• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.2
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• pp.166-179
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• 2008

Excessive concentration of stress which is occurred in occlusion around the implant in case of the implant supported fixed partial denture has been known to be the main cause of the crestal bone destruction. Therefore, it is essential to evaluate the stress analysis on supporting tissue to get higher success rates of implant. The purpose of this study was to evaluate the effects of stress distribution and deformation in 3 different types of three-unit fixed partial denture sup-ported by two implants, using a three dimensional finite element analysis in a three dimensional model of a whole mandible. A mechanical model of an edentulous mandible was generated from 3D scan, assuming two implants were placed in the left premolars area. According to the position of pontic, the experiments groups were divided into three types. Type I had a pontic in the middle position between two implants, type II in the anterior posi-tion, and type III in the posterior position. A 100-N axial load was applied to sites such as the central fossa of anterior and posterior implant abutment, central fossa of pontic, the connector of pontic or the connector between two implants, the mandibular boundary conditions were modeled considering the real geometry of its four-masticatory muscular supporting system. The results obtained from this study were as follows; 1. The mandible deformed in a way that the condyles converged medially in all types under muscular actions. In comparison with types, the deformations in the type II and type III were greater by 2-2.5 times than in the type I regardless of the loading location. 2. The values of von Mises stresses in cortical and cancellous bone were relatively stable in all types, but slightly increased as the loading position was changed more posteriorly. 3. In comparison with type I, the values of von Mises stress in the implant increased by 73% in Type II and by 77% in Type III when the load was applied anterior and posterior respectively, but when the load was applied to the middle, the values were similar in all types. 4. When the load was applied to the centric fossa of pontic, the values of von Mises stress were nearly $30{\sim}35%$ higher in the type III than type I or II in the cortical and cancellous bone. Also, in the implant, the values of von Mises stress of the type II or III were $160{\sim}170%$ higher than in the type I. 5. When the load was applied to the centric fossa of implant abutment, the values of von Mises stress in the cortical and cancellous bone were relatively $20{\sim}25%$ higher in the type III than in the other types, but in the implant they were 40-45% higher in the type I or II than in the type III. According to the results of this study, musculature modeling is important to the finite element analysis for stress distribution and deformation as the muscular action causes stress concentration. And the type I model is the most stable from a view of biomechanics. Type II is also a clinically accept-able design when the implant is stiff sufficiently and mandibular deformation is considered. Considering the high values of von Mises stress in the cortical bone, type III is not thought as an useful design.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.349-354
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• 2009

In this study, a bubbling fluidized-bed reactor was used to study $CO_2$ capture from flue gas using a potassium-based dry sorbent. A dry sorbent, manufactured by the Korea Electric Power Research Institute, consists of 35% of $K_2CO_3$ for $CO_2$ absorption and 65% of supporters for mechanical strength. $H_2O$, a reactant of the carbonation reaction, was supplied in the reactor as a form of saturated water vapor at a given temperature. The experiment of the regeneration reaction was performed by raising up to a given temperature using $N_2$ as a fluidization gas. It was indicated that sorption capacity and regenerability of dry sorbents showed high-efficiency at $1.97\;mol\;H_2O/mol\;CO_2$ and $400^{\circ}C$, respectively. The regenerated sorbent samples were analyzed by TGA to confirm the extent of the reaction. When the regeneration temperature was $150^{\circ}C$, the regenerability of dry sorbents was about 60%, which was capable of applying those sorbents to a two-interconnected fluidized-bed reactor system with continuous solid circulation. The results obtained in this study can be used as basic data for designing and operating a large scale $CO_2$ capture process with two fluidized-bed reactors.

• Korean Security Journal
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• no.21
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• pp.75-94
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• 2009

Since mechanical security systems are mostly composed of electronic, information and communication devices, they have effects in the aspects of overall social environment and crime-oriented environment. Also, the importance is increasing for wireless recognition of RFID and tracing function, which will be usefully utilized in controlling the incomings and outgoings of people/vehicles or allowance, surveillance and control. This is resulting from the increase in the care for the elderly according to the overall social environment, namely, the aging society, and the number of women entering, as well as the increase in the number of heinous crimes. The purpose of this study is to examine the theoretical considerations on ubiquitous sensor network and present a direction for securities companies for their development by focusing on the technological and application areas. To present strategies of response to a new environment for security companies, First, a diversification strategy is needed for security companies. The survival of only high level of security companies in accordance with the principle of liberal market competition will bring forth qualitative growth and competitiveness of security market. Second, active promotion by security companies is needed. It is no exaggeration to say that we are living in the modern society in the sea of advertisements and propaganda. The promotional activities that emphasize the areas of activity or importance of security need to be actively carried out using the mass media to change the aware of people regarding security companies, and they need to come up with a plan to simultaneously carry out the promotional activities that emphasize the public aspect of security by well utilizing the recent trend that the activities of security agents are being used as a topic in movies or TV dramas. Third, technically complementary establishment of ubiquitous sensor network and electronic tag is needed. Since they are used in mobile electronic tag services such as U-Home and U-Health Care, they are used throughout our lives by forming electronic tag environment within safe ubiquitous sensor network based on the existing privacy guideline for the support of mobile electronic tag terminal commercialization, reduction in communication and information usage costs, continuous technical development and strengthening of privacy protection, and the system of cooperation of academic-industrial-research needs to be established among the academic world and private research institutes for these parts.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.150-156
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• 2000

Purpose : Stereotactic radiation therapy (SRT) can deliver highly focused radiation to a small and spherical target lesion with very high degree of mechanical accuracy. For non-spherical and large lesions, however, inclusion of the neighboring normal structures within the high dose radiation volume is inevitable in SRT This is to report the beam shaping using the partial closure of the independent jaw in SRT and the verification of dose calculation and the dose display using a home-made soft ware. Materials and Methods : Authors adopted the idea to partially close one or more independent collimator jaw(5) in addition to the circular collimator cones to shield the neighboring normal structures while keeping the target lesion within the radiation beam field at all angles along the arc trajectory. The output factors (OF's) and the tissue-maximum ratios (TMR's) were measured using the micro ion chamber in the water phantom dosimetry system, and were compared with the theoretical calculations. A film dosimetry procedure was peformed to obtain the depth dose profiles at 5 cm, and they were also compared with the theoretical calculations, where the radiation dose would depend on the actual area of irradiation. Authors incorporated this algorithm into the home-made SRT software for the isodose calculation and display, and was tried on an example case with single brain metastasis. The dose-volume histograms (DVH's) of the planning target volume (PTV) and the normal brain derived by the control plan were reciprocally compared with those derived by the plan using the same arc arrangement plus the independent collimator jaw closure. Results : When using 5.0 cm diameter collimator, the measurements of the OF's and the TMR's with one independent jaw set at 30 mm (unblocked), 15.5 mm, 8.6 mm, and 0 mm from th central beam axis showed good correlation to the theoretical calculation within 0.5% and 0.3% error range. The dose profiles at 5 cm depth obtained by the film dosimetry also showed very good correlation to the theoretical calculations. The isodose profiles obtained on the home-made software demonstrated a slightly more conformal dose distribution around the target lesion by using the independent jaw closure, where the DVH's of the PTV were almost equivalent on the two plans, while the DVH's for the normal brain showed that less volume of the normal brain receiving high radiation dose by using this modification than the control plan employing the circular collimator cone only. Conclusions : With the beam shaping modification using the independent jaw closure, authors have realized wider clinical application of SRT with more conformal dose planning. Authors believe that SRT, with beam shaping ideas and efforts, should no longer be limited to the small spherical lesions, but be more widely applied to rather irregularly shaped tumors in the intracranial and the head and neck regions.

• Pediatric Infection and Vaccine
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• v.7 no.2
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• pp.193-200
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• 2000

Purpose : This study was designed and performed for evaluations of clinical manifestation and course of the children under 2 year of age with respiratory tract infection and positive respiratory syncytial virus(RSV) antigen. Methods : The selection criteria of the patients were children under 24 month-of-age, Clinical manifestation of respiratory tract infection, and positive RSV antigen that was detected by Vitek ImmunoDiagnostic Assay System(VIDAS) from nasal cavity. The additional laboratory and simple chest X-ray findings were reviewed from the chart of children who were admitted Wonkwang university hospital from October 1999 to March 2000. Results : Total number of patients enrolled on this study was 102. The 48(47%) children were RSV antigen positive by VIDAS method. Abnormal chest X-ray findings were noticed in 38 cases. The male to female sex ratio of 48 RSV antigen positive cases was 1.2 : 1. The mean and range of age was $10.2{\pm}5.9$ and 1.0~24 months. The peak outbreak of cases was noticed on November, 1999. All of the cases shows coughing but rale was audible in 30 cases(60%). Dyspnea, wheezing, and intercostal retraction were noticed 11(23%), 15(31%), and 10(21%) cases respectively. The most common chest X-ray finding was scattered patch infiltration that was noticed in 30 cases(63%). The mean total white blood cell counts in peripheral blood was $12,608{\pm}4,686/mm^3$. The mean blood level of IgA and IgE were $50.8{\pm}20.9$ and $72.1{\pm}98.3mg/dL$ respectively. The C-reactive protein was $16.0{\pm}18.5mg/L$. Total 5 cases need a mechanical respiraton. The duration of admission was under 7 days in 36 cases(75%). Conclusion : The RSV antigen was detected commonly in late fall and winter season. The severity of children under 2 years old with RSV respiratory tract infection take in some degree a gave courses.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.275-281
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• 2018

It is known that he pollutant emitted from the combustion process of marine fuel oil causes air pollution and harmful effects to the human body. Accordingly, IMO regulates pollutants emitted from ships. However, the regulation of Particulate Matter (PM) is still in the process of debate, so preemptive action is needed. Fundamental research on PM is essential. In this study, the Dimensionless Light Extinction Constant ($K_e$) of fuel oil used in marine diesel engines was measured and analyzed to construct the basic data of the PM generated from marine-based fuel oil. The fuel oil used in the land diesel engine was measured in the same way for character comparison. Both fuel oils differ in sulfur content and density. The $K_e$ was measured via the optical method using a 633 nm laser and was determined by using the volume fraction of PM collected by the gravimetric filter method. The $K_e$ of the PM discharged from marine fuel oil is 8.28, and the land fuel oil is 8.44. The $K_e$ of two fuel oils was similar within the measurement uncertainty range. However, it was found by comparison with the value obtained by the Rayleigh-Limit solution that the light scattering portion could be large. Also, it was found that light extinction characteristics could be different due to the relationship between light transmittance and collected mass.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.9-17
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• 2010

The LCC (Liquid Cadmium Cathode) structure to be developed for inhibiting the formation and growth of the uranium dendrite has been known as a key part in the electrowinning process for the simultaneous recovering of uranium and TRU (TRans Uranium) elements from spent fuels. A zinc-gallium (Zn-Ga) experimental system which is able to be functional in aqueous condition and normal temperature has been set up to observe the formation and growth phenomena of the metal dendrites on liquid cathode. The growth of the zinc dendrites on the gallium cathode and the performance of the existing stirrer type and pounder type cathode structure were observed. Although the mechanical strength of the dendrites appeared to be weak in the electrolyte and easily crashed by the various cathode structures, it was difficult to effectively submerge the dendrite into the bottom of the liquid cathode. Based on the results of the aqueous phase experiments, a lab-scale electrowinning experimental apparatus which are applicable to the development of LCC srtucture for the electrowinning process was established and the performance tests of the different types of LCC structure were conducted to prohibit the uranium dendrite growth on LCC surface. The experimental results of the stirrer type LCC structures have shown that they could not effectively remove the uranium dendrites growing at the inner side of the LCC crucible and the performances of the paddle and harrow type LCC structure were similar. Therefore a mesh type LCC structure was developed to push down the uranium dendrites to the bottom of the LCC crucible growing on the LCC surface and at the inner side of the crucible. From the experimental results for the performance test of the mesh type LCC structure, the uranium was recovered over 5 wt% in cadmium without the growth of uranium dendrites. After completion of the experiments, solid precipitates of the bottom of the LCC crucible were identified as an intermetallic compound (UCd11) by the chemical analysis.

• Tuberculosis and Respiratory Diseases
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• v.45 no.4
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• pp.805-812
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• 1998

Background: Among the variety of opportunistic infections, pneumonia comprises the major morbidity in immunocompromised patients. Pneumocystis carnii pneumonia (PCP) and cytomegalovirus (CMV) pneumonia are common infectious illness of immunocompromised hosts. Although there are many reports regarding to the co-infection of PCP and CMV diagnosed by bronchoalveolar lavage (BAL) fluid examination, the effects of CMV co-infection on the outcome of PCP is still controversial. The purpose of this investigation is to evaluate the effects of CMV detected by BAL fluid examination on the clinical course of PCP in the immunocompromised patients other than human immunodeficiency virus infection. Method: Ten patients with PCP were enrolled and retrospective analysis of their medical records were done. HIV infected persons were excluded. The PCP was diagnosed by BAL fluid examination with Calcofluor-White staining. CMV was detected in BAL fluid by Shell-vial culture system. Chest radiographic findings were reviewed. We used Fisher's exact test and Mann-Whitney U test for statistical analysis of data. Results: The underlying disorders of patients were idiopathic pulmonary fibrosis (n=1), renal transplantation (n=4), necrotizing vasculitis (n=l), systemic lupus erythematosus (n=1), brain tumor (n=1), chronic myelogenous leukemia (n=1), unidentified (n=1). There were no difference in clinical course, APACHE III score, arterial blood gas analysis, white blood cell count, lymphocyte count, serum albumin concentration, chest radiographic findings and mortality between patients with PCP alone (n=4) and those with CMV co-infection (n=6). Univariate analysis regarding to the factors that associated with mortality of PCP were revealed that the application of mechanical ventilation (p=0.028), the level of APACHE III score (p=0.018) and serum albumin concentration (p=0.048) were related to the mortality of patients with PCP. Conclusion: The clinical course of PCP patients co-infected by CMV were not different from PCP only patients. Instead, accompanied respiratory failure, high APACHE III score and poor nutritional status were associated with poor outcome of PCP.

• Journal of Korean Home Economics Education Association
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• v.18 no.3 s.41
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• pp.41-60
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• 2006

The system of teaching culinary practice needs drastic modification to catch up with dietary life and education curriculum changes. To reflect such changes, it is necessary to instill a strong will and interest as well as educational environment improvement in teachers. In this sense, this study researched the teachers' stages of concerns, levels of use, innovation configuration, and intervention demands, based on the CBAM(Concerns Based Adoption Method) developed by Hord et. al. For the survey, 500 questionnaires sent by mail and 187 were analyzed by SPSS/win 10.0 program. The results are summarized as follows. 1) The teachers stages of concerns on culinary practice is assessed to be in the lowest level of perceptual stage, which indicates a state of indifference. 2) In terms of the levels of use, routine use was the highest, followed by refinement use, integrated use, research use, and reinvent use in descending order. Mechanical use posted the lowest level. Even though the stages of concern showed the beginning stage, the Level of use was relatively high. 3) About the innovation configuration, approximately 30% of the teachers were not accomodate the culinary practice referred to the 7th National Education Curriculum. 4) According to the intervention demands on culinary practice education, it was found that teachers generally wanted more interventions in every component. Among the intervention components, the highest demand was on the support for facility. Demand on the financing is the second highest. Teachers in the level of routine use demanded more information and materials supply and individual encouragement, but teachers in the level of preparation needed study opportunity for training on operation skills more.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.656-662
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• 2007

Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as $H_2$ supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). $H_2$ selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the $O_2/C$ ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was $672^{\circ}C$ and input power 1.1 kJ/L, the production of $H_2$ was maximized 41.1%. And $CH_4$ conversion rate, $H_2$ yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the $O_2/C$ ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, $235^{\circ}C$ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were $H_2$ 38%, CO<10 ppm, $N_2$ 36%, $CO_2$ 21% and $CH_4$ 4%.