• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.3
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• pp.31-40
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• 2012

The irregularity of railway track affects not only the comfort of ride such as noise or vibration but also the safety of train operation. For this reason, it is an interesting research area to design a reliable and sustainable railway track system and to analyze the train movement mechanism based on systematic approaches considering reasons of track irregularity possible in a specific local environment. Irregularity data inspected by EM-120, an railway inspection system in Korea includes unavoidable incomplete and erratic information, so it is encountered lots of problem to analyse those data without appropriate pre-data-refining processes. In this research, for the efficient management and maintenance of railway system, progress rate of standard deviation of irregularity is quantified. During the computation, some important components of railways such as rail joint, ballast, roadbed, and fastener have been considered. Probabilistic distributions of irregularity growth with respect to time are computed to predict the remaining service life of railway track and to be adapted for the safety assessment.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.30-36
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• 2015

Austenite stainless steel(SA213-TP347H) has widely been used for the superheater & reheater tube in USC(ultra-supercritica) coal boiler because of its high creep rupture strength and anti-oxidation. But recently, the short-term failures have happened frequently in heat affected zone for only 4,000~15,000hours of service. Many investigations have been conducted to understand the failure mechanism. The root cause of failure was comfirmed to "strain induce participation hardening crack" or "reheat cracking". This mechanism often occurred due to weld residual stress and precipitation of the Cr, Nb carbides in the stabilized stainless steel such as TP347H. This paper presents an analysis of failure tube and effect of the sample tubes that conducting stabilizing heat treatment in site after 11,380hours & 16,961hours of service. Visual inspection was performed. In addition, microscopic characteristics was identified by O.M, SEM, and hardness test was carried out to find out the heat treatment effects. Failures seem to happen because of being not conducted stabilizing heat treatment in site. And another cause is inadequate weld parameter such as pass, ampere, voltage, inter-pass temperature. Thus, this paper has the purpose to describe that how to prevent similar failures in those weld-joints.

• Smart Structures and Systems
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• v.29 no.1
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• pp.195-206
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• 2022

Crack detection is essential for inspection of existing structures and crack segmentation based on deep learning is a significant solution. However, datasets are usually one of the key issues. When building a new dataset for deep learning, laborious and time-consuming annotation of a large number of crack images is an obstacle. The aim of this study is to develop an approach that can automatically select a small portion of the most informative crack images from a large pool in order to annotate them, not to label all crack images. An active learning method with difficulty learning mechanism for crack segmentation tasks is proposed. Experiments are carried out on a crack image dataset of a steel box girder, which contains 500 images of 320×320 size for training, 100 for validation, and 190 for testing. In active learning experiments, the 500 images for training are acted as unlabeled image. The acquisition function in our method is compared with traditional acquisition functions, i.e., Query-By-Committee (QBC), Entropy, and Core-set. Further, comparisons are made on four common segmentation networks: U-Net, DeepLabV3, Feature Pyramid Network (FPN), and PSPNet. The results show that when training occurs with 200 (40%) of the most informative crack images that are selected by our method, the four segmentation networks can achieve 92%-95% of the obtained performance when training takes place with 500 (100%) crack images. The acquisition function in our method shows more accurate measurements of informativeness for unlabeled crack images compared to the four traditional acquisition functions at most active learning stages. Our method can select the most informative images for annotation from many unlabeled crack images automatically and accurately. Additionally, the dataset built after selecting 40% of all crack images can support crack segmentation networks that perform more than 92% when all the images are used.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.41.3-41.3
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• 2019

To find out the origin and formation mechanism of LASCO-C2 post-CME blobs, we investigate 2 LASCO-C2 blobs and 35 low corona blobs observed by K-Cor on 2017 September 10 from 17:11 to 18:58 UT. By visual inspection of a post-CME ray and the locations of low corona blobs in K-Cor and LASCO-C2 images with examining the time-height data of all blobs, we find the following results: (1) The post-CME ray structure is well identified in the K-Cor images than LASCO-C2 ones. (2) Low corona blobs can be classified into two groups according to their formation mechanisms: 27 blobs belong to Group 1, generated by the tearing mode instability near the middles of current sheets as described by Furth et al., 1963; Shibata & Tanuma, 2001; Shen et al., 2011, the others belong to Group 2, formed by the tearing mode instability near the tips of current sheets as shown in Figure 5 of Sitnov et al., 2002. (3) Group 1 has low initial appearance heights <1.30 Rs>, broad speed range (38 ~ 945 km/s), and high accelerations <4,272 m/s² > than Group 2, which has initial appearance heights <1.72 Rs>, speed range (579 ~ 843 km/s), and accelerations <1,413 m/s² >. (4) among 8 blobs for Group 2, only 2 blobs are temporally and spatially associated with 2 LASCO-C2 ones and their initial observation heights are 1.93 and 1.79 Rs, respectively. Our results firstly demonstrate that LASCO-C2 blobs form the heights from about 1.7 to 2.0 Rs and they are generated by the tearing mode instability near the tips of current sheets.

• Journal of Korean Medical classics
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• v.30 no.2
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• pp.31-43
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• 2017

Objectives : Written by Yoongdongri in the 18th century Chosun, Chochangkyeul is a book that specially deals in Ungi. Yoon understood a person's body constitution by taking into factor the person's birth year, and used this information to determine his Ungi type, and understood his disease mechanism. Methods : Following the study on the first part of Chochangkyeul, named Ungiyeonron, the paper tries to study the book's second part, called Yongyakgwon. The book's core messages are summarized upon a thorough inspection. Results & Conclusions : Yoondongri was a highly-acclaimed doctor in the 18th century Chosun, and also an Ungi practitioner who utilized the theory of Ungi in his clinical practices. His practices were mainly based on the prescription of Ungi found in Chenwuze's Sanyinfang, coupled with almost all parts of Donguibogam's Husebang. He had an extensive clinical experience which helped him describe his methods of quickly responding to the side effects that sometimes occur due to misuse of medicine. Such detailed descriptions are never found in past medical books, which gives Yoon's book a great level of historical importance. Yongyakgwon divides the scripts between Gabsin, Muui, Byungye, Gyungjeong, and Yimgi in accordance with the theory of Ounhabgi, and also introduces treatments based on Yukisachun. Jangbupasuyak also introduces about six external organs and six internal organs with relation to treating wind medicine, treating heat medicine, treating cold medicine, treating dry dampness medicine, dryness-moistening medicine, pulling meridian medicine. All of these can be applied to patients easily.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.15 no.1
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• pp.47-54
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• 2011

In traditional Korean medicine, inspection of the tongue is an important method of making medical diagnoses and determining prognosis. We surveyed the fluorescence characteristics of the tongue coat in the ultraviolet light. The tongue coat comprises micro-organisms, blood metabolites, leukocytes from periodontal pockets, large amounts of desquamated epithelial cells released from the oral mucosa and different nutrients. In the ultraviolet light tissues of the oral cavity generally emit weak red or green fluorescence, which is not easily seen by the human eye, but is readily detected. This fluorescence has been proved to be due to the production of porphyrins by oral micro-organisms. While the composition of motile micro-organisms on the dorsum of the tongue is not constant, variations also occur persistingly in the fluorescence characteristics of the tongue coat. But because live bacteria contain a variety of intracellular biomolecules that have specific excitation and emission wavelength spectra characterizing their intrinsic fluorescence, the tongue coat emits fluorescence. the tongue itself, on the other hand, emits very weak or not fluorescence. In conclusion, we suggests that the uncoated tongue area be eliminated from the coated tongue area with the difference between the fluorescence characteristics of the tongue and that of the tongue coat.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.684-690
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• 2010

A drum cam with rotational follower has a cam mechanism and it is mainly used in its application such as index table and ATC of machine tool. Also its use can reduce the backlash in its kinematic movement. To machine the drum cam with rotational follower, 5-axis CNC machine tool is generally used and its kinematic principle is included in it's design. Until now, the commercialized CAM software can't cover the application of the drum cam machining. Even if, some special software was developed for machining a drum cam, the post processing method for finish machining was not developed yet. And to overcome the problem, the form tool is still used on the tool path of rough machining. This study includes the induction of the post processing technique for the finish machining of drum cam on three 5-axis CNC machine tools, type AC, AB and BC. To prove the finishing geometric profile, the result was clearly verified through inspection and geometric measurement after direct machining of the drum cam in AC type 5-axis machine tool in this study.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.2
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• pp.13-19
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• 2009

As the operating time in nuclear power plants (NPPs) increases, the integrity of nuclear components may be continually degraded due to aging effects of systems, structures and components. Recently, a number of NPPs are being operated beyond their design life to produce more electricity without shutting down. The critical issue in extending a lifetime is to maintain the level of safety during the extended operation period while satisfying the international regulatory standards. Therefore, it is beneficial to build a monitoring system to measure an aging status. In this paper, the Aging Monitor (AM) based on lots of aging database obtained from the operating plants and research results on the aging effects was developed to monitor, manage and evaluate the aging phenomena systematically and effectively in NPPs. The AM for the CANDU is divided into 6 modules: (1) Aging Alarm/Coloring Monitor, (2) Aging Database, (3) Aging Document, (4) Real-time Integrity Monitor, (5) Surveillance and Inspection Management System, and (6) Continued Operation and Periodic Safety Review (PSR) Safety Evaluation. The proposed system is expected to provide the integrity assessment for the major mechanical components of an NPP under concurrent working environments.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2307-2310
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• 2005

A pressurizer is one of the major safety related equipment of nuclear power plants. In order to inspect and maintain the internal structures of a pressurizer, jumpers have to enter the pressurizer, in spite of the high dose exposure. Therefore, a tele-operated robotic manipulator has been developed, which consists of four parts with 2DOFs arms, a gripper, base frame, and control console. The task of this robotic manipulator is to extract the damaged electric heaters and inspect the internal structure of the pressurizer. The gripper hanging from the manipulator approaches the heaters and extracts the damaged heater by using a self-locking mechanism. In order to investigate the structural stability of the robotic manipulator, a stress analysis has been performed by using the ANSYS code. The results of this paper include the position control and vibration control of robotic gripper and the development of processing visual information for a vision sensor.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.31.2-31.2
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• 2016

We present our study of the correlation between the UV luminosity and the merging activities of nearby galaxies (d < 300 Mpc). Our study uses ~600 UV-selected galaxies with deep optical imaging data, where the UV selection is made using the GALEX Atlas of Galaxies (Gil de Paz et al. 2007) and the updated UV catalog of nearby galaxies (Yu Bai et al. 2015). Deep optical images allow us to classify merger features using visual inspection, and we also estimate unobscured SFR using UV continuum luminosity. The fraction of galaxies with merger features in each UV luminosity bins are obtained to see if how the fraction of galaxies with merging features changes as a function of UV luminosity, Finally, we will show, above what UV luminosity (or SFR), the merging mechanism becomes an important process in enhancing star formation of galaxies.