• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.229-239
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• 2018

The purpose of this study was to effectively produce the biosugar from cell wall of lipid extracted microalgae (LEA) by using microwave-assisted pretreatment without enzymatic hydrolysis process. Response surface methodology (RSM) was applied to optimization of microwave-assisted pretreatment conditions for the production of biosugar based on enzyme-free process from LEA. Microwave power (198~702 W), extraction time (39~241 sec), and sulfuric acid (0~1.0 mol) were used as independent variables for central composite design (CCD) in order to predict optimum pretreatment conditions. It was noted that the pretreatment variables that affect the production of glucose (C6) and xylose (C5) significantly have been identified as the microwave power and extraction time. Additionally, the increase in microwave power and time had led to an increase in biosugar production. The superimposed contour plot for maximizing dependent variables showed the maximum C6 (hexose) and C5 (pentose) yields of 92.7 and 74.5% were estimated by the predicted model under pretreatment condition of 700 w, 185.7 sec, and 0.48 mol, and the yields of C6 and C5 were confirmed as 94.2 and 71.8% by experimental validation, respectively. This study showed that microwave-assisted pretreatment under low temperature below $100^{\circ}C$ with short pretreatment time was verified to be an effective enzyme free pretreatment process for the production of biosugar from LEA compared to conventional pretreatment methods.

• Journal of Biomedical Engineering Research
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• v.18 no.3
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• pp.291-299
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• 1997

As a microimaging device detecting gamma rays emitted from small lesions or tumors during operation, the intraoperative surgical probe has been proposed and is now under development. We have designed a multipurpose portable gamma prove system and evaluated the performance both for the absolute counting purpose of residual radioactivities and for the localizing capability of gamma events using the NaI(Tl) crystal and two types of photomultiplier tubes(PMTs). Counting efficiencies in the range of routine clinical use of radiation dose were measured using the assembly of single channel PMTs and 0.5 inch thick NaI(Tl) crystal of 1 inch diameter. The positioning of gamma events for imaging purpose requires the multiple channel PMTs with appropriate positioning electronics. We have designed a simple and reliable positioning circuit based on the concept of modified Anger. In preliminary experiments using the multiple channel PMT of 3 inch diameter and the dim lighth source, we were able to trace and localize the correct position with reduced positioning error by the use of two multiplier/divider chipset and simplified peripherals. The energy resolutions for the counting gamma probe measured as full width at half maximum(FWHM) for Cs-137, F-18, Tc-99m were 12%, 13%, and 36%, respectively. The spatial resolution for the imaging gamma probe measured as FWHM for green LED was 2.9 mm. The results indicate that the currently developing probe is very promising and could be very useful for many applications in nuclear medicine. Future studies will include developing collimators, improving interface hardwares, and evaluating the system with clinical data.

• Smart Media Journal
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• v.8 no.4
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• pp.58-63
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• 2019

The growth of the mobile device market has changed the education market and led to the quantitative growth of various media education. In particular, smart devices, which have better interaction than existing PCs or consoles, can develop more user-friendly content, allowing various types of educational content and inducing changes in traditional education methods for consumers. Although many researchers recently suggest viable development methods or marketing elements of contents, development companies, and developers, until now, merely rely on the human senses. Therefore, it is necessary to study the actual user's smart-device based usability and experience environment. This study aims to propose an intuitive statistical processing method for analyzing the usability of game-type educational contents in terms of form, for popular games that have been released as a basis for analyzing the user experience environment. In particular, because the game industry has a sufficient number of similar examples, it is possible to conduct research based on big data and to use them for immediate decision-making between multiple co-developers through the analysis method proposed by the research. It is expected to become an analytical model that can communicate with other industries because it is effective in securing data sources.

• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.369-374
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• 2016

The growing demand of virtual computing and storage resources in the cloud computing environment has led to deduplication of storage system for effective reduction and utilization of storage space. In particular, large reduction in the storage space is made possible by preventing data with identical content as the virtual desktop images from being stored on the virtual desktop infrastructure. However, in order to provide reliable support of virtual desktop services, the storage system must address a variety of workloads by virtual desktop, such as performance overhead due to deduplication, periodic data I/O storms and frequent random I/O operations. In this paper, we designed and implemented a clustered file system to support virtual desktop and storage services in cloud computing environment. The proposed clustered file system provides low storage consumption by means of inline deduplication on virtual desktop images. In addition, it reduces performance overhead by deduplication process in the data server and not the virtual host on which virtual desktops are running.

• Journal of Korean Society of Rural Planning
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• v.20 no.4
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• pp.209-220
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• 2014

This study investigated the problem of the existing rural development plan where the opinions of local residents are excluded due to the lack of expert knowledge and limited participation and sought the village development plan driven by the voluntary participation of local residents by applying a rural forum targeting rural villages to solve the problem. As a result of the study, (1) the problem of the current village development plan should be made based on the participation of local residents, and (2) this problem has remained as an important challenge. Therefore, the village improvement activities that have reflected the opinions of local residents can be said to be (3) the process that seeks the change into the rural planning process led by local residents, and this study derived the ways to ensure the voluntary behavior of local residents, strengthen local residents' capacity to create on-going villages, and expand local residents' participation opportunities in the entire process of rural planning through the application of the rural forum. (4) Although it is generally difficult for local residents to propose opinions directly and exert influence in the rural planning and design process and it is not easy to reduce the difference in the perspective between the professionals and local residents, significance lies in the fact that local residents voluntarily determine the future of their region and derive the plan. Therefore, the experience of decision-making and consensus process through the rural forum can promote the sustainability of the village creation participated by local residents and the increase of local residents' role. This study took one village as an example to reflect the results applied to the rural forum, and it is difficult to determine that it has been fully verified with the method of residents' participation. Therefore, future studies to verify the effectiveness of village creation and seek the empirical utilization measures are needed more, and the operation of education programs and various support plans suitable to the capacity and level of local residents should be promoted rather than the traditional lecture-style stereotyped education in the future for sustainable rural development.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.703-708
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• 2000

As the engine design changes to get high efficiency and performance of commercial diesel engine, surface w wear of the earn follower becomes an important issue as applied load increasing at the contact face between cam follower and cam. We developed the ceramic cam follower made of sili$\infty$n nitride ceramic which was more wear resistant than the cast iron or sintered metal cam follower. Ceramic cam follower was made by direct brazing of thin ceramic disk to steel body using an active brazing alloy without the interlayer. In-situ crowning(R), resulted from the difference of thermal expansion coefficient between ceramic and carbon steel after direct brazing without any stress-relieving inter]ayer, could be controlled. When a earbon steel was heated above $A_{c1}$ point and then c$\infty$led, the expansion curve represented a hysteresis. Appropriate crowning was achieved below the $A_{c1}$ point(about $723^{\circ}C$) and crowning increased with brazing temperature exponentially above the $A_{c1}$ point. Optimum brazing temperature range was from 700 to $720^{\circ}C$. We developed successfully the ceramic cam follower having appropriate crowning and being inexpensive. Also we could successfully control the crowning of ceramic earn follower by hysteresis behavior of thermal expansion of earbon steel during direct brazing process.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.6
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• pp.747-752
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• 2006

In this paper, the adaptive fuzzy sliding mode controller with two systems is designed. The existing sliding mode controller used to $approximation{\^{u}}(t)$ with discrete sgn function and sat function for keeping the state trajectories on the sliding surface[1]. The proposed controller decrease the disturbance for uncertain control gain and This paper is concerned with an Adaptive Fuzzy Sliding Mode Control(AFSMC) that the fuzzy systems ate used to approximate the unknown functions of nonlinear system. In the adaptive fuzzy system, we adopt the adaptive law to approximate the dynamics of the nonlinear plant and to adjust the parameters of AFSMC. The stability of the suggested control system is proved via Lyapunov stability theorem, and convergence and robustness properties ate demonstrated. Futhermore, fuzzy tuning improve tracking abilities by changing some sliding conditions. In the traditional sliding mode control, ${\eta}$ is a positive constant. The increase of ${\eta}$ has led to a significant decrease in the rise time. However, this has resulted in higher overshoot. Therefore the proposed ${\eta}$ tuning AFSMC improve the performances, so that the controller can track the trajectories faster and more exactly than ordinary controller. The simulation results demonstrate that the performance is improved and the system also exhibits stability.

• Research in Community and Public Health Nursing
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• v.32 no.3
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• pp.368-381
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• 2021

Purpose: The obesity prevention and management program led by public health centers are important in the community. This study aims to identify the current status of obesity prevention and management programs at public health centers and perceptions regarding facilitators and barriers when implementing programs. Methods: This study used a concurrent mixed methods design. A survey was conducted to investigate the current status and infrastructure of the obesity prevention and management program at eighty-three public health centers nationwide. Nine program managers and six local residents with experience in the program were interviewed by using a semi-structured questionnaires. Results: Most of the infrastructure facilities for the program were inadequate, and insufficient budgets and lack of professional staff were identified as barriers. Facilitators included diversification of program delivery methods, operator competence, and visible outcomes and rewards. For the effectiveness of the program, it is vital to have adequate assistants, a sufficient budget, various promotional methods, and connections with various institutions in the community. On this basis, it is acknowledged that the public health center serves as a platform for preventing and managing obesity in the community. Conclusion: It is expected that infrastructure improvements in public health centers and the link with community resources are needed. In addition, there is an urgent need to set standards for obesity prevention and management programs implemented in public health centers to 'resolve regional disparities'.

• Journal of The Korean Association For Science Education
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• v.41 no.6
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• pp.501-517
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• 2021

In the present age, when the development of science and technology is leading the changes, this study supports the view that students should possess the literacy to participate democratically and critically in socio-scientific issues, and should be positioned as agentic and participatory citizens. Accordingly, we implemented a club activity that emphasize climate social action for elementary students, and explored how students were positioned in relation to climate change. In this study, position is defined as a complex cluster of rights and duties that students have in relation to climate change. The club activity was implemented throughout 46 sessions from March to July, 2019 for 11 sixth graders of 'H elementary School' in Seoul, and transcripts of video and interviews were analyzed by means of a constant comparison method. In the course of the activity consisting of three steps, the students exhibited different positioning and they are as follows: In the global warming modeling activity for Step 1, students were positioned as 'active learners', but at the same time, they showed a contradiction in being positioned as 'apprentice'. In the student-led research activities inherent to Step 2, they were positioned as 'scientists who design and conduct research' and 'bystanders' due to the controversial nature of SSI knowledge. As students participate in the social actions involved in Step 3, the position changed from 'elementary school students facing difficulty in making a change' to 'participatory citizens creating changes.' This study is significant because it shows students' potential to promote participatory and democratic citizenship through action-oriented SSI activities. In addition, pedagogical approaches were discussed dealing with the contradictions and limitations of positioning.

• 한국사회정책
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• v.25 no.1
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• pp.71-96
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• 2018

Globalization, deindustrialization, and the revolutionary development of technology has led to the concerns that existing social policies might not be fit for the current and upcoming society. At the same time, the idea of universal basic income has drawn significant attentions as the alternative to the old welfare state. There are pros and cons of basic income, and scholars of both sides stand against each other with their equivalently strong logics. In this situation, some governments have planned or conducted field experiments in order to estimate the causal effects of basic income. This study explores the Finnish and Dutch basic income experiments in methodological perspective. All the World have been watching the experiments in these two countries with keen interest. The results of these experiments will surely influence on the pros and cons of basic income in numerous countries, including South Korea. It is important to precisely figure out the methodological meanings and limitations of the experiments, for the experiments in both countries deal with only some partial components of basic income and have been exposed to many threats to internal validity. Therefore, scholars for and against basic income should be careful in interpreting the findings from these experiments. This study elucidate the methodological meanings and limitations of the Finnish and Dutch basic income experiments. Furthermore, this study extracts some lessons from these experiments that would be useful if scholars would have an opportunity to design and conduct a basic income experiment in South Korea.