• 동력기계공학회지
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• 제18권2호
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• pp.57-61
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• 2014

Due to the changes of marine transportation industry, it requires ship in larger scale and high speed. In order to operate efficiently, the engine should be work in high power and high horse power. The increase of the number of the propeller blades and the pitch of the screw and the weight, vibration of shafting problems occurs. To evaluate the safety of the system through analyzing the dynamic characteristics propulsion shafting system, was used to prove or to verify the Lalanne & Ferraris model validation.. It indicates that the Program through Campbell diagram and Critical speed map, Root rocus map, to ensure the reliability of the experimental model.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3687-3691
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• 2011

Ion exchange experiments of molybdenum(VI) from strong HCl and $H_2SO_4$ solution have been done to investigate the existence of anionic complexes. The concentration of HCl and $H_2SO_4$was changed from 1 to 9 M. From the data on the complex formation of molybdenum in aqueous solution, a new distribution diagram of Mo(VI) was constructed in the pH range from zero to 10. AG 1 X-8, an anion exchange resin, and Diphonix, a cation exchange resin were used in the loading experiments. Ion exchange results indicate that anionic complexes of Mo(VI) begins to form from 3 M HCl and 1 M $H_2SO_4$ solution and the tendency to form anionic complexes is stronger in HCl than in $H_2SO_4$ solution. Our results can be utilized in the analysis of Mo(VI) in strong acid solution and in the design of a process to separate Mo(VI).

• Nuclear Engineering and Technology
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• 제49권4호
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• pp.692-699
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• 2017

The determination of the shape and rising velocity of gas bubbles in a liquid pool is of great importance in analyzing the radioactive aerosol emissions from nuclear power plant accidents in terms of the fission product release rate and the pool scrubbing efficiency of radioactive aerosols. This article suggests a simple parameterization for the gas bubble rising velocity as a function of the volume-equivalent bubble diameter; this parameterization does not require prior knowledge of bubble shape. This is more convenient than previously suggested parameterizations because it is given as a single explicit formula. It is also shown that a bubble shape diagram, which is very similar to the Grace's diagram, can be easily generated using the parameterization suggested in this article. Furthermore, the boundaries among the three bubble shape regimes in the $E_o-R_e$ plane and the condition for the bypass of the spheroidal regime can be delineated directly from the parameterization formula. Therefore, the parameterization suggested in this article appears to be useful not only in easily determining the bubble rising velocity (e.g., in postulated severe accident analysis codes) but also in understanding the trend of bubble shape change due to bubble growth.

• Journal of Ceramic Processing Research
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• 제19권6호
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• pp.519-524
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• 2018

Carbon/carbon composites (C/C) have been widely studied in the aerospace field because of their excellent thermal shock resistance and specific strength at high temperature. However, they have the problems that is easily oxidized and deteriorated under atmospheric environment. In order to overcome these shortcomings, the CVD coating of ultra-high-temperature ceramics to C/C has become an important technical issue. In this study, thermodynamic calculations were performed to TaC CVD coating on C/C by FactSage 6.2 program. The Ta-C phase diagrams were constructed with the results of thermodynamic calculations in the Ta-C-H-Cl system. Based on the Ta-C phase diagram, the experimental conditions were designed to confirm the deposition of various phases such as TaC single phase, TaC + C and $TaC+Ta_2C$ by varying the composition of Ta/C ratio. The deposited films were found to be in good agreement with the predicted phases.

• 정보보호학회논문지
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• 제20권2호
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• pp.23-32
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• 2010

IEEE 802.16e 표준을 기반으로 하는 와이브로(WiBro) 서비스는 순수 국내 기술로 개발된 초고속 무선 휴대인터넷 기술이다. 본 논문에서는 와이브로 초기인증 단계에서 생길 수 있는 보안취약점을 분석하고 그러한 보안위협을 대상으로 한 공격을 탐지할 수 있는 명세기반의 침입탐지시스템을 제안한다. 제안된 침입탐지시스템은 PKMv2 EAP-AKA 기반의 정상적인 초기 인증 동작방식을 명세화하여 상태전이머신으로 모델링한 후 명세에 기반한 침입탐지를 실시한다. 본 논문에서는 초기인증 과정에서 발생 가능한 다섯 가지의 공격들을 시나리오로 모델링하고, 시나리오 기반의 실험을 실시하여 제안된 침입탐지시스템의 탐지성능을 검증한다.

• 대한수학교육학회지:수학교육학연구
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• 제25권2호
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• pp.189-206
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• 2015

비례 추론에 관한 여러 연구에서 학습 지도 개선 방향으로 시각적 표상의 활용이 제안되어 왔다. 그러나 초등학교 교과서의 비와 비율, 비례식과 비례배분 단원에 사용되고 있는 시각적 표상은 질적인 면에서나 양적인 면에서나 매우 제한되어 있다. 이 논문에서는 교과서의 비례식과 비례배분 내용을 시각적 표상에 주목하여 분석하고, 시각적 표상의 적극적인 활용 방안 마련을 위한 기초적 논의를 전개한다. 이중수직선 모델과 이중테이프 모델은 각각 다중 묶음 관점과 변동 부분 관점에서 비례 맥락에 내재된 공변 관계와 불변성을 인식하는 데 유용하게 사용될 수 있다. 이 논문에서는 이를 초등학교 교과서의 비례식 및 비례배분 실생활 문제의 유형별로 이중수직선 모델과 이중테이프 모델이 어떻게 기능할 수 있는지를 논의함으로써 예시하였다. 초등 수학 교과서의 비례식 및 비례배분 실생활 문제의 각 유형은 두 관점(다중 묶음 관점과 변동 부분 관점) 및 두 모델(이중수직선 모델과 이중테이프 모델)과 모두 연결될 수 있다. 이 논문의 분석은 비례식과 비례배분 교재 구성 및 수업에서 시각적 표상을 활용하는 구체적인 방안을 마련하는 데 도움이 될 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.794-799
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• 2005

The failure of blades frequently happened in the 300MW LP turbine until now and they are maintaining the blades periodically during outage. So the blade-disk system is analysed by FEM in order to identify the main cause of failure of blade row. It is found that the stress of root's hole is highest in comparison with other parts from the result of the steady stress analysis. Also, the two dangerous frequencies which is related to the resonance condition are found in the interference diagram. one is 1,516 Hz which is related to the operating speed. The other is 2,981 Hz which is related to the 1 nozzle passing frequency. The dynamic stress analysis is per-formed to identify more accurate root cause for failure of blade row. It is confirmed that the dynamic stress of the latter is higher than one of the former. From these results, it is concluded that the former has deeply something to do with the failure of blades more than the latter. Based on versatile investigation and deliberation, the change of blade's grouping is determined to avoid the resonance condition with the operating speed. After the blade grouping is changed, the former frequency vanish completely but the latter is still in existence in the interference diagram. Fortunately, It is confirmed that the dynamic stress of the new blade grouping is lower than one of the old blade grouping. 2 years has passed since modification and the LP turbine is operated well without failure so far.

• 여성건강간호학회지
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• 제20권4호
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• pp.287-296
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• 2014

Purpose: The purpose of this study was to analyze the quality of reports on observational studies published in the Korean Journal of Women Health Nursing (KJWHN). Methods: Forty-six studies using cross-sectional designs published in KJWHN from January 2011 to June 2013 were selected for analysis. Selected articles were reviewed and evaluated by three reviewers using the 22 items of the Strengthening the Reporting of Observational studies in Epidemiology (STROBE) statement. As some of 22 items had more than one check point, further broken down, 34 checklist items were used for analysis. Results: Overall, the reviewed studies provided sufficient descriptions for many STROBE items. Seven of the 34 items were found to be not applicable, and 15 of the remaining 27 items (55.5%) were evaluated as 'sufficient' in reporting. Only one study included a flow diagram illustrating participation and this lack of flow diagram was the weakest area of reporting in this review. Conclusion: Clearer reporting of cross-sectional studies can be attained by attention to vulnerable areas of reporting, such as including a flow diagram of participants, descriptions of sources of bias and reason for non-participation, and describing limitations of the study. Issues regarding the application of STROBE statement items should be actively discussed in order to aid future revision and clarification of items included in STROBE statement.

• 대한간호학회지
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• 제45권5호
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• pp.723-732
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• 2015

Purpose: The purpose of this study was to develop a system dynamics model for adolescent obesity in Korea that could be used for obesity policy analysis. Methods: On the basis of the casual loop diagram, a model was developed by converting to stock and flow diagram. The Vensim DSS 5.0 program was used in the model development. We simulated method of moments to the calibration of this model with data from The Korea Youth Risk Behavior Web-based Survey 2005 to 2013. We ran the scenario simulation. Results: This model can be used to understand the current adolescent obesity rate, predict the future obesity rate, and be utilized as a tool for controlling the risk factors. The results of the model simulation match well with the data. It was identified that a proper model, able to predict obesity probability, was established. Conclusion: These results of stock and flow diagram modeling in adolescent obesity can be helpful in development of obesity by policy planners and other stakeholders to better anticipate the multiple effects of interventions in both the short and the long term. In the future we suggest the development of an expanded model based on this adolescent obesity model.

• 복식문화연구
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• 제23권5호
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• pp.861-875
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• 2015

This study examines the formative characteristics of Fold architecture and how its properties are shown in the fashion of the modern work of Issey Miyake through analysis. In this research, the Fold classification criteria for analysis features that appeared in Issey Miyake fashion features were established through research literature on Fold architecture and leading research. Empirical data collection was conducted for Issey Miyake's work and collection by collecting photo materials, and design concepts and the results are analyzed in terms of features. Study ranges of Issey Miyake's creative design development are Pleats Please, A-POC, 132.5 project, and collections from 2000 to 2014. The conclusion is as follows. First, design concepts presented in the Issey Miyake fashion features of Fold are Hybrid, topology, and uncertainty. Hybrid look for the meaning of fashion, which is the interaction between the wearer and garments. The concept of topology designs clothing, focusing on interrelationship of the body and clothing, and pays no attention to absolute size or the form of the clothing. The concept of uncertainty is an uncertain form that is infinitely expandable because all the elements have openness and uncertainty due to the determined incomplete state by the creator. Second, in the results presented in the Issey Miyake fashion features is the destruction of the boundary and diagram form. The destruction of the boundary is free from traditional clothing. The diagram form is a geometric form which does not create a Dart or Princess line.