• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.5
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• pp.394-400
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• 2013

Underwater radiated noise is one of the important performances related to stealth of the naval vessel. However, the evaluation can't be performed frequently due to the cost. Therefore, the estimation method of the underwater radiated noise with average hull vibration is suggested in this paper assuming that the hull of the ship is infinite plate which consists of various unit plates. Through the experiment, the estimated noise is verified from the comparison to the measured data. In addition the difference of underwater radiated noise according to the operating equipments is estimated with measured vibration velocity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9C
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• pp.1252-1257
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• 2004

This paper presents a decentralized LQ-PID controller for the TITO system which satisfies the performance of good command following, disturbance rejection, and sensor noise reduction that is design specifications in the frequency domain The procedure is developed by establishing the relationship between the closed-loop state equations including the decentralized PID tuning parameters and the closed-loop state equations of LQR and by selecting the weighting factors Q and R of the cost function in order to satisfy the design specifications in the frequency domain.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.6
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• pp.269-277
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• 2005

In this paper, designs of an Interior Permanent Magnet Synchronous Motor (IPMSM) and its motor driver for 42V automotive air condition system are introduced. The characteristics of the IPMSM are predicted by using d-q equivalent circuit having the parameters, such as current phase angle, d-q axis inductances, core loss resistance, etc. The experimental and analysis results of the prototype are compared to show validity of the analysis method, and to give analyzed characteristics in detail. As the result, an improved IPMSM is designed to widen the operating speed limit of prototype; a cost effective AC drive are considered at the same time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.2
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• pp.133-136
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• 2010

Laser direct patterning is one of new methods which are able to replace a conventional photolithography. In order reduce the fabrication cost and to improve the luminous efficiency of AC plasma display panels (PDPs), in this experiment, a Q-switched Nd:$YVO_4$ laser was used to fabricate T-shaped indium tin oxide (ITO) display electrodes. For the laser beam scanning speed from 100 mm/sec to 800 mm/sec, T-shaped ITO patterns were clearly obtained and investigated. The experimental results showed that the optimized T-shaped ITO electrode was obtained when the lasers scanning speed was 300 mm/s.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.1
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• pp.19-29
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• 2021

In the Port Logistics system, Container Stowage planning is an important issue for cost-effective efficiency improvements. At present, Planners are mainly carrying out Stowage planning by manual or semi-automatically. However, as the trend of super-large container ships continues, it is difficult to calculate an efficient Stowage plan with manpower. With the recent rapid development of artificial intelligence-related technologies, many studies have been conducted to apply enhanced learning to optimization problems. Accordingly, in this paper, we intend to develop and present a Deep Q-Learning Network model for the Master Stowage planning of Container ships.

• Journal of Hospice and Palliative Care
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• v.13 no.2
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• pp.81-88
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• 2010

Purpose: This study was conducted to study the attitude of Korean lawyers toward withdrawal of life sustaining treatment, and compare and analyze different types of their attitudes. Methods: Research design of this project was Q methodology approach. The study population was 24 lawyers, aged from 32 to 69 years. Q sample to investigate the attitude of the lawyers toward withdrawal of life sustaining treatment included 34 statements obtained from literatures, TV debate, and depth interviews of 5 lawyers among the lawyers included. After listening to the purpose and method of the study, the 24 lawyers agreed to fill out a survey asking sociodemographic information, and the information was distributed in 9 scale Q-sample. Results: The collected data were processed through QUANL PC program and sorted into 5 types as follows: The first type was 'Choosing to withdraw life sustaining treatment', the second 'Withholding life sustaining treatment' regardless of the cost, the third is neutral type that claims that humans have the right to decide the death and life, and demands the proper legalization to protect such rights, the fourth type agrees to withdrawal of life sustaining treatment, nevertheless, admits that one has a rigt to withhold one's own life treatment, categorized as self contradiction type. The fifth type believed that 'Life and death are providential' with the faith, therefore, such authority to decide life and death belongs to God, but not human beings. Conclusion: In conclusion, the lawyer's attitudes toward withdrawal of life sustaining treatment were grouped into five different types as follows: 'Choosing to withdraw life sustaining treatment', 'Withholding life sustaining treatment', 'Demanding legalization', 'Self contradiction type', and 'Life and death are providential'.

• Journal of the Korea Convergence Society
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• v.11 no.2
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• pp.323-330
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• 2020

This study is to identify the types and meaning of 'Good Leisure' that married immigrant women perceived. 32 Q samples were extracted from the interviews and questions and 40 immigrant women were selected as P samples. The conclusion are as follows; First, the types of 'Good Leisure' were classified as 4 types. Second, the type 1, 'Psychological Stability Pursue Type' recognizes 'Good Leisure' when they feel comfort and relaxed through activities. The type 2, 'Emotional Stability and Self-development Type' recognized 'Good Leisure' when they are pleased, or engaged in self-development activities. The type 3, 'Practical Use Pursue and Information Acquisition Type', recognizes 'Good Leisure' when they learn things necessary for living with less cost, and type 4, 'Acculturation and Exchange Type' recognizes 'Good Leisure' when they learn Korean culture or interact with Korean people. Third, regardless of each type, married immigrant women perceived in having a good time with people as 'Good Leisure'.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.5
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• pp.484-491
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• 2017

Recent research has shown that quadrupole noise has a significant influence on the overall characteristics of flow-induced noise and on the performance of underwater appendages such as sonar domes. However, advanced research generally uses the Ffowcs Williams-Hawkings analogy without considering the quadrupole source to reduce computational cost. In this study, flow-induced noise is predicted by using an LES turbulence model and a developed formulation, called the formulation Q1As method to properly take into account the quadrupole source. The noise around a circular cylinder in an underwater environment is examined for two cases with different velocities. The results from the method are compared to those obtained from the experiments and the permeable FW-H method. The results are in good agreement with the experimental data, with a difference of less than 1 dB, which indicates that the formulation Q1As method is suitable for use in predicting quadrupole noise around underwater appendages.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.3
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• pp.649-664
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• 2015

Recently, the risk of security incidents has been increased due to change of IT environment and development of new hacking methods. Event study methodology that measures the effect of a specific security incident on the stock price is widely adopted to analyze the damage cost of security incidents on market value. However, analysis of company's temporary stock price change is limited to immediate practical implication, and reputation loss should be considered as a collateral damage caused by security incidents. We analyzed 52 security incidents of listed Korean companies in the last decade; by refining the criteria presented by Tobin's q, we quantitatively showed that the companies has significantly higher reputation loss due to security loss than the other companies. Our research findings can be used in order that the companies can efficiently allocate its resource and investment for information security.

• Journal of Communications and Networks
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• v.15 no.4
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• pp.383-397
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• 2013

In this paper, the sensitivity of massive antenna arrays and digital beamforming to radio frequency (RF) chain in-phase quadrature-phase (I/Q) imbalance is studied and analyzed. The analysis shows that massive antenna arrays are increasingly sensitive to such RF chain imperfections, corrupting heavily the radiation pattern and beamforming capabilities. Motivated by this, novel RF-aware digital beamforming methods are then developed for automatically suppressing the unwanted effects of the RF I/Q imbalance without separate calibration loops in all individual receiver branches. More specifically, the paper covers closed-form analysis for signal processing properties as well as the associated radiation and beamforming properties of massive antenna arrays under both systematic and random RF I/Q imbalances. All analysis and derivations in this paper assume ideal signals to be circular. The well-known minimum variance distortionless response (MVDR) beamformer and a widely-linear (WL) extension of it, called WL-MVDR, are analyzed in detail from the RF imperfection perspective, in terms of interference attenuation and beamsteering. The optimum RF-aware WL-MVDR beamforming solution is formulated and shown to efficiently suppress the RF imperfections. Based on the obtained results, the developed solutions and in particular the RF-aware WL-MVDR method can provide efficient beamsteering and interference suppressing characteristics, despite of the imperfections in the RF circuits. This is seen critical especially in the massive antenna array context where the cost-efficiency of individual RF chains is emphasized.