• Journal of Power Electronics
• /
• v.11 no.3
• /
• pp.360-368
• /
• 2011

This paper proposes an active frequency with a positive feedback in the d-q frame anti-islanding method suitable for a robust phase-locked loop (PLL) algorithm using the FFT concept. In general, PLL algorithms for grid-connected PV PCS use d-q transformation and controllers to make zero an imaginary part of the transformed voltage vector. In a real grid system, the grid voltage is not ideal. It may be unbalanced, noisy and have many harmonics. For these reasons, the d-q transformed components do not have a pure DC component. The controller tuning of a PLL algorithm is difficult. The proposed PLL algorithm using the FFT concept can use the strong noise cancelation characteristics of a FFT algorithm without a PI controller. Therefore, the proposed PLL algorithm has no gain-tuning of a PI controller, and it is hardly influenced by voltage drops, phase step changes and harmonics. Islanding prediction is a necessary feature of inverter-based photovoltaic (PV) systems in order to meet the stringent standard requirements for interconnection with an electrical grid. Both passive and active anti-islanding methods exist. Typically, active methods modify a given parameter, which also affects the shape and quality of the grid injected current. In this paper, the active anti-islanding algorithm for a grid-connected PV PCS uses positive feedback control in the d-q frame. The proposed PLL and anti-islanding algorithm are implemented for a 250kW PV PCS. This system has four DC/DC converters each with a 25kW power rating. This is only one-third of the total system power. The experimental results show that the proposed PLL, anti-islanding method and topology demonstrate good performance in a 250kW PV PCS.

• Journal of the Korean Institute of Gas
• /
• v.13 no.6
• /
• pp.15-20
• /
• 2009

The number of compressed natural gas (CNG) vehicles have increased gradually by virtue of korea government's urban air quality improvement policy since 1998. Although the use of CNG as transportation fuel gives environmental benefits, there is a possibility of huge accidents from unexpected fire. Therefore, needs for the guarantee of safety are indispensible for the reliable operation of CNG vehicles. A check valve is a safety device which prevents leakage of the pressurized fuel charged in a fuel tank. Durability of this component should be guaranteed in spite of repeated operation. This research has performed durability tests of a CNG check valve regarding the repeated usage, extreme chattering, and the effect of compressor oil.Although a check valve used for CNG vehicle satisfies validation requirements in the test results, it has been found that problem in the function of leakage prevention in a check valve could take place in the case of prolonged exposure to compressor oil.

• Journal of the Korea Institute of Building Construction
• /
• v.10 no.2
• /
• pp.105-113
• /
• 2010

Method or work type improvement is needed in relation to reducing cost and increasing efficiency by ensuring construction quality and reducing labor in the form work process. This would have a great influence on the entire construction process, and make the process of adopting materials and methods more rational and economic. Hence, this study aimed to develop a Synthetic Resins Euroform that could improve durability, water-proofing, sophistication, and organizational unity through the use of injection modeling. Accordingly, this paper first investigated various performance requirements and necessary techniques, and then verified feasibility by evaluating the physical safety and technical validity when it is applied to construction field. In addition, this study evaluated the constructability, safety performance, environmental performance, and systemic excellence in terms of maintaining convenience of Synthetic Resins Euroform. Moreover, to verify feasibility in the construction field, this study analyzed and evaluated the maximum stress by measuring the load and deformation of the space of the horizontal furring, which is attached to Euroform as an armature.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.4
• /
• pp.483-491
• /
• 2011

The fabrication of steel structural members always involves welding process such as flux cored arc welding. Therefore, for the application of structural steels to cold regions, it is a prerequisite to clarify the service temperature of the welded joints in order to ensure the structural integrity of the welded parts. In this study, the Charpy impact test was conducted to evaluate the service temperature of structural steel weld. The Charpy impact test is a commercial quality control test for steels and other alloys used in the construction of metallic structures. The test allows the material properties for service conditions to be determined experimentally in a simple manner with a very low cost. Standard V-notch Charpy specimens were prepared and tested under dynamic loading condition. The service temperatures of the weld metal, HAZ (heat affected zone) and base metal were derived by the absorbed energy and the impact test requirements; thus the applicability of the structural steels to cold regions was discussed in detail.

• The Korean Journal of Health Service Management
• /
• v.6 no.4
• /
• pp.61-72
• /
• 2012

The purpose of this study was to propose how to improve and develop the college curriculum of medical record administration, satisfying requirements from hospitals having medical record administrators. For the purpose, this researcher surveyed medical record administrators serving at hospitals located in Busan, Changwon, Masan and Jinju. Finally analyzed were responses from 100 medical recorders. The frequency of searching medical records to support information use was statistically different among hospitals according to the number of sick beds(p=.041), or $3.16{\pm}1.75$ for fewer than 300 sick beds, $4.28{\pm}2.42$ for 300 to 500 and $4.86{\pm}3.18$ for more than 500. The college course that was regarded as most important by most of the surveyed medical record administrators, or 53(37.2%) was medical terminology, followed by statistics by 36 of the respondents(18.5%) and EMR, 25(12.8%) in order. To make EMR truly effective requires reforming the university curriculum of medical record administration and giving more attention and more supports to training for better computerization, realizing that medical record administrators serve as a true manager of health and medical information, not a person who just paper-based medical information. In addition to managing health and medical information, medical record administrators are expected to have more roles in the future, for example, providing high-quality clinic knowledge and medical information that are necessary for efficient hospital management and medical research to survive competition.

• Journal of the Korean Society for Library and Information Science
• /
• v.42 no.4
• /
• pp.269-290
• /
• 2008

The aim of this research was to find ways to improve the overall school library management quality and also to help finding solutions to the school library related problems, which could have not been dealt by the individual schools. To achieve the research goal, we analyzed the domestic and foreign cases of the government led supports for the school libraries as well as collaborations between the school libraries and other organizations. We surveyed the principals about the school library operating policies, current status, and requirements as the principals have influence over how the school libraries are managed. One of the findings of the research was that the survey respondents devote their efforts in the collection development but they also required training of the school library staffs. In comparison to the metropolitan and rural areas, the school libraries in the middle to small cities experienced variety of problems in all aspects of their operations. In addition, the middle to small city school libraries had high expectation on the government supports.

• Journal of KIISE:Software and Applications
• /
• v.26 no.11
• /
• pp.1282-1287
• /
• 1999

통신 프로그램은 고도의 신뢰성과 기능성, 확장성, 그리고 유지 보수성이 필요하다. 프로그램 테스트의 결과와 McCabe의 Complexity를 측정한 데이타를 가지고 회귀모델을 만들고 그 신뢰성을 분석함으로서 프로그램의 결함과 복잡도의 관련성을 평가한다.본 연구에서 사용한 통신 프로그램은 500개 블록이 59가지 기능을 수행하는 교환 기능 중에서 복잡도가 너무 많아서 통계 처리의 bias가 될 블록을 제외하고 394 블록을 선정하여 SAS에 의해서 통계 분석을 하고 회귀 분석 모델을 설계하였다. t 분포에 의하여 방정식의 유의성 수준을 검증하고 프로그램의 결함수에 가장 큰 영향을 주고 있는 복잡도가 McCabe의 복잡도와 설계 복잡도 임을 밝혀냈다. 이 연구 결과에 의해서 설계 정보 및 유지 보수 정보를 얻을 수 있다. Abstract Switching software requires high reliability, functionality, extendability and maintainability. For doing, software quality model based on MaCabe's complexity measure is investigated. It is experimentally shown using regression analysis the program fault density depends on the complexity and size of the function unit. The software should be verified and tested if it satisfies its requirements with automated analysis tools. In this paper we propose the regression model with the test data.The sample program for the regression model consists of more than 500 blocks, where each block compose of 10 files, which has 59 functions of switching activity.Among them we choose 394 blocks and analyzed for 59 functions by testing tools and SAS package. We developed Regression Analysis Model and evaluated significant of the equation based on McCabe's cyclomatic complexity, block design complexity, design complexity, and integration complexity.The results of our experimental study are that number of fault are under the influence of McCabe's complexity number and design complexity.

• Korean Journal of Construction Engineering and Management
• /
• v.9 no.3
• /
• pp.126-135
• /
• 2008

The purpose of this study is to develop the efficient information system for managing owner's requirement(O/R) throughout the design phases. In order to derive an improvement, current status of O/R management both in domestic and foreign design company has been analyzed. Through the literature reviews and interviews with experts, the Information on design process and detailed activities were investigated. Based on the basic research, inputs, outputs and participants were defined and information flow diagram was drawn. O/R's were categorized according to comprehensive interviews with specialists, and a prototype system was suggested. Conducting systematized O/R management will improve the confidence of owners' role on design, reduce re-work in design tasks, and finally elevate design quality.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2019.10a
• /
• pp.87-87
• /
• 2019

The consumption of herbal medicine and related products (herbal products) have increased in South Korea. At the same time the quality, safety, and efficacy of herbal products is being raised. Currently, the herbal products are standardized and controlled according to the requirements of the Korean Pharmacopoeia, the National Institute of Health and the Ministry of Public Health and Social Affairs. The validation of herbal products and their medicinal component is important, since many of these herbal products are composed of two or more medicinal plants. However, there are no tools to support the validation process. Interest in deep learning has exploded over the past decade, for herbal medicine using algorithms to achieve herb recognition, symptom related target prediction, and drug repositioning have been reported. In this study, individual images of four herbs (Panax ginseng C.A. Meyer, Atractylodes macrocephala Koidz, Poria cocos Wolf, Glycyrrhiza uralensis Fischer), actually sold in the market, were achieved. Certain image preprocessing steps such as noise reduction and resize were formatted. After the features are optimized, we applied GoogLeNet_Inception v4 model for herb image recognition. Experimental results show that our method achieved test accuracy of 95%. However, there are two limitations in the current study. Firstly, due to the relatively small data collection (100 images), the training loss is much lower than validation loss which possess overfitting problem. Secondly, herbal products are mostly in a mixture, the applied method cannot be reliable to detect a single herb from a mixture. Thus, further large data collection and improved object detection is needed for better classification.

• Journal of Korean Clinical Nursing Research
• /
• v.17 no.3
• /
• pp.349-362
• /
• 2011

Purpose: The purpose for this study was to identify the present working status and tasks of nurse administrators in response to requirements of expanding nurses' roles in hospitals. Methods: The design of the study was descriptive-exploratory. The participants were 338 registered nurses who were working in hospital administrative departments. The data were collected from January 17, to March 20, 2011, and analyzed with descriptive statistics. Results: The majority of nurse administrators worked in quality assurance departments while no nurse administrators assigned in finance/taxation departments. Duties of nurse administrators were developed as 117 tasks in 11 divisions. Conclusion: These results suggest that expanding nurses' roles require developing job descriptions, nursing curricula emphasizing hospital administration, positive relationships with other health professions and a supportive system.