• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 학술대회 논문집
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• pp.371-374
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• 2004

Induction motors are a critical component of many industrial processes and are frequently integrated in commercially available equipment. Safety, reliability, efficiency, and performance are some of the major concerns of induction motor applications. Preventive maintenance of induction motors has been a topic great interest to industry because of their wide range application of industry. Since the use of mechanical sensors, such as vibration probes, strain gauges, and accelerometers is often impractical, the motor current signature analysis (MACA) techniques have gained murk popularity as diagnostic tool. Fault tolerant control (FTC) strives to make the system stable and retain acceptable performance under the system faults. All present FTC method can be classified into two groups. The first group is based on fault detection and diagnostics (FDD). The second group is independent of FDD and includes methods such as integrity control, reliable stabilization and simultaneous stabilization. This paper presents the fundamental FDD-based FTC methods, which are capable of on-line detection and diagnose of the induction motors. Therefore, our group has developed the embedded distributed fault tolerant and fault diagnosis system for industrial motor. This paper presents its architecture. These mechanisms are based on two 32-bit DSPs and each TMS320F2407 DSP module is checking stator current, voltage, temperatures, vibration and speed of the motor. The DSPs share information from each sensor or DSP through DPRAM with hardware implemented semaphore. And it communicates the motor status through field bus (CAN, RS485). From the designed system, we get primitive sensors data for the case of normal condition and two abnormal conditions of 3 phase induction motor control system is implemented. This paper is the first step to drive multi-motors with serial communication which can satisfy the real time operation using CAN protocol.

• 한국재료학회지
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• 제26권10호
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• pp.561-569
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• 2016

$SrAl_2O_4$: $Eu^{2+}$ and $Dy^{3+}$ phosphorescent phosphors were synthesized using the polymerized complex method. Generally, phosphorescent phosphors synthesized by conventional solid state reaction show a micro-sized particle diameter; thus, this process is restricted to applications such as phosphorescent ink and paint. However, it is possible to synthesize homogeneous multi-component powders with fine particle diameter by wet process such as the polymerized complex method. The characteristics of $SrAl_2O_4$: $Eu^{2+}$ and $Dy^{3+}$ powders prepared by polymerized complex method with one and two step calcination processes were comparatively analyzed. Temperatures of organic material removal and crystallization were observed through TG-DTA analysis. The crystalline phase and crystallite size of the $SrAl_2O_4$: $Eu^{2+}$ and $Dy^{3+}$ phosphorescent phosphors were analyzed by XRD. Microstructures and afterglow characteristics of the $SrAl_2O_4$: $Eu^{2+}$ and $Dy^{3+}$ phosphors were measured by SEM and spectrofluorometry, respectively.

• 한국초등과학교육학회지:초등과학교육
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• 제25권1호
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• pp.27-38
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• 2006

The purpose of this study was to develop a test of a creative problem solving (CPS) for the selection of gifted science students in elementary school. For this, the methods and procedures of the selection of gifted science students was investigated through the internet homepages 23 gifted science education centers of universities and 16 city. province offices of education. The results of this study were as follows: Most of the gifted science students were selected through a multi-step examination process. They were selected on the basis of their records by recommendation of a principal or a classroom teacher in their school, by operation of standardized tests (ex. intelligence quotient score, achievements in science and mathematics, interest and attitude/aptitude for science as well as through other means), as well as through intensive observation of those gifted science students who are selected by interview and oral tests. The selection of gifted students was not evaluated through creativity testing; giftedness in city. province office of education. Testing of CPS was found to be especially lacking in these organizations. For the development of the test items of CPS in science, the five elements were extracted through the framework for the content analysis of the CPS: problem exploration, problem statement, solution thinking, experiment design, and assesment. In addition, suggestions were made regarding an appropriate scoring system for the test of the CPS. As the result of the developed test was applied to the 4th grade of the gifted and general student, we found that gifted students were superior to general students. In conclusion, it was that the CPS test developed in this study should be used to evaluate the CPS for the selection of gifted students.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권5호
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• pp.2122-2140
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• 2020

Proper and precise embedding of commercial ads within Webpages requires Ad-hoc analysis and understanding of their content. By the successful implementation of this step, both publishers and advertisers gain mutual benefits through increasing their revenues on the one hand, and improving user experience on the other. In this research work, we propose a novel multi-level context-based ads serving approach through which ads will be served at generic publisher websites based on their contextual relevance. In the proposed approach, knowledge encoded in domain-specific and generic semantic repositories is exploited in order to analyze and segment Webpages into sets of contextually-relevant segments. Semantically-enhanced indexes are also constructed to index ads based on their textual descriptions provided by advertisers. A modified cosine similarity matching algorithm is employed to embed each ad from the Ads repository into one or more contextually-relevant segments. In order to validate our proposal, we have implemented a prototype of an ad serving system with two datasets that consist of (11429 ads and 93 documents) and (11000 documents and 15 ads), respectively. To demonstrate the effectiveness of the proposed techniques, we experimentally tested the proposed method and compared the produced results against five baseline metrics that can be used in the context of ad serving systems. In addition, we compared the results produced by our system with other state-of-the-art models. Findings demonstrate that the accuracy of conventional ad matching techniques has improved by exploiting the proposed semantically-enhanced context-based ad serving model.

• 대한불안의학회지
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• 제9권1호
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• pp.54-60
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• 2013

Objectives : Posttraumatic stress disorder (PTSD) is classified as an anxiety disorder. PTSD occurrence is known to be increased in middle-aged and older people, female, and individuals with a previous history of psychiatric disorders, lower education levels, low socioeconomic status, and severely injured patients. Anxiety symptoms are also related to later development of PTSD. In this study, we investigate the influences of injury severity and sociodemographic factors on severe anxiety in PTSD patients with no previous history of psychiatric disorders. Methods : Forty-one PTSD patients without previous history of psychiatric disorders were recruited from the psychiatric clinic at Chosun University Hospital. Subjects underwent psychiatric and physical examinations including the Injury Severity Score (ISS), Beck Anxiety Inventory (BAI), and Korean-Wechsler Adult Intelligence Scale (K-WAIS). We defined severe anxiety as a BAI scores of 30 or more. Logistic regression analyses and multi-step model selection were applied to identify predictive factors for severe anxiety. Results : In univariate analysis, age, ISS, and socioeconomic status were found to be significant factors. Through multivariate logistic regression analyses and a stepwise model selection, we found the combination of age and ISS to be the best-fitted model for affecting severe anxiety in PTSD patients without a previous history of psychiatric disorders. Conclusion : Our findings suggest that the combination of age and ISS could develop severe anxiety in PTSD patients with no previous history of psychiatric disorders.

• Asian Pacific Journal of Cancer Prevention
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• 제17권3호
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• pp.1023-1035
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• 2016

The purpose of this study was to investigate the role of colon cancer stem cells (CSCs) during chemically-induced rat multi-step colon carcinogenesis with or without the treatment with a specific cyclooxygenase-2 inhibitor drug (celecoxib). Two experiments were performed, the first, a short term 12 week colon carcinogenesis bioassay in which only surrogate markers for colon cancer, aberrant crypt foci (ACF) lesions, were formed. The other experiment was a medium term colon cancer rat assay in which tumors had developed after 32 weeks. Treatment with celecoxib lowered the numbers of ACF, as well as the tumor volumes and multiplicities after 32 weeks. Immunohistochemical proliferating cell nuclear antigen (PCNA) labeling indexes LI (%) were downregulated after treatment by celecoxib. Also different cell surface antigens known to associate with CSCs such as the epithelial cell adhesion molecule (EpCAM), CD44 and CD133 were compared between the two experiments and showed differential expression patterns depending on the stage of carcinogenesis and treatment with celecoxib. Flow cytometric analysis demonstrated that the numbers of CD133 cells were increased in the colonic epithelium after 12 weeks while those of CD44 but not CD133 cells were increased after 32 weeks. Moreover, aldehyde dehydrogenase-1 activity levels in the colonic epithelium (a known CSC marker) detected by ELISA assay were found down-regulated after 12 weeks, but were up-regulated after 32 weeks. The data have also shown that the protective effect of celecoxib on these specific markers and populations of CSCs and on other molecular processes such as apoptosis targeted by this drug may vary depending on the genetic and phenotypic stages of carcinogenesis. Therefore, uncovering these distinction roles of CSCs during different phases of carcinogenesis and during specific treatment could be useful for targeted therapy.

• 한국유체기계학회 논문집
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• 제14권6호
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• pp.96-101
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• 2011

Korea Aerospace Research Institute is performing 3 stage transonic axial compressor development program. This paper introduces design step of the compressor, the performance test results and its analysis. In the fore part of the paper, aerodynamic process of the 3 stage axial compressor is presented. To satisfy both of the mass flow and pressure rise, the compressor should rotate at a high rotational speed. Therefore the transonic flow field forms in the rotor stages and it is designed with a relatively high pressure rise per stage to satisfy its design target. The compressor stage consists of 3 stages, and the bulk pressure ratio is 2.5. The first stage is burdened with the highest pressure ratio and less pressure rises occur in the following stages. Also it is designed that tip Mach number of the first rotor row does not exceed 1.3, while the maximum relative Mach number in the rotor stage is between 1.3~1.4 to increase the compressor flow coefficient. The final design has been confirmed by iterating three dimensional CFD calculations to verify design target and some design intentions. In the latter part of the paper, its performance test processes and results are presented. The performance test result shows that the overall compressor performance targets; pressure ratio and efficiency are well achieved. The stator static pressure distributions show that the blade loading is gradually increasing from the downstream of the compressor.

• Journal of Radiation Protection and Research
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• 제42권2호
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• pp.91-97
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• 2017

Background: A gamma energy identifying algorithm using spectral decomposition combined with smoothing method was suggested to confirm the existence of the artificial radio isotopes. The algorithm is composed by original pattern recognition method and smoothing method to enhance the performance to identify gamma energy of radiation sensors that have low energy resolution. Materials and Methods: The gamma energy identifying algorithm for the compact radiation sensor is a three-step of refinement process. Firstly, the magnitude set is calculated by the original spectral decomposition. Secondly, the magnitude of modeling error in the magnitude set is reduced by the smoothing method. Thirdly, the expected gamma energy is finally decided based on the enhanced magnitude set as a result of the spectral decomposition with the smoothing method. The algorithm was optimized for the designed radiation sensor composed of a CsI (Tl) scintillator and a silicon pin diode. Results and Discussion: The two performance parameters used to estimate the algorithm are the accuracy of expected gamma energy and the number of repeated calculations. The original gamma energy was accurately identified with the single energy of gamma radiation by adapting this modeling error reduction method. Also the average error decreased by half with the multi energies of gamma radiation in comparison to the original spectral decomposition. In addition, the number of repeated calculations also decreased by half even in low fluence conditions under $10^4$ ($/0.09cm^2$ of the scintillator surface). Conclusion: Through the development of this algorithm, we have confirmed the possibility of developing a product that can identify artificial radionuclides nearby using inexpensive radiation sensors that are easy to use by the public. Therefore, it can contribute to reduce the anxiety of the public exposure by determining the presence of artificial radionuclides in the vicinity.

• 한국인구학
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• 제29권1호
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• pp.71-95
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• 2006

이 연구에서는 결혼 만족과 결혼 안정에 영향을 미치는 관련 변인들을 실증 분석하였으며, 특히 성에 대한 이중 기준이 결혼 만족과 결혼 안정의 관계에 어떤 영향을 미치는지에 분석의 초점을 두었다. 이 단계 군집표집에 의해 선정된 370명의 기혼 여성으로부터 수집된 자료를 다단계 다중회귀분석을 통해 분석하였다. 결혼 만족에 영향을 미치는 요인으로는 부부간의 상호소통, 친밀성, 성적 만족을 분석에 포함시켰으며, 결혼 안정에 영향을 미치는 요인으로는 조사 대상자의 경제활동 여부, 가구 소득 수준 결혼 만족을 분석에 포함시켰다. 그리고 성에 대한 일반적 태도를 바탕으로 조사 대상자를 성에 대한 단일 기준 집단과 이중 기준 집단으로 나누었다. 분석의 결과는 부부간의 상호 소통과 친밀성은 결혼 만족에 영향을 미치나, 성적 만족은 결혼 만족과 관계가 없음을 보여 주고 있다. 그리고 결혼 만족과 결혼 안정은 매우 높은 관계를 보이고 있는데, 성에 대한 이중 기준이 결혼 만족과 결혼 안정의 관계 수준을 약화시키는 것으로 나타났다.

• 한국인터넷방송통신학회논문지
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• 제17권2호
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• pp.113-118
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• 2017

본 논문에서는 nonconstant modulus 신호에서 기존 MMA 알고리즘의 수렴 속도를 개선하고 SE-MMA 알고리즘의 높은 MSE를 줄일 수 있는 NM-MMA (Novel Mixed-Multi Modulus Algorithm) 알고리즘을 제안하며, 이의 등화 성능을 해석하였다. NM-MMA에서는 비용 함수로서 기존 MMA와 SE-MMA 비용 함수의 gradient vector 를 적절한 가중치의 합으로 구성하여 탭 계수 갱신에 이용하므로서 수렴 속도와 MSE 성능을 개선할 수 있다. 이를 위하여 동일한 채널과 스텝 크기 및 신호대 잡음비를 적용하여 컴퓨터 시뮬레이션을 수행하였으며 성능 해석을 위한 지수로는 등화기 출력 성상도, 잔류 isi, MSE와 SER을 적용하였다. 컴퓨터 시뮬레이션의 결과 제안 NM-MMA는 기존 MMA의 수렴 속도를 개선하고, SE-MMA보다 적은 MSE 성능과 SER 성능을 얻을 수 있음을 확인하였다.