• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.999-1004
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• 2010

Recently, many technologies have been developed in order to satisfy stringent emission regulations. However, in the case of diesel engines, the stringent emission regulations with respect to NOx and PM have not yet been satisfied. A dramatic reduction in the NOx and PM emissions could be achieved by using after-treatment systems such as lean NOx trap (LNT) and urea-SCR systems. However, the high temperature in the exhaust pipe affects the spray behavior of the secondary injector, which is used for supplying the Urea-SCR. Because of this high temperature, it is difficult to achieve uniform distribution of the reducing agent in the manifold. In this paper, the characteristics of a urea-SCR injector used for injecting in the exhaust pipe are presented. The purpose of this study was to investigate the spray characteristics of the injector, such as the spray angle, injection quantity, and SMD. In addition, laser diagnostics and high-speed-camera images were used to analyze the injector spray characteristics and to present a distribution of reduction in the transparent manifold.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.7
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• pp.463-468
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• 2017

For transdermal drug delivery, needless injection system is composed of laser and microjet injector. Main mechanism of microjet injector is the laser-induced bubble. Nd:YAG and Er:YAG laser are used as a power source. Laser parameters such as pulse duration and wavelength are considered, which are core parameters to control the bubble motion. The Nd:YAG laser, pulse duration is short than bubble life time making cavitation like bubble while in Er:YAG laser, long pulse duration and high absorption in water drive bubble as a boiling bubble. Detailed motion of bubble and microjet is captured by the high speed camera. So it is observed that microjet characteristics are determined by the bubble behavior. The performance of drug delivery system is evaluated by fluorescent staining of guinea pig skin.

• International Journal of Industrial Entomology and Biomaterials
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• v.4 no.1
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• pp.43-49
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• 2002

We have cloned cDNAs encoding toxin from the spider, Araneus ventricosus, and constructed a recombinant baculovirus expressing the insecticidal toxin. The cDNAs encoding toxin were cloned from the cDNA library of A. ventricosus. Sequence analysis of the cDNAs encoding the toxin of A. ventricosus revealed that the 240 bp cDNA for AvTox-1 and 192 bp cDNA for AvTox-2 have an open reading frame of 80 and 64 amino acid residues, respectively. The deduced protein sequence of the toxin genes of AvTox-1 and AvTox-2 was aligned to that of the snack Anemonia sulcata and scorpion Centruroides limpidus limpidus, respectively. Northern blot analysis indicated that AvTox-2 toxin gene showed a fat body-spe-cific expression pattern at the transcriptional level. Furthermore, we have explored the possibility of improving baculovirus by incorporating the A. vontricosus toxin gene into Bombyx mori nuclear polyhedrosis virus genome under the control of polyhedrin promoter, The AvTox-2 toxin gene was expressed as approximately 5.8 kDa band in the recombinant baculovirus-injected silkworm larvae. Bioassays with the recombinant virus expressing AvTox-2 on 5th instar silkworm larvae demonstrated a decrease in the time to kill $(LT_{50} days)$ compared to wild-type BmNPV-Kl $(LT_{50} 6.72 days)$ in the injection of 10 viruses. These results indicate that A. ventricosus toxin is a novel member of the spider toxin family, suggesting that the toxin gene can be used in recombinant baculoviruses to reduce insect feeding damage and increase the speed of insect kill.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.981-984
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• 2011

A high-resolution numerical study is carried out to investigate the transient process of the combustion and the shock-train developments in an ethylene-fueled direct-connect dual-mode scramjet combustor. Following the fuel injection, air-throttling is applied at the expansion part of the combustor to provide mass addition to block the flow to subsonic speed. The ignition occurs several ms later when the fuel and air are mixed sufficiently. The pressure build up by the combustion leads to the shock train formation in the isolator section that advances to the exit of the intake nozzle. Then, the air-throttling is deactivated and the exhaust process begins and the situation before the air-throttling is restored. Present simulation shows the detailed processes in the dual-mode scramjet combustor for better understanding of the operation regimes and characteristics.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.74-78
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• 1976

In this paper, the author experimented, by using the C. F. R. engine, how the functions of engine is changed when the compression ratio is raised. In the process of these experiments, by using three kinds of fuel, such as cetane number 95, 61, 33, and set the engine speed as 900 r. p. m., fuel injection time is determined as B. T. D. C. $13^{\circ}$. As the result of test, the best compression ratio is disernable in proportion to each fuel, and acknowledges that if the higher compression ratio were to exist other than the above one, efficiency of heat gets rather lower, and that the maximum output of engine decreases. Andthe best compression ratio changed according to supply calorie per each hour, and this change is more remarkable in the fuel of low cetane number. Consequently, the best compression ratio cannot be regardless of output in the fuel of low cetane number.

• Korean Journal of Medicinal Crop Science
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• v.24 no.1
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• pp.1-6
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• 2016

Background : Irregular meals and insufficient exercise are major modern lifestyle-related risk factors for constipation. This study aimed to examine the effects of the aqueous extract of Dendrobium speciosum var. (DM) on the improvement of intestinal function and prevention of constipation in rats. Methods and Results : Constipation in rat was induced by loperamide (4 mg/kg) injection for 5 days and rats were randomly assigned to the following groups: normal control rats (NOR), constipated rats (LOP induced) and constipated rats supplemented with dulcolax-S (POS), DMSG, 100 mg/kg (DMSG-100), 300 mg/kg (DMSG-300) and 500 mg/kg (DMSG-500). The DMSG groups showed increments in the frequency and amount of stools compared to the LOP group. Loperamide treatment markedly reduced the water content of feces, whereas DMSG administration significantly increased fecal water contents. Moreover, DMSG improved intestinal transit speed in constipated-rats. Alcian blue staining revealed increased mucus production by crypt cells and mucus contents in feces and the mucosal surface. Conclusions : In summary, DM extraction significantly improves intestinal function in rats, which indicates the effectiveness of this extract in the prevention and treatment of constipation.

• Journal of Korea Foundry Society
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• v.29 no.6
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• pp.277-283
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• 2009

Recently an increase in production cost of 300 series stainless steel with a sudden increase in nickel cost has caused a decrease in demand for 300 series stainless steel so that 400 series stainless steel has begun to make a mark. Although 400 series stainless steel has good properties, it has a problem of lack of corrosion resistance. There is Ti in 400 series stainless steel alloys to solve the problem above and it has lower density than the others. For that reason, wire feeding process has been applied for adding Ti alloy in 400 series stainless steel. This paper presents consideration of variation on the depth of wire dissolution by conditions of wire feeding which are wire injection speed, the temperature of molten steel, wire diameter and bubble generation rate. The computer program for solution of conducting wire feeding has been developed in Flow3D.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.764-767
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• 2003

The characteristics of diesel spray have much effect on the engine performances such as power. fuel consumption rate and emissions. Therefore, the measurement of fuel spray characteristics is very important for the improvement of heat engine. The factors which control diesel spray characteristics are injection pressure, ambient temperature and density etc. Spray behaviors are visualized by using the high speed video camera and spray angle, spray penetration are measured. Experimental equations of spray penetration and spray angle were derived by using the experimental results. 1) Ambient temperature and density influence on the characteristics of diesel spray. 2) Experimental equation of spray penetration is expressed as follows 0＜t＜ $t_{b}$ ; $S_1$=11.628$\Delta$ $P^{0.485}$ $\rho$$_{a}$ $^{-0.478}$ $t^{1.337}$, $t_{b}$ ＜t; $S_2$=7.457$\Delta$ $P^{0.523}$ $\rho$$_{a}$ $^{-0.382}$ $t^{0.548}$ 3) Experimental equation of spray Angie is expressed as follows $T_{a}$ =293K; Tan($\theta$/2)=059($\rho$$_{a}$ / $\rho$$_{f}$ )$^{0.437}$, $T_{a}$ =473K; Tan($\theta$/2)=0588($\rho$$_{a}$ / $\rho$$_{f}$ )$^{0.404}$_{f}$ )$^{0.404}$

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.5
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• pp.724-732
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• 2002

Although the demands for diesel engine is increased, our world is faced with very serious problems related to the air pollution due to the exhaust emissions of the diesel engine. In this study, the potential possibility of oxygenated fuel such as Methyl tertiary butyl ether (MTBE) was investigated for the sake of exhausted smoke reduction from diesel engine. MTBE has been used as a fuel additive blended into unleaded gasoline to improve octane number, but the study of application for diesel engine was incomplete. Because MTBE includes oxygen content approximately 18%, it is a kind of oxygenated fuel that the smoke emission of MTBE is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at high load and speed in diesel engine. But, the NOx emission of MTBE blended fuel is increased compared with commercial diesel fuel. And. it was tried to analyze not only total hydrocarbon but individual hydrocarbon components from $C_1$to $C_{6}$ in exhaust gas using gas chromatography to seek the reason for remarkable reduction of smoke emission. The results of this study show three conclusions. 1. The smoke omission of the MTBE blended fuel is lower than that of the diesel fuel at all experimental region in direct injection diesel engine. 2. Individual hydrocarbons(C$_1$~ $C_{6}$) as well as total hydrocarbon of oxygenated fuel are reduced remarkably compared with diesel fuel. 3. Smoke emission from diesel engines was strongly depended on oxygen content in fuel regardless of operating condition.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.508-514
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• 2010

The objective of this work presented here was experimental study of steadystate and cold start exhaust nano-sized particle characteristics from common rail diesel engine. The effect of the diesel oxidation catalyst (DOC) on the particle number reduction was insignificant, however, particle number concentration levels were reduced by 3 orders of magnitude into the downstream of diesel particulate filter (DPF). In high speed and load conditions, natural regeneration of trapped particle occurred inside DPF and it was referable to increase particle number concentration. As fuel injection timing was shifted BTDC $6^{\circ}CA$ to ATDC $4^{\circ}CA$, particle number concentration level was slightly reduced, however particle number and size was increased at ATDC $9^{\circ}CA$. Nucleation type particle reduced and accumulation type particle was increased on EGR condition.