• Smart Structures and Systems
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• 제19권3호
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• pp.269-277
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• 2017

Recently, there has been significant interest in structural health monitoring for civil engineering applications. In this research, a specially designed tendon, proposed by embedding FBG sensors into the center king cable of a 7-wire strand tendon, was applied for long-term health monitoring of tensile forces on a ground anchor. To make temperature independent sensors, the effective temperature compensation of FBG sensors must be considered. The temperature sensitivity coefficient ${\beta}^{\prime}$ of the FBG sensors embedded tendon was successfully determined to be $2.0{\times}10^{-5}^{\circ}C^{-1}$ through calibrated tests in both a model rock body and a laboratory heat chamber. Furthermore, the obtained result for ${\beta}^{\prime}$ was formally verified through the ground temperature measurement test, expectedly. As a result, the ground temperature measured by a thermometer showed good agreement compared to that measured by the proposed FBG sensor, which was calibrated considering to the temperature sensitivity coefficient ${\beta}^{\prime}$. Finally, four prototype ground anchors including two tension ground anchors and two compression ground anchors made by replacing a tendon with the proposed smart tendon were installed into an actual slope at the Yeosu site. Tensile forces, after temperature compensation was taken into account using the verified temperature sensitivity coefficient ${\beta}^{\prime}$ and ground temperature obtained from the Korean Meteorological Administration (KMA) have been monitored for over one year, and the results were very consistent to those measured from the load cell, interestingly.

• 한국전자통신학회논문지
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• 제8권10호
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• pp.1485-1490
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• 2013

스마트 그리드용 전력망이 구축시범사업이 진행됨에 따라 스마트 디지털가전 AV기술, 냉난방 습도 공기 자동관리를 위한 복합에너지 관리기능을 담당하는 스마트 홈 에너지관리기술, 노약자와 장애인을 위한 주거설계와 가족 구성원에 대한 개인별 바이오정보 측정을 담당하게 될 헬스케어 기술, 생체인식 보안과 동작감지센서 등을 다루는 스마트 홈 시큐리티 기술 등 연구가 진행되고 있다. 본 논문에서는 물리적 공격에 취약한 외부에 노출되는 문제점이 발생하게 되는 스마트미터기에 대응되는 암호기술을 분석하고 단말기의 효율성을 극대화 할수 있는 스마트 미터기 단말기용 보안시스템 설계를 제안하였다.

• Smart Structures and Systems
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• 제8권5호
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• pp.501-524
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• 2011

Recent studies have discovered that a conventional passive isolation system may suffer from an excessive isolator displacement when subjected to a near-fault earthquake that usually has a long-period velocity pulse waveform. Semi-active isolation using variable friction dampers (VFD), which requires a suitable control law, may provide a solution to this problem. To control the VFD in a semi-active isolation system more efficiently, this paper investigates experimentally the possible use of a control law whose control logic is similar to that of the anti-lock braking systems (ABS) widely used in the automobile industry. This ABS-type controller has the advantages of being simple and easily implemented, because it only requires the measurement of the isolation-layer velocity and does not require system modeling for gain design. Most importantly, it does not interfere with the isolation period, which usually decides the isolation efficiency. In order to verify its feasibility and effectiveness, the ABS-type controller was implemented on a variable-friction isolation system whose slip force is regulated by an embedded piezoelectric actuator, and a seismic simulation test was conducted for this isolation system. The experimental results demonstrate that, as compared to a passive isolation system with various levels of added damping, the semi-active isolation system using the ABS-type controller has the better overall performance when both the far-field and the near-fault earthquakes with different PGA levels are considered.

• 열처리공학회지
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• 제9권2호
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• pp.121-129
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• 1996

The solubility of Ti in Al matrix was determined by X-ray diffraction method on two different mechanical alloying systems, i.e Al+$Al_3Ti$ and Al+Ti alloys. Starting powder compositions of two systems were chosen for final volume fraction of $Al_3Ti$ phase being 25%. The solubility of Ti in ${\alpha}$-Al was estimated by the lattice parameter measurement of Al. For Al+$Al_3Ti$ mixture, it appeared that some of $Al_3Ti$ particles decomposed during milling and maximum solubility of Ti in Al was about 0.99%. The majority of $Al_3Ti$ particles were dispersed uniformly in Al matrix, having approximate size of 100~200 nm. On the other hand, higher Ti solubility of 1.24 wt.% was found in Al+Ti system, with starting composition of Al+10 wt.%Ti. After 15 hours of milling, Ti phase was identified as 20 nm sized particles embedded in Al matrix. The annealing of mechanically alloyed powders from Al+$Al_3Ti$ and Al+10 wt.%Ti systems was followed in the temperature range of 200 to $600^{\circ}C$ to study thermal stability of supersaturated solution of Al(Ti). After annealing, the lattice parameter of Al reverted back to that of pure Al, and the peak intensity ratio of $Al_3Ti$/Al was increased more than the original value before annealing. These results suggest that Ti dissolve into alpha-Al solutions during milling, and by annealing, $Do_{22}-Al_3Ti$ phase forms from Al(Ti) solution.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.439-442
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• 2003

본 연구에서는 생체인식(Biometric)을 이용하여 Access Control System을 구현하였다. Biometric 는 생체 인식 또는 생체 측정학으로 사람의 생체적, 행동적 특성을 이용하여 개인을 식별하는 학문 또는 기술이다. Access Control System은 개인을 식별 출입과 근태, 개인 관리, 보안 둥에 사용하는 System으로 Biometric System과 접목으로 편리성과 보안성에서 탁월한 효과를 발휘할 수 있다. 본 연구에서 제안한 시스템은 기존의 RF Card System에 Wiegand(Data format) Signal 출력으로 기존 RF Card Reader대신 Access Control (Security) System을 구성할 수 있도록 설계되었고 컴퓨터와 RS-232, RS-422 또는 Tcp/Ip로 구성되어 Software상에서 임베이디드 System을 Control 할 수 있게 되어 있다.

• Journal of Computational Design and Engineering
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• 제3권1호
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• pp.53-62
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• 2016

The current trends of product customization and repair of high value parts with individual defects demand automation and a high degree of flexibility of the involved manufacturing process chains. To determine the corresponding requirements this paper gives an overview of manufacturing process chains by distinguishing between horizontal and vertical process chains. The established way of modeling and programming processes with CAx systems and existing approaches is shown. Furthermore, the different types of possible adaptions of a manufacturing process chain are shown and considered as a cascaded control loop. Following this it is discussed which key requirements of repair process chains are unresolved by existing approaches. To overcome the deficits this paper introduces repair features which comprise the idea of geometric features and defines analytical auxiliary geometries based on the measurement input data. This meets challenges normally caused by working directly on reconstructed geometries in the form of triangulated surfaces which are prone to artifacts. Embedded into function blocks, this allows the use of traditional approaches for manufacturing process chains to be applied to adaptive repair process chains.

• 한국생산제조학회지
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• 제24권5호
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• pp.561-567
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• 2015

For a long time, therapeutic dolls have been provided to elderly patients with dementia as a non-drug therapy in several western countries. These dolls are made to resemble newborn babies. Touching the dolls and singing lullabies remind the elderly of taking care of their babies. These actions are effective in decreasing anxiety and reducing aggression, particularly, in the elderly with dementia. These dolls also help them to adapt to new places such as nursing facilities. This work proposes the installation of advanced systems in therapeutic dolls to aid the medical treatment of dementia patients by stabilizing their physical and mental health.

• 한국인터넷방송통신학회논문지
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• 제16권5호
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• pp.191-196
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• 2016

최근에 이르러, 임베디드 시스템 및 모바일 장치 뿐만이 아니라 고성능 마이크로프로세서 및 멀티코어프로세서의 전력 소비량이 매우 중요하게 대두되고 있다. 특히, 스마트폰과 태블릿 PC의 광범위한 사용으로 인하여 프로세서의 저전력 소비가 무엇보다 요구된다. 본 논문에서는 고성능 마이크로프로세서에 대하여 빠른 속도를 갖는 명령어 자취형 (trace-driven) 모의실험기 기반의 전력 측정기를 개발하였다. 본 전력 측정기는 마이크로프로세서를 구성하는 복합 조합회로, 배열구조, CAM 구조를 기반으로 하였으며, SPEC 2000 벤치마크를 입력으로 모의실험을 수행하여 각 벤치마크의 평균 전력 소비량을 측정하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권4호
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• pp.1555-1570
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• 2016

For monitoring forest fires, a real-time system to prevent fires in wider areas should be supported consistently. However, there has still been a lack of the support for real-time system related to forest fire monitoring. In addition, the 'real-time' processing in a forest fire detection system can lead to excessive consumption of energy. To solve these problems, the intelligent data acquisition of sensing nodes is required, and the maximum energy savings as well as rapid and accurate detection by flame sensors need to be done. In this regard, this paper proposes a node built-in filter algorithm for intelligent data collection of sensing nodes for the rapid detection of forest fires with focus on reducing the power consumption of the remote sensing nodes and providing efficient wireless sensor network-based forest environment monitoring in terms of data transmission, network stability and data acquisition. The experimental result showed that battery life can be extended through the intelligent sampling of remote sensing nodes, and the average accuracy of the measurement of flame detection based on the distance is 44%.

• 농업과학연구
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• 제40권1호
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• pp.53-59
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• 2013

Analysis of load data during field operations is highly important for optimum design of power drive lines for agricultural tractor. Objective of the paper was to analyze field load data using FFT to determine frequency and the energy levels of meaningful cyclic patterns. Rotary tillage, plowing, baling, and wrapping operations were selected as major field operations of agricultural tractor. An agricultural tractor with power measurement system was used. The tractor was equipped with strain-gauge sensors to measure torque of four driving axles and a PTO axle, speed sensors to measure rotational speed of the driving axles and an engine shaft, pressure sensors to measure pressure of hydraulic pumps, an I/O interface to acquire the sensor signals, and an embedded system to calculate power requirement. In rotary tillage, calculated frequency was decreased as travel speed increased. In baler operation, calculated frequency was increased as PTO speed was increased. The calculated peak frequency levels and expected levels were similar. Results of the study would provide information on power utilization patterns and on better design of power drive lines.