• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.4
• /
• pp.96-103
• /
• 1998

With the advance of processing technology , so as to spare fuel, piston heads used in automobile reciprocating engine have complex 3-dimension, with respect to shape such as ovality, profile, eccentricity, offset, recess. Therefore, coming out of the existing process work used master cam. the process work is performed using a CNC lathe. For a precision processing, the processing work is need to make study of high speed feed gear synchronized with the rotative speed of main spindle. And then the high speed feeding system must maintain high dynamic stiffness, high speed and high positioning accuracy . In this paper, in order to achieve high speed cutting tool feeding. The linear brushless DC motor is used for satisfying this process work. The ball bush and turicite is used as the guidance of the feed gear system. Also linear encoders, digital servo amplifiers and controller are used for controlling driving motor. This paper presents the design and simulation of the new tool feed system for noncircular machining.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.11a
• /
• pp.677-679
• /
• 2005

최근 나노입자를 이용하는 광전 화학전지(PEC, Photoelectrochemical)인 염료감응형 태양전지(DSC)의 효율이 증가함에 따라 DSC 태양광 발전 시스템의 성능 개선 또한 요구되어진다. 본 연구에서는 Fly-Back DC-DC 컨버터(변화비율1:10)를 이용하여 DSC셀의 전압을 DC 300V로 승압시켰다. 또한 풀브릿지 인버터를 사용하여 AC 220V, 60Hz의 출력전압을 얻었다. 연구에서 제안한 회로는 높은 효율의 동작특성과 간단한 제작, 낮은 제조비용, 그리고 안정성을 추구한다. 또 다른 주요점은 부하단에서 Feed back을 받아 동작을 컨트롤하는 것이다. 부하단의 출력 전압과 전류를 Feed back 받아서 DSP320LF2406을 A/D기능을 사용하여 실시간으로 부하의 변화에 대처하여 컨버터와 인버터의 동작을 제어한다.

• Proceedings of the KIPE Conference
• /
• 2015.11a
• /
• pp.46-47
• /
• 2015

본 논문은 태양광 발전 시스템의 차동 전력 조절 방식 중 Feed-Foward 방식을 적용한 다중 출력 플라이백 컨버터를 이용하여 DC_Link 다중 출력 전압을 균등화 하는 회로에 대한 내용이다. DC_Link가 여러 단으로 되어 있을 경우, 전압을 일정하게 맞추어 줄 필요가 있는데, 이를 차동 전력 조절기(Differential Power Processing converter)를 통해서 DC_Link 출력 전압을 균등화 할 수 있다. 스트링 컨버터인 부스트 컨버터의 스트링 전류를 제어 하여 부스트 컨버터의 전력과 DPP역할을 하는 다중 출력 플라이백 컨버터로 전달되는 전력을 조정가능하다. 이를 통하여 전압 균등화가 이루어지게 할 수 있고, 각 DPP 컨버터는 PV 전압 제어를 하여 MPPT 동작을 하게 된다. PSIM 시뮬레이션과 150W급 하드웨어 프로토타입을 제작해 실험을 통하여 검증 하였다.

• Journal of Electrical Engineering and Technology
• /
• v.3 no.2
• /
• pp.235-242
• /
• 2008

In this paper, a 24-pulse AC-DC converter is designed, modeled, simulated, and developed to feed non-isolated varying loads. The proposed AC-DC converter configuration consists of an auto-transformer based on zigzag connection to overcome current harmonic problems in AC mains. It improves power quality at AC mains and it meets IEEE-519 standard requirements at varying loads. A set of power quality indices on input AC mains and on DC buses for a load fed from 6-pulse and 12-pulse AC-DC converters is also given to compare their performance. It is observed that input current total harmonic distortion(THD) of less than 8% is possible with the proposed topology of AC-DC converter at varying loads.

• 한국태양에너지학회:학술대회논문집
• /
• 2012.03a
• /
• pp.325-330
• /
• 2012

A single-phase PVPCS(photovoltaic power conditioning system) that contains a single phase dc-ac inverter tends to draw an ac ripple current at twice the out frequency. Such a ripple current may shorten passive elements life span and worsen output current THD. As a result, it may reduce the efficiency of the whole PVPCS system. In this paper, the ripple current propagation is analyzed, and two methods to reduce the ripple current are proposed. Firslyt, this paper presents notch filter with IP voltage controller to reject specific current ripple in single-phase PVPCS. The notch filter can be designed that suppress just only specific frequency component and no phase delay. The proposed notch filter can suppress output command signal in the ripple bandwidth for reducing output current THD. Secondly, for reducing specific current ripple, the other method is feed-forward compensation to incorporate a current control loop in the dc-dc converter. The proposed notch filter and feed-forward compensation method have been verified with computer simulation and simulation results obtained demonstrate the validity of the proposed control scheme.

• Journal of Biosystems Engineering
• /
• v.15 no.2
• /
• pp.110-122
• /
• 1990

This study was undertaken to develop the feed rate control system for the head feed thresher by making use of the microprocessor and to evaluate the response of the system to a various threshing conditions. The control unit was composed of one-board microcomputer. The speed of the wet-paddy feeding chain was controlled by dc moter with PI controller. It was used the adaptive control method to maintain the constant feed rate regardless of the fed rice varieties. The sliding type potentiometer was used as the feed rate sensor, which was attached on the sheaf-holding apparatus. The mathematical models of the system components were derived and computer simulation was developed for investigating the parameters affecting on control performance and for estimating the response of the system. A one-board microcomputer-based feed rate control system developed in this study was properly functioned and assessed as adequate for the feed rate control system of the head feed thresher. Based on the simulation for the bundle feed, it was anticipated that the lower setting value of the cylinder speed(RL) is to be set higher than the limiting operational speed. In addition, the higher setting value of the cylinder speed(RH) is to be set lower than the limiting cylinder speed for threshing. The computer simulation for the continuous spread feed showed that the lower the setting value of straw layer thickness(LL) was set, the shorter the correction time. However, if too low LL may be established, the feed rate could not reach to its desired rate.

• Proceedings of the KIPE Conference
• /
• 2020.08a
• /
• pp.261-262
• /
• 2020

본 논문은 DC/DC 위상천이 풀브릿지 컨버터의 과도상태 개선을 위한 듀얼모드 제어를 제안한다. 기존의 discontinuous conduction mode (DCM)과 continuous conduction mode (CCM)을 이용하여 운용하는 위상천이 풀브릿지 컨버터는 각 모드의 상이한 전압게인의 특성을 고려하지 않아 급격한 로드 변동시 출력 전압의 언더슈트 혹은 오버슈트가 크게 발생한다. 제안하는 듀얼모드 제어는 DCM과 CCM 각 모드 별개로 제어가 적용되고 출력 전류의 변화에 대응하는 적응형 feed-forward 제어가 적용되어 컨버터의 과도상태를 개선할 수 있다. 듀얼모드의 제어 방법의 성능과 타당성을 시뮬레이션을 통해 입증한다.

• Membrane Journal
• /
• v.2 no.1
• /
• pp.33-48
• /
• 1992

OSRO process was developed and it was confirmed more effective in ethanol concentrating process comparing to reverse osmosis process. It may be industrialized if more effective membrane for OSRO and reverse osmosis, which indicate the value greater than zero, it was shown that OSRO process was more effective than reverse osmosis for the ethanol concentration process. The decrease of feed concentration and flow rate and the increase of applied pressure made more effective operating conditions in OSRO process to concentrate ethanol. From the numerical esults for the multi-plates, theoretical DC values of reverse osmosis and OSRO process was increased as the umber of stages increased. DC values were increased with the increase of applied pressure in same number of stages. The theoretical values of DC by numerical calculation were corresponded to the experimental values within 15% tolerance. DC value was increased proportional to applied pressure and osmotic sink solution flow rate but it was decreased proportional to feed concentration and flow rate. The numerical calculation over the wide ranges inclading experimental condition was proposed in this study.

• Journal of the East Asian Society of Dietary Life
• /
• v.15 no.1
• /
• pp.20-28
• /
• 2005

The dietary effect of water extracts of Liriopis tuber(WELT) in the diabetic SD-rats on the level of blood sugar and serum cholesterol was investigated. The experimental plots divided into normal group(N), diabetic control(DC), 5% WELT-group(WELT-I) and 10% WELT-group (WELT-II). Each group was fed for 6 weeks, then continuously fed for 1 more week after streptozotocin injection. The loss of the body weight fed for one week after induction of the diabetes was 2.2～6.3% in the WELT-I and -II groups, but it was 18.6% in the DC-group. There was no significant difference in the feed intakes after diabetes induction between N-group and WELT-group, while it was significantly increased in DC-group. The feed efficiency ratios before diabetes induction were 1.70 in WELT-I group, 1.53～1.59 in the N, DC and WELT-II group, while the ratios after diabetes induction were 0.92 in DC-group, 1.51～1.83 in the N, WELT-I and -II group. While the amounts of water intakes for one week after diabetes induction was 625.4 mL in the DC-group, and it were 364.3～371.1 mL in the WELT-groups showing no significant difference with N-group. The excretion amounts of urine were 431.96 mL in DC-group for one week after diabetes induction, and it was 182～192.84 mL in WELT-groups. The ratios of liver weight against body weight were 2.74% in N-group, 2.93～2.96% in WELT-groups, but it was 4.01% in DC-group. The level of blood glucose in WELT-groups fed for one week after diabetes induction were 136.8～138.6 mg/dL showing no significant difference with N-group, but it was 357.8 mg/dL in DC-group. The level of serum triacylglycerol and serum total cholesterol were 93.8 and 68.7 mg/dL in N-group, 120.1 and 101.6 mg/dL in DC-group, 97.4～100.6 and 60.8～67.7 mg/dL in WELT-groups, respectively, showing no significant difference between N-group and WELT-groups. HDL-cholesterol/total cholesterol ratio were 0.63 in N-group, 0.57～0.67 in WELT -groups, which was significantly higher than that of DC-group(p<0.05). Atherogenic index were 0.58 in N-group, 0.49～0.74 in WELT-groups, but it was 1.32 in DC-group. The above results suggest that the WELT diets may have both preventive and curing effects against the diabetes.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.1654-1660
• /
• 2011

The korea Electric Railway feeder voltage is DC 1500V and AC 250000V. The auxiliary power supply of the vehicle auxiliary power units for domestic electrical feed has been developed with domestic technology hyeonchae mounted station, and domestic uses, such as voltage, have been exported to other countries. However, do not use at domestic that can be used for DC 3000V voltage auxiliary power unit does not develop, vehicle exports global. This has already been replaced by imported products from other nations is a real situation. Thus, our auxiliary power unit for the DC 3000V was developed, it will be exported to Ukraine. In this paper, We introduced circuit and structure of developed auxiliary power supply unit, and verified the performance with output characteristic of the auxiliary power unit.