Search results

South Korea's World Trade Organization membership requires the "Land of the Morning Calm" to liberalize its legal market. South Korea submitted its proposal for liberalization in the spring of 2003 and planned to begin opening its legal market in 2005. However, disagreements between South Korea and other World Trade Organization members over the scope of liberalization have led to a one-year negotiation period extension, pushing back the planned market opening to early 2007. The Korean Bar Association has strongly opposed liberalization, claiming that liberalization will lead to the foreign domination of South Korea's legal market. On the other hand, most South Korean and foreign businesses, as well as foreign lawyers, have suggested that such concerns are exaggerated and that the benefits from liberalization will far outweigh its harms. Indeed, legal market liberalization will not only benefit businesses and lawyers by improving legal services quality and lowering legal costs, but it will also promote South Korea's rise as an important financial hub in East Asia. This Comment asserts that despite the potential benefits, liberalization can only be successful if South Korea simultaneously implements proper legislative revisions, reforms enforcement and oversight mechanisms, and promotes domestic firm expansion and educational reform.

STATEMENT OF PROBLEM. Recently Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) has been introduced due to superior flexural strength and fracture toughness compared to other dental ceramic systems. Although zirconia has outstanding mechanical properties, the phenomenon of decrease in the life-time of zirconia resulted from degradation in flexural strength after low temperature aging has been reported. PURPOSE. The objective of this study was to investigate degradation of flexural strength of Y-TZP ceramics after various low temperature aging treatments and to evaluate the phase stability and micro-structural change after aging by using X-ray diffraction analysis and a scanning electron microscope (SEM). MATERIAL AND METHODS. Y-TZP blocks of Vita In-Ceram YZ (Vita Zahnfabrik, Bad Sa ¨ckingen, Germany) were prepared in 40 mm (length) x 4 mm (width) x 3 mm (height) samples. Specimens were artificially aged in distilled water by heattreatment at a temperature of 75, 100, 125, 150, 175, 200, and 225℃ for 10 hours, in order to induce the phase transformation at the surface. To measure the mechanical property, the specimens were subjected to a four-point bending test using a universal testing machine (Instron model 3365; Instron, Canton, Mass, USA). In addition, X-ray diffraction analysis (DMAX 2500; Rigaku, Tokyo, Japan) and SEM (Hitachi s4700; Jeol Ltd, Tokyo, Japan) were performed to estimate the phase transformation. The statistical analysis was done using SAS 9.1.3 (SAS institute, USA). The flexural strength data of the experimental groups were analyzed by one-way analysis of variance and to detect statistically significant differences (α= .05). RESULTS. The mean flexural strength of sintered Vita In-Ceram YZ without autoclaving was 798 MPa. When applied aging temperature at below 125℃ for 10 hours, the flexural strength of Vita In-Ceram YZ increased up to 1,161 MPa. However, at above 150℃, the flexural strength started to decrease. Although low temperature aging caused the tetragonal-to-monoclinic phase transformation related to temperature, the minimum flexural strength was above 700 MPa. CONCLUSION. The monoclinic phase started to appear after aging treatment above 100℃. With the higher aging temperature, the fraction of monoclinic phase increased. The ratio of monoclinic/tetragonal + monoclinic phase reached a plateau value, circa 75% above 175℃. The point of monoclinic concentration at which the flexural strength begins to decrease was between 12% and 54%. ; This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government(MOST) (No. R01-2007-000-10977-0).