• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.549-552
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• 2009

Methane hydrate is crystalline ice-like compounds which formed methane gas enters within water molecules composed cavity at specially temperature and pressure condition, and water molecule and each other from physically-bond. $1m^3$ hydrate of pure methane can be decomposed to the maximum of $172m^3$ at standard condition. If these characteristics of hydrate are reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore the hydrate is considered to be a great way to transport and store natural gas in large quantity. Especially the transportation cost is known to be 18~24% less than the liquefied transportation. However, when methane hydrate is formed artificially, the amount of consumed gas is relatively low due to a slow reaction rate between water and methane gas. In this study, for the better hydrate reaction rate, there is make nano fluid using ultrasonic dispersion of carbon nano tube. and then, Experiment with hydrate formation by nano fluid and methane gas reaction. The results show that when the carbon nano tubes of 0.004 wt% was added to pure water, the amount of consumed gas was about 300% higher than that in pure water and the hydrate formation time decreased.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.55.1-55.1
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• 2011

Dye-sensitized solar cell(DSSC) have been considered one of the promising alternatives to conventional solar cells, because of their low cost, easy fabrication and relatively high energy conversion efficiency. However, although the cell offers reasonable efficiency at least 11%, the use of a liquid electrolyte placed technological challenges for achieving the desired durability and operational stability of the cell. In order to prevent or reduce electrolyte leakage considerable efforts have been made, such as p-type semiconductor or organic hole-transport material that better mechanical properties and simple fabrication processes. In this work, we synthesized solid-state electrolyte containing LiI and KI metal salt with starting materials of poly ethylene oxide to substitute liquid electrolyte enhance the ionic conductivity and solar conversion efficiency. Li+ leads to faster diffusion and higher efficiency and K+ leading to higher ionic conductivity. The efficiency of poly ethylene oxide/LiI system electrolyte is 1.47% and poly ethylene oxide/potassium electrolyte is 1.21%. An efficiency of 3.24% is achieved using solid-state electrolyte containing LiI and KI concentrations. The increased solar conversion efficiency is attributed to decreased crystallinity in the polymer that leads to enhanced charge transfer.

• Transactions on Electrical and Electronic Materials
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• v.6 no.3
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• pp.124-127
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• 2005

It has been a long time since organic solar cells were expected as a low-cost energy-conversion device. Although practical use of them has not been achieved, technological progress continues. Morphology of the materials, organic/inorganic interface, metal cathodes, molecular packing and structural properties of the donor and acceptor layers are essential for photovoltaic response. We have fabricated solar cell devices based on zinc-phthalocyanine(ZnPc) as donor(D) and fullerene$(C_60)$ as electron acceptor(A) with doped charge transport layers, and BCP and $Alq_3$ as an exciton blocking layer(EBL). We have measured the photovoltaic characteristics of the solar cell devices using the Xe lamp as a light source. We were use of $Alq_3$ layer leads to external power conversion efficiency was $2.65\%$ at illumination intensity $100\;mW/cm^2$. Also we confirmed the optimum thickness ratio of the DA hetero-junction is about 1:2.

• Journal of Korea Port Economic Association
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• v.17 no.1
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• pp.129-157
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• 2001

In Korea, the quantity of waste is excessive as a result of increases in population and consumption following industrialization. This has resulted in urban environmental problems, a shortage of landfills and pollution around landfills. Thus, there is a need to conduct research in order to find an effective long-term alternative. In Japan, there are more landfills at sea than there are on land. Based on projections for Korea, on-land landfills in the metropolitan area will be filled to capacity by 2020 and then be closed. This research recommends the construction of landfill sites at sea as an alternative waste disposal method. Its findings show that the most the suitable sites for landfills within the Seoul metropolitan area are the regions around Jangbongdo Island and Mueido Island. It also suggests that the best way to transport waste is through the Kyungin Canal from the middle collection center to the lower Han River. The estimated cost of constructing an at-sea landfill to be used for 50 years is approximately two trillion won, with a total construction time of 10 years. In the future, further research related to this study will be conducted in order to ensure that environmentally-friendly landfills are built.

• Journal of the Korean Solar Energy Society
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• v.29 no.4
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• pp.34-40
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• 2009

$1m^3$ hydrate of pure methane can be decomposed to the maximum of $216m^3$ methane at standard condition. If these characteristics of hydrate are reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore, the hydrate is considered to be a great way to transport and store natural gas in large quantity. Especially the transportation cost is known to be 18-24% less than the liquefied transportation. In the present investigation, experiments and theoretical calculation carried out for the formation of methane hydrate in NaCl 3.5wt% solution. The results show that the equilibrium pressure in seawater is more higher than that in pure water, and methane hydrate could be formed rapidly during pressurization if the subcooling is maintained at 9K or above in seawater and 8K or above in pure water, respectively. Also, amount of consumed gas volume in pure water is more higher that in seawater at the same experimental conditions. Therefore, it is found that NaCl acts as a inhibitor.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.41-51
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• 1999

Trade between Korea and China was 372million dollars accounting for 1.56% of total in 1988 and has been increased to 23,689 million dollars occupying 7% in 1997, which implies 32.2% increase on average per year. This trend will continue dramatically and consistently as China's open policy toward the world accelerates and korean companies advance into chinese market. The main trade routes are with marine transportation between korean west sea area and chinese San-Dong peninsula around east sea. However, due to the increasing traffic congestion on main roads connecting harbors and main consumer cities and capacity problem in west sea harbor areas, the logistics cost have been increased resulting in losing competitiveness of freight trade. Therefore, these road-oriented inland transportation means need to be changed to rail transport system to reduce congestion and to conserve natural environment. To achieve this scheme, efficient intermodal transportation system connecting road and rail should be constructed. These combined system will ensure timely delivery of goods and consequently the customers would make proper transportation schedule for the import/export goods in advance. Especially, combined transportation of Railroad and train ferry would cope with the logistics problem and this system would be efficient means for trade with not only China but further with many adjacent countries in central asia such as Kazakhstan and Uzbekistan

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1553-1560
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• 2008

The modern logistics has tried not only to convert the conventional packing system into unit load system using pallet but also to enhance the fitness between packing facilities and transport modes. This is based on the goal to reduce total logistics cost using logistics efficiency. Because the packing unit can affect on both loading rate and loading facilities, the basic form of packing unit is very important to the unit load system. In Korea, the standardization of logistics has been centered on pallet, and the basic condition will be continued except of the variety of standardized pallet form. Because of this, to enhance the standardization of pallet, it is necessary to develop new standard size and form of pallet. The object of this study is to develop a new method of collecting the effectiveness of standardized packing module. The new method is based on measure of effectiveness (MOE) which can be developed by expert survey. This study has originality from the fact that the collecting method for effectiveness of pallet standardization has not been developed up to now.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.2
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• pp.82-88
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• 2017

There are main issues of defect type that condensation, concrete crack and noise in apartment buildings. Especially, according to the Apartment Defect Dispute Mediation Committee in Korea (ADDMC) at Ministry of Land Infrastructure and Transport in Korea (MLIT), condensation defects are great importance (14 percent) on whole number of reported cases of faults from 2015 in Korea. Most condensation defects have many different causes that take a toll on the resident's life and space. So it is very important to early detection and repair. For preventing the condensation in apartment buildings, there are building codes in Korea such as 'Standard of Method and Judgment for Apartment defect of investigation, Repair cost Estimate'. This research aims to study on the improvement of preventing the condensation aforementioned korea standard. Types and characteristics (opaque wall, windows, doors) of cause of occurrence and existing state condensation defect is analyzed from evaluation of real application 100 case in 2015 ADDMC data.

• Composites Research
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• v.28 no.6
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• pp.402-407
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• 2015

It is well known that the polymer matrix composite materials have good specific strength, making them appropriate for use in transport vehicle. Since the property of composite materials can be obtained only after manufacturing parts, the property depends on greatly on the fabrication process, which is different from metallic system. Therefore, in order to use composite materials for aircraft, the certifying agency requires a robust database with extensive tests and proof of the process unlike metals. Recently developed material qualification methodology by NCAMP (National Center for Advanced Materials Performance) has been accepted by FAA and EASA and can be applied to type certificate reducing time and cost of developing a composite materials database for aircraft application. This paper summarizes a study to establish the composite materials database to apply the NCAMP methodology to composite materials characterization for composite aircraft and to provide the effective materials database through Aerospace Composite Materials Data Center to be approved by Korea Civil Aviation Certification Agency.

• ETRI Journal
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• v.42 no.2
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• pp.186-195
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• 2020

Software-defined networking (SDN) acts as a centralized management unit, especially in a network with devices that operate under the transport layer of the OSI model. However, when a network with layer 7 middleboxes (MBs) is considered, current SDNs exhibit limitations. As such, to achieve a real-centralized management unit, a new architecture is required that decouples the data and control planes of all network devices. In this report, we propose such a complementary architecture to the current SDN in which SDN-enabled MBs are included along with contemporary SDN-enabled switches. The management unit of this architecture improves network performance and reduces routing cost by considering the status of the MBs during flow forwarding. This unit consists of the following two parts: an SDN controller (SDNC) and a middlebox controller (MBC). The latter selects the best MBs for each flow and the former determines the best path according to its routing algorithm and provides information via the MBC. The results show that the proposed architecture improved performance because the utilization of all network devices including MBs is manageable.