• Journal of Navigation and Port Research
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• v.48 no.2
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• pp.125-136
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• 2024

This research presents an innovative integrated ethanol solid oxide fuel cell (SOFC) system designed for applications in marine vessels. The system incorporates an exhaust gas heat recovery mechanism. The high-temperature exhaust gas produced by the SOFC is efficiently recovered through a sequential process involving a gas turbine (GT), a regenerative system, steam Rankine cycles, and a waste heat boiler (WHB). A comprehensive thermodynamic analysis of this integrated SOFC-GT-SRC-WHB system was performed. A simulation of this proposed system was conducted using Aspen Hysys V12.1, and a genetic algorithm was employed to optimize the system parameters. Thermodynamic equations based on the first and second laws of thermodynamics were utilized to assess the system's performance. Additionally, the exergy destruction within the crucial system components was examined. The system is projected to achieve an energy efficiency of 58.44% and an exergy efficiency of 29.43%. Notably, the integrated high-temperature exhaust gas recovery systems contribute significantly, generating 1129.1 kW, which accounts for 22.9% of the total power generated. Furthermore, the waste heat boiler was designed to produce 900.8 kg/h of superheated vapor at 170 ℃ and 405 kP a, serving various onboard ship purposes, such as heating fuel oil and accommodations for seafarers and equipment.

• Safety and Health at Work
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• v.7 no.1
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• pp.63-71
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• 2016

Background: Construction painters have not been studied well in terms of their hazards exposure. The objective of this study was to evaluate the exposure levels of total volatile organic compounds (TVOCs) for painters in the construction industry. Methods: Activity-specific personal air samplings were carried out in three waterproofing activities [polyurethane (PU), asphalt, and cement mortar] and three painting activities (epoxy, oil based, and water based) by using organic-vapor-monitor passive-sampling devices. Gas chromatograph with flame ionization detector could be used for identifying and quantifying individual organic chemicals. The levels of TVOCs, by summing up 15 targeted substances, were expressed in exposure-index (EI) values. Results: As arithmetic means in the order of concentration levels, the EIs of TVOCs in waterproofing works were 10.77, 2.42, 1.78, 1.68, 0.47, 0.07, and none detected (ND) for indoor PU-primer task, outdoor PU-primer task, outdoor PU-resin task, indoor PU-resin task, asphalt-primer task, asphalt-adhesive task, and cement-mortar task, respectively. The highest EI for painting works was 5.61 for indoor epoxyprimer task, followed by indoor epoxy-resin task (2.03), outdoor oil-based-spray-paint task (1.65), outdoor water-based-paint task (0.66), and indoor oil-based-paint task (0.15). Assuming that the operations were carried out continuously for 8 hours without breaks and by using the arithmetic means of EIs for each of the 12 tasks in this study, 58.3% (7 out of 12) exceeded the exposure limit of 100% (EI > 1.0), while 8.3% (1 out of 12) was in 50e100% of exposure limit (0.5 > EI > 1.0), and 4 tasks out of 12 were located in less than 50% of the limit range (EI < 0.5). Conclusion: From this study, we recognized that construction painters are exposed to various solvents, including carcinogens and reproductive toxins, and the levels of TVOC concentration in many of the painting tasks exceeded the exposure limits. Construction workers need to be protected from chemical agents during their painting works by using personal protective devices and/or work practice measures. Additional studies should focus on the exposure assessment of other hazards for construction workers, in order to identify high-risk tasks and to improve hazardous work environments.

• Food Science and Preservation
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• v.16 no.6
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• pp.810-816
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• 2009

To identify effective food packaging compounds that could significantly affect the freshness of stored food, the efficiency and performance of porous polypropylene film containing mustard oil as a freshness maintenance ingredient was studied by GC-MS analysis and storage testing of bread. AITC (allyl-isothiocyanate)-emitting properties of films impregnated with mustard oil were evaluated by GC-MS. AITC was extracted from mustard oil, and used as a vapor as an effective antimicrobial agent. Films were prepared under four different conditions (the film types were abbreviated 25SF1, 25SF2, 50LF, and IAF) and the amounts of AITC inside vinyl packs constructed using the four films were measured. The results showed that the 25SF2 film (width 25 mm, length 20 cm) yielded a greater amount of AITC than did the 50LF film (width 50 mm, length 20 cm). We confirmed that the amount of gas emission showed better between layer and layer of the film side than the internal film. In storage testing using various films at $35^{\circ}C$ for 25 days, 25SF2 film provided excellent preservation of bread compared with 50LF film. This was in line with the fact that 25SF2 film yielded the highest amount of AITC. Emission capacities AITC of 2 cm film were measured using bottles various volumes (43 mL, 500 mL, 1000 mL) and both closed and open systems. The AITC content of the film in 43 mL bottle was much higher than that yielded by other films in the closed system, and AITC was rapidly emitted, with relatively low residual gas emission after 4 days in an open system. Mustard oil is a useful freshness maintenance ingredient hence, analysis of AITC emission kinetics from various films were helpful to develop films with optimal antimicrobial effects, and will allow application of such films in food packaging systems.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.124-129
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• 2015

An experimental study was performed estimating COP(Coefficient of Performance) of air-conditioning cycle using inverter scroll compressor with and without $Al_2O_3$ nano particle. All experiments were done for various compressor speeds from 1000~4000 rpm and used the inverter controller called CANDY to change the compressor rpm. The air-conditioning cycle components in the apparatus were used as same with components of YF hybrid car. To estimate the COP, this study measured the temperature and pressure at inlets and outlets of compressor, condenser, and evaporator. And also measured the compressor input power using Powermeter. Through the experiments, the maximum error to estimate COP was shown about ${\pm}6.09%$ at 3500rpm. The COP of refrigeration cycle with $Al_2O_3$ nano-particle was similar with that of the base cycle without nano-particle between 1000~3000 rpm of the compressor speed. But, This study showed that the COP of the cycle with $Al_2O_3$ over 3000 rpm of the compressor speed was higher than that of the base cycle due to the higher heat transfer rate increased in the evaporator from the higher oil flow rate inside the cycle as well known. Those results can be used the basic and fundamental data to design the air-conditioning cycle using inverter scroll compressor with $Al_2O_3$ nano particle.

• Journal of Radiation Protection and Research
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• v.33 no.1
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• pp.35-40
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• 2008

A distillation tower is one of the important facilities which separates and refines a crude oil stream according to certain boiling points. Its operation efficiency can affect the productivity of a refinery substantially. The objective of this study is to elucidate some operational information on the internal conditions of a distillation tower from a measurement of density profile by using a sealed gamma-ray source and a radiation detector. Gamma radiation counts were measured by a BGO detector positioned diametrically outside the tower-wall, opposite to the gamma source(Co-60) as the detector and the source were lowered concurrently. From the results, structural abnormality of the trays was not found inside the tower. Considering the flow distribution patterns, however, a vapor phase was dominantly formed at the upper part of the tower and a liquid phase at the lower part. From the gamma scanning of the distillation tower, it is anticipated that the gamma absorption technique can be used as an important tool for confirming the structural soundness of trays and investigating flow distribution in refinery facilities.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.909-916
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• 2015

In this study, to investigate the effect of spray behavior characteristics, we induce the mixing ratio of emulsified fuel using impinging spray. We formulate the emulsified fuel by mixing diesel and hydrogen peroxide($H_2O_2$). We set the temperature of the heating plate to $150^{\circ}C$, $200^{\circ}C$, and $250^{\circ}C$, and set the injection pressures to 400, 600, 800, and 1000bar. The surfactants for the emulsified fuel mixture, which were mixed span80 and tween80 was mixed as 9:1, were fixed to 3% of the total volume of the emulsified fuel. We set the mixing ratio of $H_2O_2$ in the emulsified fuel as emulsified fuel(EF)0, EF2, EF12, and EF22. Further, we visualize the evaporation impinging spray using the Schlieren method. Based on the results of this study, we found that a higher temperature and injection pressure of the heating plate impingement led to the active diffusion of the fuel vapor, which promoted emulsified fuel evaporation. When the emulsified fuel is utilized in an actual engine, because of the temperature-drop effect of the combustion chamber, which is due to the evaporation of $H_2O_2$ in fuel and faster mixture formation is expected to decrease the engine emissions.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.2
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• pp.59-72
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• 2009

In order to utilize sewage sludge as a heat source of energy, it goes without saying that the fuel should be clean and pose no threat to the environment. As a consequent, it should not contain even minute quantities of heavy metals / impurities. The SOCA (Sludge-Oil-Coal- Agglomerates) fuel can meet all these requirements. SOCA being a solid fuel can be gasified for the production of clean energy. Wet catalytic gasification is the most appropriate process for SOCA containing nearly 60% water. It is important to note that the SOCA thus obtained inherits ca. 40~50% of sulfur from the coal used. It can poison the catalyst during catalytic gasification process. Consequently, it becomes important to choose a proper catalyst for the gasification. Calcium was found to be ideal choice as a catalyst for the gasification of SOCA. The optimal gasification was performed at $850^{\circ}C$ with water vapor. The role of fuel-N is of utmost importance in the gasification of SOCA. The gasification should be controlled to reduce the production of HCN to a minimum and enhance its conversion to $N_2$ and/or $NH_3$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.191-196
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• 2010

Hybrid heat pumps, which combine the vapor compression and absorption heat pump cycle, can efficiently produce hot water of $80^{\circ}-90^{\circ}C$ from the low temperature of ${\sim}50^{\circ}C$. In this study, the performance of a two-stage hybrid heat pump (HHP) was compared with a single-stage hybrid heat pump using EES (Engineering Equation Solver). For the same operating conditions, the two-stage HHP showed a slightly higher COP (Coefficient Of Performance) and more stable operating conditions than the single-stage HHP. Moreover, the maximum working fluid temperature of the two-stage HHP was found to be lower than that of the single-stage HHP by about 40 K, which makes the working conditions of the lubricating oil safer. The COPs of both systems decreased with increasing UA-values. However, the heat output of the HHP was increased at the same time.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.150-150
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• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.21-27
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• 2018

FRN (Full range Naphtha) is distilled from crude oil in a Naphtha Splitter Unit and is separated into the Light Straight Naphtha, Heavy Naphtha, and kerosene according to the boiling point in sequence. This separation is conducted using a series of binary-like columns. In this separation method, the energy consumed in the reboiler is used to separate the heaviest components and most of this energy is discarded as vapor condensation in the overhead cooler. In this study, the first two columns of the separation process are replaced with the Petlyuk column. A structural design was exercised by a stage to stage computation with an ideal tray efficiency in the equilibrium condition. Compared to the performance of a conventional system of 3-column model, the design outcome indicates that the procedure is simple and efficient because the composition of the liquid component in the column tray was designed to be similar to the equilibrium distillation curve. An analysis of the performance of the new process indicated an energy saving of 12.3% under same total number of trays and with a saving of the initial investment cost.