• Journal of Communications and Networks
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• 제7권1호
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• pp.36-44
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• 2005

In this paper, we present a retransmission power adjustment (RPA) scheme for DS/SSMA ALOHA packet radio systems with packet combining. In the proposed RPA scheme, retransmission power is adjusted in such a way that the erroneously-received packet can be recovered with a minimized interference to other user packets. We analyze the performance of the system with the RPA by employing the equilibrium point analysis (EPA), and confirm that the results obtained from the EPA are very close to the simulation results in low power cases. Simulation results demonstrate that the RPA scheme brings forth performance gain in the throughput and the average delay while saving a significant amount of transmission power. We also investigate the stability of the system from the EPA results, and conclude that the system becomes stable as the offered load increases or the level of retransmission power decreases.

• 제어로봇시스템학회논문지
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• 제14권6호
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• pp.558-563
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• 2008

Optical axis misalignment, which represents the position deviation of the objective lens from the optical axis, is an inevitable assembly error in an optical pick-up. Since the laser power intensity varies with respect to the distance from the optical axis, the misalignment leads to variation of the laser spot power intensity, which is one of the critical factors increasing data bit-error-rate in optical disc drives. In this paper, an auto-adjustment scheme for optical axis alignment is proposed to eliminate the undesirable variation of the laser spot power intensity in optical disc drives. An envelope of the data RF signal is extracted and utilized to detect the optical axis misalignment. Then an adjustment input is added to the driving input of the tracking actuator to shift the objective lens to the optical axis. Finally, the feasibility is verified by experiments.

• ETRI Journal
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• 제32권5호
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• pp.823-826
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• 2010

This letter proposes a handover ranging power adjustment scheme to improve handover performance. Incorrect ranging power can degrade handover performance due to the increased handover latency; therefore, the proposed scheme exploits the uplink channel information to adjust the uplink handover ranging power. Simulation results demonstrate that the proposed scheme reduces call outage probability by 33% compared to that of the conventional scheme. It also improves the number of users who satisfy the system requirements for handover interruption time.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.348-350
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• 2008

A link voltage adjustment converter employing load power estimator for notebook computer adaptor is proposed. It is consisted of the boost converter as a power factor correction stage and the LLC resonant converter as a DC/DC conversion stage with a newly introduced link voltage adjustment method employing load power estimator, which helps to reduce the transformer size and peak of output voltage ripple, maintaining high efficiency over all the load condition. Experimental results with 85W converter are given to verify the validity of the proposed circuit.

• 한국생활과학회지
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• 제10권1호
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• pp.127-139
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• 2001

The purpose of this study was to find out the relationships among the elderly's self-esteem and life-adjustment according to decision-making power in their family. Interview survey was conducted and were selected. 296 over age 60 who lived in Jeonju. Frequencies, Percentiles, Pearson's correlation, t-test, ANOVA and Duncan's method were utilized for data analysis. The findings of this study were as follows ; 1) Decision-making power of the elderly in family had significant differences according to sex, coresiding with married children, and the sum of monthly personal expenses. 2) Elderly's self-esteem had significant differences according to sex, the present job, the situation of a spouse, and the sum of the monthly personal expenses. 3) Elderly's life-adjustment had significant difference according to residence type, the present job, the situation of a spouse, religion, education, and the sum of the monthly personal expenses. 4) Clothing and food in family had significant differences according to sex. 5) The elderly men's self-esteem had positive relationship with housing, sons and daughters guidance, grandchildren care, and family event and etc. But the elderly women's self-esteem had positive relationship with food, grandchildren care, and family event and etc. 6) The elderly men's life-adjustment had positive relationship with clothing, food, housing, family economy, sons and daughters guidance, grandchildren care, and family event and etc. But the elderly women's life-adjustment had positive relationship with food, housing, sons and daughters guidance, grandchildren care, and family event and etc.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.83-86
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• 1995

This paper proposes an auto-tuning method of feedforward signal in boiler control of thermal power plants by using the neural network. The neural network produces an optimal feedforward signal by tuning the weights of the network. The weights are adapted effectively by using the teaching signal of PI control output. The proposed method was evaluated based on a detailed simulator which expressed non-linear characteristics of the 600 MW actual thermal power plant at load chaning operations, showed effectiveness in the learning of the weights of the neural network, and gave an accurate control performance in the temperature control of the system. Through the evaluation, the proposed method was proved to be effectively applicable to the actual thermal plants as the automatic adjustment tool.

• 소음진동
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• 제6권6호
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• pp.701-708
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• 1996

Diesel power plants are frequently used as a power supplier on the island and the isolated places where electric power is required. The heat efficiency of the low speed 2 stroke diesel engines is higher than those of 4 stroke diesel engines or other heat engines and further its mobility and durability is also better than other engines. They can be also easily repaired and maintained. With these advantages, demand for the use of the low speed 2 stroke diesel engine as a power source is increasing. However, there are some disadvantages with these diesel engines such as the bigger vibrating excitation forces generated by higher combustion pressure in cylinder and by the inertia force of the reciprocating parts. Further, engine vibrations are transfered into their adjacent buildings and manufacturing factories and eventually produces local vibrations. In order to reduce X-mode vibration of engine body, several methods have been introduced in the recent researches. In this paper, accordingly, a new vibrationcontrol method applying a synchrophaser and a top bracing between two diesel engines is adopted in order to reduce these structural vibrations of diesel power plant. It was experimentally verified that the structural vibrations were greatly reduced by the phase adjustment for the 6th order X-mode vibration with the synchrophaser and the top bracing.

• 전기학회논문지
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• 제60권5호
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• pp.905-912
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• 2011

In this paper, the method on calculating benefits of combined heat and power is introduced for standard evaluation in electrical power system. This paper calculates benefits about new national viewpoint and viewpoint of independent power producers and assesses benefits of combined heat and power in Korea and In Seoul national capital area. Benefit costs are composed of avoid cost of centralized generation, line upgrading adjustment, loss adjustment and electrical power trade cost per year in earlier study, in addition trade cost of $CO_2$, construction cost of combined heat and power for accurate calculation. Benefit of combined heat and power is calculated by simulation results of real electrical power system.

• 동력기계공학회지
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• 제20권4호
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• pp.83-90
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• 2016

This study proposes a high-performance PI controller design method for an oil cooler system in conjunction with zero position adjustment and the characteristic parameters in its closed loop control system. The characteristic parameters included PI gains are decided by design specifications such as settling time and overshoot. The fine tuning on decided gains was performed by adjustment the zero position to get more desirable control performances. The simulations and experimental results show that the proposed PI controller design for an oil cooler system was possible to accomplish good control performances and to satisfy the design specifications.

• 한국간호교육학회지
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• 제18권2호
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• pp.312-322
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• 2012

Objectives: The purpose of this study was to investigate the factors related to adjustment of college for nursing students and to develop a collective model for successful prediction and concrete paths of the factors. Methods: Data collection was conducted from May 19th 2010 to Jun 4th 2010. Five hundred thirty-one questionnaires were used for data analysis after distributing 560 sheets to senior students in 8 different locations. Data was analyzed with SPSS 18.0 Win program and AMOS 18.0. Results: Mother attachment does not have a direct effect on adjustment to college life but does effect psychological well-being and coping, which indirect adjustment to college life. In addition, the more psychological well-being and coping usage frequency, and the less stress of clinical practice, the higher score of adjustment to college life. According to the results, explanatory power of the model for the college nursing students' adjustment was 62.0%. Conclusions: To improve adjustment to college life, it is recommended to have a direct method of developing psychological well-being and coping improvement program to improve mother attachment. The research is meaningful in a sense that it explains the cause and effect relationship between adjustment to college life and relevant variables to predict comprehensive dimensional explanation of adjustment of college life for nursing students.