• Nuclear Engineering and Technology
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• v.13 no.2
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• pp.73-84
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• 1981

B$\Phi$rrensen proposed a coarse mesh, three-dimensional one-and-half group diffusion scheme for computing the gross power distribution in light water reactors as an alternative to the conventional fine mesh finite difference approach in dealing with three dimensional problems, which require a prohibitively long computing time. The method reported takes extremely small execution time. However, its computational accuracy has not been investigated yet. The B$\Phi$rrensen method is revised in this work and both efficiency and accuracy are examined by applying it to IAEA benchmark problem and RIS$\Phi$ benchmark problem. It is found that two modifications on core-reflector boundary conditions and B$\Phi$rrensen's model constants may improve computational accuracy of power distribution calculation.

• The Journal of Society for e-Business Studies
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• v.4 no.3
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• pp.95-118
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• 1999

There have been many research papers and practical implementations on the various EC(Electronic Commerce) aspects such as merchant system, security, payment gateway, legal and policy issues. However, it is very hard to find the systematic approaches and business process models from the viewpoint of the company willing to start B2C(Business-To-Customer) EC. Therefore, we develop business process models for the planning, systems analysis and design, implementation, and operation of internet shopping mall to suggest a guideline and reference model for the realization of successful B2C EC.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.3
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• pp.39-46
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• 1994

In this paper, three types of parameter update law which can be used in model reference adaptive control are suggested based on speed-gradient algorithm which was introduced by Fradkov. It is shown that the parameter update law which was proposed by Narendra is a special from of these laws and that proposed parameter update laws can insure the global stability under some conditions such as attainability and convexity. We also comment that the transfer function of reference model shoud be positive real for the realization of parameter update law.

• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.3
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• pp.19-26
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• 1985

This paper deals with the representation and fairing of ship hull using a B-spline surface which is known as a 3-D model in computer aided free-form design. The first part of this paper is devoted to the fundamental concepts of B-spline theory and its geometrical characteristics. In its second part are described the facillities for efficient application, fast rendering of B-spline surface, and intersection of B-spline surfaces. The examples are presented with actual application to a real ship in the last part. And also a new concept of evaluating the surface fairness by the Gaussian curvature isolines is briefly discussed and its examples are presented.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.2
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• pp.385-402
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• 1996

The purpose of this study was to analyze how the stability of the implant prostheses and the loosening of the fastening screw was affected when the various types of Hex structure provided for the effect of anti-rotation of the single prostheses were given. Three dimensional finite element model was designed with which the implants with the external hex type of 0.75mm, 1.5mm and the implant with the internal hex type of 0.75mm, 1.5mm and the implant with the external hex type of $15^{\circ}$ tapered shape of 0.75mm were supposed to completely osseointegrate to the mandible. After fininshing the finite element model, the preload of 10N at the fastening screw was applied and then the vertical and $30^{\circ}$ lateral load of 200N was applied respectively at the cusp tips of the prostheses. The following results were obtained : 1. In case of displacement, the amount of displacement was increased at the internal hex type(model C, D) than at the external hex type(model A, B, E) when the vertical and lateral load was applied. 2. Less equivalent stress was represented at the model B with increased external hex height than at the model A when the vertical and lateral load was applied. 3. Much stress was represented at the model E with increased hex angle than at the model A in case of the stress happened to the implant body and the fastening screw when the vertical and lateral load was applied. 4. Much equivalent stress was represented at the model D with deepened internal hex height than at the model C when vertical and lateral load was applied. 5. The least stress was taken at the model B and the most stress was taken at the model D in case of the stress happened to the implant when the vertical and lateral load was applied. 6. The least stress was taken at the model C at the vertical load. And the least stress was taken at the model B at lateral load in case of the stress happened to the fastening screw. As a results of this study, the good lateral stability of prostheses and less stress of the component of implant was taken when the external hex height was increased, and the risk of neck fracture of implant and fastening screw was increased when the internal hex height was deepned because of long screw neck portion and thin implant neck portion.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.1
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• pp.87-99
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• 1993

Many studies have been reported on the successful replacement of missing teeth with osseointegrated dental Implants. However, little research has been carried out on the bio-mechanical aspect of the stress on the surrounding bone of the free-standing type of dental implant prostheses. This experimental study was aimed to analyze the stress distribution pattern on the supporting tissues depending upon the position of osseointegrated implants supporting fixed bridges. In the cases of unilateral partially edentulous mandible (the 2nd premolar and the 1st and 2nd molars missing), two osseointegrated implants were placed at the 2nd premolar and 2nd molar sites (Model A) , the 1st and 2nd molar sites (Model B, Anterior cantilevered type), the 2nd premolar and 1st molar sites (Model C, Posterior cantilevered type). Chewing forces of dentate patients and denture wearer were applied vertically on the 2nd premolar, the 1st molar, and the 2nd molar of each model. A 3-Unit fixed partial denture was constructed at each model and cantilevered extension parts were involved in Model B and Model C. Two dimensional finite element analysis was undertaken. The commercial software (Super SAP) for IBM 16 bit personal computer was utilized. The results were as follows : 1. The magnitude of applied load influenced on the total value of stresses, but did not in-fluence on the pattern of stress distribution. 2. The magnitude of stress developed from the supporting tissues were in order of Model C,Model A,Model B. 3. High stresses were concentrated on the cervical and apical portion of the implant/bone interface. 4. A difference of the stress magnitude on the implant/bone interface between mesial and distal implant was most prominant in Model C and in order of Model A and Model B. 5. The stresses developed in Model A were evenly distributed throughout both implants. 6. The stresses concentrated on the cervical portion of cantilevered side were higher in the posterior cantilevered type than in the anterior cantilevered type.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.3
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• pp.496-505
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• 1998

The purpose of this study was to evalute the effect of immersion disinfection on the dimensional stability of rubber impression materials. The metallic master model was made in order to simulate the intraoral arch form. Impressions were made from four impression materials (Exaflex, Extrude, Reprosil, Impregum-F) and immersed in three disinfectant solutions (Wydex, Vi-Pon, Potadine). Casts from the impressions were measured according to the interpreparation distance. The A-B and The B-D abutment distance were compared with the control group and disinfected groups. The results were as follows; 1. The measurements of the stone cast increased relative to the master model and there was a significant difference (P<0.05). 2. The relative dimensional change of the stone cast as compared with master model ranged from 0.10% to 0.56% in the A-B distance and ranged from 0.04% to 0.27% in the B-D distance. 3. The dimensional change of the disinfected groups as compared with the control group was significantly different in the three impression materials except for Impregum-F (P<0.05). 4. The relative dimensional change of the disinfected groups compared with the control group ranged from 0% to 0.20% in the A-B distance and ranged from -0.09% to 0.11% in the B-D distance. These results suggest that immersion disinfection of rubber impression materials by chemical disinfectants causes very small dimensional change and the change is clinically acceptable for prothesis fabrication

• 대한예방의학회:학술대회논문집
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• 1994.02a
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• pp.577-584
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• 1994

The relation between lead in air (PbA) and lead in blood (PbB), concentrations was investigated among 44 workers in five major operations in a United States high volume, lead acid battery plant. The study covered a 30 month period in which workers received frequent PbA and PbB determinations, workers remained in a single job, and PbA concentrations averaged below the US Occupational Safety and Health Administration (OSHA) permissible exposure limit of $50{\mu}g/m^{3}$. In both univariate and multivariable linear regressions, longitudinal analyses averaging PbA concentrations over the 30 month study period appeared superior to cross sectional analyses using only six month PbA averages .to model PbB concentrations. The covariate adjusted coefficient ($\alpha$ value) for PbA($\mu/m^{3}$) in models of PbB (${\mu}g/100\;g$) was 1-14. This figure is strikingly higher than that reported in previous studies in the lead acid battery industry in all of which PbA concentrations were substantially higher than in the current study. Plausible explanations for the differences in a: values include non-linearity of the PbA-PbB curve, a higher fraction of large size particulate associated with higher PbA concentrations, survivor bias among workers exposed to higher PbA concentrations, and the cross sectional designs of most previous studies. Despite previously reported problems with the model used by OSHA to predict PbA-PbB relations, the findings of this study are in good agreement with the predictions of that model.

• Archives of Pharmacal Research
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• v.28 no.12
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• pp.1350-1357
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• 2005

Nuclear factor kappa B (NF-$\kappa$B) regulates the expression of multiple cytokines, chemokines, and cell adhesion molecules that are involved in the pathogenesis of asthma. We investigated the anti-asthmatic effects and the mechanism of action of DA-9201, an extract of the black rice, in a mouse model of asthma. Mice immunized with ovalbumin (OVA) were administered with DA-9201 (30, 100 or 300 mg/kg) or dexamethasone (DEXA, 3 mg/kg) for 2 weeks and challenged with aerosolized OVA during the last 3 days. Anti-asthmatic effects were assessed by means of enhanced pauses, level of total lgE and Th2 cytokines in plasma or bronchoalveolar lavage fluid (BALF), the percentage of eosinophils in BALF, and histopathological examination. The expression of NF-$\kappa$B in nuclear and cytoplasmic fraction and its DNA-binding activity in lung tissues were analyzed by means of Western blotting and electrophoretic gel mobility shift assay (EMSA), respectively. DA-9201 significantly reduced airway hyperrespon-siveness (AHR), total lgE level in plasma and BALF, IL-4, IL-5, and IL-13 levels in BALF, and the percentage of eosinophils in BALF. Tissue inflammation was significantly improved by DA­9201 treatment. In addition, DA-9201 dramatically suppressed the expression of NF-$\kappa$B and its DNA-binding activity. These results suggest that DA-9201 may be useful for the treatment of asthma and its efficacy is related to suppression of NF-$\kappa$B pathway.

• 한국벤처창업학회:학술대회논문집
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• 2023.11a
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• pp.117-121
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• 2023

본 연구는 B2B (business-to-business) 비즈니스 모델 혁신(business model innovation, BMI)이 B2C (business-to-consumer) 비즈니스 모델 혁신 대비 혁신성과에 미치는 상대적 효과를 실증적으로 검증하고자 한다. BMI의 하위요인을 가치창출(value creation), 가치제안(value proposition), 가치획득(value capture)으로 나누어 각각의 요인 간의 관계를 구체적으로 분석한다. 본 연구는 실증분석을 위해 2022년 기업가정신 실태조사(기업편) DB의 3,120개 기업을 활용하였다. 분석 결과, BMI 중 가치창출은 B2B (vs. B2C) 혁신성과에 미치는 영향이 더 크며 유의한 것으로 나타났다. 반면 가치제안은 B2C (vs. B2B) 혁신성과에 미치는 영향이 더 크며 유의한 것으로 나타났다. 본 연구의 결과를 통해 주 비지니스 대상에 따라 BMI가 혁신성과에 상이한 영향을 미친다는 것을 실증했다는 점에서 학술적 의의가 있으며, 기업 특성에 따른 차별화된 BMI를 추구하는 것이 중요하다는 실무적 시사점을 가진다.