• Communications for Statistical Applications and Methods
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• 제26권2호
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• pp.103-129
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• 2019

The main goal of a case-control study is to learn the association between various risk factors and a primary outcome (e.g., disease status). Particularly recently, it is also quite common to perform secondary analyses of the case-control data in order to understand certain associations between the risk factors of the primary outcome. It has been repeatedly documented with case-control data, association studies of the risk factors that ignore the case-control sampling scheme can produce highly biased estimates of the population effects. In this article, we review the issues of the naive secondary analyses that do not account for the biased sampling scheme, and also the various methods that have been proposed to account for the case-control ascertainment. We additionally compare the results of many of the discussed methods in an example examining the association of a particular genetic variant with smoking behavior, where the data were obtained from a lung cancer case-control study.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권3호
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• pp.273-288
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• 2010

In this paper, we propose a cooperative multi-relay scheme for a secondary system to achieve spectrum access along with a primary system. In the primary network, a primary transmitter (PT) transmits the primary signal to a primary receiver (PR). In the secondary network, N secondary transmitter-receiver pairs (ST-SR) selected by a centralized control unit (CCU) are ready to assist the primary network. In particular, in the first time slot, PT broadcasts the primary signal to PR, which is also received by STs and SRs. At STs, the primary signal is regenerated and linearly combined with the secondary signal by assigning fractions of the available power to the primary and secondary signals respectively. The combined signal is then broadcasted by STs in a predetermined order. In order to achieve diversity gain, STs, SRs and PT will combine received replicas of the primary signal, using selection combining technique (SC). We derive the exact outage probability for the primary network as well as the secondary network. The simulation results are presented to verify the theoretical analyses.

• 대한두경부종양학회지
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• 제15권2호
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• pp.162-165
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• 1999

Background and Objectives: Multiple primary tumors of the upper aerodigestive tract are not unusual. We examined head and neck cancer patients to discover the presence of second primary cancer in their upper gastrointestinal tract, using esophagogastroscopy. Materials and Methods: Endoscopic examination of the upper gastrointestinal tract was performed on 51 patients whose head and neck cancers were treated at department of therapeutic radiology from August 1996 to April 1999. Two of all patients had been studied by barium swallowing study. In 51 patients, twenty-four had a primary tumor in the larynx, 8 in the oropharynx, 6 in the nasopharynx, 6 in the oral cavity, 6 in the hypopharynx, and 1 in the nasal cavity. Endoscopically pathologic lesions were biopsied. In control group, endoscopy was performed on 1097 patients who didn't complain any symptoms. Results: Endoscopy showed early malignant lesions in 4 cases(7.7%). Histology of esophageal cancers showed squamous cell carcinoma. Malignant lesions of stomach in 2 cases were histologically identified as adenocarcinoma. Two esophageal cancers occurred in patients whose primary lesions had oropharynx and hypopharynx. Two cases of gastric cancer were also accompanied by oropharynx and hypopharynx. The incidence of second primary cancer was 2 in oropharynx and 2 in hypopharynx. In all cases, second primary cancers were found simultaneously. In control group, 9(0.8%) of 1097 patients were confirmed as early esophageal and gastric cancers. Conclusion: The majority of esophageal and gastric cancer detected by endoscopy were early stage in both head and neck cancer and control group. The incidence of esophageal and gastric cancer of head and neck cancer patients was 10 times as high as that of control group. Although followup period was short, all second primary cancers were detected simultaneously. We would recommend that endoscopic evaluation be included in the workup and followup of all patients with newly diagnosed head and neck cancer.

• Journal of Power Electronics
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• 제16권3호
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• pp.840-848
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• 2016

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

• Journal of Power Electronics
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• 제16권1호
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• pp.111-120
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• 2016

Generally, a single phase H-bridge converter feeding a single primary track is employed in conventional inductive power transfer systems. However, these systems may not be suitable for some high power applications due to the constraints of the semiconductor switches and the cost. To resolve this problem, a novel dual coupled primary tracks IPT system consisting of two high frequency resonant inverters feeding the tracks is presented in this paper. The primary tracks are wound around an E-shape ferrite core in parallel which enhances the magnetic flux around the tracks. The mutual inductance of the coupled tracks is utilized to achieve adjustable power sharing between the inverters by configuring the additional resonant capacitors. The total transfer power can be continuously regulated by altering the pulse width of the inverters' output voltage with the phase shift control approach. In addition, the system's efficiency and the control strategy are provided to analyze the characteristic of the proposed IPT system. An experimental setup with total power of 1.4kW is employed to verify the proposed system under power ratios of 1:1 and 1:2 with a transfer efficiency up to 88.7%. The results verify the performance of the proposed system.

• Journal of Advanced Marine Engineering and Technology
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• 제8권1호
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• pp.64-71
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• 1984

In this paper, the fundemental equation on the Trans-vector control of 3.phi. Induction motor drive and the new equivalent circuit to be adapted for this equation, have been obtained, and control drives system to be coincide with this equation is made. Therefore, it has been obtained that control scheme can always be used motor drive. 3.phi. Induction motor drive has been got the dynamic behavior the same as that of DC motor drive. The drive dynamic response is very rapid because of Trans-vector control on the I_1$ (primary current) and .${\omega}_1$ (frequency of primary current) of the Induation mechine. This paper indicates that a practicality of the drive control system and the rationalty of the theory have been identified with the experimental results. The effect of parameter variations on the drive dynamic response can be evaluated from these results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.166.2-166
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• 2001

This paper is concerning a vector control of wound-rotor induction motor from the secondary side. When the wound-rotor induction motor is vector controlled from the secondary side, it has the possibility that the vector control can be accurately done because the disturbance input, that is, primary voltage and all state variables, that is, primary currents and secondary currents can be detected. We consider it is deserve research that the vector control of wound-rotor induction motor from the secondary side, because there is the merit that we can reduce the inverter capacity to on the order of half of the motor capacity when we choose twice of the synchronous speed to the rated speed, though there is the problem of the brush maintenance. In this paper, the vector control method of wound-rotor induction ...

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.683-684
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• 2006

It is necessary to modify the state-of-the-art of speed control theory because of the phase asymmetry in the Linear Induction Motor (LIM)and for the constant speed control of mover using single vector control inverter system, it is important that primary stack is located in appropriated intervals in the 3D conveyer system using LIM. The dynamic characteristic analysis method of the vector controlled LIM using coupled FEM and control algorithm taking into account the movement is proposed. The focus of this paper is the analysis relative to selecting primary stack intervals in order to constant speed control in the 3D conveyer system using LIM.

• Journal of Power Electronics
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• 제11권5호
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• pp.697-703
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• 2011

In this paper a control system with a high performance dynamic response for linear induction motors (LIMs) is proposed which takes into account the end-effect in both the machine model and the control system. Primary flux oriented control has two major drawbacks i.e. a lack of decoupling of the thrust and the flux and a possibility of system instability due to the end-effect. Both of these drawbacks have been dealt with in this paper. A flux estimation method is proposed to correct the flux orientation error caused by the end effect. Extensive motor performance evaluations under the proposed control system prove its superiority over conventional vector control.

• 전력전자학회논문지
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• 제24권4호
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• pp.294-302
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• 2019

A capacitor common connected LLC resonant converter with auxiliary switches for a wide output voltage control range is presented in this paper. The proposed converter can be controlled in two ways to achieve a wide output voltage control range of Vo-3Vo. The first control method is performed through pulse width modulation of the auxiliary switches and primary switching devices. The second control method is conducted through frequency modulation of the primary switching devices configured to operate in full-bridge switching modes, when the auxiliary switches are turned off. The feasibility of the proposed converter is verified by the experimental results of a 5 kW prototype.