• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.89-94
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• 1998

Seasonal variation of attenuation coefficient spectra in Japan sea was extracted from underwater radiance/irradiance spectra observed by a moored buoy system developed by National Space Development Agency of Japan (NASDA). The buoy was deployed 9 months from August 31, 1996 to June 1, 1997. Throughout this period, it was collecting downward irradiance and upward radiance spectra under water at the depth of 1.5m and 6.5m everyday. The dairy averaged diffused attenuation coefficient spectra and underwater reflectance spectra were calculated. The results were compared with the absorption spectra of filtered samples obtained by validation cruises, which carried out 5 times during the moored period. Also, the natural fluorescence of chlorophyll a were extracted from the upward radiance spectra observed at 1.5m depth. The seasonal variation of the calculated attenuation coefficient spectra and the natural fluorescence were examined. The result shows a weak blooming of phytoplankton on November and a large blooming on April.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.2
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• pp.121-127
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• 2008

This paper investigates the effects of outdoor pressure fluctuations on natural ventilation through an opening on a building envelope. The ventilation airflow rate depends on the magnitude and the period of the pressure fluctuations, the size of the opening relative to the space volume, and the resistance characteristics of the opening. Non-dimensional parameters have been derived, which determine indoor pressure responses due to outdoor pressure fluctuations. The flow regions are categorized into (1) synchronized region, (2) opening resistance region, and (3) transition region depending on the non-dimensional parameter derived. Pressure fluctuations and flow characteristics are investigated numerically using the 4th order Runge-Kutta method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.11
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• pp.2684-2693
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• 1993

The free vibration and dynamic response of cross-ply for CFRP and GFRP laminated circular cylindrical shells under dynamic loadings are investigated by using the first-order shear deformation shell theory. The modal analysis technique is used to develop the analytical solutions of simply supported cylindrical shells under dynamic load. The analysis is based on an expansion of the loads, displacements and rotations in a double Fourier series which satisfies the and boundary conditions of simply support. Analytical solution is assumed to be separable into a function of time and a function of position. In this paper, the considered load forces are step pulse, sine pulse, triangular(1, 2, 3) pulse and exponential pulse. The solution for a given loading pulse can be found by involving the convolution integral. The results show that the dynamic response are governed primarily by the natural period of the structure.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.2 s.140
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• pp.124-128
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• 2005

This paper describes motion stability of a spar platform with and without a damping plate in regular waves. The heave and pitch motion equation is derived in terms of Mathieu equation and the stability diagram is obtained. It is shown that the spar platform with damping plate has smaller unstable region than that without damping plate in the stability diagram. Model tests are carried out to verify the mathematical analysis. Under the condition that the pitch natural period is approximately double the heave natural period and the heave motion is amplified at heave resonance, unstable pitch motions are evoked. However the unstable motion is stabilized in cases of spar platform with damping plate. Therefore the damping plate is an effective device to stabilize the motion of spar platform.

• Korean Journal of Pharmacognosy
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• v.33 no.4 s.131
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• pp.376-383
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• 2002

The methanol extracts prepared from ten kinds of culinary herbs were investigated for the cytotoxcic effect againt L1210 cancer cells and the mode of action. The substantial cytotoxic effects were observed in all cases with the most prominent effect demonstrated by lemon verbena extract showing $87{\pm}4.1%$ cytotoxicity with $100{\mu}g/ml$ concentration and 3 days culture period. The cytotoxic effect was found to be dose and culture period dependent. With respect to the mechanism of the cytotoxicity, the augmented generation of $O_2{^-}ion$ and the dramatically escalated activities of antioxidant enzymes such as superoxide dismutase(SOD) and glutathione peroixdase (GPx) with addition of the herb methanol extractw suggested that there would be the involvement of reactive oxygen species (ROS) metabolism in the course of L1210 cancer cell death by the mothanol extract of the edible herbs.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.553-556
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• 2009

We surveyed natural enemies of Pachynematus itoi Okutani, newly recorded sawfly pest of Larix leptolepis, and investigated their occurrence and life cycle at Cheolwon and Taebaek, Gangwon Province in 2006~2007. Endasys liaoningensis was identified as main natural enemy of P. itoi Okutani. Parasitism of E. liaoningensiswas was 42%. Emergence period of E. liaoningensis was from May to September, and the peak of emergence was from 21th May to 20th June. It was suggested that the occurrence number and period of E. liaoningensis were quite closely relative to those of host, P. itoi.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.5
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• pp.316-322
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• 2005

In order to develop a floating breakwater, which can efficiently control long period waves, vertical plates are attached in pontoon. Wave control and dynamic behaviors of the newly developed vertical plates type are verified from numerical analysis and hydraulic experiment. As a result, for the wave control and energy dissipation, the newly developed vertical plates type is more efficient than the conventional pontoon type. For the floating body motion, the wave transmission, depending on incident wave period, is decreased at the natural frequency. Dimensionless drift distance has similar trend of the reflection rate of wave transformation near natural frequency except maximum and minimum values. Dimensionless maximum tension is 17 percent of the weight of floating breakwater in case of the conventional pontoon type and 18 percent or 14 percent in case of the newly developed vertical plates type. Thus, it is shown that the wave control is improved by the vertical plates type. In addition, by adjusting the interval of the front and back vertical plate, we would control proper wave control.

• Journal of Food Hygiene and Safety
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• v.12 no.1
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• pp.55-62
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• 1997

This study was carried out to investigate the microbiological and chemical properties of natural water during storage. The water samples were taken at the time of purchase and the opened bottles and unopened bottles stored at the temperature of 4$^{\circ}C$, 18$^{\circ}C$, and 3$0^{\circ}C$. The bacterial content normally rose to 2.06$\times$102 CFU/$m\ell$ for the unopened bottles and 2.91$\times$102 CFU/$m\ell$ for the opened bottles after 2 weeks of storage, and 1.21$\times$102 CFU/$m\ell$ and 2.64$\times$102, respectively, after 24 weeks of storage. The number of viable cells of bacteria peaked more rapidly at the storage temperature of 3$0^{\circ}C$ than 18$^{\circ}C$. But the total samples were found to be negative for coliforms test during the study period. The average range of pH value was from 7.39 to 7.76. The results showed that the nitrates and chlorides satisfied the Korea Drinking Water Quality Standards during the storage period of 24 weeks. However, the undesirable changes of the taste and odor were detected within 2 weeks and 3 weeks, respectively.

• Journal of Environmental Science International
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• v.20 no.11
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• pp.1457-1464
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• 2011

In this study, the method of estimating hydrologic information (water depth, submerged period etc.) on the proper selection of construction point and scale as well as vegetation type suggested for the design of natural riparian rehabilitation structure. Long-term comprehensive watershed model SWAT-K(Korea) was applied to this purpose. Flow duration analysis was conducted to analyze the hydrologic characteristics of Pyungchang watershed at which the 'bangtul' construction method was tested. For this purpose 20 years (1989-2008) rainfall runoff analysis was carried out. Based on the simulated daily streamflow data, flow duration curve was made to analyze the flow characteristics, and the water depth hydrograph was made to analyze the water depth distribution at the cross section. Finally, the information for the selection of proper vegetation according to the submerged period is suggested.

• Korean Journal of Pharmacognosy
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• v.28 no.4
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• pp.286-292
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• 1997

We studied the screening condition for immune regulatory responsor. We focused on the T-lymphocytes leer this purpose. Mouse fetal thymic organ culture (FTOC) system and flow cytometric analysis were mainly used in this experiment. Even if FTOC is carried out in vivo condition, the pattern of thymic development in the condition of FTOC is similar to that of in vivo condition. In this regard, FTOC system might be very powerful tool to screen the immune regulator, especially concerning on T cells. To establish the optimum condition of FTOC to screen the Immune regulator, we focused on the optimum amount of dose and culture period. The cell number and surface antigens on T cells were also analysed by using hemacytometer and flow cytometer. To monitor the differentiation event, anti-CD3, anti-CD4 and anti-CD8 antibodies were used. Alkoxyglycerol and Phellodendri Cortex were used fur positive and negative control, respectively. Astragalus membranceus was used as test sample. From our analysis, we reached to conclusions that the best dose of extract is $50\;{\mu}g/ml$ of culture medium, the best culture period is for 9 days, and ethanol used as solvent has no toxicity to FTOC.