• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.98.1-98.1
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• 2018

소듐냉각 고속로 (SFR)는 원자력 발전의 가장 시급한 문제점으로 부각되고 있는 사용 후 핵연료를 재활용 하여 가동하는 원자로 이다. Generation IV로 명명되는 차세대 원자로 중에 하나로 국제 공동연구와 자체 연구를 통해 우리나라 고유의 기술이 축적되고 개발되고 있다. 현재 소듐냉각 고속로의 가장 큰 문제점 중의 하나는 금속핵연료와 피복관의 상호반응이다. 상호반응이 일어나면 공융현상을 일으켜 피복관의 녹는점이 낮아지고 피복관의 두께가 얇아져 원자로의 안전에 치명적인 위협이 된다. 이러한 문제를 해결하기 위해 전해도금 (electro-plating)을 활용하여 HT9 피복관 내면에 크롬을 도금하여 금속핵연료와 피복관의 상호반응을 억제하는 연구가 본 연구팀에서 진행되고 있다. 크롬과 전해도금을 코팅 물질과 코팅 방법으로 선정한 이유는 튜브 내면에 적용하기 용이하고 경제적인 코팅 방법이기 때문이다. 본 연구에서는 여러 가지 전해도금 인자 중 온도와 pulse 전류의 파형이 상호반응 방지 효과에 미치는 영향에 대하여 고찰하였다. 도금액의 온도를 $50{\sim}80^{\circ}C$, 전류 파형 중 on/off time을 1:1, 10:1, 1:10으로 하여 여러 HT9 시편을 도금하였고 모의 금속 핵연료 합금인 Ce-Nd와 확산 반응 실험을 수행하여 상호반응 방지 효과를 분석하였다. 광학현미경과 전자현미경을 이용한 미세구조 분석 결과 도금액의 온도가 $65^{\circ}C$ 이하인 시편에서는 미세균열이 심하게 발생하였고 그 균열을 통해서 물질이 확산하고 상호반응을 한다는 것이 관찰되었다. $65^{\circ}C$보다 높은 도금액의 온도에서 형성된 크롬막은 균열이 없고 상호반응 방지 효과가 좋은 것이 확인되었다. 특히 전류 파형의 on/off time이 1:1일 때 상호반응 방지 효과가 가장 좋은 것을 확인하였다. 이러한 결과는 크롬 전해도금의 코팅 조건이 상호반응 방지 효과에 매우 중요한 요인으로 작용한다는 것을 말해주고 있다.

• Journal of Wetlands Research
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• v.9 no.3
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• pp.51-61
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• 2007

In natural river, river-bed change is greatly influenced by the various factors such as river improvement, change of watershed land use, construction of dam and reservoir, gravel mining, and so on. The knowledge about river-bed change in the river is essential in the river modification, wetlands plan, and maintaining stable alluvial rivers. In this study, river-bed change in the future was predicted by investigating river channel characteristics which play dominant role in the formation of channel and based on the numerical model through river survey and the grain size analysis. The Proposed investigation and model was applied to the Geum river and the Miho stream which have been experienced river degradation due to river aggregate dredging and now seams to be stable. The result of potential river-bed change which was estimated by investigating channel characteristic including slope of channel, friction velocity, and so on is similar to that which was estimated based on the numerical model. It was found that the Geum river and the Miho stream will be stable. In the future, if considering the characteristics of river channel which is estimated by the river-bed scour, sediment, and so on, it is possible that river improvement and wetland restoration plan are established stably and naturally.

• Journal of Digital Convergence
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• v.18 no.4
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• pp.177-191
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• 2020

This study examines the effect of the self-overviewing attributes derived from agency problem on the cost behavior in franchise industry. To solve the research problem, we developed the proxies for self-overviewing attributes of domestic franchise CEO and used Anderson et al. (2003)'s cost behavior model to test hypothesis. Moreover, we grouped the self-overviewing variables for additional test. We find that operating costs are more sticky for firms which present higher CEO's self-overviewing attributes in franchise industry. Second, we find that the greater the self-overviewing tendency, more strengthened cost stickiness when sales decrease. This study is meaningful in that we developed proxies for self-overviewing propensity, such as the hypodermic behaviors of franchise CEO, which have not been performed in previous studies, to enhance future studies of franchise CEO. Futhermore, we empirically provide the effects of CEO's self-overviewing attributes on the operating costs behaviors, suggesting useful information to franchise stakeholders such as prospective start-ups, franchisee and investors.

• The Journal of the Korean bone and joint tumor society
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• v.4 no.1
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• pp.65-70
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• 1998

Osteosarcoma is the most common primary bone tumor except for multiple myeloma. Hematogenous spread of osteosarcoma presents the t1susal route of dissemination. Lung metastasis is the most common, however the lymph node involvement is quite rare. In addition, according to Mirra, radiologically detectable involvement of lymph node is an extremely rare manifestation of osteosarcoma. The authors had experienced a patient with an osteosarcoma of the right distal femur which spread to the right inguinal lymph node and lung. After preoperative chemotheraphy, a limb salvage operation was performed around the lesion of right distal femur and the right inguinal lymph nodes were dissected. A adjuvant postoperative chemotheraphy was performed. After the treatment, there was no recurrence of osteosarcoma or any other metastatic evidence for two years and 8 months.

• The Mathematical Education
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• v.60 no.1
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• pp.1-19
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• 2021

This study investigates students' conceptions of fractions from a measurement approach while providing a technological environment designed to support students' understanding of the relationships between quantities and adjustable units. 13 third-graders participated in this study and they were involved in a series of measurement tasks through task-based interviews. The tasks were devised to investigate the relationship between units and quantity through manipulations. Screencasting videos were collected including verbal explanations and manipulations. Drawing upon the theory of semiotic mediation, students' constructed concepts during interviews were coded as mathematical words and visual mediators to identify conceptual profiles using a fine-grained analysis. Two students changed their strategies to solve the tasks were selected as a representative case of the two profiles: from guessing to recursive partitioning; from using random units to making a relation to the given unit. Dragging mathematical objects plays a critical role to mediate and formulate fraction understandings such as unitizing and partitioning. In addition, static and dynamic representations influence the development of unit concepts in measurement situations. The findings will contribute to the field's understanding of how students come to understand the concept of fraction as measure and the role of technology, which result in a theory-driven, empirically-tested set of tasks that can be used to introduce fractions as an alternative way.

• The Mathematical Education
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• v.60 no.4
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• pp.431-449
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• 2021

Elementary mathematics textbooks present contents for enhancing problem solving competency. Still, teachers find teaching problem solving to be challenging. To understand the supports textbooks are suggesting, this study examined tasks from the challenging/thinking and inquiry mathematics. We analyzed 288 mathematical activities based on an analytic framework from the 2015 revised mathematics curriculum. Then, we employed latent class analysis to classify 83 mathematical tasks as a new approach to categorize tasks. As a result, execution of the problem solving process was emphasized across grade levels but understanding of problems was varied by grade levels. In addition, higher grade levels had more opportunities to be engaged in collaborative problem solving and problem posing. We identified three task profiles: 'execution focus', 'collaborative-solution focus', 'multifaceted-solution focus'. In Grade 3, about 80% of tasks were categorized as the execution profile. The multifaceted-solution was about 40% in the thinking/challenging mathematics and the execution profile was about 70% in Inquiry mathematics. The implications for developing mathematics textbooks and designing mathematical tasks are discussed.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.118-121
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• 2022

국내 산업재해 사고 사망자의 상당수가 건설업에서 발생하고 있다. 건설 현장에는 굴삭기, 크레인과 같은 중장비가 많고 높은 곳에서 작업하는 경우가 흔해 위험 요소에 노출될 가능성이 높다. 물리적 사고 외에도 작업 중 발생하는 미세먼지에는 여러 유해 인자가 존재하여 건설근로자들에게 호흡기질환과 같은 직업병을 유발한다. 정부에서는 산업현장 안전 관리의 중요성이 증가함에 따라 각종 산업재해로부터 근로자를 보호하기 위한 법안을 마련하였다. 따라서 건설 현장의 경우 산업재해를 방지하기 위해서 위험요소를 사전에 인지하고 즉각 대응할 수 있는 기술이 필요하다. 본 연구에서는 인공지능(AI)과 사물인터넷(IoT)을 통한 자동화 기술을 활용하여 24시간 안전 관리 시스템을 제안한다. 제안하는 IoT 기반 통합안전 관리 시스템은 AI를 적용한 CCTV를 통해 산업 현장을 모니터링하고, 다수의 IoT 센서가 측정한 수치를 근로자 및 관리자가 실시간으로 확인할 수 있게 하여 산업 현장 내 안전사고를 예방한다. 구체적으로 어플리케이션을 통해 미세먼지 농도, 가스 농도, 온도, 습도, 안전모 착용 여부 등을 모니터링할 수 있다. 모니터링 중에 유해물질의 농도가 일정 수치를 넘기거나 안전모를 착용하지 않은 근로자가 발견될 경우 근로자 및 관리자에게 경고 알림을 발송한다. 유해물질 농도는 IoT 센서를 통해 측정하며 안전모 착용 여부는 카메라 센서에 딥러닝 모델을 적용하여 인식하였다. 본 연구에서 제시한 통합안전관리시스템을 통해 건설현장을 비롯한 산업현장의 산업재해 감소와 근로자 안전 증진에 기여할 수 있을 것으로 기대한다.

• The Mathematical Education
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• v.61 no.1
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• pp.157-178
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• 2022

Mathematics teachers' content knowledge is an important asset for effective teaching. To enhance this asset, teacher's knowledge is required to be diagnosed and developed. In this study, we employed problem-posing and problem-solving tasks to diagnose preservice teachers' understanding of fraction multiplication. We recruited 41 elementary preservice teachers who were taking elementary mathematics methods courses in Korea and the United States and gave the tasks in their final exam. The collected data was analyzed in terms of interpreting, understanding, model, and representing of fraction multiplication. The results of the study show that preservice teachers tended to interpret (fraction)×(fraction) more correctly than (whole number)×(fraction). Especially, all US preservice teachers reversed the meanings of the fraction multiplier as well as the whole number multiplicand. In addition, preservice teachers frequently used 'part of part' for posing problems and solving posed problems for (fraction)×(fraction) problems. While preservice teachers preferred to a area model to solve (fraction)×(fraction) problems, many Korean preservice teachers selected a length model for (whole number)×(fraction). Lastly, preservice teachers showed their ability to make a conceptual connection between their models and the process of fraction multiplication. This study provided specific implications for preservice teacher education in relation to the meaning of fraction multiplication, visual representations, and the purposes of using representations.

• Korean Journal of Clinical Pharmacy
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• v.32 no.1
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• pp.47-56
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• 2022

Background: In modern society, the number of households raising companion animals increases, and the market for veterinary medicines is expanding even more. This study aims to investigate the perception of companion animal lovers' veterinary medicines, the necessity of specific guidance by pharmacists for veterinary medicines, the role of pharmacists at veterinary pharmacies, and ways to fulfill that role. Methods: This study evaluated veterinary medicines and medication guidance through Google online questionnaire targeting pet-lovers from December 20, 2021, until January 19, 2022. The questions consist of 1) characteristics of petlovers, 2) purchase history and drug recognition of veterinary drugs, 3) use of veterinary vaccines, 4) use of diagnostic kits, and 5) guidance of veterinary medicines by local pharmacists. Results: The respondents' experience purchasing veterinary drugs was as high as 94.4%. The most purchased drug was heartworm-preventing products, and vaccination was performed mainly at veterinary clinics (veterinarians). The respondents primarily purchased veterinary medicines for companion animals at veterinary hospitals and did not know the name of the drugs which they bought. In addition, respondents expected to receive specific information on veterinary medicines from pharmacists. Conclusion: As the number of veterinary pharmacies in the community will increase with the expansion of the companion animal market, pharmacists should play their role as experts in veterinary medicines through systematic and continuous professional education.

• Education of Primary School Mathematics
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• v.26 no.1
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• pp.1-13
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• 2023

One of major goals of mathematics education is to cultivate human resources which equip creative problem-solving ability. Thus, the enhancement of creative and converging ideas has been emphasized in the national curriculum since the 2009 revised curriculum. In the current study, we analyzed authorized textbook series to examine how each curriculum material addresses the creativity convergence competency. The foci of the analysis were creativity (originality, fluency, flexibility, elaboration) and convergence (intrinsic connection, extrinsic connection). In addition, we analyzed the national textbook which was based on the 2015 revised curriculum to investigate the transition between the national textbook and the authorized textbooks. We found the tasks that focused on fluency were the most frequent type regarding creativity and the tasks that connected with everyday life situations (extrinsic connection) were prevalent across the three textbook series. We provided suggestions about the development of mathematics textbooks and their implementation.