• 대한조선학회논문집
• /
• 제35권2호
• /
• pp.1-7
• /
• 1998

중형 고속어업지도선의 선형개발에 관한 연구를 조선대학교 회류수조에서 수행하였다. 현재 운항중인 같은 크기의 15노트 급 선형을 모선(CU-015)으로 하여 모선의 선도를 20노트 항주에 적합하도록 길이를 연장하고 선형을 변경하였으며, 고속화에 따른 선수 쇄파를 최소화 할 수 있는 선수선형 개발 및 고마력 기관에 적합한 충분한 용적을 유지하며 저항추진 성능을 향상시킬 수 있는 U-형 선미형상의 개발을 주로 수행하였다. 모선의 선형수정에 많은 제약이 있었으나 결과적으로 도출된 개발선형은 상당한 조파저항 감소의 효과가 있었다.

• 대한조선학회지
• /
• 제19권4호
• /
• pp.31-37
• /
• 1982

Developing a minimum wave resistance hull form which is satisfying the given requirements such as displacement and speed is one of the important problems in ship hydrodynamics. The theoretical approach conducted by Pien was successful in developing an optimized hull form, however, which can not be applied directly to practical hull form without manual lines fairing process. To avoid this difficulty, source distribution which arrived after the optimization was put into a fictitious restricted channel and as a result practicably modified hull form was derived by stream line tracing. The wave resistance of the hull thus obtained was calculated by solving the simplified integral equation suggested by Kan. The resistance at design point is almost same with that of the original hull which was represented by source distribution on the vertical rectangular center plane. It is therefore recommended to use the derived hull form for the hull which obtained after manual lines fairing process at Pienoid method. Further researches both in theory and experiment are necessary before this concept is put into practical application.

• Structural Engineering and Mechanics
• /
• 제38권2호
• /
• pp.157-169
• /
• 2011

In this paper the time-dependent closed-form static solution of the suspended pre-stressed biconcave and biconvex cable trusses with unmovable, movable and elastic or viscoelastic yielding supports subjected to various types of vertical load is presented. Irvine's forms of the deflections and the cable equations are modified because the effects of the rheological behaviour needed to be incorporated in them. The concrete cable equations in the form of the explicit relations are derived and presented. From a solution of a vertical equilibrium equation for a loaded cable truss with rheological properties, the additional vertical deflection as a time-function is determined. The time-dependent closed-form model serves to determine the time-dependent response, i.e., horizontal components of cable forces and deflection of the cable truss due to applied loading at the investigated time considering effects of elastic deformations, creep strains, temperature changes and elastic supports. Results obtained by the present closed-form solution are compared with those obtained by FEM. The derived time-dependent closed-form computational model is used for a time-dependent simulation-based reliability assessment of cable trusses as is described in the second part of this paper.

• Bulletin of the Korean Chemical Society
• /
• 제27권5호
• /
• pp.613-630
• /
• 2006

Nucleic acids are virtually omnipresent; they exist in every living being. These macromolecules constitute the most important genetic storage material: the genes. Genes are conserved throughout the evolution of all living beings; they are transmitted from the parents to their offspring. Many interdisciplinary research groups are interested in modifying nucleic acids for use in a wider variety of applications. These modified oligonucleotides are used in many diverse fields, including diagnostics, detection, and therapeutics. In this account, we summarize our research efforts related to modified nucleic acid systems. First, we discuss our syntheses of modified oligonucleotides containing fluorescent tags for use as molecular probes (molecular beacons) to detect single-nucleotide polymorphisim (SNP) in nucleic acids and to distinguish between the B and Z forms of DNA. We also describe our research efforts into oligonucleotides functionalized with steroid derivatives to enhance their cell permeability, and the synthesis of several calix[4]arene-oligonucleotide conjugates possessing the ability to form defined triplexes. In addition, we have performed systematic studies to have an understanding about the functional groups necessary for a given nucleoside to behave as an organo or hydrogelator. The aggregation properties of a number of nucleoside-based phospholipids have been examined in different solvents; some of these derivatives are potential candidates for use as nucleoside-based liposomes. Finally, we also describe our research efforts toward the preparation of isoxazole- and isoxazoline-containing nucleoside derivatives and the determination of their antiviral activities.

• 항공우주기술
• /
• 제3권1호
• /
• pp.179-187
• /
• 2004

본 논문에서는 여분의 관성센서 시스템의 고장 검출 및 분리를 위한 Modified SPRT 기법의 문제점을 분석하였고, Modified SPRT 기법의 문제점들을 해결한 Advanced SPRT 기법을 제안하였다. 관성센서 시스템을 대상으로 한 Modified SPRT 기법의 문제점은 패러티 벡터에 포함된 관성센서 오차 요인들과 패러티 벡터 요소들 간의 상관관계 영향에 의해 발생한다. 관성센서 오차 요인을 제거하기 위해 two-stage Kalman filter를 이용한 보상된 패러티 벡터를 제안하였고 패러티 요소들 간의 상관관계 영향을 줄이기 위해 제어된 패러티 벡터를 제안하였다. 그리고 제안된 두 패러티 벡터를 이용하여 Advanced SPRT 기법을 설계하였다. 여분의 관성센서 시스템을 대상으로 한 Advances SPRT 기법의 성능은 시뮬레이션을 통해 확인하였다.

• 대한치과보철학회지
• /
• 제42권2호
• /
• pp.125-132
• /
• 2004

Statements of problem: All ceramic fixed partial denture cores can be made by the slip casting method and the advanced alumina tape method. The fracture resistance of these core connector areas is relatively low. Purpose: The purpose of this study is to standardize the appropriate volumetric figure and location of the connectors in the alumina core fabricated in alumina tape to be used in fixed partial dentures by way of topology optimization. Material and method: A maxillary anterior three-unit bridge alumina core with teeth form and surrounding periodontal apparatus model was used to ultimately design the most structurally rigid form of the connector. Loadings from a $0^{\circ}$, $45^{\circ}$ and $60^{\circ}$ to the axis of each tooth were applied and analyzed with the 3-D finite element analysis method. Using the results from these experiments, the topology optimization was applied and the optimal reinforcement layout of connector was obtained and the detail shape in the fixed partial denture core was designed. Results: The modified prosthesis with the form of a bulk in the lower lingual surface of the connector in the event, reduced the stress concentration up to 20% in the 3-D FEA. Conclusion: The formation of a bulk in the lower lingual connector area of an alumina core for a fixed partial denture decreases the stress to a clinically favorable measure but does not harm the esthetic point of view. This result illustrates the possibility of clinical application of the modified form designed by the topology optimization method.

• 콘크리트학회논문집
• /
• 제17권3호
• /
• pp.411-418
• /
• 2005

본 연구에서는 MMA(methyl methacrylate)계 아크릴 라텍스를 모노머 비에 따라 합성 제조하고, 각각의 모노머 비와 폴리머 시멘트 비에 따라 폴리머시멘트 모르타르를 제작한 후, 방수성, 염화물 이온 침투 저항성, 그리고 중성화에 대한 실험을 통해 MMA계 아크릴 라텍스를 혼입한 폴리머시멘트 모르타르의 내구성을 파악하고자 하였다. 실험결과, 폴리머시멘트 모르타르의 방수성과 염화물 이온 침투 저항성은 폴리머의 종류보다는 폴리머시멘트 비에 따라 많은 영향을 받는 것으로 나타나고 있으며, 폴리머시멘트 비가 높을수록 그 저항성도 증진되었다. 또 폴리머시멘트 모르타르의 중성화에 대한 저항성은 폴리머의 종류와 폴리머시멘트 비에 따라 많은 차이를 나타내고 있으며, 보통 시멘트 모르타르에 비해 현저히 증가하는 것으로 나타났다. 모노머의 종류에 따라서는 MMA/BA를 모노머로 이용한 폴리머시멘트 모르타르가 MMA/EA를 모노머로 한 폴리머시멘트 모르타르에 비해 그 성능이 우수하게 나타났다. 특히 폴리머시멘트 모르타르의 중성화는 세공구조에 따라서도 많은 영향을 받는 것으로 나타났으며 폴리머의 자체 저항능력으로 인해 폴리머의 혼입량이 높을수록 중성화에 대한 저항성도 증진되는 것으로 나타났다. 따라서 연구결과 본 실험에서 합성제조한 MMA계 아크릴 라텍스를 이용하여 폴리머시멘트 모르타르를 제작할 경우, 방수성, 염화물 이온 침투 저항성, 그리고 중성화에 대한 저항성을 크게 향상시킬 수 있었다.

• 전기화학회지
• /
• 제3권2호
• /
• pp.76-80
• /
• 2000

Electrochemical oxidation of ethanol has been studied at nickel and $RuO_2-modified$ nickel electrodes in 1 M KOH using electrochemical impedance spectroscopy. Equivalent circuits have been worked out from simulation of impedance data to model oxidation of ethanol as well as the passivation of the electrode. The charge-transfer resistances for oxidation of these electrodes became smaller in the presence of ethanol than in its absence. The nickel substrate facilitated ethanol oxidation at $RuO_2-modified$ nickel electrodes. We also describe the Performance of nanosized electrocatalysts of the same composition in comparison to those of the bulk electrodes. The nanosized electrodes were obtained by electrode-positing the alloy from complexed form of these metal ions with fourth and fifth generation polyamidoamine dendrimers.

• 전자공학회논문지B
• /
• 제33B권3호
• /
• pp.186-192
• /
• 1996

A modified learning rule is introduced for the implementation of feedforward artificial neural networks with on-chip learning circuitry using standard analog CMOS technology. Learning rule, is modified form the EBP (error back propagation) rule which is one of the well-known learning rules for the feedforward rtificial neural nets(FANNs). The employed MEBP ( modified EBP) rule is well - suited for the hardware implementation of FANNs with on-chip learning rule. As a ynapse circuit, a four-quadrant vector-product linear multiplier is employed, whose input/output signals are given with voltage units. Two $2{\times}2{\times}1$ FANNs are implemented with the learning circuitry. The implemented FANN circuits have been simulatied with learning test patterns using the PSPICE circuit simulator and their results show correct learning functions.

• 한국세라믹학회지
• /
• 제36권7호
• /
• pp.685-690
• /
• 1999

Modified belite cement clinker containing $\alpha$'-C2S and C4A3 were syntehsized form the mixture of raw materials. $\alpha$'-C2S was stabilized at room temperature by adding borax. Properties of the clinker were charaterized with a XRD, SEM, TEM The additive effects of slag on the hydration properties were also estimated by measurement of compressive strength fluidity and heat evolution. The experimental results exhibited that the addition of slag to the belite cement improves the fluidity and early compressive strength due to the formation of ettringite and C-S-H. The compressive strengths of the mortar with 20% slag after 7, 90 days hydration were 212, 355 kgf/cm2 respectively.