• 한국재료학회지
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• 제20권11호
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• pp.611-616
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• 2010

A cobalt oxide - tin oxide nanocomposite based gas sensor on an $SiO_2$ substrate was fabricated. Granular thin film of tin oxide was formed by a rheotaxial growth and thermal oxidation method using dc magnetron sputtering of Sn. Nano particles of cobalt oxide were spin-coated on the tin oxide. The cobalt oxide nanoparticles were synthesized by polymer-assisted deposition method, which is a simple cost-effective versatile synthesis method for various metal oxides. The thickness of the film can be controlled over a wide range of thicknesses. The composite structures thus formed were characterized in terms of morphology and gas sensing properties for reduction gas of $H_2$. The composites showed a highest response of 240% at $250^{\circ}C$ upon exposure to 4% $H_2$. This response is higher than those observed in pure $SnO_2$ (90%) and $Co_3O_4$ (70%) thin films. The improved response with the composite structure may be related to the additional formation of electrically active defects at the interfaces. The composite sensor shows a very fast response and good reproducibility.

• 한국항행학회논문지
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• 제20권3호
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• pp.182-189
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• 2016

본 논문에서는 해양관측을 위한 멀티 홉 릴레이 네트워크 기반의 부이 시스템을 제안한다. 제안된 시스템은 다양한 센서 모듈과 게이트웨이, 무선 통신부, 원격 모니터링부로 구성된다. 센서 모듈은 다양한 통신 인터페이스와 통합되고 CAN 버스 기반의 단일화된 프로토콜을 통하여 제안하는 부이 시스템의 게이트웨이와 연결된다. 제안한 시스템은 원격 모니터링 사이트와 무선으로 데이터를 주고 받으며 통신 커버리지를 더욱 확대하기 위하여 LTE 통신 및 XBee 메쉬 네트워크 모듈을 사용한다. 필드 테스트를 통하여 제안하는 다중 홉 릴레이 네트워크 기반의 부이 시스템이 다중 홉을 이용하여 부이의 통신 도달 거리를 더욱 확장할 수 있음을 확인할 수 있다.

• 정보처리학회논문지B
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• 제15B권3호
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• pp.219-228
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• 2008

실시간 소셜(Social) 네트워킹 서비스를 위해서, 사용 가능한-통합적-유비쿼터스 (U3) 웹 서비스에서의 모바일 상호작용을 연구하였다. 실시간 소셜 네트워크를 위한 편리한 모바일 HCI로서, 또한 유비쿼터스 웹 서비스에서의 메타데이터 정보 색인 키로서, 다국어 한 글자 도메인 명(예, 김.net, 이.net, 가.net, ㄱ.net, ㄴ.net, ㅎ.net, ㅏ.net, ㅔ.net, ㄱ.com, ㅎ.com) 은 소셜 정보를 검색하고 또한 등록할 때 편리한 모바일 인터페이스이다. U3 웹 서비스의 예로서, 실시간 소셜 네트워킹 서비스 구현과 함께 모바일 상호작용을 위해 스케치된 디자인 목표와 한국, 일본, 중국에서의 모바일 상호작용 경험을 소개한다. 또한, 소셜 네트워킹과 센서 네트워킹 서비스에서 통합 정보관리를 위해, IP 기반의 센서네트워크 (IP-USN)에서 메타데이터 디렉터리 서비스에의 응용 확장 가능성도 소개한다.

• 산업공학
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• 제23권3호
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• pp.229-238
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• 2010

Virtual metrology (VM), a critical component of semiconductor manufacturing, is an efficient way of assessing the quality of wafers not actually measured. This is done based on a model between equipment sensor data (obtained for all wafers) and the quality characteristics of wafers actually measured. This paper considers principal component regression (PCR), partial least squares regression (PLSR), kernel PCR (KPCR), and kernel PLSR (KPLSR) as VM models. For each regression model, two cases are considered. One utilizes all explanatory variables in developing a model, and the other selects significant variables using the genetic algorithm (GA). The prediction performances of 8 regression models are compared for the short- and long-term etch process data. It is found among others that the GA-KPLSR model performs best for both types of data. Especially, its prediction ability is within the requirement for the short-term data implying that it can be used to implement VM for real etch processes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.97-101
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• 2000

The AE measurement is one of the most convenient methods for detecting contacts between slider disk. The AE method has been widely used in the investigation of the tribology of sliding interfaces due to the convenience of using AE sensor. In this study, we examined the relationship between the AE signal and the flying height of a slider. We tried to know the influence of the disk velocity on the AE rms signal by using the AE measurement system. The experiment also gives the relationship between the take-off velocity and the disk surface state. To investigate the behavior of the slider further, the variances of the AE signal are analyzed. The results about a subambient pressure slider indicate that the increase in the magnitude of AE rms signal does not necessarily mean the slider/disk contacts.

• International Journal of Contents
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• 제8권3호
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• pp.20-25
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• 2012

Working in a hazardous environment can decrease work efficiency and cause a variety of occupational diseases. To prevent occupational accidents and build a refreshing and pleasant work environment, therefore, it is necessary to develop an application system through which a worker's safety can be monitored on a realtime basis and provide related services. Recently, smartphones have become very popular across the nation, with over 10 million users. As a result, a variety of application services have been developed and provided in diverse sectors. This study proposes a system structure to develop application services which monitor work environment using smartphones and examines its applicability through the implementation of server and client interfaces.

• 한국소음진동공학회논문집
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• 제15권4호
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• pp.395-403
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• 2005

The dynamic characteristics of delaminated smart composite laminates are studied using animproved layerwise laminate theory. The theory is capable of capturing interlaminar shear stresses that are critical to delamination. The presence of discrete delamination is modeled through the use of Heaviside unit step functions. Stress free boundary conditions are enforced at all free surfaces. Continuity in displacement field and transverse shear stresses are enforced at each ply level. In modeling piezoelectric composite plates, a coupled piezoelectric-mechanical formulation is used in the development of the constitutive equations. Numerical analysis is conducted to investigate the effect of nonlinearity in the transient vibration of bimodular behavior caused by the contact impact of delaminated interfaces. Composite plates with delamination, subject to external loads and voltage history from surface bonded sensors, are investigated and the results are compared with corresponding experimental results and plates without delamination.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.379-380
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• 2006

As a result of growth sensor-enabled mobile devices such as PDA, cellular phone and other computing devices, in recent years, users can utilize the diverse digital contents everywhere and anytime. However, the interfaces of mobile applications are often unnatural due to limited resources and miniaturized input/output. Especially, users may feel this problem in some applications such as the mobile game. Therefore, Novel interaction forms have been developed in order to complement the poor user interface of the mobile device and to increase the interest for the mobile game. In this paper, we describe the demonstration of the gesture and posture input supported by an accelerometer. The application example we created are AM-Fishing game on the mobile device that employs the accelerometer as the main interaction modality. The demos show the usability for the gesture and posture interaction.

• 로봇학회논문지
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• 제11권2호
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• pp.108-114
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• 2016

This paper presents a sensor-based cane mechanism for walking aid of the visually impaired person. We also describe an approach to decide properly the length of the specified cane mechanism. The cane mechanism has some sensors to identify the possibility of a collision between the cane user and an object and/or a person, and a signal processing unit that enables the user to recognize such a collision is attached in the mechanism. Thus, the walker using this cane can recognize in advance the possibility of such a collision in his walking process. Consequently, it is helpful for the visually impaired person to walk on a pedestrian road safely. The feature of the proposed cane mechanism and its availability have been shown through experimental works in a typical walking environment.

• 실천공학교육논문지
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• 제8권2호
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• pp.111-120
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• 2016

여러 가지 센서를 이용한 IOT(Internet Of Thing) 시스템의 FPGA 설계용 교육장비를 소개한다. 센서들은 다양한 출력 방식을 가지고 있어서 출력 방식에 따른 센서 인터페이스 컨트롤러를 FPGA 상에서 설계가 필요하다. 본 장비는 아날로그 출력인 경우에 FPGA(Field Programmable Gate Array)내에 있는 ADC(Analog-to-Digital Converter) 방식과 디지털 출력인 경우에 $I^2C$(Inter-Integrated Circuit), SPI(Serial Peripheral Interface Bus) 통신방식 및 GPIO(General-Purpose Input/Output)를 통해 사용한 방식에 따른 여러 가지 센서 인터페이스 컨트롤러의 설계가 가능하다. 이미지 센서를 이용해서 영상 처리 하드웨어 설계가 가능하고 더불어 영상 및 영상처리 결과를 모니터에 출력하는 VGA(Video Graphics Array) 컨트롤러 설계도 가능하다. 본 장비는 유,무선 네트워크에 통신이 가능한 IOT 시스템을 위해서 한 칩에 디지털 하드웨어와 Linux System을 결합한SOC(System on Chip) 설계가 가능하다. 이 장비를 이용해서 "이미지센서 기반의 하드웨어 설계와 가속도센서 기반의 하드웨어 설계"의 사례를 소개하고 그 설계를 기반으로 "FPGA를 이용한 디지털시스템 설계" 교과목의 교육 가능한 사례를 소개한다. 학생들에 의해서 새롭게 설계한 하드웨어를 본 FPGA를 이용해서 하드웨어 장비에 적용시키는 능력을 배양할 수 있고, 또한 개념설계, 부분설계, 상세설계를 통해서 FPGA 기반 하드웨어의 창의적 종합설계 능력을 키울 수 있다.