• Special Issue of the Society of Naval Architects of Korea
• /
• 2009.09a
• /
• pp.18-23
• /
• 2009

After the installation of electric cables at block, PE(pre-erection) and hull stages, the coating stains on the electric cable sheath were unavoidably occurred by additional painting process. According to class rules paint or coating applied on the electric cables shall not adversely affect the mechanical, chemical of fire resistant characteristics of the electric cable sheath. However, there has not been quantitatively studied about the effect of coating stains on properties of sheath materials. In this study, we tried to investigate the effect of coating stains on the performance and deterioration of sheath materials by using FTIR, SEM analysis, flame retardant, high potential voltage and tensile test. The results sowed that coating stains, which were occurred during painting work on site could not adversely affect on the performance and deterioration of sheath materials.

• Management & Information Systems Review
• /
• v.28 no.4
• /
• pp.109-129
• /
• 2009

This study aims at investigating the effectiveness of SME's R&D system empirically. Specifically, this study analyze the relationships among R&D inputs(R&D investment, R&D human resource management), process(R&D planning, external network, internal cooperation), and output(technological innovation). A questionnaire was developed to measure the above variables. To test these relations, data were collected from the small and medium-sized IT firms located in Daegu-Kyungbuk region. The survey data of 154 firms were integrated as the empirical base for testing the relations. Most respondents were from the managers. Structural equation modeling analyses were used to examine the relations. Major results are as follows: Firstly, R&D HRM was positively and significantly influenced on the R&D planning. Secondly, R&D planning was positively and significantly affected on the external network, internal cooperation, and technological innovation. Thirdly, the both relations between R&D investment and R&D planning, and external network and technological innovation were not significant statistically. These results suggest the following implications. First, R&D human resource management is very important for IT SMEs. Secondly, internal cooperation mediates R&D inputs and technological innovation by approaching the other department's unique resources and by sharing the cost of new resource development. Several future researches need to overcome the limitations of this research. First, this study's sample was based on the small and medium-sized IT firms just located in Daegu-Kyungbuk region. This limitation may imply that empirical results can not represent overall small and medium-sized firm's situations. Therefore, future research needs to include different samples. Secondly, this study depends on the latitudinal study.

• Journal of Korea Technology Innovation Society
• /
• v.17 no.3
• /
• pp.449-466
• /
• 2014

There have been various researches on the relationship between a company's R&D investment and the outcome from innovation. However, these studies failed to effectively analyze the decision-making process followed by companies in relation to knowledge production. Especially, in analyzing the patent of companies, the Poisson model has been commonly used, but its limitations have been pointed out. In recent years, many studies have adopted negative binomial models, but they still pose limitations in analyzing the selection process. This paper proposed a hurdle negative binomial model to effectively reflect the company's decision embedded within patent information and conduct an empirical analysis on a survey of businesses' activities. In particular, the study analyzed the selection process of companies in determining the number of patents. As a result of estimation, the presence of over-dispersion was identified. In addition, the Wald-test confirmed that setting up of hurdles was valid, and there was a difference between the results of hurdle models and those of general negative binomial settings.

• Korean Chemical Engineering Research
• /
• v.59 no.4
• /
• pp.532-541
• /
• 2021

Recently, research on the application of artificial intelligence in the chemical process has been increasing rapidly. However, overfitting is a significant problem that prevents the model from being generalized well to predict unseen data on test data, as well as observed training data. Cross validation is one of the ways to solve the overfitting problem. In this study, the time-series cross validation method was applied to optimize the number of batch and epoch in the hyperparameters of the prediction model for the 2,3-BDO distillation process, and it compared with K-fold cross validation generally used. As a result, the RMSE of the model with time-series cross validation was lower by 9.06%, and the MAPE was higher by 0.61% than the model with K-fold cross validation. Also, the calculation time was 198.29 sec less than the K-fold cross validation method.

• Journal of the Korean Ceramic Society
• /
• v.36 no.1
• /
• pp.15-20
• /
• 1999

Elevated temperature static fatigue behavior of silicon has been investigated by stress intensity/life test method. Static fatigue crack growth rate increase with the increase of temperature. Such tendency is found to be mainly related to the decrease of fracture toughness with the increase of temperature. That is, when static fatigue crack growth rate, da/dt is expressed by da/dt=AK1m, a constant A is a function of fracture toughness Kc and the exponent m is a constant which is independent of temperature or Kc. However, in the case of high temperature that glass phase is softened, the crack growth rate is found to be deviated from the above relation. This reason is, thus, discussed.

• Design & Manufacturing
• /
• v.10 no.2
• /
• pp.34-38
• /
• 2016

In this paper, a transversely isotropic behavior of AZ31 Mg alloy produced by equal-channel angular pressing (ECAP) process was investigated through tensile test and microstructure observation. The effects of initial ECAP pass number on the anisotropic behavior and mechanical properties of the Mg alloy are evaluated after conventional direct extrusion test, which are carried out at a temperature of $200^{\circ}C$. As a result of the tensile test in three directions ($0^{\circ}$, $45^{\circ}$, and $90^{\circ}$ to the extrusion direction of the sheet) at room temperature, elongation of as-extruded AZ31 alloy(ECAP for 0 pass) showed an unusual anisotropic behavior depending on the extrusion direction although the yield strength and tensile strength are similar to the ECAPed AZ31 alloy. After ECAP for 4 passes at $200^{\circ}C$, microstructural observations of ECAPed magnesium alloy showed a significant grain refinement, which is leading to an equiaxed grain structure with average size of $2.5{\mu}m$. The microstructures of the extruded billet are observed by the use of an electron back-scattering diffraction (EBSD) technique to evaluate of the influence on the grain refinement during extrusion process and re-crystallization mechanism of AZ31 Mg alloy.

• Journal of Advanced Navigation Technology
• /
• v.26 no.6
• /
• pp.464-473
• /
• 2022

In this paper, about a lightweight design that satisfies the performance of UHF-GPS Antenna used in autonomous underwater vehicle is proposed. Structural analysis, watertight external pressure test and non-destructive testing used in the design process are decided in consideration of structural safety for operating external forces in the underwater environment. First, the material of radome is selected for the performance of the UHF-GPS Antenna for communication with the carrier on the underwater operation in consideration of the 20 bar pressure generated. And the material of radome as PA-GF is selected by conducting electromagnetic field analysis and structural analysis and by considering high strength, rigidity and high dielectric constant. Electromagnetic field analysis and structural analysis by the thickness of radome are additionally performed in order to satisfy the required weight of UHF-GPS antenna. After selecting the final model, its structural safety is verified through watertight external pressure test and non-destructive testing.

• Journal of the Korean Society of Systems Engineering
• /
• v.14 no.2
• /
• pp.1-7
• /
• 2018

The research and development stage can improve the goal level of the project through systematic operation and management of systems engineering. The test evaluation tasks in the R&D process have a lot of connections with the system engineering in terms of requirement management, and the methodology for deriving the requirements when establishing the test evaluation items has been consistently required. In this paper, we propose the process of effectively establishing and using QFD (Quality Function Deployment), a tool to manage customer requirement, and drawing up HOQ (House of Quality) in the search and exploratory development stage of the self - propelled mortar project.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.3
• /
• pp.157-165
• /
• 2014

To develop a compact vehicle for women, the most important areas are 'behavioral characteristics, life style and driving posture'. Static AM95%ile manikin is used for package guideline. Since women's characteristics and sitting position are different from men, however, the guideline cannot satisfy women drivers. Therefore, the goal of this study is to make the database with dynamic women's driving posture and behavioral characteristics at compact vehicle. Research process will be made as follows. Firstly, through the online/offline survey and statistic analysis, lifestyle and behavioral characteristics (discomfort elements) of women are extracted. Secondly, the author performs scenario test to acquire the discomfort value of driving situation and life style. 3D models of women's manikin and driving posture were created by CATIA HUMAN. The 3D models are used for the purpose of analyzing women's driving posture. Finally, with the ANOVA result and comparison between real driving posture and package guidelines, the author is able to suggest the main issue for women drivers.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1422-1423
• /
• 2006

In our study, the PTFE nozzle ablation in the high-voltage self-blast type $SF_6$ gas circuit breaker was investigated. The test circuit breaker has the structure that the pin electrode is moving and the pressure reservoir volume and the dimension is almost same as commercial 145kv 40kA circuit breaker for similar result in real circuit breaker. The variation of current and arcing time was the range of $36kA_{rms}$(symmetry) - $40kA_{rms}$(asymmetry) and 10-16 ms. From the measured data the tendecy of the mass loss of the nozzle to current load and arc energy was estimated. In this process, the distance from the arc to nozzle(PTFE) surface, area which was exposed to arc and stroke contour was considered. These results will be used to enhance the accuracy of the computational fluid dynamics analysis in circuit breaker and estimate the residual life time of a circuit breaker.