• 전기전자학회논문지
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• 제11권4호
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• pp.205-212
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• 2007

유비쿼터스 센서 네트워크(Ubiquitous Sensor Network)는 무선통신 기능을 가진 소형 센서들로 구성된 네트워크이다. 무선통신은 유선통신에 비해 데이터의 도청과 위조, 변조가 용이하다. 그러므로 센서 네트워크를 통해 전달되는 정보들의 신뢰성을 위한 보안 연구가 수행되어야 한다. 하지만 센서네트워크에 보안을 적용하기 위해서는 추가되는 에너지소모가 발생한다. 에너지 교체가 어려운 센서네트워크에서 추가적인 에너지소모는 중요한 문제이다. 본 논문은 센서네트워크에서 획득한 데이터를 안전하게 처리할 수 있는 에너지 효율적 클러스터 기반 라우팅을 제안한다. 제안방식은 초기에 형성된 클러스터는 고정시키고 클러스터 헤드노드만 교체하는 방식으로 최초에 생성 및 교환된 클러스터 키와 노드간 키가 다시 생성 및 교환되지 않게 하는 사전배포방식을 사용할 수 있다. 제안된 방법이 기존의 클러스터 기반 라우팅에 보안을 적용한 것보다 에너지 소모가 29.2% 적게 소모됨을 모의실험을 통하여 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3576-3582
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• 2014

Zeolite-templated carbons (ZTCs), which have high specific surface area, were prepared by a conventional templating method using microporous zeolite-Y for catalyst supports in direct methanol fuel cells. The ZTCs were synthesized at different temperatures to investigate the characteristics of the surface produced and their electrochemical properties. Thereafter, Pt-Ru was deposited at different carbonization temperatures by a chemical reduction method. The crystalline and structural features were investigated using X-ray diffraction and scanning electron microscopy. The textural properties of the ZTCs were investigated by analyzing $N_2$/77 K adsorption isotherms using the Brunauer-Emmett-Teller equation, while the micro- and meso-pore size distributions were analyzed using the Barrett-Joyner-Halenda and Harvarth-Kawazoe methods, respectively. The surface morphology was characterized using transmission electron microscopy and inductively coupled plasma-mass spectrometry. The electrochemical properties of the Pt-Ru/ZTCs catalysts were also analyzed by cyclic voltammetry measurements. From the results, the ZTCs carbonized at $900^{\circ}C$ show the highest specific surface areas. In addition, ZTC900-PR led to uniform dispersion of Pt-Ru on the ZTCs, which enhanced the electro-catalytic activity of the Pt-Ru catalysts. The particle size of ZTC900-PR catalyst is about 3.4 nm, also peak current density from the CV plot is $12.5mA/cm^2$. Therefore, electro-catalytic activity of the ZTC900-PR catalyst is higher than those of ZTC1000-PR catalyst.

• Asian Pacific Journal of Cancer Prevention
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• 제16권4호
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• pp.1539-1543
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• 2015

Background: Uroplakins have been widely investigated as potential markers in patients with bladder cancer because these proteins are specific to the urothelium. However, the role of uroplakin proteins in bladder cancer remains unknown. In this study, preoperative serum levels of uroplakin III were measured in patients with urothelial carcinoma of the urinary bladder and examined for possible association with clinicopathological features and clinical outcomes. Materials and Methods: This study included 52 bladder cancer patients at various stages and 28 healthy controls. Uroplakin III levels were detected in preoperative sera using an automated dot blot system and a micro-dot blot array. Results: There was a significant increase in serum uroplakin III levels in patients with bladder cancer as compared to healthy controls (p<0.05). In addition, serum uroplakin III levels were associated with muscle-invasive status, high grade and lymphovascular invasion (p<0.02). Log-rank tests indicated high serum uroplakin III to be significantly associated with cancer-specific mortality. Conclusions: Determination of serum uroplakin III level could be valuable for identifying patients with biologically aggressive bladder cancer.

• 한국산학기술학회논문지
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• 제6권2호
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• pp.165-171
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• 2005

초음파 모터는 전자기식 모터들과는 달리 다양한 특징과 뛰어난 성능을 가진 새로운 형태의 모터이다. 그러나, 초음파 모터는 특히 구동시간에 따라 시스템의 비선형적인 특성과 파라미터의 변화들에 대한 문제를 갖는다. 그러므로 기존의 PID제어기를 사용함으로써 만족스러운 제어기의 성능을 내기가 어렵다. 본 논문에서는 원환형 초음파 모터와 선형 초음파 모터의 정밀 제어를 하기 위해 구동시간에 따른 응답 시간과 변화 등의 특성을 각각 분석하고, 리니어 초음파 모터에 대해서는 ${\mu}m$정도의 오차를 갖는 스텝 제어기와 PD제어기를 결합한 제어기를 제안한다. 제안된 제어기의 성능은 제어를 하지 않고 구동 시에 측정된 슬립 오차와 제안된 제어기를 사용하여 구동 시 측정된 슬립 오차를 비교하여 평가하였다. 실험 결과 스텝 제어기를 사용한 리니어 초음파 모터의 슬립오차는 $10{\mu}m$이하로 우수한 성능을 입증하였다.

• Composites Research
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• 제16권3호
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• pp.58-67
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• 2003

본 연구에서는 구조의 건전성을 실시간으로 모니터링하기 위해 변형률 및 파손을 동시에 감지할 수 있는 두 가지 형태의 광섬유 센서 시스템을 제안하였다. 구성된 광섬유 센서 시스템은 파손신호 취득에 사용되는 단파장 광원의 형태에 따라 EDFA에 FBG 사용한 것과 Fabry-Perot 필터를 사용한 것으로 나뉘며 EFPI센서를 통해 복합재 시편의 인장실험을 모니터링 하는데 적용되었다. 먼저, 복합재의 초기파손모드에 해당하는 모재균열 신호의 특징을 알기 위해 압전세라믹 센서를 이용하여 시편의 두께와 폭의 변화에 따른 신호특성을 파악하였다. 정량적 파손신호의 특성 분석을 위해 STFT와 Wavelet Transform과 같은 시간 주파수 변환방법을 사용하였으며, 시편의 형상변화에 따라 모재균열 신호의 주파수영역 특성이 변화함을 확인하였다 광섬유 센서로 취득 된 파손신호 및 변형률 측정값을 각각 압전세라믹 센서와 변형률게이지의 결과 값과 서로 비교하였다. 광섬유 센서 시스템들을 이용한 장시간동안의 인장실험 결과 변형률의 값은 변형률게이지의 측정값과 잘 일치하였으며 파손감지 시스템 또한 미세한 파손신호까지 민감하게 감지해 낼 수 있음을 알 수 있었다.

• 노동경제논집
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• 제29권2호
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• pp.117-143
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• 2006

본 논문은 1963년부터 2003년까지의 40년간의 국내의 금속, 화학, 금융, 자동차 운수부문(sector)의 조합원 수가 시기별로 어떤 증가나 감소 패턴을 보이는가를 규명한다. 또한 이 4개 부문에 속한 산업(industry)인 금속부문의 자동차 조립, 자동차 부품, 조선산업, 화학부문의 시멘트, 석유정제, 제약산업, 금융부문의 민간은행업, 그리고 자동차 운수부문의 시내버스업에서 노조 조직률을 추정하여 산업별로 상대적 노조규모의 차이를 보여준다. 이러한 노조규모의 절대적인 혹은 상대적인 규모의 시기별 변화나 산업별 차이가 각 부문이나 산업이 처한 경제적 환경(성장 단계나 경로)과 제도적 환경(정부개입의 유형이나 정도) 및 사회적 환경(근로자들의 학력, 성별, 연령 혹은 회사의 규모 등의 산업구조)에 영향을 받는 사용자들이나 노조의 태도나 선택에 의해 설명된다. 부문이나 산업수준의 다양성을 고려한 본 논문의 미시적인 사회 경제적 이론들은 선진국의 국제비교 노사관계의 최근 연구들에서 나타나는 미시적인 연구의 필요성의 증가와 맥을 같이한다.

• 한국가시화정보학회지
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• 제13권1호
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• pp.43-48
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• 2015

Collective cell migration is a fundamental phenomenon observed in various biological processes such as development, wound healing, and cancer metastasis. During the collective migration, cells undergo changes in their phenotypes from those of stable to the migratory state via the process called epithelial-mesenchymal transition (EMT). Recent findings in biology and biochemistry have shown that EMT is closely related to the cancer invasion or metastasis, but not much of the correlations in kinematics and physical forces between the neighboring cells are known yet. In this study, we aim to understand the cell migration and stress distribution within the expanding cell cluster. We constructed the in vitro cell cluster on the hydrogel, employed traction force microscopy (TFM) and monolayer stress microscopy (MSM) to visualize the physical forces within the expanding cell monolayer. During the expansion, cells at the cluster edge exhibited enhanced motility and developed focal adhesions that are the essential features of EMT while cells at the core of the cluster maintained the epithelial characteristics. In the aspect of mechanical stress, the cluster edge had the highest traction force of ~90 Pa directed toward the cluster core, which means that cells at the edge actively pull the substrate to make the cluster expansion. The cluster core of the tightly confined cells by neighboring cells had a lower traction force value (~60 Pa) but the highest intercellular normal stress of ~800 Pa because of the accumulation of traction from the edge of the monolayer.

• 대기
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• 제18권2호
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• pp.97-109
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• 2008

The aerosol characteristics in terms of 4 different cases (Asian dust, fog, clear sky and cloud) which had happened at Anmyeon Island in April 2006 were studied using various measurements such as the Micro Pulse Lidar (MPL), sunphotometer, $\beta$-ray $PM_{10}$ Analyzer, anemoscope and anemometer. In addition, synoptic charts, back trajectory analyses and satellite images were also used to help characterize the aerosol events. The aerosol optical properties were featured by the Aerosol Optical Depth (AOD) and ${\AA}ngstr\ddot{o}m$ exponent which were estimated by the sunphotometer. When Anmyeon Island was dominated by the Asian dust, the AOD was sharply increased as seven times as a yearly average of it (0.35). As compared with a yearly average of the ${\AA}ngstr\ddot{o}m$ exponent of 0.97, the ${\AA}ngstr\ddot{o}m$ exponent of a dust day was significantly low (0.099). In addition, $PM_{10}$ mass concentration showed an extremely high record. The maximum concentration reached $1790.5{\mu}gm^{-3}$ on 8 April 2006. The maximum mass concentration was shown with delay when the wind speed of $0ms^{-1}$ was observed. It was also found that a satellite image of the MODIS-RGB had a good agreement with the results of those measurements. It was shown that the MPL was able to describe effectively the vertical distribution of aerosol for all the cases. In particular, the MPL evidently captured the aerosol layer before the cloud observation. The aerosol layer was similarly described by the AOD. On a clear sky day, the AOD had not only a very low value (0.054) but also a feature of homogeneity.

• KIEAE Journal
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• 제14권3호
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• pp.105-109
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• 2014

The recent rising living standards, environment-friendly, well-being and health aspects of life in the basic gratification, as well as the desire for a pleasant environment emotionally environmentally friendly way of external space or industrial interest in the indoor environment, the manifestation. In particular, the biggest problem of the indoor environment has been emerged as a Sick House Syndrome indoor space that is provided to the building materials, and the impact on the domestic and the indoor environment, and clean the house in a health standards are specified as laws. The performance rating and the various materials to create environmentally-friendly standards for building materials. The more detail, Porous clay material, toxic substances released by applying the high humidity and the water itself, and to absorb the moisture, if the emissions, without a separate device, to maintain a comfortable indoor environment and at the same time, one of the causes of Sick House Syndrome breaking down harmful substances to absorb a comfortable indoor environment to maintain an environmentally-friendly building interior material studies. It is aimed at the development to multi-functional high performance eco-friendly construction materials, rather than through one feature performance, identify key features for national and international eco-friendly building materials can exert Water Vapour Adsorption raw, decomposed materials for the application and selection.

• Smart Structures and Systems
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• 제16권3호
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• pp.383-399
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• 2015

Today, as railways increase their capacity and speeds, it is more important than ever to be completely aware of the state of vehicles fleet's condition to ensure the highest quality and safety standards, as well as being able to maintain the costs as low as possible. Operation of a modern, dynamic and efficient railway demands a real time, accurate and reliable evaluation of the infrastructure assets, including signal networks and diagnostic systems able to acquire functional parameters. In the conventional system, measurement data are reliably collected using coaxial wires for communication between sensors and the repository. As sensors grow in size, the cost of the monitoring system can grow. Recently, auto-powered wireless sensor has been considered as an alternative tool for economical and accurate realization of structural health monitoring system, being provided by the following essential features: on-board micro-processor, sensing capability, wireless communication, auto-powered battery, and low cost. In this work, an original harvester device is designed to supply wireless sensor system battery using train bogie energy. Piezoelectric materials have in here considered due to their established ability to directly convert applied strain energy into usable electric energy and their relatively simple modelling into an integrated system. The mechanical and electrical properties of the system are studied according to the project specifications. The numerical formulation is implemented with in-house code using commercial software tool and then experimentally validated through a proof of concept setup using an excitation signal by a real application scenario.