• 전력전자학회논문지
• /
• 제14권2호
• /
• pp.142-149
• /
• 2009

본 논문은 단위 역률을 갖도록 직접 시비율 펄스폭 변조 방식으로 제어되는 3상 매트릭스 컨버터의 평형 및 불평형 부하시의 동작 특성을 고찰한다. 시스템의 해석으로부터 얻어진 중요하고 유용한 사실을 정리하면 다음과 같다. (1) 단위 역률 제어 알고리즘은 부하측의 변수에 의해서가 아니라 입력전압에 의하여 정해진다. (2) 평형 3상 부하가 리액티브 부하인 경우만 아니라면 입력측 역률을 1로 만들 수 있다. (3) 불평형 선형부하의 경우, 매트릭스 컨버터의 등가입력 특성은 비선형저항과 같다. (4) 입력 주파수와 출력 주파수가 특정한 관계를 가질 때, 입력측의 각상은 동일한 평균전력 분담률을 갖는다. 해석의 타당성과 유효성은 시뮬레이션과 실험결과를 통하여 검증하였다.

• 동서간호학연구지
• /
• 제11권1호
• /
• pp.12-24
• /
• 2005

The objective of this research is to explore the attitude on the transfer of duty post and job satisfaction of nurses. The subjects of this study were 512 nurses who have engages in the K-university hospital. The measurement tool consisted of attitude on the transfer of duty post, job satisfaction. The collected data have been processed using SPSS/PC 12.0 program: The results of this study were as follows: 1. The age the subjects was from 21 to 56 and average 32, blow 3 years experience in current duty post occupied most by 37.1%. The experience of the transfer of duty post showed 50.2%. 51.4% of the nurses wanted $3{\sim}5$ years as the suitable periods for the transfer of duty post showing the highest degree of frequency. 2. The positive degree of the attitude on the transfer of duty post of the nurses appeared average (3.36) to maximum evaluation point 5, and when asked about 4 factors the nurses wanted individual development most by (3.72) while administration management was lowest by (2.65). The satisfaction degree on their job appeared to be average (3.06) to the maximum point 5, and when asked about 7 factors, interaction appeared to be the highest by (3.63), here we saw that interaction was the most important elevating factor of the job satisfaction degree. 3. In the relation of the attitude on the transfer of duty post according to general characteristics, there were the significant difference according to whether it is necessary for the current duty post and periodical duty post to be transferred. In the relation between general characteristics and job satisfaction degree there were the significant differences according to age, marital status, education, position of nurse, hospital clinical nursing experiences, satisfaction degree with current post and the hope of the transfer of duty post from current post. 4. The correlation between attitude on the transfer of duty post and job satisfaction degree was positive relation(r=0.137, p=.002), that the higher the degree of positive attitude on the transfer of duty post the higher the degree of job satisfaction.

• 간호행정학회지
• /
• 제9권1호
• /
• pp.141-150
• /
• 2003

Purposes : This study was to investigate the job stress and turnover intention related to transfer of duty post of staff nurses working in general hospitals. Method : The subjects of this study were 384 staff nurses working in 6 general hospitals, with more than 200 beds, in Daegu and Kungbuk province in Korea. Data were collected through questionnaires and from Sep. 15 to Oct. 6, 2001. The used tool for measuring the degree of job stress was developed by Kim and Gu(1984) and the used tool for measuring the degree of turnover intention was developed Kim and Lee(2001). The data were analyzed into frequency, percentage, mean, standard deviation, t-test, ANOVA, Tukey's post hoc contrast, Pearson's correlation coefficient according to the purpose of study by use SPSS Win 10.0 statistical program. Results : The following are the results of the study: (1) Average score of the job stress, turnover intention of resignation of the subjects were 2.64 and 4.44. (2) The result of the analysis of job stress related to transfer of duty post was higher in job stress; not satisfaction of current duty post(t=-2.06, p=0.04). (3) The result of the analysis of turnover intention related to transfer of duty post was higher in turnover intention; period of the an advance notice when transfer to current duty post less than 7day(F=3.55, p=0.02), not satisfaction of current duty post(t=-2.45, p=0.02), want the transfer from current duty post(t=3.68, p=0.00). (4) The study reveals that there was statistically significant positive correlation relationship between job stress factors and turnover intention(r=.183, p=.000). Conclusion : The study which relating to period of the an advance when transfer and satisfaction of current duty post and reconsideration of transfer of duty post shows statistically significant difference between job stress and turnover intention. Therefore it is regarded that is needed to set a period of profer advance notice, grip on unsatisfactory factor of current duty post and intervention and management of the subjects were wanted transfer of duty post.

• 전력전자학회논문지
• /
• 제22권6호
• /
• pp.527-534
• /
• 2017

This paper proposes a new DC link voltage controller for a single-phase power factor correction (PFC) boost converter. The load current of the PFC boost converter affects the capacitor current, whereas the load current changes the output voltage. However, previous works that compensate output current have failed to consider the relationship between load current and duty. Thus, they also fail to maintain a constant output voltage if the load fluctuates under the conditions of a non-rated input voltage. By considering the duty in the load current compensation, the proposed method improves the load transient response regardless of the input voltage. To demonstrate its effectiveness, the proposed method is compared with other control methods by conducting PSM simulations and experiments under a rapidly changing load.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1996년도 추계학술대회 논문
• /
• pp.52-57
• /
• 1996

Conductive Ceramic Matrix Composite(CMC) of TIC/Al2O3 and Metal Matrix Composite (MMC) of SiC/Al were experienced by the die sinking Electrical Discharge Machining(EDM) for different current and duty factor according to negative polarity. Inthis experimental study Material Removal Rate(MRR) maximum surface roughness four point bending stress distribution and Scanning Electron Microscopy(SEM) Photographs were analysed. the higher MRR was obtained for CMC than MMC but slowly decreased around duty factor of 0.67 for MMC and better surface morphology was found CMC than MMC. The SEM photographs of discharge traces for CMC showe uniform shape about 100 to 200${\mu}{\textrm}{m}$ in diameter but MMC showed irregular shape.

• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
• /
• pp.74-78
• /
• 2003

This paper shows the dosimetric uncertainties of electromagnetic field at in-vivo and in-vitro experiments. For more accurate consequences of these researches, we have tried to find out any correlations among output power, power density and specific absorption rate(SAR) with the results of in-vivo, in-vitro tests and SAR reports of cellular phone and PDA. In the case of in-vivo tests, the power density has close statistical correlations with SAR value and in the event of in-vitro tests, the output power has considerable statistical correlations with SAR containing duty factor. On the other hand, we found that both power density and output power don't have any close correlations with SAR. And, we obtained fitted regression form among frequency, power density and SAR containing duty factor through multiple linear regression analysis.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1999년도 춘계학술대회 논문집
• /
• pp.245-250
• /
• 1999

The experimental study of die-sinking electrical discharge machining for alloy tool steel of STD-11 with circular electrode was conducted for various conditions of the peak current and duty factor with the change of internal size of electrode for distributing the amount of dielectric flow through the electrode. From this study, the material removal rate(MRR) was found to be increased with the peak current and duty factor. The more MRR was obtained for the case of electrode inside diameter of 10mm. The surface roughness and roundness values were analyzed regularity under various conditions, and these values were not affected by the inside diameter change of electrode.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2013년도 추계 학술논문 발표대회
• /
• pp.90-91
• /
• 2013

In the field of nuclear power construction, management and the systematic construction is very necessary. For more efficiently managing, analysis of influence factors and productivity is indispensable now. On this research, we collected the data from the nuclear power plant which is located in Korea. We analyzed the productivity and influence factors. As a result, productivity was 0.75(㎡/man·hour).On one hand, the productivity should be personnel, weather and whether there is a night duty or not. On the other hand, work crew depends upon operators, formwork amount, the presence or absence of night duty.

• 전기학회논문지
• /
• 제60권7호
• /
• pp.1372-1377
• /
• 2011

This paper proposes the control method of MPPT(maximum power point tracking) for the wind energy generation system using the duty ratio control of boost type DC-DC converter. For a lower cost and a higher reliability, the wind and the generator velocity sensors are removed. MPPT control is implemented by changing the duty ratio of the boost converter. Chain rule is applied by using each function. The grid side inverter is controlled to regulate unity power factor. The proposed control method was analyzed mathematically and verified by the computer simulation using PSIM.

• International Journal of Control, Automation, and Systems
• /
• 제6권5호
• /
• pp.660-669
• /
• 2008

This paper presents a new carrier based pulse-width modulation (PWM) method for matrix converters. By using the concept of average over one switching period, the modulation algorithm and the required equations are derived to synthesize the desired output voltage and to achieve the controlled input power factor. The proposed method uses a continuous carrier and the predetermined duty ratio signals to directly generate the gating signals and, thus, is referred to as "direct duty ratio PWM (DDPWM)". The feasibility and validity of the proposed method were verified by simulation and experiment.