• 한국CDE학회논문집
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• 제12권6호
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• pp.461-465
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• 2007

There have been 3E problems of energy, economy and environment since the earth has its history. Especially, the energy and environment problems have been getting serious after the modem industry revolution. Therefore, the demand of gas as an eco-friendly energy source is getting increased. With the demand of gas, the installation and use of gas boiler is also increased, so human life injury by the waste gas(CO) of boiler goes on increasing every year. It is the content about a life of the exhaust tube which is used at Gas boiler in this paper. We explain also the course to apply the 6SC(6 Step Creativity)of practical TRIZ and evaluate the resolution.

• 한국전산유체공학회지
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• 제14권4호
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• pp.7-12
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• 2009

The purpose of the present study is to investigate the convective heat transfer characteristics and the validity of fin efficiency of the circular finned-tube heat exchanger by using commercial CFD code. The heat transfer coefficient obtained by using the laminar model was 22% overestimated to the experimental data. The fin surface temperature compared with the experimental data measured by the liquid crystal method. The fin efficiency by the present numerical experiment, defined as normalized and averaged fin surface temperature, was greater than the theoretical fin efficiency and the difference is increased at high value of the factor $mr{\phi}$.

• 기술사
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• 제30권3호
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• pp.43-51
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• 1997

Vacuum tubes are electron tubes in which the motion of electrons are utilized. There are many kinds of vacuum tubes, e.g. diode tubes, triode tubes, pentodes. muti-tubes and etc. Generally accommodated in glass tube, its eletrodes can be seen easily from outside and it easy to understand. In 1884 Edison discovered a current flow in the vacuum tube. He could not, however, explain this phenomenon. This is called Edison effect. In 1904 Fleming developed the backup for the practical diode theory. The most important milestone in this early history of electronics came in 1906 when De Forest put a third electrode (a grid) into the above, and thus invented the triode tube. It is 90 years since the triode was invented by De Forest (as of 1996) and 100 years (centennial also as of 1996) since the specific electric change e/mo$_0$ ≒ 1.7589 ${\times}$ 1011 (C/kg) was confirmed by the English scientist Thomson in 1896. On the occasion of the 90th and 100th anniversary of these inventions and discovery, E would like to describe the rise and 1111 of the vacuum tubes and the current status of these tubes.

• 소성∙가공
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• 제13권7호
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• pp.629-634
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• 2004

Based on plastic instability, analytical prediction of bursting failure on tube hydroforming processes under combined infernal pressure and independent axial feeding is carried out. Bursting is irrecoverable phenomenon due to local instability under excessive tensile stresses. In order to predict the bursting failure, three different classical necking criteria such as diffuse necking criterion for sheet and tube, local necking criterion for sheet are introduced. The incremental theory of plasticity for anisotropic material is adopted and then the hydroforming limit and bursting failure diagram with respect to axial feeding and hydraulic pressure are presented. In addition, the influences of the material properties such as anisotropy Parameter, strain hardening exponent and strength coefficient on bursting Pressure are investigated. As results of the above approach, the hydroforming limit in view of bursting failure is verified with experimental results.

• 대한기계학회논문집B
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• 제41권10호
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• pp.639-647
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• 2017

Solid SCR에 사용 가능한 암모니아 저장물질의 하나인 암모니움 카바메이트는 열 분해시 이산화탄소 가스와 암모니아 가스를 생성하며, 분해 온도인 $60^{\circ}C$ 이하에서 암모니움 염으로 재결합되는 단점이 있다. 이러한 재결합 현상을 극복하기 위하여, 희석기체인 압축공기를 이용하여 기초가시화 실험을 수행하였다. 또한, 재결합 현상을 계량화하기 위하여, 재결합 물질의 무게변화를 측정하기 위한 간단한 장치를 만들어 자동차환경에서 사용되는 SUS재질의 3가지 관경에 크기에 대한 상관관계를 검토하였다. 아크릴 튜브로 제작된 온도조절이 가능한 가시화 실험장치에, 암모니아 가스, 이산화탄소 가스, 희석기 체인 질소 가스를 공급하며, 재결합 방지를 위한 온도, 압력, 희석유량과의 관계를 고찰하고, Chapman-Enskog Theory에서 파생된 Diffusivity를 사용하여 재결합 조건을 유추할 수 있는 지표로 사용하고자 한다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.355.2-355
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• 1999

The spnng back phenomena occurring in the coiling process of a steam generator tube induces the dimensional inaccuracy and makes the coiling procedure difficult. In this research, an analytical model was developed to evaluate the amount of the spring back for SMART steam generator tubes. The model was developed on the basis of beam theory and elastic-perfectly plastic material property. This model was extended to consider the effect of plastic hardening and the effect of the tensile force on the spring back phenomena. Parametric studies were performed for various design variables of steam generator tubes in order to minimize the spring back in the design stage. A sensitivity analysis has shown that the low yield strength, the high elastic modulus, the small helix diameter, and the large tube diameter result in a small amount of the spring back. The amount of the spring back can be controlled by the selection of adequate design values in the basic design stage and reduced to an allowable limit by the application of the tensile force to the tube during the coiling process.rocess.

• 서비스연구
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• 제13권2호
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• pp.181-203
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• 2023

유튜브는 OTT와 개인방송 플랫폼의 특성을 모두 갖춘 하이브리드적 성격을 띠고 있다. 그러나, 이러한 하이브리드적 특성을, 특히 유료 채널멤버십의 맥락에서 조사한 선행연구는 제한적이다. 따라서, 본 연구에서는 소비가치이론과 선행연구를 바탕으로 유튜브 유료 채널멤버십과 관련된 소비가치 요인이 이용만족도와 지속이용의도에 미치는 영향을 검증하고자 한다. 구체적으로, 본 연구는 유튜브 유료 채널멤버십 맥락에서 인지된 네 가지 소비가치 요인(기능적 가치, 사회적 가치, 감정적 가치, 진귀적 가치)을 도출하고, 각 요인이 이용만족과 지속이용의도에 미치는 영향을 검증한 후, 이러한 관계에서 상황적 가치(유료 유튜브 멤버십 채널에서의 실시간 방송 시청경험)의 조절효과를 추가적으로 살펴보고자 한다. 데이터는 여러 유료 유튜브 채널멤버십에 가입한 한국 성인을 대상으로 온라인 설문조사를 통해 총 274부가 수집되었다. 구조방정식모델링 기법을 활용하여 연구모형을 검증한 결과, 네 가지 소비가치 요인이 모두 이용만족에 유의미한 영향을 미치며, 이용만족은 지속이용의도에 긍정적인 영향을 미치는 것으로 나타났다. 상황적 가치 또한, 기능적/감성적 가치와 이용만족 간의 관계와 이용만족과 지속이용의도 간의 관계를 유의하게 조절하는 것으로 조사되었다. 본 연구는 OTT와 개인방송 플랫폼의 특성을 모두 포괄하는 유튜브 채널 유료 멤버십에 초점을 맞춘 최초의 연구로서, 본 연구의 결과를 통해 개인방송 진행자 및 이해관계자들에게 시청자의 이용만족에 영향을 미치고 채널멤버십 가입 및 지속유지를 유도하는 동기부여 요인에 대한 인사이트를 제공할 수 있을 것으로 기대한다.

• Korea-Australia Rheology Journal
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• 제11권4호
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• pp.287-291
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• 1999

The tube model theory of entangled polymer presumes that the polymer chain holds its equilibrium contour length under certain conditions of flow; at times longer than a certain characteristic time, ${\tau}_k$, in the stress relaxation process following any flow history; in steady flow of rates smaller than ${{\tau}_k}^{-1}$; etc. Rheological phenomena associated with this presumption are discussed.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 요약집 춘계학술발표대회
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• pp.317.1-317.1
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• 2004

• Steel and Composite Structures
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• 제28권5호
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• pp.541-557
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• 2018

This paper presents the influence of carbon nanotubes (CNTs) waviness and aspect ratio on the vibrational behavior of functionally graded nanocomposite sandwich annular sector plates resting on two-parameter elastic foundations. The carbon nanotube-reinforced (CNTR) sandwich plate has smooth variation of CNT fraction along the thickness direction. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. Effects of CNT distribution, volume fraction, aspect ratio and waviness, and also effects of Pasternak's elastic foundation coefficients, sandwich plate thickness, face sheets thickness and plate aspect ratio are investigated on the free vibration of the sandwich plates with wavy CNT-reinforced face sheets. The study is carried out based on three-dimensional theory of elasticity and in contrary to two-dimensional theories, such as classical, the first- and the higher-order shear deformation plate theories, this approach does not neglect transverse normal deformations. The sandwich annular sector plate is assumed to be simply supported in the radial edges while any arbitrary boundary conditions are applied to the other two circular edges including simply supported, clamped and free.