• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.306-311
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• 2013

Purpose: With the ever-rising energy prices, thermal energy heavily consuming facilities of the agricultural sector such as commercialized greenhouses and large-scale Rice Processing Complexes (RPCs) need to cut down their energy cost if they must run profitable businesses continually. One possible way to reduce their energy cost is to utilize combustible agricultural by-products or low-price oil instead of light oil as the fuel for their boiler systems. This study aims to analyze the heavy oil combustion characteristics of a newly developed hot water boiler system that can use both rice husk and heavy oil as its fuel convertibly. Methods: Heavy oil combustion experiments were conducted in this study employing four fuel feed rates (7.6, 8.5, 9.5, 11.4 $l/h$) at a combustion furnace vacuum pressure of 500 Pa and with four combustion furnace vacuum pressures (375, 500, 625, 750 Pa) at fuel feed rates of 9.5 and 11.4 $l/h$. Temperatures at five locations inside the combustion furnace and 20 additional locations throughout the whole hot water boiler system were measured to ascertain the combustion characteristics of the heavy oil. From the temperature measurement data, the thermal efficiency of the system was calculated. Flue gas smoke density and concentrations of air-polluting components in the flue gas were also measured by a gas analyzer. Results: As the fuel feed rate or combustion furnace vacuum pressure increased, the average temperature in the combustion furnace decreased but the thermal efficiency of the system showed no distinctive change. On the other hand, the thermal efficiency of the system was inversely proportionally to the vacuum level in the furnace. For all experimental conditions, the thermal efficiency remained in the range of 80.1-89.6%. The CO concentration in the flue gas was negligibly low. The NO and $SO_2$ concentration as well as the smoke density met the legal requirements. Conclusions: Considering the combustion temperature characteristics, thermal efficiency, and flue gas composition, the optimal combustion condition of the system seemed to be either the fuel feed rate of 9.5 $l/h$ with a combustion furnace vacuum pressure of 375 Pa or a fuel feed rate of 11.4 $l/h$ with a furnace vacuum pressure between 500 Pa and 625 Pa.

• 한국체육학회지인문사회과학편
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• v.57 no.1
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• pp.405-419
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• 2018

This study of the Wholeness Program relevant to dementia behavior and verification of buffering effects. For the purpose of this, among those who were attending Day Care Centers belonging to Seniors Welfare Center of M1 and M2 located in Seoul. Among those who met all these requirements, 40 senior citizens were finally selected. After carrying out a preliminary test to the selected subjects, 20 elderly of Seniors Welfare Center of M1 were randomly placed as an experimental group, while other 20 people of Seniors Welfare Center of M2, as a control group. The Wholeness Program relevant to dementia behavior was carried out from March 14 to May 30 of 2016, for 12 weeks, twice a week. As for the measurement tool, this study depended on the Korean version of Mini Mental State Examination (MMSE-K), the Korean version of Modified Barthel Index (K-MBI) and the Korean version of Geriatric Depression Scale (GDS-K). While the elderly were participating in the Wholeness Program relevant to dementia behavior, they were measured two times in total, before and after the participation in dementia behavior. Based on SPSS-PC (version 21.0), firstly, independent t-test was carried out to understand the homogeneity between the experimental group and the control group. Secondly, matched-pair t-test was carried out between preliminary test and post-test to inquire into the effects of MMSE-K, K-MBI and GDS-K. Thirdly, ANOVA was conducted to confirm the variation (change amount) between preliminary test and post-test. According to the survey results, the Wholeness Program relevant to dementia behavior of the elderly shows overall effects in all spheres of changes of cognitive ability (MMSE-K), changes of physical capacity (K-MBI) and changes of depression level (GDS-K).

• Journal of Energy Engineering
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• v.23 no.1
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• pp.40-45
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• 2014

The ventilation frequency of 0.5 times in residential facilities is applied mandatorily to the housing facilities containing more than 100 house units to improve the indoor air quality and create comfortable interior conditions and pleasantness for residents. The Building Energy Efficiency Rating system requires the implementation of leakage test based on ventilation frequency with the test results being reflected in the efficiency ratings, thereby stimulating the precise construction of the fittings in the periphery of windows and savings of energy that can be lost due to the infiltration air. The inspection results of the Building Energy Efficiency Rating at the site showed that the ventilation frequency was in the range between 0.63 and 0.71 and that the difference was found to have a significant effect on the amount of energy reduction. It is urgent to conduct the study on highly leakage-proof buildings and construction methods, along with the expansion of mandatory leakage-proof diagnosis of non-residential buildings, considering the mandatory ventilation frequency below 0.6 for passive houses under the European standards and the target set by Korea to introduce the passive house, the rigorous standard for energy efficiency in buildings and mitigating their ecological footprint, by 2017 and achieve the zero house by 2025.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.119-127
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• 2011

Objective of this study is to identify properties on strength increase of hardened concrete and fluidization of non-hardened concrete using waste ceramics generated by construction waste, which is a type of industrial waste, and by ceramics, which is a clay plastic, during its production process, and determine length change ratio caused by drying shrinkage during substitution of recycle aggregate and waste ceramics, and whether they can be used as concrete compounds. Slump of non-hardened concrete exhibited the best fluidization and formability at recycled aggregate's replacement ratio of 60% driven by higher substitution ratio of recycled aggregate and waste ceramics while air content met the KS requirement when substitution ratio of waste ceramics was $4,000cm^2/g$. Compressive strength of hardened concrete exceeded the requirements at early age and standard age and temperature dropped by roughly $6{\sim}10^{\circ}C$ less than the standard at maximum temperature in adiabatic temperature increase, which will hopefully result in stronger durability.

• Information Systems Review
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• v.11 no.2
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• pp.147-167
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• 2009

As global climate changes, the interest in environmental crisis is increasing and a number of international agreements and regulations against this crisis are being established. Global information technology(IT) corporations are building their own pro-environmental green IT strategies to cope with the regulatory measures. Green IT broadly refers to pro-environmental technologies designed to replace hazardous materials, maximize energy effectivity, and find alternative energies. In the current stage of the IT industry development, Green IT specifically refers to the technologies that deal with the server heat generation and the energy reduction in data center. This study defines the concept of Green IT and reviews its origin and necessity. Then, it examines the issues regarding Green IT industry in Korea as well as other countries and compares the Green IT strategies developed in each country. Reviewing the recent development of IT and data center market enables us to see that overall Green IT strategies focus on the establishment of Green Internet Data Centers. Therefore, this study analyzes the cases in which some domestic and foreign corporations introduced Green Data Centers in order to examine the protocol and legal requirements for building Green IT, the aspects of environmental evaluation and design, and specific strategies for launching Green IT strategies and its future assignments. The conclusions of this study are as follows. First, to introduce Green Data Center as a strategy to build Green IT, the government and corporations should cooperate with each other. Partial introduction at the initial stage is desirable because, through the process, mutual trust between the two parties can be built more smoothly. Second, CEO's determination to build Green IT and continue its operation is indispensable. CEO's are required to have clear understanding as to why Green IT needs to be built and how it should be constructed. Those who initiate the construction of Green Data Center for Green IT need to know the definition and necessity of Green IT while at the same time understanding the implicit meanings of Green IT. They also need to be aware of future-oriented values of Green Data Center and readjust their corporate business activities in the pro-environmental direction. Finally, not only the CEOs' pro-environmental activities but also the change of mind on the part of all corporate employees is required to realize Green IT. It should be remembered that pro-environmental Green IT starts with minor activities.

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.463-470
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• 2015

The angular dependence of active dosimeters, EPD, is analysed and compared with that of passive dosimeters, OSLD, after evaluating their relative response and uncertainty of measurement, where it is known that the personal use of them has been increased recently. There appeared a minor variation for average relative response of OSLD in the horizontal and vertical directions within the range $0^{\circ}{\sim}{\pm}90^{\circ}$, which are 0.97 and 0.95 respectively. The variations of angular dependence in the same situations with OSLD are 0.65 and 0.62, respectively, which also reveals a negligible effect on the overall uncertainty. EPDs within the interval $0^{\circ}{\sim}{\pm}60^{\circ}$ for horizontal and vertical directions are 0.94 and 0.97, respectively. These satisfy the requirements of IEC 61526. Uncertainties about the dependence of direction from horizontal and vertical directions are 0.44, 0.40, respectively. The impact of these uncertainties on the overall uncertainty was negligible. However, we observed a significant change in reactivity: the relative reactivities for $+90^{\circ}$ and $-90^{\circ}$ from the horizontal direction are 0.60, 0.37, while that form vertical direction is 0.06. The direction dependence of OSLD was superior to EPD in the range of $0^{\circ}{\sim}{\pm}90^{\circ}$. There appeared a rapidly changing structural features in EPD response for a certain direction. Therefore, we conclude that concurrent use of passive dosimeters and auxiliary dosimeter provides accurate data for personal dose measurements.

• The Korean Journal of Air & Space Law and Policy
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• v.28 no.2
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• pp.145-181
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• 2013

General aviation is an integral part of civil aviation and involves the widest range of aviation segments except commercial aviation. Featured with different operational procedures and practices to satisfy the economic needs and safety requirements of a sovereign state, general aviation tends to be regulated by an individual state. The last three decades have seen exponential growth of commercial air transport in China, but its general aviation sector has remained disproportionally underdeveloped. With the deepening of the reform of low-altitude airspace, the sector is poised for a radical change and rapid growth. However, legislation governing general aviation activities in China is distorted causing inconsistency and confusions in their application and implementation. This paper aims to analyse China's prevailing legislation regulating general aviation activities. It first discusses the various definitions adopted by ICAO and its member states and reviews the development of general aviation in the US, EU, Australia and China. It then examines the sources of China's general aviation laws, e.g. Chicago Convention and its annexes, and Chinese domestic legislature which covers legislation, laws, directives, rules and procedures. The paper continues to analyse and establish the deficiencies of its prevailing legal framework by pointing out the following: variation of definitions in different regulations, inconsistency of principles in existing laws and regulations, legal vacuum concerning government subsidy, environment protection, safety and security, and other operational areas such as aerial club, sightseeing, and search and rescue. In this process, the paper argues that a coherent, consistent and systematic legal framework is required in order to ensure fair competition and safety for a healthy, progressive and sustainable general aviation growth. Suggestions for rectification and improvement are proposed.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.6
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• pp.7-20
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• 2017

The advancement of cloud and big data and the considerable growth of traffic have increased the complexity and problems in the management inefficiency of existing networks. The software-defined networking (SDN) environment has been developed to solve this problem. SDN enables us to control network equipment through programming by separating the transmission and control functions of the equipment. Accordingly, several studies have been conducted to improve the performance of SDN controllers, such as the method of connecting existing legacy equipment with SDN, the packet management method for efficient data communication, and the method of distributing controller load in a centralized architecture. However, there is insufficient research on the control of SDN in terms of the quality of network-using applications. To support the establishment and change of the routing paths that meet the required network service quality, we require a mechanism to identify network requirements based on a contract for application network service quality and to collect information about the current network status and identify the violations of network service quality. This study proposes a method of identifying the quality violations of network paths through ontology to ensure the network service quality of applications and provide efficient services in an SDN environment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.2
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• pp.102-105
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• 2009

The accelerated life time test of the MLCCs with different $BaTiO_3$ particle sizes were conducted at $150^{\circ}C$, 75 V condition and the effect of $BaTiO_3$ particle size on the breakdown voltage and degradation characteristics of MLCCs was investigated. The MLCCs were prepared by using the $BaTiO_3$ particles having the size of $0.525{\mu}m$, $0.555{\mu}m$, $0.580{\mu}m$ and Ni-electrode, respectively. The MLCCs which have the particle size of $0.525{\mu}m$, $0.555{\mu}m$, and $0.580{\mu}m$, respectively were confirmed to meet the standard requirements of X5R(change capacitance within ${\pm}15%$ at $-55{\sim}85^{\circ}C$) by TCC(Temperature Coefficient of Capacitance). The effect of the $BaTiO_3$ particle size on the insulation resistance behavior of MLCCs was confirmed by BDV(Breakdown Voltage) measurements and the cause and degree of degradation of MLCCs were characterized by XPS analysis after the accelerated life test. The MLCCs with $0.525{\mu}m-BaTiO_3$ showed better insulation resistance and BDV characteristics compare to other MLCCs and XPS analysis revealed that the MLCCs degradation is caused by the NiO peak and $BaTiO_3$ peak decrease.

• Journal of Korean Elementary Science Education
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• v.26 no.3
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• pp.295-308
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• 2007

The purpose of the study is to develop an effective model of a science teachers' professional development program. This study consists of two parts: (1) the theoretical review of science teachers' professional development and (2) a case study of a science teachers' professional development programme in the UK. After reviewing recent research on pedagogical content knowledge and new approaches to educational research, the following suggestions emerged: (1) Continuing Professional Development(CPD) should be embedded in teachers' real practice in the classroom and (2) embedded in the everyday life of learners' within the community. (3) CPD should support the development of teachers' communities of professional practice. The case study of 'CPD through Portfolios of Evidence' in the British programme indicated that collecting explicit evidence of good practice in the classroom and establishing agreement as to what constitutes good practice in a teachers' community helped teachers' professional development. Finally, what emerged from the case study of the CPD programme in the UK and the theoretical review of PCK was the following. An effective CPD model of science teachers should comprise these three stages: (1) providing opportunities of professional development, (2) changing practice in the classroom and research, and (3) spreading and sustaining change. The whole process is circular.