Mineral dust in the polar snow plays an important role both in the climate system of the Earth and in global biogeochemical cycles. Analysis of the concentration and the particle size distribution of mineral dust has been carried out in the snow from the Antarctic surface snow and the Greenland snowpit. Among the various particle size determination techniques, a Multisizer 3 Coulter Counter in a class 100 clean bench counted all particles between 1.1 and $30.0{\mu}m$ with a $50{\mu}m$ aperture tube. The aperture tube size, the concentration of electrolytes and the accuracy of the particle size distribution were determined in this study. The number concentrations from the Antarctic surface snow were 81,843 particles $mL^{-1}$, but those from the Greenland snowpit were 10,666 particles $mL^{-1}$. In the volume distribution, the distributions of mineral dust in both the Antarctic surface snow and the Greenland snowpit showed lognormal distribution in the size interval 1.1 to $6.0{\mu}m$ with the mode, 3.562 and $3.836{\mu}m$, respectively. The analysis technique using a coulter counter for mineral dust could be used for reconstructing paleoclimates from polar ice cores.

This study aims to analyze causality among Wando abalone producer prices by size using a vector autoregressive model to expiscate the leading-price of Wando abalone in various price classes by size per kg. This study, using an analytical approach, applies a unit-root test for stability of data, a Granger causality test to learn about interaction among price classes by size for Wando abalone, and a vector autoregressive model to estimate the statistical impact among t-1 variables used in the model. As a result of our leading-price analysis of Wando abalone producer prices by shell size using a VAR model, first, DF, PP, and KPSS tests showed that the Wando abalone monthly price change rate by size differentiated by logarithm were stable. Second, the Granger causality relationship analysis showed that the price change rate for big size abalone weakly led the price change rate for the small and medium sizes of abalone. Third, the vector autoregressive model showed that three price change rates of t-1 period variables statistically, significantly impacted price change rates of own size and other sizes in t period. Fourth, the impulse response analysis indicated that the impulse responses of structural shocks for price change rate for big size abalone was relatively more powerful in its own size and in other sizes than shocks emanating from other sizes. Fifth, the variance decomposition analysis indicated that the price change rate for big size abalone was relatively more influential than the price change rates for medium and small size abalone.

The purpose of this study is to estimate the economic value and productivity achieved through a reduction in fishing vessels engaged in coastal and offshore fisheries. We found that the value of increasing catch by types in offshore and coastal fisheries was about 17,338 billion won. To examine the economic value, a cost-benefit analysis was applied. This is based on the total cost of vessel reduction (4,576 billion won) assumed to be invested equally each year for five years. BCR and NPV with a discount rate (5.5%) were used to compare the profit of fishery activities in offshore and coastal areas. The model results showed that the NPV and BCR in offshore and coastal fisheries was 5,522 billion won and 2.340 respectively.

Artificial islands, installations and structures have been used as a major means for ocean development and management since the early 20th century. The International legal regime to regulate the man-made offshore structures also have evolved and the UN Convention on the Law of the Sea (UNCLOS) acts as a basic international instrument for that purpose. Although the Convention includes more detailed provisions on man-made offshore structures, there are some legal issues regarding jurisdiction of coastal State on the man-made offshore structures in the Exclusive Economic Zone (EEZ) or on the Continental shelf. For this reason, this article begins by reviewing the 1958 Convention on the Continental shelf and the UNCLOS by focusing on the EEZ and the Continental shelf regime governing the man-made offshore structures. It next examines some controversial international legal issues that have emerged from the regulation of man-made offshore structures in the EEZ or on the Continental shelf. This is followed by a review of the Korean domestic laws regulating artificial islands, installations and structures in the EEZ or on the continental shelf. Finally, it closes by summarizing the findings of the above examinations, and suggests some recommendations for future works.

In early 1990s, the Korean government has launched a deep-sea research program to secure the stable long-term supply of strategic metallic minerals including Cr, Cu and Ni. Through the pioneering surveys, Korea registered $150,000km^2$ of Mn-nodule field in the Clarion-Clipperton area, the NE equatorial Pacific to the international sea-bed authority (ISA) in 1994. Following the ISA exploration code, the final exclusive exploration area of $75,000km^2$ was assigned in 2002, based on results of eight-year researches of chemico-physical properties of nodules, bottom profiles and sediment properties. Since that time, environmental studies, mining technical developments including robot miner and lifting system and establishment of smelting systems were accompanied with the detailed geophysical studies to decipher the priori mining area until 2009. Major points of the recent Korea Mn-nodule program are deployed on a commercial scale until 2015. In order to meet the goals, we developed a 1/5 scaled robot miner compared to commercial one in 2012 and performed a mining test at the water depth of 1,370 m in 2013. In addition, detailed 25,000 scaled mining maps in the priori area, which can provide operation roots of the miner, will be prepared and an environmental-friendly mining strategy will be pursued based on the environmental impact test and environmental monitoring.

Korea contract Mn-nodule field in the NE equatorial Pacific is composed of seven sectors with average water depths of 4,513-5,025 m. Of the various factors controlling the properties of Mn-nodule, it seems that water depth is likely connected to the chemical composition and occurrence of nodules. To test whether such an assumption held in each sector, we reviewed previous research data accumulated since 1994 for one of the northern sectors (hereafter KR1) where there are stark contrasts in water depth. High-resolution seabed mapping clearly separates a northern part (KR1N) from a deeper southern part (KR1S), cutting across in the middle of the KR1. In addition, significant volcanic activities forming numerous seamounts are distinctive especially in KR1N. In terms of nodule occurrence, manganese nodules in KR1S are comparatively larger (2-4 cm) with a discoidal shape, while those in KR1N are generally small (<2 cm) with poly-lobate and irregular shapes. Nodules in KR1N also have lower Co, Cu, Mn and Ni, and higher Fe contents. The spatial separation in nodule characteristics might be caused by volcanic activities in KR1N rather than water depth contrast. During the formation of the seamounts in KR1N, rock fragments and volcanic ashes as new nuclei of the nodules would have been continuously generated. As a result, the nodules could not grow larger than 2 cm and display the shapes of a newbie (i.e., irregular and poly-lobate shapes). Moreover, significant Fe supply from volcanic activities probably decreases the Mn/Fe ratio, which may lead to the KR1 nodules being misinterpreted as a hydrogenic in origin compared to other sectors where a high Mn/Fe ratio is present.

The surface sediments from the manganese nodule exploration area of Korea in the Clarion-Clipperton fracture zone were investigated to understand the resource potential of and emplacement mechanism for rare earth elements (REEs). The sediments are categorized into three lithological units (Unit I, II and III from top to bottom), but into two groups (Unit I/II and Unit III) based on the distribution pattern of REEs. The distribution pattern of REEs in Unit I/II is similar to that of Post-Archean Australian Shale (PAAS), but shows a negative Ce anomaly and enrichment in heavy REEs (HREEs). In Unit III, the HREE enrichment and Ce anomaly is much more remarkable than Unit I/II when normalized to PAAS, which are interpreted as resulting from the absorption of REEs from seawater by Fe oxyhydroxides that were transported along the buoyant plume from remotely-located hydrothermal vents. It is supported by the PAAS-normalized REE pattern of Unit III which is similar to those of seawater and East Pacific Rise sediments. Meanwhile, the PAAS-normalized REE pattern of Unit I/II is explained by the 4:1 mixing of terrestrial eolian sediment and Unit III from each, indicating the much smaller contribution of hydrothermal origin material to Unit I/II. The studied sediments have the potentiality of a low-grade and large tonnage REE resource. However, the mining of REE-bearing sediment needs a large size extra collecting, lifting and treatment system to dress and refine low-grade sediments if the sediment is exploited with manganese nodules. It is economically infeasible to develop low-grade REE sediments at this moment in time because the exploitation of REE-bearing sediments with manganese nodules increase the mining cost.

A 570 cm-long sediment core was retrieved at $9^{\circ}57^{\prime}N$ and $131^{\circ}42^{\prime}W$ in 5,080 m water depth from the northeast equatorial Pacific and its stratigraphy was established with $^{10}Be/^9Be$ and paleomagnetic measurements. Successive AF demagnetization reveals eight geomagnetic field reversals. In the reference geologic time scale, the eight reversal events correspond to an age of about 4.5 Ma. However, $^{10}Be/^9Be$-based age yields 9.5 Ma at a depth of 372 cm. Such a large discrepancy in determined ages is attributed to an extremely low sedimentation rate, 0.4 mm/kyr on average, of the study core and resultant loss or smoothing of geomagnetic fields. The composite age model reveals a wide range in the sedimentation rate - varying from 0.1 to 2.4 mm/kyr. However, the sedimentation rate shows systematic variation depending on sedimentary facies (Unit II and III), which suggests that each lithologic unit has a unique provenance and transport mechanism. At depths of 110-80 cm with a sedimentation rate of about 0.1 mm/kyr, ancient geomagnetic field reversal events of at least a 1.8 Myr time span have not been recorded, which indicates the probable existence of a hiatus in the interval. Such a sedimentary hiatus is observed widely in the deep-sea sediments of the NE equatorial Pacific.

The benthic environmental impact experiment addresses environmental impacts at a specific site related to deep-sea mineral resource development. We have acquired several tens of multi- or box core samples at 31 sites within the Benthic environmental Impact Site (BIS) since 2010, aiming to examine the basic properties of surficial deep-sea sediment as a potential source for deep-water plumes. In this study, we present the geochemical properties such as major elements, rare earth elements (REEs), and heavy metal contents at the BIS. Such proxies vary distinctly according to the Facies association. The lithology of all core sediments in the BIS corresponds to both Association Ib and Association IIIb. The vertical profiles of some major elements ($SiO_2$, $Fe_2O_3$, CaO, $P_2O_5$, MgO, MnO) show noticeable differences between Association Ib and IIIb, while others ($Al_2O_3$, $TiO_2$, $Na_2O$, and $K_2O$) do not vary between Association Ib and IIIb. REEs are also distinctly different for Associations Ib and IIIb; in Association Ib, REY and HREE/LREE are uniform through the sediment section, while they increase downward in Association IIIb like the major elements; below a depth of 8 cm, REY is over 500 ppm. The metal enrichment factor (EF) evaluates the anthropogenic influences of some metals (Cu, Ni, Pb, Zn, and Cd) in marine sediments. In both Associations, the EF for Cu is over 1.5, the EF for Ni and Pb ranges from 0.5 to 1.5, and the EF for Zn and Cd are less than 0.5, indicating Cu is enriched but Zn and Cd are relatively depleted in the BIS. The vertical variations of geochemical properties between Association Ib and IIIb are shown to be clearly different, which seems to be related to the global climate changes such as the shift of Intertropical convergence zone (ITCZ).

Verifying the similarity of environmental characteristics between an artificial impact site and a preserved or reference site is necessary to quantitatively and qualitatively evaluate the environmental impact of mining activity. Although an impact site (BIS station) and a preserved site (called KOMO station) that have been selected in the Korea manganese nodule contract area may share similar environmental characteristics, similarities in terms of the water column environment between both sites has not been investigated. In this study, we compared the chemical properties of the water columns and sinking particle fluxes between BIS and KOMO stations through two observations (August 2011 and September 2012). Additionally, we observed particle fluxes at the KOMO station for five years (July 2003~July 2008) to understand long-term natural variability. Vertical distributions of water column properties such as dissolved oxygen, inorganic nutrients (N, P, Si), total organic carbon below surface layer (within the depth range of 200 m) were not considerably different between the two sites. Especially, values of water column parameters in the abyssopelagic zone from 4000 m to bottom layer (~5000 m) were very similar between the BIS and KOMO sites. Sinking particle fluxes from the two sites also showed similar seasonality. However, natural variation of particle flux at the KOMO site varied from 3.5 to $129.9mg\;m^{-2}day^{-1}$, with a distinct temporal variation originating from ENSO events (almost forty times higher than a minimum value). These results could provide valuable information to more exactly evaluate the environmental impact of mining activity on water columns.

A time-series sediment trap was operated at a water depth of 4950 m from July 2003 to May 2004 at KOMO station ($10^{\circ}30^{\prime}N$, $131^{\circ}20^{\prime}W$) in the northeastern equatorial Pacific, with the aim of understanding the temporal variation of planktonic foraminifera assemblages in response to the seasonal shift of Inter-Tropical Convergence Zone (ITCZ). A total of 22130 planktonic foraminifera specimens belonging to 30 species and 11 genera were identified, which shows a distinct seasonal variation with high values (125~288 specimens $m^{-2}day^{-1}$) in the winter to spring (December-May) and low values (16~23 specimens $m^{-2}day^{-1}$) in the fall (September-November). In addition, seasonal ecological differences of foraminifera assemblages are distinctly recognizable: omnivorous foraminifera occurred predominantly during the summer season, whereas herbivorous ones were dominant during the winter season. Such seasonal variations correspond to the seasonal shift of the ITCZ. Enhanced occurrence of herbivorous species during the winter-spring season seems a result of surface water mixing generated by the southward shift of the ITCZ. The increase in omnivorous species during the summer season may be due to the northward movement of the ITCZ caused by weakened wind speed, resulting in the intensification of water column stratification and nutrient-poor environment. A significant reduction of planktonic foraminifera specimens during the fall is attributed to heavy precipitation and reduction in light intensity.

In August, 2013, we collected epifaunal megabenthos using a deep sea camera (DSC) around a benthic impact study (BIS) site. This was located in the KR5 block of the Korea Deep Ocean Study (KODOS) area in the Northeastern Pacific. The DSC was positioned at $6.8{\pm}2.9m$ (SD) from the sea bottom and was operated from a position at $131^{\circ}56.85^{\prime}-131^{\circ}55.02^{\prime}W$ for 2.3 h at a speed of 1-2 knot. The geographical features of the study area consisted of two structures; a trough in the middle and hills at the east and west sides. Sediment conditions were consistent within six blocks and were affected by slope and polymetallic nodule deposits. We analyzed 226 megafaunal species. Sipunculida comprised the highest percentage of individuals (39%), and the dominant epifaunal megabenthos were Hormathiidae sp., Primnoidae sp., Hexactinellida sp., Hyphalaster inermis, Freyella benthophila, Paelopatides confundens, Psychropotes longicauda, and Peniagone leander. More than 80% of the total density of megafauna occurred on sea plain (D- and E-blocks). We found two distinct groups in the community, one located on sea plains and the other along both sides of the sea slop. Our results suggest that geographical features such as slope and polymetalic nodule deposits are important in controlling the distribution of the epifaunal megabenthos around the KODOS area.

This paper presents data from performance tests carried out to assess a manganese nodule crusher. Manganese nodules should be crushed into smaller pieces in order to assure the slurry flow of the lifting system. Both artificial nodules and real manganese nodules are used to evaluate nodule breaking ability of the crusher. The crushing performance of the crusher depends on the flow rate and pressure of the power transmission device. The size of the crushed manganese nodules also depends on the shape of the crushing drum. In this paper, several comparative tests are carried out to evaluate and improve the crushing performance and find the optimal design point of the crusher.

This paper proposes a formation control method by which multi-mining robots maintain a specified formation and follow a path. To secure the path tracking performance, a pure-pursuit algorithm is considered for each individual robot, and to minimize the deviation from the reference path, speed reduction in the steering motion is added. For the formation, in which two robots are parallel in a lateral direction, the robots track the specified path at a constant distance. In this way, the Leader-Follower method is adopted and the following robot knows the position and heading angle of the leader robot. Through the experimental test using two ground vehicle models, the performance is verified.

Seawater flow characteristics around a manganese nodule mining device in deep sea were analyzed through numerical investigation. The mining device influences the seawater flow field with complicated velocity distributions, and they are largely dependent on the seawater flow speed, device moving speed, and injection velocity from the collecting part. The flow velocity and turbulent kinetic energy distributions are compared at several positions from the device rear, side, and top, and it is possible to predict the distance from which the mining device affects the seawater flow field through the variation of turbulent kinetic energy. With the operation of the collecting device the turbulent kinetic energy remarkably increases, and it gradually decreases along the seawater flow direction. Turbulent kinetic energy behind the mining system increases with the seawater flow velocity. The transient behavior of nodule particles, which are not collected, is also predicted. This study will be helpful in creating an optimal design for a manganese nodule collecting device that can operate efficiently and which is eco-friendly.

Deep-seabed test miner operated by a self-propelled mining system moving on soft soil is an essential device to secure floating and towing performances. The performances of the tracked vehicle are seriously influenced by noise factors such as the shear strength of the seafloor, bottom current, seafloor slope, speed of tracked vehicle, reaction forces of flexible hose, steering ratio, etc. Due to uncertainties related to noise factors, the design of a deep-sea manganese nodules test miner that satisfies target reliabilities is difficult. Therefore, reliability-based design optimization (RBDO) is required to guarantee system reliability under circumstances where uncertainties related to noise factors prevail. Among noise factors, the bottom current, a bimodal distribution, is censored due to the observation limit of measurement devices. Therefore, estimated distribution of the bottom current is inaccurate without considering these characteristics and the result of RBDO cannot be guaranteed. In this paper, we define censored data as unknown values over the limit of observation. If this data is estimated by using Akaike information criterion (AIC) that cannot consider the characteristics of censored data, the distribution of estimated data cannot guarantee accurate reliability. Therefore, censored AIC that can consider the characteristics of data is used to estimate accurate distribution of the bottom current. Finally, RBDO, under circumstances where uncertainties related to noise factors combined censored data are present, is performed on the mobility of a deep-sea manganese nodules test miner.

This paper focuses on the dynamic responses of a tracked vehicle crawling on extremely cohesive soft soil, each side of which is composed of two parallel tracks. The tracked vehicle consisted of 2 bodies. One body is the tracked vehicle body, which is assumed to be a rigid body with 6 DOFs. The other body is the buoy body. The two bodies are connected by a revolute joint. In order to evaluate the travelling performance of a 7 DOFs vehicle, a dynamic analysis program for the tracked vehicle was developed using Newmark's method and the incremental-iterative method. The effects of road wheels on the track and soil are not taken into account. A terra-mechanics model of extremely cohesive soft soil is implemented in form of relationships: normal pressure to sinkage, shear resistance to shear displacement, and dynamic sinkage to shear displacement. Pressure-sinkage relationship and shear displacement-stress relationship should represent the non-linear characteristics of extremely soft soil. Especially, since the shear resistance of soft soil is very sensitive to shear displacement, spatial distribution of shear displacement occurring at the contact area of the tracks should be calculated precisely. The proposed program is developed in FORTRAN.

The development of deep seabed manganese nodules has been carried out with the aim of commercial development in 2023. It is important to forecast the price of the four metals (copper, nickel, cobalt, and manganese) extracted from manganese nodules because price change is a criterion for investment decision. The main purpose of the study is to forecast the price of four metals using the ARIMA model and VAR model, and calculate the MAPE to compare a goodness-of-fit between the two models. The estimated results of the two models reveal statistical significance and are in keeping with economic theory. The results of MAPE for goodness-of-fit show that the VAR model is between 0.1 and 0.2, and the ARIMA model is between 0.4 and 0.6. That is, the VAR model is better than the ARIMA model in forecasting changes in the price of metals.

The Korea Institute of Ocean Science and Technology has acquired detailed biological, chemicophysical, and geological data in the northeastern Pacific through a manganese nodule program since 1983. Plenty of manganese nodules were collected to estimate the amount of resources by free-fall grab and box corer. The collected manganese nodules have been archived systematically in the rock and mineral storage section of the Library of Marine Samples (LIMS) since 2012. The LIMS provides essencial information on the stored samples including sample name, nodule type, sampling location, depth, and equipment. Although a high quality database of the information system is under construction, the samples have tagged information for manganese nodules like chemical composition, morphology, weight, size, abundance, and photograph. In this study, we attempted to provide information on the well-organized and easily accessible archived manganese nodule samples for future studies and to introduce the usefulness of the LIMS.