• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.17-23
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• 2017

Optical current sensors are suitable for operation in high voltage and high current environments such as power plants due to they are not affected by electromagnetic interference and have excellent insulation characteristics. However, as they operate in a harsh environment such as large temperature fluctuation and mechanical vibration, high reliability of the sensor is required. Therefore, many groups have been working on enhancing the reliability. In this work, an integrated optical current sensor incorporating polarization-rotated reflection interferometer is proposed. By integrating various optical components on a single chip, the sensor exhibits enhanced stability as well as the solution for low-cost optical sensors. Using this, we performed the characterization for the actual field application. By using a large power source, the current of 0.3 kA~36 kA was applied to the photosensor and the linear operation characteristics were observed. The error of the sensor was within $0{\pm}.5%$. Even when operating for a long time, the error range of the sensor was kept within $0{\pm}.5%$. In addition, the measurement of the frequency response over the range of 60 Hz to 10 kHz has confirmed that the 3-dB frequency band of the proposed OCT is well over 10 kHz.

• Journal of Environmental Impact Assessment
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• v.13 no.3
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• pp.125-135
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• 2004

Environmental Impact Assessment(EIA) in Korea has been used to improve environmental conservation and decision-making. Since environmental impact statement(EIS) was introduced in 1981 with the promulgation of the Environmental Preservation Act in 1977, which replaced the Pollution Control Act legislated in 1963. With a rapid growth of environmental perception as well as the diversification of development activities, however, it has recently bring about a strong demand for a new assessment process related to the strategic level of policies, plan, programs. Method of this study includes analyses of the situation of local EIA and its problematic issues through survey and analysis of information and data, analysis of the level of environmental awareness of professionals and case studies including analysis of foreign strategic environmental assessment. Accordingly, I have elicited a concept of SEA. In addition, I have studied on costs of environmental assessment, and efficiency of internalization of HIA. The survey was carried between September and November 2003, and 177 professionals were asks to complete a questionnaire. As a result of questionnaire survey of environmental pundits, it revealed that 83.8% of participants were in favor of introduction of strategic assessment. This result demonstrated more or less higher approval rate than those of awareness survey done by the Ministry of Environment, i.e. 86.0% ayes, and 14.0% nays. 22.8% of participants agreed to the opinion; "For introduction of this system, earlier is better," 50% reported having an opinion such as, "Will introduce this system in an earliest possible time after correcting problems," 26.3% reported having an opinion such as, "Let's decide the time for introduction of this system after correcting problems first,' and 0.9% reported having an opinion, "it's too early to introduce this system." Specifically, the ratio of ayes on introduction of the system marked 72.8%, and it revealed that a majority of respondents have an opinion such as, "Will introduce this system in an earliest possible time after correcting problems." As means of solutions for the problem regarding the limits of applications that existed in SEA System, factors, such as collecting a wide variety of opinions, securing experts, and faithful implementation, etc. were reported important, and in addition to these factors, respondents revealed having opinions such as, consistent research and development, reflection of public interest, establishment of professional organization, enforcement of after-management service, expanding investments in large, systemizing reference materials, and encouraging public participation, etc. To improve problems involving with present EIA system, it has been identified through this study that SEA is efficient and useful. In order to have SEA introduced successfully, it has been cleared that internalization of effectiveness of environmental cost together with HIA must be accomplished.

• Journal of Fashion Business
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• v.6 no.2
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• pp.29-40
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• 2002

Honor guards‘ dress represented by royal carriage parade. This thesis studies the ceremonial dress worn by the ceremonial troops during the Hwa-sung Hang-hang Ban-cha drawing (華城幸行班次圖) in the Chosun dynasty of King Jung-jo. The purpose of this study is to understand the national level ceremony by closely looking into the traditional ceremonial dress and the various signs that were used at these events thereby enhancing the cultural status of the Jung-jo King period. The Hwa-sung Hang-hang Ban-cha drawing(華城幸行班次圖) has its characteristics and also has commonality between the garments worn at these ceremonies. These garments are a traditional heritage brought down from many ages before and is a reflection of the changes that have occurred within our everyday life. Among these many records the Bancha-do(班次圖) is a representation of records that show what was worn by both nobles down to the ceremonial troops. The uniforms of the ceremonial troops were not only huge in size but also very diverse according to rank and grade. They used strong true colors with colorful flags, ceremonial items and musical instruments. These all added to the grandeur of the ceremony. The ceremonial flag was itself a symbol and was the core of the whole ceremony and parade. These ceremonial flags represented the heaven, sun, moon, hill and animals as well as supernatural gods. All these showed change in shape, color and content by age and time. Also the Yongmun Gichi(Dragon flag: 龍紋旗幟) is a supernatural being representing the power and wish of the ruler. The Chunsang-mun represents the indivisible relationship between man and heaven and also a metaphor for absolute power. A close look at ceremonial instruments show a direct representation towards power such as an axe, spear and sword and integrated with other large ceremonial items not only provided a shade but was also a representation of worship. These all were a more or less representation of authority. The musical instruments expressed the absolute authority of the ruler and maintained the marching order and also added grandeur to the parade. A summary of the ceremonial troops in the As seen above, these national ceremonies were a representation of the present power of authority and the will to rule. These ideas and the philosophy of “ruled by heaven” is represented here in the uniforms and the ceremony itself. The Bicentennial anniversary of the Nung - hang of February 1795 will be an excellent opportunity to show and inherit the tradition and recreation of our heritage. In this view we must look at the color and shape of traditional dress to be able to inherit and learn from our ancestors.

• Journal of the Korean Chemical Society
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• v.62 no.5
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• pp.398-411
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• 2018

The purpose of this study is to investigate the effects of research project activities using the science writing heuristic on science inquiry abilities and attitudes toward science in high school students. For this purpose, we conducted the research project activities using the science writing heuristic consisting of questioning, experimental design, observation, argument and evidence, reading, and reflection steps for 73 students of the second year of science core course in high school in Jeonnam. In order to analyze the effects of the program, we surveyed the scientific inquiry ability and attitude toward science, investigated the perception of the research project class applying science writing heuristic, and conducted interviews when there was difficulty in interpreting the results. And the results of this study are as follows. First, among the science inquiry abilities, the score of Reasoning, Hypothesis setting, Finding variables, Operational definition, Experimental design, Graphing and data interpretation, Generalization was significantly improved statistically (p<.05), but the score of Expectation was not statistically significant (p>.05). Second, among the attitudes toward science, the score of 'Leisure interest in science', 'Enjoyment of science lessons', 'Career interest in science' was significantly improved statistically (p<.05). And the score of 'Attitude to scientific inquiry' decreased but it's not significant statistically. The high school research project applying science writing heuristic had a positive effect on scientific inquiry ability and scientific attitude but it could be burden to students because it is led by students in a form different from general science class for a long time. And so continuous study on research project that minimize these disadvantages and maximize their merits is needed.

• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.120-125
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• 2008

In this study, NiCoZn ferrites with the variation of sintering temperature and chemical composition were prepared by the coprecipitation. Microstructures Crystal structure of NiCoZn ferrites were analyzed by XRD and their electric magnetic characteristics were analyzed by LCR meter and their morphology observed by SEM. We identified that these powders have a typical NiCoZn spinel structure and nanoparticles average size of 40 nm. The impurity, the initial permeability and the Q factor value are the lowest of sintered NiCoZn ferrite at $1250^{\circ}C$. Also, we measured S-parameter for $(Ni_{0.4}Co_{0.1}Zn_{0.5})Fe_2O_4$ which showed a maximum reflection loss of -3.1 dB at 6 GHz for the 2 mm thick sample. From this result, we found that the NiCoZn ferrite can be used in ferrite microwave-absorbing application at a higher frequency region (> 6 GHz).

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.2089-2092
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• 2007

Tantalum-containing metal oxides, well known for their efficiency in water splitting and H2 production, have never been used in visible light driven photodecomposition of H2S and H2 production. The present work is an attempt in this direction and investigates their efficiency. A mixed metal oxide, ZnFe2Ta2O9, with the inclusion of Fe2O3 to impart color, was prepared by the conventional ceramic route in single- and double-calcinations (represented as ZnFe2Ta2O9-SC and ZnFe2Ta2O9-DC respectively). The XRD characterization shows that both have identical patterns and reveals tetragonal structure to a major extent and a minor contribution of orthorhombic crystalline system. The UV-visible diffuse reflection spectra demonstrate the intense, coherent and wide absorption of visible light by both the catalysts, with absorption edge at 650 nm, giving rise to a band gap of 1.9 eV. Between the two catalysts, however, ZnFe2Ta2O9-DC has greater absorption in almost the entire wavelength region, which accounts for its strong brown coloration than ZnFe2Ta2O9-SC when viewed by the naked eye. In photocatalysis, both catalysts decompose H2S under visible light irradiation (λ ≥ 420 nm) and produce solar H2 at a much higher rate than previously reported catalysts. Nevertheless, ZnFe2Ta2O9-DC distinguishes itself from ZnFe2Ta2O9-SC by exhibiting a higher efficiency because of its greater light absorption. Altogether, the tantalum-containing mixed metal oxide proves its efficient catalytic role in H2S decomposition and H2 production process also.

• Journal of Korean Home Economics Education Association
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• v.25 no.2
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• pp.79-101
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• 2013

This study examined how practical reasoning processes were reflected in the revised consumer education of technology & home economics textbooks in secondary schools. Twenty-four textbooks from secondary schools for 7th to 10th grades were analyzed. Areas of textbooks analyzed were introduction, body content, learning activity, and evaluation. Analysis criteria were extracted from the previous literature regarding contents and questions dealing with practical reasoning processes and revised by a researcher of this paper. The results and conclusions of this study are as follows. The results of the analysis of the practical reasoning processes showed that, across all grades, "contexts" was the most common element, and "alternatives and means" was the second most common elements. The elements of "consequences", "action and reflection" were less represented in the textbooks, with the exception of the learning activity part. The types of practical reasoning process reflected were classified either as the entire process of reasoning being reflected or some of the process being reflected, or included in the body content. Most of these were some of the process being reflected. Since there were a lot of concept-oriented statements rather than questions, more practical reasoning questions should be developed to increase the reasoning process. In addition, a need exists to develop a variety of ways to utilize the entire practical reasoning processes in the textbooks to help teachers apply the practical reasoning processes to their lessons.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.354-361
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• 2004

This Paper describes a crack scattering model for SH wave based on the boundary integral equation(BIE) method, where the fundamental unknown is crack opening displacement(COD). When a time harmonic plane wave was incident on a 2-D isolated crack (slit) of width 2a, the COD distributions were numerically calculated as a function of ka. The calculated COD agreed well with results obtained with other methods. The far-field scattering amplitude, which completely characterizes the flaw response, was calculated in two ways. The Kirchhoff approximation and the BIE-COD exact formulation were compared in terms of incidence angle and frequency ka in a pulse-echo mode. Maximum response was obtained for both methods at the specular reflection direction. Away from the specular direction, the Kirchhoff approximation becomes less accurate. The time domain crack response was also calculated using a band-limited spectrum of center frequency 10 MHz. At oblique incidence to the crack both methods show the existence of an antisymmetric flash points occurring from the crack edge. The Kirchhoff approximation provides an exact time interval between flash points, although it unrealistically gives the same amplitude.

• Journal of Conservation Science
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• v.35 no.3
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• pp.237-244
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• 2019

In this study, we applied terahertz imaging technology to three Korean modern oil paintings ('Boy,' 'Girl,' and 'Hyehwadong Landscape'); investigated the types of inner layer information in the pictures that can be extracted with terahertz imaging technology; and analyzed the conditions for extracting them. The biggest problem in the terahertz imaging analysis we encountered was the image distortion caused by the change of the distance between the target surface and the terahertz detector, depending on the surface curvature of the target paintings. We then developed a 'working distance maintaining device' to solve this problem. As a result, the terahertz imaging technique was used to identify the base material characteristics and any patterns of damage inside, and presented the optimal conditions for identifying each characteristic. In addition, it was useful to employ the terahertz frequency-division image to check the characteristics of the background materials. To confirm coloring techniques such as brush strokes, it is effective to compare the maximum reflection peak image with the cross-section image; and to detect damage information inside the paintings that cannot be observed on the surface, to compare the cross-section image with the frequency-division image. On the other hand, according to the terahertz imaging analysis of the oil paintings, the internal structural damage marks of 'Boy' and 'Girl' were confirmed, and the artist's painting style was confirmed in 'Hyehwadong Landscape.' The above results are expected to be useful for the analysis and diagnosis of Korean modern oil paintings for their preservation.

• The Journal of the Korea Contents Association
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• v.22 no.4
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• pp.754-764
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• 2022

This study began with a reflection and review of looking back on the anti-Japanese movement of Jeju Haenyeo. The Jeju Haenyeo Anti-Japanese Movement is the largest women's solidarity movement in Korea, with the struggle for the right to survive expanding to the anti-Japanese movement. Kang Kwan-Soon of young intellectuals in Jeju carried out an enlightenment campaign and made the unfair lives of Haenyeo into song lyrics to promote the anti-Japanese consciousness. 'Song of Haenyeo' has been excluded from the record for reasons of using Japanese melodies of 'Tokyo March', not traditional folk songs, and the socialist forces behind it. The study of Jeju Haenyeo is an important basic reference for the study of the anti-Japanese movement that successfully led the Jeju Haenyeo's human rights struggle. Oral tradition songs are the most fundamental art form. Through this research to revive the spirit of the anti-Japanese movement and remember the value of their sacrifices and contributions through comparative of the two songs.