• The Korean Journal of Applied Statistics
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• v.25 no.6
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• pp.977-985
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• 2012

Data quality and climate forecasting performance deteriorates because of long climate data contaminated by non-climatic factors such as the station relocation or new instrument replacement. For a trusted climate forecast, it is necessary to implement data quality control and test inhomogeneous data. Before the inhomogeneity test, a reference series was created by $d$ index to measure the temperature series relationship between the candidate and surrounding stations. In this study, a inhomogeneity test to each season and climatological station was performed on the daily mean temperatures, daily minimum temperatures and daily maximum temperatures. After comparing two inhomogeneity tests, the traditional and the adjusted SNHT method, we found the adjusted SNHT method was slightly superior to the traditional one.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.13 no.2
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• pp.60-66
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• 2017

The standard master curve (MC) approach has the major limitation because it is only applicable to homogeneous datasets. In nature, materials are macroscopically inhomogeneous and involve scatter of fracture toughness data due to various deterministic material inhomogeneity and random inhomogeneity. RPV(reactor pressure vessel) steel has different fracture toughness with varying distance from the inner surface of the wall due to cooling rate in manufacturing process; deterministic inhomogeneity. On the other hand, reference temperature, $T_0$, used in the evaluation of fracture toughness is acting as a random parameter in the evaluation of welding region; random inhomogeneity. In the present paper, four regions, the surface, 1/8T, 1/4T and 1/2T, were considered for fracture toughness specimens of KSNP (Korean Standard Nuclear Plant) SA508 Gr. 3 steel to investigate deterministic material inhomogeneity and random inhomogeneity. Fracture toughness tests were carried out for four regions and three test temperatures in the transition region. Fracture toughness evaluation was performed using the bimodal master curve (BMC) approach which is applicable to the inhomogeneous material. The results of the bimodal master curve analyses were compared with that of conventional master curve analyses. As a result, the bimodal master approach considering inhomogeneous materials provides better description of scatter in fracture toughness data than conventional master curve analysis. However, the difference in the $T_0$ determined by two master curve approaches was insignificant.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.58.1-58.1
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• 2013

The main idea of the Alcock-Paczynski (AP) test is that, if we use a wrong distance-redshift relation to infer the shape of a spherical object in the Universe, this object may look non-spherical. To probe the cosmic expansion history through the AP test, the key point is to find something which is known as spherical in the Universe. We propose two possible ways applying the AP test to the large scale structure (LSS): 1) Based on the observed galaxies or quasars, one built up the beta-skeleton tracing the LSS, and investigating the inhomogeneity of the connections; 2) One reconstructs the smoothed density-contrast gradient field based on LSS observations, and investigating the inhomogeneity of the gradient vectors. Compared with some existed methods probing AP effect through 2-point correlation function, galaxy pairs, or voids, our methods have various advantages: 1) The information of both the high and low dense regions of the LSS are taken into account. 2) The redshift space distortion as the main contamination to the AP effect can be easily removed.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4112-4119
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• 2023

This study employs the microshear test method to examine the local mechanical properties of narrow-gap welded joints, revealing the mechanical inhomogeneity by evaluating the microshear strength, stress-strain curves, and failure strain. On this basis, the influence of weld joints micromechanical inhomogeneity on the crack tip opening displacement (CTOD) fracture toughness is investigated. From the root weld layer to the cover weld layer, the fracture toughness at the center of the weld seam demonstrates an increasing trend, with the experimental and calculated CTOD values showing a good correspondence. The microproperties of the welded joints significantly impact the load-bearing capacity and fracture toughness. During the deformation process of the "low-matching" microregions, the plastic zone expansion is hindered by the surrounding microregion strength constraints, thus reducing the fracture toughness. In contrast, during the deformation of the "high-matching" microregions, the surrounding microregions absorb some of the loading energy, partially releasing the concentrated stress at the crack tip, which in turn increases the fracture toughness.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.271-281
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• 2010

Brazing fitting which is one of the aircraft hydraulic power system components is widely used for saving weight and achieving higher reliability. Any inherent defects or damage of fitting can cause system failure and/or physical damage of human body due to highly pressurized fluid. Radiographic testing(RT) technique and additional micro-structure investigation on cut-away surfaces have been accomplished to find out some defect-like-inhomogeneity in the fittings. The radiography results showed that some defect-like-inhomogeneity existed inside body. Additional micro-structure investigation on cut-away surface reveals that the inhomogeneity is due to internal voids. In this study, it can be is said that RT technique can be a useful tool for field acceptance test of hydraulic brazing fitting in short time.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1043-1050
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• 2010

Fuel stratification and thermal stratification occur in the HCCI combustion chamber on a microscopic scale. They affect the ignition and combustion processes. In this study, the effect of the inhomogeneity in the mixture gas on the HCCI combustion process was investigated. Two-dimensional chemiluminescence images were captured using a framing camera to evaluate the flame structure. DME was used as the test fuel. First, the effect of inhomogeneity in the fuel distribution in the premixture was investigated for the four-stroke optically accessible engine. Then, by comparing the combustion of the homogeneous mixture in the rapid compression machine, which does not contain any residual gas, with the combustion in the four-stroke engine, the effect of inhomogeneity in temperature due to the residual gas was analyzed. The results showed that a time lag appears spatially in combustion under inhomogeneous conditions in the four-stroke engine. The spatial variation in the combustion without the residual gas in the rapid compression machine is less than that in the combustion in the four-stroke engine.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.18 no.3
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• pp.225-244
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• 2014

In this work, we discuss segmentation algorithms based on the level set method that incorporates shape prior knowledge. Fundamental segmentation models fail to segment desirable objects from a background when the objects are occluded by others or missing parts of their whole. To overcome these difficulties, we incorporate shape prior knowledge into a new segmentation energy that, uses global and local image information to construct the energy functional. This method improves upon other methods found in the literature and segments images with intensity inhomogeneity, even when images have missing or misleading information due to occlusions, noise, or low-contrast. We consider the case when the shape prior is placed exactly at the locations of the desired objects and the case when the shape prior is placed at arbitrary locations. We test our methods on various images and compare them to other existing methods. Experimental results show that our methods are not only accurate and computationally efficient, but faster than existing methods as well.

• Smart Structures and Systems
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• v.13 no.1
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• pp.155-171
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• 2014

Various monitoring techniques are now available for structural health monitoring and Acoustic Emission (AE) is one of them. One of the major advantages of the AE technique is its capability to locate active cracks in structural members. AE crack locating approaches are affected by the signal attenuation and dispersion of elastic waves due to inhomogeneity and geometry of reinforced concrete (RC) members. In this paper, a novel technique is described based on signal processing and sensor arrangement to process multisensory AE data generated by the onset and propagation of cracks and is validated with experimental results from an in-situ load test. Considering the sources of uncertainty in the AE crack location process, a methodology is proposed to capture and locate events generated by cracks. In particular, the relationship between AE events and load is analyzed, and the feasibility of using the AE technique to evaluate the cracking behavior of two RC slab strips during loading to failure is studied.

• Composites Research
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• v.13 no.2
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• pp.72-80
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• 2000

Effect of graphite powder addition on the mechanical properties of carbon fiber reinforced carbon composites (C/C composites) was investigated. Greenbody (G/B) with 0~30wt.% graphite powder addition to phenol resin was prepared and carbonized at $1000^{\circ}C$ to make C/C composites. Flexural strengths of 20wt.% graphite powder additions showed maximum values in the both case of G/B and C/C composites. But, at the graphite addition over 20wt.%, there was negative effect due to the matrix inhomogeneity. Flexural strength of cured resin without graphite Powder was higher than that with graphite. However, flexural strength of carbonized resin with graphite increased three times as much as that of carbonized resin without graphite. Because the addition of graphite powder effects the restraint of shrinkage after carbonization and the deflection of crack path. In Mode II ENF test, energy release rates($G_{II}$) of G/B and C/C composites with the 20w1.% addition of graphite were both increased. But, the addition of graphite was more effective to the increase of $G_{II}$ in C/C composites than that in G/B.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.3
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• pp.99-103
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• 2011

Radiation Therapy has been used in the treatment of breast cancer for over 80 years. Technically, it should include a part or all of such areas as chest wall or breast, axilla, internam mammary nodes and supraclavicular nodes. The purpose of this study is treated breast cancer patient to use 6 MV, 10 MV with bolus so that we observe changing of skin dose and evaluate those usefulness. Using woman's phantom, after CT simulate scanning, Through RTP system to make treatment plan, select three any place. And then, we measure that dose rate. After moving the phantom to linac, we put for TLD to three point same as RTP system which we put on the phantom. We exposed 6 MV, 10 MV with bolus and without so that it is measured dose by TLD device(4000 Harshaw). As a reult expose 6 MV,10 MV, it differences 10%, 15% according to bolus and withoout bolus where lateral point from RAO, LPO beam, other one is 20% where the furthest from both beams. To use bolus in the hospital is material to include closely part at skin among tissue of breast cancer. Acquired skin dose from RTP system is uncertainity. So it has to test another system likely TLD or other dosimetry system. Also exposed field of breast cancer is included inhomogeneity such as lung, bone and so on. Therefore it has to be accomplished a dose calculating of inhomogeneity part from treatment plan.