• Journal of the Korean Solar Energy Society
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• 제26권4호
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• pp.17-23
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• 2006

This paper proposes a novel active frequency drift (AFD) method for the islanding prevention of grid-connected photovoltaic inverter. To detect the islanding phenomenon of grid-connected photovoltaic (PV) inverters concerning about the safety hazards and the damage to other electric equipments, many kinds of anti-islanding methods have been presented. Among them, AFD method using chopping fraction enables the islanding detection to drift up (or down) the frequency of the voltage during the islanding situation. In this paper, injecting the periodic zero current into the basic AFD method is proposed. This proposed method shows the analytical design value of cf to meet the test procedure of IEEE Std. 1547 with various load conditions. Detection of islanding is verified using simulation tool PSIM.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.250-254
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• 2007

As photovoltaic(PV) power generation systems become more common, it will be necessary to investigate islanding detection method for PV systems. Islanding of PV systems can cause a variety of problems and must be prevented. However, if the real and reactive powers of the load and PV system are closely matched, islanding detection by passive methods becomes difficult. Also, most active methods lose effectiveness when there are several PV systems feeding the same island. The active frequency drift positive feedback method(AFDPF) enables islanding detection by forcing the frequency of the voltage in the island to drift up or down. In this paper the research for the minimum value of chopping fraction gain applied digital phase-locked-loop (DPLL) to AFDPF considering output power quality and islanding prevention performance are performed by simulation and experiment according to IEEE Std 929-2000 islanding test.

• Journal of the Korean Solar Energy Society
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• 제27권2호
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• pp.37-44
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• 2007

As photovoltaic(PV) power generation system becomes more common, it will be necessary to investigate islanding detection method for PV systems. Islanding of PV systems can cause a variety of problems and must be prevented. However, if the real and reactive power of the load and PV system are closely matched, islanding detection by Passive methods becomes difficult. Also, most active methods lose effectiveness when there are several PV systems feeding the same island. The active frequency drift positive feedback method(AFDPF) enables islanding detection by forcing the frequency of the voltage in the island to drift up or down. In this paper the research for the minimum value of chopping fraction gain applied digital phase-locked-loop (DPLL) to AFDPF considering output power quality and islanding prevention performance are performed by simulation and experiment according to IEEE Std 929-2000 islanding test.

• Korean Journal of Health Education and Promotion
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• 제31권5호
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• pp.29-43
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• 2014

Objectives: This study was to develop a reliable and valid instrument measuring the reproductive health promoting behavior of undergraduates. Methods: The initial questionnaires were made of 106 items from four domains through literature review. All questionnaire items were revised by an expert group and a pilot test. Data were collected using the revised initial questionnaire of men's 58 items and female's 64 items from 634 male and 685 female undergraduate students. The collected questionnaires were analyzed by factor analysis using varimax rotation to evaluate the construct validity. Results: According to the gender, two measurement were invented and analysed separately. Four common factors consisting of 'safe sex', 'sexual responsibility', 'genital health management' and 'STD prevention' were discovered in both groups. The 'genital hygiene' factor was added as a female factor. Male students' scale was made up 4 factors 16 items and female students' scale was made up 5 factors 18 items. Cronbach's alpha for male scale was estimated to be .892 and female scale to be .882. Conclusions: This scale will make it possible to measure the level of reproductive health among Korean university students. This scale may be useful for developing effective methods of education as well as policy programs for improving the reproductive health of Korean university students.

• Proceedings of the KIEE Conference
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1684-1686
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• 2005

As photovoltaic(PV) power generation systems become more common, it will be necessary to investigate islanding detection method for PV systems. Islanding of PV systems can cause a variety of problems and must be prevented. However, if the real and reactive power of load and PV system are closely matched, islanding detection by passive methods becomes difficult. Also, most active methods lose effectiveness when there are several PV systems feeding the same island. The active frequency drift positive feedback method(AFDPF) enables islanding detection by forcing the frequency of the voltage in the island to drift up or down. In this paper the research for the minimum value of chopping fraction gain applied digital phase-locked-loop(DPLL) to AFDPF considering output power quality and islanding prevention performance are performed by simulation and experiment in IEEE Std 929-2000 islanding test.

• Proceedings of the KIEE Conference
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1705-1707
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• 2005

This paper proposes a novel active frequency drift(AFD) method for the islanding prevention of grid-connected photovoltaic inverter. To detect the islanding phenomenon of grid-connected photovoltaic(PV) inverters concerning about the safety hazards and the damage to other electric equipments, many kinds of anti-islanding methods have been presented. Among them, AFD method using chopping fraction(cf) enables the islanding detection to drift up(or down) the frequency of the voltage during the islanding situation. However, the performance of the conventional AFD methods, which have a certain value of cf only, is inefficient and difficult to design the appropriate cf value analytically to meet the limit of harmonics. In this paper, the periodic chopping fraction based on an AFD method is proposed. This proposed method shows the analytical design value of cf to meet the test procedure of IEEE Std. 929-2000 with the power quality and islanding detection time. To verify the validation of the proposed method, the islanding test results are presented. It is confirmed that the proposed method has not only less harmonic distortion but also good performance of islanding detection compare with the conventional AFD method.

• Asian Pacific Journal of Cancer Prevention
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• 제13권3호
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• pp.799-802
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• 2012

Background: Human papillomavirus (HPV) is a very common sexually transmitted disease affecting both men and women and is responsible for different ano-genital cancers in either sex. Co-existing sexually transmitted infections (STI) including HIV have been considered as important co-factors for carcinogenesis induced by HPV. The purpose of this study was to determine the prevalence of any HPV, HPV 16 and HPV 18 and also concomitant STIs among female sex workers (FSW), men having sex with men (MSM) and injectable drug users (IDU). Material and Method: This cross-sectional study was conducted among 45 FSWs, 26 MSMs and 58 IDUs who attended the STI or de-addiction clinics. Genital scrape samples collected from glans penis and coronal sulcus in males and cervical squamo-columnar junction in females were tested for HPV DNA by PCR using HPV L1 consensus primer. Type specific PCR to detect HPV 16 and 18 was done on the samples positive on consensus PCR. All participants were tested for associated STIs including HIV and hepatitis B and cervical cytology was done on all females. Results: Among the FSWs, HPV was detected in 73.3% and HPV 16 and 18 was detected in 25.7%. Though the HPV prevalence was similarly high among MSMs (69.2%) and IDUs (72.4%), the prevalence of HPV 16 and 18 was much lower in these groups compared to the FSWs. Prevalence of cervico-vaginal infection with Trichomonas vaginalis and syphilis was significantly higher in the HPV positive women compared to the HPV negative women. There was no statistically significant difference in the prevalence of other STIs among HPV positive and negative women and men. Conclusion: HPV infection is highly prevalent among FSW, MSM and IDUs. Trichomonas vaginalis infection is more frequent in HPV positive women.

• Journal of Hospice and Palliative Care
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• 제4권1호
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• pp.4-13
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• 2001

Purpose : Since the acquired immune deficiency syndrome (AIDS) was first recognized in the United States in the summer of 1981, the number of these patients has been increasing in the world. But do not find out a cure and a vaccine for ARS (5). And so, the best treatment for AIDS is the prevention. People can find out accurate knowledge about AIDS, and they can prevent themselves from AIDS approximately 100%. In this study, we investigate with AIDS knowledge and attitudes in unmarried young men (<24 age) and suggest accurate preventive education for AIDS and good sexual behaviors. Methods : Un-married young soldiers and college students who were not diagnosed as AIDS until June 30, 2000 were included in the study. The study included a total of 923 men. A self evaluation questionnaire, included questions on 36 items(the part of demographic data - 9; the part of knowledge - 20; the part of attitudes - 8), was drawn up by three physicians. The demographic data, AIDS knowledge and attitudes were analyzed by chi-square analysis, and the total score of AIDS knowledge - comparison according to demographic factors and attitudewere analyzed by one-way ANOVA test. Results : In demographic characteristics, as for the first recognized time of AIDS, most of men knew it when they were in their middle school, as for sources of information on AIDS, most of them knew it through the TV-media, and as for the educational need about AIDS, most of them agreed with it. In AIDS knowledge, mean scores were $14.0{\pm}1.8$ (70.3%). Items of the misconceptions concerning AIDS, reported as less than 50% correct answers, were 6 among 20 items (30%). In AIDS attitudes, as for the item about that if I will be an AIDS patient, I will have an AIDS treatment, it showed that the number of men agreed with 759 (82.2%), and as for the item about that I will help for AIDS patient even though I don't know him, it showed that the number of them agreed with 412 (45.8%). In correlation of AIDS knowledge and demographic factors, the mean scores of knowledge of men with higher than college degree were higher than them of others. The mean scores of knowledge of men with total income of family with more than US$1667 were higher than them of others. The mean scores of knowledge of men with sources of information on AIDS through the TV-media were higher than them of others. And the mean scores of knowledge of men with past medical history of STD(sexually transmitted disease) were higher than them of others. Conclusions : The higher the knowledge he has, the lower the possibility of risk and the more positive the attitude he has. And then we think that the education program for AIDS will be included as a regular part of the curriculum in high school, and young men must be effectively educated by it.