• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.979-980
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• 2011

영구자석 선형 동기 전동기(Permanent Magnet Linear Synchronous Motor)는 구조적으로 간단하며 고속화 고추력화 등의 많은 장점을 가지고 있지만 전기자 권선부의 슬롯-치 구조로 인한 코깅력과 단부효과에 의한 코깅력이 발생한다. 이는 추력 맥동의 원인이 되며, 소음과 진동을 발생시킨다. 따라서, 본 연구에서는 전기자를 분산배치할 경우 필연적으로 생기는 단부에 의한 코깅력을 저감하기 위해 기존의 전기자 끝단에 설치한 보조치를 응용하여 계단형 형상을 가진 보조치의 설치를 제안하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.837-838
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• 2015

본 논문에서는 양측식 영구자석 선형 동기 전동기(Permanent Magnet Linear Synchronous Motor: 이하 PMLSM)의 전기자 분산배치를 위해 전기자에 보조치 및 Offset에 의해 나타나는 단부 코깅력을 해석하였다. 또한 가장 낮은 단부 코깅력을 가지는 Offset 위치에 대하여 역기전력을 분석하였으며 이에 따른 추력 특성에 대한 고찰을 수행하였다.

• Journal of Chest Surgery
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• v.27 no.5
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• pp.390-393
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• 1994

의료기술의 발달로 오늘날의 개심술은 대부분 성공적으로 시행되고 있지만 극히 일부분은 아직도 개심술후 심한 심실기능의 저하로 사망하는 겨우가 있다. 1960년대 중반 Spencer와 DeBakey에 의해 개심술후 심한 심실기능이 저하된 환자에게 심실보조장치를 이용하여 성공적으로 치험한 이후로 많은 발전을 거듭해 왔다. 저자들은 4개월 (6.5Kg)된 남아에서 개심술후 심한 저심박출증으로 인공심폐기의 제거를 못하여 좌심실 보조장치(Centrifugal Biopump)를 사용하여 성공적으로 치험하였기에 보고하는 바이다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.883_884
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• 2009

PMLSM에서는 전기자 권선부의 슬롯-치 구조로 인한 디텐트력과 단부효과에 의한 디텐트력, 영구자석의 고조파 성분 자속에 의한 디텐트력이 발생한다. 따라서, 본 연구에서는 자기저항의 불연속으로 인한 디텐트력을 제거시키기 위하여 전기자 권선과는 독립된 자기회로를 가지는 보조코어의 설치를 제안하였다. 보조코어의 최적 설계는 유한요소 해석과 실험계획법을 이용하였으며 이론치와 실험치를 비교함으로서 본 연구의 타당성을 입증하였다.

• Tuberculosis and Respiratory Diseases
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• v.45 no.2
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• pp.380-387
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• 1998

Background: Minimal pressure support(PSmin) is a level of pressure support which offset the imposed work of breathing(WOBimp) developed by endotracheal tube and ventilator circuits in pressure support ventilation While the lower applied level of pressure support compared to PSmin could induce respiratory muscle fatigue, the higher level than PSmin could keep respiratory muscle rest resulting in prolongation of weaning period during weaning from mechanical ventilation PSmin has been usually applied in the level of 5~10 cm$H_2O$, but the accurate level of PSmin is difficult to be determinated in individual cases. PSmin is known to be calculated by using the equation of "PSmin = peak inspiratory flow rate during spontaneus ventilation$\times$total ventilatory system resistance", but correlation of calculated PSmin and measured PSmin has not been known. The objects of this study were firstly to assess whether customarily applied pressure support level of 5~10 cm$H_2O$ would be appropriate to offset the imposed work of breathing among the patients under weaning process, and secondly to estimate the correlation between the measured PSmin and calculated PSmin. Method : 1) Measurement of PSmin : Intratracheal pressure changes were measured through Hi-Lo jet tracheal tube (8mm in diameter, Mallinckroft, USA) by using pulmonary monitor(CP-100 pulmonary monitor, Bicore, USA), and then pressure support level of mechanical ventilator were increased until WOBimp was reached to 0.01 J/L or less. Measured PSmin was defined as the lowest pressure to make WOBimp 0.01 J/L or less. 2) Calculation of PSmin : Peak airway pressure(Ppeak), plateau airway pressure(Pplat) and mean inspiratory flow rate of the subjects were measured on volume control mode of mechanical ventilation after sedation. Spontaneous peak inspiratory flow rates were measured on CPAP mode(O cm$H_2O$). Thereafter PSmin was calculated by using the equation "PSmin = peak inspiratory flow rate$\times$R, R = (Ppeak-Pplat)/mean inspiratory flow rate during volume control mode on mechanical ventilation". Results: Sixteen patients who were considered as the candidate for weaning from mechanical ventilation were included in the study. Mean age was 64(${\pm}14$) years, and the mean of total ventilation times was 9(${\pm}4$) days. All patients except one were males. The measured PSmin of the subjects ranged 4.0~12.5cm$H_2O$ in 14 patients. The mean level of PSmin was 7.6(${\pm}2.5\;cmH_2O$) in measured PSmin, 8.6 (${\pm}3.25\;cmH_2O$) in calculated PSmin Correlation between the measured PSmin and the calculated PSmin is significantly high(n=9, r=0.88, p=0.002). The calculated PSmin show a tendancy to be higher than the corresponding measured PSmin in 8 out of 9 subjects(p=0.09). The ratio of measured PSmin/calculated PSmin was 0.81(${\pm}0.05$). Conclusion: Minimal pressure support levels were different in individual cases in the range from 4 to 12.5 cm$H_2O$. Because the equation-driven calculated PSmin showed a good correlation with measured PSmin, the application of equation-driven PSmin would be then appropriate compared with conventional application of 5~10 cm$H_2O$ in patients under difficult weaning process with pressure support ventilation.

• Proceedings of the Korean Association for Survey Research Conference
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• 2003.06a
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• pp.19-28
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• 2003

Weighting adjustment is a method of improving the efficiency of the estimator by incorporating auxiliary variables at the estimation stage. One commonly used method of weighting adjustment is the poststratification, which is a special case of regression estimation but is relatively feasible in terms of actual implementation. If too many auxiliary variables are used in the poststratification, the bias of the resulting point estimator is no longer negligible and the final weights may have extreme weights. In this study, we propose a method of weight ing adjustment that compromises the efficiency and the bias of the point estimator. A limited simulation study is also presented.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.11
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• pp.1675-1680
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• 2013

Recently, the permanent magnet linear synchronous motor as low noise, high speed and high thrust force transportation system has been proposed but this motor causes an increase of material cost because of its characteristic arranging the armature on the full length of transportation lines when this system is applied to the long distance transportation system. Therefore, we suggested discontinuous arrangement method of the armature to solve this problem. However, Detent force which causes thrust force ripple generating noise, vibration and decline of performance is generated when a mover pass between the armatures. Thus, in this paper, we examined characteristic of detent force to reduce the end edge effect according to the end edge teeth's height and auxiliary teeth and suggested the shape that can the most reduce the detent force.

• Journal of Korean Dental Hygiene Science
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• v.6 no.2
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• pp.65-77
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• 2023

Background: The shortage of dental hygienists as assistant is a great concern to dental clinics, while dental hygienists are rather pursuing the role of oral hygiene control and preventive treatments which is the main role for dental hygienists in the United States. The dental hygienist and dental assistant system in the United States can be a reference in these discussions. Methods: Educational requirements for licensure and work areas for dental hygienists and dental assistants were investigated through the information provided by the American Dental Association (ADA), American Dental Hygienists Association, National Board Dental Hygiene Examination (NBDHE), Dental Assistants Association of America (ADAA), and Dental Assistants National Board (DANB). Results: In the United States, each state has different systems, but in general, dental hygienists obtain licenses after completing 2~3 years of associate degree programs in dental hygiene after obtaining basic learning skills, and mainly perform tasks related to patient screening procedures, oral hygiene management and preventive care. Dental assistants can take the license test after completing a training course of 9~11 months to obtain a dental assistant certification. Additional expanded work typically requires passing state qualification tests, completing a training program, obtaining a degree, or gaining clinical experience for a certain period of time, depending on the state Conclusion: The scope of work of dental hygienists designated by the Medical Engineer Act and the Enforcement Decree in Korea includes both the work of dental hygienists and dental assistants in the United States, and if a dental assistant system like the United States is introduced to address the current shortage of dental assistants, institutional supplementation such as adjustment of the scope of work and expansion of the role of dental hygienists in oral hygiene management and prevention work is needed and in-depth discussion is necessary.

• Journal of the Korean Magnetics Society
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• v.26 no.1
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• pp.31-37
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• 2016

This study considered the reduction of the detent force of a permanent magnet linear synchronous generator (PMLSG). The PMLSG has a relatively large magnetic air gap. Thus, a slotted type of stator structure is generally employed. Furthermore, the detent force, which is caused by energy imbalances owing to the interaction between tooth-slot structures and the permanent magnets (PMs), must be minimized for start-up operation. Therefore, in this paper, the methods of auxiliary teeth and a notch in the teeth are applied to reduce the detent force.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.236-237
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• 2008

이 논문은 노인 및 장애인의 활동을 보조하기 위한 보행보조 로봇의 핵심 기술인 사용자의 진행하고자 하는 방향과 속도를 검출하는 보행의지 파악시스템 구현을 하고자 한다. 최근에 노인인구의 증가로 인해 노인 및 장애인을 위한 보행 보조기에 대한 관심이 증가되고 있다. 그러나 대부분의 경우 동력이 없는 시스템으로 경사 등의 공간에서 취약성을 가지고 있다. 이에 동력형 보행보조기에 대만 관심이 증가되고 있으나, 대부분의 경우 보행보조기 조종이 여의치 않다. 이에 본 논문에서는 사용자의 보행의지를 파악할 수 있는 시스템을 도입하고 이를 기초로 보행자의 안정적인 구동을 수행할 수 있도록 하였다. 사용자의 의지력은 FSR 센서를 이용하여 파악하고, 이를 기초로 사용자가 이동하고자 하는 이동 방향과 이동속도 데이터를 기초로 보행보조기의 차량 속도와 방향에 대해 구동 바퀴의 차동구동을 통해 사용자의 의지에 맞춰 구동할 수 있도록 하였다. 이를 통해 사용자의 이동하려는 의지에 대해 안정적으로 차량을 이동시킬 수 있도록 보행 시스템을 구축하였다. 또한 사용자자의 힘에 대한 속도 및 방향 매핑 기법을 개발하여 보행의지의 정확성을 높였다.