• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.54 no.5
• /
• pp.245-252
• /
• 2005

The fuel cell systems are one of very useful energy sources. The systems have advantages as renewable and environmental sources. To obtain AC components from fuel cells, it needs inverters. A multilevel converter is used as a power conversion system for a high power fuel cell system. Through harmonic analysis, it is shown that the harmonic components and THD increase while a fundamental component of output decreases as voltage droop increases. To solve the voltage disturbance problems, three different approaches are investigated in this paper; installation of a boost converter at the fuel cell output, control of pulse widths, and use of ultracapacitors. The proposed three approaches are analyzed and compared through simulation and experimental results.

• Journal of Korean Institute of Industrial Engineers
• /
• v.39 no.5
• /
• pp.351-360
• /
• 2013

Taguchi's robust design is a method for quality improvement by making a system insensitive to uncontrollable variations incurred by noise factors and it has received much attention in a wide range of engineering fields. Robust design can be broadly classified into static and dynamic ones. This paper is concerned with dynamic robust design. Taguchi suggested to use a signal-to-noise ratio as a robustness measure, but there has been much debate and criticism on its blind use. In order to cope with this drawback, many alternatives have been proposed. They are divided into performance measure modeling (PMM) and response function modeling (RFM) approaches. In this paper, both PMM and RFM approaches for dynamic robust design are reviewed. An example for illustration is provided as well.

• Journal of Communications and Networks
• /
• v.1 no.2
• /
• pp.118-133
• /
• 1999

In this paper we compare linear and non-linear inter-ference cancellation for systems employing code division multi-ple access (CDMA) techniques. Specifically, we examine linear and non-linear parallel interference cancellation(also called multi-stage cancellation) in relationship to other multiuser detection al-gorithms. We show the explicit relationship between parallel inter-ference cancellation and the decorrelator (or direct matrix inver-sion). This comparison gives insight into the performance of paral-lel interference cancellation (PIC) and leads to vetter approaches. We also show that non-linear PIC approaches with explicit chan-nel setimation can provide performance improvement over linear PIC, especially when using soft non-linear symbol estimates. The application of interference cancellation to non-linear modulation techniques is also presented along with a discussion on minimum mean-squared error(MMSE) symbol estimation techniques. These are shown to further improve the performance of parallel cancella-tion.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.12
• /
• pp.2503-2510
• /
• 2002

Since the first shape-form-shading technique was developed by Horn in the early 1970s, many different approaches have been continuously emerging in the past three decades. Some of them improve existing techniques, while others are completely new approaches. Using the image reflectance equation, they estimate the 3-D shape of an object utilizing adequate constraints. Each algorithm applies different constraints such as brightness, smoothness, and integrability to solve the shape-from-shading problem. Especially for symmetric objects, a symmetry constraint is proposed to improve the performance of existing shape-from-shading algorithm in this paper. The symmetry constraint is imposed to a conventional algorithm and then the improvement in the performance of 3-D shape reconstruction is proved by quantitatively comparing the depth and gradient errors.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.12 no.sup1
• /
• pp.118-126
• /
• 2009

The incidence of childhood obesity has increased dramatically. Childhood obesity is an increasing health problem because of its strong associations with chronic health problems in children and adults. These health problems significantly contribute to the development of common chronic diseases in later life, including hypertension, type2 diabetes, hyperinsulinemia, coronary heart disease, and other psychological disorders. So it is an important issue to prevent and treat obesity during childhood and adolescent. Diet and exercise are the cornerstones of treatment for obesity and related complications. For obese children, some clinical trials have shown improvement with diet, exercise, and /or behavioral interventions. Promising interventions for high-risk individuals, such as bariatric surgery and novel pharmacological agents, also require rigorous assessment with attention to long-term patient important outcomes. There are various pharmacological approaches to the treatment of obesity in the adolescent population some of which have FDA approval. In the article we discuss pharmacological approaches to guide the treatment of obesity in the pediatric population, including risks of treatment, monitoring of potential side effects.

• Journal of Animal Reproduction and Biotechnology
• /
• v.36 no.3
• /
• pp.162-167
• /
• 2021

Camel (camelus dromedarius) is a unique large mammalian species that can survive harsh environmental conditions and produce milk, meat, and wool. Camel reproduction is inferior when compared to other farm animal species such as cattle and sheep. Several trials have been reported to increase camel reproduction and production through assisted reproductive techniques (ARTs) such as in vitro fertilization and cloning. For these reasons, obtaining enough mature oocytes is a cornerstone for ARTs. This demand would be improved by the oocyte in vitro maturation (IVM) systems. In this review, the current approaches and views from different laboratories using ARTs and the IVM to produce embryos in vitro in camel species. For the last two decades, conventional IVM system was the common approach, however, recently the bi-phasic IVM system has been introduced and showed promising improvement in IVM of camel oocytes. Detailed studies are needed to understand camel meiosis and IVM to efficiently increase the production of this species.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.821-826
• /
• 2009

Current construction simulation approaches mostly focus on operation aspects of construction projects, ignoring managerial aspects which can radically change operational profiles (e.g., number of resources, expected productivity level, or daily working hours) during the course of construction. As a result, these approaches may mislead construction managers into unrealistic execution plans as well as make them difficult to find potential performance improvement areas. As an effort to address this issue, this paper establishes a comprehensive construction modeling framework which integrates operational and managerial aspects of construction projects. The proposed modeling framework will provide construction managers with more accurate, more reliable, and more realistic simulation results thus reducing the likelihoods of schedule delays and cost overruns.

• Journal of Hospice and Palliative Care
• /
• v.27 no.2
• /
• pp.77-81
• /
• 2024

This case report explores the challenges and complexities associated with opioid management of cancer pain, emphasizing the importance of early involvement of a hospice consultation team and the adoption of a multidisciplinary approach to care. A 56-year-old man with advanced pancreatic cancer experienced escalating pain and inappropriate opioid prescriptions, highlighting the shortcomings of traditional pain management approaches. Despite procedural intervention by the attending physician and increased opioid dosages, the patient's condition deteriorated. Subsequently, the involvement of a hospice consultation team, in conjunction with collaborative psychiatric care, led to an overall improvement. The case underscores the necessity of early hospice engagement, psychosocial assessments, and collaborative approaches in the optimization of patient-centered palliative care.

• Quality Improvement in Health Care
• /
• v.29 no.2
• /
• pp.47-63
• /
• 2023

Purpose:This study aims to suggest the future direction for applying service design to improve the quality of healthcare as part of hospital service innovation and present implementation plans in Korea, based on a review of quality improvement activities and the current status of service design applications. Methods: Through a literature review, we examined the status of service design introduction and application in the healthcare field, focusing on cases in the US and Europe. The possibility and limitations of service design in the healthcare field were examined through a comparison of oversea and domestic cases. Results: Recently, service design has begun to be applied to the healthcare field worldwide. Service design shows the possibility of an alternative that alleviates and complements the limitations of existing quality improvement activities. It also offers the possibility of creating new organizational improvement and innovation approaches through integration and convergence with existing quality improvement activities and management innovation. Conclusion: To effectively apply service design to hospitals, it is necessary to integrate internal organizations related to service improvement, combine methods, and objectively measure and evaluate performance. To this end, we propose the operation of a nationwide education and training center for quality improvement and service design led by academic society. Service design will provide an opportunity to change the management innovation and organizational culture of hospitals beyond the scope of the current quality improvement, which deals only with micro-subjects of individual hospitals.

• Nuclear Engineering and Technology
• /
• v.50 no.4
• /
• pp.589-598
• /
• 2018

To maintain safety and reliability of reactors, redundant sensors are usually used to measure critical variables and estimate their averaged time-dependency. Nonhealthy sensors can badly influence the estimation result of the process variable. Since online condition monitoring was introduced, the online cross-calibration method has been widely used to detect any anomaly of sensor readings among the redundant group. The cross-calibration method has four main averaging techniques: simple averaging, band averaging, weighted averaging, and parity space averaging (PSA). PSA is used to weigh redundant signals based on their error bounds and their band consistency. Using the consistency weighting factor (C), PSA assigns more weight to consistent signals that have shared bands, based on how many bands they share, and gives inconsistent signals of very low weight. In this article, three approaches are introduced for improving the PSA technique: the first is to add another consistency factor, so called trend consistency (TC), to include a consideration of the preserving of any characteristic edge that reflects the behavior of equipment/component measured by the process parameter; the second approach proposes replacing the error bound/accuracy based weighting factor ($W^a$) with a weighting factor based on the Euclidean distance ($W^d$), and the third approach proposes applying $W^d$, TC, and C, all together. Cold neutron source data sets of four redundant hydrogen pressure transmitters from a research reactor were used to perform the validation and verification. Results showed that the second and third modified approaches lead to reasonable improvement of the PSA technique. All approaches implemented in this study were similar in that they have the capability to (1) identify and isolate a drifted sensor that should undergo calibration, (2) identify a faulty sensor/s due to long and continuous missing data range, and (3) identify a healthy sensor.