• Parasites, Hosts and Diseases
• /
• v.32 no.2
• /
• pp.65-74
• /
• 1994

Surface ultrastructure of Pawctrema timonnauini developmental stages was studied using a scanning electron microscope. The metacercariae were collected from the marine clam, Topes phiLippinam and juvenile and adult worms were recovered at 1, 2, 3 and 7 days after experimental infection of mice. The metacercariae had a large oral sucker and characteristic lateral projections. Around the lip of the oral sucker many type I and type II sensory papillae were observed, and type III papillae were located symmetrically on the medial side of the lateral projection. Numerous type I papillae were grouped around the genital pore. The tegumental spines were distributed over the worm surface except the lip of the suckers and genital pore. The 1-day old worm had a well-developed ventral sucker, with 6 type II sensory papillae on its outer surface and another 6 type I papillae on the inner side. Two small type I papillae were seen on the anterior side of the ventral sucker. The genital pore was small and opened separately from the ventral sucker and 15 type I papillae were grouped around it. The 2-, 3-. and 7-day worms revealed that as they grew to be adults, the spine tips became multipointed, the genital pore formed a genital atrium, and the cytoplasmic process became well differentiated. In 2- and 3-day worms 10 type II papillae encircling the lip of the oral sucker, and additional 4 papillae at the dorsal side of 4 dorsal type II papillae were a characteristic feature. The distribution pattern of sensory papillae around the oral sucker and genital pore, and 2 type I papillae on the anterior side of the ventral sucker, was so peculiar in R timonnnuini, that they seem to be useful keys for taxonomic differentiation from other gymnophallids.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.12 no.1
• /
• pp.35-46
• /
• 2009

In order to investigate spatial and temporal distributional characteristics of major water qualities in the Saemangeum area during the Saemangeum dike construction, salinity, COD, dissolved nutrients(DIN, Silicate) and heavy metals were analyzed from the surface water collected in April, May, August and November 2002. The overall value of Salinity, COD, DIN, and silicate in surface waters were in the range of $13.08{\sim}31.96\;psu$, $0.12{\sim}3.43\;mg/L$, $0.001{\sim}2.638\;mg/L$, and $0.010{\sim}3.181\;mg/L$, respectively. The COD and DIN in each survey showed the highest concentration at the mouth of Mangyeong river estuary(St. 1) where freshwater flow into the Saemangeum area. The concentrations of nutrients were high in the inner part of the Saemangeum dike with low-salinity, and low nutrients in the outer part of the dike with high-salinity, which strongly indicated that concentrations were adjusted by physical mixing. The ranges of dissolved metals and acid-soluble Hg in surface seawater were $0.006{\sim}0.115{\mu}g/L$ for Co, $0.26{\sim}0.114{\mu}g/L$ for Ni, $0.14{\sim}0.93{\mu}g/L$ for Cu, $0.04{\sim}0.53{\mu}g/L$ for Zn, $0.010{\sim}0.043{\mu}g/L$ for Cd, $0.010{\sim}0.795{\mu}g/L$ for Pb, and $0.25{\sim}4.16{\mu}g/L$ for Hg. The highest concentrations of some metals except for Cd were found at the estuary(Sts. 1 or 3). In most cases, a decreasing order of metal concentrations towards open sea(low-salinity$\rightarrow$high-salinity) was observed and showed positive relationship with DIN and silicate caused by land base pollutants input. On the other hand, due to Cd desorption from suspended solids in saline water, dissolved Cd concentrations were high in high-salinity area and low in low-salinity. In November, Co, Zn, Cu and Pb were relatively high in the northern area of the outer-side of Saemangeum, which was only influenced by the Geum river discharge. The concentrations of most dissolved metals of this study were lower than those of the past data in this area, but higher than those in Lena river estuary under the pristine environment.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.6 no.3
• /
• pp.142-151
• /
• 2001

Detailed interpretation of some high-resolution seismic profiles in Yosu Strait reveals that Late Quaternary deposits consist of three allostratigraphic units (UH, LH, PL) formed by fluvial and tidal controls. The top mud unit, UH, thins onshore, and overlies the backstepping modem Seomjin delta deposits, which is interpreted as a transgressive systems tract (757) related to Holocene relative sea-level rise. The unit LH below the unit UH is composed of delta, valley- and basin-fill facies. The delta facies (Unit $LH_1$) occurs only in Gwangyang Bay and shows two prograding sets retrogradationaly stacked, thus it is also interpreted as a transgressive systems tract(757). On the contrary, the valley- and basin-fill facies (Unit $LH_2$), interpreted as 757, occur between the units UH and PL (Pleistocene deposits) in Yosu Strait. The bounding surface between UH and $LH_2$ can be interpreted as a tidal ravinement surface on the basis of trends thinning toward inner bay and becoming young landward. Furthermore its geomorphological pattern is similar to that of recent tidal channels. This allostratigraphy in'ffsu Strait suggests that two 757 deposits (UH and $LH_2$), divided by tidal ravinement surface, have been formed in Yosu Strait, whereas in Gwangyang Bay backstepping delta deposits ($LH_1$) without tidal ravinement surface have been formed during Holocene sea-level rise. These characteristics indicate that different stacking patterns could be formed in these two areas according to different increasing rate of accommodation space caused by different geomorphology, sediment supply and tidal-current patterns even in the same period of Holocene sea-level rise.

• The korean journal of orthodontics
• /
• v.18 no.2
• /
• pp.311-327
• /
• 1988

Vascular changes in the periodontal ligament of the rat incisors following application of experimental orthodontic forces were examined by the India ink perfusion method. 57 rats were used for this experiment. The rats were divided into experimental group (54 rats) and control group (3 rats). 54 experimental rats were divided into group I (27 rats) and group II (27 rats). The right and left upper incisors of group. I and group II rats were separated distally with forces of 20gm, 70gm respectively. The vascular changes of periodontal ligament were observed histologically by means of light microscope after 1, 2 and 3 days of tooth movement and 1,3,5,8,14, and 21 days after removal of orthodontic force. The results were as follows; 1. After one day of tooth movement, occlusion of blood vessels, hyalinization of periodontal ligament and resorption of alveolar bone adjacent to the alveolar crest on pressure side were observed. Above the tissue changes on the pressure side of group II were more severe than those of group I. Especially, septal bone of group II was separated after 2 days of tooth movement. 2. In tension zones, periodontal space was widened and periodontal fibers were orientated in the direction of puil. The blood vessels of periodontal ligament were distended. New bone deposition was seen along the inner surface of the alveolus after 2 days of tooth movement. 3. After 3 days of tooth movement, deposition of new bone was seen along the periosteal surface of alveolar bone on pressure side, progressing with increasing after removal of orthodontic force. Remodelling of the new bone was occurred 5 days after removal of orthodontic force. 4. 3 days after removal of orthodontic force, invasion of blood vessels into the marginal periodontal ligament on pressure side was observed clearly and the vessels below the epithelial attachment were increased. 5. After removal of orthodontic force, hyalinized structures disappeared concomittantly with an invasion of blood vessels from the neighboring periodontal ligament. 14 days after removal of orthodontic force, the vessels in the periodontal ligament of group I were finished the vascular rearrangement. 21 days after removal of orthodontic force, the vessels in the periodontal ligament of group II were finished the vascular rearrangement.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.23 no.4
• /
• pp.334-341
• /
• 2003

When the pressure tubes(f are in contact with the calandria tube(CT) in the pressurized heavy water reactor(PHWR), the temperature difference between inner and outer wall of W results in a thermal diffusion of hydrogen (deuterium) and hydride blisters are formed on the outer surface of PT. Because the hydride blisters and zirconium matrix are acoustically continuous, it is not easy to distinguish the blisters from the matrix with conventional ultrasonic method. An ultrasonic velocity ratio method was developed to detect small hydride blisters on the zirconium pressure tube. Hydride blisters were grown in the PT specimen using a steady state thermal diffusion device. The flight times of longitudinal echo and reflected shear echo from the outer surface were measured accurately. The velocity ratio of the longitudinal wave to the shear wave was calculated and displayed using contour plot. Compared to the conventional flight time method of longitudinal wave, the velocity ratio method shows superior sensitivity to detect smaller blisters as well as better images for the blister shapes. Detectable limit of the outer shape of the hydride blisters was conservatively estimated as $500{\mu}m$, with the same specifications of ultrasonic transducer used in the actual PHWR pressure tube inspection.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.37 no.4
• /
• pp.488-496
• /
• 2010

Dens evaginatus is a tooth with cylindrical enamel projection which forms a nodule on occlusal surface. It could be explained as outward overgrowth of inner enamel epithelium or localized hyperplasia of pulpal mesenchymal tissue during tooth development. A problem is that it is likely to be worn out or fractured by mastication ensuing pulpal inflammation. It is occasionally found on the lingual surface of upper anterior teeth as well, called talon cusp. Dens invaginatus is a tooth with deep lingual pit made by invagination of lingual enamel epithelium during tooth development while it is considered normal in terms of size and shape. Radiographically, a part of cervical enamel shows inward growth forming cavity and it is reasonable to say that the base is possibly open to pulpal cavity since they are very close. Talon cusp and dens invaginatus are relatively common abnormality of shape. However it becomes the opposite if the two exist in the same tooth. Once the talon cusp is broken by occlusal force or fissure between cusps is decayed, the complicated structure of canals makes the pulpal treatment difficult. Preventive treatments such as occlusal equilibrium and sealant, and regular oral examination should be preceded and thorough understanding of canal shape, using radiography, is required when pulpal treatment is necessary. This report is about a 9- year-old boy(lower left central incisor), a 8-year-old girl(upper right central incisor), and a 7-year-old boy(upper right central incisor), who have dens invaginatus and talon cusp in the same teeth. The first and the second patients are under pulpal treatments, and the last one is being observed showing no pathologic impressions.

• Economic and Environmental Geology
• /
• v.45 no.5
• /
• pp.565-578
• /
• 2012

Sedimentary facies of the Middle to Upper Cambrian Sesong Formation, Taebacksan Basin, are analyzed using detailed field mapping and stratigraphic section measuring. As a result, five sedimentary facies are recognized in the formation, which include lime nodule bearing shale facies, anastomosing wackestone-packstone facies, well-laminated siltstone facies, fine to medium sandstone facies and lime pebble conglomerate facies. Together with sedimentary facies analysis, study on vertical facies variation indicates that the Sesong Formation was deposited in an outer to inner shelf during relative sea-level fall. Especially, shallow marine aspects of the upper part of the Sesong Formation including 10-m-thick, fine to medium-grained sandstones appear to be very similar with the shallow marine strata accumulated during the Steptoean Stage (Dunderbergia) in Laurentia. These lithofacies comparisons of coeval strata between two continents suggest that sedimentation in the Sesong Formation reflects the influence of global sea-level fall occurred during the late Middle Cambrian to early Late Cambrian. As well, a stratigraphic discontinuity surface that may have sequence stratigraphic significance is recognized within the shallow marine sandstone beds of the uppermost Sesong Formation. This stratigraphic discontinuity surface may correspond to the Sauk II-III sequence boundary in Laurentia. Therefore, results delineated in this study will use a new stratigraphic paradigm for regional correlation of the Middle to Late Cambrian strata (e.g., the Sesong Formation) in the Taebacksan Basin, and will provide very useful information on intercontinental stratigraphic correlation in the future.

• Journal of Chest Surgery
• /
• v.29 no.8
• /
• pp.836-843
• /
• 1996

Histologic, and scanning electron microscopic observa ions were made of 12 biopsy specimens from polytetrdiluoroethylene (PTFE) grafts that had been Implanted as systemic-pulmonAry shunt for improving oxygenation of cyanotic congenital heart disease and harvested near the end of pulmonary artery side at the time of redo shunt or tonal correction between 1985 and 1992. The types of shunt operation are modified Blalock-Taussig shunt in 10 cases, Waterston-Cooley shunt in 1 And Potts shunt in 1 case. The 5 mm PTFE graft was used In 10, 4mm in 1 and 6mm in 1 case. The mean duration of implantalion was 0 $\pm$ 14.1 months(rl.on 12 months to 55 months). The plAtelets were aggregated between gaps'of Coretex surface and intimal thickening was noted about 10 to 20 months after implantation. Endothelial cells were found in the 40-months patent PTFE graft by light and scanning electron microscopy. In the specimen of poor flow or zero flow graft, severe intimal hyperplasia and thrombi which was made of platelets were noted . Based on this experience, we think that the patency will be maintained well if the connective tissue could be Hxed firmly over the Inner layer of the Goretex and the endothelial cell layer sllould form over the con- nective tissue and platelet aggregation should be prevented.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.4 no.2
• /
• pp.161-170
• /
• 2006

PFC(Perfluorocarbon) decontamination process is one of best methods to remove hot particulate adhered on the inner surface of hot cell and surface of equipment in hot cell. It was necessary to develop a filtration equipment to reuse the PFC waste solution generated on PFC decontamination due to the high cost of PFC solution and for minimization of the volume of second waste solution. The filtration equipment was developed to remove hot particulate in PFC waste solution. It was made suitable size and weight in consideration of hot cell gate and crane. And it has wheels for easy movement. Flux of the filtration equipment decreased with particulate concentration increase. It consists of pre-filter($1.4{\mu}m$) and final-filter($0.2{\mu}m$) for protection of the flux decrease along filtration time. It treatment capacity of waste solution is 0.2 L/min.

• Journal of the Korean Applied Science and Technology
• /
• v.30 no.4
• /
• pp.790-796
• /
• 2013

The following is the study result of herbal tea roasted at different temperatures between $80{\sim}140^{\circ}C$. Depending on treatment temperature the water content decreased, some carbonization occurred and crude ash content relatively increased. Also crude protein and crude fat changed little. Benzopyrene content (0.17~0.35ppb) showed a tendency to increase with higher treating temperature. From this result, the $B({\alpha})P$ content differed depending on the treatment temperature and raw materials. In case of roasting, the actual inside temperature is around $200^{\circ}C$ but since the surface temperature of the roaster reaches around $2,000^{\circ}C$ some portion of $B({\alpha})P$ content was presumed to be produced from the area that came in contact with this surface. Solid elution rate of herbal tea showed 0.18~0.35%(w/w) and the rate of solid elution decreased with higher roasting temperature. There was no big change in $80{\sim}110^{\circ}C$ treatment section but the solid elution decreased rapidly in $110{\sim}140^{\circ}C$ section. The reason for decreasing solid elution rate at higher treatment temperature is because the compact inner tissue makes elution difficult.