• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1453-1454
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• 2011

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.97-104
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• 2000

Evaluating a Review-Level Ground Motion is a key to efficiently perform Seismic Margin Assessment of nuclear power plants whose purpose is to determine a ground motion level for which a plant has high-confidence-of-a-low-probability of seismic-induced core damage and to identify any weaker-link components. In this study a method to obtain RLGMs is reviewed which is recommended by Electric Power Research Institute and implemented to be applied to Limerick site in eastern and central U. S as a case study. This method provides reasonable and site-specific RLGMs as minimum required plant HCLPF for SMA that meet a target mean seismic core-damage frequency based on seismic hazard results and generic values of uncertainty and randomness parameters of the core-damage fragility curves. In addition high-frequency RLGM is justifiably modified to reflect the increased seismic capacity of high-frequency components and spatial variation and incoherence of input ground motion on a basemat of large structures by establishing a method to obtain high0-frequency reduction factors according to EPRI guidelines.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.380-384
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• 2010

A disturbance flow at piping bands and discontinuous regions such as a valve, a header has a intense broadband internal pressure field and a sound field which are propagated through the piping system The fields becomes the source of a vibration of this piping system. Intense broadband disturbance flow at a discontinuous region such as elbows, valves or headers generates an acoustical pulsation. The pulsation becomes the source of structural vibration at the piping system. If it coincides with the natural frequency of the pipe system, excessive vibration results. High-level vibration due to the pressure pulsation affects the reliability of the plant piping system. This paper discusses the high vibration and the branch vent pipe's failure of condensate-water supply piping system due to the effect of acoustical pulsations by flow turbulence from the flow control valves of globe type in a power site.

• Applied Microscopy
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• v.45 no.4
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• pp.230-235
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• 2015

Crystallographic models are effective tools to interpret, calculate and even to predict the preferred crystallographic morphologies of precipitates in various precipitation systems. The present study gives an introduction on the recently developed secondary constrained coincident site lattice (II-CCSL) model. Using the II-CCSL model, the interface matching condition of the ${\beta}-Mg_{17}Al_{12}$ precipitates with ${\alpha}-Mg$ matrix in an aged AZ91 alloy has been analyzed to rationalize the morphologies of the precipitates. The results show that the characteristic crystallographic features of the observed ${\beta}-Mg_{17}Al_{12}$ precipitates, i.e., the habit plane of the ${\beta}-Mg_{17}Al_{12}$ lath with a Burgers orientation relationship (OR) and the growth direction of the ${\beta}-Mg_{17}Al_{12}$ with a Crawley OR exhibit a better lattice matching degree than their vicinal orientations. Moreover, the Crawley OR is preferred to the Burgers OR due to a better lattice match.

• Environmental Engineering Research
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• v.13 no.2
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• pp.73-78
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• 2008

For a given soil-contaminated site, a level of soil contamination is characterized and decisions on risk may be made from the risk assessment. The study evaluated critical design factors for the determination of sample size in the sampling design plan and the assessment of soil contaminant- leaching to groundwater. Two variables, the minimum relative detectable difference (T) and coefficient of variation (CV) were evaluated for the sample size determination. The minimum number of samples can be appropriately determined by CV under a T value greater than or equal to 0.2. Soil-contaminant leaching to groundwater was evaluated by using the Soil Screening Level equation of U.S. Environmental Protection Agency and the Risk Based Screening Level equation of American Society for Testing and Materials, with the same input parameters. The groundwater concentrations estimated from soil contaminant concentrations were significantly affected by the Darcy velocity of groundwater and the organic content of soil.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.2 no.2
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• pp.39-53
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• 1991

디지탈 기기를 포함한 일반적인 전기전자기기로 부터 발생하는 방해전자파는, 낮은 주파수 대역(MF, HF 대역)에서는 전원성 등의 도선을 따라서 전달(전도성 방해파)되고, 높은 주파수 대역(VHF, UHF 대역)에서는 직접 공간에 방사(방사성 방해파)된다. 이러한 전도성 및 방사성 방해파의 측정은 IEC, CISPR, FCC, VDE 등의 규격이 정하고 있는 규정에 따라서 실시된다. 이들 규격은 방해파 측정법을 규정하고 있을 뿐만 아니라, 재현성이 좋은 측정을 실현시키기 위해 측정용 시설에 대해서도 자세하게 규정하고 있다. 방사성 방해파의 측정에 사용하는 측정시설로서는, 기본적으로 야외시험장(Open Area Test Site, OATS)을 사용하도록 규정하고 있는데, 측정치의 상호연관성을 위해서는 규약에 정해진 적합성이 평 가되고 확인되어 있어야만 한다. 여기서는 방사성 방해파 측정용 시설중에서 가장 기본적이고도 중요한 야외시험장의 적합성 평가 파 라미터 - 두 지점간의 전송손실, 이를 시험장감쇠량 이라함 - 에 대하여 기술하기로 한다.

• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.7-11
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• 2003

CDMA(code division multiple access) has very large peak to average power ratio(PAR) and behave as noise-like wide band digital signals with 1.2288 Mbps transmission rate. For signals with high PAR like CDMA, it is reasonable to prescribe occupied bandwidth(OBW) as average occupied bandwidth. Bandwidth measurements of CDMA signals at remote site are affected by co-channel and adjacent channel interference from adjacent CDMA base station, distortion of signal by fading effect, spurious emission and environment noises. In this study, we have compared OBW measurements in an on-air environment with those measured in a base station using adjacent channel leakage ratio(ACLR) as a reference measurement factor. As results of analysis, the OBW at ACLR$\geq$35 ㏈ shows nearly same statistical characteristics regardless of the measurement locations and environments.

• Tunnel and Underground Space
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• v.3 no.1
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• pp.54-62
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• 1993

In order to evaluate the necessity for the support during the excavation of the transport drift and use the data for design applications, laboratory testings of mechanical properties of rock samples and engineering rock mass classifications on this study site were performed. The values of RMR and Q-system are 68 and 11.8, respectively. Since these results were evaluated as good, this rock mass were determined to be unsupported. Full face excavation method was determined to be suitable for excavating this drift. In case of excavation, smooth blasting techniques must be carried out at the wall rock and the crown. However, considering the blast vibration etc. that have an effect on the surrounding rock mass, approximately less than 9kg of explosive charges per blast should be maintained.

• Nuclear Engineering and Technology
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• v.11 no.2
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• pp.127-132
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• 1979

A model is considered in order to evaluate the potential risk from a nuclear facility directly combining the on-site meteorological data. The model is utilized to evaluate the environmental consequences from the routine releases during normal plant operation as well as following postulated accidental releases. The doses to individual and risks to the population-at-large are also analyzed in conjunction with design of rad-waste management and safety systems. It is observed that the conventional analysis, which is done in two separate unaffiliated phases of releases and atmospheric dispersion tends to result in unnecessary over-design of the systems because of high resultant doses calculated by multiplication of two extreme values.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.721-724
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• 2005

In this study the spatial distribution characters of forest in forest damaged area were first considered by analyzing spatial data and monitoring forest landscape. Then suitable tree species on each site were selected through the weighted score analysis of GIS analysis methods. Finally, the best forest stand arrangement method could be presented on the 3D based simulation system for the advanced reforestation technology in Korea. For this purpose, the virtual reforestation system was implemented by using the concept of virtual GIS and CBD (Component Based Development) method. By use of this system the change offorest landscape of burnt forest area some years after reforestation practice could be detected and monitored by applying the site index and 3D modeling method.