• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.97-102
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• 2003

An experimental study is conducted to investigate the effects of duct corrugation angle on heat/mass transfer characteristics in wavy ducts by using a naphthalene sublimation technique. The corrugation angles of the wavy ducts are $145^{\circ}$ , $130^{\circ}$ and $115^{\circ}$ . and the Reynolds numbers based on the duct hydraulic diameter vary from 300 to 3,000. At the low $Re(Re{\leq}1000)$, high heat/mass transfer regions are formed by the secondary vortex flows called Taylor-Gortler vortices on both pressure-side and suction-side walls. At the high $Re(Re{\geq}1000)$, the effects of these secondary flows are vanished. As corrugation angle decreases, the local peak Sh induced by Taylor-Gertler vortices are increased and average Sh also enhanced. More pumping power (pressure loss) is required with the smaller corrugation angle due to the stronger secondary vortex flows.

• 태양에너지
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• 제18권3호
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• pp.95-105
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• 1998

In this study, basic design data which were required for development of highly efficient ice storage system with low temperature latent heat were experimentally obtained. The ice storage system considered in this study was the one that has been widly used in the developed country and called the ice-on-coil type. Using the system, the ice storage performance for various design parameters which were the flow direction and the inlet temperature of the secondary fluid was tested. In addition, the timewise variation of the interface profiles between the solid and the liquid were visualized, and the heat transfer characteristics of the Phase Change Material(PCM) in the ice storage tank were Investigated. During the freezing processes in the ice storage tank with several vertical tubes, decrease of the heat transfer area and the heat resistance of the ice layer made the increasing rate of ice packing factor(IPF) less. The total freezing energy for the upward flow of the secondary fluid was higher than that for the downward flow. The average ice storage efficiency for the upward flow of the secondary fluid was higher than that for the downward flow.

• Clinical and Experimental Reproductive Medicine
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• 제51권1호
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• pp.63-68
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• 2024

Objective: This study was conducted to investigate the impact of previous delivery mode on pregnancy outcomes in patients with secondary infertility after frozen-thawed embryo transfer. Methods: This prospective observational study included 140 patients experiencing secondary infertility. Of these, 70 patients had a previous cesarean delivery (CD), while the remaining 70 patients had a previous normal vaginal delivery (NVD). The primary outcome was the implantation rate. The secondary outcomes included rates of clinical pregnancy, chemical pregnancy, miscarriage, and ectopic pregnancy. Results: The comparison of all fertility outcomes between the two groups revealed no statistically significant differences. The implantation rate was 40.4% in the CD group and 41.7% in the NVD group (p=0.842). The clinical pregnancy rate was 50% in the CD group and 49.3% in the NVD group (p=0.932), while the chemical pregnancy rate was 14.6% in the CD group and 19% in the NVD group (p=0.591). The miscarriage rates in the CD and NVD groups were 20% and 17.6%, respectively (p=0.803). One case of tubal ectopic pregnancy occurred in the NVD group (1.4%). Conclusion: The mode of prior delivery did not significantly impact pregnancy outcomes following frozen-thawed embryo transfer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2448-2453
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• 2008

The present study numerically investigates the flow and heat transfer characteristics of rib-induced secondary flow in a cooling channel with staggered V-shaped ribs, extruded on both walls. The rib-height-to-hydraulic diameter ration (h/$D_h$) is 0.17; the rib pitch-to-height ratio (p/h) equals 2.8; the Reynolds number is 50,000. Shear stress transport (SST) turbulence model is used as a turbulence closure. The present results are compared with those for a continuous V-shaped rib. Computational results show that, for average heat transfer rate the staggered V-shaped rib gives about 2.5 times higher values than the continuous V-shaped rib, while, for the streamwise pressure drop the former gives about 5 times higher values than the latter. Consequently, for the thermal performances, based on the equal pumping power condition, the staggered one gives about 2 times higher values than the continuous one. Also, for the staggered V-shaped rib, complex secondary flow patterns are generated in the duct due to the snaking flow in the streamwise direction, and more uniform heat transfer distributions are obtained.

• Archives of Plastic Surgery
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• 제49권4호
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• pp.527-530
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• 2022

Lupus panniculitis (LP) often presents with tender nodules and intermittent ulcers that then heal with scarring and lipoatrophy. The current mainstay of treatment is medical treatment. Research regarding the treatment of lipoatrophy from LP with autologous fat grafting is limited. We would like to share our experience in this rare case, which was treated with autologous fat transfer. A 48-year-old female presented with erythematous plaque, tender nodules, and ulcers following by a depression of the lesion at the left temporal area. The patient also had indurated erythematous plaque at her left cheek. Both lesions were aggravated by sunlight exposure. After several investigations, she was diagnosed as LP with secondary lipoatrophy and tumid lupus erythematosus at her left temporal and left cheek, respectively. She received antimalarial drug and topical steroids. The patient underwent two sessions of autologous fat transfer. She was satisfied with the volume and contour improvement in the scar following the injection of 8 and 3.7 mL of fat. Furthermore, the patient reported the remission of tender nodules and ulcers since the first fat graft injection. In conclusion, the autologous fat transfer is a simple and effective treatment for lipoatrophy and scar secondary to LP with promising results.

• Journal of Power Electronics
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• 제18권4호
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• pp.1190-1200
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• 2018

A current sourced bi-directional wireless power transfer (WPT) system is proposed to solve the problems that exist in the bi-directional WPT for vehicle-to-grid (V2G) systems. These problems include the fact that these systems are not safe enough, the output power is limited and the control methods are complicated. Firstly, the proposed system adopts two different compensation and control methods on both the primary and secondary sides. Secondly, based on an AC impedance analysis, the working principle is analyzed and the parameter configuration method with frequency stability is given. In order to output a constant voltage, a bi-directional DC/DC circuit and a controllable rectifier bridge are adopted, which are based on the "constant primary current, constant secondary voltage" control strategy. Finally, the effectiveness and feasibility of the proposed methods are verified by experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1006-1007
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• 2015

Recent improvement in semiconductor technology make efficient switching possible at higher frequencies, which benefits the application of wireless inductive energy transfer. However, a higher frequency does not alter the magnetic coupling between energy transmitter and receiver. Due to the still weak magnetic coupling between transmitting and receiving sides that are separated by a substantial air gap, energy circulates in the primary transmitting side without being transferred to the secondary receiving side. This paper proposes an analysis on the system efficiency to determine the optimal impedance requirement for coils, rectifier and DC-DC Converter. A novel Boost DC-DC Converter is designed to provide the optimal impedance matching in WPT(Wireless Power Transfer) system for various loads.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.267-271
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• 1996

In this study, performance improvement of the inverse modeling as the on-line control method for the estimation, control experiment is performed. As the modeling errors is occurred in duct system arbitrarily, a case using the filtered-x LMS algorithm only as the control method, a case using tile inverse modeling method only and a case using the inverse modeling with the adaptive line enhancer are compared. The estimation errors between real secondary path transfer functions and the estimated and the control performances of primary noises with these estimated transfer functions are compared.

• 전기학회논문지P
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• 제63권4호
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• pp.260-265
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• 2014

Recently, many active noise control (ANC) systems, which employ the adaptive filter controlling method, have been reported for eliminating unwanted noise. ANC systems based on the filtered-X least mean square (FXLMS) algorithm have a problem with compensating the acoustic feedback of secondary route. It is difficult to apply the real time, because transfer function of secondary route must be measured by off-line method to solve this problem. In this paper, we propose the ANC system that applies a correlation LMS(CLMS) algorithm for improving a problem of transfer function measurement. The proposed algorithm is based on input of road noise. The proposed ANC systems have an advantage of real-time process without degradation of performance, although there are many calculation compared with FXLMS algorithm.

• Nuclear Engineering and Technology
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• 제36권2호
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• pp.153-164
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• 2004

A computational fluid dynamics (CFD) analysis has been performed to investigate the turbulent flow and heat transfer in a triangular rod bundle with pitch-to-diameter ratios (P/D) of 1.06 and 1.12. Anisotropic turbulence models predicted the turbulence-driven secondary flow in a triangular subchannel and the distributions of the time mean velocity and temperature, showing a significantly improved agreement with the measurements from the linear standard $k-{\epsilon}$ model. The anisotropic turbulence models predicted the turbulence structure for a rod bundle with a large P/D fairly well, but could not predict the very high turbulent intensity of the azimuthal velocity observed in the narrow flow region (gap) for a rod bundle with a small P/D.