• 제목/요약/키워드: 대학원

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고온초전도 DC케이블용 LPP의 액체질소 중 DC 및 임펄스 절연파괴 특성 (DC and impulse electrical breakdown characteristics of LPP in liquid nitrogen for a HTS DC cable)

  • 곽동순;천현권;최재형;민치현;김해종;조전욱;김상현
    • 한국초전도ㆍ저온공학회논문지
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    • 제9권3호
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    • pp.52-56
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    • 2007
  • A high temperature superconducting (HTS) DC cable is ideal for transmitting large blocks of electrical power over a long distance. However, it must be designed to operate reliably within the constraints of the electrical systems. Therefore, a study of the electrical insulation is important to develop a HTS DC cable because it is operated in a cryogenic high voltage environment. This paper discusses the dielectric constructions of the cable and summarizes the experimental results on the DC and impulse dielectric characteristics of the insulation material. in sheet form and mini-model cable configuration. This shows how to design such insulation to be operated reliably. These studies are essential for the insulation design of a HTS DC cable operated in cryogenic environment.

분할형 YBCO CC들을 전위한 적층도체의 수직 자화손실 저감 특성 (Reduction Characteristics on Perpendicular Magnetization Loss in Transposed Stacking Conductor of Striated YBCO CC)

  • 이지광;변상범;한병욱;박상호;최석진;김우석;박찬;최경달
    • 한국초전도ㆍ저온공학회논문지
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    • 제11권3호
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    • pp.15-19
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    • 2009
  • Recently, it is proposed to make striations on the YBCO coated conductor and to transpose each other as one of the solutions to decrease the perpendicular magnetization loss. For large power application using HTS, the stacked conductor packing the YBCO coated conductors should be used because single conductor is limited in flowing of demanded large current. In this paper, we research the affect of the striation and continuously transposed stacking geometry on the magnetization loss in perpendicularly exposed magnetic field. Several short samples having different number of striation and continuously transposed stack are prepared and tested in perpendicularly exposed magnetic field for the magnetization loss characteristics. The magnetization loss of striated sample was lower than sample without striation. The reduction effect on magnetization loss by the striation is obviously appeared in higher field and lower number of stack and decreased as increasing the transposed stacking number. Also, the reduction effect by transposed stack is obviously appeared in lower field at lower number of striation and isn't appeared at higher striation number and higher magnetic field.

유기 은 착체 화합물을 코팅용액으로 사용하여 연속적인 담금코팅방법에 의한 은 안정화층 제조 (Preparation of silver stabilizer layer on coated conductor by continuous dip coating method using organic silver complexes)

  • 이종범;김지철;박신근;김병주;김재근;이희균;홍계원
    • 한국초전도ㆍ저온공학회논문지
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    • 제12권1호
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    • pp.1-5
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    • 2010
  • Silver stabilizing layer of coated conductor has been prepared by dip coating method using organic silver complexes containing 10 wt% silver as a starting material. Coated silver complex layer was dried in situ with hot air and converted to crystalline silver by post heat treatment in flowing oxygen atmosphere. A dense continuous silver layer with good surface coverage and proper thickness of 230 nm is obtained by multiple dip coatings and heat treatments. The film heat treated at $500^{\circ}C$ showed good mechanical adhesion and crystallographic property. The interface resistivity between superconducting YBCO layer and silver layer prepared by dip coating was measured as $0.67\;{\times}\;10^{-13}\;{\Omega}m^2$. Additional protecting copper layer with the thickness of $20\;{\mu}m$ was successfully deposited by electroplating. The critical current measured with the specimen prepared by dip coating and sputtering on same quality YBCO layer showed similar value of ~140 A and proved its ability to replace sputtering method for industrial production of coated conductor.

타입에 따른 무유도 권선형 코일의 한류 특성연구 및 자장해석 (A study on the current limiting characteristics and magnetic analysis of the non-inductively wound coil)

  • 장재영;박동근;장기성;나진배;김원철;정윤도;고태국
    • 한국초전도ㆍ저온공학회논문지
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    • 제11권1호
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    • pp.25-29
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    • 2009
  • To reduce the power loss in normal state, non-inductively wound high temperature superconducting (HTS) coils are used for fault current limiter (FCL) application. Non-inductively wound coils can be classified into two types: solenoid type and pancake type. These two types have different electrical and thermal and mechanical characteristics due to their winding structure difference. This paper deals with the current limiting characteristics, magnetic field analysis of the two coils. Simulation using finite element method (FEM) was used to analyze the magnetic field distribution and inductance of the coils. Short circuit test using stabilizer-free coated conductor (CC) was also carried out. We can compare the characteristics of the two types of coil by using the data obtained from simulation and short circuit test. We confirmed the feasibility of FCL application by the analysis about the characteristics of non-inductively wound coil using CC.

소아 선천성 근성 사경의 추나 치료 효과에 대한 임상연구 고찰 - 중의학 무작위 대조군 임상연구를 중심으로 - (A Systematic Review of Clinical Studies of Tuina Treatment on Congenital Muscular Torticollis - Focused on Chinese Randomized Controlled Trials -)

  • 권효은;오수민;장수비;최일신;김기봉;천진홍
    • 대한한방소아과학회지
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    • 제37권2호
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    • pp.12-27
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    • 2023
  • Objective This study aimed to analyze the efficacy of the tuina treatment for congenital muscular torticollis based on randomized controlled clinical studies in China. Methods The China National Knowledge Infrastructure was the main source of data. Using the keywords "tuina", "chuna", "推拿", and "斜颈", 12 randomized controlled clinical studies were identified and analyzed. Results Compared with the control group, the tuina treatment group showed statistically significant changes with respect to the therapeutic effect. Conclusions This study suggests that tuina treatment is effective for congenital muscular torticollis patients and provides evidence for further studies on oriental medicine treatments, including tuina for congenital muscular torticollis.

XAI 기법을 이용한 전자상거래의 고객 구매 행동 이해 (Understanding Customer Purchasing Behavior in E-Commerce using Explainable Artificial Intelligence Techniques)

  • 이재준;정이태;임도현;곽기영;안현철
    • 한국컴퓨터정보학회:학술대회논문집
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    • 한국컴퓨터정보학회 2021년도 제64차 하계학술대회논문집 29권2호
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    • pp.387-390
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    • 2021
  • 최근 전자 상거래 시장이 급격한 성장을 이루면서 고객들의 급변하는 니즈를 파악하는 것이 기업들의 수익에 직결되는 요소로 인식되고 있다. 이에 기업들은 고객들의 니즈를 신속하고 정확하게 파악하기 위해, 기축적된 고객 관련 각종 데이터를 활용하려는 시도를 강화하고 있다. 기존 시도들은 주로 구매 행동 예측에 중점을 두었으나 고객 행동의 전후 과정을 해석하는데 있어 어려움이 존재했다. 본 연구에서는 고객이 구매한 상품을 확정 또는 환불하는 행동을 취할 때 해당 행동이 발생하는데 있어 어떤 요소들이 작용하였는지를 파악하고, 어떤 고객이 환불할 지를 예측하는 예측 모형을 새롭게 제시한다. 예측 모형 구현에는 트리 기반 앙상블 방법을 사용해 예측력을 높인 XGBoost 기법을 적용하였으며, 고객 의도에 영향을 미치는 요소들을 파악하기 위하여 대표적인 설명가능한 인공지능(XAI) 기법 중 하나인 SHAP 기법을 적용하였다. 이를 통해 특정 고객 행동에 대한 각 요인들의 전반적인 영향 뿐만 아니라, 각 개별 고객에 대해서도 어떤 요소가 환불결정에 영향을 미쳤는지 파악할 수 있었다. 이를 통해 기업은 고객 개개인의 의사 결정에 영향을 미치는 요소를 파악하여 개인화 마케팅에 사용할 수 있을 것으로 기대된다.

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교대 근무 여부에 따른 빈혈 유병 현황 및 위험 인자에 대한 연구 (Research on the Prevalence and Risk Factors for Anemia according to Working Schedule)

  • 오은아;강성규;함승헌;최원준;이완형
    • 한국산업보건학회지
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    • 제33권2호
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    • pp.126-133
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    • 2023
  • Objectives: This study was conducted to find out the prevalence and risk factors of anemia according to shift work. Methods: Data from the Korean National Health and Nutrition Survey (2016-2020) were used. 9,787 workers were divided into shift workers and non-shift workers. The work type between 6AM-6PM was defined as day work, and other work types were defined as shift work. A chi-square test was used to indicate the distribution of risk factors expected to affect shift work in both frequency and percentage. Multiple logistic regression analysis was performed to find out the relationship between anemia prevalence and shift work. Results: As a result of analysis, multiple logistic regression analysis of anemia prevalence and shift work, the OR (95% CI) of male workers on shift work was 2.186 (1.139 to 4.194) and there was a statistically significant difference. Conclusions: In conclusion, anemia in male shift workers should be considered a possibility of health problems. In the future, research based on various data collection should be conducted for research to reveal various causes or diseases of anemia in the future.

사전학습 언어 모델을 활용한 트랜스포머 기반 텍스트 요약 (Transformer-based Text Summarization Using Pre-trained Language Model)

  • 송의석;김무성;이유린;안현철;김남규
    • 한국컴퓨터정보학회:학술대회논문집
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    • 한국컴퓨터정보학회 2021년도 제64차 하계학술대회논문집 29권2호
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    • pp.395-398
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    • 2021
  • 최근 방대한 양의 텍스트 정보가 인터넷에 유통되면서 정보의 핵심 내용을 파악하기가 더욱 어려워졌으며, 이로 인해 자동으로 텍스트를 요약하려는 연구가 활발하게 이루어지고 있다. 텍스트 자동 요약을 위한 다양한 기법 중 특히 트랜스포머(Transformer) 기반의 모델은 추상 요약(Abstractive Summarization) 과제에서 매우 우수한 성능을 보이며, 해당 분야의 SOTA(State of the Art)를 달성하고 있다. 하지만 트랜스포머 모델은 매우 많은 수의 매개변수들(Parameters)로 구성되어 있어서, 충분한 양의 데이터가 확보되지 않으면 이들 매개변수에 대한 충분한 학습이 이루어지지 않아서 양질의 요약문을 생성하기 어렵다는 한계를 갖는다. 이러한 한계를 극복하기 위해 본 연구는 소량의 데이터가 주어진 환경에서도 양질의 요약문을 생성할 수 있는 문서 요약 방법론을 제안한다. 구체적으로 제안 방법론은 한국어 사전학습 언어 모델인 KoBERT의 임베딩 행렬을 트랜스포머 모델에 적용하는 방식으로 문서 요약을 수행하며, 제안 방법론의 우수성은 Dacon 한국어 문서 생성 요약 데이터셋에 대한 실험을 통해 ROUGE 지표를 기준으로 평가하였다.

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아동의 간식섭취가 주의력 결핍 과잉행동에 미치는 영향 (The Effect of Snack Intake of Preschoolers on ADHD)

  • 주나미;김성희;박희나;이소영;김민정;정경숙
    • 한국식생활문화학회지
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    • 제21권2호
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    • pp.193-201
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    • 2006
  • The purpose of this study was to examine the relationships of snack intake and ADHD (Attention Deficit Hyperactivity Disorder) among 284 children aged $4{\sim}7$ years. The degree of ADHD (Attention Deficit Hyperactivity Disorder) were assessed by both children's mother and their teachers using Behavior check list. The subjects who had a higher ADHD (Attention Deficit Hyperactivity Disorder) score ate more pizza, hamburger, chicken, processed milk, carbonated beverage. These results indicate ADHD (Attention Deficit Hyperactivity Disorder) were related positively for snack(pizza, hamburger, chicken, processed milk, carbonated beverage etc.) intake.

위장관 간질종양의 수술 후 재발한 환자에서 발생한 Imatinib의 부작용과 효능 - 증례와 문헌고찰 (Clinical Course and Side Effects of Imatinib in Recurrent Patient after Surgical Resection of GIST - A Case and Literature Review)

  • 배정호;김광하;김동욱;이봉은;송근암
    • Journal of Digestive Cancer Research
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    • 제1권2호
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    • pp.100-103
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    • 2013
  • A 79-year-old man was diagnosed with gastrointestinal stromal tumor (GIST) of the gastric cardia. We performed proximal subtotal gastrectomy and started imatinib therapy as adjuvant treatment after surgery. Whole body skin rash with urticaria was onset on 10 days after imatinib treatment, and the patient decided to stop imatinib because of side effect. After 3 months, PET CT revealed GIST was recurred at spleen and abdominal lymph nodes, abdominal wall. The patient was then restarted on imatinib therapy. On follow-up imaging studies, the tumor almost disappeared, but both pleural effusion and pericardial effusion were found. In this paper, we describe a case of clinical course and side effects in recurred GIST after adjuvant imatinib mesylate treatment.

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