• Steel and Composite Structures
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• 제47권1호
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• pp.1-17
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• 2023

This paper deals with the free vibration behavior of rotating composite beams reinforced with carbon nanotubes (CNTs) under uniform thermal loads. The temperature-dependent beam material is assumed to be a mixture of single-walled carbon nanotubes (SWCNTs) in an isotropic matrix and five different functionally graded (FG) distributions of CNTs are considered according to the variation along the thickness, namely the UD-uniform, FG-O, FG-V, FG-Λ and FG-X distributions where FG-V and FG-Λ are unsymmetrical patterns. Considering the Timoshenko beam theory (TBT), a new finite element formulation of functionally graded carbon nanotube reinforced composite (FGCNTRC) beam is created for the first time. And the effects of several essential parameters including rotational speed, hub radius, effective material properties, slenderness ratio, boundary conditions, thermal force and moments due to temperature variation are considered in the formulation. By implementing different boundary conditions, some new results of both symmetric and non-symmetrical distribution patterns are presented in tables and figures to be used as benchmark for further validation. In addition, as an alternative advanced composite application for rotating systems exposed to thermal load, the positive effects of CNT addition in improving the dynamic performance of the system have been observed and the results are presented in several tables and figures.

• Elastomers and Composites
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• 제37권4호
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• pp.234-243
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• 2002

A general scheme of a rubber structure is proposed. Using the thermomechanical method(TMA), some changes in the molecular and topological structures for uncured and cured, and unfilled and filled rubbers during processing are shown. In our investigations as region it is understood a complex structure, which is expressed at the thermomechanical curve(TMC) as a zone differed from others in thermal expansion properties. This zone is between the noticed temperatures of relaxation transitions, usually on the level like those determined by DMTA at 1Hz. These regions, which shares, are not stable, and differ in molecular-weight distribution(MWD) of chain fragments between the junctions. Differences in dynamics of the formation of the molecular and topological structures of a vulcanizate are dependent on the rubber formulation, mixing technology and curing time. Some of characteristics of these regions correlate with mechanical properties of vulcanizates what is shown for NR rubbers containing ENR or CPE as a polymeric additive. It is well known that the state of order influences diffusivity of low-molecular substances into the polymer matrix. Because of this, the two topological amorphous regions should influence the distribution of the ingredients and resulting in rubber compounds' heterogeneity, and related properties of cured rubber. Investigation of this problem is expected to be, in the future, one of the essential factors in determining further improvement of polymeric materials properties by compounding with additives and in reprocessing of rubber scrap.

• 융합경영연구
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• 제4권2호
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• pp.1-19
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• 2016

The purpose of this study was to examine the issues involved in offering superior customer experience on fashion retail stores in Brazil. The approach used to access CEM (Customer Experience Management) issues was a special questionnaire with 23 questions, through a research with managers of three important brazilian fashion retail chains (focused on class A clients). Some statistical techniques were used for data processing. It was possible to analyze the aspects that impact on the customer experience and their relevance. it was possible to realize that CEM is effective in increasing productivity and, so, it can be used as a guideline matrix management in decision making to promote superior customer experiences. The classical management is usually conservative and avoids to deal with strategies that do not necessarily involve numbers. Dealing with intangible and so subtle experience is unusual and a huge challenge, but sometimes it is necessary to look beyond the obvious and accessible statistics. If CEM is a strategy to focus on operations and processes of a business around the customers experiences with the company, it is essential to structure it and find out its effectiveness.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.494-496
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• 2013

Cost-Benefit Analysis (CBA) is a systematic optimization process that allows users to compare different alternatives and to determine if a project is a solid investment. Many state DOTs have included CBA in their pavement management systems (PMSs) to help allocate state funds for maintenance, rehabilitation, resurfacing, and reconstruction of pavements. In a typical CBA, each pavement type has an assigned weight factor which represents the level of importance of this pavement type. To conduct an accurate CBA, it is essential to select appropriate weight factors. Arbitrarily assigning weights factors to pavements can lead to biased and inaccurate funding allocation decisions. The purpose for this paper is to outline a method to develop an ideal set of weight factors that can be utilized to conduct more accurate CBA. To this end, a matrix of all possible weight factors sets was developed. CBA was conducted for each set of weight factors to obtain a population of possible optimization solutions. Then a regression analysis was performed to establish the relationship between benefit and weight factors. Finally, a multi-objective genetic algorithm was applied to select the optimal set of weight factors. The findings from this study can be used by state DOTs to strategically manage their roadway systems in a cost effective manner.

• 마이크로전자및패키징학회지
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• 제31권2호
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• pp.45-53
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• 2024

The maintenance of semiconductor equipment is crucial for the continuous growth of the semiconductor market. System management is imperative given the anticipated increase in the capacity and complexity of industrial equipment. Ensuring optimal operation of manufacturing processes is essential to maintaining a steady supply of numerous parts. Particularly, monitoring the status of substrate transfer robots, which play a central role in these processes, is crucial. Diagnosing failures of their major components is vital for preventive maintenance. Fault diagnosis methods can be broadly categorized into physics-based and data-driven approaches. This study focuses on data-driven fault diagnosis methods due to the limitations of physics-based approaches. We propose a methodology for data acquisition and preprocessing for robot fault diagnosis. Data is gathered from vibration sensors, and the data preprocessing method is applied to the vibration signals. Subsequently, the dataset is trained using Gradient Tree-based XGBoost machine learning classification algorithms. The effectiveness of the proposed model is validated through performance evaluation metrics, including accuracy, F1 score, and confusion matrix. The XGBoost classifiers achieve an accuracy of approximately 92.76% and an equivalent F1 score. ROC curves indicate exceptional performance in class discrimination, with 100% discrimination for the normal class and 98% discrimination for abnormal classes.

• Tuberculosis and Respiratory Diseases
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• 제52권2호
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• pp.107-116
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• 2002

연구배경 : Matrix metalloproteinase(MMP)는 세포외 기질중 기저막의 용해 및 혈관 생성에 관여하여 전이를 일으키며, 이중 MMP-9 과 STR-3 가 폐암에서 발현된 경우 예후가 나쁘며 림프절 전이와 연관이 있다는 보고가 있다. 말초혈액에서 MMP-9와 STR-3의 발현이 폐암의 진단 표지자로 사용될 수 있는 지를 평가하고 자하였다. 방 법 : 44명의 폐암 환자, 19명의 감염성 폐질환 환자, 33명의 정상인의 혈액을 채취하여 단핵구를 분리하여 MMP-9과 STR-3의 RT-PCR을 시행하였고, 혈청내 MMP-9 단백질을 ELISA로 측정하여 비교 분석하였다. 결 과 : MMP-9은 폐암환자 (26/44, 59.1%)와 정상 대조군(23/33, 69.7%)에 비해 폐감염환자 (18/19, 94.7%)에서 유의하게 높게 발현되며(p=0.018), STR-3은 폐감염환자(8/19, 42.1%)와 정상 대조군 (20/33, 60.6%)에 비해 폐암환자(37/44, 84.1%)에서 유의하게 높게 발현되었다(p=0.003). MMP-9는 폐암 환자들 사이에서 림프절 전이가 있는 군(17/24, 70.8%)에서 없는 군 (3/13, 23.1%)보다 유의하게 높게 발현되었으며(p=0.005), 그 이외에 T 병기, 원격전이 유무, 종양의 병리소견, 연령, 성별에 따른 MMP-9과 STR-3 mRNA의 발현차이는 관찰되지 않았다. 세 군간 혈청내 MMP-9 농도의 차이는 관찰되지 않았다. 결 론 : RT-PCR을 이용한 말초혈액 단핵세포에서의 STR-3 mRNA 발현 측정은 폐암의 진단 표지자로 사용될 가능성이 있을 것으로 사료된다.

• 대한한방내과학회지
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• 제23권2호
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• pp.165-173
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• 2002

Purpose : Among numerous biological symptoms of cancer, matrix metalloproteinases (MMPs) are essential for tumor invasion and metastasis. HAD is used as an inhibitor of MMP gene. This study was designed to evaluate the effects of HAD on anti metastasis and preventing recurrence in cancer patients. Materials and Methods : We retrospectively analyzed the medical records of 69 cancer patients who had been administered with HAD for over 12 months continuously in East-West Cancer Center of Oriental Hospital of Daejeon University, from January 1993 to May 2002. Results : We analyzed gender, portion, stage and anti-metastasis & recurrence rates of cancer patients. Analysis of sex cases showed that the percentage of male is 62.3%, female is 37.7%. Analysis of cancer portion showed that the percentage of stomach is 31.9%, colorectum is 26.1%, lung is 21.7%, liver is 8.7%, breast is 8.7% Analysis of stage showed that the rate of III is 78.3%, IV is 13.0% and II is 8.7%. Analysis of anti-metastasis and recurrence rates showed that colorectal cancer is 77.8%, stomach cancer is 63.6%, lung cancer is 33.4% and breast cancer is 33.3% (mean : 53.6%). Conclusions : HAD has significant effects on anti-metastasis and preventing recurrence of tumor on cancer patients. So it helps to prolong the survival rates of cancer patients.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권4호
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• pp.271-281
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• 2004

Adenoid cystic carcinoma is malignant tumor in salivary gland, and its behavior is very invasive. Of all malignant tumor adenoid cystic carcinoma is occured in frequency of 4.4% in major salivary gland, and 1.29% in minor salivary gland. Histopathologically, adenoid cystic carcinoma is characterized by a cribriform appearance, and tubular form and solid nest type tumor can be seen. The tumor cell structure composed of modified myoepithelial cell, and basaloid cell. Extracellular matrix of this tumor cell contains variable ground substance with basement membrane component. Basement membrane matrix composed of collagen fibers, glycoproteins, proteoglycans, and its function is well known that it participate in differentiation, proliferation, and growth of tumor cell. Basement membrane molecule is essential for invasion of peripheral nerve, blood vessel, skeletal muscle in tumor cell of adenoid cystic carcinoma. In many studies, the tumor cell of adenoid cystic carcinoma containing modified myoepithelial cell participate in synthesis of proteoglycan. In this study, tissue sample of adenoid cystic carcinoma of human salivary gland were obtained from 15 surgical specimen, and all specimen were routinely fixed in 10% formalin and embedded. Serial $4-{\mu}m$ thick sections were cut from paraffin blocks. the histopathologic evaluation was done with light microscopy. And, the immunohistochemical staining, characteristics of glycosaminoglycan were observed. For biochemical analysis of glycosaminoglycan, isolation of crude glycosaminoglycan from tumor tissue and Western bolt analysis were carried out. With transmission electomicroscopy, tumor cell were observed. Biologic behavior of adenoid cystic carcinoma was observed with distribution and expression of basement membrane of glycosaminoglycan in tumor cells, The results obtained were as follows: 1. In immunohistochemical study, chondroitin sulfate is postively stained in tumor cell and interstitial space, dermatan sulfate is weakly stained in ductal cell. But keratan sulfate is negatively stained. 2. In immunohistochemical study, heparan sulfate is strong positive stained in tumor cell and basement membrane, especially in invasion area to peripheral nerve tissue. 3. In transmission electromicroscpic view, the tumor cells are composed modifed myoepithelial cells, and contains many microvilli and rough endoplasmic reticulum. 4. In Western blot analysis, the expression of glycosaminoglycan is expressed mostly in heparan sulfate. From the results obtained in this study, tumor cell of adenoid cystic carcinoma is composed modified myoepithelial cell, and glycosaminoglycan of basement membrane molecule of heparan sulfate and chondroitin sulfate mostly participate in the development and invasiveness of adenoid cystic carcinoma by immunohistochemical study and western blot analysis.

• Asian Pacific Journal of Cancer Prevention
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• 제16권2호
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• pp.443-449
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• 2015

Background: Myeloproliferative disorders (MPDs) are clonal hematologic malignancies originating at the level of the pluripotent hematopoietic stem cell. Matrix metalloproteases (MMPs) are proteolytic enzymes that contribute to all stages of malignancy progression. Genetic variants in the MMP genes may influence the biological function of these enzymes and change their role in carcinogenesis and progression. To our knowledge, this is the first investigation of associations between the -735 C/T and -1562 C/T polymorphisms in the MMP2 and MMP9 genes, respectively, and the risk of essential thrombocytosis (ET), and polycythemia vera (PV). Materials and Methods: The case-control study included JAK2V617F mutation positive 102 ET and PV patients and 111 controls. Polymorphisms were determined by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and electrophoresis. Results: No statistically significant differences were detected between patient (ET+PV) and control groups regarding genotype distribution for MMP2 gene-735 C/T and MMP9 gene -1562 C/T polymorphisms and C/T allele frequency (p>0.050). Statistically borderline significance was observed between PV and control groups regarding genotype distribution for the MMP9 gene -1562 C/T polymorphism (p=0.050, OR=2.26, 95%Cl=0.99-5.16). Conclusions: Consequently this study supported that CC genotype of MMP9 gene -1562 C/T polymorphism may be related with PV even if with borderline significance.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제34권1호
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• pp.1-15
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• 2020

첨단 정보통신기술(ICT)인 인공지능(AI), 사물인터넷(IoT), 빅데이터(Big Data) 등이 사회와 경제 전반에 융합돼 혁신적인 변화가 일어나는 요즘, 헬스케어, 지능형 로봇, 가정용 인공지능 시스템(스마트홈), 공유자동차 등은 이미 우리 생활에 깊이 영향을 미치고 있다. 이미 오래전부터 공장에서는 로봇이 사람 대신 일을 하고 있으며(FA, OA), 인공지능 의사도 병원에서 활동을 하고 있고(Dr. Watson), 인공지능 스피커(기가지니)와 인공지능 비서인 구글 어시스턴트가 자연어생성을 하며 우리를 돕고 있다. 이제 인공지능을 이해하는 것은 필수가 되었으며, 인공지능을 이해하기 위해서 수학의 지식은 선택이 아니라 필수가 되었다. 따라서 이런 일들을 가능하게 해주는 수학지식을 설명하는 역할이 수학자들에게 주어졌다. 이에 본 연구진은 인공지능과 머신러닝(Machine Learning, 기계학습)을 이해하기 위해 필요한 수학 개념을 우리의 실정에 맞게 한 학기(또는 두 학기) 분량으로 정리하여, 무료 전자교과서 "인공지능을 위한 기초수학"을 집필하고, 인공지능 분야에 관심이 있는 다양한 전공의 대학생과 대학원생을 대상으로 하는 강좌를 개설하였다. 본 논문에서는 그 개발과정과 운영사례를 공유한다. http://matrix.skku.ac.kr/math4ai/