• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.858-865
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• 2009

Based on the proven feasibility of bottom ash and tire shred-soil mixtures as lightweight fill materials, tire shred-bottom ash mixtures were suggested as a new lightweight fill material to replace the conventional construction material with bottom ash. Therefore, we carried out the laboratory test, field compaction test and performance test of large scale embankment in order to evaluate their suitability for the use of lightweight fill materials in the before studies. We could verified that the ash, tire-shred and the mixture are able to be the useful materials as light fill materials. In this study, we estimated the long-term compressible settlements for 6 materials such as TA(Tire-Bottom Ash mixture), TBA(Tire-Bottom Ash<5mm) mixture, TWS(Tire-Weathered Soil mixture), Bottom Ash, Bottom Ash(<5mm), Weathered soils.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.1
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• pp.105-115
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• 2006

In this paper, we investigate the problem of minimizing average inventory costs subject to a fill rate constraint in a two-stage serial inventory model with a normally distributed demand. Fill rate is the fraction of demand that is satisfied immediately from on-hand inventory. We first find the lower bounds of base-stock levels in each node by using the exact base-stock level that satisfies a fill rate in a single node model proposed by Sobel. And then, we extensively analyze the system and show that the cost function is convex. Using such convexity and some other useful properties, we can easily find optimal base-stock levels numerically.

• Journal of dental hygiene science
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• v.23 no.2
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• pp.123-131
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• 2023

Background: As a restorative material used to treat dental caries, the light-curing type resin is widely used, but it has the disadvantage of polymerization shrinkage. The Bulk-Fill composite resin was developed to solve these shortcomings, but the existing research mainly focused on comparing the physical properties of a composite resin and a Bulk-Fill resin. A study on the light curing time and distance of the Bulk-Fill resin itself tend to be lacking. Methods: This study compares the surface microhardness of specimens prepared by varying the light curing time and distance of smart dentin replacement (SDR) as a flowable Bulk-Fill resin and Tetric N-ceram as a packable Bulk-Fill resin, and confirms the polymerization time and distance that becomes the optimum hardness. To determine the hardness of the specimen, it was measured using the Vickers Hardness Number (Matsuzawa MMT-X, Japan). Results: In SDR, the surface microhardness decreased as the distance increased in all time groups in the change distance from the curing tip. In the change of light curing time with respect to the distance from curing tip, the surface microhardness increased as the time increased. In Tetric N-ceram, the surface microharness showed no significant difference in the change of the distance of curing tip in the group of 20 and 60 second. But in the group of 10 and 40 seconds, decreased as the distance increased. The surface microharness increased as the light curing time increased in all distance groups. Conclusion: When using SDR and Tetric N-ceram in clinical practice, it is considered that as the distance from the polymerization reactor tip increases, a longer light curing time than the polymerization time recommended by the manufacturer is required.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.277-284
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• 2017

For passive power factor correction, the valley fill circuit approach is attractive for low power applications because of low cost, high efficiency, and simple circuit design. However, to vouch for the product quality, two dc-link capacitors in the valley fill circuit should be selected to withstand the peak rectified ac input voltage. The common mode (CM) and differential mode (DM) choke should be used to suppress the electromagnetic interference (EMI) noise, thereby resulting in large size volume product. This paper presents the practical design and implementation of a valley fill flyback converter with reduced dc link capacitors and EMI magnetic volumes. By using the proposed over voltage protection circuit, dc-link capacitors in the valley fill circuit can be selected to withstand half the peak rectified ac input voltage, and the proposed CM/DM choke can be successfully adopted. The proposed circuit effectiveness is shown by simulation and experimentally verified by a 78W prototype.

• Magazine of the Korean Society of Agricultural Engineers
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• v.12 no.4
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• pp.2090-2123
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• 1970

This paper is a report on the research of experimental model test of Andong Fill Dam, which has been planned by the Government of Korea as a project, of its over-flowing capacity in spillway, creation of minus pressure and structure of anti-water impulse in over-flow weir. Andong Fill Dam is one of the project of master development plant for water resources, locating at Nakdong River side of Korea, and is aimed to have a multi-purpose dam for flood-control, irrigation, water power, urban and industrial water supply. This dam is planned to erect in fill-dam type due to the improper soil foundation and condition for concrete dam. The refore for the proper and advantageous points, this is designed as center core fill dam. By a model minimized of Andong Fill Dam, held an experimental model test on water quentity of reservir, discharges of overflow part, low pressure and anti-water impulse of overflow part, which was conducted an experiment by flowing aspects through each section of spillway to find the changes of water pressure and that of water level, and corrected the section of each part in order to conduct a check on the creation of minus pressure not to be over acted to the allowable bundary of the section structure; and for the prevention of concentated scouring at the down stream side of flow.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.569-574
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• 1999

In Soft ground of south-western coast of our country necessity of marine indutrial complex and container facility has been remarkable. Site construction for habor facility is one of the most urgent problems. Consolidation of dredged fill has become important task. In addition, volume change of dredged fill should be examined carefully. This study dealt with consolidation of dredged fill by PCDDF and in order to secure trafficability of heavy equipment for surface treatment should be studied.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.915-920
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• 2000

The effectiveness of bottom ash on the slump flow, compressive strength of flowable fill is investigated in this study. This study was undertaken on the use of bottom ash as a fine aggregate in flowable fill. Bottom ash is combined with portland cement, fly ash, and water to flowable fill with slump flow(20~30cm). Four different level of bottom ash with fly ash contents, 25%, 50%, 75%, 100% are investigated. Laboratory test results conclude that the inclusion of bottom ash increases the demand for mixing water n obtaining the require slump flow.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.129-136
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• 1999

Several seismic design standards for fill dams adopted in Japan USA and Korea are reviewed in this study. The review on those standards is tried to provide a thinking way for a new seismic design standard which is urgently requested by the government I. e. the Ministry of Construction & Transportation and the Ministry of Science & Techniology. This study suggest that as a new seismic design standard of fill dam including concrete face rockfill dam(CFRD) the modified earthquake intensity method based on dynamic analysis be adopted in Korea while the dynamic analysis method should be used in evaluatiing the performance of fill dams precisely.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.427-434
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• 2016

The aim of this study was to compare the mechanical properties of high viscosity bulk-fill resin composites, $Filtek^{TM}$ Bulk Fill Posterior Restorative (FBF) and $Tetric^{(R)}$ N-Ceram Bulk Fill (TBF), with conventional composite ($Filtek^{TM}$ Z-350 XT, Z-350). The Vickers hardness test which indicates the degree of conversion was performed and the dye penetration test was performed to measure the microleakage which indicates polymerization shrinkage amount. To minimize experimental error, the standardized 3D-printed molds and the bovine teeth were used. Obtained data were analyzed by the Kruskal-Wallis test and Mann-Whitney test with the confidence interval of 95%. In the microhardness test within 1 hour of polymerization, lower surface of FBF and TBF showed significantly lower value than that of Z-350 (p < 0.05). But after 24 hours, the microhardness of FBF had increased and showed no significant difference with Z-350 (p > 0.05). In top and 2 mm depth surface, mean microhardness values were in the following order: Z-350 > FBF > TBF (p < 0.05). The mean microleakage value of TBF was significantly lower than others (p < 0.05). For clinical application of bulk-fill resin composites, caution for applying masticatory forces during 24 hours after polymerization is advised and further studies to decrease microleakage should be conducted.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.3
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• pp.184-193
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• 2016

Purpose: To evaluate marginal leakage of bulk fill flowable composite resin filling with different curing time by using microcomputed tomography technology. Materials and Methods: 30 previously extracted human molars were randomly divided into 6 groups based upon restorative system and different curing time. Class II cavities (vertical slot cavities) were prepared. An individual metallic matrix was used to build up the proximal wall. The SonicFill or SureFil SDR flow was inserted into the preparation by using 1 bulk increment, followed by light polymerization for different curing times. The different exposure times were 20, 40, and 60 seconds. All specimens were submitted to 5,000 thermal cycles for artificial aging. Micro-CT scanning was performed by using SkyScan 1272. One evaluator assessed microleakage of silver nitrated solution at the resin-dentin interface. The 3D image of each leakage around the restoration was reconstructed with CT-Analyser V.1.14.4. The leakage was analyzed with the Mann-Whitney test. Results: Significant differences were observed between the light curing times, but no significant differences were found between the bulk fill composite resins. Increasing in the photoactivation time resulted in greater microleakage in all the experimental groups. Those subjected to 60 seconds of light curing showed higher microleakage means than those exposed for 20 seconds and 40 seconds. Conclusion: Increasing the photoactivation time is factor that may increase marginal microlekage of the bulk fill composite resins. Further, micro-CT can nondestructively detect leakage around the resin composite restoration in three dimensions.