
• /
• 2007

The more deeply the researches make progress in ocean researches including the seabed resource investigation or the oceanic ecosystem investigation, the more important the role of UUV gets. In case of study on the deep sea, there are difficulties in telecommunications between AUV and ships, and in data communication and recharging. Therefore, docking is required. In AUV docking system, the AUV should identify the position of docking device and make contact with a certain point of docking device. MOERI (Maritime & Ocean Engineering Research Institute), KORDI has conducted the docking testing on AUV ISIMI in KORDI ocean engineering water tank. As AUV ISIMI approachs the docking device, there is some cases of showing an unstable attitude, because the lights which is on Image Frame are disappeared. So we propose the docking algorithm that is fixing the rudder and stem, if the lights on image frame are reaching the specific area in the Image Frame. Also we propose the new docking device, which has a variety of position and light number. In this paper, we intend to solve the some cases of showing an unstable attitude that were found in the testing, which, first, will be identified the validity via simulation.

• Journal of the Society of Naval Architects of Korea
• /
• v.56 no.3
• /
• pp.263-272
• /
• 2019

The aim of this study is to develop a rapid calculation technique of the residual strength in order to prevent sequential events under grounding accidents. Very Large Crude-Oil Carrier (VLCC), Suezmax, and Aframax double hull oil tankers carrying large quantities of crude oil were selected for target structures. The rock geometries are chosen from the published regulation by Marine Pollution Treaty (MARPOL) of the International Maritime Organization (IMO). Oceanic rocks as the most frequently encountered obstruction with ships are applied in this work. Damage condition was predicted using ALPS/HULL program based on grounding scenario with selected parameters, i.e. depth of penetration, damage location and tanker type. The results of the scenarios are quantified to form an empirical formula which can evaluate the residual strength. The proposed formula is validated by applying a series of random grounding scenarios.

• Journal of Navigation and Port Research
• /
• v.36 no.6
• /
• pp.449-458
• /
• 2012

Recently many different floating buildings are planed and constructed in the sea, river, etc. for active use of water spaces. But many problems are occurred in the process of floating building design, construction and management due to the inadequate legal system. This incomplete legal system has become one of the critical factors which are hampering the invigoration of floating buildings. Therefore this study is to suggest preliminary data and improvement directions through a case study with domestic and foreign examples of appropriate laws and law applications concerning floating buildings. As the results of this study the laws related to floating building have to be revised in the directions of qualifying legally floating building as 'building' but not 'ship', designating 'special zone' for floating building site, and applying the established 'building licensing procedure' to floating building also.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.335-338
• /
• 2006

The more deeply the researches make progress in ocean researches including the seabed resource investigation or the oceanic ecosystem investigation, the more important the role of UUV gets. In case of study on the deep sea, there are difficulties in telecommunications between AUV and ships, and in data communication and recharging. Therefore, docking is required. In AUV docking system, the AUV should identify the position of docking and make contact with a certain point of docking device. MOERI (Maritime & Ocean Engineering Research Institute), KORDI has conducted the docking testing on AUV ISIMI in KORDI Ocean Engineering Water Tank. As AUV ISIMI approachs the docking device, it is presented that attitude is unstable, because the lights Which is on Image Frame are disappeared. So we fix the rudder and stem, if the lights on Image Frame are reaching the specific area in the Image Frame. In this paper, we intend to solve the problems that were found in the testing, which, first, will be identified via simulation.

• Journal of Navigation and Port Research
• /
• v.37 no.4
• /
• pp.409-418
• /
• 2013

On the assumption of the rise of sea level, the inundation vulnerabilities on coastal areas of Korea are evaluated in different ways. The propose of this study is to find out the influences of sea level rise caused by global warming at Young-do coastal area, and to suggest the prevention schemes against the flooding damage caused by the sea level rise. The potential rates of sea level rise are assumed and with these rates the inundation vulnerabilities are simulated using CAD program. With the virtual maps, as the results of the previous CAD simulation, this study attempts to suggest the flood prevention schemes for each sector of damage-expected coastal area.