• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.8
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• pp.645-651
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• 2015

The objective of this study is to experimentally investigate the effect of design parameter on the mass ratio of a central-driven ejector. The design parameters are the primary nozzle area and distance ratios, diffuser exit-area ratio and mixing-tube length ratio. The experimental setup was an open-loop continuous circulation system which has a movable nozzle ejector, an electric motor-pump, a water tank, a control panel and high-speed camera unit. We calculated the mass ratio using the measured primary and suction-flow rates with the experimental parameter of primary water-flow rate or pressure. The results showed that the mass ratio increased with the primary nozzle distance ratio and mixing tube length ratio, while the mass ratio decreased with the primary nozzle-area ratio and diffuser exit-area ratio.

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.590-598
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• 2006

In-situ Air sparging (IAS) is a groundwater remediation technique, in which organic contaminants volatilize into air form the saturated to vadose zone. This study was carried out to evaluate the effect of sludge and soil microbial community structure on air sparging of Total Petroleum Hydrocarbons (TPH) contaminated groundwater soils. In the laboratory, diesel (10,000 mg TPH/kg) contaminated saturated soil. The Air was injected in intermittent (Q=1500 mL/min, 10 minute injection and 10 minute idle) modes. For Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis of eubacterial communities in sludge of wastewater treatment plants and soil of experiment site, the 16S rDNA was amplified by Polymerase Chain Reaction (PCR) from the sludge and the soil. The obtained 16S rDNA fragments were digested with Msp I and separated by electrophoresis gel. We found various sequence types for experiment with sludge soil samples that were closely related to Agrococcus, Flavobacterium, Thermoanaerobacter, Flexibacter and Shewanella, etc, in the clone library. The results of the present study suggests that T-RFLP method may be applied as a useful tool for the monitoring in the TPH contaminated soil the fate of microorganisms in natural microbial community.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.800-806
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• 2016

The maneuverability of a tugboat is affected by the slewing motion of a barge while the tug is navigating with the barge in water. Therefore, it is necessary to reduce the slewing motion of the barge to allow for safe towing work. In this study, a water tank experiment was performed to examine the factors affecting the slewing motion of a barge and improve course stability. The characteristics of slewing motion vary according to bow shape. Three barge models, each with a different bow shape, were selected as experimental subjects. A comprehensive analysis was performed to study the effects of various factors on the slewing motion of a barge such as the presence of a skeg and bridle, towing speed, and the length of the towline. The effect of the location of the skeg varied according to bow-hull form. The slewing motion of the barge decreased as the length of the towline increased, and this decrease was even greater when a bridle was connected to the towline. In addition, the slewing motion decreased significantly as the length of the bridle increased. The slewing angles did not show significant change with respect to towing speed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.4
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• pp.320-327
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• 2006

Numerical analysis and experimental study are performed to investigate the effect of heat load and operating temperature on the thermal performance of several variable conductance heat pipe (VCHP) with screen meshed wick. The heat pipe is designed in 200 screen meshes, 500 mm length and 12.7 mm outer diameter tube of copper, water (4.8 g) is used as working fluid and nitrogen as non-condensible gas (NCG). Heat pipe used in this study has evaporator, condenser and adiabatic section, respectively. Analysis values and experimental data of wall temperature distribution along axial length are presented for heat transport capacity, condenser cooling water temperature change, degrees of an inclination angle and operating temperature. These analysis and experiment give the follow findings: For the same charging mass of working fluid, the operating temperature of heat pipe becomes to be high with the increasing of charging mass of NCG. When the heat flux at the evaporator section increases, the vapor pressure in the pipe rises and consequently compresses the NCG to the condenser end part and increases the active length of the condenser. From previous process, it is found out we can control the operating temperature effectively and also the analysis and experimental results are relatively coincided well.

• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.330-339
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• 2008

Effect of additives such as NP series nonionic surfactant and cosurfactant on AgCl nanoparticles was investigated where nanoparticles were prepared using two different types of water-in-oil (W/O) microemulsions containing silver nitrate and sodium chloride, respectively. Phase behavior experiments showed that the region of one phase W/O microemulsion was found to be broadened with an increase in the ethylene oxide length of a nonionic surfactant mainly due to an increase in hydrophilic nature of a surfactant. Photomicrographs obtained by transmission electron microscopy indicated that an increase in ethylene oxide length of a nonionic surfactant results in both increases in particle size and size distribution. Phase behavior experiments for the systems containing AOT surfactant, isooctane and aqueous solution of an inorganic salt showed that addition of a cosurfactant caused a shrinkage in phase region of one phase W/O microemulsion, especially water contents contained in W/O microemulsion with an increase in the chain length or the concentration of a cosurfactant used. Photomicrographs obtained by transmission electron microscopy indicated that characteristics of AgCl nanoparticles produced were dependent both on the radius of spontaneous curvature and film rigidity of a microemulsion.

• International Journal of Fluid Machinery and Systems
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• v.5 no.3
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• pp.109-116
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• 2012

Water hammer pumps can effectively use the water hammer phenomenon for water pumping. They are capable of providing an effective fluid transport method in regions without a well-developed social infrastructure. The results of experiments examining the effect of the geometric form of water hammer pumps by considering their major dimensions have been reported. However, these conventional studies have not fully evaluated pump performance in terms of pump head and flow rate, common measures of pump performance. The authors have focused on the effects on the pump performance of various geometric form factors in water hammer pumps. The previous study examined how the hydrodynamic characteristics was affected by the inner diameter ratio of the drive and lift pipes and the angle of the drive pipe, basic form factors of water hammer pumps. The previous papers also showed that the behavior of water hammer pump operation could be divided into four characteristic phases. The behavior of temporal changes in valve chamber and air chamber pressures according to the air volume in the air chamber located downstream of the lift valve was also clarified in connection with changes in water hammer pump performance. In addition, the effects on water hammer pump performance of the length of the spring attached to the drain valve and the drain pipe angle, form factors around the drain valve, were examined experimentally. This study focuses on the form of the lift valve, a major component of water hammer pumps, and examines the effects of the size of the lift valve opening area on water hammer pump performance. It also clarifies the behavior of flow in the valve chamber during water hammer pump operation.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.377-383
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• 1997

Studies were conducted on the nature of allelopathic effect of the substances in the waste of ginkgo leaves from pharmaceutic factory. In the first step, to find out whether there was any allelophatic effect, young seedlings of radish and rice were grown in the water (crude) extract of ginkgo leaf waste and in different liquid/lquid partitioned fractions of EtOAc at pH 9, EtOAc at pH 3, and BuOH. As second step, attempts were made to isolate and identify the allelophatic substance in different liquid/liquid partitioned fractions using GC/MS and NMR techniques. The water (crude) extract of ginkgo leaf waste retarded the growth of radish seedlings under 10% concentration. In case of rice seedlings, the water extract of ginkgo leaf extract showed adverse effect on the growth when combined with $3.3{\times}10^{-6}M$ gibberellin A3. All of the liquid/liquid fractions of crude extract showed strong retardation of seedling growth of radish and rice at the concentration of 1%. Allelophatic substance was isolated from the crude extract using liquid/liquid partition, column chromatography and HPLC techniques. The analytical results of isolated componet using GC/MS and NMR proved that the allelophatic substance in the ginkgo leaf wastes is catechol; one of phenol compounds. Based on the experiences current study, a practical method for the testing of allelophatic effect of crude extract of some materials was proposed. In this method, rice seeds were allowed to sprout until the length of coleoptile to reach 0.5 mm. Such seedlings were submerged in the solution containing supposedly allelophatic substance and the length of shoot and root was measured 3 days after treatment.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.2
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• pp.151-160
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• 2017

Growing demand and rapid development of the synthetic fiber rope in mooring system have taken place since it has been used in deep water platform lately. Unlike a chain mooring, synthetic fiber rope composed of lightweight materials such as Polyester(polyethylene terephthalate), HMPE(high modulus polyethylene) and Aramid(aromatic polyamide). Non-linear stiffness and another failure mode are distinct characteristics of synthetic fiber rope when compared to mooring chain. When these ropes are exposed to environmental load for a long time, the length of rope will be increased permanently. This is called 'the creep phenomenon'. Due to the phenomenon, The initial characteristics of mooring systems would be changed because the length and stiffness of the rope have been changed as time goes on. The changed characteristics of fiber rope cause different mooring tension and vessel offset compared to the initial design condition. Commercial mooring analysis software that widely used in industries is unable to take into account this phenomenon automatically. Even though the American Petroleum Institute (API) or other classification rules present some standard or criteria with respect to length and stiffness of a mooring line, simulation guide considers the mechanical properties that is not mentioned in such rules. In this paper, the effect of creep phenomenon in the fiber rope mooring system under specific environment condition is investigated. Desiged mooring system for a Mobile Offshore Drilling Unit(MODU) with HMPE rope which has the highest creep is analyzed in a time domain in order to investigate the effects creep phenomenon to vessel offset and mooring tension. We have developed a new procedure to an analysis of mooring system reflecting the creep phenomenon and it is validated through a time domain simulation using non-linear mooring analysis software, OrcaFlex. The result shows that the creep phenomenon should be considered in analysis procedure because it affects the length and stiffness of synthetic fiber rope in case of high water temperature and permanent mooring system.

• The Korean Journal of Malacology
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• v.31 no.4
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• pp.263-266
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• 2015

This study was performed to determine the effect of water temperature condition on survival rate and growth of juvenile geoduck (Panopea japonica). Panopea japonica juveniles were bred for 6 weeks at 12, 15, 18, 21, 24 and $27^{\circ}C$ on incubator. Juveniles median lethal times (LT50) were 29 hours in $27^{\circ}C$, 14.5 day in $24^{\circ}C$, 37.4 day in $21^{\circ}C$. Survival rate of water temperature 12, 15 and $18^{\circ}C$ showed a high survival rate in 95.0%, 95.0% and 93.3% at 6 weeks. As a result of culturing for 6 weeks at 12, 15, 18, 21 and $24^{\circ}C$, a daily growth of shell length and total weight was 0.10 mm, 0.12 mm, 0.13 mm, 0.16 mm and 0.14 mm, and 2.21 mg, 2.65 mg, 2.84 mg, 3.13 mg and 2.93 mg. Juvenile shell length and total weight have significantly increased at $15-21^{\circ}C$. However, mortality rate has significantly increased at more than $21^{\circ}C$. As a result, appropriate water temperature for juveniles culturing considered $15-18^{\circ}C$.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.144-150
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• 2015

Silicate fertilizers known to be effective in improving the growth and density of zoysiagrass. Most silicate fertilizers being used in Korea are slag-originated silicate fertilizer, but some water soluble silicate fertilizers are commercially available recently. This study was conducted to know the effect of water soluble silicate fertilizer, on the growth of zoysiagrass and the change of soil chemical properties in Wagner pot and field experiment. Root length, fresh and dry weight of shoots and stolons, the number of shoots and stolons, total of stolons length and the $SiO_2$ content of internal plant were significantly increased by the $SiO_2$ content but chemical properties of the soil were not significantly changed by the $SiO_2$ content. The $SiO_2$ contents of 18 and $36{\mu}lml^{-1}$ did not show significance difference, and therefore a reasonable application the content of $SiO_2$ was thought to be $18{\mu}lml^{-1}$. Foliar spray of water soluble silicate fertilizer is believed to enhance the growth and density of zoysiagrass than soil application.