• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1394-1402
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• 2011

This paper describes solar light collecting system which employs parabolic reflector and Fresnel lens and its industrial application. We have introduced second-stage optical system so that it makes optical fiber overcome its numerical aperture limitation and also it makes focused light become collimated, which results in decreased light energy density. As result of these, light collecting efficiency become maximized and the system does not require separate cooling apparatus any more. The developed solar lighting system together with artificial light source like LED has been applied to plant factory as a hybrid lighting source. This makes us save electric energy for artificial lighting during day time. The intensity of LED light in the hybrid lighting system is controlled automatically according to ambient-light-sensor installed in the system so that the light intensity for a plant always keeps the same level no matter how the sun light changes. For a plant factory whose size is 330 square meters, when solar lighting system is applied, 28,080KWh electric energy can be saved per month.2 times.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.236-242
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• 2010

A GNSS/INS integration system can not provide navigation solutions if there are no available satellites. To overcome this problem, a vision sensor is integrated with this system. Since generally a vision aided integration system uses only feature point to compute navigation solutions, it has a problem in observability. In this case, additional landmarks, which is priory known points, can improve the observability. In this paper, the observability is evaluated using TOM/SOM matrix and Eigenvalues. There are always the observability problems in the feature-point-only case, but the landmark-use case is fully observable after the $2^{nd}$ update time. Consequently the landmarks ensure full observability, so the system performance can be improved.

• Journal of the Korea Convergence Society
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• v.8 no.5
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• pp.19-28
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• 2017

In this paper, we propose a method to reduce the difference in image characteristics when multiple camera images are captured for virtual space production. Sixty-four images were used by cross-mounting eight bodies and lenses, respectively. Image analysis compares and analyzes the standard deviation of the histogram and pixel distribution values. As a result of the analysis, it shows different image characteristics depending on the lens or image sensor, though it is a camera of the same model. In this paper, we have adjusted the distribution of the overall brightness value of the image to compensate for this difference. As a result, the average deviation was the maximum of (Indoor: 6.89, outdoor: 24.23), we obtained images with almost no deviation (Indoor: maximum 0.42, outdoor: maximum: 2.73). In the future, we will study and apply more accurate image analysis methods than image brightness distribution.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.2
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• pp.215-222
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• 2016

Research on gait recognition and its use is actively underway. This study suggests a method to recognize abnormal gaits of pedestrians. The purposes of the existing research to recognize normal steps are to measure physical activities and to validate people by their walks, but the purpose to recognize abnormal steps in this study is to insure the safe life of pedestrians. There are situations in which pedestrians are unaware of themselves vulnerable and can not ask for help. The purpose of this research is that even if pedestrians are unaware of themselves and there are no spontaneous requests for helps, it is intended for them to escape from dangers and difficulties by adopting the recent IOT technology. Hence, this study analyzes normal pace of pedestrians using the triaxial acceleration sensors, and takes ranges of their normal walking. And then, the steps of pedestrians are measured using the triaxial acceleration sensors, contrasted with their normal walking ranges, and determine whether their steps are normal or not. When it is out of the state for normal paces, a method to determine as abnormal paces is suggested.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.101-109
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• 2004

This paper presents a novel z-axis accelerometer with perfectly aligned vertical combs fabricated using the extended sacrificial bulk micromachining (extended SBM) process. The z-axis accelerometer is fabricated using only one (111) SOI wafer and two photo masks without wafer bonding or CMP processes as used by other research efforts that involve vertical combs. In our process, there is no misalignment in lateral gap between the upper and lower comb electrodes, because all critical dimensions including lateral gaps are defined using only one mask. The fabricated accelerometer has the structure thickness of $30{\mu}m$, the vertical offset of $12{\mu}m$, and lateral gap between electrodes of $4{\mu}m$. Torsional springs and asymmetric proof mass produce a vertical displacement when an external z-axis acceleration is applied, and capacitance change due to the vertical displacement of the comb is detected by charge-to-voltage converter. The signal-to-noise ratio of the modulated and demodulated output signal is 80 dB and 76.5 dB, respectively. The noise equivalent input acceleration resolution of the modulated and demodulated output signal is calculated to be $500{\mu}g$ and $748{\mu}g$. The scale factor and linearity of the accelerometer are measured to be 1.1 mV/g and 1.18% FSO, respectively.

• Journal of Korea Game Society
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• v.12 no.2
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• pp.15-29
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• 2012

In order to predict satisfaction and performance of sensible healthcare game using motion recognition sensor, this study analyzed the effects of flow, presence and social cognitive factor and then, it attempted to verify structural relationships thereof. Self-efficacy, being a social cognitive factor, was found to affect the level of functional satisfaction of health game but it showed no direct effect to intention of using game. Flow experience was also observed to be a meaningful predictor for the level of functional and entertainment satisfaction in the direction hypothesized. It is also shown that presence exerts a direct effect on functional satisfaction. Finally, it is discovered that functional satisfaction has meaningful influence on entertainment satisfaction as well as future intention to use. The results verifies that even in sensible healthcare game, user experience and social cognitive factor have significant effects on satisfaction and performance of a serious game.

• Journal of Sensor Science and Technology
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• v.23 no.2
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• pp.105-109
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• 2014

Structure and electrical properties of $0.85NaNbO_3-0.15LiNbO_3$ ($(Li_{0.15}Na_{0.85})NbO_3$) ceramics were investigated as a function of sintering temperature. $(Li_{0.15}Na_{0.85})NbO_3$ ceramics were prepared by conventional solid state processing. A main phase of the orthorhombic perovskite structure and secondary phase of $LiNbO_3$ were confirmed for all sintered specimens. Dense $(Li_{0.15}Na_{0.85})NbO_3$ ceramics were obtained at sintering temperature above $1050^{\circ}C$. With increasing sintering temperature, the electromechanical coupling factor ($k_p$), piezoelectric constant ($d_{33}$) and relative dielectric constant (${\varepsilon}_r$) of the sintered specimens increased, while the mechanical quality factor ($Q_m$) decreased. These results are due to the increase of grain size and crystallite size of orthorhombic perovskite structure. Based on the temperature dependence of ${\varepsilon}_r$, stable piezoelectric properties were expected because no phase transition found up to $300^{\circ}C$. Typically, kp of 18%, $d_{33}$ of 34.7 pC/N, ${\varepsilon}_r$ of 135, and $Q_m$ of 62.8 were obtained for the specimens sintered at $1200^{\circ}C$ for 5 h.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.91-98
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• 2010

In order to control moving facilities on a remote place effectively, it are required to acquire a environment informations such as images where the moving facilities are placed. However, since there is no tools to acquire such informations to the central control system based on the non-networked sensor environments, it is difficult to control the moving facilities remotely. Therefore, we design and implement the Zigbee based image transmission system and communication protocol to control the moving target remotely. The wireless control utilizing the Zigbee protocol is that electrically consumption is more small than the Bluetooth and reliability of data transmission is better. The implemented Zigbee based control systems and communication protocol have the normal and replay function for a realtime control of the moving target under the server PC and the mobile FDA with the WiFi protocol. The functional operability and performance are analyzed by a designed prototype under the wireless home network environment.

• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.191-196
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• 2010

The purpose of this study was to investigate the effect of gait speed and walkway slope on the body acceleration, for the future validation of using an accelerometer in the estimation of energy consumption. Ten young healthy subjects with accelerometers on the upper thigh and ankle walked on a treadmill at 9 conditions(three speeds ${\times}$ three slopes) for 5 minutes. Acceleration signals of four directions, i.e. anterior-posterior(AP), medio-lateral(ML), superior-inferior(SI) and vector sum(VS) directions, of each sensor were measured, and root means squared(RMS) values of them were used as analysis variables. As statistical analysis, repeated measure two-way ANOVA was performed for RMS accelerations at each attachment sites, with slope and velocity as independent factors. At both the upper thigh and ankle, RMS acceleration of all directions were affected by gait velocities(p<.001) showing greater accelerations for higher velocities. Contrary to expectations, no slope effect existed in RMS accelerations at hip. Moreover, RMS acceleraion at ankle decreased with slope in SI and VS directions(p<.01). These results suggests that RMS acceleration cannot reflect the change in physical activity due to the change in walkway slope.

• The Journal of Korean Academy of Prosthodontics
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• v.24 no.1
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• pp.141-150
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• 1986

This study conducted 2 types of occlusal splint therapy to eliminate clicking sound. 15 patients who had clicking on their joints were selected, and divided, at random, into 3 groups. In the first group, 4 persons put on stabilization splint and in the second group, 6 persons put on anterior repositioning splint which had made condyle to protrude 3mm, and in the last group, 5 persons put on anterior repositioning splint which had made condyle to protrude 6mm. Patients who wore anterior repositioning splint were instructed to use the splint for all days. The evaluation of clicking was measured by occlusal soundscope. The clicking was converted to aucostic signal by the attached microphone, instead of vibrating sensor The in-put aucostic signal on the occlusal soundscope made it possible to observe the experiment's result. Anterior repositioning splint was produced in the centric occlusion state, when the model was mounted to articulator and inserted two pieces of 3mm and 6mm resin blocks each into the rear wall of articulator fossa. The observation of the patients who wore three different splints for 3 weeks has reached the following conclusions: 1. Stabilization splint produced no effect in eliminating the clicking sound. 2. Anterior repositioning splint therapy with 3mm condylar protrusion produced significant improvement in eliminating the clicking sound. 3. The 6mm protruded anterior repositioning splint caused pain on affected TMJ area as well as the clicking on unaffected joint.