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Analyzing Mathematical Performances of ChatGPT: Focusing on the Solution of National Assessment of Educational Achievement and the College Scholastic Ability Test (ChatGPT의 수학적 성능 분석: 국가수준 학업성취도 평가 및 대학수학능력시험 수학 문제 풀이를 중심으로)

  • Kwon, Oh Nam;Oh, Se Jun;Yoon, Jungeun;Lee, Kyungwon;Shin, Byoung Chul;Jung, Won
    • Communications of Mathematical Education
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    • v.37 no.2
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    • pp.233-256
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    • 2023
  • This study conducted foundational research to derive ways to use ChatGPT in mathematics education by analyzing ChatGPT's responses to questions from the National Assessment of Educational Achievement (NAEA) and the College Scholastic Ability Test (CSAT). ChatGPT, a generative artificial intelligence model, has gained attention in various fields, and there is a growing demand for its use in education as the number of users rapidly increases. To the best of our knowledge, there are very few reported cases of educational studies utilizing ChatGPT. In this study, we analyzed ChatGPT 3.5 responses to questions from the three-year National Assessment of Educational Achievement and the College Scholastic Ability Test, categorizing them based on the percentage of correct answers, the accuracy of the solution process, and types of errors. The correct answer rates for ChatGPT in the National Assessment of Educational Achievement and the College Scholastic Ability Test questions were 37.1% and 15.97%, respectively. The accuracy of ChatGPT's solution process was calculated as 3.44 for the National Assessment of Educational Achievement and 2.49 for the College Scholastic Ability Test. Errors in solving math problems with ChatGPT were classified into procedural and functional errors. Procedural errors referred to mistakes in connecting expressions to the next step or in calculations, while functional errors were related to how ChatGPT recognized, judged, and outputted text. This analysis suggests that relying solely on the percentage of correct answers should not be the criterion for assessing ChatGPT's mathematical performance, but rather a combination of the accuracy of the solution process and types of errors should be considered.

Analysis of the Effect of the Etching Process and Ion Injection Process in the Unit Process for the Development of High Voltage Power Semiconductor Devices (고전압 전력반도체 소자 개발을 위한 단위공정에서 식각공정과 이온주입공정의 영향 분석)

  • Gyu Cheol Choi;KyungBeom Kim;Bonghwan Kim;Jong Min Kim;SangMok Chang
    • Clean Technology
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    • v.29 no.4
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    • pp.255-261
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    • 2023
  • Power semiconductors are semiconductors used for power conversion, transformation, distribution, and control. Recently, the global demand for high-voltage power semiconductors is increasing across various industrial fields, and optimization research on high-voltage IGBT components is urgently needed in these industries. For high-voltage IGBT development, setting the resistance value of the wafer and optimizing key unit processes are major variables in the electrical characteristics of the finished chip. Furthermore, the securing process and optimization of the technology to support high breakdown voltage is also important. Etching is a process of transferring the pattern of the mask circuit in the photolithography process to the wafer and removing unnecessary parts at the bottom of the photoresist film. Ion implantation is a process of injecting impurities along with thermal diffusion technology into the wafer substrate during the semiconductor manufacturing process. This process helps achieve a certain conductivity. In this study, dry etching and wet etching were controlled during field ring etching, which is an important process for forming a ring structure that supports the 3.3 kV breakdown voltage of IGBT, in order to analyze four conditions and form a stable body junction depth to secure the breakdown voltage. The field ring ion implantation process was optimized based on the TEG design by dividing it into four conditions. The wet etching 1-step method was advantageous in terms of process and work efficiency, and the ring pattern ion implantation conditions showed a doping concentration of 9.0E13 and an energy of 120 keV. The p-ion implantation conditions were optimized at a doping concentration of 6.5E13 and an energy of 80 keV, and the p+ ion implantation conditions were optimized at a doping concentration of 3.0E15 and an energy of 160 keV.

A Study on the Status of Startups and Their Nurturing Plans: Focusing on Startups in Seongnam City (스타트업 실태 및 육성방안에 관한 연구: 성남시 스타트업을 중심으로)

  • Han, Kyu-Dong;Jeon, Byung-Hoon
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.17 no.5
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    • pp.67-80
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    • 2022
  • This study was conducted to derive policy measures such as fostering and supporting by examining the actual conditions of domestic startups. The subject of this study was the start-ups located in Seongnam-si, where Pangyo Techno Valley, which is the highest-level innovation cluster in Korea and is evaluated as a start-up mecca. Startups were defined as startups under 7 years old based on new technologies such as IT, BT, and CT, and the subjects of the study were selected. This can be seen as a step forward from previous research in that it embodies the concept of a startup that was previously abstract in a quantitatively measurable way. As a result of the analysis, about 94% of startups are distributed in the so-called "Death Valley" growth stage, and startups above scale-up, which means full-scale growth beyond BEP, account for about 6%. appeared to be occupied. He cited the problem of start-up funds as the biggest difficulty in the early stages of startups, and cited the loan evaluation method that prioritizes sales or collateral in raising funds as the biggest problem. In addition, start-ups rated the access to private investment capital such as VC, AC, and angel investors at a low level compared to policy funds, which are public funds. Most startups showed a lot of interest in overseas expansion, and they chose matching overseas investors such as overseas VCs as the biggest support for overseas expansion. The overall competitiveness in the overseas market was 49.6 points, which is less than 50 points out of 100, indicating that the overall competitiveness was somewhat inferior. It was analyzed that public support and investment in overseas sales channels (sales channels, distribution networks, etc.) should be prioritized along with enhancement of technological competitiveness in order for domestic startups to increase their competitiveness in overseas markets as well as in the domestic market.

Exploring the Model of Social Enterprise in Sport: Focused on Organization Form(Type) and Task (스포츠 분야 사회적기업의 모델 탐색: 조직형태 및 과제)

  • Sang-Hyun Park;Joo-Young Park
    • Journal of Industrial Convergence
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    • v.22 no.2
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    • pp.73-83
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    • 2024
  • The purpose of this study is to diagnose various problems arising around social enterprises in the sport field from the perspective of the organization and derive necessary tasks and implications. In order to achieve the purpose of the study, the study was largely divided into three stages, and the results were derived. First, the main status and characteristics of social enterprises in the sport field were examined. The current status was analyzed focusing on aspects such as background and origin, legislation and policy, organizational goals, organizational structure and procedures, and organizational characteristics. Social enterprises in the sport sector were in their early stages, and the government's social enterprise policy goal tended to focus on increasing the number of social enterprises in a short period of time through financial input. In addition, it was found that most individual companies rely on government subsidy support due to insufficient profit generation capacity. In the second stage, we focused on the situational factors that affect the functional performance of social enterprises in the sport field. As a result of reviewing the value, ideology, technology, and history of the organization, which are situational factors, it was derived that when certified as a social enterprise in the sport field and supported by the central government or local governments, political control is strong to some extent and exposure to the market is not severe. In the last third step, tasks and implications were derived to form an appropriate organization for social enterprises in the sport field. After the social enterprise ecosystem in the sport sector has been established to some extent, it is necessary to gradually move from the current "government-type" organization to the "national enterprise" organization. This is true in light of the government's limited financial level, not in the short term, but in order for the organization of social enterprises in the sports sector to survive in the long term.

Development of deep learning network based low-quality image enhancement techniques for improving foreign object detection performance (이물 객체 탐지 성능 개선을 위한 딥러닝 네트워크 기반 저품질 영상 개선 기법 개발)

  • Ki-Yeol Eom;Byeong-Seok Min
    • Journal of Internet Computing and Services
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    • v.25 no.1
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    • pp.99-107
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    • 2024
  • Along with economic growth and industrial development, there is an increasing demand for various electronic components and device production of semiconductor, SMT component, and electrical battery products. However, these products may contain foreign substances coming from manufacturing process such as iron, aluminum, plastic and so on, which could lead to serious problems or malfunctioning of the product, and fire on the electric vehicle. To solve these problems, it is necessary to determine whether there are foreign materials inside the product, and may tests have been done by means of non-destructive testing methodology such as ultrasound ot X-ray. Nevertheless, there are technical challenges and limitation in acquiring X-ray images and determining the presence of foreign materials. In particular Small-sized or low-density foreign materials may not be visible even when X-ray equipment is used, and noise can also make it difficult to detect foreign objects. Moreover, in order to meet the manufacturing speed requirement, the x-ray acquisition time should be reduced, which can result in the very low signal- to-noise ratio(SNR) lowering the foreign material detection accuracy. Therefore, in this paper, we propose a five-step approach to overcome the limitations of low resolution, which make it challenging to detect foreign substances. Firstly, global contrast of X-ray images are increased through histogram stretching methodology. Second, to strengthen the high frequency signal and local contrast, we applied local contrast enhancement technique. Third, to improve the edge clearness, Unsharp masking is applied to enhance edges, making objects more visible. Forth, the super-resolution method of the Residual Dense Block (RDB) is used for noise reduction and image enhancement. Last, the Yolov5 algorithm is employed to train and detect foreign objects after learning. Using the proposed method in this study, experimental results show an improvement of more than 10% in performance metrics such as precision compared to low-density images.

A Psychological Interpretation of Fairly Tale Mokdoryung, Son of Tree (한국민담 '목(木)도령'의 분석심리학적 해석)

  • Jin-Sook Kim
    • Sim-seong Yeon-gu
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    • v.25 no.2
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    • pp.224-264
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    • 2010
  • A brief story of the tale follows : Mokdoryung was a son of an arbor tree and a fairly. When the boy was 7-8 years old, mother-fairy returned to the sky. By using father-tree, Mokdoryung survived from the flood where he saved ants, mosquitos, and a boy with the same age. They arrived on top of the highest mountain, met an old woman with two daughters, worked as servants. With help of insects, Mokdoryung passed the trials, married to a wise daughter and 2 couples became the ancestor of the mankind. Interpretation of the tale starts with amplification of tree which symbolizes Self and Libido. As the son of the tree-spirit and a fairly from the sky, Mokdoryung is a kind of 'divine child' which represents a psychic possibility to understand archetypal nature of unconscious. Adversities of early childhood due to mother's absence regarded as necessary condition for 'divine child' to attain highest good. Flood can be compensation of absence of feminine as well as to bring a new life. The notion of father·tree becomes a kind of life-boat has to do with union of opposite(vertical phallic tree and horizontal feminine boat). Ants and mosquitoes represent upper and lower level of unconsciousness, they mediate divine power. Therefore respecting insects means respecting unconscious, and reward of insects means salvation come from unconscious. The boy saved from the flood presents emergence of psychic energy in its latent unconscious condition to create mental dynamism. The old woman is Great Mother or anima, the controller or guider of unconscious. Working as servants can be an active service for the divine marriage. Trials of separating millet from sand, and finding right direction relate to separatio, means one needs to be separated from unconscious before conunctio, union of opposite. Two sets of couple becoming ancestor of man-kind has to do with number 4 (quaternity) as well as regeneration. Although the tale includes both positive couple (Mokdoryung, wise daugther in east room). and negative couple(shadow side of Mokdoryung, step daughter in west room)as ancestors of mankind, "Good" seems to be more valued than "evil".

A Discovery of the Creative Healing Properties in the Unconscious of Alcoholics: From the Perspective of Analytical Psychology (알코올 중독에서 발견되는 무의식의 창조적 치유 활동: 분석심리학의 관점에서)

  • Kihong Baek
    • Sim-seong Yeon-gu
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    • v.39 no.1
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    • pp.129-183
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    • 2024
  • This study is an attempt to get closer to the psychological truth of alcohol addiction. After reviewing previous related studies, the experiences of Korean alcoholics were examined, encompassing both the conscious and unconscious aspects. In order to approach the unconscious, the researcher paid attention to the series of dreams that the patients reported, from the perspective of Jungian dream analysis. Working with dreams brought considerable benefits in increasing patient's involvement in the therapeutic process and fostering therapist-patient alliance. It also helped to understand patients' conscious and unconscious aspects further. The results were as follows. On the conscious level, patients showed a long-standing alienation from their true emotional needs, a lack of sufficient experience in genuinely expressing and being accepted with one's own emotion, resulting in the need for emotional re-experience, along with the intense longing for maternal affection. This also meant that they were in need for maternal re-experience, and at the same time, for the associated paternal re-experience. Furthermore, the researcher identified that certain powerful archetypal complexes had been activated in the patient's unconscious in response to their conscious situations, triggering the destructive shadows to emerge and exert a strong influence on their conscious lives. The series of reported dreams shows how the unconscious always properly and diligently compensates, modifying the perspective and attitude of the conscious and gradually opening the doors to healing, even for alcoholic patients. This indicates that the unconscious carries out a specific and consistent guidance role so the conscious can realize and adequately respond to it, and that it also provides the creative force for transforming the conscious life. These findings suggest that alcohol addiction is a psychological condition that can jeopardize one's life by allowing the powerful energy of the unconscious to penetrate the conscious, but at the same time, have the purpose and direction to urge the creative transformation of one's conscious life. From these results, it can be concluded that the first step towards true recovery is for the individual to turn their attention towards the psychological truth occurring within themselves. In this regard, the therapist's role is crucial. This also suggests that various attempts in the field of addiction treatment will blossom their real values when they contribute, directly or indirectly, to the development of one's self-awareness since as long as one continues to turn away from the psychological truth and persist in craving for false objects, their creative healing properties in the unconscious could rather have negative and destructive impacts on their life.

Seeking a Better Place: Sustainability in the CPG Industry (추심경호적지방(追寻更好的地方): 유포장적소비품적산업적가지속발전(有包装的消费品的产业的可持续发展))

  • Rapert, Molly Inhofe;Newman, Christopher;Park, Seong-Yeon;Lee, Eun-Mi
    • Journal of Global Scholars of Marketing Science
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    • v.20 no.2
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    • pp.199-207
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    • 2010
  • For us, there is virtually no distinction between being a responsible citizen and a successful business... they are one and the same for Wal-Mart today." ~ Lee Scott, al-Mart CEO after the 2005 Katrina disaster; cited in Green to Gold (Esty and Winston 2006). Lee Scott's statement signaled a new era in sustainability as manufacturers and retailers around the globe watched the world's largest mass merchandiser confirm its intentions with respect to sustainability. For decades, the environmental movement has grown, slowly bleeding over into the corporate world. Companies have been born, products have been created, academic journals have been launched, and government initiatives have been undertaken - all in the pursuit of sustainability (Peattie and Crane 2005). While progress has been admittedly slower than some may desire, the emergence and entrance of environmentally concerned mass merchandisers has done much to help with sustainable efforts. To better understand this movement, we incorporate the perspectives of both executives and consumers involved in the consumer packaged goods (CPG) industry. This research relies on three underlying themes: (1) Conceptual and anecdotal evidence suggests that companies undertake sustainability initiatives for a plethora of reasons, (2) The number of sustainability initiatives continues to increase in the consumer packaged goods industries, and (3) That it is, therefore, necessary to explore the role that sustainability plays in the minds of consumers. In light of these themes, surveys were administered to and completed by 143 college students and 101 business executives to assess a number of variables in regards to sustainability including willingness-to-pay, behavioral intentions, attitudes, willingness-to-pay, and preferences. Survey results indicate that the top three reasons why executives believe sustainability to be important include (1) the opportunity for profitability, (2) the fulfillment of an obligation to the environment, and (3) a responsibility to customers and shareholders. College students identified the top three reasons as (1) a responsibility to the environment, (2) an indebtedness to future generations, and (3) an effective management of resources. While the rationale for supporting sustainability efforts differed between college students and executives, the executives and consumers reported similar responses for the majority of the remaining sustainability issues. Furthermore, when we asked consumers to assess the importance of six key issues (healthcare, economy, education, crime, government spending, and environment) previously identified as important to consumers by Gallup Poll, protecting the environment only ranked fourth out of the six (Carlson 2005). While all six of these issues were identified as important, the top three that emerged as most important were (1) improvements in education, (2) the economy, and (3) health care. As the pursuit and incorporation of sustainability continues to evolve, so too will the expected outcomes. New definitions of performance that reflect the social/business benefits as well as the lengthened implementation period are relevant and warranted (Ehrenfeld 2005; Hitchcock and Willard 2006). We identified three primary categories of outcomes based on a literature review of both anecdotal and conceptual expectations of sustainability: (1) improvements in constituent satisfaction, (2) differentiation opportunities, and (3) financial rewards. Within each of these categories, several specific outcomes were identified resulting in eleven different outcomes arising from sustainability initiatives. Our survey results indicate that the top five most likely outcomes for companies that pursue sustainability are: (1) green consumers will be more satisfied, (2) company image will be better, (3) corporate responsibility will be enhanced, (4) energy costs will be reduced, and (5) products will be more innovative. Additionally, to better understand the interesting intersection between the environmental "identity" of a consumer and the willingness to manifest that identity with marketplace purchases, we extended prior research developed by Experian Research (2008). Accordingly, respondents were categorized as one of four types of green consumers (Behavioral Greens, Think Greens, Potential Greens, or True Browns) to garner a better understanding of the green consumer in addition to assisting with a more effective interpretation of results. We assessed these consumers' willingness to engage in eco-friendly behavior by evaluating three options: (1) shopping at retailers that support environmental initiatives, (2) paying more for products that protect the environment, and (3) paying higher taxes so the government can support environmental initiatives. Think Greens expressed the greatest willingness to change, followed by Behavioral Greens, Potential Greens, and True Browns. These differences were all significant at p<.01. Further Conclusions and Implications We have undertaken a descriptive study which seeks to enhance our understanding of the strategic domain of sustainability. Specifically, this research fills a gap in the literature by comparing and contrasting the sustainability views of business executives and consumers with specific regard to preferences, intentions, willingness-to-pay, behavior, and attitudes. For practitioners, much can be gained from a strategic standpoint. In addition to the many results already reported, respondents also reported than willing to pay more for products that protect the environment. Other specific results indicate that female respondents consistently communicate a stronger willingness than males to pay more for these products and to shop at eco-friendly retailers. Knowing this additional information, practitioners can now have a more specific market in which to target and communicate their sustainability efforts. While this research is only an initial step towards understanding similarities and differences among practitioners and consumers regarding sustainability, it presents original findings that contribute to both practice and research. Future research should be directed toward examining other variables affecting this relationship, as well as other specific industries.

A Contemplation on Measures to Advance Logistics Centers (물류센터 선진화를 위한 발전 방안에 대한 소고)

  • Sun, Il-Suck;Lee, Won-Dong
    • Journal of Distribution Science
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    • v.9 no.1
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    • pp.17-27
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    • 2011
  • As the world becomes more globalized, business competition becomes fiercer, while consumers' needs for less expensive quality products are on the increase. Business operations make an effort to secure a competitive edge in costs and services, and the logistics industry, that is, the industry operating the storing and transporting of goods, once thought to be an expense, begins to be considered as the third cash cow, a source of new income. Logistics centers are central to storage, loading and unloading of deliveries, packaging operations, and dispensing goods' information. As hubs for various deliveries, they also serve as a core infrastructure to smoothly coordinate manufacturing and selling, using varied information and operation systems. Logistics centers are increasingly on the rise as centers of business supply activities, growing beyond their previous role of primarily storing goods. They are no longer just facilities; they have become logistics strongholds that encompass various features from demand forecast to the regulation of supply, manufacturing, and sales by realizing SCM, taking into account marketability and the operation of service and products. However, despite these changes in logistics operations, some centers have been unable to shed their past roles as warehouses. For the continuous development of logistics centers, various measures would be needed, including a revision of current supporting policies, formulating effective management plans, and establishing systematic standards for founding, managing, and controlling logistics centers. To this end, the research explored previous studies on the use and effectiveness of logistics centers. From a theoretical perspective, an evaluation of the overall introduction, purposes, and transitions in the use of logistics centers found issues to ponder and suggested measures to promote and further advance logistics centers. First, a fact-finding survey to establish demand forecast and standardization is needed. As logistics newspapers predicted that after 2012 supply would exceed demand, causing rents to fall, the business environment for logistics centers has faltered. However, since there is a shortage of fact-finding surveys regarding actual demand for domestic logistic centers, it is hard to predict what the future holds for this industry. Accordingly, the first priority should be to get to the essence of the current market situation by conducting accurate domestic and international fact-finding surveys. Based on those, management and evaluation indicators should be developed to build the foundation for the consistent advancement of logistics centers. Second, many policies for logistics centers should be revised or developed. Above all, a guideline for fair trade between a shipper and a commercial logistics center should be enacted. Since there are no standards for fair trade between them, rampant unfair trades according to market practices have brought chaos to market orders, and now the logistics industry is confronting its own difficulties. Therefore, unfair trade cases that currently plague logistics centers should be gathered by the industry and fair trade guidelines should be established and implemented. In addition, restrictive employment regulations for foreign workers should be eased, and logistics centers should be charged industry rates for the use of electricity. Third, various measures should be taken to improve the management environment. First, we need to find out how to activate value-added logistics. Because the traditional purpose of logistics centers was storage and loading/unloading of goods, their profitability had a limit, and the need arose to find a new angle to create a value added service. Logistic centers have been perceived as support for a company's storage, manufacturing, and sales needs, not as creators of profits. The center's role in the company's economics has been lowering costs. However, as the logistics' management environment spiraled, along with its storage purpose, developing a new feature of profit creation should be a desirable goal, and to achieve that, value added logistics should be promoted. Logistics centers can also be improved through cost estimation. In the meantime, they have achieved some strides in facility development but have still fallen behind in others, particularly in management functioning. Lax management has been rampant because the industry has not developed a concept of cost estimation. The centers have since made an effort toward unification, standardization, and informatization while realizing cost reductions by establishing systems for effective management, but it has been hard to produce profits. Thus, there is an urgent need to estimate costs by determining a basic cost range for each division of work at logistics centers. This undertaking can be the first step to improving the ineffective aspects of how they operate. Ongoing research and constant efforts have been made to improve the level of effectiveness in the manufacturing industry, but studies on resource management in logistics centers are hardly enough. Thus, a plan to calculate the optimal level of resources necessary to operate a logistics center should be developed and implemented in management behavior, for example, by standardizing the hours of operation. If logistics centers, shippers, related trade groups, academic figures, and other experts could launch a committee to work with the government and maintain an ongoing relationship, the constraint and cooperation among members would help lead to coherent development plans for logistics centers. If the government continues its efforts to provide financial support, nurture professional workers, and maintain safety management, we can anticipate the continuous advancement of logistics centers.

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Evaluation of Radiation Exposure to Nurse on Nuclear Medicine Examination by Use Radioisotope (방사성 동위원소를 이용한 핵의학과 검사에서 병동 간호사의 방사선 피폭선량 평가)

  • Jeong, Jae Hoon;Lee, Chung Wun;You, Yeon Wook;Seo, Yeong Deok;Choi, Ho Yong;Kim, Yun Cheol;Kim, Yong Geun;Won, Woo Jae
    • The Korean Journal of Nuclear Medicine Technology
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    • v.21 no.1
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    • pp.44-49
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    • 2017
  • Purpose Radiation exposure management has been strictly regulated for the radiation workers, but there are only a few studies on potential risk of radiation exposure to non-radiation workers, especially nurses in a general ward. The present study aimed to estimate the exact total exposure of the nurse in a general ward by close contact with the patient undergoing nuclear medicine examinations. Materials and Methods Radiation exposure rate was determined by using thermoluminescent dosimeter (TLD) and optical simulated luminescence (OSL) in 14 nurses in a general ward from October 2015 to June 2016. External radiation rate was measured immediately after injection and examination at skin surface, and 50 cm and 1 m distance from 50 patients (PET/CT 20 pts; Bone scan 20 pts; Myocardial SPECT 10 pts). After measurement, effective half-life, and total radiation exposure expected in nurses were calculated. Then, expected total exposure was compared with total exposures actually measured in nurses by TLD and OSL. Results Mean and maximum amount of radiation exposure of 14 nurses in a general ward were 0.01 and 0.02 mSv, respectively in each measuring period. External radiation rate after injection at skin surface, 0.5 m and 1 m distance from patients was as following; $376.0{\pm}25.2$, $88.1{\pm}8.2$ and $29.0{\pm}5.8{\mu}Sv/hr$, respectively in PET/CT; $206.7{\pm}56.6$, $23.1{\pm}4.4$ and $10.1{\pm}1.4{\mu}Sv/hr$, respectively in bone scan; $22.5{\pm}2.6$, $2.4{\pm}0.7$ and $0.9{\pm}0.2{\mu}Sv/hr$, respectively in myocardial SPECT. After examination, external radiation rate at skin surface, 0.5 m and 1 m distance from patients was decreased as following; $165.3{\pm}22.1$, $38.7{\pm}5.9$ and $12.4{\pm}2.5{\mu}Sv/hr$, respectively in PET/CT; $32.1{\pm}8.7$, $6.2{\pm}1.1$, $2.8{\pm}0.6$, respectively in bone scan; $14.0{\pm}1.2$, $2.1{\pm}0.3$, $0.8{\pm}0.2{\mu}Sv/hr$, respectively in myocardial SPECT. Based upon the results, an effective half-life was calculated, and at 30 minutes after examination the time to reach normal dose limit in 'Nuclear Safety Act' was calculated conservatively without considering a half-life. In oder of distance (at skin surface, 0.5 m and 1 m distance from patients), it was 7.9, 34.1 and 106.8 hr, respectively in PET/CT; 40.4, 199.5 and 451.1 hr, respectively in bone scan, 62.5, 519.3 and 1313.6 hr, respectively in myocardial SPECT. Conclusion Radiation exposure rate may differ slightly depending on the work process and the environment in a general ward. Exposure rate was measured at step in the general examination procedure and it made our results more reliable. Our results clearly showed that total amount of radiation exposure caused by residual radioactive isotope in the patient body was neglectable, even comparing with the natural radiation exposure. In conclusion, nurses in a general ward were much less exposed than the normal dose limit, and the effects of exposure by contacting patients undergoing nuclear medicine examination was ignorable.

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