• Journal of Advanced Marine Engineering and Technology
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• v.37 no.6
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• pp.611-616
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• 2013

Many researches have been carried out consistently for the green ship owing to its economic increasement, efficiency and convenience. One of them is an electronic controlled marine diesel engine. However, we are suffered from dissemination of above engine, due to its anxiety about safety and reliability. In order to solve these problems in this study, emission characteristics test of main propulsive two-stroke diesel engine, equipped both electronic control and cam drive fuel injection systems, has been performed and evaluated under the various load conditions. From the test results, we have confirmed that exhaust gas emission characteristics of the electronic control system is similar to the cam drive system in eco-mode operation, but NOx in emission mode has been decreased 100ppm or more in full load condition. HC emission from the electronic control system is decreased 10~20ppm at 50% load, and 35~40ppm at 25% load in comparison to cam drive system. In fuel consumption, it is considered that 7g/kWh is decreased than the value of cam drive system at 700bar of injection pressure, which is 200bar higher than cam drive system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.4
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• pp.397-406
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• 2016

Diverse stakeholders engaged in design, construction, and operation and maintenance of offshore plants typically operate heterogeneous plant 3D CAD systems. Engineering, procurement, and construction (EPC) companies are required to submit plant design result to the owner in the form of a plant 3D CAD model, as specified in the contract. However, because of the limitations of data interface of plant 3D CAD systems, EPC companies frequently perform manual remodeling to fulfill the terms and conditions of the contract. Therefore, comparison should be performed between the source plant 3D CAD model and the remodeled plant 3D CAD model to prove the validity of the remodeled plant 3D CAD model. To automate the comparison process, we have developed a system for quantitatively assessing the similarity of the plant 3D CAD models. This paper presents the architecture and detailed functions of the system. In addition, experimental results using this system are explained.

• Economic and Environmental Geology
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• v.45 no.2
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• pp.137-144
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• 2012

Soil pan typically presents the problems in soil water movement or in aeration which is not appropriate for a plant root growth, In this study physico-chemical characteristics of soils and micromorphological characteristic of clay accumulated zone were investigated to identify redox characteristic and evolution of a fragipan of Gangreung series commonly developed in coastal terraces. Gangreung series is classified as Aquic Fragiudalfs according to the USDA soil taxonomy. It is known that sedimentary ocean floor results in soil pan having parallel liner soil structure due to landscape evolution around 200 to 250 million years ago. it is considered that illite, kaolinite, and vermiculite are major clay minerals contained in a fragipan of Gangreung series. Mixed gray and reddish brown colored band around soil pores was found and would be the redoxmorphic features of fragipan. It is possibly due to accumulated illuvial clay and ferriargillans in soil pores and aggregates in reducing conditions eluding ferrous material. Therefore, mixed colored band around pores in soils of Gangreung series would be developed from the eluted ferrous materials which were accumulated in fragipan during the emerged land formation.

• ALGAE
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• v.20 no.2
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• pp.167-176
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• 2005

In order to produce Laminaria japonica in Jeju as feed for abalone, a transplant experiment was performed with the Baekryungdo and the Wando cultivar stocks at the Udo aquafarm from January to July 2003. Eight water conditions at the aquafarm and eleven traits of the two cultivar stocks were measured once a month. The water temperature ranged from 12.9$^{\circ}C$ to 23.5$^{\circ}C$. The salinity was 31.3-36.8‰ the DO was 5.40-9.86 mg ${\cdot}$ $l^{-1}$ the pH was 7.82-9.61. Concentrations of $NO_2-N,\;NO_3-N,\;NH_4-N\;and\;PO_4-P$ were 0.02-0.15 $\mu$M, 2.27-3.49 $\mu$M, 0.16-0.56 $\mu$M and 0.07-0.99 $\mu$M, respectively. The whole frond length of the Baekryungdo and the Wando specimens were 173.84 and 153.67 cm. The blade width, stipe length, blade length, fascia length, blade thickness, total weight and substantiality of the Baekryungdo and the Wando specimens were 14.61 and 13.05 cm, 3.94 and 3.02 cm, 169.88 and 150.65 cm, 155.81 and 137.10 cm, 1.01 and 0.96 cm, 258.04 and 200.96 cm, and 101.56 and 94.62, respectively at the conclusion of the experiment in July. The measurements of the Baekryungdo specimens were slightly higher than those of Wando specimens. The fascia width, stipe thickness and fascia thickness of the Wando specimens were slightly higher than those of the Baekryungdo specimens. The relative growth rates of these traits of two cultivar stocks during the growth test were very similar. Generally, the performance of the Baekryungdo cultivar stock seems to be better than that of the Wando samples. Further study of the physiological ecology for cultivation and breeding is needed in the future.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.663-666
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• 2005

Gas hydrates are ice-like compounds that form at the low temperature and high pressure conditions common in shallow marine sediments at water depths greater than 300-500 m when concentrations of methane and other hydrocarbon gases exceed saturation. Estimates of the total mass of methane carbon that resides in this reservoir vary widely. While there is general agreement that gas hydrate is a significant component of the global near-surface carbon budget, there is considerable controversy about whether it has the potential to be a major source of fossil fuel in the future and whether periods of global climate change in the past can be attributed to destabilization of this reservoir. Also essentially unknown is the interaction between gas hydrate and the subsurface biosphere. ODP Leg 204 was designed to address these questions by determining the distribution, amount and rate of formation of gas hydrate within an accretionary ridge and adjacent basin and the sources of gas for forming hydrate. Additional objectives included identification of geologic proxies for past gas hydrate occurrence and calibration of remote sensing techniques to quantify the in situ amount of gas hydrate that can be used to improve estimates where no boreholes exist. Leg 204 also provided an opportunity to test several new techniques for sampling, preserving and measuring gas hydrates. During ODP Leg 204, nine sites were drilled and cored on southern Hydrate Ridge, a topographic high in the accretionary complex of the Cascadia subduction zone, located approximately 80km west of Newport, Oregon. Previous studies of southern Hydrate Ridge had documented the presence of seafloor gas vents, outcrops of massive gas hydrate, and a pinnacle' of authigenic carbonate near the summit. Deep-towed sidescan data show an approximately $300\times500m$ area of relatively high acoustic backscatter that indicates the extent of seafloor venting. Elsewhere on southern Hydrate Ridge, the seafloor is covered with low reflectivity sediment, but the presence of a regional bottom-simulating seismic reflection (BSR) suggests that gas hydrate is widespread. The sites that were drilled and cored during ODP Leg 204 can be grouped into three end-member environments basedon the seismic data. Sites 1244 through 1247 characterize the flanks of southern Hydrate Ridge. Sites 1248-1250 characterize the summit in the region of active seafloor venting. Sites 1251 and 1252 characterize the slope basin east of Hydrate Ridge, which is a region of rapid sedimentation, in contrast to the erosional environment of Hydrate Ridge. Site 1252 was located on the flank of a secondary anticline and is the only site where no BSR is observed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.2
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• pp.92-101
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• 2015

We investigated cause of non-outbreak of Cochlodinium polykrikoides blooms in the western coast of Jaran Bay during summer, 2013, based on the species competition among C. polykrikoides and Skeletonema sp. using a mathematical model. As a result of the model simulation where the nutrient conditions in Jaran Bay was applied during summer, the cell density of Skeletonema sp. was higher than that of C. polykrikoides. In the sensitivity analyses by doubling and halving the parameters, any parameter had little effect on the cell density of C. polykrikoides. The cell density of Skeletonema sp. was significantly affected by changes in the parameter values. These results indicated that the growth of C. polykrikoides could be unaffected by rapidly changing environments. However, the growth of Skeletonema sp. may have been promoted by the changing nutrient supply of coast environments. Therefore, C. polykrikoides might have been suppressed by diatom blooms, such as Skeletonema sp., in changing nutrient supply condition of Jaran Bay.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.107-117
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• 1975

Alaska pollack caught in the Northern Pacific Ocean and frozen aboard vessel are skipped to the plant and processed into frozen fillets. In the present paper quality changes during thwaing, refreezing and storage at $-20^{\circ}C$ are discussed. Natural, running-water, vacuum and steam thawing were employed as thawing methods. And contact plate, air blast, immersion in dry ice-alcohol solution freezing and storage at $-5^{\circ}C$ were applied to refreeze the thawed fillets. As quality factors content of drip released, salt-extractable protein, VBN, DNA in the drip and pH were determined. In addition, bacteriological tests were also carried out along with the whole process. In thawing of round material, the vacuum thawing was more effective than any other method, resulting in drip, salt-extractable protein $(N\%)$, VBN and DNA as $4.4\%,\;1.82\%,\;16.21mg\%$ and $13.70\;{\mu}g/ml$, respectively. Storage at $-5^{\circ}C$ as refreezing method yielded lower in drip and DNA content but similar to or slightly higher in both salt-extractable protein and VBN, which might postulate that the quality of the frozen fillet depends not largely on the secondary freezing but on the conditions of thawing and primary freezing. It seemed that most of the bacterial flora in thawed fillet came from skin and viscera of fish, worker's hands, utensils and other processing facilities, since sanitary indicative bacteria were not detected in the frozen flesh of round Alaska pollack. Bacterial quality of fillet varied with thawing methods, vacuum thawing appeared more sanitative compared with other methods as natural, running-water, and steam thawing. Bacterial colonies isolated from the thawed fillet were composed of $73.8\%$ Gram negative rod shape, $4.9\%$ Gram positive rod shape, $18.0\%$ cocci, and $3.3\%$ yeast. Decreasing rate of coliform group of the fillet during the storage at $-20^{\circ}C$ for 30 days was more than $70\%$ and that of plate count was less than of coliform group.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.771-780
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• 2014

Tetragonia tetragonides is a medicinal plant native to ocean sand soil of southern provinces and has significant effects on the prevention and curing of gastroenteric disorders. Despite of its popularity, supply of the plant has never met the level of demand because of the absence of an adequate culturing method. The present study, thereby, was conducted for classifying the plants with geographically different characteristics, studying growth habits, developing a new culturing method and establishing a large scale propagation system of selected superior individual plants. The study was also aimed for revealing optimum conditions for seed treatment, fertilization, and efficient culturing system and thereby, for utilizing the plant as a new income source for rural communities. The seed was elongated with size of 2.6 mm (width) ${\times}$ 1.8 mm (length). No difference in seed size was observed depending on different inhabitate. Each flower produced about 4.5~4.8 seeds. Germination rate was high for seeds matured for 40 days after fertilization, but deceased to 50% for seeds matured only for 20 or 30 days. Seed dormancy lasted 6 months and seed storage at humid $5^{\circ}C$ facilitated germination. Mechanical obstruct of seed germination was due to seed coat and removal of seed coat enhanced the germination rate. Optimum temp. for seed storage was $5^{\circ}C$, and high germination rate was maintained for 350 days. However, for stratification condition or at room temperature, germination was significantly reduced as storage time increased Optimum treatment of plant growth regulators was soaking in $GA_3$ 250 mg/L for 1 hr. The priming treatment with 50 mM $Ca(NO_3)_2$ at $20^{\circ}C$ for two days improved the seed germination with 10% compared to non-treated control. The treatment of 20% NaOCl for 3 hr. improved the seed germination rate up to 10% and 1 day ahead.

• Korean Journal of Remote Sensing
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• v.36 no.2_1
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• pp.103-119
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• 2020

Recently, the rapid redeposition and erosion of rivers artificially created by climate change and the Four Rivers Restoration Project is questionable. According to the revised law in Korea, the river management agency will periodically carry out bed changes surveys. However, there are technical limitations in contrast to the trend of increasing spatial coverage, density and narrowing of intervals. National organizations are interest in developing innovative bed changessurvey techniquesfor efficiency. Core of bathymetry survey is to measure the depth of rivers under a variety of river conditions, but that is relatively more risky, time-consuming and expensive compared to conventional ground surveys. To overcome the limitations of traditional technology, echo sounder, which has been mainly used for ocean depth surveying, has been applied to rivers. However, due to various technical limitations, it is still difficult to periodically investigate a wide range of areas. Therefore, technique using the remote sensing has been spotlighted as an alternative, especially showing the possibility of depth measurement using spectral characteristics. In this study, we develop and examine a technique that can measure depth of water using reflectance from spectral characteristics. As a result of applying the technique proposed in thisstudy, it was confirmed that the measured depth and the correlation and error corresponding to 0.986 and 0.053 m were measured in the depth range within 0.95 m. In the future, this study could be applied to the measurement of spatial depth if it is applied to the hyperspectral sensor mounted on the drone.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.248-254
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• 2015

There has been no previous study on technology development of large capacity drainage pump for rescue sinking ship in the country. The agricultural drainage pump was widely used for rescue sinking ship but this pump has several problems such as efficiency, low displacement and malfunction in winter. Therefore, this paper proposes to solve the problems for swiftly rescue sinking ship and develops the drainage pump system that has $20m^3/min$ mass flow rate specification at suction head 8 m. The centrifugal pump type the most commonly used in the field of naval architecture and ocean engineering was selected and designed based on the requirement specification. The blade design of impeller was derived from the Stepanoff coefficient and requirement specification and used computational fluid dynamics to review the target mass flow rate according to the impeller RPM at design operating conditions. We also performed structure analysis of the impeller to find structurally vulnerable points for the pump in service and completed the theoretical design of drainage pump system.