• Korean Journal of Radiology
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• v.19 no.6
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• pp.1053-1065
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• 2018

Objective: To evaluate the clinical impact of using registration software for ablative margin assessment on pre-radiofrequency ablation (RFA) magnetic resonance imaging (MRI) and post-RFA computed tomography (CT) compared with the conventional side-by-side MR-CT visual comparison. Materials and Methods: In this Institutional Review Board-approved prospective study, 68 patients with 88 hepatocellulcar carcinomas (HCCs) who had undergone pre-RFA MRI were enrolled. Informed consent was obtained from all patients. Pre-RFA MRI and post-RFA CT images were analyzed to evaluate the presence of a sufficient safety margin (${\geq}3mm$) in two separate sessions using either side-by-side visual comparison or non-rigid registration software. Patients with an insufficient ablative margin on either one or both methods underwent additional treatment depending on the technical feasibility and patient's condition. Then, ablative margins were re-assessed using both methods. Local tumor progression (LTP) rates were compared between the sufficient and insufficient margin groups in each method. Results: The two methods showed 14.8% (13/88) discordance in estimating sufficient ablative margins. On registration software-assisted inspection, patients with insufficient ablative margins showed a significantly higher 5-year LTP rate than those with sufficient ablative margins (66.7% vs. 27.0%, p = 0.004). However, classification by visual inspection alone did not reveal a significant difference in 5-year LTP between the two groups (28.6% vs. 30.5%, p = 0.79). Conclusion: Registration software provided better ablative margin assessment than did visual inspection in patients with HCCs who had undergone pre-RFA MRI and post-RFA CT for prediction of LTP after RFA and may provide more precise risk stratification of those who are treated with RFA.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.977-981
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• 2006

In order to improve water quality in drinking water sources, Ministry of Environment (MOE) was implemented total water pollution load management (TWPLM) in all the major river basins. From the experience of the application of TWPLM, we could find some problems relating the target watershed, standard operating procedure (SOP) of establishment and implementation plan, water quality and flow rate, design flow, water quality model, margin of safety (MOS), and estimation of wasteload were found. The authors were reviewed ongoing TWPLM and presented the improvement schemes for a successful TWPLM. For the application of these suggestions, further detailed studies should be done to implement TWPLM in the future.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.234-241
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• 2000

Stress analysis of the bogie frame by using the finite element method has been performed for the various loading conditions according to the results of vehicle dynamics analysis. Multiaxial fatigue analysis methods such as signed von Mises method, and typical critical plane theories were reviewed, and margin of safety for fatigue is defined. Multiaxial fatigue analysis program to predict the margin of safety of bogie frame under non-proportional loading conditions has been developed by using a commercial command language. Fatigue analysis of bogie frame under multiaxial loading was performed through this program and finite element analysis result. The procedure developed in this study is considered to be useful for the fatigue strength analysis in preliminary design stage of railway components under multiaxial loading condition.

• Earthquakes and Structures
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• v.5 no.3
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• pp.277-296
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• 2013

Margin of safety against potential of progressive collapse is among important features of a structural system. Often eccentricity in plan of a building causes concentration of damage, thus adversely affects its progressive collapse safety margin. In this paper the progressive collapse of symmetric and asymmetric 3-story reinforced concrete ordinary moment resisting frame buildings subjected to the earthquake ground motions are studied. The asymmetric buildings have 5%, 15% and 25% mass eccentricity. The distribution of the damage and spread of the collapse is investigated using nonlinear time history analyses. Results show that potential of the progressive collapse at both stiff and flexible edges of the buildings increases with increase in the level of asymmetry in buildings. It is also demonstrated that "drift" as a more easily available global response parameter is a good measure of the potential of progressive collapse rather than much difficult-to-calculate local response parameter of "number of collapse plastic hinges".

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.110-117
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• 2003

The result of recent seismic hazard analysis indicates that the ground motion response spectra for Korean nuclear power plant site have relatively large high frequency acceleration contents. In the ordinary seismic fragility analysis of nuclear power plant structures and equipments, the safety margin of design ground response spectrum is directly used as a response spectrum shape factor. The effects of input response spectrum shape on the floor response spectrum were investigated by performing the direct generation of floor response spectrum from the ground response spectrum. The safety margin included in the design ground response spectrum should be considered as a floor response spectrum shape factor for the seismic fragility analysis of the equipments located in a building.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.3
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• pp.121-128
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• 2021

Structures of domestic nuclear power plants are designed to perform elastic behavior against beyond design earthquakes, but studies on the nonlinear behavior of structures have been insufficient since the beyond design earthquake. Accordingly, it is judged that it will be necessary to develop an evaluation method that considers the nonlinear behavioral characteristics to check the safety margin for a standard nuclear power plant structure. It is confirmed that the restoring force characteristics for each member level can be identified through the calculation formula, and the lateral stiffness for each story can also be easily calculated by JEAC 4601. In addition, as a result of applying the evaluation method of JEAC 4601 as a nonlinear restoring force model of the nuclear power plant, a certain degree of safety margin can be identified.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.26-32
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• 2021

The antenna is mounted on the vehicle and operated, so its components must be able to withstand the shock that may occur while driving. In this study, the stability of antenna mounted on the vehicle is verified through the connection between modal analysis and transient analysis. The shock data used was taken from MIL-STD-810H, METHOD 516.8. As a result of the analysis of antenna, the maximum equivalent stress 169.49MPa and minimum margin of safety 2.31 has occurred on the bracket of antenna. Thus, it was found that the antenna has enough stability during the operation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.44-50
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• 2021

This study analyzed the stability of antenna equipped on vehicles by the link of modal analysis and random vibration analysis with the vibration data of MIL-STD-810H, METHOD 514.8. As a result of the random vibration analysis of antenna, the maximum equivalent stress 41.9MPa and minimum margin of safety 8.37 was generated in the bracket of antenna by the vertical direction vibration. Thus, it was found that antenna has enough stability during the operation.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.359-359
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• 2017

하천관리청은 유량변동이 큰 환경에서도 평상시 하천의 기능을 유지하고 안정적인 용수공급이 이루어지도록 하천수 허가관리를 수행하고 있다. 이때, 하천수 사용허가 검토시 기준으로 사용되는 유량은 자연상태의 기준갈수량에서 하천유지유량을 감안하여 적용하고 있는데, 이는 하천유량의 변동에도 최대 용수수요를 만족할 수 있게끔 관리하기 위한 것으로 최대 사용량일 때의 물의 과부족을 계산하여 허가 여부를 결정한다. 본 연구에서는 Park et al.(2016)이 제안한 시기별(홍수기/이수기, 비관개기/관개기 고려) 하천수 사용허가 기준유량 설정방법을 기반으로, 수질오염총량제(Total Maximum Daily Loads, TMDLs)에서 적용하는 안전율(Margin of Safety, MOS)의 개념을 접목하여 허가기준유량의 불확실성을 정량적으로 고려할 수 있는 방법을 제시하였다. 허가기준 유량은 수문모델에 의해 자연상태의 모의유량을 유황분석하여 도출하게 되므로 유량의 연도별 변도성(Margin of Variability, MOV)과 예측모델 매개변수의 불확실성(Margin of Uncertainty, MOU)을 고려하는 Walker Jr.(2003)의 안전율 산정방법을 적용하였다. 본 연구에서는 금호강 유역을 대상으로 시기별 자연유량 산정시 고려한 SWAT 모형결과를 기반으로 하였으며, 모의자료의 변이계수를 산정하여 시간적 변동성에 의한 불확실성을 도출하고 SWAT-CUP모형을 활용하여 모형의 불확실성을 도출하여 안전율을 계산하였다. 단, 기준갈수량이 허가기준유량으로 사용되는 기간(1월 1일~3월 31일)에는 안전율까지 고려할 경우 지나치게 보수적이라고 판단되어 적용에서 제외하였다. 본 연구에서 제안된 불확실성을 고려한 하천수 관리방법론은 시기별 하천수 허가기준유량 설정에 대한 의사결정자들의 판단을 지원하는데 기여함으로써 정책적 활용도를 높일 뿐만아니라 탄력적인 하천유량관리를 위한 기초연구로 활용될 수 있을 것이며, 타 분야 기술과의 융합이라는 점에서도 의의를 가질 수 있을 것으로 생각된다.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.531.1-531
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• 2001