• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2003.10a
• /
• pp.70-75
• /
• 2003

Model tests using 2.0m model of the series 60 form ($C_{b}$ = 0.6) were carried out in the Circulating Water Channel(CWC) in the Chosun University(CU, Korea) for the purpose of a correlative study with Towing Tank(TT). Resistance, propeller open water, self propulsion, and wake survey tests were carried out and the results were extrapolated to the ship scale. These results were compared with the extrapolated ship values based on the model test of 7.0m model in the TT at the Korea Research Institute of Ships and Ocean Engineering (KRISO, Korea). The CWC test results were correlated with the results of the towing tank tests.

• Korean Journal of Ecology and Environment
• /
• v.46 no.3
• /
• pp.332-342
• /
• 2013

We collected zooplankton from May to October, 2011, with the aim of understanding the zooplankton community distribution and food web interaction between the open water and littoral (aquatic plants) zones in two small reservoirs with different land covers (Sobudang, Myeongdong). Small-sized reservoirs are more abundant in South Korea, and a total of 51 and 65 species of zooplankton were identified at the two small reservoir (Sobudang and Myeongdong), where zooplankton densities were more abundant in the littoral zone than in the open water zone. Cladocerans and copepods densities were also higher in the littoral zone, in contrast, rotifers showed higher densities in the open water zone (t-test, P/0.05). Epiphytic zooplankton dominated at the littoral zone (Lecane, Monostyla, Alona and Chydorus) because aquatic plants provided refuge spaces for attachment. Some rotifers (e.g. Brachionus, Keratella and Polyarthra) were more abundant in the open water zone because of their small size, which might help them to go unnoticed by predators. In two-way ANOVA, rotifers related to two reservoirs or habitat space (littoral zone and open water zone), but cladocerans and copepods showed a statistically significant relationship on only two reservoirs. The results of stable isotope analysis showed that zooplankton in the littoral zone tended to depend on organic matter attached to aquatic plants as a food source, which indicates the avoidance of competition of zooplankton with other macro-invertebrates (e.g. Damselfly larva, Cybister brevis and Neocardina denticulate). As a result, zooplankton community distribution is determined by not only habitat space (aquatic plant zone and open water zone) but also by food source (phytoplankton).

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.6 no.2
• /
• pp.187-205
• /
• 2014

The global price of oil, which is both finite and limited in quantity, has been rising steadily because of the increasing requirements for energy in both developing and developed countries. Furthermore, regulations have been strengthened across all industries to address global warming. Many studies of hull resistance, propulsion and operation of ships have been performed to reduce fuel consumption and emissions. This study examined the design parameters of the propeller boss cap fin (PBCF) and hub cap for 6,000TEU container ships to improve the propulsion efficiency. The design parameters of PBCF have been selected based on the geometrical shape. Computational fluid dynamics (CFD) analysis with a propeller open water (POW) test was performed to check the validity of CFD analysis. The design of experiment (DOE) case was selected as a full factorial design, and the experiment was analyzed by POW and CFD analysis. Analysis of variance (ANOVA) was performed to determine the correlation among design parameters. Four design alternatives of PBCF were selected from the DOE. The shape of a propeller hub cap was selected as a divergent shape, and the divergent angle was determined by the DOE. Four design alternatives of PBCF were attached to the divergent hub cap, and the POW was estimated by CFD. As a result, the divergent hub cap with PBCF has a negative effect on the POW, which is induced by an increase in torque coefficient. A POW test and cavitation test were performed with a divergent hub cap with PBCF to verify the CFD result. The POW test result showed that the open water efficiency was increased approximately 2% with a divergent hub cap compared to a normal cap. The POW test result was similar to the CFD result, and the divergent hub cap with the PBCF models showed lower open water efficiency. This was attributed to an increase in the torque coefficient just like the CFD results. A cavitation test was performed using the 2 models selected. The test result showed that the hub vortex is increased downstream of the propeller.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.4 no.1
• /
• pp.131-138
• /
• 2000

In this study, physical and engineering properties of ordinary portland cement and microcement were investigated to verify reinforcing effect of underpinning of open caisson foundation by using microcement grouting. Laboratory injection tests such as infiltration and injection in case of seepage for the stream bed soil at ${\bigcirc}{\bigcirc}$ Great Bridge in Seoul were carried out. Field injection tests to reinforce open caisson foundation at ${\bigcirc}{\bigcirc}$ Great Bridge were performed and the ability of application by microcement grouting was evaluated. From the test results, physical and engineering properties of microcement are better than those of ordinary portland cement. Also, the ability of infiltration and solidity in case of seepage is better than that of ordinary portland cement. Therefore, it is concluded that microcement is an excellent material to reinforce open caisson foundation of the existing bridge structure under the water and can be used as underpinning material of general foundations.

• The Korea Journal of Herbology
• /
• v.30 no.3
• /
• pp.13-17
• /
• 2015

Objectives : Taraxacum platycarpum H. Dahlstedt has been reported to have several biological properties such as skin hydration and antiinflammation. The purpose of this study was to examine the antidepressive effects of water extract of T. platycarpum (WTP) on an animal model of depression. Methods : In the present study, normal ICR mice (4 weeks) were used, and orally administered with WTP (25, 50 and 100 mg/kg). Depression-like behavior was monitored the forced swimming test (FST) and tail suspension test (TST) in mice. The locomotor activity was evaluated to eliminate the false-positive activity in the open field test (OFT). Fluoxetine, the selective serotonin reuptake inhibitor, as a positive control was intraperitoneally administered at a dose of 15 mg/kg at 30 min before starting the behavioral test. Moreover, we evaluated the effects of WTP on the expression of brain-derived neurotrophic factor (BDNF) and the extracellular signal-regulated kinase (ERK)/ cyclic AMP response-element binding protein (CREB) signaling pathway in the hippocampus using Western blot. Results : The administration of WTP (50 and 100 mg/kg) significantly (P < 0.05, respectively) reduced the immobility time during FST and TST without accompanying changes in locomotor activity by OFT. Furthermore, WTP at dose of 100 mg/kg increased the BDNF expression and the phosphorylation of ERK and CREB in the hippocampus region. Conclusions : These results suggest that WTP has a useful anti-depressant effect through the regulation of BDNF/ERK/CREB signaling pathway.

• The KSFM Journal of Fluid Machinery
• /
• v.18 no.6
• /
• pp.57-62
• /
• 2015

The test of comparing liquid flow calibration system (approved by KOLAS) for accuracy and structure change test was performed in the test bed in order to evaluate the typical characteristics of the electromagnetic flow meters and parshall flume that are generally used in the water discharging facilities. The results of the accuracy comparing test with liquid flow calibration system showed the error of less than 2%. Pharshall plume got error up to -8.3% (low flow) from the flow rate test, but less than 4% from the accumulated flow test because of offset error at high flow rate and low flow rate. Evaluation of structual change test was tested with only parshall flume using structure and it consisted of installation angle (parshall flume and level sensor) and position change. Installation angle, water level sensor angle and position changing test for parshall flume had errors of 3.1%~-9.2%, 0.4%~-5.6% and 0.2%~1.3% respectively. Especially, the error showed the largest increase when the water level sensor measured the point of decreased flow by the structure change. Therefore, error factors (change of straight pipe length, installation of obstacle or effect of foreign substances on water level sensor) that can often occur in the field should be derived and the research for optimized installation method should be carried out continuously.

• Korean Journal of Environmental Agriculture
• /
• v.24 no.1
• /
• pp.6-11
• /
• 2005

A prototype surface flow constructed wetland was built in the upstream area of reclaimed tidal lands to improve the water quality of Lake Sihwa by treating severely polluted stream water. In this study, a tracer test using rhodamine-WT was performed to investigate the flow characteristics and to quantify the observed hydraulic residence time (HRT) for a high-lying cell in the Banwol wetland of the Sihwa constructed wetland. The tracer test indicated that even if flow was mainly observed in the open water area of the Banwol wetland, water flowed continuously in the vegetative area and there was no dead zone. The calculated HRT (51.3 hrs), calculated by dividing the wetland volume by the wetland inflow, exceeded the observed HRT (38.7 hrs), since the short-circuiting of flux resulting from irregular topography and vegetation was not reflected in the calculated HRT. The exit tracer concentration curves were reproduced well by both the plug flow with dispersion and tanks-in-series models, indicating that the performance of the Banwol wetland can be estimated accurately using these models.

• Journal of Oriental Neuropsychiatry
• /
• v.15 no.1
• /
• pp.43-64
• /
• 2004

The aim of this study was to evaluate the effects of Jowiseungcheongtang compared with St. John's wort in the chronic mild stress(CMS) animal model of depression. Wistar rats were used for this study. The subjects were divided into 4 groups (Naive group: without CMS procedure, CMS-vehicle: water was administered during CMS procedure, CMS-Jowiseungcheongtang: Jowiseungcheongtang was administered after 5 weeks of CMS procedure, CMS-St. John's wort: St. John's wort was administered after 5 weeks of CMS procedure) During 9 weeks of CMS procedure, The change of the consumption of sucrose and the changes of weights were measured. After CMS procedure, Morris water maze test, open field test, elevated plus maze test and Western blotting were measured. The results were as follows. 1. The consumption of sucrose solution was significantly reversed in Jowiseungcheongtang group and relatively reversed in St. John's Wort group at 7 week. 2. In open field test, Neither Jowiseungcheongtang nor St. John's wort group showed statistically significant change of exploratory activity. In EPM test, St. John's Wort group showed significant decrease of total arm entry in comparison with Naive group. And Jowiseungcheongtang group was showed no significant change. 3. In Morris water maze test, St. John's Wort group showed significant increase in escape latency of the last Morris water maze trial. And in water maze probe test, there was no significant change. 4. St. John's Wort group showed relative increase in LP1 division of 5HT1A receptor compared with Naive group. Both St. John's Wort and Jowiseungcheongtang group showed relative increase in P2 division of GluRl compared with Naive group. These results suggest that Jowiseungcheongtang is as effective as St. John's Wort in the treatment of depression.

• Journal of Oriental Neuropsychiatry
• /
• v.15 no.2
• /
• pp.53-70
• /
• 2004

Objective : This study was designed to assess the protective effects of Bambusae caulis and St. John's Wort on the animal model of depression, induced by chronic mild stress(CMS) Method : Male Wistar rats were used for this experiment. The subjects were divided into 4 groups ( 1. CMS-drugs: Bambusae caulis administered during CMS treatment, 2. CMS-drugs: St. John's Wort administered during CMS treatment, 3. CMS-vehicle: Water administered during CMS treatment, 4. normal control group without CMS treatment ). After 3 weeks of CMS treatment, they were executed open field test and weight, sucrose intake were measured. Result : 1. CMS Bambusae caulis group showed significant difference of locomotor activities and marginal difference of start latency in comparison with other groups in open field test. 2. There was no change of weights between CMS Bambusae caulis, St. John's Wort groups and CMS control group. 3. CMS St. John's Wort group showed upper level of sucrose intake than CMS Bambusae caulis group and CMS control group. Conclusion : These results suggest that Bambusae caulis may have protective antidepressant effects in CMS model rats. And these effects could be explained by the elevated locomotor activities in open field test.

• Journal of the Society of Naval Architects of Korea
• /
• v.43 no.4 s.148
• /
• pp.440-450
• /
• 2006

In this paper, we suggest a design concept of defining the propeller geometry by stacking up the blade sections aligned with propeller surface streamlines. Numerical and experimental propeller open water(P.O.W.) characteristics of a newly designed propeller are presented. The surface streamlines for a propeller are obtained by using the panel method. Redefinition of the blade sections aligned with the streamlines is provided together with 8-spline modeling, by which we manufacture model propellers. We carried out the P.O.W, tests in a towing tank in order to show the effect of the present method on P.O.W. characteristics.