• Proceedings of the IEEK Conference
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• 2001.06c
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• pp.13-16
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• 2001

In reinforcement teaming, Q-learning converges quite slowly to a good policy. Its because searching for the goal state takes very long time in a large stochastic domain. So I propose the speedup method using the Q-value initialization for model-free reinforcement learning. In the speedup method, it learns a naive model of a domain and makes boundaries around the goal state. By using these boundaries, it assigns the initial Q-values to the state-action pairs and does Q-learning with the initial Q-values. The initial Q-values guide the agent to the goal state in the early states of learning, so that Q-teaming updates Q-values efficiently. Therefore it saves exploration time to search for the goal state and has better performance than Q-learning. 1 present Speedup Q-learning algorithm to implement the speedup method. This algorithm is evaluated. in a grid-world domain and compared to Q-teaming.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.205-209
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• 2006

For measuring the viable cells in lakes, quantitative direct viable count (qDVC) method is applied. In the qDVC process, the final concentration of glycine is fixed as 2%. For confirming the effectiveness of qDVC for enumerating the viable cells, the viable bacterial numbers were measured by plate count, CTC reduction method and qDVC method at 5 different lakes. Among these 3 methods, the bacterial numbers by qDVC is $2.4{\sim}6.0$ times higher than those by the other 2 methods. And by the qDVC method, the viable cells were easily discriminated from dead or dormant cells.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1A
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• pp.37-45
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• 2005

In this paper, after analyzing the effect of I/Q imbalance in an OFDM system, the detection method of an OFDM signal distorted by I/Q imbalance is proposed. Also, the channel estimation and the pilot symbol design scheme are proposed for using the proposed detection method. Since I/Q imbalance in an OFDM system degrades the SIR and the BER(Bit Error Ratio) performance, the robust detection method is required for an OFDM system. the proposed detection method can effectively suppress the interference caused by I/Q imbalance using characteristics of an OFDM signal differently from the conventional method, and results in improving the SIR of a desired OFDM signal.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.285-291
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• 2003

An experimental method to measure Q-parameter in-situ is described. The basic idea comes from the fact that the side necking near a crack tip indicates the loss of stress triaxiality, which can be scaled by Q. From the out-of-plane displacement and the in-plane strain near the surface of side necking, stress field averaged through the thickness is calculated and then Q is determined from the difference between the stress field and the HRR field corresponding to the identical J-integral. To prove the validity, three-dimensional finite element analysis has been performed for a CT configuration with side-groove. Q-value which was calculated directly from the near-tip stress field is compared with that determined by simulating the experimental procedure according to the proposed method, that is, the Q-value determined from the lateral displacement and the inplane strain. Also, the effect of location where the displacement and strain are measured is explored.

• Journal of the Korean Geophysical Society
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• v.5 no.3
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• pp.211-218
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• 2002

The reversed two station method (RSTM) devised by Chun et al. (1987) is widely used to obtain $Q_{Lg}^{-1}$ for Lg wave data with hypocentral distance greater than 90 km. By applying RSTM to the Lg data of central South Korea with hypocentral distance between 95 and 381 km, we obtained high $Q_{Lg}^{-1}$. The value of $Q_{Lg}^{-1}$ is very similar with that of southeastern S. Korea, which is derived from the same method for similar distances. The studied hypocentral range seems to distort $Q_{Lg}^{-1}$ to high value because decay rate in this range is higher than 0.5, which is typical decay rate of surface wave.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.579-582
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• 2003

In this paper, we propose a 4-step inference method needed for constructing a natural language communication system. The method is used to obtain fuzzy quantifier Q′when QA is Fisr τ⇔ Q′(m′A) is mF is m"is τ is inferred (Q, Q′: quantifiers, A: fuzzy subject, m′, m": modifiers, y: fuzzy predicate, τ: truth qualifier). We show that Q′is resolved step by step for two types of Q, including a non-increasing type (few,...) and a non-decreasing type(most,...).

• Proceedings of the Korea Society for Simulation Conference
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• 1999.10a
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• pp.62-62
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• 1999

In this paper, we propose a new technique of estimating tail of steady-state queue length distribution; Pr(Q>q), fo ATM multiplexer. Pr(Q>q) is a fundamental measure of network congestion. Assessing Pr(Q>q) properly is crucial for design and control of ATM networks. Data traffic pattern of high-speed networks is highly correlated and bursty. Estimating Pr(Q>q) is very difficult because of correlation and burstiness. We estimate entropy(rate-function) using large deviation principles and threshold bootstrap. Simulation studies are conducted to compare the performance of an existing method and our new method.

• Geophysics and Geophysical Exploration
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• v.14 no.3
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• pp.242-248
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• 2011

By applying analytic method to the uniform model, the intrinsic and scattering quality factor ($Q_i^{-1}$ and $Q_s^{-1}$) was separated for the southeastern part of Korean Peninsula. The Multiple Lapse Time Window Analysis method was used to fit theoretical values with observations obtained 759 earthquake data. While previous study for the Korean Peninsula showed very low $Q_i^{-1}$ and $Q_s^{-1}$ reflecting inactive seismicity, southeastern Korea exhibited relatively high $Q_i^{-1}$ and $Q_s^{-1}$ values interpreted as higher seismicity than the other region in the peninsula.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1265-1272
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• 2006

This paper proposes a compensation method that can alleviate the problem of I/Q mismatch generated in the direct-conversion receiver of OFDM systems. In the proposed method, the amount of I/Q mismatch is estimated using null-carriers in transmitted signals, and it is subtracted from received symbols to suppress I/Q mismatch effects. Simulations show experiments that the proposed method can effectively eliminate the I/Q mismatch effects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1146-1153
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• 2007

In this paper, we analyze the I/Q imbalances effects at the WiBro uplimk when using direct-conversion RF transceiver. If I/Q imbalance exists, the transmit signal is spread over two sbcarriers. As a result, phenomenon of performance reducing is produced. Contrary to OFDM system in which one user uses all subcarrier, symmetrical two subcarriers are assigned other users in OFDMA system. I/Q imbalances elements can't be estimated such a conventional allocation method of tiles in subchannel and compensated. In order to solve the problem, We propose a new method in order that symmetrical two subcarriers are assigned one user. If novel method is applied, we can estimate I/Q imbalances and compensate distortion received signal. As a result, we can obtain a performance similar performance when I/Q imbalances is not existed. Also, if proper detection methods are used, we get the effect of performance improvement, because of diversity gain what is happened due to combining I/Q imbalances with multi path fading channel.