• Transactions of the Korean hydrogen and new energy society
• /
• v.33 no.2
• /
• pp.176-182
• /
• 2022

Since the various characteristics of the polymer electrolyte membrane are not clearly identified, it is difficult to predict and design applications for various conditions. In this study, as a previous study on the aging of the polymer electrolyte membrane, a study was conducted on the change of mechanical properties according to the aging of the polymer electrolyte membrane. Through the tensile test of Nafion 117, the mechanical properties change due to aging was confirmed. As a result of the tensile test, it was confirmed that the aged Nafion 117 had reduced tensile strength. Through DSC measurement, aged Nafion confirmed that the glass transition temperature and enthalpy change were low, which is thought to be the effect of molecular motion and transition due to the lapse of time. The effect is thought to cause a difference in the amount of change in enthalpy, resulting in a difference in mechanical properties during tension.

• Journal of Industrial Technology
• /
• v.36
• /
• pp.9-16
• /
• 2016

In the face of increasing impact of climate change due to human activities, there has been an urgent need to resolve the problem in water resources planning management and environmental engineering. Therefore SWAT model was used to identify the impacts and change in hydrological cycle and environmental aspect. The most important step for the development of SWAT model is calibration procedure. Therefore, SWAT-CUP automatic calibration module was used to find some optimal parameters in SWAT model. After calibration in the cheongmicheon basin, SWAT model is used for the projected precipitation and temperature of RCP 4.5 and 8.5 climate change scenarios in AR5. The quantity and quality using SWAT model from 2014 to 2100 were identified. Finally, this study can provide the reasonable finding on impact by climate change.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.5
• /
• pp.710-715
• /
• 2010

This study developed an automatic tool change system of the SMA-based tool clamping device for applications of micro-machine tools. This paper first describes clamping and unclamping procedures of the automatic tool change system and its basic configuration. Second, it presents fabrication techniques of components, such as a heating/cooling system and a tool loader. Finally, it describes automatic tool change test conducted with a prototype in which the fabrication techniques of components were employed. As the results of the test, times needed for clamping and unclamping operations were estimated to 18(s) and 8(s) respectively. The experimental results confirm that the proposed automatic tool change system can be sucessfully applied to micro-machine tools.

• The Journal of Information Systems
• /
• v.6 no.1
• /
• pp.47-62
• /
• 1997

Adoption of information technology(IT) in a corporation has been started with the aim of efficient process and management of business being complicated. But, this adoption of IT is roleplaying the rearrangement of organization structure. Many researchers have studied the relationship between adoption of IT and change of organization structure. In this research, it has been studied that how the adoption of IT influences on the change of organization structure. Adoption of IT ina corporation influences the structure of manpower and this influence causes the change of structure of organization. However, this influence is not only the deterministic source to the change. In a corporation, not only intention and role of chief executive and but also participations of employees for the adoption of IT make differences in the quality of corporation information systems and, as a result, the aspect of organization structure change.

• Proceedings of the Korea Inteligent Information System Society Conference
• /
• 2000.11a
• /
• pp.417-426
• /
• 2000

This study suggests integrated neural network models for Interest rate forecasting using change-point detection, classifiers, and classification functions based on structural change. The proposed model is composed of three phases with tee-staged learning. The first phase is to detect successive and appropriate structural changes in interest rare dataset. The second phase is to forecast change-point group with classifiers (discriminant analysis, logistic regression, and backpropagation neural networks) and their. combined classification functions. The fecal phase is to forecast the interest rate with backpropagation neural networks. We propose some classification functions to overcome the problems of two-staged learning that cannot measure the performance of the first learning. Subsequently, we compare the structured models with a neural network model alone and, in addition, determine which of classifiers and classification functions can perform better. This article then examines the predictability of the proposed classification functions for interest rate forecasting using structural change.

• Journal of Forest and Environmental Science
• /
• v.33 no.4
• /
• pp.281-294
• /
• 2017

Tropical forests constitute almost half of the global forest cover, account for 35% of the global net primary productivity and thereby have potential to contribute substantially to sequester atmospheric $CO_2$ and offset climate change impact. However, deforestation and degradation lead by unsustainable management of tropical forests contribute to the unprecedented species losses and limit ecosystem services including carbon sequestration. Sustainable forest management (SFM) in the tropics may tackle and rectify such deleterious impacts of anthropogenic disturbances and climatic changes. However, the existing dilemma on the definition of SFM and lack of understanding of how tropical forest sustainability can be achieved lead to increasing debate on whether climate change mitigation initiatives would be successful. We reviewed the available literature with a view to clarify the concept of sustainability and provide with a framework towards the sustainability of tropical forests for enhanced carbon stock and climate change mitigation. We argue that along with securing forest tenure and thereby reducing deforestation, application of reduced impact logging (RIL) and appropriate silvicultural system can enhance tropical forest carbon stock and help mitigate climate change.

• 대한공업교육학회지
• /
• v.36 no.2
• /
• pp.111-130
• /
• 2011

The purpose of this study was to identify a causal relationship among commitment to change, needs of technology education innovation, communication and self-efficacy of technology teachers. A total of 300 copies of questionnaires were used for data analysis except for 117 copies like the one where insincerely responds to any question was found. To ensure the reliability and validity of questions, I performed technical statistics like average, standard deviation, skewness, and kurtosis via PASW 18.0, item-total correlation and the totality, and reliability analysis. I undertook a confirmatory factor analysis via AMOS 7.0 to ensure the validity of items together with a structural analysis to perform a path analysis among variables and assess the suitability of model. The major finding of this study were as follows: First, because fit index of hypothetical model generally met standards in this study, a hypothetical model was judged appropriately. Second, needs of technology education innovation had a positive effect on communication and commitment to change of technology teachers. And, communication among technology teachers had a positive effect on commitment to change of technology teachers. This result means that communication among technology teachers is important to activation of technology education. Third, self-efficacy had a positive effect on commitment to change of technology teachers. This result means that it needs to raise self-efficacy level through teacher education.

• Journal of Technologic Dentistry
• /
• v.6 no.1
• /
• pp.5-10
• /
• 1984

This experimental study was performed to investigate the effect of the wax extension method of posterior palatal seal area, introduced by Vig, on the amount of the vertical occlusal change of processed dentures. Twenty samples of maxillary wax trial dentures were constructed. Among them, the posterior palatall seal of ten samples were extended with wax over the posterior wall of the cast while that of the other ten were not. Then all were processed with self-curing resin and the amount of the vertical occlusal change was compared. The obtained result was that this method was proved to be effective in reducing the amount of the vertical occlusal change occuring in denure proccsing.

• Journal of Korean Physical Therapy Science
• /
• v.18 no.4
• /
• pp.73-79
• /
• 2011

Purpose : This study is to know how position change in high-heels affects sacral tilt angle. 15 healthy women aged 21.87(standard deviation=3.54) were tested. Method : Lumbar and sacral tilt angle was measured by radiography barefooted, and after 15 mins of application time, they were measured in the same way in high-heels. Result : There was not notable difference in lumbar lordosis, lumbosacral angle, and sacral tilt angle. However, there was differences in change degree, which was measured by estimation data of [post-pre)/pre]${\times}$100. Conclusion : There was no notable difference in lumbar lordosis, lumbosacral angle, and sacral tilt angle, but as there were differences in change degree, research about how women's lumbar change when heel height increases is needed.

• Journal of Electrical Engineering and information Science
• /
• v.1 no.1
• /
• pp.23-28
• /
• 1996

In this series of two papers, adaptive code rate change schemes in DS-SSMA systems are proposed. In the proposed schemes the error correcting code rate is changed according to the channel states. Two channel states having significant effects on the bit error probability are considered: one is the effective number of users considered in Part 1, and the other is the fading environment considered in Part 2. These channel states are estimated based on retransmission requests. The criterion for the change of the code rate is to maximize the throughput under given error bound. Simulation results show that we can transmit maximum amount of information if we change the code rate based on the channel states.