• Horticultural Science & Technology
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• v.30 no.2
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• pp.152-157
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• 2012

We investigated the effect of 1-methylcyclopropene (1-MCP) on ethylene production induced by simulated transport stress in $Begonia$ ${\times}$ $hiemalis$ 'Blitz' and 'Carnival' to improve the display life in potted plants. The simulated transportation conditions were imposed for 4 days in simulated export containers with darkness, vibration with continuous shaking ($150{\pm}20$ rpm) on a rotary lab shaker, and low temperature ($12^{\circ}C$). Plants were treated with 1-MCP at three concentrations (5, 25, or 125 $nL{\cdot}L^{-1}$) and for three different periods (0, 6, or 12 hours) before undergoing the simulated transport stress treatments. Treatment with 25 or 125 $nL{\cdot}L^{-1}$ 1-MCP inhibited the abscission of open flowers by more than 40% as compared to the untreated plants. One week after the treatments, the ethylene production decreased in the plants treated with 125 $nL{\cdot}L^{-1}$ 1-MCP for 'Blitz' and 25 $nL{\cdot}L^{-1}$ for 'Carnival'. Ethylene production was correlated with concentration and duration of 1-MCP treatment in 'Blitz', but not in 'Carnival'. To reduce flower abscission and ethylene production, thus improve the display life when plants are exposed to transportation stress, we recommend pre-treatment with 1-MCP before packaging, using concentrations and durations specific to each cultivar, 125 $nL{\cdot}L^{-1}$ for 6 h and 25 $nL{\cdot}L^{-1}$ for 12 hours for 'Blitz' and 'Carnival', respectively.

• Journal of Aerospace System Engineering
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• v.13 no.4
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• pp.66-73
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• 2019

The objective of this study was to evaluate the structural safety of the basic design for the linear actuator for the flap control of aircrafts. The kinetic behavior of the linear actuator was determined using the multi-body dynamics (MBD) analysis, and the contact force was calculated to be used as input data for the structural analysis based on the finite element analysis. In the structural analysis, the thermal and static behaviors of the linear actuator satisfying the designed velocity were examined, and the structural safety of the linear actuator evaluated. Moreover, the dynamic behaviors of the key components of the linear actuator were investigated by the modal analysis. The actuation rod linearly moved with about 5 mm/s when the motor operated at 225 rpm and the maximum contact force of 32.83 N occurred between two driving gears. Meanwhile, the structural analysis revealed that the maximum thermal and static stresses were 1.57% and 78% of the yield strength of steel, respectively, and they were in a safe range of the structure. In addition, the linear actuator for the basic design is stable to the resonance by avoiding the natural frequencies of the components.

• Food Engineering Progress
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• v.23 no.2
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• pp.118-124
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• 2019

This study aims to investigate the physical properties of extruded psyllium husk upon the addition of emulsifiers. Three different emulsifiers-glycerol monostearate (GMS), polyglycerol ester (PGE), and sugar ester (SE)-were added to the mixture of psyllium husk and rice powder before extrusion. Extrusion was performed using a twin-screw extruder at 140℃ die temperature, 200 rpm screw speed, and 16% feed moisture content. The physical properties of psyllium husk extrudates including expansion ratio, specific length, piece density, texture profile, color properties, water soluble index, and water absorption index were evaluated. It was observed that the expansion ratio was the highest while the specific length and piece density were the lowest in the control which had no emulsifiers. Texture profile analysis showed that the apparent elastic modulus and breaking strength were highest in the extrudate with a PGE of 0.1%. The adhesiveness was found to be lowest in the extrudates with an SE of 0.1% and GMS of 0.5%. Lightness value was highest in the extrudate with a PGE of 0.1%. Color difference, water soluble index, and water absorption index were highest in the control. The results reveal that some physical properties of extruded psyllium husk were improved with the addition of emulsifiers. This finding provides useful information for the development of psyllium snacks with good physical characteristics.

• Journal of Environmental Health Sciences
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• v.31 no.2 s.83
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• pp.160-164
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• 2005

This study was performed to evaluate the effects of washing food wastes before aerobic composting on temperature, pH and salinity, and the effects of washing after composting on salinity of sample mixtures. Weight ratios of food wastes to water in washing were 1:0(Control), 1:1(W-1), 1:2(W-2), 1:3(W-3) and 1:0(N-4), respectively. Ratios of food wastes to wood chips in reactor of Control, W-1, W-2, W-3 and N-1 were $5\;kg:0\iota,\;5\;kg:5\iota,\;5\;kg:5\iota,\;5\;kg:5\iota\;and\;5\;kg:5\iota$, respectively. Reactors were operated for 24 days with 1 hour stirring by 1 rpm and 2 hours of forced aeration per day. The increase in the ratio of water to food wastes resulted in the increase of the maximum reaction temperature and the shortening of the high temperature reaction period. The increase in the ratio of water to food wastes also resulted in faster reaching to the lowest pH and then to the steady state of pH 9.0. The final salinities of Control, N-1, W-1, W-2 and W-3 were $1.04\%,\;0.92\%,\;0.78\%,\;0.64\%\;and\;0.53\%$, respectively. The salinities of the N-l samples which were washed by the weight ratios (water:N-l) of 1:1, 2:1 and 3:1 after composting were $0.72\%,\;0.61\%\;and\;0.51\%$, respectively. Therefore, washing food wastes before aerobic composting is more efficient method than that after aerobic composting.

• KSBB Journal
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• v.15 no.1
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• pp.27-34
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• 2000

A marine bacterium having a high oil-degrading activity was isolated form the oil-polluted southern sea of Korea, and was identified as Pseudomonas aeruginosa and was named Pseudomonas aeruginosa BYK-2. The optimal tmeperatur, culture time, pH and NaCl concentration for biosurfactant production and cell growth showed $25^{\circ}C$, 48h, 7.0 and 0%(w/v), respectively. After cultivation at $25^{\circ}C$, 180 rpm in 250 mL erlenmeyer flask for 7days, 1%(w/v) arabian light crude oil and bunker C oil which are considered to be hardly degradable compounds were degraded 92.1%(w/w) and 76%(w/w) respectively. And then, cell adherence was measured on various carbon sources. The cell adherence indicated over 80% on hydrocarbons(arabian light crude oil, kuwait curde oil, bunker C oil, n-paraffine, n-hexadecane, n-tetradecane) as carbon sources. Lecithin among fatty acids(oleic acid, olive oil, lecithin) showed highest cell adherence of 91.5%. The cell adherence of sugars(arabinose, trehalose, dextrose, galactose, lactose, fructose, maltose, sorbitol, sucrose) observed to be less than 70% except for arabinose, galactose, sorbitol and sucrose.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.3
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• pp.245-250
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• 2006

The effects of aliphatic hydrocarbons (n-hexadecane and n-dodecane) on the volumetric oxygen mass transfer coefficient $(k_L\;a)$ were studied in flat alveolar airlift reactor and continuous stirred tank reactors (CSTRs). In the flat alveolar airlift reactor, high aeration rates (>2vvm) were required in order to obtain efficient organic-aqueous phase dispersion and reliable $k_La$ measurements. Addition of 1% (v/v) n-hexadecane or n-dodecane increased the $k_La$ 1.55- and 1.33-fold, respectively, compared to the control (superficial velocity: $25.8{\times}10^{-3}m/s$, sparger orifice diameter: 0.5 mm). Analysis of the gas-liquid interfacial area a and the liquid film mass transfer coefficient $k_L$ suggests that the observed $k_La$ increase was a function of the media's liquid film mass transfer. Addition of 1% (v/v) n-hexadecane or n-dodecane to analogous setups using CSTRs led to a $k_La$ increase by a factor of 1.68 and 1.36, respectively (superficial velocity: $2.1{\times}10^{-3}m/s$, stirring rate: 250 rpm). These results propose that low-concentration addition of oxygen-vectors to aerobic microbial cultures has additional benefit relative to incubation in purely aqueous media.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.499-506
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• 2010

Recently, a great deal of attention have been directed to the use of alternative fuels as a means to reduce vehicular emissions. As one of the promising alternative fuels, bio-diesel has advantages of a wide adaptability without retrofit of diesel engine. It is also effective enough to reduce CO, THC, $SO_x$, polycyclic aromatic hydrocarbons (PAHs) and PM. In this study, we investigated the emission characteristics of biofuels between different operating conditions, i.e., engine speed (1,400 rpm and 2,300 rpm), engine load (10% and 100%), bio-diesel blending (BD0, BD5 and BD20), and recirculation (EGR) rate of exhaust gas (0% and 20%). Relative performance of the system was evaluated mainly for the greenhouse gases ($CH_4$, $N_2O$ and $CO_2$). In addition, emission characteristics of ND-13 mode were also tested against both greenhouse gases and other airborne pollutants under emission regulation. The relative composition of bio-diesel has shown fairly clear effects on the emission quantities of CO, THC, and PM emission, although it was not on $NO_x$ and greenhouse gases. EGR rate has shown trade-off characteristics between $NO_x$ and PM.

• Tribology and Lubricants
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• v.21 no.2
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• pp.53-62
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• 2005

In this study a general Galerkin FE lubrication analysis method was utilized to analyze the complex lubrication performance of a spiral groove seal having an additional inner circular groove, which was designed for a chemical process mixer operating at a low speed of the maximum 500 rpm. Equilibrium seal clearance analyses under varying outer pressure revealed that the seal maintains a certain levitation seal clearance under the outer pressure of more than about 1.5 bar, regardless of a rotating speed. Also, under the normal outer pressure of 11 bar, the axial stiffness of the seal was predicted to have a high value of more than 7.0 e + 07 N/m, regardless of a rotating speed and thereby, the seal is expected to maintain a stable thickness of lubrication film under a certain external excitation acting. A seal levitation test rig was designed and constructed. Experimental results at 500 rpm agreed well with analytical predictions and the applied lubrication analysis method was verified.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.142-150
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• 2005

Design and performance evaluation of a spindle system which was composed of a grinding spindle and a regulating spindle for the centerless grinding of ferrule were performed in this paper. Layout and details of spindle system were designed and hydrostatic bearings for spindles were also designed. Prototype of spindle system was developed and its availabilities to machine the ferrule were discussed using the experimental results on the spindle stiffness of each spindle, loop stiffness, rotational accuracy and thermal characteristics. Loop stiffness of the spindle system was $130\;N/{\mu}m$, which was enough to machine the ferrule. Rotational accuracies of each spindle were about $0.2{\mu}m$ at the primary speed of 2,300 rpm(grinding spindle) and 300 rpm(regulating spindle). Temperature rises at the same speed were about $4.4\~4.7^{\circ}C$ in the case of grinding spindle and $1.8^{\circ}C$ in the case of regulating spindle, which agreed well with the designed value. From these results, it was estimated that the prototype of spindle system had enough performances for the centerless grinding machine to machine the ferrule.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.195-200
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• 2012

In this study, parameters and requirements of an 120kW class monorail planetary gearbox was analysed and the adaptive planetary gearbox design was selected. The specification of the sun gear, planetary gear and carrier was set and the profile & lead was optimized. The mechanical efficiency of the optimized one and the original one was observed. Dynamo-tester system was used to observe the mechanical efficiency of the planetary gearbox. A dynamo unit was connected with the planetary gearbox which straightened through the motor by a coupling. The standard tooth shape planetary gearbox and modified tooth shape planetary gearbox were used as test pieces and the rotation speed was set from 600 to 6000rpm with 600rpm, 2.5min one step. In order to check the mechanical efficiency of the planetary gearbox, the tests were done as follows. 1) The power loss between driving motor and dynamo tester. 2) Temperature variation by different rotation speeds. 3) Noise variation by different rotation speeds.