• Journal of Plant Biotechnology
• /
• v.6 no.4
• /
• pp.213-219
• /
• 2004

Zygotic embryos were excised from immature and mature seeds of the Himalayan yew, Taxus wallichiana. The embryos germinated precociously when kept in darkness for 5 weeks and developed into full seedlings within 10-12 weeks. The highest rate of embryo germination ($81\%$) was obtained in modified Lloyd & McCown' s woody plant medium containing macro and micronutrients at half strength supplemented with $1\%$ activated charcoal, which supported both the best embryonic growth ($43\%$) and seedling development ($32\%$). However, the supplementation of basal media with kinetin, thidiazuron, 6-benzyl aminopurine or $GA_3$ had no effect on the germination of the embryos. The embryos derived from immature seeds germinated but the frequency of embryonic growth was better in mature seeds. Stratification of seeds effected precocious germination of embryos. Seeds kept at $4^{\circ}C$ for 1 week germinated earlier and at a higher frequency irrespective of the stage of seed maturity, while the germination rate declined with prolonged cold treatment for 1 month at that same temperature. Analysis of taxanes in germinating seedlings revealed that root tissues contained high levels of taxol, 10-deacetyl-baccatin ill and baccatin ill as compared to shoots. Thus embryo culture technique appears to overcome the lengthy dormancy requirement of T. wallichiana seeds.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.29 no.2 s.233
• /
• pp.180-188
• /
• 2005

It is well known that a lean burn engine caused by stratified mixture formation has many kinds of advantages to combustion characteristics, such as higher thermal efficiency and lower CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can achieve low fuel consumption technology, it produces much unburned hydrocarbon and soot because of heterogeneous equivalence ratio in the combustion chamber. Therefore, the stratified mixture formation technology is very important to obtain the stable lean combustion. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The local effect of mixture formation according to control air-fuel distribution in the chamber was examined experimentally. In addition, the effect of turbulence on stratified charge combustion process was observed by schlieren photography. From this study, we found that the flame propagation speed increase with swirl flow and the swirl promotes the formation of fuel and air mixture.

• 한국해양학회지
• /
• v.12 no.1
• /
• pp.13-32
• /
• 1977

In order to determine the distributional ecology, and to investigate factors influencing these features, the diatom communities in plankton at depths of one, twenty-five, fifty, and seventy five meters in the area were studied and measured over a fifteen month of period. Measurements of environmental factors including temperature and salinity and algal nutrients such as phosphate, silicate, nitrate, and ammonia were also made at the same depths and locations. The results indicate that the size of diatom communities and the species population changes were heavily dependent upon to season and location parameters as well as nutrient concentrations and hydrographic factors. Major factors influencing population distributions varied with principal species responsible for dominant species and species sucession. Two distinct distributional patterns in total diatom crop were observed in the study area. Maximum standing crop observed during spring and/or summer were related to the concentration of nutrients available at the onset of the spring bloom on a large scale. On a small scale, however, the distributions of total diatom standing crops were significantly correlated with both season/location factors and with hydrographic parameters as well. Vertical stratification of diatoms was observed only in the presence of the thermocline in the water column. Within the study area there was some seasonal consistancy in the composition of the species groups. However, some species association in these environments may vary with the change of season.

• Solar Energy
• /
• v.18 no.1
• /
• pp.99-109
• /
• 1998

The study on ice thermal storage system is to improve total system performance in actual air-conditioning facilities. To attain the high efficiencies in ice thermal storage system, the improvement of thermal stratification is essential, therfore the process flow must be piston flow in thermal storage tank. Ice packing factor is better on condition that the inflowing temperature is low, the flow direction in the thermal storage is upward and the cylindericalthermal storage type is used. This result shows that the cylinderical ice storage tank has better storage capacity than the rectangular type in case of the same porocity.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.1288-1293
• /
• 2009

The TES (Thermal Energy Storage) cooling system utilizing cheaper off-peak electricity has been applied just for building air-conditioning currently and causes limitation of usage rate and inefficiency of national resources utilization. In this regard, more says the necessity to apply TES system in industrial cooling system which is longer using period and wider usage. In this study, we will approve the technical and economical improvement in efficiency of industrial cooling system applied TES system by utilizing cheaper off-peak electricity and it will attribute the promotion of TES system and stabilization of supply and demand of electric power by proving the necessity to develop more efficient industrial cooling system by combining TES system.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2005.05a
• /
• pp.241-244
• /
• 2005

The aim of this study was to determine the first outbreaks of nontoxic Gonyaulax polygramma Stein in Yeosu waters in place of harmful Cochlodinium polykrikoides Margalef, which has occurred annually in the same coastal region since 1995. The observation of cellular arrangement and structure by electron microscopy showed that G. polygramma isolated from Yeosu waters had a few spines connecting with mem-branes and prominent longitudinal ridges on the cell surface, with a cingular dis-placement 1.5 times their cell width. Furthermore, the location of the nucleus wasposterior of large oval formation according to electron microscopy. On 6 August, 2004,the first bloom of G. pozygramma occurred, the date of own its disappearance was with a maximum cell density of 8,000 cells ml$^{-1}$ on 21 August, 2004. During the period of this study, the horizontal distribution of sea water temperature and salinity showed a strong coastal front, whereas the front of DIN (Dissolved Inoganic Nitrogen) was significantly different between the occurrence and disappearance of G. polygramma blooms. These results suggested that the process of the breakdown of stratification by wind and a low level of inorganic nitrogen play important roles in the rapid growth of G. polygrmma, which is associated with a greater robustness in growth against DIN than that of C.polykrikoides in nature.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.36 no.2
• /
• pp.178-186
• /
• 2003

Seasonal variation of phytoplankton was investigated with surface mixed layer ecosystem model in the East Sea. The model consisted of four compartments (phytoplankton, zooplankton, nutrient, detritus) forced by mixed layer depths, photosynthetically available radiation and nutrient concentrations. From model results we estimated entrainment rate $2.5-4.0\;m{\cdot}day^{-1}$ to reproduce the two annual blooms, and reproduced seasonal variation of phytoplankton at southern and northern regions by the difference of surface winter mixed layer depth (MLD) using the entrainment rate value $3.0\;m{\cdot}day^{-1}$. The spring blooms in the southern and northern regions closely related to deepening of a winter surface MLD. In the southern region where MLD was shallow and phytoplankton spring bloom occurs one month in advance to the northern region where MLD was deep. The amount of light increases within the MLD during the onset of stratification and water temperature increases faster in spring in the southern region than the northern region. Decrease of phytoplankton was mainly affected by zooplankton grazing in the southern region and by nutrient exhaustion in the northern region. The fall bloom in the two regions was caused by the nutrient availability and entrainment on the phytoplankton.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.4
• /
• pp.24-30
• /
• 2004

As the environmental pollution becomes serious global problem, the regulation of emission exhausted from automobiles is strengthened. Therefore, it is very important to know how to reduce the NOx and PM simultaneously in diesel engines, which has lot of merits such as high thermal efficiency, low fuel consumption and durability. By this reason, the new concept called as Homogeneous Charge Compression Ignition(HCCI) engines are spotlighted because this concept reduced NOx and P.M. simultaneously. However, there is trade off between output and NOx in a HCCI engine. In this study, output and emission characteristics for a gasoline direct injection type HCCI engine were investigated to clarify the effects of intake air temperature, injection time and mixture formation. From these experiments, we found that the smoke was not produced when the fuel was injected earlier than BTDC 90$^{\circ}$. In addition, the output was increased because of delay of ignition time and NOx emission was decreased because of homogeneous charge of first injection in case of split injection.

• Journal of Environmental Science International
• /
• v.14 no.7
• /
• pp.639-647
• /
• 2005

The aim of this study is to determine the outbreaks of nontoxic Gonyaulax polygramma Stein in Yeosu waters in place of harmful Cochlodinium polykrikoides Margalef, which has occurred annually in the same region since 1995. The observation of cellular arrangement and structure by electron microscopy showed that G. polygramma isolated from Yeosu waters had a few spines connecting with membranes and prominent longitudinal ridges on the cell surface, with a cingular displacement 1.5 times their cell width. Furthermore, the location of the nucleus was posterior of large oval formation according to electron microscopy. On 6 August, 2004, the first bloom of G. polygramma occurred, the date of its disappearance was with a maximum cell density of 8,000 cells $ml^{-1}$ on 21 August, 2004. During the period of this study, the horizontal distribution of sea water temperature and salinity showed a strong coastal front, whereas the front of DIN (Dissolved Inorganic Nitrogen) was significantly different between the occurrence and disappearance of G. polygramma blooms. These results suggested that the process of the breakdown of stratification by wind and a low level of inorganic nitrogen play important roles in the rapid growth of G. polygramma, which is associated with a greater robustness in growth against DIN than that of C. polykrikoides in nature.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.640-641
• /
• 2003

Abnormal oceanic conditions associated with the passage of typhoons are examined using hydrographic and satellite data 1990-2002. During the passage period of typhoons in the Korean waters, an abrupt decrease of sea surface temperature(SST) in range of 5 to 8 $^{\circ}$ was observed. The areas of SST decrease were an order of 100-200km, and the low SST lasted about 15-25 days after passage of typhoon. After passage of typhoon, the water temperatures in the surface mixed layer of 30m show negative anomalies for quite a long period. In addition, stratification parameters were substantially decreased and chlorophyll a density was rapidly increased.