• 비파괴검사학회지
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• 제24권1호
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• pp.45-51
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• 2004

발전소 보일러튜브는 장시간 동안 고온고압하의 기혹한 조건으로 운전됨에 따라 크리프, 열피로와 같은 각종 열화에 의해 누설손상이 발생하고 있다. 이러한 누설손상을 실시간 감시하고 진단하기 위하여 음향방출기술을 이용한 현장적용 연구를 수행하였다. 또한 고장예측 진단기술, 튜브의 수명관리 및 설비 감시에 활용할 수 있도록 음향방출 진단시스템을 개발하여 현장에 설치하고, 보일러 운전상태에 따른 신호측정 및 평가, 누설위치 판별 등에 대해 고찰하였다. 누설감지는 저주파 및 고주파대역의 누설로 구분하여 음향방출신호를 각각 측정 및 평가하였다. 현장적용 연구결과로부터 실시간으로 보일러튜브 상태감시와 누설위치 추적이 가능하였으며, 향후 본 기술을 이용하면 발전설비 안전운전과 발전소 정지에 따른 경제적 손실 예방에 크게 기여할 것으로 기대된다.

• 화훼연구
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• 제17권3호
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• pp.197-200
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• 2009

접목선인장 신품종 '고홍'은 진적색의 'DR' 계통을 모본으로 진적색의 '설홍'을 부본으로 2004년에 교배하여 개발되었다. 이 품종은 처음 기내에서 파종한 후 유묘를 무병삼각주에 접목하고 100 mL 시험관에 정식하여 6개월을 재배하였다. 2005년에 기외에서 접목한 후에 2008년까지 3회에 걸쳐 그 특성이 조사되었다. 구는 진적색의 편원형이며, 몸체에 8~10개의 결각이 있으며, 회색의 직립 가시를 가지고 있다. 구의 직경은 44.1 mm로 대조 품종 '설홍'에 비해 구가 크고 생육 속도도 빠르다. 지구 착생수는 평균 12.1개로 12.2개의 대조 품종 '설홍'과 유사하다.

• 화훼연구
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• 제19권4호
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• pp.248-250
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• 2011

비모란 선인장 '이홍' 품종은 진적색의 계통 'DR'을 모본으로 진적색의 '설홍' 품종을 부본으로 2005년 교배하여 개발되었다. 파종된 종자는 기내에서 접목되어 6개월 동안 100 mL 시험관에서 6개월 동안 자랐다. 2006년 재접목되어 온실에 정식되어 2009년까지 다양한 특징이 조사되었다. 편원형의 모양과 진적색의 구색을 가지고 있으며, 또한, 8-10개의 결각과 갈색의 직립형 가시를 가지고 있다. 온실에 정식 후 10개월째에 '이홍' 품종의 구직경은 44.0 mm였으며 '설홍' 품종에 비해 큰 편이었다. 자구수는 10개월째에 15.8개로 '설홍' 품종에 비해 많았으나 유의성은 없었다.

• 화훼연구
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• 제16권3호
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• pp.196-199
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• 2008

접목선인장 신품종 '다홍'은 흑적색의 '9508021'계통을 모본으로 진적색의 '진홍'을 부본으로 2002년에 교배한 후대이다. 2003년 기외에서 접목한 후에 2006년까지 3회에 걸쳐 그 특성이 조사되었다. 구는 진적색의 편원형이며, 가지자리에 같은 색의 자구가 모구하부에 정연히 착생된다. 또한 몸체에 8~10 결각이 있으며, 회색의 반직립 가시를 가지고 있다. 자구 착생수는 평균 13.6개로 10.4개의 대조품종 '진홍'보다 우수하였다.

• 화훼연구
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• 제18권4호
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• pp.291-294
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• 2010

접목선인장 신품종 '황운'은 해외 수출용 목적으로, 황색과 오렌지색을 가진 복색의 '황월' 품종을 모본으로 황색의 계통 '0111021'을 부본으로 교배하여 2008년에 개발되었다. 이 품종은 처음 기내에서 무병삼각주에 접목된 후 100 mL 시험관에 정식되어 6개월간 생육되었다. 2005년에 기외에서 접목한 후에 2008년까지 3회에 걸쳐 그 특성이 조사되었다. 구는 황색의 편원형이며, 몸체에 7~9개의 결각이 있으며, 갈색의 직립형 가시를 가지고 있다. 10개월간 재배되었을 때 구의 직경은 40.9 mm로 대조 품종 '후광'에 비해 구가 작고, 자구 착생수는 평균 22.3개로 '후광' 품종에 비해 우수하였다.

• 설비공학논문집
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• 제19권5호
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• pp.372-378
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• 2007

GHX (Geothermal Heat Exchanger) design which determines the performance and initial cost is the most important factor in ground source heat pump system. Performance of GHX is strongly dependent on the thermal resistance of soil, grout and pipe. In general, GHX design is based on the static simulation program. In this study, dynamic simulation has been peformed to analyze the variation of system performance for various GHX parameters. Line-source theory has been applied to calculate the variation of ground temperature. The averaged weather data measured during a 10-year period $(1991\sim2000)$ in Seoul is used to calculate cooling and heating loads of a building with a floor area of $100m^2$. The simulation results indicate that thermal properties of borehole play significant effect on the overall performance. Change of grout thermal conductivity from 0.4 to $3.0W/(m^{\circ}C)$ increases COP of heating by 9.4% and cooling by 17%. Change of soil thermal conductivity from 1.5 to $4.0W/(m^{\circ}C)$ increases COP of heating by 13.3% and cooling by 4.4%. Change of GHX(length from 100 to 200 m increases COP of heating by 10.6% and cooling by 10.2%. To study long term performance, dynamic simulation has been conducted for a 20-year period and the result showed that soil temperature decreases by $1^{\circ}C$, heating COP decreases by 2.7% and cooling COP decreases by 1.4%.

• 시스템엔지니어링학술지
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• 제18권2호
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• pp.94-107
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• 2022

Accidents prevention and mitigation is the highest priority of nuclear power plant (NPP) operation, particularly in the aftermath of the Fukushima Daiichi accident, which has reignited public anxieties and skepticism regarding nuclear energy usage. To deal with accident scenarios more effectively, operators must have ample and precise information about key safety parameters as well as their future trajectories. This work investigates the potential of machine learning in forecasting NPP response in real-time to provide an additional validation method and help reduce human error, especially in accident situations where operators are under a lot of stress. First, a base-case SGTR simulation is carried out by the best-estimate code RELAP5/MOD3.4 to confirm the validity of the model against results reported in the APR1400 Design Control Document (DCD). Then, uncertainty quantification is performed by coupling RELAP5/MOD3.4 and the statistical tool DAKOTA to generate a large enough dataset for the construction and training of neural-based machine learning (ML) models, namely LSTM, GRU, and hybrid CNN-LSTM. Finally, the accuracy and reliability of these models in forecasting system response are tested by their performance on fresh data. To facilitate and oversee the process of developing the ML models, a Systems Engineering (SE) methodology is used to ensure that the work is consistently in line with the originating mission statement and that the findings obtained at each subsequent phase are valid.

• 한국압력기기공학회 논문집
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• 제17권1호
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• pp.18-27
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• 2021

This study aims to develop an improved evaluation technology for assessing CANDU-6 safety. For this purpose, the multiple steam generator tube rupture (mSGTR) followed by an unmitigated station blackout (SBO) in a CANDU-6 plant was selected as a hypothetical event scenario and the analysis model to evaluate the plant responses was envisioned into the MARS-KS input model. The model includes logic models for controlling the pressure and inventory of the primary heat transport system (PHTS) decreasing due to the u-tubes' rupture, as well as the main features of PHTS with a simplified model for the horizontal fuel channels, the secondary heat transport system including the shell side of steam generators, feedwater and main steam line, and moderator system. A steady state condition was successfully achieved to confirm the stable convergence of the key parameters. Until the turbine trip, the fuel channels were adequately cooled by forced circulation of coolant and supply of main feedwater. However, due to the continuous reduction of PHTS pressure and inventory, the reactor and turbine were shut down and the thermal-hydraulic behaviors between intact and broken loops got asymmetric. Furthermore, as the conditions of low-flow coolant and high void fraction in the broken loop persisted, leading to degradation of decay heat removal, it was evaluated that the peak cladding temperature (PCT) exceeded the limit criteria for ensuring nuclear fuel integrity. This study is expected to provide the technical bases to the accident management strategy for transient conditions with multiple events.

• 대한치위생과학회지
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• 제5권1호
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• pp.13-19
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• 2022

Background: In this study, zirconia copings were fabricated by setting clinically acceptable inner values for prostheses using computer-aided design/computer-aided manufacturing (CAD/CAM). The processed copings were evaluated for the marginal and internal fit of each abutment shape with a CAD program using the silicone replica technique. Methods A total of 20 copings was produced by selecting models commonly used in clinical practice. After injecting the sample, the minimum thickness, internal adhesion interval, and distance to the margin line were set to 0.5, 0.05, and 1.00 mm using a dental CAD program, respectively. It was measured using a 2D section function in a three-way program of the silicon replication technology. Although the positions and number of measurements of the anterior and posterior regions differed, nine parts of each pre-tube were designated and measured by referring to a previous study to compare the two samples. Results As a result, the average margin of the mesial, distal, and buccal (labial) surfaces was 59.90 ㎛ in the anterior region and 60.40 ㎛ in the posterior region. The mean axial wall margin was 67.25 ㎛ in the anterior region and 69.25 ㎛ in the posterior region. In occlusion, the anterior teeth (77.70 ㎛), posterior teeth (77.60 ㎛), and both anterior and posterior regions were within the clinically acceptable range. Conclusion The edge and inner fit of zirconia coping manufactured using the CAD/CAM system showed clinically applicable results. To reduce errors and increase accuracy, materials and machine errors that affect the manufacture of prosthetics should be investigated. Based on our results, the completeness of prosthetics could increase if the inner value and characteristics of the material are adjusted when applied in clinical practice.

• Asia pacific journal of information systems
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• 제30권3호
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• pp.568-589
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• 2020

Recently, Social media has become a concern for businesses, including Small and Medium Enterprises (SMEs). SMEs began to adopt social media to support their performance. To benefit from the application of social media, SMEs must implement the right strategy. This study aims to analyze the factors that influence the use of social media in SMEs. Furthermore, alignment between social media functionalities and strategies and their effect on SME's performance are investigated. A case study is conducted in Gymi, a garment SMEs in East Java, Indonesia. The data collection includes interviews with the owner of SMEs, observations, and document analysis. Data analysis is performed by pattern matching, which matches the patterns from the literature with data from the case study. The results of this study show that cost-effectiveness, interactivity, and compatibility are factors that influence the use of social media in Gymi. The social media used by Gymi are Instagram, Facebook, YouTube, WhatsApp, and LINE. However, the main social media used to support Gymi's functions is Instagram. Gymi has a relatively good social media strategy as it has defined a specific goal, target audience, and channel selection for social media (Instagram). It also has specific resources and policies to handle social media. Gymi monitors and evaluates their social media content activities. These strategies are aligned with the Instagram feature used to support Gymi's function, particularly marketing, sales, customer service, and to some extent, internal operation. The alignment contributes to Gymi's performance measured by the increase in reputation (number of Instagram followers) and sales.