• Journal of Wetlands Research
• /
• v.7 no.1
• /
• pp.129-138
• /
• 2005

The flora and vegetation of Jang-cheok wetland (Gyeong-nam) was investigated from April 1. 2004 to Feburary 28. 2005. The vegetation plants collected from this area were 18 taxa : 18 species 17 genera 14 families. Hygrophtes were 2 species 2 genera 2 families. Emergent plants were 6 species 5 genera 6 families. Submersed plants were 1 species 1 genera 1 families. Floating-leaved plants were 5 species 5 genera 5 families. Free-floating plants were 2 species 3 genera 2 families. Dominance of life form was investigated Trapa japonica, Phragmites commnis, Leersia japonica by 5 dominance values and Hydrocharis dubia, Ceratophyllum dmersum were 1 dominance values. The community was investigated 5 communities : Leersia japonica community. Trapa japonica community. Nelumbo nucifera community. Miscanthus sacchariflorus community. Phragmites communis community. Dominance species(Leersia japonica) of Leersia japonica community was investigated $1,89g/m^{2}$(Dry weight) and $1,730ind./m^{2}$(Density). Doninance species(Trapa japonica) of Trapa japonica community was investigated $36,25g/m^{2}$(Dry weight) and $15.20ind./m^{2}$(Density). Dominance species(Nelumbo nucifera) of Nelumbo nucifera community was investigated $30.59g/m^{2}$(Dry weight) and $11.20ind./m^{2}$(Density). Dominance species(Miscanthus sacchariflorus) of Miscanthus sacchariflorus community was investigated $180.50g/m^{2}$(Dry weight) and $124.80ind./m^{2}$(Density). Dominance species(Phragmites communis) of Phragmites communis community was investigated $159.50g/m^{2}$(Dry weight) and $60.00ind./m^{2}$(Density). The predominant species of this area was investigated Trapa. Japonica and the other communities was only small area in the waterside area.

• Journal of fish pathology
• /
• v.5 no.2
• /
• pp.93-118
• /
• 1992

The research was carried out to examine the chronic toxic effects of nitrite on the Japanese eel, Anguilla japonica by neans of histological observations. Young eel, 10.8g mean body weight. were exposed to 6 different concentrations of nitrite(1, 5, 10, 20, 30 and 40ppm) for 10 weeks. Each concentration was treated under 5 different levels of pH(5.5, 6.0, 6.5, 7.0 and 7.5) and each of these treatment was tested at 2 different temperature regimes($25^{\circ}C$ and $30^{\circ}C$). Proper concentration of nitrite was made by $NaNO_2$ and proper pH levels were made by the combinations of 0.1M $KH_2PO_4$ and 0.1M $NaHCO_3$. Histopathological test of gill tissues were made along with the test of the formation of thrombocystes and chloride cells on the gill filaments. At the lower pH levels, mucus secretion from the gill was incrased as the nitrite concentration increased. As the level of nitrite increased the number of chloride cells on the gill filament were decreased. Most of the remained chloride cells were observed only at the terminar part of the gill filament at 40ppm of nitrite. Degeneration of gill tissues were observed when nitrite levels were over 10ppm along with detachement and sweption of the epithelial cells of the gill lamellae. Shrunken gill lamellae and formation of thrombosis in the capillaries of gill lamellae were also observed. When temperature goes higher at the higher level of nitrite, necroses in the gill lamellae was increased. At the lower than 10ppm of nitrite, degeneration of gill lamellae was occured at the beginning of the test period but regenerated later. Negative effects of nitrite on the growth of young eel was started between 5~10ppm at the pH level of 7.0 and 7.5. Thrombosis formation were also started at this level. The safety concentration of nitrite at the pH levels of 7.0 and 7.5 on the small eel seems to be 1ppm. Thrombosis and gill lamella detachment and necrosis in the gill capillaries were not observed at this level. Chloride cells were appeared the whole part of the gill filament.

• The Journal of Korean Academy of Prosthodontics
• /
• v.48 no.3
• /
• pp.224-231
• /
• 2010

Purpose: This study was to investigate how the crestal module design could affect the level of marginal bone stress around dental implant. Materials and methods: A submerged implant of 4.1 mm in diameter and 10 mm in length was selected as baseline model (Dentis Co., Daegu,Korea).A total of 5 experimental implants of different crestal modules were designed (Type I model : with microthread at the cervical 3 mm, Type II model : the same thread pattern as Type I but with a trans-gingival module, Type III model: the same thread pattern as the control model but with a trans-gingival module, Type IV model: one piece system with concave transgingival part, Type V model: equipped with beveled platform). Stress analysis was conducted with the use of axisy mmetric finite element modeling scheme. A force of 100 N was applied at 30 degrees from the implant axis. Results: Stress analysis has shown no stress concentration around the marginal bone for the control model. As compared to the control model, the stress levels of 0.2 mm areas away from the recorded implant were slightly lower in Type I and Type IV models, but higher in Type II, Type III and Type V models. As compared to 15.09 MPa around for the control model, the stress levels were 14.78 MPa, 18.39 MPa, 21.11 MPa, 14.63 MPa, 17.88 MPa in the cases of Type I, II, III, IV and V models. Conclusion: From these results, the conclusion was drawn that the microthread and the concavity with either crestal or trans-gingival modules maybe used in standard size dental implants to reduce marginal bone stress.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.9B
• /
• pp.610-618
• /
• 2005

As developed Internet and Computer Capability, Many Users take the many information through the network. So requirement of User that use to network was rapidly increased and become various. But it spend much time to accept user requirement on current network, so studied such as Active network for solved it. This Active node on Active network have the capability that stored and processed execution code aside from capability of forwarding packet on current network. So required execution code for executed packet arrived in active node, if execution code should not be in active node, have to take by request previous Action node and Code Server to it. But if this execution code take from previous active node and Code Server, bring to time delay by transport execution code and increased traffic of network and execution time. So, As used execution code stored in cache on active node, it need to increase execution time and decreased number of request. So, our paper suggest ANC caching technique that able to decrease number of execution code request and time of execution code by efficiently store execution code to active node. ANC caching technique may decrease the network traffic and execution time of code, to decrease request of execution code from previous active node.

• The Journal of Korean Academy of Prosthodontics
• /
• v.50 no.3
• /
• pp.162-168
• /
• 2012

Purpose: Teeth are generally exposed when people smiling. Moreover, the exposed teeth and soft tissue when smiling becomes an important guideline for esthetically prosthetic restoration. This research is to compare and find out differences of Korean young men's smile living in presence and twenty years ago. Materials and methods: Subjects, 100 young men (50 male and 50 female), were required about several aspects; normally developed physical condition, no psychological or genetic disorders, a fine face with no loss of teeth, no experience in orthodontic or prosthetic treatment, relatively normal occlusion, aged between 20-29. The photos of the subject at rest position and front face when fully smiled were taken three times. 100 photos (50 male and 50 female) were chosen at random from the 240 university students' smile photos taken by Yoon and his colleagues in 1991. By Hulsey's method of measuring smile, several factors; the change of upper lip curvature, the change of the relation between the upper lip and teeth, parallelism between Mx. incisor and lower lip, contact relation between Mx. incisor and lower lip and teeth displayed in a smile, were measured and analyzed. Meanwhile, ten dentists assessed aesthetic evaluation about men and women's smile for twice and recorded and compared smile score. The -test (P<.05) was used to compare the measured value. The difference of smile score was analyzed by t-test (P<.05). Results: The smile score calculated in 2011 (60.22) was higher than that of 1991 (52.80). Among five measurement categories, the noticeable difference was distinguished from two factors; the change of upper lip curvature and contact relation between Mx. incisor and lower lip. Conclusion: The Korean young men's smile has been considerably improved for twenty years. And it is found that the change of upper lip curvature plays an important role, that is, the smile formed with an ascended labial commissure has been increased significantly.

• Restorative Dentistry and Endodontics
• /
• v.35 no.4
• /
• pp.267-272
• /
• 2010

Screw-in effect is one of the unintended phenomena that occurs during the root canal preparation with nickel-titanium rotary files. The aim of this study was to compare the screw-in effect among various nickel-titanium rotary file systems. Six different nickel-titanium rotary instruments (ISO 20/.06 taper) were used: $K3^{TM}$ (SybronEndo, Glendora, CA, USA), $M_{two}$ (VDW GmbH, Munchen, Germany), NRT with safe-tip and with active tip (Mani Inc., Shioya-gun, Japan), ProFile$^{(R)}$ (Dentsply-Maillefer, Ballaigues, Switzerland) and ProTaper$^{(R)}$ (Dentsply-Maillefer, Ballaigues, Switzerland). For ProTaper$^{(R)}$, S2 was selected because it has size 20. Root canal instrumentations were done in sixty simulated single-curved resin root canals with a rotational speed of 300 rpm and single pecking motion. A special device was designed to measure the force of screw-in effect. A dynamometer of the device recorded the screw-in force during simulated canal preparation and the recorded data was stored in a computer with designed software (LCV-USE-VS, Lorenz Messtechnik GmbH, Alfdorf, Germany). The data were subjected to one-way ANOVA and Tukey's multiple range test for post-hoc test. P value of less than 0.05 was regarded significant. ProTaper$^{(R)}$ produced significantly more screw-in effects than any other instruments in the study (p < 0.001). $K3^{TM}$ produced significantly more screw-in effects than $M_{two}$, and ProFile$^{(R)}$ (p < 0.001). There was no significant difference among $M_{two}$, NRT, and ProFile$^{(R)}$ (p > 0.05), and between NRT with active tip and NRT with safe one neither (p > 0.05). From the result of the present study, it was concluded, therefore, that there seems significant differences of screw-in effect among the tested nickel-titanium rotary instruments. The radial lands and rake angle of nickel-titanium rotary instrument might be the cause of the difference.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.37 no.2
• /
• pp.106-116
• /
• 2001

A serious of studies on the fishing gear and system of the East Sea trawl fishery was carried out to improve the fishing efficiency and the working conditions. As the first step of these studies, the fishing gear and system of the traditional East Sea trawl were checked in order to solve the some problems, such as the poor sheering efficiency of net mouth, the inconvenient fishing system of the side trawl and etc. And then the fishing system was reorganized from the side trawl into the stern trawl by setting up the net drum system on the stern deck, and introduction of two types of new designed nets, one for mainly the midwater trawl and the other for the bottom trawl. The results of the field experiment on the modified system and nets can be summarized as follows : 1. the modified system was well worked and could save the man-labour by about 80%. 2. The sheering efficiency of the improved net, A type was improved to 20 m height and 30 m width in the net mouth, and that of B type net, to 10 m height and 33 m width, compared with 1.5 m height and 15 m width in the traditional net. 3. Catch efficiency of pink shrimp in A or B type net was better about 3 or 5 times than that of traditional net, and in B net, for herring and other bottom fishes is better about 2 times than that of the traditional net.

• Economic and Environmental Geology
• /
• v.18 no.4
• /
• pp.399-410
• /
• 1985

Bentonites from the Janggi Group of the Lower Miocene age from the Geumgwangdong area, Korea, have been studied for mineralogical and genetic characterization. The Janggi Group is subdivided, in ascending order, into the Janggi Conglomerate, the Nuldaeri Tuff, the Geumgwangdong Shale, the Lower Coal-bearing Formation, the Basaltic Tuff, and the Upper Coalbearing Formation. Bentonites occur as thin or thick beds in all sedimentary units of the Janggi Group, except for the Janggi Conglomerate. Significant bentonite deposits are found in the Nuldaeri Tuff, the Lower Coal-bearing Formation and the Basaltic Tuff. Bentonites consist mainly of smectite (mainly montmorillonite), with minor quartz, cristobalite, opal-CT and feldspar. Occasionally, kaolinite, clinoptilolite or gypsum is associated with bentonites. Bentonites were studied by the methods of petrographic microscopy, X-ray diffraction, thermal analysis (DT A and TG), infrared absorption spectroscopic analysis, SEM, intercalation reaction, and chemical analysis. Smectites commonly occur as irregular boxwork-like masses with characteristic curled thin edges, but occasionally as smoothly curved to nearly flat thin flakes. Most of smectites have layer charge of 0.25-0.42, indicating typical montmorillonite. Crystal-chemical relations suggest that Fe is the dominant substituent for Al in the octahedral layer and there are generally no significant substituents for Si in the tetrahedral layer. Ca is the dominant interlayer cation in montmorillonite. Therefore, montmorillonite from the study area is dioctahedral Ca-montmorillonite. Occurrence and fabrics of bentonites suggest that smectites as well as cristobalite, opal-CT and zeolites have been formed diagenetically from tuffaceous materials. The precursor of smectites is trachytic or basaltic tuff. Smectites derived from the former contain relatively more $Al_2O$ a and less $Fe_2O_3$ than those from the latter.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.2
• /
• pp.169-179
• /
• 2004

The purpose of this study was to discriminate clinically and radiographically among the three groups of dentigerous cysts studied. First, Group I, involved area of dentigerous cyst was successive permanent tooth area beneath deciduous tooth. Second, Group II, involved permanent molar area, and the last, Group III involved maxillary anterior supernumerary tooth area. The author observed and compared the clinico-radiographic features of 49 cases of Group I, 36 cases of Group II, and 15 cases of Group III of dentigerous cyst and this observation and comparison had been done by based on the charts and panoramic films. The obtained results were as follows: 1. The cases of Group I were 29 cases and, those of Group II were 36 and those of Group III were 15. 2. The incidence of dentigerous cyst is high in first decade. In Group I, before first decade and early first decade was 87.8%, in Group II and Group III, was discovered more lately. 3. The frequency of dentigerous cyst is 2.5 times higher in male than in female. 4. The sequence of chief complaint was swelling(50%), routine examination(32%), and pain(9%). 5. When considering the type of the cyst, lateral type is many most in Group I (71.4%) and central type is many most in Group II (94.4%) and Group III (100%). 6. The most size of dentigerous cyst was 2 crown size in Group I, 1 crown size in Group II, above of 4 crown size in Group III. 7. Almost involved teeth showed displacement and some tooth of displaced teeth showed delayed root development and dilaceration of root. 8. The most many response of alveolar bone was buccal bone expansion in Group I (67.3%), no bone expansion in Group II(66.7%) and palatal bone expansion in Group III (60.0%). 9. The percentage of involved teeth were as follows : The mandibular third molar was 31% and many most. The mandibular second premolar was 30%. Mesiodens of maxillary anterior area was 15%. The maxillary canine was 8%. The mandibular first premolar was 5%. 10. In the Group I, causes suggesting of dentigeous cyst are pulpotomized deciduous tooth(59.2%), severe dental caries of deciduous tooth, untreated traumatic history on the deciduous tooth etc. 11. The treatment method of dentigerous was marsupialization in 61.2% of cases of Group I and that was enucleation in 61.1% of cases of Group II and in 80.0% of cases of Group III.

• Journal of Korea Water Resources Association
• /
• v.47 no.6
• /
• pp.537-546
• /
• 2014

Surface image velocimetry was introduced as an efficient and sage alternative to conventional river flow measurement methods during floods. The conventional surface image velocimetry uses a pair of images to estimate velocity fields using cross-correlation analysis. This method is appropriate to analyzing images taken with a short time interval. It, however, has some drawbacks; it takes a while to analyze images for the verage velocity of long time intervals and is prone to include errors or uncertainties due to flow characteristics and/or image taking conditions. Methods using spatio-temporal images, called STIV, were developed to overcome the drawbacks of conventional surface image velocimetry. The grayscale-gradient tensor method, one of various STIVs, has shown to be effectively reducing the analysis time and is fairly insusceptible to any measurement noise. It, unfortunately, can only be applied to the main flow direction. This means that it can not measure any two-dimensional flow field, e.g. flow in the vicinity of river structures and flow around river bends. The present study aimed to develop a new method of analyzing spatio-temporal images in two-dimension using cross-correlation analysis. Unlike the conventional STIV, the developed method can be used to measure two-dimensional flow substantially. The method also has very high spatial resolution and reduces the analysis time. A verification test using artificial images with lid-driven cavity flow showed that the maximum error of the method is less than 10 % and the average error is less than 5 %. This means that the developed scheme seems to be fairly accurate, even for two-dimensional flow.