• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.2
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• pp.85-95
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• 2009

The fishing lamp is a fishing gear that gathers fish at night. But the cost of oil, which is used to light fishing lamp, has been risen significantly up to 30-40% of total fishing costs. Therefore it is very urgent to develop an energy economical fishing lamp in order to solve the business difficulties of fisheries. Under this background, this research aims at developing a fishing lamp for squid jigging and hairtail angling fishery using the LED, which has excellent energy efficiency and durability. The LED fishing lamp developed can be controlled to fix a fit direction of fish shoal deep because a fishing lamp can be adjustable up and down directions. One unit of fishing lamp has about an 80Watt capacity and the frame of fishing lamp is made of aluminium to emit generated heat of LED to outside. The LED lamp developed was highly durable, only 5.7% of emitting efficiency decreased for 18 months. The illuminance of a unit LED lamp was 2,070lux at 1m and 21lux at 10 m distance, and the intensity of LED lamp system emitted 2,580lux and 400lux at the respective distances. After development of this fishing lamp, 100 units are installed on operating fishing vessels. Experimental results show that energy consumption of squid jigging and hairtail angling was reduced by 40% and 87%, respectively. In conclusion, our methods showed elevated fishing power, compared with traditional fishing method: 37.7% for squid jigging and 24.5% for hairtail angling.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.191-200
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• 2020

Tracked military vehicles are operated under harsher conditions and climates than ordinary vehicles, and the components require high degrees of reliability and durability. A diesel engine is the main power generator, and when the vehicle breaks down, there is a high possibility of causing a large-scale accident. Therefore, analyzing the cause of engine failure can be important for preventing similar cases that may occur. In this study, we clarified the mechanism of engine failure according to an overhaul test, hardness measurement, and an analysis of the fracture surface. The overhaul test confirmed that a bolt was separated from the connecting rod (number 4). In addition, the hardness measurement results of the connecting rod bolt conformed to the standard, and it was found that the bolt fracture was ductile fracture through an analysis of the fracture surface. Based on the results, it was concluded that damage to a diesel engine of a tracked military vehicle was caused by separating and damage caused by loosening of the connecting rod bolts, resulting in cascading damage. The results of the study could be used as reference examples and could be useful for another study on engine failure analysis.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.175-184
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• 2012

This study was conducted to develop new mattress systems with vegetation base materials for protecting stream bank and rapid rehabilitation. Vegetation base materials are primarily compounded with fine soil, organic composts and peat moss as plant fibers, a water retainer and a soil improver. Peat moss can usually provide necessary natural fibers and organic materials in soil. Especially, peat moss can absorb up to 25 times its own weight in water and is therefore valued as a water retainer to prevent drying effect of vegetation base materials which can harm the growth of vegetation in mattresses. Normally mattress systems resist the lateral earth pressures or stream power by their own weight. Therefore, filled materials must have suitable weight, compressive strength and durability to resist the loading, as well as the effects of water and weathering. In this project, 100 to 200-mm clean, hard stones were basically specified, and about 50-mm rubbles were also used. Test application of new mattress system carried out in the stream bank of a small stream in the Gwangreung experimental forest, belonging to Korea Forest Research Institute (KFRI) in December 16th, 2006. As a result of the monitoring of vegetation coverage of test application plots (each plot size is 4 by 2 m), the coverage of all plots reached 100% in the end of May, 2007 (approximately 50 days passed after the first gemination of vegetation). The coverage of the plots using big hard stones and organic composts and the plots containing peat moss increased more rapidly. The results show that peat moss is effective to retain soil moisture and establish more sound environment for vegetation gemination.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.829-839
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• 2003

Recently, the corrosion of reinforced concrete structures has received great attention related with the deterioration of sea-side structures, such as new airport, bridges, and nuclear power plants. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the influences of carbonation to chloride attack in concrete structures. The test results indicate that the chloride penetration is more pronounced than the case of single chloride attack when the carbonation process is combined with the chloride attack. It is supposed that the chloride ion concentration of carbonation region is higher than the sound region because of the separation of fixed salts. Though the use of fly ash pronounces the chloride ion concentration in surface, amounts of chloride ion penetration into deep region decreases with the use of fly ash. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of both chlorides and carbonation but the future studies for combined environment will assure the precise assessment.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.840-847
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• 2003

Recently, the coal-ash production has been increased by increase of consumption of electric power. So it is important to secure a reclaimed land and treatment utility for coal-ash. This is an experimental study to compare and analyze the engineering properties of concrete according to W/C and replacement ratio of bottom ash. For this purpose, the mix proportions of concrete according to W/C(40, 50, 60%) and replacement ratio of bottom ash(0, 10, 20, 35, 50%) were established, and then tested for slump, chloride content, setting time, bleeding content, compressive strength. Also the durability test of concrete with W/E 60% was performed. According to test results, it was found that the bleeding content of concrete decreased as the replacement ratio of bottom ash increased. And the chloride content of concrete using the bottom ash increased as the replacement ratio of bottom ash increased, but it is satisfied with the chloride content of fresh concrete $0.30kg/m^3$ below("concrete standard specification" regulation value). The compressive strength of concrete using the bottom ash was similar to that of BA0 concrete after 28 days of curing and the carbonation depth of concrete was increased according to increase of the replacement ratio of bottom ash.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.687-693
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• 2019

As the hydrogen fuel cell market is expanded starting from hydrogen electric vehicle and power generation field, the demand for fuel cells and hydrogen increases recently. Therefore, research works on fuel cell durability and fuel efficiency are required in order to activate the fuel cell market and commercialization. A dead-ended anode system was used in this study to optimize the fuel cell performance and fuel efficiency. The effect of purge condition according to the applied current and hydrogen supply pressure on the fuel cell performance were evaluated. In addition, the influence of water back diffusion on the different electrolyte membrane thickness was analyzed. The accumulated water was purged with a solenoid valve in the case of 3% voltage decrease in the dead-ended anode system. The experiment was performed with the hydrogen supply pressure of 0.1~0.5 bar and purge duration of 0.1~1 second. A maximum fuel efficiency of 98.9% was achieved under the purge duration of 0.1 s and hydrogen supply pressure of 0.1 bar with a NR 211 (25.4 um) membrane. However, the fuel cell performance decreased in a long-term operation due to some frequent flooding. The fuel efficiency and purge interval increased due to decreased back diffusion rates of the water and nitrogen with a NR 212 (50.8 um) membrane.

• Journal of the Korean GEO-environmental Society
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• v.15 no.4
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• pp.61-67
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• 2014

With a view to resolving environmental problems of hazardous cement, this study seeks to identify the unconfined compressive strength and bending strength of the vegetation block designed herein by utilizing high-strength natural soil stabilizer instead of cement. Soil stabilizer is mainly made of mixture of short fiber extracted from natural fiber and lime, etc. Soil stabilizer reinforces the shearing strength of soil to improve block supportive power and durability while preventing flood and frost damages. For the unconfined compressive strength test, test pieces were prepared by mixing soil stabilizer and weathered soil in different ratios of 6 %, 12 % and 18 %. Experiments were carried out according to curing periods of 5th, 7th, 14th and 28th of the day. For bending strength test, blocks were made in the same mixture ratios as for the unconfined compressive test and tested for each stage. Also, to evaluate for the field applicability, proposed optimum water content considering the characteristics of the soil stabilizer. Permeability test result for the vegetation block, satisfied by the KS F 4419 quality standards.

• International Journal of Fluid Machinery and Systems
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• v.10 no.1
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• pp.40-46
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• 2017

Small valves including ball valves, gate valves and butterfly valves have been adopted in the fields of steam power generation, petrochemical industry, carriers, and oil tankers. Butterfly valves have normally been applied to fields where in narrow places installing the existing valves such as gate valves and ball valves have proven difficult due to the surrounding area and the heavier of these valves. Butterfly valves are used to control the mass flow of the piping system under low pressure by rotating the circular disk installed inside. The butterfly valve is benefitted by having simpler structure in which the flow is controlled by rotating the disc circular plate along the center axis, whereas the weight of the valve is light compared to the gate valve and ball valve above-mentioned, as there is no additional bracket supporting the valve body. The manufacturing company needs to acquire the performance and life test equipment, in the case of adopting the improving factors to detect leakage and damage on the seat of the valve disc. However, small companies, which are manufacturing the industrial valves, normally sell their products without the life test, which is the reliability test and environment test, because of financial and manpower problems. Furthermore, the failure mode analysis of the products failed in the field is likewise problematic as there is no system collecting the failure data on sites for analyzing the failures of valves. The analyzing and researching process is not arranged systematically because of the financial problem. Therefore this study firstly tried to obtain information about the failure data from the sites, analyzed the failure mode based on the field data collected from the customers, and then obtained field data using measuring equipment. Secondly, we designed and manufactured the performance and life test equipment which also have the real time monitoring system with the naked eye for the butterfly valves. The concept of this equipment can also be adopted by other valves, such as the ball valve, gate valve, and various others. It can be applied to variously sized valves, ranging from 25 mm to large sized valves exceeding 3000 mm. Finally, this study carries out the life test with square wave pressure, using performance and life test equipment. The performance found out that the failures from the real time monitoring system were good. The results of this study can be expanded to the other valves like ball valves, gate valves, and control valves to find out the failure mode using the real time monitoring system for durability and performance tests.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.155-161
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• 2009

Lithium secondary batteries have been widely used in the portable electric devices as power source. Recently it is expected that the realm of its applications expands to the markets such as energy storage medium of hybrid electric vehicle(HEV), electric vehicle(EV). Cathode active material is crucial in terms of performance, durability, capacity of lithium secondary batteries. It is urgent to develope the technology for mass production of cathode material to cope with the markets' demands in the near future. In this study, a calcination furnace running in real production line is modelled in 3D, and the thermal flow and gas flow after chemical reaction in the furnace is analyzed through numerical computations. Based on the results, it is shown that large volume of $CO_2$ gas is generated from chemical reaction. High concentration of $CO_2$ gas and it's stagnation is clearly found from the reactant containers in which the reaction occur to the bottom area of the furnace. It is also studied that 15% or more $CO_2$ mol fraction could affect to proper formation of $LiCoO_2$ through TGA-DSC analysis. The solutions to evacuate carbon dioxide from the furnace are suggested through the change of furnace design and operating condition as well.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.485-489
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• 2012

We investigated vanadium (V) loading effects on selective catalytic reduction (SCR) activity and $SO_2$ resistance using commercial SCR catalysts applied on a power plant and incinerator with different amounts of V loading. These catalysts were characterized using XRD, Raman, ICP, BET analysis and found to contain $TiO_2$ (anatase) supported $V_2O_5$ added $WO_3$ and $SiO_2$. The SCR activity of the catalysts increased by increasing either the $V_2O_5$ or the $WO_3$ loading amounts; the SCR activity of the catalysts added $WO_3$ is higher than that of $WO_3$-free catalysts. As the V loading amount in the catalyst increased, the $SO_2$ durability decreased. The $V_2O_5$ supported $TiO_2$ catalyst added $WO_3$ and $SiO_2$ inhibits the deactivation process by $SO_2$. The $SO_2$ resistance of catalysts added $SiO_2$ is higher than that of catalysts added $WO_3$.