• Annual Conference of KIPS
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• 2009.04a
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• pp.573-576
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• 2009

현재 산업 장비의 가동률 최대화를 위한 다양한 모니터링 시스템에 대한 연구들이 이루어지고 있으며, 특히 해양 수송 산업이 중심인 국내에서는 진동 정보를 활용한 선박 엔진의 고장 감지 시스템에 대한 연구들이 많이 이루어지고 있다. 본 논문에서는 국내에서 아직 관심이 적은 중소형 선박의 엔진에 대한 고장 감지 시스템의 설계 방안 및 인터페이스 설계 방안에 대해서 연구하고, 기본적인 프로그램의 프로토타입을 구현하였다. RS-View를 통해 구현한 인터페이스 간소화와 센서 수의 최소화를 통한 경제성 확보를 달성하여 중소형 선박에 언제든지 탑재 가능한 고장 감지 시스템의 설계를 수행하였다. 향후 선박에 의무 탑재화가 진행될 e-navigation의 일부분으로서 엔진의 상태 모니터링과 고장 감지를 할 수 있는 프로그램으로서 중소형 선박에 탑재되어 적절하게 사용될 수 있을 것으로 사료된다.

• Journal of Practical Engineering Education
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• v.15 no.2
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• pp.419-427
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• 2023

In this study, optimal adhesion conditions to alleviate defects caused by heat shrinkage with FDM type 3D printers with machine learning are researched. Machine learning is one of the "statistical methods of extracting the law from data" and can be classified as supervised learning, unsupervised learning and reinforcement learning. Among them, a function model for adhesion between the bed and the output is presented using supervised learning specialized for optimization, which can be expected to reduce output defects with FDM type 3D printers by deriving conditions for optimum adhesion between the bed and the output. Machine learning codes prepared using Python generate a function model that predicts the effect of operating variables on adhesion using data obtained through adhesion testing. The adhesion prediction data and verification data have been shown to be very consistent, and the potential of this method is explained by conclusions.

• Journal of the Korea Institute of Building Construction
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• v.12 no.1
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• pp.42-53
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• 2012

Lawsuits related to defects in apartment buildings involve a range of legal issues, based on which the current subjective judgment system has been established. This study aims to organize the judgment system by stage of lawsuit from a legal perspective by reviewing the factors dealt with in precedent research. The main issues at hand include assignment of obligation, the day on which the computation of exclusion period begins and the day on which the defect repair is completed. The rationality of the current subjective judgment system could be determined by reviewing the recent cases. Based on the findings of the review, the following are suggestions for improvements and complements of the system. First, the process of assignment of obligation should be systemized, and the guarantee insurance system that provides a warranty deed should be improved as well. In addition, improvements and systemization should be made to clarify the responsibilities for any defect arising from the agreements that are not stipulated on the contract, computation of abatement rate of compensation and the system by which the responsibility for the defects is completed when residents acquire ownership from rental status.

• Korean Journal of Construction Engineering and Management
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• v.21 no.1
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• pp.40-49
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• 2020

This study analyzed the factors affecting the ruling of litigation on the housing reconstruction and housing redevelopment project based on the cross analysis and logistic regression analysis. According to cross analysis result, the defensive process prerequisite group was showed significant in many variables which were past legal relation, no ownership or association member status, double lawsuit, abuse of lawsuit right·litigation trust, existence of claim-preclusion, no standing to sue·no standing to be sued, lapse of litigation period, no legal interest, no own defect of approval. On the other hand, the offensive cause of action group was found to have no significant variable. According to logistic regression result, the defensive process prerequisite group was showed significant in many variables which were past legal relation, no standing to sue·no standing to be sued, no ownership or association member status, double lawsuit, no own defect of approval, abuse of lawsuit right·litigation trust, existence of claim-preclusion. Meanwhile, the offensive cause of action group was showed significant in only one variable that was defect in relation with articles of association. Overall, it is noteworthy that the offensive cause group showed very low significant results compared with the defensive process prerequisite group.

• Korean Journal of Materials Research
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• v.11 no.10
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• pp.889-894
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• 2001

2wt% $Al_2O_3-doped$ ZnO (AZO) thin films were deposited on sapphire (0001) single crystal substrate by parellel type rf magnetron sputtering at 55$0^{\circ}C$. The as-grown AZO thin films was polycrystalline and showed only broad deep defect-level photoluminescence (PL). In order to examine the change of PL property, AZO thin films were annealed in $N_2$ (N-AZO) and $H_2$ (H-AZO) at the temperature of $600^{\circ}C$~$1000^{\circ}C$ through rapid thermal annealing. After annealed at $800^{\circ}C$, N-AZO shows near band edge emission (NBE) with very small deep-level emission, and then N-AZO annealed at $900^{\circ}C$ shows only sharp NBE with 219 meV FWHM. In Comparison with N-AZO, H-AZO exhibits very interesting PL features. After $600^{\circ}C$ annealing, deep defect-level emission was quire quenched and NBE around 382 nm (3.2 eV) was observed, which can be explained by the $H_2$passivation effect. At elevated temperature, two interesting peaks corresponding to violet (406 nm, 3.05 eV) and blue (436 nm, 2.84 eV) emission was firstly observed in AZO thin films. Moreover, peculiar PL peak around 694 nm (1.78 eV) is also firstly observed in all the H-AZO thin films and this is believed good evidence of hydrogenation of AZO. Based on defect-level scheme calculated by using the full potential linear muffin-tin orbital (FP-LMTO), the emission 3.2 eV, 3.05 eV, 3.84 eV and 1.78 eV of H-AZO are substantially deginated as exciton emission, transition from conduction band maximum to $V_{ Zn},$ from $Zn_i$, to valence band maximum $(V_{BM})$ and from $V_{o} to V_BM}$, respectively.

• Journal of Periodontal and Implant Science
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• v.32 no.4
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• pp.769-779
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• 2002

This present study was carried out to find the effects of calcium aluminate cement($CaO\;{\cdot}\;Al_2O_3$, CAC), which has been developed with bio-compatibility and mechanical properties, in biological environments. Two different particle sizes of CAC - 3.5${\mu}m$ vs. 212${\sim}$250${\mu}m$ which is recommended in periodontal bone grafting procedures-were filled in 8mm calvarial defect in Sprague-Dawley rat. The specimens were examined histologically, especially the bone-cement interface and the response of surrounding tissues. The results are as follows; 1. In the control group, inflammatory cells were observed at 2 weeks. At 8 weeks, periosteum and dura mater were continuously joined together in the defect areas. But in the center of defect area were filled up with the loose connective tissues. 2. In the experimental group l($212{\mu}m{\sim}250{\mu}m$ particle), immature bone was formed and outermost layer was surrounded by osteoid layer at 2 weeks. Osteoblasts were arranged between immature bone and osteoid layer. And, osteoid layer was remained until 8 weeks after surgery. 3. In the experimental group 2, periosteum and dura mater lost its continuity at 2 weeks. Scattering of CAC particles and infiltration of inflammatory cells were observed, which this findings deepened at 8 weeks. The result of this study shows that when calvarial defects in white rats are filled with calcium aluminate cement of 212${\sim}$250${\mu}m$, the materials are to be bio-compatible in growth and healing on surrounding tissues. When further researches are fulfilled, such as direct bone adhesion and bone regeneration ability, it's possible that CAC could be applied to various periodontology fields in the future.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.145-150
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• 2020

Water wall tube is one of the major factors consisting of a fluidized bed boiler and it plays very important role for the generation of electricity within the boiler. But these water wall tubes within the fluidized bed boiler are subject to the ware and corrosion caused by the high temperature gas and the flowing medium. If water leak is occurred, the secondary damage by the water leak will occur. As a result of that, the power generation efficiency decreases noticeably. Therefore, the maintenance of the water wall tube is very important. In this study, we designed a exciter sensor based on simulation and composed a remote field eddy current system for the defect evaluation of the outer water wall tube. Starting from the shape design of exciter, we conducted simulations for various design factors such as the water wall tube size, material, frequency, lift-off and so on. Based on the results, we designed the optimum exciter sensor for the water wall tube test within the fluidized bed boiler.

• Korean Journal of Construction Engineering and Management
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• v.14 no.5
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• pp.55-64
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• 2013

The complexity of constructing medical institutions is higher than that of general buildings, and many change orders in the design and defect repairs in the construction phase are required due to strict government regulations. The priority control of constructions and impact factors of medical institutions were analyzed in this study, and difficulties in the control in the design and construction phase were identified. First, the priority management factors that were identified were as follows: architecture, facilities, and electricity. Second, 1) priority management in constructions and factors resulting in change orders and 2) priority management in constructions involving defect repair were analyzed. Third, the importance recognized by the construction managers were analyzed. The priority management in constructions and factors that were recognized by the construction manager were deducted as having low importance, although there were many change orders and defects. The work of finishing, wall building, joining, office automation and communication function, and lighting were analyzed in the design phase, and waste, the office automation and communication function, ceilings, contamination control, and plumbing were analyzed in the construction phase. The results showed that there will be a decrease in change orders and defects if the concentration of the manager was elevated and priorities were managed.

• Journal of the Korean Society for Railway
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• v.18 no.5
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• pp.401-409
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• 2015

Defects generated in a railroad track that guides the railroad vehicle have the characteristic of growing fast; as such, the detection technology for railroad track defects is very important because defects can eventually cause mass disasters like derailments. In this study, a speed-up test facility was fabricated to investigate the feasibility of using magnetic flux leakage (MFL) technology for defect detection in a railroad track under speed-up condition; a test was conducted using a railroad track specimen with defects. For this purpose, an MFL sensor head dedicated to the configuration of the railroad was designed and test specimens with artificial defects on their surfaces were manufactured. Using the test facility, a speed-up test ranging from 4km/h to 12km/h was performed and defects including locations were successfully detected from MFL signals induced by defects with enhanced visibility by differentiating raw MFL signals. In the future, it should be possible to apply this system to a high-speed railroad inspection car by improving the lift-off stability that is necessary for speed-up of the developed MFL sensor system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1066-1072
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• 2011

In the method to analyze the relationship in the system call orders, the normal system call orders are divided into a certain size of system call orders to generates gene and use them as the detectors. In the method to consider the system call parameters, the mean and standard deviation of the parameter lengths are used as the detectors. The attack of which system call order is normal but the parameter values are changed, such as the format string attack, cannot be detected by the method that considers only the system call orders, whereas the model that considers only the system call parameters has the drawback of high positive defect rate because of the information obtained from the interval where the attack has not been initiated, since the parameters are considered individually. To solve these problems, it is necessary to develop a more efficient learning and detecting method that groups the continuous system call orders and parameters as the approach that considers various characteristics of system call related to attacking simultaneously. In this article, we detected the anomaly of the system call orders and parameters by applying the temporal concept to the system call orders and parameters in order to improve the rate of positive defect, that is, the misjudgment of anomaly as normality. The result of the experiment where the DARPA data set was employed showed that the proposed method improved the positive defect rate by 13% in the system call order model where time was considered in comparison with that of the model where time was not considered.