• Title/Summary/Keyword: Earlier Detection

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Nondestructive damage evaluation of a curved thin beam

  • Kim, Byeong Hwa;Joo, Hwan Joong;Park, Tae Hyo
    • Structural Engineering and Mechanics
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    • v.24 no.6
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    • pp.665-682
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    • 2006
  • A vibration-based nondestructive damage evaluation technique for a curved thin beam is introduced. The proposed method is capable of detecting, locating, and sizing structural damage simultaneously by using a few of the lower natural frequencies and their corresponding mode shapes before and after a small damage event. The proposed approach utilizes modal flexibilities reconstructed from measured modal parameters. A rigorous system of equations governing damage and curvature of modal flexibility is derived in the context of elasticity. To solve the resulting system of governing equations, an efficient pseudo-inverse technique is introduced. The direct inspection of the resulting solutions provides the location and severity of damage in a curved thin beam. This study confirms that there is a strong linear relationship between the curvature of modal flexibility and flexural damage in the selected class of structures. Several numerical case studies are provided to justify the performance of the proposed approach. The proposed method introduces a way to avoid the singularity and mode selection problems from earlier attempts.

Underwater Acoustic Research Trends with Machine Learning: Ocean Parameter Inversion Applications

  • Yang, Haesang;Lee, Keunhwa;Choo, Youngmin;Kim, Kookhyun
    • Journal of Ocean Engineering and Technology
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    • v.34 no.5
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    • pp.371-376
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    • 2020
  • Underwater acoustics, which is the study of the phenomena related to sound waves in water, has been applied mainly in research on the use of sound navigation and range (SONAR) systems for communication, target detection, investigation of marine resources and environments, and noise measurement and analysis. Underwater acoustics is mainly applied in the field of remote sensing, wherein information on a target object is acquired indirectly from acoustic data. Presently, machine learning, which has recently been applied successfully in a variety of research fields, is being utilized extensively in remote sensing to obtain and extract information. In the earlier parts of this work, we examined the research trends involving the machine learning techniques and theories that are mainly used in underwater acoustics, as well as their applications in active/passive SONAR systems (Yang et al., 2020a; Yang et al., 2020b; Yang et al., 2020c). As a follow-up, this paper reviews machine learning applications for the inversion of ocean parameters such as sound speed profiles and sediment geoacoustic parameters.

Lipophilic Crown-4 Derivatives as Lithium Ionophores for Lithium Ion Selective Liquid Membrane Electrodes

  • Jae Sang Kim;Sung Ouk Jung;Shim Sung Lee;Si-Joong Kim
    • Bulletin of the Korean Chemical Society
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    • v.14 no.1
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    • pp.123-127
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    • 1993
  • New lipophilic Crown-4 compounds of 16-membered rings containing furan (neutral carrier,I), tetrahydrofuran (neutral carrier,II) and lithium complex of the latter (neutral carrier,III) have been synthesized and tested as the active sensors for lithium ion in poly(vinyl chloride) (PVC) membrane electrode, in the presence and absence of an anion excluder, tetrakis(4-chloro-phenyl)borate (KTClPB), 2-nitrophenyl phenyl ether (NPPE), tris(2-ethylhexyl)phosphate (TEHP), o-nitrophenyl octyl ether (NPOE), dioctyl adipate (DOA), bis(2-ethylhexyl)adipate (BEHA), di-n-octylphenyl phosphonate (DOPP) were used as plasticizing solvent mediators. The electrode response function had a nearly Nernstian slope of 54-61 mV per decade (25$^{\circ}$C) within the concentration range of $10^{-1}-10^{-4}$ M LiCl and the detection limits for all electrodes were ca. $5{\times}10^{-4}$ M. The response time of the electrode was faster at the higher lithium concentration and the response of the electrode was stable for longer than 6 months. The sensor membranes exhibit improved response times and increased lifetimes as compared to the system described earlier.

Upgrade of gamma electron vertex imaging system for high-performance range verification in pencil beam scanning proton therapy

  • Kim, Sung Hun;Jeong, Jong Hwi;Ku, Youngmo;Jung, Jaerin;Cho, Sungkoo;Jo, Kwanghyun;Kim, Chan Hyeong
    • Nuclear Engineering and Technology
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    • v.54 no.3
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    • pp.1016-1023
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    • 2022
  • In proton therapy, a highly conformal proton dose can be delivered to the tumor by means of the steep distal dose penumbra at the end of the beam range. The proton beam range, however, is highly sensitive to range uncertainty, which makes accurately locating the proton range in the patient difficult. In-vivo range verification is a method to manage range uncertainty, one of the promising techniques being prompt gamma imaging (PGI). In earlier studies, we proposed gamma electron vertex imaging (GEVI), and constructed a proof-of-principle system. The system successfully demonstrated the GEVI imaging principle for therapeutic proton pencil beams without scanning, but showed some limitations under clinical conditions, particularly for pencil beam scanning proton therapy. In the present study, we upgraded the GEVI system in several aspects and tested the performance improvements such as for range-shift verification in the context of line scanning proton treatment. Specifically, the system showed better performance in obtaining accurate prompt gamma (PG) distributions in the clinical environment. Furthermore, high shift-detection sensitivity and accuracy were shown under various range-shift conditions using line scanning proton beams.

Stackelberg Game between Multi-Leader and Multi-Follower for Detecting Black Hole and Warm Hole Attacks In WSN

  • S.Suganthi;D.Usha
    • International Journal of Computer Science & Network Security
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    • v.23 no.8
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    • pp.159-167
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    • 2023
  • Objective: • To detect black hole and warm hole attacks in wireless sensor networks. • To give a solution for energy depletion and security breach in wireless sensor networks. • To address the security problem using strategic decision support system. Methods: The proposed stackelberg game is used to make the spirited relations between multi leaders and multi followers. In this game, all cluster heads are acts as leaders, whereas agent nodes are acts as followers. The game is initially modeled as Quadratic Programming and also use backtracking search optimization algorithm for getting threshold value to determine the optimal strategies of both defender and attacker. Findings: To find optimal payoffs of multi leaders and multi followers are based on their utility functions. The attacks are easily detected based on some defined rules and optimum results of the game. Finally, the simulations are executed in matlab and the impacts of detection of black hole and warm hole attacks are also presented in this paper. Novelty: The novelty of this study is to considering the stackelberg game with backtracking search optimization algorithm (BSOA). BSOA is based on iterative process which tries to minimize the objective function. Thus we obtain the better optimization results than the earlier approaches.

Blood Biomarkers for Alzheimer's Dementia Diagnosis (알츠하이머성 치매에서 혈액 진단을 위한 바이오마커)

  • Chang-Eun, Park
    • Korean Journal of Clinical Laboratory Science
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    • v.54 no.4
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    • pp.249-255
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    • 2022
  • Alzheimer's disease (AD) represents a major public health concern and has been identified as a research priority. Clinical research evidence supports that the core cerebrospinal fluid (CSF) biomarkers for AD, including amyloid-β (Aβ42), total tau (T-tau), and phosphorylated tau (P-tau), reflect key elements of AD pathophysiology. Nevertheless, advances in the clinical identification of new indicators will be critical not only for the discovery of sensitive, specific, and reliable biomarkers of preclinical AD pathology, but also for the development of tests that facilitate the early detection and differential diagnosis of dementia and disease progression monitoring. The early detection of AD in its presymptomatic stages would represent a great opportunity for earlier therapeutic intervention. The chance of successful treatment would be increased since interventions would be performed before extensive synaptic damage and neuronal loss would have occurred. In this study, the importance of developing an early diagnostic method using cognitive decline biomarkers that can discriminate between normal, mild cognitive impairment (MCI), and AD preclinical stages has been emphasized.

Anomaly Detection for User Action with Generative Adversarial Networks (적대적 생성 모델을 활용한 사용자 행위 이상 탐지 방법)

  • Choi, Nam woong;Kim, Wooju
    • Journal of Intelligence and Information Systems
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    • v.25 no.3
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    • pp.43-62
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    • 2019
  • At one time, the anomaly detection sector dominated the method of determining whether there was an abnormality based on the statistics derived from specific data. This methodology was possible because the dimension of the data was simple in the past, so the classical statistical method could work effectively. However, as the characteristics of data have changed complexly in the era of big data, it has become more difficult to accurately analyze and predict the data that occurs throughout the industry in the conventional way. Therefore, SVM and Decision Tree based supervised learning algorithms were used. However, there is peculiarity that supervised learning based model can only accurately predict the test data, when the number of classes is equal to the number of normal classes and most of the data generated in the industry has unbalanced data class. Therefore, the predicted results are not always valid when supervised learning model is applied. In order to overcome these drawbacks, many studies now use the unsupervised learning-based model that is not influenced by class distribution, such as autoencoder or generative adversarial networks. In this paper, we propose a method to detect anomalies using generative adversarial networks. AnoGAN, introduced in the study of Thomas et al (2017), is a classification model that performs abnormal detection of medical images. It was composed of a Convolution Neural Net and was used in the field of detection. On the other hand, sequencing data abnormality detection using generative adversarial network is a lack of research papers compared to image data. Of course, in Li et al (2018), a study by Li et al (LSTM), a type of recurrent neural network, has proposed a model to classify the abnormities of numerical sequence data, but it has not been used for categorical sequence data, as well as feature matching method applied by salans et al.(2016). So it suggests that there are a number of studies to be tried on in the ideal classification of sequence data through a generative adversarial Network. In order to learn the sequence data, the structure of the generative adversarial networks is composed of LSTM, and the 2 stacked-LSTM of the generator is composed of 32-dim hidden unit layers and 64-dim hidden unit layers. The LSTM of the discriminator consists of 64-dim hidden unit layer were used. In the process of deriving abnormal scores from existing paper of Anomaly Detection for Sequence data, entropy values of probability of actual data are used in the process of deriving abnormal scores. but in this paper, as mentioned earlier, abnormal scores have been derived by using feature matching techniques. In addition, the process of optimizing latent variables was designed with LSTM to improve model performance. The modified form of generative adversarial model was more accurate in all experiments than the autoencoder in terms of precision and was approximately 7% higher in accuracy. In terms of Robustness, Generative adversarial networks also performed better than autoencoder. Because generative adversarial networks can learn data distribution from real categorical sequence data, Unaffected by a single normal data. But autoencoder is not. Result of Robustness test showed that he accuracy of the autocoder was 92%, the accuracy of the hostile neural network was 96%, and in terms of sensitivity, the autocoder was 40% and the hostile neural network was 51%. In this paper, experiments have also been conducted to show how much performance changes due to differences in the optimization structure of potential variables. As a result, the level of 1% was improved in terms of sensitivity. These results suggest that it presented a new perspective on optimizing latent variable that were relatively insignificant.

It Was Possible to Reduce the Pain of the Victims of Humidifier Disinfectant (가습기살균제 피해자의 아픔을 줄일 수 있었다)

  • Kim, Pangyi;Choi, Yoon-Hyeong;Park, YeongChul;Park, Tae-Hyun;Leem, JongHan
    • Journal of Environmental Health Sciences
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    • v.48 no.1
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    • pp.1-8
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    • 2022
  • Objectives: The purpose of this study is to reveal the circumstances under which the cases of harm to health caused by humidifier disinfectant were neglected and show the points where the number of victims and the degree of damage could have been reduced. In addition, it attempts to describe how damage management proceeded immediately after the incident and actually exacerbated the damage. Finally, it explores the unfortunate aspects of the recent trial. By doing so, it attempts to take this as an opportunity to consider whether a tragic event such as the humidifier disinfectant incident could occur in the future. Methods: This study collected and analyzed data on chemical material characteristics related to humidifier disinfectants, data on health effect characteristics, data on related laws and regulations from the Ministry of Environment, data related to the damage investigation by the Korea Environmental Industry and Technology Institute, and current contents. Results: The lack of related systems and laws is the area where the greatest responsibility for the cause of the humidifier disinfectant disaster falls, so it is difficult for the government to escape this responsibility. Establishing a dedicated department to identify the prevalence of certain diseases within the functions of the Health Insurance Review and Assessment Service to monitor health can greatly contribute to the prevention and management of diseases through early detection and management of group outbreaks caused by harmful factors. Humidifier disinfectant damage relief should have been expanded earlier beyond HDLI (humidifier disinfectant lung injury) to include non-specific diseases such as asthma, pneumonia, and interstitial pneumonia. The scope of relief benefits should have also been expanded earlier to include the payment of disability benefits. Fortunately, with the 2020 revision of the Special Act, the conditions for estimating causal relations were eased and individual screening systems such as health impact assessment were reorganized along with the introduction of a rapid screening system. Conclusions: The management system for chemical substances in a country is clearly of paramount importance, and the ministry in charge must have a response system in case of damage to health effects. Administration that looks at the victims' situation from their point of view is needed, and technical countermeasures are required to quickly recognize the prevalence of certain diseases.

Differential Expression of Genes Important to Efferent Ductules Ion Homeostasis across Postnatal Development in Estrogen Receptor-α Knockout and Wildtype Mice

  • Lee, Ki-Ho;Bunick, David;Lamprecht, Georg;Choi, Inho;Bahr, Janice M.
    • Asian-Australasian Journal of Animal Sciences
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    • v.21 no.4
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    • pp.510-522
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    • 2008
  • Our earlier studies showed that estrogen was involved in the regulation of fluid reabsorption in adult mouse efferent ductules (ED), through estrogen receptor (ER) ${\alpha}$ and $ER{\beta}$ by modulating gene expression of epithelial genes involved in ion homeostasis. However, little is known about the importance of $ER{\alpha}$ in the ED during postnatal development. Based on previous findings, we hypothesized that there should be a difference in the expression of epithelial ion transporters and anion producers in the ED of postnatal wild type (WT) and estrogen receptor ${\alpha}$ knockout (${\alpha}ERKO$) mice. Using absolute, comparative and semi-quantitative RT-PCR along with immunohistochemistry, we looked at expression levels of several genes in the ED across postnatal development. The presence of estrogen in the testicular fluid was indirectly ascertained by immunohistochemical detection of the P450 aromatase in the testis. There was no immunohistochemically detectable difference in the expression of P450 aromatase in the testes and ER${\beta}$ in the ED of WT and ${\alpha}$ERKO mice. ER${\alpha}$ was only detected in the ED of WT mice. The absence of ER${\alpha}$ in the ED of postnatally developing mice resulted in differential expression of mRNAs and/or proteins for carbonic anhydrase II, $Na^+/H^+$ exchanger 3, down-regulated in adenoma, cystic fibrosis transmembrane regulator, and $Na^+/K^+$ ATPase ${\alpha}$. Our data indicate that the absence of ER${\alpha}$ resulted in altered expression of an epithelial ion producer and transporters during postnatal development of mice. We conclude that the presence of ER${\alpha}$is important for regulation of the ED function during the prepubertal developmental and postpubertal period.

MICRODONTIA IN A CHILD TREATED WITH CHEMOTHERAPEUTIC AGENT (항암 화학치료를 받은 아동의 치아발육이상 : 증례 보고)

  • Kye, Hi-Ran;Lee, Jae-Ho;Kim, Seong-Oh;Sohn, Heung-Kyu
    • Journal of the korean academy of Pediatric Dentistry
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    • v.26 no.1
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    • pp.146-150
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    • 1999
  • With the improved cure rates for childhood malignant conditions in the past decade, late effects of cancer therapy must be recognized to minimize their impact on the quality of life in long-term survivors. Chemoradiation therapy is a major part of pediatric oncology treatment and is implicated in causing tooth agenesis, microdontia, root shortening, early apical closure, and coronal hypocalcification. Dental development may be affected by illness, trauma, chemotherapy, or radiation therapy at any point prior to complete maturation. Treatment given during the first 3.5 years of life was more likely to affect the dental lamina and crown formation and result in a small tooth. Dental treatment affected by chemoradiation damage to developing teeth includes orthodontic tooth movement, prosthetic abutment consideration, periodontal health, space maintenance, requirement for home fluoride regimens to protect hypomineralized teeth, and enodontic procedures. Dental abnormalities are common in patients treated for cancer, and these children require aggressive dental follow-up. Meticulous surveillance may facilitate detection of abnormalities, enabling the dental practitioner to intervene earlier in promoting a more aggressive regimen of oral care, thus reducing the morbidity associated with dental sequelae of oncotherapy, specifically periodontal disease and malocclusion. In this case, we report microdontia of all permanent second premolar and second molar in an 8 year old boy treated with chemotherapeutic agents during period of active dental development(14 months to 38 months of age).

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