• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.10-22
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• 2022

According to the Space Development Promotion Basic Plan, more than 110 satellites are expected to be deployed by 2031. Accordingly, the operation concept and technology for satellites constellation are required, compared to the existing few multi-satellite operations. It is essential to automate and optimize the mission operation system, for efficient operation of the satellite constellation, and preparations are urgently needed for the operation of satellite constellation in domestic as well. In this study, the development direction and strategy of the mission operation system applying automation and optimization for efficient operation of the satellite constellation are proposed. The framework for evaluating the automation level and priority of the mission operation system was developed, to identify the tasks to which automation should be applied preferentially.

• KIEAE Journal
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• v.12 no.5
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• pp.21-27
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• 2012

This study researches the level of satisfaction by apartment building management factor for different characteristics of apartment building residents and seeks to understand the relationship between socio-psychological properties and level of satisfaction. This study is based on a comparative method using a questionnaire by more than 682 housewives living in apartment complexes. Residents of apartment buildings are generally satisfied with housing and management of the apartment building that they are currently living in, but they wanted improvements such as programs that can support community living and increase participation of residents and operation of a web site. Furthermore, it was found that there was a significant difference in terms of operation management, such as sanitation control and processing for apartment buildings and community life management, according to the characteristics of the resident. Also, level of satisfaction in management was found to be influenced by pride and level of satisfaction in relationships with neighbors, showing that management of apartment buildings can have a positive impact on the socio-psychological properties of the residents.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1291-1298
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• 1998

In this paper, a simple algorithm for detection of timing error of a synchronous, band-limited, multi-level data stream is proposed. The proposed algorithm can be applied to multi-level PAM, M-ary PSK, or M-ary QAM. The proposed algorithm for M-ary PSK requires only two samples per symbol for its operation, and it is based on the concept of transition logic table and transition level table. In orer to prove the steady-state operation of the proposed algorithm, its performance is evaluated and compared to BECM by Monte Carlo simulation method under Gaussian noise and fading noise channel environments. The comparison results confirm that the perforance of proposed algorithm is superior to that of BECM in jitter characteristics.

• Nuclear Engineering and Technology
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• v.26 no.3
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• pp.420-424
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• 1994

This paper presents an improved water level control scheme for Pressurized Water Reactor(PWR) Steam Generator(S/G) at the low power operation and transient states. To reduce fluctuations of the water level by the swell and shrink phenomena, the scheme adds feedforward terms considering S/G pressure and the feedwater temperature into the conventional proportional-integral feedback controller. The simulation results using the Compact Nuclear Simulator show that smaller level errors and much faster settling time than those of the conventional scheme can be obtained. The proposed algorithm is easily implementable and has a potential for the real applications.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.4
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• pp.161-169
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• 2003

The applications of SRM(Switched Reluctance motor) are dramatically increasing due to a simple mechanical structure, a high efficiency and a high speed drive characteristics. Energy recovery in the regenerative region is very important when SRM is used in traction drive. This is to reduce energy loss during mechanical braking and/or to have a high efficiency drive. To control excitation voltage during motoring and regenerating voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper suggests multi-level inverter which is useful for motoring and regenerative operation. The proposed method is verified through simulations and experiments.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.4
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• pp.161-161
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• 2003

The applications of SRM(Switched Reluctance motor) are dramatically increasing due to a simple mechanical structure, a high efficiency and a high speed drive characteristics. Energy recovery in the regenerative region is very important when SRM is used in traction drive. This is to reduce energy loss during mechanical braking and/or to have a high efficiency drive. To control excitation voltage during motoring and regenerating voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper suggests multi-level inverter which is useful for motoring and regenerative operation. The proposed method is verified through simulations and experiments.

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.269-276
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• 2006

Running tests on roads were conducted to clarify the influences of road infrastructure, traffic condition and vehicle's emission level to the amount of emission at local roadsides, and to reveal the operation patterns which can reduce the emission peaks. NOx emission peaks of two light duty freight diesel vehicles which have different emission levels were evaluated by using an on-board measurement system. Tests were carried out with various payload conditions and road conditions. As a result many NOx emission peaks were observed when the vehicles were starting or accelerating at intersections. The test vehicle which has higher emission level caused higher frequency and level of NOx emission peaks. Shifting up at lower engine speed in combination with lower acceleration brought out not only reduction of NOx emission peaks level but also of $CO_2$ mass emission.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.1 s.12
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• pp.33-40
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• 2004

The objective of this study is to develop single dam operation models for flood control using Fuzzy control technique, which can improve flood controllability. We set control rules by water level and inflow, and developed three models Fuzzy I, II, III according to rule to decide outflow. Fuzzy I model consists of six rules considering only flood control and Fuzzy II model considers the effect of water use by increasing water level at the end of flood control period as well as flood control during the same period. Finally, Fuzzy m is an adaptive model designed to perform multipurpose dam operation for both flood control and water use simultaneously based on a control rules.

• Journal of Chest Surgery
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• v.25 no.11
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• pp.1185-1191
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• 1992

Cell mediated immunity is depressed following surgical procedure and the degree of immunosuppression is directly related to the magintude of the procedure, blood transfusion, and length of operation. So we would expect cardiac operations to be highly immunosuppressive, although little is konwn about their immunosuppressive effect. The nearly complete consumption of complement factors and decreased levels of IgM and IgG resulting in an impaired opsonizing capacity. Additionally, peripheral blood mononuclear cell counts including T-and B-lymphocytes and T-cell subsets are reduced. Depression of cell-mediated immunity following open-heart surgery is potentially detrimental because it could increase the susceptability of patients to viral and bacterial infection. We reviewed 20 patients after cardiac operation to search for changes in peripheral blood lymphocyte subsets. Lymphocyte subsets were measured by flow cytometer and the preoperative values of lymphocyte subsets were compared with those from the first, fourth, and seventh days after operation. After cardiac operation, total mumbers of T lymphocyte was severely depressed on the first postoperative day and returned to the preoperative level by the seventh day after operation. CD3, CD4, and CD8 lymphocytes were decreased on the first postoperative day and returned to the preoperative level by the seventh day also. There was four cases of wound infection and these patients had increased CD4 lympocyte and more decreased CD19 lymphocyte compared with the non-infected group. It is concluded from these data that cell-mediated immunity is significantly depressed for at least one week following open-heart surgery and this result was closely related to the postoperative infection.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.157-158
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• 2005

Superconducting fault currents(SFCLs) are expected to improve not only reliability but also stability of real power systems. The analysis on the single line-to-ground fault of the integrated three phase flux-lock type SFCL, which consists of three flux-lock reactor wound on an iron core in each single phase and three YBCO thin films, was investigated in current limiting operation characteristics. We compared 21turn numbers with 42turn numbers according to wound turn numbers each the coil 2 under the additive polarity winding operation between coil 1 and coil 2. The three phase flux-lock type SFCL using an iron core differently operates general three phase resistive SFCLs. When a single line-to-ground fault occurred, the SFCL's three units were quenched after fault onset. We confirmed effective current limiting operation characteristics with adjustable inductance level.