• 디지털산업정보학회논문지
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• 제13권4호
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• pp.81-90
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• 2017

This paper presents a smart seat for correction of driver posture while driving. We introduce good postures with seat height, seat angle, head height, back of knees, distances of foot pedals, tilt of seat, etc. There have been some studies on correction of good posture while driving, effects of driving environment on driver's posture, sitting strategies based on seating pressure distribution, estimation of driver's standard postures, and others. However, there are a few studies on guide of good postures while driving for problem of driver's posture using machine leaning. Therefore, we suggest a smart seat for correction of driver's posture based on machine leaning, 1) developed the system to get postures by 10 piezoelectric effect element, 2) collect piezoelectric values from 37 drivers and 28 types of cars, 3) suggest 4 types of good postures while driving, 4) analyze test postures by kNN. As the results, we can guide good postures for bad or problems of postures while driving.

• Journal of Astronomy and Space Sciences
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• 제31권4호
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• pp.347-351
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• 2014

Planetary exploration rovers are likely to make a trip on a winding and sloping road of irregular surfaces to the destination in order to accomplish scientific missions. One of the key technologies for rovers is a suspension for traveling and performing exploration missions; the suspension is an essential area of technology for a stable movement of a rover. In this study, an 8-wheel suspension is designed to enable efficient climbing of slopes on a passage to the destination. For the two front wheels among the eight wheels, the moment at the pivot connecting two wheels is derived when the distance between the wheels and the torque of wheels are same. A test experiment was performed to compare the magnitude of moment according to the change in tilt angle and the position of the pivot. Finally, a suspension design considering the position of the pivot was proposed to enhance the hill-climbing performance.

• Wind and Structures
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• 제21권6호
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• pp.677-691
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• 2015

In this study, the geometrical setup of a turbine blade is tracked. A research-scale rotating turbine blade system is setup with a single 3-axes accelerometer mounted on one of the blades. The turbine system is rotated by a controlled motor. The tilt and rolling angles of the rotating blade under operating conditions are determined from the response measurement of the single accelerometer. Data acquisition is achieved using a prototype wireless sensing system. First, the Rodrigues' rotation formula and an optimization algorithm are used to track the blade rolling angle and pitching angles of the turbine blade system. In addition, the blade flapwise natural frequency is identified by removing the rotation-related response induced by gravity and centrifuge force. To verify the result of calculations, a covariance-driven stochastic subspace identification method (SSI-COV) is applied to the vibration measurements of the blades to determine the system natural frequencies. It is thus proven that by using a single sensor and through a series of coordinate transformations and the Rodrigues' rotation formula, the geometrical setup of the blade can be tracked and the blade flapwise vibration frequency can be determined successfully.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.305-310
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• 2004

We have studied the optimal phase retardation value of a homogeneously aligned liquid crystal (LC) driven by fringe-field when using the LC with positive dielectric anisotropy. In general, the transmittance of a homogeneous aligned LC cell under crossed polarizer is maximum when a twist angle of LC by in-plane rotation is 45$^{\circ}$ with polarizer and the cell retardation becomes λ/2. However, the device using the LC with positive dielectric anisotropy does not follow this since the degree of rotation of the LC is dependent on electrode position and in addition the LCs tilt up along the fringe-field. At the center of common and pixel electrode, the LC is most twisted around a middle position of a cell whereas at the edge position of pixel electrode, the LC is most twisted near bottom surface of a cell. Consequently, the optimal phase retardation of the device becomes much larger than λ/2 and the transmittance can be described using the combination of the in-plane switching and twisted nematic mode.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.3016-3018
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• 2005

The PSD(Position Sensitive Detector) is a sensor for detecting the position of incident light. Because of its various advantages, it is used for position and angle sensing, optical range finders, laser displacement sensing, and etc. In the previous study of the position finding system, the laser tracking robot is developed. Small data rate and unidirectionality is the characteristics of data communication both DSP-based pan/tilt control board and the robot. If we can transmit data to the target using PSD sensor and laser diode module, there is no need for communication devices such as the bluetooth and wireless module. For this reason, this paper presents the new method for data transmission. Transmit data using RS-232 is modulated by a VTF(Voltage To Frequency) converter The laser diode module transmits the modulated data. And then the PSD sensor receive that data. Demodulation process is accomplished by the system which is consisted with trans-impedance amplifier, FTV(Frequency To Voltage) converter, and etc.

• 한국지구과학회지
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• 제36권5호
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• pp.437-446
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• 2015

Many edge detection methods, based on horizontal and vertical derivatives, have been introduced to provide us with intuitive information about the horizontal distribution of a subsurface anomalous body. Understanding the characteristics of each edge detection method is important for selecting an optimized method. In order to compare the characteristics of the individual methods, this study applied each method to synthetic magnetic data created using homogeneous prisms with different sizes, the numbers of bodies, and spacings between them. Seven edge detection methods were comprehensively and quantitatively analyzed: the total horizontal derivative (HD), the vertical derivative (VD), the 3D analytic signal (AS), the title derivative (TD), the theta map (TM), the horizontal derivative of tilt angle (HTD), and the normalized total horizontal derivative (NHD). HD and VD showed average good performance for a single-body model, but failed to detect multiple bodies. AS traced the edge for a single-body model comparatively well, but it was unable to detect an angulated corner and multiple bodies at the same time. TD and TM performed well in delineating the edges of shallower and larger bodies, but they showed relatively poor performance for deeper and smaller bodies. In contrast, they had a significant advantage in detecting the edges of multiple bodies. HTD showed poor performance in tracing close bodies since it was sensitive to an interference effect. NHD showed great performance under an appropriate window.

• 한국전문물리치료학회지
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• 제5권2호
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• pp.23-38
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• 1998

The objective of this study was to identify the effects of pelvic tilting exercise on gait patterns of hemiplegic patients. The subjects of this study were 31 hemiplegic in- and out-patients of the Rehabilitation Hospital, Yonsei University Medical Center, from September 24, 1997 through November 5, 1997. Pre- and post-treatment change in gait patterns were measured using a ink foot-print. The data were analyzed by the paired t-test, one-way ANOVA, and independent t-test. The findings were as follows: The difference in gait patterns between pre- and post-treatment was statistically significant, with an increase in gait velocity to 7.98 cm/sec post-treatment; an increase in cadence to 7.29 steps/min; a narrowing of the base of support to 1.33 cm; an increase in step length of 3.92 cm on the less affected side and 3.73 cm on the more affected side; an increase in stride length of 5.82 cm on the less affected side and 5.92 cm on the more affected side(statistically not significant in foot angle). In relation to sex, age, cause of stroke, and laterality of paralysis, the difference in gait patterns between pre- and post-treatment was not statistically significant. Where there was no significant difference of the effects of pelvic exercise regarding the degree of spasticity, the presence of a decrease in proprioception, and the duration of treatment. In conclusion, hemiplegic pelvic tilting exercise was found to have transmitting positive effect in improving gait patterns.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.776-779
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• 2006

The alignment of liquid crystal (LC) is one of the key issues of liquid crystal display (LCD) technologies. In this study, we aligned polyimide (as the LC alignment layer) by ALT plasma beam and to realize the stability and characteristics of this technology. The characteristics such as anchoring energy, pre-tilt angle, voltage holding ratio(VHR) and residual direct current(Rdc) were discussed. Besides, we applied it to the in plane switch (IPS) mode 23" WXGA real panel, the performance parameters and electrical properties were measured and compared with those of rubbing alignment. From the result, we demonstrated a successful LC alignment treatment process in real panel by ALT plasma beam.

• 전자공학회논문지SC
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• 제48권6호
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• pp.1-7
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• 2011

본 논문에서는 역진자 시스템과 이동로봇 시스템의 두 시스템으로 구성된 두 바퀴 구동 이동로봇의 구현 및 제어에 대해 논한다. 제어 목적은 균형을 유지하며 이동하는 것이다. 밸런싱 로봇은 한 점에서 회전이 가능하고 바닥으로 부터의 외란에 강건한 균형을 유지한다. 국부 및 전역 좌표계에서의 제어방식의 시뮬레이션을 수행하였다. 로봇이 대칭을 이루도록 만들어졌기 때문에 균형과 주행제어에 간단한 선형 제어기를 사용하였다. 기울어진 각도를 추출하기 위해 자이로와 기울기 센서를 융합하여 사용하였다. 주어진 원형 경로를 주행하는 실험을 수행하였다.

• 전기전자학회논문지
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• 제2권2호
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• pp.173-177
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• 1998

실내환경에서의 광무선 LAN은 송수신기 사이의 시정선이 성립되지 않는 경우 넓은 수광각을 얻기 위해 반구형 렌즈나 반사체를 사용해야 하며, 실내환경에서 반구형 렌즈를 사용했을 때, 교란대기를 통과하는 광신호는 진폭과 위상이 불규칙하게 변화하고, 빔을 편향시킬 수 있다. 이 페이딩은 비트오류율을 증가시켜 결국 광무선통신의 성능을 저하시키게 된다. 본 논문에서는 시정선이 성립되지 않는 광무선채널을 고려하여 수신기에 반구형 렌즈를 장착한 경우, 천정각에 따른 신호대잡음비를 고찰하고, 또한 실내온도에 기인한 교란효과가 통신성능에 미치는 영향를 살펴 본다.