• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.2
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• pp.151-157
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• 2022

In this paper, the performance of various blockchain consensus algorithms was compared and analyzed as a method to increase the transaction cost and processing time during NFT transactions and to increase the transaction stability requirements that occur during smart contract execution. Network reliability and TPS are evaluation items for performance comparison. TPS and the stability of the Consensus algorithm are presented for three evaluation items. In order to establish a standardized expression for each evaluation item, the reliability of the node and the success rate of the smart contract were considered as variables in the calculation formula, and the performance of the consensus algorithm of the three groups, PoW/PoS, Paxos/Raft and PBFT, was compared under the same conditions. / analyzed. As a result of the performance evaluation, the network reliability of the three groups was similar, and in the case of the remaining two evaluation items, it was analyzed that the PBFT consensus algorithm was superior to other consensus algorithms. Through the performance evaluation equations and results of this study, it was analyzed that when the PBFT consensus processing process is reflected in the consensus process, the network reliability can be guaranteed and the stability and economic efficiency of the consensus algorithm can be increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3794-3801
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• 2010

This study evaluated the linear dimensional changes with the factor of time and thickness using of three commercially available tissue conditioners (Coe-Comport, Visco-Gel, Soft-Liner). The thickness of materials were changed (1.5mm, 3.0mm) and the percentage changes in dimension were measured at 1h(baseline), 12h, 24h, 3 days and 7days after specimen preparation. The obtained data were analyzed by ANOVA with the SAS/PC statistical package. From the results, large differences appear between the various tissue conditioners. The results suggested that the period recommended for forming functional impression would be 36h to 3days after insertion in the mouth. Depending on the type of tissue conditioner over time, as there were significant differences in the elastic change(p<0.05). Tissue conditioner of the 1.5mm, 3.0mm thickness were significantly different by the dimensional stability(p<0.05). Elastic deformation of the ideal itself, and resilient when compared only the look, Visco-Gel 3.0mm group, stability was the most stable volume. In addition, it is important to select tissue conditioners suitable for functional impression because of the wide range of dimensional stability among the materials.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.378-378
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• 2011

본 연구에서는 ZnO 나노선 기판을 제작하여 그 위에 밴드갭이 낮은 물질인 CdS, CdSe를 증착시킨 후 p-type 반도체 물질인 CuSCN을 증착시켜 안정성이 향상된 양자점 감응형 태양전지를 제작하였다. ZnO 나노선 기판은 투명한 FTO 기판 위에 ZnO를 진공증착시켜 seed layer를 제작하고 그 위에 $10{\mu}m$정도의 길이의 나노와이어를 성장시킨 후, 밴드갭이 낮은 CdS, CdSe 물질과의 다중접합을 이용하여 제작하고, 이러한 나노선 구조위에 chemical solution deposition을 이용하여 ${\beta}$-CuSCN을 형성시켰다. 양자점 감응형 태양전지는 ZnO 나노선을 photoanode로 이용하고 ZnO 나노선은 암모니아수와 아연염을 이용한, 비교적 저온의 수열합성법을 통해 합성하였고, sensitizer로 쓰인 CdS, CdSe 물질은 CBD방식을 통하여 합성된 나노선 위에 in-situ로 접합시켰다. 또한, 기존의 액체전해질을 이용한 양자점 감응형 태양전지의 안정성을 향상시키기 위해 p-type의 반도체 물질인 CuSCN물질을 propyl sulfide를 이용, ${\sim}80^{\circ}C$의 열을 가하여 in-situ 방식으로 다공성 구조에 효율적으로 접합이 가능하도록 deposition하였다. 일반적으로, CuSCN film은 홀 전도체로서의 장점을 지닌 반면, 전도성이 낮은 단점이 있기 때문에 이를 향상시키기 위해서 첨가제를 이용, 농도에 따라서 전도도가 향상되고 셀의 성능이 향상되는 것을 확인하였다. 이와 같이 합성된 구조는 주사전자현미경(SEM), X-선 회절(XRD), 솔라시뮬레이터 등의 분석장비를 이용하여 태양전지로서의 특성을 분석하였다. 또한 안정성 평가를 위하여 시간에 따른 셀의 특성변화도 비교하였다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.3
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• pp.123-132
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• 2021

To determine 3D(three-dimensional) positions using a stereo-camera in close-range photogrammetry, camera calibration to determine not only the interior orientation parameters of each camera but also the relative orientation parameters between the cameras must be preceded. As time passes after performing camera calibration, in the case of non-metric cameras, the interior and relative orientation parameters may change due to internal instability or external factors. In this study, to evaluate the stability of the stereo-camera, not only the stability of two single cameras and a stereo-camera were analyzed, but also the three-dimensional position accuracy was evaluated using checkpoints. As a result of evaluating the stability of two single cameras through three camera calibration experiments over four months, the root mean square error was ±0.001mm, and the root mean square error of the stereo-camera was ±0.012mm ~ ±0.025mm, respectively. In addition, as the results of distance accuracy using the checkpoint were ±1mm, the interior and relative orientation parameters of the stereo-camera were considered stable over that period.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.527-532
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• 2014

본 연구에서는 사각 실린더로 근사된 차체 주위에 균일한 층류 유동이 흐를 때, 앞 사각 실린더의 후면에 나타나는 후류의 변화를 정상적인 관점에서 분석하였다. EDISON_CFD를 이용하여 앞 실린더와 뒷 실린더의 변화에 따른 공력계수를 확인하였다. 격자 분해능과 시간 간격에 따른 정확성을 분석하였다. 앞 실린더의 길이 변화, 두 실린더 간의 거리를 통해 나타나는 공력계수의 변화를 실제 상황에서의 운행 안정성 및 공기 저항에 대입하여 분석하였다.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.2
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• pp.86-94
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• 2020

Purpose: The purpose of this study is to compare the volume stability depending on the mixing methods and storage time for the conventional alginate and extended-pour alginate. Materials and methods: An arch-shaped metal model was fabricated, and one conventional alginate and two extended-pour alginates were used to take impressions using different mixing methods (hand and automatic). 120 impressions were taken (40 per each alginate) and stone models were made in accordance with the different storage times (immediate, 2 days, 5 days, and 6 days). The models were scanned with a 3D table scanner and dimensional change was measured by superimposing the scan data. Using SAS 9.4 (SAS Institute Inc., Cary, NC, USA), the general linear model and Tukey's post hoc test was conducted for statistical analysis (P<.001). Results: There was no statistically significant difference in the dimensional accuracy between two mixing methods, and the volume change was minimum when the stone was poured immediately in all groups. Dimensional accuracy showed a statistically significant difference between groups after 2 days of storage, and extended-pour alginate showed higher accuracy after 5 days of storage comparing to conventional one. Large amounts of volume change were showed at 2 - 5 days for conventional alginate and at 5 - 6 days for extended pour alginate. Conclusion: The mixing method of alginate does not affect volume stability. Although extended-pour alginate has better volume stability than conventional alginate for a long time, it is recommended to pour stone as soon as possible.

• Journal of Korea Port Economic Association
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• v.34 no.1
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• pp.111-132
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• 2018

As China continues to evolve as a major economic power and the Free Trade Agreement (FTA) between the Republic of Korea and China was ratified on June 1, 2015, market volume between the two countries is expected to grow more rapidly. This study aims on improving the efficiency of car-ferry lines. We conducted two surveys- for shippers and forwarders of car-ferry companies, and container liners. The study analyzes the decision factors for delivery companies and their importance for shippers and forwarders of car-ferry companies and container liners. Based on analysis of prior studies on the competition for car-ferry companies and liners, three primary variables are selected-promptness, economics, and safety. The promptness variable consists of shipping time, loading/unloading time, and customs clearing time. The economic variable consists of marine transportation cost from a domestic harbor to China, loading/unloading cost in the harbor, and overland transport cost from the harbor to shippers inland. Finally, the safety variable consists of cargo damage rates, safety facilities, such as lashing and shoring, and punctuality of transportation time. The survey and AHP results show that the promptness, safety, and economics factors are 0.549, 0.309, and 0.142 in the shipper groups of car-ferry companies' category, respectively. It indicates that there is considerable difference in the importance of each factor. In contrast, the factors are 0.350, 0.348, and 0.302 in the forwarders category, which suggests that there is little difference in each factor's importance. As for shippers and forwarders of liners, the importance of each factor is found to be in the following order: economics, safety, and promptness.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.242-242
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• 2003

DLC(Diamond-Like Carbon)는 높은 경도, 내마모성, 화학적 안정성, 생체친화성 및 열전도율이 우수하여 VTR 헤드드럼, CRT Gun, Video Tape, 인공골절, 면도날 등에 널리 사용되고 있다. 에어컨용 Al 냉각핀은 높은 냉각성능의 향상으로 인한 전기절전 효과와 내부식성 및 친수성 등이 요구된다. DC-Sputtering법에 의한 에어컨용 알루미늄 냉각핀에 인가전압의 변화 (300V, 500V, 600V)와 증착시간 (3시간, 5시간 증착)의 변화에 따른 DLC 박막을 합성하여 AFM, XRD 및 Raman spectroscopy 측정을 통하여 분석하고, Micro Vickers Hardness 및 Roughness 등을 측정하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06b
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• pp.445-450
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• 2007

NAND 플래시 메모리 기반의 실시간 임베디드 시스템에서는 일반적으로 shadowing 기법을 통해 프로그램을 수행한다. 그러나 shadowing 기법은 시스템의 부팅 시간을 증가시키고 불필요한 DRAM 영역을 차지한다는 단점 때문에 자원 제약이 심한 실시간 임베디드 시스템에는 적합하지 않다. 이에 대한 대안 중 하나는 demand paging 기법을 활용하는 것이다. 단, demand paging 환경에서는 page fault에 의한 시간 지연 때문에 태스크의 최악 실행 성능을 예측하기 어렵다. 따라서 본 논문에서는 NAND 플래시 메모리 기반의 실시간 임베디드 시스템에서 demand paging 비용을 고려한 태스크 최악 성능 분석 기법을 제안한다. 제안하는 기법은 각 태스크에 대해 demand paging 비용을 계산하고, 이를 전통적인 WCRT 분석 기법과 결합하는 방법을 사용한다. 또한 demand paging 비용과 WCET 분석을 독립적으로 고려함으로써, 최악의 경우에도 분석 결과의 안정성을 보장하고 기존의 방법에 비해 분석 복잡도를 줄였다.

• Polymer(Korea)
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• v.25 no.4
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• pp.536-544
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• 2001

We investigate, in the viewpoint of mathematical stability, the validity of the time-strain separability hypothesis employed in polymer viscoelasticity on the basis of experimental results. There have been suggested two distinct stability criteria such as Hadamard related to quick response and dissipative stability conditions, and in the limit of high deformation rate we have proved that separable constitutive equations are either Hadamard or dissipative unstable. The fact that the separability is not valid in the short time region in stress relaxation experiments exactly coincides with the results of our analysis. Therefore, since the application of the separability hypothesis incurs thermodynamic inconsistency as well as mathematical instability, such application should be avoided in the formulation of constitutive equations. In addition, careful attention should be paid to the limit of its validity even in experiments. It is also proved that there is neither theoretical nor physical validity of using the damping function.