• Journal of Advanced Navigation Technology
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• v.17 no.1
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• pp.80-89
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• 2013

The amount of object which reenter the Earth's atmosphere has been increasing after the Sputnik I launch in October 1957. Most of reentry objects were incinerated by aerodynamic heating so they hardly survive. But they may incur casualties and widespread property damages if they survive and fall to surface. The amount of reentry objects, such as Satellite, Rocket Booster, Pressure Tank, ISS shows continued growth as byproduct of space activities. Most of the re-entry objects are incinerated at between altitude of 50km~80km and 10%~40% of the objects are surviving and falling to the ground. Therefore, this paper try to piece together the reentry event and analysis the survival characteristics of re-entry object.

• Tunnel and Underground Space
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• v.13 no.1
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• pp.64-75
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• 2003

This study presents a newly suggested test method of Mode II fracture toughness measurement called "Punch Through Shear Test" which was originally proposed by Backers and Stephansson in 2001. The purpose of this study is to check the validity of the suggested testing method by performing Mode II fracture toughness tests for Daejeon Granite. In addition, the optimal specimen geometry for the testing and the relation between Mode II fracture toughness and confining pressure were also investigated. Fractured surface was observed to be very smooth with lots of rock debris which came off fracture surface which obviously implies that the surface was sheared off. This confirms that Mode II fracturing actually occurred. In addition, numerical analyses including continuum analysis, particle flow code analysis and crack propagation simulations were performed. Results of these numerical analyses indicated that the cracks occurred in the specimen were predominantly in Mode II and these cracks led to failure of the test specimen. From this investigation, it can be concluded that the newly suggested "Punch Through Shear Test" method provides a reliable means of determining the Mode II fracture toughness. fracture toughness.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.117-127
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• 1992

Japan is situated in the zone attacked repeatedly by typhoon. She is apt to be given by the nature damage like flood and loss the life and the property conventionally because of her short channel and steep slope ground. This paper is centered on the method of analysis and the damage management of river which are based on the Bulletin of the Disaster Prevention Research Institute of Kyoto University. The field of flood disaster, submersion damage, water proof system, debris control disaster and water resources are studied respectely. The river management examples which are done by Foundation of River and Basin Integrated Communications and The Yodo River are analyzed. The above analysis helps to control disaster of river in Korea.

• Tribology and Lubricants
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• v.35 no.6
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• pp.382-388
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• 2019

It is currently well known that surface textures act as lubricant reservoirs, entrap wear debris, and hydrodynamic bearings, which can lead to certain increases in load-carrying capacities. Until recently, the vast majority of research has focused on parallel sliding machine components such as thrust bearings, mechanical face seals, piston rings, etc. However, most sliding bearings have a convergent film shape in the sliding direction and their hydrodynamic pressure is mainly generated by the wedge action. Following the first part of the present study that investigates the effect of groove position on the lubrication performances of inclined slider bearings, this paper focuses on the effects of groove depths and film thicknesses. Using a commercial computational fluid dynamics (CFD) code, FLUENT, the continuity and Navier-Stokes equations are numerically analyzed. The results show that the film thickness and groove depth have a significant influence on the pressure distribution. The maximum pressure occurs at the groove depth where the vortex is found and, as the depth increases, the pressure decreases. There is also a groove depth to maximize the supporting load with the film thickness. The friction force acting on the slider decreases with deeper grooves. Therefore, properly designed groove depths, depending on the operating conditions, can improve the load-carrying capacity of inclined slider bearings as compared to the bearings without a groove.

• Korean Journal of Construction Engineering and Management
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• v.12 no.5
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• pp.103-116
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• 2011

Crack sealing is a maintenance technique commonly used to prevent water and debris penetration and reduce future degradation in pavement. In recent years, several systems for automatically routing and sealing pavement cracks have been developed in the highway construction and maintenance area. Automating pavement crack sealing can improve safety, productivity and quality, and reduce road user cost as well. The reduction in crew size and the increase in productivity of the automated sealing process will be translated directly into significant potential cost savings. The main objective of this study is to illustrate conceptual models for the development of the automated pavement crack sealer which meets domestic road condition and regulation, and to discuss its technical feasibilities. Conclusions are made concerning the applicability and the value of cantilever-typed pavement crack which is selected as the most feasible alternative in both economical and technical aspects.

• Parasites, Hosts and Diseases
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• v.40 no.1
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• pp.17-24
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• 2002

We have cloned a cDNA encoding a cysteine proteinase of the Acanthamoeba healui OC-3A strain isolated from the brain of a granulomatous amoebic encephalitis patient. A DNA probe for an A. healui cDNA library screening was amplified by PCR using degenerate oligonucleotide primers designed on the basis of conserved amino acids franking the active sites of cysteine and asparagine residues that are conserved in the eukaryotic cysteine proteinases. Cysteine proteinase gene of A. healui (AhCPI) was composed of 330 amino acids with signal sequence, a proposed pro-domain and a predicted active site made up of the catalytic residues, $Cys^{25},{\;}His^{159},{\;}and{\;}Asn^{175}$. Deduced amino acid sequence analysis indicates that AhCPI belong to ERFNIN subfamily of C 1 peptidases. By Northern blot analysis. no direct correlation was observed between AhCPI mRNA expression and virulence of Acanthamoeba, but the gene was expressed at higher level in amoebae isolated from soil than amoeba from clinical samples. These findings raise the possibility that AhCPI protein may play a role in protein metabolism and digestion of phagocytosed bacteria or host tissue debris rather than in invasion of amoebae into host tissue.

• The Korean Journal of Cytopathology
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• v.10 no.1
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• pp.35-42
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• 1999

The accuracy of fine needle aspiration cytology(FNAC) of the lymph node was investigated through a review of 176 FNAC cases and the corresponding biopsies. We chose 157 FNAC cases after the exclusion of 19 inadequate ones. Sensitivity of malignancy was 94.0%, specificity 100%, false negativity 6.0%, and false positivity 0.0%. The overall diagnostic accuracy was 96.8%. Sensitivity of metastatic carcinoma was 98.0% and that of malignant lymphoma was 87.9%. False negative cases included one metastatic carcinoma and four malignant lymphomas. The aspirates of metastatic carcinoma with false negativity exhibited a diffuse smear of keratin debris without viable cells, which led to the difficulty in differentiation from benign epithelial cyst. The cases of malignant lymphoma with false negative diagnosis were two Hodgkin diseases, one Lennert's lymphoma, and one peripheral T cell lymphoma in the histologic sections. On the analysis of 39 cases of tuberculosis, 17 cases(43.6%) were diagnosed as tuberculosis, 4(10.3%) as granulomatous lymphadenitis, 3(7.7%) as necrotizing lymphadenitis, and 15(38.5%) as reactive hyperplasia or pyogenic inflammation. Sensitivity of tuberculosis was 53.9%. In conclusion, lymph node FNAC is an excellent non-invasive diagnostic tool for the diagnosis of metastatic carcinoma. The diagnostic accuracy of malignant lymphoma could be improved with flow cytometry or polymerase chain reaction for antigen receptor genes. For the FNAC diagnosis of tuberculosis, AFB stain, culture, and PCR would be helpful as adjuvant techniques.

• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.237-245
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• 2015

A strategy is needed for a regional survey of geosynchronous orbits (GSOs) to monitor known space objects and detect uncataloged space objects. On the basis of the Inter-Agency Debris Committee's recommendation regarding the protected region of geosynchronous Earth orbit (GEO), target satellites with perigee and apogee of $GEO{\pm}200km$ and various inclinations are selected for analysis. The status of the GSO region was analyzed using the satellite distribution based on the orbital characteristics in publicly available two-line element data. Natural perturbation effects cause inactive satellites to drift to two stable longitudinal points. Active satellites usually maintain the designed positions as a result of regular or irregular maneuver operations against their natural drift. To analyze the detection rate of a single optical telescope, 152 out of 412 active satellites and 135 out of 288 inactive satellites in the GSO region were selected on the basis of their visibility at the observation site in Daejeon, Korea. By using various vertical view ranges and various numbers of observations of the GSO region, the detection efficiencies were analyzed for a single night, and the numbers of follow-up observations were determined. The orbital estimation accuracies were also checked using the arc length and number of observed data points to maintain the GSO satellite catalog.

• Restorative Dentistry and Endodontics
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• v.27 no.2
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• pp.175-182
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• 2002

Dental caries is a chronic disease that causes the destruction of tooth structure by the interaction of plaque bacteria, food debris, and saliva. There has been attempts to induce remineralization by supersaturating the Intra-oral environment around the surface enamel, where there is incipient caries. In this study, supersaturated remineralized solution "R" was applied to specimens with incipient enamel caries, and the quantitative analysis of remineralization was evaluated using microradiography. Thirty subjects volunteered to participate in this study. Removable appliances were constructed for the subjects, and the enamel specimen with incipient caries were embedded in the appliances. The subjects wore the intra-oral appliance for 15 days except while eating and sleeping. The removable appliance were soaked in supersaturated solution "R", saline, or Senstime$^{\circledR}$ to expose the specimen to those solutions three times a day, 5 minutes each time. After 15 days, microradiography was retaken to compare and evaluate remineralization The results were as the following: 1. The ratio of remineralized area to demineralized area was significantly higher in the supersaturated solution "R" and Senstime$^{\circledR}$ than in the saline (p<0.05) 2. Remineralization in the supersaturated buffer solution "R" occurred in the significantly deeper parts of the tooth. compared to the Senstime$^{\circledR}$ group containing high concentration or fluoride. (p<0.05) As in the above results, the remineralization effect of remineralized buffer solution "R" on incipient enamel caries has been proven. For clinical utilization, further studies on soft tissue reaction and the effect on dentin and cementum are necessary In conclusion compared to commercially available fluoride solution. remineralization solution“R”showed better remineralization effect on early enamel caries lesion, so it is considered as effecient solution for clinical application.

• The Journal of the Petrological Society of Korea
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• v.23 no.3
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• pp.261-272
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• 2014

Over the last three decades, advances in AMS (Accelerator Mass Spectrometry) and Noble Gas Mass Spectrometer make various application of terrestrial cosmogenic nuclides (CNs) to wide range of earth surface sciences possible. Dating techniques can be divided into three sub-approaches: simple surface exposure dating, depth-profile dating, and burial dating, depending on the condition of targeted surfaces. In terms of Korean landscape view, CNs dating can be applied to fluvial and marine terrace, alluvial fan, tectonic landform (fault scarp and faulted surfaces), debris landforms such as rock fall, talus, block field and stream, lacustrine and marine wave-cut platform, cave deposits, Pliocene basin fill and archaeological sites. In addition, in terms of lithology, the previous limit to quartz-rich rocks such as granite and gneiss can be expanded to volcanic and carbonate rocks with the help of recent advances in CNs analysis in those rocks.