• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2288-2296
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• 2015

This paper proposes a novel systematic modeling approach for an integrated single-stage power converter in order to predict its dynamic characteristics. The basic strategy of the proposed modeling is substituting the internal converters with an equivalent current source, and then deriving the dynamic equations under a standalone operation using the state-space averaging technique. The proposed approach provides an intuitive modeling solution and simplified mathematical process with accurate dynamic prediction. The simulation and experimental results by using an integrated boost-flyback converter prototype provide verification consistent with theoretical expectations.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.205-208
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• 2020

This paper examines the approach, enabled by using SiC power devices, to unify the inverter design for central air conditioning (CAC) system for both single- and 3-phase input, and reduce the PFC inductor size to be PCB-mountable. By using SiC-instead of Si-diode in PFC stage, it is possible to increase the switching frequency from 16kHz to 60kHz to reduce the required PFC inductance from 0.93mH to 0.25mH, thus enable PCB-mounting of inductor. With the next step of using 1200V SiC MOSFET instead of Si-IGBT, the DC link voltage can be boosted from 311Vdc to 550Vdc in PFC stage, allowing the inverter and compressor used in 3-phase input CAC be used for single-phase input as well. Furthermore, using SiC MOSFET in inverter stage can further reduce total loss system total loss to 200.8 W. Simulation and experimental results are presented in the paper.

• Journal of Chest Surgery
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• v.55 no.1
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• pp.37-43
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• 2022

Background: The surgical strategy for single-stage resection of primary colorectal cancer (CRC) and synchronous pulmonary metastases remains a matter of debate. Methods: Perioperative data of patients who underwent single-stage resection of primary CRC and synchronous pulmonary metastases were compared to those of patients who underwent 2-stage resections. The demographic data, number of metastases, type of pulmonary and colorectal resections, operation time, blood loss, postoperative complications, morbidities, mortality, medical costs, and length of hospital stay were analyzed. Results: Twenty-two patients underwent single-stage resection of primary CRC and pulmonary metastases, while 27 patients underwent 2-stage resection. Tumor size and the number of pulmonary metastases were not significantly different between the 2 groups. The extent of pulmonary metastasectomy and abdominal procedures were similar in both groups, as was the thoracic surgical approach (video-assisted thoracic surgery vs. thoracotomy). However, open laparotomy was performed more frequently in the 2-stage group than in the single-stage group (p=0.045), which also had a longer total anesthetic time (p=0.013). The operation time, medical costs, estimated blood loss, complication rates, and severity were similar in both groups, but the length of hospital stay was shorter in the single-stage group (p<0.001). Conclusion: Single-stage colorectal and pulmonary resection shortened the overall hospital stay, with no significant changes in operation time, medical costs, hospital mortality, and morbidity. Therefore, single-stage resection could be a good surgical strategy in selected patients.

• Journal of Korean Society for Quality Management
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• v.18 no.1
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• pp.65-76
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• 1990

A lot-sizing model for multi-stage MRP systems is proposed, in which known demands must be satisfied. In this model, an approach with considerations of initial inventory and limited production capacity is involved. Most of the studies on the lot-sizing techniques for multi-stage material requirement planning systems have been focused upon two basic approaches. One approach is to develope an algorithm yielding an optimal solution. Due to the computational complexity and sensitivity of the optimal solution to the problem of lot sizing, heuristic approaches are often employed. In this paper, the heuristic approach is used by sequential application of a single-stage algorithm with a set of modified cost by the concept of multi-echelon costs. The proposed method is compared with an lot-sizing method(Florian-Klein Model) to prove its effectiveness by numerical examples.

• Archives of Plastic Surgery
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• v.47 no.5
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• pp.460-466
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• 2020

Background Sternoclavicular joint (SCJ) osteomyelitis is a rare pathology requiring urgent intervention. Several operative approaches have been described with conflicting reports. Here, we present a multi-institutional study utilizing multiple surgical pathways for SCJ reconstruction. Methods A multi-institutional retrospective cohort study was conducted to identify patients who underwent surgical repair for sternoclavicular osteomyelitis between 2008 and 2019. Patients were stratified according to reconstruction approach: single-stage reconstruction with advancement flap and delayed-reconstruction with flap following initial debridement. Demographics, operative approach, type of reconstruction, and postoperative outcomes were analyzed. Results Thirty-two patients were identified. Mean patient age was 56.2±13.8 years and 68.8% were male. The average body mass index (BMI) was 30.0±8.8 kg/㎡. The most common infection etiologies were intravenous drug use and bacteremia (both 25%). Fourteen patients (43.8%) underwent one-stage reconstruction and 18 (56.2%) underwent delayed two-staged reconstruction. Both single and delayed-stage groups had comparable rates of reinfection (7.1% vs. 11.1%, respectively), surgical site complications (21.4% vs. 27.8%), readmissions (7.1% vs. 16.6%), and reoperations (7.1% vs. 5.6%; all P>0.05). The single-stage reconstruction group had a significantly lower BMI (26.2±5.7 kg/㎡ vs. 32.9±9.1 kg/㎡; P<0.05) and trended towards shorter hospital length of stay (11.3 days vs. 17.9 days; P=0.01). Conclusions Both single and delayed-stage approaches are appropriate methods with comparable outcomes for reconstruction for SCJ osteomyelitis. When clinically indicated, a single-stage reconstruction approach may be preferable in order to avoid a second operation as associated with the delayed phase, and possibly shortening total hospital length of stay.

• Journal of the Korean housing association
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• v.14 no.4
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• pp.39-48
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• 2003

The purpose of this study was to analyze the changes of floor plans in the entry and transfer spaces of single detached houses. The sample size was 185 households in Chungju, Jechon and Wonju Which are small cities in the central region of Korea. The results of the study are as follows: Firstly, the approach and transfer spaces show various changes and those are important factors which symbolize the housing plane typology transformations of the research areas. Secondly, the approach direction to the indoor space was more adopted a front approach in 1960's and 1970's, it is a side approach in 1980's, and a back side approach in 1990's. Thirdly, as the stage of the transfer space increased, the detached house planes have been changing to the direction, the depth of space comes to be deep, spatial function to be fixed, and privacy of bed rooms to be increased.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.308-311
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• 2004

A novel single-stage power factor corrected (PFC) drive for switched reluctance motor (SRM) is presented to achieve sinusoidal, near unity power factor input current. The proposed PFC SRM drive has no additional active switch. And a single-stage approach, which combines a DC link capacitor used as do source and a drive used for driving the motor into one power stage, has a simple structure and low cost. The characteristics and validity of the proposed circuit will be discussed in depth through the experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.519-526
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• 2003

A singl-phase power factor corrected converter for switched reluctance motor hive is presented to achieve a sinusoidal and new unity power factor input currents. Because it combines a power factor corrected converter and a conventional asymmetric SRM driver into one power stage, the configuration has a simple structure resulted in low cost. A prototype to drive 6/6 poles SRM employing a parking magnet Is designed to evaluate the proposed topology. The characteristics and operational mode will be discussed in depth, and the validity of proposed driver will be verified through the experimental results.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.979-981
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• 2003

A novel single-stage power factor corrected (PFC) drive for switched reluctance motor (SRM) is presented to achieve sinusoidal, near unity power factor input current. The proposed PFC SRM drive has no additional active switch. And a single-stage approach, which combines a DC link capacitor used as do source and a drive used for driving the motor into one power stage, has a simple structure and low cost. The characteristics and validity of the proposed circuit will be discussed in depth through the experimental results.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.235-238
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• 2001

A novel single-stage power factor corrected (PFC) drive for switched reluctance motor (SRM) is presented to achieve sinusoidal, near unity power factor input current. The proposed PFC SRM drive has no additional active switch. And a single-stage approach, which combines a DC link capacitor used as dc source and a drive used for driving the motor into one power stage, has a simple structure and low cost. The characteristics and validity of the proposed circuit will be discussed in depth through the experimental results.