• International Journal of Oral Biology
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• v.30 no.4
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• pp.131-134
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• 2005

In the present study, performances of several in vitro maturation (IVM) systems for porcine follicular oocytes were evaluated, and an efficient chemically defined IVM system for porcine oocytes was proposed. The proposed one-step culture system supplemented with polyvinylalcohol (PVA) gave competitive efficiencies in terms of oocyte maturation and blastocyst development after parthenogenetic activation and in vitro culture, compared with the conventional two-step culture system by a supplementation of porcine follicular fluid (pFF). Additionally, it is identified that the proposed chemically defined one-step culture system yielded the comparable level of blastocyst production to the conventional maturation system in porcine somatic cell nuclear transfer (SCNT). Therefore, one can eliminate un-expected effects accompanied by supplementation of pFF. No medium replacement during whole maturation period is an additional benefit by applying this new system. Thus, these data support that the developed PVA supplemented chemically defined one-step IVM system for porcine follicular oocyte might be used in porcine SCNT program.

• Nuclear Engineering and Technology
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• v.33 no.6
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• pp.566-584
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• 2001

In this paper, the progressive deformation and the creep-fatigue damage for the conceptually designed reactor internals of KALIMER(Korea Advanced Liquid MEtal Reactor) are carried out by using the elastic analysis method in the RCC-MR code for normal operating conditions including the thermal load, seismic load (OBE) and dead weight. The maximum operating temperature of this reactor is 53$0^{\circ}C$ and the total service lifetime is 30 years. Thus, the time- dependent creep and stress-rupture effects become quite important in the structural design. The effects of the thermal induced membrane stress on the creep-fatigue damage are investigated with the risk of the elastic follow-up. To calculate the thermal stress, detailed thermal analyses considering conduction, convection and radiation heat transfer mechanisms are carried out with the ANSYS program. Using the results of the elastic analysis, the progressive deformation and creep-fatigue damages are calculated step by step using the RCC-MR in detail. This paper ill be a very useful guide for an actual application of the high temperature structural design of the nuclear power plant accounting for the time-dependent creep and stress-rupture effects.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.2
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• pp.49-58
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• 2018

The regulatory periodic inspection program (PSI) conducted at every overhaul period is the most important process for confirming the safety of nuclear power plants. The PSI for operating nuclear power plants in Korea mainly consist of component level performance check that had been developed based on deterministic approach putting the same degree of importance to all the inspection items. This inspection methodology is likely to be effective for preoperational inspection. However, once the plant is put into service, the PSI must be focused on whether to minimize the risk of accident using defense-in-depth concept and risk insight. The incorporation of defense-in-depth concept and risk insight into the deterministic based safety inspection has not been well studied so far. In this study, two track approaches are proposed to make sure that core damage be avoided: one is to secure success path and the other to block the failure path in a specific event tree of PSA. The investigation shows how to select safety important components and how to set up inspection group to ensure that core damage would not occur for a given initiating event, which results in strengthening defense-in-depth level 3.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.283-292
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• 2022

Advanced radiation applications have been widely used and extended to many fields. As a result of this fact, choosing an appropriate shielding material based on the radiation application has become vital. In this regard, the integration of elements into polymer composites has been investigated and contributed to the quantity and quality of radiation shielding materials. This study reports photon attenuation parameters and electromagnetic shielding effectiveness of a novel polymer composite prepared with a matrix reinforced with three different proportions (5, 10, and 15 wt%) of niobium content. Addition of Nb dopant improves both photon attenuation and electromagnetic shielding effectiveness for the investigated composites. Therefore, Nb(15%) polymer composite with highest concentration has been found to be the best absorber for ionizing and non-ionizing radiations. Consequently, the performed analyzes provide evidences that the prepared Nb-reinforced polymer composite could be effectively used as photon radiation attenuator and electromagnetic shielding material.

• BMB Reports
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• v.50 no.2
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• pp.97-102
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• 2017

Patients with inflammatory bone disease or cancer exhibit an increased risk of fractures and delayed bone healing. The S100A4 protein is a member of the calcium-binding S100 protein family, which is abundantly expressed in inflammatory diseases and cancers. We investigated the effects of extracellular S100A4 on osteoblasts, which are cells responsible for bone formation. Treating primary calvarial osteoblasts with recombinant S100A4 resulted in matrix mineralization reductions. The expression of osteoblast marker genes including osteocalcin and osterix was also suppressed. Interestingly, S100A4 stimulated the nuclear factor-kappaB (NF-${\kappa}B$) signaling pathway in osteoblasts. More importantly, the ex vivo organ culture of mouse calvariae with recombinant S100A4 decreased the expression levels of osteocalcin, supporting the results of our in vitro experiments. This suggests that extracellular S100A4 is important for the regulation of bone formation by activating the NF-${\kappa}B$ signaling pathway in osteoblasts.

• Molecules and Cells
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• v.42 no.11
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• pp.810-819
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• 2019

For physiological or pathological understanding of bone disease caused by abnormal behavior of osteoclasts (OCs), functional studies of molecules that regulate the generation and action of OCs are required. In a microarray approach, we found the suppression of tumorigenicity 5 (ST5) gene is upregulated by receptor activator of nuclear $factor-{\kappa}B$ ligand (RANKL), the OC differentiation factor. Although the roles of ST5 in cancer and ${\beta}-cells$ have been reported, the function of ST5 in bone cells has not yet been investigated. Knockdown of ST5 by siRNA reduced OC differentiation from primary precursors. Moreover, ST5 downregulation decreased expression of NFATc1, a key transcription factor for osteoclastogenesis. In contrast, overexpression of ST5 resulted in the opposite phenotype of ST5 knockdown. In immunocytochemistry experiments, the ST5 protein is colocalized with Src in RANKL-committed cells. In addition, ST5 enhanced activation of Src and Syk, a Src substrate, in response to RANKL. ST5 reduction caused a decrease in RANKL-evoked calcium oscillation and inhibited translocation of NFATc1 into the nucleus. Taken together, these findings provide the first evidence of ST5 involvement in positive regulation of osteoclastogenesis via Src/Syk/calcium signaling.

• Molecules and Cells
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• v.45 no.10
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• pp.749-760
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• 2022

Osteoclast generation from monocyte/macrophage lineage precursor cells needs to be tightly regulated to maintain bone homeostasis and is frequently over-activated in inflammatory conditions. PARK2, a protein associated with Parkinson's disease, plays an important role in mitophagy via its ubiquitin ligase function. In this study, we investigated whether PARK2 is involved in osteoclastogenesis. PARK2 expression was found to be increased during the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation. PARK2 gene silencing with siRNA significantly reduced osteoclastogenesis induced by RANKL, LPS (lipopolysaccharide), TNFα (tumor necrosis factor α), and IL-1β (interleukin-1β). On the other hand, overexpression of PARK2 promoted osteoclastogenesis. This regulation of osteoclastogenesis by PARK2 was mediated by IKK (inhibitory κB kinase) and NF-κB activation while MAPK (mitogen-activated protein kinases) activation was not involved. Additionally, administration of PARK2 siRNA significantly reduced osteoclastogenesis and bone loss in an in vivo model of inflammatory bone erosion. Taken together, this study establishes a novel role for PARK2 as a positive regulator in osteoclast differentiation and inflammatory bone destruction.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.6 no.1
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• pp.1-8
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• 2010

The existing maintenance program is focused on time-based maintenance to inspect and repair components according to maintenance period, rather than condition-based maintenance or predictive maintenance. The preventive maintenance template of the steam turbine has been developed for optimizing maintenance procedure and improving reliability and availability of the steam turbine of nuclear power plants based on EPRI PM template methodology and EPRI technical reports about preventive maintenance.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.807-812
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• 2001

This paper represents the wall thinning analysis results for secondary side piping of two types of domestic nuclear power plants based on the DB establishment and F AC analysis study for NPP secondary system piping. CHECWORKS code utilized in this study has been applied world widely to wall thinning analyses for secondary side piping and its reliability has also been proved. The predicted wear rates for several piping systems of a pressurized water reactor NPP are compared with those of a pressurized heavy water reactor NPP and with the measured wear rates. On the basis of comparison results of the predicted and measured wear rates, the analysis results can be effectively applied to the development of a standard thinned pipe management program targeted all domestic nuclear power plants.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.83-89
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• 1997

본 연구에서는 국내 WH형 원전에서 내출력분포분석을 위해 INCORE 코드를 각 원전의 인접한 전산소의 주전산기에 설치하고, 단말기를 이용한 on-line 작업으로 수행하는 현행 노내출력분포 분석업무를 개선하기 위하여 PC용 INCORE 코드를 개발하였고, 이를 바탕으로 동일 윈도우 통합환경에서 INCORE 코드 운영에 필요한 모든 기능과 노내 출력분포 분석을 위한 발전소 운영절차 수행기능을 통합한 WINCORE(Windows program for INCORE) 시스템을 개발하였다. 현재 WINCORE 시스템은 울진 1호기 8주기부터 노내출력분포 분석업무를 지원하기 위하여 사용중에 있으며, 개발된 WINCORE 시스템을 이용함으로써 현장에서 직접적인 자료처리, 분석계산 및 기술지침서 안전제한치 만족여부 결정을 통하여 노심관리 업무의 효율성을 제고함을 확인하였다.