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NaOH용액중에서 PET필름의 응력완화거동에 관한 연구
전한용,최영엽,임승순,Jeon, Han-Yong,Choe, Yeong-Yeop,Im, Seung-Sun 한국섬유공학회 1988 한국섬유공학회지 Vol.25 No.1
The relaxation behaviors of PET film in NaOH solution were investigated in view of chemorheology under the various temperatures and those of the film with draw ratio and temperatures were examined phenomenologically in relation to the decomposition effect of NaOH. As the experimental results, the initial relaxation stress was decreased and relaxation rates rfrb were increased with temperatures at constant draw ratio. The relaxation spectra were composed of box and wedge types distribution and the relaxation time t1,t2 from constitutive eq. were shifted to a shorter time side with temperatures.
전한용,장경호 한국섬유공학회 1998 한국섬유공학회지 Vol.35 No.6
Composite nonwovens were made by thermal bonding method to examine the validity as the construction materials from needle punched and spunbonded nonwovens. The effects of air permeability, number of layers, porosity and pore size on bonding temperatures were investigated. The air permeability of composite nonwovens was varied with the bonding temperatures. The variation of air permeability was dependent on the nonwoven to have more lower air permeability for 2-layer composite nonwovens. Air permeability of composite nonwovens was influenced by the number of layer. In case of the same weight for multi-layered nonwovens, air permeability coefficients were dependent on the porosity and thickness of nonwovens rather than the weight of nonwovens. Finally, the variation of air permeability of composite nonwovens by puncturing was dependent on the pore size rather than the number of puncture.
전한용,김진오 한국음향학회 2002 韓國音響學會誌 Vol.21 No.8
본 논문은 해석과 실험을 통하여 구형 압전 변환기의 점대칭 방사모드 진동 특성을 규명하는 것을 목적으로 한다. 반경 방향 좌표와 시간의 함수인 반경 방향 변위와 전기 퍼텐셜로 표현되는 지배방정식을 구성한다. 역학적 경계조건과 전기적 경계조건을 적용하여 방사 진동의 특성방정식을 유도한다. 이 식을 이용하여 압전 고유진동수를 계산하고, 그 결과를 측정 결과와 비교한다. 수치계산을 통하여 압전 공진과 탄성 공진의 차이, 구형 압전체의 반경 및 두께에 따른 고유진동수 등을 고찰한다. 그 결과 1차 방사모드의 고유진동수 크기는 압전현상으로 인해 작아지며 구형의 곡률 반지름이 커짐에 따라 지수함수적으로 작아지는 것을 알게 되었다. The object of this paper is to examine the vibration characteristics of the point-symmetric radial mode in a spherical piezoelectric transducer. The differential equations of piezoelectric radial motion are derived in terms of the radial displacement and electric potential, which are functions of the radial coordinate and time. Applying mechanical and electrical boundary conditions yields the characteristic equation of radial vibration. Numerical results of the natural frequencies are compared with the experimental measurements. The paper discusses the difference between piezoelectric and elastic resonances and the dependence of the natural frequencies on the radius and thickness of the piezoelectric spheres. As a result it is concluded for the first radial mode that the natural frequency is reduced due to the piezoelectric phenomenon and that the frequency exponentially decreases as the sphere radius increases.
Duplicated Geotextiles의 제조 및 내후성 평가
전한용 한국섬유공학회 2003 한국섬유공학회지 Vol.40 No.6
Duplicated geotextiles to improve the weatherability were made of recycled polyester (PET) geotextile with carbon black as ultraviolet stabilizer and polypropylene (PP) geotextile by needle-punching method. Their physical properties, ultraviolet resistance, and chemical stability of duplicated geotextiles were evaluated. Retention ratio of tensile properties of nonwoven polypropylene geotextiles decreased by about 50% on exposure to ultraviolet light, but those of geotextile composites were slightly decreased compared with polypropylene geotextiles. Duplicated geotextiles which have larger weights of polyester geotextile were more stable against ultraviolet light. The changes of tensile properties of geotextile composites were in the range of -20∼+10% under the various chemical conditions.
全漢容 혜전대학 1988 論文集 Vol.6 No.-
The validity of constitutive equations of 5-element mechanical model was examined as compared with the constitutive equations analyzed the stress relaxation behaviors of PET film for the initial and later relaxation process. In considering the effects of ions if draw ratio, ionic strength and ionic valance were constant, the smaller radii of ions are, the larger relaxation stress are since these ions will act on the chain segments of molecule as the effective ion.
전한용,목문성,조성호 한국섬유공학회 2002 한국섬유공학회지 Vol.39 No.4
The manufacturing processes and engineering properties of geocomposites, which were fabricated with two different functional geosynthetics; geotextile for separation and geogrid for reinforcement, were investigated. Geocomposites were manufactured using three different types of resins and one hot-melt adhesive type. Among them, EVA(ethylene vinyl acetate) showed the most excellent bonding effect. The mechanical and hydraulic properties of spunbonded geotextiles and geogrids were evaluated. The geocomposites manufactured in this experiment showed that the tensile strengths are increased, and the breaking strains are decreased. The EOS(effective opening size) and permittivity of the two different spunbonded geotextiles, used as the raw material in geocomposites, were also compared. The chemical resistance of the geocomposites in this experiment was deduced by comparing the tensile strength reduction under acidic and basic circumstances for four months. The results showed that tensile strength was reduced by less them two percentage.