양안시 유형에 따른 경사 AC/A비와 계산 AC/A비의 관계

김재도,김효정,황정희 대한시과학회 2012 대한시과학회지 Vol.14 No.4

목적: 일반적으로 임상에서 가장 많이 사용되는 AC/A비 측정방법은 경사(Gradient)에 의한 방법과 계 산(Calculate)에 의한 방법이다. 양안시 타입에 있어서 이들 두 측정 방법에 의한 결과의 관계는 알려지지 않았다. 따라서 본 연구는 양안시 유형에 따른 경사에 의한 방법과 계산에 의한 방법을 비교하고자 하였다. 방법: 안과질환과 사시 및 약시가 없는 164명이 연구에 참여하였다. 대상자의 평균굴절이 상도 및 연령 은 각각 우안 S-2.34(±2.25)D C-0.98(±1.00)D, 좌안 S-2.22(±2.15)D C-1.05(±1.06)D, 20.84±0.96 세(6세에서 41세)였다. 모든 측정은 Vision-K Auto-refractor®에 의한 완전교정 상태에서 실시하였다. 원 거리(3m) 및 근거리(40 cm) 사위 검사는 각각 하웰 사위카드와 하웰-김 카드를 이용하여 측정하였다. 계산 AC/A비는 동공거리(cm)+0.4(근거리사위-원거리사위)로 경사 AC/A비는 +1.00D와 -1.00D 조절자극에 의 한 근거리 사위 차이의 반으로 결정하였다. 결과: 전체 대상자에 있어서 계산 AC/A비(5.07±1.55)가 경사 AC/A비(4.00±1.32) 보다 통계적으로 유의적인 수준에서 높았다(t=1.95, p < 0.001). 계산AC/A는 정위(t=2.0, p < 0.001), 기본형 내사위 (t= 2.16, p < 0.05), 기본형 외사위(t=2.20, p < 0.01), 폭주과다(t =2.26, p < 0.01) 유형에서 경사AC/A비 보 다 유의 수준에서 높았지만 다른 양안시 그룹에서는 유의수준에서 차이가 없었다. 전체대상자에 있어서 두 방법 간에 상관관계는 없었다(r = 0.012, p > 0.05). 결론: 전체 대상자에 있어서 계산 AC/A비가 경사 AC/A비 보다 높았지만 두 AC/A비 사이의 상관관계 는 보이지 않았으며 두 AC/A비 차이는 양안시 유형에 따라 달랐다. Purpose: The two most commonly used clinical methods for determining AC/A ratio are gradient method and calculated method. Relation between results by these two methods has not been found in different binocular vision types. This study is to compare between gradient method and calculated method in the different binocular vision types. Methods: 164 subjects who have no the ocular disease, strabismus and ambylyopia were participated. Means of refractive error and age are S-2.34(±2.25)D C-0.98(±1.00)D for right eye and S-2.22(±2.15)D C-1.05(±1.06)D for left eye, and 20.84±0.96(6 to 41 years) years old respectively. All measurements were performed with full spectacle correction measured by Vision-K Auto-refractor®. Distance (3 m) and near (40 cm) heterophorias were measured using Howell phoria and card Howell- Kim phoria card respectively. Calculated AC/A ratios (CAC/A ratio) were decided by pupil distance(cm) +0.4 (near phoria - distance phoria) and by a half of difference between near phorias with -1D and +1D accommodative stimuli Gradient AC/A ratios (GAC/A ratio). Result: CAC/A ratio (5.07±1.55) was significantly higher than GAC/A ratio (t = 1.95, p < 0.001) for all subjects. CAC/A ratio was significantly higher than GAC/A ratio in orthophoric (t = 2.0, p < 0.001), basic esophoric(t = 2.16, p < 0.05) basic exophoric(t = 2.20, p < 0.01) and convergence excessive(t = 2.26, p < 0.01) types, but not significantly different in other groups. There was no significant correlation between two methods in the individual (r = 0.012, p > 0.05). Conclusion: For all subjects, CAC/A ratios were higher than GAC/A ratios, but there was no correlation between two ratios. The differences between two AC/A ratios were different by binocular types.

PWM Cuk AC-AC 컨버터를 위한 새로운 Commutation 회로

최남섭,김인동,Li Yulong,노의철 전력전자학회 2006 전력전자학회 논문지 Vol.11 No.5

This paper proposes a new commutation circuit for a PWM Cuk AC-AC converter. The proposed commutation circuit utilizes a modified Undeland snubber as a commutation aid. The snubber circuit has some good features such as reduction of voltage/current stress of the main switches and improved efficiency. The experiment results show the adaptability and feasibility of the proposed commutation circuit. 본 논문에서는 PWM Cuk AC-AC 컨버터를 위한 새로운 commutation 회로를 제안한다. 제안된 commutation 회로는 컨버터 전류의 commutation을 위하여 개선된 Undeland 스너버를 이용한다. 개선된 스너버 회로는 주 스위치의 전압/전류 스트레스 저감, 효율 개선과 같은 장점을 갖는다. 본 논문에서는 실험을 통하여 제안된 commutation 회로의 효과와 적용 가능성을 확인하였다.

AC133 항원 양성 급성백혈병의 생물학적 특성

김진석,맹호영,정준원,이승태,한지숙,고윤웅,민유홍 大韓血液學會 2002 大韓血液學會誌 Vol.37 No.3

Steady State and Transient Analysis of Switched Reluctance Motor Drive Fed from a Controlled AC-DC Rectifier

Moussa, Mona Fouad The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.8 No.1

The Theory of operation of switched reluctance motors (SRM) depends on the reluctance torque, where energy is transferred to stator winding only. Although its construction is simple, the electrical design is complex, due to the switching configuration needed to deliver power to stator coils. However, because of the nonlinearly of magnetic circuit, SRM has torque ripple. This paper proposes a new strategy to drive SRM from a single-phase AC supply. Each stator winding is connected to AC-DC or AC-AC converters, which is called branch. All branches are connected in parallel to a single-phase AC supply. A shaft encoder allows current production in stator winding during the positive torque production region and terminates it during the negative torque production region. A magnetic flux is produced between stator poles when current is supplied from AC supply to stator coil and repeats many cycles as long as the rate of change of stator inductance is positive. Different possibilities for the configurations of AC-AC or AC-DC converters are introduced to drive SRM from the single-phase AC supply. A case study is presented for a SRM fed from AC supply through semi-controlled AC-DC converter is presented. A simulation model is introduced and verified by experimental rig for two-phase SRM.

Ultrasparse AC-Link Converters

Amirabadi, Mahshid,Jeihoon Baek,Toliyat, Hamid A. IEEE 2015 IEEE transactions on industry applications Vol.51 No.1

<P>Soft-switching ac-link universal power converters, also called partial resonant converters and ac-link buck-boost converters, have received noticeable attention during the last few years. In these converters, each of the inputs and outputs can be dc, single-phase ac, or multiphase ac; therefore, they can be used for dc-dc, dc-ac, ac-dc, or ac-ac power conversion systems. The soft-switching ac-link universal power converters are compact, reliable, and expected to offer longer lifetime compared with the other types of converters. However, they require more switches, which make the control process more involved. The sparse ac-link buck-boost converters were proposed to partially solve this problem. The sparse configuration reduces the number of switches from 24 to 20 in a three-phase ac-ac configuration. This paper proposes a modified configuration, which further reduces the number of switches without changing the principles of operation. This converter, which is named ultrasparse ac-link buck-boost converter, reduces the number of switches from 24 to 16, in a three-phase ac-to-ac case, and from 20 to 10, in a dc-to-three-phase-ac configuration. The proposed converter is applicable to systems with unidirectional flow of power, such as PV and wind power generation systems. This converter is expected to offer higher reliability compared with the original converter and higher reliability and efficiency compared with the sparse configuration. Another important feature of this configuration is that it can be fabricated by insulated-gate bipolar transistor modules, which are more compact and more cost effective compared with discrete devices. This paper presents the principles of the operation of this configuration and compares the efficiency, the failure rate, and the current rating of the switches in the ultrasparse, sparse, and original configurations. Moreover, it evaluates the performance of the proposed converter through simulation and experiment.</P>

Steady State and Transient Analysis of Switched Reluctance Motor Drive Fed from a Controlled AC-DC Rectifier

M. F. Moussa 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.4

The Theory of operation of switched reluctance motors (SRM) depends on the reluctance torque, where energy is transferred to stator winding only. Although its construction is simple, the electrical design is complex, due to the switching configuration needed to deliver power to stator coils. However, because of the nonlinearly of magnetic circuit, SRM has torque ripple. This paper proposes a new strategy to drive SRM from a single-phase AC supply. Each stator winding is connected to ACDC or AC-AC converters, which is called branch. All branches are connected in parallel to a singlephase AC supply. A shaft encoder allows current production in stator winding during the positive torque production region and terminates it during the negative torque production region. A magnetic flux is produced between stator poles when current is supplied from AC supply to stator coil and repeats many cycles as long as the rate of change of stator inductance is positive. Different possibilities for the configurations of AC-AC or AC-DC converters are introduced to drive SRM from the singlephase AC supply. A case study is presented for a SRM fed from AC supply through semi-controlled AC-DC converter is presented. A simulation model is introduced and verified by experimental rig for two-phase SRM.

Integrated Magnetic Core Switching Cell AC-AC Converters

Ashraf Ali Khan,Honnyong Cha,Hafiz Furqan Ahmed,Heung-Geun Kim 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The switching cell (SC) direct PWM ac-ac converters solve the commutation problem of traditional direct PWM ac-ac converters in a very effective way. The magnetic components of the SC ac-ac converters consist of two coupled inductors and an AC inductor. In order to make the SC ac-ac converters more useful and practical, this paper presents the integration of magnetic components in these converters in one magnetic core. The proposed integration method can significantly improve the power density of the SC ac-ac converters. In addition the cost of magnetic components and inductor coils can be reduced. In order to prove the validity of the proposed integration scheme a 600 W prototype inductor is built and tested.

항응고약물상담 서비스( AC S )가 신경과 환자의 warfarin 치료효과에 미치는 영향

예경남,김재연,김희세,나양숙,신혜영,오정미 韓國病院藥師會 2005 병원약사회지 Vol.22 No.1

Pharmacist-managed anticoagulation service (ACS) are responsible for providing the patient education, adjustment of warfarin dosage, monitoring of side effect to maintain prothrombin time within the therapeutic range. Many studies have proven the therapeutics efficiency of ACS by showing the improvements in warfarin therapy while reducing warfarin related adverse effects. There are several hospitals in Korea that are operating the ACS. The ACS in Seoul Asan Medical Center (AMC) began to provide the ACS for the neurology patients treated with warfarin from April 2003 and its effectiveness remains to be evaluated. The purpose of this study was to evaluate the therapeutic effect of ACS by comparing the achievement rate of INR within the therapeutic range before and after ACS operation and by surveying the patient satisfaction of ACS. We compared the achievement rate of INR values within the therapeutic range during the six-month before the ACS (Pre-ACS) and after the referral to the ACS (Post-ACS). The study included 58 patients who had been previously managed by physician but now was managed by ACS. We have also surveyed the patient satisfaction of ACS A total 679 INR values were analyzed pre-ACS group consisted of 285(41%) cases while post-ACS group consisted of 411(59%) cases. The analysis showed that the achievement rate of INR values within the therapeutics range in post-group was significantly superior to the Pre-ACS(65.45% vs. 47.9%, p.0.0001). Furthermore post-group spent more time within the therapeutic range than the pre-ACS group (68.08% vs. 50.10%, p.0.0001). Seventy-nine patients completed the survey on the patient satisfaction. Most patients responded positively with ACS in 18 questions, which correspond with overall satisfaction on ACS, understanding of explanation, knowledge of their medication and non-medication (Cronbach α0.66, 0.77, 0.84, 0.68 respectively). In conclusion, ACS improved the anticoagulation control in neurology patients treated with warfarin by effectively maintaining the INR level within the therapeutics range. The levels of patient satisfaction on ACS and knowledge of the disease and medication were superior.

Biocontrol activity of Paenibacillus polymyxa AC-1 against Pseudomonas syringae and its interaction with Arabidopsis thaliana

Hong, C.E.,Kwon, S.Y.,Park, J.M. G. Fischer 2016 MICROBIOLOGICAL RESEARCH Vol.185 No.-

<P>Paenibacillus polymyxa AC-1 (AC-1) is a plant growth-promoting rhizobacterium (PGPR) that has been used as a soil inoculant for biocontrol of plant pathogenic fungi and to promote plant growth. In this study, we examine the effects of AC-1 on the bacterial phytopathogen Pseudomonas syringae and internal colonization of AC-1 by counting bacterial populations that colonize plants. AC-1 inhibited the growth of both P. syringae pv. tomato DC3000 (Pst) and P. syringae pv. tabaci (Pta) in a concentration-dependent manner in in vitro assays. Upon treatment of AC-1 dropping at root tip of axenically grown Arabidopsis, we found that most of the AC-1 was detected in interior of leaves of Arabidiopsis plants rather than roots after 5 days post infection, indicating systemic spreading of AC-1 occur. We examined further AC-1 colonization patterns in Arabidopsis mutants deficient in phytohormone signaling pathways. These results indicated that abscisic acid (ABA) and jasmonic acid (JA) signaling pathways positively and negatively contributed, respectively, to AC-1 colonization of leaves, whereas epiphytic accumulation of AC-1 around root tissues was not affected. This study shows that AC-1 is an effective biocontrol agent to suppress P. syringae growth, possibly owing to its colonization patterns as a leaf-inhabiting endophyte. The results showed in this work will help to expand our understanding of the mode of action of AC-1 as a biological control agent and consequently, its application in agriculture. (C) 2016 Elsevier GmbH. All rights reserved.</P>

Novel Single-Phase PWM AC–AC Converters Solving Commutation Problem Using Switching Cell Structure and Coupled Inductor

Shin, Hyun-Hak,Cha, Honnyong,Kim, Heung-Geun,Yoo, Dong-Wook Institute of Electrical and Electronics Engineers 2015 IEEE transactions on power electronics Vol. No.

<P>This paper presents novel single-phase pulse width modulation (PWM) ac-ac converters that can solve the commutation problem in single-phase direct PWM ac-ac converters without sensing the input voltage polarity. By using a basic switching cell structure and coupled inductors, the proposed ac-ac converters can be short-and open-circuited without damaging the switching devices. Neither lossy RC snubber nor dedicated soft commutation strategy is required in the proposed converter. By replacing the conventional phase-leg of the PWM ac-ac converters with the switching cell structure and the coupled inductor, three novel buck, boost, and buck-boost type PWM ac-ac converters are developed. Although two coupled inductors are required for the proposed converter, the input inductor of the proposed converter can be much smaller than that of the conventional PWM ac-ac converters. The volume of the magnetic components can be further reduced by increasing switching frequency of the converter because very fast recovery diodes can be selected externally. In order to verify performance and robustness of the proposed converter, a 200-W boost type prototype converter was built and tested with both mismatched gate signals and highly distorted input voltage.</P>