• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.762-767
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• 2009

In this study, the feasibility of using vegetable oil extracted from tropical crop seed as a biodiesel feedstock was investigated by producing biodiesel and analysing the quality parameters as a transport fuel. In order to produce biodiesel efficiently, two step reaction process(pre-treatment and transesterificaion) was required because the tropical crop oil have a high content of free fatty acids. To determine the suitable acid catalyst for the pre-esterification, three kinds of acid catalysts were tested and sulfuric acid was identified as the best catalyst. After constructing the experimental matrix based on RSM and analysing the statistical data, the optimal pre-treatment conditions were determined to be 26.7% of methanol and 0.982% of sulfuric acid. Trans-esterification experiments of the pre-esterified oil based on RSM were carried out, then discovered 1.24% of KOH catalyst and 22.76% of methanol as the optimal trans-esterification conditions. However, the quantity of KOH was higher than the previously established KOH concentration of our team. So, we carried out supplemental experiment to determine the quantity of catalyst and methanol. As a result, the optimal transesterification conditions were determined to be 0.8% of KOH and 16.13% of methanol. After trans-esterification of tropical crop oil, the produced biodiesel could meet the major quality standard specifications; 100.8% of FAME, 0.45 mgKOH/g of acid value, 0.00% of water, 0.04% of total glycerol, $4.041mm^2/s$ of kinematic viscosity(at $40^{\circ}C$).

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.105.1-105.1
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• 2010

Korea Electric Power Research Institute (KEPRI) has developed a compact coal-gasification system to accumulate our experiment skills. The combustion furnace for residual oil was modified as a small size coal gasifier. Recently, coal feeding system was also upgraded to control coal feed rate more accurately. Our research group has conducted several experiments to find out the effect of $O_2$/coal ratio on the cold gas efficiency. Furthermore, the effect of $N_2$/coal ratio on the transport characteristics was also studied. According to the calculation of heat and mass balance, the cold gas efficiency was estimated to the maximum at $O_2$/coal ratio of around 0.73. But small size gasifier such as ours required higher value of $O_2$/coal ratio than that of the theoretical estimation. On the optimal $N_2$/coal ratio, we noticed that the coal feed rate was intimately related with the transporting gas pressure and the pipe diameter.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2349-2351
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• 2003

This paper reports a novel microfluidic system, by which microfluidic delivery, transport and control can be digitally realized in femtoliter scale. Microelectronic grade $N_2$ from a pressurized canister was passed through HPLC tubing into a micro injector. The micro injector was driven and controlled digitally by the control system that can apply various control parameters such as pulse frequencies. A front-end of micro nozzle was inserted the dyed oil to collect droplets injected. The diameter of a droplet was measured by a microscope and a CCD camera, and then its volume can be calculated on the assumption that the droplet is spherical. The micro nozzles were simply pulled in glass capillary tubes by the micro puller self-made, and the geometry parameters of the micro nozzles can be adjusted easily. Experiments have successfully been carried out, and the results demonstrated that the proposed digital micro injector possesses three significant advantages : precise ultra-small liquid volume in femtoliter scale, digital microfluidic control and micro devices fabricated by simple glass process, not based on IC process.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.4
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• pp.289-296
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• 2018

The offshore subsea platforms are connected to subsea pipelines to transport gas/oil from wells. The pipe is a multilayered structure of polymer and steel for compensating both flexibility and strength. The pipe also requires reinforcement structures to endure the extreme environmental conditions. A vertebrae structure of bend restrictors is one of the reinforcement structures installed to protect the subsea pipe from excessive bending deformations. In this study, structural behaviors of the subsea pipeline with bend restrictors are investigated by the multi-body contact analysis in Abaqus 6.14-2. Contact forces of each bend restrictor extracted from the multi-body contact analysis can be boundary conditions for topology design optimization in Altair Hyperworks 13.0 Hypermesh-Optistruct. Multiple design constraints are considered to obtain a manufacturable design with efficient material usage. Through the multi-body contact analysis with optimized bend restrictors, it is confirmed that the bending performance of the optimized design is enhanced.

• Journal of ILASS-Korea
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• v.1 no.3
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• pp.20-28
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• 1996

It is well known that drag reduction in single phase liquid flow is affected by polymer material, molecular weight, polymer concentration, pipe diameter, and flow velocity. Drag reduction in two phase flow can be applied to the transport of crude oil, phase change system such as chemical reactor, pool and boiling flow, and to present cavitation which occurs in pump impellers. But the research of drag reduction in two phase flow is not sufficient. The purpose of the present work is to evaluate the drag reduction by measuring pressure drop, void fraction whether polymer is added in the horizontal two phase system or not. Experiment has been conducted in a test section with 24 m of the inner diameter and 1,500 mm of the length. The used polymer materials are two kinds of polyacrylamide[PAAM] and co-polymer[A611P]. The polymer concentration was varied with 50, 100 and 200 ppm under the same experimental conditions. Experimental results were shown that the drag is higher reduced by co-polymer rather than polyanylamide.

• Journal of Ocean Engineering and Technology
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• v.32 no.2
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• pp.84-94
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• 2018

Subsea pipelines are designed to transport mixtures of oil, gas, and their associated impurities from a wellhead that can be in excess of approximately $100^{\circ}C$, while the external temperature may be approximately $5^{\circ}C$. Heat can be lost from a subsea pipeline containing a high-temperature fluid to the surrounding environment. It is important that the pipeline be designed to ensure that the heat loss is small enough to maintain sufficient flow from the unwanted deposition of hydrate and wax, which occurs at a critical temperature of about $40^{\circ}C$. Therefore, it is essential to estimate the heat loss of a subsea pipeline in various circumstances. In previous studies, overall heat transfer coefficient(OHTC) formulas were considered only for a single soil type. Thus, it is difficult to characterize the OHTC of the actual seabed with multiple soil layers. In this paper, an OHTC formula that considers multi-layered soils is proposed for more precise OHTC estimation.

• The KSFM Journal of Fluid Machinery
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• v.12 no.1
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• pp.35-42
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• 2009

The flow and heat/mass transfer characteristics on the squealer tip surface of a high-turning turbine rotor blade have been investigated at a Reynolds number of $2.09{\times}10^5$, by employing the oil-film flow visualization and naphthalene sublimation technique. The squealer rim height-to-chord ratio and tip gap height-to-chord ratio are fixed as typical values of $h_{st}/c$ = 5.5% and h/c = 2.0%, respectively, for turbulence intensities of Tu = 0.3% and 15%. The results show that the near-wall flow phenomena within the cavity of the squealer tip are totally different from those over the plane tip. There are complicated backward flows from the suction side to the pressure side near the cavity floor, in contrast to the plane tip gap flows moving toward the suction side after flow separation/reattachment. The squealer tip provides a significant reduction in tip surface thermal load with less severe gradient compared to the plane tip. In this study, the tip surface is divided into six different regions, and transport phenomena at each region are discussed in detail. The mean thermal load averaged over the squealer cavity floor is augmented by 7.5 percents under the high inlet turbulence level.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.105-111
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• 2020

Interest and demand for hydrogen sensors are increasing in the field of H₂ leakage detection during storage/transport/use and detection of H₂ dissolved in transformer oil for safety issues as well as in the field of breath analysis for non-invasively diagnosing a number of disease states for a healthy life. In this study, various ZnO-based sensors were synthesized by controlling the reduction in crystallite size, decoration of Pt nanoparticles, doping of electron donating atoms, and doping of various atoms with different ionic radii. The sensing response of the various prepared ZnO-based nanoparticles and quantum dots (QDs) for 10 ppm H₂ was investigated. Among the samples, the smallest-sized (3.5 nm) In³⁺-doped ZnO QDs showed the best sensing response, which is superior to those in previously reported hydrogen sensors based on semiconducting metal oxides. The higher sensing response of In-doped ZnO QDs is attributed to the synergic effects of the increased number of oxygen vacancies, higher optical band gap, and larger specific surface area.

• Korean Journal of Pharmacognosy
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• v.15 no.3
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• pp.121-127
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• 1984

Attempts were to investigate the effects of 'Bojungikgi-tang' on the digestive system, blood pressure and diuresis. The results showed that relaxing action was shown on the isolated ileum in mice and that strong antagonistic actions were seen on $BaCl_2$, acetylcholine and histamine-induced contraction of the ileum in mice and guinea-pigs that the relaxing effect of the intestinal smooth muscle was recognized. Inhibitory effects on transport rate in the small intestine of mice and castor oil-induced catharsis in mice were noted. Inhibitory action on the secretion of gastric juice, pH ascending effect and decreasing effect of the free acidity and total acidity were recognized. Continuous hypotensive action was seen, but when the vagus nerve was cut, hypotensive action was remarkably decreased. The diuretic effect was also recognized.

• The Journal of Internal Korean Medicine
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• v.11 no.1
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• pp.15-27
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• 1990

For the purpose of examing on the efficancy of the Boolwhangumjeonggisan and on the effect of the Boolwhangumjeonggisan, dropsy animals given water boil ding abstraction exgis power. What made an experiment, the motility of isolate ileume, anticathartic action, the action of gastric juice, tied pylous ulcer and inhibited vomitting. 1. Boolwhangumjeonggisan displayed great suppresion effect in regard to automatic movement of the motility of isolated of mice and displayed anti-acethylcholine action, antibarium chloride action. Thus, the origin of muscle relaxation for internal smooth muscle is admitted. 2. It displayed great rexation effect in regard to fraction of rat's stomach and displayed contentional effect in regard to a cetylcholine and barium chloride. 3. It decreased rat of barium sulfate transport through the small intestine of mice. 4. It recognized anti-cathartic action, rat suffered from leading diarrhea by caster oil. 5. Total activity, pepsin secretion decreased and increased the pH of stomach in Shay's method. 6. It recognized powerful prevention effect on tied pylous ulcer. 7. It inhibited vomitting by administration of CuSo4 in frog.