ZVT DC-DC 전파 브리지 컨버터 해석 및 설계

전칠환,이수원,조승렬 群山大學校 情報通信技術硏究所 1999 情報通信技術硏究論文集 Vol.3 No.-

This paper presents an analysis and design of an optimized soft switching DC-DC full-bridge topology. Soft switching for all main switches is achieved by using a combination of phase shift control and a Zero-Voltage-Transition auxiliary network. Based on a steady-state analysis of the topology a mathematical model describing the converter behaviour is developed. The influence of the auxiliary network design on the operating range, achievable switching frequency and current stress is investigated.

흰쥐에서 외상성 신경종예방에 대한 연구

김승한,전종완,강진성,김찬환,정재홍 大韓成形外科學會 1990 Archives of Plastic Surgery Vol.17 No.5

Prevention of traumatic neuroma has been the subject of extensive since early in the nineteenth century. Odier described this enlargement which develops at the distal end of proximal segments of peripheral nerves after partial or complete transsection. However, there seems to be no unanimity of opinion regarding the treatments of nerve at the time of severed injury. Ligating the proximal end of such a nerve, implanting it into muscle or born, resecting it, injecting it with a sclerosing agent or capping it with a silicone cuff are commonly used at the present time. Petropoulos introduced a nitrogen mustard as a sclerosing agent to prevent the neuroma. Tupper and Booth reported funniculecomy and epincurial ligation with satisfactory result obtained in many patients. However there is no commonly acceptable method. The authers carried out animal studys to find out the better operative procedure to prevent the traumatic neuroma. The sciatic nerve of the rat was exposed under the operating microscope and resected about 1㎝ from the end of the divied portion. Eighty rats were divided into 4 groups by a technique to differentiate management of the severed proximal nerve ends, that is, a control group, a nitrogen mustard injected group, a epineurial ligation group and a combined group(epineurial ligation following the injection of nitrogen mustard). The wound was closed with 4-0 black silk. Three months later, the wound was reopened and the presence of neuroma was observed grossly and microscopically. The results were as follows : 1) The proximal portion of the severed nerve in the combined group were tapered to the end and neuromas were hardly seen grossly. 2) The diameters of minifascicle and the numbers of nerve fibers of the combined group were the smallest and fewest compared with others(p<0.05). 3) The combined group took only 2 to 3 minutes more than the others, but it was better method. The authors found the superiority of this latter method, epineurial ligation following nitrogen mustard injection in the severed end, compaired with the others.

급성 포름알데히드 가스 흡입에 의한 흰쥐 후각상피의 형태학적 변화

백선용,전재기,문용석,황승영,노환중,고의경,왕수건 대한해부학회 1998 Anatomy & Cell Biology Vol.31 No.3

직렬 리액터를 이용한 계통연계형 태양광 발전 시스템

金大均,鄭春炳,全基英,李丞煥,吳鳳煥,李勳九,金容珠,韓慶熙 명지대학교 산업기술연구소 2005 産業技術硏究所論文集 Vol.24 No.-

Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

다중 제어루프에 의한 자기부상용 DC-DC 전원장치에 관한 연구

조주현,조정민,전기영,이상집,이승환,오봉환,이훈구,한경희 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-

The author present a modified multi-loop algorithm including feedforward for controlling a 55kW step down chopper in the power supply of Maglev. The control law for the duty cycle consists of three terms. The first is the feedforward term which compensates for variations in the input voltage. The second term consists of the difference between the slowly moving inductor current and output current. The third term consists of proportional and integral terms involving the perturbation in the output voltage. This perturvation is derived by subtracting the desired output voltage from the actual output voltage. The proportional and integral action stabilizes the system and minimizes output voltage error. In order to verify the validity of the proposed multi-loop controller, simulation study was tried using Matlab simulink.

함암요법으로 골수기능이 억제된 악성종양환자에서 rhG-CSF의 임상적 효과

김원민,서영환,조경상,유병전,김상도,이승일,정춘해 朝鮮大學校 附設 醫學硏究所 1992 The Medical Journal of Chosun University Vol.17 No.2

We have studied the efficacy of rhG-CSF in patients with non-hodgkin's lymphoma, acute leukemia, and small cell lung cancer undergoing anticancer chemotherapy. These patients were below leukocyte count 3,000 cubic millimeter due to myelosuppression induced by the first cycle of intensive chemotherapy. Treatment with rhG-CSF (100㎍ per square meter of body surface area per day in a 30-minute intravenous infusion) was begun two days and for 14 consecutive days after the end of the second cycle of chemotherapy. The results were as follows. 1. The onset of myelosuppression was 6 days after chemotherapy, and the onset of recovery was 16.7 days after chemotherapy, and the duration of granulocytopenia was 10.7 days in patients with malignant tumor during contrast period. 2. The duration of granulocytopenia was shortened 5.2 days in patients administered rhG-CSF than without rhG-CSF, and we observed the shortest duration of granulocytopenia with increasing granulocyte in patients with small cell lung cancer. 3. Observing the differential count of leukocyte checked the highest level of leukocyte in contrast and rhG-CSF period, the persentage of neutrophil was increased in patients with acute leukemia and small cell lung cancer during rhG-CSF period, but not increased in patients with non-hodgkin's lymphoma. 4. rhG-CSF was not influenced on liver faction, renal fuction, uric acid, and glucose metabolism, also had no effect on recovery of platelet. In conclusion, rhG-CSF can be administered to patients with hematologic or nonhematologic malignant tumor that myelosuppression induced by anticancer chemotherapy result in shortening the duration of granulocytopenia and increasing the peripheral neutrophil, therefore full dose chemotherapy can be administered on time, and rhG-CSF may reduce the morbidity and mortality of patients with malignant tumor undergoing chemotherapy.

신경회로망 제어기를 이용한 PID 파라미터 추정에 관한 연구

權重東,裵銀敬,金恩基,全基英,李承桓,吳鳳煥,李勳九,金容珠,韓慶熙 明知大學校 産業技術硏究所 2006 産業技術硏究所論文集 Vol.25 No.-

In this paper, supposed to solve these problem to PID parameters controller algorithm using ANN. In the proposed algorithm, the parameters of the controller were adjusted to reduce by on-line system the error of the speed of IM. In this process, EBPA NN was constituted to an output error value of an IM and conspired an input and output. The performance of the self-tuning controller is compared with that of the PH) controller tuned by conventional method (Ziehler-Nichols). The effectiveness of the proposed control method is verified thought the Matlab Simulink and experimental results.

서울의 PPNG 발생 빈도(1991-1992)

김재홍,윤기범,박평원,김영진,전경민,김영태,김중환,곽호,구상완,송민석,유옥,지혜구,김동원,문상은,박영립,정승호,성범진,성순제,엄주용,황정열,이기홍,이주협,전태진 대한화학요법학회 1994 대한화학요법학회지 Vol.12 No.1

The prevalence of PPNG among pretreated gonorrhea cases isolated at the STD clinic of Choong-Ku Public Health Center in Seoul has been studied and reported annually since 1981. In 1991, 123 strains of N.gonorrhoeae were isolated, among which 58(47.1%) were PPNG. In 1992, 98 starains of N.gonorrhoeae were isolated, among which 51(52.0%) were PPNG. In all, 109(49.3%) strains were found to be PPNG among 221 strains isolated between 1991-1992. The prevalence of PPNG in Seoul showed increased tendency till 1989, thereafter, it has been stationary or slightly decreasing.

Steady-Flow Characteristics and Its Influence on Spray for Direct Injection Diesel Engine

Jeon, Chung-hwan,Park, Seung-hwan,Chang, Young-june The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.7

Flow and spray characteristics are critical factors that affect the performance and exhaust emissions of a direct injection diesel engine. It is well known that the swirl control system is one of the useful ways to improve the fuel consumption and emission reduction rate in a diesel engine. However, until now there have only been a few studies on the effect of flow on spray. Because of this, the relationship between the flow pattern in the cylinder and its influence on the behavior of the spray is in need of investigation. First, in-cylinder flow distributions for 4-valve cylinder head of DI (Direct Injection) Diesel engine were investigated under steady-state conditions for different SCV (Swirl Control Valve) opening angles using a steady flow rig and 2-D LDV (Laser Doppler Velocimetry). It was found that swirl flow was more dominant than that of tumble in the experimented engine. In addition, the in-cylinder flow was quantified in terms of swirl/tumble ratio and mean flow coefficient. As the SCV opening angle was increased, high swirl ratios more than 3.0 were obtained in the case of SCV -70° and 90°. Second, spray characteristics of the intermittent injection were investigated by a PDA (Phase Doppler Anemometer) system. A Time Dividing Method (TDM) was used to analyze the microscopic spray characteristics. It was found that the atomization characteristics such as velocity and SMD (Sauter Mean Diameter) of the spray were affected by the in-cylinder swirl ratio. As a result, it was concluded that the swirl ratio improves atomization characteristics uniformly.

Steady-Flow Characteristics and Its Influence on Spray for Direct Injection Diesel Engine

Seung-hwan Choi,Chung-hwan Jeon. young-june Ch 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.7

Flow and spray characteristics are critical factors that affect the performance and exhaust emissions of a direct injection diesel engine. It is well known that the swirl control system is one of the useful ways to improve the fuel consumption and emission reduction rate in a diesel engine. However, until now there have only been a few studies on the effect of flow on spray. Because of this, the relationship between the flow pattern in the cylinder and its infiuence on the behavior of the spray is in need of investigation. First, in-cylinder flow distributions for 4-valve cylinder head of DI (Direct Injection) Diesel engine were investigated under steady-state conditions for different SCV (Swirl Control Valve) opening angles using a steady flow rig and 2-D LDV (Laser Doppler Velocimetry). It was found that swirl flow was more dominant than that of tumble in the experimented engine. In addition, the in-cylinder flow was quantified in terms of swirl/tumble ratio and mean flow coefficient. As the SCV opening angle was increased, high swirl ratios more than 3.0 were obtained in the case of SCV -7℃ and 90°. Second, spray characteristics of the intermittent injection were investigated by a PDA (Phase Doppler Anemometer) system. A Time Dividing Method (TDM) was used to analyze the microscopic spray characteristics. It was found that the atomization characteristics such as velocity and SMD (Sauter Mean Diameter) of the spray were affected by the in-cylinder swirl ratio. As a result, it was concluded that the swirl ratio improves atomization characteristics uniformly.<br/>