• Nuclear Engineering and Technology
• /
• 제53권2호
• /
• pp.498-508
• /
• 2021

Micro reactors are increasingly being considered for utilization as distributed power sources. Hence, the probabilistic safety assessment (PSA) of a direct supercritical-CO₂-cooled fast reactor, called micro modular reactor (MMR), was performed in this study; this reactor was developed using innovative design concepts. It adopted a modular design and passive safety systems to minimize site constraints. As the MMR is in its conceptual design phase, design weaknesses and valuable safety insights could be identified during PSA. Level 1 internal event PSA was carried out involving literature survey, system characterization, identification of initiating events, transient analyses, development of event trees and fault trees, and quantification. The initiating events and scenarios significantly contributing to core damage frequency (CDF) were determined to identify design weaknesses in MMR. The most significant initiating event category contributing to CDF was the transients with the power conversion system initially available category, owing to its relatively high occurrence frequency. Further, an importance analysis revealed that the safety of MMR can be significantly improved by improving the reliability of reactor trip and passive decay heat removal system operation. The findings presented in this paper are expected to contribute toward future applications of PSA for assessing unconventional nuclear reactors in their conceptual design phases.

• 한국지능시스템학회논문지
• /
• 제10권2호
• /
• pp.75-82
• /
• 2000

이논문에서는 영상처리 기법과 신경회로망 분류기를 이용하여 냉연강판의 표면에 나타나는 결함을 검출하는 기법을 제안한다. 냉연강판 표면의 입력영상을 웨이블렛 변환하여 영상신호 데이터량을 감소시키고 영상신호의 저주파수 영역에 해당하는 부분영상으로부터 구한 co-occurrence 행렬을 이용하여 주된 특징들을 추출한 후 신경회로망 분류기를 이용하여 표면결함을 분류하는 과정을 밟는다 현장에서 직접입수한 실제 냉연강판 표면결함 영상에 대하여 결함의 검출 및 분류기법을 제시하고 실험을 통해 기존의 백터양자화 기법과 비교하여 우수한 성능을 보임을 입증하였다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1999년도 전력전자학술대회 논문집
• /
• pp.563-568
• /
• 1999

Generally the control method of wire feeding motor in welding machine has been used full-wave phase control method. The fire-angle control generates low frequency speed ripple, and it causes the output current ripple. So it results in the variation of welding condition and low welding performances such as spatter generation and bead state. For the purpose of welding performances improvement by speed controller in wire feeding motor, in this paper the constant speed control method for welding machine is proposed. The proposed system is composed of speed control loop and current control loop. As a result of experiment by using proposed constant wire feed experiment by using proposed constant wire feed speed controller, the output voltage and current waveform and metal transfer are maintained stably. And moreover the number of instantaneous short circuit occurrence is reduced remarkably.

• ALGAE
• /
• 제21권1호
• /
• pp.11-13
• /
• 2006

In this work we report the occurrence of Scytosiphon gracilis Kogame (Scytosiphonaceae, Phaeophyceae) on the Pacific coast of Mexico. This is the first report of S. gracilis outside its previously known distribution in the western North Pacific (Korea and Japan). The identification was based on a morphological revision and a comparison of the plastid-encoded RuBisCO spacer sequences determined for Korean and Mexican algal material. Thalli were collected from the intertidal zone of Saldamando Beach, Baja California, in January 2003. The vegetative structure, as well as habitat and geographic distribution of the species are described. Reproductive structures were not found in our specimens. The poor presence/absence of S. gracilis in previous floristic studies of the area could be due to its small size and low frequency.

• 정보학연구
• /
• 제1권1호
• /
• pp.13-26
• /
• 1998

대부분의 정보검색시스템들은 부적절한 색인어들에 의해 가끔 사용자의 의도에 맞지 않는 전혀 다른 검색 결과가 나타난다. 그것은 시스템이 색인어들을 검색하기 위해 그 의미가 아닌, 단지 용어로서만 고려하기 때문이다. 검색 정확도의 증진을 위해 색인어는 연관된 용어 사용 빈도와 역 빈도 사용으로 검색되고 동시 발생어는 원시 문서로부터 추출된다. 결과적으로 색인어는 계산된 상호 정보들을 사용함으로써 그들의 세맨틱에 의해 클러스팅된다. 이 논문은 재현율의 감소없이 클라이언트 사용자 모듈로부터 피드백에 따라 세분된 세맨틱 정보를 사용하여 부적절한 검색 결과를 거절함으로써 검색 효율을 높일 수 있도록 설계하였다.

• 융합경영연구
• /
• 제10권6호
• /
• pp.1-7
• /
• 2022

Purpose: The purpose of this study is identifying the research trends of degree papers related to the beauty industry and providing information which can contribute to the development of the domestic beauty industry and the direction of various research about beauty industry. Research design, data and methodology: This study used 154 academic papers and 189 academic papers with English abstracts out of 299 academic papers. All of these papers were found by searching for the keyword "beauty industry" in ScienceON on August 15, 2022. For the analysis, BERTopic and LDA (Latent Dirichlet Allocation) analysis were conducted using Python 3.7. Also, OLS regression analysis was conducted to understand the annual increase and decrease trend of each topic derived with trend analysis. Results: As a result of word frequency analysis, the frequency of satisfaction, management, behavior, and service was found to be high. In addition, it was found that 'service', 'satisfaction' and 'customer' were frequently associated with program and relationship in the word co-occurrence frequency analysis. As a result of topic modeling, six topics were derived: 'Beauty shop', 'Health education', 'Cosmetics', 'Customer satisfaction', 'Beauty education', and 'Beauty business'. The trend analysis result of each topic confirmed that 'Beauty education' and 'Health education' are getting more attention as time goes by. Conclusions: The future studies must resolve the extreme polarization between the structure of the small beauty industry and beauty stores. Furthermore, the researches have to direct various ways to create the performance of internal personnel. The ways to maximize product capabilities such as competitive cosmetics and brands are also needed attentions.

• 산경연구논집
• /
• 제13권9호
• /
• pp.37-50
• /
• 2022

Purpose: The purpose of this study is to explore and compare research trends in Korea and overseas academic papers on social media marketing, and to present new academic perspectives for the future direction in Korea. Research design, data and methodology: We used English abstract of research paper (Korea's: 1,349, overseas': 5,036) for word frequency analysis, topic modeling, and trend analysis for each topic. Results: The results of word frequency and co-occurrence frequency analysis showed that Korea researches focused on the experiential values of users, and overseas researches focused on platforms and content. Next, 13 topics and 12 topics for Korea and overseas researches were derived from topic modeling. And, trend analysis showed that Korean studies were different from overseas in applying marketing methods to specific industries and they were interested in the short-term performance of social media marketing. Conclusions: We found that the long-term strategies of social media marketing and academic interest in the overall industry will necessary in the future researches. Also, data mining techniques will necessary to generate more general results by quantifying various phenomena in reality. Finally, we expected that continuous and various academic approaches for volatile social media is effective to derive practical implications.

• Journal of Electrical Engineering and Technology
• /
• 제7권4호
• /
• pp.576-581
• /
• 2012

A 23 W continuous wavelength $CO_2$ laser system exited by a high-frequency LCC resonant converter is adapted to cut a biodegradable rope fabricated with polybutylene succinate. As the biodegradable rope consists of three twisted strands, the thickness changes relative to the position of the laser beam and we thus propose a method to determine exact cutting depth. In order to obtain the parameters related to the rope cutting, the experimental and theoretical cutting depths are compared and analyzed for a range of laser heat sources. The melted thickness and groove width of the cut biodegradable rope are also examined. The proposed theoretical cutting depth depends on the incident power and target velocity ratio. From these experimental results, the biodegradable rope with a diameter of 22 mm can be cut with a heat source of 50 J/cm resulting in a melted thickness of 1.96 mm and a groove width of 0.65 mm. The laser system is shown to be perfect tool for the processing of biodegradable rope without the occurrence of raveling.

• 아시아태평양코퍼스연구
• /
• 제2권1호
• /
• pp.13-22
• /
• 2021

The present study employed an analytical framework that is characterised by a synthesis of quantitative and qualitative analyses with a specially designed computer software SpeechActConc to examine speech acts in business communication. The naturally occurring data from the audio recordings and the prosodic transcriptions of the business sub-corpora of the HKCSE (prosodic) are manually annotated with a speech act taxonomy for finding out the frequency of fillers, the co-occurring patterns of fillers with other speech acts, and the linguistic realisations of fillers. The discoursal function of fillers to sustain the discourse or to hold the floor has diverse linguistic realisations, ranging from a sound (e.g. 'uhuh') and a word (e.g. 'well') to sounds (e.g. 'um er') and words, namely phrase ('sort of') and clause (e.g. 'you know'). Some are even combinations of sound(s) and word(s) (e.g. 'and um', 'yes er um', 'sort of erm'). Among the top five frequent linguistic realisations of fillers, 'er' and 'um' are the most common ones found in all the six genres with relatively higher percentages of occurrence. The remaining more frequent realisations consist of clause ('you know'), word ('yeah') and sound ('erm'). These common forms are syntactically simpler than the less frequent realisations found in the genres. The co-occurring patterns of fillers and other speech acts are diverse. The more common co-occurring speech acts with fillers include informing and answering. The findings show that fillers are not only frequently used by speakers in spontaneous conversation but also mostly represented in sounds or non-linguistic realisations.

• 지능정보연구
• /
• 제27권1호
• /
• pp.47-64
• /
• 2021

전 세계적으로 퍼진 코로나 19 상황은 우리의 일상생활의 많은 부분에 영향을 끼쳤을 뿐만 아니라, 경제·사회 등 많은 부분에 걸쳐 막대한 영향력을 미치고 있다. 확진자와 사망자 수가 증가함에 따라 의료진과 대중은 불안, 우울, 스트레스 등 심리적인 문제를 겪고 있다고 한다. 장기적인 부정적인 감정은 사람들의 면역력을 감소시키고 신체적인 균형을 파괴할 수도 있으므로 코로나 19로 인한 심리적인 상태를 이해하는 것이 필수적인 상황이다. 본 연구에서는 코로나 19 감정과 관련된 뉴스 데이터를 수집하여, 텍스트 마이닝을 통해 키워드를 분류하고, 키워드 사이의 의미 네트워크 분석을 통해 단어들의 관계를 시각화하였다. 코로나 감정과 관련된 기사의 키워드에 나타난 단어들의 빈도수를 확인하고 이를 워드 클라우드로 분석하였다. 키워드 빈도 분석 결과 코로나 19 감정과 관련하여 '중국', '불안', '상황', '마음', '사회', '건강'과 같은 단어의 빈도가 높게 나타난 것을 확인할 수 있었다. 각 데이터 간 연결 중심성을 분석한 결과 키워드 중심성 네트워크에서 가장 중심적인 핵심어는 '심리'와 '코로나 19', '블루', '불안'이라는 단어가 높은 연결 중심성을 가지는 것을 확인할 수 있었다. 기사의 헤드라인에 나타난 주요 핵심어 사이의 동시 출현 빈도 네트워크를 그래프로 시각화한 결과, '코로나-블루' 쌍이 가장 굵게 표시되었고, '코로나-감정', '코로나-불안' 쌍이 비교적 굵은 선으로 표시된 것을 알 수 있었다. 코로나와 관련된 '블루'는 우울증을 의미하는 단어로, 코로나와 우울증은 이제 관심을 가져야 할 키워드임을 확인할 수 있었다. 본 연구에서는 장기화한 코로나 19 상황에서 신체적인 방역뿐만 아니라 심리적인 방역에도 힘써야 할 이 시기에 보건 정책담당자가 빠르고 복잡한 의사결정 과정에 도움이 되고자 미디어 뉴스를 모니터링 함으로써, 더욱더 쉬운 소셜 미디어 네트워크 분석 방법을 제시하고자 한다.