We study substrate support structures and materials to improve uptime and shorten preventive maintenance cycles for chemical vapor deposition equipment. In order to improve the rolling of the substrate support, the bushing device adopts a ball transfer method in which a large ball and a small ball are mixed. When the main transfer ball of the bushing part of the substrate support contacts the substrate support, the small ball also rotates simultaneously with the rotation of the main ball, minimizing the resistance that can be generated during the vertical movement of the substrate support. As a result of the improvement, the glass substrate breakage rate is reduced by more than 90 ~ 95 %, and the equipment preventive maintenance and board support replacement cycles are extended four times or more, from once a month to more than four months, and the equipment uptime is at least 15 % improved. This study proposes an optimization method for substrate support structure and material improvement of chemical vapor deposition equipment.

To ensure the safety and functionality of a railroad bridge, maintaining the integrity of the bridge via continuous structural health monitoring is important. However, most structural integrity monitoring methods proposed to date are based on modal responses which require the extracting process and have limited availability. In this paper, the applicability of the existing damage identification method based on free-vibration reponses to time-domain deflection shapes due to moving train load is investigated. Since the proposed method directly utilizes the time-domain responses of the structure due to the moving vehicles, the extracting process for modal responses can be avoided, and the applicability of structural health evaluation can be enhanced. The feasibility of the presented method is verified via a numerical example of a simple plate girder bridge.

현행 국내법상 해안방제 기자재 확보 및 비치에 관한 규정은 없고, 또한 가상 최대오염사고를 대비하여 전국에서 사고지역에 동원해 야 하는 해안방제 기자재의 수량 또한 정해진 바가 없다. 해안방제 기자재 소요수량의 산정을 위해 Hebei Spirit호 오염사고시 소모 및 동원되었 던 자원의 양을 기준으로 최대오염사고 대비에 필요한 목표량을 산출하여 해안방제 기자재 확보를 위한 기초 자료로 활용되도록 제안한다.

In this study we conducted a material flow analysis (MFA) of the four major types of waste electrical and electronic equipment (WEEE), namely refrigerators, TV sets, washing machines, and air conditioners, based on the most reliable data available from the Eco-Assurance System, other governmental sources, the literature, a field survey, and interviews. A MFA of six major components, iron, copper, aluminum, plastics, precious metals, and rare metals was also conducted. The estimated total generation of WEEE in 2013 amounted to 401.8 thousand tons, of which 3.8% (or, approximately 5% including printed circuit boards) was exported and 55.0% was recycled. The collection by the formal take-back system occupied 34.6% of the total generation, from which 83.9% was recovered as valuables. The six major components amounted to 299.7 thousand tons, among which 89.8% of iron, 91.4% of copper, 56.0% of aluminum, 27.1% of plastics, 37.1% of precious metals, and 6.2% of rare metals were recovered. A high positive correlation was found between the amount of WEEE flowing into the private recycling business and its economic value. Since the recovery ratio in the private sector was estimated to be much lower, while the potential environmental impact was higher, an optimal strategy was identified to enhance the collection by the public sector. Providing economic incentives should be an effective means to encourage private collection through the formal take-back system.

Environmental regulations on the management of waste electrical and electronic equipments (WEEE) have been strengthened in many developed countries. Improper management and disposal of such waste, especially in informal sectors, may pose serious threats to the environment and human health. In Korea, there are very few available statistical data regarding distribution flow and treatment of WEEE in informal sectors (i.e., unreported private collection and recycling facilities). In order to provide additional measures related to proper management of WEEE, there is an urgent need for a quantitative material flow study on the amount of the waste found in the sectors. This can be achieved by conducting a statistical analysis of the flow of WEEE in the sectors and by drawing significant results and implications of such analysis. In this study, the relevant data were collected from literature review and a number of field site visits to informal private collection and recycling sites with survey in Daejoen Metropolitan City. Statistical analysis of the survey related to the distribution of WEEE in informal sectors was conducted to determine the quantitative flow of WEEE in the sectors. According to the results of this study, 3.38 kg/person/year were introduced into informal sectors in 2013, while 2.48 kg/ person/year was recycled in formal sectors in 2012. This study implies that there are significant amounts of WEEE that are present and processed in the sectors, which are not regulated by government. Small private collectors of WEEE in informal sectors received approximately 60.6 unit/month on average. The results of this statistical study indicate that there are no significant differences among the factors such as the amount of treatment, the number of employee, and the degree of dismantle process. However, there is significant difference among the WEEE category large home appliance, small-sized home appliance, and audio-video equipment. Further study may be warranted to focus the flow of WEEE in informal sectors in more large scale in order to accurately determine the final destination and disposal of such waste in the environment.