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The subsidence rate in a reclaimed coastal land has been estimated by using JERS-1 L-band SAR two-pass differential interferometry. Measurement of subsidence rate during reclamation is difficult to obtain as a two-dimensional subsidence map based on sparsely distributed field measurements is required. Owing to the severe temporal decorrelation induced by frequent soil loading and intense deformation gradients, the L-band was found to be effective for observing subsidence in reclaimed land. We evaluated the accuracy of the estimated subsidence rate using field measurements obtained by a magnetic probe extensometer from 42 ground stations. A two-dimensional subsidence map was generated from seven qualified pairs. The correlation coefficient R between the two-dimensional radar measurements and the in situ data was 0.87 with a rms error of 1.42 cm. Two interferometric pairs obtained from an adjoining JERS-1 path were also used to verify the results. Independent estimations from the two different JERS-1 paths correlated each other with correlation coefficients R of 0.97 and 0.80. The main sources of the error were the reference DEM errors and additional phase noises calculated from phase fluctuation at stable points. The error from these two sources was ¡1.27 cm. The estimated maximum subsidence was about 60 cm over 352 days. The results demonstrate that L-band differential SAR interferometry is a useful tool in geological engineering applications.

Apatite and zircon fission track (FT) analyses were carried out to reconstruct the thermal history of the Lower Cretaceous Sindong Group, which is the lowermost stratal unit of the Gyeongsang Basin, Korea. Zircon FT central ages show a wide range from 83 + 5 to 157 + 18 Ma, and single-grain age spectra have multiple age populations, whereas all apatites have very consistent FT ages of c. 60 Ma, suggesting a totally reset cooling age. Co-existence of both older and younger ages compared with the depositional age and relatively short mean track length indicate that the Sindong zircons were partially annealed. The Sindong Group was heated into the zircon partial annealing zone (ZPAZ) around 80 Ma, and cooled below the apatite closure temperature at c. 60 Ma. Based on the zircon FT results combined with vitrinite reflectance data, the maximum palaeotemperature to which the Sindong Group had been subjected can be inferred to be about 260 8C. Zircon FT data from a granite body that is in contact with the Sindong Group and sandstones close to the granite body indicate that thermal influence caused by Upper Cretaceous intrusive rocks was limited in close vicinity of the intrusion and that the major heat source of the Sindong Group was burial. The thickness of uplifted and eroded section is estimated to be about 7 km.

A series of poly(amide‐imide)s were prepared using a new monomer, 1,3‐bis(trimellitimido)‐2,4,6‐trimethyl benzene (BTB), with four different diamines: 1,4‐phenylene diamine (PDA), 2,4‐diamino mesitylene (DAM), 2,2′‐dimethyl‐4,4′‐diamino biphenyl (DMDB), and 2,2′‐bis(trifluoromethyl)‐4,4′‐diamino biphenyl (TFDB). They were prepared by the condensation method in N‐methyl‐2‐pyrrolidinone (NMP) solvent using triphenyl phosphate and pyridine as condensing agents. The synthesized poly(amide‐imide)s were characterized by Fourier transform infrared and 1H NMR techniques. Films were prepared and characterized using DSC, thermogravimetric analysis (TGA), a prism coupler, and a film dielectric property analyzer. DSC measurement showed that the glass‐transition temperatures of the polymers were in the range of 259–327 °C. TGA analysis showed 5% weight loss, in the range of 472–514 °C. The refractive index varied from 1.6004 to 1.6586 in the following increasing order: BTB‐TFBM < BTB‐DAM < BTB‐DMDB < BTB‐PDA. For the poly(amide‐imide) films, the birefringence varied in the range of 0.0319–0.0580, in the following increasing order: BTB‐DAM < BTB‐TFBM < BTB‐DMDB < BTB‐PDA. The capacitance method showed that the dielectric constant of poly(amide‐imide) varied with the diamine structure; no difference was found by the optical method. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 137–143, 2004