• ETRI Journal
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• v.35 no.3
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• pp.371-377
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• 2013

An effective signal detection algorithm with low complexity is presented for multiple-input multiple-output orthogonal frequency division multiplexing systems. The proposed technique, QR-MLD, combines the conventional maximum likelihood detection (MLD) algorithm and the QR algorithm, resulting in much lower complexity compared to MLD. The proposed technique is compared with a similar algorithm, showing that the complexity of the proposed technique with T=1 is a 95% improvement over that of MLD, at the expense of about a 2-dB signal-to-noise-ratio (SNR) degradation for a bit error rate (BER) of $10^{-3}$. Additionally, with T=2, the proposed technique reduces the complexity by 73% for multiplications and 80% for additions and enhances the SNR performance about 1 dB for a BER of $10^{-3}$.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.6
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• pp.1221-1225
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• 2009

The pulse diagnosis is an important and universally used method in Oriental Medicine. Since the traditional method of palpating the pulse relies on the subjective sense in the fingers of an Oriental Medical Doctor(OMD), there has been continued need for more objective method for pulse diagnosis. Recently, various pulse analyzers have been developed to meet such objective palpation and interpretation. However, most of these attempts were not successful to replace OMD's own palpation by fingers. To improve the performance of the pulse analyzers, one should develop machine-appropriate interpretations for the pulse images in the literature, in addition to the improvement in the repeatability and reproducibility. One of such widely-used pulse images to be interpreted is the floating and sinking pulse. The floating and sinking pulses are the two representative pulse images informing us how strong pressure one should apply to obtain the maximal pulse strength. A previous study suggested a convenient and unified measure for the floating and sinking pulses by defining the coefficient of the floating-sinking pulse(CFS). We found the original definition of the CFS could be erroneous under some situations. To improve the performance, we introduce new CFS algorithm for determining the floating and sinking pulse with a pulse analyzers(3-D MAC). To test the performance of the newly suggested algorithm, we conducted a clinical study comparing the agreement ratio with the floating and sinking pulse diagnosis by the OMDs. We found that, among the subjects who are diagnosed with having either the floating pulse or sinking pulse, the new CFS algorithm showed 55.3% diagnosis rate and 73.0% concordance rate, which are about 3% and 6% improvement in the diagnosis rate and agreement rate, respectively, compared to the original CFS algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.1075-1081
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• 2008

In this paper, we propose a code acquisition algorithm using optical orthogonal code (OOC) for optical code division multiple access (CDMA) systems. Generally, a good code acquisition algorithm offers short mean acquisition time (MAT). The conventional multiple-shift (MS) algorithm consists of two stages and has shorter MAT than that of well-known serial-search (SS) algorithm. This paper proposes a novel code acquisition algorithm called enhanced multiple-shift (EMS) algorithm. By using multiple thresholds, the proposed EMS algorithm provides shorter MAT compared with that of the MS algorithm. The simulation results show that the EMS algorithm presents shorter MAT compared with the MS algorithm in both single-user and multi-user environments.

• Journal of the Korean Society of Combustion
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• v.20 no.1
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• pp.24-31
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• 2015

Flame structure, which contains a useful information for studying combustion instability of the flame, is often quantitatively visualized with PLIF (planar laser-induced fluorescence) and/or chemiluminescence images. The latter, a line-integral of a flame property, needs to be preprocessed before being inverted, mainly due to its inherent noise and the axisymmetry assumption of the inversion. A preprocessing scheme utilizing multi-division of ROI (region of interest) of the chemiluminescence image is proposed. Its feasibility has been tested with OH PLIF and $OH^*$ chemiluminescence images of SNG (synthetic natural gas) swirl-stabilized flames taken from a model gas turbine combustor. It turns out that the multi-division technique outperforms two conventional ones: those are, one without preprocessing and the other with uni-division preprocessing, reconstructing the SNG flame structure much better than its two counterparts, when compared with the corresponding OH PLIF images. It is also found that the Canny edge detection algorithm used for detecting edges in the multi-division method works better than the Sobel algorithm does.

• ETRI Journal
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• v.29 no.4
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• pp.445-451
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• 2007

An adaptive modulation scheme is presented for multiuser orthogonal frequency-division multiplexing systems. The aim of the scheme is to minimize the total transmit power with a constraint on the transmission rate for users, assuming knowledge of the instantaneous channel gains for all users using a combined bit-loading and subcarrier allocation algorithm. The subcarrier allocation algorithm identifies the appropriate assignment of subcarriers to the users, while the bit-loading algorithm determines the number of bits given to each subcarrier. The proposed bit-loading algorithm is derived from the geometric progression of the additional transmission power required by the subcarriers and the arithmetic-geometric means inequality. This algorithm has a simple procedure and low computational complexity. A heuristic approach is also used for the subcarrier allocation algorithm, providing a trade-off between complexity and performance. Numerical results demonstrate that the proposed algorithms provide comparable performance with existing algorithms with low computational cost.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.2
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• pp.172-179
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• 2006

This study developed a program for detecting charged refrigerant amount in system air-conditioner. System air-conditioner is an air-conditioning system with multiple indoor units. Due to the complexity of the system, it is more difficult to detect the refrigerant amount charged in the system air-conditioner than in a general single air-conditioner. Experiments were performed for a 6 HP outdoor unit with 3 indoor units in a psychrometric calorimeter. The experimental amount of the charged refrigerant was ranged from $60\%\;to\;140\%\;with\;10\%$ increasement. Fuzzy algorithm was employed for detecting the charged refrigerant amount in the system air-conditioner. The experimental data were used for curve-fitting for the general ranges of indoor and outdoor temperature conditions. Membership function was determined for the whole ranges of experimentally measured data and rule-bases were defined for each charged refrigerant amount. Developed program successfully predicted the measured data within $10\%$ resolution range.

• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.64-70
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• 2005

Target Strength(TS) is an important factor for the detection of the target in an active sonar system: thus the numerical model for the prediction of TS is widely being developed. For the frequency range of several kHz, the most important scattering mechanism is known to be specular reflection, which is largely affected by the geometrical shape of the target. In this paper, a numerical algorithm to predict TS is developed based on the Kirchhoff approximation which is computationally efficient. The developed algorithm is applied to the canonical targets of simple shapes, for which the analytical solutions exist. The numerical results show good agreement with the analytical solutions. Also, the algorithm is applied to more complex scatterers, and is compared with the experimental data obtained in the water tank experiment for the purpose of verifying the developed numerical model. Discussions on the effect of spatial sampling and other aspects of numerical m odeling are presented.

• 순환기질환의공학회:학술대회논문집
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• 2006.04a
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• pp.10-19
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• 2006

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.2
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• pp.288-307
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• 2013

This paper formulates resource allocation for decode-and-forward (DF) relay assisted multi-cell orthogonal frequency division multiple (OFDM) networks as an optimization problem taking into account of inter-cell interference and users fairness. To maximize the transmit rate of system we propose a joint interference coordination, subcarrier and power allocation algorithm. To reduce the complexity, this semi-distributed algorithm divides the primal optimization into three sub-optimization problems, which transforms the mixed binary nonlinear programming problem (BNLP) into standard convex optimization problems. The first layer optimization problem is used to get the optimal subcarrier distribution index. The second is to solve the problem that how to allocate power optimally in a certain subcarrier distribution order. Based on the concept of equivalent channel gain (ECG) we transform the max-min function into standard closed expression. Subsequently, with the aid of dual decomposition, water-filling theorem and iterative power allocation algorithm the optimal solution of the original problem can be got with acceptable complexity. The third sub-problem considers dynamic co-channel interference caused by adjacent cells and redistributes resources to achieve the goal of maximizing system throughput. Finally, simulation results are provided to corroborate the proposed algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.967-971
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• 2009

The histogram equalization algorithm is the most crucial algorithm for image enhancement. Since its direct hardware implementation always requires a divider or multiplier, its implementation cost tends to increas as the image resolution is increased or diverse image resolutions are handled. In this paper, we propose a divider-free reconstruction of histogram equalization algorithm and the corresponding hardware architecture. The logic synthesis results show that the proposed scheme can reduce the logic gate count by 84.2% compared to the conventional implementation example when the UXGA resolution is considered.