• 대한치과보철학회지
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• 제25권1호
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• pp.161-179
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• 1987

To study the mechanical behaviors of the margins of porcelain-fused-to-metal crown on the posterior teeth, 5 types of margins on the lower first molar were chosen, and then the finite element models were constructed. 50kg forces were applied to the porcelain on the axial wall supported by the metal vertically. The displacements and stresses of the porcelain-fused-to-metal crown were analyzed to investigate the influence of the type of margins. The results were as follows; 1. High tensile stresses were exhibited on the porcelain of the portion of the coronal line angle insufficient metallic support. 2. In case metal coping had a good supporting form to vertical force, uniform compressive stresses were exhibited on their supporting form. 3. Tensile stresses in the inframetallic margin on the series of the shoulder with a bevel margins were decreased in the bevel portion. 4. Principal stresses on the metal of the chamfer marginal portion were decreased comparing with the series of the shoulder margins. 5. The noticeable compressive stress gradients were exhibited between axial cement layer and metal on the series of the shoulder margins. 6. The principal stresses on the marginal cement layer were higher than that of the occlusal surface and axial wall.

• Advances in concrete construction
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• 제9권6호
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• pp.557-568
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• 2020

In this study, the impact of ring supports around the shell circumferential has been examined for their various positions along the shell axial length using Rayleigh-Ritz formulation. These shells are stiffened by rings in the tangential direction. For isotropic materials, the physical properties are same everywhere where the laminated and functionally graded materials, they vary from point to point. Here the shell material has been taken as functionally graded material. The influence of the ring supports is investigated at various positions. These variations have been plotted against the locations of ring supports for three values of length-to-diameter ratios. Effect of ring supports with middle layer thickness is presented using the Rayleigh-Ritz procedure with three different conditions. The influence of the positions of ring supports for clamped-clamped is more visible than simply supported and clamped-free end conditions. The frequency first increases and gain maximum value in the midway of the shell length and then lowers down. The Lagrangian functional is created by adding the energy expressions for the shell and rings. The axial modal deformations are approximated by making use of the beam functions. The comparisons of frequencies have been made for efficiency and robustness for the present numerical procedure. Throughout the computation, it is observed that the frequency behavior for the boundary conditions follow as; clamped-clamped, simply supported-simply supported frequency curves are higher than that of clamped-simply curves. To generate the fundamental natural frequencies and for better accuracy and effectiveness, the computer software MATLAB is used.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.66-69
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• 2008

IP계층에서의 이동성 지원에 대한 연구가 활발히 진행되어 IETF에서 MIPv6에 대한 표준화가 진행되었다. MIPv6는 이동 노드가 망과 망 사이를 이동할 때, 서비스에 대한 연결성을 유지하여 끊김 없는 통신을 가능하게 해주며, 이러한 방법을 핸드오버라고 한다. IEEE 802.21에서는 MIH(Media Independent Handover)라는 끊김 없는 핸드오버를 위한 방법을 표준화했다. MIH는 하위 레이어와 상위 레이어에서의 핸드오버를 위해 세 가지 서비스를 사용하였으며, 본 논문에서는 기존의 MIH에 두 가지 모드를 적용하여 네트워크 시뮬레이터에서 듀얼 모바일 호스트와 싱글 모바일 호스트의 성능 평가를 수행하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문 발표회
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• pp.107-111
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• 2003

The need for this study must be considerable, as being activate of green roofs research that the organization and construction obtain access to more development technologies. Nevertheless, the green roofs system has begun to apply since 1980's, the green roofs technology was restricted to develop without verification of technologies such as a load or water leakage. There is a limit as urethane waterproofing to almost domestic waterproofing materials and methods of construction for general green roofs. The introduction of materials and methods of construction which are appropriated to property of green roofs could be a decisive factor in a long-range durability and economical maintenance cost, moreover, it support to variety construction system and organization. This present paper describes a necessity of waterproofing and root barrier system is one of the sub-organization based on green roofs construction, which have enormously large impact on the durability.

• 정보처리학회논문지C
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• 제10C권1호
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• pp.1-10
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• 2003

본 논문에서는 취약점 검색공격 탐지시스템 DS-NVSA(Detection System of Network Vulnerability Scan Attacks)에서 서버와 에이전트들 사이의 상호연동을 위한 안전한 통신 프레임워크를 제안한다. 기존 시스템과의 상호연동을 위하여 제안 프레임워크는 IETF의 IDWG에서 제안한 IDMEF와 IAP를 확장 적용하였다. 또한 공개키 기반의 환경을 지원하지 못하는 네트워크 시스템을 위해 대칭키 기반의 암호화 통신 프로토콜 SKTLS(Symmetric Key based Transport Layer Security Protocol)를 제시하였다. 제안된 프레임워크는 DS-NVSA 이외에도 기존의 이기종 침입탐지 시스템의 제사용과 탐지 영역의 확대를 제공하며, 또한 기업내 통합 보안환경시스템 ESM(Enterprise Security Management) 시스템에도 적용될 수 있다.

• 멤브레인
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• 제19권3호
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• pp.212-221
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• 2009

본 연구는 PVDF/PDMS 복합막을 제조하여 부탄올을 농축을 위한 투과증발특성에 대해 알아보았다. 또한 복합막의 제조 방법에 따른 투과특성을 알아보기 위해 지지층의 PVDF 농도변화와 활성층의 경화조건에 따라 투과증발 최적막을 선정하였다. 이 막을 사용하여 공급액의 농도, 온도 및 순환 유속을 변화시켜 부탄올의 투과특성에 미치는 영향에 대해 알아보았다. 그 결과 공급액의 농도, 온도, 순환 유속이 증가할 경우 부탄올의 플럭스와 투과 농도가 증가함을 확인하였으며 상용막인 GKSS사의 PVDF/POMS 복합막과 비교한 결과 부탄올 투과 플럭스, 투과 농도, 선택도 등 모두 높은 값을 나타내었다.

• 한국분말재료학회지
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• 제23권2호
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• pp.149-169
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• 2016

Additive manufacturing (AM) is defined as the manufacture of three-dimensional tangible products by additively consolidating two-dimensional patterns layer by layer. In this review, we introduce four fundamental conceptual pillars that support AM technology: the bottom-up manufacturing factor, computer-aided manufacturing factor, distributed manufacturing factor, and eliminated manufacturing factor. All the conceptual factors work together; however, business strategy and technology optimization will vary according to the main factor that we emphasize. In parallel to the manufacturing paradigm shift toward mass personalization, manufacturing industrial ecology evolves to achieve competitiveness in economics of scope. AM technology is indeed a potent candidate manufacturing technology for satisfying volatile and customized markets. From the viewpoint of the innovation technology adoption cycle, various pros and cons of AM technology themselves prove that it is an innovative technology, in particular a disruptive innovation in manufacturing technology, as powder technology was when ingot metallurgy was dominant. Chasms related to the AM technology adoption cycle and efforts to cross the chasms are considered.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.3789-3809
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• 2014

Radio environment maps (REMs) and geolocation database represent an important source of information for the operation of cognitive radio networks, replacing or complementing spectrum sensing information. This paper provides a survey of methods for constructing the radio frequency layer of radio environment map (RF-REM) using distributed measurements of the signal levels at a given frequency in space and time. The signal level measurements can be obtained from fixed or mobile devices capable of sensing radio environment and sending this information to the REM. The signal measurements are complemented with information already stored in different REM content layers. The combined information is applied for estimation of the RF-REM layer. The RF-REM construction methods are compared, and their advantages and disadvantages with respect to the spatial distribution of signal measurements and computational complexity is given. This survey also indicates possible directions of further research in indirect RF-REM construction methods. It emphasizes that accurate RF-REM construction methods should in the best case support operation with random and clustered signal measurements, their operation should not be affected by measurements outliers, and it must estimate signal levels comparably on all RF-REM locations with moderate computational effort.

• Structural Engineering and Mechanics
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• 제37권3호
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• pp.309-320
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• 2011

As a new type of large-span space structure, suspendome is composited of the upper single-layer reticulated shell and the lower cable-strut system. It has better mechanical properties compared to single-layer reticulated shell, and the overall stiffness of suspendome structure increases greatly due to the prestress of cable. Consequently, it can cross a larger span reasonably, economically and grandly with high rigidity, good stability and simple construction. For a better assessment of the advantages of mechanical characteristic of suspendome quantitatively, the static behavior of Kiewitt6 suspendome was studied by using finite element method, and ADINA was the software application to implement the analysis. By studying a certain suspendome, the internal forces, deformation and support constrained forces of the structure were obtained in this paper. Furthermore, the influences of parameters including prestress, stay bar length, cross-sectional area and rise-to-span ratio were also discussed. The results show that the increase of prestress and vertical stay bar length can improve the stiffness of suspendome; Cross-sectional area has nearly no impact on the static behavior, and the rise-to-span ratio is the most sensitive parameter.

• 약학회지
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• 제26권4호
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• pp.223-229
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• 1982

Uremia is associated with defective protein binding of weakly acidic drugs, whereas the protein binding of basic drugs tends to be normal. The exact chemical nature of compound(s) and mechanism for these changes as yet is unknown, and has not been defined. Organic solvent extraction of pooled normal human urine following hydrolysis by hydrochloric acid produced an extract, which when added to normal human serum, was capable of inducing binding defects similar to those in uremia. Binding defects were observed with the weakly acidic drugs such as nafcillin, salicylate, sulfamethoxazole and phenytoin while the binding of the basic drugs such as trimethoprim and quinidine were unaffected. The binding defects induced by the hydrolyzed urine extract could readily be corrected by same organic solvent extraction of acidified serum and the defects could be transferred to the normal human serum using the organic solvent layer at the physiologic pH (7.4). Followed by reacidification ind extraction of the binding defects induced serum with the same solvent, separated several fractions were obtained on thin-layer chromatography. One of these fractions could reinduce the binding defects and this factor(s) is apparently weakly acidic compounds and tightly bound to serum at physiologic pH, but extractable at acidic pH, and its molecular weight range is approximately 500 or less similar to those seen in uremia. These findings strongly support the hypothesis that the drug binding defect in uremia is due to the accumulation of endogenous metabolic products which arc normally excreted by the kidneys but accumulate in renal failure.