• 아시안잔디학회지
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• 제11권4호
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• pp.311-320
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• 1997

This study was carried out to induce and maintain callus from 59 zoysiagrass lines, to know the effective disinfestation method for zoysiagrass stolon as explant and the difference in the response of callus induction among 59 lines, and to investigate the effect of medium, growth regulators, light, temperature, stolon part and internode position on callus induction and emhryogenic callus(E.C.) formation. The treatment of 0.lmg/L $HgCl_2$for 15 min resulted in no contamination and the highest callus induction(46.6%). Callus was induced from the 59 zoysiagrass lines. The callus growth of Z. japonica and Z. sinica was generally better than Z. matrella Ten cell lines whose callus and stolon grow fast in culture and in field, respectively were selected to he used for breeding. Callus induction was the most effective at 2.0mg /L of both 2, 4-D and picloram in MS medium. MS medium was the best for callus induction and growth while LS medium was the best for embryogenic callus and shoot formation. Callus induction and growth was better at 28, 31$^{\circ}C$. than 25$^{\circ}C$. and dark condition was better than light condition in MS me-dium containing 2mg/L 2,4-D. While callus induction was better with node part as explant than with internode part, callus growth and embryogenic callus formation was better with internode part. In 'Japonica 1', the first internode was the most effective in callus induction, but third internode was the best in '$M_2$ X $S_2$'.

• 한국산업융합학회 논문집
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• 제25권3호
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• pp.433-441
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• 2022

In general, in an emergency generator system for an electric facility including an induction motor load, an emergency power generation facility larger than the facility load capacity is built due to the initial starting current of the induction motor. In order to reduce this economic burden, various methods to reduce the inrush current of induction motors are applied to suppress the additional expansion of generators due to the reduction of power generation facilities and the increase in electrical facilities. Among these methods, when a system with a built-in soft start function of an induction motor using an inverter is built, it is the best way to reduce the inrush current of the induction motor to less than the rated current. However, in this case, the installation cost of the inverter to drive the induction motor increases. This paper proposes a soft start method of an induction motor by expanding the frequency and voltage control operation area of an emergency generator. In addition, proposed a speed calculation method based on power factor information, which is essential information for stable soft start of an induction motor, and a method for generating a speed command value of the governor for starting with maximum torque.

• 한국안전학회지
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• 제38권3호
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• pp.35-42
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• 2023

This study analyzed the current and temperature characteristics of major components of an induction motor during normal and abnormal operations as functions of the difference in the rated capacities of medium and large-sized motors widely used in industrial settings. The temperature rise equation of the induction motor winding was derived through locked-rotor operation experiments and linear regression analysis. When the ambient temperature is 40 ℃, the time to reach 155 ℃, the temperature limit of the insulation class (F class) of the winding of the induction motor, was confirmed to be 48 seconds for the 2.2 kW induction motor and 39 seconds for the 3.7 kW induction motor. This means that when the rated capacity is large or the installation environment is high temperature, the time to reach the temperature limit of the insulation class during locked-rotor operation is short, and the risk of insulation deterioration and fire is high. In addition, even if the EOCR (Electronic Over Current Relay) is installed, if the setting time is excessively set, the EOCR does not operate even if the normal and locked-rotor operation of the induction motor is repeated, and the temperature limit of the insulation grade of the winding of the induction motor is exceeded. The results of this study can be used for preventive measures such as the promotion of electrical and mechanical measures for the failure of induction motors and fire prevention in industrial sites, or the installation of fire alarm systems.

• 대한두경부종양학회지
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• 제17권1호
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• pp.32-37
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• 2001

Objectives: We performed this study to compare the short term results of induction chemotherapy and radiotherapy versus concurrent chemoradiotherapy in patients with locally advanced head and neck cancer. Materials and Methods: From Oct. 1985 to May 1998, 121 patients with locally advanced head and neck cancer were treated with induction chemotherapy and radiotherapy (induction group) or concurrent chemoradiotherapy (concurrent group), and a retrospective analysis was done. Induction chemotherapy was done for 97 patients, and concurrent chemotherapy for 24 patients. Age, sex, performance status, and pathologic types were evenly distributed between two groups. Primary site showed nasopharynx(72.2%), oropharynx(27.8%) in induction group, and nasopharynx(50%), oropharynx(50%) in concurrent group. Chemotherapy regimen was CF(cisplatin and 5-fluorouracil) for 67 patients and CVB (cisplatin, vincristine, bleomycin) for 30 patients in induction group, and CF for all of 24 patients in concurrent group. Proportion of patients treated with more than 2 cycles of planned chemotherapy was 94.8% in induction group and 87.5% in concurrent group. Conventionally fractionated radiotherapy with daily fraction size of 1.8-2.0Gy and 5 fractions/week was done. Total dose was 61-95Gy (median 73.4Gy) for induction group, and 69.4-75.4Gy (median 69.4Gy) for concurrent group. Follow-up time was 4-161 months (median 38 months) for induction group, 7-35 months (median 21.5 months) for concurrent group, respectively. Results: According to treatment modality, overall 2-year survival rates were 68.0% for induction group, 74.3% for concurrent group (p>0.05). two-year disease-free survival rates were 51 % and 74% (p=0.05). Complete response rates were 67.4% for induction group and 83.3% for concurrent group (p=0.09). The incidence of grade 3-4 hematologic toxicity (2.1% vs. 25%, p=0.001) and grade 3-4 mucositis (9.3% vs. 37.5%, p=0.002) during radiotherapy was higher in concurrent group. Conclusion: Concurrent chemoradiotherapy showed a trend of improvement in short-term survival and treatment response when compared with induction chemotherapy and radiotherapy in locally advanced head and neck cancer. A more controlled randomized trial is needed.

• 한국산학기술학회논문지
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• 제8권4호
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• pp.748-757
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• 2007

본 논문은 대용량 유도전동기가 기동할 때 발생하는 큰 돌입전류로 인해 PCC(Point of Common Coupling)에 심한 전압 강하가 발생하게 되어 기동에 실패하는 문제를 해결하기 위해 대상 유도전동기의 기동 특성과 배전계통을 모델링하고 시뮬레이션을 수행함으로써 유도기 기동시에 전압저하 현상을 해석하였다. 문제가 되는 유도전동기는 2500KVA 용량의 펌프용 농형 유도전동기로 리액터 기동법을 채용하고 있다. 2500KVA 유도전동기 한대의 기동에는 문제가 없으나 기동 완료 후 PCC 전압이 다소 떨어진다. 하지만 추가로 동일 용량의 유도전동기가 기동하게 되면 PCC의 심한 전압강하로 기동에 실패하게 되는 문제가 발생하였다. 이러한 문제 해결을 위해 본 논문에서는 실제 기기의 기동시 토크-속도 곡선을 이용한 유도전동기의 기동 특성을 정확히 모델링하고 시뮬레이션을 수행하여 두 대의 대용량 유도전동기가 순차적으로 기동에 성공할 수 있는 적절한 전압보상 방안을 제안하였다. 본 논문에서 논의되는 대용량 유도전동기는 한국수자원공사의 취수장에서 운전되고 있으며 대상 유도전동기 및 배전계통은 PSCAD/EMTDC 소프트웨어를 사용하여 모델링 및 시뮬레이션을 수행하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.848-850
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• 2002

Single phase induction motor is directly used usual source, it can be a source of an appliance such as mechanical fan, refrigerator, washing machine, etc. Especially capacitor-run single phase induction motor is suitable to make more inexpensive and high efficient products because it is more high efficiency, and good to start than other single phase induction motors. Generally, voltage and current of capacitor-run single phase induction motor transfer to the part of positive phase and negative phase based on two motor theory. In this paper, we simulate the torque characteristics to capacitance variation from single phase induction motor's equivalent circuit. Through the test using the real motor, we compare and investigate the maximum torque of run state related with capacitance and the adequacy of the converted model.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.57-62
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• 2003

A general procedure of obtaining reliable one-step kinetics model for hydrocarbon mixture from the fully detailed chemistry is described iin this study. One-step theoretical formulation of the induction parameter model IPM uses a theoretical reconstruction of the induction time database obtained from a detailed kinetics library. Non-dimensional induction time calculations is compared with that of detailed kinetics. The IPM was latter implemented to fluid dynamics code and applied for the numerical simulation of detonation wave propagation. The numerical results including the numerical smoked-foil record show the all the details of the detonation wave propagation characteristics at the cost around 1/100 of the detailed kinetics calculation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.194-197
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• 2009

The TR forging is a kind of continuous grain flow forging. The preform of crank shaft for TR forging process was a round bar with a ring groove. In the first stage, the preform was partly heated by induction heating and then forged by vertical and horizontal force in sequence. In this study, the simulation process of induction heating was proposed to evaluate the temperature distribution of preform for TR forging. The equivalent circuit method was adopted to find coil current of the preform with a various dimensions and power levels. With these results, the coupled electromagnetic and transient thermal analysis for induction heating was performed to evaluate the temperature distribution at the preform of crank shaft during induction heating process. This FE analysis technique with equivalent circuit method was verified by comparing the analysis results with the experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.195-198
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• 1997

This paper proposes the effective compensation method of the rotor time constant of induction motor. An indirect vector control method is highly dependent on the motor parameters. To solve the problem of performance degradation due to parameter variation in an indirect vector control of induction motor, we compensate the rotor time constant by current error feedback. The proposed method is a simple on-line rotor time constant compensation method using the information from terminal voltages and currents. As the current error, difference between current command and estimated current, approaches to zero, the value of rotor time constant in an indirect vector controller follows the real value of induction motor. This scheme is valid transient region as well as steady state region regardless of low or high speed. This method is verified by computer simulation. For this, we constructed the simulation model of induction motor, indirect vector controller and current regulated PWM (CRPWM) voltage source inverter (VSI) using SIMULINK in MATLAB.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.69-74
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• 2001

In this Paper are described the indirect induction heated boiler and induction heated hot air producer using the voltage-fed series resonant high-frequency inverter which can operate in the frequency range from 20kHz to 50kHz. A specially designed induction heater, which is composed of laminated stainless assembly with many tiny holes and interconnected spot welding points between stainless plates, is inserted into the ceramic type vessel with external working coil. This working coil is connected to the inverter and turbulence fluid through this induction heater to moving fluid generates in the vessel. The operating performances of this unique appliance in next generation and its effectiveness are evaluated and discussed from a practical point of view.