• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.17-24
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• 2000

• Clinics in Shoulder and Elbow
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• v.14 no.2
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• pp.253-261
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• 2011

Purpose: The purpose of the present article is to help orthopedic surgeons better understand the basic principles of unconstrained total shoulder arthroplasty, and to help them perform the best surgical technique for reconstruction. Materials and Methods: In this article, we reviewed in depth current biomechanics, indications & contraindications, surgical techniques, complications and outcomes of unconstrained total shoulder arthroplasty. Additionally, we discussed current issues relevant to total shoulder arthroplasty such as whether a keeled or a pegged glenoid should be used. Results and Conclusion: A thorough understanding of the biomechanics of total shoulder arthroplasty, and the technical details and problems in implantation, are critical to provide the best functional outcome and to avoid the risk of complications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.499-508
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• 2017

A new digital pre-distortion technique to linearize power amplifier (PA) is proposed for concurrent dual-band transmitters. In the conventional dual-band DPD techniques, two independent dual-feedback paths are required to compensate nonlinear cross-products between different bands as well as the nonlinear self-products of each band's own signal. However, it increases hardware complexity and expense. In this paper, we propose a new DPD method requiring only a single feedback path. In this new structure, the proposed technique first estimates the dual-band PA characteristics using the single feedback path. The DPD parameters are then extracted from the estimated PA characteristics. The DPD performance of the proposed method is validated through computer simulation. According to the results, the proposed technique can achieve comparable performance to the conventional two feedback DPD with significantly reduced hardware complexity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.681-684
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• 2015

Power amplifier is an essential component for transmitting signals to a remote receiver in wireless communication systems. Power amplifier is a non-linear device in general, and the nonlinear distortion becomes severer as the output power increases. The nonlinearity results in spectral regrowth, which leads to adjacent channel interference, and decreases the transmit signal quality. To linearize power amplifiers, many techniques have been developed so far. Among the techniques, digital pre-distortion is known as the most cost and performance effective technique. However, the linearization performance falls down abruptly when the power amplifier operates in its saturation region. This is because of the severe nonlinearity. To relieve this problem, this paper proposes a new adaptive predistortion technique. The proposed technique controls the adaptive algorithm based on the power amplifier input level. Specifically, for small signals, the adaptive predistortion algorithm works normally. On the contrary, for large signals, the adaptive algorithm stops until small signals occur again. By doing this, wrong coefficient update by severe nonlinearity can be avoided. Computer simulation results show that the proposed method can improve the linearization performance compared with the conventional digital predistortion algorithms.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.3
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• pp.221-225
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• 2013

Proper management of provisional prosthesis is key to success in prosthodontics. Provisional restoration on maxillary anterior missing area frequently come across a incident of falling off especially in patients with long span pontics and oval arch shape. This is because maxillary anterior teeth are more exposed to horizontal force than the posterior teeth and additional anterior cantilever effect will negatively affect to the retention of provisional prosthesis. Beside that maxillary anterior provisional prosthesis should provide proper incisal guidance during the mandibular functional movements. However occlusal contacts on the prosthesis in maximum intercuspal position are located on opposite side of fulcrum line of prosthesis which will cause removing force against the provisional prosthesis. This case report present that provisional implant prevent pre-described harmful effect on maxillary anterior fixed provisional prosthesis and provide comfort and satisfactory result during post-extraction healing period.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.2 s.314
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• pp.32-38
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• 2007

This paper represents a Doherty amplifier (DPA) with analog predistorter (PD) to improve the linearity of the DPA while preserving the high efficiency. A third-order PD cancels fifth-order intermodulation (IM5) as well as third-order intermodulation (IM3) components by their same phase difference in the PD and DPA. This is accomplished by independently controlling their phase by using the phase-controlled error generator in the PD. Also, we confirm the phase-control ability of the error generator experimentally with a simple and accurate phase measurement setup. For experimental verification, a third-order PD has been implemented and tested in a 180-W DPA at the wide-band code division multiple access (WCDMA) band of 2.11-2.17 GHz. Two-tone test results show that significant cancellation of IM3 and IM5 components can be obtained. For four-carrier WCDMA applications, significant adjacent channel leakage ratio (ACLR) improvement is achieved over a wide range of output power levels. This technique is cost-effective and convenient due to its simple structure, compact size, and three control parameters.

• Clinics in Shoulder and Elbow
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• v.14 no.1
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• pp.125-133
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• 2011

Purpose: The purpose of the present article is to help orthopedic surgeons better understand the function and performance of reverse total shoulder arthroplasty, and also to help them perform the most proper surgical technique for reconstruction. Materials and methods: In this article, the specific technical aspects and pitfalls of reverse total shoulder arthroplasty were reviewed in depth. Additionally, the current issues relevant to the reverse total shoulder arthroplasty such as scapular notching and restoration of active external rotation were discussed. Results and conclusion: An understanding of the biomechanics of reverse total shoulder arthroplasty and the technical details and pitfalls of its implantation are critical in order to provide the best functional outcome without increasing the risk of complications.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.2
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• pp.236-243
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• 2005

Anterior openbite is defined as the lack of contacts between the functional occluding teeth on vertical line at centric occlusion and classified into functional and skeletal anterior openbite based on its causes and characteristics. In mixed dentition, habit control and the elimination of abnormal perioral muscle function and moving the vertical direction development to the sagittal direction of the mandible by the functional appliance is a goal of treatment. This study presents the effective interception of oral habit by the tongue crib and functional-fixed treatment and treatment response of openbite related to tongue thrust habit.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.236-248
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• 2013

In this study, 37 subjects with normal facial shape and normal occlusion are classified and reference value for such classification was investigated. Difference in position of maxillary incisor was studied according to the cl assification. Moreover, by investigating correlation between factors affecting forehead morphology and positio n of maxillary incisor, following results have been obtained. 1. Morphology of forehead can be classified as angular type, round type, straight type, and concave type. 2. There were no specific reference value for evaluation of forehead morphology but possibilities of evaluating forehead morphology using S value and forehead length (Tri-Gla) still remain. 3. There were no correlation between forehead morphology and position of maxillary incisor. 4. Forehead inclination and Andrew analysis show statistically significant negative correlation. That is, as forehead inclination increases, maxillary incisor is positioned posteriorly and this relationship can be shown as following equation, Andrew analysis = -0.39*Forehead inclination.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.1
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• pp.21-31
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• 2018

This study aimed to investigate the correlation between the inclinations of the incisors and lips in mixed dentition aged 7 - 11 years. Lateral cephalometric radiographs of 353 children were analyzed to measure the upper incisor inclination, lower incisor inclination, lower-nasolabial angle, and mentolabial angle in relation to the skeletal malocclusion classification. The measurements were then assessed using the Kruskal-Wallis test, Pearson correlation, and multiple regression analysis. There were significant negative correlations between the inclination of the upper incisors and lower-nasolabial angle in all classes of skeletal malocclusion. There was a negative correlation between the inclination of the lower incisors and mentolabial angle; however, class II malocclusion had a significant positive correlation. This study identified the factors that affect lip inclination and verified their associations.