• 농업과학연구
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• 제38권2호
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• pp.309-314
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• 2011

The purpose of this study is to select the dominant discharge which mostly affects the formation of the channel shape in Yo-Stream. So far, three different discharge conditions such as bankfull discharge, discharge of a specific recurrence interval, and effective discharge have been considered as an indicator of dominant discharge. Therefore, three different discharge conditions were studied and based on the study results, dominant discharge was selected for Yo-Stream. When comparing bankfull discharge and effective discharge at Beonam stream gaging station, it has turned out that effective discharge was 10 $m^3$/sec, which is 6 times greater than bankfull discharge of 58.83 $m^3$/sec. Furthermore, when comparing bankfull discharge and discharge of a specific recurrence interval, bankfull discharge was quite similar to discharge with recurrence interval of 1.52 years. Previous study results also indicate that dominant discharge occurs with recurrence interval of similar duration. Therefore, discharge of 58.83 $m^3$/sec was considered as a dominant discharge, which corresponds to discharge with recurrence interval of 1.52 years.

• 성인간호학회지
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• 제18권3호
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• pp.436-445
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• 2006

Purpose: The purpose of this study was to examine the effect of the discharge education program on compliance with the sick role behavior for patients having undergone cerebrovascular surgery. Method: Research was done using a posttest only design. The subjects were 60 patients who were admitted to the neurosurgery unit at C.N.U. Hospital in G. City and were divided into the experimental and control groups. The discharge education program were intervened two times in the experimental group by the researcher; the first one was at the time of discharge using a booklet about knowledge related to disease and compliance, and the other one was a telephone education session after a week from discharge. Data were collected two times by interview and telephone using questionnaires from January 19, to June 10, 2000. The first one was at hospital before discharge, and the other one was one month later from discharge. Data were analysed by $\chi^{2}$, t-test, ANOVA, and Pearson's correlation. Results: The experimental group showed a higher score of compliance(t=2.772, p=.008) than those of the control group, but knowledge about CVD was not significant between the two groups(p>.05). Conclusion: The discharge education program was effective on the compliance of the patients having undergone cerebrovascular surgery.

• 반도체디스플레이기술학회지
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• 제17권3호
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• pp.90-94
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• 2018

In this paper, we applied a three-level T-type inverter with the one more voltage level than two-level inverter. However, the three-level T-type inverter has a systematic problem with voltage unbalances. So neutral point control is essential. Therefore, the voltage unbalance problem of the three - phase inverter was confirmed to be controlled within 5V using the neutral point control algorithm in charge and discharge mode. In addition, total harmonic distortion was reduced in three phases (u phase, v phase, w phase) when neutral point control was performed in charging mode and also in three phases (u phase, v phase, w phase) in discharge mode. In this paper suggests a neutral point control algorithm to solve the voltage unbalance of a three-level T-type inverter, and shows the improvement of the performance of the proposed algorithm through experiment.

• 조명전기설비학회논문지
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• 제16권1호
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• pp.13-19
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• 2002

새로운 방전 AND gate를 가지는 플라즈마 디스플레이 패널이 제안되었고 이를 검증하기 위한 구동 회로 시스템이 개발되었다. 그리고 방전 AND gate의 동작이 검증되었다. 방전 AND gate는 8$\mu\textrm{s}$의 동작속도와 20V의 동작마진을 가지고 동작하였으며 인근 주사라인의 방전을 정확히 제어할 수 있다는 것을 알았다. 이 방식은 직류 방전을 사용함으로 종래의 방전 AND gate에 비해 손쉽게 방전을 제어할 수가 있다. 더구나 AND gate의 입력방전과 출력방전이 분리되어 동작하기 때문에 디스플레이 방전이 AND gate를 통과하는 것을 방지할 수 있다. 그러므로 대화면 플라즈마 디스플레이에의 적용이 가능하고 주사방전이 화질에 영향을 주지 않으므로 명암비의 저하가 일어나지 않는다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.574-578
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• 2008

In order to achieve thrust vector control and discharge stabilization in Hall thrusters, the azimuthal nonuniformity of propellant flow rate in an acceleration channel was created. A plenum chamber was divided into two rooms by two walls and propellant flow rate supplied to each section was independently controlled. In a magnetic layer type Hall thruster, steering angle of up to ${\pm}2.3$ degree was achieved. In an anode layer type Hall thruster, discharge current oscillation amplitude was decreased with the normalized differential mass flow rate.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.290-293
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• 2012

플라즈마 유동제어를 위한 DBD 엑츄에이터 해석 및 성능 평가를 수행하였다. DBD 엑츄에이터의 방전조건에 따른 유속 특성을 밝히고 최적의 방전조건을 찾기 위해 실험 장치를 제작하였다. 동일한 유전체에서 방전조건에 따른 플라즈마 엑츄에이터 표면에서의 유속을 측정하였다. 방전전압에 비례하여 유속이 증가하였다. 유동의 특성을 좀 더 자세히 파악하기 위해 CFD해석을 통하여 실험결과와 해석결과를 비교하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.499-500
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• 2006

The electrode wear in micro-EDM significantly deteriorates the machining accuracy. In this regard, electrode wear needs to be compensated in-process to improve the product quality. Therefore, there are substantial amount of research about electrode wear. In this study a control method for micro-EDM using discharge pulse counting is proposed. The method is based on the assumption that the removed workpiece volume is proportional to the number of discharge pulses, which is verified from experimental results analyzing geometrically machined volume according to various number of discharges. Especially, the method has an advantage that electrode wear does not need to be concerned. The proposed method is implemented to an actual micro-EDM system using high speed data acquisition board, simple counting algorithm with 3 axis motion system. As a result, it is demonstrated that the volume of hole machined by EDM drilling can be accurately estimated using the number of discharge pulses. In EDM milling process a micro groove without depth variation caused by electrode wear could be machined using the developed control method. Consequently, it is shown that machining accuracy in drilling and milling processes can be improved by using process control based on the number of discharge pulses.

• 한국토양비료학회지
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• 제48권6호
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• pp.671-676
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• 2015

Control of surface runoff from upland soil is essential to reduce nonpoint source pollution. The use of non-woven fabric as a soil cover can be helpful to control surface runoff. The field experiment was conducted to evaluate the furrow cover effects of black non-woven fabric on the nutrient discharge from upland soil used for red pepper cultivation. The experimental plots consisted of chemical fertilizer (CF), cow manure compost (CMC), and pig manure compost (PMC) treatment. Each nutrient material treatment plot has control (no furrow cover (NFC)) and black non-woven fabric cover treatment, respectively. The amount of nutrient application was chemical fertilizer of $190-112-149(N-P_2O_5-K_2O)kgha^{-1}$, cow manure compost of $29.5tonha^{-1}$, and pig manure compost of $7.9tonha^{-1}$ as recommended amount after soil test for red pepper cultivation. Compared to control (NFC), furrow cover treatment with black non-woven fabric reduced the amount of T-N discharge by 50% at CF treatment, 36.9% at CMC treatment, and 44.8% at PMC treatment. Furrow cover treatment with black non-woven fabric reduced the amount of T-P discharge by 37.1% at CF treatment, 49.9% at CMC treatment, and 63.4% at PMC treatment compared to control (NFC). The production of red pepper did not show significant difference. There was no weed occurring in furrow cover treatment plots with black non-woven fabric. Results from this study showed that the furrow cover with black non-woven fabric could play a significant role in reduce nutrient discharge from upland soil used for red pepper cultivation.

• International Journal of Fluid Machinery and Systems
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• 제4권3호
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• pp.334-340
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• 2011

Turbo-pumps have weak points, such as the pumping operation is unstable on the positive slope of the head curve and/or the cavitation occurs at the low suction head. To improve simultaneously both weak points, the first author invented the unique pumping unit composed of the tandem impellers and the peculiar motor with the double rotational armatures. The front and the rear impellers are driven by the inner and the outer armatures of the motor, respectively. Both impeller speeds are automatically and smartly adjusted in response to the pumping discharge, while the rotational torques between both impellers/armatures are counter-balanced. Such speeds contribute to suppress successfully not only the unstable operation at the low discharge but also the cavitation at the high discharge, as verified with the axial flow type pumping unit in the previous paper. Continuously, this paper investigates experimentally the effects of the tandem impeller profiles on the pump performances and the rotational speeds against the discharge, using the impellers whose loads are low and/or high at the normal discharge. The worthy remarks are that (a) the unstable operation is suppressed as expected and the shut off power is scarcely large in the smart control, (b) the blade profile contributes to determine the discharge giving the maximum/minimum rotational speed where the reverse flow may incipiently appears at the front impeller inlet, (c) the tandem impeller profiles scarcely affect the rotational speeds, while the loads of the front and the rear impellers are same, but (d) the impeller with the low load must run faster and the impeller with the high load must run slower at the same discharge to take the same rotational torque, and (e) the reverse flow at the inlet and the swirling velocity component at the outlet of the front impeller with the high load require making the rotational speed of the rear impeller with low load fairly faster at the lower discharge.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.527-528
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• 2012

플라즈마 유동제어를 통한 공기저항저감을 위해 DBD(Dielectric Barrier Discharge) 플라즈마 구동기를 설계하였고, 2D 시험모델의 풍동시험을 통해 항력저감을 측정하였다. 풍속이 없는 경우에는 유동박리 및 표면마찰저항이 존재하지 않으므로 플라즈마 유동제어를 통한 항력저감도 없었다. 2m/s의 풍속에서 유동박리제어를 통해 항력이 9.7%까지 감소됨을 확인하였으며, 풍속이 증가할수록 항력저감은 감소하였다.