• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.2043-2050
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• 2017

This paper presents two MPC (Model Predictive Control) based charging and discharging algorithms of BESS (Battery Energy Storage System) for capacity firming of wind generation. To deal with the intermittency of the output of wind generation, a single BESS is employed. The proposed algorithms not only make the output of combined systems of wind generation and BESS track the predefined reference, but also keep the SoC (State of Charge) of BESS within its physical limitation. Since the proposed algorithms are both presented in simple if-then statements which are the optimal solutions of related optimization problems, they are both easy to implement in a real-time system. Finally, simulations of the two strategies are done using a realistic wind farm library and a BESS model. The results on both simulations show that the proposed algorithms effectively achieve capacity firming while fulfilling all physical constraints.

• 전기학회논문지P
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• 제63권4호
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• pp.254-259
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• 2014

In this paper, we describe construction of a wind stabilization demo-site and effects of output power control of wind turbines for suppression of ramp rate using ESS (Energy Storage System). It is difficult to control the output power of distributed generator such as wind turbine which of variation is very large. If the large capacity wind farm be interconnected into power system may cause blackout due to Power Quality. For these reasons, the international standards such as Grid-Code is limited to less than 10 [%/min] of renewable energy ramp rate. The case of Korea, government actively conducts propagating large-scale renewable energy for green growth policy, to interconnecting more renewable energy into power system is necessary for stabilization technology. For these reasons, the POSCO consortium has constructed a wind stabilization demo-site that is configured as 500 [kWh] battery energy storage systems can output up to 3 [C-Rate] and two wind turbines rated 750 [kW]. In POSCO consortium, which implements various methods stabilizing output power of wind turbine such as smoothing, section firming and ramp control, we derive the results of long-term demonstration that can be controlled to satisfy to the international standard about ramp rate [%/kW] of wind turbine output power.

• 한국수산과학회지
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• 제36권2호
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• pp.74-79
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• 2003

The functional properties such as a firming maintenance capacity for fermented vegetables, protein coagulation capacity antibacterial activity, calcium and peroxide absorption capacity of calcium powder of cuttle bone treated with acetic acid (ATC) were examined. In the Korean pickled cucumbers (20 days), the calcium content of ethanol insoluble solids was 5,264.9 mg/100 g and this value was higher than that of control (2,036.4 mg/100 g). Protein coagulation capacity of ATC was $0.9\%$ and its calcium absorption capacity was $49.3\%.$ The peroxide absorption capacity of ATC was shown $0-1.1\%$ range. Antibacterial activity was detected above $0.2\%.$ The ATC was effective in a firming maintenance of fermented vegetables (cucumber), coagulation capacities for soybean milk and antibacterial activity. The ATC was not effective in clarifying wastewater. Peroxide absorption capacity toward linoleic acid could not be checked by ATC, but its calcium absorption ratio was high compared to that of commercial calcium powder.

• 한국식품영양학회지
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• 제14권1호
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• pp.40-45
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• 2001

유화제가 찹쌀떡의 품질에 미치는 영향을 규명하기 위하여 monoglyceride, lecithin, sugar ester를 찹쌀분말 대비 각각 0.5%, 1%씩 혼합하여 falling number, RVA를 측정하고 찹쌀떡을 제조한 후 5~7$^{\circ}C$ 사이에 서 냉장 보관하면서 색차계, 수분활성도, rheometer 등을 조사하였다. Falling number는 control과 mono-glyceride, lecithin 0.5%, 1%를 사용한 것은 큰 차이를 보이지 않았으나 control의 77.5에 비하여 sugar ester의 경우0.5%와1% 사용시 각각 88.4, 81로 높게 나와 sugar ester가 점도를 높이는 것을 알 수 있었다. 찹쌀 분말의 호화개시온도는 66.78$^{\circ}C$이었으며 유화제를 첨가한 것은 66.45~67.05$^{\circ}C$로 유화제가 호화개시온도에 큰 영향을 미치지 못하였다. 최고점도는 lecithin이 227 RVU, 1% sugar ester가 228.5로 control 231.5에 비하여 낮아졌으며 그밖에 유화제는 최고점도 및 최종 점도가 control에 비하여 높아졌고 특히 1% sugar ester 사용한 것의 최종점도는 199.5 RVU로 가장 높게 나와 falling number와 유사한 경향을 보였다. 유화제를 첨가하여 찹쌀떡의 제조한 결과 유화제를 첨가하지 않은 경우보다 노화가 지연되었으며 1% sugar ester 첨가시 지연 효과가 가장 크게 나타났다. 수분 활성도는 저장 5일째 1% sugar ester를 사용한 것이 0.875로 가장 낮았고 유화제를 사용하지 않은 것이 0.911로 가장 높게 나와 유화제가 찹쌀떡의 수분활성도를 낮추었으며 그 가운데 sugar ester의 효과가 가장 좋았다.

• Journal of Biosystems Engineering
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• 제33권2호
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• pp.83-93
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• 2008

In order to save labor and cost, direct seeding has been considered as an important alternative to the machine transplanting in rice cultivation. Current direct seeding machines for rice in Korea drill irregularly under various operating conditions. This study was conducted to develope a precision seeder which enables the accurate, even-spaced in row placement of rice seeds at uniform depths of 3-4 cm on dry paddy. Design, construction and performance evaluation of the precision seeder were carried out. The tractor rear-mounted type 8-rows precision seeder which performs seeding in addition to fertilizing, ditching, and rotary tilling works on dry paddy was developed. Main components of the seeder were ditcher and leveller, rotary tiller, powered roller type furrow opener, seeding device, powered roller type furrow covering and firming device, hydraulic unit, seeding speed control system, power transmission system, hitch and frame. Ditching, furrow opening, and seed covering and firming performances were good and seeding depths of 2-4 cm could be maintained. Planting accuracies and planting precisions were within 13.6%, and 31.2%, respectively, for planting space of 15 cm, and seeding velocity of 0.5 m/s. These mean variations of average planting space were within 2.1 cm, and 90% of seeds in a hill were seeded within 4.7 cm of hill length, respectively. Error ratios between setting planting space and measured average planting space were shown within 6.7%. Therefore the seeder showed good planting performance up to seeding velocity of 0.5 m/s in field tests. And field capacity of the seeder was about 0.28 ha/hour.

• 대한치과보철학회지
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• 제44권5호
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• pp.549-560
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• 2006

Purpose : This experiment examined the effects of anodization on commercially pure titanium implant fixtures. Material & methods : The implant fixtures were anodized at three different voltage levels, producing three different levels of oxidation on the surface of the fixure. Implant were divided into four groups according to the level of oxidation. Group 1 consist of the control group of machined surface implants, Group 2 implants were treated by anodizing to 100 voltage, Group 3 implants were treated by anodizing oxidation to 200 voltage Group 4 implants were treated by anodizing oxidation to 350 voltage. Surface morphology was observed by Scanning Electron Microscope(SEM) and the surface roughness was measured using NanoScan $E-1000^{\circledR}$. Implantation of the fixtures were performed using New Zealand white rabbits. $Periotest^{\circledR}$ value(PTV) resonance frequency analysis(RFA), and removal torque were measured in 0, 2, 4, 8, 12 weeks after implantation. Results : The results of the study were as follows: 1. Values for the measured surface roughness indicate statistically significant differences in Ra, Rq, and Rt values among group 1, 2, 3, and 4 at the top portion of the thread,(p<0.05) while values at the base of the threads indicated no significant difference in these values. 2. A direct correlation between the firming voltage, and surface roughness and irregularities were observed using scanning electron microscope. 3. No statistically significant differences were found between test groups regarding $Periotest^{\circledR}$ values. 4. Analysis of the data produced by RFA, significant differences were found between group 1 and group 4 at 12 weeks after implantation.(p<0.05) Conclusions : In conclusion, no significant differences could be found among test groups up to a certain level of forming voltage threshold, beyond this firming voltage threshold, statistically significant differences occurred as the surface area of the oxide layer increased with the increase in surface porosity, resulting in enhanced bone response and osseointegration.

• 대한간호학회지
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• 제15권1호
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• pp.59-75
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• 1985

Accepting the health as the fundamental human right, the nation and society came to admit the duty to give it to all the people. Korean government is expanding the Primary Health Care as one of the policies for developing the people's health by the lead of community. Like this current situation the School Health Service which is the center of community Health Service schould be active to keep, promote and maintain the health of students and teachers. This investigation was attempted to help to establish the basis of the Health Education Program which would perform the health education efficiently and bring the reforming of student's health control, by measuring the degree of junior high school student's practice concerning health care and con-firming the relationship of knowledge, concern and level of health. The subjects for this study were made up 296 boys at the third grade in a school, located in Seoul. The tool for this study was questionaire. Data were collected for five days, September 22∼26, 1983. The investigators explained the students how to answer the questions of the survey questionaire and then collected the survey cards immediately. The data were analyzed by means of percentages, Pearson Correlation Coefficient and Stepwise Multiple Regression. The results of this study are as follows. 1. The subjects' reaction to the practice concerning Health Care; According to the average proportion of practice concerning health care, subjects' practice in the aspect of Infectious Disease Care is the highest 82.4％ and they showed their practice in the aspect of the accident prevention by 77.5% and in the aspect of mental health by 74.8%. Their practice in the aspect of personal hygiene and daily lifehabit is the lowest 71.2%. 2. Health Knowledge; The whole mark distribution of health knowledge is ranged from the lowest 4 point to the highest, 30 point, therefore point range is 26.0. The Average point is 16.58. 11.2% of students solved more than two thirds of personal knowledge levels. 81.4% of students did more than one third of them. 7.415 of students did less than one third of them. 3. Health Concern; The Students of the average 3.99 point respond positively to the question about the health concern, ‘They think health is more important than money’, this is the highest rate. The students of the average 2.78 respond“when they are sick, they enter the appointed hospital where they own choose”, while it is the lowest. 4. Subjects' response to the health level are at follow: Very healthy 26.0%, healthy 47.0%, less healthy 10.5%, 34.9% of them have ever been sick within two weeks, the number of symptoms they reported amount to 114 and the number of cases poi one person is 0.35. 5. The hypotheses test about the practice concerning health care and the factor which effect on it. 1) The main first hypothesis:“The more knowledge of health the subjects have, the better they practice health care.”was accepted. (r=0.1582, p <0.05) 2) The minor first hypothesis:“The more interest in health subjects have, the better they practice”was accepted. (r=0.4354, p ＜0.001) 3) The minor second hypothesis;“The healthier subjects are, the better they practice health care”was accepted. (r=0.1069, p＜0.05) As other test, partical correlation test is performed in other refine whether health knowledge, a fact influencing the students practice concerning health care, is associated with the practice after controlling the third variables. First, after controlling health concern, the correlation of health knowledge and practice concerning health care was kept. (r=0.1347, p <0.005) Second, after controlling health level, the correlation of health knowledge and practice concerning health care was kept. (r=0.1526, p <0.005) And finally, after controlling economic state, the correlation of health knowledge and practice concern-ing health care was kept. (r=0.1413, p <0.05) Additionally Stepwise Multiple Regression between practice concerning health care and variables. 1.6591 of compliance was explained with the know-ledge (F=5.584, p <0.05), 20.0% of compliance was explained with the health concern added to knowledge. (F=63,213, p <0.005) As the above, health knowledge obviously have effects on the practice about the health care. But, contrary to researcher's expectation, health concern has more affects than health knowledge. Therefore, we must grope the plan to enhance health concern through the regular curriculum and systematic health education for students. Besides, we must study further on, to find the factors which have affect on the practice concerning health care.