• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.1 s.106
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• pp.12-18
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• 2006

This research investigates the electromechanical characteristics of a spindle motor in a free-falling mobile hard disk drive before unexpected shock. Electromechanical simulation includes a time-stepping finite element analysis of the magnetic field in a speed controlled brushless DC motor and dynamic analysis of the stationary and rotating part linked by the fluid dynamic bearing under the free-falling condition. Analysis results show that the dynamic characteristics of the rotating spindle system during free-falling state have an effect on the relative motion between the stationary and rotating part of HDD. It results from the variation of reaction force in the bearing area due to the gravity force exerted on the rotating part of HDD, and the free-falling condition can be detected by observing the signal of the spindle motor and disk-head interface without using an accelerometer.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.429-437
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• 1996

The purpose of this study is to correct the nodule abundance of FFG (Free Fall Grab) sampler on KODOS (Korea Deep Ocean Study) area in North-East Pacific Ocean. The image analysis of sea-floor photography was carried out for correcting the abundance of nodules, and the image enhancement techniques and edge detection method were used to discriminate between nodules and sediments. The trace of nodules on sediments was detected to reduce the fractionation effect in calculating the coverage of nodules. The three methods, using the coverage of nodules, using the volume density, and using corrected volume density, were utilized for the correction of the nodule abundance. The method using the coverage of nodules was more convenient and available for the correction of nodule abundance than the other two methods. The method using the corrected volume density had the highest confidence level compared with the other methods.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.40-43
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• 2009

최근 모바일 영상기반 응용 분야에 관한 연구가 활발히 진행되고 있으며 모바일기기로 촬영된 영상에서 문자정보를 추출하고자 하는 많은 연구도 진행되고 있다. 자연이미지로부터 문자정보를 추출을 위한 전단계로 문자영역 검출이 필수적이다. 본 연구는 문자영역의 지역적 에지 및 연결요소 특징을 고려하여 조명 및 복잡한 배경에서도 문자영역을 검출하는 방법을 제안한다. 에지 검출은 캐니-에지 검출기로 추출하고, RGB 컬러분포 패턴을 분석하여 컬러 양자화를 함으로서 연결성분을 추출한다. 각각 추출된 에지 및 연결성분으로부터 문자후보 영역을 검출하고, 각각의 결과를 결합하여 최종적인 문자 후보 영역을 검출하고, 문자 후보 영역에 대한 검증을 수행함으로서 최종적인 문자영역을 검출한다. 제안한 방법은 다양한 환경에서 얻어진 자연이미지를 대상으로 실험한 결과, 에지 및 연결성분의 두 가지 특징을 결합함으로서 자연이미지에 존재하는 다양한 형태의 문자영역을 효과적으로 검출하였다.

• Atmosphere
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• v.24 no.2
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• pp.235-243
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• 2014

Sources of aviation turbulence vary through the seasons, especially in the East Asia including Korean peninsula, associated primarily with the changes in the jet/front system and convective activities. For this reason, a seasonal Korean aviation Turbulence Guidance (KTG) system (seasonal-KTG) is developed in the present study by using pilot reports (PIREPs) and analysis data of the operational Unified Model (UM) of the Korea Meteorological Administration (KMA) for two years between June 2011 and May 2013. Twenty best diagnostics of aviation turbulence in each season are selected by the method of probability of detection (POD) using the PIREPs and UM data. After calculating a weighting value of each selected diagnostics using their area under curve (AUC), the 20 best diagnostics are combined with the weighting scores into a single ensemble-averaged index by season. Compared with the current operational-KTG system that is based on the diagnostics applying all seasons, the performances of the seasonal-KTG system are better in all seasons, except in fall.

• Journal of Biomedical Engineering Research
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• v.30 no.3
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• pp.185-190
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• 2009

Biomedical mobile devices for ubiquitous healthcare consist of biomedical sensors and communication terminal. They have two types of configuration. One is the sensor-network type device using wired or wireless communication with intelligent sensors to acquire biomedical data. The other is the sensor embedded type device, where the data can be acquired directly by itself. There are many examples of sensor network type, such as, fall detection sensor, blood glucose sensor, and ECG sensors networked with commercial PDA phone and commercial phone terminal for ubiquitous healthcare. On the other hand, sensor embedded type mounts blood glucose sensor, accelerometer, and etc. on commercial phone. However, to enable true ubiquitous healthcare, motion sensing is essential, because users go around anywhere and their signals should be measured and monitored, when they are affected by the motion. Therefore, in this paper, two biomedical mobile devices with motion monitoring function were addressed. One is sensor-network type with motion monitoring function, which uses Zigbee communication to measure the ECG, PPG and acceleration. The other is sensor-embedded type with motion monitoring function, which also can measure the data and uses the built-in cellular phone network modem for remote connection. These devices are expected to be useful for ubiquitous healthcare in coming aged society in Korea.

• Smart Structures and Systems
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• v.6 no.7
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• pp.851-866
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• 2010

This paper presents a new concept of using PZT (lead zircornate titanate) transducers as a non-destructive testing (NDT) tool for evaluating quality of concrete. Detection of defects in concrete is very important in order to check the integrity of concrete structures. The electro-mechanical impedance (EMI) response of PZT transducers bonded onto a concrete specimen can be used for evaluating local condition of the specimen. Measurements are carried out by electrically exciting the bonded PZT transducers at high frequency range and taking response measurements of the transducers. In this study, the compression test results showed that concrete specimens without sufficient compaction are likely to fall below the desired strength. In addition, the strength of concrete was greatly reduced as the voids in concrete were increased. It was found that the root mean square deviation (RMSD) values yielded between the EMI signatures for concrete specimens in dry and saturated states showed good agreement with the specimens' compressive strength and permeable voids. A quality metric was introduced for predicting the quality of concrete based on the dry-saturated state of concrete specimens. The simplicity of the method and the current development towards low cost and portable impedance measuring system, offer an advantage over other NDE methods for evaluating concrete quality.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.400-403
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• 2010

도로상의 안개로 인한 시정감소는 교통사고를 유발하는 주된 원인이므로 전방의 운전자에게 도로의 시정거리를 미리 알려주어 안전운행을 유도하기 위한 안개경고시스템은 도로의 안전관리를 위해 매우 중요한 요소이다. 우리는 CCTV 카메라 영상에서 도로상에 통행중인 차량의 이동영역이 시정에 따라 달라진다는 점에 착안하여 이동영역을 추출하고 이를 이용하여 가시거리를 계산하는 시정 측정 장치를 개발하고 있으며, 주간, 야간 등 날씨의 변화에 덜 민감하면서도 효과적이고 정확한 이동영역의 추출은 시정측정을 위해 매우 중요하다. 본 논문에서는 이동영역의 추출을 위해 영상대비를 이용하여 자동으로 임계치를 결정하는 방법을 제안하며, 결정된 임계치를 적용시킴으로써 프레임간의 차영상으로 부터 잡음이 효과적으로 제거될 수 있음을 보인다. 또한, 차영상을 일정시간 누적시키는 방법을 통해 효과적으로 차량의 이동영역이 추출 되는 것을 보이기 위해 실제 고속도로에서 촬영된 CCTV 영상을 이용하여 실험한 결과를 제시한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.324-329
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• 2005

This research investigates the electromechanical characteristics of a spindle motor in a free-falling mobile hard disk drive before unexpected shock. Electromechanical simulation includes a time-stepping finite element analysis of the magnetic field in a speed controlled brushless DC motor and dynamic analysis of the stationary and rotating part linked by fluid dynamic bearing under the free-failing condition. Analysis results show that the dynamic characteristics of the rotating spindle system during free-falling state have an effect on the relative motion between the stationary and rotating part of HDD. It results from the variation of reaction force in the bearing area due to the gravely force exerted on the rotating part of HDD, and the free-failing condition can be detected by observing the signal of the spindle motor and disk-head interface without using the accelerometer.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.262-265
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• 2007

이미지 데이터베이스 시스템에서 이미지에 포함된 문자정보를 기반으로 검색어를 사용한다면 검색의 정확도 높일 수 있다. 이미지에서 문자정보를 추출을 위한 전단계로서 문자열 영역 검출이 필수적인 과제가 된다. 그러므로 본 논문에서는 문자의 크기와 문자열의 방향에 적응적인 문자-에지 맵을 이용한 문자열 영역 검출 방법을 제안한다. 캐니-에지 검출기로 에지를 추출하고, 생성된 에지 이미지로 레이블 이미지를 얻고, 그 영역의 문자구조 특징을 분석하기 위해서 배열문법으로 문자-에지 맵에 적응적으로 분석한다. 문자-에지 맵의 분석결과로서 문자열 후보 영역을 얻고, 문자열 영역의 구조적인 특징을 이용하여 문자열 후보 영역을 검증함으로서 최종적인 문자열 영역을 검출한다. 제안한 방법은 다양한 종류의 자연영상을 대상으로 실험하였고, 자연영상에서 기울어진 문자열과 다양한 크기의 문자를 갖는 문자열 영역을 효과적으로 검출하였다.

• ETRI Journal
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• v.44 no.2
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• pp.286-299
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• 2022

Human activity recognition in real time is a challenging task. Recently, a plethora of studies has been proposed using deep learning architectures. The implementation of these architectures requires the high computing power of the machine and a massive database. However, handcrafted features-based machine learning models need less computing power and very accurate where features are effectively extracted. In this study, we propose a handcrafted model based on three-dimensional sequential skeleton data. The human body skeleton movement over a frame is computed through joint positions in a frame. The joints of these skeletal frames are projected into two-dimensional space, forming a "movement polygon." These polygons are further transformed into a one-dimensional space by computing amplitudes at different angles from the centroid of polygons. The feature vector is formed by the sampling of these amplitudes at different angles. The performance of the algorithm is evaluated using a support vector machine on four public datasets: MSR Action3D, Berkeley MHAD, TST Fall Detection, and NTU-RGB+D, and the highest accuracies achieved on these datasets are 94.13%, 93.34%, 95.7%, and 86.8%, respectively. These accuracies are compared with similar state-of-the-art and show superior performance.