• Journal of Power Electronics
• /
• 제16권1호
• /
• pp.173-181
• /
• 2016

In this paper, a new technique for harmonic optimization in cascaded H-bridge 7-level inverters is proposed. The suggested strategy is based on minimizing an objective function which simultaneously optimizes the converter utilization and Total Harmonic Distortion (THD). The Switch Utilization Ratio (SUR) is formulized for both the phase and line-line voltages of a 7-level inverter and is considered in the final objective functions. Based upon the SUR formula, utilization ratio enhancement will reduce the value of feeding DC links, which improves the efficiency and lifetime of the circuit components due to lower voltage stresses and losses. In order to achieve more effective solution in different modulation indices, it is assumed that the DC sources can be altered. Experimental validation is presented based on a three-phase 7-level inverter prototype.

• 기본간호학회지
• /
• 제10권2호
• /
• pp.214-222
• /
• 2003

Purpose: This study was done to investigate sleep patterns and utilization of the charcoal eyepatch In high school students through a survey research. Method: The participants in this study were 80 students in a high school in Seoul. The period of data collection was from July 1, 2002 to 15, 2002. The research instruments used in this study were the measures of sleep and SPSSWIN 10.0 Program was used for data analysis. Result: The students went to bed after 12 p.m., but many of them easily fell asleep within 5 minutes. They woke up quite early at around 4 to 6 o'clock in the morning but remained in bed 1 hour. Satisfaction with their sleep was the response for 38.8% of the students. While 77% napped, they generally did so in the afternoon and 38.8% napped for half an hour. As for quality of sleep, 2.5% of the students could not sleep deeply, and 21.7% woke frequently during sleep. Their sleep environments were calm and comfortable, and they turned off the light when sleeping. The utilization of the charcoal eyepatch was effective for sleep, fatigue and powerlessness in high school students. Conclusion: Utilization of the charcoal eyepatch was effective for sleep in high school students and while the utilization of charcoal is recommended in life, the effect of charcoal must be testified through research.

• 대한전기학회논문지
• /
• 제39권2호
• /
• pp.149-156
• /
• 1990

In DC electric railway systems, the feeding currrnt is not permitted to flow backward in almost all the substations and the pantograph voltages at the regenerating cars rise extremely by the voltage drop of the resistance of the feeder line. In order to prevent the overrise of the pantograph voltage in power regenerating cars, the squeezing circuits for the regenerative current are equipped and this leads to double losses, which are an extra worn-out of the brake-shoes and an ineffective use of regenerative power. In this study, the insertion of resistors in the feeder line system is proposed as a possible method for the effective utilization of the regenerative power in the electric railways. Also it is investigated how the output voltages of substations affect the effective use of regenertive capability. The investigation results show that the energy savings and the reduction of the worn-out of the brake-shoe can be achieved at the same time by the insertion of resistors in the feeder line system.

• 한국IT서비스학회지
• /
• 제10권4호
• /
• pp.149-169
• /
• 2011

As the number of smart phone users increases, many organizations begin to adopt social media rapidly to diversify communication channels with customers. Specifically, twitter, which supports instant and two-way communications between users and between organizations and users, has been adopted by many organizations as an efficient way not only to identify new customers but also to retain existing customers. However, little attention has been given to the issue on how organizations can effectively use twitter to improve customer satisfaction. To explore the issue, this study proposes two major dimensions, customer participation and organization resource utilization, which should be considered in building a utilization strategy for twitter in organizations. We then develop four different combinations along with these dimensions-follow, mention, retweet, and review types. Based on case studies of 27 organizations that use twitter, we evaluate the degrees of customer participation, resource utilization, and customer satisfaction, and examine matching or mismatching of the adoption purpose of twitter and its actual utilization. The study results reveal that organizations in the matching group show higher customer satisfaction that those in the mismatching group. This study sheds new light on twitter research by developing a new conceptual framework and using a case study approach to explore the relationship between the utilization strategy of twitter and customer satisfaction.

• Asian-Australasian Journal of Animal Sciences
• /
• 제16권9호
• /
• pp.1369-1373
• /
• 2003

ACE (Angiotensin-I converting enzyme) inhibitory peptides derived from foods are thought to suppress high blood pressure by inhibiting ACE. We tried to make efficient production of the ACE inhibitory hydrolysate from egg albumen. A hydrolysate digested by neutrase presented the highest ACE inhibitory activity ($IC_50\;value=256.35{\mu}g/ml$) and the proper proteolysis was occurred by 1.0% enzyme addition and 4 h incubation at $47^{\circ}C$. Antihypertensive effect of neutrase hydrolysate was investigated in spontaneously hypertensive rats (SHR, n=5). Systolic blood pressure (SBP) was decrease by 6.88% (-14.14 mmHg, p<0.05) at 3 h after oral administration of 300 mg/kg body weight, and by 13.33% (-27.72 mmHg, p<0.05) by emulsified hydrolysate. These results showed that it is very effective to utilize egg albumen as a protein source for the production of ACE inhibitory peptides. However, further studies are required to investigate the methods to increase recovery yield and the isolation of active peptide is necessary for determining its sequence responsible for ACE inhibitory activity.

• 한국측량학회지
• /
• 제30권4호
• /
• pp.369-377
• /
• 2012

최근 IT기술의 발달과 공간정보기술의 고도화는 방재분야에 있어서 효과적인 피해조사 기술 개발의 필요성을 증대시키고 있다. 자연재해에 효과적으로 대응하고, 복구계획을 수립하기 위해서는 신속한 피해조사가 필요하며, 이러한 점에서 UAV는 신속한 피해조사를 위한 유용한 수단이 될 수 있다. 본 연구에서는 효율적인 자연재해 피해조사를 위한 UAV 기반 실시간 공중자료획득시스템의 활용성을 평가하고자 하였다. 시스템의 적용성 평가를 위해 정확도 분석을 수행하였으며, 국내 규정을 바탕으로 재난 유형을 구분하여 재해 유형별로 시스템을 적용한 피해조사의 활용성을 평가하였다. 연구 결과, 주택피해, 농경지 및 농림시설 피해, 공공시설 피해 등의 피해조사가 가능하였다. 향후 다양한 자연재해 현장을 대상으로 실시간공중자료획득시스템을 통해 취득된 영상자료를 활용함으로써 효율적인 자연재해 피해조사 및 복구계획 수립이 가능할 것이다.

• 가족자원경영과 정책
• /
• 제9권1호
• /
• pp.131-146
• /
• 2005

The farming type in Korea is predominantly a small farm managed by family members. This study mainly examines the current usage of the website of family farms as a management tool for small farm business and discusses the strategies for effective utilization of the website. A county that currently employs governmental project of information system was purposely selected. Among all the websites operated by small farm businesses in that county, websites of which purpose is introduction of the business, advertisement, or e-business were included for analysis; it yielded total seven websites, The study was conducted with two phases; on-line website analysis and interview with business owners. The websites were analyzed based on four categories; content, interface, design, and site management. With regard to the content of the websites, the lack of connection between domain names and product names was found. Moreover, the problem relevant to site management was shown as low utilization of bulletin boards and delayed upload of new information. However, design and interface were comparatively well presented. Business owners reported that the motivation to initiate the websites was mostly supports from the governmental project for the agricultural information system. The barriers to effective management of websites were found i) business owner's misinterpretation of business website with e-business ii) very limited opportunity for website management education in small farm business, and iii) lack of regional infrastructure for information system. Based on the findings, this study suggests as followed; i) construction of infrastructure should be preceded to make effective management for websites; ii) education for website management should include small business management strategies as well as computer skills, iii) the education should be provided in diverse ways considering subject's characteristics iv) small farm business owners should be informed that their websites could play a role only to provide information about the products and hand over the practical load for e-business to retailing web sites such as portal shopping mall; and v) wives' participation should be encouraged.

• Journal of Preventive Medicine and Public Health
• /
• 제21권2호
• /
• pp.419-430
• /
• 1988

This study was performed in a rural community, Kanghwa county which was introduced to a regional medical insurance pilot program in 1982. The purposes of this study were, firstly, to observe the changes in ambulatory care utilization in the three years 1982, 1983 and 1987 : secondly, to analyse factors which convert perceived medical care needs to effective medical care demand. During the three periods, a serial interview survey was performed to determine the changes in medical utilization before and after the regional medical insurance program implementation. The number of subjects was 3,356 persons in the year 1982, 3,705 in 1983 and 2,745 in 1987. The results of the study were as follows : 1. Total ambulatory care utilization rates per 100 persons during a 2-week period were 23.6 in the year 1982, 21.8 in 1983, and 29.3 in 1987; and physician visit rates were 6.1 in 1982, 11.7 in 1983, and 14.9 in 1987. Thus, compared to the total utilization rate there was a definite increase in physician visit, and during the study periods there was a decrease in drug store visits whereas an increase in hospital or clinic visits was noticed. 2. The rates of effective demand for medical care need were 70.7% in 1982, 70.5% in 1983 and 75.9% in 1987 : and the rates of patients who visited physicians were 20.2% in 1982, 42.8% in 1983 and 35.6% in 1987. Thus, physician visits increased sharply by introducing the medical insurance program, but after the latent medical care demands were fulfilled, there was a slight decrease in the physician visits. 3. The number of acute symptoms and the number of chronic symptoms were common determinants of total ambulatory care utilization and physician visits. Besides the medical care need factors, age in 1982, sex and accessibility in 1983, and accessibility in 1987 were statistically significant determinants of the total utilization ; sex and accessibility in 1983, and education in 1987 were also statistically significant determinants of the physician visit. 4. For persons with perceived acute symptoms during the 2-week periods, accessibility in total utilization and age in physician visits were common discriminating factors of ambulatory care utilization in the three years, and education and income were also statistically significant variables. For persons with perceived chronic symptoms, occupation and income were statistically significant discriminating variables commonly observed in total utilization and physician visits.

• 기술혁신학회지
• /
• 제19권2호
• /
• pp.358-394
• /
• 2016

이 연구는 연구장비 공동활용 정책의 꾸준한 시행에도 불구하고 저조한 공동활용의 원인이 정책집행이 현장관료 또는 정책대상자의 입장에서가 아니라 정책결정자의 시각에서 이루어져 왔다는 문제의식에서 시작하고 있다. 따라서 이 연구는 정책집행의 상향적 접근법에서 기초연구사업을 수행하는 현장 연구자들과 장비 관리자들을 대상으로 연구장비 공동활용의 현황을 분석하였다. 분석결과는 공동활용에 대한 연구 책임자들의 중요성 인식이 여전히 낮은 편이며, 실제의 공동활용 과정에서는 필요한 집행자원이 부족하며, 공동활용의 지속성을 확보하기 위한 일상적인 관리단계에서의 유인책도 충분하지 못한 것으로 나타나고 있다. 이에 따라 기초연구사업에서의 연구장비 공동활용을 증진하기 위한 정책대안을 관리단계별로 정책집행의 상향적 관점에서 유인도구와 정보도구 중심의 정책수단 도구들을 개발 논의하고자 노력하였다.

• 기술사
• /
• 제32권1호
• /
• pp.90-98
• /
• 1999