• Journal of the Korean Society of Mechanical Technology
• /
• v.13 no.3
• /
• pp.107-111
• /
• 2011

This carbon nano heating system was consisted of power supply equipment, a carbon fiber and a stainless flexible hose. carbon nano heating system was manufactured by carbon fiber of a power capacity 30kw/h and light-oil hot air heater in control plot was the heating capacity 30,000kcal/h, As the result, Temperature difference due to carbon nano heating system and hot air heater in greenhouse showed that air temperature at experimental greenhouse, comparison greenhouse were $14.8^{\circ}C$, $13.4^{\circ}C$ respectively. It was found that carbon nano heating system and light-oil hot air heater heating cost were 1,095,740won, 2,683,628won. therefore as heating cost saving 60%. Yield of tomatoes cultured in greenhouse using carbon nano heating pipe was 4% inclease. Economic analysis comparison between the carbon nano heating pipe and the hot air heater in greenhouse were 41% respectively.

• Journal of Power System Engineering
• /
• v.16 no.4
• /
• pp.30-36
• /
• 2012

A scroll expander has been designed to produce a shaft power from a R134a Rankine cycle for electricity generation. Heat was supplied to the Rankine cycle through a heat exchanger, which received heat from another cycle of water. In the water cycle, water was heated up in a boiler using biogenic solid fuel. The designed scroll expander was a horizontal type, and a trochoidal oil pump was employed for oil supply to bearings and Oldham-ring keys. For axial compliance, a back pressure chamber was created on the backside of the orbiting scroll base plate. Numerical study has been carried out to estimate the performance of the designed scroll expander. The expander was estimated to produce the shaft power of about 2.9 kW from a heat supply of 36 kW, when the temperature of R134a was $80^{\circ}C$ and $35^{\circ}C$ at the evaporator and condenser of the Rankine cycle, respectively. The expander efficiency was about 70.5%. When the amount of heat supply varied in the ranges of 7.5~55 kW, the expander efficiency changed in the range of 45.6~70.5%, showing a peak efficiency of 70.5% at the design shaft speed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.7
• /
• pp.9-15
• /
• 2018

The turbochargers, which are used widely in diesel and gasoline engines, are an effective device to reduce fuel consumption and emissions. On the other hand, turbo-lag is one of the main problems of a turbocharger. Bearing friction losses is a major cause of turbo lag and is particularly intense in the lower speed range of the engine. Current turbochargers are mostly equipped with floating bearings: two journal bearings and one thrust bearing. This study focused on the bearing friction at the lower speed range and the experimental equipment was established with a drive-motor, load-cell, magnetic coupling, and oil control system. Finally, the friction losses of turbochargers were measured considering the influence of the rotating speed from 30,000rpm to 90,000rpm, oil temperature from $50^{\circ}C$ to $100^{\circ}C$, and oil supply pressure of 3bar and 4bar. The friction power losses were increased exponentially to 1.6 when the turbocharger speed was increased. Friction torques decreased with increasing oil temperature and increased with increasing oil pressure. Therefore, the oil temperature and pressure must be maintained at appropriate levels.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.21 no.4
• /
• pp.239-245
• /
• 1988

As a part of the studies on effective utilization of polyunsaturated lipids in sardine (Sardinops melanosticta) when the refined sardine oil was added to surimi-based product as a dietary supplement of biologically active fatty acids, eicosapentaenoic aicd and docosahexaenoic acid, storage stability and the effect to the qualify of the product was tested. Addition of the refined sardine oil up to $5\%$ to surimi did not affect the textural properties of the product. And the polyunsaturated fatty acids of the sardine oil was fairly stabilized when it stored for 1 month at room temperature and 43 days at $5^{\circ}C$. These results suggested the possibility that the refined sardine oil or other fish oils containing highly polyunsaturated fatty acids, especially EPA and DHA could be used as a food ingredient for dietary supply of the lipids.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.7 no.1
• /
• pp.67-77
• /
• 1999

The biodegradation of algae coagulated with poly aluminum chloride(PAC) was investigated by using the thermophilic oxic process. The compositions of coagulated algae were 83.5% of water content, 24.6% of ash, 32% of organic carbon with in total solid, respectively. In present study, food waste oil was used for the increment of calorie of mixtures in order to accelate the microbial activity. As a result, the maximum temperature of mixtures was higher than $50^{\circ}C$ when the mixing ratio of food oil was over 10%. However the temperature indicated the lower than $50^{\circ}C$ when conditions of no mixing with waste food oil, and 5% of mixing ratio. Therefore, the optimum condition was 10% of the mixing ration at $217l{\cdot}m^{-3}{\cdot}min^{-1}$ of air supply rate. The conversion efficiency of carbon was highest as 92% at the optimum condition. And then water was evaluated from imxture without accumulation at 10% of mixing ratio. The thermophilic oxic process well conducted that is good process for the treatment of waste algae without effluents however it has to consider the retreatment of accumulated aluminum in the reactor.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.11a
• /
• pp.87-90
• /
• 2006

The experimental study has been done for two kinds of pelletized RDFs to Investigate the carbonization effect to the chlorine concentrations, the heating value and the yield of Produced char in variable conditions of the carbonizing temperature and reaction time. One(RDF-1) is made of 100% wasted plastics and the other(RDF-2) is made of 60% wasted paper with 40% wasted plastics. The screw type carbonizer heated Indirectly by oil burner was used for the experiment and RDF feeding rate was 3kg/hr. The carbonizing temperature was 300, 350 400 and $45^{\circ}C$ and the reaction tine was 5, 10 and 15 minutes respectively. As the increase of carbonizing reaction time and temperature, the chlorine reduction rate was increased and oppositely the yield of char was decreased At the temperature of $400^{\circ}C$ and reaction time of 10 minutes the chlorine reduction rate was 60% and the char yield rate was 80% for the RDF-1 and those of RDF-2 were 80% and 75%, respectively. Additional activation experiment to the char produced from RDF-2 was done in the activation reactor by hot steam supply. As the increase of activation time the iodine number was increased. At the activation time of 20 minutes the iodine number was 552mg/g and the yield of activated carbon was 16%.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.5
• /
• pp.447-452
• /
• 2016

The use of gas as fuel, particularly liquefied natural gas (LNG), has increased in recent years owing to its lower sulfur and particulate emissions compared to fuel oil or marine diesel oil. LNG is a low temperature, volatile fuel with very low flash point. The major challenges of using LNG are related to fuel bunkering, storing, and handling during ship operation. The main components of an LNG fuel system are the bunkering equipment, fuel tanks, vaporizers/heaters, pressure build-up units (PBUs), and gas controlling units. Low-pressure dual-fuel (DF) engines are predominant in small LNG-powered vessels and have been operating in many small- and medium-sized ferries or LNG-fueled generators.(Tamura, K., 2010; Esoy, V., 2011[1][2]) Small ships sailing at coast or offshore rarely have continuous operation at constant engine load in contrast to large ships sailing in the ocean. This is because ship operators need to change the engine load frequently due to various obstacles and narrow channels. Therefore, controlling the overall system performance of a gas supply system during transient operations and decision of bunkering time under a very poor infrastructure condition is crucial. In this study, we analyzed the fuel consumption, the system stability, and the dynamic characteristics in supplying fuel gas for operating conditions with frequent engine load changes using a commercial analysis program. For the model ship, we selected the 'Econuri', Asia's first LNG-powered vessel, which is now in operation at Incheon Port of South Korea.

• Journal of Korea Foundry Society
• /
• v.29 no.5
• /
• pp.238-243
• /
• 2009

This study has been carried out to investigate the cooling ability improvement of diecasting mold by decompression cooling system. The decompression cooling system was applied to the new/used oil pump cover molds. The temperature of the surface mold applied the decompression cooling system fell to 15 degrees, especially in case of the used mold. The defect ratio of the oil pump cover manufactured by decompression cooling system has decreased from 2.8 percent to 0.2 percent. According to the results of the cooling ability improvement of diecasting mold by decompression cooling system, the decompression degree and supply pressure were set up the control item to apply the decompression cooling system to the diecasting mold in the industry field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1135-1138
• /
• 2003

The transformer is major equipment in power receiving and substation facilities. Necessary conditions required for the transformer are compactness, lightness, high reliability, economic advantages, and easy maintenance. The pole-mount transformer installed in distribution system is acting direct role in supply of electric power and it is electric power device should drive for long term. Most of modem transformer are oil-filled transformer and accident is happening considerable. The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. One body molding transformer needs some cooling method because heat radiation between each winding is difficult. In this paper, The thermal analysis of pole mount mold transformer with one body molding by duct condition is investigated and the test result of temperature rise is compared with simulation data.

• Journal of Aquaculture
• /
• v.10 no.4
• /
• pp.473-483
• /
• 1997

Yolk resorotion and commencement of external feeding in larvae of red spotted grouper, Epinepheus akaara were studied to understand the high mortality of larvae. Consumption of yolk was higher than that of oil globule for the first 24hs after hatching. The resorption rates of yolk and oil globule increased with the increase of temperature. The time yolk was comsumed up to 99% was 84hs after hatching in 23~$25^{\circ}C$,72hs at ~$27^{\circ}C$, and 60hs in 29~~$31^{\circ}C$, while the time for oil globule was 96hs in 23~$25^{\circ}C$, 84hs at $27^{\circ}C$, and 60hs in 29~$31^{\circ}C$. The relationship between mouth openning time (Y) and water temperature (X) was repersented as a linear regression, Y=-2.53X+118.4, (r2=0.89). In 72~96hs after hatching, upper jaw sizes of the larvae reached around 0.114 mm. By the time the larvae comsumed most of the yolk and oil globule, and started external feeding. The relationship between upper jaw length (Y) and total length (X) was represented as a linear regression, Y=0.139X-0.165, (r2=0.88). Rotifer was not found in the guts of larvae before 72hs after hatching at $28^{\circ}C$, when larvae resorbed their yolk and oil globule over 99%. But, at 96hs after hatching, about 33% of the larvae had the rotifer in their guts. Delayed feeding experiments revealed that the earlier food supply within 84hs after hatching showed the better survival rates for the larvae. The larvae fed at 96hs after hatching died all within 120hs.