• Journal of The Korean Association For Science Education
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• v.38 no.2
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• pp.187-202
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• 2018

This study posits that a more equitable science education is possible through analyzing the sociocultural mechanisms that operate in the participation and marginalization in science learning process, and therefore aims to review research trends in this area of science education. To do so, the study analyzed 85 articles that adopted a sociocultural approach to science learning identity in major international journals. The review was organized into 1) overall trends such as the number of articles by year, country, learner's sociocultural background, research context and research methods, and 2) a more in-depth analysis of the main research problems and conceptual frameworks along with concrete research examples. The study found that the current research works in this area have contributed to broadening the idea of legitimate learners in science education by considering learners' various sociocultural identities as the positive resource for learning based on the premise that science learning occurs as identity formation through participating communities of practice, and critiquing the culture or discourses that oppress such identity formation. The studies in this area also brought up the equity issue in science education in ways which embrace various learners that had been marginalized in the traditional science class and facilitate their agency. Based on these findings, the study made a case for analyzing various sociocultural mechanisms relating to the participation and marginalization in science learning to realize 'science education for all Koreans' and proposed future research direction.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.1
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• pp.1-8
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• 2008

A two-wheel balancing vehicle, which helps people moving freely and fast, and is applied from inverted pendulum system, has been widely researched and developed, and some products are came into a market in actuality. Until now, the two-wheel balancing vehicles developed have chosen the general PID control method. In this paper, we propose a new control method to improve a control capacity for a two-wheeled balancing vehicle for human transportation. The proposed method is the fuzzy PD+I control that is one of the improved PID control, and it contains a 2input-1output fuzzy system. This fuzzy system processes signals from proportional and derivative controller, and the fuzzy output signal generates the final output by summing up integral signal. The non-linearity of the fuzzy system makes an optimal output control signal by changing weight of the proportional signal and the derivative signal in process of time. We have simulated the fuzzy PD+I control system and experimented by implementing the two-wheel balancing mobile robot to verify the advantages of the proposed fuzzy PD+I control method in comparison with general PID control. As the results of simulation and experimentation, the proposed fuzzy PD+I control method has better control performance than general PID in this system and improves it.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.26.2-26.2
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• 2010

최근에는 차세대 조명용 후보광원인 고출력 백색 LED를 개발하기 위한 경쟁이 치열하며, 이를 위해 업체가 고심하고 있는 가장 큰 문제 중의 하나가 칩에서 발생하는 열을 어떻게 관리하는가 하는 방열의 문제이다. 따라서, LED의 가장 큰 특징인 장수명을 손해보지 않기 위해서는 칩에서 발생되고 있는 열을 외부에 확산시키기 위한 기술 개발이 필수적이다. 다양한 방열소재 중 W-Cu 복합재는 W의 낮은 열팽창계수와 Cu의 높은 열전도도로 인해 방열소재로써 유망한 소재로 주목받고 있으나, 우수한 열적 특성을 발현하기 위해서는 고치밀화를 갖는 W-Cu 복합재 제조가 우선적으로 필요하다. W-Cu 복합체는 일반적으로 액상소결법을 통해 균일한 미세조직을 얻을 수 있으나, 열팽창계수를 낮추기 위해 Cu 함량이 적어지게 되면 치밀화가 어려우며 이를 해결하기 위해 나노입자를 갖는 분말을 이용하고자 하는 연구가 많이 진행되고 있다. 본 연구에서는 W과 Cu 산화물을 이용하는 것이 구성성분끼리의 편석이 발생하지 않으며, 소결성도 우수하여 양산화에 가장 접근한 방법으로 알려져 있다. 그러나, 지금까지의 얻어진 W-Cu 복합체의 경우, 분말상태에서의 얻어진 나노입자가 승온시에 마이크로 크기로 과도한 입자성장이 일어나기 때문에 소결 후에도 나노크기를 유지하기 어려울 뿐만 아니라, 구성상끼리의 응집체가 형성된다. 본 연구에서는 액상소결후에 W 입자가 Cu 기지내에 균일하게 분산되는 동시에 나노크기의 입자를 가지는 고분산 W-Cu 소결체를 얻고자 하였다. 이를 위해 금속산화물 분말의 분쇄를 위해 효과적인 방법으로 알려진 습식상태에서의 고에너지 볼밀링을 통하여 혼합된 텅스텐과 구리 산화물 분말의 수소환원공정을 통해 얻어진 100nm 이하의 입자를 가지는 W-20wt%Cu 나노복합분말을 출발분말로 사용하였다. W-20wt%Cu 나노복합분말의 성형체를 $1050^{\circ}C-1250^{\circ}C$의 온도범위에서 소결거동을 조사하였다. 그 결과, $1100^{\circ}C$ 온도에서 이론밀도에 가까운 소결밀도를 나타내었으며, 이는 기존에 비해 $100^{\circ}C$ 정도 치밀화 온도를 낮추는 결과이다. 소결체의 미세구조 관찰결과, 소결 후 약 200nm의 텅스텐 입자가 Cu내에 균일하게 분산되어 있었다. 제조된 W-Cu 시편에 대해서는 LED 응용성을 조사하기 위해 열전도도와 열팽창계수 등을 평가하였다.

• Nuclear Engineering and Technology
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• v.15 no.3
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• pp.197-206
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• 1983

The slightly hyperstoichiometric uranium dioxide, i.e. U $O_{2.005}$ and U $O_{2.01}$ within a range of the requirement for the use of a nuclear fuel, were sintered directly in an atmosphere of $CO_2$/CO mixture without any succeeding reduction process. The kinetics of sintering in the late stage were investigated for various O/U ratios. A sintering diagram, which show the relation of Temperature-Time-Density-Grain size, was established for each O/U ratio. Only by controlling the oxygen partial pressure in the sintering atmosphere, U $O_2$ pellet could be sintered very easily at low temperature 1050$^{\circ}$～120$0^{\circ}C$ with a density above 95% T.D. and average grain size above 7${\mu}{\textrm}{m}$. It was found that the rate of grain growth follows D=(Kt)$^{1}$4/ in the late stage of sintering. And the activation energies for grain growth in the final sintering stage were found to be 75, 64 and 62kca1/mo1 for U $O_{2.005}$, U $O_{2.01}$ and U $O_{2.10}$, respectively. Although no significant differences are obtained between the activation energies for different O/U ratios, the sinterability is enhanced considerably with increasing the oxygen partial pressure in the sintering atmosphere.tmosphere.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.146-151
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• 2008

In this study, batch or semi-continuous reactions, introducing site-specific carboxylic acids in ${\beta}$-1,3-glucan structures, were performed to increase water solubility and gel forming ability, using TEMPO/hypobromite with or without NaBr as catalysts. Regio-selective carboxylic acid formations were determined with infrared (IR) and $^{13}C$ nuclear magnetic resonance (NMR) spectroscopic analyses. The regio-selective reactions with and without NaBr gave oxidation yields of 92.5 and 85.6%, respectively, in the batch type, and yields of 93.9 and 86.4%, respectively, in the semi-continuous type. The reaction times in the batch and semi-continuous reactions without NaBr were delayed by 100 and 150%, respectively, as compared to those with NaBr. A combination of IR and $^{13}C$ NMR analyses were used to confirm the formation of carboxylic acids in ${\beta}$-1,3-glucan. From the batch reactions with and without NaBr, the water solubilities of oxidized products were 50.0 and 55.6%, respectively, and in the semi-continuous reactions they were 52.6 and 53.5%, respectively; while the water solubility of the native ${\beta}$-1,3-glucan was less than 1.0%. Finally, as compared to the native ${\beta}$-1,3-glucan, the gel forming ability of the reaction products was greatly increased irrespective of the presence of NaBr or the reaction type.

• The Journal of the Convergence on Culture Technology
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• v.8 no.1
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• pp.175-190
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• 2022

Abusive supervision occurs in a social context in which third-party observers react and interact with the abused victims and supervisors. Despite the importance of third-party observers' behavior in abusive supervision, research on abusive supervision has mainly focused on the dyadic relationship between direct victims and supervisors. Although in recent years research on third parties' reactions to peer abusive supervision has attracted growing attention, there are still insufficient studies examining the topic especially within domestic research in Korea. As such, this study comprehensively reviews empirical studies on third parties' reactions to peer abusive supervision and aims to broaden the scope of research in the field. Firstly, the results of previous studies show that the effects of observed peer abusive supervision are mediated by cognitive and affective processes. Secondly, previous studies are found to investigate the boundary conditions where the effects of observed peer abusive supervision can be amplified or mitigated with regard to various outcomes. Overall, compared to research on direct victims, research on third-party observers of abusive supervision is found to capture a wider spectrum of responses. In order to explain the mechanisms of this phenomena, this study thoroughly examines theoretical assumptions presented in previous studies and categorizes them into five theory types. Finally, this study identifies a couple of central methodological issues, including common method bias and inadequate model specification in the literature and suggests future research directions.

• Analyses & Alternatives
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• v.8 no.1
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• pp.137-167
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• 2024

This study sought to explain the reasons why the civic education bill failed to be enacted as many as 13 times. What we discovered as a result of our research is, first, the absence of a legislative strategy by the minority member of the national assembly on this bills. The Citizenship Education Bill was a controversial bill with great potential for ideological conflict, and after the 19th National Assembly, this bill was promoted by a minority of a specific political party. The Democratic Party's sponsoring lawmakers did not use active legislative strategies, such as exerting influence within the party to have these bills adopted as the party's platform, or developing them into major pledges for the general and presidential elections. Second, there is a consistent passive response from civic groups as well as lawmakers who signed the bill in an unfavorable public opinion environment. During the legislative process, opposing opinions were overwhelming, including concerns about the spread of leftist ideology, waste of budget and organization, and violation of neutrality and fairness in education. In addition, the passive attitude of field teachers and civic groups, who should be in charge of civic education, also served as a background for the legislative failure. Third, due to a lack of sharing of reliable information on recent theoretical research and global policy trends among stakeholders, legislation through an agreement between the ruling and opposition parties failed.

• Archives of design research
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• v.18 no.4 s.62
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• pp.277-286
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• 2005

The purpose of this study is to ascertain the design element in traditional palaces of Korea, China and Japan. It takes threesteps to proceed this study. Firstly, it needs to be established the analysis framework from the documents. In second step, the design elements - the form, the material, the pattern and the color - should be collected and investigated through the observation of the actual traditional palaces the Changduckung, the Forbidden City, the Nijo castle. The third step is the analysis of the results of the investigation of the design elements from step two. To sum up similarities and dissimilarities among the design element in traditional palaces of Korea, China and Japan is as the following It is to be noticed that the mainly common characteristics of the artistic design are 'naturalism', 'harmonious ideas' and 'confucianism'. But the representation style of the design element is differed from the country. : The typical features of China are symmetry, glassy surface by artificial process, the meandered curve, the magnificent pattern and the constrable color. In Japan, the mathematical asymmetry, made-up rough surface by artificial skill, decorativepattern with abbreviation and achromatic color are important feature of the design element. While the major features of Korean design element are asymmetrical balance with nature, rough surface by natural process, moderate pattern and harmonious color.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1087-1093
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• 2010

Autotrophic denitrification is known as an effective and economical alternative for heterotrophic denitrification using external carbon sources such as methanol. In this study, we evaluated design and operation parameters for a sulfur denitrification reactor (SDR) treating high strength nitrogen wastewater. The SDR was filled with spherical sulfur media in connected to a pilot-scale nutrient removal process (daily flow rate, $Q=18\;m^3/d$) using moving spongy media. Total nitrogen (TN) concentration of the final effluent was below the 7.0 mg TN/L because nitrate was additionally removed through autotrophic denitrificationin without adding alkalinity (initial alkalinity was $169.4{\pm}20.8\;mg$ $CaCO_3$/L). During the test period, 60~80% of nitrogen in the influent was removed even in low temperature (below $15^{\circ}C$). The alkalinity consumption for nitrate removal in SDR was $4.09{\pm}1.29$ g $CaCO_3/g$ ${NO_3}^-$-N, and the residual alkalinity of influent of SDR was higher than that of theoretical requirements for full conversion of nitrate. The consumption of sulfur was 943.8 g S/d and it was 2.4 times higher than theoretical value (400.1 g S/d) due to abrasion and loss of sulfur media in backwash, etc.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.872-879
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• 2010

Layered copper hydroxides [LCHs, $Cu_2(OH)_3{\cdot}NO_3$] has the agricultural potentials as a fungicide because of its high crystallinity, excellent anion exchange capacity, and its regular layered particle size. The study, for the first time, has synthesized LCHs in highly concentrated solution and evaluated its physicochemical properties including the crystallinity and suspension stability. Optimal synthetic condition of LCHs was determined by crystallinity and stability of suspension as follow; 1) concentrations of $Cu(NO_3)_2$ and NaOH solutions were 3.0 M respectively, 2) reaction temperature and solution pH were $25^{\circ}C$ and 6.0, respectively, and 3) aging time after reaction was 2hr. Crystallinity of LCHs enhanced with increase in pH up to 9.0. Whereas, stability of suspension was decrease by increase in crystal size. Especially, increase in reaction temperature decreased stability of suspension. XRD patterns and SEM images exhibited that LCHs had regular layered particle size with 0.2~0.8 ${\mu}m$ and high crystallinity in optimal synthetic condition. The particle size was increased with increase in reaction temperature and pH. These results showed that LCHs synthesized in highly concentrated solution exhibited high stability of suspension as well as high crystallinity suitable to their potential as a fungicide.