• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.174-177
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• 2001

The dependence of modern life upon the continuous supply of electrical energy makes system reliability and power quality topics of the utmost importance in the power systems. Power quality is the combination of voltage quality and current quality. But in this paper, voltage quality and harmonic distortion are focused. Transient phenomena and current quality are not included. Voltage quality is split into voltage sags. voltage swells, and short interruptions. These voltage variations are studied on their definitions, origins, the effect on electric equipment. Related industrial standards and guidelines are summarized. Harmonic voltage and current distortion are strongly linked. The concepts and contributions of harmonic distortions are studied. Typical symptoms of harmonic problems and a summary of the trends and guidelines are given.

• Clinics in Shoulder and Elbow
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• v.25 no.3
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• pp.244-254
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• 2022

Radiographic osteolysis after total shoulder arthroplasty (TSA) remains a challenging clinical entity, as it may not initially manifest clinically apparent symptoms but can lead to clinically important complications, such as aseptic loosening. A thorough consideration of medical history and physical examination is essential to rule out other causes of symptomatic TSA-namely, periprosthetic joint infection-as symptoms often progress to vague pain or discomfort due to subtle component loosening. Once confirmed, nonoperative treatment of osteolysis should first be pursued given the potential to avoid surgery-associated risks. If needed, the current surgical options include glenoid polyethylene revision and conversion to reverse shoulder arthroplasty. The current article provides a comprehensive review of the evaluation and management of osteolysis after TSA through an evidence-based discussion of current concepts.

• Clinics in Shoulder and Elbow
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• v.24 no.3
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• pp.189-198
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• 2021

Midshaft clavicle fractures are the most common fracture of the clavicle accounting for 80% of all clavicle fractures. Traditionally, midshaft clavicle fractures are treated with conservative treatment even when prominent displacement is observed; however, recent studies revealed that nonunion or malunion rate may be higher with conservative treatment. Moreover, recent studies have shown better functional results and patient satisfaction with surgical treatment. This review article provides a review of clavicle anatomy, describes the current clavicle fracture classification system, and outlines various treatment options including current surgical options for clavicle fracture in adults.

• Journal of Trauma and Injury
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• v.36 no.4
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• pp.315-321
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• 2023

Pediatric carpal fractures are rare and often difficult to detect. This paper reviews the current literature on pediatric non-scaphoid carpal fractures, with a case report of a lunate fracture associated with a distal radius and ulnar styloid fracture, managed nonoperatively in a 12-year-old boy. There is lack of consensus regarding the management of these fractures due to the low number of reported cases. A frequent lack of long-term follow-up limits our understanding of the outcomes, but good outcomes have been reported for both nonoperative and operative management. This case report brings attention to the current time period for the definition of delayed union in pediatric carpal fractures, and emphasizes the need for prolonged follow-up for the detection of delayed complications leading to functional impairment.

• Journal of Educational Research in Mathematics
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• v.18 no.3
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• pp.407-434
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• 2008

This research is to analyze the descriptions in the statistic chapter of the grade 7's current textbooks. The analysis is based on the distribution concepts suggested by Nam(2007). Thus we assumed that the goal of this statistic chapter is to establish concepts on the distributions and to learn ways of communication and comparison through distributional presentations. What we learned and wanted to suggest through the study is the followings. 1) Students are to learn what the distribution is and what are not. 2) Every kinds of presentational form of distributions is to given its own right to learn so that students are more encouraged to learn them and use them more adequately. 3) Density histogram is to be introduced to extend student's experiences viewing an area as 3 relative frequency, which is later to be progressed into a probability density. 4) Comparison of two distributions, especially through frequency polygons, is to be an hot issue among educational stakeholder whether to include or not. It is very important when stochastic correlations be learned, because it is nothing but a comparison between conditional distributions. 5) Statistical literacy is also an important issue for student's daily life. Especially the process ahead of the data collection must be introduced so that students acknowledge the importance of accurate and object-oriented data.

• Journal of Korean Elementary Science Education
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• v.41 no.2
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• pp.186-198
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• 2022

With the science curriculum about to be revised in 2022, this study aimed to guide curriculum revision by addressing suggested approaches to the electromagnetism education in elementary school science curriculum. The core concepts of electromagnetism are "electric field" and "magnetic field" as a medium of force, but the current curriculum does not properly describe the core concepts of electromagnetism. Mechanics and electromagnetism should be linked in elementary schools to form science curriculum based on core concepts to solve this problem. Additionally, the nine aspects of technology extracted in this study offer various educational contexts to match the development of engineering technology based on electromagnetism. However, the current curriculum does not comprise these various contexts and focuses on the limited content of electric circuits using light bulbs. Therefore, it is necessary to expand the scope of the curriculum to better mirror real-life technology. Through the use of more diverse materials and contexts, the scope and level of STS education as well as conceptual learning could be expanded. Finally, in the case of electric circuit learning, various issues such as difficulty in connecting electric circuits and electric field concepts, representativeness of electric circuit, students' learning difficulty, and phenomena-oriented learning should be considered.

• Journal of Environmental Policy
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• v.3 no.2
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• pp.113-137
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• 2004

The objective of this study is to introduce the definitions and classification methods of wastes in international agreements and legislations, examine the concept of wastes and their classification systems in Korea, and finally analyze and compare the concept of wastes in different countries for finding better solutions and suggestions. The study summarizes the concept of wastes as introduced in the Basel Convention, OECD, EU, US, and UK. First, each of the member countries adapt to the same concepts of wastes as defined in their international agreements; second, the intention of the wastes holder and the conditions of the wastes are considered at the same time when defining the concepts. Upon close examination of the classification of wastes systems as introduced in the Basel Convention, OECD, EU, US, and UK, the wastes are classified into toxic and non-toxic wastes according to the existence of poisonous substances. Therefore, it is classified as a toxic waste when any toxic substance on its list is included in the waste, while others are considered as a non-toxic waste if they don't contain poisonous substances. Secondly, in the UK, the matter of toxic or non-toxic wastes are classified, not according to the existence of the poisonous substances, but based on the generation of sources. In Korea, the concepts of wastes are divided into the two categories - a concept as defined in actual legislations and a concept in its translation. The Korean classification of the wastes include Wastes Management Act, amended in 1995, which stipulates that toxic substances should be managed in a special way as the designated wastes. It appears that the Act utilizes the classification method that classifies the wastes according to the existence of poisonous substance. Korea's concepts of wastes should be changed after recognition of the concepts in international agreement (Basel Convention, EU) and other foreign laws(US, UK) that consider subjective and objective standards at the same time when they define the concepts. Also, the development of technology in recycling and reuse of the wastes can remove the current absolute notion of the wastes so that it also should not be passed over. Also, because a classification structure of wastes has a close relationship with a disposal structure, its classification system should be fixed gradually to come up with the development of wastes disposal technology and its policy.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.779-784
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• 2001

For electrical vehicles, switched reluctance drives present a promising alternative-compared to asynchronous and synchronous (permanent magnet) concepts. For these applications, a very wide field weakening range is a key issue. Other requirements include high torque output from a small machine and low current ripple at the DC-side without the use of bulky filters - when powered from fuel cells or advanced Lithium-Ion-batteries. A new converter and control strategy according to these requirements is presented and compared to existing designs. The comparison is done for a drive system with a continuous power rating of 30 to 40 kW.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.421-426
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• 1998

Current code provisions for the development of positive moment reinforcement is reviewed and criticized in this paper. Both the flexural bond and development length concepts are neccesary to consider anchorage requirement of reinforcement at beam ends. The curent design codes show unconservatism for the detailing of reinforcement at the beam ends. This study proposes a new design formula for the development of positive moment reinforcement.

• Journal of the Korean Arthroscopy Society
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• v.9 no.2
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• pp.93-101
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• 2005

일반적으로 전방 십자인대 손상의 치료만큼 관심과 논쟁의 대상이 되는 분야도 드문 것으로 알려져 있다. 치료 방법으로는 과거에는 보존적 요법이나 일차 수복술, 관절외 재건술 등이 시행되었으나, 근래에는 관절경하에 재건술이 가장 보편화되고 선호되는 방법으로 발전되어 왔다. 현재까지 400개 이상의 전방십자인대 재건술의 방법이 문헌상 발표되고 있으나 아직까지도 이상적인 방법은 없는 것으로 알려져 있다. 재건술의 성공을 위하여 환자의 선택, 수술시기, 수술방법 재건술의 기본원칙에 대한 이해 등이 중요한 요인으로 인정되며, 이에 대한 문헌고찰과 최근경향 등에 대하여 논하고자 한다.