• Nuclear Engineering and Technology
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• 제40권3호
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• pp.191-198
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• 2008

The influence of fission products' contents on the DUPIC fuel powder and pellet properties was experimentally evaluated using SIMFUEL as a surrogate for actual spent PWR fuel due to the high radioactivity of spent fuel. Pure $UO_2$ and SIMFUEL pellets with fission products equivalent to a burn-up of 35,000 MWd/tU and 60,000 MWd/tU were used as impurities in this study. The specific surface area of the powder milled after the OREOX treatment increased and resulted in sintered pellets with a theoretical density (TD) higher than 95%, regardless of the impurity contents. However, the grain size of the sintered pellets decreased with the increasing impurity contents. As a result of the dissolved oxides in $UO_2$ from the impurity groups, the specific surface area of the OREOX powder increased with an increase of the impurities. The grain size of the sintered pellets was significantly decreased by the metallic and oxide precipitates.

• The Journal of Korean Physical Therapy
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• 제28권3호
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• pp.176-182
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• 2016

Purpose: To investigate the effect of treadmill training applied simultaneously with gait related action observation on walking ability in chronic stroke patients. Methods: Sixteen chronic stroke patients participated in this study. Participants were randomly allocated into either the treadmill applied simultaneously with action observation training group (TAG) or treadmill applied simultaneously with landscape observation training group (TLG). The participants in both group underwent treadmill training for four weeks (a total of twelve minute, once a day, three times weekly for a four week period). All participants were measured to gait speed (10 m walking test, 10 MWT), gait endurance (6 minute walk distance, 6 MWD), dynamic gait index (DGI). In order to assure the statistical significance of the results, we used for SPSS 15.0 for windows. The Wilcoxon signed ranks test was used to compare pre-test and post-test result, and the Mann-Whitney U-test was employed for comparison between groups. Results: The 10 MWT, 6 MWD, DGI was significantly different between the TAG and the TLG group. Conclusion: According the results of this study, treadmill applied simultaneously with action observation (TAG) is effective intervention for improvement of walking ability in chronic stroke patient.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.219-224
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• 1996

노심설계에서 현재 사용되는 일체형 가연성 흡수봉인 Gd, ZrB$_2$ 그리고 Er의 한국표준형 원전 노심 설계에의 타당성을 노심 F$\Delta$H 제어, 저누출 장전모형 설계, 농축도/주기길이 그리고 주기말의 잔존 페널티 등의 측면에서 분석하였다. 초기노심의 경우는 영광 3호기 1주기 장전모형에 동일 연료집합체를 사용한 Gd/ZrB$_2$/Er의 경우와 ZrB$_2$/Er 최적장전모형에 동일 연료집합체를 사용한 경우에 대하여 분석하였다. 평형노심은 Gd/ZrB$_2$/Er 모두 동일한 장전모형을 사용한 18개월 주기길이의 노심에 대하여 동일한 농축도에서의 주기길이차이와 동등 주기길이를 내는데 필요한 농축도 요구량에 대하여 분석하였다. 초기노심 평형노심 모두 F$\Delta$H 제어에는 ZrB$_2$/Er가 Gd보다 유리하였으며, 저누출 장전모형의 설계에도 ZrB$_2$와 Er가 Gd보다 유리하였다. 평형노심에서 동일한 주기길이를 내는데 요구되는 농축도는 ZrB$_2$에 비하여 Er는 0.182 w/o Gd는 0.063 w/o 높게 나타났으며 동일 농축도를 사용할 경우 주기길이는 ZrB$_2$에 비하여 Gd는 165 MWD/MTU 그리고 Er은 575 MWD/MTU가 짧게 나타났다. 따라서, F$\Delta$H 제어와 저누출 장전모형은 설계에는 ZrB$_2$와 Er가 Gd보다 유리하였으나 Er의 경우 주기말에서의 잔존 페널티가 매우 크다는 단점이 있다.

• Nuclear Engineering and Technology
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• 제43권2호
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• pp.141-148
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• 2011

This paper presents the quantitative analysis results of research on the burnup effect on the nuclear fuel cycle cost of BeO-$UO_2$ fuel. As a result of this analysis, if the burnup is 60 MWD/kg, which is the limit under South Korean regulations, the nuclear fuel cycle cost is 4.47 mills/kWh at 4.8wt% of Be content for the BeO-$UO_2$ fuel. It is, however, reduced to 3.70 mills/kWh at 5.4wt% of Be content if the burnup is 75MWD/kg. Therefore, it seems very advantageous, in terms of the economic aspect, to develop BeO-$UO_2$ fuel, which does not have any technical problem with its safety and is a high burnup & long life cycle nuclear fuel.

• Nuclear Engineering and Technology
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• 제40권4호
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• pp.311-318
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• 2008

In modem power reactors, nuclear fuels have recently reached 55,000 MWd/MtU from the initial average burnup of 35,000 MWd/MtU to reduce the fuel cycle cost and waste volume. At such high burnups, a fuel pellet produces fission products proportional to the burnup and creates a typical high burnup structure around the periphery region of the pellet, producing the so called 'rim effect'. This rim region of a highly burnt fuel is known to be ca. $200\;{\mu}m$ in width and is known to affect the fuel integrity. To characterize the local burnup in the rim region, solid sampling in the micro meter region by laser ablation is needed so that the distribution of isotopes can be determined by ICP-MS. For this procedure, special radiation shielding is required for personnel safety. In this study, we installed a radiation shielded laser ablation ICP-MS system, and a performance test of the developed system was conducted to evaluate the safe operation of instruments.

• 방사성폐기물학회지
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• 제20권4호
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• pp.501-510
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• 2022

The nuclear criticality analyses considering burnup credit were performed for a spent nuclear fuel (SNF) disposal cell consisting of bentonite buffer and two different types of SNF disposal canister: the KBS-3 canister and small standardized transportation, aging and disposal (STAD) canister. Firstly, the KBS-3 & STAD canister containing four SNFs of the initial enrichment of 4.0wt% ²³⁵U and discharge burnup of 45,000 MWD/MTU were modelled. The k_eff values for the cooling times of 40, 50, and 60 years of SNFs were calculated to be 0.79108, 0.78803, and 0.78484 & 0.76149, 0.75683, and 0.75444, respectively. Secondly, the KBS-3 & STAD canister with four SNFs of 4.5wt% and 55,000 MWD/MTU were modelled. The k_eff values for the cooling times of 40, 50, and 60 years were 0.78067, 0.77581, and 0.77335 & 0.75024, 0.74647, and 0.74420, respectively. Therefore, all cases met the performance criterion with respect to the k_eff value, 0.95. The STAD canister had the lower k_eff values than KBS-3. The neutron absorber plates in the STAD canister significantly affected the reduction in k_eff values although the distance among the SNFs in the STAD canister was considerably shorter than that in the KBS-3 canister.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4499-4513
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• 2022

Spent fuel behavior of dry storage was simulated in a continuous state from steady-state operation by modifying FRAPCON-4.0 to incorporate spent fuel-specific fuel behavior models. Spent fuel behavior of a typical PWR was compared with that of NuScale Power Module (NPM^TM). Current PWR discharge burnup (60 MWd/kgU) gives a sufficient margin to the hoop stress limit of 90 MPa. Most hydrogen precipitation occurs in the first 50 years of dry storage, thereby no extra phenomenological safety factor is identified for extended dry storage up to 100 years. Regulation for spent fuel management can be significantly alleviated for LWR-based SMRs. Hydride embrittlement safety criterion is irrelevant to NuScale spent fuels; they have sufficiently lower plenum pressure and hydrogen contents compared to those of PWRs. Cladding creep out during dry storage reduces the subchannel area with burnup. The most deformed cladding outer diameter after 100 years of dry storage is found to be 9.64 mm for discharge burnup of 70 MWd/kgU. It may deteriorate heat transfer of dry storage by increasing flow resistance and decreasing the view factor of radiative heat transfer. Self-regulated by decreasing rod internal pressure with opening gap, cladding creep out closely reaches the saturated point after ~50 years of dry storage.

• Elastomers and Composites
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• 제37권4호
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• pp.234-243
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• 2002

A general scheme of a rubber structure is proposed. Using the thermomechanical method(TMA), some changes in the molecular and topological structures for uncured and cured, and unfilled and filled rubbers during processing are shown. In our investigations as region it is understood a complex structure, which is expressed at the thermomechanical curve(TMC) as a zone differed from others in thermal expansion properties. This zone is between the noticed temperatures of relaxation transitions, usually on the level like those determined by DMTA at 1Hz. These regions, which shares, are not stable, and differ in molecular-weight distribution(MWD) of chain fragments between the junctions. Differences in dynamics of the formation of the molecular and topological structures of a vulcanizate are dependent on the rubber formulation, mixing technology and curing time. Some of characteristics of these regions correlate with mechanical properties of vulcanizates what is shown for NR rubbers containing ENR or CPE as a polymeric additive. It is well known that the state of order influences diffusivity of low-molecular substances into the polymer matrix. Because of this, the two topological amorphous regions should influence the distribution of the ingredients and resulting in rubber compounds' heterogeneity, and related properties of cured rubber. Investigation of this problem is expected to be, in the future, one of the essential factors in determining further improvement of polymeric materials properties by compounding with additives and in reprocessing of rubber scrap.

• 대한간호학회지
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• 제50권1호
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• pp.66-80
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• 2020

Purpose: This study aims to examine the effects of nursing interventions based on the Extended Theory of Planned Behavior (ETPB) regarding self-efficacy for exercise (SEE), physical activity (PA), physical function (PF), and quality of life (QOL) in patients with lung cancer who have undergone pulmonary resection. Methods: This quasi-experimental study was conducted between July 2015 and June 2018 in two university-affiliated hospitals. The intervention included pre-operative patient education, goal setting (action and coping planning), and feedback (behavior intention and perceived behavioral control). The intervention group (IG) (n=51) received nursing interventions from the day before surgery to 12 months after lung resection, while the comparison group (CG) (n=36) received usual care. SEE, PA, PF (dyspnea, functional status, and 6-minute walking distance [6MWD]), and QOL were measured before surgery and at one, three, six, and 12 months after surgery. Data were analyzed using the χ² test, Fisher's exact test, Mann-Whitney U test, t-test, and generalized estimation equations (GEE). Results: There were significant differences between the two groups regarding SEE (χ²=13.53, p=.009), PA (χ²=9.51, p=.049), functional status (χ²=10.55, p=.032), and 6MWD (χ²=15.62, p=.004). Although there were no time or group effects, the QOL mental component (Z=-2.78, p=.005) of the IG was higher than that of the CG one month after surgery. Interventions did not affect dyspnea or the QOL physical component. Conclusion: The intervention of this study was effective in improving SEE, PA, functional status, and 6MWD of lung cancer patients after lung resection. Further extended investigations that utilize ETPB are warranted to confirm these results.

• 정보처리학회논문지A
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• 제12A권6호
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• pp.515-522
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• 2005

본 논문에서는 부분적으로 파손된 치아의 수복에 사용되는 인레이/온레이 인공치아를 효과적으로 모델링하는 기법을 제안한다. 인레이/온레이는 지대치에 부착되는 내면과 밖으로 들어나는 외면으로 구성된다. 내면은 지대치와의 밀착력을 확보하기 위하여 지대치의 삭제된 표면의 확장된 부분으로 Minkowski sum을 이용하여 모델링된다. 외면을 모델링하기 위해서는 표준치아 모델, 환자 치아 석고모형을 스캔한 메쉬 자료, 환자 치아교합을 측정한 FGP(functionally guided plane) 등 세 가지 정보와 DMFFD(direct manipulation free-form deformation)[19]과 MWD(multiple wires deformation)[17]의 3D 메쉬 변형 기술들을 이용한다. 표준치아 모델은 외면의 기본적인 형태를 결정하기 위하여 사용되는 반면 석고모형 데이터와 FGP는 환자 치아 인접면과 교합면마다 약간 다르지만 정확한 기능에 매우 중요한 고유 특성을 반영하기 위해 사용되는 정보이다. 이러한 정보들을 입력으로 DMFFD 기법과 MWD 기법을 각각 적용하여 인레이/온레이 인접면과 교합면을 메쉬 자료로 자동으로 생성해낸다. 연구된 기법은 치과의사에 의한 요구사항을 반영하여 생성된 메쉬 모델을 가시화하면서 보다 정확하게 인레이/온레이를 디자인할 수 있도록 구현되었다.