• Nuclear Engineering and Technology
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• 제26권3호
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• pp.345-354
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• 1994

수치 해석을 통하여 이차유동을 포함한 핵연료봉 주위의 난류 유동장을 예측하였다. 등방성 난류와 점성계수 모델과 이차 유동을 모사하기 위해 단순화된 대수응력모델을 사용하여 난류 운동 에너지 (k)와 난류 에너지 소멸률($\varepsilon$)의 이 방정식 모델과 운동량 방정식을 유한 차분법으로 풀어 유동장내의 평균속도, 이차유동, 난류 운동 에너지, 난류 응력 분포 등을 구하였다. 수치해석 예측치를 실험데이타와 비교하여 만족할만한 결과를 얻었고 유동장내에서 이차유동의 영향을 확인하였다. 즉 이차유동이 절대 크기는 작더라도 대류 효과에 의해 큰 영향을 미치는 것을 본 연구를 통해 알 수 있었다.

• 기본간호학회지
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• 제13권1호
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• pp.96-106
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• 2006

Purpose: This study was dont: to evaluate the factors that influence secondary traumatic stress, burnout, and physical symptoms experienced by firefighters. In addition, a hypothetical model was developed. Method: The data were collected using self-reported questionnaires from 410 field service firefighters. Data analysis was done with the SPSSWIN 10.0 program for descriptive statistics and Windows LISREL program to determine the causal relationship between the measurement variables. Results: The hypothetical model which was developed fits well with actual data(${\chi}^2$=3.16, p=0.99, GFI=1.00, AGFI=0.99, NFI=0.99, and NNFI=1.06). The variable, personality type, social support, and impact mobilization frequency had a significant effect and accounted for 7% of the secondary traumatic stress in firefighters. The variables, career, social support, and secondary traumatic stress had a significant effect and accounted for 24% of the burnout in firefighters. Social support, impact mobilization frequency, and secondary traumatic stress were important variables and accounted for 31% of the physical symptoms in firefighters. Conclusion: It is necessary for firefighters to manage themselves according to their personality types. Strategies that can increase the firefighters' social support and decrease their perceived secondary traumatic stress also need to be developed to minimize or prevent a negative effect on their health.

• 대한기계학회논문집B
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• 제22권4호
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• pp.417-427
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• 1998

The effect of secondary flow on the heat transfer of a turbulent wake generated by a flat plate was experimentally investigated. The secondary flow was induced in a curved duct in which the flat plate wake generator was installed. All three components of turbulent heat flux were measured in the plane containing the mean radius of curvature of the curved duct. The results showed that mean temperature profiles deviate from the similarity of the straight wake because of the cold fluid transported from the free-stream. The half-width of the mean temperature profile increased rapidly by upwash motion of the secondary flow. The changes to turbulence structure caused by the secondary flow show more pronounced effect on heat transport than on momentum transport. This is because the response to the variation of flow conditions is delayed in temperature field. Negative production of the turbulent heat flux is observed in the inner wake region. From the conditional averaging, it has been found that the negative production of the turbulent heat flux is generated due to a mixing process between the hot and low momentum eddies occupied in the inner wake region and the cold and high momentum eddies in the potential region.

• 한국학교수학회논문집
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• 제22권1호
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• pp.63-80
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• 2019

본 연구는 중등예비수학교사의 학생의 학습에 대한 노티싱을 살펴보기 위해 시작되었다. 이를 위해 4명의 중등예비수학교사가 중학교 수학수업에서 학습보조교사 활동을 하고 작성한 일지를 조사하였다. 일지에 나타난 학생에 대한 노티싱은 선행연구의 분석틀을 기초로 하여 알아차리기, 해석하기, 반응하기의 세 가지로 구분하여 분석하였다. 연구결과 중등예비수학교사들은 대체로 학생에 대한 일반적인 알아차리기가 많고 수학적 사고에 대한 해석하기가 상대적으로 적게 나타났다. 반응하기에서는 질문을 통한 학생의 사고 촉진보다는 학생들에게 설명하기가 많이 나타남을 확인하였다. 이를 토대로 중등예비수학교사 교육프로그램에 주는 시사점을 논의하고자 한다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 춘계학술대회 및 임시총회
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• pp.49-49
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• 2015

Over the past decade, clubroot has emerged as a major constraint to canola (Brassica napus) production in central Alberta, Canada. The number of fields with confirmed P. brassicae infestations in Alberta has increased steadily from 12 in 2003 to nearly 2,000 in 2014. Management of clubroot on canola has focused on sanitization of field equipment, soil amendments to reduce viable pathogen populations, long rotations out of susceptible crops and cropping of resistant cultivars. Clubroot resistance is the most effective and economical method of disease mitigation, but the recent identification of isolated P. brassicae populations with novel virulence phenotypes capable of overcoming resistance in most canola cultivars highlights the variable nature and adaptability of the pathogen. Recent studies have shown slight reductions in pathogen populations through crop rotations, but much more substantial reductions in spore populations in heavily infested areas near field entrances using fumigants such as Vapam (metam-sodium) or Basamid (dazomet). Greenhouse trials showed that seedling emergence, plant height and root weight increased, while primary and secondary infection and disease severity decreased with increased Basamid dosage. However, field trials showed some phytotoxicity. Application of Vapam at rates of 0.4 to $1.6mL\;L^{-1}$ soil resulted in 12-16 fold reductions in clubroot severity and primary and secondary infection. Vapam also was effective in reducing clubroot severity and improving canola seed yield under field conditions. These studies underscore the need for good resistance stewardship and for the integration of multiple products and practices for successful management of clubroot on canola.

• Geomechanics and Engineering
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• 제3권3호
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• pp.233-254
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• 2011

The consolidation behavior of Sri Lankan peaty clay is analyzed using an elasto-viscoplastic model. The model can describe the secondary compression behavior as a continuous process and it can also account for the effect of structural degradation on the consolidation analysis. The analysis takes into account all the main features involved in the process of peat consolidation, namely, finite strain, variable permeability, and the secondary compression. The material parameters required for the analysis and the procedures to evaluate them, using both standard laboratory and field tests, are explained. Initially, the model performance is assessed by comparing the predicted and the observed peat consolidation behavior under laboratory conditions. The results indicate that the model is capable of predicting the observed creep settlements and the effect of layer thickness on the settlement analysis of peaty clay. Then, the model is applied to predict the consolidation behavior of peaty clay under different field conditions. In this context, firstly, the one-dimensional field consolidation of peaty clay, brought about by the construction of compacted earth fill, is predicted. Then, the two-dimensional peat foundation response upon embankment loading is simulated. A good agreement is seen in the comparison of the predicted results with the field observations.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.119-122
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• 2002

In general, Liquid Injection Thrust Vector Control(LITVC) is accomplished by injecting a liquid into the supersonic exhaust flow through holes in the wall of the propulsion nozzle. This injection flow field is highly complicated and detailed flow physics associated with the secondary flow injection should be known far the practical design and use of the LITVC system. The present study aims at understanding the LTTVC flow field and obtaining fundamental design parameters for LITVC. The experimentations were performed in a supersonic blow-down wind tunnel. Compressed, dry air was used for both the main exhaust and injection flows but the pressures of these two flows were controlled independently. The location of the injection holes was changed and the pressures of the two streams were also changed between 2.0 and 15.0 bar. The effectiveness of LITVC was discussed in details using the results of the pressure measurements and flow visualizations

• 대한방사선치료학회지
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• 제27권1호
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• pp.87-95
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• 2015

목 적 : 안와 주변 방사선 치료 시 수정체 피폭선량감소를 위하여 사용된 2차 차폐 block의 유용성을 알아보고자 한다. 대상 및 방법 : Human phantom(Alderson Rando Phantom, The Phantom Laboratory, USA)을 사용하여 CT(Somatom Definition AS, Siemens, Germany) 모의촬영 후 전산화치료계획시스템(Pinnacle, PHILIPS, USA)을 통해 실제 치료와 유사한 IMRT치료계획을 실시하였다. 2차 차폐를 위하여 두께 3mm 지름 25 mm의 납판과 3 mm tungsten eye-shield block(Extra small size, Radiation Products Design, Inc, USA)를 사용하였으며, TPS(Treatment Planning System) 상의 lens dose와 모의치료 상의 lens dose를 OSLD로 측정 비교하였다. 또한, 5 cm 두께의 acrylic phantom에 동일한 조건의 2차 차폐물인 3 mm 납판과 tungsten eye-shield block을 사용하여 200 MU(6 MV, SPD(Source to Phantom Distance)=100 cm, $F{\cdot}S\;5{\times}5cm$)를 조사 및 측정하였으며, 조사야 밖의 누설선 및 투과방사선 영향을 제한시키고자 8 cm 납블럭(O.S.B: Outside Scatter Block)을 적용하여 위와 동일한 실험을 시행하였다. 조사야로부터 1 cm 이격하여 phantom 끝 옆면에 OSLD(Optically Stimulated Luminescence Dosimeter)를 부착하였고, eyelid의 두께에 해당하는 bolus 3 mm를 적용하였다. 결 과 : human phantom을 이용하여 IMRT 치료계획 상의 Lens dose와 실 측정치는 각각 315.9, 216.7 cGy가 측정되었고, 3 mm 납판과 tungsten eye-shield block으로 2차 차폐 후 각각 234.3, 224.1 cGy가 측정되었다. acrylic phantom을 이용한 실험 결과는 no block, 3 mm 납판, tungsten eye-shield block을 사용했을 때 5.24, 5.42, 5.39 cGy가 측정되었으며, 조사야 밖에 O.S.B를 적용하여 no block, 3 mm 납판, tungsten eye-shield block을 실험한 결과 각각 1.79, 2.00, 2.02 cGy가 측정되었다. 결 론 : 광자선 조사 시 critical organ을 보호하기 위하여 2차 차폐를 적용할 시에는 field 외부일지라도 헤드 누설방사선 및 collimator & MLC 투과방사선이 존재하므로 치료부위와 beam 방향에 따라 금속과 같은 높은 원자번호의 차폐물질이 critical organ근처에 있다면 선량 증가의 원인이 될 수 있다는 사실을 알 수 있었다. 따라서 피폭선량 감소를 위한 2차 차폐의 시도는 분명 의미가 있었으나 미 검증된 시도는 오히려 역효과를 가져올 수 있다는 사실을 인지하여 QA를 통해 목적에 부합하는 결과가 나오는지를 사전에 알아보아야 할 것이다.

• Radiation Oncology Journal
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• 제33권3호
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• pp.226-232
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• 2015

Purpose: Toxicity of mucosa is one of the major concerns of radiotherapy (RT), when a target tumor is located near a mucosal lined organ. Energy of photon RT is transferred primarily by secondary electrons. If these secondary electrons could be removed in an internal cavity of mucosal lined organ, the mucosa will be spared without compromising the target tumor dose. The purpose of this study was to present a RT dose reduction in near target inner-surface (NTIS) of internal cavity, using Lorentz force of magnetic field. Materials and Methods: Tissue equivalent phantoms, composed with a cylinder shaped internal cavity, and adjacent a target tumor part, were developed. The phantoms were irradiated using 6 MV photon beam, with or without 0.3 T of perpendicular magnetic field. Two experimental models were developed: single beam model (SBM) to analyze central axis dose distributions and multiple beam model (MBM) to simulate a clinical case of prostate cancer with rectum. RT dose of NTIS of internal cavity and target tumor area (TTA) were measured. Results: With magnetic field applied, bending effect of dose distribution was visualized. The depth dose distribution of SBM showed 28.1% dose reduction of NTIS and little difference in dose of TTA with magnetic field. In MBM, cross-sectional dose of NTIS was reduced by 33.1% with magnetic field, while TTA dose were the same, irrespective of magnetic field. Conclusion: RT dose of mucosal lined organ, located near treatment target, could be modulated by perpendicular magnetic field.

• 대한공업교육학회지
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• 제42권1호
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• pp.53-67
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• 2017

본 연구는 중등단계 직업교육 기관에 대한 중학교 교장의 과거와 현재, 미래의 인식의 변화를 분석하여 중등단계 직업교육 기관의 인식 변화를 구명하고, 중등단계 직업교육 기관의 인식 개선을 위한 정책 지원에 대한 기초 자료를 제시하기 위해 수행되었다. 이를 위해 중학교 교장 214명을 대상으로 하여 중등단계 직업교육 기관에 대한 과거와 현재, 미래의 인식을 조사하여 분석하였다. 연구 결과 첫째, 중학교 교장이 인식한 중등단계 직업교육 기관에 대한 인식은 과거보다 현재가 더 긍정적으로 변화하였고, 현재보다 미래가 더 긍정적으로 변화할 것으로 나타났다. 이는 2005년 이후 다양한 중등단계 직업교육 정책이 직업교육의 인식 개선의 측면에서 긍정적 효과가 있음으로 해석할 수 있다. 둘째, 중학교 교장의 중등단계 직업교육 기관에 대한 과거 현재 미래의 인식의 내용에 대한 순위 변화를 분석한 결과, "적성과 소질을 일찍 살릴 수 있음"과 "졸업 후 학생의 경제적 자립이 빠름"과 관련된 내용에서 과거 현재 미래 모두 긍정적으로 인식하고 있었다. "동일계 대학 진학이 용이함"과 관련된 내용은 과거와 현재에서는 높은 순위로 인식하였으나, 미래에는 낮은 순위로 인식될 것으로 예상하고 있어 정부의 정책의 방향에 따른 중등단계 직업교육 기관에 대한 인식도 달라지고 있음을 확인하였다.