• Nuclear Engineering and Technology
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• 제50권2호
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• pp.259-267
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• 2018

Focused ion beam-scanning electron microscope and electron backscattered diffraction examinations were conducted in the center of a $73\;GWd/t_U\;UO_2$ fuel. They showed the formation of subdomains within the initial grains. The local crystal orientations in these domains were close to that of the original grain. Most of the fission gas bubbles were located on the boundaries. Their shapes were far from spherical and far from lenticular. No interlinked bubble network was found. These observations shed light on previous unexplained observations. They plead for a revision of the classical description of fission gas release mechanisms for the center of high burn-up $UO_2$. Yet, complementary detailed observations are needed to better understand the mechanisms involved.

• 전자공학회논문지 IE
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• 제43권1호
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• pp.5-15
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• 2006

족탕기(STYX ford202)를 이용하여 발 부분의 온열수 자극을 인가하여 생체 현상의 각종 변화를 계측하였다. 생체 현상의 변화 데이터는 발 부분의 온수 열 자극을 43$^{\circ}C$, 45$^{\circ}C$의 조건으로 10명의 남여 사람을 10일 동안 1회 측정시 5분, 10분, 15분, 20분, 경과 실험을 통해 9가지 생리적 요소를 측정하여 분석하였다. 생체신호요소의 측정의 분석 결과는 이마온도는 -0.69 $\pm$ 0.01 감소하였고, 다리온도는 1.51 $\pm$ 0.22 증가되었다. 혈류($m\ell/min$)는 1.18 $\pm$ 0.50 증가되며, 혈압(mmHg)는 -1.49$\pm$ 2.81, (min) -0.06$\pm$ 0.13 감소 현상을 보였다. 맥박수의 변화는 6.97 $\pm$ 0.72 증가하며, 혈당은 ($mg/d\ell$) : -2.41 $\pm$ 1.55 감소되었고, 피부산소포화도 (%): 1.34 $\pm$ 0.28 증가하였다. 또한 체지방(%) -1.75$\pm$ 0.15 및 체중은 (kr): -0.10 $\pm$ 0.04 감소 현상으로 나타났다.

• Journal of Chest Surgery
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• 제17권3호
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• pp.475-483
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• 1984

Here presented six cases of benign tumors of the lung treated surgically between Dec. 1957 and Dec. 1983 in the Department of Thoracic Surgery, Seoul National University Hospital. They include four cases of hamartoma, one case of benign mesothelioma, and one case of Castlemans disease. The operative procedures are three cases of lobectomy, one case of segmentectomy, and two cases of mass excision. The operative results are excellent without complication.

• 한국콘텐츠학회논문지
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• 제17권7호
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• pp.332-343
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• 2017

본 연구는 개인의 이타적 성향과 메시지 프레이밍의 상호작용이 국제기아 돕기 캠페인의 효과에 미치는 영향에 대하여 조사하였다. 이타적 성향은 고통 받는 타인에게 연민을 느끼고, 관심을 갖는 정도를 나타내는 공감적 관심을 선정하였고, 프레이밍은 도움을 주었을 때의 긍정적 결과 혹은 도움을 주지 않았을 때의 부정적 결과를 강조하는 대비 방식을 이용하였다. 실험은 175명을 대상으로 실행되었으며, 2단계로 나누어서 실행되었다. 1단계에서는 참여자들의 이타적 성향과 관여도에 관한 설문을 진행하였고, 2단계에서는 긍정적 혹은 부정적으로 유형화된 메시지를 제시한 후 나타나는 반응을 측정하였다. 연구 결과, 긍정적 프레이밍에서 공감적 관심이 높은 사람들이 낮은 사람들에 비하여 더 높은 행위 의도와 친밀감을 보여주었고, 부정적 프레이밍은 차별적 반응을 이끌어 내지 않은 것으로 나타났다. 그리고 인지된 친밀감은 행위 의도에 대한 상호작용을 매개하는 것으로 나타났다.

• 천문학회보
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• 제42권2호
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• pp.61.1-61.1
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• 2017

As the application of deep-learning methods has been succeeded in various fields, they have a high potential to be applied to space weather forecasting. Convolutional neural network, one of deep learning methods, is specialized in image recognition. In this study, we apply the AlexNet architecture, which is a winner of Imagenet Large Scale Virtual Recognition Challenge (ILSVRC) 2012, to the forecast of daily solar flare occurrence using the MatConvNet software of MATLAB. Our input images are SOHO/MDI, EIT $195{\AA}$, and $304{\AA}$ from January 1996 to December 2010, and output ones are yes or no of flare occurrence. We consider other input images which consist of last two images and their difference image. We select training dataset from Jan 1996 to Dec 2000 and from Jan 2003 to Dec 2008. Testing dataset is chosen from Jan 2001 to Dec 2002 and from Jan 2009 to Dec 2010 in order to consider the solar cycle effect. In training dataset, we randomly select one fifth of training data for validation dataset to avoid the over-fitting problem. Our model successfully forecasts the flare occurrence with about 0.90 probability of detection (POD) for common flares (C-, M-, and X-class). While POD of major flares (M- and X-class) forecasting is 0.96, false alarm rate (FAR) also scores relatively high(0.60). We also present several statistical parameters such as critical success index (CSI) and true skill statistics (TSS). All statistical parameters do not strongly depend on the number of input data sets. Our model can immediately be applied to automatic forecasting service when image data are available.

• Tribology and Lubricants
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• 제37권3호
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• pp.99-105
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• 2021

In this study, for a high-pressure turbine (HPT) of 800 MW class supercritical thermal-power plant, considering aerodynamic cross-coupling, we performed a rotordynamic logarithmic decrement (LogDec) stability analysis with various tilting pad journal bearing (TPJB) designs, which several steam turbine OEMs (original equipment manufacturers) currently apply in their supercritical and ultra-supercritical HPTs. We considered the following TPJB designs: 6-Pad load on pad (LOP)/load between pad (LBP), 5-Pad LOP/LBP, Hybrid 3-Pad LOP (lower 3-Pad tilting and upper 1-Pad fixed), and 5-Pad LBPs with the design variables of offset and preload. We used the API Level-I method for a LogDec stability analysis. Following results are summarized only in a standpoint of LogDec stability. The Hybrid 3-Pad LOP TPJBs most excellently outperform all the other TPJBs over nearly a full range of cross-coupled stiffness. In a high range of cross-coupled stiffness, both the 6-Pad LOP and 5-Pad LOP TPJBs may be recommended as a practical conservative bearing design approach for enhancing a rotordynamic stability of the HPT. As expected, in a high range of cross-coupled stiffness, the 6-Pad LBP TPJBs exhibit a better performance than the 5-Pad LBP TPJBs. However, contrary to one's expectation, notably, the 5-Pad LOP TPJBs exhibit a slightly better performance than the 6-Pad LOP TPJBs. Furthermore, we do not recommend any TPJB design efforts of either increasing a pad offset from 0.5 or a pad preload from 0 for the HPT in a standpoint of stability.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.884-894
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• 2023

Design and safety assessment of fuel pins for application in innovative Generation IV fast reactors calls for a dedicated nuclear fuel modelling and for the extension of the fuel performance code capabilities to the envisaged materials and irradiation conditions. In the INSPYRE Project, comprehensive and physics-based models for the thermal-mechanical properties of U-Pu mixed-oxide (MOX) fuels and for fission gas behaviour were developed and implemented in the European fuel performance codes GERMINAL, MACROS and TRANSURANUS. As a follow-up to the assessment of the reference code versions ("pre-INSPYRE", NET 53 (2021) 3367-3378), this work presents the integral validation and benchmark of the code versions extended in INSPYRE ("post-INSPYRE") against two pins from the SUPERFACT-1 fast reactor irradiation experiment. The post-INSPYRE simulation results are compared to the available integral and local data from post-irradiation examinations, and benchmarked on the evolution during irradiation of quantities of engineering interest (e.g., fuel central temperature, fission gas release). The comparison with the pre-INSPYRE results is reported to evaluate the impact of the novel models on the predicted pin performance. The outcome represents a step forward towards the description of fuel behaviour in fast reactor irradiation conditions, and allows the identification of the main remaining gaps.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.973-979
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• 2024

In the framework of the Generation IV research and development project, in which the French Commission of Alternative and Atomic Energies (CEA) is involved, a main objective for the design of Sodium-cooled Fast Reactor (SFR) is to meet the safety goals for severe accidents. Among the severe ones, the Unprotected Transient OverPower (UTOP) accidents can lead very quickly to a global melting of the core. UTOP accidents can be considered either as slow during a Control Rod Withdrawal (CRW) or as fast. The paper focuses on fast UTOP accidents, which occur in a few milliseconds, and three different scenarios are considered: rupture of the core support plate, uncontrolled passage of a gas bubble inside the core and core mechanical distortion such as a core flowering/compaction during an earthquake. Several levels and rates of reactivity insertions are also considered and the thermal-mechanical behavior of an ASTRID fuel pin from the ASTRID CFV core is simulated with the GERMINAL code. Two types of fuel pins are simulated, inner and outer core pins, and three different burn-up are considered. Moreover, the feedback from the CABRI programs on these type of transients is used in order to evaluate the failure mechanism in terms of kinetics of energy injection and fuel melting. The CABRI experiments complete the analysis made with GERMINAL calculations and have shown that three dominant mechanisms can be considered as responsible for pin failure or onset of pin degradation during ULOF/UTOP accident: molten cavity pressure loading, fuel-cladding mechanical interaction (FCMI) and fuel break-up. The study is one of the first step in fast UTOP accidents modelling with GERMINAL and it has shown that the code can already succeed in modelling these type of scenarios up to the sodium boiling point. The modeling of the radial propagation of the melting front, validated by comparison with CABRI tests, is already very efficient.

• 전기전자학회논문지
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• 제22권1호
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• pp.209-212
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• 2018

본 논문에서는 P(VDF-TrFE)유기물 강유전체 기반 metal-ferroelectric-metal (MFM) capacitor 와 차세대 반도체 물질인 질화갈륨 반도체를 활용한 네거티브 커패시턴스 전계효과 트랜지스터를 제작 및 분석 하였다. 27 nm의 두께의 P(VDF-TrFE) MFM 커패시터의 분극지수는 4 MV/cm에서 $6{\mu}C/cm^2$ 값을 나타내었으며 약 65 ~ 95 pF의 커패시턴스 값을 나타내었다. 강유전체의 커패시턴스와 전계효과 트랜지스터의 커패시턴스 매칭을 분석하기 위해 제작된 P(VDF-TrFE) MFM 커패시터는 GaN 전계효과 트랜지스터의 게이트 전극에 집적화 되었으며 집적화되기 전 104 mV/dec 의 문턱전압 이하 기울기에서 82 mV/dec 값으로 개선된 효과를 보였다.

• 한국철도학회논문집
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• 제11권1호
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• pp.69-74
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• 2008

철도차량 간 통신에 적용 가능한 SNMP기반 전력선 통신 시스템의 운영 정보베이스(MIB)의 설계 및 구현에 관한 연구로, "Basic Information", "Configuration", "Stats", 그리고 "Alarm"의 네 가지 노드를 갖는 MIB를 정의하고 구현한다. 특히 통신 성능의 향상을 위한 "Alarm"운용 함수들로서 사용자 간섭 없이 장비와의 자동 연결을 가능하게 하는 ACF, 데이터 손실과 에러의 유무를 검사하는 DEC, 그리고 에러를 포함한 데이터의 손실을 방지하는 DLPF를 정의하고 구현한다. 제안된 MIB의 평가를 위해 전력선 통신 실험 장치를 만들어 실험을 수행한다. 제안된 MIB를 갖는 전력선 통신 시스템은 종래의 것을 개선하는데 기여한 바가 있다.