• The Korean Journal of Community Living Science
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• v.25 no.4
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• pp.557-566
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• 2014

This study examines he trend in the development of protective clothing for pesticide spraying based on materials with domestic patents and proposes pesticide protection clothing using a cooling blower unit effective for reducing heat stress in pesticide spraying. There was a total of 54 domestic patents on protective clothing related to pesticide spraying, reflecting a sharp increase based on the increasing demand for protective clothing since 2000. Protective clothing with a lower level of heat stress as the core technology accounted for 35.2% of these patents, and recent years have witnessed the increased development of protective clothing supplying cold air to the interior of the clothing through a separate device. However, this may cause some inconvenience in the activity of farmers. Therefore, this study proposes a lightweight cooling blower unit that does not hinder the user's appearance and activity. In the cooling blower unit, contaminated air from outside is purified through a filter and cools down as it passes a cooling device with refrigerant in the copper pipe. This chilled air is supplied to the interior of the clothing through a bidirectional inhaling blower. The proposed protective clothing is an overall with raglan sleeves. Its chill injection site has an area where the most conspicuous change in temperature is selected, and at the back, there is a large pocket for a cooling blower unit.

• International Journal of Oral Biology
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• v.35 no.3
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• pp.75-81
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• 2010

The present study investigated the role of ERK in the onset of mechanical and cold allodynia in a rat model of compression of the trigeminal ganglion by examining changes in the air-puff thresholds and number of scratches following the intracisternal injection of PD98059, a MEK inhibitor. Male Sprague Dawley rats weighing between 250 and 260 g were used. Under anesthesia, the rats were mounted onto a stereotaxic frame and received 4% agar ($10\;{\mu}l$) solution to compress the trigeminal ganglion. In the control group, the animals were given a sham operation without the application of agar. Changes in behavior were examined at 3 days before and at 3, 7, 10, 14, 17, 21, 24, 30, and 40 days after surgery. Compression of the trigeminal ganglion significantly decreased the air-puff thresholds. Mechanical allodynia was established within 3 days and persisted over postoperative day 24. To evaluate cold allodynia, nociceptive scratching behavior was monitored after acetone application on the vibrissa pad of the rats. Compression of the trigeminal ganglion was found to produce significant cold allodynia, which persisted for more than 40 days after surgery. On postoperative day 14, the intracisternal administration of $1\;{\mu}g$ or $10\;{\mu}g$ of PD98059 in the rat model significantly decreased the air-puff thresholds on both the ipsilateral and contralateral side. The intracisternal administration of $10\;{\mu}g$ of PD98059 also significantly alleviated the cold allodynia, compared with the vehicle-treated group. These results suggest that central ERK plays an important role in the development of mechanical and cold allodynia in rats with compression of the trigeminal ganglion and that a targeted blockade of this pathway is a potential future treatment strategy for trigeminal neuralgia-like nociception.

• Journal of Energy Engineering
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• v.2 no.3
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• pp.268-275
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• 1993

A series of parametric investigations are performed in order to resolve the flow characteristic of a Quebec city stoker incinerator. The parameters considered in this study are five internal configurations of the Quebec city stoker itself and its modified ones, primary air velocity, the injection velocity and angle of the secondary air, and the reduction of the stoker exit area. A control-volume based finite-difference method by Patankar together with the power-law scheme is employed for discretization. The resolution of the pressure-velocity coupling is made by the use of SIMPLEC algorithm. The standard, two equation, k-$\varepsilon$ model is incorporated for the closure of turbulence. The size of recirculation region, turbulent viscosity, the mass fraction of the secondary air and pressure drop are calculated in order to analyze the characteristics of flow field. The results are physically acceptable and discussed in detail. The flow field of the Quebec city stoker shows the strong recirculation zone together with the high turbulence intensity over the upper part of the incinerator.

• Journal of Powder Materials
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• v.22 no.3
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• pp.197-202
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• 2015

In this study, porous stainless steel (STS316L) sintered body was fabricated by powder metallurgy method and its properties such as porosity, compressive yield strength, hardness, and permeability were evaluated. 67.5Fe-17Cr- 13Ni-2.5Mo (wt%) powder was produced by a water atomization. The atomized powder was classified into size with under $45{\mu}m$ and over $180{\mu}m$, and then they were compacted with various pressures and sintered at $1210^{\circ}C$ for 1 h in a vacuum atmosphere. The porosities of sintered bodies could be obtained in range of 20~53% by controlling the compaction pressure. Compressive yield strength and hardness were achieved up to 268 MPa and 94 Shore D, respectively. Air permeability was obtained up to $79l/min{\cdot}cm^2$. As a result, mechanical properties and air permeability of the optimized porous body having a porosity of 25~40% were very superior to that of Al alloy.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1050-1056
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• 2010

Diesel engines introduce only air into the cylinder, and the air is high lycompressed. Fuel is directly injected into the combustion chamber in high temperature and pressure. Therefore diesel engines have high thermal efficiency because of the high compression ratio, while having high level of particulate matter and nitrogen oxide emissions because of the direct fuel injection. Many technologies have been developed to reduce particulate matter and nitrogen oxide emissions from diesel engines. One of the technologies is hydrogen fuel introduced into the combustion chamber with diesel fuel. In this thesis tiny amount of hydrogen is supplied into the combustion chamber in order to enhance the combustion performance. The engine, in which hydrogen is introduced, is tested. There are 20 test conditions given as 5 torque values of 100%, 75%, 50%, 25%, 0%, and 4 engine speeds of 700rpm, 1000rpm, 1500rpm and 2000rpm for the two cases with or without hydrogen addition. Maximum torques and Idle torques at each engine speed are measured, then the torque values are divided into 4 levels with 25% increasing step. The result shows that the fuel consumption, smoke, CO are reduced while the NOx emission is slightly increased, and the hydrogen addition has not a great effect on the performance at low loads but a great effect at a maximum load.

• Journal of Mechanical Science and Technology
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• v.14 no.10
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• pp.1131-1142
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• 2000

In an effort to illustrate the global variation of SMD (Sauter mean diameter, or $D_{32}$) and AMD (Arithmetic mean diameter, or $D_{10}$) at five axial downstream locations (i. e., at Z=30, 50, 80, 120, and 170 mm) under the different experimental conditions, the radial coordinate is normalized by the spray half-width. Experimental data to analyze the atomization characteristics concerning with an internal mixing type have been obtained using a PDPA(Phase Doppler Particle Analyzer). The air injection pressure was varied from 40 kPa to 120 kPa. In this study, counterflowing internal mixing nozzles manufactured at an angle of $15^{\circ}$with axi-symmetric tangential-drilled four holes have been considered. By comparing the results, it is clearly possible to discern the effects of increasing air pressure, suggesting that the disintegration process is enhanced and finer spray droplets can be obtained under higher air assist. The variations in $D_{32}$ are attributed to the characteristic feature of internal mixing nozzle in which the droplets are preferentially ejected downward with strong axial momentum, and dispersed with the larger droplets which are detected in the spray centerline at the near stations and smaller ones are generated due to further subsequent breakup by higher shear stresses at farther axial locations. The poor atomization around the centre close to the nozzle exit is attributed to the fact that the relatively lower rates of spherical particles are detected and these drops are not subject to instantaneous breakup in spite of the strong axial momentum. However, substantial increases in SMD from the central part toward the edge of the spray as they go farther downstream are mainly due to the fact that the relative velocity of droplet is too low to cause any subsequent disintegration.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.1
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• pp.57-63
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• 2008

In combustor of SCRamjet of air-breathing engine type, the flow duration time is very short because of the supersonic air flow. In this short duration, the whole process of combustion should be done, so it is very important to study supersonic combustion technologies. In this study, we focus fuel-air mixing enhancement method using cavity and conducted 3-dimensional Navier-Stokes computational analysis. Cavity height is fixed by 10mm, length is changed from 0 to 40mm. There is a supersonic jet injection downstream of the cavity and the hole size is 1mm. As a result, the higher ratio of cavity length/height is, the higher value of vorticity gets. The increased area of vorticity expands to upper and sidewise combustor. However, the stagnation pressure loss which generates thrust loss becomes higher when the vorticity is higher. Considering these result, we can conclude that optimized design which considers the highest mixing performance and the least stagnation pressure loss is needed.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.114-120
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• 2006

The basic effects of hydrogen addition for engine performance and emission were investigated in single cylinder research engine. Seven commercial injectors were tested to choose a suitable injector for hydrogen injection prior to its engine implementation. The hydrogen fuel leakage and flow rate were evaluated for each injector and KN3-1(Keihin, CO.) showed the best performance for hydrogen fuel. At the higher excess air ratio(${\lambda}=1.7$, 2.0), the better combustion stability was found with hydrogen addition even though its effect was small at lower excess air ratio (${\lambda}=1.0$, 1.3). Stable operation of the engine was even guaranteed at ${\lambda}=2.0$, if the amount of hydrogen gas was near 15% of total energy. In the lean region, ${\lambda}>1.3$, thermal efficiency was improved slightly while it was not clearly observed at ${\lambda}=1.0$, 1.3. It is considered that, in some cases, high temperature environment due to hydrogen combustion caused further heat loss to surroundings. Except for ${\lambda}=1.0$, with larger amount of hydrogen addition, CO was reduced drastically but it was emitted more at the leaner region. Nitric oxides(NOx) was increased a little more with hydrogen addition at ${\lambda}=1.0$, 1.3. However, at ${\lambda}>1.3$ its relative amount of emission was low. In addition, the amount of NOx was continuously decreased with hydrogen addition, but, at ${\lambda}=2.0$ the amount of NOx was lowered to 1/100 of that of ${\lambda}=1.0$. THC emission was significantly increased as air/fuel ratio was raised to leaner region due to misfire and partial burn.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.286-291
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• 2016

This study was carried out to evaluate the feasibility of air-stripping by DIWS(Dip Injection Wet Scrubber) system on high concentration of ammonia wastewater more than 10,000 mg/L. In the case of changing temperature from $30^{\circ}C$ to $70^{\circ}C$ maintaining pH 12.5 within the 72 hours, the removal efficiency of T-N by the present treatment plant was increased to 90.5% which was initially kept 70.3%. Although the high concentration of T-N with 9,120~12,955 mg/L was treated by micro-bubble through DIWS system maintaining the temperature of $30^{\circ}C$ within the 20 hours, the removal efficiency of T-N reached 91.9%, which indicated the possibility of air-stripping.

• The Korean Journal of Pain
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• v.12 no.1
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• pp.43-47
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• 1999

Backgroud: Systemic administration of opioid can prolong the duration of epidural anesthesia. The authors examined the effect of nitrous oxide ($N_2O$) on the level of sensory block induced by epidural lidocaine. Methods: Twenty minutes after epidural injection of 2% lidocaine (below 70 years : 20 ml, 70 years and above : 15 ml), the level of sensory block was assessed (2nd stage). Patients were randomly assigned to receive either medical air (control group, n=15) or 50% $N_2O$ in oxygen ($N_2O$ group, n=15) for 10 minutes, the level of block was reassessed (3rd stage). Pateints were given room air (control group) or 100% oxygen for 5 minutes and room air for 5 minutes ($N_2O$ group), and the level of block was reassessed (4th stage). Results: At the 3rd stage, $N_2O$ group showed 4.3 cm cephalad increase in the level of sensory block (p=0.005), but control group revealed 1.43 cm regression. After discontinuation of gas, the level of block regressed in both group (p=0.000). At the 4th stage, $N_2O$ group revealed 3.5 cm cephalad increase (p=0.048) and control group 1.97 cm regression (p=0.001) as compared with the 2nd stage. Conclusions: The level of sensory block induced by epidural lidocaine was significantly increased cephalad by concommitant use of 50% $N_2O$ for 10 minutes.