• The Journal of the Korean dental association
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• v.20 no.11 s.162
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• pp.945-966
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• 1982

• The Journal of the Korean dental association
• /
• v.18 no.3 s.132
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• pp.207-213
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• 1980

• The Journal of the Korean dental association
• /
• v.27 no.10 s.245
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• pp.910-912
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• 1989

• The Journal of the Acoustical Society of Korea
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• v.20 no.1
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• pp.62-67
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• 2001

Velocities of leaky surface acoustic waves (LSAW/sub s/) were measured by using a line-focus polyvinylidene fluoride (PVDF) transducer and compared with theoretically calculated ones. Isotropic materials of Cu, Al, fused quartz, and anisotropic one of Z-cut α-quartz crystal were used as specimens. The velocities were obtained by the separation time between wave components reflected directly from the surface of specimen and LSAW components according to the defocusing distance. The measured velocities well agree with the theoretical results within 1％ error, and it was shown that the leaky pseudo-surface acoustic wave (LPSAW) as well as the LSAW propagates with the typical 6-fold anisotropy on the (0,0,1) surface of α-quartz.

• The Journal of the Korean dental association
• /
• v.23 no.1 s.188
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• pp.45-60
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• 1985

• The Journal of the Korean dental association
• /
• v.35 no.4 s.335
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• pp.251-265
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• 1997

• The Journal of the Korean dental association
• /
• v.27 no.2 s.237
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• pp.161-169
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• 1989

• The Journal of the Korean dental association
• /
• v.24 no.3 s.202
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• pp.199-203
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• 1986

치과용 인상재는 구강내에서 치아나 주위조직을 정확히 인기하여야 하며 조작이 간편하고 유동성이 충분하며 경화시간이 적당하고 값도 저렴해야 한다. 또 구강내에서 제거할 때 영구변형이나 파절되지 않는 충분한 강도와 크기의 정확성도 있어야 하며 자극이나 독성이 없고 인체에 안정성이 있고 모형재와 친화성이 있으며 보관중에도 변질해서는 안된다. 그러나 인상재는 서로 상이한 특성이 있고 장단점이 각각 다르므로 모든 조건에 일치하는 인상재는 거의 없다. 따라서 여러 인상재중에서 가장 적합한 인상재를 선택하는 것이 중요한 과정이다. 즉 인상재의 특성과 응용을 알고 선택할땐 보다 정밀한 모형을 얻을 수 있다. 기록에 의하면 18~19세기경에 최초로 인상용 왁스를 사용한 이래 19세기 중엽에 인상용 석고, 1925년에 agar, 1930년 ZOE, 1945년 앨지네이트, 1957년 실리콘, 1967년 polyether 및 1975년 부가중합형 실리콘이 사용되었으며 인상재가 유연성과 탄성이 있는가 경고하며 비탄성인가 또는 온도변화와 화학반응으로 경화되는 가에 따라서 ZOE paste, 인상용 석고, 인상용 왁스, 인상용 콤파운드, 수성콜로이드(agar, 앨지네이트), polysulfide, 실리콘(축중합형, 부가중합형) 및 polyether 인상재등 10여종으로 분류된다.

• Geophysics and Geophysical Exploration
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• v.1 no.3
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• pp.183-187
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• 1998

Seismic waveform estimation is based on the assumption that the seismic trace tying a well is one dimensional convolution of the propagating seismic waveform and the reflectivity series derived from well logs (sonic and density). With this assumption, the waveform embedded in a seismic trace can be estimated using a Wiener match filter. In this paper, I experimented a preprocessing procedure that applies both on the seismic trace and on the reflectivity series. The procedure is based on the assumption that the travel time can be estimated better from the seismic trace and that the instantaneous reflectivity values can be measured better on the well log. Thus the procedure is, 1) start-time adjustment and dynamic differential stretches are applied on the sonic log, and 2) seismic amplitudes are balanced such that the low frequency part of the seismic are matched to that of the reflectivities derived from well logs.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.293-298
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• 2007

A new way to integrate various geophysical information for evaluation of RQD was developed. In this study, we does not directly define the RQD value where borehole data are not sampled. Instead, we infer the probability of RQD values with prior probability of data directly obtained from borehole, and secondary supporting probability from resistivity and seismic tomography data. First, we applied the geostatstical indicator kriging to get prior probability of RQD value, and indicator kriging with soft data to get the supporting probability from resistivity and seismic data. And we finally applied the permanence ratio rule to integrate these information. The finally obtained result was also analyzed to fully utilize the probabilistic features. For example, we showed the probability of wrongly classifying the RQD evaluation and vice versa. This kind of analytical result may be used for decision making process based on the geophysical exploration.