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Hieu, Pham-Duong,Chung, Jin-Hyung,Yim, Sung-Bin,Hong, Ki-Seok Korean Academy of Periodontology 2010 Journal of Periodontal & Implant Science Vol.40 No.1
Purpose: The performance of implant surgery in the posterior maxilla often poses a challenge due to insufficient available bone. Sinus floor elevation was developed to increase the needed vertical height to overcome this problem. However, grafting materials used for the sinus lift technique eventually show resorption. The present study radiographically compared and evaluated the changes in height of the grafting materials after carrying out maxillary sinus elevation with a window opening procedure. This study also evaluated the difference between two xenogenic bone materials when being used for the sinus lifting procedure. Methods: Twenty-one patients were recruited for this study and underwent a sinus lift procedure. All sites were treated with either bovine bone (Bio-$Oss^{(R)}$) with platelet-rich plasma (PRP) or bovine bone (OCS-$B^{(R)}$)/PRP. A total of 69 implants were placed equally 6-8 months after the sinus lift. All sites were clinically and radiographically evaluated right after the implant surgery, 7-12 months, 13-24 months, and 25-48 months after their prosthetic loading. Results: Changes of implant length/bone length with time showed a statistically significant decreasing tendency (P<0.05). There was no significant change in the Bio-$Oss^{(R)}$ group (P>0.05). In contrast, the OCS-$B^{(R)}$ group showed a significant decrease with time (P<0.05). However, no significant difference was observed between the two groups (P>0.05). Conclusions: The results showed that there was significant reduction in comparison with data right after placement, after 7 to 12 months, 13 to 24 months, and over 25 months; however, reduction rates between each period have shown to be without significance. No significant difference in height change was observed between the Bio-$Oss^{(R)}$ and the OCS-$B^{(R)}$ groups.
High Speed Segmental Stator Type 4/3 SRM: Design, Analysis, and Experimental Verification
Hieu, Pham Trung,Lee, Dong-Hee,Ahn, Jin-Woo The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5
This paper presents a design of a 2-phase segmental stator type 4/3 switched reluctance motor (SRM) for air-blower application. The air-blower requires only one direction rotation, high rotor speed without torque dead-zone. In order to satisfy the requirements of the load, the rotor of the 4/3 proposed SRM is designed with wider rotor pole arc and non-uniform air-gap is applied on the rotor shape. With a special rotor structure, the motor generates a wider positive torque region and has no torque dead-zone. The stator of the proposed SRM is constructed with two segmental C-cores, and there are no magnetic connections between 2 C-cores. The flux follows in a short closed loop in each C-core and has no reversal flux in the stator. The static and dynamic characteristics of the proposed motor are analyzed by the finite element method (FEA) and Matlab-Simulink, respectively. In order to verify the design, a prototype of the proposed motor has manufactured for laboratory test. The performance of the proposed motor is verified by the simulation and experimental results.
Design of a High Speed 4/2 Switched Reluctance Motor for Blender Application
Pham Trung Hieu(팜쭝희웨),Dong-Hee Lee(이동희),Jin-Woo Ahn(안진우) 대한전기학회 2017 대한전기학회 학술대회 논문집 Vol.2017 No.4
This paper presents the design of a high speed 4/2 switched reluctance motor (SRM) for blender application. The proposed SRM is designed to replace a universal motor that equipped for the blender. The universal motor has low efficiency and unpleasant odor when operating. The blender requires a high speed motor drive with self-start ability. In order to overcome torque dead-zone that exists in single- and 2-phase SRM, stepper rotor with wider rotor pole arc is considered. The rated speed is up to 18.000 rpm and 40.000 rpm at no-load. In order to verify the design, a prototype of the proposed SRM is manufactured for laboratory test.
Design and Operation Characteristics of Novel 2-Phase 6/5 Switched Reluctance Motor
Hieu, Pham Trung,Lee, Dong-Hee,Ahn, Jin-Woo The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.6
This paper presents a design of novel 2-phase 6/5 switched reluctance motor (SRM) for an air-blower application. This type of motor is suitable for the applications that require high speed and only one directional rotation as air-blower. The desired air-blower is unidirectional application, and requires a wide positive torque region without torque dead-zone. In order to get a wide positive torque region without torque dead-zone during phase commutation, asymmetric inductance characteristic with non-uniform air-gap is considered. The proposed motor can be operated at any rotor position. The proposed 6/5 SRM uses short flux path technique that achieved by means of winding configuration and lamination geometry. The purpose of short flux path is to reduce the core loss and the absorption MMF in the stator. The proposed 2-phase 6/5 SRM is verified by finite element method (FEM) analysis and Matlab-Simulink. In order to verify the design, a prototype of the proposed motor was manufactured for practical system.
Pham-Duong Hieu,Jin-Hyung Chung,Sung-Bin Yim,홍기석 대한치주과학회 2010 Journal of Periodontal & Implant Science Vol.40 No.1
Purpose: The performance of implant surgery in the posterior maxilla often poses a challenge due to insufficient available bone. Sinus floor elevation was developed to increase the needed vertical height to overcome this problem. However, grafting materials used for the sinus lift technique eventually show resorption. The present study radiographically compared and evaluated the changes in height of the grafting materials after carrying out maxillary sinus elevation with a window opening procedure. This study also evaluated the difference between two xenogenic bone materials when being used for the sinus lifting procedure. Methods: Twenty-one patients were recruited for this study and underwent a sinus lift procedure. All sites were treated with either bovine bone (Bio-Oss®) with platelet-rich plasma (PRP) or bovine bone (OCS-B®)/PRP. A total of 69 implants were placed equally 6-8 months after the sinus lift. All sites were clinically and radiographically evaluated right after the implant surgery, 7-12 months, 13-24 months, and 25-48 months after their prosthetic loading. Results: Changes of implant length/bone length with time showed a statistically significant decreasing tendency (P < 0.05). There was no significant change in the Bio-Oss® group (P > 0.05). In contrast, the OCS-B® group showed a significant decrease with time (P < 0.05). However, no significant difference was observed between the two groups (P > 0.05). Conclusions: The results showed that there was significant reduction in comparison with data right after placement, after 7 to 12 months, 13 to 24 months, and over 25 months; however, reduction rates between each period have shown to be without significance. No significant difference in height change was observed between the Bio-Oss® and the OCS-B® groups.
Design of 2-Phase 4/2 SRM For Low Torque Ripple
Pham Trung Hieu,Dong-Hee Lee,Jin-Woo Ahn 대한전기학회 2012 대한전기학회 학술대회 논문집 Vol.2012 No.4
This paper presents a optimization design process of a 2-phase 4/2 SRM(Switched Reluctance Motor) for a high speed air-blower with low torque ripple. The desired air-blower is unidirectional application, and requires a wide positive torque region without torque dead-zone in the conventional 2-phase SRM. In order to get a wide positive torque region without torque dead-zone during phase commutation, asymmetric inductance characteristic with non-uniform air-gap is considered. For the flat-top torque with a low torque ripple with torque over-lap between phases, air-gap according to the rotor position is optimized. Based on the output torque analysis at each rotor position, the air-gap is modified to reduce torque ripple while rotating.