• 펄프종이기술
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• 제45권4호
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• pp.9-15
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• 2013

An oxidized starch ester was prepared and used for surface sizing. Esterification of starch decreased both Brookfield viscosity and Brabender viscosity substantially even though the solids level was increased by 2% from 14% to 16%. Surface sizing with the esterified starch gave better performance in tensile strength, stiffness and compressive strength than surface sizing with oxidized starch in the laboratory. Advantages in strength improvement, however, were not obtained when it was applied in commercial papermaking process. This was attributed to the fact that the influence of starch types has been nullified by high pressure penetration that occurs in the commercial papermaking process. Drying energy consumption, however, decreased by 3.3% by substituting the low solids oxidized starch with a high solids starch ester.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.443-448
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• 2014

Recently, car-ferry passenger ships of navigating the coast area in the inside of our country are on an increasing trend of main engine power and the height of upper structure, which is increased to ship's speed and loading of large vehicles. The most ship with high-speed main engine is happened to excessive vibration by propeller induced excitation force on account of connecting the vibration of hull's girder and the upper structure by decreasing the shear stiffness and natural frequency for increasing the height of passenger deck. In this paper, By exchanging the propeller of alteration the number of blades, it could be keep to ship's speed and it's decreased the vibration of hull part that is located passenger deck on the upper deck, which is identified by countermeasure of protection against vibration to procure the safety ship's navigation through measuring the vibration of hull structure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.336-342
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• 1997

In this paper, in order to analyze dynamic characteristics of automobile steering system consisting of many components, natural frequencies and transfer functions of each component and total system are found on FFT by experiments. Then, the data are transmitted to commercial package program, CADA-PC. By analyzing the data, the mode shape of each natural frequency and damping values are obtained. Also, the function of rubber coupling in column and telescoping effects on system are considered. C.A.E commercial program are used to compare with the results of experiments. For finite element modeling, I-DEAS is used. Data processing and post processing are operated on NASTRAN and XL, respectively. The ball-bearing and the linkage of shaft with column are modeled by spring elements. Stiffness is modified from the results of experiments. The results of those show close agreement. In the mode shape of total system, wheel mode is dominant at lower frequency while the column mode is main mode at higher . The role of rubber coupling in vibration isolation is clear on mode shape. Telescoping function makes natural frequency of column changed.

• 한국염색가공학회지
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• 제6권3호
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• pp.15-26
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• 1994

Cotton fabrics were treated with the cellulase which is an enzyme to decompose cellulose and its actional mechanism is known. The optimum condition of the cellulase to the cotton fabrics and the weight losses, tensile strengths of the treated cotton fabrics were also obtained. The cellulase performs a specific catalytic action on the ${\beta}-1$, 4-glucosidic bonds of the cellulose molecules and hydrolyzes them. For that reason, the negative surface charges of the cotton fabrics were increased by additional generation. of hyrdoxyl groups. The increased surface charges cause the decrease of dye adsorption by inhibiting the approach of the anions of direct dyes. But, it was overcome by the use of enough amount of salt, it means that sodium ions of the salt neutralize the almost all of negative charges of the cotton fabrics. The improvement of the water absorbency is also due to the increased hydroxyl groups In addition, their handles including the mechanical properties were measured and caculated by KES system which is a measuring apparatus that numerizes and objectificates human's feeling, especially touch. As the results, we knew that KOSH(stiffness) and FUKURAMI(fulness & softness) were decreased and that NUMERI(smoothness) was increased.

• 한국구조물진단유지관리공학회 논문집
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• 제12권6호
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• pp.225-232
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• 2008

본 논문에서는 FRP 보강재의 부착방식에 따른 RC보의 휨보강 성능평가에 대하여 연구하였다. 기존의 FRP 휨보강공법은 보강재의 형태에 따라 크게 FRP 쉬트 보강공법과 FRP 플레이트 보강공법으로 분류될 수 있으며, 각 공법은 에폭시의 양생기간동안 쉬트의 들뜸이 발생하지 않도록 주의해야하거나, 앵커설치 등 시공이 복잡하며, 인력이 많이 소요되는 단점이 있다. 이러한 문제점을 개선하기 위하여 본 논문에서는 Velcro형 고정재를 사용하여 FRP 플레이트를 임시 고정하는 보강공법을 제안하였고, 이에 대한 휨보강 성능평가 실험을 실시하였다. 실험은 FRP보강재의 부착방식을 변수로 하여 총 4개 실험체에 대하여 수행하였다. 실험결과 벨크로형 FRP판 보강공법은 타 공법에 비하여 우수한 시공성을 가짐과 동시에 휨내력이나 연성도 면에서도 우수한 보강성능을 확보하고 있는 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.888-895
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• 2009

Compaction is a process of increasing soil density using physical energy. It is intended to improve the strength and stiffness of soil. In embankment, degree of compaction affects the construction time, money, also method of soil improvement. In large scale embankment project, difficulties of embankment should change due to uncertainty of settlement. So it is very important to predict the final settlement and factor of safety induced by embankment. In many construction site, there are primarily design of high embankment using in-situ soil. Therefore numerical analyses are necessary for valid evaluation of the settlement prediction. But due to the construction cost and schedule, there were lacking in properties of soil and also limited number of in-situ test were performed. So we proposed the method that can easily estimate the proper soil parameters and suggest the proper method of numerical analysis. From this, two-dimensional finite-difference numerical analysis was conducted to investigate the settlement and factor of safety induced by embankment with various case of compaction rate and embankment height.

• 한국지반신소재학회논문집
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• 제9권3호
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• pp.67-75
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• 2010

본 연구에서는 생분해성 수지를 이용한 연직배수재에 대해 다양한 성능 평가방법을 적용하여 생분해성 플라스틱배수재의 공학적 특성을 분석하였다. 생분해성 플라스틱으로 제작한 연직배수재는 기존 합성수지 연직배수재에 비해 낮은 인장변형률을 가지며 상대적으로 낮은 인장강도를 갖지만, 연직배수재로서 가져야 할 최소한의 인장강도는 발휘하는 것으로 나타났다. 생분해성 플라스틱으로 제작한 필터는 투수성이 좋고 유효구멍크기가 작아 필터의 성능으로 매우 적합한 것으로 나타났다. 또한 생분해성플라스틱 배수재의 통수능은 필터의 강성을 개선하는 경우 국내 시방기준에도 만족할 수 있는 성능을 갖는 것으로 나타났다.

• Steel and Composite Structures
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• 제8권4호
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• pp.313-328
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• 2008

This study attempts to suggest bending reinforcement method by applying bending reinforcement to composite profile beam in which the concept of prefabrication is introduced. Profile use can be in place of framework and is effective in improvement of shear and bending strength and advantageous in long-term deflection. As a result of experiment, MPB-CB2 with improved module had higher strength and ductility than the previously published MPB-CB and MPB-LB. In case of bending reinforcement with deformed bar and built-up T-shape section based on MPB-CB2, the MPB-RB series reinforced with deformed bar were found to have higher initial stiffness, bending strength and ductility than the MPB-RT series. The less reinforcement effect of the MPB-RT series might be caused by poor concrete filling at the bottom of the built-up T-shape. In comparison between theoretical values and experimental values using minimum yield strength, the ratio between experimental value and theoretical value was shown to be 0.9 or higher except for MPB-RB16 and MPB-RT16 that have more reinforcement compared to the section, thus it is deemed that the reinforced modular composite profiled beam is highly applicable on the basis of minimum yield strength.

• 한국생산제조학회지
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• 제19권4호
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• pp.511-520
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• 2010

In general, spot welding is used at no welding rod or flux for the process, low welding point temperature compared to arc welding, short heating time, less damage to the parent material, and low deformation and residual stress, relatively. Also, because of the pressurization effect, better mechanical qualities of the welding parts are obtained. Therefore, in various fields of industry its rapid operation speed can make mass production possible such as motor industry. In FEM analysis for the spot welding process, it is effective to use simple modeling rather than complicated one because of its numerous number of spots and reduction of analysis time. Therefore, this study provides with not only simplification of modeling analysis by using beam component composition of structure without re-compositing the spot welding point mesh but also modeling analysis of which property of fracture strength is reflected. In addition complete spot welding model is examined at rectangular post shape (hat shape) by impact test, compared the results, and verified its validity. As a result, it is possible to optimize the welding position and to recognize the strength of structure and the proposed equal distance model shows the effect of welding point reduction and improvement of stiffness.

• Advances in aircraft and spacecraft science
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• 제2권3호
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• pp.303-328
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• 2015

A design methodology is presented to develop the hingeless control surfaces for MAV using adhesively bonded Macro Fiber Composite (MFC) actuators. These actuators have got the capability to deflect the trailing edge surfaces of the wing to attain the required maneuverability, besides achieving the set aerodynamic trim condition. A scheme involving design, analysis, fabrication and testing procedure has been adopted to realize the trailing edge morphing mechanism. The stiffness distribution of the composite MAV wing is tailored such that the induced deflection by piezoelectric actuation is approximately optimized. Through ground testing, the proposed concept has been demonstrated on a typical MAV structure. Electromechanical analysis is performed to evaluate the actuator performance and subsequently aeroelastic and 2D CFD analyses are carried out to see the functional requirements of wing trailing edge surfaces to behave as elevons. Efforts have been made to obtain the performance comparison of conventional control surfaces (elevons) with morphing wing trailing edge surfaces. A significant improvement in lift to drag ratio is noticed with morphed wing configuration in comparison to conventional wing. Further, it has been shown that the morphed wing trailing edge surfaces can be deployed as elevons for aerodynamic trim applications.