SVPWM 방식의 3상 고역율 AC-DC Boost 컨버터

나재형(Jae-Hyeong Na),이정효(Jung-Hyo Lee),김경민(Kyung-Min Kim),이수원(Su-Won Lee),원충연(Chung-Yuen Won) 한국조명·전기설비학회 2008 한국조명·전기설비학회 학술대회논문집 Vol.2008 No.10월

The problems of power factor and harmonics are occurred in converter system which used to SCRs and diodes as power semiconductor devices IGBT was solved that problem, maintain the input line current with sinusoidal wave current of input power source voltage. In this paper, three phase AC to DC boost converter that operates with unity power factor and sinusoidal input currents is presented. The current control of the converter is based on the space vector PWM strategy with fixed switching frequency and the input current tracks the reference current within one sampling time interval. Space vector PWM strategy for current control was materialized as a digital control method. By using this control strategy low ripples in the output voltage, low harmonics in the input current and fast dynamic responses are achieved with a small capacitance in the de link.

연료전지 발전용 풀-브리지 컨버터의 병렬제어

나재형(Jae-Hyeong Na),장수진(Su-jin Jang),박찬흥(Chan-Heung Park),원충연(Chung-Yuen Won),이병국(Byoung-Kuk Lee) 한국조명·전기설비학회 2007 한국조명·전기설비학회 학술대회논문집 Vol.2007 No.5월

A large power fuel cell generation system needs a parallel operation of dc-dc boost converter. Therefore, this paper proposed parallel operation algorithms of de-de boost converters for the large scale fuel cell generation system of 250[㎾] and the operating principle along with the control method in detail. This paper uses a maximum current sharing method as a parallel operation method and also the phase shift full bridge dc-dc converter as a de-de boost converter. Simulation and experimental results on two prototype converter modules of 500W show that the parallel operation method can be applied to the 250[㎾] cower converter.

칼륨식이 변화에 따른 신장 집합관 개재세포의 형태학적 적응반응

나재형(Jae Hyeong Na),이송은(Song Eun Lee),정창영(Chang Young Jeong),박성식(Sung Sik Park),안규윤(Kyu Youn Ahn) 대한신장학회 2001 Kidney Research and Clinical Practice Vol.20 No.5

체내 K^+ 균형은 신장에서의 K^+ 배설조절과 소화관에서의 K^+ 흡수조절에 의해서 이루어진다. 저칼륨혈증 동안 형태학적 연구로는 신장 외수질집합관의 개재세포의 수적 증가와 강측 세포막 비대가 관찰된다는 보고만 있을 뿐 타 부위의 개재세포에서의 관찰소견과 칼륨식이 변화에 따른 형태학적인 연구는 없는 실정이다. 본 연구는 흰쥐 신장 집합관의 부위별 개재세포에서 칼륨식이 변화에 따른 형태학적 적응변화를 전자현미경을 이용하여 관찰하였다. 전자현미경소견에서 정상 식이군의 피질집합관 A형 개재세포는 강측면에 0.4-0.6 ㎛ 길이의 많은 미세돌기를 내고 있었으며 기저면은 많은 기저주름을 내고 있었다. 첨부 세포질에는 많은 관소포가 출현하였고, 사립체는 세포질 전역에 고르게 분포하고 있었다. 칼륨제한 식이군의 피질집합관 A형 개재세포는 강측면에 미세돌기가 정상식이군의 개재세포보다 수와 길이가 증가하였고 기저면은 기저주름이 줄어들어 더 단순해졌다. 관소포는 대부분 사라졌고 사립체는 증가되어 세포질의 대부분을 차지하고 있었다. 칼륨제한 식이 후 정상 식이군의 피질집합관 A형 개재세포는 미세돌기가 길어지고, 사립체가 증가한 소견 이외에는 정상 식이군의 소견과 유사하였다. 정상 식이군의 외수질집합관 개재세포는 강측면에 피질집합관 A형 개재세포보다는 수도 적고 크기도 작은 미세돌기와 기저면에 단순한 기저주름을 내고 있었다. 첨부 세포질에는 많은 관소포와 사립체가 출현하였다. 칼륨제한 식이군의 외수질집합관 개재세포는 정상 식이군에 비해 훨씬 더 비대해졌고, 강측면의 미세돌기는 수와 길이가 증가하였고, 기저면의 기저주름은 증가하여 복잡해졌다. 관소포는 대부분 사라졌고, 사립체는 증가되어 세포질의 대부분을 차지하고 있었으며, 용해 소체도 출현하였다. 칼륨제한 식이 후 정상 식이군의 외수질집합관 개재세포는 비대되고, 더 길어진 미세돌기, 증가된 사립체와 용해소체 이외에는 정상 식이군 소견과 유사하였다. 정상 식이군의 내수질 집합관 개재세포는 강측면에 소수의 짧은 미세돌기를 내고 있었고 기저면의 기저주름은 외수질집합관 개재세포의 것과 유사하여 단순하였다. 첨부 세포질에는 많은 관소포가 출현하였고, 사립체는 세포질 전역에 고르게 분포하고 있었으며 용해소체도 출현하였다. 칼륨 제한식이 군의 내수질집합관 개재세포는 정상 식이군에 비해 훨씬 더 비대해졌고, 강측면의 미세돌기는 수와 길이가 증가하였고 기저면의 기저주름은 증가하였다. 관소포는 대부분 사라졌고, 사립체는 증가하였다. 칼륨 제한식 이후 정상 식이군의 내수질 집합관개재세포는 비대되고, 증가하고 길어진 미세돌기 이외에는 정상 식이군 소견과 유사하였다. 이상의 결과는 부위별 신장 집합관개재세포는 혈중 칼륨 농도변화에 대응하여 K^+ 평형을 유지하기 위해 형태학적인 변화를 일으켜 적응함을 시사하였다. N/A

제왕절개술 후 발생한 산후 난소 정맥 혈전증

이유경 ( Lee Yu Gyeong ),윤대석 ( Yun Dae Seog ),유재두 ( Yu Jae Du ),강창구 ( Kang Chang Gu ),나재형 ( Na Jae Hyeong ),배열 ( Bae Yeol ) 대한산부인과학회 2003 Obstetrics & Gynecology Science Vol.46 No.8

Postpartum ovarian vein thrombosis has been thought to be a rare disease of which clinical finding is not accurate. Most of postpartum ovarian vein thrombosis presents as symptoms consisting of fever, lower abdominal pain, abdominal mass. If the symptom d

칼륨식이 변화에 따른 신장 집합관 개재세포의 형태학적 적응반응

나재형,이송은,정창영,박성식,안규윤 대한신장학회 2001 대한신장학회잡지 Vol.20 No.5

개에서 Nicardipine 과 Sodium Nitroprusside 가 Stunned Myocardium 의 기능 회복에 미치는 영향

유경연,임웅모,나재형 대한마취과학회 1996 Korean Journal of Anesthesiology Vol.30 No.4

Background: Cytosolic Ca^(2+) overload and oxygen derived free radicals may contribute to stunned myocardium. The pnt study was aimed to investigate the effects of nicardipine and sodium nitroprusside (SNP) on the functional recovery of postischemic reperfused myocardium. Methods: Fifty-seven halothane-anesthetized dogs were subjected to 15 minutes of 1eft anterior descending coronary artery (LAD) occlusion and 3 hours of reperfusion. They were randomly assigned to receive either intracoronary nicardipine (n=11) or SNP (n=10) alone or both (nicardipine plus SNP, n=10). Eleven dogs that received saline i.c. served as the controL Regional myocardial contractility was evaluated by systolic shortening (%SS), the preload recruitable stroke work slope (Mw), and intramyocardial pressure (IMPs). Diastolic function was assessed by time constant of myocardial relaxation (IMP-tau) and postsystolic shortening (%PSS), LAD blood flow was measured by a Doppler flowmeter as well. Results: LAD occlusion produced a significant reduction in systolic as well as diasto1ic functions to similar degrees in all groups. However, %SS was significantly higher in the nicardipine, SNP and nicardipine-SNP groups (67%, 56%, and 68% of baseline values, respectively) than in the controls (20%) at 3 hours of reperfusion. Furthermore, Mw recovered to the baseline with the onset of reperfusian in the three experimental groups. IMP-tau was restored to the baseline during early nperfusion in the SNP-treated groups but was significantly prolonged in the control and nicardipine poups throughout the seperfusion. LAD blood flow during reperfusion was higher in the SNP-treated groups in comparison to the control group. Conclusions: Treatment with either nicardipine or SNP enhances the recovery of mgional contractile function in the canine model of myocardial stunning. SNP not nicardipine is also beneficial in attenuation of early diastolic dysfunction. Nicardipine combined with SNP improved systolic as well as early diastolic functions more significantly when compared to either nicardipine or SNP alane.

전신마취하에서 복강경 담낭절제술이 동맥 혈액가스에 미치는 영향

정창영,윤명하,나재형 대한마취과학회 1995 Korean Journal of Anesthesiology Vol.28 No.5

Changes in arterial blood gases and arterial pressure during laparoscopic cholecystectomy under the general anesthesia (enflurane in N2O/O2 50%) were investigated in 30 patients, who were divided into two groups according to control of minute ventilation. During surgery, minute ventilation was set 100 ml/kg in group I and 150 ml/kg in group II, and intraabdominal pressure was maintained at 15mmHg by CO₂ insufflation, in both groups. Variables were measured before CO₂ gas insufflation, 15 and 30 minutes after insufflation, just after exsufflation, 15 and 30 minutes after exsufflation and in recovery room. 1. PaCO₂ was increased significantly during CO₂ gas insufflation and just after exsufflation in both group, and degree of increase (PaCO₂) was significantly greater in group I compared to group II. 2. Changes of PaO₂ were not statistically significant in comparison to control value and between two groups during CO₂ gas insufflation and exsufflation. 3. Blood pH in both groups were lowered significantly compared to control value during CO₂ gas insufflation and exsufflation, and group II (increased minute ventilation group), represents lower risk of acidosis compared to group I. 4. Mean arterial pressure and airway pressure were significantly increased compared to control value during CO₂ gas insufflation, but there was no significant difference between two groups. These results suggest that minute ventilation during laparoscopic cholecystectomy should be increased up to maintaining normal PaCO₂ for prevention of hemodynamic and blood gas changes due to CO₂ retention.