• 한국군사과학기술학회지
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• 제9권2호
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• pp.42-52
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• 2006

Tube erosion can be defined as a phenomenon for an increment of bore diameter, a declination of accuracy and utility of tube by firing. This study introduces the characteristics of tube life for the 155 mm K9 SHP Using a tube history book with bore measurement data and firing data of standard charge, this study analyzed the EFC vs Tube life and EFC with heat transfer effect formula as a consideration of continuous firing vs tube life. The results were compared with Firing Table(FT 155-K9-1) after the analysis. Also, this study suggests that CN98 tube can be rifled as 1000 EFC through the severe condition with continuous firing.

• 한국산업보건학회지
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• 제18권1호
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• pp.20-31
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• 2008

A respirator is useful to protect a worker from the harmful gases and vapors in the workplace, and the evaluation of respirator cartridge service life is important for the worker's health and safety. The performance of cartridge is effected by several factors such as concentration of gas and vapor, humidity, temperature, adsorbents and cartridge packing density. Adsorption model was applied to both sampling tube and respirator cartridge to predict the service life for organic vapors. The variables of the adsorption model were measured from the experiment with the sampling tube, and it was used to predict the service life of respirator cartridge. In the experiment, we used carbon tetrachloride as a organic vapor and activated carbon take out respirator cartridge as activated carbon. As a result, it was possible to predict the service life of respirator cartridge and predicted service life was quite correct. Breakthrough time decreased with increase of CCl4 concentration. In case of sampling tube, adsorbed amount of CCl4 was larger than respirator cartridge due to linear velocity. Also, rate constant of sampling tube was larger than respirator cartridge, because of, effect of flow rate, packing density. In the prediction of service life of respirator cartridge by using sampling tube, the time required for 50% contaminant breakthrough(${\tau}$) is more effective than the rate constant(k').

• Tribology and Lubricants
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• 제24권6호
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• pp.362-367
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• 2008

Tubes in nuclear steam generators are held up by supports because the tubes are long and slender. Fluid flows of high-pressure and high-temperature in the tubes cause oscillating motions between tubes and supports. This is called as FIV (flow induced vibration), which causes fretting wear in contact parts of tube-support. The fretting wear of tube-support can threaten the safety of nuclear power plant. The tube and support materials were Inconel 690 and STS 409. The wear tests were conducted in various environments, which are in water without flow, in flowing water and in flowing water with air. The results showed that the flow of water influenced on the wear-life of tube. The wear-life of tube decreased in water flow as compared with wear-life in stationary water.

• 한국안전학회지
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• 제11권4호
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• pp.72-78
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• 1996

The breakthrough curves of a sampling tube were studied to predict the service life of a respirator cartridge for organic vapors. The fixed bed adsorption model was applied to respirator cartridge and it's variables were calculated from tile experiment of sampling tube. By the experiment and simulation, it was possible to predict the service life of a respirator cartridge, however, not adequate at low $CCl_4$ concentration less than 700ppm and at high air humidify. The breakthrough curves of sampling tube were irregular compare to that of respirator cartridge due to .packing density.

• Steel and Composite Structures
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• 제19권3호
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• pp.585-599
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• 2015

This paper presents the experimental work on fatigue life and specific fatigue strength of circular hollow sectioned steel tube and wood filled circular hollow section steel tube. Burning effect was observed in the case of circular hollow sectioned steel tube when it is subjected to Maximum bending moment of 19613.30 N-mm at 4200 rpm, but this did not happen in the case of wood filled hollow section. Statistical analysis was done based on the experimental data and relations have been built to predict the number of cycles for the applied stress or vice versa. The relations built in this paper can safely be applied for design of the fatigue life or fatigue strength of circular hollow sections and wood filled hollow sections. Results were validated by static specific bending strengths determined by ANSYS using a known applied load.

• 한국안전학회지
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• 제11권2호
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• pp.89-95
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• 1996

To predict the service life of an organic vapor respirator cartridge, the breakthrough curve of respirator was simulated using a fixed-bed adsorption model and compared with that of sampling tube. And the effects of bed porosity, length to diameter ratio and flow rate of the sampling tube were studied. The life time of respirator cartridge was increased with the decrease of particle size and bed porosity. And the breakthrough time of sampling tube was affected by the flow rate, however not by the length to diameter ratio. The 10% breakthrough time of the sampling tube was corresponded with that of cartridge.

• 한국콘텐츠학회논문지
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• 제20권7호
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• pp.342-351
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• 2020

본 연구의 목적은 코로나19 원격 교육 환경에서 대학생들의 외로움과 유튜브 과다사용이 대학생활적응과 어떠한 관계가 있는가를 파악하는 것이다. 이를 위하여 본 연구는 외로움과 유튜브 과다사용이 사회 적응 및 학업 적응에 미치는 영향을 파악하는 연구모형을 개발하였다. 본 논문은 온라인 설문조사를 실시하여 95개의 설문조사 데이터를 최종 분석에 적용하였다. 설문 데이터는 구조 방정식 모형을 사용하여 분석하였다. 분석결과는 다음과 같다. 첫째, 외로움이 많을수록 대학 사회 적응과 학업 적응이 낮은 것으로 나타났다. 둘째, 유튜브 과다사용이 많을수록 대학 사회 적응이 낮은 것으로 나타났다. 결론적으로 외로움과 유튜브 과다사용은 대학생활적응을 예측하는 유의한 변인인 것으로 나타났다. 본 연구의 결과는 대학생들이 외로움 관리와 유튜브를 사용을 적절하게 할 수 있도록 돕는 환경 조성과 제도적 지원의 필요성을 시사하고 있다.

• 한국콘텐츠학회논문지
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• 제20권5호
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• pp.513-524
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• 2020

최근 유튜브의 성장이 주목받고 있다. 유튜브는 콘텐츠를 소비하는 채널일 뿐만 아니라 소비자의 의사를 표시하는 공간이 되고 있다. 소비자들은 댓글이라는 형식으로 유튜브 안에서 그들의 의견을 표출한다. 이 연구는 유튜브에 업로드되어 시청되는 글로벌 기업가 연설문과 영상을 시청하고 작성한 댓글의 텍스트를 연구대상으로 한다. 텍스트 마이닝 소프트웨어인 Leximancer를 사용하여 각각의 연설문과 댓글을 대상으로 내용 분석(content analysis)을 시행하였다. 각 기업가 연설문의 주제는 대응분석(correspondence analysis)을 사용하여 분석하였고 기업가 개인의 성향과 특성과 관련 있는 주제를 도출하였다. 댓글에서는 각 연설문의 내용과는 관계없이 공통적으로 money, work, need의 주제를 발견하였다. 텍스트의 길이가 다름을 고려하여 추가로 중요도 지표 (Prominence Index) 분석을 실행하였고 연설문 내용과 시청자 댓글의 공통적인 주제를 구성하는 핵심어로 time, future, better, best, change, life, business, need를 도출하였다. 유튜브 연설문의 시청자는 인생과 시간, 미래, 고객의 니즈, 긍정적 변화에 대한 메시지에 대하여 동일한 주제로 반응하는 것으로 나타났다.

• 한국소음진동공학회논문집
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• 제14권4호
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• pp.327-335
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• 2004

본 연구에서는 가동중인 원자력발전소의 이물질에 의한 프레팅 마모 특성을 평가하였다. 다양한 조건의 나선형 튜브 고유진동수 및 모드 형상을 구하기 위하여 모드 해석을 수행하였다. 이물질에 의한 나선형 튜브의 마모율을 Archard 공식을 이용하여 계산하였고 이로부터 튜브의 잔여 수명을 예측하였으며 튜브의 진동 특성이 잔여 수명에 미치는 영향을 고찰하였다. 또한 튜브에 가해지는 외압이 진동 및 프레팅 마모 특성에 미치는 영향을 평가하였다.

• Nuclear Engineering and Technology
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• 제35권5호
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• pp.442-453
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• 2003

This study investigates the safety assessment of the potential for fretting-wear damages on steam generator (SG) U-tubes caused by foreign object in operating nuclear power plants. The operating SG shell-side flow field conditions are obtained from three-dimensional SG flow calculation using the ATHOS3 code. Modal analyses are performed for the finite element modelings of U-tubes to get the natural frequency, corresponding mode shape and participation factor. The wear rate of U-tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted. Also, discussed in this study is the effect of the flow velocity and vibration of the tube on the remaining life of the tube.