• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.125-130
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• 2013

According to the law revision of TPMS mounting obligations in Korea, researches about energy harvester which is the alternative of the battery are actively performed by many groups. Because WSN (Wireless Sensor Network) has the proposition of "Install and forget" and the power supplier also has the same performance as the vehicle's lifetime. In this paper, electromagnetic induction type of energy harvester through the relative motion between the rotating wheel and the fixed brake disc is introduced by using the most efficient source as the rotating motion in the view of vehicle's mechanism. The coil on the wheel and the permanent magnet at the brake disc are arranged in several ways. These various arrangements are the number of coil turns are consisted of design variables. By using the orthogonal array to reduce the experimental cost, the optimal composition is verified through the experiment. Finally the validity of the module is considered by measuring the level of storable electrical energy.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.1
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• pp.218-227
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• 1996

The purpose of this study was performed to analyze the trend of bodytype change of adult males. Subjects were 1290 Korean adult males and their age range was from 19 to 54 year, ; old. 75 variables(66 variables from the direct anthropometric data and 9 variables from the multiplication method) in total were applied to analyze. The principal component analysis was applied to the data with orthogonal rotation after extraction of major factors. The high factor loading items extracted by factor analysis were analyzed for the trend of bodytype change by the age group respectively. The result of factor analysis indicated that the first factor was composed with about 30 items, girth, depth and width-measures in 4 age groups and was analysed as form factors. Especially, age-related change was caused by increase of waist girth, depth and width. The second factor was composed with about 23 items, length and height-measures in all age groups. Stature has a constant factor loading value in 4 groups. Front and back waist-height and the navel-height have the highest factor loading value. The third, fourth and fifth factors were composed with different variables among the age groups.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5370-5393
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• 2019

In this paper, we consider a two-way relay non-orthogonal multiple access (TWR-NOMA) system with residual hardware impairments (RHIs) and channel estimation errors (CEEs), where two group users exchange their information via the decode-and-forward (DF) relay by using NOMA protocol. To evaluate the performance of the considered system, exact analytical expressions for the outage probability of the two groups users are derived in closed-form. Moreover, the asymptotic outage behavior in the high signal-to-noise ratio (SNR) regime is examined and the diversity order is derived and discussed. Numerical simulation results verify the accuracy of theoretical analyses, and show that: i) RHIs and CEEs have a deleterious effects on the outage probabilities; ii) CEEs have significant effects on the performance of the near user; iii) Due to the RHIs, CEEs, inter-group interference and intra-group interference, there exists error floors for the outage probability.

• East Asian mathematical journal
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• v.22 no.2
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• pp.249-257
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• 2006

Let n be a 2-step nilpotent Lie algebra which has an inner product <,> and has an orthogonal decomposition $n=\delta{\oplus}\varsigma$ for its center $\delta$ and the orthogonal complement $\varsigma\;of\;\delta$. Then Each element Z of $\delta$ defines a skew symmetric linear map $J_Z:\varsigma{\rightarrow}\varsigma$ given by $=$ for all $X,\;Y{\in}\varsigma$. Let $\gamma$ be a unit speed geodesic in a 2-step nilpotent Lie group H(2, 1) with its Lie algebra n(2, 1) and let its initial velocity ${\gamma}$(0) be given by ${\gamma}(0)=Z_0+X_0{\in}\delta{\oplus}\varsigma=n(2,\;1)$ with its center component $Z_0$ nonzero. Then we showed that $\gamma(0)$ is conjugate to $\gamma(\frac{2n{\pi}}{\theta})$, where n is a nonzero intger and $-{\theta}^2$ is a nonzero eigenvalue of $J^2_{Z_0}$, along $\gamma$ if and only if either $X_0$ is an eigenvector of $J^2_{Z_0}$ or $adX_0:\varsigma{\rightarrow}\delta$ is not surjective.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.181-190
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• 2014

This paper reports a cognitive radio network architecture based on overloaded multicarrier direct sequence code division multiple access (O-MC-DS-CDMA). The O-MC-DSCDMA technique combines CDMA with a multicarrier modulation technique to overcome the channel fading effects. In this technique, secondary users are enabled to share the available bandwidth with the existing primary users. Two sets of orthogonal Gold codes are used to support the primary and secondary users simultaneously. The orthogonality between the spreading codes is lost due to the non-zero cross correlation between the codes and the timing synchronization error in the uplink transmission, which causes interference between primary and secondary users. This paper proposes two modified hybrid parallel/successive interference cancellation techniques for primary and secondary user base station receivers with multiple antennas to suppress the interference among users. Interference among the same group of users is cancelled by parallel interference cancellation and the interference among groups is cancelled using successive interference cancellation. The simulation results confirmed that the proposed modified interference cancellation techniques show better BER performance over conventional interference cancellation techniques.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7A
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• pp.720-726
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• 2008

In this paper, we propose a multi-cell cooperation method for broadcast packet data services in the orthogonal frequency division multiplexing (OFDM)-based cellular system with multiple transmit antennas. In the proposed method, to transmit two streams of spatially demultiplexed or transmit diversity coded symbols over a number of transmit antennas, we divide a coded packet into multiple subparts to which different cell groups and antenna pairs are assigned. The proposed method enhances the diversity order by transforming the channel frequency responses of two symbol streams in each subpart of the broadcast packet. The increase in diversity of the proposed method is shown with the outage probability under various configurations.

• Wind and Structures
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• v.38 no.5
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• pp.381-398
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• 2024

This study presents a mode analysis of 3D turbulent velocity data around a square-section building model to identify the dynamic system for Kármán-type vortex shedding. Proper orthogonal decomposition (POD) was first performed to extract the significant 3D modes. Magnitude-squared coherence was then applied to detect the phase consistency between the modes, which were roughly divided into three groups. Group 1 (modes 1-4) depicted the main vortex shedding on the wake of the building, with mode 2 being controlled by the inflow fluctuation. Group 2 exhibited complex wake vortexes and single-sided vortex phenomena, while Group 3 exhibited more complicated phenomena, including flow separation. Subsequently, a third-order polynomial regression model was used to fit the dynamics system of modes 1, 3, and 4, which revealed average trend of the state trajectory. The two limit cycles of the regression model depicted the two rotation directions of Kármán-type vortex. Furthermore, two characteristic periods were identified from the trajectory generated by the regression model, which indicates fast and slow motions of the wake vortex. This study provides valuable insights into 3D mode morphology and dynamics of Kármán-type vortex shedding that helps to improve design and efficiency of structures in turbulent flow.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.107-114
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• 2012

In this paper, we propose a new modulation scheme called multi-coded variable pulse position modulation (MC-VPPM) for visible light communication systems. Two groups of signals (Pulse Width Modulation (PWM) and Pulse Position Modulation (PPM) groups) are multi-coded by orthogonal codes for transmitting data simultaneously. Then, each multi-level value of the multi-coded signal is converted to pulse width and position which results in not only an improved data rate, but also a processing gain in reception. In addition, we introduce average duty ratio and cyclic shift concepts in PWM through which dimming control for light illumination can be supported without any degradation in communication performance. Through simulation, we confirm that the proposed MC-VPPM shows a comparable BER curve and much greater achievable data rate than the conventional VPPM scheme using a visible light optical channel environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1363-1376
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• 2020

An improved clustering scheme based on user group is proposed. Every two users are grouped among N-users in the allowed system according to their link gain from large to small. Each user group is numbered sequentially. Two user clusters are obtained according to the principle of maximizing link gain difference for the users in the first and last user groups. The remaining user groups are added to the two existing user clusters according to the parity of the group number. The clustering should be clustered again among the users in either user cluster if the throughput summation of a user cluster in NOMA is less than that of these users in orthogonal multiple access. The simulation results show that the proposed clustering scheme can increase the system throughput by about 8% compared with the hybrid clustering scheme when the number of users requiring service is 12.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1467-1472
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• 2013

Metabolomics is a field that studies systematic dynamics and secretion of metabolites from cells to understand biological pathways based on metabolite changes. The metabolic profiling of intact human colorectal tissues was performed using high-resolution magic angle spinning (HR-MAS) NMR spectroscopy, which was unnecessary to extract metabolites from tissues. We used two different groups of samples, which were defined as normal and cancer, from 9 patients with colorectal cancer and investigated the samples in NMR experiments with a water suppression pulse sequence. We applied target profiling and multivariative statistical analysis to the analyzed 1D NMR spectra to identify the metabolites and discriminate between normal and cancer tissues. Cancer tissue showed higher levels of arginine, betaine, glutamate, lysine, taurine and lower levels of glutamine, hypoxanthine, isoleucine, lactate, methionine, pyruvate, tyrosine relative to normal tissue. In the OPLS-DA (orthogonal partial least square discriminant analysis), the score plot showed good separation between the normal and cancer groups. These results suggest that metabolic profiling of colorectal cancer could provide new biomarkers.