• Journal of Technologic Dentistry
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• v.29 no.2
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• pp.17-34
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• 2007

This study was conducted to research into the recognition level of employment and overseas employment on 173 students majoring in dental technology at two colleges in Daegu metropolitan city and Jeju self-governing island through questionnaires which are recorded individually. The results are as follows. 1. About 31.8% students chose dental technician department taking their aptitude into consideration when they entered college. 52% students gained information about dental technology through internet, and 57.3% students among them, which was the highest level, were under age 20. 2. 48.6% students responded that they thought the level of satisfaction with major was average and there was a difference according to their ages among the level of satisfaction or dissatisfaction with their major and the previous knowledge of major they had gained before entering college. 75.1% students said they wouldn't transfer to other major even if they were given the chance, which was much higher than the opposite case. And only 2.3% students had dissatisfaction at their major, which means students majoring dental technology evaluate their major positively. 3. Most students(58.4%) wanted to get a job for living cost and 53.2% students took advice from their seniors or elderly people in choosing their jobs. 64.7% students answered they should have professional skills to get a good job, which was different according to their ages. In addition, 51.4% students of dental technology department regarded the opportunities to exert their abilities as the most important element in choosing their jobs. That means students value self-decision and selfrealization when they choose their jobs. 4. The majority of students(32.9%) preferred to work at the dental laboratory in dental college hospital as their workplace. Moreover, seniors over age 21 wanted to work in the field of porcelain and juniors under age 20 preferred to work in the implant part concerning the field which students wants to work. 5. About 91.3% students have ever heard about overseas employment and wanted to work abroad if given the opportunities(77.5%). This points out students have much interest in overseas employment and positive attitude. And there was a difference according to age and grade in case of the preferred country when they work abroad 6. The main barrier to overseas employment was a lack of communication ability(63.0%), therefore, students thought foreign language education should be activated to improve overseas employment(26.0%). To show this more specifically, juniors thought foreign language education and internship are most important factors(both are 21.4% alike), while seniors thought foreign language education is essential(24.6%) as a way to improve overseas employment. Students also thought that participation in language study club helps to prepare for overseas employment(69.4%). When putting all these survey results together, it's very important to develop people in advance who have job ability and language ability necessary for overseas employment as well as to improve job awareness in the field of dental technology. Consequently, it's needed to seek for various ways to get a overseas job through foreign language education and overseas internship.

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.376-386
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• 2005

This study investigated to describe how the nature of science is revealed in the four natural history museums in Korea. Natural history museums are well considered as informal settings of education, and the nature of science has been one of major topics stressed in science education. Therefore, the revelation of this topic is supposedly reflected in developing museum exhibitions. In each of the four target natural history museum or natural history exhibition, the representative exhibits subtitled by scientific inquiry and cases dealing with history of science were selected for the study. The analyzing exhibits focused on whether exhibitions were labeled with emphasis on declarative description or interpretative one. In analyzing the contents, the focus was on the concerns of scientists, scientific community, social and cultural aspects, uncertainty of scientific knowledge, and providing sufficient evidences. All things considered, it was hard to conclude that every target exhibit clearly considered the nature of science as an essential element, in designing and developing their exhibitions. More deliberate input of nature of science is suggested for worldly renowned natural history museums, because previous researches keep insisting that the nature of science would be more efficiently achieved in an informal educational setting rather than in classrooms.

• Journal of The Korean Association For Science Education
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• v.35 no.4
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• pp.573-584
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• 2015

Inquiry has been consistently emphasized in science education as a crucial element for learning. Although many researchers came to agree on the importance of scientific inquiry, authentic inquiry activities are hard to be actualized in an educational context. Therefore it is required to critically examine what teachers have difficulty in teaching inquiry. In this article, we looked into inquiry-based science activities in a small group setting where pre-service science teachers faced dilemmas between cognition and practice of inquiry. A case study was conducted on eight undergraduate students who are majoring in science education. The participants attended a weekly science program for middle school students in low SES as teaching assistants and mentors, and took full care of his/her mentees during open-inquiry activities. The results were drawn by analyzing participants' personal and group interviews, participant observations, self-reports, and others. The pre-service teachers viewed the knowledge and procedure of science as an essential factor in inquiry activities along with student's spontaneous attitude. However, in the process of performing inquiry, they faced several dilemmas between ideal cognition and real activities. The aspects of dilemmas could be summarized in three pairs of opposing concepts: 'diverging inquiry or converging science', 'interest-centered inquiry or learning-centered inquiry', and 'student as the subject or student with the insufficient expertise.' We discussed ways of resolving dilemmas and alternative perspectives on scientific inquiry.

• Journal of Korea Water Resources Association
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• v.53 no.10
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• pp.903-915
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• 2020

Long-term high-resolution hydro-meteorological data has been recognized as an essential element in establishing the water resources plan. The increasing demand for spatial precipitation in various areas such as climate, hydrology, geography, ecology, and environment is apparent. However, potential limitations of the existing area-weighted and numerical interpolation methods for interpolating precipitation in high altitude areas remains less explored. The proposed PRISM (Precipitation-Elevation Regressions on Independent Slopes Model) model can produce gridded precipitation that can adequately consider topographic characteristics (e.g., slope and altitude), which are not substantially included in the existing interpolation techniques. In this study, the PRISM model was optimized with SCEM-UA (Shuffled Complex Evolution Metropolis-University of Arizona) to produce daily gridded precipitation. As a result, the minimum impact radius was calculated 9.10 km and the maximum 34.99 km. The altitude of coastal weighted was 681.03 m, the minimum and maximum distances from coastal were 9.85 km and 38.05 km. The distance weighting factor was calculated to be about 0.87, confirming that the PRISM result was very sensitive to distance. The results showed that the proposed PRISM model could reproduce the observed statistical properties reasonably well.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.17-23
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• 2020

This paper proposes a simulation model using an equivalent circuit for the development of an MMC system. The MMC has been chosen as the most suitable topology for high voltage power transmission, such as a voltage-type HVDC, and it has dozens to hundreds of sub-modules in the form of a half-bridge or full-bridge connected in series. A simulation study is essential for the development of an MMC algorithm. On the other hand, it is virtually impossible to construct and implement MMC simulation models, including hundreds or thousands of switching devices. Therefore, this paper presents an MMC equivalent model, which is easily expandable and implemented by modeling the dynamic characteristics. The voltage and current equation of the equivalent circuit was calculated using the direction of the arm current and switching signal. The model was implemented on Matlab/Simulink. In this paper, to show the validity of the model developed using Matlab/Simulink, the simulation results of a five-level MMC using the real switching element and the proposed equivalent model are shown. The validity of the proposed model was verified by showing that the current and voltage waveform in the two models match each other.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.490-496
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• 2020

A styrofoam box is used as a simple and easy freezing method to preserve animal semen as a livestock genetic source. This study optimized the methods of freezing chikso brindled cattle semen. To test the freezing box, the motility of spermatozoa was compared between two box sizes (length×width×heigh) with the dimensions of 23.5×30.5×22.5 cm and 25.5×46.5×26.5 cm. The motility of thawed sperm from brindled Korean bulls was used to confirm the efficiency of the freezing boxes. The box having a larger inner space with larger horizontal and height measurements supported better motility after thawing (60.4±5.3% vs 67.2±3.1%) with 10 min of exposure time in liquid nitrogen vapor. The optimized freezing space is estimated to be an essential element for successful freezing results and the larger box could be used for production of more than 60 frozen semen straws. These properties are also helpful to optimize the cryopreservation techniques that would control the quality and quantity of semen straws according to different animal species.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.4
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• pp.10-21
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• 2008

A forest functions classification map is an essential element for the management planning of national forests. This study was intended to make out the map at the stand level by utilizing the Forest Functions Evaluation Program(FFEP), developed by Korea Forest Research Institute. In this program, the potential of each function was evaluated in each grid cell, and then a forest functions estimation map was generated based on the optimum grid cell values in each sub-compartment unit. Finally, the program produced a forest functions classification map with consideration of the priority of the functions. The final forest functions classification map required for the national forest management planning made out overlapping those results which the rest of the forest classified referring priority functions classification map to national forest manager and classified according to the local administrative guidance and sustainable forest resources management guidance. The results indicated that the forest function classification using the FFEP program could be an efficient tool for providing the data required for national forest management planning. Also this study made a meaningful progress in the forest function classification by considering the local forest administrative guidance and sustainable forest resources management guidance.

• Journal of the Korean Regional Science Association
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• v.34 no.1
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• pp.19-30
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• 2018

Social overhead capital(SOC) is an essential element for society to be developed and operated normally. In spite of the increase in the importance of SOC, It is difficult to present the criteria for the appropriate investment of SOC. and The discussion on making SOC investments of local government is insufficient. If the local autonomy has been guaranteed, local government increases investment in regional public goods that residents prefer. Reflection of such residents preferences is the driving force to bring the efficiency of resource allocation in the decentralization theorem. In this study, the authority and autonomy of local governments are measured through local finance. and the decision-making of local governments for SOC investment is examined in point of decentralization theorem. In the empirical analysis, the elasticities of fiscal resources are estimated for facilities(road, water and sewage, irrigation canal and flood control) that local governments are involved in investment. These decisions made by metropolitan cities and provinces were different. The difference was most evident in the effect of per capita local tax on investment. These results show that metropolitan cities and provinces that have different situation made investment decisions differently. It shows that local governments reflect the preferences of the residents in making an investment. The main implication of this study is as follow. In case the role of local government in social overhead capital investment is increased, the increase in efficiency of resource allocation occurs. and The fiscal resources must be raised by local taxes rather than the financial resources from the central government.

• Toxicological Research
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• v.23 no.3
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• pp.279-287
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• 2007

Copper (Cu) is an essential trace element indispensable for brain development and function; either excess or deficiency in Cu can cause brain malfunction. While it is known that Cu and Fe homeostasis are strictly regulated in the brain, the question as to how systemic Fe status may influence brain Cu distribution was poorly understood. This study was designed to test the hypothesis that dietary Fe condition affects Cu transport into the brain, leading to an altered brain distribution of Cu. Rats were divided into 3 groups; an Fe-deficient (Fe-D) group which received an Fe-D diet ($3{\sim}5 mg$ Fe/kg), a control group that was fed with normal diet (35mg Fe/kg), and an Fe-overload group whose diet contained an Fe-O diet (20g carbonyl Fe/kg). Following a 4-week treatment, the concentration of Cu/Fe in serum, CSF (cerebrospinal fluid) and brain were determined by AAS, and the uptake rates of Cu into choroids plexus (CP), CSF, brain capillary and parenchyma were determined by an in situ brain perfusion, followed by capillary depletion. In Fe-D and Fe-O, serum Fe level decreased by 91% (p<0.01) and increased by 131% (p<0.01), respectively, in comparison to controls. Fe concentrations in all brain regions tested (frontal cortex, striatum, hippocampus, mid brain, and cerebellum) were lower than those of controls in Fe-D rats (p<0.05), but not changed in Fe-O rats. In Fe-D animals, serum and CSF Cu were not affected, while brain Cu levels in all tested regions (frontal cortex, striatum, hippocampus, mid brain, and cerebellum) were significantly increased (p<0.05). Likewise, the unidirectional transport rate constants $(K_{in})$ of Cu in CP, CSF, brain capillary and parenchyma were significantly increased (p<0.05) in the Fe-D rats. In contrast, with Fe-O, serum, CSF and brain Cu concentrations were significantly decreased as compared to controls (p<0.05). Cu transport was no significant change of Cu transport of serum in Fe-O rats. The mRNA levels of five Cu-related transporters were not affected by Fe status except DMT1 in the CP, which was increased in Fe-D and decreased in Fe-O. Our data suggest that Cu transport into brain and ensuing brain Cu levels are regulated by systemic Fe status. Fe deficiency appears to augment Cu transport by brain barriers, leading to an accumulation of Cu in brain parenchyma.

• Journal of Plant Biotechnology
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• v.37 no.2
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• pp.125-132
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• 2010

Rice is the staple food of more than 50% of the worlds population. Cultivated rice has the AA genome (diploid, 2n=24) and small genome size of only 430 megabase (haploid genome). As the sequencing of rice genome was completed by the International Rice Genome Sequencing Project (IRGSP), many researchers in the world have been working to explore the gene function on rice genome. Insertional mutagenesis has been a powerful strategy for assessing gene function. In maize, well characterized transposable elements have traditionally been used to clone genes for which only phenotypic information is available. In rice endogenous mobile elements such as MITE and Tos (Hirochika. 1997) have been used to generate gene-tagged populations. To date T-DNA and maize transposable element systems has been utilized as main insertional mutagens in rice. A main drawback of a T-DNA scheme is that Agrobacteria-mediated transformation in rice requires extensive facilities, time, and labor. In contrast, the Ac/Ds system offers the advantage of generating new mutants by secondary transposition from a single tagged gene. Revertants can be utilized to correlate phenotype with genotype. To enhance the efficiency of gene detection, advanced gene-tagging systems (i.e. activation, gene or enhancer trap) have been employed for functional genomic studies in rice. Internationally, there have been many projects to develop large scales of insertionally mutagenized populations and databases of insertion sites has been established. Ultimate goals of these projects are to supply genetic materials and informations essential for functional analysis of rice genes and for breeding using agronomically important genes. In this report, we summarize the current status of Ac/Ds-mediated gene tagging systems that has been launched by collaborative works from 2001 in Korea.