• Korean Membrane Journal
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• 제6권1호
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• pp.37-43
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• 2004

Comb-type graft hydrogels composed of alginate and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to manifest rapid temperature and pH sensitivity. To appear the electro-sensitivity, the polyaniline, conducting polymer, was added into the matrix. The swelling kinetics and ratios were compared under the various compositions of polyaniline. The swelling behaviors revealed that conducting polymer/hydrogel composites could control the swelling ratio and kinetics. The addition of polyaniline in the matrix improved the thermal stability in comparison with that of the hydrogel without polyaniline. In temperature sensitivity, the adding the polyaniline into the matrix decreased the degree of change in the swelling ratio. The swelling ratios continuously increased with increasing pH values. The drug release rate from the hydrogel increased with the adding the polyaniline and the applying the direct voltage to the hydrogels.

• 전기의세계
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• 제25권2호
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• pp.100-106
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• 1976

A comparative study on thermal, static mechanical and dielectric characteristics were made over a temperature range of ca.20.deg.C to 320.deg.C and a frequency range of KHZ to MHZ band on low density polyethylene specimens crosslinked, respectively, by radiation and chemical method. The thermal property of both specimens shows that softening point appears to unchange by crosslinking, however, melting and liquidizing temperatures attain rapid increase at the imitiation of crosslinking. Mechanical properties show little difference to both specimens crosslinked by different method, further the behaviors were discussed in connection with the relaxation of molecular segments in amorphous phase. Dose dependent dielectric characteristics observed at ambient temperature under several fixed frequencies exhibit extremities at ca. 20 Mrad and the behaviors also were interpreted qualitatively by taking into consideration of dipole concentration change in amorphous phase together with the role of specimen geometry to the depth of oxidative layer. Observing frequency dependent dielectric characteristics, it was also proved that ionic conduction loss is appreciably greater in the specimen prepared by chemical method than that by radiation.

• 한국세라믹학회지
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• 제31권4호
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• pp.381-388
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• 1994

A new process which co-fires the low-firing-substrate and copper conductor was studied to achieve good bond strength and low sheet resistance of conductor. Cupric oxide is used as the precursor of conductive material in the new method and the firing atmosphere of the new process is changed sequently in air H2N2. The addition of cupric oxide and variations of firing atmosphere permited complete binder-burnout in comparison with the conventional method and contributed to the improvement of resistance and bonding behaviors. The potimum conditions of this experiment to obtain the satisfactory resistance and bond strength are as follows (binder-burnout temperature in air; 55$0^{\circ}C$, reducing temperature in H2; 40$0^{\circ}C$ for 30 min, ratio of copper and cupric oxide; 60:40~30:70 wt%). The bonding mechanism between the substrate and metal was explained by metal diffusion layer in the interface and the bond strength mainly depended on the stress caused by the difference of shrinkage and thermal expansion coefficient between the substrate and metal.

• Structural Engineering and Mechanics
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• 제48권3호
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• pp.415-434
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• 2013

This work is concerned with transverse vibrations of axially traveling nanobeams including strain gradient and thermal effects. The strain gradient elasticity theory and the temperature field are taken into consideration. A new higher-order differential equation of motion is derived from the variational principle and the corresponding higher-order non-classical boundary conditions including simple, clamped, cantilevered supports and their higher-order "offspring" are established. Effects of strain gradient nanoscale parameter, temperature change, shape parameter and axial traction on the natural frequencies are presented and discussed through some numerical examples. It is concluded that the factors mentioned above significantly influence the dynamic behaviors of an axially traveling nanobeam. In particular, the strain gradient effect tends to induce higher vibration frequencies as compared to an axially traveling macro beams based on the classical vibration theory without strain gradient effect.

• 대한기계학회논문집B
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• 제29권3호
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• pp.402-408
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• 2005

The instantaneous temperature behaviors on impinging plate in case of ultra high pressure have been measured and analyzed by using the instantaneous temperature probe and ultra high pressure injection equipment. The temperature drop was largest at P1 which is center of impinging spray and decreased with propagation of spray to the radius direction. The temperature drop was bigger in case of higher temperature of impinging plate. The temperature drop decreased with increase of injection pressure. But decreasing rate of temperature drop was slight over 2,500 bars. Therefore, it was predicted that the fuel evaporation versus the increase of injection pressure was maximum at around 2,500 bars.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권4호
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• pp.449-457
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• 2012

The program/erase (P/E) cyclic endurances including bias temperature instability (BTI) behaviors of Metal-$Al_2O_3$-Nitride-Oxide-Semiconductor (MANOS) memories are investigated in comparison with those of Semiconductor-Oxide-Nitride-Oxide-Semiconductor (SONOS) memories. In terms of BTI behaviors, the SONOS power-law exponent n is ~0.3 independent of the P/E cycle and the temperature in the case of programmed cell, and 0.36~0.66 sensitive to the temperature in case of erased cell. Physical mechanisms are observed with thermally activated $h^*$ diffusion-induced Si/$SiO_2$ interface trap ($N_{IT}$) curing and Poole-Frenkel emission of holes trapped in border trap in the bottom oxide ($N_{OT}$). In terms of the BTI behavior in MANOS memory cells, the power-law exponent is n=0.4~0.9 in the programmed cell and n=0.65~1.2 in the erased cell, which means that the power law is strong function of the number of P/E cycles, not of the temperature. Related mechanism is can be explained by the competition between the cycle-induced degradation of P/E efficiency and the temperature-controlled $h^*$ diffusion followed by $N_{IT}$ passivation.

• 폴리머
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• 제27권2호
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• pp.113-119
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• 2003

폴리(에틸렌 테레프탈레이트) (PET)의 열처리 조건들 즉, 상대 습도, 온도 그리고 시간 등에 따라 나타나는 PET의 열적 특성과 결정화 거동에 대해서 연구하였다. PET샘플에 열처리를 수행한 후 수분 함유량, 유리 전이온도($T_g$), 그리고 결정화 온도($T_{\propto}$) 등의 변화를 조사하였다. 그리고 열처리된 PET시편에 대해서 결정화를 시키고 결정화도에 따른 열변형 온도(HDT)를 측정하였다. 또한 사출 성형으로 제작된 PET샘플의 열처리 후 잔류 응력의 완화를 편광 필름을 통하여 조사하였다. 열처리 시의 상대 습도, 온도, 그리고 시간이 증가함에 따라 PET샘플 내의 수분 함유량은 최대 6000 ppm이상 까지 증가하였다. $T_g$와 $T_c$는 시편 내에 수분 함유량이 증가할수록 감소하였다. PET샘플의 결정화도는 수분의 함유량이 증가함에 따라 증가되었다. 그러나 같은 양의 수분 함량에서 결정화도는 열처리의 조건에 따라 다르게 나타났다. PET샘플 내의 잔류응력의 완화는 열처리 조건에 따라 다르게 나타났으며, PET샘플 내에 잔류 응력이 감소할수록 최대 결정화도는 증가하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2000년도 춘계학술발표회 초록집
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• pp.6-6
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• 2000

• 한국재료학회:학술대회논문집
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• 한국재료학회 1997년도 한국재료학회 추계학술발표회
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• pp.165-165
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• 1997

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2003년도 추계학술발표대회 요약집
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• pp.363.2-363.2
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• 2003