• The Journal of Engineering Geology
• /
• v.10 no.1
• /
• pp.1-12
• /
• 2000

Heaving of road and subsidence of slope took place at the Wiri region of the local highway 999 in Gyeongsangbukdo, Korea after heavy rain in the next year of construction. Although the state government had performed remedial treatments by reducing the angle and the height of the slope, deformation had never stopped. Therefore, we have preformed the analysis of deformation and stabilityof the slope. Study area consists of the Cretaceous shale, siltstone and sandstone and two faults are found. The major deformation occurred by sliding of rock mass along faults after heavy rain because not only thepore pressure at the fault plane and the unit weight of sliding mass increased, but did the shearstrength of saturated fault clay become very low. The decrease in shear strength of saturated fault clayis the major factor among the reasons for deformation. Numerical simulations using limit equilibriummodel, finite difference model and finite element model were performed for eight cross sections.Although safety factors are above 1.7 during the dry season, they become below 1.0 when groundwaterlevel raises to surface. The maximum displacement is about 15-3Ocm. However, safety factors increasedto above 2.4 and the maximum displacement is below 2.08cm after remedial treatment, Indicating thatthe slope becomes stable.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.16 no.3
• /
• pp.125-138
• /
• 2011

This study was conducted to investigate the benthic condition around Busan Port by analysing spatio-temporal distribution pattern of polychaete community and some benthic environmental factors. Field survey was seasonally carried out at 15 stations covering in and outside of Busan Port from February to December, 2007. Water temperature, salinity and the type of surface sediment showed little changes among the stations, but factors related to organic enrichment such as TOC, AVS, coprostanol showed an obvious contrast, especially between in and outside of Busan Port. A total of96 species occurred and mean density was 1,814 ind./$m^2$. Species richness was higher at outer port than inner port, but density was higher at inner port. Dominant species were Aphelochaeta monilaris, Magelona japonica, Pseudopolydora paucibranchiata, etc. and many of them were typical species of organically enriched area. From the multivariate analyses, the whole study area was composed of two distinct polychaete communities located at the inside and outside of the port, and seasonal changes didn't have any influential effects on the structure. Coprostanol and AVS, indicators of organically enriched condition, well explained the community structures of polychaete worms in the vicinity of Busan Port. In this context, the innermost area of North Harbor was in a highly enriched state.

• Journal of the Korean Society for Precision Engineering
• /
• v.3 no.1
• /
• pp.40-49
• /
• 1986

Crack, craze and void are common defects which may be found in the bulk of polymeric materials such as either themoplastics or thermosets. The healing phenomena, autohesion, of these defects are known to be a intrinsic material property of various polymeric materials. However, only a few experimental and theoretical investigations on crack, void and craze healing phenomena for various polymeric materials have been reported up to date [1, 2, 3]. This may be partly due to the complications of healing processes and lacking of appropriate theoretical developments. Recently, some investigators have been urged to study the healing phenomena of various polymenic materials since the significance of the use of polymer based alloys or composites has been raised in terms of specific strength and energy saving. In the earlier published reports [1, 2, 3, 4], the crack and void healing velocity, healing toughness and some other healing mechanical and physical properties were measured experimentally and compared with predicted values by utilizing a simple model such as the reptation model under some resonable assumptions. It seems, however, that the general acceptance of the proposed modeling analyses is yet open question. The crack healing processes seem to be complicate and highly dependent on the state of virgin material in terms of mechanical and physical properties. Furthermore, it is also strongly dependent on the histories of crack, craze and void development including fracture suface morphology, the shape of void and the degree of disentanglement of fibril in the craze. The rate of crack healing may be a function of environmental factors such as healing temperature, time and pressure which gives different contact configurations between two separated surfaces. It seems to be reasonable to assume that the crack healing processes may be divided in several distinguished steps like stress relaxation with molecular chain arrangement, surface contact (wetting), inter- diffusion process and com;oete healing (to obtain the original strength). In this context, it is likely that we no longer have to accept the limitation of cumulative damage theories and fatigue life if it is probable to remove the defects such as crack, craze and void and to restore the original strength of polymers or polymer based compowites by suitable choice of healing histories and methods. In this paper, we wish to present a very simple and intuitive theoretical model for the prediction of healed fracture toughness of cracked or defective polymeric components. The central idea of this investigation, thus, may be the modeling of behavior of chain molecules under healing conditions including the effects of chain scission on the healing processes. The validity of this proposed model will be studied by making comparisons between theoretically predicted values and experimentally determined results in near future and will be reported elsewhere.

• Journal of Preventive Medicine and Public Health
• /
• v.20 no.2 s.22
• /
• pp.280-286
• /
• 1987

For evaluating the boosting (anamnestic) effects of the most recent commercially produced plasma derived heat-inactivated hepatitis B vaccine (A. Co.), 117 adults with naturally acquired antibody to hepatitis B surface antigen (anti-HBs) were selected at random. In addition, out of case immunized at zero and 1 month, and boosted at 6 months (primary boosting) by conventional vaccine (B. Co), inactivated by pepsin digestion and formalin treatment, 11 cases who showed elevated titer after primary boosting were also submitted to the study. The results were as follows: 1) Out of the 117 subjects with naturally acquired anti-HBs, 6(5.1%) showed isolated anti-HBs and the titers were below 10 ratio units (RU). Negative seroconversion was seen in 4(3.4%) of the 117 cases at 12 months after the screening and, of these cases, 3 showed isolated anti-HBs and the titers were below 10 RU. 2) Eighty-three percent of the cases with naturally acquired isolated anti-HBs below 10 RU did not respond to a booster injection with 3 us dose of A. Co. vaccine at all, but 90% of the other subjects responded. 3) The anti-HBs titers of all the 11 cases who showed a rise of more than 10 RU (increased GMT, 28.04) at one month after primary booster injection by $20{\mu}g$ dose of B. Co. vaccine decreased at 19 months after the primary booster. And 3 subjects (27.3%) of the 11 reached negative seroconversion. All of the 11 cases, who had secondary booster injection with $3{\mu}g$ dose of A. Co. vaccine at 19 months after primary boosting, showed increased anti-HBs titer at least 20 RU or more (increased GMT, 57. 72) at one month after the boosting. According to the above results in the anti-HBs screening survey for the purpose of immunization with hepatitis B vaccine, subjects with isolated anti-HBs below 10 RU should be regarded as being in an unimmunized state. In cases who are in risk circumstances, immunized primarily with a $20{\mu}g$ dose of B. Co. vaccine, a secondary booster injection should be given within 2 years after initiation of primary immunization and a $3{\mu}g$ booster dose of A. Co. vaccine can be reliably used.

• Journal of the Korean Vacuum Society
• /
• v.7 no.4
• /
• pp.368-373
• /
• 1998

As device dimensions approach submicrometer size in ULSI, the demand for interlayer dielectric materials with very low dielectric constant is increased to solve problems of RC delay caused by increase in parasitic resistance and capacitance in multilevel interconnectins. Fluorinated amorphous carbon in one of the promising materials in ULSI for the interlayer dielectric films with low dielectric constant. However, poor thermal stability and adhesion with Si substrates have inhibited its use. Recently, amorphous hydrogenated carbon (a-C:H) film as a buffer layer between the Si substrate and a-C:F has been introduced because it improves the adhesion with Si substrate. In this study, therfore, a-C:F/a-C:H films were deposited on p-type Si(100) by ECRCVD from $C_2F_6, CH_4$and $H_2$gas source and investigated the effect of forward power and composition on the thickness, chemical bonding state, dielectric constant, surface morphology and roughness of a-C:F films as an interlayer dielectric for ULSI. SEM, FT-IR, XPS, C-V meter and AFM were used for determination of each properties. The dielectric constant in the a-C:F/a-C:H films were found to decrease with increasing fluorine content. However, the dielectric constant increased after furnace annealing in $N_2$atomosphere at $400^{\circ}C$ for 1hour due to decreasing of flurorine content. However, the dielectric constant increased after furnace annealing in $N_2$atmosphere at $400^{\circ}C$ for 1hour due to decreasing of fluorine concentration.

• Korean Journal of Ichthyology
• /
• v.10 no.2
• /
• pp.207-215
• /
• 1998

Just after hatching the embryo has a yolk sac and straighted digestive tract. Just after parturition in 5.0mm TL the mouth and anus were opened. In the larval stage of 5.2mm TL, digestive tract could be divided into pharynx, esophagus, stomach, pyloric caeca and intestine of the early differentiated state. The esophagus of larvae in 5.3mm TL has a PAS positive mucous cell. From over 5.7mm TL, PAS positive goblet cell recognized in the intestine. PAS positive absorptive cell began to appear in the intestine from 5.9mm TL. Yolky materials were absorbed completely in 6.0mm TL. In the larvae of B.5mm TL, gastric glands were observed in the mucosa, but the surface epithelium did not have PAS positive granules. From over 9.0mm TL, the histological structure of esophagus showed similar to adult. In the juvenile stage from 13.0mm to 15.0mm TL, histological structure of the stomach, pyloric caeca and intestine showed similar to adult. From the ultrastructural and histochemical study, it is concluded that the functional digestive tract is present in the juvenile stage from 18.0mm to 20.0mm TL.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.4
• /
• pp.7-14
• /
• 2000

A Bi$_{4}$Ti$_{3}$O$_{12}$ (BIT) thin film is prepared by sol-gel method using acetate precursors and evaluated whether it could be applied to NVFRAM (Non-Volatile Ferroelectric RAM). The drying and the annealing temperature are 40$0^{\circ}C$ and $650^{\circ}C$, respectively and they are determined from the DT-TG (Differential Thermal-Thermal Gravimetric) analysis. The BIT thin film deposited on Pt/Ta/SiO$_{2}$/Si substrate shows orthorhombic perovskite phase. The grain size and the surface roughness are about 100 nm and 70.2$\AA$, respectively. The dielectric constant and the loss tangent at 10 KHz are 176 and 0.038, respectively, and the leakage current density at 100 ㎸/cm is 4.71 $mutextrm{A}$/$\textrm{cm}^2$. In the results of hysteresis loops measured at $\pm$250 ㎸/cm, the remanent polarization (Pt) and the coercive field (Ec) are 5.92 $\mu$C/$\textrm{cm}^2$ and 86.3 ㎸/cm, respectively. After applying 10$^{9}$ square pulses of $\pm$5V, the remanent polarization of the BIT thin film decreases as much as about 33% from 5.92 $\mu$C/$\textrm{cm}^2$ of initial state to 3.95 $\mu$C/$\textrm{cm}^2$.

• KSBB Journal
• /
• v.11 no.1
• /
• pp.77-85
• /
• 1996

The optimal initial pH for the ethanol production by Saccharomyces K35 was found to be 5.0, and about 80% of yield was obtained when 200g/$\ell$ of glucose was used as a substrate, which showed sugar tolerant. As the additives and cross-linking agent, the addition of 1.67%(w/v) Celite R-634 together with 0.33%(v/v) of glutaraldehyde(ACG bead) resulted in better stability, ethanol productivity and cell viability than Ca-alginate bead. Also, ACG bead seemed to be more resistant to phosphate ion than Ca-alginate bead, considering outgrowing cell concentration in the media. Scanning electron microscopic observation depicted that the surface of ACG bead was almost similar to the original state but not for Ca-alginate bead. When repealpd-batch culture was performed with Ca-alginate bead for 60 days in a 500m1 Erlenmeyer flask, ethanol and cell concentration were maintained about 138g/$\ell$-gel and 29~30g/$\ell$-gel, respectively, up to 40 days(7th run number), and then both were rapidly decreased. In the case of ACG bead, ethanol and cell concentration were maintained about 130~150g/$\ell$-gel and 32~35g/$\ell$-gel, respectively, up to 60days(10th run number). Cell viability was maintained about 70%, and outgrowing cell concentration was below 5.8% of total cell concentration.

• Current Industrial and Technological Trends in Aerospace
• /
• v.6 no.1
• /
• pp.90-98
• /
• 2008

Nanotechnology(NT) refers to a field of advanced micro-technology covering the creation and manufacturing of materials on the atomic and molecular scale and requires interdisciplinary study with various fields including materials science, physics, chemistry, electronics and others. Whileas nanotechnology is a kind of micro and small scaled science, space technology(ST) is one of the larger and system technologies utilizing broad fields of mechanical, materials, electronics and communication technologies. It is necessary to select and concentrate the functional items of nanotechnology for efficient application to be utilized in space technology, due to the cross-sectional characteristics of nanotechnology within nanomaterials, nanoelectronics, and nanomanufacturing. This paper provides the current state of art of nanotechnology in space technology by evaluating NASA's activities and the 9th frame of the project ANTARES(Analysis of Nanotechnology Applications in Space Developments and Systems) with the support of the German Aerospace Center (DLR), Space Flight Management, Division Technology for Space Systems and Robotics. It has shown that it is necessary to apply nanotechnology to space technology in order to achieve international competitiveness, for the nanotechnology can bring the previously impossible things to reality. Since KARI plans to send an unmanned probe to the moon's orbit and land a probe on the moon's surface in 2025, it is urgently needed to incorporate nanotechnology to national space development plan.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.26 no.4
• /
• pp.477-482
• /
• 2010

In a case of multiple posterior teeth loss, antagonistic teeth extrude to the edentulous space and compensatory occlusion on the remained anterior teeth leads to occlusal trauma. Extrusion of antagonistic teeth breaks down occlusion plane and loss of posterior support bring about severe wear of remained teeth. In this situation, it is needed to restore remained teeth and edentulous space by increasing vertical dimension to obtain prosthodontic rehabilitation space and to correct occlusion plane. In this case report, the patient had a masticatory problem with loss of posterior teeth support and an esthetic problem of shortened anterior teeth. Before the tooth preparation for the prosthodontic restoration, the patient used removable device for 2 months to increase vertical dimension reversibly. After that, he got provisional fixed restoration with irreversible tooth reduction and used it for 3 months. It had spent 5 month to evaluate the adaptation state on final restoration with incresed vertical dimension. The increasing amount was 3 mm, which was relatively in less degree and masticatory system adapted to the increased vertical dimension without any pathologic changes. Final restoration was made to have equal-intensity contacts on all teeth in a verifiable centric relations and immediate disclusion of all posterior contacts the moment the mandible moves in any direction from centric relation. In addition, metal occlusion surface on posterior teeth was applied to prevent excessive muscle activation, occlusal trauma and the porcelain fracture.